Events
We plan to have two types of events.
A twice termly zoom seminar.
Some in person two day workshops (first to be held in Warwick 12-13 December).
The zoom seminar will start in January 2023. Please sign up to our mailing list or send us an email to receive the link.
Zoom Seminar Schedule:
The term 2, 23/24 seminars are:
17th January: Lorenzo Pareschi
Title: A kinetic and mean-field perspective on metaheuristic optimization
Abstact: Metaheuristic optimization based on multi-agent dynamics has a long history and plays a pivotal role today in many applications, ranging from machine learning to optimal control. In this talk, we will show how the use of kinetic and mean-field techniques enables a rigorous mathematical formulation of such algorithms and permits to prove convergence to the global minimum under mild assumptions on the objective function. In particular, we will focus on analyzing some of the most popular algorithms, such as simulated annealing, genetic algorithms and particle swarm optimization.26
2626th February - Ewelina Zatorska
Past seminars:
Tuesday 21st February 15h
Speaker Michele Coti Zelati
Title: Orientation mixing in active suspensions
Abstract:
We study a popular kinetic model introduced by Saintillan and Shelley for the dynamics of suspensions of active elongated
particles. We focus on the linear analysis of incoherence, that is on the linearized equation around the uniform distribution, in the
regime of parameters corresponding to spectral (neutral) stability. We show that in the absence of rotational diffusion, the
suspension experiences a mixing phenomenon similar to Landau damping. We show that this phenomenon persists for small rotational
diffusion, and is combined with an enhanced dissipation at time scale at a faster time scale than the diffusive one.
Friday 27th January 14h
Speaker Michela Ottobre
Title: Non mean-field Vicsek type models for collective behaviour
Abstract: We consider Interacting Particle dynamics with Vicsek type interactions, and their macropscopic PDE limit, in the non-mean-field regime; that is, we consider the case in which each particle/agent in the system interacts only with a prescribed subset of the particles in the system (for example, those within a certain distance). It was observed by Motsch and Tadmore that in this non-mean-field regime the influence between agents (i.e. the interaction term) can be scaled either by the total number of agents in the system (global scaling) or by the number of agents with which the particle is effectively interacting at time t (local scaling). We compare the behaviour of the globally scaled and the locally scaled system in many respects; in particular we observe that, while both models exhibit multiple stationary states, such equilibria are unstable (for certain parameter regimes) for the globally scaled model, with the instability leading to travelling wave solutions, while they are always stable for the locally scaled one.
Based on work with with P. Butta', B. Goddard, T. Hodgson, K.Painter.
Monday 22nd May 15h
Speaker: Florian Theil
Title: Justification of kinetic equations
Abstract: We give an overview of past and current efforts to provide mathematically rigorous derivations of kinetic equations from particle systems. The main goal is to explain the conceptual challenges.
19/10 at 4pm our speaker will be Megan Griffin-Pickering from UCL, title: The quasi-neutral limit for Vlasov-Poisson systems.
20/11 at 3pm our speaker will be Avi Mayorcas from Bath - Title: Blow-up criteria for an SPDE model of chemotaxis Abstract: Chemotaxis and related phenomena have been an active area of mathematical research since statistical and PDE models were first proposed by C. Patlak (’53) and E. Keller & L. Segel (’71). They are commonly studied through mean field PDE models and a common feature of these equations is the possibility of finite time blow-up under given model parameters. Recently it was shown that advection by a sufficiently strong relaxation enhancing vector field could suppress this blow up (Kiselev & Xu ’16, Iyer, Zlatos & Xu ’20). In this talk I will discuss new results (obtained with M. Tomašević) regarding criteria for the persistence of blow-up for an SPDE model of chemotaxis with stochastic advection. The noise we cover is of a form recently shown to be almost surely relaxation enhancing (Gess & Yaroslavtsev ’21) and closely related to those studied in recent works by Galeati, Flandoli and Luo.