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Schulze H.,South Westphalia University of Applied Sciences
IEEE Transactions on Communications | Year: 2016

The indoor wireless optical communication channel is characterised by the multiple reflections of the light from the surrounding walls. We present a new frequency-domain simulation method for this channel. In contrast to the known time-domain simulation techniques, our method is not restricted to a finite order of reflections. We show that the contributions of an infinite number of reflections can be summed up analytically to a formula that can be handled by standard numerical methods. We illustrate the method by comparing it to the results of previous time domain simulations, and we apply it to the numerical evaluation of some further model scenarios with more than one transmitter. © 2016 IEEE.

Lee-Thedieck C.,Karlsruhe Institute of Technology | Lee-Thedieck C.,Max Planck Institute for Intelligent Systems (Stuttgart) | Lee-Thedieck C.,University of Heidelberg | Rauch N.,South Westphalia University of Applied Sciences | And 5 more authors.
Journal of Cell Science | Year: 2012

In the bone marrow, hematopoietic stem cells (HSCs) reside in endosteal and vascular niches. The interactions with the niches are essential for the maintenance of HSC number and properties. Although the molecular nature of these interactions is well understood, little is known about the role of physical parameters such as matrix elasticity. Osteoblasts, the major cellular component of the endosteal HSC niche, flatten during HSC mobilization. We show that this process is accompanied by osteoblast stiffening, demonstrating that not only biochemical signals but also mechanical properties of the niche are modulated. HSCs react to stiffer substrates with increased cell adhesion and migration, which could facilitate the exit of HSCs from the niche. These results indicate that matrix elasticity is an important factor in regulating the retention of HSCs in the endosteal niche and should be considered in attempts to propagate HSCs in vitro for clinical applications. © 2012. Published by The Company of Biologists Ltd.

Platte F.,IANUS Simulation GmbH | Heise H.M.,South Westphalia University of Applied Sciences
Journal of Molecular Structure | Year: 2014

Over recent years terahertz spectroscopy has become a new tool for the characterization of solid materials, in particular for investigating polymorphism and crystallinity in pharmaceutics. Search strategies have been tested for THz spectra of various organic compounds with their spectra taken from the Riken database (http://www.riken.jp), using the GRAMS spectroscopy software. A subset of the entire database was used, which had been processed by removal of atmospheric water vapour lines and smoothing applied based on Savitzky-Golay convolution or time domain filtering. The spectral range available for all library substances was restricted to an interval from 0.9 to 4.5 THz (30-150 cm-1). The number of vibrational bands within this spectral range is much reduced compared with mid-infrared or Raman spectra. The appropriateness of spectral pre-treatment is demonstrated with regard to reliability and robustness of the search methods. In particular, time-domain filters for smoothing and pre-treatment by the removal of water lines and etalon effects have been successfully tested in combination with least squares and correlation methods. With these insights, applications for substance identification, especially for the pharmaceutical industry, may be enlarged. © 2013 Elsevier B.V. All rights reserved.

Schwung A.,South Westphalia University of Applied Sciences
IEEE International Conference on Automation Science and Engineering | Year: 2015

This paper presents a novel approach to cyber-physical modeling of compression systems. The proposed model covers both physical as well as virtual, i.e. control components. As the modeling framework we employ hybrid automata due to their ability to conveniently handle both continuous and discrete dynamics. Simulation results comparing the proposed model with a complex real world compression system model underline the effectiveness of the approach. © 2015 IEEE.

Schulze H.,South Westphalia University of Applied Sciences
2010 International ITG Workshop on Smart Antennas, WSA 2010 | Year: 2010

We apply the Monte-Carlo simulation model to a frequency selective fading channel including space-variance. This model is suited to simulate the performance of a multi-antenna system for a moving receiver (or transmitter). It takes into account that the time-variance of the channel due to this motion has its origin in the space-variance. We emphasize that for such a channel, time and frequency correlations cannot be separated. ©2010 IEEE.

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