IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2019-09-20T05:55:30ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2017-11-09T11:15:59Z2017-11-09T11:15:59Zhttp://eprints.imtlucca.it/id/eprint/3825This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38252017-11-09T11:15:59ZGli artisti della vita meccanica. Étienne-Jules Marey, Charles Frémont e il problema dell’automatismoIl problema dell’automatismo psicofisico, di cui andremo a tracciare alcuni contorni in merito alla sua relazione con l’istantanea fotografica, emerge da una costellazione scientifica e culturale che segna in profondità il XIX secolo, caratterizzata come fu da un acceso dibattito internazionale che chiamò in causa lo statuto e gli avanzamenti della neurofisiologia, della psicofisiologia e della psicologia sperimentale, quest’ultima all’epoca ai suoi albori. Più precisamente, il problema dell’automatismo e delle modalità della sua corretta registrazione scientifica ne rappresenta uno degli sviluppi e una delle conseguenze, la cui portata, a nostro giudizio, dev’essere ancora adeguatamente considerata sotto il profilo epistemologico e storico-scientifico.
L’ipotesi che ci guida in questo lavoro concerne l’esame della fun-zione euristica svolta dall’istantanea fotografica nella cronofotografia di Étienne-Jules Marey (1830-1904) e Charles Frémont (1855-1930) come esito di quel dibattito e, al contempo, come compimento di una svolta epistemologica, da tempo incubata, che da esso si produsse.Linda Bertellilinda.bertelli@imtlucca.it2017-09-26T07:57:29Z2017-09-26T07:57:29Zhttp://eprints.imtlucca.it/id/eprint/3799This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37992017-09-26T07:57:29ZA nonlocal adaptive discrete empirical interpolation method combined with modified hp-refinement for order reduction of molecular dynamics systemsModel order reduction is an emerging technique to tackle the computational complexities of molecular
dynamics (MD) simulations. Different strategies are required to adequately obtain the reduced solutions
of different classes of molecular dynamics systems. In this work, a proper orthogonal decomposition
(POD) is combined with the discrete empirical interpolation method (DEIM) to study atomic systems.
Due to the limitations of the DEIM in capturing the nonlocal response of the nonlinear force field of
MD systems, a nonlocal adaptive discrete empirical interpolation method (ADEIM) is proposed.
Furthermore, a modified hp-refinement algorithm is introduced to extend the application of the PODDEIM
approach to order reduction of multi-dimensional MD systems. In the DEIM, the distance between
atoms and hence the reduced internal force vector is estimated based on a local interpolation of the state
variables. The internal forces of a multi-dimensional MD system depend on the distance between the
atoms, represented in space by more than one coordinate. Therefore, the ADEIM approach seeks to obtain
a nonlocal interpolation of the state variables to accurately predict the distance between the interpolated
atoms and hence the reduced force vector. Simulation of MD systems with frequently changing neighbour
atoms leads to change in the system dynamics, which further leads to change of properties of the
snapshots. Therefore, the temporal domain is adaptively subdivided into smaller sub-domains using
the adopted hp-refinement procedure. The reduced system parameters are effectively derived over the
sub-domains. Considering the computational cost, a modified hp-refinement algorithm is developed in
this study, which is further coupled with the POD-ADEIM approach to obtain the reduced-order solution
of the MD systems. The results of the proposed approach demonstrate the efficiency and accuracy of the
reduced solutions.Saheed Olalekan Ojosaheed.ojo@imtlucca.itPattabhi R. Budarapupattabhi.budarapu@imtlucca.itMarco Paggimarco.paggi@imtlucca.it2017-09-26T07:55:57Z2017-09-26T07:55:57Zhttp://eprints.imtlucca.it/id/eprint/3800This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38002017-09-26T07:55:57ZStrength prediction of notched thin ply laminates using finite fracture mechanics and the phase field approachThin ply laminates are a new class of composite materials with great potential for application in the design of thinner and highly optimized components, resulting in potential weight savings and improved mechanical performance. These new composites can stir the development of lighter structures, overcoming current design limitations as well as notably reducing the onset and development of matrix cracking and delamination events. This paper presents the application of two recent modeling methods for the failure analysis and strength prediction of open-hole thin ply laminates under tensile loading,
which exhibit a brittle response upon failure: (i) the analytical coupled energy-stress Finite Fracture Mechanics (FFMs) technique, and (ii) the FE-based Phase Field (PF) approach for fracture that is incorporated into an enhanced assumed solid shell element. The predictions obtained using both strategies are compared with experimental data. These correlations exhibit a very satisfactory level of agreement, proving the robustness and reliability of both methods under consideration.José ReinosoA. ArterioMarco Paggimarco.paggi@imtlucca.itP.P. Camanho2017-09-04T14:16:28Z2017-09-04T14:17:39Zhttp://eprints.imtlucca.it/id/eprint/3776This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37762017-09-04T14:16:28ZPerspectives on optimal control of Varicella and Herpes Zoster by mass routine varicella vaccination: the effects of Immunity BoostingMonica Bettamonica.betta@imtlucca.itMarco LaurinoA. PuglieseGiorgio GuzzettaAlberto LandiPiero Manfredi2017-08-04T10:48:57Z2017-08-04T10:48:57Zhttp://eprints.imtlucca.it/id/eprint/3751This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37512017-08-04T10:48:57ZEssentiality, conservation, evolutionary pressure and codon bias in bacterial genesEssential genes constitute the core of genes which cannot be mutated too much nor lost along the adaptive evolutionary history of a species. Natural selection is expected to be stricter on essential genes and on conserved (highly shared) genes, than on genes that are either nonessential or peculiar to a single or a few species. In order to further assess this expectation, we study here how essentiality of a gene is connected with its degree of conservation among several unrelated bacterial species, each one characterised by its own codon usage bias. Confirming previous results on E- Coli, we show the existence of a universal exponential correlation between gene essentiality and conservation in bacteria. Moreover, we show that, within each bacterial genome, there are at least two groups of functionally distinct genes, characterised by different levels of conservation and codon bias: i) a core of essential genes, mainly related to cellular information processing; ii) a set of less conserved genes with prevalent functions related to metabolism. The genes in the first group are more retained among species, are subject to a relatively purifying conservative selection and display a more selected choice of synonymous codons.The core of essential genes is close to the minimal bacterial genome, which is in the focus of recent studies in synthetic biology, though we confirm that othologues of genes that are essential in one species are not necessarily essential in other species. We also list a set of highly shared genes, which could constitute a reservoir of targets for new anti-microbial drugs.Maddalena DiluccaGiulio Ciminigiulio.cimini@imtlucca.itAndrea Giansanti2017-08-04T10:42:24Z2017-08-04T10:42:24Zhttp://eprints.imtlucca.it/id/eprint/3750This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37502017-08-04T10:42:24ZUnfolding the innovation system for the development of countries: co-evolution of Science, Technology and ProductionWe show that the space in which scientific, technological and economic developments interplay with each other can be mathematically shaped using pioneering multilayer network and complexity techniques. We build the tri-layered network of human activities (scientific production, patenting, and industrial production) and study the interactions among them, also taking into account the possible time delays. Within this construction we can identify which capabilities and prerequisites are needed to be competitive in a given activity, and even measure how much time is needed to transform, for instance, the technological know-how into economic wealth and scientific innovation, being able to make predictions with a very long time horizon. Quite unexpectedly, we find empirical evidence that the naive knowledge flow from science, to patents, to products is not supported by data, being instead technology the best predictor for industrial and scientific production for the next decades.Emanuele PuglieseGiulio Ciminigiulio.cimini@imtlucca.itAurelio PatelliAndrea ZaccariaLuciano PietroneroAndrea Gabrielli2017-04-28T09:28:28Z2017-04-28T09:28:28Zhttp://eprints.imtlucca.it/id/eprint/3661This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36612017-04-28T09:28:28ZCausal-consistent rollback in a tuple-based languageElena GiachinoIvan LaneseClaudio Antares Mezzinaclaudio.mezzina@imtlucca.itFrancesco Tiezzi2016-11-23T09:04:15Z2017-11-29T13:22:13Zhttp://eprints.imtlucca.it/id/eprint/3600This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36002016-11-23T09:04:15ZPolymer Nanoparticles as Smart Carriers for the Enhanced Release of Therapeutic Agents to the CNSBackground: The brain is the most protected organ in the human body; its protective shield, relying on a complex system of cells, proteins and transporters, prevents potentially harmful substances from entering the brain from the bloodstream but, on the other hand, it also stops drugs administered via the systemic route. To improve the efficacy of pharmacological treatments, targeted drug delivery by means of polymer nanoparticles is a challenging but, at the same time, efficient strategy.
Methods: Thanks to a highly multidisciplinary approach, several ways to overcome the brain protection have provided effective solutions to treat a large number of diseases. Important advances in polymer science, together with the development of novel techniques for nanocarrier preparation, and the discovery of novel targeting ligands and molecules, allow a fine-tuning of size, shape, chemicophysical properties and surface chemistry of functional particulate systems; it enables the improvement of the therapeutic performances for several drugs, also toward districts that are difficult to be treated, such as the brain.
Conclusion: This review focuses on the great strides made from scientists and doctors in the development of polymer nano-sized drug delivery systems for brain diseases. Even though the optimal nanocarrier was not yet discovered, important advances were made to strive for safer, performant and successful systems, with the expectation to find soon better solutions to cure some still untreatable pathologies.Mariacristina Gagliardimariacristina.gagliardi@imtlucca.itClaudia Borriclaudia.borri@imtlucca.it2016-04-19T08:08:19Z2016-04-19T08:08:19Zhttp://eprints.imtlucca.it/id/eprint/3457This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/34572016-04-19T08:08:19ZNode-to-segment and node-to-surface interface finite elements for fracture mechanicsThe topologies of existing interface elements used to discretize cohesive cracks are such that they can be used to compute the relative displacements (displacement discontinuities) of two opposing segments (in 2D) or of two opposing facets (in 3D) belonging to the opposite crack faces and enforce the cohesive traction–separation relation. In the present work we propose a novel type of interface element for fracture mechanics sharing some analogies with the node-to-segment (in 2D) and with the node-to-surface (in
3D) contact elements. The displacement gap of a node belonging to the finite element discretization of one crack face with respect to its projected point on the opposite face is used to determine the cohesive tractions, the residual vector and its consistent linearization for an implicit solution scheme. The following advantages with respect to classical interface finite elements are demonstrated: (i) non-matching finite element discretizations of the opposite crack faces is possible; (ii) easy modeling of cohesive cracks with non-propagating crack tips; (iii) the internal rotational equilibrium of the interface element is assured. Detailed examples are provided to show the usefulness of the proposed approach in nonlinear fracture mechanics problems.Marco Paggimarco.paggi@imtlucca.itPeter Wriggers2016-04-19T08:06:52Z2016-04-19T08:06:52Zhttp://eprints.imtlucca.it/id/eprint/3456This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/34562016-04-19T08:06:52ZFrom NASGRO to fractals: Representing crack growth in metalsThis paper presents the results of an extensive experimental analysis of the fractal properties of fatigue crack rough surfaces. The analysis of the power-spectral density functions of profilometric traces shows a predominance of the box fractal dimension D = 1.2. This result leads to a particularization of the fatigue crack growth equation based on fractality proposed by the last two authors which is very close to the generalized Frost–Dugdale equation proposed by the first three authors. The two approaches, albeit based
on different initial modelling assumptions, are both very effective in predicting the crack growth rate of short cracks.R. JonesF. ChenS. PittMarco Paggimarco.paggi@imtlucca.itAlberto Carpinteri2016-03-21T10:55:23Z2016-03-21T10:55:23Zhttp://eprints.imtlucca.it/id/eprint/3259This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32592016-03-21T10:55:23ZComputational models for the in silico analysis of drug delivery from drug-eluting stentsStents are tubular meshed devices implanted to restore the perviety of an occluded vessel owing to the presence of an atherosclerotic plaque. These devices were introduced in to clinical practice from 1980. The first stent implanted in a human coronary artery was the Wallstent [1], a self-expandable metallic device. The use of a stent to expand the vessel was introduced to overcome the greater limit of angioplasty, the elastic recoil of the vessel wall, yet also caused the onset of another, different pathology: intra-stent restenosis. This pathology results from injuries on the vessel wall after balloon inflation as well as the different fluid dynamic regime established after stent implantation [2]. Intra-stent restenosis is caused by the abnormal growth of tissues within stent meshes, leading to the implant failure.
The common therapeutic approach to limit hyperplasia is the systemic administration of antimitotic and anti-inflammatory drugs. This treatment generally fails because effective dosing levels have toxic effects on patients. Since 2000, a new and emerging class of stents was introduced to redress this problem. We are referring to drug-eluting stents (DES), new devices loaded with one or more active principles for the local administration of the drug, avoiding the systemic administration of massive doses. DES are metallic devices impregnated with a drug on their surface or coated with a polymeric thin layer containing the active principle.Mariacristina Gagliardimariacristina.gagliardi@imtlucca.it2016-03-15T09:17:00Z2016-03-15T09:17:00Zhttp://eprints.imtlucca.it/id/eprint/3233This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/32332016-03-15T09:17:00ZAnalysis of the validity of the asymptotic techniques in the lower hybrid wave equation solution for reactor applicationsKnowing that the lower hybrid (LH) wave propagation in tokamak plasmas can be correctly described with a full wave approach only, based on fully numerical techniques or on semianalytical approaches, in this paper, the LH wave equation is asymptotically solved via the Wentzel-Kramers-Brillouin (WKB) method for the first two orders of the expansion parameter, obtaining governing equations for the phase at the lowest and for the amplitude at the next order. The nonlinear partial differential equation(PDE) for the phase is solved in a pseudotoroidal geometry (circular and concentric magnetic surfaces) by the method of characteristics. The associated system of ordinary differential equations for the position and the wavenumber is obtained and analytically solved by choosing an appropriate expansion parameter. The quasilinear PDE for the WKB amplitude is also solved analytically, allowing us to reconstruct the wave electric field inside the plasma. The solution is also obtained numerically and compared with the analytical solution. A discussion of the validity limits of the WKB method is also given on the basis of the obtained results.A. CardinaliLorenzo Morinilorenzo.morini@imtlucca.itC. CastaldoR. CesarioF. Zonca2015-11-16T09:10:37Z2015-11-16T09:10:37Zhttp://eprints.imtlucca.it/id/eprint/2900This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/29002015-11-16T09:10:37ZMemory Kernel in the Expertise of Chess PlayersIn this work we investigate a mechanism for the emergence of long-range time correlations observed in a chronologically ordered database of chess games. We analyze a modified Yule-Simon preferential growth process proposed by Cattuto et al., which includes memory effects by means of a probabilistic kernel. According to the Hurst exponent of different constructed time series from the record of games, artificially generated databases from the model exhibit similar long-range correlations. In addition, the inter-event time frequency distribution is well reproduced by the model for realistic parameter values. In particular, we find the inter-event time distribution properties to be correlated with the expertise of the chess players through the memory kernel extension. Our work provides new information about the strategies implemented by players with different levels of expertise, showing an interesting example of how popularities and long-range correlations build together during a collective learning process.Ana L. Schaigorodskyalschaigorodsky@gmail.comJuan I. Perottijuanignacio.perotti@imtlucca.itOrlando V. Billonialschaigorodsky@gmail.com2015-11-05T10:42:16Z2015-11-05T15:23:16Zhttp://eprints.imtlucca.it/id/eprint/2806This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/28062015-11-05T10:42:16ZNeural networks: A reviewTiziano Squartinitiziano.squartini@imtlucca.it2015-10-08T08:06:56Z2017-03-27T14:23:19Zhttp://eprints.imtlucca.it/id/eprint/2764This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27642015-10-08T08:06:56ZEvolution of the free volume between rough surfaces in contactThe free volume comprised between rough surfaces in contact governs the fluid/gas transport properties across networks of cracks and the leakage/percolation phenomena in seals. In this study, a fundamental insight into the evolution of the free volume depending on the mean plane separation, on the real contact area and on the applied pressure is gained in reference to fractal surfaces whose contact response is solved using the boundary element method. Particular attention is paid to the effect of the surface fractal dimension and of the surface resolution on the predicted results. The free volume domains corresponding to different threshold levels are found to display fractal spatial distributions whose bounds to their fractal dimensions are theoretically derived. A synthetic formula based on the probability distribution function of the free volumes is proposed to synthetically interpret the numerically observed trends.Marco Paggimarco.paggi@imtlucca.itQi-Chang He2015-10-08T08:01:12Z2015-10-08T08:02:01Zhttp://eprints.imtlucca.it/id/eprint/2762This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27622015-10-08T08:01:12ZAn anisotropic large displacement cohesive zone model for fibrillar and crazing interfacesA new cohesive zone model to describe fracture of interfaces with a microstructurs made of fibrils with statistically distributed in-plane and out-of-plane orientations is proposed. The elementary force–displacement relation of each fibril is considered to obey the peeling theory of a tape, although other refined constitutive relations could be invoked for the adhesive constitutive response without any lack of generality. The proposed consistent 2D and 3D interface finite element formulations for large displacements account for both the mechanical and the geometrical tangent stiffness matrices, required for implicit solution schemes. After a preliminary discussion on model parameters identification, it is shown that by tailoring the spatial density of fibrils at different orientations can be a way to realize innovative interfaces enhancing adhesion or decohesion, depending on the need. For instance, it can be possible to realize microstructured adhesives to facilitate debonding of the glass cover in photovoltaic modules to simplify recycling purposes. Moreover, the use of probability distribution functions describing the density of fibrils at different orientations is a very effective approach for modeling the anisotropy in the mechanical bonding between paper tissues and for simulating the complex process of crazing in amorphous polymers.Marco Paggimarco.paggi@imtlucca.itJosé Reinoso2015-10-08T07:55:10Z2015-10-08T08:03:01Zhttp://eprints.imtlucca.it/id/eprint/2761This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27612015-10-08T07:55:10ZNumerical modelling and validation of thermally-induced spallingIn order to reduce the silicon consumption in the production of crystalline silicon solar cells, the improvement of sawing techniques or the use of a kerf-less process are possible solutions. This study focuses on a particular kerf-less technique based on thermally-induced spalling of thin silicon layers joined to aluminum. Via a controlled temperature variation we demonstrate that it is possible to drive an initially sharp crack, introduced by laser, into the silicon substrate and obtain the detachment of ultra-thin silicon layers. A numerical approach based on the finite element method (FEM) and Linear Elastic Fracture Mechanics (LEFM) is herein proposed to compute the Stress Intensity Factors (SIFs) that characterize the stress field at the crack tip and predict crack propagation of an initial notch, depending on the geometry of the specimen and on the boundary conditions. We propose a parametric study to evaluate the dependence of the crack path on the following parameters: (i) the distance between the notch and the aluminum-silicon interface, (ii) the thickness of the stressor (aluminum) layer, and (iii) the applied load. The results for the cooling process here analyzed show that ΔT >43 K and a ratio λ=0.65 between the thickness of the stressor layer and the distance of the initial notch from the interface are suitable values to achieve a steady-state propagation in case of a ratio λ0=0.115 between the in plane thickness of the silicon substrate and the aluminum thickness, a value typically used in applications.Irene BerardoneSarah Kajari-SchröderR NiepeltJ HensenV SteckenreiterMarco Paggimarco.paggi@imtlucca.it2015-10-08T07:35:04Z2015-10-08T07:46:39Zhttp://eprints.imtlucca.it/id/eprint/2758This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27582015-10-08T07:35:04ZThe interaction ‘Supply’, ‘Demand’, and ‘Technological Capabilities’ in terms of Medical Subject Headings: A triple helix model of medical innovationsWe develop a model of innovation that enables us to trace the interplay among three key dimensions of the innovation process: (i) demand of and (ii) supply for innovation, and (iii) technological capabilities available to generate innovation in the forms of products, processes, and services. Building on Triple Helix research, we use entropy statistics to elaborate an indicator of mutual information among these dimensions that can provide indication of reduction of uncertainty. To do so, we focus on the medical context, where uncertainty poses significant challenges to the governance of innovation. The Medical Subject Headings (MeSH) of MEDLINE/PubMed provide us with publication records classified within the categories “Diseases” (C), “Drugs and Chemicals” (D), “Analytic, Diagnostic, and Therapeutic Techniques and Equipment” (E) as knowledge representations of demand, supply, and technological capabilities, respectively. Three case-studies of medical research areas are used as representative ‘entry perspectives’ of the medical innovation process. These are: (i) Human Papilloma Virus, (ii) RNA interference, and (iii) Magnetic Resonance Imaging. We find statistically significant periods of synergy among demand, supply, and technological capabilities (C-D-E) that points to three-dimensional interactions as a fundamental perspective for the understanding and governance of the uncertainty associated with medical innovation. Among the pairwise configurations in these contexts, the demand-technological capabilities (C-E) provided the strongest link, followed by the supply-demand (D-C) and the supply-technological capabilities (D-E) channels.Alexander M. Petersenalexander.petersen@imtlucca.itD. RotoloL. Leydesdorff2015-10-08T07:34:21Z2015-10-08T07:34:21Zhttp://eprints.imtlucca.it/id/eprint/2757This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27572015-10-08T07:34:21ZQuantifying the impact of weak, strong, and super ties in scientific careersScientists are frequently faced with the important decision to start or terminate a creative partnership. This process can be influenced by strategic motivations, as early career researchers are pursuers, whereas senior researchers are typically attractors, of new collaborative opportunities. Focusing on the longitudinal aspects of scientific collaboration, we analyzed 473 collaboration profiles using an egocentric perspective that accounts for researcher-specific characteristics and provides insight into a range of topics, from career achievement and sustainability to team dynamics and efficiency. From more than 166,000 collaboration records, we quantify the frequency distributions of collaboration duration and tie strength, showing that collaboration networks are dominated by weak ties characterized by high turnover rates. We use analytic extreme value thresholds to identify a new class of indispensable super ties, the strongest of which commonly exhibit >50% publication overlap with the central scientist. The prevalence of super ties suggests that they arise from career strategies based upon cost, risk, and reward sharing and complementary skill matching. We then use a combination of descriptive and panel regression methods to com- pare the subset of publications coauthored with a super tie to the subset without one, controlling for pertinent features such as career age, prestige, team size, and prior group experience. We find that super ties contribute to above-average productivity and a 17% citation increase per publication, thus identifying these partner- ships—the analog of life partners—as a major factor in science career development.Alexander M. Petersenalexander.petersen@imtlucca.it2015-06-23T12:59:23Z2017-03-27T14:19:42Zhttp://eprints.imtlucca.it/id/eprint/2709This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27092015-06-23T12:59:23ZA power and energy procedure in operating
photovoltaic systems to quantify the losses
according to the causesRecently, after high feed-in tariffs in Italy, retroactive cuts in the energy payments have generated economic concern about several grid-connected photovoltaic (PV) systems with poor performance. In this paper the proposed procedure suggests some rules for determining the sources of losses and thus minimizing poor performance in the energy production. The on-site
field inspection, the identification of the irradiance sensors, as close as possible the PV system, and the assessment of energy production are three preliminary steps which do not require experimental tests. The fourth step is to test the arrays of PV modules on-site. The fifth step is to test only the PV strings or single modules belonging to arrays with poor performance (e.g., I-V mismatch). The sixth step is to use the thermo-graphic camera and the electroluminescence at the PV-module level. The seventh step is to monitor the DC racks of each inverter or the individual inverter, if equipped with only one Maximum Power Point Tracker (MPPT). Experimental results on real PV systems show the effectiveness of this procedure.F. Spertinofilippo.spertino@polito.itA. CiociaP. Di LeoR. TommasiniIrene Berardoneirene.berardone@polito.itMauro Corradomauro.corrado@polito.itAndrea Infusoandrea.infuso@polito.itMarco Paggimarco.paggi@imtlucca.it2015-05-29T08:09:32Z2015-05-29T08:09:32Zhttp://eprints.imtlucca.it/id/eprint/2700This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/27002015-05-29T08:09:32ZDictionary learning for unsupervised identification of ischemic territories in CP-BOLD Cardiac MRI at restMarco Bevilacquamarco.bevilacqua@imtlucca.itCristian RusuRohan DharmakumarSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.it2015-05-29T08:04:45Z2015-05-29T08:04:45Zhttp://eprints.imtlucca.it/id/eprint/2699This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/26992015-05-29T08:04:45ZWhole-heart, free-breathing, three-dimensional myocardial BOLD MRI at 3T with simultaneous 13N-ammonia PET in caninesHsin-Jung YangDamini DeyJane SykesJohn ButlerAvinash KaliIvan CokicBehzad SharifDebiao LiSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itPiotr SlomkaFrank S. PratoRohan Dharmakumar2015-05-19T09:35:54Z2015-10-28T14:47:41Zhttp://eprints.imtlucca.it/id/eprint/2681This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/26812015-05-19T09:35:54ZModel Predictive Control for Linear Impulsive Systems Linear impulsive control systems have been extensively studied with respect to their equilibrium points which, in most cases, are no other than the origin. However, the trajectory of an impulsive system cannot be stabilized to arbitrary desired points hindering their utilization in a great many applications. In this paper, we study the equilibrium of linear impulsive systems with respect to target-sets. We properly extend the notion of invariance and design stabilizing model predictive controllers (MPC). Finally, we apply the proposed methodology to control the intravenous bolus administration of Lithium.Pantelis Sopasakispantelis.sopasakis@imtlucca.itPanagiotis Patrinospanagiotis.patrinos@imtlucca.itHaralambos SarimveisAlberto Bemporadalberto.bemporad@imtlucca.it2015-05-12T10:26:46Z2017-01-26T14:22:08Zhttp://eprints.imtlucca.it/id/eprint/2674This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/26742015-05-12T10:26:46ZA Hybrid Model Predictive Control Approach to Attitude Control with Minimum-Impulse-Bit ThrustersThis paper studies an important aspect of attitude control for a launcher's upper stage: the minimum impulse bit (MIB), that is, the minimum torque that can be exerted by the thrusters. We model this effect using principles of hybrid systems theory and we design a hybrid model predictive control scheme for the attitude control of a launcher during its long coasting period, aiming at minimizing the number of thrusters' actuations. We apply the proposed methodology to a nonlinear model of a typical upper stage with multi-payload capability. Pantelis Sopasakispantelis.sopasakis@imtlucca.itDaniele Bernardinidaniele.bernardini@imtlucca.itHans StrauchSamir BennaniAlberto Bemporadalberto.bemporad@imtlucca.it2014-12-03T11:47:33Z2014-12-18T13:54:51Zhttp://eprints.imtlucca.it/id/eprint/2390This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23902014-12-03T11:47:33ZGeneralized friendship paradox in complex networks: the case of scientific collaborationThe friendship paradox states that your friends have on average more friends than you have. Does the paradox “hold” for other individual characteristics like income or happiness? To address this question, we generalize the friendship paradox for arbitrary node characteristics in complex networks. By analyzing two coauthorship networks of Physical Review journals and Google Scholar profiles, we find that the generalized friendship paradox (GFP) holds at the individual and network levels for various characteristics, including the number of coauthors, the number of citations, and the number of publications. The origin of the GFP is shown to be rooted in positive correlations between degree and characteristics. As a fruitful application of the GFP, we suggest effective and efficient sampling methods for identifying high characteristic nodes in large-scale networks. Our study on the GFP can shed lights on understanding the interplay between network structure and node characteristics in complex networks.Young-Ho Eomyoungho.eom@imtlucca.itHang-Hyun Jo2014-11-24T08:25:15Z2014-11-24T08:25:15Zhttp://eprints.imtlucca.it/id/eprint/2376This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23762014-11-24T08:25:15ZThe Z-index: A geometric representation of productivity and impact which accounts for information in the entire rank-citation profileWe present a simple generalization of Hirsch's h-index, Z \equiv \sqrt{h^{2}+C}/\sqrt 5, where C is the total number of citations. Z is aimed at correcting the potentially excessive penalty made by h on a scientist's highly cited papers, because for the majority of scientists analyzed, we find the excess citation fraction (C-h^{2})/C to be distributed closely around the value 0.75, meaning that 75 percent of the author's impact is neglected. Additionally, Z is less sensitive to local changes in a scientist's citation profile, namely perturbations which increase h while only marginally affecting C. Using real career data for 476 physicists careers and 488 biologist careers, we analyze both the distribution of Z and the rank stability of Z with respect to the Hirsch index h and the Egghe index g. We analyze careers distributed across a wide range of total impact, including top-cited physicists and biologists for benchmark comparison. In practice, the Z-index requires the same information needed to calculate h and could be effortlessly incorporated within career profile
databases, such as Google Scholar and ResearcherID. Because Z incorporates information from the entire publication profile while being more robust than h and g to local perturbations, we argue that Z is better suited for ranking comparisons in academic decision-making scenarios comprising a large number of scientists. Alexander M. Petersenalexander.petersen@imtlucca.itSauro Succi2014-11-24T08:24:41Z2014-11-24T08:24:41Zhttp://eprints.imtlucca.it/id/eprint/2374This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23742014-11-24T08:24:41ZExploiting citation networks for large-scale author name disambiguationWe present a novel algorithm and validation method for disambiguating author names in very large bibliographic data sets and apply it to the full Web of Science (WoS) citation index. Our algorithm relies only upon the author and citation graphs available for the whole period covered by the WoS. A pair-wise publication similarity metric, which is based on common co-authors, self-citations, shared references and citations, is established to perform a two-step agglomerative clustering that first connects individual papers and then merges similar clusters. This parameterized model is optimized using an h-index based recall measure, favoring the correct assignment of well-cited publications, and a name-initials-based precision using WoS metadata and cross-referenced Google Scholar profiles. Despite the use of limited metadata, we reach a recall of 87% and a precision of 88% with a preference for researchers with high h-index values. 47 million articles of WoS can be disambiguated on a single machine in less than a day. We develop an h-index distribution model, confirming that the prediction is in excellent agreement with the empirical data, and yielding insight into the utility of the h-index in real academic ranking scenarios. Christian SchulzAmin MazloumianAlexander M. Petersenalexander.petersen@imtlucca.itOrion Pennerorion.penner@imtlucca.itDirk Helbingdhelbing@ethz.ch2014-11-24T08:24:05Z2014-11-24T08:24:05Zhttp://eprints.imtlucca.it/id/eprint/2375This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23752014-11-24T08:24:05ZInequality and cumulative advantage in science careers: a case study of high-impact journalsAnalyzing a large data set of publications drawn from the most competitive journals in the natural and social sciences we show that research careers exhibit the broad distributions of individual achievement characteristic of systems in which cumulative advantage plays a key role. While most researchers are personally aware of the competition implicit in the publication process, little is known about the levels of inequality at the level of individual researchers. Here we analyzed both productivity and impact measures for a large set of researchers publishing in high-impact journals, accounting for censoring biases in the publication data by using distinct researcher cohorts defined over non-overlapping time periods. For each researcher cohort we calculated Gini inequality coefficients, with average Gini values around 0.48 for total publications and 0.73 for total citations. For perspective, these observed values are well in excess of the inequality levels observed for personal income in developing countries. Investigating possible sources of this inequality, we identify two potential mechanisms that act at the level of the individual that may play defining roles in the emergence of the broad productivity and impact distributions found in science. First, we show that the average time interval between a researcher’s successive publications in top journals decreases with each subsequent publication. Second, after controlling for the time dependent features of citation distributions, we compare the citation impact of subsequent publications within a researcher’s publication record. We find that as researchers continue to publish in top journals, there is more likely to be a decreasing trend in the relative citation impact with each subsequent publication. This pattern highlights the difficulty of repeatedly producing research findings in the highest citation-impact echelon, as well as the role played by finite career and knowledge life-cycles, and the intriguing possibility that confirmation bias plays a role in the evaluation of scientific careers.Alexander M. Petersenalexander.petersen@imtlucca.itOrion Pennerorion.penner@imtlucca.it2014-11-17T11:38:14Z2014-11-17T11:38:14Zhttp://eprints.imtlucca.it/id/eprint/2370This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23702014-11-17T11:38:14ZReputation and impact in academic careersReputation is an important social construct in science, which enables informed quality assessments of both publications and careers of scientists in the absence of complete systemic information. However, the relation between reputation and career growth of an individual remains poorly understood, despite recent proliferation of quantitative research evaluation methods. Here, we develop an original framework for measuring how a publication’s citation rate Δc depends on the reputation of its central author i, in addition to its net citation count c. To estimate the strength of the reputation effect, we perform a longitudinal analysis on the careers of 450 highly cited scientists, using the total citations Ci of each scientist as his/her reputation measure. We find a citation crossover c×, which distinguishes the strength of the reputation effect. For publications with c < c×, the author’s reputation is found to dominate the annual citation rate. Hence, a new publication may gain a significant early advantage corresponding to roughly a 66% increase in the citation rate for each tenfold increase in Ci. However, the reputation effect becomes negligible for highly cited publications meaning that, for c ≥ c×, the citation rate measures scientific impact more transparently. In addition, we have developed a stochastic reputation model, which is found to reproduce numerous statistical observations for real careers, thus providing insight into the microscopic mechanisms underlying cumulative advantage in science. Alexander M. Petersenalexander.petersen@imtlucca.itSanto FortunatoRaj K. PanKimmo KaskiOrion Pennerorion.penner@imtlucca.itArmando Rungiarmando.rungi@imtlucca.itMassimo Riccabonimassimo.riccaboni@imtlucca.itH. Eugene StanleyFabio Pammollif.pammolli@imtlucca.it2014-10-09T09:29:56Z2014-10-09T09:29:56Zhttp://eprints.imtlucca.it/id/eprint/2305This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23052014-10-09T09:29:56ZLagrange and his Mécanique Analytique: from Kantian noumenon to present applicationsThe deduction of most of the fundamental laws governing solid and fluid mechanics is due to Lagrange. As already mentioned by several researchers and science historians, analytical mechanics has achieved the highest degree of perfection thanks to Lagrange’s work. The aim of this editorial is to provide a critical review of the second edition of Mécanique Analytique, which has been considered Lagrange’s opera summa, and to illustrate the influence of such a treatise on modern mechanics. Particular emphasis will be given to the current perspectives of Lagrange’s work in relation to the many mathematical and engineering developments that have been inspired by it.Alberto CarpinteriMarco Paggimarco.paggi@imtlucca.it2014-10-09T08:59:38Z2014-10-09T08:59:38Zhttp://eprints.imtlucca.it/id/eprint/2301This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23012014-10-09T08:59:38ZOn the dependency of the parameters of fatigue crack growth from the fractal dimension of rough crack profilesA theoretical study based on dimensional analysis and fractal geometry of crack profiles is proposed to establish the relation between their fractal dimension D (1<D<2) and the parameters defining the fatigue crack propagation rate. The exponent m of the Paris' law is found to be an increasing function of the fractal dimension of the crack profile, m=2D/(2-D). This trend is confirmed by a quantitative analysis of fractographic images of Titanium alloys with different grain sizes (different roughness of crack profiles), by a new experimental test and by an indirect estimation of D from crack growth equations accounting from crack-size effects in Steel and Aluminum. The present study can be considered as the first quantitative analysis of fractographic images aiming at relating the morphological features of cracks to their kinetics in fatigue.Marco Paggimarco.paggi@imtlucca.itOleg Plekhovpoa@icmm.ru2014-10-07T10:39:38Z2014-10-07T10:39:38Zhttp://eprints.imtlucca.it/id/eprint/2288This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22882014-10-07T10:39:38ZTogether we standUniversity culture stands at a critical crossroads: the era of team science is upon us functionally, but not
yet structurally. Solutions to the problems this mismatch creates involve rethinking education — and
giving credit where credit is due.Ioannis PavlidisAlexander M. Petersenalexander.petersen@imtlucca.itIoanna Semendeferi2014-10-02T09:29:52Z2014-10-02T09:29:52Zhttp://eprints.imtlucca.it/id/eprint/2248This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22482014-10-02T09:29:52ZElectrical recovery and fatigue degradation phenomena in cracked silicon cellsAn experimental study based on the electroluminescence technique is herein proposed to demonstrate the existence of coupling between mechanical deformations and the intensity of the electric field due to cracks in monocrystalline Silicon cells embedded in photovoltaic modules. In spite of the very brittle nature of Silicon, due to the action of the encapsulating polymer and residual compressive stresses resulting from the lamination stage, cracks experience crack closure and contact during mechanical unloading, partially recovering their original electric response. Crack propagation in case of cyclic loading, as, e.g., in case of vibrations due to transportation and use, have also been reported for the very first time. The research results pinpoint the need of improving electric predictions based on the estimation of inactive cell areas, since worst case scenarios not accounting for electro-mechanical coupling are too conservative.Marco Paggimarco.paggi@imtlucca.itIrene Berardoneirene.berardone@polito.itAndrea Infusoandrea.infuso@polito.itMauro Corradomauro.corrado@polito.it2014-10-02T09:04:58Z2014-10-02T09:04:58Zhttp://eprints.imtlucca.it/id/eprint/2285This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22852014-10-02T09:04:58ZPartial-slip frictional response of rough surfacesIf two elastic bodies with rough surfaces are first pressed against each other and then loaded tangentially, sliding will occur at the boundary of the contact area while the inner parts may still stick. With increasing tangential force, the sliding parts will expand while the sticking parts shrink and finally vanish. In this paper, we study the fractions of the contact area, tangential force and tangential stiffness, associated with the sticking portion of the contact area, as a function of the total applied tangential force up to the onset of full sliding. For the numerical analysis randomly rough, fractal surfaces are used, with the Hurst exponent H ranging from 0.1 to 0.9. Numerical simulations by boundary element method are compared with an analytical analysis in the framework of the Greenwood and Williamson (GW) model. In both cases, a universal linear dependency between the real contact area fraction in stick condition and the applied tangential force is found, regardless of the Hurst exponent of the rough surfaces. Regarding the dependence of the differential tangential stiffness on the tangential force, a linear relation is found in the GW case. For randomly rough surfaces, a nonlinear relation depending on H is derived.Marco Paggimarco.paggi@imtlucca.itRoman PohrtValentin A. Popov2014-10-02T08:53:58Z2014-10-02T08:53:58Zhttp://eprints.imtlucca.it/id/eprint/2287This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22872014-10-02T08:53:58ZA generalized electric model for mono and polycrystalline silicon in the presence of cracks and random defectsDamage, micro-cracks, grain boundaries and other defects in solar cells are impacting on the electric power-loss of photovoltaic modules, their actual solar conversion efficiency and also their lifetime. In the present contribution, a one-dimensional model for simulating the electric current distribution in solar cells accounting for a distributed series resistance is generalized to the presence of partially conductive cracks. The proposed model is used to perform a quantitative analysis of electroluminescence (EL) images of cracked monocrystalline silicon solar cells. A further generalization in a stochastic direction is also proposed in order to take into account randomly distributed defects typical of polycrystalline silicon.Irene Berardoneirene.berardone@polito.itMauro Corradomauro.corrado@polito.itMarco Paggimarco.paggi@imtlucca.it2014-10-02T08:50:00Z2014-10-02T08:50:00Zhttp://eprints.imtlucca.it/id/eprint/2286This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22862014-10-02T08:50:00ZDynamic nonlinear crack growth at interfaces in multi-layered materialsFinite thickness interfaces, such as structural adhesives, are often simplified from the modelling point of view by introducing ideal cohesive zone models that do not take into account the finite thickness properties in the evaluation of the interface stiffness and inertia. In the present work, the nonlinear dynamic response of those layered systems is numerically investigated according to the finite element method. The weak form of the dynamic equilibrium is written by including not only the contribution of cohesive interfaces related to the virtual work exerted by the cohesive tractions for the corresponding relative displacements, but also considering the work done by the dynamic forces of the finite thickness interfaces resulting from their inertia properties. A fully implicit solution scheme both in space and in time is exploited and the numerical results for the double cantilever beam test show that the role of finite thickness properties is remarkable as far as the crack growth kinetics and the dynamic strength increase factor are concerned.Mauro Corradomauro.corrado@polito.itMarco Paggimarco.paggi@imtlucca.it2014-09-10T07:48:39Z2014-09-10T07:48:39Zhttp://eprints.imtlucca.it/id/eprint/2281This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22812014-09-10T07:48:39ZA Scientist's guide to cloud computingNew tools (some commercial and even public), have made it so that dealing with the cloud and running large-scale processing can be rather easy and efficient. Cloud's appeal for science is clear: simplicity, elasticity (that is, the availability of large resources on the spot by launching as many instances as needed), true reproducibility (the virtual machine and the code running on that machine can be made public together with the data, when necessary), the ability to cover a large span of open questions previously unattainable due to a possible lack of computing power, and most importantly, democratization of science (since anyone has access to large computing power). PiCloud (www.multyvac.com) is one of the first commercial entities with a special focus on making scientific computing in the cloud simple for the users. PiCloud provisions AWS instances transparently to the user, acting as a middleware between AWS and the user. Their provisioning technology allows PiCloud to compete for the lower cost spot instances on Amazon.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.it2014-06-16T12:27:41Z2014-09-02T09:53:17Zhttp://eprints.imtlucca.it/id/eprint/2205This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22052014-06-16T12:27:41ZPower grids, smart grids and complex networksWe present some possible Complex Networks approaches to study and understand Power Grids and to improve them into Smart Grids . We first sketch the general properties of the Electric System with an attention to the effects of Distributed Generation. We then analyse the effects of renewable power sources on Voltage Controllability. Afterwords, we study the impact of electric line overloads on the nature of Blackouts. Finally, we discuss the possibility of implementing Self Healing capabilities into Power Grids through the use of Routing Protocols.Antonio ScalaGuido Caldarelliguido.caldarelli@imtlucca.itAlessandro Chessaalessandro.chessa@imtlucca.itAlfonso DamianoMario MuredduSakshi PahwaCaterina ScoglioWalter Quattrociocchi2013-12-23T08:31:58Z2013-12-23T08:31:58Zhttp://eprints.imtlucca.it/id/eprint/2084This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/20842013-12-23T08:31:58ZA generalized telegraph process with velocity driven by random trialsWe consider a random trial-based telegraph process, which describes a motion on the real line with two constant velocities along opposite directions. At each epoch of the underlying counting process the new velocity is determined by the outcome of a random trial. Two schemes are taken into account: Bernoulli trials and classical Pòlya urn trials. We investigate the probability law of the process and the mean of the velocity of the moving particle. We finally discuss two cases of interest: (i) the case of Bernoulli trials and intertimes having exponential distributions with linear rates (in which, interestingly, the process exhibits a logistic stationary density with non-zero mean), and (ii) the case of Pòlya trials and intertimes having first Gamma and then exponential distributions with constant rates. Irene Crimaldiirene.crimaldi@imtlucca.itAntonio Di CrescenzoAntonella IulianoBarbara Martinucci2013-05-17T08:25:25Z2013-11-21T11:43:09Zhttp://eprints.imtlucca.it/id/eprint/1585This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/15852013-05-17T08:25:25ZLanguages cool as they expand: Allometric scaling and the decreasing need for new words We analyze the occurrence frequencies of over 15 million words recorded in millions of books published during the past two centuries in seven different languages. For all languages and chronological subsets of the data we confirm that two scaling regimes characterize the word frequency distributions, with only the more common words obeying the classic Zipf law. Using corpora of unprecedented size, we test the allometric scaling relation between the corpus size and the vocabulary size of growing languages to demonstrate a decreasing marginal need for new words, a feature that is likely related to the underlying correlations between words. We calculate the annual growth fluctuations of word use which has a decreasing trend as the corpus size increases, indicating a slowdown in linguistic evolution following language expansion. This ‘‘cooling pattern’’ forms the basis of a third statistical regularity, which unlike the Zipf and the Heaps law, is dynamical in nature.Alexander M. Petersenalexander.petersen@imtlucca.itJoel TenenbaumShlomo HavlinH. Eugene StanleyMatjaz Perc2011-12-13T14:45:12Z2011-12-13T14:45:12Zhttp://eprints.imtlucca.it/id/eprint/1040This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/10402011-12-13T14:45:12ZA few special cases: scientific creativity and network dynamics in the field of rare diseasesWe develop a model of scientific creativity and test it in the field of rare diseases. Our model is based on the results of an in-depth case study of the Rett Syndrome. Archival analysis, bibliometric techniques and expert surveys are combined with network analysis to identify the most creative scientists. First, we compare alternative measures of generative and combinatorial creativity. Then, we generalize our results in a stochastic model of socio-semantic network evolution. The model predictions are tested with an extended set of rare diseases. We find that new scientific collaborations among experts in a field enhance combinatorial creativity. Instead, high entry rates of novices are negatively related to generative creativity. By expanding the set of useful concepts, creative scientists gain in centrality. At the same time, by increasing their centrality in the scientific community, scientists can replicate and generalize their results, thus contributing to a scientific paradigm. M. Laura FrigottoMassimo Riccabonimassimo.riccaboni@imtlucca.it2011-07-27T08:47:33Z2014-03-05T13:44:24Zhttp://eprints.imtlucca.it/id/eprint/567This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/5672011-07-27T08:47:33ZEvent-driven optimal control of continuous Petri netsOptimally controlling a hybrid system is a challenging problem for which mainly continuous-time and discrete-time methods have been suggested. In this paper, the problem of optimal control is addressed in the framework of continuous Petri nets, a kind of hybrid systems whose state evolution is piecewise linear. The proposed approach consists of transforming the continuous Petri net into an equivalent hybrid system whose evolution is described by means of discrete-event steps. In particular, each step coincides with the occurrence of an event in the continuous Petri net. Thus, the number of steps required to know the behavior of the Petri net is minimum, while the accuracy is completely preserved. It is shown how to design a mixed integer linear programming problem in order to compute the optimal control solution of different performance criteria.Jorge JúlvezAlberto Bemporadalberto.bemporad@imtlucca.itLaura RecaldeManuel Silva2011-06-30T14:24:33Z2011-08-31T14:40:39Zhttp://eprints.imtlucca.it/id/eprint/663This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/6632011-06-30T14:24:33ZPublic Research and Industrial Innovation: A comparison of U.S. and European Innovation Systems in the Life SciencesFabio Pammollif.pammolli@imtlucca.itMassimo Riccabonimassimo.riccaboni@imtlucca.itWalter W. PowellJason Owen-Smith2011-06-06T15:00:33Z2014-01-15T10:30:16Zhttp://eprints.imtlucca.it/id/eprint/333This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3332011-06-06T15:00:33ZProgramming Access Control: The KLAIM ExperienceIn the design of programming languages for highly distributed systems where processes can migrate and execute on new hosts, the integration of security mechanisms is a major challenge. In this paper, we report our experience in the design of an experimental programming language, called Klaim, which provides mechanisms to customize access control policies. Klaim security architecture exploits a capability-based type system to provide mechanisms for specifying and enforcing policies that control uses of resources and authorize migration and execution of processes. By means of a few programming examples, we illustrate the flexibility of the Klaim approach to support the specification of control policies and to guarantee their enforcement.
Rocco De Nicolar.denicola@imtlucca.itGianLuigi FerrariRosario Pugliese2011-02-15T11:47:44Z2011-07-11T14:24:17Zhttp://eprints.imtlucca.it/id/eprint/73This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/732011-02-15T11:47:44ZThe Engraved Frontispiece of Kepler’s Tabulae Rudolphinae (1627): A Preliminary
StudyJohannes Kepler completed the Tabulae Rudolphinae in their logarithmic
form in 1624. It then took three years to gather the financial support, find a
suitable publisher and, particularly, overcome the difficulties posed by
Tycho’s heirs, who claimed both a share in the profits as well as censorship
rights. The tables represented the crowning achievement of Kepler’s career
as an astronomer. Because of their novelty and importance, he proposed
that the tall folio volume should have an appropriate frontispiece. The
paper describes the meaning of the very many components of the engraving
and relates them to Kepler’s published works. Furthermore, it traces the
origin of Kepler’s frontispiece to Tycho’s observatory on the Isle of Hven, as
well as suggests the possible pictorial source of the key element of the
drawing. Finally, it highlights how Kepler, by way of this frontispiece, found
the way both to assert his own position in and contribution to the history of
astronomy, as well as to place himself in the dispute over the Copernican
hypothesis.Stefano Gatteistefano.gattei@imtlucca.it