IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2023-12-04T17:00:33ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2016-09-13T08:20:42Z2016-09-13T08:20:42Zhttp://eprints.imtlucca.it/id/eprint/3538This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/35382016-09-13T08:20:42ZNeural correlates of spatial working memory in humans: a functional magnetic resonance imaging study comparing visual and tactile processesRecent studies of neural correlates of working memory components have identified both low-level perceptual processes and higher-order supramodal mechanisms through which sensory information can be integrated and manipulated. In addition to the primary sensory cortices, working memory relies on a widely distributed neural system of higher-order association areas that includes posterior parietal and occipital areas, and on prefrontal cortex for maintaining and manipulating information. The present study was designed to determine brain patterns of neural response to the same spatial working memory task presented either visually or in a tactile format, and to evaluate the relationship between spatial processing in the visual and tactile sensory modalities. Brain activity during visual and tactile spatial working memory tasks was measured in six young right-handed healthy male volunteers by using functional magnetic resonance imaging. Results indicated that similar fronto-parietal networks were recruited during spatial information processing across the two sensory modalities—specifically the posterior parietal cortex, the dorsolateral prefrontal cortex and the anterior cingulate cortex. These findings provide a neurobiological support to behavioral observations by indicating that common cerebral regions subserve generation of higher order mental representations involved in working memory independently from a specific sensory modality.Emiliano Ricciardiemiliano.ricciardi@imtlucca.itDaniela BoninoClaudio GentiliLorenzo SaniPietro Pietrinipietro.pietrini@imtlucca.itTomaso Vecchi2016-09-13T08:14:47Z2016-09-13T08:14:47Zhttp://eprints.imtlucca.it/id/eprint/3537This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/35372016-09-13T08:14:47ZCombination of event-related potentials and functional magnetic resonance imaging during single-letter readingThis work proposes a mathematical approach for combining event-related potentials (ERPs) and functional magnetic resonance images (fMRI). Data were separately recorded during the same event-related experimental design, consisting of visually presented single letters and non-alphabetic symbols, that had to be either simply observed (passive condition) or read aloud (active condition). This protocol was useful for exploring the neural correlates of reading processes. Healthy adults participated in the experiment. Averaged ERPs were decomposed by independent component analysis; low resolution electromagnetic tomography (LORETA) was applied to estimate the current density distribution maps of each independent component. fMRI images time series were analyzed by multiple linear regression. ERP-fMRI correspondence was quantified by computing the Euclidean distance between LORETA local maxima and clusters of significantly activated fMRI voxels. During reading aloud of letters, that is clearly the task most similar to natural reading conditions, significant electrical and hemodynamic response was observed in the left medial frontal gyrus (BA 6) and left middle temporal gyrus (BA 22/39) just before articulation and in the bilateral middle superior temporal gyrus (BA 22/37) during and after verbal-motor production. These results indicate that the middle-superior temporal gyrus plays a crucial and multifunctional role in grapheme-phoneme matchingSilvia CasarottoAnna M. BianchiSergio CeruttiNicola VanelloEmiliano Ricciardiemiliano.ricciardi@imtlucca.itClaudio GentiliLorenzo SaniDaniela BoninoMario GuazzelliPietro Pietrinipietro.pietrini@imtlucca.itLuigi LandiniGiuseppe A. Chiarenza2016-06-30T13:04:05Z2016-09-13T10:10:45Zhttp://eprints.imtlucca.it/id/eprint/3495This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/34952016-06-30T13:04:05ZNeuronal correlates of cholinergic enhancement on cognitive function: In vivo PET and fMRI studies in humansPietro Pietrinipietro.pietrini@imtlucca.itEmiliano Ricciardiemiliano.ricciardi@imtlucca.itMario GuazzelliMaura L. Furey2016-06-09T10:53:27Z2016-09-13T10:09:53Zhttp://eprints.imtlucca.it/id/eprint/3498This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/34982016-06-09T10:53:27ZA Combined ERPs and fMRI Approach to Investigate the Neural Correlates of Reading in the Human BrainSilvia CasarottoA.M. BianchiSergio CeruttiNicola VanelloEmiliano Ricciardiemiliano.ricciardi@imtlucca.itClaudio GentiliLorenzo SaniDaniela BoninoMario GuazzelliPietro Pietrinipietro.pietrini@imtlucca.itLuigi LandiniGiuseppe A. Chiarenza2016-05-04T16:16:35Z2016-09-13T10:10:31Zhttp://eprints.imtlucca.it/id/eprint/3479This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/34792016-05-04T16:16:35ZA compatible electrocutaneous display for functional magnetic resonance imaging applicationIn this paper we propose an MR (magnetic resonance) compatible electrocutaneous stimulator able to inject an electric current, variable in amplitude and frequency, into the fingertips in order to elicit tactile skin receptors (mechanoreceptors). The desired goal is to evoke specific tactile sensations selectively stimulating skin receptors by means of an electric current in place of mechanical stimuli. The field of application ranges from functional magnetic resonance imaging (fMRI) tactile studies to augmented reality technology. The device here proposed is designed using safety criteria in order to comply with the threshold of voltage and current permitted by regulations. Moreover, MR safety and compatibility criteria were considered in order to perform experiments inside the MR scanner during an fMRI acquisition for functional brain activation analysis. Psychophysical laboratory tests are performed in order to define the different evoked tactile sensation. After verifying the device MR safety and compatibility on a phantom, a test on a human subject during fMRI acquisition is performed to visualize the brain areas activated by the simulated tactile sensation.Valentina HartwigClaudia CappelliNicola VanelloEmiliano Ricciardiemiliano.ricciardi@imtlucca.itEnzo Pasquale ScilingoGiulio GiovannettiMaria Filomena SantarelliVincenzo PositanoPietro Pietrinipietro.pietrini@imtlucca.itLuigi LandiniAntonio Bicchi2016-05-02T16:10:20Z2016-05-02T16:10:20Zhttp://eprints.imtlucca.it/id/eprint/3478This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/34782016-05-02T16:10:20ZNeurocircuitry of disgust and anxiety in obsessive-compulsive disorder : a positron emission tomography studyBackground: Disgust and fear are basic emotions that have different elicitors and expressions, and that appear to be mediated by different neurocircuits. Although obsessive-compulsive disorder (OCD) is classified as an anxiety disorder, disgust may be involved in its pathogenesis. Functional magnetic resonance imaging (fMRI) studies of disgust-inducing visual stimuli in OCD have suggested disorder specific alterations in brain activation during these tasks. Methods: Subjects with OCD and healthy controls (HC) underwent positron emission tomography (PET) brain scanning after injection of H2 15O. During PET, subjects either watched slides designed to evoke feelings of disgust (OCD = 5, HC = 11), expected the delivery of an electrical shock (OCD = 11, HC = 13), or rested (OCD = 11, HC = 14). After the anticipatory anxiety and resting tasks, anxiety ratings, heart rate, and electrodermal measures were obtained. Statistical parametric mapping (SPM) was used to analyze regional cerebral blood flow (rCBF) data. Results: Comparison of OCD subjects with controls on differences in rCBF across the disgust-inducing and resting tasks showed that OCD was characterized by greater rCBF in the left insula. In OCD the disgust-inducing task increased right lateral orbitofrontal cortex rCBF compared to resting, whereas in controls there was no difference in rCBF between these tasks. Anxiety ratings, heart rate, and electrodermal activity increased during anticipatory anxiety in both groups, and comparison of rCBF in OCD subjects with controls in anticipatory anxiety versus resting state also found no significant differences. Conclusions: OCD may be characterized by a disruption in disgust processing, such that there is a decrease in appropriate disgust (such as that evoked by observing disgust in others) and an increase in inappropriate disgust (such as that evoked by contamination stimuli). The insula may play a particularly important role in mediating such putative disruptions. The sample studied here was small, and further work is required to determine whether disgust-induced activation patterns in OCD are more apparent in specific subtypes of this disorder, whether they are specific to OCD, and whether they are normalized by treatment.Dan J. SteinMonisha AryaPietro Pietrinipietro.pietrini@imtlucca.itJudith L. RapoportSusan E. Swedo2016-03-23T17:12:49Z2016-03-23T17:12:49Zhttp://eprints.imtlucca.it/id/eprint/3337This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/33372016-03-23T17:12:49ZOn cultural constraints on piraha grammarValentina BambiniClaudio GentiliPietro Pietrinipietro.pietrini@imtlucca.it2016-03-09T09:39:11Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3210This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32102016-03-09T09:39:11ZGlobal administrative law: bibliographyBruno CarottiLorenzo Casinilorenzo.casini@imtlucca.it2016-03-09T09:05:09Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3207This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32072016-03-09T09:05:09ZL'attività normativa del governo nel periodo luglio-dicembre 2005Martina ConticelliLorenzo Casinilorenzo.casini@imtlucca.it2016-03-09T09:02:06Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3206This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32062016-03-09T09:02:06ZL'attività normativa del governo nel periodo gennaio-maggio 2006Martina ConticelliLorenzo Casinilorenzo.casini@imtlucca.it2016-03-08T13:10:36Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3200This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32002016-03-08T13:10:36ZDiritto amministrativo globaleLorenzo Casinilorenzo.casini@imtlucca.it2016-03-08T13:08:57Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3199This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31992016-03-08T13:08:57ZCatasto (diritto amministrativo)Lorenzo Casinilorenzo.casini@imtlucca.it2016-03-08T13:07:07Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3198This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31982016-03-08T13:07:07ZBeni culturaliLorenzo Casinilorenzo.casini@imtlucca.it2016-03-08T13:05:23Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3197This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31972016-03-08T13:05:23ZAgenzie amministrativeLorenzo Casinilorenzo.casini@imtlucca.it2016-02-29T16:53:08Z2016-09-13T10:11:00Zhttp://eprints.imtlucca.it/id/eprint/3169This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31692016-02-29T16:53:08ZAdvanced data analysis in brain functional studies with magnetic resonance imagingNicola VanelloMaria Filomena SantarelliVincenzo PositanoEmiliano Ricciardiemiliano.ricciardi@imtlucca.itPietro Pietrinipietro.pietrini@imtlucca.itLuigi Landini2016-02-29T11:19:00Z2016-09-13T10:09:38Zhttp://eprints.imtlucca.it/id/eprint/3164This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31642016-02-29T11:19:00ZThe role of imagery in visual and tactile spatial discrimination in congenitally blind and sighted individualsDaniela BoninoEmiliano Ricciardiemiliano.ricciardi@imtlucca.itClaudio GentiliLorenzo SaniMario GuazzelliPietro Pietrinipietro.pietrini@imtlucca.itTomaso Vecchi2016-02-26T09:51:25Z2016-02-26T09:51:25Zhttp://eprints.imtlucca.it/id/eprint/3118This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31182016-02-26T09:51:25ZCharacteristics of frontotemporal dementia patients with a Progranulin mutationObjectiveMutations in the Progranulin gene (PGRN) recently have been discovered to be associated with frontotemporal dementia (FTD) linked to 17q21 without identified MAPT mutations. The range of mutations of PGRN that can result in the FTD phenotype and the clinical presentation of patients with PGRN mutations have yet to be determined.MethodsIn this study, we examined 84 FTD patients from families not known previously to have illness linked to chromosome 17 for identified PGRN and MAPT mutations and sequenced the coding exons and the flanking intronic regions of PGRN. We compared the prevalence, clinical characteristics, magnetic resonance imaging and 18-fluoro-deoxyglucose positron emission tomography results, and neuropsychological testing of patients with the PGRN R493X mutation with those patients without identified PGRN mutations.ResultsWe discovered a new PGRN mutation (R493X) resulting in a stop codon in two patients. This was the only PGRN mutation identified in our sample. The patients with the PGRN R493X mutation had a rapid illness course and had predominant right-sided atrophy and hypometabolism on magnetic resonance imaging and 18-fluoro-deoxyglucose positron emission tomography. The affected father of one of the patients with the PGRN R493X mutation showed frontal and temporal atrophy without neurofibrillary tangles on neuropathological examination.InterpretationKnown PGRN and MAPT mutations were rare and of similar prevalence in our sample (2 compared with 1/84). The patients with the PGRN R493X mutation had a clinical presentation comparable with other behavior-predominant FTD patients. The neuropathology of an affected family member of a patient with the PGRN R493X mutation appears not to be Alzheimer's disease.Edward D. HueyJordan GrafmanEric M. WassermannPietro Pietrinipietro.pietrini@imtlucca.itMichael C. TierneyBernardino GhettiSalvatore SpinaMatt BakerMike HuttonJoshua W. ElderStephen L. BergerKyle A. HeflinJohn HardyParastoo Momeni2016-02-26T09:27:49Z2016-09-13T10:10:06Zhttp://eprints.imtlucca.it/id/eprint/3117This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31172016-02-26T09:27:49ZPhysiological reading processes by integrating ERP and fMRI data.This study investigates the neural correlates of reading by combining ERPs and fMRI. Data were recorded in separate sessions from 8 healthy adults during the same event-related design with jittered inter-stimulus interval. Two passive tasks (letter presentation - LP and symbol presentation - SP) and a reading aloud task (letter recognition - LR) were implemented. Averaged ERPs were decomposed by Independent Component Analysis after data dimensionality reduction by Principal Component Analysis. The independent components (ICs) were associated to well-known physiological potentials: N2_P2b and P2a for all tasks and a late wide negativity (LNA) for LP and LR. Low Resolution Electromagnetic Tomography (LORETA) was applied to single ICs. fMRI data were analysed by multiple linear regression. ERPs-fMRI correspondence was described by the Euclidean distance between LORETA and fMRI local maxima.Silvia CasarottoA.M. BianchiGiuseppe A. ChiarenzaNicola VanelloEmiliano Ricciardiemiliano.ricciardi@imtlucca.itPietro Pietrinipietro.pietrini@imtlucca.it2016-02-25T15:59:28Z2016-02-25T15:59:28Zhttp://eprints.imtlucca.it/id/eprint/3116This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31162016-02-25T15:59:28ZWhy cyclops could not compete with Ulysses : monocular vision and mental imagesThe present research demonstrates that the limitations of congenitally blind people in tasks requiring the processing of mental images are specifically related to the absence of binocular vision and not to the absence of vision per se. We contrasted three different groups of participants: sighted; visually impaired, with reduced binocular vision; monocular, with a normal visual acuity although in one eye only. Visually impaired participants (i.e. blurred vision) show a pattern of performance comparable to that of the sighted. In contrast, monocular participants show a similar pattern of performance to congenitally blind individuals despite being able to see perfectly well. These results shed new light on the relationship between perception and imagery and on the characteristics of sequential and simultaneous processes in the human brain.Tomaso VecchiZaira CattaneoMaura MonegatoAlfredo PeceCesare CornoldiPietro Pietrinipietro.pietrini@imtlucca.it2016-02-22T17:14:26Z2016-02-22T17:14:26Zhttp://eprints.imtlucca.it/id/eprint/3115This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/31152016-02-22T17:14:26ZRegional network of magnetic resonance imaging gray matter volume in healthy agingHealthy aging has been associated with brain volume reductions preferentially affecting the frontal cortex, but also involving other regions. We used a network model of regional covariance, the Scaled Subprofile Model, with magnetic resonance imaging voxel-based morphometry to identify the regional distribution of gray matter associated with aging in 26 healthy adults, 22–77 years old. Scaled Subprofile Model analysis identified a pattern that was highly correlated with age (R2=0.66, P≤0.0001). Older age was associated with less gray matter in the bilateral frontal, temporal,thalamic, and right cerebellar regions. Gender differences suggested more advanced brain aging in the men. In this healthy adult sample, aging was associated with a regional pattern of gray matter atrophy most prominently involving the frontal and temporal cortices. Scaled Subprofile Model network analysis may aid in the detection and tracking of brain aging and in the evaluation of putative antiaging therapies.Gene E. AlexanderKewei ChenTricia L. MerkleyEric M. ReimanRichard J. CaselliMelaney AschenbrennerLaura Santerre-LemmonDiana J. LewisPietro Pietrinipietro.pietrini@imtlucca.itStefan J. TeipelHarald HampelStanley I. RapoportJames R. Moeller2016-02-19T10:44:15Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/3076This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30762016-02-19T10:44:15ZAssetto amministrativo e profili organizzativi della disciplinaLorenzo Casinilorenzo.casini@imtlucca.it2016-01-14T08:37:03Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/2998This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29982016-01-14T08:37:03ZLa disciplina dei beni culturali dopo il d.lgs. n. 156/2006Lorenzo Casinilorenzo.casini@imtlucca.it2016-01-13T13:13:53Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/2997This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29972016-01-13T13:13:53ZLa prima sentenza della Corte costituzionale: le memorie processualiLorenzo Casinilorenzo.casini@imtlucca.it2016-01-13T13:12:23Z2016-09-14T10:21:18Zhttp://eprints.imtlucca.it/id/eprint/2996This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29962016-01-13T13:12:23ZLa valorizzazione dei beni culturali tra pubblico e privatoLorenzo Casinilorenzo.casini@imtlucca.it2015-06-26T12:53:17Z2015-06-26T12:53:17Zhttp://eprints.imtlucca.it/id/eprint/2722This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27222015-06-26T12:53:17ZAn observational model for spatial logicsSpatiality is an important aspect of distributed systems because their computations depend both on the dynamic behaviour and on the structure of their components. Spatial logics have been proposed as the formal device for expressing spatial properties of systems.
We define CCS∥, a CCS-like calculus whose semantics allows one to observe spatial aspects of systems on the top of which we define models of the spatial logic. Our alternative definition of models is proved equivalent to the standard one. Furthermore, logical equivalence is characterized in terms of the bisimilarity of CCS∥.Emilio TuostoHugo Torres Vieirahugo.torresvieira@imtlucca.it2015-02-06T11:57:01Z2015-02-06T12:01:45Zhttp://eprints.imtlucca.it/id/eprint/2561This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25612015-02-06T11:57:01ZEvaluating the scalability of a web service-based distributed e-learning and course management systemA growing concern of Web service providers is scalability. An implementation of a Web service may be able at present to support its user base, but how can a provider judge what will happen if that user base grows? We present a modelling approach based on process algebra which allows service providers to investigate how models of Web service execution scale with increasing client population sizes. The method has the benefit of allowing a simple model of the service to be scaled to realistic population sizes without the modeller needing to aggregate or re-model the system.Stephen GilmoreMirco Tribastonemirco.tribastone@imtlucca.it2015-02-06T11:43:48Z2015-02-06T11:43:48Zhttp://eprints.imtlucca.it/id/eprint/2559This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/25592015-02-06T11:43:48ZThe PEPA Plug-in projectMirco Tribastonemirco.tribastone@imtlucca.it2014-12-04T09:16:12Z2014-12-04T09:16:12Zhttp://eprints.imtlucca.it/id/eprint/2396This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23962014-12-04T09:16:12ZA scale-free neural network for modelling neurogenesis In this work we introduce a neural network model for associative memory based on a diluted Hopfield model, which grows through a neurogenesis algorithm that guarantees that the final network is a small-world and scale-free one. We also analyze the storage capacity of the network and prove that its performance is larger than that measured in a randomly dilute network with the same connectivity. Juan I. Perottijuanignacio.perotti@imtlucca.itFrancisco A. TamaritSergio A. Cannas2014-12-02T14:40:33Z2014-12-18T13:57:42Zhttp://eprints.imtlucca.it/id/eprint/2380This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23802014-12-02T14:40:33ZStructure and evolution of online social relationships: heterogeneity in unrestricted discussionsWith the advancement in the information age, people are using electronic media more frequently for communications, and social relationships are also increasingly resorting to online channels. While extensive studies on traditional social networks have been carried out, little has been done on online social networks. Here we analyze the structure and evolution of online social relationships by examining the temporal records of a bulletin board system (BBS) in a university. The BBS dataset comprises of 1908 boards, in which a total of 7446 students participate. An edge is assigned to each dialogue between two students, and it is defined as the appearance of the name of a student in the from- and to-field in each message. This yields a weighted network between the communicating students with an unambiguous group association of individuals. In contrast to a typical community network, where intracommunities (intercommunities) are strongly (weakly) tied, the BBS network contains hub members who participate in many boards simultaneously but are strongly tied, that is, they have a large degree and betweenness centrality and provide communication channels between communities. On the other hand, intracommunities are rather homogeneously and weakly connected. Such a structure, which has never been empirically characterized in the past, might provide a new perspective on the social opinion formation in this digital era.Kwang-Il GohYoung-Ho Eomyoungho.eom@imtlucca.itHawoong JeongByungnam KahngDong-Hee Kim2014-12-02T14:19:38Z2014-12-18T13:57:27Zhttp://eprints.imtlucca.it/id/eprint/2379This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23792014-12-02T14:19:38ZExploring local structural organization of metabolic networks using subgraph patterns Metabolic networks of many cellular organisms share global statistical features. Their connectivity distributions follow the long-tailed power law and show the small-world property. In addition, their modular structures are organized in a hierarchical manner. Although the global topological organization of metabolic networks is well understood, their local structural organization is still not clear. Investigating local properties of metabolic networks is necessary to understand the nature of metabolism in living organisms. To identify the local structural organization of metabolic networks, we analysed the subgraphs of metabolic networks of 43 organisms from three domains of life. We first identified the network motifs of metabolic networks and identified the statistically significant subgraph patterns. We then compared metabolic networks from different domains and found that they have similar local structures and that the local structure of each metabolic network has its own taxonomical meaning. Organisms closer in taxonomy showed similar local structures. In addition, the common substrates of 43 metabolic networks were not randomly distributed, but were more likely to be constituents of cohesive subgraph patterns. Young-Ho Eomyoungho.eom@imtlucca.itSoojin LeeHawoong Jeong2014-06-30T08:42:58Z2014-06-30T08:42:58Zhttp://eprints.imtlucca.it/id/eprint/2217This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22172014-06-30T08:42:58ZOn wars and political development. The role of international conflicts in the democratization of the WestWe investigate the role played by international conflicts in the processes of national political development with particular attention to the transition from autocracy toward democracy. We argue that, if a country is endangered by some outside threat, its elite may find optimal to concede democracy or income redistribution to the masses in order to increase their patriotism and their war effort. This in turn increases the chances of victory of the country so avoiding to the elite severe income losses. We provide historical evidence for some Western countries that confirms this theory.Davide Ticchidavide.ticchi@imtlucca.itAndrea Vindigniandrea.vindigni@imtlucca.it2014-02-27T11:00:55Z2014-02-27T11:00:55Zhttp://eprints.imtlucca.it/id/eprint/2153This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21532014-02-27T11:00:55ZCoerenzaStefano Gatteistefano.gattei@imtlucca.it2014-02-27T11:00:48Z2014-02-27T11:00:48Zhttp://eprints.imtlucca.it/id/eprint/2156This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21562014-02-27T11:00:48ZOggettivitàStefano Gatteistefano.gattei@imtlucca.it2014-02-27T10:55:05Z2014-02-27T10:55:05Zhttp://eprints.imtlucca.it/id/eprint/2158This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21582014-02-27T10:55:05ZRicorsivitàStefano Gatteistefano.gattei@imtlucca.itEvandro Agazzi2014-02-27T10:50:26Z2014-02-27T10:50:26Zhttp://eprints.imtlucca.it/id/eprint/2159This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21592014-02-27T10:50:26ZValiditàStefano Gatteistefano.gattei@imtlucca.itEnrico De Mas2014-02-27T10:46:52Z2014-02-27T10:46:52Zhttp://eprints.imtlucca.it/id/eprint/2154This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21542014-02-27T10:46:52ZDefinizioneStefano Gatteistefano.gattei@imtlucca.itJoseph Dopp2014-02-27T10:46:18Z2014-02-27T10:46:18Zhttp://eprints.imtlucca.it/id/eprint/2157This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21572014-02-27T10:46:18ZMill, John StuartStefano Gatteistefano.gattei@imtlucca.itVittorio Mathieu2014-02-27T10:40:53Z2014-02-27T10:40:53Zhttp://eprints.imtlucca.it/id/eprint/2160This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21602014-02-27T10:40:53ZVerosimileStefano Gatteistefano.gattei@imtlucca.itGiovanni Santinello2013-12-04T10:45:29Z2013-12-04T10:45:29Zhttp://eprints.imtlucca.it/id/eprint/2033This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20332013-12-04T10:45:29ZKarl Raimund PopperStefano Gatteistefano.gattei@imtlucca.it2013-11-25T12:04:38Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1947This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19472013-11-25T12:04:38ZNumerical evaluation of generalized stress-intensity factors in multi-layered composites The problem of the evaluation of the generalized stress-intensity factors for re-entrant corners in multi-layered structural components is addressed. An approximate analytical model based on the theory of multi-layered beams is presented. This approach provides a simple closed-form solution for the direct computation of the Mode I stress-intensity factor for the general problem of a re-entrant corner symmetrically meeting a bi-material interface. For the self-consistency of the theory, re-entrant corners in homogeneous materials and cracks perpendicular to bi-material interfaces can also be gained as limit cases of this formulation. According to this approach, the effects of the elastic mismatch parameters, the value of the notch angle and the thicknesses of the layers on the stress-intensity factor are carefully quantified and the results are compared with {FE} solutions. {FE} results are obtained by applying a combination of analytical and numerical techniques based on the knowledge a priori of the asymptotic stress field for re-entrant corners perpendicular to a bi-material interface and on the use of generalized isoparametric singular finite elements at the notch tip. A good agreement between approximate and analytical/numerical predictions is achieved, showing the effectiveness of this approach. Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.itNicola Pugno2013-11-25T12:01:39Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1946This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19462013-11-25T12:01:39ZInfluence of the intermediate material on the singular stress field in trimaterial junctionsBy the method of eigenfunctions, we analyze the stresses formed at the vertex of a multicomponent wedge formed by homogeneous elastic wedges under the conditions of plane stress state or plane deformation. The exponent of the singularity of stresses in the case of opening and shift of the wedges is numerically determined. The singular stresses formed near the vertex are investigated both for softer and stiffer wedges.Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-11-25T11:58:56Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1945This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19452013-11-25T11:58:56ZAn analytical approach for fracture and fatigue in functionally graded materialsThe problem of brittle crack propagation and fatigue crack growth in functionally graded materials (FGMs) is addressed. The proposed analytical approach can be used to estimate the variation of the stress-intensity factor as a function of the crack length in FGMs. Furthermore, according to the Paris’ law, the fatigue life and the crack-tip velocity of crack propagation can be predicted in the case of fatigue crack growth. A comparison with numerical results obtained according to the Finite Element method will show the effectiveness of the proposed approach. Detailed examples are provided in the case of three-point bending beam problems with either a FGM interlayer, or a FGM external coating. A comparison is presented between two types of grading in the elastic modulus: a continuous linear variation in the FGM layer and a discrete approximation with a multi-layered beam and a constant Young’s modulus in each layer.Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.itNicola Pugno2013-11-25T11:54:22Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1944This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19442013-11-25T11:54:22ZMultiscale models for contact mechanics of rough surfacesMarco Paggimarco.paggi@imtlucca.itBernardino ChiaiaMauro Borri Brunetto2013-11-25T11:39:06Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1943This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19432013-11-25T11:39:06ZA unified interface constitutive law for the study of fracture and contact problems in heterogeneous materialsA unified interface constitutive law for the description of contact and decohesion at bi-material interfaces is proposed. To this aim, a synthesis of the nonlinear models pertaining to Fracture and Contact Mechanics is presented. The issues pertinent to the implementation within the FE discretization framework are also discussed in detail. Finally, a numerical example of fatigue modeling at the mesoscopical level in a fiber-reinforced composite is provided.Marco Paggimarco.paggi@imtlucca.itAlberto CarpinteriGiorgio Zavarise2013-11-25T11:07:25Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1942This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19422013-11-25T11:07:25ZCorrelation Between Paris’ Law Parameters Based on Self-Similarity and Criticality ConditionFatigue crack growth data are usually presented in terms of the crack growth rate, da / dN, and the stress-intensity factor range, ΔK. The typical fatigue crack propagation curve is shown in Fig.1, where Region I is referred to as the near-threshold region, Region II as the power-law region and Region III as the rapid crack propagation region where K max → K IC and crack growth instability occurs. In Region II the Paris’ equation (Paris and Erdogan [1]) provides a good approximation to the majority of experimental data: (1) dadN=C(ΔK)m
where C and m are empirical constants usually referred to as Paris’ law parameters.Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2013-11-25T10:49:20Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1941This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19412013-11-25T10:49:20ZLa forma del provino ed il problema del contatto nella valutazione della resistenza del calcestruzzoFerdinando IndelicatoMarco Paggimarco.paggi@imtlucca.it2013-11-25T10:31:11Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1940This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19402013-11-25T10:31:11ZA numerical model for the analysis of decohesion at bi-material interfaces with random propertiesMarco Paggimarco.paggi@imtlucca.itAlberto CarpinteriGiorgio Zavarise2013-11-25T09:43:14Z2014-10-09T09:20:26Zhttp://eprints.imtlucca.it/id/eprint/1934This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19342013-11-25T09:43:14ZMicro-slip of rough surfaces under cyclic tangential loadingA numerical model based on the solution of the normal contact between elastic half-spaces and subsequent post-processing according to the Mindlin and Deresiewicz solution for cyclic tangential loading is presented. Thanks to a recent extension of the Cattaneo-Mindlin analogy to the solution of tangential contact between non-convex domains, the proposed approach enables the study of cyclic micro-slip and energy dissipation between elastic bodies with general shapes in contact. In order to make the procedure straightforward and as general as possible, a non-dimensional formulation, based only on the normal contact load displacement curve, is proposed. The cyclic behaviour of the tangential contact of self-affine fractal surfaces, like those generated by fracture of concrete or rock, is described with several examples.Mauro Borri BrunettoAlberto CarpinteriStefano InvernizziMarco Paggimarco.paggi@imtlucca.it2012-10-18T13:43:13Z2012-10-18T13:43:13Zhttp://eprints.imtlucca.it/id/eprint/1414This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14142012-10-18T13:43:13Z[recensione a] Aldo Mazzacane, Alessandro Somma, Michael Stolleis (a cura di), Korporativismus in den südeuropäischen Diktaturen. Il corporativismo nelle dittature sudeuropeeFiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-17T13:45:16Z2012-10-17T13:45:16Zhttp://eprints.imtlucca.it/id/eprint/1405This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14052012-10-17T13:45:16ZMemoria resistente. L'Istituto della Resistenza e il museo diffuso di TorinoFiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-12T13:01:47Z2013-06-11T12:08:23Zhttp://eprints.imtlucca.it/id/eprint/1396This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13962012-10-12T13:01:47ZL'editoria come transfer culturale: autori e libri italiani nel sistema editoriale tedesco (1880-1945)In this essay Balestracci analyses the role of the Italian literature since the late 1800s until the End of the World War Two. From the dissertation emerged the niche placement occupied from the Italian Literature in the German literary and editorial field, also in the years of the German-Italian Cultural Pact during the dictatorships.Fiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-12T12:54:48Z2013-06-11T12:05:35Zhttp://eprints.imtlucca.it/id/eprint/1395This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13952012-10-12T12:54:48ZKlaus Wagenbach und die italienische Literatur in der Bundesrepublik Deutschland, 1964-1989Klaus Wagenbach was one of the must important German editor for the diffusion of the Italian literature in West Germany since the 60s. For this reason he was nominated “cavaliere” of the Italian Republic in 1990. In this essay the Author reconstructs the editorial and cultural activity of the Berlins editor with particular regard for him relations with Italian editors and writers. Fiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-10-12T12:19:46Z2013-06-11T12:06:38Zhttp://eprints.imtlucca.it/id/eprint/1394This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13942012-10-12T12:19:46ZDie <<zweite Bauernrätebewegung>> im Deutschen Reich 1919–1920 (The second movement of farmers' councils in Germany, 1919–1920)In this article Balestracci illustrated the trajectory of the German Farmers Councils after the First World War focussing the activity of the rural councils movement driven from the Saxon council of Goslar. -
Nach der Revolution von 1918 waren überall im Reich Arbeiter und Soldateräte entstanden, die mit den alten agrarischen Interessenverbänden um die Kontrolle der Räte wetteiferten, die sich in den landwirtschaflich geprägeten Regionen gebildet hatten. Im Fruhahr 1919 trat August Davier ein Großagrarier aus Sachsen-anhalt auf den Plan, der das Projekt eines nationalen Zusammenschlusses aller agrarischen Interessen verfolgte-schließlich aber scheiterte. Worauf wollte der Großagrarier hinaus? Und wes-halb erlitt mit seiwen Ambitionem, die sich offenkundig auch gegen den neuen demokratischen Staat richteten, Schiffbruch?Fiammetta Balestraccifiammetta.balestracci@imtlucca.it2012-09-26T13:05:53Z2013-03-07T12:56:25Zhttp://eprints.imtlucca.it/id/eprint/1382This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13822012-09-26T13:05:53ZTransformational Verification of Parameterized Protocols Using Array FormulasWe propose a method for the specification and the automated verification of temporal properties of parameterized protocols. Our method is based on logic programming and program transformation. We specify the properties of parameterized protocols by using an extension of stratified logic programs. This extension allows premises of clauses to contain first order formulas over arrays of parameterized length. A property of a given protocol is proved by applying suitable unfold/fold transformations to the specification of that protocol. We demonstrate our method by proving that the parameterized Peterson’s protocol among N processes, for any N ≥ 2, ensures the mutual exclusion property. Alberto PettorossiMaurizio ProiettiValerio Sennivalerio.senni@imtlucca.it2012-09-26T12:54:23Z2013-03-07T12:56:25Zhttp://eprints.imtlucca.it/id/eprint/1381This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13812012-09-26T12:54:23ZProofs of Program Properties via Unfold/Fold Transformations of Constraint Logic ProgramsIn the literature there are various papers which illustrate the relationship between the unfold/fold program transformation techniques and the proofs of program properties both in the case of logic programs and in the case of functional programs.In this paper we illustrate that relationship in the case of constraint logic programs. We build up on results already presented, i.e.,where we have considered logic programs with locally stratified negation. The constraint logic programming paradigm significantly extends the logic-programming paradigm by allowing some of the atoms to denote constraints in a suitably chosen constraint domain. By using those constraints it is often possible to get simple and direct formulations of problem solutions.Alberto PettorossiMaurizio ProiettiValerio Sennivalerio.senni@imtlucca.it2012-09-26T12:42:46Z2013-03-07T12:56:25Zhttp://eprints.imtlucca.it/id/eprint/1380This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/13802012-09-26T12:42:46ZProving Properties of Constraint Logic Programs by Eliminating Existential VariablesWe propose a method for proving first order properties of constraint logic programs which manipulate finite lists of real numbers. Constraints are linear equations and inequations over reals. Our method consists in converting any given first order formula into a stratified constraint logic program and then applying a suitable unfold/fold transformation strategy that preserves the perfect model. Our strategy is based on the elimination of existential variables, that is, variables which occur in the body of a clause and not in its head. Since, in general, the first order properties of the class of programs we consider are undecidable, our strategy is necessarily incomplete. However, experiments show that it is powerful enough to prove several non-trivial program properties. Alberto PettorossiMaurizio ProiettiValerio Sennivalerio.senni@imtlucca.it2012-02-03T14:29:51Z2014-12-18T16:02:51Zhttp://eprints.imtlucca.it/id/eprint/1109This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/11092012-02-03T14:29:51ZPreferential attachment in the growth of social networks: the internet encyclopedia WikipediaWe present an analysis of the statistical properties and growth of the free on-line encyclopedia Wikipedia. By describing topics by vertices and hyperlinks between them as edges, we can represent this encyclopedia as a directed graph. The topological properties of this graph are in close analogy with those of the World Wide Web, despite the very different growth mechanism. In particular, we measure a scale-invariant distribution of the in and out degree and we are able to reproduce these features by means of a simple statistical model. As a major consequence, Wikipedia growth can be described by local rules such as the preferential attachment mechanism, though users, who are responsible of its evolution, can act globally on the network.Andrea CapocciVito D. P. ServedioFrancesca ColaioriLuciana BuriolDebora DonatoStefano LeonardiGuido Caldarelliguido.caldarelli@imtlucca.it2012-02-03T13:56:18Z2018-03-08T17:07:02Zhttp://eprints.imtlucca.it/id/eprint/1108This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/11082012-02-03T13:56:18ZGraph Theory and Food WebsRecently the study of complex networks has received great attention. One of the most interesting applications of these concepts is found in the study of food webs. Food webs provide fascinating examples of biological organization in ecological communities and display characteristic and unexpected statistical properties. In particular, comparison to other complex networks shows that food webs lack the scale-free properties observed in almost all other artificial and natural networks. That is, the frequency distribution for the degree (numer of different predators per species) does not display scale-free behavior. Nevertheless, we show here that self-similiar and universal behavior are still present. By considering food webs as transportation networks (for the flow of resources between species), we can recover scaling properties typical of other transportation system, such as vascular and river networks. The importance of these properties for models of structure in food webs is discussed.Cécile Caretta CartozoDiego Garlaschellidiego.garlaschelli@imtlucca.itGuido Caldarelliguido.caldarelli@imtlucca.it2012-02-01T16:12:55Z2014-12-18T15:56:24Zhttp://eprints.imtlucca.it/id/eprint/1107This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/11072012-02-01T16:12:55ZFitness model for the Italian interbank money marketWe use the theory of complex networks in order to quantitatively characterize the formation of communities in a particular financial market. The system is composed by different banks exchanging on a daily basis loans and debts of liquidity. Through topological analysis and by means of a model of network growth we can determine the formation of different group of banks characterized by different business strategy. The model based on Pareto’s law makes no use of growth or preferential attachment and it reproduces correctly all the various statistical properties of the system. We believe that this network modeling of the market could be an efficient way to evaluate the impact of different policies in the market of liquidity.Giulia De MasiGiulia IoriGuido Caldarelliguido.caldarelli@imtlucca.it2012-02-01T16:07:06Z2018-03-08T17:07:17Zhttp://eprints.imtlucca.it/id/eprint/1106This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/11062012-02-01T16:07:06ZTemperature in complex networksVarious statistical-mechanics approaches to complex networks have been proposed to describe expected topological properties in terms of ensemble averages. Here we extend this formalism by introducing the fundamental concept of graph temperature, controlling the degree of topological optimization of a network. We recover the temperature-dependent version of various important models as particular cases of our approach, and show examples where, remarkably, the onset of a percolation transition, a scale-free degree distribution, correlations and clustering can be understood as natural properties of an optimized (low-temperature) topology. We then apply our formalism to real weighted networks and we compute their temperature, finding that various techniques used to extract information from complex networks are again particular cases of our approach. Diego Garlaschellidiego.garlaschelli@imtlucca.itSebastian E. AhnertThomas M.A. FinkGuido Caldarelliguido.caldarelli@imtlucca.it2011-12-05T11:15:09Z2011-12-05T11:15:09Zhttp://eprints.imtlucca.it/id/eprint/1026This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10262011-12-05T11:15:09ZTime series sales forecasting for short shelf-life food products based on artificial neural networks and evolutionary computingDue to the strong competition that exists today, most manufacturing organizations are in a continuous effort for increasing their profits and reducing their costs. Accurate sales forecasting is certainly an inexpensive way to meet the aforementioned goals, since this leads to improved customer service, reduced lost sales and product returns and more efficient production planning. Especially for the food industry, successful sales forecasting systems can be very beneficial, due to the short shelf-life of many food products and the importance of the product quality which is closely related to human health. In this paper we present a complete framework that can be used for developing nonlinear time series sales forecasting models. The method is a combination of two artificial intelligence technologies, namely the radial basis function (RBF) neural network architecture and a specially designed genetic algorithm (GA). The methodology is applied successfully to sales data of fresh milk provided by a major manufacturing company of dairy products.Philip DoganisAlex AlexandridisPanagiotis Patrinospanagiotis.patrinos@imtlucca.itHaralambos Sarimveis2011-10-31T15:45:47Z2012-01-18T08:02:03Zhttp://eprints.imtlucca.it/id/eprint/995This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9952011-10-31T15:45:47ZA dose-finding sequential method for targeting a given mean response: Up&Down experimentsTradizionalmente, gli studi dose-risposta sono esperimenti di tipo binario volti a stimare un determinato “quantile” di interesse di una curva di risposta. In questo lavoro si considera il caso in cui la risposta osservata sia una generica variabile aleatoria reale, non necessariamente dicotomica, e lo scopo dell’esperimento consiste nello stimare la dose target associata ad una preassegnata risposta media. Ripercorrendo i risultati di Giovagnoli e Pintacuda (1998) e Baldi Antognini et al (2006), viene proposta ed analizzata un’estensione randomizzata dell’algoritmo up-and-down, fornendo inoltre una
procedura di stima della risposta media basata sul metodo di massima verosimiglianza.Alessandro Baldi AntogniniIrene Crimaldiirene.crimaldi@imtlucca.it2011-10-24T13:37:02Z2011-10-24T13:37:02Zhttp://eprints.imtlucca.it/id/eprint/964This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9642011-10-24T13:37:02ZPiazze invisibiliEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-18T13:08:59Z2011-10-18T13:08:59Zhttp://eprints.imtlucca.it/id/eprint/959This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9592011-10-18T13:08:59ZGli occhi del Sismondi: le arti figurative nelle Repubbliche italiane del MedioevoEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-18T12:49:15Z2011-10-18T13:05:01Zhttp://eprints.imtlucca.it/id/eprint/956This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9562011-10-18T12:49:15ZLa fondazione de «La Critica d’Arte» nelle carte di Carlo Ludovico Ragghianti : Parte I: 1934-35Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-13T10:57:35Z2011-10-13T10:57:35Zhttp://eprints.imtlucca.it/id/eprint/935This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9352011-10-13T10:57:35ZTra le carte di Tommaso Francesco Bernardi : percorsi della letteratura artistica lucchese del SettecentoEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-13T10:48:45Z2011-10-13T13:51:39Zhttp://eprints.imtlucca.it/id/eprint/934This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9342011-10-13T10:48:45ZUomini, cose, scrittura : dalla Vita alla Storia : profilo della letteratura artistica toscana del SettecentoEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-13T10:39:03Z2011-10-13T10:39:03Zhttp://eprints.imtlucca.it/id/eprint/933This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9332011-10-13T10:39:03ZStoria di immagini e immagini di una storiaEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-13T10:11:51Z2011-10-13T10:11:51Zhttp://eprints.imtlucca.it/id/eprint/932This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9322011-10-13T10:11:51ZUno sguardo a ritroso nell’arredo figurativo del monastero di San Michele di PesciaSin dall’alto Medioevo il San Michele ha avuto ruoli importanti per la città di Pescia: per la scolarizzazione delle giovani, come educandato monastico prima e conservatorio femminile poi (voluto da Pietro Leopoldo nel 1785), e per l’arricchimento del patrimonio artistico-monumentale cittadino. Emanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-10-12T09:49:21Z2011-10-12T09:49:21Zhttp://eprints.imtlucca.it/id/eprint/917This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9172011-10-12T09:49:21ZLe tentazioni del Barocco : i disegni capricciosi dell'Archivio Sardini di LuccaUn taccuino di Disegni capricciosi, una collezione di grafica ed opere d'arte, una serie di trattati manoscritti, un carteggio amplissimo: è questo quanto si potrebbe dire, in un breve giro di parole, di Giacomo Sardini, marchese lucchese vissuto tra il 1750 e il 1811. Il taccuino di disegni seicenteschi che qui si presenta è soltanto un esempio di questa grande collezione, formata sui dettami del gusto razionalista e neoclassico di fine Settecento, ma intelligentemente aperta a tutte le manifestazioni figurative, anche a quelle più distanti, come il barocco. Tentazioni, appunto, a cui volentieri si cede.Susanna CacciaEmanuele Pellegriniemanuele.pellegrini@imtlucca.it2011-09-15T10:56:44Z2014-12-02T09:55:09Zhttp://eprints.imtlucca.it/id/eprint/889This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8892011-09-15T10:56:44ZSchemata e danza: un problema politicoMaria Luisa Catonimarialuisa.catoni@imtlucca.it2011-09-09T13:19:00Z2013-03-05T15:48:13Zhttp://eprints.imtlucca.it/id/eprint/855This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8552011-09-09T13:19:00ZDNA-Based storage and retrieval of digital signalsSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.it2011-08-12T09:27:34Z2013-03-05T15:47:33Zhttp://eprints.imtlucca.it/id/eprint/812This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8122011-08-12T09:27:34ZDNA as a medium for storing digital signalsMotivated by the storage capacity and efficiency of the DNA molecule in this paper we propose to utilize DNA molecules to store digital signals. We show that hybridization of DNA molecules can be used as a similarity criterion for retrieving digital signals encoded and stored in a DNA database. Since retrieval is achieved through hybridization of query and data carrying DNA molecules, we present a mathematical model to estimate hybridization efficiency (also known as selectivity annealing). We show that selectivity annealing is inversely proportional to the mean squared error (MSE) of the encoded signal values. In addition, we show that the concentration of the molecules plays the same role as the decision threshold employed in digital signal matching algorithms. Finally, similarly to the digital domain, we define a DNA signal-to-noise ratio (SNR) measure to assess the performance of the DNA-based retrieval scheme. Simulations are presented to validate our arguments.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itVassily HatzimanikatiAggelos K. Katsaggelos2011-08-12T09:20:11Z2013-03-05T15:47:59Zhttp://eprints.imtlucca.it/id/eprint/811This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8112011-08-12T09:20:11ZDNA hybridization as a similarity criterion for querying digital signals stored in DNA databasesWe demonstrate via simulation that hybridization of DNA molecules can be used as a similarity criterion for retrieving digital signals encoded and stored in a synthesized DNA database. After introducing some necessary DNA terminology, we briefly explain how digital signals are transformed to DNA sequences. Since retrieval is achieved through hybridization of query and data carrying DNA molecules, we present a mathematical model to estimate hybridization efficiency (also known as selectivity annealing). We show that selectivity annealing is inversely proportional to the mean squared error (MSE) of the encoded signal values. In addition, we show that the concentration of the molecules plays the same role as the decision threshold employed in digital signal matching algorithms. Finally, similar to the digital domain, we define a DNA signal-to-noise ratio (SNR) measure to assess the performance of the DNA-based retrieval scheme. Simulations are presented to validate our arguments.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itVassily HatzimanikatiAggelos K. Katsaggelos2011-08-10T13:58:34Z2013-03-05T15:47:46Zhttp://eprints.imtlucca.it/id/eprint/792This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7922011-08-10T13:58:34ZJoint source-channel coding for wireless object-based video communications utilizing data hidingIn recent years, joint source-channel coding for multimedia communications has gained increased popularity. However, very limited work has been conducted to address the problem of joint source-channel coding for object-based video. In this paper, we propose a data hiding scheme that improves the error resilience of object-based video by adaptively embedding the shape and motion information into the texture data. Within a rate-distortion theoretical framework, the source coding, channel coding, data embedding, and decoder error concealment are jointly optimized based on knowledge of the transmission channel conditions. Our goal is to achieve the best video quality as expressed by the minimum total expected distortion. The optimization problem is solved using Lagrangian relaxation and dynamic programming. The performance of the proposed scheme is tested using simulations of a Rayleigh-fading wireless channel, and the algorithm is implemented based on the MPEG-4 verification model. Experimental results indicate that the proposed hybrid source-channel coding scheme significantly outperforms methods without data hiding or unequal error protectionHaohong WangSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itAggelos K. Katsaggelos2011-08-10T13:16:23Z2013-03-05T15:48:25Zhttp://eprints.imtlucca.it/id/eprint/786This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7862011-08-10T13:16:23ZDNA sequencingSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itAggelos K. Katsaggelos2011-08-02T09:22:36Z2011-08-04T07:30:21Zhttp://eprints.imtlucca.it/id/eprint/760This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7602011-08-02T09:22:36ZMultidisciplinary design optimization of a pressure controller for CNG injection systemsIn this work, the multidisciplinary design optimization (MDO) methodology is applied to a case arising in the automotive engineering in which the design optimization of mechanical and control features of a system are simultaneously carried out with an evolutionary algorithm based method. The system under study is the regulator of the injection pressure of an innovative Common Rail system for Compressed Natural Gas (CNG) automotive engines, whose engineering design includes several practical and numerical difficulties. To tackle such a situation, this paper proposes a constrained multi-objective optimization method, that pursues the Pareto-optimality on the basis of fitness functions that capture domain specific design aspects as well as static and dynamic objectives. The proposed scheme provides ways to incorporate the designers specific knowledge, from interactive actions to simulation based analysis or surrogate-assisted evolution. The computational experiments show the ability of the method for finding a relevant and satisfactory set of efficient solutions.Gabriella Dellinogabriella.dellino@imtlucca.itPaolo LinoCarlo MeloniAlessandro Rizzo2011-07-27T08:44:00Z2011-08-05T13:44:03Zhttp://eprints.imtlucca.it/id/eprint/537This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5372011-07-27T08:44:00ZFeedback min-max model predictive control based on a quadratic cost functionFeedback min-max model predictive control based on a quadratic cost function is addressed in this paper. The main contribution is an algorithm for solving the min-max quadratic MPC problem with an arbitrary degree of approximation. The paper also introduces the "recourse horizon", which allows one to obtain a trade-off between computational complexity and performance of the control law. The results are illustrated by means of a simulation of a quadruple-tank processDavid Muñoz de la PeñaTeodoro AlamoAlberto Bemporadalberto.bemporad@imtlucca.itEduardo F. Camacho2011-07-27T08:43:58Z2016-04-06T10:27:04Zhttp://eprints.imtlucca.it/id/eprint/488This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4882011-07-27T08:43:58ZHybrid model predictive control application towards optimal semi-active suspensionThe optimal control problem of a quarter-car semi-active suspension has been studied in the past. Considering that a quarter-car semi-active suspension can either be modelled as a linear system with state dependent constraint on control (of actuator force) input, or a bi-linear system with a control (of variable damping coefficient) saturation, the seemingly simple problem poses several interesting questions and challenges. Does the saturated version of the optimal control law derived from the corresponding un-constrained system, i.e. “clipped-optimal”, remain optimal for the constrained case as suggested in some previous publications? Or should the optimal deviate from the “clipped-optimal” as suggested in other publications? If the optimal control law of the constrained system does deviate from its unconstrained counter-part, how different are they? What is the structure of the optimal control law? Does it retain the linear state feedback form (as the unconstrained case)? In this paper, we attempt to answer some of the above questions by utilizing the recent development in model predictive control (MPC) of hybrid dynamical systems.
The constrained quarter-car semi-active suspension is modelled as a switching affine system, where the switching is determined by the activation of passivity constraints, force saturation, and maximum power dissipation limits. Theoretically, over an infinite prediction horizon the MPC controller corresponds to the exact optimal controller. The performance of different finite-horizon hybrid MPC controllers is tested in simulation using mixed-integer quadratic programming. Then, for short-horizon MPC controllers, we derive the explicit optimal control law and show that the optimal control is piecewise affine in state. In the process, we show that for horizon equal to one the explicit MPC control law corresponds to clipped LQR as expected. We also compare the derived optimal control law to various semi-active control laws in the literature including the well-known “clipped-optimal”. We evaluate their corresponding performances for both a deterministic shock input case and a stochastic random disturbances case through simulations.Nicolò GiorgettiAlberto Bemporadalberto.bemporad@imtlucca.itH. E. TsengDavor Hrovat2011-07-27T08:43:56Z2011-08-05T13:43:06Zhttp://eprints.imtlucca.it/id/eprint/491This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4912011-07-27T08:43:56ZHybrid model predictive control of direct injection stratified charge enginesThis paper illustrates the application of hybrid modeling and model predictive control techniques to the management of air-to-fuel ratio and torque in advanced technology gasoline direct-injection stratified-charge (DISC) engines. A DISC engine is an example of a constrained hybrid dynamical system, because it can operate in two distinct modes (stratified and homogeneous) and because the mode-dependent constraints on the air-to-fuel ratio and on the spark timing need to be enforced during its operation to avoid misfire, knock, and high combustion variability. In this paper, we approximate the DISC engine dynamics as a two-mode discrete-time switched affine system. Using this approximation, we tune a hybrid model predictive controller with integral action based on online mixed-integer quadratic optimization, and show the effectiveness of the approach through simulations. Then, using an offline multiparametric optimization procedure, we convert the controller into an equivalent explicit piecewise affine form that is easily implementable in an automotive microcontroller through a lookup table of linear gainsNicolò GiorgettiGiulio RipaccioliAlberto Bemporadalberto.bemporad@imtlucca.itIlya KolmanovskyDavor Hrovat2011-07-27T08:43:54Z2013-09-13T09:50:06Zhttp://eprints.imtlucca.it/id/eprint/492This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4922011-07-27T08:43:54ZAn algorithm for approximate multiparametric convex programmingFor multiparametric convex nonlinear programming problems we propose a recursive algorithm for approximating, within a given suboptimality tolerance, the value function and an optimizer as functions of the parameters. The approximate solution is expressed as a piecewise affine function over a simplicial partition of a subset of the feasible parameters, and it is organized over a tree structure for efficiency of evaluation. Adaptations of the algorithm to deal with multiparametric semidefinite programming and multiparametric geometric programming are provided and exemplified. The approach is relevant for real-time implementation of several optimization-based feedback control strategies. Alberto Bemporadalberto.bemporad@imtlucca.itCarlo Filippi2011-07-27T08:43:52Z2011-08-05T13:42:05Zhttp://eprints.imtlucca.it/id/eprint/539This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5392011-07-27T08:43:52ZModel predictive control of nonlinear mechatronic systems: an application to a magnetically actuated mass spring damperMechatronic systems in the automotive applications are characterized by significant nonlinearities and tight performance specifications further exacerbated by state and input constraints. Model Predictive Control (MPC) in conjunction with hybrid modeling can be an attractive and systematic methodology to handle these challenging control problems. In this paper, we focus on a mass spring damper system actuated by an electromagnet, which is one of the most common elements in the automotive actuators, with fuel injectors representing a concrete example. We present two designs which are based, respectively, on a linear MPC approach in cascade with a nonlinear state-dependent saturation, and on a hybrid MPC approach. The performance and the complexity of the two MPC controllers are compared.Stefano Di CairanoAlberto Bemporadalberto.bemporad@imtlucca.itIlya KolmanovskyDavor Hrovat2011-07-27T08:43:50Z2011-08-04T07:29:07Zhttp://eprints.imtlucca.it/id/eprint/498This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4982011-07-27T08:43:50ZEvent-based model predictive control and verification of integral continuous-time hybrid automataThis paper proposes an event-driven model predictive control scheme with guaranteed closed-loop convergence properties for the class of integral continuous-time hybrid automata (icHA). After converting icHA to a corresponding event-driven representation that allows one to compute the model predictive control action by mixed integer programming, sufficient conditions ensuring event-asymptotic and time-asymptotic convergence are proven. The paper also shows how the same modeling methodology can be employed to efficiently solve problems of verification of safety properties. Alberto BemporadStefano Di CairanoJorge Júlvez2011-07-27T08:43:46Z2011-08-05T13:40:55Zhttp://eprints.imtlucca.it/id/eprint/454This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4542011-07-27T08:43:46ZAn MPC/hybrid system approach to traction controlThis paper describes a hybrid model and a model predictive control (MPC) strategy for solving a traction control problem. The problem is tackled in a systematic way from modeling to control synthesis and implementation. The model is described first in the Hybrid Systems Description Language to obtain a mixed-logical dynamical (MLD) hybrid model of the open-loop system. For the resulting MLD model, we design a receding horizon finite-time optimal controller. The resulting optimal controller is converted to its equivalent piecewise affine form by employing multiparametric programming techniques, and finally experimentally tested on a car prototype. Experiments show that good and robust performance is achieved in a limited development time by avoiding the design of ad hoc supervisory and logical constructs usually required by controllers developed according to standard techniques.Francesco BorrelliAlberto Bemporadalberto.bemporad@imtlucca.itMichael FodorDavor Hrovat2011-07-27T08:43:43Z2011-08-05T13:38:38Zhttp://eprints.imtlucca.it/id/eprint/538This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5382011-07-27T08:43:43ZSquaring the circle: An algorithm for generating polyhedral invariant sets from ellipsoidal onesThis paper presents a new (geometrical) approach to the computation of polyhedral positively invariant sets for general (possibly discontinuous) nonlinear systems, possibly affected by disturbances. Given a beta-contractive ellipsoidal set E, the key idea is to construct a polyhedral set that lies between the ellipsoidal sets betaE and E. A proof that the resulting polyhedral set is positively invariant (and contractive under an additional assumption) is given, and a new algorithm is developed to construct the desired polyhedral set. An advantage of the proposed method is that the problem of computing polyhedral invariant sets is formulated as a number of quadratic programming (QP) problems. The number of QP problems is guaranteed to be finite and therefore, the algorithm has finite termination. An important application of the proposed algorithm is the computation of polyhedral terminal constraint sets for model predictive control based on quadratic costsMircea LazarAlessandro AlessioAlberto Bemporadalberto.bemporad@imtlucca.itW.P.M.H. Heemels2011-07-27T08:43:40Z2011-08-05T13:37:53Zhttp://eprints.imtlucca.it/id/eprint/543This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5432011-07-27T08:43:40ZConvex Polyhedral Invariant Sets for Closed-Loop Linear MPC Systems Given an asymptotically stabilizing linear MPC controller, this paper proposes an algorithm to construct invariant polyhedral sets for the closed-loop system. Rather than exploiting an explicit form of the MPC controller, the approach exploits a recently developed DC (Difference of Convex functions) programming technique developed by the authors to construct a polyhedral set in between two convex sets. Here, the inner convex set is any given level set V(x) les gamma of the MPC value function (implicitly defined by the quadratic programming problem associated with MPC or explicitly computed via multiparametric quadratic programming), while the outer convex set is the level set of a the value function of a modified multiparametric quadratic program (implicitly or explicitly defined). The level gamma acts as a tuning parameter for deciding the size of the polyhedral invariant containing the inner set, ranging from the origin (gamma = 0) to the maximum invariant set around the origin where the solution to the unconstrained MPC problem remains feasible, up to the whole domain of definition of the controller (possibly the whole state space Ropfn) (gamma = inf). Potential applications of the technique include reachability analysis of MPC systems and generation of constraints to supervisory decision algorithms on top of MPC loopsAlessandro AlessioAlberto Bemporadalberto.bemporad@imtlucca.itW.P.M.H. HeemelsMircea Lazar2011-07-27T08:41:35Z2011-08-05T13:35:14Zhttp://eprints.imtlucca.it/id/eprint/540This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5402011-07-27T08:41:35ZFeasible mode enumeration and cost comparison for explicit quadratic model predictive control of hybrid systemsFor hybrid systems in piecewise affine (PWA) form, this paper presents a new methodology for computing the solution, defined over a set of (possibly overlapping) polyhedra, of the finite-time constrained optimal control problem based on quadratic costs. First, feasible mode sequences are determined via backward reachability analysis, and multiparametric quadratic programming is employed to determine candidate polyhedral regions of the solution and the corresponding value functions and optimal control gains. Then, the value functions associated with overlapping regions are compared in order to discard those regions whose associated control law is never optimal. The comparison problem is, in general, nonconvex and is tackled here as a DC (Difference of Convex functions) programming problem.Alessandro AlessioAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T08:40:49Z2011-08-04T07:29:07Zhttp://eprints.imtlucca.it/id/eprint/544This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5442011-07-27T08:40:49ZModel predictive control Design: New Trends and Tools Model-based design is well recognized in industry as a systematic approach to the development, evaluation, and implementation of feedback controllers. Model predictive control (MPC) is a particular branch of model-based design: a dynamical model of the open-loop process is explicitly used to construct an optimization problem aimed at achieving the prescribed system's performance under specified restrictions on input and output variables. The solution of the optimization problem provides the feedback control action, and can be either computed by embedding a numerical solver in the real-time control code, or pre-computed off-line and evaluated through a lookup table of linear feedback gains. This paper reviews the basic ideas of MPC design, from the traditional linear MPC setup based on quadratic programming to more a advanced explicit and hybrid MPC, and highlights available software tools for the design, evaluation, code generation, and deployment of MPC controllers in real-time hardware platformsAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T08:40:46Z2011-08-05T13:23:15Zhttp://eprints.imtlucca.it/id/eprint/455This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4552011-07-27T08:40:46ZOptimal control of continuous-time switched affine systemsThis paper deals with optimal control of switched piecewise affine autonomous systems, where the objective is to minimize a performance index over an infinite time horizon. We assume that the switching sequence has a finite length, and that the decision variables are the switching instants and the sequence of operating modes. We present two different approaches for solving such an optimal control problem. The first approach iterates between a procedure that finds an optimal switching sequence of modes, and a procedure that finds the optimal switching instants. The second approach is inspired by dynamic programming and identifies the regions of the state space where an optimal mode switch should occur, therefore providing a state feedback control law.Carla SeatzuDaniele CoronaAlessandro GiuaAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-27T08:40:43Z2012-03-30T10:34:59Zhttp://eprints.imtlucca.it/id/eprint/495This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4952011-07-27T08:40:43ZLogic-based solution methods for optimal control of hybrid systemsCombinatorial optimization over continuous and integer variables is a useful tool for solving complex optimal control problems of hybrid dynamical systems formulated in discrete-time. Current approaches are based on mixed-integer linear (or quadratic) programming (MIP), which provides the solution after solving a sequence of relaxed linear (or quadratic) programs. MIP formulations require the translation of the discrete/logic part of the hybrid problem into mixed-integer inequalities. Although this operation can be done automatically, most of the original symbolic structure of the problem (e.g., transition functions of finite state machines, logic constraints, symbolic variables, etc.) is lost during the conversion, with a consequent loss of computational performance. In this paper, we attempt to overcome such a difficulty by combining numerical techniques for solving convex programming problems with symbolic techniques for solving constraint satisfaction problems (CSP). The resulting "hybrid" solver proposed here takes advantage of CSP solvers for dealing with satisfiability of logic constraints very efficiently. We propose a suitable model of the hybrid dynamics and a class of optimal control problems that embrace both symbolic and continuous variables/functions, and that are tailored to the use of the new hybrid solver. The superiority in terms of computational performance with respect to commercial MIP solvers is shown on a centralized supply chain management problem with uncertain forecast demand.Alberto Bemporadalberto.bemporad@imtlucca.itNicolò Giorgetti2011-07-27T08:40:40Z2011-08-05T13:20:31Zhttp://eprints.imtlucca.it/id/eprint/489This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4892011-07-27T08:40:40ZRobust explicit MPC based on approximate multi-parametric convex programmingMany robust model predictive control (MPC) schemes require the online solution of a computationally demanding convex program. For deterministic MPC schemes, multiparametric programming was successfully applied to move offline most of the computation. In this paper, we adopt a general approximate multiparametric algorithm recently suggested for convex problems and propose to apply it to a classical robust MPC scheme. This approach enables one to implement a robust MPC controller in real time for systems with polytopic uncertainty, ensuring robust constraint satisfaction and robust convergence to a given bounded setDavid Muñoz de la PeñaAlberto Bemporadalberto.bemporad@imtlucca.itCarlo Filippi2011-07-27T08:40:37Z2011-08-04T07:29:07Zhttp://eprints.imtlucca.it/id/eprint/494This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4942011-07-27T08:40:37ZOptimal control of investments for quality of supply improvement in electrical energy distribution networksThis paper considers the problem of deciding multi-period investments for maintenance and upgrade of electrical energy distribution networks. After describing the network as a constrained hybrid dynamical system, optimal control theory is applied to optimize profit under a complex incentive/penalty mechanism imposed by public authorities. The dynamics of the system and the cost function are translated into a mixed integer optimization model, whose solution gives the optimal investment policy over the multi-period horizon. While for a reduced-size test problem the pure mixed-integer approach provides the best optimal control policy, for real-life large-scale scenarios a heuristic solution is also introduced. Finally, the uncertainty associated with the dynamical model of the network is taken care of by adopting ideas from stochastic programming.Alberto Bemporadalberto.bemporad@imtlucca.itDavid Muñoz de la PeñaPeter Piazzesi2011-07-27T08:40:35Z2011-08-05T13:20:08Zhttp://eprints.imtlucca.it/id/eprint/490This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4902011-07-27T08:40:35ZA decomposition algorithm for feedback min-max model predictive controlAn algorithm for solving feedback min-max model predictive control for discrete-time uncertain linear systems with constraints is presented in this note. The algorithm is based on applying recursively a decomposition technique to solve the min-max problem via a sequence of low complexity linear programs. It is proved that the algorithm converges to the optimal solution in finite time. Simulation results are provided to compare the proposed algorithm with other approachesDavid Muñoz de la PeñaTeodoro AlamoAlberto Bemporadalberto.bemporad@imtlucca.itEduardo F. Camacho2011-07-27T08:40:33Z2011-08-05T13:19:18Zhttp://eprints.imtlucca.it/id/eprint/493This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4932011-07-27T08:40:33ZStabilizing model predictive control of hybrid systemsIn this note, we investigate the stability of hybrid systems in closed-loop with model predictive controllers (MPC). A priori sufficient conditions for Lyapunov asymptotic stability and exponential stability are derived in the terminal cost and constraint set fashion, while allowing for discontinuous system dynamics and discontinuous MPC value functions. For constrained piecewise affine (PWA) systems as prediction models, we present novel techniques for computing a terminal cost and a terminal constraint set that satisfy the developed stabilization conditions. For quadratic MPC costs, these conditions translate into a linear matrix inequality while, for MPC costs based on 1, infin-norms, they are obtained as norm inequalities. New ways for calculating low complexity piecewise polyhedral positively invariant sets for PWA systems are also presented. An example illustrates the developed theoryMircea LazarW.P.M.H. HeemelsSiep WeilandAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-08T11:23:17Z2011-08-04T07:29:07Zhttp://eprints.imtlucca.it/id/eprint/542This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5422011-07-08T11:23:17ZAn equivalence result between linear hybrid automata and piecewise affine systemsIn this paper we examine a relationship existing among linear hybrid automata (LHA) and piecewise affine (PWA) systems. While a LHA is an autonomous non-deterministic model, a PWA system is a deterministic model with inputs. By extending continuous-time PWA models to include the dynamics of discrete states and resets, we show in a constructive way that a LHA can be equivalently represented as a PWA system, where equivalent means that the two systems generate the same trajectories. The key idea is to model the uncertainty associated with LHA transitions as an additional vector of input disturbances in the corresponding PWA model. By linking the LHA modelling framework (popular in computer science) with the PWA modelling framework (popular in systems science), our equivalence result allows one to expand the use of several existing control theoretical tools (for stability analysis, optimal control, etc.) developed for PWA models to a much wider class of hybrid systemsStefano Di CairanoAlberto Bemporadalberto.bemporad@imtlucca.it2011-07-05T10:03:27Z2011-08-31T14:40:39Zhttp://eprints.imtlucca.it/id/eprint/699This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6992011-07-05T10:03:27ZPublic health, innovation and intellectual property rights: report of the Commission on Intellectual Property Rights, Innovation and Public HealthFabio Pammollif.pammolli@imtlucca.itRuth DreifussRaghunath Anant MashelkarCarlos CorreaMahmoud FathallaMaria C. FreireTrevor JonesTshediso MatonaPakdee PothisiriHiroko Yamane2011-07-01T14:44:36Z2011-08-31T14:40:39Zhttp://eprints.imtlucca.it/id/eprint/693This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6932011-07-01T14:44:36ZIl sistema di istruzione italiano: un confronto internazionaleFabio Pammollif.pammolli@imtlucca.itGianluca PapaNicola C. Salerno2011-07-01T08:58:09Z2011-08-31T14:40:39Zhttp://eprints.imtlucca.it/id/eprint/683This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6832011-07-01T08:58:09ZPreferential attachment and growth dynamics in complex systemsComplex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the steady influx of new classes. According to the model, the distribution changes from a pure exponential form for zero influx of new classes to a power law with an exponential cut-off form when the influx of new classes is substantial. Predictions of the model are tested through the analysis of a unique industrial database, which covers both elementary units (products) and classes (markets, firms) in a given industry (pharmaceuticals), covering the entire size distribution. The model’s predictions are in good agreement with the data. The paper sheds light on the emergence of the exponent τ≈2 observed as a universal feature of many biological, social and economic problems.Fabio Pammollif.pammolli@imtlucca.itKazuko YamasakiKaushik MatiaSergey V. BuldyrevDongfeng FuMassimo Riccabonimassimo.riccaboni@imtlucca.itH. Eugene Stanley2011-06-30T14:24:57Z2011-08-31T14:40:39Zhttp://eprints.imtlucca.it/id/eprint/660This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6602011-06-30T14:24:57ZGrowth and diversification patterns of the worldwide pharmaceutical industryFabio Pammollif.pammolli@imtlucca.itGiulio BottazziAngelo Secchi2011-06-15T08:43:00Z2011-07-11T14:35:30Zhttp://eprints.imtlucca.it/id/eprint/419This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/4192011-06-15T08:43:00ZA WSDL-Based Type System for WS-BPELWe tackle the problem of providing rigorous formal foundations to current software engineering technologies for web services. We focus on two of the most used XML-based languages for web services: WSDL and WS-BPEL. To this aim, first we select an expressive subset of WS-BPEL, with special concern for modeling the interactions among web service instances in a network context, and define its operational semantics. We call ws-calculus the resulting formalism. Then, we put forward a rigorous typing discipline that formalizes the relationship existing between ws-calculus terms and the associated WSDL documents and supports verification of their compliance. We prove that the type system and the operational semantics of ws-calculus are ‘sound’ and apply our approach to an example application involving three interacting web services. Alessandro LapadulaRosario PuglieseFrancesco Tiezzifrancesco.tiezzi@imtlucca.it2011-05-27T14:23:50Z2016-04-06T07:58:40Zhttp://eprints.imtlucca.it/id/eprint/294This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2942011-05-27T14:23:50ZSENSORIA Process Calculi for Service-Oriented ComputingThe IST-FET Integrated Project Sensoria aims at developing a novel comprehensive approach to the engineering of service-oriented software systems where foundational theories, techniques and methods are fully integrated in a pragmatic software engineering approach. Process calculi and logical methods serve as the main mathematical basis of the Sensoria approach. In this paper we give first a short overview of Sensoria and then focus on process calculi for service-oriented computing. The Service Centered Calculus SCC is a general purpose calculus which enriches traditional process calculi with an explicit notion of session; the Service Oriented Computing Kernel SOCK is inspired by the Web services protocol stack and consists of three layers for service description, service engines, and the service network; Performance Evaluation Process Algebra (PEPA) is an expressive formal language for modelling distributed systems which we use for quantitative analysis of services. The calculi and the analysis techniques are illustrated by a case study in the area of distributed e-learning systems.
Martin WirsingRocco De Nicolar.denicola@imtlucca.itStephen GilmoreMatthias HölzlRoberto LucchiMirco Tribastonemirco.tribastone@imtlucca.itGianluigi Zavattaro2011-05-25T09:18:22Z2014-10-08T08:18:50Zhttp://eprints.imtlucca.it/id/eprint/296This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2962011-05-25T09:18:22ZTowards a logic for performance and mobilityKlaim is an experimental language designed for modeling and programming distributed systems composed of mobile components where distribution awareness and dynamic system architecture configuration are key issues. StocKlaim [R. De Nicola, D. Latella, and M. Massink. Formal modeling and quantitative analysis of KLAIM-based mobile systems. In ACM Symposium on Applied Computing (SAC). ACM Press, 2005. Also available as Technical Report 2004-TR-25; CNR/ISTI, 2004] is a Markovian extension of the core subset of Klaim which includes process distribution, process mobility, asynchronous communication, and site creation. In this paper, MoSL, a temporal logic for StocKlaim is proposed which addresses and integrates the issues of distribution awareness and mobility and those concerning stochastic behaviour of systems. The satisfiability relation is formally defined over labelled Markov chains. A large fragment of the proposed logic can be translated to action-based CSL for which efficient model-checkers exist. This way, such model-checkers can be used for the verification of StocKlaim models against MoSL properties. An example application is provided in the present paper.Rocco De Nicolar.denicola@imtlucca.itPieter KatoenDiego LatellaMieke Massink2011-05-25T09:13:57Z2011-07-11T14:36:25Zhttp://eprints.imtlucca.it/id/eprint/295This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2952011-05-25T09:13:57ZSCC: A Service Centered CalculusWe seek for a small set of primitives that might serve as a basis for formalising and programming service oriented applications over global computers. As an outcome of this study we introduce here SCC, a process calculus that features explicit notions of service definition, service invocation and session handling. Our proposal has been influenced by Orc, a programming model for structured orchestration of services, but the SCC’s session handling mechanism allows for the definition of structured interaction protocols, more complex than the basic request-response provided by Orc. We present syntax and operational semantics of SCC and a number of simple but nontrivial programming examples that demonstrate flexibility of the chosen set of primitives. A few encodings are also provided to relate our proposal with existing ones.
Michele BorealeRoberto BruniLuis CairesRocco De Nicolar.denicola@imtlucca.itIvan LaneseMichele LoretiFrancisco MartinsUgo MontanariAntonio RavaraDavide SangiorgiVasco Thudichum VasconcelosGianluigi Zavattaro2011-05-24T10:30:56Z2011-07-11T14:36:25Zhttp://eprints.imtlucca.it/id/eprint/299This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2992011-05-24T10:30:56ZOn the expressive power of KLAIM-based calculiWe study the expressive power of variants of KLAIM, an experimental language with programming primitives for network-aware programming that combines the process algebra approach with the coordination-oriented one. KLAIM has proved to be suitable for programming a wide range of distributed applications with agents and code mobility, and has been implemented on the top of a runtime system written in Java. In this paper, the expressivity of its constructs is tested by distilling from it a few, more and more foundational, languages and by studying the encoding of each of them into a simpler one. The expressive power of the considered calculi is finally tested by comparing one of them with asynchronous π-calculus.Rocco De Nicolar.denicola@imtlucca.itDaniele GorlaRosario Pugliese2011-05-24T10:15:37Z2011-07-11T14:36:25Zhttp://eprints.imtlucca.it/id/eprint/298This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2982011-05-24T10:15:37ZConfining data and processes in global computing applicationsA programming notation is introduced that can be used for protecting secrecy and integrity of data in global computing applications. The approach is based on the explicit annotations of data and network nodes. Data are tagged with information about the allowed movements, network nodes are tagged with information about the nodes that can send data and spawn processes to them. The annotations are used to confine movements of data and processes. The approach is illustrated by applying it to three paradigmatic calculi for global computing, namely cKlaim (a calculus at the basis of cKlaim), (a distributed version of the [pi]-calculus) and Mobile Ambients Calculus. For all of these formalisms, it is shown that their semantics guarantees that computations proceed only while respecting confinement constraints. Namely, it is proven that, after successful static type checking, data can reside at and cross only authorised nodes. "Local" formulations of this property where only relevant subnets type check are also presented. Finally, the theory is tested by using it to model secure behaviours of a UNIX-like multiuser system.Rocco De Nicolar.denicola@imtlucca.itDaniele GorlaRosario Pugliese2011-05-24T09:53:16Z2014-10-08T08:57:48Zhttp://eprints.imtlucca.it/id/eprint/297This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2972011-05-24T09:53:16ZFrom Process Calculi to Klaim and BackWe briefly describe the motivations and the background behind the design of Klaim, a process description language that has proved to be suitable for describing a wide range of distributed applications with agents and code mobility. We argue that a drawback of Klaim is that it is neither a programming language, nor a process calculus. We then outline the two research directions we have pursued more recently. On the one hand we have evolved Klaim to a full-fledged language for distributed mobile programming. On the other hand we have distilled the language into a number of simple calculi that we have used to define new semantic theories and equivalences and to test the impact of new operators for network aware programming.Rocco De Nicolar.denicola@imtlucca.it2011-03-31T14:52:50Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/157This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1572011-03-31T14:52:50ZHeuristic Search for the Analysis of Graph Transition SystemsGraphs are suitable modeling formalisms for software and hardware systems involving aspects such as communication, object orientation, concurrency, mobility and distribution. State spaces of such systems can be represented by graph transition systems, which are basically transition systems whose states and transitions represent graphs and graph morphisms. Heuristic search is a successful Artificial Intelligence technique for solving exploration problems implicitly present in games, planning, and formal verification. Heuristic search exploits information about the problem being solved to guide the exploration process. The main benefits are significant reductions in the search effort and the size of solutions. We propose the application of heuristic search for the analysis of graph transition systems. We define algorithms and heuristics and present experimental results.Stefan EdelkampShahid JabbarAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-03-31T14:06:37Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/158This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1582011-03-31T14:06:37ZPartial-Order Reduction for General State Exploring AlgorithmsAn important component of partial-order based reduction algorithms is the condition that prevents action ignoring, commonly known as the cycle proviso. In this paper we give a new version of this proviso that is applicable to a general search algorithm skeleton also known as the General State Expanding Algorithm (GSEA). GSEA maintains a set of open (visited but not expanded) states from which states are iteratively selected for exploration and moved to a closed set of states (visited and expanded). Depending on the open set data structure used, GSEA can be instantiated as depth-first, breadth-first, or a directed search algorithm. The proviso is characterized by reference to the open and closed set of states in GSEA. As a result the proviso 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, which is an extension of the model checker SPIN for directed model checking. We evaluate the state space reduction achieved by partial-order reduction according to the proviso that we propose by comparing it on a set of benchmark problems to other reduction approaches. We also compare the use of breadth-first search 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.it2011-03-30T10:16:30Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/225This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2252011-03-30T10:16:30ZCalcio, diritti collettivi e ritorno all'antico. Storia a lieto fine?This paper investigates the Italian proposed Act n. 1496, aimed at replacing the individual negotiation of broadcast rights for soccer events with collective selling. In particular, the reasons and phases that have led to the individual negotiation of rights are scrutinised also in order to better evaluate if the collective mechanism will be able to solve the problems of solidarity and competitive balance among sport teams. Against this backdrop, the article analyses and critically assesses the anticompetitive impact of the joint selling with specific emphasis on the main antitrust proceedings recently concluded by the European Commission. / Il contributo analizza il progetto di riforma relativo alla titolarità e vendita collettiva dei diritti sulle manifestazioni calcistiche. In particolare, dopo aver ricostruito le tappe e i motivi che hanno condotto alla modalità di contrattazione individuale, viene approfondito il tema della cessione centralizzata, attribuita alla Lega Calcio, e si sottolineano le distonie di natura antitrust che tale forma di cessione è suscettibile di realizzare. Infine, viene posta enfasi alle modalità di redistribuzione dei proventi sui diritti televisivi, nella prospettiva di valutare se la riforma sia effettivamente in grado di garantire l'equilibrio competitivo delle manifestazioni sportive. Andrea Giannaccaria.giannaccari@imtlucca.it2011-03-30T10:16:23Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/226This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2262011-03-30T10:16:23ZIl caso GlaxoNota a Autorità Garante della Concorrenza e del Mercato, Caso A363, Glaxo-Principi Attivi, Provvedimento n. 15175, 8 febbraio 2006.Andrea Giannaccaria.giannaccari@imtlucca.it2011-03-30T10:15:59Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/228This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2282011-03-30T10:15:59ZIl caso Glaxo e le importazioni paralleleAndrea Giannaccaria.giannaccari@imtlucca.it2011-03-30T10:15:07Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/234This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2342011-03-30T10:15:07ZStrategie commerciali e politiche antitrust nel trasporto aereoAndrea Giannaccaria.giannaccari@imtlucca.itGiuseppe Colangelo2011-03-30T10:14:59Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/235This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2352011-03-30T10:14:59ZIl caso GE-Honeywell Nota a Tribunale di Primo Grado, Honeywell International Inc. c. Commissione delle Comunità Europee, General Electric c. Commissione delle Comunità Europee, cause T-209/01, T-210/01Andrea Giannaccaria.giannaccari@imtlucca.it2011-03-30T10:14:33Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/237This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2372011-03-30T10:14:33ZGestione collettiva e diritto antitrust: figure in cerca d’autor(i)?Andrea Giannaccaria.giannaccari@imtlucca.itRoberto Pardolesi2011-03-25T12:44:00Z2011-07-11T14:21:53Zhttp://eprints.imtlucca.it/id/eprint/219This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2192011-03-25T12:44:00ZStandardisation in the ICT sector: The (complex) interface between antitrust and intellectual propertyThis article investigates the issue of standardisation in the ICT sector, analysing the most relevant aspects concerning intellectual property rights and anticompetitive strategies that can arise in standard setting organisations. The strategic dimension of this activity is also scrutinised, highlighting the different approaches followed by the United States and by the European Union. In this respect, after underlining the benefits of processes not lead by public structures, the article describes the fundamental role of internal regulations, which are necessary both for the purpose of having a sound process, and also reducing the risk of collusion and other anticompetitive conducts among members. Mario CalderiniAndrea Giannaccaria.giannaccari@imtlucca.it2011-03-24T09:48:30Z2014-10-07T15:04:23Zhttp://eprints.imtlucca.it/id/eprint/162This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1622011-03-24T09:48:30ZGraphical Verification of a Spatial Logic for the Graphical Verification of a Spatial Logic for the pi-calculusThe paper introduces a novel approach to the verification of spatial properties for finite [pi]-calculus specifications. The mechanism is based on a recently proposed graphical encoding for mobile calculi: Each process is mapped into a (ranked) graph, such that the denotation is fully abstract with respect to the usual structural congruence (i.e., two processes are equivalent exactly when the corresponding encodings yield the same graph). Spatial properties for reasoning about the behavior and the structure of pi-calculus processes are then expressed in a logic introduced by Caires, and they are verified on the graphical encoding of a process, rather than on its textual representation. More precisely, the graphical presentation allows for providing a simple and easy to implement verification algorithm based on the graphical encoding (returning true if and only if a given process verifies a given spatial formula).
Fabio GadducciAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-03-24T09:18:25Z2014-10-07T14:57:13Zhttp://eprints.imtlucca.it/id/eprint/161This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1612011-03-24T09:18:25ZA logic for application level QoSService Oriented Computing (SOC) has been proposed as a paradigm to describe computations of applications on wide area distributed systems. Awareness of Quality of Service (QoS) is emerging as a new exigency in both design and implementation of SOC applications.
We do not refer to QoS aspects related to low-level performance and focus on those high-level non-functional features perceived by end-users as application dependent requirements, e.g., the price of a given service, or the payment mode, or else the availability of a resource (e.g., a file in a given format).
In this paper we present a logic which includes mechanisms to consider the three main dimensions of systems, namely their structure, behaviour and QoS aspects. The evaluation of a formula is a value of a constraint-semiring and not just a boolean value expressing whether or not the formula holds. This permits to express not only topological and temporal properties but also QoS properties of systems.
The logic is interpreted on SHReQ, a formal framework for specifying systems that handles abstract high-level QoS aspects combining Synchronised Hyperedge Replacement with constraint-semirings.
Dan HirschAlberto Lluch-Lafuentealberto.lluch@imtlucca.itEmilio Tuosto2011-03-18T15:00:05Z2011-07-11T14:27:36Zhttp://eprints.imtlucca.it/id/eprint/209This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2092011-03-18T15:00:05ZLe libéralisme Italien: IntroductionAntonio Masalaa.masala@imtlucca.itRaimondo Cubeddu2011-03-18T14:56:03Z2011-07-11T14:27:36Zhttp://eprints.imtlucca.it/id/eprint/208This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2082011-03-18T14:56:03ZLiberté et droit dans la pensée de Bruno LeoniAntonio Masalaa.masala@imtlucca.it2011-03-09T14:42:08Z2014-10-07T14:04:04Zhttp://eprints.imtlucca.it/id/eprint/160This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1602011-03-09T14:42:08ZA Logic for Graphs with QoSWe introduce a simple graph logic that supports specification of Quality of Service (QoS) properties of applications. The idea is that we are not only interested in representing whether two sites are connected, but we want to express the QoS level of the connection. The evaluation of a formula in the graph logic is a value of a suitable algebraic structure, a c-semiring, representing the QoS level of the formula and not just a boolean value expressing whether or not the formula holds. We present some examples and briefly discuss the expressiveness and complexity of our logic.
GianLuigi FerrariAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-03-07T14:27:54Z2011-07-11T14:34:34Zhttp://eprints.imtlucca.it/id/eprint/159This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1592011-03-07T14:27:54ZA Temporal Graph Logic for Verification of Graph Transformation SystemsWe extend our approach for verifying properties of graph transformation systems using suitable abstractions. In the original approach properties are specified as formulae of a propositional temporal logic whose atomic predicates are monadic second-order graph formulae. We generalize this aspect by considering more expressive logics, where edge quantifiers and temporal modalities can be interleaved, a feature which allows, e.g., to trace the history of objects in time. This requires the use of graph transition systems, a generalization of transition systems where states and transitions are mapped to graphs and graph morphisms, respectively, and of a corresponding notion of abstraction. After characterizing fragments of the logic which can be safely checked on the approximations, we show how the verification of the logic over graph transformation systems can be reduced to the verification of a logic over suitably defined Petri nets.
Paolo BaldanAndrea CorradiniBarbara KönigAlberto Lluch-Lafuentealberto.lluch@imtlucca.it2011-03-03T10:21:08Z2014-10-08T09:13:23Zhttp://eprints.imtlucca.it/id/eprint/126This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1262011-03-03T10:21:08ZA compositional coalgebraic model of a fragment of fusion calculusThis work is a further step in exploring the labelled transitions and bisimulations of fusion calculi. We follow the approach developed by Turi and Plotkin for lifting transition systems with a syntactic structure to bialgebras and, thus, we provide a compositional model of the fusion calculus with explicit fusions. In such a model, the bisimilarity relation induced by the unique morphism to the final coalgebra coincides with fusion hyperequivalence and it is a congruence with respect to the operations of the calculus. The key novelty in our work is to give an account of explicit fusions through labelled transitions. In this short essay, we focus on a fragment of the fusion calculus without recursion and replication.Maria Grazia Buscemim.buscemi@imtlucca.itUgo Montanari2011-02-25T08:56:32Z2011-07-11T14:00:42Zhttp://eprints.imtlucca.it/id/eprint/95This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/952011-02-25T08:56:32ZA Simple Theory of Defensive PatentingThis paper examines innovating firms’ incentives to engage in defensive patenting.
It first establishes a “truce equilibrium” in patent enforcement: when litigation is
costly, the equal strength of two symmetric parties’ patent portfolios deters any patent
disputes along the equilibrium path. This equilibrium behavior generates two benefits
of defensive patenting, namely, to prevent licensing outlays and to protect downstream
investments. In addition, firms can use patents to coordinate non-contractible
investment decisions. Depending on the joint interests, they can either reach a license
in order to guarantee high investment incentives, or agree not to grant a license so
that investments are deterred by the litigation threat. On the other hand, the strategic
patenting concern may generate a bandwagon of patent accumulation, where firms
rush to the patent office to get a patent, but the subsequent investment performance
is the same as when there is no patent at all.
The paper also argues that defensive patenting may weaken the effectiveness of
patents as an appropriation scheme. This offers an explanation that the “pro-patent” policy shift in the United States since the 1980s may actually have undermined the
incentive power of the patent system.
Jing-Yuan Chioujy.chiou@imtlucca.it2011-02-15T10:31:35Z2011-07-11T14:24:17Zhttp://eprints.imtlucca.it/id/eprint/63This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/632011-02-15T10:31:35ZRationality without Foundations Stefano Gatteistefano.gattei@imtlucca.it2011-02-15T10:26:42Z2011-07-11T14:24:17Zhttp://eprints.imtlucca.it/id/eprint/66This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/662011-02-15T10:26:42ZRespect as the Ethic of the Open SocietyKarl Popper’s description of the open society in terms of respect,
rather than mere tolerance, appears to be highly relevant today. Although
he never explicitly addressed the issues of multiculturalism and valuepluralism
in contemporary societies, Popper’s idea of respect provides an
effective way to approach them. For, on the one hand, it may help to reframe
current debates about multiculturalism in clearer terms. On the other, it
provides a critical assessment of the widespread relativism that presents
itself as a sort of panacea of all theoretical and practical problems posed by
the cohabitation of groups sharing different values and worldviews. On
closer scrutiny, political relativism – just as its epistemological counterpart
– is not only entirely inadequate but also dangerous for the very existence of
the open society. A serious look at the present situation suggests, rather, the
adoption of a principle of reciprocity that is consistent with Popper’s critical
pluralism and might prove to be effective in addressing the problems faced
by a multicultural society.Stefano Gatteistefano.gattei@imtlucca.it