Causes, consequences and countermeasures of overtaking accidents on two-lane rural roads

Overtaking accidents have one of the most serious consequences of accidents on German rural roads. The aim of this project was to determine the infrastructural and traffic related variables which influence the occurrence and consequences of overtaking accidents as well as the overtaking behavior of drivers. Finally, diverse correlations between operational and infrastructural road characteristics and overtaking accidents and driver behavior were found out and a catalogue of measures had been developed. The given recommendations will have beneficial influences on overtaking behavior and their practice will lead to an increase in safety on two-lane rural roads

Determination of piezo-resistive coefficient π44 in p-type silicon by comparing simulation and measurement of pressure sensors

The piezo-resistive coefficient π44 is reported for the case of single crystalline p-type silicon. By comparing the measured sensitivity of pressure sensors with the simulated sensitivity of these pressure sensors, we are able to extract π44 since this is the only free parameter in the simulation. A value of π44 = (108.3 ± 2.1) × 10−11 Pa−1 at a dopant concentration of (5.0 ± 4.5) × 1017 cm−3 was found, which is in good agreement with experimental literature dat

Berechnung von Matrix-Multiplikationen auf dem PC

Es steht das Problem, ob man nicht für klassische Algorithmen die Eigenschaften des Rechnersystems und/oder des Compilers ausnutzen kann, um die Laufzeit eines Programms zu optimieren. Möglicherweise bringt eine solche Optimierung letztendlich mehr Gewinn als die Implementierung eines neuen Algorithmus. In dieser Arbeit untersuchen wir die Fragen für das Problem der Matrixmultiplikation auf PC-Technik. Dabei werden wir vorhandene Verfahren, insbesondere die Aufrolltechnik, an rechnerspezifische Gegebenheiten anpassen und Einsparungen durch Verringerung der "Hilfsarbeit" anstreben

Carrier mobility in semiconductors at very low temperatures

Carrier mobilities and concentrations were measured for different p- and n-type silicon materials in the temperature range 0.3–300 K. Simulations show that experimentally determined carrier mobilities are best described in this temperature range by Klaassen’s model. Freeze-out reduces the carrier concentration with decreasing temperature. Freeze-out, however, depends on the dopant type and initial concentration. Semi-classical calculations are useful only for temperatures above 100 K. Otherwise quantum mechanical calculations are require

ASi-Sii defect model of light-induced degradation (LID) in silicon: a discussion and review

The ASi-Sii defect model as one possible explanation for light-induced degradation (LID) in typically boron-doped silicon solar cells, detectors, and related systems is discussed and reviewed. Starting from the basic experiments which led to the ASi-Sii defect model, the ASi-Sii defect model (A: boron, or indium) is explained and contrasted to the assumption of a fast-diffusing so-called “boron interstitial.” An LID cycle of illumination and annealing is discussed within the conceptual frame of the ASi-Sii defect model. The dependence of the LID defect density on the interstitial oxygen concentration is explained within the ASi-Sii defect picture. By comparison of electron paramagnetic resonance data and minority carrier lifetime data related to the assumed fast diffusion of the “boron interstitial” and the annihilation of the fast LID component, respectively, the characteristic EPR signal Si-G28 in boron-doped silicon is related to a specific ASi-Sii defect state. Several other LID-related experiments are found to be consistent with an interpretation by an ASi-Sii defect

Development of low-gain avalanche detectors in the frame of the acceptor removal phenomenon

Low-gain avalanche detectors (LGAD) suffer from an acceptor removal phenomenon due to irradiation. This acceptor removal phenomenon is investigated in boron, gallium, and indium implanted samples by 4-point-probe (4pp) measurements, low-temperature photoluminescence spectroscopy (LTPL), and secondary ion mass spectrometry (SIMS) before and after irradiation with electrons and protons. Different co-implantation species are evaluated with respect to their ability to reduce the acceptor removal phenomenon. In case of boron, the beneficial effect is found to be most pronounced for the low-dose fluorine and high-dose nitrogen co-implantation. In case of gallium, the low-dose implantations of carbon and oxygen are found to be beneficial. For indium, the different co-implantation species have no beneficial effect. SIMS boron concentration depth profiles measured before and after irradiation show no indication of a fast movement of boron at room temperature. Hence, the discussed BSi-Sii-defect explanation approach of the acceptor removal phenomenon seems to be more likely than the other discussed Bi-Oi-defect explanation approach