Mathematics Seminars next week

[math]

MATHEMATICS SEMINARS 2010


Tuesday, 20 April, at 14:00


Professor Akhtam A. Dzhalilov
(Samarkand State Uzbekistan)


"Invariant Measures of Circle Homeomorhisms with Singularities"

Abstract:

We study circle homeomorphisms with break points and irrational rotation
number.
We will  formulate our main results on:

1) ergodicity, regularity and singularity properties of preserving
orientation circle homeomorphisms with single break point;

2) absolute continuity and singularity of invariant measures of circle
homeomorphisms with several break points.



Venue: Luigi Stasi Seminar Room (ICTP Leonardo Building, first floor)

***

Wednesday, 21 April, at 14:30

Dr. Andre' Fonseca
(ABC Federal University, Santo Andre, Brazil/ICTP)

A Prototype of Complex Systems: A Piecewise-smooth Mechanical Oscillator

Abstract:

In this talk we are interested in classical vector fields which are not 
required to be continuous everywhere, that is, defined by 
piecewise-smooth maps. To perform a qualitative analysis of the phase 
portraits of a class of discontinuous vector fields, identifying 
algebraical and topological features for the so called escaping and 
sliding regions, has been the goal of several researchers, mainly in 
Control theory, where the discontinuous oscillations phenomena have been 
modeled by the introduction of discontinuities in semi-linear vector 
fields, using sign functions. Those systems are called relay systems and 
they have gain great importance to understand the discontinuous behavior 
and the interesting phenomena that can be observed. We will analyze a 
system composed of a block connected to a fixed linear-elastic
spring on a moving conveyor belt, subject to Coulomb friction.

Venue: Luigi Stasi Seminar Room (ICTP Leonardo Building, first floor)