Seminars

Seminars appear in decreasing order in relation to date. To find an activity of your interest just go down on the list. Normally seminars are given in english. If not, they will be marked as Spanish Only.

 

“On the non-local Lazer-McKenna conjecture with superlinear potential under a partial symmetry condition on the domain: Critical and supercritical cases”

Event Date: Mar 25, 2019 in CAPDE, Differential Equations, Seminars

Abstract: “In 1983 A. Lazer and P.J. McKenna conjectured that the Ambrosetti-Prodi type problems have an unbounded number of solutions as a defined parameter grows to infinity. There were not results on this conjecture, other than the one dimensional case, until 2003 by Breuer . In this talk we will see the existence of a family of solutions indexed by a real number for the non-local problem with superlinear potential under a partial symmetry condition on the domain”

Maximizing Covered Area in a Euclidean Plane with Connectivity Constraint

Event Date: Mar 20, 2019 in AGCO, Seminars

Abstract: Given a set of unit disks in the plane and an integer K, the maximum area connected subset problem asks for a subset of K disks covering the maximum area, under the constraint that the area covered by the K disks is connected. This problem is motivated by wireless router deployment and is a special case of maximizing a submodular function under a connectivity constraint.

Understanding physical mixing processes via transfer operator approach

Event Date: Mar 18, 2019 in Dynamical Systems, Seminars

ABSTRACT:  Industrial and chemical mixing processes of various kinds occur throughout nature and are vital in many technological applications.In the context of discrete dynamical systems, the transfer operator approach has been shown as a powerful tools from both theoretic and numerical viewpoint. In this talk, I will use a toy model (i.e., the one dimensional stretch and fold map) as an example to provide a brief introductionon the relationships between the spectral properties of the associated transfer operator and the estimations of the...

Energy flux enhancement, intermittency and turbulence via Fourier triad phase dynamics in the 1-D Burgers equation.

Event Date: Mar 14, 2019 in Mathematical Mechanics and Inverse Problems, Seminars

Abstract: We present a theoretical and numerical study of Fourier space triad phase dynamics in 1-D stochastically forced Burgers equation at Reynolds number Re ≈ 27000. We show that Fourier triad phases over the inertial range display a collective behaviour characterised by intermittent periods of synchronisation and alignment, reminiscent of Kuramoto model (1984) and directly related to shock collisions in physical space. These periods of synchronisation favour efficient energy fluxes across the inertial range towards small scales,...

Progressive Decoupling of Linkages in Optimization with Elicitable Convexity

Event Date: Mar 13, 2019 in Optimization and Equilibrium, Seminars

ABSTRACT:   A method called the Progressive Decoupling Algorithm is described for solving variational inequalities and optimization problems in which a subspace captures “linkages” that can be relaxed.  The approach is inspired by the Progressive Hedging Algorithm in convex stochastic programming and resembles the Partial Inverse Method of Spingarn, but retains more parametric flexibility than the latter.  It is able even to work when mononicity or convexity is not directly present but can be “elicited”.  The role...

Preferential Attachment Random graphs with edge-step functions

Event Date: Mar 13, 2019 in AGCO, Seminars

Abstract: Nowadays, modeling and understanding the evolution and properties of concrete networks are important questions for many areas in the scientific community. The huge amount of data generated these days combined with new computing power allowed us to see concretely how many entities, such as our own society, are organized and connected. These findings naturally motivated the investigation of many models that intended to reproduce the properties observed empirically. In this seminar, in its first moment, we will introduce which kind of...

Well-posedness for viscous compressible fluids with only bounded density

Event Date: Mar 11, 2019 in CAPDE, Seminars

Abstract: In this talk, we consider the well-posedness issue for the barotropic Navier-Stokes equations. We consider initial velocity fields which have (slightly) sub-critical regularity, and initial densities which are (essentially) only bounded; in particular, we can consider densities having discontinuities across an interface. We are able to establish a local in time existence and uniqueness result in any space dimension, generalising previous results due to Hoff. The proof combines a maximal regularity approach with the study of...

Cross-diffusion and entropy in population dynamics

Event Date: Mar 11, 2019 in CAPDE, Seminars

Abstract: In Population dynamics, reaction-cross diffusion systems model the evolution of the populations of competing species with a segregation effect between individuals. For these strongly coupled, often nonlinear systems, a question as basic as the existence of solutions appears to be extremely complex. We introduce an approach based on duality and entropy methods. We prove the existence of weak solutions in a general setting of reaction-cross diffusion systems, as well as some qualitative properties of the solutions. This is a joint...

Fair Auctions with Asymmetrically Informed Bidders

Event Date: Mar 06, 2019 in AGCO, Seminars

Abstract: (With Aranyak Mehta and Uri Nadav) Agents often arrive to auctions with different levels of informations about their own value for the object sold. In such asymmetric settings, it may be optimal to charge different reservation prices to discriminate between bidders. However, it is often infeasible to expressly treat different bidders in the same auction differently, particularly in on-line settings. We characterize optimal nondiscriminatory mechanisms in the presence of informational asymmetries and compares them to the revenue of...

Estimación de variación total y volatilidad en modelos unificados de GARCH-Ito con saltos.

Event Date: Jan 16, 2019 in Seminars, Stochastic Modeling

Estimación de variación total y volatilidad en modelos unificados de GARCH-Ito con saltos. Resumen:   Los modelos discretos de GARCH y continuos de Drift-Difusión son ampliamente utilizados en campos como finanzas y neurociencia. El modelo GARCH-Ito, introducido recientemente por Wang y Kim, superpone un modelo GARCH en tiempos discretos en el modelo de Ito para la volatilidad instantánea. En este trabajo, se propone una metodología conjunta para la estimación de la variación cuadratica para trayectorias con discontinuidades, utilizando...