IMT Institutional Repository: No conditions. Results ordered -Date Deposited.
2021-10-23T15:05:43Z
EPrints
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http://eprints.imtlucca.it/
2018-03-09T11:37:17Z
2018-03-09T11:37:17Z
http://eprints.imtlucca.it/id/eprint/3984
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3984
2018-03-09T11:37:17Z
Potenzialità economica e dinamiche reddituali. Relazioni e fattori di impulso
Nicola Lattanzi
nicola.lattanzi@imtlucca.it
2016-04-06T12:13:52Z
2016-09-13T10:18:31Z
http://eprints.imtlucca.it/id/eprint/3377
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3377
2016-04-06T12:13:52Z
Seeing with one's hands: Supramodal cortical organization of perception in the human brain revealed by fMRI
Pietro Pietrini
pietro.pietrini@imtlucca.it
Maura L. Furey
Emiliano Ricciardi
emiliano.ricciardi@imtlucca.it
Maria Ida Gobbini
Mario Guazzelli
James V. Haxby
2016-03-23T13:12:34Z
2016-09-13T10:18:44Z
http://eprints.imtlucca.it/id/eprint/3321
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3321
2016-03-23T13:12:34Z
Effect of healthy aging on the cholinergic modulation of the interaction between prefrontal cortex (PFC) activity and visual working memory (vWM) task difficulty
Emiliano Ricciardi
emiliano.ricciardi@imtlucca.it
Pietro Pietrini
pietro.pietrini@imtlucca.it
Stanley I. Rapoport
Mark B. Schapiro
Maura L. Furey
2016-03-23T13:07:11Z
2016-09-13T10:18:01Z
http://eprints.imtlucca.it/id/eprint/3320
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3320
2016-03-23T13:07:11Z
Independent component analysis of fMRI data: a model based approach for artifacts separation
Independent component analysis applied to functional magnetic resonance imaging is a promising technique for non invasive study of brain function. We examine the behavior of spatial ICA decomposition applying ICA to simulated data sets. We study the ICA performances in presence of movement correlated and uncorrelated with activation task, also taking into account the presence of rician distributed noise. We show that the presence of image artifacts due to simulated subject movement and MRI noise greatly affects the method ability to reveal the activation, especially in the presence of movement correlated with activation task. Spatial smoothing of data, before ICA, seems to overcome this problem, allowing us to retrieve the original sources also in the presence of both correlated movement and high noise level.
Nicola Vanello
Vincenzo Positano
Emiliano Ricciardi
emiliano.ricciardi@imtlucca.it
Maria Filomena Santarelli
Mario Guazzelli
Pietro Pietrini
pietro.pietrini@imtlucca.it
Luigi Landini
2016-03-23T13:01:40Z
2016-09-13T10:19:00Z
http://eprints.imtlucca.it/id/eprint/3319
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3319
2016-03-23T13:01:40Z
Separation of movement and task related fMRI signal changes in a simulated data set by Independent Component Analysis
Nicola Vanello
Vincenzo Positano
Emiliano Ricciardi
emiliano.ricciardi@imtlucca.it
Maria Filomena Santarelli
Mario Guazzelli
Pietro Pietrini
pietro.pietrini@imtlucca.it
Luigi Landini
2016-03-23T13:00:07Z
2016-09-13T10:18:13Z
http://eprints.imtlucca.it/id/eprint/3318
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3318
2016-03-23T13:00:07Z
Cholinergic Enhancement during Working Memory Eliminates Regional Cerebral Blood Flow (rCBF) Modulation Associated with Task Difficulty in Prefrontal Cortex
Maura L. Furey
Emiliano Ricciardi
emiliano.ricciardi@imtlucca.it
Stanley I. Rapoport
Mark B. Schapiro
Pietro Pietrini
pietro.pietrini@imtlucca.it
2016-03-23T12:55:37Z
2016-03-23T12:55:37Z
http://eprints.imtlucca.it/id/eprint/3317
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3317
2016-03-23T12:55:37Z
Polimorfismi genetici e rischio di sviluppo di demenza
Silvia Pellegrini
Arianna Cozza
C. Franceschini
Veronica Mariotti
Mario Guazzelli
Pietro Pietrini
pietro.pietrini@imtlucca.it
2016-03-23T12:49:39Z
2016-03-23T12:49:39Z
http://eprints.imtlucca.it/id/eprint/3316
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3316
2016-03-23T12:49:39Z
Emozioni e sentimenti: come il cervello anima la nostra esistenza
Pietro Pietrini
pietro.pietrini@imtlucca.it
2016-03-23T12:30:26Z
2016-03-23T12:30:26Z
http://eprints.imtlucca.it/id/eprint/3315
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3315
2016-03-23T12:30:26Z
Toward a Biochemistry of Mind?
Pietro Pietrini
pietro.pietrini@imtlucca.it
2016-03-08T12:54:39Z
2016-09-14T10:21:18Z
http://eprints.imtlucca.it/id/eprint/3196
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3196
2016-03-08T12:54:39Z
Il catasto e i registri immobiliari
Lorenzo Casini
lorenzo.casini@imtlucca.it
2016-01-13T12:56:19Z
2016-09-14T10:21:18Z
http://eprints.imtlucca.it/id/eprint/2991
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2991
2016-01-13T12:56:19Z
Le agenzie amministrative
Lorenzo Casini
lorenzo.casini@imtlucca.it
2014-07-09T14:05:30Z
2014-07-09T14:05:30Z
http://eprints.imtlucca.it/id/eprint/2254
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2254
2014-07-09T14:05:30Z
Using MPC as master controller for integrated gasification combined cycle processes
The aim of this work is the design of a master controller for IGCC (Integrated Gasification Combine Cycle) plant, based on an MPC (Model Predictive Control) approach, which is able to coordinate the main process variables interacting with the basic structure of standard controllers at the unit level. Generally, a master controller is obtained by conventional loops based on a “pressure driven” configuration. In the following , the MPC library for MATLAB, by Bemporad, Morari and Ricker (2000) [1] has been applied to a detailed IGCC plant stimulation tool in order to understand the performance of a reliable multivariable linear MPC when adopted for such a nonlinear complex process with crucial targets. A detailed first principle model has been used as a “real plant” when performing the step tests for the identification of the simplified linear model and when checking the reliability of the control tool. Moreover, the effectiveness of the designed controller has been proved through the comparison between the linear MPC approach and an ideal solution (“direct” approach) obtained by the direct inversion of the DAE model, where perfect setpoint tracking is imposed by additional constraint equations and using the corresponding manipulated variables as closing variables. Moreover the performance of the derived MPC controller, when compared with a more conventional control configuration , shows a significant reduction of the overshoots and settling time when the plant is subject to load variations. The paper clearly shows how the MPS approach for a master controller is reliable, easy to design and of real value for practical purposes.
Alberto Bemporad
alberto.bemporad@imtlucca.it
F. Rusconi
Manfred Morari
M. Rovaglio
2014-06-30T08:32:08Z
2014-06-30T08:32:34Z
http://eprints.imtlucca.it/id/eprint/2216
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2216
2014-06-30T08:32:08Z
Employment protection and product market regulation
Product market regulation and employment protection are highly correlated across OECD countries. Using an augmented model of monopolistic competition we show why in countries with more regulated product markets, incumbent workers prefer to protect jobs relatively more. Product market regulation increases the scope for employment protection because firms can bear the cost of employment protection more easily and still break even. Moreover, product market regulation decreases employment so that the workers' outside option becomes relatively worse. This increases the incentive to protect the job.
Winfried Koeniger
Andrea Vindigni
andrea.vindigni@imtlucca.it
2014-02-27T08:53:15Z
2014-02-27T08:53:15Z
http://eprints.imtlucca.it/id/eprint/2143
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2143
2014-02-27T08:53:15Z
The Kuhn Controversy
Stefano Gattei
stefano.gattei@imtlucca.it
2013-12-04T11:04:48Z
2013-12-04T11:04:48Z
http://eprints.imtlucca.it/id/eprint/2021
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2021
2013-12-04T11:04:48Z
Reply to Olivier Rieppel
Stefano Gattei
stefano.gattei@imtlucca.it
2013-12-03T15:10:32Z
2013-12-03T15:10:32Z
http://eprints.imtlucca.it/id/eprint/2013
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2013-12-03T15:10:32Z
Editor's introduction of The Kuhn Controversy
This special issue of Social Epistemology is devoted to critical comments on Fuller's study of the philosophy of Thomas S. Kuhn and its context.
Stefano Gattei
stefano.gattei@imtlucca.it
2013-11-21T14:33:25Z
2014-10-09T09:20:26Z
http://eprints.imtlucca.it/id/eprint/1921
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1921
2013-11-21T14:33:25Z
Prediction of real contact area for interfacial debonding damage in fibrous composite materials
Giorgio Zavarise
Mauro Borri Brunetto
Marco Paggi
marco.paggi@imtlucca.it
2012-10-17T14:01:17Z
2012-10-17T14:01:17Z
http://eprints.imtlucca.it/id/eprint/1406
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1406
2012-10-17T14:01:17Z
La falce di Weimar. Rivoluzione, consigli e corporativismo nelle campagne prussiane (1918-1920)
Fiammetta Balestracci
fiammetta.balestracci@imtlucca.it
2012-02-27T11:18:53Z
2012-02-27T12:02:28Z
http://eprints.imtlucca.it/id/eprint/1192
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1192
2012-02-27T11:18:53Z
Introduction to complex networks
We present here an introduction to the ideas and models that physicist developed in order to describe the graph or network structure in a variety of different systems. Firstly we give a very basic list of definition that can be of some help in approaching this field. After that we present a brief review of the state of art for the models. © 2003 American Institute of Physics
Guido Caldarelli
guido.caldarelli@imtlucca.it
2012-02-20T13:54:38Z
2018-03-08T17:08:28Z
http://eprints.imtlucca.it/id/eprint/1135
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1135
2012-02-20T13:54:38Z
Universal scaling relations in food webs
The structure of ecological communities is usually represented by food webs. In these webs, we describe species by means of vertices connected by links representing the predations. We can therefore study different webs by considering the shape (topology) of these networks. Comparing food webs by searching for regularities is of fundamental importance, because universal patterns would reveal common principles underlying the organization of different ecosystems. However, features observed in small food webs are different from those found in large ones. Furthermore, food webs (except in isolated cases) do not share general features with other types of network (including the Internet, the World Wide Web and biological webs). These features are a small-world character and a scale-free (power-law) distribution of the degree (the number of links per vertex). Here we propose to describe food webs as transportation networks by extending to them the concept of allometric scaling (how branching properties change with network size). We then decompose food webs in spanning trees and loop-forming links. We show that, whereas the number of loops varies significantly across real webs, spanning trees are characterized by universal scaling relations.
Diego Garlaschelli
diego.garlaschelli@imtlucca.it
Guido Caldarelli
guido.caldarelli@imtlucca.it
Luciano Pietronero
2012-02-20T13:43:10Z
2013-11-20T14:30:41Z
http://eprints.imtlucca.it/id/eprint/1134
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1134
2012-02-20T13:43:10Z
Topology of correlation-based minimal spanning trees in real and model markets
We compare the topological properties of the minimal spanning tree obtained from a large group of stocks traded at the New York Stock Exchange during a 12-year trading period with the one obtained from surrogated data simulated by using simple market models. We find that the empirical tree has features of a complex network that cannot be reproduced, even as a first approximation, by a random market model and by the widespread one-factor model.
Giovanni Bonanno
Guido Caldarelli
guido.caldarelli@imtlucca.it
Fabrizio Lillo
Rosario Nunzio Mantegna
2012-02-20T13:38:39Z
2018-03-08T17:08:41Z
http://eprints.imtlucca.it/id/eprint/1133
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1133
2012-02-20T13:38:39Z
Food web structure and the evolution of complex networks
In addition to traditional properties such as the degree distribution P(k), in this work we propose two other useful quantities that can help in characterizing the topology of food webs quantitatively, namely the allometric scaling relations C(A) and the branch size distribution P(A) which are defined on the spanning tree of the webs. These quantities, whose use has proved relevant in characterizing other different networks appearing in nature (such as river basins, Internet, and vascular systems), are related (in the context of food webs) to the efficiency in the resource transfer and to the stability against species removal. We present the analysis of the data for both real food webs and numerical simulations of a growing network model. Our results allow us to conclude that real food webs display a high degree of both efficiency and stability due to the evolving character of their topology.
Guido Caldarelli
guido.caldarelli@imtlucca.it
Diego Garlaschelli
diego.garlaschelli@imtlucca.it
Luciano Pietronero
2012-02-15T16:25:31Z
2012-02-21T13:54:41Z
http://eprints.imtlucca.it/id/eprint/1130
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1130
2012-02-15T16:25:31Z
Quantitative description and modeling of real networks
We present data analysis and modeling of two particular cases of study in the field of growing networks. We analyze World Wide Web data set and authorship collaboration networks in order to check the presence of correlation in the data. The results are reproduced with good agreement through a suitable modification of the standard Albert-Barabási model of network growth. In particular, intrinsic relevance of sites plays a role in determining the future degree of the vertex.
Andrea Capocci
Guido Caldarelli
guido.caldarelli@imtlucca.it
Paolo De Los Rios
2012-02-15T16:22:57Z
2013-11-20T14:28:27Z
http://eprints.imtlucca.it/id/eprint/1129
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1129
2012-02-15T16:22:57Z
Dynamic fracture model for acoustic emission
We study the acoustic emission produced by micro-cracks using a two-dimensional disordered lattice model of dynamic fracture, which allows to relate the acoustic response to the internal damage of the sample. We find that the distributions of acoustic energy bursts decays as a power law in agreement with experimental observations. The scaling exponents measured in the present dynamic model can related to those obtained in the quasi-static random fuse model.
Manuela Minozzi
Guido Caldarelli
guido.caldarelli@imtlucca.it
Luciano Pietronero
Stefano Zapperi
2012-01-18T11:28:17Z
2012-01-18T11:28:17Z
http://eprints.imtlucca.it/id/eprint/1062
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1062
2012-01-18T11:28:17Z
Does co-location matter for formal knowledge collaboration in the Swedish biotechnology–pharmaceutical sector?
This article addresses the validity of assumptions about the importance of co-locality for innovation, by analyzing whether or not co-location matters for formal knowledge collaboration in the Swedish biotechnology–pharmaceutical sector, or biotech–pharma sector. The population of Swedish biotech–pharma firms has been defined, based on the three criteria of geographical location, their engagement in active knowledge development, and their specialized knowledge/product focus. The firms’ patterns of regional, national and international collaboration with other firms and with universities is analyzed, as well as the differing collaborative patterns of small versus large firm. In addressing the theoretical questions about the relative importance of co-location for innovation, the article also provides an empirical overview of the Swedish biotech–pharma sector, especially trends over time. This paper thus contributes to the literature by expanding our empirical knowledge about one European biotech–pharma sectoral system, e.g. Sweden, as well as addressing the theoretical question about the relative importance of co-location for formal knowledge collaboration.
Maureen McKelvey
Håkan Alm
Massimo Riccaboni
massimo.riccaboni@imtlucca.it
2011-11-22T13:30:17Z
2011-12-20T12:00:25Z
http://eprints.imtlucca.it/id/eprint/1017
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/1017
2011-11-22T13:30:17Z
Symmetry reduction and heuristic search for error detection in model checking
The state explosion problem is the main limitation of model checking. Symmetries in the system being verified can be exploited in order to avoid this problem by defining an equivalence (symmetry) relation on the states of the system, which induces a semantically equivalent quotient system of smaller size. On the other hand, heuristic search algorithms can be applied to improve the bug finding capabilities of model checking. Such algorithms use
heuristic functions to guide the exploration. Bestfirst
is used for accelerating the search, while A* guarantees optimal error trails if combined with admissible estimates. We analyze some aspects of combining both approaches, concentrating on the problem of finding the optimal path to the equivalence class of a given error state. Experimental
results evaluate our approach.
Alberto Lluch-Lafuente
alberto.lluch@imtlucca.it
2011-10-24T13:28:44Z
2011-10-24T13:28:44Z
http://eprints.imtlucca.it/id/eprint/963
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/963
2011-10-24T13:28:44Z
Per Carlo Ludovico Ragghianti
Emanuele Pellegrini
emanuele.pellegrini@imtlucca.it
2011-10-18T09:16:14Z
2011-10-18T09:16:14Z
http://eprints.imtlucca.it/id/eprint/948
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/948
2011-10-18T09:16:14Z
Splendori e miserie di un museo civico attraverso il Novecento
Emanuele Pellegrini
emanuele.pellegrini@imtlucca.it
2011-10-13T08:39:47Z
2011-10-13T13:07:19Z
http://eprints.imtlucca.it/id/eprint/927
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/927
2011-10-13T08:39:47Z
Giulio Romano Ansaldi : avvio di una ricerca
Emanuele Pellegrini
emanuele.pellegrini@imtlucca.it
2011-09-09T13:22:10Z
2013-03-05T15:50:22Z
http://eprints.imtlucca.it/id/eprint/856
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/856
2011-09-09T13:22:10Z
DNA-Based digital signal processing
Sotirios A. Tsaftaris
sotirios.tsaftaris@imtlucca.it
2011-07-27T10:51:01Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/558
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/558
2011-07-27T10:51:01Z
Approximate multiparametric convex programming
Alberto Bemporad
alberto.bemporad@imtlucca.it
Carlo Filippi
2011-07-27T09:05:32Z
2011-08-05T14:09:02Z
http://eprints.imtlucca.it/id/eprint/459
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/459
2011-07-27T09:05:32Z
An algorithm for multi-parametric quadratic programming and explicit MPC solutions
Explicit solutions to constrained linear model predictive control problems can be obtained by solving multi-parametric quadratic programs (mp-QP) where the parameters are the components of the state vector. We study the properties of the polyhedral partition of the state space induced by the multi-parametric piecewise affine solution and propose a new mp-QP solver. Compared to existing algorithms, our approach adopts a different exploration strategy for subdividing the parameter space, avoiding unnecessary partitioning and QP problem solving, with a significant improvement of efficiency.
Petter Tondel
Tor Arne Johansen
Alberto Bemporad
alberto.bemporad@imtlucca.it
2011-07-27T09:04:28Z
2011-08-05T14:08:37Z
http://eprints.imtlucca.it/id/eprint/460
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/460
2011-07-27T09:04:28Z
Evaluation of piecewise affine control via binary search tree
We present an algorithm for generating a binary search tree that allows efficient computation of piecewise affine (PWA) functions defined on a polyhedral partition. This is useful for PWA control approaches, such as explicit model predictive control, as it allows the controller to be implemented online with small computational effort. The computation time is logarithmic in the number of regions in the PWA partition.
Petter Tondel
Tor Arne Johansen
Alberto Bemporad
alberto.bemporad@imtlucca.it
2011-07-27T09:04:23Z
2011-08-05T14:08:12Z
http://eprints.imtlucca.it/id/eprint/556
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/556
2011-07-27T09:04:23Z
Optimal control of uncertain piecewise affine/mixed logical dynamical systems
This paper proposes an approach to extend the mixed logical
dynamical modelling framework for synthesizing robust optimal control actions for constrained piecewise affine systems subject to bounded additive input disturbances. Rather than using closed-loop dynamic programming arguments, robustness is achieved here with an open-loop optimization strategy, such that the optimal control sequence optimizes nominal performance while robustly guaranteeing that safety/performance constraints are respected. The proposed approach is based on the robust mode control concept, which enforces the control input
to generate trajectories such that the mode of the system, at each time instant, is independent of the disturbances.
Miguel Pedro Silva
Alberto Bemporad
alberto.bemporad@imtlucca.it
Miguel Ayala Botto
José Sa da Costa
2011-07-27T09:04:20Z
2016-05-11T11:07:22Z
http://eprints.imtlucca.it/id/eprint/487
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/487
2011-07-27T09:04:20Z
Hybrid modeling and optimal control of an asphalt base process
Bostjan Potocnik
Alberto Bemporad
alberto.bemporad@imtlucca.it
Fabio Danilo Torrisi
Gasper Music
Borut Zupancic
2011-07-27T09:04:08Z
2011-08-05T14:07:13Z
http://eprints.imtlucca.it/id/eprint/552
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/552
2011-07-27T09:04:08Z
Receding-horizon control of LTI systems with quantized inputs
This paper deals with the stabilization problem for a particular class of hybrid systems, namely discrete–time linear systems subject to a uniform (a priori fixed) quantization of the control set. Results of our previous work on the subject provided a description of minimal (in a specific sense) invariant sets that could be rendered maximally attractive under any quantized feedback strategy. In this paper, we consider the design of stabilizing laws that optimize a given cost index on the state and input evolution on a finite, receding horizon. Application of Model Predictive Control techniques for the solution of similar hybrid control problems through Mixed Logical Dynamical reformulations can provide a stabilizing control law, provided that the feasibility hypotheses are met. In this paper, we discuss precisely what are the shortest horizon length and the minimal invariant terminal set for which it can be guaranteed a stabilizing MPC scheme. The final paper will provide an example and simulations of the application of the control scheme to a practical quantized control problem.
Bruno Picasso
Stefania Pancanti
Alberto Bemporad
alberto.bemporad@imtlucca.it
Antonio Bicchi
2011-07-27T09:04:05Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/554
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/554
2011-07-27T09:04:05Z
Set membership identification of piecewise affine models
This paper addresses the problem of identification of piecewise affine (PWA)models, which involves the joint estimations of both the parameters of the affine submodels and the partition of the PWA map from data. According to ideas from set-membership identification, the key approach is to characterize the model by its maximum allowed prediction error, which is used as a tuning knob for traning off between prediction accuracy and model complexity. At initialization, the proposed procedure for PWA identification exploits a technique per partitioning an infeasible system of linear inequalities into a (possibly minimum) number of feasible subsystems. This provides both an initial clustering of the datapoints and a guess of the number of required submodels, which therefore is not fixed a priori. A refinement procedure is then applied in order to improve both data classification and parameter estimation. The partition of the PWA maps is finally estimated by considering multicategory classification techniques.
Alberto Bemporad
alberto.bemporad@imtlucca.it
Andrea Garulli
Simone Paoletti
Antonio Vicino
2011-07-27T09:04:02Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/553
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/553
2011-07-27T09:04:02Z
Optimal state-feedback quadratic regulation of linear hybrid automata
For linear hybrid automata, namely switched linear autonomous systems whose mode of operation is determined by a controlled automaton, in this paper we face the problem of optimal control, where the objective is to minimize a quadratic performance index over an infinite time horizon. The quantities to be optimized are the sequence of switching times and the sequence of modes (or ”locations”), under the following constraints: the sequence of modes has a finite length; the discrete dynamics of the automaton restricts the possible switches from a given location to
the next location, with a cost associated to each switch; the time interval between two consecutive switching times is greater than a fixed quantity. We show how a state-feedback solution can be computed off-line through a numerical procedure.
Alberto Bemporad
alberto.bemporad@imtlucca.it
Daniele Corona
Alessandro Giua
Carla Seatzu
2011-07-27T09:04:00Z
2011-08-05T14:04:27Z
http://eprints.imtlucca.it/id/eprint/450
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/450
2011-07-27T09:04:00Z
A geometric algorithm for multi-parametric linear programming
We propose a novel algorithm for solving multiparametric linear programming problems. Rather than visiting different bases of the associated LP tableau, we follow a geometric approach based on the direct exploration of the parameter space. The resulting algorithm has computational advantages, namely the simplicity of its implementation in a recursive form and an efficient handling of primal and dual degeneracy. Illustrative examples describe the approach throughout the paper. The algorithm is used to solve finite-time constrained optimal control problems for discrete-time linear dynamical systems.
Francesco Borrelli
Alberto Bemporad
alberto.bemporad@imtlucca.it
Manfred Morari
2011-07-27T09:03:57Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/501
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/501
2011-07-27T09:03:57Z
Hybrid control of an automotive robotized gearbox for reduction of consumptions and emissions
This paper describes the application of hybrid modeling and receding horizon optimal control techniques for supervising an automotive robotized gearbox, with the goal of reducing consumptions and emissions, a problem that is currently under investigation at Fiat Research Center (CRF). We show that the dynamic behavior of the vehicle can be easily approximated and captured by the hybrid model, and through simulations on standard speed patterns that a good closed loop performance can be achieved. The synthesized control law can be implemented on automotive hardware as a piecewise affine function of the measured and estimated quantities.
Alberto Bemporad
alberto.bemporad@imtlucca.it
Pandeli Borodani
Massimo Mannelli
2011-07-27T09:03:54Z
2014-01-24T14:29:49Z
http://eprints.imtlucca.it/id/eprint/627
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/627
2011-07-27T09:03:54Z
Hybrid Toolbox for MATLAB - User's Guide
The Hybrid Toolbox is a MATLAB/Simulink toolbox for modeling, simulating, and verifying hybrid dynamical systems, for designing and simulating model predictive controllers for hybrid systems subject to constraints, and for generating linear and hybrid MPC control laws in piecewise affine form that can be directly embedded as C-code in real-time applications.
Alberto Bemporad
alberto.bemporad@imtlucca.it
2011-07-27T09:02:47Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/471
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/471
2011-07-27T09:02:47Z
Suboptimal Explicit Receding Horizon Control via Approximate Multiparametric Quadratic Programming
Algorithms for solving multiparametric quadratic programming (MPQP) were recently proposed in Refs. 1–2 for computing explicit receding horizon control (RHC) laws for linear systems subject to linear constraints on input and state variables. The reason for this interest is that the solution to MPQP is a piecewise affine function of the state vector and thus it is easily implementable online. The main drawback of solving MPQP exactly is that, whenever the number of linear constraints involved in the optimization problem increases, the number of polyhedral cells in the piecewise affine partition of the parameter space may increase exponentially. In this paper, we address the problem of finding approximate solutions to MPQP, where the degree of approximation is arbitrary and allows to tradeoff between optimality and a smaller number of cells in the piecewise affine solution. We provide analytic formulas for bounding the errors on the optimal value and the optimizer, and for guaranteeing that the resulting suboptimal RHC law provides closed-loop stability and constraint fulfillment.
Alberto Bemporad
alberto.bemporad@imtlucca.it
Carlo Filippi
2011-07-27T09:02:45Z
2011-08-05T14:03:07Z
http://eprints.imtlucca.it/id/eprint/555
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/555
2011-07-27T09:02:45Z
An efficient algorithm for computing the state feedback optimal control law for discrete time hybrid systems
Francesco Borrelli
Mato Baotic
Alberto Bemporad
alberto.bemporad@imtlucca.it
Manfred Morari
2011-07-27T09:02:43Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/472
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/472
2011-07-27T09:02:43Z
Min-max control of constrained uncertain discrete-time linear systems
For discrete-time uncertain linear systems with constraints on inputs and states, we develop an approach to determine state feedback controllers based on a min-max control formulation. Robustness is achieved against additive norm-bounded input disturbances and/or polyhedral parametric uncertainties in the state-space matrices. We show that the finite-horizon robust optimal control law is a continuous piecewise affine function of the state vector and can be calculated by solving a sequence of multiparametric linear programs. When the optimal control law is implemented in a receding horizon scheme, only a piecewise affine function needs to be evaluated on line at each time step. The technique computes the robust optimal feedback controller for a rather general class of systems with modest computational effort without needing to resort to gridding of the state-space.
Alberto Bemporad
alberto.bemporad@imtlucca.it
Francesco Borrelli
Manfred Morari
2011-07-27T09:02:41Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/483
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/483
2011-07-27T09:02:41Z
Corrigendum to: "The explicit linear quadratic regulator for constrained systems" [Automatica 38(1) (2002) 3-20]
We apologize that Example 7.1 as publishedin Bemporad,
Morari, Dua, andPistikopoulos (2002) is incorrect due to a
miscalculation of the weight matrix P on the terminal state
Alberto Bemporad
alberto.bemporad@imtlucca.it
Manfred Morari
Vivek Dua
Efstratios N. Pistikopoulos
2011-07-27T09:02:38Z
2011-08-05T14:01:58Z
http://eprints.imtlucca.it/id/eprint/557
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/557
2011-07-27T09:02:38Z
Further results on multiparametric quadratic programming
In this paper we extend results on strictly convex multiparametric quadratic programming (mpQP) to the convex case. An efficient method for computing the mpQP solution is provided. We give a fairly complete description of the mpQP solver, focusing on implementational issues such as degeneracy handling.
Petter Tondel
Tor Arne Johansen
Alberto Bemporad
alberto.bemporad@imtlucca.it
2011-07-27T09:02:37Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/559
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/559
2011-07-27T09:02:37Z
Logic-based hybrid solvers for optimal control of hybrid systems
Combinatorial optimization over continuous and integer variables was proposed recently as an useful tool for solving complex optimal control problems for linear hybrid dynamical systems formulated in discrete-time. Current approaches are based on mixed-integer linear/quadratic programming (MIP), which provides the solution after solving a sequence of relaxed standard linear (or quadratic) programs (LP, QP). An MIP formulation has the drawback of requiring that the discrete/logic part of the hybrid problem needs to be converted to into mixed-integer inequalities. Although this operation can be done automatically, most of the original discrete structure of the problem is lost during the conversion. Moreover, the efficiency of the MIP solver only relies upon the tightness of the continuous LP/QP relaxations. In this paper we attempt at overcoming such difficulties by combining MIP and constraint programming (CP) techniques into a "hybrid" solver, taking advantage of CP for dealing efficiently with satisfiability of logic constraints. We detail how to model the hybrid dynamics so that the optimal control problem can be solved by the hybrid MIP+CP solver, and show on a case study that the achieved performance is superior to the one achieved by pure MIP solvers.
Alberto Bemporad
alberto.bemporad@imtlucca.it
Nicolò Giorgetti
2011-07-27T09:02:33Z
2011-08-04T07:29:08Z
http://eprints.imtlucca.it/id/eprint/560
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/560
2011-07-27T09:02:33Z
Multiparametric nonlinear integer programming and explicit quantized optimal control
This paper deals with multiparametric nonlinear integer programming problems where the optimization variables belong to a finite set and where the cost function and the constraints depend in an arbitrary nonlinear fashion on the optimization variables and in a linear fashion on the parameters. We examine the main theoretical properties of the optimizer and of the optimum as a function of the parameters, and propose a solution algorithm. The methodology is employed to investigate properties of quantized optimal control laws and optimal performance, and to obtain their explicit representation as a function of the state vector.
Alberto Bemporad
alberto.bemporad@imtlucca.it
2011-07-01T10:40:04Z
2011-08-31T14:40:39Z
http://eprints.imtlucca.it/id/eprint/687
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/687
2011-07-01T10:40:04Z
On size and growth of business firms
We study size and growth distributions of products and business firms in the context of a given industry. Firm size growth is analyzed in terms of two basic mechanisms, i.e., the increase of the number of new elementary business units and their size growth. We find a power-law relationship between size and the variance of growth rates for both firms and products, with an exponent between -0.17 and -0.15, with a remarkable stability upon aggregation. We then introduce a simple and general model of proportional growth for both the number of firm independent constituent units and their size, which conveys a good representation of the empirical evidences. This general and plausible generative process can account for the observed scaling in a wide variety of economic and industrial systems. Our findings contribute to shed light on the mechanisms that sustain economic growth in terms of the relationships between the size of economic entities and the number and size distribution of their elementary components.
Fabio Pammolli
f.pammolli@imtlucca.it
G. De Fabritiis
Massimo Riccaboni
massimo.riccaboni@imtlucca.it
2011-06-30T14:24:45Z
2011-08-31T14:40:39Z
http://eprints.imtlucca.it/id/eprint/662
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/662
2011-06-30T14:24:45Z
Technological Paradigms and the Evolution of Networks: Lessons from the Pharmaceutical Industry
Fabio Pammolli
f.pammolli@imtlucca.it
Massimo Riccaboni
massimo.riccaboni@imtlucca.it
2011-06-30T14:24:33Z
2011-08-31T14:40:39Z
http://eprints.imtlucca.it/id/eprint/663
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/663
2011-06-30T14:24:33Z
Public Research and Industrial Innovation: A comparison of U.S. and European Innovation Systems in the Life Sciences
Fabio Pammolli
f.pammolli@imtlucca.it
Massimo Riccaboni
massimo.riccaboni@imtlucca.it
Walter W. Powell
Jason Owen-Smith
2011-06-30T14:24:24Z
2011-08-31T14:40:39Z
http://eprints.imtlucca.it/id/eprint/664
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/664
2011-06-30T14:24:24Z
Technological regimes and the evolution of networks of innovators. Lessons from biotechnology and pharmaceuticals
In this paper, we analyse the relationships between technological regimes, regimes of local interaction, and the global structure of an industrial network. Given the complexity of the task, we follow a semi-inductivist approach, combining quantitative empirical analyses and simulative exercises. We show that the topological properties of the R&D network in pharmaceuticals are the result of neither a purely random nor of a cumulative process of growth. Instead, they emerge from a mixture of the two generative processes, under a regime of intense and stable entry. This paper should be considered only as a first step towards the understanding of some general determinants of industry networks growth. Despite its limitations, it provides a parsimonious and general framework to reverse engineer the growth of networks in different industries. Some of the current limitations of our analysis could be overcome, in the future, based on a higher availability of data on real systems and, in particular, of detailed topological and economic information on real-world networks. While currently such data are rare, the increasing interest in industrial networks should soon lead to the development of suitable data sets, offering further guidance for modelling and interpreting the growth of these complex and important economic systems.
Fabio Pammolli
f.pammolli@imtlucca.it
Massimo Riccaboni
massimo.riccaboni@imtlucca.it
2011-06-08T13:28:05Z
2011-07-11T14:36:26Z
http://eprints.imtlucca.it/id/eprint/319
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/319
2011-06-08T13:28:05Z
Nondeterministic regular expressions as solutions of equational systems
We define the class of the linear systems whose solution is expressible as a tuple of nondeterministic regular expressions when they are interpreted as trees of actions rather than as sets of sequences. We precisely characterize those systems that have a regular expression as "canonical" solution, and show that any regular expression can be obtained as a canonical solution of a system of the defined class.
Rocco De Nicola
r.denicola@imtlucca.it
Anna Labella
2011-06-06T15:06:07Z
2014-01-15T10:29:16Z
http://eprints.imtlucca.it/id/eprint/317
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/317
2011-06-06T15:06:07Z
The Klaim Project: Theory and Practice
Klaim (Kernel Language for Agents Interaction and
Mobility) is an experimental language specifically designed to
program distributed systems consisting of several mobile
components that interact through multiple distributed tuple
spaces. Klaim primitives allow programmers to distribute and
retrieve data and processes to and from the nodes of a net.
Moreover, localities are first-class citizens that can be
dynamically created and communicated over the network. Components,
both stationary and mobile, can explicitly refer and control the
spatial structures of the network.
This paper reports the experiences in the design and development
of Klaim. Its main purpose is to outline the theoretical
foundations of the main features of Klaim and its programming
model. We also present a modal logic that permits reasoning about
behavioural properties of systems and various type systems that
help in controlling agents movements and actions. Extensions of
the language in the direction of object oriented programming are
also discussed together with the description of the implementation
efforts which have lead to the current prototypes.
Lorenzo Bettini
Viviana Bono
Rocco De Nicola
r.denicola@imtlucca.it
GianLuigi Ferrari
Daniele Gorla
Michele Loreti
Eugenio Moggi
Rosario Pugliese
Emilio Tuosto
Betti Venneri
2011-06-06T09:03:49Z
2011-09-19T10:00:54Z
http://eprints.imtlucca.it/id/eprint/323
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/323
2011-06-06T09:03:49Z
AGILE: Software Architecture for Mobility
Architecture-based approaches have been promoted as a means of controlling the complexity of system construction and evolution, in particular for providing systems with the agility required to operate in turbulent environments and to adapt very quickly to changes in the enterprise world. Recent technological advances in communication and distribution have made mobility an additional factor of complexity, one for which current architectural concepts and techniques can be hardly used. The AGILE project is developing an architectural approach in which mobility aspects can be modelled explicitly and mapped on the distribution and communication topology made available at physical levels. The whole approach is developed over a uniform mathematical framework based on graph-oriented techniques that support sound methodological principles, formal analysis, and refinement. This paper describes the AGILE project and some of the results gained during the first project year.
Luis Filipe Andrade
Paolo Baldan
Hubert Baumeister
Roberto Bruni
Andrea Corradini
Rocco De Nicola
r.denicola@imtlucca.it
Jose Luiz Fiadeiro
Fabio Gadducci
Stefania Gnesi
Piotr Hoffman
Nora Koch
Piotr Kosiuczenko
Alessandro Lapadula
Diego Latella
Antonia Lopes
Michele Loreti
Mieke Massink
Franco Mazzanti
Ugo Montanari
Cristóvão Oliveira
Rosario Pugliese
Andrzej Tarlecki
Michel Wermelinger
Martin Wirsing
Artur Zawlocki
2011-03-30T10:16:06Z
2011-07-11T14:21:54Z
http://eprints.imtlucca.it/id/eprint/227
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/227
2011-03-30T10:16:06Z
Volo Alitalia verso il mercato. Turbolenze con le agenzie di viaggio
In recent years Alitalia has often been subject to antitrust scrutiny by the Autorità Garante della Concorrenza e del Mercato. This article analyses the recent proceeding involving travel agents. The decision has been appealed and judged by the administrative court (TAR Lazio) and then, again, by the AGCM for failure in respecting the authority's decision. It was focused on the arrangements with travel agents and, more precisely, on the (over)commissions paid by Alitalia on the tickets sold by agents. These commissions represented illegal loyalty discounts and gave rise to abusive discrimination between travel agents. The case is discussed by underlining the ongoing deregulation of the airline sector, pointing out the many critical aspects that the Italian national champion has to deal with and, above all, overcome.
Andrea Giannaccari
a.giannaccari@imtlucca.it
2011-03-30T10:13:59Z
2011-07-11T14:21:54Z
http://eprints.imtlucca.it/id/eprint/241
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/241
2011-03-30T10:13:59Z
L’ambito di applicazione della legge, l’importazione e l’esportazione dei dati personali
Andrea Giannaccari
a.giannaccari@imtlucca.it
2011-03-09T16:16:42Z
2011-07-11T14:27:37Z
http://eprints.imtlucca.it/id/eprint/196
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/196
2011-03-09T16:16:42Z
Il liberalismo di Bruno Leoni
Antonio Masala
a.masala@imtlucca.it
2011-03-01T10:03:05Z
2011-07-11T14:33:43Z
http://eprints.imtlucca.it/id/eprint/130
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/130
2011-03-01T10:03:05Z
Symbolic Analysis of Crypto-Protocols Based on Modular Exponentiation
Automatic methods developed so far for analysis of security protocols only model a limited set of cryptographic primitives (often, only encryption and concatenation) and from low-level features of cryptographic algorithms. This paper is an attempt towards closing this gap. We propose a symbolic technique and a decision method for analysis of protocols based on modular exponentiation, such as Diffie-Hellman key exchange. We introduce a protocol description language along with its semantics. Then, we propose a notion of symbolic execution and, based on it, a verification method. We prove that the method is sound and complete with respect to the language semantics.
Michele Boreale
Maria Grazia Buscemi
m.buscemi@imtlucca.it
2011-02-15T10:28:26Z
2013-12-03T14:29:43Z
http://eprints.imtlucca.it/id/eprint/69
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/69
2011-02-15T10:28:26Z
A Plea for Criticism in Matters Epistemological
Stefano Gattei
stefano.gattei@imtlucca.it