TY - JOUR A1 - Gutheil, Inge A1 - Berg, Tommy A1 - Grotendorst, Johannes T1 - Performance Analysis of Parallel Eigensolvers of two Libraries on BlueGene/P JF - Journal of Mathematics and Systems Science N2 - Many applications in computational science and engineering require the computation of eigenvalues and vectors of dense symmetric or Hermitian matrices. For example, in DFT (density functional theory) calculations on modern supercomputers 10% to 30% of the eigenvalues and eigenvectors of huge dense matrices have to be calculated. Therefore, performance and parallel scaling of the used eigensolvers is of upmost interest. In this article different routines of the linear algebra packages ScaLAPACK and Elemental for parallel solution of the symmetric eigenvalue problem are compared concerning their performance on the BlueGene/P supercomputer. Parameters for performance optimization are adjusted for the different data distribution methods used in the two libraries. It is found that for all test cases the new library Elemental which uses a two-dimensional element by element distribution of the matrices to the processors shows better performance than the old ScaLAPACK library which uses a block-cyclic distribution. KW - performance analysis KW - Elemental KW - ScaLAPACK KW - eigensolvers KW - Numerical linear algebra Y1 - 2012 U6 - http://dx.doi.org/10.17265/2159-5291/2012.04.003 SN - 2159-5291 VL - 2 IS - 4 SP - 231 EP - 236 PB - David Publishing CY - Libertyville ER - TY - JOUR A1 - Grotendorst, Johannes T1 - Supercomputer programmieren - ein besonderes Studienangebot in Jülich JF - Junge Wissenschaft. 27 (2012), H. 94 Y1 - 2012 SN - 0179-8529 SP - 12 EP - 14 PB - - ER - TY - JOUR A1 - Grotendorst, Johannes T1 - IAS Winter School: Hierarchical Methods for Dynamics in Complex Molecular Systems JF - Innovatives Supercomputing in Deutschland : inSiDE. 10 (2012), H. 1 Y1 - 2012 SP - 104 PB - - ER - TY - BOOK A1 - Timme, Michael T1 - HGB Crashkurs : der sichere Weg durch die Prüfung ; [Gesellschafts- und Wirtschaftsrecht] Y1 - 2012 SN - 978-3-406-63679-0 PB - Beck CY - München ER - TY - BOOK A1 - Timme, Michael T1 - BGB Crashkurs : der sichere Weg durch die Prüfung ; [Fall für Fall durch das Privatrecht]. - 2. Aufl. Y1 - 2012 SN - 978-3-406-63681-3 PB - Beck CY - München ER - TY - JOUR A1 - Timme, Michael T1 - Die Reichweite der "werdenden" Wohnungseigentümergemeinschaft gegenüber dem Zweiterwerb JF - Monatsschrift für Deutsches Recht : MdR N2 - Mit einer aktuellen Entscheidung hat der BGH, Urt. v. 11.5.2012 - V ZR 196/11, MDR 2012, 958 seine Rechtsprechung v. 5.6.2008 - V ZB 85/07 zur Entstehungsphase einer Wohnungseigentümergemeinschaft fortgeführt. In dieser Entscheidung sieht der BGH die Erwerber von Wohnungseigentum als Kostenschuldner gem. § 16 Abs. 2 WEG an, obwohl diese noch nicht im Grundbuch eingetragen sind. Eine andere Rechtslage besteht beim sog. Zweiterwerb. Die Abgrenzung von Erstund Zweierwerb ist aufgrund der völlig unterschiedlichen Rechtsfolgen für die Praxis von großer Bedeutung. Y1 - 2012 U6 - http://dx.doi.org/10.9785/ovs-mdtr-2012-1069 SN - 0340-1812 VL - 2012 IS - 18 SP - 1068 EP - 1071 PB - Verlag Dr. Otto Schmidt CY - Köln ER - TY - BOOK A1 - Grotendorst, Johannes T1 - Hierarchical methods for dynamics in complex molecular systems : IAS Winter School, 5 - 9 March 2012, Forschungszentrum Jülich GmbH ; lecture notes / ed. by Johannes Grotendorst, Godehard Sutmann, Gerhard Gompper, Dominik Marx Y1 - 2012 SN - 978-3-89336-768-9 N1 - (Schriften des Forschungszentrums Jülich IAS Series 10) PB - Forschungszentrum Jülich CY - Jülich ER - TY - GEN A1 - Baumgartner, Thomas A1 - Wunderlich, Florian A1 - Jaunich, Arthur A1 - Sato, Tomoo A1 - Bundy, Georg A1 - Grießmann, Nadine A1 - Kowalski, Julia A1 - Burghardt, Stefan A1 - Hanebrink, Jörg T1 - Lighting the way: Perspectives on the global lighting market Y1 - 2012 CY - McKinsey ET - 2nd ed. ER - TY - JOUR A1 - Olaru, Alexandra Maria A1 - Kowalski, Julia A1 - Sethi, Vaishali A1 - Blümich, Bernhard T1 - Exchange relaxometry of flow at small Péclet numbers in a glass bead pack JF - Journal of Magnetic Resonance (JMR) N2 - In this paper we consider low Péclet number flow in bead packs. A series of relaxation exchange experiments has been conducted and evaluated by ILT analysis. In the resulting correlation maps, we observed a collapse of the signal and a translation towards smaller relaxation times with increasing flow rates, as well as a signal tilt with respect to the diagonal. In the discussion of the phenomena we present a mathematical theory for relaxation exchange experiments that considers both diffusive and advective transport. We perform simulations based on this theory and discuss them with respect to the conducted experiments. KW - NMR exchange relaxometry KW - Low-field NMR Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.jmr.2012.04.015 SN - 1096-0856 VL - 220 SP - 32 EP - 44 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fischer, Jan-Thomas A1 - Kowalski, Julia A1 - Pudasaini, Shiva P. T1 - Topographic curvature effects in applied avalanche modelling JF - Cold Regions Science and Technology N2 - This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients. KW - Snow KW - Avalanche Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.coldregions.2012.01.005 SN - 1872-7441 VL - 74-75 SP - 21 EP - 30 PB - Elsevier CY - Amsterdam ER -