<H4>In:</H4>Intelligent Search on XML Data : Applications, Languages, Models, Implementations, and Benchmarks / Henk Blanken ... [et al.] (eds.)- Berlin : Springer, 2003. - ISBN 3-540-40768-5, S. 59-75

<H4>In:</H4>SIGIR 2003 : proceedings of the 26th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, July 28 to August 1, 2003, Toronto, Canada / edited by Jamie Callan ... - New York, 2003

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The work deals with the task of forecasting motorway traffic states. The data of inductive loop detectors, placed on a large scale German motorway network, are analysed in regard to develop new traffic forecast algorithms. An application is presented that uses the new algorithms in operation for online traffic information.

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This work presents an analysis of the energy structure of carriers enclosed in self-assembled InAs quantum dots. Capacitance-voltage-spectroscopy (CV) with perpendicular magnetic fields is used to identify the energy structure of holes in quantum dots. Applying a two-dimensional harmonic oscillator model, we demonstrate an irregular filling sequence where the d states are occupied with holes before the filling of the p shell is completed. This surprising behavior is explained by a shift in the energy structure in favor of the coulomb repulsion due to the strong interaction in the hole system. We have mapped out the wave functions of electron and hole carriers using CV-spectroscopy with parallel magnetic fields. This allows us to obtain two dimensional plots of the probability densities in k-space for the carriers. The wave functions are interpreted in a quasi particle picture. For the s electrons in quantum dots we obtain Gaussian like probability densities with certain deviations. The wave functions are elongated along [1-10] in direct space. This is caused by a morphological anisotropy of the quantum dots and due to the piezoelectric effect in these structures. The p states show nodal structures with orbitals that are oriented perpendicular to each other. The low energy p states are oriented along [1-10] in direct space. The hole wave functions show an elongation along the perpendicular direction [110] in direct space. This confirms the assumption that the probability distribution is mainly influenced by piezoelectric effects in the strained semiconductor system. Using polarization dependent photoluminescence spectroscopy we demonstrate an energy shift in the interband transitions which indicates an anisotropic confining potential.

Cellular automata (CA) models are quite popular in the field of traffic flow. They allow an effective implementation of real-time traffic computer-simulations. Therefore, various approaches based on CA models have been suggested in recent years. The first part of this thesis focuses on the so-called VDR (velocity-dependent randomization) model which is a modified version of the well known Nagel-Schreckenberg (NaSch) CA model. This choice is motivated by the fact that wide phase separated jams occur in the model. On the basis of random walk theory an analytical approach to the dynamics of these separated jam clusters is given. The predictions are in good agreement with the results of computer simulations and provide a deeper insight into the dynamics of wide jams which seem to be generic for CA approaches and are therefore of special interest. Furthermore, the impact of a localized defect in a periodic system is analyzed in the VDR model. It turns out that depending on the magnitude of the defect stop-and-go traffic can occur which can not be found in the VDR model without lattice defects. Finally, the VDR model is studied with open boundaries. The phase diagrams, obtained by Monte-Carlo simulations, reveal two jam phases with a stripped microscopic structure and for finite systems the existence of a new high-flow phase is shown. The second part of this thesis concentrates on CA models for city traffic with the focus on the Chowdhury-Schadschneider (ChSch) model. In the context of jam clusters the model reveals interesting features since two factors exert influence on the jamming behavior. On the one hand, jams are induced at crossings due to the traffic lights, i.e., cars are forced to stop at a ``red light', and, on the other hand, the dynamics of such induced jams is governed by the NaSch model rules. One part of the investigations covers global (fixed) traffic light strategies. These are found to lead to strong oscillations in the global flow except for the case of randomly switching lights. Furthermore, the impact of adaptive (local) traffic light control is analyzed. It is found that the autonomous strategies can nearly match the global optimum of the ChSch model. In order to provide a more realistic vehicle distribution, the ChSch model is enhanced by a stochastic turning of vehicles and by inhomogeneous densities. Here, the autonomous strategies can outperform the global ones in some cases.

Humboldt-Univ., Diss.--Berlin, 2005. / Literaturverz. S. 209 - 229.

Essen, Universiẗat, Diss., 2002.

Single ion activity coeffients of NaCl, KCl, HCl and CaCl2 in aqueous solution have been estimated by means of ion selective electrode (ISE) potentiometric measurements. Two methods are described for the calibration of the electrodes within the extended Debye-Hückel concentration range, using the Henderson-Bates approximation for the diffusion potential arising at the reference electrode. The consistency of the results indicates that the junction potentials in the examined systems calculated by the Henderson-Bates approximation are of reasonable precision. The published methods and data might be useful to develop single ion parameters for individual ion activity coefficient models.