University of Mannheim

About: University of Mannheim is a education organization based out in Mannheim, Germany. It is known for research contribution in the topics: Population & European union. The organization has 4448 authors who have published 12918 publications receiving 446557 citations. The organization is also known as: Uni Mannheim & UMA.

A Multigrid Platform for Real-Time Motion Computation with Discontinuity-Preserving Variational Methods

Abstract: Variational methods are among the most accurate techniques for estimating the optic flow. They yield dense flow fields and can be designed such that they preserve discontinuities, estimate large displacements correctly and perform well under noise and varying illumination. However, such adaptations render the minimisation of the underlying energy functional very expensive in terms of computational costs: Typically one or more large linear or nonlinear equation systems have to be solved in order to obtain the desired solution. Consequently, variational methods are considered to be too slow for real-time performance. In our paper we address this problem in two ways: (i) We present a numerical framework based on bidirectional multigrid methods for accelerating a broad class of variational optic flow methods with different constancy and smoothness assumptions. Thereby, our work focuses particularly on regularisation strategies that preserve discontinuities. (ii) We show by the examples of five classical and two recent variational techniques that real-time performance is possible in all cases--even for very complex optic flow models that offer high accuracy. Experiments show that frame rates up to 63 dense flow fields per second for image sequences of size 160 × 120 can be achieved on a standard PC. Compared to classical iterative methods this constitutes a speedup of two to four orders of magnitude.

Multitasking on FPGA Coprocessors

Abstract: Multitasking on an FPGA-based processor is one possibility to explore the efficacy of reconfigurable computing. Conventional computers and operating systems have demonstrated the many advantages of sharing computational hardware by several tasks over time. The ability to do run-time configuration and readback of FPGAs in a coprocessor architecture allows investigating the problems of implementing realistic multitasking. This paper explores the control software required to support task switching for an application split over the host processor - coprocessor boundary as well as the requirements and features of context saving and restoring in the FPGA coprocessor context. An FPGA coprocessor designed especially to support multitasking of such applications is described.

Determining the effectiveness of prompts for self-regulated learning in problem-solving scenarios

Abstract: Cognitive scientists have studied internal cognitive structures, processes, and systems for decades in order to understand how they function in human learning. In order to solve challenging tasks in problem situations, learners not only have to perform cognitive activities, e.g., activating existing cognitive structures or organizing new information, they also have to set specific goals, plan their activities, monitor their performance during the problem-solving process, and evaluate the efficiency of their actions. This paper reports an experimental study with 98 participants where effective instructional interventions for self-regulated learning within problem-solving processes are investigated. Furthermore, an automated assessment and analysis methodology for determining the quality of learning outcomes is introduced. The results indicate that generic prompts are an important aid for developing cognitive structures while solving problems.

Subexponential distributions and characterizations of related classes

Abstract: LetL(γ),γ≧0, γ≧0, denote the class of distributionsF satisfying $$\mathop {\lim }\limits_{x \to \infty } \bar F^{2*} (x)/\bar F(x) = 2\mathop \smallint \limits_0^\infty e^{\gamma y} dF(y)< \infty$$ (i) $$\mathop {\lim }\limits_{x \to \infty } \bar F^{2*} (x - y)/\bar F(x) = e^{\gamma y} \forall y \in \mathbb{R}.$$ (ii) The classesL(γ), for γ>0, are characterized by means of subexponential densities. As an application we derive a result on the asymptotic behaviour of densities of random sums. In particular for anM/G/1 queue, we relate the tail behaviour of the stationary waiting time density to that of the service time distribution.

The impact of thin-capitalization rules on multinationals' financing and investment decisions

Abstract: This paper analyzes the role of Thin-Capitalization rules for capital structure choice and investment decisions of multinationals. A theoretical analysis shows that the imposition of such rules tends to affect not only the leverage and the level of investment but also their tax-sensitivity. An empirical investigation of leverage and investment reported for affiliates of German multinationals in 24 countries in the period between 1996 and 2004 offers some support for the theoretical predictions. While Thin-Capitalization rules are found to be effective in restricting debt finance, investment is found to be more sensitive to taxes if debt finance is restricted.