Böcker utgivna av Cuvillier

In dieser Arbeit wird eine schiffsbasierte CO2-Transportkette entwickelt und in Hinblick auf einen möglichst geringen Energiebedarf optimiert. Die einzelnen Komponenten der schiffsbasierten CO2-Transportkette werden in Aspen Plus V8.6 modelliert. Für die Verflüssigung von reinem CO2 werden Werte zwischen 7,3 kWh/t CO2 und 14,6 kWh/t CO2 ermittelt. Bei Anwesenheit von typischen CO2-Begleitstoffen aus Post-Combustion- und Oxyfuel-Abscheideprozessen ist der Energiebedarf höher. Für die Injektion von reinem CO2 wird ein Wert von 3,8 kWh/t CO2 für den elektrischen Energiebedarf und ein Wert von 26,5 kWh/t CO2 für den thermischen Energiebedarf ermittelt (Bohrkopfdruck 120 bar). Anschließend wird die entwickelte Transportkette für drei Beispielszenarien mit verschiedenen Transportkapazitäten, Einspeisecharakteristiken und Begleitstoff-Konzentrationen dimensioniert. Für die betrachteten Transportkapazitäten (1 Mt/a bis 20 Mt/a) erscheint der Einsatz von zwei Schiffen bei einer Transportstrecke von 100 km am sinnvollsten. Bei einer Transportstrecke von 1000 km wird für eine Transportkapazität von 20 Mt/a eine größere Anzahl an Schiffen benötigt.

Die Einschlussqualität von Plasmen in toroidalen Magnetfeldern wird maßgeblich durch den turbulenten Transport senkrecht zum Magnetfeld limitiert. Zonalströmungen sind dabei für die Fusionsforschung von großer Bedeutung, da vermutet wird, dass sie mit der Bildung von Transportbarrieren in Zusammenhang stehen. Diese mesoskopischen Scherströmungen tragen auf Grund ihrer Symmetrie nicht zum turbulenten Transport bei und können durch Verscherung von Wirbeln den radialen Transport unterdrücken. Dabei werden Zonalströmungen in einem Selbstorganisationsprozess von der umgebenden Plasmaturbulenz generiert indem Wirbel durch die Zonalströmung verkippt werden, was die Scherströmung weiter antreibt. Ein Maß für die Verkippung ist der sogenannte Reynolds-Stress, wobei der radiale Gradient des Flussflächenmittels die Antriebskraft der Zonalströmung darstellt. Die Dynamik gleicht dabei einer Räuber-Beute-Beziehung, bei der die Driftwellen die Beute für die Zonalströmungen sind. In Fusionsexperimenten konnte beim spontanen Übergang in ein verbessertes Einschlussregime (H-Mode) ein verstärktes Auftreten von Zonalströmungen mit den charakteristischen Räuber-Beute-Oszillationen nachgewiesen werden. Die Rolle und die genaue Wirkungsweise der Zonalströmungen bei dieser Bifurkation des Plasmaeinschlusses sind jedoch ungeklärt. Ein tieferes Verständnis der Physik der Zonalströmungen, speziell in komplexen Magnetfeldgeometrien, ist daher wünschenswert.Diese Arbeit beschäftigt sich vorwiegend mit der Untersuchung des Antriebsmechanismus von Zonalströmungen, im Speziellen mit der Abhängigkeit von der Magnetfeldgeometrie und dem Einfluss der Kollisionalität. Dazu wurden Messungen am Stellarator-Experiment TJ-K durchgeführt, in Plasmen, die dimensional ähnlich zu Randplasmen von Fusionsexperimenten sind. Die relativ geringen Plasmatemperaturen erlauben den Einsatz von Langmuir-Sonden im gesamten Einschlussgebiet. Mit einem poloidalen Sonden Array, bestehend aus 128 Sonden mit je 32 Sonden auf vier benachbarten Flussflächen, können Dichte- und Potentialfluktuationen mit hoher räumlicher und zeitlicher Auflösung gleichzeitig über den gesamten poloidalen Umfang aufgenommen werden.

The present volume draws on the experience of the Summer School held in August 2018 in Split, where graduate students and experienced scholars met from Germany, Albania, Serbia, Macedonia, and Croatia. All contributions discuss small-scale empirical research on the threatened ideals mentioned in the title as desirable and achievable parts of their daily lives as members of modern universities and civil societies.The contributions can also serve as a general model for open and critical international and intercultural academic discourse in joint teaching, research and publishing.

The ongoing diffusion of digital technologies heralds a major change in the mobility domain as it helps to unearth significant opportunities for the reorganization of socio-technical arrangements that have existed for decades. In this light, both scholars and practitioners have begun to investigate the novel opportunities and challenges confronting the mobilitysector. This cumulative thesis, composed of five individual studies, aspires to provide a comprehensive understanding of the transformational impacts of pervasive digital technologies on business models in the mobility sector. Employing a multi-level perspective, this thesis focuses on three main objectives:(1) shedding light on the nature of digitalization and its impacts on business models in general terms, (2) exploring changes in incumbent mobility firms¿ business models in response to the increased diffusion of digital technologies, and (3) examining the potentials of digital technologies to improve value creation and capture in disruptive mobility business models.The findings underline that digitalization is not only concerned with technical aspects but is rather a socio-technical process of applying digital technologies to broader institutional and social contexts. Due to the diversity of technologies and actors involved, digitalization has evolved into an overarching phenomenon that is beyond the control of single actors and affects changes in firms¿ business models through diverse mechanisms. In addition, this thesis describes how incumbent mobility firms adapt their business models in light of consumers¿ changing preferences and how they source the knowledge necessary to develop innovations that build upon hybrid combinations of physical and digital components.Finally, the thesis elaborates on the capacity of digital technologies to facilitate the rise of disruptive mobility business models by improving their attractiveness for both consumers and providers.The crucial success factor is compatibility with the surrounding digital eco-systems, thus rendering it imperative to co-create and co-capture value with diverse actors, including partners, competitors, and customers. From the findings, this thesis derives valuable implications for both research and practice.

This work focuses on the development of AlGaAs-based diode laser (DL) bars optimized for reaching highest powers and efficiencies at low operation temperatures. Specifically, the quasi continuous wave (QCW) pumping of cryogenically cooled Yb:YAG solid-state lasers is targeted, setting requirements on the wavelength (940 nm), the pulse conditions (pulse length 1.2 ms) and frequency (10 Hz) as well as the lowest DL operating temperature THS ~ 200 K, consistent with economic cooling. High fill-factor bars for QCW operation are to reach high optical performance with optical output powers of P 1.5 kW and power conversion efficiencies of ¿E 60% at these power levels. Understanding the efficiency-limiting factors and the behavior at lower temperatures is necessary to design these devices.Optimizations are performed iteratively in three stages. First, vertical epitaxial designs are studied theoretically, adjusted to the targeted operation temperatures and specific laser parameters are extracted. Secondly, resulting vertical designs are processed into low power single emitters and their electro-optical behavior at low currents is experimentally assessed over a wide range of temperatures. The obtained laser parameters characteristic to the vertical design are then used to extrapolate the laser's performance up to the high targeted currents. Finally, vertical designs promising to reach the targeted values for power and efficiency are processed into high power single emitters and bars which are measured up to the highest currents. Eventually, laser bars are fabricated reaching output powers of 2 kW and efficiencies of 61% at 1.5 kW at an operation temperature of 203 K.

Cette étude scrute et compare la manière dont les locuteurs formulent, contextualisent et varient leurs refus selon qu'ils repoussent des demandes d'aide, invitations et offres faites par leurs amis, leurs patrons, leurs professeurs ou des personnes inconnues dans différents types d'échanges verbaux au Cameroun et en France. S'inscrivant dans le cadre de la pragmatique différentielle des français régionaux, l'analyse met en lumière des stratégies mises en oeuvre par les répondants de ces deux espaces francophones pour concilier deux enjeux socio-pragmatiques du refus dans les interactions quotidiennes, à savoir « dire non » et « préserver les faces et les rapports sociaux ». Se fondant sur des données recueillies auprès d'un groupe d'étudiants camerounais et d'un groupe d'étudiants français, l'étude permet de saisir un pan de la réalité des styles interactionnels camerounais et français.

Electrochemical energy conversion technologies are often seen as key components for the transition to an economy that is powered by renewable energy sources. Knowledge-based design and systematic improvement of electrochemical processes is only possible if the underlying reaction kinetics are well understood.This work is based on the hypothesis that a combination of dynamic electrochemical methods, in-operando techniques, and simulations is a feasible and advantageous way towards the determination of electrochemical reaction kinetics. To demonstrate advantages of such a combined approach, four model systems are studied. Differential electrochemical mass spectrometry (DEMS) data and electrochemical data is used to parameterise physical models of the CO and methanol electrooxidation. The second part covers bioelectrochemical reactions. The first DEMS results on acetate oxidation in electrochemically active biofilms are presented, and storage mechanisms for charge as well as substrate are quantified. Furthermore, conversion pathways and rate constants in bioelectrochemical glycerol oxidation are investigated. In conclusion, it is demonstrated that the identification of electrochemical macrokinetics benefits significantly from the application of dynamic techniques, concentration measurements, physical simulation models.

Am 12.11.2014 wurde die Landeeinheit Philae von der Rosetta Sonde abgesetzt und landete auf dem Kometen 67P/Churyumov-Gerasimenko. Beide Raumfahrzeuge erreichten den Kometen im August 2014 als Teil der ESA Rosetta Mission. Nach dem ersten Aufsetzen versagte das Ankersystem, der Lander prallte ab und kam nach drei weiteren Oberflächenkontakten unter einem Kliff zum Liegen. Aufgrund des dortigen Schattens konnten die Akkus nicht aufladen, und der Funkkontakt brach am 15.11.2014 um 00:36 UTC ab. Rosetta blieb für weitere zwei Jahre im Orbit, um die Entwicklung des Kometen zu untersuchen. Diese Arbeit behandelt den Philae Lander, speziell die Messungen mit dem ROMAP Magnetometer. Während des Abstiegs und nach der Landung waren sowohl das Orbiter Magnetometer RPC-MAG als auch das ROMAP Magnetometer gleichzeitig aktiv und ermöglichten simultane Zweipunkt-Messungen. Diese erlaubten es, die niederfrequenten "Singing-Comet" Plasmawellen im Bereich von 5 mHz bis 50 mHz zu analysieren. Die Messungen wurden darüber hinaus verwendet, um die Dynamik des Landers und die Magnetisierung des Kometen während des Abstiegs und des weiteren Flugs zu bestimmen. Aus der Dynamik konnte eine obere Grenze von 800 Pa für die Druckfestigkeit des Oberflächenmaterials des Kometen abgeleitet werden.

BeschreibungDas Gefrieren von Brotteig ermöglicht eine beträchtliche Steigerung der betrieblichen Flexibilität in der Backbranche, jedoch erfolgt dies auf Kosten der Produktqualität.Die während des Einfrierens, der TK-Lagerung und des Auftauens stattfindenden physikalischen und chemischen Veränderungen sind bisher nur zum Teil verstanden. Das erste Ziel der vorliegenden Arbeit bestand darin, eine Methode zur Untersuchung der Mikrostruktur gefrorenen Brotteigs zu entwickeln. Die Methode nutzt die spezifischen Raman-Spektren der Hauptbestandteile gefrorenen Teigs, um ihre jeweilige räumliche Verteilung in den Proben zu ermitteln und entsprechende Bilder zu generieren. Auf den so gewonnenen Bildern stellte sich Eis als kontinuierliches dreidimensionales Netzwerk dar. Außerdem zeigte sich, dass die Bildung größerer Eisblöcke während des Gefrierens durch die Anwesenheit der anderen Teigbestandteile stark limitiert wird.Weizenmehl hat eine komplexe chemische Zusammensetzung, als Ergebnis zahlreicher genetischer sowie Umwelt- und Prozessfaktoren. Das zweite Ziel der Arbeit bestand darin, unter den in der Wertschöpfungskette üblichen analytischen Methoden diejenigen zu identifizieren, die die besten Aussagen zur Eignung der Mehle für TK-Anwendungen geben. Methoden, die die Funktionalität des Glutens sowie die Wasseraufnahme charakterisieren, zeigten sich diesbezüglich als besonders relevant.

BeschreibungThe recent rise of bio-succinic acid as an industrial platform chemical has brought the rumen bacterium Basfia succiniciproducens, a natural producer of this organic acid, into the focus of research. This work investigated the potential of B. succiniciproducens for the production of carbon-three chemicals from sugars. Beside the optimization of improved genetic tools, the C3 chemicals alanine, ß-alanine and 3-hydroxypropionate (3-HP) were targeted. A new alanine producer, B. succiniciproducens ALA-1, exhibited good performance in the bioprocess. The next step demonstrated the proof-of-concept for ß-alanine synthesis using the heterologous expression of aspartate 1 decarboxylase genes from Corynebacterium glutamicum or Vibrio natriegens. The expression of two additional genes enabled the de novo synthesis of up to 100 mg L-1 3-HP from glucose.

BeschreibungCowpea aphid (Aphis craccivora Koch) is a major pest of cowpea, an important African Indigenous Vegetable (AIV) in tropical Africa. Cowpea leaves are a popular delicacy providing daily balanced dietary requirements for millions of people. Synthetic chemicals are first choice management strategy for this pest despite their associated risks of food safety, environmental pollution, and development of resistance by the pest. Consumers are increasingly demanding less use of pesticides and this had led to search of alternative pest management products. This study has identified an environmentally and user entomopathogenic fungi based biopesticide that can be used in the management of A. craccovora in vegetables. The efficacy of cowpea aphid control has been enhanced through incorporation of the biopesticide into a cowpea-maize intercropping system. Use of this biopesticide makes economic sense and can confer yield benefit to farm

The fungus Ashbya gossypii is an important industrial producer of riboflavin, i.e. vitamin B2. Here, we developed and then used a highly sophisticated set-up of parallel 13C tracer studies with labeling analysis by GC/MS, LC/MS, 1D, and 2D NMR to resolve carbon fluxes and obtain a detailed picture of the underlying metabolism in the overproducing strain A. gossypii B2 during growth and riboflavin production from a complex industrial medium using vegetable oil as carbon source. Glycine was exclusively used as carbon-two - but not carbon-one (C1) - donor of the vitamin's pyrimidine ring due to the proven absence of a functional glycine cleavage system. Yeast extract was the main carbon source during growth, while still contributing 8 % overall carbon to riboflavin. Overall carbon flux from rapeseed oil into riboflavin equaled 80 %. Transmembrane formate flux simulations revealed that the C1-supply displayed a severe bottleneck during the initial riboflavin production, which was overcome in later phases of the cultivation by intrinsic formate accumulation. The transiently limiting C1-pool was successfully replenished by time-resolved feeding of formate or serine. This increased the intracellular precursor availability and resulted in a riboflavin titer increase of 45 %. This study is the first that successfully sheds light on carbon fluxes during the growth and riboflavin production phase by use of 13C tracers and a complementary platform of analytical techniques.

Terahertz (THz) technology bears great potential in spectroscopy, imaging, material science, security screening and high-speed wireless communication. However, the generation of intensive, directional THz radiation has been difficult and the THz frequency range has long been considered the last final frontier of the electromagnetic spectrum. Recent advancement in optoelectronic terahertz generation techniques and high power electronic sources has helped to bridge the THz gap and has opened up a wealth of new applications for THz technology. However, there is still a major technical limitation in developing THz systems for mass markets, mainly due to the cost of THz hardware components including sources and detectors.In this regard, we investigated the use of semiconductor diode lasers as THz detectors as well as excitation sources for photomixers for THz generation. For THz detection, we investigated the interaction of semiconductor lasers with THz radiation. Intense THz radiation from different sources and at various frequencies was injected into the laser diode. The laser diode was operated in Littman configuration to ensure clean single mode operation in the near infrared. The charge carrier system in the semiconductor was expected to interact with the injected THz radiation and introduce nonlinear frequency mixing. This nonlinear mixing was to induce sidebands in the near infrared optical spectra and was to be analyzed with an optical spectrum analyzer. This may lead to the demonstration of a simple, cost effective and compact room temperature THz spectrometer since the distance between the emission line and the sidebands equals the incident THz frequency. Unfortunatly, due to unprecedented challenges the interaction of THz radiation with diode laser experiment was not successful.

In this PhD thesis, the flow stability in a laboratory three-dimensional prismatic spouted bed is investigated both experimentally and in CFD-DEM simulations. Liquid is injected in bottom-spray configuration with the aim of a homogeneous distribution of the coating suspension on the whole particle bed. The range of stable spouting is increased by the installation of two parallel draft plates. Nevertheless, the instable spouting regime is found to be advantageous for obtaining a homogeneous coating as the draft plates prevent the mixing in the depth of the apparatus. In addition to the investigations on laboratory scale, the residence time behavior in a continuous pilot scale spouted bed is characterized using a novel tracer method with magnetizable particles. The back-mixing in the apparatus is reduced by the insertion of separation plates with defined transfer geometries.

La Universidad de Ciencias Aplicadas de Schmalkalden se ha involucrado intensamente en los últimos años con instituciones en España para llevar a cabo numerosos proyectos existosos de colaboración que van más allá de los programas de intercambio con universidades españolas, igualmente exitosos.Desde que la crisis económica y financiera afectó especialmente a los estados del sur de Europa, la Universidad de Ciencias Aplicadas de Schmalkalden comenzó a explorar sus posibilidades en Alemania y especialmente en el mercado laboral de Thuringia junto con estudiantes y graduados españoles.La Universidad de Ciencias Aplicadas de Schmalkalden tiene una red multidimensional de socios en España, que incluye universidades y colegios (públicos y privados), pero también Centros de Formación Profesional, escuelas y empresas, así como instituciones políticas. Como resultado, ya se está llevando a cabo una comunicación de múltiples capas, que reúne a diferentes actores en el sistema educativo español a través de la Universidad de Ciencias Aplicadas de Schmalkalden.Como parte del programa "Diálogo universitario con el sur de Europa" del Servicio Alemán de Intercambio Académico (DAAD), todas las instituciones asociadas españolas en Schmalkalden pudieron reunirse en un congreso para ampliar la cooperación actual en proyectos innovadores, lo cual aumenta la empleabilidad de jóvenes académicos. La Facultad de Ciencias Económicas y Empresariales de la Universidad de Ciencias Aplicadas de Schmalkalden ha decidido hacer más atractivos sus programas de estudio, especialmente para universidades, socios y estudiantes de habla hispana. Estos enfoques se desarrollarán aún más con los socios españoles y se vincularán de forma intensiva en la extensa red de socios empresariales e industriales de la Universidad de Ciencias Aplicadas de Schmalkalden.Como resultado concreto de la conferencia en Schmalkalden, debe observarse una nueva vinculación de los programas de estudio entre las universidades asociadas españolas y la Hochschule Schmalkalden.

The present volume draws on the experience of the Workshop held in Benin City, Nigeria in May 2018, where doctoral students and experienced mentors met to work on their journal articles from a simple abstract or a first draft to a concrete publication proposal. Since research articles are the most important academic texts in academic careers today, young African scholars must practice to choose current topics, to use appropriate methodologies and argumentation structures, to draw tentative conclusions, and to be aware of limitations and further research necessary in their field. Mentors can advise them to apply proper statistical procedures, to edit their texts carefully and to submit them in acceptable format to appropriate journals.The contributions can also serve as a general model for open and critical international and intercultural academic discourse on publishing research articles in international journals.

The miniaturisation of bioreactors to the microliter-scale and the integration of online sensors for monitoring the most important process variables during the cultivations is a promising approach for the screening and optimization of cultivation and biocatalysis processes, enabling information-rich, parallelised and cost-effective experiments under well-controlled environmental conditions. The main advantages of microbioreactors (MBRs) are minimization of space and reagents, their easy manipulation, and their high-throughput screening potential, which make them very interesting tools to develop bioprocesses.This thesis is focused on the development of MBRs and the sensor integration for monitoring optical density (OD), dissolved oxygen (DO), pH and glucose as well as their validation for different biotechnological applications.On the basis of a developed PDMS-based MBR, a borosilicate glass-based microbubble column-biroeactor (gµBC) (working volume of 60 µL, aeration occurs through a nozzle with Ø =26 µm) was designed and manufactured by wet etching and powder blasting technology. The gµBC proved to have good oxygen transfer capacity, reaching kLa values up to 320 1/h and fast mixing times ¿95 down to 5.5 s when working at a gas superficial velocity uG of 2.25·10-3 m/s. The mixing performance was simulated using a simplified CFD model, and the tracer profile yielded a good qualitative prediction that was comparable to the experimental results, presenting a tolerable deviation of the mixing times. The gµBC was validated as a suitable cultivation screening tool with a batch cultivation of Saccharomyces cerevisiae with the real-time online monitoring of OD and DO.Furthermore, a cuvette-based microbubble column-bioreactor (cµBC) made of polystyrene (working volume of 550 µL, aeration occurs through a nozzle with Ø = 100 µm) was developed and manufactured with online sensors for pH, OD, DO and glucose. The cµBC showed homogeneous mixing of the cultivation medium with ¿95 < 1 s, with high kLa up to 775 1/h at uG of 8.4·10 3 m/s. The applicability of the cµBC for aerobic submerged whole-cell cultivation in batch and chemostat mode was demonstrated with the model organisms S. cerevisiae and Staphylococcus carnosus. In addition, the use of the cµBC for oxygen-dependent (cell-free) biocatalysis was successfully demonstrated with the example of the model enzyme glucose oxidase immobilization on supports to convert glucose via gluconolactone and hydrogen peroxide to gluconic acid in a microfluidic bed bioreactor (µFBR).The characterization of the developed and manufactured MBRs in this work as well as the integration of the online sensors for OD, DO, pH and glucose are now the basis for the future development of a consolidated and parallelisable MBR system for bioprocess development.

The industry of safety-critical and dependable embedded systems calls for even cheaper, high performance platforms that allow flexibility and an efficient verification of safety and real-time requirements. In this sense, flexibility denotes the ability to (online) adapt a system to changes (e.g. changing environment, application dynamics, errors) and the reuse-ability for different use cases. To cope with the increasing complexity of interconnected functions and to reduce the cost and power consumption of the system, multicore systems are used to efficiently integrate different processing units in the same chip. Networks-on-chip (NoCs), as a modular interconnect, are used as a promising solution for such multiprocessor systems on chip (MPSoCs), due to their scalability and performance. Hence, future NoC designs must face the aforementioned challenges.For safety-critical systems, a major goal is the avoidance of hazards. For this, safety-critical systems are qualified or even certified to prove the correctness of the functioning under all possible cases. A predictable behavior of the NoC can help to ease the qualification process (e.g. formal analysis) of the system. To achieve the required predictability, designers have two classes of solutions: isolation (quality of service (QoS) mechanisms) and (formal) analysis. For mixed-criticality systems, isolation and analysis approaches must be combined to efficiently achieve the desired predictability. Isolation techniques are used to bound interference between different application classes. And analysis can then be applied verifying the real-time applications and sufficient isolation properties.Traditional NoC analysis and architecture concepts tackle only a subpart of the challenges-they focus on either performance or predictability. Existing, predictable NoCs are deemed too expensive and inflexible to host a variety of applications with opposing constraints. And state-of-the-art analyses neglect certain platform properties (e.g. they assume sufficient buffer sizes to avoid backpressure) to verify the behaviour. Together this leads to a high over-provisioning of the hardware resources as well as adverse impacts on system performance (especially for the non safety-critical applications), and on the flexibility of the system.In this work we tackle these challenges and develop a predictable and runtime-adaptable NoC architecture that efficiently integrates mixed-critical applications with opposing constraints. Additionally, we present a modeling and analysis framework for NoCs that accounts for backpressure (i.e. full buffers in network routers delaying the progress of network packets). This framework enables to evaluate the performance and reliability early at design time. Hence, the designer can assess multiple design decisions and trade-offs (such as area, voltage, reliability, performance) by using abstract models and formal approaches.

Successful miniaturization of complex electro-optic devices is a prerequisite for bringing quantum optical sensors to work outside optical labs in a real-world application scenario. Monolithic, i.e. chip-scale integration, holds the promise of achieving the highest level of compactness, robustness, and reliability at the lowest production cost possible.This work focuses on modelling, simulation, design, manufacturing, and testing of functional building blocks for photonic integrated circuits. GaAs-based waveguides, NxM multi-mode interference couplers, and electro-optic phase modulators were developed for applications of rubidium precision spectroscopy at 780 nm for the first time. As an example for photonic integrated circuits a monolithic amplitude modulator based on a Mach-Zehnder-interferometer was demonstrated. Further, GaAs-based phase modulators were developed for applications at 1064 nm. For operation at 780 nm single-mode waveguides with an exceptionally small loss of 1.2 dB/cm and phase modulators with an efficiency as large as 16 deg/(Vxmm) were demonstrated.This work additionally advances the experimental methods available to investigate the electro-optic properties of phase modulators: a novel method based on the I&Q-demodulation of time domain modulation signals derived with a heterodyne interferometer does not only provide access to the phase but also to the (residual) amplitude modulation and allows to separate linear from quadratic phase modulation effects. This provides novel experimental insights into the physical effects governing phase modulation. In fact, it is shown that the current understanding according to which carrier-density related effects contribute solely to the linearly of phase modulation is questionable.

In search of an alternative for chemicals and energy from fossil fuels, lignin pyrolysis is experimentally investigated in a circulating fluidized bed. Deviation in pyrolysis behavior of a softwood Kraft lignin and a wheat straw hydrolysis lignin is analyzed by means of char morphology as well as overall yield and composition determination for gas, oil, and char. The influence of catalytically active mineral matter in lignin on the product distribution is investigated. Progressively, the fluidized bed pyrolysis process is modeled semi-empirically considering fluid dynamics, feedstock composition, micro-particle pyrolysis reactions and mass balances. The lignin secondary reaction kinetics from oil-to-gas are obtained from the Kraft lignin experimental data and a pyrolysis plant with integrated char and permanent gas combustion is modeled with a flowsheeting tool.

Egon Petri, one of the most admired musicians of his generation, brought the sensibilities of the nineteeth century to his students in the mid-twentieth century. In his youth, his parents' home hosted the likes of Brahms, Tchaikovsky, and Clara Schumann, and he studied with Ferruccio Busoni and other great musicians of the prewar and interwar periods. As a prolific and magisterial pianist, he performed prodigious programs throughout Europe and Russia, both solo recitals and concerts with the great orchestral conductors of the time, before settling in Oakland, California in the United States. With ongoing interest in Petri's life, artistry, and teaching intensified by a re-release of his 1929-1951 recordings, Alfred Kanwischer returned to transcripts of interviews he had conducted with Petri in the period 1960-1962 to create this engaging narrative, replete with treasured memories and extensive direct quotations revealing Petri's charm, humor, and wisdom.The narrative is divided into chapters focusing on Petri's youth, influences, performance artistry, and teaching, with engaging interludes on conductors and "dream pianos." Fans of classical music will find the world revealed in this book fascinating, while pianists and piano teachers will find it useful and inspiring.A facsmile of a booklet detailing Petri's concert repertoire during the period 1892-1929 is also included.

Two novel nanoarchitectures - including the highly branched spikecube exemplified by ß-SnWO4 and the biomimetic nanopeapod manifested in Au@Nb@HxK1-xNbO3 - were put forward for the first time in this dissertation, particularly aiming at enriching the library of pattern designs for sunlight-driven photo(electro)chemical applications. Specifically, ß-SnWO4 spikecubes were entitled on the basis of the peculiar morphology, wherein bundles of nanopillars were self-aligned with quasi-periodicity onto each sharp face of hexahedral cube cores. Moreover, this geometric engineering was particularly carried out on a Scheelite-type (ABO4) ß-SnWO4 crystal with a visible-light-active band gap of 2.91 eV and subtle conduction and valence band positions, endowing the photoexcited electron-hole pairs on ß-SnWO4 with strong reducing and oxidizing power, respectively. Consequently, an outstanding photocatalytic activity in degrading organic dyes was observed for the ß-SnWO4 spikecube with an enhancement more than 150% in comparison with a benchmark visible-light-active WO3 photocatalyst. By contrast, the design of Au@Nb@HxK1-xNbO3 emulates the growth pattern of a natural plant - a peapod -, wherein sub-10 nm core-shell Au@Nb plasmonic bimetallics as the particulate peas seeded discretely inside the unidirectional cavity of the tubular HxK1-xNbO3 semiconductor as the pod. The biomimicry of this configuration endows the Au@Nb@HxK1-xNbO3 nanopeapods with strong light harvesting abilities, wherein the HxK1-xNbO3 nanopod and the Au@Nb nanopeas absorb ultraviolet and visible light via interband transition and surface plasmon resonance, respectively. More importantly, the strong near-field plasmon-plasmon coupling between neighboured Au@Nb nanoparticles allows the Au@Nb@HxK1-xNbO3 nanopeapod absorbing near-infrared light. Last but not least, dye photodegradation and water photoelectrolysis as proofs-of-concept manifested the full-spectrum utilization of diffusive solar energy by the Au@Nb@HxK1-xNbO3 nanopeapod for environmental remediation and fuel generation, respectively.

Low Bond number open capillary channel flows have been shown to exhibit collapsing free surfaces when a critical flow rate is exceeded, a phenomenon that is referred to as choking. As shown in this work, the critical flow rate can be pre-determined with sufficient accuracy for the presented channel geometry when certain boundary conditions are known a priori. The presented model that describes the flow rate limitation of stable liquid flow through the open channel is examined and compared to numerical simulations and experimental studies. In addition, the characteristics of the supercritical domain, in which bubbles are ingested passively into the flow in the channel, are described and a new model for bubble formation via choking is proposed.

BeschreibungDie Dissertation "Risk Assessment of Covered Bonds in the International Secondary Market - An Empirical Analysis" beschäftigt sich mit der Risikobewertung von Covered Bonds im internationalen Sekundärmarkt. Covered Bonds sind verzinsliche Wertpapiere, die von Finanzinstituten emittiert werden und durch Vermögenswerte besichert sind, welche in einem sogenannten Cover Pool zusammengefasst werden. In der großen Mehrheit der Fälle handelt es sich bei diesen Vermögensgegenständen entweder um Hypothekendarlehen oder um Kredite an öffentliche Stellen, wie z. B. Staaten oder sonstige Gebietskörperschaften. Die durch diese Arten von Vermögensgegenständen besicherten Covered Bonds werden dementsprechend als Hypotheken-Covered-Bonds bzw. öffentliche Covered Bonds bezeichnet. Während Covered Bonds in der Vergangenheit häufig generell als nahezu ausfallrisikofrei angesehen wurden, hat sich diese Ansicht bedingt durch die Finanzkrise sowie die sich anschließende Staatsschuldenkrise geändert. Vor diesem Hintergrund wird in dieser Arbeit im Rahmen von empirischen Analysen sowohl für öffentliche als auch für Hypotheken-Covered-Bonds untersucht, welche Faktoren die Höhe der Risikoprämien beeinflussen und es werden diesbezügliche Unterschiede zwischen den beiden Covered-Bond-Arten aufgezeigt.

Coal is a rock composed of organic and inorganic materials, which contains 50% or more than 75% organic material (Fig. 1). The organic matter mostly consists of carbon ©, but is also comprised of hydrogen (H), oxygen (O), sulphur (S) and nitrogen (N). Besides organic matter, coal contains some inorganic compounds (minerals) and water (H2O). Naturally, coal is formed from vegetation that has been consolidated between other rock strata and altered by the combined effects of pressure and heat over millions of years to ultimately form coal seams (World Coal Institute, 200

Der deutsche Strommarkt unterliegt durch den zunehmenden Anteil der Stromerzeugung aus Erneuerbaren Energien einem fundamentalen Wandel. Von zentraler Bedeutung ist der Merit-Order-Effekt, der die Verdrängung konventioneller Stromerzeugung und damit einhergehende Preisminderungseffekte beschreibt. In der vorliegenden Arbeit werden in diesem Zusammenhang grundlegende Preiszusammenhänge des Großhandelsmarktes unter Berücksichtigung der Stromerzeugung aus Wind und Photovoltaik analysiert. Dies erfolgt zum einen über Paneldaten-Modelle, zum anderen werden über Zeitreihenmodelle Kurzfristprognosen erstellt. Dabei werden die folgenden Kernfragen der Arbeit thematisiert: Was ist der aktuelle Stand der wissenschaftlichen Forschung im Bereich Zeitreihenanalyse auf Großhandelsmärkten für Strom? Welche Zeitreihenmodelle weisen die beste Prognosequalität auf? Und: Welche Preiseffekte hat die Stromerzeugung aus Erneuerbaren Energien? Die Beantwortung erfolgt über umfangreiche Literaturanalysen und empirische Studien.

In recent years, Silicon Photomultipliers (SiPMs) developed into mature photon detectors which are chosen in a wide field of applications. However, the dark count rate (DCR) of SiPMs sets strong limitations to such detector systems. This quantity describes the rate at which pulses are generated in the absence of light (dark pulses) and deteriorate the photon counting performance of SiPMs.In the course of the presented research, two innovative characterization methods were developed for the identification and evaluation of the physical effects which underlie the generation of dark pulses in SiPMs.The first method is based on the temperature dependence of the DCR. It allows for the extraction of different contributions to the dark count rate, which (a) depend on the applied voltage, (b) depend on the applied overvoltage and © are quasi-independent of the electric field. The second method is based on the detection and mapping of the light intensity which is emitted by the effect of hot carrier luminescence during the avalanche breakdowns of SiPM micro-cells. This method enables a sub-micro-cell, 2D spatially resolved measurement of the dark count rate within the plane of the active area. In particular, the individual contributions of implantation and radiation induced defects to the DCR were evaluated via this method.The acquired knowledge was used to successfully suppress the dark count rate of KETEK SiPMs down to a level of 40 kHz/mm².

BeschreibungGases have to be specifically mixed with a continuous liquid phase to perform a reaction with high yield and selectivity. The time scales of mixing are determined by the transport processes in the boundary layer close to the phase boundary and by bubble swarm turbulence. For clarification of the local mass transfer in bubbly flows, an experimental setup is developed and successfully used to investigate single rectilinear (spherical), helical (ellipsoid) and irregular rising bubbles with and without chemical reaction. Therefore, the time resolved scanning laser induced fluorescence technique is further developed and applied for the first time to bubbly flows to allow new insights in the mass transfer processes.