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.

Automatic text recognition for video indexing

Abstract: Efficient indexing and retrieval of digital video is an important aspect of video databases. One powerful index for retrieval is the text appearing in them. It enables content- based browsing. We present our methods for automatic segmentation and recognition of text in digital videos. The algorithms we propose make use of typical characteristics of text in videos in order to enable and enhance segmentation and recognition performance. Especially the inter-frame dependencies of the characters provide new possibilities for their refinement. Then, a straightforward indexing and retrieval scheme is introduced. It is used in the experiments to demonstrate that the proposed text segmentation and text recognition algorithms are suitable for indexing and retrieval of relevant video scenes in and from a video data base. Our experimental results are very encouraging and suggest that these algorithms can be used in video retrieval applications as well as to recognize higher semantics in video.

Variational optical flow estimation for particle image velocimetry

Abstract: We introduce a novel class of algorithms for evaluating PIV image pairs. The mathematical basis is a continuous variational formulation for globally estimating the optical flow vector fields over the whole image. This class of approaches has been known in the field of image processing and computer vision for more than two decades but apparently has not been applied to PIV image pairs so far. We pay particular attention to a multi-scale representation of the image data so as to cope with the quite specific signal structure of particle image pairs. The experimental evaluation shows that a prototypical variational approach competes in noisy real-world scenarios with three alternative approaches especially designed for PIV-sequence evaluation. We outline the potential of the variational method for further developments.

Coups and Democracy

Abstract: We use new data on coup d’etats and elections to document a striking development: whereas the vast majority of successful coups before 1991 installed durable rules, the majority of coups after that have been followed by competitive elections. We argue that after the Cold War international pressure influenced the consequences of coups. In the post-Cold War era those countries that are most dependent on Western aid have been the first to embrace competitive elections after the coup. Our theory also sheds light on the pronounced decline in the number of coups since 1991. While the coup d’etat has been and still is the single most important factor leading to the downfall of democratic government, our findings indicate that the new generation of coups has been far less harmful for democracy than their historical predecessors.

Regulatory fit and cognitive performance: the interactive effect of chronic and situationally induced self-regulatory mechanisms on test performance

Abstract: Two studies examined the impact of chronic and situational self-regulatory mechanisms on cognitive test performance. In both studies, test performance was enhanced when situationally induced regulatory mechanisms matched the chronic self-regulatory focus of the test taker. These results support the regulatory fit hypothesis put forward in regulatory focus theory and point to the importance of compatibility between chronic and situationally induced self-regulatory states when it comes to cognitive test performance. Copyright © 2006 John Wiley & Sons, Ltd.

System Dynamics as a Structural Theory in Operations Management

Abstract: The purpose of the paper is to demonstrate the usefulness of (1) system dynamics as a structural theory for operations management and (2) system dynamics models as content theories in operations management. The key findings are that, although feedback loops, accumulation processes, and delays exist and are widespread in operations management, often these phenomena are ignored completely or not considered appropriately. Hence, it is reasoned why system dynamics is well suited as an approach for many operations management studies, and it is shown how system dynamics theory can be used to explain, analyze, and understand such phenomena in operations management. The discussion is based on a literature review and on conceptual considerations, with examples of operations management studies based on system dynamics. Implications of using this theory include the necessary re-framing of some operations management issues and the extension of empirical studies by dynamic modeling and simulation. The value of the paper lies in the conceptualization of the link between system dynamics and operations management, which is discussed on the level of theory.