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Direttore Vicario: Prof. Gabriele Grillo
Responsabile Gestionale: Dr.ssa Franca Di Censo

 Seminari

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Prossimi Seminari

  • Laser "su misura" per il trattamento di tumori
    Paola Saccomandi, Politecnico di Milano
    mercoledì 27 marzo 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Some remarks on the forces exerted by a viscous fluid on a bluff body
    Gianmarco Sperone, Politecnico di Milano
    giovedì 28 marzo 2019 alle ore 15:15, Aula seminari 3° piano
  • Simplicial splines for representation of density functions
    Karel Hron e Jitka Machalova, Palacky University di Olomouc
    martedì 2 aprile 2019 alle ore 15:00 precise, Aula Seminari 'Saleri' VI Piano MOX-Dipartimento di Matematica, Politecnico di Milano - Edificio 14
  • Stima del valore aggiunto di scuola: stato dell'arte del modello INVALSI e prospettive. Quali implicazioni di policy?
    Tommaso Agasisti, Politecnico di Milano
    mercoledì 3 aprile 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • On the modelling of particle and pedestrian motion with Fokker-Planck equations
    Alfio Borzì, University of Wuerzburg -Germania-
    giovedì 4 aprile 2019 alle ore 14:00, Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO
  • Problemi di frontiera libera nelle scienze applicate
    Sandro Salsa, Politecnico di Milano
    mercoledì 10 aprile 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Errori sistematici e confondimento degli studi osservazionali basati sui dati dal mondo reale
    Giovanni Corrao, Università degli Studi di Milano-Bicocca
    mercoledì 8 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Inverse Problems in Adaptive Optics
    Ronny Ramlau, RICAM, Austrian Academy of Sciences, Linz, Austria
    mercoledì 8 maggio 2019 alle ore 14:00, Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO
  • Forma e complessità in Natura: perché il mondo è matematico?
    Pasquale Ciarletta, Politecnico di Milano
    mercoledì 15 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Matematica, società, economia e sviluppo
    Giulia di Nunno, University di Oslo
    mercoledì 22 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Comunicare il progetto. Storytelling e tecniche di rappresentazione
    Francesca Piredda, Politecnico di Milano
    mercoledì 29 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Semi-implicit finite-volume integrators for all-scale atmospheric dynamics
    Piotr Smolarkiewicz, European Centre for Medium-Range Weather Forecasts, Reading, Berkshire, United Kingdom
    giovedì 30 maggio 2019 alle ore 14:00, Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO

Seminari Passati

  • An overview of some mathematical and computational problems in Network Science
    Michele Benzi, Scuola Normale Superiore, Pisa
    giovedì 22 novembre 2018 alle ore 14:00,  Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO
    ABSTRACT
    Network Science is a rapidly growing interdisciplinary area at the intersection of mathematics, computer science, and a multitude of disciplines from the natural and life sciences to the social sciences and even the humanities. Network analysis methods are now widely used in proteomics, in the study of social networks (both human and animal), in finance, in ecology, in bibliometric studies, in archeology, and in a host of other fields. In this talk I will introduce the audience to some of the mathematical and computational problems and methods of complex networks, with an emphasis on the basic notions of centrality and communicability. More specifically, I will describe some of the problems in large-scale numerical linear algebra arising in this area, and how they differ from the corresponding problems encountered in more traditional applications of numerical analysis. The talk will be accessible to students, requiring only a modest background in linear algebra, numerical analysis and graph theory.

    Contacts: paola.antonietti@polimi.it, paolo.zunino@polimi.it
  • Working with compositional data in coordinates
    Eva Fiserova, Palacky University Olomouc, Czech Republic
    mercoledì 21 novembre 2018 alle ore 14:30, aula Saleri VI piano
    ABSTRACT
    Compositional data are multivariate observations carrying only relative information, popularly expressed in percentages, proportions, mg/kg, etc. Because of features inherent to compositional data, such as scale invariance and the relative scale, the statistical analysis of raw compositional data often leads to spurious results. Natural principles of compositional data are followed by the Aitchison geometry on a simplex, the sample space of compositional data (Aitchison, 1986; Pawlowsky-Glahn et al., 2015). However, because most standard statistical methods rely on the Euclidean geometry in real space, compositional data need to be converted to this space prior to statistical processing. In the lecture, we will present the log ratio methodology for dealing with compositional data and several types of their coordinate representations, such as orthonormal log-ratio coordinates, pivot coordinates, weighted pivot coordinates (Hron et al., 2017), or symmetric balances (!
    Kynvclova et al., 2017). Their usage will be demonstrated on examples.
  • Illuminazione, visione e opere d'arte: il punto di vista del fisico
    Farini Alessandro, Istituto Nazionale di Ottica, CNR, Firenze
    mercoledì 21 novembre 2018 alle ore 15:00, Sala Consiglio VII piano
    ABSTRACT
    Quale è il legame tra le onde elettromagnetiche appartenenti a quella parte dello spettro che chiamiamo visibile e la nostra visione? L’interpretazione che il nostro occhio e il nostro cervello forniscono della realtà circostante è così complessa che è necessario tenere conto di tantissimi fattori per comprendere ad esempio perché vediamo alcuni colori o percepiamo il contrasto in un certo modo. Uno degli esempi più affascinanti è sicuramente quello delle opere pittoriche, dove spesso ci rendiamo conto che l’artista dimostra una comprensione, almeno
    implicita, del funzionamento della nostra percezione veramente interessante. Questi aspetti saranno mostrati con alcuni esperimenti dal vivo che vogliono rendere più chiari i concetti espressi.
  • Mixed finite elements for next-generation atmospheric models
    Tommaso Benacchio , MOX, Politecnico di Milano
    martedì 20 novembre 2018 alle ore 10:30, aula Saleri VI piano
    ABSTRACT
    The terrestrial atmosphere provides the arena for physical processes on multiple spatial and temporal scales. Numerical methods used to solve the governing hyperbolic models must simulate features of meteorological interest accurately while handling efficiently fast and less significant wavelike phenomena. Tight production constraints in operational numerical weather prediction (NWP) drive the development of scalable dynamical cores to keep up with computing architectures that increasingly rely on massively parallel systems for performance.
    While spectral transform and grid-point models have traditionally held sway in operational NWP and climate prediction, finite element methods have been gaining ground in recent years, due to their straightforward accuracy-tuning capabilities and flexibility towards unstructured grid arrangements in a context of deteriorating parallel performance of legacy codes. The seminar will present a mixed finite element-based dynamical core for the solution of the nonhydrostatic compressible equations under gravity. The mimetic spatial discretization reproduces continuous vector identities at the discrete level and ensures desirable properties such as pointwise mass conservation. Placement of the thermodynamic variable in a horizontally discontinuous, vertically continuous function space was recently shown to remove spurious buoyancy modes. Time discretization is handled by an iterative semi-implicit method. The numerical scheme is coded in object-oriented Fortran within a novel co-des!
    igned software framework using PSyClone, a Python-based domain-specific compiler. The new paradigm enables a clear separation of the scientific routines from the computational infrastructure, greatly facilitating portability across platforms and performance optimization.
    Results on two- and three-dimensional benchmarks of nonhydrostatic dynamics with idealized orography closely match those of existing models. Scaling scores will also be presented that highlight the model's computational performance.
  • What about nutrient kinetics in a (gliomatous) brain
    Angelique Perrillat , Université de Poitiers
    martedì 20 novembre 2018 alle ore 14:00, aula Saleri VI piano
    ABSTRACT
    The brain is an organ with high energy needs. While it represents only 2% of the body
    weight it grabs at least 20% of its total energy needs. The consumed energy can come from many
    forms such as glutamate, glucose, oxygen and also lactate. Moreover energy is necessary to support
    neural activity. But because energy management in healthy and tumoral cells can be difficult to
    observe and explain experimentally, we use mathematical modeling to help to describe and
    understand cells energy changes. We present here a time-delayed system and two fast-slow systems
    describing the local mechanisms of interest. We will also compare simulations with MRS and
    litterature data and discuss our results.
  • Bayesian Dynamic Tensor Regression
    Matteo Iacopini , Università Ca’ Foscari di Venezia
    giovedì 8 novembre 2018 alle ore 11:30, aula Saleri VI piano
    ABSTRACT
    Multidimensional arrays (i.e. tensors) of data are becoming increasingly available and call for suitable econometric tools.
    We propose a new dynamic linear regression model for tensor-valued response variables and covariates that encompasses some well known multivariate models such as SUR, VAR, VECM, panel VAR and matrix regression models as special cases.
    For dealing with the over-parametrization and over-fitting issues due to the curse of dimensionality, we exploit a suitable parametrization based on the parallel factor (PARAFAC) decomposition which enables to achieve both parameter parsimony and to incorporate sparsity effects. Our contribution is twofold: first, we provide an extension of multivariate econometric models to account for both tensor-variate response and covariates; second, we show the effectiveness of proposed methodology in defining an autoregressive process for time-varying real economic networks.
    Inference is carried out in the Bayesian framework combined with Monte Carlo Markov Chain (MCMC). We show the efficiency of the MCMC procedure on simulated datasets, with different size of the response and independent variables, proving computational efficiency even with high-dimensions of the parameter space. Finally, we apply the model for studying the temporal evolution of real economic networks.
  • Predator-prey model with competition, the emergence of territoriality
    Alessandro Zilio, Université Paris Diderot
    martedì 30 ottobre 2018 alle ore 15:15, Aula seminari 3° piano
    ABSTRACT
    I will present a series of works in collaboration with Henri Berestycki (PSL), dealing with systems of predators interacting with a single prey. The system is linked to the Lotka-Volterra model of interaction with diffusion, but unlike more classic works, we are interested in studying the case where competition between predators is very strong: in this context, the original domain is partitioned in different sub-territories occupied by different predators. The question that we ask is under which conditions the predators segregate in packs and whether there is a benefit to the hostility between the packs. More specifically, we study the stationary states of the system, the stability of the solutions and the bifurcation diagram, and the asymptotic properties of the system when the intensity of the competition becomes infinite.
  • Material constitutive modeling and parameter calibration: towards identification of representative material properties
    Vladimir Buljak, Department of Strength of Materials, University of Belgrade
    lunedì 29 ottobre 2018 alle ore 14:00, aula Saleri VI piano
    ABSTRACT
    Numerical simulations are used with growing popularity in diverse sectors of engineering. The most important applications are those which attempt to replace expensive experiments on real structures that involve material mechanical behavior beyond their elastic limit. Such circumstance makes strong requirement for formulating material constitutive models with appropriate numerical implementation and for defining protocols for their calibration. Both problems are rather challenging when dealing with advanced materials.
    In order to describe mechanical behavior of materials through an appropriate constitute model experiments are needed, but the transition from measurable quantities to sought parameters cannot always be directly established. Additional difficulty is encountered when dealing with complex constitutive models which tend to capture most of the physical processes taking place during material deforming, resulting in constitutive models with elevated number of parameters. Calibration of such models on the basis of too simple experiments, risks to identify particular solutions only, managing to fit a single experiment, thus not to be treated as material representative properties. A systematic way of resolving these difficulty is through the application of inverse analysis, centered on the minimization of a discrepancy function designed to quantify the difference between measured quantities and their counter parts, computed as a function of sought material parameters. This approach is!
    more and more frequently adopted despite common mathematical difficulties, such as ill-posedness, non-uniqueness of the solution and non-convex function minimization.
    Within this lecture some recent research contributions achieved by our team to the methodology of inverse analysis apt for calibration of complex constitutive models will be given. Results are presented with reference to real life engineering problems, related to diverse industrial environments. The first group of problems considers diagnostic analysis of structures based on instrumented indentation test. Results concern the development of reduced basis model for the acceleration of non-linear elasto-plastic simulations. The second group of problems concerns compaction of ceramic powders and the development of phenomenological constitutive models together with protocols for their calibration. The last group of problems, discussed within the lecture, is related to applications of porous ceramics for diesel particulate filters and catalytic substrates. Some innovative modeling techniques regarding thermally induced cracking and crack healing, observed in these materials will b!e shown.