Adaptive Aggregation Based Domain Decomposition Multigrid for the Lattice Wilson Dirac Operator

In lattice QCD computations a substantial amount of work is spent in solving discretized versions of the Dirac equation. Conventional Krylov solvers show critical slowing down for large system sizes and physically interesting parameter regions. We present a domain decomposition adaptive algebraic multigrid method used as a precondtioner to solve the "clover improved" Wilson discretization of the Dirac equation. This approach combines and improves two approaches, namely domain decomposition and adaptive algebraic multigrid, that have been used seperately in lattice QCD before. We show in extensive numerical test conducted with a parallel production code implementation that considerable speed-up over conventional Krylov subspace methods, domain decomposition methods and other hierarchical approaches for realistic system sizes can be achieved.Comment: Additional comparison to method of arXiv:1011.2775 and to mixed-precision odd-even preconditioned BiCGStab. Results of numerical experiments changed slightly due to more systematic use of odd-even preconditionin

Structure Identification of Dynamical Takagi-Sugeno Fuzzy Models by Using LPV Techniques

In this paper the problem of order selection for nonlinear dynamical Takagi-Sugeno (TS) fuzzy models is investigated. The problem is solved by formulating the TS model in its Linear Parameter Varying (LPV) form and applying a recently proposed Regularized Least Squares SupportVector Machine (R-LSSVM) technique for LPV models. In contrast to parametric identification approaches, this non-parametric method enables the selection of the model order without specifying the scheduling dependencies of the model coefficients. Once the correct model order is found, a parametric TS model can be re-estimated by standard methods. Different re-estimation approaches are proposed. The approaches are illustrated in a numerical example

Prototypical Implementation of an Intermediary Platform for Context-Sensitive Mobile Marketing Applications

The mobile online medium (i.e. mobile data communication) allows the creation of context-sensitive Mobile Marketing applications by using identity- and context information and thereby enabling the efficient targeting of current user needs. However, existing concepts/implementations do not address the impacts of identity- and context information integration to marketing intermediary platforms which connect mobile users and advertisers. Therefore, this paper describes the latter impacts and documents how they can be considered when designing and implementing of a prototypical Mobile Marketing intermediary platform. Besides showing the feasibility of the concept, the foundation for conducting empirical research (e.g. user acceptance tests) about the young field of context-sensitive Mobile Marketing is provisioned

Aggregation-based Multilevel Methods for Lattice QCD

In Lattice QCD computations a substantial amount of work is spent in solving the Dirac equation. In the recent past it has been observed that conventional Krylov solvers tend to critically slow down for large lattices and small quark masses. We present a Schwarz alternating procedure (SAP) multilevel method as a solver for the Clover improved Wilson discretization of the Dirac equation. This approach combines two components (SAP and algebraic multigrid) that have separately been used in lattice QCD before. In combination with a bootstrap setup procedure we show that considerable speed-up over conventional Krylov subspace methods for realistic configurations can be achieved.Comment: Talk presented at the XXIX International Symposium on Lattice Field Theory, July 10-16, 2011, Lake Tahoe, Californi

Google Wave

Wird die Wissenschaft mit dem 'E-Mail 2.0' ganz neu funktionieren? Ist alles nur ein Hype? Ich werde in meinem Vortrag einige Funktionen und Einsatzmöglichkeiten von Google Wave für Bibliotheken zeigen. Schließlich werde ich einige Ideen anreissen, welche Dienstleistungen Bibliotheken mit der neuen Technologien anbieten könnten