Adaptive mesh refinement with spectral accuracy for magnetohydrodynamics in two space dimensions

We examine the effect of accuracy of high-order spectral element methods, with or without adaptive mesh refinement (AMR), in the context of a classical configuration of magnetic reconnection in two space dimensions, the so-called Orszag-Tang vortex made up of a magnetic X-point centered on a stagnation point of the velocity. A recently developed spectral-element adaptive refinement incompressible magnetohydrodynamic (MHD) code is applied to simulate this problem. The MHD solver is explicit, and uses the Elsasser formulation on high-order elements. It automatically takes advantage of the adaptive grid mechanics that have been described elsewhere in the fluid context [Rosenberg, Fournier, Fischer, Pouquet, J. Comp. Phys. 215, 59-80 (2006)]; the code allows both statically refined and dynamically refined grids. Tests of the algorithm using analytic solutions are described, and comparisons of the Orszag-Tang solutions with pseudo-spectral computations are performed. We demonstrate for moderate Reynolds numbers that the algorithms using both static and refined grids reproduce the pseudo--spectral solutions quite well. We show that low-order truncation--even with a comparable number of global degrees of freedom--fails to correctly model some strong (sup--norm) quantities in this problem, even though it satisfies adequately the weak (integrated) balance diagnostics.Comment: 19 pages, 10 figures, 1 table. Submitted to New Journal of Physic

Abusive Supervision, Upward Maintenance Communication, and Subordinates\u27 Psychological Distress

This study reanalyzes data from Tepper\u27s (2000) two-wave study regarding the effects of subordinates\u27 perceptions of supervisory abuse to assess previously unexamined relationships. As predicted, we found that subordinates who more rather than less strongly perceived that they had been abused by supervisors tended to use regulative maintenance tactics with higher frequency. Further, the positive relationship between abusive supervision and subordinates\u27 psychological distress was exacerbated by subordinates\u27 use of regulative maintenance communications, and that relationship was reduced by subordinates\u27 use of direct maintenance communication. Theoretical and practical implications are discussed

A Finite Element Method on Convex Polyhedra

Wicke M, Botsch M, Gross M. A Finite Element Method on Convex Polyhedra. Computer Graphics Forum (Eurographics). 2007;26(3):355-364

Finite Elements Method Coupled with Delaunay Triangulation Method Applied on a Silicon Corner Diode

International audienceThis work considers a two dimensional numerical device simulation system using a novel digitizing scheme based on finite elements coupled with the Delaunay triangulation method which allowed an optimal mesh involved in nonrectangular devices as a corner diode. A grid was generated automatically according to the specified device geometry standing on the Delaunay triangulation process. The solution of the problem consists in the resolution of three strong nonlinear partial differential equations (PDE) which are, in occurrence, two dimensional Poisson and continuity equations. Modeled voltage, free carriers distribution and I-V characteristics were extracted when the PN junction resolution was based on second-order Bezier curves. The results are presented using a Delaunay triangulation meshing mathematical tool

Social problem-solving processes and mood in college students: an examination of self-report and performance-based approaches

Previous research has consistently linked poor problem-solving with depression and anxiety. However, much of this research has failed to directly assess real-life problem-solving, relying on self-appraisal or responses to hypothetical problems. This study examined real-life problem-solving in three groups of college students: non-depressed/non-anxious controls; anxious; and mixed depressed/anxious. Participants completed a diary of the interpersonal problems they encountered, and their attempts to solve them. Real-life social problem-solving was also assessed by asking participants to recall past problem solutions. Participants also completed the Social Problem-Solving Inventory-Revised (SPSI-R) and the Mean Ends Problem Solving (MEPS) task. The real-life problem-solving tasks revealed significant differences between the groups, with the mixed depression/anxiety participants exhibiting less effective strategies compared to the control group. However, there were no group differences in MEPS performance, or within the constructive problem-solving style component of the SPSI-R. No deficits were found within the anxious group. Both the anxious and the mixed depressed/anxious groups expressed negative attitudes towards problem-solving. Results have implications for social problem-solving research and suggest that current assessment procedures may be unable to detect impairments in real life problem-solving. Therefore a diary procedure where individuals record their response to the problems they encounter in everyday life may prove a valuable addition to the current battery of assessment procedures