University of Paderborn

About: University of Paderborn is a education organization based out in Paderborn, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Computer science & Context (language use). The organization has 6684 authors who have published 16929 publications receiving 323154 citations.

Towards a Formal Semantics of UML 2.0 Activities.

Abstract: The new version 2.0 of the Unified Modeling Language (UML) was targeted at improving expressiveness and semantic precision. These developments are particularly evident in activity diagrams which have not only acquired many new features, but a completely new metamodel and semantic foundation. The UML contains some hints that Petri-nets are the inspirational source for the new semantics. In this paper we will investigate how strong the alignment of UML’s activity diagrams to Petri-nets really is. We start by providing a mapping of the basic elements of activity diagrams to Petri-nets and discuss the problems arising when trying to extend this approach to some of the advanced features of activity diagrams, namely exceptions, traverse-to-completion, and streaming. This examination raises several syntactic and semantic questions concerning activities. We conclude that for basic activities, the analogy works pretty well, but for higher-level constructs, no such intuitive connection exists.

Active damping of drive train oscillations for an electrically driven vehicle

Abstract: A problem encountered with electrically driven vehicles are resonances in the drive train caused by elasticity and gear play. Disadvantageous effects caused by this are noticeable vibrations and high mechanical stresses due to torque oscillations. The oscillations can be damped using a control structure consisting of a nonlinear observer to estimate the torque in the gear and a controller, which computes a damping torque signal that is added to the driver's demand. The control algorithm was implemented in the existing motor control unit without any additional hardware cost. The controller was successfully tested in a test vehicle. The resonances can essentially be eliminated. The controller copes satisfactorily with the backlash problem.

Application of an approximate density-functional method to sulfur containing compounds

Abstract: We present the results of an investigation of sulfur containing compounds using a tight-binding (TB) approach, which is a second-order approximation to density-functional theory (DFT). The performance of the so-called self-consistent charge density-functional based TB (SCC-DFTB) method is analyzed via comparison of the results for several molecular properties with other semi-empirical methods as well as with full DFT calculations. We also examine different conformers of the amino acid cysteine in order to estimate the reliability of our method for large-scale biomolecular systems. We find that SCC-DFTB provides, in general, good agreement with full DFT calculations and a similar deviation from experiment.