Dipartimento di Matematica e Informatica https://old.dmi.unife.it These are the search results for the query, showing results 21 to 35. Mathematical and numerical analysis of non-standard mathematical models for flow in porous media -- Iuliu Sorin Pop (Hasselt University) https://old.dmi.unife.it/it/eventi/tba-iuliu-sorin-pop-hasselt-university Seminario di: Analisi Matematica  

Commonly used models for flow in porous media assume that quantities like saturation, phase pressure differences, or relative permeability are related by monotone, algebraic relationships. These relationships are determined experimentally, assuming that the involved quantities have reached a local equilibrium. Under such assumptions, the solutions of the resulting mathematical models have properties like stability in various norms, and satisfy the maximum principle. In particular, such standard models rule out effects like saturation overshoot or the formation of finger profiles, which have been evidenced experimentally. This contradiction is the main motivation when considering non-standard models, where dynamic effects and hysteresis are included in the above mentioned relationships. The resulting models are nonlinear evolution systems of (pseudo-)parabolic and possibly degenerate equations, and may involve differential inclusions. In this contribution we discuss the behaviour of the solutions to such models based on the travelling wave analysis, and analyze different numerical schemes (multipoint flux approximation, discontinuous Galerkin) for approximating the solutions. In particular, we present the rigorous convergence analysis of the numerical solution to the weak solution of the model. Also, we analyze different linear iterative methods for approximating the numerical solution to the nonlinear, fully discrete problems encountered at each time step.
Joint work with C.J. van Duijn, K. Mitra (Eindhoven University of Technology), X. Cao (York University), S. Karpinski (ESPRiT Engineering GmbH), F.A. Radu (University of Bergen), S. Lunowa (Hasselt University).

 

 

]]> No publisher Brasco Lorenzo seminario 2019-01-08T15:50:13Z Evento One dimensional optimal reinforcements of elastic structures - Giuseppe Buttazzo (Pisa) https://old.dmi.unife.it/it/eventi/one-dimensional-optimal-reinforcements-of-elastic-structures-giuseppe-buttazzo-pisa Seminario di: Analisi Matematica Il problema che si intende studiare è quello del rinforzo di una membrana elastica, fissata al bordo, mediante una struttura unidimensionale. Il risultato principale è l'esistenza di un rinforzo ottimo nella classe degli insiemi unidimensionali connessi di lunghezza totale prefissata. La struttura ottima può presentare zone di molteplicità, cioè in cui possono esserci sovrapposizioni. Questo viene mostrato anche da alcune simulazioni numeriche, che illustrano la crescente complessità delle strutture ottime al crescere della lunghezza totale.

]]> No publisher Stumbo Fabio seminario 2018-01-25T10:58:46Z Evento Lagrangian numerical schemes for continuum mechanics https://old.dmi.unife.it/it/eventi/lagrangian-numerical-schemes-for-continuum-mechanics Online seminar on Google Meet platform. The behavior of a continuum is mathematically described by systems of nonlinear hyperbolic partial differential equations (PDE). Both fluids and solids are modelled by balance laws which are based on first physical principles like conservation of mass, momentum and total energy. A wide range of applications are involved in continuum mechanics, such as environmental and meteorological flows, hydrodynamic and thermodynamic problems, plasma flows as well as the dynamics of many industrial and mechanical processes, namely high energetic interactions of metals involving fluidization, melting and solidification in metallurgy, complex flows like granular flows and flows of viscoplastic fluids (yield stress fluids), which exhibit properties of both elastic solids and viscous fluids. The numerical solution of the discrete governing equations constitutes nowadays a challenging task, thus being a very active research field in the context of applied mathematics. Lagrangian algorithms, in which the computational mesh moves with the material velocity, have become very popular in the last decades due to the excellent properties achieved by these numerical methods in the resolution of moving material interfaces and contact waves. Since the computational mesh is moving with the local fluid velocity, Lagrangian methods are typically affected by much less numerical dissipation compared to classical Eulerian approaches on fixed grids, hence obtaining a more accurate approximation of the solution.
This series of lectures aims at introducing the governing equations for continuum mechanics and at providing an overview of the state-of-the-art numerical methods for the numerical solution of the PDE in the Lagrangian framework.

Date
1st – 3rd December 2020.
Venue
Online seminar on Google Meet platform.
Registration and contacts
Please register by email to walter.boscheri@unife.it before 15th November 2020.
Note
PhD students will be granted 1 CFU for attending the entire series of lectures.

Program
1st December, 9:00 – 11:00 am
Governing equations and models for continuum mechanics Ilya Peshkov
2nd December, 9:00 – 11:00 am
Lagrangian and ALE numerical methods. Raphaël Loubère
3rd December, 9:00 – 11:00 am
ALE and structure-preserving numerical schemes for fluids and solids. Walter Boscheri

 

Locandina

]]> No publisher Rizzati Michele seminario 2020-11-09T08:12:14Z Evento The story of a fish in a turbulent ocean: how to survive and how to return home - Eugene Stepanov (San Pietroburgo) https://old.dmi.unife.it/it/eventi/the-story-of-a-fish-in-a-turbulent-ocean-how-to-survive-and-how-to-return-home-eugene-stepanov-san-pietroburgo Seminario di Analisi Matematica Abstract:

Can a  fish with limited velocity capabilities reach any point in the (possibly unbounded) ocean?  In a recent paper by D. Burago, S. Ivanov and A. Novikov, "A survival guide for feeble fish", an affirmative answer has been given under the condition that the fluid velocity field is incompressible, bounded and has vanishing mean drift. This brilliant result extends some known point-to-point global controllability theorems though being substantially non constructive. We will give a fish a different recipe of how to survive in a turbulent ocean, and show how this is related to structural stability of dynamical systems by providing a constructive way to change slightly a divergence free vector field with vanishing mean drift to produce a non dissipative dynamics. This immediately leads to closing lemmas for dynamical systems, in particular to C. Pugh's closing lemma, saying also that the fish can eventually return home.
Joint work with Sergey Kryzhevich (Nova Gorica and St. Petersburg).

]]> No publisher Stumbo Fabio seminario 2018-01-12T11:50:07Z Evento Convegno "Matematica e Storia" nel Liceo Matematico https://old.dmi.unife.it/it/eventi/convegno-matematica-e-storia-nel-liceo-matematico Il convegno su “Matematica e Storia” è uno dei convegni tematici del progetto “Liceo Matematico”, che secondo le linee guida del progetto, presenta temi interdisciplinari tra matematica e storia, per tutti i cicli di istruzione, rivolti agli insegnanti di scuola e ai ricercatori in didattica e storia della matematica ( https://www.liceomatematico.it/ ). Questa edizione del convegno ha un focus particolare sulle applicazioni della matematica.

 

Organizzato dal Dipartimento di Matematica e Informatica dell’Università di Ferrara, in collaborazione con il Dipartimento di Matematica di Salerno, si svolge nelle giornate del 10 e 11 dicembre 2020 in modalità telematica, e si articola in conferenze e in laboratori.

 

Comitato scientifico: Maria Teresa Borgato, Alessandra Fiocca, Emilia Florio Erika Luciano, Francesco Saverio Tortoriello.

Comitato organizzatore: Maria Teresa Borgato, Maria Giulia Lugaresi, Elisa Patergnani.,

 

Locandina e il programma del convegno.

 

Per iscriversi bisogna compilare l’apposito modulo di Google reperibile al seguente link:

https://docs.google.com/forms/d/1h90yeUYFbSzEcc77QWEwZdQUJZvTiJJkk820deB83Iw/edit

Successivamente verrà inviata una mail con il link per accedere all'aula virtuale di Google Meet.

 

Link per partecipare all'evento in live streaming:

https://stream.meet.google.com/stream/6a8157e2-e448-49a4-a57c-7466074cc1eb

]]> No publisher Rizzati Michele seminario 2020-12-09T20:25:00Z Evento Alcuni Spunti di Matematica Pura per l'Orientamento Nelle Scuole Superiori https://old.dmi.unife.it/it/eventi/alcuni-spunti-di-matematica-pura-per-lorientamento-nelle-scuole-superiori Seminario Fermat su Google Meet Il seminario nasce da un'esperienza personale dello studente Matteo Misurati, il quale si è dedicato ad attività di orientamento nelle classi terminali della scuola secondaria ed ha osservato che spesso in tali attività si tende a dare esempi di matematica applicata per coinvolgere maggiormente gli studenti. Questo però non soddisfa coloro che, come lui, amano la matematica pura. Da qui il desiderio di strutturare un breve percorso che possa essere utilizzato da chiunque per presentare la bellezza della matematica pura.
Siete tutti invitati a partecipare, questo il link di Meet dal quale sarà possibile seguire il seminario.
meet.google.com/tga-cktm-pgx
]]> No publisher Rizzati Michele seminario 2020-11-18T11:43:10Z Evento Alcuni risultati di statica e dinamica per sistemi elasticamente accoppiati di tipo trave-trave e cavo-trave - Claudio Giorgi (Università di Brescia) https://old.dmi.unife.it/it/eventi/alcuni-risultati-di-statica-e-dinamica-per-sistemi-elasticamente-accoppiati-di-tipo-trave-trave-e-cavo-trave-claudio-giorgi-universita-di-brescia Seminario di Fisica Matematica Abstract:

 

Si presenteranno risultati di esistenza dell’attrattore globale per la dinamica asintotica di sistemi meccanici dissipativi costituiti da due travi elastiche estensibili (secondo il modello non lineare di Woinowski-Krieger) o da una trave di W-K ed un cavo (corda vibrante) quando l’accoppiamento elastico è lineare e distribuito lungo la loro lunghezza. Oltre ad un’analisi completa delle soluzioni stazionarie nei due problemi, si evidenzia che per particolari valori dei parametri elastici strutturali sorgono fenomeni di risonanza associati a infinite soluzioni statiche con due o tre modi fondamentali sovrapposti

]]> No publisher Stumbo Fabio seminario 2018-10-30T09:15:55Z Evento Seminario di Geometria Algebrica: Mori Dream Spaces obtained by blowing-up points in projective spaces (Massarenti) https://old.dmi.unife.it/it/risorse/events/seminario-di-geometria-algebrica-mori-dream-spaces-obtained-by-blowing-up-points-in-projective-spaces-massarenti speaker: Alex Massarenti (IMPA, Rio de Janeiro)

title: Mori Dream Spaces obtained by blowing-up points in projective spaces.

abstract:

The goal of the minimal model program is to construct a birational model of any complex projective variety which is as simple as possible in a suitable sense. This subject has its origins in the classical birational geometry of surfaces studied by the Italian school. In 1988 S. Mori extended the concept of minimal model to 3-folds by allowing suitable singularities on them. In 2010 there was a great breakthrough in the minimal model theory when C. Birkar, P. Cascini, C. Hacon and J. McKernan proved the existence of minimal models for varieties of log general type.

Mori Dream Spaces, introduced by Y. Hu and S. Keel in 2002, form a class of algebraic varieties that behave very well from the point of view of Mori's minimal model program. They can be algebraically characterized as varieties whose total coordinate ring, called the Cox ring, is finitely generated.

In addition to this algebraic characterization there are several algebraic varieties characterized by some positivity property of the anti-canonical divisor, such as weak Fano and log Fano varieties, that tourn out to be Mori Dream Spaces. In this talk, I will show how to obtain log Fano varieties and Mori Dream Spaces by blowing-up projective spaces in a certain number of general points.

 


]]> No publisher Foschi Damiano seminario 2014-12-11T16:44:45Z Evento Theory and applications of shearlets - Demetrio Labate (University of Houston - Texas) https://old.dmi.unife.it/it/risorse/events/20151215-seminario-labate Seminario di Analisi Numerica Theory and applications of shearlets - Demetrio Labate (University of Houston - Texas)
Abstract
Several advanced multiscale representations, most notably curvelets and shearlets, were introduced during the last decade to overcome known limitations of wavelets and other traditional methods. In fact, even though wavelets are very efficient to handle signals with point singularities, they are suboptimal when dealing with edges and those distributed singularities which typically dominate multidimensional data. Shearlets, in particular, are specially designed to combine the power of multiscale analysis with ability to handle directional information efficiently. As a result, they offer very useful microlocal properties and optimally efficient representations, in a precise sense, for a large class of  multivariate functions.
In this talk, I will illustrate the construction of shearlet frames and give a brief overview of their sparse approximation properties. Next, I will present and discuss several results illustrating the unique ability of the shearlet transform to provide a precise geometric characterization of singularities. These properties provide the theoretical underpinning for several state-of-the-art applications from signal processing and inverse problems, including data restoration, edge detection and feature extraction.
--
Il seminario, pur di ambito applicativo, include argomenti trasversali di analisi armonica e teoria dell'approssimazione.
]]> No publisher Stumbo Fabio seminario dipartimento 2015-11-24T11:23:18Z Evento Elliptic threefolds - Singularities and non-Kodaira fibres -- Andrea Cattaneo (Università di Parma) https://old.dmi.unife.it/it/risorse/events/20160114-cattaneo Seminario di Geometria Algebrica Abstract.

Kodaira's classification of the singular fibres in an elliptic surface no
longer applies in the case of elliptic threefolds or higher dimensional
elliptic fibrations. In fact, the classification problem of the singular
fibres for a general elliptic fibration is sill open.

In this talk, we want to study the case of threefolds in detail: after
making some examples of non-Kodaira fibres, we will focus on the link
between the fibration and its Weierstrass model and, using some
singularity theory, we will prove a structure result for non-Kodaira
fibres for a class of elliptic threefolds which is much considered in the
applications.

Finally, we will briefly discuss some aspects concerning this
classification problem in general and how it is possible to extend the
previous results (this is still a work in progress).

]]> No publisher Stumbo Fabio seminario 2016-01-04T16:44:52Z Evento Seminario di Analisi Matematica - Non occurrence of the Lavrentiev gap for multidimensional autonomous problems https://old.dmi.unife.it/it/eventi/seminario-di-analisi-matematica-non-occurrence-of-the-lavrentiev-gap-for-multidimensional-autonomous-problems Relatore: Pierre Bousquet (Université Paul Sabatier Toulouse III) NON OCCURRENCE OF THE LAVRENTIEV GAP FOR
MULTIDIMENSIONAL AUTONOMOUS PROBLEMS

PIERRE BOUSQUET

 

We establish that the Lavrentiev phenomenon does not occur for autonomous

problems in the multiple integrals Calculus of Variations, provided that the inte-
grand is convex with respect to the gradient variable. The main novelty is that

no other (artificial) restriction is assumed on the integrand or on the domain. The
core of the proof is based on a new approximation result for a parametric version
of the variational problem.

]]> No publisher Rizzati Michele seminario 2022-02-24T09:59:44Z Evento CalVaFer - Calculus of Variations in Ferrara https://old.dmi.unife.it/it/eventi/calvafer-calculus-of-variations-in-ferrara A two days meeting in Calculus of Variations and PDE's at the University of Ferrara List of Speakers:

 

- Veronica Felli (Milano Bicocca)
- Giuseppe Mingione (Parma)
- Alessandra Pluda (Pisa)
- Berardo Ruffini (Bologna)
- Firoj Sk (Oldenburg)
- Giorgio Tortone (Pisa)
Per maggiori informazioni potete consultare https://sites.google.com/unife.it/calvafer/home-page
Tutti gli interessati sono i benvenuti a partecipare, previa registrazione on-line all'indirizzo sopra indicato.
]]> No publisher Brasco Lorenzo seminario dipartimento convegno 2024-03-05T08:24:54Z Evento Dimension Lifting for Quantum Computation of partial differential equations and related problems https://old.dmi.unife.it/it/eventi/dimension-lifting-for-quantum-computation-of-partial-differential-equations-and-related-problems Seminario Giovedì 7 marzo 2024, ore 16.30

Aula C1 (Palazzo Manfredini)
Shi Jin (Shangai Jiao Tong University)
"Dimension Lifting for Quantum Computation of  partial differential equations and related problems"

Abstract
Quantum computers have the potential to gain algebraic and even up to exponential speed up compared with its classical counterparts, and can lead to technology revolution in the 21st century. Since quantum computers are designed based on quantum mechanics principle, they are most suitable to solve the Schrodinger equation, and linear PDEs (and ODEs) evolved by unitary operators.  The most efficient quantum PDE solver is quantum simulation based on solving the Schrodinger equation. It will be interesting to explore what other problems in scientific computing, such as ODEs, PDEs, and  linear algebra that arise in both classical and quantum systems,  can be handled by quantum simulation.  
We will present a systematic way to develop quantum simulation algorithms for general differential equations. Our basic framework is dimension lifting, that transfers nonlinear PDEs to linear ones, and linear ones to Schrodinger type PDEs. For non-autonomous PDEs and ODEs, or Hamiltonian systems with time-dependent Hamiltonians,  we also add an extra dimension to transform them into autonomous PDEs that have only time-independent coefficients, thus quantum simulations can be done without using the cumbersome Dyson’s series and time-ordering operators. Our formulation allows both qubit and qumode (continuous-variable) formulations, and their hybridizations, and provides the foundation for analog quantum computing.
Biography
Prof. Shi Jin is the Director of Institute of Natural Sciences, and Chair Professor of Mathematics, at Shanghai Jiao Tong University. He is also a co-director of the Shanghai Center of Applied Mathematics. He was department chair and Vilas Distinguished Achievement Professor at University of WisconsinMadison, Chair of Department of Mathematics at Shanghai Jiao Tong University. He received a Feng Kang Prize of Scientific Computing in 2001 and a Morningside Silver Medal of Mathematics at the International Congress of Chinese Mathematicians in 2007. He is an inaugural Fellow of the American Mathematical Society (AMS) (2012), a Fellow of Society of Industrial and Applied Mathematics (SIAM) (2013), an inaugural Fellow of the China Society for Industrial and Applied Mathematics (CSIAM) (2020), and an Invited Speaker at the International Congress of Mathematicians (ICM) in 2018.
]]> No publisher Rizzati Michele seminario dipartimento convegno 2024-03-05T08:18:58Z Evento Come gli animali usano la matematica - A. Foà (Università di Ferrara) https://old.dmi.unife.it/it/eventi/come-gli-animali-usano-la-matematica-a-foa-universita-di-ferrara Seminario Mathesis No publisher Stumbo Fabio seminario 2020-01-15T10:41:09Z Evento Smoluchowski equation in perforamed domains: Homogenization and applications to mathematical models in medicine - Silvia Lorenzani (Politecnico di Milano) https://old.dmi.unife.it/it/eventi/smoluchowski-equation-in-perforamed-domains-homogenization-and-applications-to-mathematical-models-in-medicine-silvia-lorenzani-politecnico-di-milano Abstract:
In recent years, the Smoluchowski equation has been considered in biomedical research to model the aggregation and diffusion of beta-amyloid peptide in the cerebral tissue, a process thought to be associated with the development of Alzheimer's disease. In this work, we study the homogenization of a Smoluchowski system of  discrete diffusion-coagulation equations with non-homogeneous Neumann boundary conditions, defined in a periodically perforated domain through a two scale convergence technique.
]]> No publisher Stumbo Fabio seminario 2018-11-20T08:13:22Z Evento