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Siegen, Germany

The University of Siegen in Siegen, North Rhine-Westphalia, was founded in 1972. 17,500 students were enrolled at the university as of October 2012. Wikipedia.

Budroni C.,University of Siegen | Emary C.,University of Hull
Physical Review Letters | Year: 2014

We show that the quantum bound for temporal correlations in a Leggett-Garg test, analogous to the Tsirelson bound for spatial correlations in a Bell test, strongly depends on the number of levels N that can be accessed by the measurement apparatus via projective measurements. We provide exact bounds for small N that exceed the known bound for the Leggett-Garg inequality, and we show that in the limit N the Leggett-Garg inequality can be violated up to its algebraic maximum. © 2014 American Physical Society. Source

Wickleder C.,University of Siegen
Angewandte Chemie - International Edition | Year: 2011

Bright light! Semiconductor materials are playing an ever-increasing role in optical applications, but the number of systems used is limited. The AZrPS6 class of compounds (A=K, Rb, Cs) shows extremely interesting optical properties (see picture) and could thus smooth the way to the use of more complex materials. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Chubanov S.,University of Siegen
Mathematical Programming | Year: 2012

This paper proposes a strongly polynomial algorithm which either finds a solution of a linear system Ax = b, 0 ≤ x ≤ 1, or correctly decides that the system has no 0,1-solutions. The algorithm can be used as the basis for the construction of a polynomial algorithm for linear programming. © 2011 Springer and Mathematical Optimization Society. Source

Zimmermann M.,University of Siegen
International Materials Reviews | Year: 2012

Over the last decade, it has been shown for a number of metals that failure occurs even beyond the classical fatigue limit. High frequency testing techniques make it possible to conduct fatigue tests up to 10 9 or even 10 11 cycles for various alloys, ranging from aluminium to high strength steels. As a consequence, the characterisation of fatigue life and damage mechanisms at N>10 7 cycles [very high cycle fatigue (VHCF)] has become a major research issue. Fatigue life in this regime is dominated by crack initiation. With the overall strain being in the purely elastic range, microstructural features acting as stress raisers lead to localised and inhomogeneously distributed irreversible deformation. Hence, microstructural discontinuities become the leading features controlling fatigue life at very high numbers of cycles. The present survey will focus on dislocation arrangement, grain orientation, grain size and surface roughening and their implications on the VHCF behaviour for selected virtually defect free metals, thus providing a sound basis for a detailed understanding of the relevant deformation and damage evolution mechanisms. It will also focus on the VHCF behaviour of materials representing a 'transition' between non-defect related damage evolution and defect based crack initiation, thus pointing out the complexity of damage evolution in the VHCF range. In this context, the term defect is limited to hard non-metallic inclusions, which can be found, among others, in high strength steels as well as pores in casting materials, both dominating the VHCF behaviour of these material types. In contrast, second phases, precipitates or intermetallic particles are considered as irregularities of the microstructure and will not be classified as defects. The current review will show that a true understanding of the VHCF behaviour requires a careful differential analysis of the possible microstructural features leading to localised plastic deformation and that not only crack initiation, but also crack growth behaviour analysis is essential to gain a sound basis for a reliable fatigue life prediction. © 2012 Institute of Materials, Minerals and Mining and ASM International Published by Maney for the Institute and ASM International. Source

University of Siegen | Date: 2011-04-12

A communication system for transmitting information via drilling rod linkages includes a drill drive, drilling rod linkages comprising a first drilling rod linkage and at least one second drilling rod linkage. The first drilling rod linkage comprises an electrical line, an upper end and a lower end which comprises a receptacle for a drill head. The second drilling rod linkage comprises at least one electrical line, an upper end and a lower end. A sensor and/or actuator is arranged at the lower end of the first drilling rod linkage and at the drill head and transmits data. A first communication unit and an electronics unit are arranged at a drive end. A further communication unit is arranged at the upper end of the first drilling rod linkage and at the upper and lower ends of the second drilling rod linkage. The first communication unit and the further communication units are radio modules which transmit/receive data.

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