15 Maggio, 2003 16:15

Sezione di Calcolo delle Variazioni ed Equazioni Differenziali

The classical limit of the relativistic Vlasov-Maxwell system in two space dimensions

Hayoung Lee, Max Planck Institute for Gravitational Physics

Aula seminari III piano

abstract

abstract

The motion of a collisionless plasma is modeled by the Vlasov-Maxwell system. Here the speed of light, c, appears as a parameter. First we study the existence of classical solutions of the relativistic Vlasov-Maxwell system with smooth initial data, on a time interval independent of c. Then we show that solutions of the relativistic Vlasov-Maxwell system converge pointwise to solutions of the non relativistic Vlasov-Poisson system as c tends to infinity, at the asymptotic rate of 1/c.

15 Maggio, 2003 17:15

Sezione di Calcolo delle Variazioni ed Equazioni Differenziali

Quasistationary Penrose-Fife Model with Neumann Boundary Conditions.

Anastasia Klepatcheva, Politecnico di Milano

Aula seminari III piano, Dip. di Matematica

abstract

abstract

We study the problem of the existence of a global solution to the quasistationary phase field model of the Penrose-Fife type.
We prove the existence of approximate solutions and obtain a priori estimate.

15 Maggio, 2003 

Sezione di Calcolo delle Variazioni ed Equazioni Differenziali

Quasistationary Penrose-Fife Model with Neumann Boundary Conditions

Anastasia Klepatcheva, Dip. di Matematica Politecnico di Milano

We study the problem of the existence of a global solution to the quasistationary phase field model of the Penrose-Fife type.
We prove the existence of approximate solutions and obtain a priori estimate.

15 Maggio, 2003 

Sezione di Calcolo delle Variazioni ed Equazioni Differenziali

The classical limit of the relativistic Vlasov-Maxwell system in two space dimensions

Hayoung Lee Max Planck, Institute for Gravitational Physics

We study the problem of the existence of a global solution to the quasistationary phase field model of the Penrose-Fife type.
We prove the existence of approximate solutions and obtain a priori estimate.

14 Maggio, 2003 12:30

Seminari di Cultura Matematica

Il sistema solare: un orologio perfetto o una Babele ben mascherata? (I parte)

A. Giorgilli, Univ. Milano Bicocca

aula consiglio VII piano

We study the problem of the existence of a global solution to the quasistationary phase field model of the Penrose-Fife type.
We prove the existence of approximate solutions and obtain a priori estimate.

12 Maggio, 2003 14:30

Seminari di Cultura Matematica

Blackholes vs. naked singularities formation in gravitational collapse: analytical and numerical results and perspectives.

Giulio Magli, Dipartimento di matematica F. Brioschi

aula seminari MOX- 6° piano dip. matem.

abstract

abstract

In 1969 Roger Penrose proposed the so called Cosmic Censorship
conjecture, namely the idea that all gravitating systems
undergoing complete gravitational collapse - such as very massive
stars - should always form blackholes. In other words, the
conjecture states that all singularities eventually forming will
be safely hidden to far-away observers by a event horizon. From
the mathematical point of view the conjecture can be read off as
a characterization of the geodesic motion (governed by o.d.e.) in
a gravitational field assumed to be a solution of the Einstein
field equations (a system of p.d.e.), with the addition of
reasonable physical assumptions. No proof of the conjecture is
available so far, while several examples of physically sound
systems exhibiting naked singularities have been found. In recent
years, the application of techniques coming from non-linear
o.d.e. analysis allowed to construct a new mathematical framework
for censorship experiments which can be used in problems so far
considered unsolvable, such as the gravitational collapse of
barotropic perfect fluids. Parallel, relevant results obtained by
other groups working in the numerical simulation of gravitational
collapse will also be reviewed.

12 Maggio, 2003 16:00

Seminario Matematico e Fisico di Milano

Estimating Unobserved Probability and the Number of Unobserved Outcomes of an Experiment

Chelluri C.A. Sastri, Dalhousie University, Halifax (Canada)

Dipartimento di Matematica e Applicazioni - Università degli Studi di Milano Bicocca - Via Bicocca degli Arcimboldi, 8 - Aula 371

abstract

abstract

Suppose that an experiment with an unknown, possibly infinite, number of outcomes is performed and that these outcomes occur according to some random mechanism. Suppose that n independent trials are carried out and that N distinct outcomes have been observed. We attempt to answer the following questions: What is the probability that, on the next trial, an outcome not observed before occurs? (This is called the problem of unobserved probability.) What is the total number of outcomes not observed? This second problem has a long history going back to Turing and is, apart from its mathematical interest, important in many areas such as biology (species sampling), numismatics, and literary scholarship. We'll give a brief survey of past work and also discuss recent joint work with Alberto Gandolfi in which a Bayes-like estimator for the number of unobserved outcomes is derived. This has the advantage over the existing estimators -- due to Chao and Lee and others -- in that, modulo the fact that Turing's ansatz is used (it is used by everyone else as well), it is derived from first principles, without any ad hoc assumptions, and includes previous estimators as special cases. We'll also briefly discuss an almost complete classification of infinite discrete probability measures, which emerges as a by-product of a solution we have obtained for the problem of unobserved probability.

10 Maggio, 2003 09:30

Seminario Matematico e Fisico di Milano

Presentazione del Corso di Studi in Ingegneria Matematica

Proff. A.Quarteroni, F.Saleri, S.Salsa, P.Secchi, A.Veneziani

Aula S05 (replica ore 11:30 e 14:45, stessa aula)

abstract

abstract

Nota: Il seminario verra ripetuto alle ore 11:30 e alle ore 14:45 .

7 Maggio, 2003 

Sezione di Calcolo delle Variazioni ed Equazioni Differenziali

A variational approach to double-porosity problems

Valeria Chiad•, Piat Dip. di Matematica Politecnico di Torino

Nota: Il seminario verra ripetuto alle ore 11:30 e alle ore 14:45 .

5 Maggio, 2003 11:00

Sezione di Calcolo delle Variazioni ed Equazioni Differenziali

3D Computer Vision and Pattern Recognition: Recent Activities at the VIPS Laboratories

Vittorio Murino, Dip. di Informatica - Univ. degli Studi di Verona

Aula Seminari MOX - 6° piano - Dip. Matematica

abstract

abstract

In this talk, a general overview of the activities carried out at the
Vision, Image Processing and Sound (VIPS) laboratory (Department of
Computer Science, University of Verona, Italy), and the main research
projects in which it is involved will be described.

The laboratory is involved in a broad spectrum of activities, mainly in
the areas of Computer Vision, Pattern Recognition, and Human-Computer
Interaction.

In particular, the talk will focus on the following research topics:

- 3D Computer Vision: 3D data registration and reconstruction, mosaicing,
view synthesis, augmented reality.

- Pattern Recognition: object detection and classification in remote
sensing images, Hidden Markov models for classification and
videosurveillance applications, face recognition.

Depending on the audience interest and the available time, some issues
can be more detailed.

In particular, the lab is working from long time on methods for the
automatic environment reconstruction from multiple 3D images, and in
exploring Hidden Markov Models (HMMs) for 2D shape classification, and
background detection.