In this work, we employed micromechanical techniques on directionally solidified NiAl-Cr prepared at different solidification speeds, to understand the effect of processing conditions and the role of individual phases and interfaces on the deformation behaviour. The observations from the different tests suggest that the interface between the fiber and the matrix dominates the deformation of DS NiAl-Cr eutectic alloys by providing additional mobile dislocation generation sites at the interface.

Metallische Inserts stellen ein alternatives Verbindungskonzept dar, um im Kontext des Multi-Material-Designs (endlos-) faserverstärkte Kunststoffe (FVK) mit metall- oder anderen kunststoffbasierten Bauteilen zu verbinden. Die vorliegende Arbeit beinhaltet die Untersuchung und der daraus resultierende, systematische Vergleich und Bewertung zweier punktförmiger Insertkonzepte. Diese bestehen aus einer geschweißten Referenz und einer gestaltoptimierten, gedrehten Variante. Mechanical fasteners, so-called insert, offer the opportunity to allow for an inexpensive, detachable connection of thin-walled carbon fiber reinforced plastics (CFRP) parts to metal- or other plastic-based structures in the context of multi-material design. The present work is comprised of a systematic comparison of both insert types under near-application load conditions, whereby the strength as well as the damage behavior were evaluated.

In dieser Arbeit werden Antennensysteme für Radar- und Kommunikationssysteme präsentiert. Zusätzlich wird ein QFN Gehäusekonzept erarbeitet. Bei den Antennensystemen für Kommunikationsanwendungen liegt der Fokus auf der Maximierung der abgestrahlten Leistung, um die Reichweite zu erhöhen. Es wird ein neuartiges Konzept zur Leistungskombination von parallelisierten Verstärkern aufgezeigt, bei dem die Signale der einzelnen Verstärker im Antennenelement kombiniert werden. In this work antenna systems for radar- and communication systems are presented. Additionally, a QFN-based packaging concept is evaluated. For communication systems the antenna systems are optimized for maximum radiated power to extend the transmit range. Therefore, a new concept for the power-combination of parallelized amplifiers is presented, where the signals of the amplifiers are combined in a single antenna element.

Dynamisch-mechanische Analyse wird verwendet um die temperaturabhängige, anisotrope viskoelastische Steifigkeit, Schädigungsinduzierte Steifigkeitsdegradation sowie physikalische Alterung von Polypropylen und dem im Fließpressverfahren hergestellten langfaserverstärkten Polypropylen zu untersuchen. Basierend auf Mikro-Computertomographiedaten wird die Approximation linear elastischer Eigenschaften unter Verwendung der Mori-Tanaka-Methode dargestellt. Dynamical mechanical analysis is used to investigate the temperature dependent, anisotropic visco-elastic stiffness, damage induced stiffness degradation as well as physical aging of polypropylene and the anisotropic compression molded long fiber reinforced polypropylene. Based on micro-computer tomography data, the approximations of the linear elastic properties using the Mori-Tanaka method are presented.

A new measurement concept was developed to determine the amount, variability and governing factors of evaporation from the Dead Sea. Additionally, a suitable indirect method to calculate evaporation is presented. Results show that vapour pressure deficit and wind speed are governing evaporation and that the diurnal cycle is determined by three distinct diurnal wind systems. The occurrence frequency and intensity of the wind systems are determined by local differential cooling and heating.

Grating based X-ray phase contrast imaging sets out to overcome the limits of conventional X-ray imaging in the detection of subtle density differences and opens a way to characterize a sample’s microstructure without the need for ultrahigh spatial resolution. The technique relies on grating structures with micrometric periods and extreme aspect ratio – their fabrication by X-ray lithography with optimal structure quality is the topic of this work.

There are thousands of indicators produced to understand and govern our societies. Studies about the way indicators are used in technological innovation are significantly rare, despite the centrality of these decisions to promote growth in our technology-intensive civilization. This book presents what is known and what was discovered in a doctoral research, which analysed innovative business leaders, policymakers and public researchers responsible for technological innovations.

Flow boiling heat transfer, pressure drop and flow pattern of CO₂-POE oil mixtures were experimentally investigated in smooth and micro-fin tubes. The POE oil used features full miscibility in the range of operation investigated. The experimental data was evaluated based on mixture properties, used to evaluate and improve established predictive methods. The knowledge obtained contributes to understanding the influence of oil, which is essential for achieving an efficient evaporator design.

Um das Strom-Spannungs-Verhalten einer Lithium-Ionen-Batterie zu untersuchen und zu verstehen, muss ihre Impedanz im Niederfrequenzbereich analysiert werden. Diese Arbeit behandelt Messung, Modellbildung und Modellvalidierung in diesem Niederfrequenzbereich und führt mit der Verteilungsfunktion der differentiellen Kapazität (DDC) ein neuartiges Werkzeug zur Analyse der Kapazitätsbeiträge unterschiedlicher Partikelgrößen und Partikelarten im Innern einer Lithium-Ionen Batterie ein. In order to understand the current-voltage behaviour of a Lithium-Ion Battery, its impedance needs to be investigated in the low-frequency domain. This work deals with measurement, modelling and model validation in that low-frequency domain and introduces the Distribution-Function-of-Differential-Capacity (DDC) as a new tool for investigating capacity contributions of different particle sizes and particle types inside of a Lithium-Ion Battery.

Die Wartezeit ist maßgeblich für die Bewertung der Verkehrsqualität an Knotenpunkten. Instationarität, also Schwankungen der Verkehrsstärke, ist in den Verfahren zur Wartezeitbestimmung nur teilweise enthalten. In dieser Arbeit wird das Vorkommen unterschiedlicher Arten instationärer Verkehrsstärkeverläufe analysiert, ihr Einfluss auf die Wartezeit mittels mikroskopischer Verkehrsfluss-Simulation untersucht und ein neuer Faktor zur besseren Berücksichtigung innerhalb der Verfahren vorgeschlagen. Vehicle delay is used to assess the level of service for intersections. The impact of non-stationary arrival flow rates has only partly been included in calculation methods. Empirical data is used to show that traffic volume during the peak hour can be distributed in very different forms. A microscopic traffic simulation study is carried out in order to assess their impact on the delay. As a result a new factor is proposed to include non-stationarity more precisely in the calculation of delay.