IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2020-06-05T13:37:16ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2018-01-24T12:17:41Z2018-01-24T12:17:41Zhttp://eprints.imtlucca.it/id/eprint/3887This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38872018-01-24T12:17:41ZThe co-evolution of cooperation and defection under local interaction and endogenous network formationThe Prisoner’s Dilemma is a typical structure of interaction in human societies. In spite of a long tradition dealing with the matter from different perspectives, the emergence of cooperation or defection still remains a controversial issue from both an empirical and a theoretical point of view. In this paper we propose a local interaction model with endogenous network formation, in the attempt to provide a reasonable account of emerging behaviors. A population of boundedly rational agents repeatedly chooses to cooperate or defect. Each agent’s action affects only her interacting mates, according to a network of relationships. Agents are randomly given the possibility to substitute undesired mates with unknown ones. Full cooperation, full defection and coexistence of both cooperation and defection in homogeneous clusters are possible outcomes of the model. Computer-based simulations are applied to investigate under what circumstances either case is most likely.Ennio Bilanciniennio.bilancini@imtlucca.itLeonardo Boncinelli2018-01-24T10:04:08Z2018-01-24T10:04:08Zhttp://eprints.imtlucca.it/id/eprint/3868This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38682018-01-24T10:04:08ZDistribution of Agricultural Surplus and Industrial TakeoffThis paper analyses how the distribution of agricultural product between landlords and peasants affects both industrial takeoff and aggregate income through the demand side. Using a model that builds on Murphy et al. (1989), we find that the relationship between peasants' share of agricultural product and aggregate income is either non-monotonic or positive. This induces a relationship between aggregate income and the degree of inequality which is negative under industrialization but can be either positive or negative when industrialization is absent. We also prove that, in contrast with Murphy et al. (1989), in order for industrialization to take place a middle class of land- and firm-owners is not required: if peasants' share of agricultural product is large enough, then the buying power of workers of both agricultural and manufacturing sectors is sufficient to trigger industrializationEnnio Bilanciniennio.bilancini@imtlucca.itS. D'Alessandro2017-09-29T08:54:43Z2017-09-29T08:54:43Zhttp://eprints.imtlucca.it/id/eprint/3820This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38202017-09-29T08:54:43ZCurrent Density Simulations in the Electrodeposition from Ionic Liquids: Effects of the Conductivity.The overall goal of this work is the
use of COMSOL Multiphysics in the modelling
of the current density distributions for the
electrodeposition of Aluminium coatings from
Ionic Liquids. The local current distribution is
strongly dependant on the conductivity and on
the geometry of the galvanic cell and can only be
performed by the numerical solution of the
PDE’s governing the system. The ability to
predict the local current density on an electrode
is crucial to eventually evidence portions where
the deposition may be invalidate.I. PerissiClaudia Borriclaudia.borri@imtlucca.itStefano CaporaliAlessandro Lavacchi2017-09-29T08:52:40Z2017-09-29T08:52:40Zhttp://eprints.imtlucca.it/id/eprint/3821This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38212017-09-29T08:52:40ZFinite element analysis of thermal fatigue in thermal barrier coatings (TBC)A Finite element model of plasma sprayed
TBC’s was developed to estimate the stress
induced by thermal cycling experiments. A heat
transfer analysis was performed to evaluate the
temperature distribution on the specimen during the cooling under an impinging air jet; temperature measurements performed with an infrared pyrometer on the cooled samples show good agreement with the evaluated data. These results were then integrated in a structural
mechanic model as thermal load. The COMSOL Multiphysics® Thermal-Structural interaction model allowed to determine the dependence of the stress on the temperature fieldsClaudia Borriclaudia.borri@imtlucca.itAlessandro LavacchiAlessio FossatiIlaria PerissiUgo Bardi2016-09-13T07:02:01Z2016-09-13T07:02:01Zhttp://eprints.imtlucca.it/id/eprint/3536This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/35362016-09-13T07:02:01ZNeural correlates of extinction of moral pain through forgivenessGiuseppina RotaEmiliano Ricciardiemiliano.ricciardi@imtlucca.itLorenzo SaniClaudio GentiliNicola VanelloMario GuazzelliPietro Pietrinipietro.pietrini@imtlucca.it2016-03-22T10:25:20Z2016-03-22T10:25:20Zhttp://eprints.imtlucca.it/id/eprint/3296This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32962016-03-22T10:25:20ZSingle and simultaneous release of drugs with different hydrophilicity from acrylic matricesMariacristina Gagliardimariacristina.gagliardi@imtlucca.itDavide SilvestriCaterina CristalliniPaolo Giusti2016-03-22T10:22:45Z2016-03-22T10:22:45Zhttp://eprints.imtlucca.it/id/eprint/3295This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32952016-03-22T10:22:45ZComputational evaluation of the mechanical behaviour of drug-loaded coatings for endovascular stentsMariacristina Gagliardimariacristina.gagliardi@imtlucca.itDavide SilvestriCaterina CristalliniNiccoletta BarbaniPaolo Giusti2016-03-22T10:21:58Z2016-03-22T10:21:58Zhttp://eprints.imtlucca.it/id/eprint/3294This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32942016-03-22T10:21:58ZSingle and combined drug elution of hydrophilic and hydrophobic drugs from acrylic matrices obtained by monomer-starved seeded semi-batch emulsion polymerizationDavide SilvestriMariacristina Gagliardimariacristina.gagliardi@imtlucca.itCaterina CristalliniPaolo Giusti2016-03-22T09:50:59Z2016-04-06T07:46:33Zhttp://eprints.imtlucca.it/id/eprint/3286This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32862016-03-22T09:50:59ZPoly(vinil alcohol)-chitosan blends modified by means of a dehydrothermal treatmentGiulio D. GuerraNiccoletta BarbaniCaterina CristalliniMariacristina Gagliardimariacristina.gagliardi@imtlucca.itElisabetta RoselliniDavide Silvestri2016-03-22T09:16:36Z2016-04-06T07:43:44Zhttp://eprints.imtlucca.it/id/eprint/3275This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32752016-03-22T09:16:36ZPreparation and functional characterization of a polysaccharidic matrix microsphere-shaped
for controlled drug releaseNiccoletta BarbaniCaterina CristalliniR. PulizziM. DonatiMariacristina Gagliardimariacristina.gagliardi@imtlucca.itA. RechichiGiulio D. GuerraPaolo Giusti2016-03-22T09:07:41Z2016-04-06T07:44:05Zhttp://eprints.imtlucca.it/id/eprint/3274This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32742016-03-22T09:07:41ZSmart polymer nanocomplexes obtained by template polymerisation for drug targetingCaterina CristalliniA. RuffiniT. RanzaniNiccoletta BarbaniElisabetta RoselliniDavide SilvestriMariacristina Gagliardimariacristina.gagliardi@imtlucca.itGiulio D. GuerraPaolo Giusti2016-03-22T09:04:58Z2016-03-22T09:04:58Zhttp://eprints.imtlucca.it/id/eprint/3273This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32732016-03-22T09:04:58ZDrug elution of hydrophilic and hydrophobic drugs from biostable acrylic matricesDavide SilvestriMariacristina Gagliardimariacristina.gagliardi@imtlucca.itCaterina CristalliniI. BaldoliC. ZeccaPaolo Giusti2016-03-22T09:00:26Z2016-03-22T09:00:26Zhttp://eprints.imtlucca.it/id/eprint/3271This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32712016-03-22T09:00:26ZPoly(methylmethacrylate-co-butylmethacrylate) copolymer from monomer-starved seeded
semi-batch reaction for biomedical useMariacristina Gagliardimariacristina.gagliardi@imtlucca.itDavide SilvestriNiccoletta BarbaniCaterina CristalliniE. BellottiS. ParriniPaolo Giusti2016-03-22T08:58:29Z2016-03-22T08:58:29Zhttp://eprints.imtlucca.it/id/eprint/3270This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32702016-03-22T08:58:29ZStudy of drug release mechanisms from PLGA/PHBHV bi-layered biodegradable
polymeric matricesMariacristina Gagliardimariacristina.gagliardi@imtlucca.itDavide SilvestriCaterina CristalliniM. GuadagniG. CrifaciPaolo Giusti2016-03-21T12:25:50Z2016-03-21T12:25:50Zhttp://eprints.imtlucca.it/id/eprint/3264This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32642016-03-21T12:25:50ZAcrylic Copolymers as Candidates for Drug-Eluting Coating of Vascular StentsThe aim of the present work is the synthesis and characterization of polymer materials showing good adhesion, drug loading, and delivery properties, for potential cardiovascular application. In particular, poly(methylmethacrylate-co-acrylic acid) copolymers are prepared in different compositions by a radical polymerization and investigated as potential materials to coat metallic stents and to carry out a local drug release. Films obtained by dissolving the copolymer in an appropriate organic solvent (also loaded with an anti-restenosis drug, such as tacrolimus) are investigated: physicochemical properties, adhesiveness to metallic stent material, and kinetics of drug release in physiological environment are studied.Davide SilvestriCaterina CristalliniMariacristina Gagliardimariacristina.gagliardi@imtlucca.itNiccoletta BarbaniM. D'AcuntoG. CiardelliPaolo Giusti2016-03-21T12:23:37Z2016-03-21T12:23:37Zhttp://eprints.imtlucca.it/id/eprint/3263This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32632016-03-21T12:23:37ZSynthesis and characterization of copolymers of methylmethacrylate and 2-hydroxyethyl methacrylate for the aqueous solubilization of PaclitaxelThe aim of the present work is the modification of a hydrophobic polymeric macromolecule, polymethylmethacrylate, by introducing hydrophilic moieties of 2-hydroxyethyl methacrylate within the polymer chain. Synthesis, characterization, and drug delivery control capabilities exerted on a highly hydrophobic drug (Paclitaxel) are illustrated. In particular, the dependency of the drug delivery kinetic on the fraction of hydrophilic units inserted in the copolymer chain was studied. Results showed that it is possible to have an increase of the kinetic delivery introducing hydrophilic units. In addition, a double control, diffusive and due to the relaxation of the molecules, on drug delivery was obtained.Davide SilvestriMariacristina Gagliardimariacristina.gagliardi@imtlucca.itNiccoletta BarbaniCaterina CristalliniPaolo Giusti2016-03-21T12:19:51Z2016-03-21T12:19:51Zhttp://eprints.imtlucca.it/id/eprint/3262This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32622016-03-21T12:19:51ZDifferent composition poly(methyl methacrylate-co-butyl methacrylate) copolymers through seeded semi-batch emulsion polymerizationIn the present work the synthesis and the chemical and thermal characterization of poly(methyl methacrylate-co-butyl methacrylate) copolymer, in three different macromolecular compositions, are reported. The aim of the present work was the identification of a standard method to obtain copolymers with controlled macromolecular composition, molecular weights and particle size distribution, together with the identification of the effect of the macromolecular composition on the material properties. A monomer-starved seeded semi-batch emulsion reaction was carried out and optimized, monitoring the kinetic of the copolymerization through the evaluation of residual monomer amounts. Then, an evaluation of the macromolecular composition was performed by Fourier transform infrared spectroscopy analysis. Molecular weight, molecular weight distribution, latex characteristics and thermal behaviour were also investigated.Davide SilvestriMariacristina Gagliardimariacristina.gagliardi@imtlucca.itCaterina CristalliniNiccoletta BarbaniPaolo Giusti2016-03-08T08:45:18Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3182This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31822016-03-08T08:45:18ZLa partecipazione nella localizzazione delle opere pubbliche.
Esperienze di diritto comparato.Lorenzo Casinilorenzo.casini@imtlucca.it2016-03-08T08:36:59Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3181This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31812016-03-08T08:36:59ZL'esperienza del LazioLorenzo Casinilorenzo.casini@imtlucca.it2016-03-08T08:18:52Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3180This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31802016-03-08T08:18:52ZLe funzioniLorenzo Casinilorenzo.casini@imtlucca.it2016-03-03T11:01:47Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3179This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31792016-03-03T11:01:47ZI confini e le dimensioniLorenzo Casinilorenzo.casini@imtlucca.it2016-02-19T12:50:49Z2016-02-19T12:50:49Zhttp://eprints.imtlucca.it/id/eprint/3092This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30922016-02-19T12:50:49ZBlindness and Consciousness: New Light from the DarkHow what we perceive is transformed into a coherent and integrated representation of the world around us is
a question that has fascinated humans since the early days. What happens in our brain that enables us to make
sense of what we see, hear, touch, smell or taste? How does the brain of someone who has never had any visual
perception form an image of the external world? Do brains from sighted and blind individuals differ and how? In
this chapter we discuss recent findings from research in animals as well from functional brain imaging studies in
sighted and blind individuals that are shedding new light on how the brain works.Pietro Pietrinipietro.pietrini@imtlucca.itMaurice PtitoRon Kupers2016-01-14T11:25:23Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3006This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30062016-01-14T11:25:23ZLe role des autorités publiques dans le management du sport: l'émergence des partenariats public/privéLorenzo Casinilorenzo.casini@imtlucca.itGiulio Napolitano2016-01-14T09:26:26Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3005This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30052016-01-14T09:26:26ZGlobal Hybrid Public-Private Bodies: The World Anti-Doping Agency (WADA)Acting in concert, States, sporting institutions and members of the international community have created a body that is emblematic of the emergence of the new forms of hybrid public-private governance mechanisms in the global sphere: the World Anti-Doping Agency (WADA). This article examines the structure and activities of this institution, in order to highlight a number of problems concerning the increasing use of public-private partnerships (PPPs) at the global level: the spread of normative functions carried out by global institutions and the binding force of these norms; the harmonization of different regulations at the global level; and the adoption of administrative law type mechanisms within global regimes and the emergence of global administrative law.Lorenzo Casini2016-01-14T08:58:50Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3003This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30032016-01-14T08:58:50ZGlobal Administrative Law Dimensions of International Organizations LawSeveral important legal features of the contemporary practice of international organizations (IOs) are not easily accommodated in standard approaches to international organizations law. This article argues that Global Administrative Law (GAL) approaches may strengthen analysis of operational issues such as emergency actions by IOs and the human rights implications of IO activities, structural issues such as the involvement of IOs in field missions and in public-private partnerships, and normative issues concerning the production and effects of non-treaty regulatory instruments by IOs (guidelines, best practices, national policy assessments, and other documents rather amorphously analyzed under the 'soft law' rubric). In examining these activities as forms of administration (broadly understood), subject to precepts of good administration and legal standards concerning transparency, participation, reason-giving, review, and accountability, a GAL perspective provides a basis both for critique of problematic practices, and for increasing the effectiveness and legitimacy of some beneficial IO activities which are contentious or currently not undertaken. GAL also responds to the proliferation and differentiation of IOs and other entities in global governance through applying legal standards to their interactions, bringing a principled 'inter-public' approach to the legal relations among global public entities. GAL provides a valuable, and thus far overly neglected, addition to the field of international institutional law.Benedict KingsburyLorenzo Casinilorenzo.casini@imtlucca.it2016-01-14T08:49:29Z2016-09-14T10:21:17Zhttp://eprints.imtlucca.it/id/eprint/3002This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30022016-01-14T08:49:29ZPerequazioni e compensazioni nel nuovo Prg di RomaLorenzo Casinilorenzo.casini@imtlucca.it2015-12-23T15:17:45Z2016-09-13T09:55:21Zhttp://eprints.imtlucca.it/id/eprint/2976This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29762015-12-23T15:17:45ZDo we really need vision? How blind people "see" the actions of othersObserving and learning actions and behaviors from others, a mechanism crucial for survival and social interaction, engages the mirror neuron system. To determine whether vision is a necessary prerequisite for the human mirror system to develop and function, we used functional magnetic resonance imaging to compare brain activity in congenitally blind individuals during the auditory presentation of hand-executed actions or environmental sounds, and the motor pantomime of manipulation tasks, with that in sighted volunteers, who additionally performed a visual action recognition task. Congenitally blind individuals activated a premotor–temporoparietal cortical network in response to aurally presented actions that overlapped both with mirror system areas found in sighted subjects in response to visually and aurally presented stimuli, and with the brain response elicited by motor pantomime of the same actions. Furthermore, the mirror system cortex showed a significantly greater response to motor familiar than to unfamiliar action sounds in both sighted and blind individuals. Thus, the mirror system in humans can develop in the absence of sight. The results in blind individuals demonstrate that the sound of an action engages the mirror system for action schemas that have not been learned through the visual modality and that this activity is not mediated by visual imagery. These findings indicate that the mirror system is based on supramodal sensory representations of actions and, furthermore, that these abstract representations allow individuals with no visual experience to interact effectively with others.Emiliano Ricciardiemiliano.ricciardi@imtlucca.itDaniela BoninoLorenzo SaniTomaso VecchiMario GuazzelliJames V. HaxbyLuciano FadigaPietro Pietrinipietro.pietrini@imtlucca.it2015-12-02T15:47:05Z2016-09-13T09:55:50Zhttp://eprints.imtlucca.it/id/eprint/2960This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29602015-12-02T15:47:05ZCholinergic modulation of visual working memory during aging: a parametric PET studyAge-related differences in the regional recruitment of prefrontal cortex (PFC) during cognitive tasks suggests that aging is associated with functional reorganization. Cholinergic enhancement with physostigmine reduces activity in the {PFC} regions selectively recruited during working memory (WM) and increases activity in visual processing areas, suggesting that augmenting cholinergic function reduces task effort by improving the visual representation of {WM} stimuli. Here, we investigated how cholinergic enhancement influenced {PFC} and visual cortical activity in young and older subjects as {WM} difficulty was altered. Regional cerebral blood flow (rCBF) was measured using H215O-PET in 10 young and 10 older volunteers during a parametrically varied face {WM} task, following an i.v. infusion of saline and physostigmine. Reaction time decreased during physostigmine relative to placebo in both groups. Prefrontal brain regions selectively recruited in each age group that responded differentially to task demands during placebo, had no significant activity during physostigmine. Medial visual processing areas showed task-selective increases in activity during drug in both groups, while lateral regions showed decreased activity in young and increased activity in older participants at longer task delays. These results are consistent with our previous findings, showing that the modulatory role of the cholinergic system persists during aging, and that the effects of cholinergic enhancement are functionally specific rather than anatomically specific. Moreover, the use of the parametric design allowed us to uncover group specific effects in lateral visual processing areas where increasing cholinergic function produced opposite effects on neural activity in the two age groups.Emiliano Ricciardiemiliano.ricciardi@imtlucca.itPietro Pietrinipietro.pietrini@imtlucca.itMark B. SchapiroStanley I. RapoportMaura L. Furey2015-12-02T15:36:51Z2016-09-13T09:55:34Zhttp://eprints.imtlucca.it/id/eprint/2959This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29592015-12-02T15:36:51ZNeural correlates of “analytical-specific visual perception” and degree of task difficulty as investigated by the Mangina-Test: A functional magnetic resonance imaging (fMRI) study in young healthy adultsThe Mangina-Test is a neuropsychometric method for evaluating varying degrees of “analytical-specific perception” as they relate to learning abilities and disabilities. It consists of the identification of simple stimuli which are masked within a complex configuration according to their exact size, dimension, direction, spatial orientation, and shape within a limited span of time. This test has been successfully applied in clinical settings for the assessment of cognitive abilities and disorders in young and elderly populations. This investigation aimed to examine the neural correlates of analytical-specific visual perceptual processes as measured by the Mangina-Test. Functional Magnetic Resonance Imaging (fMRI) was recorded during the administration of a computer-adapted version of the Mangina-Test in twelve young healthy adults. Multiple linear regression analysis was applied to estimate the overall brain activation during task accomplishment. In addition, the fMRI response area was correlated with task difficulty, in order to explore the spatial distribution of brain regions modulated by increasing task demand. Results indicate that a widely distributed bilateral network of brain regions, including the ventral and dorsal occipital cortex, parietal lobule, frontal and supplementary eye field, dorsolateral prefrontal cortex, and supplementary motor area, was significantly activated during test performance. Moreover, increasing difficulty significantly enhanced the neural response of ventral and dorsal occipital regions, frontal eye field, and superior parietal sulcus bilaterally, as well as the right dorsolateral prefrontal cortex. Conversely, neural activity in the left temporo-parietal junction, inferior frontal gyrus, and bilateral middle-superior temporal cortex was inversely correlated with task difficulty. Results also indicate that performance in the Mangina-Test requires an optimal integration between the enhancement of activity in specific task-related cortical areas and suppression of interfering noise from unrelated brain regions.Constantine A. ManginaHelen Beuzeron-ManginaEmiliano Ricciardiemiliano.ricciardi@imtlucca.itPietro Pietrinipietro.pietrini@imtlucca.itGiuseppe A. ChiarenzaSilvia Casarotto2015-12-02T15:24:06Z2016-09-13T09:55:03Zhttp://eprints.imtlucca.it/id/eprint/2958This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29582015-12-02T15:24:06ZBeyond amygdala: default mode network activity differs between patients with social phobia and healthy controlsThe Default Mode Network (DMN) is a constellation of brain areas that decrease their activity during a wide number of different goal-oriented tasks as compared to passive “rest” tasks. {DMN} can be modulated by different factors such as emotional states, cognitive load of the task and psychopathology, including anxiety. Moreover, {DMN} seems to play a pivotal role in social cognition. For example, the ability to predict another person's behaviour taking his or her perspective modulates the activity of the DMN. Recent data from autistic patients support a role of {DMN} in social cognition as well. Social Phobia (SP) is an anxiety disorder characterized by an abnormal distress in situations that require social interaction. To date, no study has assessed {DMN} in Social Phobia. To determine potential differences in {DMN} activity between Social Phobia patients (SPP) and healthy control (HC) subjects we examined functional magnetic resonance imaging (fMRI) data obtained during a face perception study with emotional and neutral stimuli. As compared to HC, {SPP} showed a lower deactivation in the precuneus and posterior cingulate regions (PCun/PCC) during task conditions. These regions are part of the so-called “Theory of Mind” circuit and in particular they are involved in the evaluation of one's own emotional state. Because of the role of the PCun/PCC in self-state perception and attribution and, more in general, the role of the {DMN} in social cognition, we suggest that its impairment in the {DMN} network in {SPP} might be relevant in the development of the feeling of wariness of others’ judgment and may be related to the so-called self-focused attention. Self-focused attention is the awareness of self-referent information, and is present in many emotional disorders and may additionally prevent individuals from observing external information that could disconfirm their own fears. Moreover, the abnormal modulation of activity in the {DMN} may reflect persistent rumination or anxiety-related thoughts that are not modulated by the switch from rest to task.Claudio GentiliEmiliano Ricciardiemiliano.ricciardi@imtlucca.itMaria Ida GobbiniMaria Filomena SantarelliJames V. HaxbyPietro Pietrinipietro.pietrini@imtlucca.itMario Guazzelli2015-12-02T14:45:09Z2016-09-13T09:56:06Zhttp://eprints.imtlucca.it/id/eprint/2957This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29572015-12-02T14:45:09ZModulation of specific brain activity by the perceptual analysis of very subtle geometrical relationships of the Mangina-Test stimuli: a functional magnetic resonance imaging (fMRI) investigation in young healthy adultsThe Mangina-Test provides a neuropsychometric assessment of varying degrees of “Analytical-Specific Visual Perception”, i.e., the ability to identify simple stimuli inserted into more complex ones according to their exact geometrical properties in a limited span of time. Perceptual analysis of stimuli dealing with the exact discrimination of size and dimension is related more to mathematical abilities (MATH), while perceptual analysis of direction and spatial orientation is related more to abilities in reading and reading comprehension (READ). Some stimuli are {MIXED} since they deal with both of the above features combined. We previously determined the distributed neuronal network of analytical-specific visual perceptual processes as measured by the Mangina-Test. Here, we aim at further assessing as to how brain activity is differentially modulated by the discrimination of very subtle category-specific perceptual relationships. Brain activity was measured by functional magnetic resonance imaging in 12 young healthy subjects while they performed a computer-adapted version of the Mangina-Test. Behavioral results of the present study indicate that performance was not different among stimulus categories. However, brain functional data show that analytical-specific perceptual processes for MATH, {READ} and {MIXED} stimuli rely on partially distinct brain circuits. Bilateral posterior parietal, premotor and prefrontal regions along with the anterior cingulate appeared to be more activated by {MATH} stimuli, while {READ} stimuli predominantly activated bilateral medial occipito-temporal, amygdala/parahippocampal and sensorimotor cortices, and the right inferior frontal cortex. Moreover, the posterior parahippocampal cortex showed a higher activity specifically for {MIXED} stimuli. Altogether, these findings demonstrate that in the Mangina-Test, the exact discrimination of very subtle perceptual relationships between geometrical stimuli distinctly modulates cerebral activity, so that category-specific brain responses can be related to identifiable cognitive abilities.Constantine A. ManginaHelen Beuzeron-ManginaSilvia CasarottoGiuseppe A. ChiarenzaPietro Pietrinipietro.pietrini@imtlucca.itEmiliano Ricciardiemiliano.ricciardi@imtlucca.it2015-12-02T14:36:51Z2015-12-02T14:36:51Zhttp://eprints.imtlucca.it/id/eprint/2956This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29562015-12-02T14:36:51ZRole of matrix metalloproteinases and their tissue inhibitors as potential biomarkers of left ventricular remodelling in the athlete’s heartThe aim of the present study was to verify whether plasma MMPs (matrix metalloproteinases) and TIMPs (tissue inhibitors of MMPs) could be used as potential markers of paraphysiological remodelling in the athlete’s heart, and to correlate these matrix parameters with echocardiographic signs of LV (left ventricular) remodelling. Plasma MMP-2 and MMP-9 were measured by zymography, and TIMP-1 and TIMP-2 were measured by ELISA in 42 veteran marathoners with AH (athlete’s heart), and in 25 sedentary healthy subjects (CTL). All subjects were submitted to a clinical examination and two-dimensional colour Doppler echocardiography together with the measurement of circulating NT-proBNP (N-terminal pro-B-type natriuretic peptide); GGT (γ-glutamyl transpeptidase) was evaluated as a marker of cardiovascular disease. Veteran athletes had a significant elevation in LV dimensions and calculated LV mass index. Diastolic and systolic functions were normal for both groups. MMP-9 levels were significantly lower in AH than in CTL subjects (56.9±4.3 compared with 119.4±21.5 m-units/l, P<0.01). There were significant differences in MMP-2 between the two groups, with a down-regulation in the AH subjects (182.5±16.8~units/ml in CTL compared with 117.1±9.1~units/ml in AH, P<0.01). MMP-2 and MMP-2/TIMP-2 were inversely correlated with myocardial indices of hypertrophy in AH and CTL subjects. AH and CTL subjects showed similar TIMP values. The results of the present study indicate that MMPs and TIMPs could represent potential biomarkers of adaptive heart remodelling in the athletes. In addition, the inverse correlation of the MMP-2/TIMP-2 system with echocardiographic signs of myocardial hypertrophy could represent a new diagnostic and prognostic indicator useful in the evaluation of cardiovascular risk in athletes. Abbreviations: A, late diastolic peak velocity; AH, athlete’s heart; CTL, control; E, early diastolic peak velocity; ECM, extracellular matrix; EF, ejection fraction; GGT, γ-glutamyl transpeptidase; HF, heart failure; LV, left ventricular; LVEDD, LV end-diastolic diameter; LVM, LV mass; MMP, matrix metalloproteinase; NT-proBNP, N-terminal pro-B-type natriuretic peptide; TIMP, tissue inhibitor of MMPsAnnamaria VianelloLaura CaponiFerdinando FranzoniFabio GalettaMarco RossiMarco TaddeiGino MalvaldiPietro Pietrinipietro.pietrini@imtlucca.itGino Santoro2015-12-02T14:24:42Z2015-12-02T15:25:11Zhttp://eprints.imtlucca.it/id/eprint/2955This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29552015-12-02T14:24:42ZHomo ferox: the contribution of functional brain studies to understanding the neural bases of aggressive and criminal behaviorPietro Pietrinipietro.pietrini@imtlucca.itValentina Bambini2015-11-05T10:48:48Z2018-03-08T17:05:17Zhttp://eprints.imtlucca.it/id/eprint/2807This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/28072015-11-05T10:48:48ZWeighted Random GraphTiziano Squartinitiziano.squartini@imtlucca.itDiego Garlaschellidiego.garlaschelli@imtlucca.it2015-03-27T11:14:59Z2015-03-27T12:54:14Zhttp://eprints.imtlucca.it/id/eprint/2651This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/26512015-03-27T11:14:59ZAero-Elastic Analysis of Stiffened Composite Wing StructureThe interaction of the Elastic, Inertia and Aerodynamic forces is a dynamic phenomena resulting in flutter. Dynamic Aero elasticity is critical for a high-speed subsonic class of AerialVehicles. In the presentwork, dynamic Aero-elastic analysis of the Unmanned Aerial Vehicles (UAVs) has been studied for a stiffened composite structure. The flutter speed and the corresponding flutter frequencies are computed using the Velocity-Damping (V -g) method. The V -g method is employed to estimate the flutter speed and flutter frequencies, for a high-speed subsonic composite wing structure, designed and developed at ADE. Also the improvement of the flutter frequencies over the existing metallic wing structure is discussed. The work can be further extended to develop an optimized composite structure with higher margins in flutter speeds.
Keywords: Aeroelasticity, Flutter, Velocity-damping methodPattabhi R. Budarapupattabhi.budarapu@imtlucca.itB. RammohanS. Vijay KumarD. Satish Babu R. Raghuatnhan2015-02-11T13:51:46Z2015-02-11T13:51:46Zhttp://eprints.imtlucca.it/id/eprint/2598This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25982015-02-11T13:51:46ZThe PEPA eclipse pluginThe PEPA Eclipse Plug-in supports the creation and analysis of performance models, from small-scale Markov models to large-scale simulation studies and differential equation systems. Whichever form of analysis is used, models are expressed in a single highlevel language for quantitative modelling, Performance Evaluation Process Algebra (PEPA).Mirco Tribastonemirco.tribastone@imtlucca.itAdam DuguidStephen Gilmore2015-02-11T13:40:30Z2015-02-11T13:40:30Zhttp://eprints.imtlucca.it/id/eprint/2596This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25962015-02-11T13:40:30ZQuantitative analysis of web services using SRMCIn this tutorial paper we present quantitative methods for analysing Web Services with the goal of understanding how they will perform under increased demand, or when asked to serve a larger pool of service subscribers. We use a process calculus called SRMC to model the service. We apply efficient analysis techniques to numerically evaluate our model. The process calculus and the numerical analysis are supported by a set of software tools which relieve the modeller of the burden of generating and evaluating a large family of related models. The methods are illustrated on a classical example of Web Service usage in a business-to-business scenario.Allan ClarkStephen GilmoreMirco Tribastonemirco.tribastone@imtlucca.it2015-02-09T09:18:02Z2015-02-09T09:19:12Zhttp://eprints.imtlucca.it/id/eprint/2572This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25722015-02-09T09:18:02ZScalable analysis of scalable systemsWe present a systematic method of analysing the scalability of large-scale systems. We construct a high-level model using the SRMC process calculus and generate variants of this using model transformation. The models are compiled into systems of ordinary differential equations and numerically integrated to predict non-functional properties such as responsiveness and scalability.Allan ClarkStephen GilmoreMirco Tribastonemirco.tribastone@imtlucca.it2015-02-06T13:39:18Z2015-02-06T13:39:18Zhttp://eprints.imtlucca.it/id/eprint/2567This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25672015-02-06T13:39:18ZService-level agreements for service-oriented computingService-oriented computing is dynamic. There may be many possible service instances available for binding, leading to uncertainty about where service requests will execute. We present a novel Markovian process calculus which allows the formal expression of uncertainty about binding as found in service-oriented computing. We show how to compute meaningful quantitative information about the quality of service provided in such a setting. These numerical results can be used to allow the expression of accurate service-level agreements about service-oriented computing.Allan ClarkStephen GilmoreMirco Tribastonemirco.tribastone@imtlucca.it2015-02-06T10:35:18Z2015-02-06T13:56:54Zhttp://eprints.imtlucca.it/id/eprint/2556This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25562015-02-06T10:35:18ZDifferential analysis of PEPA modelsMirco Tribastonemirco.tribastone@imtlucca.it2015-01-20T10:12:08Z2015-01-20T10:12:08Zhttp://eprints.imtlucca.it/id/eprint/2521This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25212015-01-20T10:12:08ZNon-local computational homogenization of periodic masonry for the in-plane analysis of shear wallsAndrea Bacigalupoandrea.bacigalupo@imtlucca.itLuigi Gambarotta2015-01-19T14:27:53Z2015-01-19T14:27:53Zhttp://eprints.imtlucca.it/id/eprint/2507This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25072015-01-19T14:27:53ZMicro-polar and second order homogenization of periodic masonryMicro-polar and second order homogenization procedures for periodic elastic
masonry are implemented to include geometric and material length scales in the constitutive
equation. By the solution of the RVE equilibrium problems with properly prescribed boundary
conditions the orthotropic elastic moduli of the higher order continua are obtained on the basis of
an enhanced Hill–Mandel condition. A shear layer problem is analysed and the results from the
heterogeneous models are compared with those ones obtained by the homogenization procedures;
the second-order homogenization appears to provide better results in comparison to the micropolar
homogenizationAndrea Bacigalupoandrea.bacigalupo@imtlucca.itLuigi Gambarotta2015-01-19T13:59:20Z2015-01-19T13:59:20Zhttp://eprints.imtlucca.it/id/eprint/2506This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25062015-01-19T13:59:20ZCostruire in muratura: un processo continuo di crescita strutturaleAndrea Bacigalupoandrea.bacigalupo@imtlucca.itLuigi Gambarotta2015-01-15T13:01:59Z2015-01-15T13:01:59Zhttp://eprints.imtlucca.it/id/eprint/2487This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/24872015-01-15T13:01:59ZTyping component-based communication systemsBuilding complex component-based software systems, for instance communication systems based on the Click, Coyote, Appia, or Dream frameworks, can lead to subtle assemblage errors. We present a novel type system and type inference algorithm that prevent interconnection and message-handling errors when assembling component-based communication systems. These errors are typically not captured by classical type systems of host programming languages such as Java or ML. We have implemented our approach by extending the architecture description language (ADL) toolset used by the Dream framework, and used it to check Dream-based communication systems.Michael LienhardtClaudio Antares Mezzinaclaudio.mezzina@imtlucca.itAlan SchmittJean-Bernard Stefani2015-01-08T13:49:05Z2015-01-08T13:49:05Zhttp://eprints.imtlucca.it/id/eprint/2437This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/24372015-01-08T13:49:05ZKitenergy: a radical innovation in wind energy generationThis paper presents an innovative technology of high-altitude wind power generation, indicated as Kitenergy, which exploits the automatic flight of tethered airfoils (e.g. power kites) to extract energy from wind blowing between 200 and 800 meters above the ground. The key points of such a technology are described and the design of large scale plants is investigated here, in order to show that Kitenergy technology has the potential to provide large quantities of renewable energy with competitive cost with respect to fossil sources. Such claims are supported by the results obtained so far in the research activities undergoing at Politecnico di Torino, Italy, including numerical simulations, prototype experiments and wind data analyses.Lorenzo FagianoMario MilaneseDario Pigadario.piga@imtlucca.it2015-01-08T13:24:07Z2015-01-08T13:24:07Zhttp://eprints.imtlucca.it/id/eprint/2436This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/24362015-01-08T13:24:07ZSet-membership identification of block-structured nonlinear feedback systemsIn this paper a three-stage procedure for set-membership identification of block-structured nonlinear feedback systems is proposed. Nonlinear block parameters bounds are computed in the first stage exploiting steady-state measurements. Then, given the uncertain description of the nonlinear block, bounds on the unmeasurable inner-signal are computed in the second stage. Finally, linear block parameters bounds are computed in the third stage on the basis of output measurements and computed inner signal bounds. Computation of both the nonlinear block parameters and the inner-signal bounds is formulated in terms of semialgebraic optimization and solved by means of suitable convex LMI relaxation techniques. Linear block parameters are bounded solving a number of linear programming problems.Vito CeroneDario Pigadario.piga@imtlucca.itDiego Regruto2015-01-08T11:51:23Z2015-01-08T11:51:23Zhttp://eprints.imtlucca.it/id/eprint/2434This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/24342015-01-08T11:51:23ZParameter bounds evaluation for linear systems with output backlashIn this paper a procedure is presented for deriving parameters bounds of linear systems with output backlash when the output measurement errors are bounded. First, using steady-state input/output data, parameters of the backlash are bounded. Then, given the estimated uncertain backlash and the output measurements collected exciting the system with a PRBS, bounds on the unmeasurable inner signal are computed. Finally, such bounds, together with the input sequence, are used for bounding the parameters of the linear block.Vito CeroneDario Pigadario.piga@imtlucca.itDiego Regruto2014-12-11T09:38:48Z2014-12-16T14:35:43Zhttp://eprints.imtlucca.it/id/eprint/2410This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/24102014-12-11T09:38:48ZSparse reconstruction for compressed sensing using Stagewise Polytope Faces PursuitCompressed sensing, also known as compressive sampling, is an approach to the measurement of signals which have a sparse representation, that can reduce the number of measurements that are needed to reconstruct the signal. The signal reconstruction part requires efficient methods to perform sparse reconstruction, such as those based on linear programming. In this paper we present a method for sparse reconstruction which is an extension of our earlier polytope faces pursuit algorithm, based on the polytope geometry of the dual linear program. The new algorithm adds several basis vectors at each stage, in a similar way to the recent stagewise orthogonal matching pursuit (StOMP) algorithm. We demonstrate the application of the algorithm to some standard compressed sensing problems.Mark D. PlumbleyMarco Bevilacquamarco.bevilacqua@imtlucca.it2014-12-04T09:22:00Z2016-04-06T09:57:54Zhttp://eprints.imtlucca.it/id/eprint/2397This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23972014-12-04T09:22:00ZEmergent self-organized complex network topology out of stability constraintsAlthough most networks in nature exhibit complex topologies, the origins of such complexity remain unclear. We propose a general evolutionary mechanism based on global stability. This mechanism is incorporated into a model of a growing network of interacting agents in which each new agent’s membership in the network is determined by the agent’s effect on the network’s global stability. It is shown that out of this stability constraint complex topological properties emerge in a self-organized manner, offering an explanation for their observed ubiquity in biological networks.Juan I. Perottijuanignacio.perotti@imtlucca.itOrlando V. BilloniFrancisco A. TamaritDante ChialvoSergio A. Cannas2014-12-02T15:15:35Z2014-12-18T13:56:23Zhttp://eprints.imtlucca.it/id/eprint/2384This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23842014-12-02T15:15:35ZMining communities in networksOnline social networks pose significant challenges to computer scientists, physicists, and sociologists alike, for their massive size, fast evolution, and uncharted potential for social computing. One particular problem that has interested us is community identification. Many algorithms based on various metrics have been proposed for communities in networks [18, 24], but a few algorithms scale to very large networks. Three recent community identification algorithms, namely CNM [16], Wakita [59], and Louvain [10], stand out for their scalability to a few millions of nodes. All of them use modularity as the metric of optimization. However, all three algorithms produce inconsistent communities every time the ordering of nodes to the algorithms changes.
We propose two quantitative metrics to represent the level of consistency across multiple runs of an algorithm: pairwise membership probability and consistency. Based on these two metrics, we propose a solution that improves the consistency without compromising the modularity. We demonstrate that our solution to use pairwise membership probabilities as link weights generates consistent communities within six or fewer cycles for most networks. However, our iterative, pairwise membership reinforcing approach does not deliver convergence for Flickr, Orkut, and Cyworld networks as well for the rest of the networks. Our approach is empirically driven and is yet to be shown to produce consistent output analytically. We leave further investigation into the topological structure and its impact on the consistency as future work.
In order to evaluate the quality of clustering, we have looked at 3 of the 48 communities identified in the AS graph. Surprisingly, all have either hierarchical, geographical, or topological interpretations to their groupings. Our preliminary evaluation of the quality of communities is promising. We plan to conduct more thorough evaluation of the communities and study network structures and their evolutions using our approach.
Haewoon KwakYoonchan ChoiYoung-Ho Eomyoungho.eom@imtlucca.itHawoong JeongSue Moon2014-11-10T12:00:01Z2015-03-25T09:16:39Zhttp://eprints.imtlucca.it/id/eprint/2357This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23572014-11-10T12:00:01ZTwo millennia of climate variability in the Central MediterraneanThis experimental work addresses the need for high-resolution, long and homogeneous climatic time series that facilitate the study of climate variability over time scales of decades to millennia. We present a high-resolution record of foraminiferal δ18O from a Central-Mediterranean sediment core that covers the last two millennia. The record was analyzed using advanced spectral methods and shows highly significant oscillatory components with periods of roughly 600, 350, 200, 125 and 11 years. Over the last millennium, our data show several features related to known climatic periods, such as the Medieval Optimum, the Little Ice Age and a recent steep variation since the beginning of the Industrial Era. During the preceding millennium, the δ18O series also reveals a surprising maximum at about 0 AD, suggesting low temperatures at that time. This feature contradicts widely held ideas about the Roman Classical Period; it is, therefore, discussed at some length, by reviewing the somewhat contradictory evidence about this period.
We compare the δ18O record with an alkenone-derived sea surface temperature time series, obtained from cores extracted in the same Central-Mediterranean area (Gallipoli Terrace, Ionian Sea), as well as with Italian and other European temperature reconstructions over the last centuries. Based on this comparison, we show that the long-term trend and the 200-y oscillation in the records are temperature driven and have a dominant role in describing temperature variations over the last two millennia.Carla TariccoMichael GhilSilvia AlessioGianna Vivaldogianna.vivaldo@imtlucca.it2014-11-10T11:48:40Z2015-03-25T09:16:39Zhttp://eprints.imtlucca.it/id/eprint/2356This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23562014-11-10T11:48:40ZAccurate dating of Gallipoli Terrace (Ionian Sea) sediments: historical eruptions and climate recordsThe radiometric and tephro-analysis dating of shallow-water Ionian Sea cores is summarized. The 2-kyr series of volcanic pyroxene grains provides information on the volcanic activity of the Campanian area for the period that precedes detailed documentation of eruptions.Gianna Vivaldogianna.vivaldo@imtlucca.itCarla TariccoSilvia AlessioMichael Ghil2014-11-10T11:20:52Z2015-03-25T09:16:39Zhttp://eprints.imtlucca.it/id/eprint/2355This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23552014-11-10T11:20:52ZReconstruction of solar activity variations in the past by measurement of cosmogenic radioisotopes in meteoritesMany reconstructions of solar activity variations in the past are based on the measurement of cosmogenic isotopes (such as 14C and 10Be) stored in terrestrial archives. The concentration of these isotopes is however influenced by terrestrial phenomena. In order to avoid this problem our group is studying cosmogenic radioisotopes in meteorites at the underground laboratory of Monte dei Cappuccini in Torino (Italy). Measurement of 44Ti decay activity in 21 meteorites has revealed a centennial oscillation superimposed on a decreasing trend of the cosmic ray flux in the last 235 years. The decreasing trend is consistent with some models based on solar open magnetic field variations. We show some preliminary results obtained using a new acquisition system we have recently developed and set up in order to enhance selectivity of 44Ti detection.Carla TariccoNarendra BhandariPaolo ColombettiAlberto RomeroNeeharika VermaGianna Vivaldogianna.vivaldo@imtlucca.it2014-10-10T08:18:48Z2014-10-10T08:18:48Zhttp://eprints.imtlucca.it/id/eprint/2309This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23092014-10-10T08:18:48ZCalcolo delle strutture isostaticheI numerosi esercizi sulle strutture isostatiche proposti nel presente volume sono stati risolti completamente, riportando, oltre ai diagrammi delle caratteristiche della sollecitazione interna, la curva delle pressioni e il poligono delle forze attive e reattive. Inoltre, nel caso di diversi esercizi, si è verificata una reazione vincolare interna, applicando il Principio dei Lavori Virtuali per i sistemi di corpi rigidi, così come i due Teoremi delle Catene Cinematiche riguardanti i centri di rotazione assoluta e relativa. In altri casi si è calcolato invece uno spostamento elastico o una rotazione elastica, applicando il Principio dei Lavori Virtuali per i sistemi di travi elastiche. La teoria su cui si basano i metodi di risoluzione proposti, così come la stessa simbologia utilizzata, si riferiscono ai Volumi 1 e 2 della presente Collana di Ingegneria Strutturale ("Scienza delle Costruzioni 1 e 2", autore: Alberto Carpinteri, Pitagora Editrice Bologna, 1992). L'opera si sviluppa in quattro diversi capitoli, in ordine crescente di difficoltà concettuale, così come viene usualmente fatto dalla maggior parte delle Scuole Italiane: (1) Strutture reticolari; (2) Travi Gerber; (3) Archi a tre cerniere; (4) Strutture chiuse. Pur presentando geometrie strutturali e condizioni di vincolamento assai varie, le tipologie studiate risultano essere in tutti i casi analoghe a quelle che si possono incontrare nella pratica professionale (strutture di grande luce, ponti, coperture, apparecchi di sollevamento, etc.).
Alberto CarpinteriGiuseppe LacidognaMarco Paggimarco.paggi@imtlucca.it2014-10-09T11:45:31Z2015-04-08T10:37:32Zhttp://eprints.imtlucca.it/id/eprint/2310This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23102014-10-09T11:45:31ZSpatial logic model checker user’s guide : version 1.15Luis CairesHugo Torres Vieirahugo.torresvieira@imtlucca.it2014-10-08T13:38:03Z2015-04-08T10:37:32Zhttp://eprints.imtlucca.it/id/eprint/2298This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22982014-10-08T13:38:03ZConversation typesWe present a type theory for analyzing concurrent multiparty interactions as found in service-oriented computing. Our theory introduces a novel and flexible type structure, able to uniformly describe both the internal and the interface behavior of systems, referred respectively as choreographies and contracts in web-services terminology. The notion of conversation builds on the fundamental concept of session, but generalizes it along directions up to now unexplored; in particular, conversation types discipline interactions in conversations while accounting for dynamical join and leave of an unanticipated number of participants. We prove that well-typed systems never violate the prescribed conversation constraints. We also present techniques to ensure progress of systems involving several interleaved conversations, a previously open problem.Luis CairesHugo Torres Vieirahugo.torresvieira@imtlucca.it2014-10-08T13:21:57Z2015-04-08T10:37:32Zhttp://eprints.imtlucca.it/id/eprint/2297This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22972014-10-08T13:21:57ZA process calculus analysis of compensationsConversations in service-oriented computation are frequently long running. In such a setting, traditional ACID properties of transactions cannot be reasonably implemented, and compensation mechanisms seem to provide convenient techniques to, at least, approximate them. In this paper, we investigate the representation and analysis of structured compensating transactions within a process calculus model, by embedding in the Conversation Calculus certain structured compensation programming abstractions inspired by the ones proposed by Butler, Ferreira, and Hoare. We prove the correctness of the embedding after developing a general notion of stateful model for structured compensations and related results, and showing that the embedding induces such a model.Luis CairesCarla FerreiraHugo Torres Vieirahugo.torresvieira@imtlucca.it2014-03-03T14:13:47Z2014-03-03T14:17:25Zhttp://eprints.imtlucca.it/id/eprint/2169This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21692014-03-03T14:13:47ZPurification of liquid indium by electric current-induced impurity migration in a static transverse magnetic field We have developed an original method for indium purification. Our approach is based on the directional transfer of impurities by applying crossed electric and magnetic fields to the melting volume. The method reduced the concentration of nickel and tin by a factor of 10 while copper was reduced by a factor of 3. A simple hydrodynamic mass transport model describing the process was also derived.Ugo BardiClaudia Borriclaudia.borri@imtlucca.itAlessandro LavacchiAlexander TolstogouzovE.B. TruninO.E Trunina2014-03-03T13:05:06Z2014-03-03T14:07:02Zhttp://eprints.imtlucca.it/id/eprint/2165This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21652014-03-03T13:05:06ZCyclic voltammetry simulation at microelectrode arrays with COMSOL MultiphysicsThe present paper reports the results obtained applying the general purpose software COMSOL Multiphysics® to the finite elements simulation of Cyclic Voltammetries (CV’s) at microelectrodes arrays (MEA). CV’s at inlaid micro disk electrode arrays have been simulated benchmarking our results with those obtained by Compton with the finite difference method. Then the influence of meshing on the quality of the simulated data have been investigated showing that bad meshing may provide shapes with no physical meaning. Simulations have also been performed on recessed micro disk arrays in order to show the effect of the depth of the recess on the voltammetric wave shape. We found that COMSOL Multiphysics® provides a flexible and straightforward route to the simulation of electrochemical systems with complex geometry.Alessandro LavacchiUgo BardiClaudia Borriclaudia.borri@imtlucca.itStefano CaporaliAlessio FossatiI. Perissi2014-01-17T13:49:15Z2014-01-17T13:49:15Zhttp://eprints.imtlucca.it/id/eprint/2095This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20952014-01-17T13:49:15ZAdvanced features in Bayesian reputation systemsBayesian reputation systems are quite flexible and can relatively easily be adapted to different types of applications and environments. The purpose of this paper is to provide a concise overview of the rich set of features that characterizes Bayesian reputation systems. In particular we demonstrate the importance of base rates during bootstrapping, for handling rating scarcity and for expressing long term trendsAudun JøsangWalter Quattrociocchiwalter.quattrociocchi@imtlucca.it2014-01-17T12:13:16Z2014-01-17T12:13:16Zhttp://eprints.imtlucca.it/id/eprint/2094This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20942014-01-17T12:13:16ZOn the effects of informational cheating on social evaluations: image and reputation through gossipMulti-agent-based simulation is an arising scientific trend which is naturally provided of instruments able to cope with complex systems, in particular the socio-cognitive complex systems. In this paper, a simulation-based exploration of the effect of false information on social
evaluation formation is presented. We perform simulative experiments on the Repage platform, a computational system allowing agents to communicate and acquire both direct (image) and indirect and unchecked (reputation) information. Informational cheating, when the number of liars becomes substantial, is shown to seriously affect quality achievement obtained through reputation. In the paper, after a brief introduction of the theoretical background, the hypotheses and the market scenario are presented and the simulation results are discussed with respect to the agents’ decision-making process, focusing on
uncertainty, false information spreading and quality of contracts.Walter Quattrociocchiwalter.quattrociocchi@imtlucca.itMario PaolucciRosaria Conte2014-01-17T12:02:57Z2014-01-17T12:02:57Zhttp://eprints.imtlucca.it/id/eprint/2093This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20932014-01-17T12:02:57ZImage and reputation coping differently with massive informational cheatingMulti-agent based simulation is an arising scientific trend which is naturally provided of instruments able to cope with complex systems, in particular the socio-cognitive complex systems. In this paper, a simulation-based exploration of the effect of false information on social evaluation formation is presented. We perform simulative experiments on the RepAge platform, a computational system allowing agents to communicate and acquire both direct (image) and indirect and unchecked (reputation) information. Informational cheating, when the number of liars becomes substantial, is shown to seriously affect quality achievement obtained through reputation. In the paper, after a brief introduction of the theoretical background, the hypotheses and the market scenario are presented and the simulation results are discussed with respect to the agents’ decision making process, focusing on uncertainty, false information spreading and quality of contracts.Walter Quattrociocchiwalter.quattrociocchi@imtlucca.itMario PaolucciRosaria Conte2014-01-17T11:52:05Z2014-01-17T11:52:05Zhttp://eprints.imtlucca.it/id/eprint/2092This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20922014-01-17T11:52:05ZReputation and uncertainty : a fairly optimistic
society when cheating is totalIn an uncertain world, humans or artificial agents, to cope
with uncertainty, need to communicate and share information to increase the number of their experiences, and consequently their possibility of success. The information shared by agents in a society can have different
nature: accepted evaluations (Image) or reported voices (Reputation). In this work we model a simulative context where information acquisition is strongly affected by false information; in the experiments presented, performed on the RepAge Platform which is a computational module for the management of reputational information, agents can lie or report others’ lies. In this work we explore the effect of informational cheating under extreme setting, focusing to study from one hand, the effect of cheating on the quality achievement when the society is composed by a large amount of liars, and on the other hand, the beliefs formation
and revision dynamics when the informational domain is not reliable. Information accuracy has effect on the market in relation with its trustworthiness; if social information is not reliable communication loses its importance.Walter Quattrociocchiwalter.quattrociocchi@imtlucca.itMario Paolucci2014-01-17T11:42:46Z2014-01-17T11:42:46Zhttp://eprints.imtlucca.it/id/eprint/2091This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20912014-01-17T11:42:46ZOn the effects of reputation in the Internet of Services The Internet of Services is a term used to describe open
global computing infrastructures in which an increasing number of services is made available to users through the Internet. Due to the openness, from the users point, the quality of the services offered can vary a lot and users have to concentrate on choosing the right ones. The choice
of a good service thereby depends on the users’ direct experience (Image), and their ability to acquire information (Reputation), which can be used to update their own evaluations. In this work, we present a set of simulation runs to explore the effect of reputation regarding services delivery in a Service network where information is asymmetrically distributed.Stefan KönigTina BalkeWalter Quattrociocchiwalter.quattrociocchi@imtlucca.itMario PaolucciTorsten Eymann2013-12-20T10:48:18Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2082This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20822013-12-20T10:48:18ZContact of microscopically rough surfaces with graded elasticityMarco Paggimarco.paggi@imtlucca.itGiorgio Zavarise2013-12-13T10:29:04Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2067This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20672013-12-13T10:29:04ZIntroduzione alla termomeccanica dei continuiNei primi cinque capitoli vengono presentate le nozioni fondamentali relative agli sforzi ed alle
deformazioni, la cinematica e la dinamica dei mezzi continui, le equazioni costitutive, i principi
della termodinamica e le equazioni fondamentali della termomeccanica con relative applicazioni,
sia per i solidi che per i fluidi.
Un ultimo capitolo è dedicato alla conduzione del calore nei solidi, con alcune soluzioni in forma
chiusa di problemi monodimensionali.
In appendice si illustrano infine alcuni importanti legami costitutivi non lineari, facendo riferimento
alla plasticità ed alla viscoelasticità.
Marco Paggimarco.paggi@imtlucca.itAlberto Rossani2013-12-12T14:15:48Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2066This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20662013-12-12T14:15:48ZA generalized dimensional analysis approach to fatigue crack growthAlberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-12-12T14:13:09Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2065This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20652013-12-12T14:13:09ZThe mitigation of stress-singularities in Linear ElasticityAlberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-12-12T14:10:00Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2064This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20642013-12-12T14:10:00ZSize-scale effects on the ductility of reinforced concrete structural elementsMauro CorradoMarco Paggimarco.paggi@imtlucca.itAlberto Carpinteri2013-12-12T14:04:43Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2063This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20632013-12-12T14:04:43ZGeneralized representations of fatigue and size-scale effects on the Paris and Wöhler regimesMarco Paggimarco.paggi@imtlucca.itAlberto Carpinteri2013-12-12T14:00:21Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2062This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20622013-12-12T14:00:21ZDelamination vs. shear failure in retrofitted concrete beams and related size-scale effectsAlberto CarpinteriGiuseppe LacidognaMarco Paggimarco.paggi@imtlucca.it2013-12-12T13:19:24Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2060This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20602013-12-12T13:19:24ZFatigue of quasi-brittle materials: a unified interpretation of microstructural size, crack size and size-scale effectsIn this study, a generalized Barenblatt and Botvina dimensional analysis approach to fatigue crack growth is proposed in order to highlight and explain the deviations from the classical power-law equations used to characterize the fatigue behaviour of quasi-brittle materials. According to this theoretical approach, the microstructural-size (related to the volumetric content of fibres in fibre-reinforced concrete), the crack-size, and the size-scale effects on the Paris’ law and the Wöhler equation are presented within a unified mathematical framework. Relevant experimental results taken from the literature are used to confirm the theoretical trends and to determine the values of the incomplete self-similarity exponents. All these information are expected to be useful for the design of experiments, since the role of the different dimensionless numbers governing the phenomenon of fatigue is herein elucidated.Marco Paggimarco.paggi@imtlucca.itGiuseppe Ferro2013-12-12T13:07:39Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2055This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20552013-12-12T13:07:39ZContact mechanics of functionally graded rough surfacesIn this paper the Greenwood and Williamson contact theory for microscopically
rough surfaces is generalized by considering a grading on the elastic modulus of the asperities.
This situation can be representative of surfaces receiving superficial treatments or characterized by
a chemical degradation. The effect of an exponential grading on the applied normal load, on the
relationship between the real contact area and the load, on the plasticity index, as well as on the
contact conductance is illustrated with detailed numerical examples.Marco Paggimarco.paggi@imtlucca.itGiorgio Zavarise2013-12-12T12:59:27Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2054This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20542013-12-12T12:59:27ZA theoretical and numerical approach to the interaction between buckling and resonance instabilities in discrete and continuous mechanical systemsThe paper deals with the interaction between buckling and resonance instabilities of
mechanical systems. Taking into account the effect of geometric nonlinearity in the equations of
motion through the geometric stiffness matrix, the problem is reduced to a generalized eigenproblem
where both the loading multiplier and the natural frequency of the system are unknown. According
to this approach, all the forms of instabilities intermediate between those of pure buckling and pure
forced resonance can be investigated. Numerous examples including discrete mechanical systems
and continuous mechanical systems, such as oscillating deflected beams subjected to a compressive
axial load and oscillating beams subjected to lateral-torsional buckling, are analyzed. The proposed
results provide a new insight in the interpretation of coupled phenomena such as flutter instability of
long-span or high-rise structures.Marco Paggimarco.paggi@imtlucca.itAlberto Carpinteri2013-12-12T11:46:29Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/2053This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20532013-12-12T11:46:29ZA unified mathematical formulation for the asymptotic analysis of singular elastic and electromagnetic fieldsIn the present contribution, the mathematical analogy existing between the singular stress field in elasticity due to antiplane loading and the singular electromagnetic fields in electromagnetism is derived with reference to the problem of isotropic multi-material wedges. These
configurations, where dissimilar sectors converge to the same vertex, are very commonly observed in composite materials and may lead to stress-singularities. The proposed analogy permits to extend several elastic solutions already available in the literature to the analogous electromagnetic problems, without the need of performing new calculations.Marco Paggimarco.paggi@imtlucca.itAlberto CarpinteriRenato Orta2013-12-02T10:25:30Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1981This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19812013-12-02T10:25:30ZA dimensional analysis approach to fatigue in quasi-brittle materialsRIASSUNTO. Nel presente lavoro si propone uno studio di analisi dimensionale del fenomeno della fatica nei
materiali quasi-fragili. Esso costituisce una generalizzazione della metodologia pionieristica proposta da
Barenblatt e Botvina e si prefigge di interpretare le deviazioni dalle leggi di potenza classiche usate per
caratterizzare il comportamento a fatica dei materiali. In base a questo approccio teorico, gli effetti dovuti alla
dimensione microstrutturale (correlabile al contenuto volumetrico di fibre nei calcestruzzi fibrorinforzati), alla
dimensione delle fessure e alla scala strutturale sulla legge di Paris e sulle curve di Wöhler sono discussi in un
contesto matematico unificato. Il modello teorico è confermato dal confronto con rilevanti risultati sperimentali
disponibili in letteratura, usati per determinare i valori degli esponenti di autosimilarità incompleta. Le
informazioni fornite da questa teoria possono essere particolarmente utili per guidare la progettazione di nuovi
esperimenti, dal momento che viene chiarito il ruolo delle diverse variabili adimensionalizzate che governano il
fenomeno della fatica.
ABSTRACT. In this study, a generalized Barenblatt and Botvina dimensional analysis approach to fatigue crack
growth is proposed in order to highlight and explain the deviations from the classical power-law equations used
to characterize the fatigue behaviour of quasi-brittle materials. According to this theoretical approach, the
microstructural-size (related to the volumetric content of fibres in fibre-reinforced concrete), the crack-size, and
the size-scale effects on the Paris’ law and the Wöhler equation are presented within a unified mathematical
framework. Relevant experimental results taken from the literature are used to confirm the theoretical trends
and to determine the values of the incomplete self-similarity exponents. All these information are expected to
be useful for the design of experiments, since the role of the different dimensionless numbers governing the
phenomenon of fatigue is herein elucidated.Marco Paggimarco.paggi@imtlucca.it2013-12-02T10:18:03Z2014-10-09T09:20:24Zhttp://eprints.imtlucca.it/id/eprint/1980This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19802013-12-02T10:18:03ZIl modello della fessura coesiva in trazione e compressione per la valutazione della duttilità degli elementi strutturali in calcestruzzo armatoRIASSUNTO. Il problema della valutazione della duttilità degli elementi in calcestruzzo armato soggetti a flessione o presso-flessione è stato largamente studiato negli ultimi decenni, sia da un punto di vista sperimentale che analitico. Data l’influenza di numerosi parametri di progetto sulla duttilità, tuttavia, è difficile sviluppare un modello in grado di descrivere completamente la risposta meccanica di elementi strutturali, tenendo conto di tutti gli effetti dovuti alla non-linearità dei materiali. Nel passato, in particolare, si è studiato in maniera approfondita l’effetto della classe di duttilità dell’acciaio, mentre il ruolo degli effetti di scala, evidenziato da più campagne sperimentali, non è stato ancora del tutto chiarito. Una delle ragioni principali è l’inadeguatezza dei modelli tradizionali, basati su leggi costitutive tra tensioni e deformazioni. Nel presente lavoro, si propone un nuovo modello basato sul concetto della localizzazione delle deformazioni, capace di descrivere la propagazione della fessura e l’avanzamento del crushing durante il processo di carico. In tale contesto, il comportamento non-lineare del calcestruzzo in compressione è modellato attraverso l’Overlapping Crack Model, modello analogo a quello coesivo valido per la trazione, che descrive la localizzazione delle deformazioni dovuta al danneggiamento del calcestruzzo mediante una compenetrazione del materiale. Con questo nuovo algoritmo è possibile cogliere l’effettiva risposta flessionale di elementi strutturali in calcestruzzo armato al variare della percentuale di armatura e della scala dimensionale. Applicazioni numeriche riguardano l’analisi della risposta post-picco di provini in calcestruzzo soggetti a compressione e la valutazione delle rotazioni plastiche di travi in calcestruzzo armato soggette a flessione su tre punti. Si propone infine un ampio confronto con i risultati di prove sperimentali, con lo scopo di dimostrare la validità del nuovo approccio.
ABSTRACT. The problem of assessing the ductility of reinforced concrete (RC) structural elements in bending or under the action of eccentric forces has been largely investigated from both the experimental and the analytical point of view during the last decades. Since the development of ductility is influenced by several design parameters, it is difficult to develop a predictive model able to fully describe the mechanical behaviour of the structural element. In particular, the role of the size-scale effect, which has been evidenced by some experimental tests, is not yet completely understood. One of the main reasons is the inadequacy of the traditional models based on ad hoc stress-strain constitutive laws. In the present contribution, a new model based on the concept of strain localization is proposed, which is able to describe both cracking and crushing growths during the loading process. In particular, the nonlinear behaviour of concrete in compression is modelled by the Overlapping Crack Model, which describes the strain localization due to crushing by means of a material compenetration. With this numerical algorithm in hand, it is possible to effectively capture the flexural behaviour of RC structural elements by varying the reinforcement percentage and/or the structural size. Numerical applications regard the analysis of the post-peak nonlinear response of concrete specimens subjected to eccentric compression tests and the evaluation of the plastic rotation of RC beams under three-point bending. An extensive comparison with experimental results is also proposed, fully demonstrating the effectiveness of the proposed approach.Alberto CarpinteriAndrea CorradiniGiuseppe ManciniMarco Paggimarco.paggi@imtlucca.it2013-11-29T13:51:34Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1979This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19792013-11-29T13:51:34ZCusp-catastrophe interpretation of the stick-slip behaviour of rough surfacesThe stick-slip instability is a typical manifestation of the nonlinearity of the frictional response of rough surfaces. As recently demonstrated by several researchers, the problem of contact loss is also inherently connected to the stick-slip instability and it has been detected both in elastically soft materials, such as rubber or gelatine, and in elastic stiff materials, such as for earthquake faults. Treating the problem of tangential contact in the framework of micromechanical contact models, the effect of the phenomenon of contact loss on the micro-slip behavior of rough surfaces is herein investigated. To this aim, the stick and slip components of the total applied tangential force and of the total real contact area are properly determined as functions of the total applied tangential force. A comparison with the behavior of smooth surfaces, such as spheres, cylinders and flat surfaces, is presented. Then, simulating the problem of tangential loading followed by a reduction of the applied normal force, it will be shown that the phenomenon of contact loss gives rise to energy release due to snap-back instability in the diagram relating the tangential force to the sliding displacement. This result provides for the very first time an explanation to the phenomenon of stick-slip according to the Catastrophe Theory, in close analogy with the cusp-catastrophe instability of Mode I crack propagation in cohesive solids.Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.itGiorgio Zavarise2013-11-29T13:47:57Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1978This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19782013-11-29T13:47:57ZTowards a unified approach for the analysis of failure modes in FRP-retrofitted concrete beamsThe application of the external reinforcement makes rather complex the scenario of the possible failure modes in reinforced concrete beams retrofitted with FRP. The far more commonly observed failure modes are: (i) edge debonding of the FRP sheet, (ii) intermediate crack induced debonding and (iii) beam failure due to diagonal (shear) crack propagation. In the present study we revisited the competition between all the possible failure modes that can occur in this structural element. To this aim, different analytical models based on linear and non-linear fracture mechanics are developed and harmonized. As a result, useful failure maps are analytically determined, giving, for each failure mode, the critical load of activation as a function of the main parameters governing the problem, i.e. the mechanical properties of the constituent materials, the amount of reinforcement and its bonding length, as well as the size and slenderness of the structural element. The studies presented in this paper are mainly intended to establish guidelines for the future development of these concepts towards a unified mathematical approach. Indeed, once the validity of this unified approach is confirmed, also by comparison with further experimental data, it will be possible to remove some of the simplifying assumptions we used in this analysis to reach a more comprehensive analytical formulation.Marco Paggimarco.paggi@imtlucca.itGiuseppe LacidognaPietro CornettiAlberto Carpinteri2013-11-29T13:35:55Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1977This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19772013-11-29T13:35:55ZA numerical approach to modelling size effects on the flexural ductility of RC beamsThe problem of evaluating the rotation capacity of reinforced concrete (RC) beams in bending has been largely investigated from both the experimental and the analytical point of view during the last decades. Since the development of ductility is influenced by several design parameters, it is difficult to develop a predictive model that can fully describe the mechanical behaviour of RC beams. In particular, the role of the size-scale effect, which has been evidenced by some experimental tests, is not yet completely understood. One of the main reasons is the inadequacy of the traditional models based on ad hoc stress–strain constitutive laws. In the present paper, a new model based on the concept of strain localization is proposed, which is able to describe both cracking and crushing growths in RC beams during the loading process. In particular, the nonlinear behaviour of concrete in compression is modelled by the Overlapping Crack Model, which describes the strain localization due to crushing by means of a material interpenetration. With this algorithm in hand, it is possible to effectively capture the flexural behaviour of RC beams by varying the reinforcement percentage and/or the beam depth. An extensive comparison with experimental results demonstrates the effectiveness of the proposed approach.Alberto CarpinteriMauro CorradoGiuseppe ManciniMarco Paggimarco.paggi@imtlucca.it2013-11-29T13:33:31Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1976This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19762013-11-29T13:33:31ZSize-scale effects on plastic rotational capacity of reinforced concrete beamsA complete numerical algorithm that assumes a strain localization in concrete, both in tension and compression, is proposed for modeling cracking and crushing growths during the loading process of reinforced concrete beams in bending. With this algorithm based on nonlinear fracture mechanics models, it is possible to investigate the effects of the main mechanical and geometrical parameters on the rotational capacity with particular regard to the reinforcement percentage and the element size. A comparison with experimental results demonstrates the effectiveness of the proposed approach for a wide range of reinforcement percentages and beam depths. The obtained results show that the prescriptions concerning the admissible plastic rotations provided by the existing design formulas are not conservative in the case of large structural sizes. To overcome such a drawback, a new design diagram is proposed for practical purposes.Alberto CarpinteriMauro CorradoGiuseppe ManciniMarco Paggimarco.paggi@imtlucca.it2013-11-29T12:57:06Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1975This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19752013-11-29T12:57:06ZA top-down approach for the prediction of hardness and toughness of hierarchical materials Many natural and man-made materials exhibit structure over more than one length scale. In this paper, we deal with hierarchical grained composite materials that have recently been designed to achieve superior hardness and toughness as compared to their traditional counterparts. Their nested structure, where meso-grains are recursively composed of smaller and smaller micro-grains at the different scales with a fractal-like topology, is herein studied from a hierarchical perspective. Considering a top-down approach, i.e. from the largest to the smallest scale, we propose a recursive micromechanical model coupled with a generalized fractal mixture rule for the prediction of hardness and toughness of a grained material with n hierarchical levels. A relationship between hardness and toughness is also derived and the analytical predictions are compared with experimental data. Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-11-29T12:22:03Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1974This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19742013-11-29T12:22:03ZA unified interpretation of the power laws in fatigue and the analytical correlations between cyclic properties of engineering materials A phenomenological description of the fatigue life of engineering components can be given either by plotting the applied stress range as a function of the total number of cycles to failure, i.e., according to the Wöhler’s curve, or, after the advent of fracture mechanics, by plotting the crack growth rate in terms of the stress-intensity factor range, i.e., using the Paris’ curve. In this work, an analytical approach is proposed for the study of the relationships existing between the Wöhler’s and the Paris’ representations of fatigue. According to dimensional analysis and the concepts of complete and incomplete self-similarity, generalized Wöhler and Paris equations are determined, which provide a rational interpretation to a majority of empirical power-law criteria used in fatigue. Then, by integration of the generalized Paris’ law, the relationship between the aforementioned generalized representations of fatigue is established, providing the link between the cumulative fatigue damage and the fatigue crack propagation approaches. Moreover, paying attention to the limit points defining the range of validity of the classical Wöhler and Paris power-law relationships, whose co-ordinates are referred to as cyclic or fatigue properties, alternative expressions for the classical laws of fatigue are proposed. Finally, the correlations between such fatigue properties are determined according to theoretical arguments, giving an interpretation of the empirical trends observed in the material property charts. Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-11-29T12:09:25Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1973This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19732013-11-29T12:09:25ZAsymptotic analysis in Linear Elasticity: from the pioneering studies by Wieghardt and Irwin until today The asymptotic analysis of the stress distribution around an elastic wedge-shaped domain is one of the most fundamental problems in Linear Elasticity. In occasion of the century anniversary of the pioneering paper by Wieghardt on splitting and cracking of elastic bodies, and of the half-a-century anniversary of the Irwin’s paper on the analysis of stresses and strains near the end of a crack, we propose a review of the most important contributions leading to fundamental advances in this research field. Special focus will be given to the epistemological steps towards a full appreciation of the mathematical and engineering relevance of the stress-singularities. We also provide the reader with a review of the geometrical configurations and mechanical conditions that can relieve or remove the singularities, including: re-entrant corners; power-law hardening constitutive laws; fractal cracks; multi-material junctions and wedges; nonhomogeneous materials. Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-11-29T11:58:45Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1972This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19722013-11-29T11:58:45ZThe overlapping crack model for uniaxial and eccentric concrete compression testsAn analytical/numerical model, referred to as the overlapping crack model, is proposed in the present paper for the analysis of the mechanical behaviour of concrete in compression. Starting from the experimental evidence of strain localisation in uniaxial compression tests, the present model is based on a couple of constitutive laws for the description of the compression behaviour of concrete: a stress–strain law until the achievement of the compression strength and a stress–displacement relationship describing the post-peak softening behaviour. The displacement would correspond to a fictitious interpenetration and therefore the concept of overlapping crack in compression is analogous to the cohesive crack in tension. According to this approach, the slenderness and size-scale effects of concrete specimens tested under uniaxial compression are interpreted from an analytical point of view. Then, implementing the overlapping crack model into the finite element method, eccentric compression tests are numerically simulated and compared with experimental results. The influence of the size-scale, the specimen slenderness, as well as the degree of load eccentricity, is discussed in detail, quantifying the effect of each parameter on the ductility of concrete specimens.Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.itMauro CorradoGiuseppe Mancini2013-11-29T11:55:29Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1971This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19712013-11-29T11:55:29ZFractal and multifractal approaches for the analysis of crack-size dependent scaling laws in fatigue The enhanced ability to detect and measure very short cracks, along with a great interest in applying fracture mechanics formulae to smaller and smaller crack sizes, has pointed out the so-called anomalous behavior of short cracks with respect to their longer counterparts. The crack-size dependencies of both the fatigue threshold and the Paris’ constant C are only two notable examples of these anomalous scaling laws. In this framework, a unified theoretical model seems to be missing and the behavior of short cracks can still be considered as an open problem. In this paper, we propose a critical reexamination of the fractal models for the analysis of crack-size effects in fatigue. The limitations of each model are put into evidence and removed. At the end, a new generalized theory based on fractal geometry is proposed, which permits to consistently interpret the short crack-related anomalous scaling laws within a unified theoretical formulation. Finally, this approach is herein used to interpret relevant experimental data related to the crack-size dependence of the fatigue threshold in metals. Marco Paggimarco.paggi@imtlucca.itAlberto Carpinteri2013-11-29T11:52:17Z2014-10-09T09:20:25Zhttp://eprints.imtlucca.it/id/eprint/1970This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19702013-11-29T11:52:17ZA fractal interpretation of size-scale effects on strength, friction and fracture energy of faults Experimental results indicate that large faults involved in earthquakes possess low strength, low friction coefficient and high fracture energy, in comparison with data obtained according to small scale laboratory tests on the same material. The reasons for such an unexpected anomalous behaviour have been the subject of several researches in the past and are still under debate in the Scientific Community. In this note, we propose a unifying interpretation of these size-scale effects according to fractal geometry, which represents the proper mathematical framework for the analysis of the multi-scale properties of rough surfaces in contact. This contribution sheds a new light on the non-linear properties of friction and on the understanding the fundamental physics governing the scaling of the mechanical properties in geophysics from the laboratory to a planetary scale. Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-11-07T13:17:48Z2013-11-07T13:17:48Zhttp://eprints.imtlucca.it/id/eprint/1888This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18882013-11-07T13:17:48ZGroup Recommendation with Automatic Identification of Users CommunitiesRecommender systems usually propose items to single users. However, in some domains like Mobile IPTV or Satellite Systems it might be impossible to generate a program schedule for each user, because of bandwidth limitations. A few approaches were proposed to generate group recommendations. However, these approaches take into account that groups of users already exist and no recommender system is able to detect intrinsic users communities. This paper describes an algorithm that detects groups of users whose preferences are similar and predicts recommendations for such groups. Groups of different granularities are generated through a modularity-based Community Detection algorithm, making it possible for a content provider to explore the trade off between the level of personalization of the recommendations and the number of channels. Experimental results show that the quality of group recommendations increases linearly with the number of groups created.Ludovico BorattoSalvatore CartaAlessandro Chessaalessandro.chessa@imtlucca.itMaurizio AgelliM. Laura Clemente2013-11-07T12:05:18Z2014-09-02T09:50:59Zhttp://eprints.imtlucca.it/id/eprint/1887This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18872013-11-07T12:05:18ZWeighted networks and community detection: planning productive districts in SardiniaWe study the patterns of the communities of workers and students of Sardinia, by applying grouping methodologies based on the characterization of the Sardinian commuting system as a complex weighted network. The algorithm is based on a heuristic method able to optimize a quality function called modularity, as proposed by Newman et al. [01]. Its adoption allows us to detect productive basins geographically located, as composed by towns and their territories showing a certain degree of similarity. We compare the spatial distributions of communities with relevant historical and provincial boundaries, investigate on their discrepancies and correspondences, and propose possible perspectives for local policy making and planning.Simone CaschiliAndrea De MontisAlessandro Chessaalessandro.chessa@imtlucca.itGiancarlo Deplano2013-11-07T10:58:11Z2013-11-07T10:58:11Zhttp://eprints.imtlucca.it/id/eprint/1882This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18822013-11-07T10:58:11ZComplex Networks Analysis of Commuting: Recent Advances and a Research AgendaThe emerging new science of networks is providing an elegant paradigm for the characterization of the broad area of complex systems. New research perspectives have been opened in the study of many real phenomena and processes, and recently fields like urban, regional, and environmental sciences have gained new insights from the tools provided by network science. The complex networks analysis (CNA) becomes a useful framework in these fields to disentangle problems of a complex and unpredictable nature.
At the end of the last millennium, the availability of large data sets and the parallel explosion of computer processing power have made a systematic and intensive application of CNA to the study of very large networks(Pastor-Satorras and Vespignani 2004; Albert and Barabási 2002) possible. According to CNA, complex behaviours are signalled by the emergence of some characteristics that can be featured in terms of statistical propertiesAndrea De MontisAlessandro Chessaalessandro.chessa@imtlucca.itMichele CampagnaSimone CaschiliGiancarlo Deplano2013-10-04T10:07:03Z2013-10-04T10:07:03Zhttp://eprints.imtlucca.it/id/eprint/1822This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18222013-10-04T10:07:03ZHow accurate are polymer models in the analysis of Förster resonance energy transfer experiments on proteins?Single molecule Förster resonance energy transfer (FRET) experiments are used to infer the properties of the denatured state ensemble (DSE) of proteins. From the measured average FRET efficiency, 〈E〉, the distance distribution P(R) is inferred by assuming that the DSE can be described as a polymer. The single parameter in the appropriate polymer model (Gaussian chain, wormlike chain, or self-avoiding walk) for P(R) is determined by equating the calculated and measured 〈E〉. In order to assess the accuracy of this “standard procedure,” we consider the generalized Rouse model (GRM), whose properties [〈E〉 and P(R)] can be analytically computed, and the Molecular Transfer Model for protein L for which accurate simulations can be carried out as a function of guanadinium hydrochloride (GdmCl) concentration. Using the precisely computed 〈E〉 for the GRM and protein L, we infer P(R) using the standard procedure. We find that the mean end-to-end distance can be accurately inferred (less than 10% relative error) using 〈E〉 and polymer models for P(R). However, the value extracted for the radius of gyration (Rg) and the persistence length (lp) are less accurate. For protein L, the errors in the inferred properties increase as the GdmCl concentration increases for all polymer models. The relative error in the inferred Rg and lp, with respect to the exact values, can be as large as 25% at the highest GdmCl concentration. We propose a self-consistency test, requiring measurements of 〈E〉 by attaching dyes to different residues in the protein, to assess the validity of describing DSE using the Gaussian model. Application of the self-consistency test to the GRM shows that even for this simple model, which exhibits an order→disorder transition, the Gaussian P(R) is inadequate. Analysis of experimental data of FRET efficiencies with dyes at several locations for the cold shock protein, and simulations results for protein L, for which accurate FRET efficiencies between various locations were computed, shows that at high GdmCl concentrations there are significant deviations in the DSE P(R) from the Gaussian model.Edward P. O’BrienGreg Morrisongreg.morrison@imtlucca.itBernard R. BrooksD. Thirumalai2013-10-04T10:03:20Z2014-12-18T15:39:58Zhttp://eprints.imtlucca.it/id/eprint/1821This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18212013-10-04T10:03:20ZSemiflexible chains in confined spacesWe develop an analytical method for studying the properties of a noninteracting wormlike chain (WLC) in confined geometries. The mean-field-like theory replaces the rigid constraints of confinement with average constraints, thus allowing us to develop a tractable method for treating a WLC wrapped on the surface of a sphere, and fully encapsulated within it. The efficacy of the theory is established by reproducing the exact correlation functions for a WLC confined to the surface of a sphere. In addition, the coefficients in the free energy are exactly calculated. We also describe the behavior of a surface-confined chain under external tension that is relevant for single molecule experiments on histone-DNA complexes. The force-extension curves display spatial oscillations, and the extension of the chain, whose maximum value is bounded by the sphere diameter, scales as f−1 at large forces, in contrast to the unconfined chain that approaches the contour length as f−1∕2. A WLC encapsulated in a sphere, that is relevant for the study of the viral encapsulation of DNA, can also be treated using the mean-field approach. The predictions of the theory for various correlation functions are in excellent agreement with Langevin simulations. We find that strongly confined chains are highly structured by examining the correlations using a local winding axis. The predicted pressure of the system is in excellent agreement with simulations but, as is known, is significantly lower than the pressures seen for DNA packaged in viral capsids.Greg Morrisongreg.morrison@imtlucca.itD. Thirumalai2013-10-04T09:56:41Z2013-11-21T12:19:10Zhttp://eprints.imtlucca.it/id/eprint/1820This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18202013-10-04T09:56:41ZRefolding dynamics of stretched biopolymers upon force quenchSingle-molecule force spectroscopy methods can be used to generate folding trajectories of biopolymers from arbitrary regions of the folding landscape. We illustrate the complexity of the folding kinetics and generic aspects of the collapse of RNA and proteins upon force quench by using simulations of an RNA hairpin and theory based on the de Gennes model for homopolymer collapse. The folding time, τF, depends asymmetrically on δfS = f S − f m and δf Q = f m − f Q where f S (f Q) is the stretch (quench) force and f m is the transition midforce of the RNA hairpin. In accord with experiments, the relaxation kinetics of the molecular extension, R(t), occurs in three stages: A rapid initial decrease in the extension is followed by a plateau and finally, an abrupt reduction in R(t) occurs as the native state is approached. The duration of the plateau increases as λ = τ Q/τ F decreases (where τ Q is the time in which the force is reduced from f S to f Q). Variations in the mechanisms of force-quench relaxation as λ is altered are reflected in the experimentally measurable time-dependent entropy, which is computed directly from the folding trajectories. An analytical solution of the de Gennes model under tension reproduces the multistage stage kinetics in R(t). The prediction that the initial stages of collapse should also be a generic feature of polymers is validated by simulation of the kinetics of toroid (globule) formation in semiflexible (flexible) homopolymers in poor solvents upon quenching the force from a fully stretched state. Our findings give a unified explanation for multiple disparate experimental observations of protein folding.Changbong HyeonGreg Morrisongreg.morrison@imtlucca.itDavid L. PincusD. Thirumalai2013-10-04T09:45:11Z2013-10-04T09:45:11Zhttp://eprints.imtlucca.it/id/eprint/1819This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18192013-10-04T09:45:11ZInfochemistry: Encoding Information as Optical Pulses Using Droplets in a Microfluidic Device This article describes a new procedure for generating and transmitting a message—a sequence of optical pulses—by aligning a mask (an opaque sheet containing transparent “windows”) below a microfluidic channel in which flows an opaque continuous fluid containing transparent droplets. The optical mask encodes the message as a unique sequence of windows that can transmit or block light; the flow of transparent droplets in the channel converts this message into a sequence of optical pulses. The properties of the windows on the mask (e.g., their size, wavelength of transmittance, orientation of polarization) determine the information carried in these optical pulses (e.g., intensity, color, polarization). The structure of a transmitted signal depends on the number and spacing of droplets in the channel. Fourier transformation can deconvolve superimposed signals created by the flow of multiple droplets into the message that a single droplet would transmit. The research described in this contribution explores a new field at the intersection of chemistry, materials science, and information technology: infochemistry. Michinao HashimotoJi FengRoger L. YorkAudrey K. EllerbeeGreg Morrisongreg.morrison@imtlucca.itSamuel W. Thomas IIIL. MahadevanGeorge M. Whitesides2013-09-17T13:11:58Z2013-09-17T13:11:58Zhttp://eprints.imtlucca.it/id/eprint/1796This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17962013-09-17T13:11:58ZThe Weight-Decay Technique in Learning from Data: An Optimization Point of ViewThe technique known as “weight decay” in the literature about learning from data is investigated using tools from regularization theory. Weight-decay regularization is compared with Tikhonov’s regularization of the learning problem and with a mixed regularized learning technique. The accuracies of suboptimal solutions to weight-decay learning are estimated for connectionistic models with a-priori fixed numbers of computational units.Giorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T13:11:35Z2013-09-17T13:11:35Zhttp://eprints.imtlucca.it/id/eprint/1786This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17862013-09-17T13:11:35ZSuboptimal Solutions to Network Team Optimization ProblemsSmoothness of the solutions to network team optimization problems with statistical information structure is investigated. Suboptimal solutions expressed as linear combinations of elements from sets of basis functions containing adjustable parameters are considered. Estimates of their accuracy are derived, for basis functions represented by sinusoids with variable frequencies and phases and
Gaussians with variable centers and widthss.Giorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T13:11:21Z2013-09-17T13:11:21Zhttp://eprints.imtlucca.it/id/eprint/1782This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17822013-09-17T13:11:21ZStructural Properties of Stochastic Dynamic Concave Optimization Problems and Approximations of the Value and Optimal Policy FunctionsGiorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T13:11:08Z2013-09-17T13:11:08Zhttp://eprints.imtlucca.it/id/eprint/1777This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17772013-09-17T13:11:08ZSmoothness and Approximation of Optimal Decision Strategies in Team Optimization ProblemsGiorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T13:10:48Z2013-09-17T13:10:48Zhttp://eprints.imtlucca.it/id/eprint/1776This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17762013-09-17T13:10:48ZRegularization and Suboptimal Solutions in Learning from DataSupervised learning from data is investigated from an optimization viewpoint. Ill-posedness issues of the learning problem are discussed and its Tikhonov, Ivanov, Phillips, and Miller regularizations are analyzed. Theoretical features of the optimization problems associated with these regularization techniques and their use in learning tasks are considered. Weight-decay learning is investigated, too. Exploiting properties of the functionals to be minimized in the various regularized problems, estimates are derived on the accuracy of suboptimal solutions formed by linear combinations of n-tuples of computational units, for values of n smaller than the number of data.Giorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T13:10:30Z2013-09-17T13:10:30Zhttp://eprints.imtlucca.it/id/eprint/1770This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17702013-09-17T13:10:30ZLipschitz Continuity of the Solutions to Team Optimization Problems RevisitedSufficient conditions for the existence and Lipschitz
continuity of optimal strategies for static team optimization problems are studied. Revised statements and proofs of some results in “Kim K.H., Roush F.W., Team Theory. Ellis Horwood Limited Publishers, Chichester, UK, 1987” are presented.Giorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T07:40:37Z2013-09-17T07:40:37Zhttp://eprints.imtlucca.it/id/eprint/1744This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17442013-09-17T07:40:37ZAccuracy of Suboptimal Solutions to Kernel Principal Component AnalysisFor Principal Component Analysis in Reproducing Kernel Hilbert Spaces (KPCA), optimization over sets containing only linear combinations of all n-tuples of kernel functions is investigated, where n is a positive integer smaller than the number of data. Upper bounds on the accuracy in approximating the optimal solution, achievable without restrictions on the number of kernel functions, are derived. The rates of decrease of the upper bounds for increasing number n of kernel functions are given by the summation of two terms, one proportional to n −1/2 and the other to n −1, and depend on the maximum eigenvalue of the Gram matrix of the kernel with respect to the data. Primal and dual formulations of KPCA are considered. The estimates provide insights into the effectiveness of sparse KPCA techniques, aimed at reducing the computational costs of expansions in terms of kernel units. Giorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-09-17T07:40:01Z2013-09-17T07:40:01Zhttp://eprints.imtlucca.it/id/eprint/1746This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/17462013-09-17T07:40:01ZApproximate Dynamic Programming by Value-Function Approximation via Variable-Basis SchemesGiorgio Gneccogiorgio.gnecco@imtlucca.itMarcello Sanguineti2013-07-08T13:58:37Z2013-07-08T14:02:29Zhttp://eprints.imtlucca.it/id/eprint/1630This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/16302013-07-08T13:58:37ZMATLAB Applications of Trading Rules and GARCH with Wavelets AnalysisIn this paper we provide MATLAB routines for two major used trading rules, the moving average indicator and MACD oscillator as also the GARCH univariate regression with Monte Carlo simulations and wavelets decomposition, which is an update of an older algorithm Eleftherios Giovaniseleftherios.giovanis@imtlucca.it2013-07-08T13:49:35Z2014-01-24T14:24:24Zhttp://eprints.imtlucca.it/id/eprint/1629This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/16292013-07-08T13:49:35ZMATLAB Routine for Bootstrapping Statistic Hypothesis for Calendar Effects in Stock ReturnsThis paper presents a programming routine in MATLAB software for applications in calendar effects or anomalies in stock returns. The calendar effects which are tested is the turn-of-the-month, the day-of-the-Week, the month-of-the-Year and the semi-month effect. Eleftherios Giovaniseleftherios.giovanis@imtlucca.it2013-07-08T13:44:34Z2014-01-24T14:24:45Zhttp://eprints.imtlucca.it/id/eprint/1628This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/16282013-07-08T13:44:34ZThe Month-of-The-Year Effect: Evidence from GARCH Models in Fifty Five Stock MarketsThis paper studies the month of the year effect, where January effect presents positive and the highest returns of the other months of the year. In order to investigate the specific calendar effect in global level, fifty-five stock market indices from fifty-one countries are examined. Symmetric GARCH models are applied and based on asymmetries tests asymmetric GARCH models are estimated. The main findings of this study is that a December effect is found on twenty stock markets, with higher returns on the specific month, while February effect is presented in nine stock markets, followed by January and April effects in seven and six stock markets respectively. These patterns provide positive and highest returns on the mentioned months, while a pattern where a specific month gives a persistence signal of negative returns couldn’t be found. Eleftherios Giovaniseleftherios.giovanis@imtlucca.it2013-07-08T13:33:12Z2014-01-24T14:25:00Zhttp://eprints.imtlucca.it/id/eprint/1627This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/16272013-07-08T13:33:12ZARIMA and Neural Networks: An Application to the Real GNP Growth Rate and the Unemployment Rate of U.S.A.This paper examines the estimation and forecasting performance of ARIMA models in comparison with some of the most popular and common models of neural networks. Specifically we provide the estimation results of AR-GRNN (Generalized regression neural networks) and the AR-RBF (Radial basis function). We show that neural networks models outperform the ARIMA forecasting. We found that the best model in the case of real US GNP is the AR-GRNN and for US unemployment rate is the AR-MLP. Eleftherios Giovaniseleftherios.giovanis@imtlucca.it2013-07-08T13:17:54Z2014-01-24T14:25:40Zhttp://eprints.imtlucca.it/id/eprint/1626This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/16262013-07-08T13:17:54ZHealth Expenditures in Greece: A Multiple Least Squares Regression and Cointegration Analysis Using Bootstrap Simulation in EVIEWSThis paper examines the factors that are contribute at the most explained and efficient way to health expenditures in Greece. Two methods are applied. Multiple regressions and vector error correction models are estimated, as also unit root tests applied to define in which order variables are stationary. Because the available data are yearly and capture a small period from 1985-2006, so the sample is small, a bootstrap simulation is applied, to improve the estimations.Eleftherios Giovaniseleftherios.giovanis@imtlucca.it2013-02-15T08:10:34Z2013-03-12T14:57:38Zhttp://eprints.imtlucca.it/id/eprint/1467This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14672013-02-15T08:10:34ZDevelopment of a methodology for the computation of a near-optimal explicit control law for nonlinear systems that are subject to constraints coupling fuzzy model predictive control and multi-parametric programmingPantelis Sopasakispantelis.sopasakis@imtlucca.itPanagiotis Patrinospanagiotis.patrinos@imtlucca.itHaralambos Sarimveis2013-01-24T15:10:05Z2013-03-12T14:57:38Zhttp://eprints.imtlucca.it/id/eprint/1468This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14682013-01-24T15:10:05ZA Model Predictive Control Approach for Optimal Drug AdministrationThe barriers between systems engineering and medicine are slowly eroding as recently it has become evident that medicine has a lot to gain by systems technology. In particular, the drug administration problem be cast as a control engineering problem, where the objective is to keep the drug concentration at certain organs in the body close to desired set-points. A number of constraints render the problem rather challenging. For example, hard constraints may be posed on the drug concentration in blood, because a higher than a certain limit concentration may render the drug effects adverse and toxic. In this paper we show that a popular method for tackling chemical engineering control problems can be used for determining the optimal drug administration. Specifically, the Model Predictive Control (MPC) technology is used for taking optimal decisions regarding of drug concentration in the human body, while incorporating constraints on both drug concentration and drug infusion rate. Haralambos SarimveisPantelis Sopasakispantelis.sopasakis@imtlucca.itAntreas AfantitisGeorgia Melagraki2013-01-24T10:34:13Z2013-03-12T14:57:38Zhttp://eprints.imtlucca.it/id/eprint/1466This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14662013-01-24T10:34:13ZFormulation and solution of an optimal control problem where the input values are restricted on a finite setPantelis Sopasakispantelis.sopasakis@imtlucca.itHaralambos Sarimveis2013-01-24T10:16:26Z2013-03-12T14:57:38Zhttp://eprints.imtlucca.it/id/eprint/1465This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14652013-01-24T10:16:26ZForecasting of the technological and market evolution of QDs using an ARIMA stochastic processPantelis Sopasakispantelis.sopasakis@imtlucca.itA. GolnasN. ApratzanisC.A. Charitides2012-10-19T10:29:28Z2012-10-19T10:29:28Zhttp://eprints.imtlucca.it/id/eprint/1416This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14162012-10-19T10:29:28Z[rezension von] Giovanni Moro: anni SettantaFiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-18T13:27:02Z2012-10-18T13:45:12Zhttp://eprints.imtlucca.it/id/eprint/1412This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14122012-10-18T13:27:02Z[recensione a] Eric A. Johnson, Karl-Heinz Reuband, La Germania sapeva. Terrore, genocidio, vita quotidiana. Una storia oraleFiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-17T14:12:30Z2012-10-17T15:31:18Zhttp://eprints.imtlucca.it/id/eprint/1408This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14082012-10-17T14:12:30ZStoria del confine orientale [recensione]Fiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-17T12:48:23Z2012-10-17T12:48:23Zhttp://eprints.imtlucca.it/id/eprint/1404This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14042012-10-17T12:48:23ZViolenza, occupazione, Resistenza e collaborazione in Trentino e nella zona d'operazione delle Prealpi. Appunti corsari a partire da alcune recenti pubblicazioniFiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-15T12:26:11Z2012-10-17T15:31:47Zhttp://eprints.imtlucca.it/id/eprint/1402This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14022012-10-15T12:26:11ZRileggere gli anni '80 attraverso l'attivismo radicale [recensione a: Beppe De Sario, Resistenze innaturali. Attivismo radicale nell'Italia degli anni '80]Fiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-09-24T13:28:00Z2013-03-07T12:56:25Zhttp://eprints.imtlucca.it/id/eprint/1373This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13732012-09-24T13:28:00ZTransformational Verification of Linear Temporal LogicWe present a new method for verifying Linear Temporal
Logic (LTL) properties of finite state reactive systems based on logic programming and program transformation. We encode a finite state system and an LTL property which we want to verify as a logic program on infinite lists. Then we apply a verification method consisting of two steps. In the first step we transform the logic program that encodes the given system and the given property into a new program belonging to the class of the so-called linear monadic !-programs (which are stratified, linear recursive programs defining nullary predicates or unary predicates on infinite lists). This transformation is performed by applying rules that preserve correctness. In the second step we verify the property of interest by using suitable proof rules for linear monadic !-programs. These proof rules can be encoded as a logic program which always terminates, if evaluated by using tabled resolution. Although our method uses standard
program transformation techniques, the computational complexity of the derived verification algorithm is essentially the same as the one of the Lichtenstein-Pnueli algorithm [9], which uses sophisticated ad-hoc techniques.Alberto PettorossiMaurizio ProiettiValerio Sennivalerio.senni@imtlucca.it2012-09-24T12:48:57Z2013-03-07T12:56:25Zhttp://eprints.imtlucca.it/id/eprint/1371This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13712012-09-24T12:48:57ZA Folding Rule for Eliminating Existential Variables from Constraint Logic Programs The existential variables of a clause in a constraint logic program are the variables which occur in the body of the clause and not in its head. The elimination of these variables is a transformation technique which is often used for improving program efficiency and verifying program properties. We consider a folding transformation rule which ensures the elimination of existential variables and we propose an algorithm for applying this rule in the case where the constraints are linear inequations over rational or real numbers. The algorithm combines techniques for matching terms modulo equational theories and techniques for solving systems of linear inequations. Through some examples we show that an implementation of our folding algorithm has a good performance in practice. Valerio Sennivalerio.senni@imtlucca.itAlberto PettorossiMaurizio Proietti2012-07-02T13:40:26Z2013-04-16T14:20:56Zhttp://eprints.imtlucca.it/id/eprint/1301This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13012012-07-02T13:40:26ZVisual Encounters: Africa, Oceania and Modern ArtSilvia Loretisilvia.loreti@imtlucca.it2012-07-02T13:34:39Z2013-04-16T14:20:56Zhttp://eprints.imtlucca.it/id/eprint/1300This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13002012-07-02T13:34:39ZGiorgio De Chirico. La fabrique des rêvesSilvia Loretisilvia.loreti@imtlucca.it2012-07-02T13:11:34Z2013-04-16T14:20:56Zhttp://eprints.imtlucca.it/id/eprint/1297This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12972012-07-02T13:11:34ZEnigmes et peintures métaphysiques. L'invention d'une rhétoriqueIssues des souvenirs personnels de l'artiste, les énigmes architecturales de Chirico sont aussi le fruit d'une tradition classique, d'une mémoire collective. Hantés par la figure d'Ariane, rythmés par le leitmotiv des arcades, ces paysages forment un espace métaphysique, précis et onirique à la fois, où les statues et les ombres ont pris la place des vivants. Progressivement, ces paysages se referment pour devenir des intérieurs dans lesquels les objets changent de fonction et de sens.Silvia Loretisilvia.loreti@imtlucca.it2012-06-29T12:41:07Z2013-04-16T14:20:56Zhttp://eprints.imtlucca.it/id/eprint/1295This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12952012-06-29T12:41:07ZAffair of the Statuettes Reexamined: Picasso and Apollinaire’s role in the famed Louvre theftSilvia Loretisilvia.loreti@imtlucca.it2012-05-16T10:38:19Z2012-05-17T08:57:30Zhttp://eprints.imtlucca.it/id/eprint/1271This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12712012-05-16T10:38:19ZChe cosa resta: razionalità e tecnica a partire dal pensiero di Ernst BlochLinda Bertellilinda.bertelli@imtlucca.it2012-03-28T12:54:38Z2012-04-03T07:52:37Zhttp://eprints.imtlucca.it/id/eprint/1251This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12512012-03-28T12:54:38ZLocalization of Shipping Containers in Ports and Terminals Using Wireless Sensor NetworksThe most advanced logistics solutions that are currently adopted in ports and terminals use RFID- and GPS-based technologies to identify and localize shipping containers in the yard. Nevertheless, because of the limits of these techniques, the position of containers is still affected by some errors or it cannot be determined in real-time. We propose a non-conventional approach where the position of containers can be continuously determined by means of a wireless sensor network. Each container is equipped with a number of nodes that use wireless communication to detect neighbor containers. At the base station, geometrical constraints and proximity data are combined together to determine the relative positions of containers.Stefano Abbatestefano.abbate@alumni.imtlucca.itMarco AvvenutiPaolo CorsiniAlessio Vecchio2012-03-26T11:31:43Z2012-07-05T10:08:35Zhttp://eprints.imtlucca.it/id/eprint/1242This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12422012-03-26T11:31:43ZThe dynamics of delinking in industrial emissions: The role of productivity, trade and R&DThis paper provides new empirical evidence on delinking / Environmental Kuznets Curves (EKC) for greenhouse gases and other air pollutant emissions in Italy. We analysed a panel dataset based on the Italian NAMEA for 1990-2005 with a specific focus on industry. We integrated the emission-income NAMEA with data on trade openness and R&D expenditures. The highly disaggregated dataset provides a large heterogeneity and can help to overcome the shortcomings of the usual approach to EKC based on cross-country data. We use in this paper CO2, SOx, NOx and PM10 as objects of investigation. We use as empirical models of reference both a standard EKC model and a STIRPAT/IPAT model. Our results show that looking at sector evidence, both decupling and then eventually re-coupling trends could emerge along the path of economic development. The analysis of how stagnation periods affect environmental performances is also of interest.Giovanni Maringiovanni.marin@alumni.imtlucca.itMassimiliano Mazzanti2012-03-07T10:51:31Z2013-09-30T12:32:32Zhttp://eprints.imtlucca.it/id/eprint/1229This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12292012-03-07T10:51:31ZA sub-optimal second order sliding mode controller for systems with saturating actuatorsIn this technical note, the problem of the possible saturation of the continuous control variable in the sub-optimal second order sliding mode controller, applied to systems with saturating actuators, is addressed. It is proved that during the sliding phase, if basic assumptions are made, the continuous control variable never saturates. On the contrary, during the reaching phase, the presence of saturating actuators can make the steering of the sliding variable to zero in a finite time not always guaranteed. In the present technical note, the original algorithm is modified in order to solve this problem: a new strategy is proposed, which proves to be able to steer the sliding variable to zero in a finite time in spite of the presence of saturating actuators.Antonella FerraraMatteo Rubagotti2012-03-06T14:31:56Z2013-09-30T12:26:54Zhttp://eprints.imtlucca.it/id/eprint/1223This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12232012-03-06T14:31:56ZA sub-optimal second order sliding mode controller for current-fed induction motorsA second order sliding mode controller for current-fed induction motors is proposed in this paper. The design of the controller is based on a reduced order model of the machine, and the control variables are non-discontinuous currents, obtained integrating a discontinuous auxiliary control signal. The phase voltages are then generated using a current regulated pulse width modulation inverter, while the rotor flux value is obtained by means of a simple observer. The convergence properties of the proposed control strategy are studied in the paper, and verified in simulation.Antonella FerraraMatteo Rubagotti2012-03-06T13:42:41Z2013-09-30T12:26:11Zhttp://eprints.imtlucca.it/id/eprint/1222This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12222012-03-06T13:42:41ZDiagnosis and prognosis of automotive systems: motivations, history and some resultsThis paper presents an overview of diagnostic needs and methodologies in the automotive field. The field of automotive engineering has seen an explosion in the presence of electronic components and systems on-board vehicles since the 1970s. This growth was initially motivated by the introduction of emissions regulations that led to the widespread application of electronic engine controls. A secondary but important consequence of these developments was the adoption of on-board diagnostics regulations aimed at insiring that emission control systems remained functional for a prescribed period of time (or vehicle mileage). In addition, the presence of micro-controllers on-board the vehicle led to a proliferation of functions implemented through electronic systems and related software, related to safety and customer convenience, creating the need for more sophisticated on-board diagnostics. Today, a significant percentage of the software code in an automobile is devoted to diagnostic functions. This paper presents an overview of diagnostic needs and requirements in the automotive industry, illustrates some of the challenges that are associated with satisfying these requirements and proposes some future directions, in particular with respect to prognostics.Giorgio RizzoniSimona OnoriMatteo Rubagotti2012-03-06T13:33:24Z2013-09-30T12:27:16Zhttp://eprints.imtlucca.it/id/eprint/1221This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12212012-03-06T13:33:24ZA dynamic obstacle avoidance strategy for a mobile robot based on sliding mode controlIn this paper, a dynamic obstacle avoidance strategy for mobile robots is proposed. The strategy consists of two key elements: an on-line reference generator and a control scheme to make the robot track the reference signals so as to reach a pre-specified goal point. To generate the online reference signals, a harmonic potential field for dynamic environments is exploited. The potential field is modified on-line, in order to make the robot avoid the collision with obstacles which move along non a-priori known trajectories with timevarying speed. The proposed multi-level sliding mode controller is capable of making the robot move tracking the prescribed reference signals determined by the trajectory generator. The simulation results confirm the good performances of this approach.Antonella FerraraMatteo Rubagotti2012-03-06T13:28:10Z2013-09-30T12:25:32Zhttp://eprints.imtlucca.it/id/eprint/1220This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12202012-03-06T13:28:10ZRobust model predictive control of continuous-time sampled-data nonlinear systems with integral sliding modeA hierarchical Nonlinear Model Predictive Control (NMPC) scheme with guaranteed Input-to-State-practical- Stability (ISpS) is proposed. The controller is formed by an Integral Sliding Mode (ISM) controller and a NMPC one. The ISM, relying on the knowledge of the nominal continuous-time model of the system and of the piecewise constant control signal generated by the NMPC produces a control action aimed at reducing the difference between the dynamics of the nominal closed-loop system and the actual evolution of the state. The NMPC in this way can be designed based on a system with reduced uncertainty. In order to prove the stability of the overall control scheme, some general Regional ISpS results for continuous-time systems are proven.Matteo RubagottiDavide Martino RaimondoAntonella FerraraLalo Magni2012-03-06T13:19:59Z2013-09-30T12:26:33Zhttp://eprints.imtlucca.it/id/eprint/1219This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12192012-03-06T13:19:59ZAutomotive battery prognostics using dual Extended Kalman FilterThis paper proposes a strategy for estimating the remaining useful life of automotive batteries based on dual Extended Kalman Filter. A nonlinear model of the battery is exploited for the on-line estimation of the State of Charge, and this information is used to evaluate the actual capacity and predict its future evolution, from which an estimate of the remaining useful life is obtained with suitable margins of uncertainty. Simulation results using experimental data from lead-acid batteries show the effectiveness of the approachMatteo RubagottiSimona OnoriGiorgio Rizzoni2012-02-01T10:59:01Z2018-03-08T17:05:00Zhttp://eprints.imtlucca.it/id/eprint/1091This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10912012-02-01T10:59:01ZOn the rich-club effect in dense and weighted networksFor many complex networks present in nature only a single instance, usually of large size, is available. Any measurement made on this single instance cannot be repeated on different realizations. In order to detect significant patterns in a real-world network it is therefore crucial to compare the measured results with a null model counterpart. Here we focus on dense and weighted networks, proposing a suitable null model and studying the behaviour of the degree correlations as measured by the rich-club coefficient. Our method solves an existing problem with the randomization of dense unweighted graphs, and at the same time represents a generalization of the rich-club coefficient to weighted networks which is complementary to other recently proposed ones. Vinko ZlaticGinestra BianconiAlbert Díaz-GuileraDiego Garlaschellidiego.garlaschelli@imtlucca.itFrancesco RaoGuido Caldarelliguido.caldarelli@imtlucca.it2012-01-26T14:23:51Z2014-12-18T15:38:41Zhttp://eprints.imtlucca.it/id/eprint/1087This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10872012-01-26T14:23:51ZInvasion percolation on a tree and queueing modelsWe study the properties of the Barabási model of queuing [ A.-L. Barabási Nature (London) 435 207 (2005); J. G. Oliveira and A.-L. Barabási Nature (London) 437 1251 (2005)] in the hypothesis that the number of tasks grows with time steadily. Our analytical approach is based on two ingredients. First we map exactly this model into an invasion percolation dynamics on a Cayley tree. Second we use the theory of biased random walks. In this way we obtain the following results: the stationary-state dynamics is a sequence of causally and geometrically connected bursts of execution activities with scale-invariant size distribution. We recover the correct waiting-time distribution PW(τ)∼τ−3/2 at the stationary state (as observed in different realistic data). Finally we describe quantitatively the dynamics out of the stationary state quantifying the power-law slow approach to stationarity both in single dynamical realization and in average. These results can be generalized to the case of a stochastic increase in the queue length in time with limited fluctuations. As a limit case we recover the situation in which the queue length fluctuates around a constant average value.Andrea GabrielliGuido Caldarelliguido.caldarelli@imtlucca.it2012-01-26T14:09:16Z2014-12-18T15:37:28Zhttp://eprints.imtlucca.it/id/eprint/1085This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10852012-01-26T14:09:16ZRandom hypergraphs and their applicationsIn the last few years we have witnessed the emergence, primarily in online communities, of new types of social networks that require for their representation more complex graph structures than have been employed in the past. One example is the folksonomy, a tripartite structure of users, resources, and tags—labels collaboratively applied by the users to the resources in order to impart meaningful structure on an otherwise undifferentiated database. Here we propose a mathematical model of such tripartite structures that represents them as random hypergraphs. We show that it is possible to calculate many properties of this model exactly in the limit of large network size and we compare the results against observations of a real folksonomy, that of the online photography website Flickr. We show that in some cases the model matches the properties of the observed network well, while in others there are significant differences, which we find to be attributable to the practice of multiple tagging, i.e., the application by a single user of many tags to one resource or one tag to many resourcesGourab GhoshalVinko ZlaticGuido Caldarelliguido.caldarelli@imtlucca.itM.E.J. Newman2012-01-26T13:53:54Z2014-12-18T15:35:35Zhttp://eprints.imtlucca.it/id/eprint/1084This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10842012-01-26T13:53:54ZHypergraph topological quantities for tagged social networksRecent years have witnessed the emergence of a new class of social networks, which require us to move beyond previously employed representations of complex graph structures. A notable example is that of the folksonomy, an online process where users collaboratively employ tags to resources to impart structure to an otherwise undifferentiated database. In a recent paper, we proposed a mathematical model that represents these structures as tripartite hypergraphs and defined basic topological quantities of interest. In this paper, we extend our model by defining additional quantities such as edge distributions, vertex similarity and correlations as well as clustering. We then empirically measure these quantities on two real life folksonomies, the popular online photo sharing site Flickr and the bookmarking site CiteULike. We find that these systems share similar qualitative features with the majority of complex networks that have been previously studied. We propose that the quantities and methodology described here can be used as a standard tool in measuring the structure of tagged networks.Vinko ZlaticGourab GhoshalGuido Caldarelliguido.caldarelli@imtlucca.it2012-01-26T10:49:27Z2013-11-20T15:59:36Zhttp://eprints.imtlucca.it/id/eprint/1083This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10832012-01-26T10:49:27ZPageRank equation and localization in the WWWWe show that the PageRank in a network can be represented as the solution of a differential equation discretized over a directed graph. By exploiting a formal relationship with the time-independent Schrödinger equation it is possible to interpret hub formation and related phenomena as a wave-like localization process in the presence of disorder and trapping potentials. The result opens new perspectives in the physics of networks with interdisciplinary connections and opens the way to the employment of various mathematical techniques to the analysis of self-organization in structured systems. Applications are envisaged in the World-Wide Web, traffic, social and biological networks.Nicola PerraVinko ZlaticAlessandro Chessaalessandro.chessa@imtlucca.itClaudio ContiDebora DonatoGuido Caldarelliguido.caldarelli@imtlucca.it2012-01-25T13:47:35Z2012-01-25T13:47:35Zhttp://eprints.imtlucca.it/id/eprint/1078This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10782012-01-25T13:47:35ZInvasion percolation and the time scaling behavior of a queuing model of human dynamicsIn this paper we study the properties of the Barabási model of queuing under the hypothesis that the number of tasks is steadily growing in time. We map this model exactly onto an invasion percolation dynamics on a Cayley tree. This allows us to recover the correct waiting time distribution PW(τ)~τ−3/2 at the stationary state (as observed in different realistic data) and also to characterize it as a sequence of causally and geometrically connected bursts of activity. We also find that the approach to stationarity is very slow.Andrea GabrielliGuido Caldarelliguido.caldarelli@imtlucca.it2011-12-14T15:19:28Z2011-12-14T15:19:28Zhttp://eprints.imtlucca.it/id/eprint/1042This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10422011-12-14T15:19:28ZManaging technological transitions through R&D alliancesTechnological and market transitions are difficult to manage, and collaborations can be viewed as either resources or constraints in dynamic settings. In the biopharmaceutical industry, a paradigmatic shift in the relevant knowledge bases occurred in the mid-1990s, inducing a structural change in the network of R&D collaborations. Search and relational strategies oriented toward exploration versus exploitation have prevailed in different phases of the network evolution. Therefore, biotechnology firms have experienced overwhelming difficulties in reorienting their learning strategies throughout paradigmatic shifts and ambidextrous organizations have been able to attain superior performances in terms of stability and centralization in the R&D network.Massimo Riccabonimassimo.riccaboni@imtlucca.itRocco Moliterni2011-12-06T10:15:20Z2013-03-12T14:57:39Zhttp://eprints.imtlucca.it/id/eprint/1032This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10322011-12-06T10:15:20ZExplicit control for nonlinear constrained systems combining fuzzy model predictive control and multiparametric
programmingPantelis Sopasakispantelis.sopasakis@imtlucca.itPanagiotis Patrinospanagiotis.patrinos@imtlucca.itHaralambos Sarimveis2011-11-17T14:36:26Z2011-11-17T14:36:26Zhttp://eprints.imtlucca.it/id/eprint/1006This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10062011-11-17T14:36:26ZEnergy-aware robust model predictive control with feedback from multiple noisy wireless sensorsWireless Sensor Networks (WSNs) are becoming fundamental components of modern control systems. Although WSNs provide tremendous advantages in versatility, their use poses new issues in the design of the control system, in particular the discharge of batteries of sensor nodes, which is mainly due to radio communications, must be taken into account. In a previous work, for the case of a single wireless measurement device and no measurement noise, we have provided a general transmission strategy for communication between controller and sensors and an energy-aware robust Model Predictive Control (MPC) algorithm that achieve a profitable trade-off between transmission rate (battery energy savings) and loss of closed-loop system performance. In this paper we extend the approach by taking into account unknown but bounded noise on state measurements, and by considering a local area network of multiple wireless sensors measuring the state vector for disturbance rejection.Daniele Bernardinidaniele.bernardini@imtlucca.itAlberto Bemporadalberto.bemporad@imtlucca.it2011-10-31T13:28:39Z2011-11-03T13:19:36Zhttp://eprints.imtlucca.it/id/eprint/980This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9802011-10-31T13:28:39ZRate of convergence of predictive distributions for dependent dataThis paper deals with empirical processes of the type
[C_{n}(B)=\sqrt{n}\{\mu_{n}(B)-P(X_{n+1}\in B\mid X_{1},\ldots,X_{n})\},\]
where (Xn) is a sequence of random variables and μn=(1/n)∑i=1nδXi the empirical measure. Conditions for supB|Cn(B)| to converge stably (in particular, in distribution) are given, where B ranges over a suitable class of measurable sets. These conditions apply when (Xn) is exchangeable or, more generally, conditionally identically distributed (in the sense of Berti et al. [Ann. Probab. 32 (2004) 2029–2052]). By such conditions, in some relevant situations, one obtains that $\sup_{B}|C_{n}(B)|\stackrel{P}{\rightarrow}0$ or even that $\sqrt{n}\sup_{B}|C_{n}(B)|$ converges a.s. Results of this type are useful in Bayesian statistics.
Patrizia BertiIrene Crimaldiirene.crimaldi@imtlucca.itLuca PratelliPietro Rigo2011-10-31T13:16:20Z2011-11-03T13:19:36Zhttp://eprints.imtlucca.it/id/eprint/979This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9792011-10-31T13:16:20ZAn almost sure conditional convergence result and an application to a generalized Polya urn We prove an almost sure conditional convergence result toward a Gaussian kernel and we apply it to a two-colors randomly reinforced urn.Irene Crimaldiirene.crimaldi@imtlucca.it2011-10-24T14:00:14Z2011-10-24T14:00:14Zhttp://eprints.imtlucca.it/id/eprint/967This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9672011-10-24T14:00:14ZIl re è nudo. Riflessioni a margine del convegno "Lo stato dell’Arte: la storia dell’arte nell’università italiana" (Firenze, Aula Magna della facoltà di Lettere e Filosofia, 15-16 giugno 2009)Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-24T13:49:19Z2011-10-24T13:49:19Zhttp://eprints.imtlucca.it/id/eprint/966This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9662011-10-24T13:49:19ZLe arti di William Roscoe: biblioteca e collezione (II parte)Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-24T13:45:43Z2011-10-24T13:45:43Zhttp://eprints.imtlucca.it/id/eprint/965This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9652011-10-24T13:45:43ZLe arti di William Roscoe: biblioteca e collezione (I parte)Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-14T10:48:58Z2011-10-14T10:48:58Zhttp://eprints.imtlucca.it/id/eprint/941This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9412011-10-14T10:48:58ZIl viaggio di una collezione romanaEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-14T10:02:11Z2011-10-14T10:02:11Zhttp://eprints.imtlucca.it/id/eprint/940This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9402011-10-14T10:02:11ZRagghianti, Emporium, il 1942Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-12T13:16:17Z2011-11-22T11:21:32Zhttp://eprints.imtlucca.it/id/eprint/923This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9232011-10-12T13:16:17Z(a cura di) Descrivere Lucca : viaggio tra note, inventari e guide dal 17. al 19. secolo Dall'appassionato Pellegrino di Bartolomeo Beverini al rigoroso Inventario di Michele Ridolfi, passando per la Lucca pittrice di Tommaso Bernardi, l'insieme dei manoscritti inediti che vengono raccolti in questo volume forma una piccola antologia di descrizioni della città di Lucca dalla metà del diciassettesimo sino ai primi anni del diciannovesimo secolo. Sia che si tratti di meri elenchi, di rigidi inventari di stampo notarile, sia invece che ci si trovi di fronte ad articolate descrizioni o vere e proprie guide turistiche, una lettura di questi testi consente di ripercorrere, quasi in modo fisico, le vicende delle opere d'arte che hanno costruito, modellato e connotato nei secoli la nobile immagine di Lucca. Seguendo la penna di questi indefessi ricercatori, di varia estrazione e formazione, l'occhio del presente viaggia attraverso la città e il suo contado, ripercorre la geometria variabile di un ricchissimo patrimonio culturale che, distrutto, accresciuto, disperso, conserva intatto il suo valore.Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-12T13:11:13Z2011-10-12T13:11:13Zhttp://eprints.imtlucca.it/id/eprint/922This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9222011-10-12T13:11:13Z(a cura di) Regioni e musei : politiche per i sistemi museali dagli anni Settanta a oggi : Atti del convegno, Pisa, Scuola Normale Superiore, 4 dicembre 200Denise La MonicaEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-09-22T13:32:40Z2014-01-24T14:26:07Zhttp://eprints.imtlucca.it/id/eprint/902This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9022011-09-22T13:32:40ZYoung workers flows and short-term contractsThe issue of fixed term contract in the labor market is not a problem of the past. In the last ten years the share of temporary contracts has been growing in many European countries. Moreover, the category of young workers seems to be the most affected. This paper develops a search model in which firms hire young and old workers either on a short-term or on a long-term contract. The firm decision is driven mainly by two key parameters: the length of the short-term contract and the firing cost associated with the long-term contract. The presence of full or asymmetric information in the economy affects the contract choice of the firm and, consequently, the steady-state distribution of unemployment across types. Simulation and estimation exercises are performed; the availability of data on the Italian labor market will contribute to the completion of the paper.Cristina Tealdicristina.tealdi@imtlucca.it2011-09-07T14:28:53Z2013-03-05T15:44:49Zhttp://eprints.imtlucca.it/id/eprint/836This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8362011-09-07T14:28:53ZAutomated detection and quantification of microcirculatory oxygenation changes in the heartBlood-oxygen-level dependent (BOLD) MRI may be used for detecting myocardial oxygenation (MO) changes secondary to coronary artery stenosis (CAS). Under pharmacological stress, the myocardial territory affected by CAS appears hypointense relative to healthy regions in BOLD images.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangDebiao LiRohan Dharmakumar2011-09-07T14:12:18Z2013-03-05T15:43:13Zhttp://eprints.imtlucca.it/id/eprint/832This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8322011-09-07T14:12:18ZPlant phenotyping with low cost digital cameras and image analyticsIn this paper we discuss a prototype, easy-to-deploy, and low cost (~ $250) phenotype collection system for growth chambers. Off the shelf digital cameras, wireless transmitters, and PCs are used to store and process the
images. A Matlab pipeline is used to fuse multiple images, identify the location of each Arabidopsis plant, segment its leaves, and measure leaf topology and area. Our early findings (unpublished) using this system for correlating genotype to phenotype are very promising. We hope that with
future improvements and broad adoption, it will have the same disruptive effects as the first “build your own” microarrayers, which allowed for the explosion of genotyping information. Low cost genotyping and phenotyping
will hopefully address some of the environmental, agricultural, and industrial sustainability challenges we are facing today.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itChristos Noutsos2011-09-07T13:59:42Z2013-03-05T15:42:58Zhttp://eprints.imtlucca.it/id/eprint/831This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8312011-09-07T13:59:42ZVisualization and tracking of a conventional guidewire with low flip angle SSFP imaging: an initial studyInductive coupling between signal reception coils and conventional guidewires in the presence of low flip-angle (LF) balanced SSFP (b-SSFP) imaging may permit the visualization of guidewires with positive contrast. To test our hypothesis, ex-vivo and in-vivo experiments were performed using a radio-opaque coronary guidewire and LF b-SSFP imaging. Our initial studies showed that it is possible to visualize and track a conventional guidewire with positive contrast using LF b-SSFP imaging within ex-vivo and in-vivo settings. These results lend support to the hypothesis that signal reception coils and passive guidewires may be inductively coupled in the presence of LF excitations.Rohan DharmakumarIoannis KoktzoglouSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itSven ZuehlsdorffRichard TangWright GrahamDebiao Li2011-09-07T13:52:43Z2013-03-05T15:44:38Zhttp://eprints.imtlucca.it/id/eprint/830This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8302011-09-07T13:52:43ZAn intensity based statistical approach for left ventricular localization and identification of end-systolic and end-diastolic images from cine cardiac MRIA critical component in computing quantitative diagnostic metrics, such as ejection fraction, as well as, image segmentation and registration is the accurate identification of the end-systolic (ES) and end-diastolic (ED) frames in cine MRI. Localization of the LV is also
important, to assist further analysis (ie., myocardial segmentation). Currently, these tasks are performed in a manual, semi- or fully-automated fashion. Fully-automated methods are desirable since they can eliminate manual labor and inter- and intra-observer variability. Most methods rely on measuring the area of the blood pool in the LV chamber, but they are computationally intensive,susceptible to noise, and require prior localization and segmentation of the LV. An image-driven statistical method is presented that utilizes cross-correlation (1), to detect ES and ED from cine MRI acquired from canines under control conditions. The purpose of this work is to develop a fully automated, computationally efficient, post-processing method for reliable LV localization and identification of ES and ED frames from cine cardiac MR imagesSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangRachel KleinRohan Dharmakumar2011-09-07T13:48:06Z2013-03-05T15:43:59Zhttp://eprints.imtlucca.it/id/eprint/829This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8292011-09-07T13:48:06ZVisualizing and quantifying myocardial oxygenation changes with statistically optimal colormapsBlood-oxygen-level dependent (BOLD) MRI may be used for detecting myocardial oxygenation (MO) changes secondary to coronary artery stenosis. Under pharmacological stress, areas of the myocardium supplied by a stenotic coronary artery are hypointense relative to healthy regions. Visualizing these changes requires manual windowing. In this paper a method for automatic visualization and quantification of myocardial signal changes reflecting the regional variations in oxygenation is presented, using images obtained from a canine study under controlled conditions.
The objective of this study is to overcome the rather subjective step of windowing by establishing an optimal colormap that permits visualization of
statistical changes in signal intensities between healthy and pathological cases. In addition, graph theory is used to derive a quantitative metric indicative
of changes in myocardial oxygenation. The purpose of this effort is to facilitate the evaluation of myocardial BOLD images by automating the
detection of regional abnormalities in MO under pharmacological stress in the presence of coronary artery stenosis.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itRichard TangRachel KleinDebiao LiRohan Dharmakumar2011-09-07T13:33:50Z2013-03-05T15:44:23Zhttp://eprints.imtlucca.it/id/eprint/828This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8282011-09-07T13:33:50ZAn automated method for left ventricular localization and identification of end-systolic and end-diastolic images from cine cardiac MRIA critical component in computing quantitative diagnostic metrics, such as ejection fraction, as well as image segmentation and registration is the accurate identification of the end-systolic (ES) and end-diastolic (ED) frames in cine MRI. Localization of the LV is also important, to assist further analysis (ie., myocardial segmentation). Currently, these tasks are performed in a manual, semi- or fully-automated fashion. Fully-automated methods are desirable since they can eliminate manual labor and inter- and intra-observer variability. Most methods rely on measuring the area of the blood pool in the LV chamber, but they are computationally intensive, susceptible to noise, and require prior localization and segmentation of the LV. An image-driven statistical method is presented that utilizes cross-correlation to detect ES and ED from cine MRI acquired from canines under control conditions.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangRachel KleinRohan Dharmakumar2011-09-07T13:28:16Z2013-03-05T15:44:11Zhttp://eprints.imtlucca.it/id/eprint/827This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8272011-09-07T13:28:16ZVisualizing regional myocardial oxygenation changes with statistically optimal colormapsBlood-oxygen-level dependent (BOLD) MRI may be used for detecting myocardial oxygenation (MO) changes secondary to coronary artery stenosis. Under pharmacological stress, areas in the myocardium supplied by a stenotic coronary artery are hypointense relative to healthy regions. Visualizing these changes requires manual windowing. In this paper a method for automatic visualization of myocardial signal changes reflecting the regional variations in oxygenation is presented, using images obtained from a canine study under controlled conditions. The objective of this study is to overcome the rather subjective step of windowing by establishing an optimal colormap that permits visualization of statistical changes in signal intensities between healthy and pathological cases.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itRichard TangRachel KleinDebiao LiRohan Dharmakumar2011-09-07T13:23:38Z2013-03-05T15:45:03Zhttp://eprints.imtlucca.it/id/eprint/826This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8262011-09-07T13:23:38ZImpact of temporal resolution on cardiac phase-resolved oxygen-sensitive myocardial steady-state free precession imagingCardiac phase-resolved imaging studies that are used in the assessment of cardiac function are performed with a temporal resolution (TRES) of approximately 50 ms to mitigate the effects from cardiac motion and flow. To date, there has been minimal interest on the characterization of myocardial signal intensities from cine images. Steady-state free precession based cardiac phase-resolved blood-oxygen-level-dependent (CP-SSFP BOLD) imaging is a relatively new method for identifying myocardial oxygen abnormalities on the basis of regional signal differences. For reliable assessment of oxygenation changes, it is imperative to ensure that acquisitions enable robust image quality. We hypothesize that TRES plays a significant role on CP-SSFP image quality and that, in particular, myocardial signal characteristics disintegrate with elevations in TRES.Xiangzhi ZhouRichard TangRachel KleinSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itDebiao LiRohan Dharmakumar2011-08-11T10:23:31Z2013-03-05T15:40:36Zhttp://eprints.imtlucca.it/id/eprint/797This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7972011-08-11T10:23:31ZDual-contrast cellular magnetic resonance imagingNegative contrast magnetic resonance imaging (MRI) methods using magnetic susceptibility shifting agents have become one of the most important approaches in cellular imaging research. However, visualizing and tracking labeled cells on the basis of negative contrast is often met with limited specificity and sensitivity. Here we report on a MRI method for cellular imaging that generates a new contrast with a distinct topology for identifying labeled cells that has the potential to significantly improve both the sensitivity and the specificity. Specifically, we show that low flip-angle steady-state free precession MRI can be used to generate fast three-dimensional images of tissue that can be rapidly processed to generate quantitative metrics enabling color overlays indicative of regions containing labeled cells. The technique substantially improves the ability of MRI for detecting labeled cells by overcoming the fundamental limits that currently plague negative contrast methods.Rohan DharmakumarZheng ZhangIoannis KoktzoglouSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itDebiao Li2011-08-11T10:12:31Z2013-03-05T15:42:26Zhttp://eprints.imtlucca.it/id/eprint/796This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7962011-08-11T10:12:31ZRetrieval efficiency of DNA-Based databases of digital signalsUsing DNA to store digital signals, or data in general, offers significant advantages when compared to other media. The DNA molecule, especially in its double-stranded form, is very stable, compact, and inexpensive. In the past, we have shown that DNA can be used to store and retrieve digital signals encoded and stored in DNA. We have also shown that DNA hybridization can be used as a similarity criterion for retrieving digital signals encoded and stored in a DNA database. Retrieval is achieved through hybridization of "query" and "data" DNA molecules. In this paper, we present a mathematical framework to simulate single-query and parallel-query scenarios, and to estimate hybridization efficiency. Our framework allows for exact numerical solutions as well as closed-form approximations under certain conditions. Similarly to the digital domain, we define a DNA SNR measure to assess the performance of the DNA-based retrieval scheme in terms of database size and source statistics. With approximations, we show that the SNR of any finite-sized DNA-based database is upper bounded by the SNR of an infinitely large DNA-based database that has the same source distribution. Computer simulations are presented to validate our results.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itAggelos K. Katsaggelos2011-08-01T13:49:28Z2011-08-08T08:40:22Zhttp://eprints.imtlucca.it/id/eprint/757This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7572011-08-01T13:49:28ZRobust simulation-optimization methodologyThis contribution summarizes a methodology for simulation
optimization assuming some simulation inputs are
uncertain. This methodology integrates Taguchi’s worldview
(distinguishing between decision and environmental
inputs), metamodeling (either Response Surface Methodology
or Kriging), and mathematical programming. Instead
of Taguchi’s statistical designs, this contribution uses Latin Hypercube Sampling for the environmental inputs. Mathematical programming is used to estimate the decision inputs that minimize the mean output, subject to a threshold for the standard deviation of the simulation output. Changing that threshold gives the estimated Pareto frontier. Confidence regions for the Pareto-optimal solution based on that frontier can be estimated through bootstrapping. This methodology is illustrated through Economic Order Quantity (EOQ)
simulations.Jack P.C. KleijnenGabriella Dellinogabriella.dellino@imtlucca.itCarlo Meloni2011-08-01T13:42:54Z2011-10-07T08:21:48Zhttp://eprints.imtlucca.it/id/eprint/756This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7562011-08-01T13:42:54ZRobust simulation-optimization using metamodelsOptimization of simulated systems is the goal of many methods, but most methods assume known environments. In this paper we present a methodology that does account for uncertain environments. Our methodology uses Taguchi's view of the uncertain world, but replaces his statistical techniques by either Response Surface Methodology or Kriging metamodeling. We illustrate the resulting methodology through the well-known Economic Order Quantity (EOQ) modelGabriella Dellinogabriella.dellino@imtlucca.itJack P.C. KleijnenCarlo Meloni2011-08-01T12:19:29Z2011-08-04T07:30:21Zhttp://eprints.imtlucca.it/id/eprint/751This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7512011-08-01T12:19:29ZRobust simulation optimization methods using Kriging metamodelsGabriella Dellinogabriella.dellino@imtlucca.it2011-08-01T10:24:59Z2011-08-04T07:30:21Zhttp://eprints.imtlucca.it/id/eprint/747This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7472011-08-01T10:24:59ZKriging metamodel management in the design optimization of a CNG injection systemThis paper deals with the use of Kriging metamodels in multi-objective engineering design optimization. The metamodel management issue to find the tradeoff between accuracy and efficiency is addressed. A comparative analysis of different strategies is conducted for a case study devoted to the design of a component of the injection system for Compressed Natural Gas (CNG) engines. The computational results are reported and analyzed for a performance assessment conducted with a data envelopment analysis approach.Gabriella Dellinogabriella.dellino@imtlucca.itPaolo LinoCarlo MeloniAlessandro Rizzo2011-07-27T10:14:44Z2014-07-03T13:45:30Zhttp://eprints.imtlucca.it/id/eprint/437This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4372011-07-27T10:14:44ZModeling and control of hybrid dynamical systems: the hybrid toolbox for MATLABAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T09:42:01Z2011-08-05T12:45:52Zhttp://eprints.imtlucca.it/id/eprint/624This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6242011-07-27T09:42:01ZFurther switched systemsMixed logical dynamical systems and linear complementarity systems are representations of switched systems, which under the conditions described here are equivalent to the model used in Chapter 4. They are particularly useful for model-predictive control. The equivalences of several hybrid system models show that different models, which are suitable for specific analysis and design problems and have been investigated in detail, cover the same class of hybrid systems. The analysis of the well-posedness of the models leads to conditions on the model equations under which a unique solution exists.Alberto Bemporadalberto.bemporad@imtlucca.itM.Kanat ÇamlıbelW.P.M.H. HeemelsArjan J. Van der SchaftJ.M. SchumacherBart De Schutter2011-07-27T08:34:14Z2014-07-02T14:30:10Zhttp://eprints.imtlucca.it/id/eprint/433This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4332011-07-27T08:34:14ZModel predictive control for systems with time delay: an application to air-fuel ratio control in automotive enginesTo meet increasingly stringent emission regulations modern internal combustion engines require highly accurate control of the air-to-fuel ratio. The performance of the conventional air-to-fuel ratio feedback loop is limited by the combustion delay between fuel injection and engine exhaust, and by the transport delay for the exhaust gas to propagate to the air-to-fuel ratio sensor location. The combined delay is variable, since it depends on engine speed and airflow. Drivability, fuel economy and emission requirements result in constraints on the deviations of the air-to-fuel ratio, stored oxygen in the three-way catalyst, and fuel injection. This paper proposes an approach for air-to-fuel ratio control based on Model Predictive Control (MPC). The approach systematically handles both variable time delays and pointwise-in-time constraints. A delay-free model is considered first, which takes into account the dynamic relations between the injected fuel and the air-to-fuel ratio and the dynamics of the oxygen stored in the catalyst. For the delay-free model, the explicit MPC law is computed. Delay compensation is obtained by estimating the delay online from engine operating conditions, and feeding the MPC law with the state predicted ahead over the time interval of the estimated delay. The predicted state is computed by combining measurement filtering with forward iterations of the nonlinear dynamic equations of the model. The achieved performance in tracking the air-to-fuel ratio and the oxygen storage setpoints while enforcing the constraints is demonstrated in simulation using real data profiles.Sergio TrimboliStefano Di CairanoAlberto Bemporadalberto.bemporad@imtlucca.itIlya Kolmanovsky2011-07-27T08:34:12Z2011-08-05T12:43:59Zhttp://eprints.imtlucca.it/id/eprint/513This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5132011-07-27T08:34:12ZHybrid modeling, identification, and predictive control: an application to hybrid electric vehicle energy managementRising fuel prices and tightening emission regulations have resulted in an increasing need for advanced powertrain systems and systematic model-based control approaches. Along these lines, this paper illustrates the use of hybrid modeling and model predictive control for a vehicle equipped with an advanced hybrid powertrain. Starting from an existing high fidelity nonlinear simulation model based on experimental data, the hybrid dynamical model is developed through the use of linear and piecewise affine identification methods. Based on the resulting hybrid dynamical model, a hybrid MPC controller is tuned and its effectiveness is demonstrated through closed-loop simulations with the high-fidelity nonlinear model. Giulio RipaccioliAlberto Bemporadalberto.bemporad@imtlucca.itF. AssadianC. DextreitStefano Di CairanoIlya Kolmanovsky2011-07-27T08:34:07Z2013-02-20T10:16:40Zhttp://eprints.imtlucca.it/id/eprint/432This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4322011-07-27T08:34:07ZHierarchical and hybrid model predictive control of quadcopter air vehiclesThis paper proposes a hierachical hybrid MPC approach to design feedback control functions for stabilization and autonomous navigation of unmanned air vehicles. After formulating the nonlinear dynamical equations of a "quadcopter" air vehicle, a linear MPC controller is designed to stabilize the vehicle around commanded desired set-points. These are generated at a slower sampling rate by a hybrid MPC controller at the upper control layer, based on a hybrid dynamical model of the UAV and of its surrounding environment, with the overall goal of controlling the vehicle to a target set-point while avoiding obstacles. The performance of the complete hierarchical control scheme is assessed through simulations and visualization in a virtual 3D environment, showing the ability of linear MPC to handle the strong couplings among the dynamical variables of the quadcopter under various torque and angle/position constraints, and the flexibility of hybrid MPC in planning the desired trajectory on-line.Alberto Bemporadalberto.bemporad@imtlucca.itCarlo A. PascucciClaudio Rocchi2011-07-27T08:34:04Z2011-08-04T07:29:06Zhttp://eprints.imtlucca.it/id/eprint/442This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4422011-07-27T08:34:04ZMultiobjective model predictive controlThis paper proposes a novel model predictive control (MPC) scheme based on multiobjective optimization. At each sampling time, the MPC control action is chosen among the set of Pareto optimal solutions based on a time-varying, state-dependent decision criterion. Compared to standard single-objective MPC formulations, such a criterion allows one to take into account several, often irreconcilable, control specifications, such as high bandwidth (closed-loop promptness) when the state vector is far away from the equilibrium and low bandwidth (good noise rejection properties) near the equilibrium. After recasting the optimization problem associated with the multiobjective MPC controller as a multiparametric multiobjective linear or quadratic program, we show that it is possible to compute each Pareto optimal solution as an explicit piecewise affine function of the state vector and of the vector of weights to be assigned to the different objectives in order to get that particular Pareto optimal solution. Furthermore, we provide conditions for selecting Pareto optimal solutions so that the MPC control loop is asymptotically stable, and show the effectiveness of the approach in simulation examples.Alberto Bemporadalberto.bemporad@imtlucca.itDavid Muñoz de la Peña2011-07-27T08:34:02Z2011-11-17T14:32:55Zhttp://eprints.imtlucca.it/id/eprint/435This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4352011-07-27T08:34:02ZMultiobjective model predictive control based on convex piecewise affine costsThis paper proposes a novel model predictive control (MPC) scheme based on multiobjective optimization. At each sampling time, the MPC control action is chosen among the set of Pareto optimal solutions based on a time-varying and state-dependent decision criterion. After recasting the optimization problem associated with the multiobjective MPC controller as a multiparametric multiobjective linear problem, we show that it is possible to compute each Pareto optimal solution as an explicit piecewise affine function of the state vector and of the vector of weights to be assigned to the different objectives in order to get that particular Pareto optimal solution. Furthermore, we provide conditions for selecting Pareto optimal solutions so that the MPC control loop is asymptotically stable, and show the effectiveness of the approach in simulation examples.Alberto Bemporadalberto.bemporad@imtlucca.itDavid Muñoz de la Peña2011-07-27T08:32:34Z2014-03-05T13:43:45Zhttp://eprints.imtlucca.it/id/eprint/475This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4752011-07-27T08:32:34ZEvent-driven optimization-based control of hybrid systems with integral continuous-time dynamicsIn this paper we introduce a class of continuous-time hybrid dynamical systems called integral continuous-time hybrid automata (icHA) for which we propose an event-driven optimization-based control strategy. Events include both external actions applied to the system and changes of continuous dynamics (mode switches). The icHA formalism subsumes a number of hybrid dynamical systems with practical interest, e.g., linear hybrid automata. Different cost functions, including minimum-time and minimum-effort criteria, and constraints are examined in the event-driven optimal control formulation. This is translated into a finite-dimensional mixed-integer optimization problem, in which the event instants and the corresponding values of the control input are the optimization variables. As a consequence, the proposed approach has the advantage of automatically adjusting the attention of the controller to the frequency of event occurrence in the hybrid process. A receding horizon control scheme exploiting the event-based optimal control formulation is proposed as a feedback control strategy and proved to ensure either finite-time or asymptotic convergence of the closed-loop.Stefano Di CairanoAlberto Bemporadalberto.bemporad@imtlucca.itJorge Júlvez2011-07-27T08:32:07Z2011-08-05T12:39:05Zhttp://eprints.imtlucca.it/id/eprint/434This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4342011-07-27T08:32:07ZModel predictive controller matching: Can MPC enjoy small signal properties of my favorite linear controller?Model predictive control (MPC) strategies can efficiently deal with constraints on system states, inputs, and outputs. However, in contrast with linear control techniques, closed-loop frequency-domain properties of MPC such as sensitivity and robustness to small perturbations are difficult to enforce a priori. This paper considers the problem of transforming a given linear feedback control design, referred to as “favorite controller”, into a model predictive control one. In this way, the MPC controller inherits all the stability, robustness and frequency properties of the given favorite controller in the region around the equilibrium where the constraints are not active. The added value is that the constructed MPC controller is able to properly handle constraints that may be activated during the transient, and that global stability in the set of feasible initial conditions can be guaranteed.Stefano Di CairanoAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T08:32:04Z2011-10-12T14:23:42Zhttp://eprints.imtlucca.it/id/eprint/512This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5122011-07-27T08:32:04ZSimultaneous optimal control and discrete stochastic sensor selectionIn this paper we present the problem of combining optimal control with efficient information gathering in an uncertain environment. We assume that the decision maker has the ability to choose among a discrete set of sources of information, where the outcome of each source is stochastic. Different sources and outcomes determine a reduction of uncertainty, expressed in terms of constraints on system variables and set-points, in different directions. This paper proposes an optimization-based decision making algorithm that simultaneously determines the best source to query and the optimal sequence of control moves, according to the minimization of the expected value of an index that weights both dynamic performance and the cost of querying. The problem is formulated using stochastic programming ideas with decision-dependent scenario trees, and a solution based on mixed-integer linear programming is presented. The results are demonstrated on a simple supply-chain management example with uncertain market demand. Daniele Bernardinidaniele.bernardini@imtlucca.itDavid Muñoz de la PeñaAlberto Bemporadalberto.bemporad@imtlucca.itEmilio Frazzoli2011-07-27T08:32:01Z2016-04-06T10:26:11Zhttp://eprints.imtlucca.it/id/eprint/430This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4302011-07-27T08:32:01ZDrive-by-wire vehicle stabilization and yaw regulation: A hybrid model predictive control designElectronic Stability Control (ESC) and Active Front Steering (AFS) have been introduced in production vehicles in recent years, due to improved vehicle maneuverability and the effects in reducing single vehicle accident. We propose a hybrid Model Predictive Control (MPC) design for coordinated control of AFS and ESC. By formulating the vehicle dynamics with respect to the front and rear tire slip angles and by approximating the tire-force characteristics by piecewise affine functions, the vehicle dynamics are formulated as a linear hybrid dynamical system. This model is used to design a hybrid model predictive controller. The proposed model formulation allows one to visually analyze the stability region of the closed-loop system and to assess the stabilizing capability of the hybrid MPC controller. Simulations of the controller in closed-loop with an accurate nonlinear model are presented.Daniele Bernardinidaniele.bernardini@imtlucca.itStefano Di CairanoAlberto Bemporadalberto.bemporad@imtlucca.itH. E. Tseng2011-07-27T08:31:59Z2011-11-17T11:28:12Zhttp://eprints.imtlucca.it/id/eprint/429This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4292011-07-27T08:31:59ZScenario-based model predictive control of stochastic constrained linear systemsIn this paper we propose a stochastic model predictive control (MPC) formulation based on scenario generation for linear systems affected by discrete multiplicative disturbances. By separating the problems of (1) stochastic performance, and (2) stochastic stabilization and robust constraints fulfillment of the closed-loop system, we aim at obtaining a less conservative control action with respect to classical robust MPC schemes, still enforcing convergence and feasibility properties for the controlled system. Stochastic performance is addressed for very general classes of stochastic disturbance processes, although discretized in the probability space, by adopting ideas from multi-stage stochastic optimization. Stochastic stability and recursive feasibility are enforced through linear matrix inequality (LMI) problems, which are solved off-line; stochastic performance is optimized by an on-line MPC problem which is formulated as a convex quadratically constrained quadratic program (QCQP) and solved in a receding horizon fashion. The performance achieved by the proposed approach is shown in simulation and compared to the one obtained by standard robust and deterministic MPC schemes.Daniele Bernardinidaniele.bernardini@imtlucca.itAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T08:31:54Z2011-08-05T12:39:58Zhttp://eprints.imtlucca.it/id/eprint/607This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6072011-07-27T08:31:54ZAutomotive controlLuca BenvenutiAndrea BalluchiAlberto Bemporadalberto.bemporad@imtlucca.itStefano Di CairanoBengt JohanssonRolf JohanssonAlberto Sangiovanni VincentelliPer Tunest2011-07-27T08:31:52Z2011-08-05T12:34:42Zhttp://eprints.imtlucca.it/id/eprint/431This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4312011-07-27T08:31:52ZDecentralized model predictive control of dynamically-coupled linear systems: tracking under packet lossFor large-scale processes whose dynamics can be represented as the interaction of several dynamically-coupled linear subsystems, this paper proposes a decentralized model predictive control (MPC) design approach for set-point tracking under input constraints and possible loss of information packets. Following earlier results in (Alessio and Bemporad, 2007 and 2008), the global model of the process is approximated as the decomposition of several (possibly overlapping) smaller models used for local predictions. We present sufficient criteria for asymptotic tracking of output set-points and rejection of constant measured disturbances when the overall process is in closed loop with the set of decentralized MPC controllers, under possible intermittent lack of communication of measurement data between controllers. The effectiveness of the approach is shown in a simulation example on distributed temperature control in the passenger area of a railcar.Davide BarcelliAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T08:31:50Z2011-08-05T12:33:40Zhttp://eprints.imtlucca.it/id/eprint/511This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5112011-07-27T08:31:50ZA survey on explicit model predictive controlExplicit model predictive control (MPC) addresses the problem of removing one of the main drawbacks of MPC, namely the need to solve a mathematical program on line to compute the control action. This computation prevents the application of MPC in several contexts, either because the computer technology needed to solve the optimization problem within the sampling time is too expensive or simply infeasible, or because the computer code implementing the numerical solver causes software certification concerns,especially in safety critical applications.
Explicit MPC allows one to solve the optimization problem off-line for a given range of operating conditions of interest. By exploiting multiparametric programming techniques, explicit MPC computes the optimal control action off line as an “explicit” function of the state and reference vectors, so that on-line operations reduce to a simple function evaluation. Such a function is piecewise affine in most cases, so that the MPC controller maps into a lookup table of linear gains.
In this paper we survey the main contributions on explicit MPC appeared in the scientific literature. After recalling the basic concepts and problem formulations of MPC, we review the main approaches to solve explicit MPC problems, including a novel and simple suboptimal practical approach to reduce the complexity of the explicit form. The paper concludes with some comments on future research directions.
Alessandro AlessioAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-06T09:44:42Z2011-07-11T14:37:42Zhttp://eprints.imtlucca.it/id/eprint/707This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7072011-07-06T09:44:42ZA spatial mixed Poisson framework for combination of excess-of-loss and proportional reinsurance contractsIn this paper a purely theoretical reinsurance model is presented, where the reinsurance contract is assumed to be simultaneously of an excess-of-loss and of a proportional type. The stochastic structure of the set of pairs (claim’s arrival time, claim’s size) is described by a Spatial Mixed Poisson Process. By using an invariance property of the Spatial Mixed Poisson Processes, we estimate the amount that the ceding company obtains in a fixed time interval in force of the reinsurance contract.Roy CerquetiRachele Foschirachele.foschi@imtlucca.itFabio Spizzichino2011-07-04T09:21:46Z2016-04-06T08:02:07Zhttp://eprints.imtlucca.it/id/eprint/263This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2632011-07-04T09:21:46ZQuantitative relations between risk, return and firm sizeWe analyze —for a large set of stocks comprising four financial indices— the annual logarithmic growth rate R and the firm size, quantified by the market capitalization MC. For the Nasdaq Composite and the New York Stock Exchange Composite we find that the probability density functions of growth rates are Laplace ones in the broad central region, where the standard deviation σ(R), as a measure of risk, decreases with the MC as a power law σ(R)~(MC)- β. For both the Nasdaq Composite and the S&P 500, we find that the average growth rate langRrang decreases faster than σ(R) with MC, implying that the return-to-risk ratio langRrang/σ(R) also decreases with MC. For the S&P 500, langRrang and langRrang/σ(R) also follow power laws. For a 20-year time horizon, for the Nasdaq Composite we find that σ(R) vs. MC exhibits a functional form called a volatility smile, while for the NYSE Composite, we find power law stability between σ(r) and MC.Boris PodobnikDavor HorvaticAlexander M. Petersenalexander.petersen@imtlucca.itH. Eugene Stanley2011-07-04T09:21:34Z2013-11-21T11:40:02Zhttp://eprints.imtlucca.it/id/eprint/265This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2652011-07-04T09:21:34ZCross-correlations between volume change and price changeIn finance, one usually deals not with prices but with growth rates R, defined as the difference in logarithm between two consecutive prices. Here we consider not the trading volume, but rather the volume growth rate R̃, the difference in logarithm between two consecutive values of trading volume. To this end, we use several methods to analyze the properties of volume changes |R̃|, and their relationship to price changes |R|. We analyze 14,981 daily recordings of the Standard and Poor's (S & P) 500 Index over the 59-year period 1950–2009, and find power-law cross-correlations between |R| and |R̃| by using detrended cross-correlation analysis (DCCA). We introduce a joint stochastic process that models these cross-correlations. Motivated by the relationship between |R| and |R̃|, we estimate the tail exponent α̃ of the probability density function P(|R̃|) ∼ |R̃|−1−α̃ for both the S & P 500 Index as well as the collection of 1819 constituents of the New York Stock Exchange Composite Index on 17 July 2009. As a new method to estimate α̃, we calculate the time intervals τq between events where R̃ > q. We demonstrate that τ̃q, the average of τq, obeys τ̃q ∼ qα̃. We find α̃ ≈ 3. Furthermore, by aggregating all τq values of 28 global financial indices, we also observe an approximate inverse cubic law. Boris PodobnikDavor HorvaticAlexander M. Petersenalexander.petersen@imtlucca.itH. Eugene Stanley2011-06-30T14:27:33Z2011-08-31T14:40:38Zhttp://eprints.imtlucca.it/id/eprint/635This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6352011-06-30T14:27:33ZPatent disclosure and R&D competition in pharmaceuticalsThe prominent role played by patents within the pharmaceutical domain is unquestionable. In this paper, we focus on a relatively neglected implication of patents: the effect of patent-induced information disclosure on the dynamics of R&D and market competition. The study builds upon the combination of two large datasets, linking the information about patents to firm-level data on R&D projects and their outcome. Two case studies in the fields of anti-inflammatory compounds and cancer research complement our analysis. We argue that patent disclosure induces R&D competition and shapes firms' technological trajectories. In fact, we show that under conditions of uncertainty, patent disclosure can contribute to generate knowledge spillovers, promoting multiple parallel research efforts on plausible targets and stimulating private investment and competition. Fabio Pammollif.pammolli@imtlucca.itLaura MagazziniMassimo Riccabonimassimo.riccaboni@imtlucca.itMaria Alessandra Rossi2011-06-30T14:27:24Z2011-08-31T14:40:38Zhttp://eprints.imtlucca.it/id/eprint/636This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6362011-06-30T14:27:24ZA Breath of Fresh Air? Firm Type, Scale, Scope, and Selection Effects in Drug DevelopmentThis paper compares the innovation performance of established pharmaceutical firms and biotech companies, controlling for differences in the scale and scope of research. We develop a structural model to analyze more than 3,000 drug research and development projects advanced to preclinical and clinical trials in the United States between 1980 and 1994. Key to our approach is careful attention to the issue of selection. Firms choose which compounds to advance into clinical trials. This choice depends not only on the technical promise of the compound, but also on commercial considerations such as the expected profitability of the market or concerns about product cannibalization. After controlling for selection, we find that (a) even after controlling for scale and scope in research, established pharmaceutical firms are more innovative than newly entered biotech firms; (b) older biotech firms display selection behaviors and innovation performances similar to established pharmaceutical firms; and (c) compounds licensed during preclinical trials are as likely to succeed as internal compounds of the licensor, which is inconsistent with the "lemons" hypothesis in technology markets. Fabio Pammollif.pammolli@imtlucca.itAshish AroraAlfonso GambardellaLaura Magazzini2011-06-30T14:23:12Z2011-08-31T14:40:38Zhttp://eprints.imtlucca.it/id/eprint/675This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6752011-06-30T14:23:12ZRequisiti anagrafici di accesso alle pensioni differenziati tra pilastro pubblico e pilastro privato, per riformare il" welfare system" rispettando le scelte individualiFabio Pammollif.pammolli@imtlucca.itNicola C. Salerno2011-06-30T14:22:48Z2011-08-31T14:40:38Zhttp://eprints.imtlucca.it/id/eprint/676This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6762011-06-30T14:22:48ZCorte di giustizia, età di pensionamento di vecchiaia per le donne e riforma delle pensioni e del welfare in ItaliaFabio Pammollif.pammolli@imtlucca.itNicola C. Salerno2011-06-21T14:19:10Z2011-08-04T07:29:06Zhttp://eprints.imtlucca.it/id/eprint/623This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6232011-06-21T14:19:10ZTools for modeling, simulation, control, and verification of piecewise affine systemsAlberto Bemporadalberto.bemporad@imtlucca.itStefano Di CairanoGiancarlo Ferrari-TrecateMichal KvasnicaManfred MorariSimone Paoletti2011-06-15T13:40:09Z2014-10-08T09:40:50Zhttp://eprints.imtlucca.it/id/eprint/409This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4092011-06-15T13:40:09ZFrom architectural to behavioural specification of servicesMany efforts are currently devoted to provide software developers with methods and techniques that can endow service-oriented computing with systematic and accountable engineering practices. To this purpose, a number of languages and calculi have been proposed within the Sensoria project that address different levels of abstraction of the software engineering process. Here, we report on two such languages and the way they can be formally related within an integrated approach that can lead to verifiable development of service components from more abstract architectural models of business activities.Laura BocchiJose Luiz FiadeiroAlessandro LapadulaRosario PuglieseFrancesco Tiezzifrancesco.tiezzi@imtlucca.it2011-06-15T13:31:10Z2014-10-08T09:31:57Zhttp://eprints.imtlucca.it/id/eprint/408This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4082011-06-15T13:31:10ZA symbolic semantics for a clculus for service-oriented computingWe introduce a symbolic characterisation of the operational semantics of COWS, a formal language for specifying and combining service-oriented applications, while modelling their dynamic behaviour. This alternative semantics avoids infinite representations of COWS terms due to the value-passing nature of communication in COWS and is more amenable for automatic manipulation by analytical tools, such as e.g. equivalence and model checkers. We illustrate our approach through a ‘translation service’ scenario.Rosario PuglieseFrancesco Tiezzifrancesco.tiezzi@imtlucca.itNobuko Yoshida2011-06-15T13:25:13Z2014-10-08T09:43:28Zhttp://eprints.imtlucca.it/id/eprint/407This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4072011-06-15T13:25:13ZSpecification and analysis of SOC systems using COWS: a finance case studyService-oriented computing, an emerging paradigm for distributed computing based on the use of services, is calling for the development of tools and techniques to build safe and trustworthy systems, and to analyse their behaviour. Therefore many researchers have proposed to use process calculi, a cornerstone of current foundational research on specification and analysis of concurrent and distributed systems.
We illustrate this approach by focussing on COWS, a process calculus expressly designed for specifying and combining services, while modelling their dynamic behaviour. We present the calculus and one of the analysis techniques it enables, that is based on the temporal logic SocL and the associated model checker CMC. We demonstrate applicability of our tools by means of a large case study, from the financial domain, which is first specified in COWS, and then analysed by using SocL to express many significant properties and CMC to verify them.Federico BantiAlessandro LapadulaRosario PuglieseFrancesco Tiezzifrancesco.tiezzi@imtlucca.it2011-06-15T13:03:05Z2011-07-11T14:35:30Zhttp://eprints.imtlucca.it/id/eprint/405This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4052011-06-15T13:03:05ZOn Observing Dynamic Prioritised Actions in SOCWe study the impact on observational semantics for SOC of priority mechanisms which combine dynamic priority with local pre-emption. We define manageable notions of strong and weak labelled bisimilarities for COWS, a process calculus for SOC, and provide alternative characterisations in terms of open barbed bisimilarities. These semantics show that COWS’s priority mechanisms partially recover the capability to observe receive actions (that could not be observed in a purely asynchronous setting) and that high priority primitives for termination impose specific conditions on the bisimilarities. Rosario PuglieseFrancesco Tiezzifrancesco.tiezzi@imtlucca.itNobuko Yoshida2011-06-15T12:52:15Z2011-07-11T14:35:30Zhttp://eprints.imtlucca.it/id/eprint/406This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4062011-06-15T12:52:15ZOn Secure Implementation of an IHE XUA-Based Protocol for Authenticating Healthcare ProfessionalsThe importance of the Electronic Health Record (EHR) has been addressed in recent years by governments and institutions.Many large scale projects have been funded with the aim to allow healthcare professionals to consult patients data. Properties such as confidentiality, authentication and authorization are the key for the success for these projects. The Integrating the Healthcare Enterprise (IHE) initiative promotes the coordinated use of established standards for authenticated and secure EHR exchanges among clinics and hospitals. In particular, the IHE integration profile named XUA permits to attest user identities by relying on SAML assertions, i.e. XML documents containing authentication statements. In this paper, we provide a formal model for the secure issuance of such an assertion. We first specify the scenario using the process calculus COWS and then analyse it using the model checker CMC. Our analysis reveals a potential flaw in the XUA profile when using a SAML assertion in an unprotected network. We then suggest a solution for this flaw, and model check and implement this solution to show that it is secure and feasible. Massimiliano MasiRosario PuglieseFrancesco Tiezzifrancesco.tiezzi@imtlucca.it2011-05-26T10:16:54Z2014-03-03T11:59:47Zhttp://eprints.imtlucca.it/id/eprint/282This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2822011-05-26T10:16:54ZProvably Correct Implementations of ServicesA number of formalisms have been defined to support the specification and analysis of service oriented applications. These formalisms have been equipped with tools (types or logics) to guarantee the correct behavior of the specified services. Due to the semantic gap between the specification formalism and the programming languages of service oriented overlay computers a critical issue is guaranteeing that correctness is preserved when running the specified systems over available implementations. We have defined a service oriented abstract machine, equipped with a formal structural semantics, that can be used to implement service specification formalisms. We use our abstract machine to implement different service oriented formalisms that have been recently proposed, each posing specific challenges that we can address successfully. By exploiting the SOS semantics of the abstract machine and those of the considered service oriented formalisms we do prove that our implementations are correct (sound and complete). We also discuss possible implementations of other formalisms.
Roberto BruniRocco De Nicolar.denicola@imtlucca.itMichele LoretiLeonardo Gaetano Mezzina2011-05-25T13:18:28Z2014-10-08T09:33:54Zhttp://eprints.imtlucca.it/id/eprint/276This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2762011-05-25T13:18:28ZMarCaSPiS: a Markovian Extension of a Calculus for ServicesService Oriented Computing (SOC) is a design paradigm that has evolved from earlier paradigms including object-orientation and component-based software engineering. Important features of services are compositionality, context-independence, encapsulation and re-usability. To support the formal design and analysis of SOC applications recently a number of Service Oriented Calculi have been proposed. Most of them are based on process algebras enriched with primitives specific of service orientation such as operators for manipulating semi-structured data, mechanisms for describing safe client-service interactions, constructors for composing possibly unreliable services and techniques for services query and discovery. In this paper we show a versatile technique for the definition of Structural Operational Semantics of MarCaSPiS, a Markovian extension of one of such calculi, namely the Calculus of Sessions and Pipelines, CaSPiS. The semantics deals in an elegant way with a stochastic version of two-party synchronisation, typical of a service-oriented approach, and with the problem of transition multiplicity while preserving highly desirable mathematical properties such as associativity and commutativity of parallel composition.
We also show how the proposed semantics can be naturally used for defining a bisimulation-based behavioural equivalence for MarCaSPiS terms that induces the same equalities as those obtained via Strong Markovian Equivalence.Rocco De Nicolar.denicola@imtlucca.itDiego LatellaMichele LoretiMieke Massink2011-05-25T10:30:52Z2011-07-11T14:36:25Zhttp://eprints.imtlucca.it/id/eprint/275This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2752011-05-25T10:30:52ZRate-Based Transition Systems for Stochastic Process CalculiA variant of Rate Transition Systems (RTS), proposed by Klin and Sassone, is introduced and used as the basic model for defining stochastic behaviour of processes. The transition relation used in our variant associates to each process, for each action, the set of possible futures paired with a measure indicating their rates. We show how RTS can be used for providing the operational semantics of stochastic extensions of classical formalisms, namely CSP and CCS. We also show that our semantics for stochastic CCS guarantees associativity of parallel composition. Similarly, in contrast with the original definition by Priami, we argue that a semantics for stochastic π-calculus can be provided that guarantees associativity of parallel composition. Rocco De Nicolar.denicola@imtlucca.itDiego LatellaMichele LoretiMieke Massink2011-05-25T10:17:05Z2011-07-11T14:36:24Zhttp://eprints.imtlucca.it/id/eprint/274This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2742011-05-25T10:17:05ZOn a Uniform Framework for the Definition of Stochastic Process LanguagesIn this paper we show how Rate Transition Systems (RTSs) can be used as a unifying framework for the definition of the semantics of stochastic process algebras. RTSs facilitate the compositional definition of such semantics exploiting operators on the next state functions which are the functional counterpart of classical process algebra operators. We apply this framework to representative fragments of major stochastic process calculi namely TIPP, PEPA and IML and show how they solve the issue of transition multiplicity in a simple and elegant way. We, moreover, show how RTSs help describing different languages, their differences and their similarities. For each calculus, we also show the formal correspondence between the RTSs semantics and the standard SOS one.Rocco De Nicolar.denicola@imtlucca.itDiego LatellaMichele LoretiMieke Massink2011-05-18T10:31:57Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/147This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1472011-05-18T10:31:57ZA Graph Syntax for Processes and ServicesWe propose a class of hierarchical graphs equipped with a simple algebraic syntax as a convenient way to describe configurations in languages with inherently hierarchical features such as sessions, fault- handling scopes or transactions. The graph syntax can be seen as an intermediate representation language, that facilitates the encoding of structured specifications and, in particular, of process calculi, since it provides primitives for nesting, name restriction and parallel composition. The syntax is based on an algebraic presentation that faithfully characterises families of hierarchical graphs, meaning that each term of the language uniquely identifies an equivalence class of graphs (modulo graph isomorphism). Proving soundness and completeness of an encoding (i.e. proving that structurally equivalent processes are mapped to isomorphic graphs) is then facilitated and can be done by structural induction. Summing up, the graph syntax facilitates the definition of faithful encodings, yet allowing a precise visual representation. We illustrate our work with an application to a workflow language and a service-oriented calculus.Roberto BruniFabio GadducciAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-05-18T10:27:27Z2016-04-06T07:57:34Zhttp://eprints.imtlucca.it/id/eprint/146This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1462011-05-18T10:27:27ZA Service-Oriented UML Profile with Formal SupportWe present a UML Profile for the description of service oriented applications. The profile focuses on style-based design and reconfiguration aspects at the architectural level. Moreover, it has formal support in terms of an approach called Architectural Design Rewriting, which enables formal analysis of the UML specifications. We show how our prototypical implementation can be used to analyse and verify properties of a service oriented application.
Roberto BruniMatthias HölzlNora KochAlberto Lluch-Lafuentealberto.lluch@imtlucca.itPhilip MayerUgo MontanariAndreas SchroederMartin Wirsing2011-05-18T08:46:12Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/148This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1482011-05-18T08:46:12ZA Formalisation of Adaptable Pervasive FlowsAdaptable Pervasive Flows is a novel workflow-based paradigm for the design and execution of pervasive applications, where dynamic workflows situated in the real world are able to modify their execution in order to adapt to changes in their environment. In this paper, we study a formalisation of such flows by means of a formal flow language. More precisely, we define APFoL (Adaptable Pervasive Flow Language) and formalise its textual notation by encoding it in Blite, a formalisation of WS-BPEL. The encoding in Blite equips the language with a formal semantics and enables the use of automated verification techniques. We illustrate the approach with an example of a Warehouse Case Study.
Antonio BucchiaroneAlberto Lluch-Lafuentealberto.lluch@imtlucca.itAnnapaola MarconiMarco Pistore2011-05-17T15:01:44Z2014-10-08T09:39:01Zhttp://eprints.imtlucca.it/id/eprint/150This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1502011-05-17T15:01:44ZOn symbolic semantics for name-decorated contextsUnder several regards, various of the recently proposed computational paradigms are open-ended, i.e. they may comprise components whose behaviour is not or cannot be fully specified. For instance, applications can be distributed across different administration domains that do not fully disclose their internal business processes to each other, or the dynamics of the system may allow reconfigurations and dynamic bindings whose specification is not available at design time. While a large set of mature design and analysis techniques for closed systems have been developed, their lifting to the open case is not always straightforward. Some existing approaches in the process calculi community are based on the need of proving properties for components that may hold in any, or significantly many, execution environments. Dually, frameworks describing the dynamics of systems with unspecified components have also been presented. In this paper we lay some preliminary ideas on how to extend a symbolic semantics model for open systems in order to deal with name-based calculi. Moreover, we also discuss how the use of a simple type system based on name-decoration for unknown components can improve the expressiveness of the framework. The approach is illustrated on a simple, paradigmatic calculus of web crawlers, which can be understood as a term representation of a simple class of graphs.Andrea BraccialiRoberto BruniAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-05-17T14:56:11Z2014-10-08T09:36:46Zhttp://eprints.imtlucca.it/id/eprint/151This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1512011-05-17T14:56:11ZHierarchical design rewriting with MaudeArchitectural Design Rewriting (ADR) is a rule-based approach for the design of dynamic software architectures. The key features that make ADR a suitable and expressive framework are the algebraic presentation and the use of conditional rewrite rules. These features enable, e.g. hierarchical (top-down, bottom-up or composition-based) design and inductively-defined reconfigurations. The contribution of this paper is twofold: we define Hierarchical Design Rewriting (HDR) and present our prototypical tool support. HDR is a flavour of ADR that exploits the concept of hierarchical graph to deal with system specifications combining both symbolic and interpreted parts. Our prototypical implementation is based on Maude and its presentation serves several purposes. First, we show that HDR is not only a well-founded formal approach but also a tool-supported framework for the design and analysis of software architectures. Second, our illustration tailored to a particular algebra of designs and a particular scenario traces a general methodology for the reuse and exploitation of ADR concepts in other scenarios.
Roberto BruniAlberto Lluch-Lafuentealberto.lluch@imtlucca.itUgo Montanari2011-05-13T13:17:12Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/152This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1522011-05-13T13:17:12ZPartial-order reduction for general state exploring algorithms Partial-order reduction is one of the main techniques used to tackle the combinatorial state explosion problem occurring in explicit-state model checking of concurrent systems. The reduction is performed by exploiting the independence of concurrently executed events, which allows portions of the state space to be pruned. An important condition for the soundness of partial-order-based reduction algorithms is a condition that prevents indefinite ignoring of actions when pruning the state space. This condition is commonly known as the cycle proviso. In this paper, we present a new version of this proviso, which is applicable to a general search algorithm skeleton that we refer to as the general state exploring algorithm (GSEA). GSEA maintains a set of open states from which states are iteratively selected for expansion and moved to a closed set of states. Depending on the data structure used to represent the open set, GSEA can be instantiated as a depth-first, a breadth-first, or a directed search algorithm such as Best-First Search or A*. The proviso is characterized by reference to the open and closed set of states of the search algorithm. As a result, it can be computed in an efficient manner during the search based on local information. We implemented partial-order reduction for GSEA based on our proposed proviso in the tool HSF-SPIN, an extension of the explicit-state model checker SPIN for directed model checking. We evaluate the state space reduction achieved by partial-order reduction using the proposed proviso by comparing it on a set of benchmark problems to the use of other provisos. We also compare the use of breadth-first search (BFS) and A*, two algorithms ensuring that counterexamples of minimal length will be found, together with the proviso that we propose.
Dragan BosnackiStefan LeueAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-04-04T13:33:37Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/255This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2552011-04-04T13:33:37ZTranslation: La politica della concorrenza in epoca di crisi by John Fingleton Il contributo analizza il legame tra politica della concorrenza e recessione economica. In particolare, viene approfondito il tema della fiducia nella capacità degli assetti concorrenziali di produrre effetti positivi, messa sostanzialmente a rischio dalla crisi finanziaria e dallo stato di recessione. Si approfondiscono inoltre il ruolo e le modalità di intervento delle autorità di garanzia che devono essere capaci di rispondere rapidamente alle nuove priorità, mettendo in campo una buona dose di pragmatismo nel riconoscere le condizioni nelle quali la tutela della concorrenza possa essere accantonata in funzione di interessi politici differenti. Andrea Giannaccaria.giannaccari@imtlucca.it2011-04-04T13:27:52Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/253This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2532011-04-04T13:27:52ZTranslation: Tutela della concorrenza e tutela dei consumatori. Due fini confliggenti? by Heike SchweitzerAndrea Giannaccaria.giannaccari@imtlucca.it2011-04-01T10:10:21Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/252This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2522011-04-01T10:10:21ZTranslation: La sorte del monopolio al vaglio antitrust. Dubbi e prospettive interpretative dal fronte nord-americano, by Rudolph J.R. PeritzAndrea Giannaccaria.giannaccari@imtlucca.it2011-03-31T14:41:48Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/149This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1492011-03-31T14:41:48ZTen virtues of structured graphsThis paper extends the invited talk by the first author about the virtues
of structured graphs. The motivation behind the talk and this paper relies on our
experience on the development of ADR, a formal approach for the design of styleconformant,
reconfigurable software systems. ADR is based on hierarchical graphs
with interfaces and it has been conceived in the attempt of reconciling software architectures
and process calculi by means of graphical methods. We have tried to
write an ADR agnostic paper where we raise some drawbacks of flat, unstructured
graphs for the design and analysis of software systems and we argue that hierarchical,
structured graphs can alleviate such drawbacks.Roberto BruniAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-03-30T10:15:51Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/229This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2292011-03-30T10:15:51ZIl caso Europa 7 al Consiglio di StatoNota a Consiglio di Stato, sezione VI, sentenza 20 gennaio 2009, n. 242, Centro Europa 7 c. Ministero dello sviluppo economico.Andrea Giannaccaria.giannaccari@imtlucca.it2011-03-30T10:13:37Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/245This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2452011-03-30T10:13:37ZNota a sentenza: Corte d’Appello di Milano, ordinanza 4 novembre 2009.Andrea Giannaccaria.giannaccari@imtlucca.itRoberto Pardolesi2011-03-23T12:48:55Z2011-07-11T13:54:05Zhttp://eprints.imtlucca.it/id/eprint/186This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1862011-03-23T12:48:55ZIl “disastro” di Suez nel dibattito pubblico francese: crisi del socialismo, dell’élite politica e dell’identità franceseLucia Bonfreschilucia.bonfreschi@imtlucca.it2011-03-23T12:48:40Z2011-07-11T13:54:05Zhttp://eprints.imtlucca.it/id/eprint/187This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1872011-03-23T12:48:40ZJean Monnet et le retour au pouvoir du général de Gaulle en 1958Lucia Bonfreschilucia.bonfreschi@imtlucca.it2011-03-23T11:11:34Z2011-07-11T14:27:36Zhttp://eprints.imtlucca.it/id/eprint/214This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2142011-03-23T11:11:34ZSaggi sul pensiero politico contemporaneo: IntroduzioneAntonio Masalaa.masala@imtlucca.it2011-03-10T10:09:31Z2011-07-11T14:27:36Zhttp://eprints.imtlucca.it/id/eprint/193This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1932011-03-10T10:09:31ZMorte presunta e resurrezione incerta della Filosofia Politica nel NovecentoThe idea that Political Philosophy was going through a deep crisis in the first half of the twentieth century, and that it reawakened, more or less unexpectedly, only in 1971, with A Theory of Justice from John Rawls, had been a deeply-rooted common place in political studies for long time. Several thinkers have seen the “old tradition” succumb under the strokes of historicism, positivism and relativism, and some important philosopher (like Leo Strauss, Sheldon Wolin, Eric Voegelin) have laid the responsibility of the crisis on liberalism. Even though that common place is today often considered groundless, it is interesting to analyze it, at least from the post-war period. In fact those thinkers gave rise to a sort of “unconscious debate”, and the problems raised regarded not only political philosophy as discipline, but some crucial points regarding some of the main political theories. Such analyses can also be useful to make clear some differences between different political theories and in particular to evaluate the evolution of liberalism, a theory whose definition often seems controversial. Antonio Masalaa.masala@imtlucca.it2011-03-02T11:04:47Z2011-07-11T14:33:42Zhttp://eprints.imtlucca.it/id/eprint/118This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1182011-03-02T11:04:47ZAbstract Processes in Orchestration LanguagesOrchestrators are descriptions at implementation level and may contain sensitive information that should be kept private. Consequently, orchestration languages come equipped with a notion of abstract processes, which enable the interaction among parties while hiding private information. An interesting question is whether an abstract process accurately describes the behavior of a concrete process so to ensure that some particular property is preserved when composing services. In this paper we focus on compliance, i.e, the correct interaction of two orchestrators and we introduce two definitions of abstraction: one in terms of traces, called trace-based abstraction, and the other as a generalization of symbolic bisimulation, called simulation-based abstraction. We show that simulation-based abstraction is strictly more refined than trace-based abstraction and that simulation-based abstraction behaves well with respect to compliance. Maria Grazia Buscemim.buscemi@imtlucca.itHernán C. Melgratti2011-02-25T10:08:25Z2013-05-29T12:40:05Zhttp://eprints.imtlucca.it/id/eprint/104This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1042011-02-25T10:08:25ZEuropeismo e opposizione democratica dal franchismo alla transizione democraticaIn this essay I analyze both the history of moderate opposition to the Franco’s regime devoloped inside and outside the country. I underline the differnces between their antiregime activities, organizations, goals, militants and how the inside and outside groups succeded in talking to each other and find a common stategy. It happened in Germany during the annual meeting of the European Movement conference (1962) devoted to the role played by the European institutions. I describe how the process of reconciliation between the two groups took place there, which was the role played by the European Movement, the one played by the Communist party (PCE) and how the result of the European Movement conference influenced the anti Franco’s activity during the latest years of the regime up to the death of the dictator. And finally I try to describe how the Europeanism which characterized these groups was later on absorbed by the several political parties legalized in 1977.Maria Elena Cavallarom.cavallaro@imtlucca.it2011-02-25T09:59:00Z2013-05-29T12:40:38Zhttp://eprints.imtlucca.it/id/eprint/103This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1032011-02-25T09:59:00ZThe Spanish European Integration. The First Steps of a Long Journey The article focus on two main aspects. First of all the attention on the european policy developed by regime during the Sixties and secondly the reactions it caused at supranational level both within the EEC Council of Ministers, The Eu Commission, The Council of Europe. It tries to show how much the action and the reports delivered at supranational level influenced later on during the Seventies, and above all after Franco death, the european approach of the several spanish political parties. Maria Elena Cavallarom.cavallaro@imtlucca.it2011-02-25T09:51:09Z2013-05-29T12:59:15Zhttp://eprints.imtlucca.it/id/eprint/102This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1022011-02-25T09:51:09ZLos origenes de la integraciόn de España en Europa. Desde el franquismo a los años de la transiciόnThis aim of this book is to show the long run origin of the Europeanism as a movement in Spain and to underline how Spain during the transition to democracy bet on its own European future within the EEC Institutions because it has already matured a long tradition and a very well developed knowledge of the European mechanism at least from the Sixties. The book is divided into three chapters. The first one describes the Spanish foreign policy in particular from the late Fifties to the late Seventies and it explains which was the meaning the regime assigned to the Europeanization of Spain. I underline the specific economic value tribute to Europeanism by the majority of the political family of the regime, but I also reproduce the internal debate explaining which political families sustain the European model who do not , and why.
In the second chapter I analize the meaning of Europeanism for the moderate opposition to the regime. I explain how it was linked to democratic values and to the plan to overtrow the dictatorship. I also show how under the umbrella of Europeanism a fragmentated opposition found a shared starting point to overcome the dictatorship and then it became less vulnerable. In the third and latest chapter I analyze how the Europeanism of the previous decades influenced the political parties foreign policy guidelines, and why every single party in the parliament even with different reasons behind it was in favour of the Spanish EEC integration as soon as it was possible. I also explain how every single party interpreted this measure as a confirmation of an external support and legitimization of the Spanish transition to democracy.Maria Elena Cavallarom.cavallaro@imtlucca.it2011-02-25T09:18:58Z2011-07-11T14:00:42Zhttp://eprints.imtlucca.it/id/eprint/99This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/992011-02-25T09:18:58ZThe Patent Quality Control Process: Can We Afford An
(Rationally) Ignorant Patent Office?This paper considers patent granting as a two-tiered process, which consists of
patent office examination (public enforcement) and court challenges (private enforcement).
It argues that, when the patent-holder has private information about the patent
validity, (i) a weak patent is more likely to be settled and thus escape court challenges
than a strong patent; and (ii) when the economy suffers from the low patent quality
problem, a tighter examination by the patent office may strengthen private scrutiny
over a weak patent. Both work against Lemley (2001)’s hypothesis of a “rationally
ignorant” patent office.Jing-Yuan Chioujy.chiou@imtlucca.it2011-02-25T09:11:56Z2011-07-11T14:00:42Zhttp://eprints.imtlucca.it/id/eprint/98This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/982011-02-25T09:11:56ZThe Design of Post-Grant Patent ChallengesThis paper proposes a patent challenge mechanism with partial patent rights previously
granted to the patent-holder as the challenge reward. Transferring patent
rights to a successful challenger raises the incentive to search for patent-defeating prior
art, and, after the discovery of the information, helps deter collusion between the
patent-holder and the challenger. It also reduces costly opportunistic patenting and
therefore improves patent application quality. However, from an ex post point of view,
over-search ensues when the collusion problem is severe. The optimal re-allocation of
patent rights, then, calls for a careful balance between these costs and benefits.
Jing-Yuan Chioujy.chiou@imtlucca.it2011-02-22T15:57:22Z2011-07-11T14:25:31Zhttp://eprints.imtlucca.it/id/eprint/89This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/892011-02-22T15:57:22ZReassessing the Link between Voter Heterogeneity and Political
Accountability: A Latent Class Regression Model of Economic
VotingWhile recent research has underscored the conditioning effect of individual characteristics on economic voting behavior, most empirical studies have failed to explicitly incorporate observed heterogeneity into statistical analyses linking citizens' economic evaluations to electoral choices. In order to overcome these drawbacks, we propose a latent
class regression model to jointly analyze the determinants and influence of economic
voting in Presidential and Congressional elections. Our modeling approach allows us to
better describe the effects of individual covariates on economic voting and to test hypotheses on the existence of heterogeneous types of voters, providing an empirical basis
for assessing the relative validity of alternative explanations proposed in the literature.
Using survey data from the 2004 U.S. Presidential, Senate and House elections, we
and that voters with college education and those more interested in political campaigns
based their vote on factors other than their economic perceptions. In contrast, less educated and interested respondents assigned considerable weight to economic assessments,
with sociotropic jugdgments strongly in
uencing their vote in the Presidential election
and personal financial considerations affecting their vote in House elections. We conclude that the main distinction in the 2004 election was not between `sociotropic' and
`pocketbook' voters, but rather between `economic' and `non-economic' voters.Jonathan N. KatzGabriel Katzg.katz@imtlucca.it2011-02-22T15:54:05Z2011-07-11T14:25:31Zhttp://eprints.imtlucca.it/id/eprint/85This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/852011-02-22T15:54:05ZAssessing Voters’ Attitudes towards Electronic Voting in Latin America: Evidence from Colombia’s 2007 E-Voting PilotElectronic voting could increase citizens’ electoral participation and trust in countries characterized by fragile democratic institutions and public discredit of the political system such as those in Latin America. This paper examines attitudes towards e-voting among participants in a large scale pilot project conducted in Colombia in 2007, focusing on the perceived reliability and usability of different automated voting technologies. Using a multivariate probit model, we determine the effect of socio-demographic, geographic and technical factors on users’ evaluations of electronic voting vis a vis the traditional paper ballot system. Our results show that users find e-voting not only easier than the current voting system, but also substantially more reliable. While voters’ opinions on usability are driven by technical issues, their trust in the new technologies is strongly affected by individual characteristics. We conclude that e-voting entails a promising opportunity to empower voters and increase confidence in elections in Colombia. R. Michael AlvarezGabriel Katzg.katz@imtlucca.itRicardo LlamosaHugo E. Martinez2011-02-22T15:52:33Z2011-07-11T14:25:31Zhttp://eprints.imtlucca.it/id/eprint/84This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/842011-02-22T15:52:33ZStructural cleavages, electoral competition and partisan divide: A Bayesian multinomial probit analysis of Chile's 2005 electionThe transformations in Chile's party structure since 1989 have led several authors to examine the main cleavages shaping partisan divisions and the impact of different factors on citizens' party preferences. Previous studies, however, failed to analyze the effect of these variables on actual vote choice and neglected the influence of election-specific factors. In order to address these issues, we implement a Bayesian multinomial probit model to analyze Chile's 2005 election. We show that, while both socio-demographic variables and attitudes towards democracy affected voter behavior, the latter were the main determinants of the choice between Chile's two main political coalitions. In addition, we find that the presence of a second conservative candidate, together with voters' strategic considerations, significantly affected candidate choice. These results cannot be accounted for by analyses focused on citizens' party identification or by methodologies that ignore the effect of substitution patterns between candidates on voters' electoral behavior.R. Michael AlvarezGabriel Katzg.katz@imtlucca.it2011-02-15T11:47:44Z2011-07-11T14:24:17Zhttp://eprints.imtlucca.it/id/eprint/73This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/732011-02-15T11:47:44ZThe Engraved Frontispiece of Kepler’s Tabulae Rudolphinae (1627): A Preliminary
StudyJohannes Kepler completed the Tabulae Rudolphinae in their logarithmic
form in 1624. It then took three years to gather the financial support, find a
suitable publisher and, particularly, overcome the difficulties posed by
Tycho’s heirs, who claimed both a share in the profits as well as censorship
rights. The tables represented the crowning achievement of Kepler’s career
as an astronomer. Because of their novelty and importance, he proposed
that the tall folio volume should have an appropriate frontispiece. The
paper describes the meaning of the very many components of the engraving
and relates them to Kepler’s published works. Furthermore, it traces the
origin of Kepler’s frontispiece to Tycho’s observatory on the Isle of Hven, as
well as suggests the possible pictorial source of the key element of the
drawing. Finally, it highlights how Kepler, by way of this frontispiece, found
the way both to assert his own position in and contribution to the history of
astronomy, as well as to place himself in the dispute over the Copernican
hypothesis.Stefano Gatteistefano.gattei@imtlucca.it2011-02-15T10:32:44Z2011-07-11T14:24:17Zhttp://eprints.imtlucca.it/id/eprint/61This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/612011-02-15T10:32:44ZGalileo ‘filosofo’Stefano Gatteistefano.gattei@imtlucca.it2011-02-15T10:30:50Z2011-07-11T14:24:17Zhttp://eprints.imtlucca.it/id/eprint/62This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/622011-02-15T10:30:50ZWhy and to What Extent May a False Hypothesis Yield the TruthSome of Kepler's works seem very different in character. His youthful
Mysterium cosmographicum (1596) argues for heliocentrism on the basis of metaphysical,
astronomical, astrological, numerological and architectonic principles. By
contrast, Astronomia nova (1609) is far more tightly argued on the basis of only a
few dynamical principles. In the eyes of many, such a contrast embodies a transition
from Renaissance to early modern science. I suggest that Karl Popper's fallibilist and
piecemeal approach, and especially his theory of errors, might prove extremely helpful
in resolving such alleged tension. By abandoning the perspective of the inductivist
philosophy of science, which is forced by its own standards to portray Kepler as a "sleepwalker", I focus on the method he followed: he never hesitated to discuss his
own intellectual journey, offering a rational reconstruction of the series of false starts,
blind alleys and failures he encountered. The critical dialogue he managed to establish
in private correspondence with fellow astronomers he later transplanted into his printed
works, whose structure closely resembles that of a dialogue, however implicit.Stefano Gatteistefano.gattei@imtlucca.it2011-02-11T15:18:55Z2015-10-21T11:29:31Zhttp://eprints.imtlucca.it/id/eprint/57This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/572011-02-11T15:18:55ZKarl Popper's Philosophy of Science: Rationality without Foundations Stefano Gatteistefano.gattei@imtlucca.it2011-02-09T09:28:13Z2011-07-11T14:32:25Zhttp://eprints.imtlucca.it/id/eprint/42This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/422011-02-09T09:28:13ZThe Endurance of National ConstitutionsZachary ElkinsTom GinsburgJames Meltonjames.melton@imtlucca.it2011-02-07T11:57:23Z2011-09-29T13:47:20Zhttp://eprints.imtlucca.it/id/eprint/20This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/202011-02-07T11:57:23ZFiscal Centralization, Limited Government, and Public Revenues in Europe, 1650-1913Old Regime polities typically suffered from fiscal fragmentation and absolutist rule. By the start of World War I, however, many such countries had centralized institutions and limited government. This article uses a new panel data set to perform a statistical analysis of political regimes and public revenues in Europe from 1650 to 1913. Panel regressions indicate that centralized and limited regimes were associated with significantly higher revenues than fragmented and absolutist ones. Structural break tests also suggest close relationships between major turning points in revenue series and political transformations. Mark Dinceccom.dincecco@imtlucca.it2011-02-07T11:48:24Z2012-03-19T08:16:32Zhttp://eprints.imtlucca.it/id/eprint/19This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/192011-02-07T11:48:24ZPolitical Regimes and Sovereign Credit Risk in Europe, 1750-1913This article uses a new panel data set to perform a statistical analysis of political regimes and sovereign credit risk in Europe from 1750 to 1913. Old Regime polities typically suffered from fiscal fragmentation and absolutist rule. By the start of World War I, however, many such countries had centralized institutions and limited government. Panel regressions indicate that centralized and?or limited regimes were associated with significant improvements in credit risk relative to fragmented and absolutist ones. Structural break tests also reveal close relationships between major turning points in yield series and political transformations. Mark Dinceccom.dincecco@imtlucca.it