Tidligere arrangementer - Side 48

John Hosking, CMA, holder et seminar med tittelen: On the realization of jump-diffusion processes

Magnus Dahler Norling will give a second talk on the topic of inverse semigroup C*-algebras associated with left cancellative semigroups.

Salah Mohammed, Uni. Southern Illinois (USA), holder et seminar med tittelen: Linear Stochastic Partial Differential Equations

Peter Friis-Hansen, Det Norske Veritas, skal snakke om

Structuring complex systems using Bayesian network

Magnus Dahler Norling will give a talk with title "Inverse semigroup C*-algebras associated with left cancellative semigroups".

 

Abstract: To each discrete left cancellative semigroup S one may associate a certain inverse semigroup I_l(S), often called the left inverse hull of S. We show how the full and the reduced C*-algebras of I_l(S) are related to the full and the reduced semigroup C*-algebras for S recently introduced by Xin Li, and give conditions ensuring that these algebras are isomorphic. Our picture provides an enhanced understanding of Li's algebras.  

Lateral-torsional buckling of elastic structures under combined loading will be considered in this seminar. This problem has been first reported  in the habilitation thesis of Prandtl dated 1899. Closed-form solutions based on Bessel's functions are available for some specific types of loading. However, numerical methods such as the Finite Element Methods (FEM) or other approximate methods are needed in the general case. More generally, approximation of the buckling curve (limit of the stable domain in the loading parameters space) is investigated from the stationary property of the Rayleigh’s quotient. The approximation is then compared to a numerical approach, namely the iterative method of Vianello and Stodola. Closed-form solutions give upper bounds with relative error less than 0.2%. It is shown that the stable domain of the loading parameter space is convex. The Papkovitch–Schaefer theorem proven in 1934 is extended for this specific problem, despite the nonlinear dependence of the equilibrium equations on the loading parameters for the one-dimensional system. The boundary of the stable domain is clearly nonlinear, but this nonlinearity is weak. It is shown that Dunkerley’s lower bound is relevant for the two structural cases considered, and the maximum relative error induced by such a lower bound is lower than 2%. Prandtl's linear approximation is then validated approximately one century later the pioneer works of Prandtl devoted to elastic instability.

Noël Challamel is Professor at the Department of Civil Engineering (LIMATB), University of South-Brittany, Lorient, France, and Marie Curie fellow at the Department of Mathematics, University of Oslo, Oslo, Norway.

Matthijs Pronk, TU Delft (NL), holder et seminar med tittelen: Malliavin calculus in UMD Banach spaces

The fundamental mechanisms of plasticity in inorganic glasses are distinctly different from those in crystalline metals. Whereas dislocations and their mobility require plasticity in metals, mechanisms responsible for permanent deformation in glasses are to be looked at the atomistic scale. The lecture will deal with this and will involve topics such as for instance constitutive material laws, plasticity theory, dislocation theory, computational mechanics, multiscale analysis, finite element methods, crack modelling, etc.

Vincent Keryvin is professor at  Department of Materials Engineering (LIMATB), University of South-Brittany, Lorient, France.

Simen Rustad (UiO) will give a talk with title  "Construction of Bost-Connes type systems for function fields".

 

Abstract: I will try to indicate how Benoit Jacob's construction of a Bost-Connes  type system for function fields fits into a more general framework.  

Bora Yalkinoglu will give a talk entitled: Introduction to p-adic Bost-Connes systems.

Abstract: In this talk we want to give a gentle introduction into the recently emerging theory of p-adic Bost-Connes systems. In the first part of the talk, after reviewing the necessary background from p-adic analysis and number theory, we will explain recent work of Connes and Consani on certain p-adic representations of the classical BC-system. In the second part of the talk we will discuss recent work on generalizations of the work of Connes and Consani and, further, point out several open problems for further research.  

Oliver Menokeu Pamen, CMA, holder et seminar med tittelen: Computing Greeks without derivatives

Arne Bang Huseby (Matematisk Institutt, Universitetet i Oslo) skal snakke om

A framework for multi-reservoir production optimization

 

Thomas Timmermann, Westfälische Wilhelms-Universität Münster, Germany, will give a talk with title "Towards the dynamical quantum group SU_q(2) on the level of operator algebras"

Nathalie Støer (Matematisk Institutt, Universitetet i Oslo) skal snakke om

Reuse of controls in nested case-control designs with application to a study of prostate cancer and vitamin D

Fred Shultz, Wellesley College (USA) will give a talk with title "Affine automorphisms of the convex set of separable states, and decompositions of separable states".

For simplisielle mengder X og Y gir projeksjonene X x Y -> X og X x Y -> Y fra produktet ned på henholdsvis første og annen faktor opphav til en simplisiell avbildning f : Sd( X x Y ) -> Sd X x Sd Y fra den normale oppdelingen av produktet til produktet av oppdelingene. Vi viser at for endelige simplisielle mengder X og Y er denne en simpel avbildning, det vil si at når vi går over til topologiske rom så er punktinversene |f|^{-1}(p), p element i |Y|, kontraktible. 

Sjur Westgaard (NTNU) skal snakke om

Modelling and forecasting electricity price risk using volatility adjusted quantile regression

In nature, groups of individuals organize globally using only local information. For instance, in a school of fish, there are no external forces to coordinate the group, no leader to guide them. Several mathematical models have been proposed to describe self-organization. In this talk, we will consider two of the most famous models; the Keller-Segel model for bacterial chemotaxis and the Cucker-Smale model for flocking. The emphasis will be on recent mathematical results and remaining open questions. Starting from the microscopic description on particle level, we will discuss the derivation of mesoscopic and macroscopic models at the continuum level. Since the motivation for deriving continuum models is largely numerical, we will also discuss distinct numerical challenges with the resulting models.

The gas pipeline from the Ormen Lange Field to the terminal at Aukra faced several challenges. First, the terrain was very rugged as the route goes through the Storegga slide area where unprecedented long free spans were to be expected. Secondly, the area was believed to have complicated and strong ocean currents. An oceanographic campaign was started in 1999 and lasted to 2007. The presentation will give some background for the measurements, describe the programme and show some results.

Jan Pedersen, Uni. Aarhus, holder et seminar med tittelen:  Stochastic integration on the real line

Erik Vanem (Matematisk Institutt, Universitetet i Oslo) skal snakke om

A Bayesian hierarchical space-time model of significant wave height

Rodwell Kufakunesu, Uni. Pretoria, holder et seminar med tittelen: On Embedded Options - Do We Really Need Jumps And Stochastic Volatility?

Raouf Ghomrasni, AIMS (Cape Town),  holder et seminar med tittelen: A generalized occupation time formula