Böcker utgivna av Cuvillier

The automotive industry is pushing towards highly assisted and even autonomous driving cars. To gather a more precise and reliable representation of the car¿s surroundings, the sensors and the signal processing are improving over time and are a subject to continuous research. One essential sensor is the radar, which is robust and reliable even in harsh environmental conditions. The primary downside of a radar is its low resolution compared to lidar or camera-based systems.To mitigate these drawbacks the resolution of radar systems has to be improved. The bandwidth has to be increased to improve the range resolution, and the aperture has to be increased to improve the angular resolution.Primarily caused by the automotive industry, fully integrated radar on chip solutions are now available and allow the construction of more complex radar systems. These radar on chip devices lay the foundation for radars that fulfill the requirements of increased resolution for future systems.Although this work is focused automotive applications, most ideas, concepts, and calculations are also applicable to other fields. Similar systems may be used in the security sector, quality control in industrial processes, or gesture detection, to name a few examples.This thesis shows the development of a conceptual future radar system for automotive applications. The focus is on providing a large antenna aperture to achieve the required high angular resolution. Two genetic algorithms are developed to optimize the antenna array for a good side lobe level while providing high angular resolution.Two demonstrators are built to implement certain aspects of the proposed radar system and prove the general concept viable. The first demonstrator features a large aperture with a limited side lobe level and is using a modular approach. The modules are synchronized with a radio over fiber system. The second demonstrator uses the previously proposed antenna array, which is implemented with a synthetic aperture radar approach. The system¿s capabilities in a real scenario are demonstrated, and the reconstruction of a high-resolution three-dimensional image from the captured data is shown.As larger arrays for radar systems automatically come with higher manufacturing tolerances, larger thermal expansion, and other negative impacts on the actual antenna positions, this work also analyzes the impact of such imperfections. Additionally, an algorithm is proposed, which can estimate the actual antenna displacement during operation. Therefore, the system is capable of compensating for most of the negative effects.

In 1959 Anderson et. al publish their paper ¿The CAA Doppler Omnirange¿. In that contribution they present their analytically derived receiver¿model for quantifying the bearing error of the Doppler VOR (DVOR) due to multipath propagation. At that time this model exclusively serves for comparing the susceptibility of the DVOR with the one of its precursor which is the conventional VOR. For this purpose, they take the impact of a static omnidirectional scatterer solely upon one signal component into account, which is the frequency modulated one.Due to the number of already installed wind turbines and especially due to the desire to install way more turbines, the signal integrity of the DVOR has become a very timely topic in Germany in the context of renewables energies.In this dissertation Anderson¿s basic generic model is both improved and substantially extended with respect to the impact of wind turbines upon the multipath signal.In the first part of this work Anderson¿s error model is quantitively expended with respect to the relative amplitude of the scattering path. Furthermore, the analytical model is fundamentally improved with respect to quality: For the first time the analytical model allows to take the dynamic effects of wind turbines into account, i.e. both Doppler shifts as well as an additional amplitude modulation due to the scattering object ¿ namely the wind turbine. Additionally, this analysis is carried out for the DVOR¿s reference provided by an amplitude modulated signal component, which has been completely neglected so far by the current state of the art.These analytical models allow for extensive parameter studies, which are applicable e.g. for the validation of both numerical simulation tools as well as approaches by measurements.In the second part of this work the dynamic impact of wind turbines upon the DVOR¿s bearing intelligence is investigated by measurements. This is carried out in an environment scaled with a ratio of 1:144. It utilizes the equipment realized within the projects ¿Sk-ILS¿ and ¿min-Vor-Win¿ and expands it by inventing a procedure for crafting and electromagnetically characterizing voluminous scattering bodies. These allow for a systematic analysis of the impact of terrain topologies.A variety of measurements and the corresponding fundamental analysis address: Doppler shifts and Doppler spectra depending on the orientation of the plane of rotation, the blades¿ shape, revolutions per minute, and the position of the turbines as well as the amplitude and width of Doppler spectra.Fundamental results of this work are e.g.: A 10 km safety¿radius of the DVOR¿s protective area, up to now applied in Germany and as well recommended by the ICAO, can be considered way to restrictive. Furthermore, the receiver settings play a crucial role, when determining the bearing error. Thus, stating the latter makes it mandatory to state the receiver settings as well.

Particularly in the upper stage development of rockets (launchers), gravity dominated fluid motion in upper stage tanks (sloshing) during flight represents an undesired dynamic effect. On the one hand the sloshing forces lead to disturbances, which have to be compensated by the reaction control system. On the other hand, when cryogenic fluids are considered, the fluctuations in tank pressure may be critical under some circumstances compromising the structural stability of the tank. In this field, the utilization of cryogenic propellants represents a high challenge to layout and design of the propulsion components including the propellant tanks.This work deals with two effects that are directly coupled to the sloshing content inside the propellant tank. To investigate these effects a dedicated test setup has been developed. At first, the damping characteristics of sloshing cryogenic nitrogen ¿ which is used as a substitute for the rocket propellants liquid hydrogen and liquid oxygen ¿ are determined. The results are correlated to the theory based on storable propellants. The main part of this work is linked to a characteristic pressure drop inside the propellant tank caused by the sloshing liquid. For the effect to occur, the tank must be pressurized to enable the formation of a thermal stratification below the liquid surface. Sloshing leads to the mixing of liquid in this region with subcooled liquid from the bulk. This affects the decrease of the temperature at the free surface leading to the condensation of superheated vapor. Thus, the pressure in the tank must decreases. Three different pressurization concepts are introduced in this work; self-pressurization where the tank is pressurized by evaporating liquid caused by the heat flowing into the tank. Furthermore, the tank is pressurized with gaseous nitrogen taken from an external gas bottle and at last gaseous helium from an external supply is used for pressurization purpose. By the application of helium as non-condensable gas, a significant reduction of the pressure drop is expected. The experimental results confirm this working hypothesis and therefore support the theoretical considerations described by an approach of Das & Hopfinger.All results are presented in a non-dimensional form to allow the comparison to data from the literature. Furthermore, the upscaling of the current results enables the prediction for future cryogenic upper stages such as the ESC-B for the European space launcher Ariane 5.

A song was presented in the Kaweinag-Asmat language by people living in the south of the Asmat region in Papua in 1984. It conveyed parts of the story of Saunat, one of their mythical heroes. Several years later, a recording of this song served as the source for a research project.A presupposition for this project was the translation of the song-text. In 2007, the place where the recording was made was the locality for the attempt to translate the text. Elaborating a transcription and translating this transcript proved to be far more of a challenge than expected. The difficulties of this work and the uncertainties its results contain will not be concealed. On the contrary, they will become evident in the documentation of this scientific project.The elaborated transcription and translation versions of the song are reproduced in this book.The stories of Saunat belong to the wonderful testimonies of Asmat mythology. They illustrate a socially animating and innovating concept of surmounting dividing lines.

"I find Prof Tagou's book refreshingly captivating, original and above all up-to-date. For the first time with no taboo and no bias, a Cameroonian, scholar hits head-on theories and practices of tribalism in Africa at large and specifically in Cameroon and Ivory Coast and handles them with serenity. The Rotation in High Office Democracy proposal questions in the most ridiculous way countries where the main obstacle to democracy is the mode of power transfer and retention for survival purposes. It is a pragmatic breath of fresh air for our nations bruised by colonialism and prejudice, then for new rulers and their wandering. It is both a solution to the Anglophone crisis and an answer to other ethno-regional problems facing Cameroon, Côte d'Ivoire and some African countries..."Haman Mana, Journalist and Editor in Chief of Le Jour"A piece of Bassa wisdom holds that each tree builds up from its roots. Metaphorically speaking, democracy should be like the earth, universally shared that feeds each tree according to the nature of its soil. Celestin Tagou, in an eloquently relevant style, demonstrates that democracy should benefit from an endogenous appraisal according to the historical, sociological and anthropological diversity of each people. For democracy, he puts forward a theoretically innovating model for diverse societies: Rotation in High Office Democracy."Dr. François Bingono Bingono, Journalist - Lecturer - Anthropologist

Organic electronics are getting more and more interest from industrial companies and research groups in the last years since they enable many new applications, which could not be realized by inorganic materials [1{7]. Flexible displays [1], large-area sensors [1], light-emitting large surfaces [8], printable radio-frequency identification tags (RFID) for packaging or logistic industry [2] and many other systems which require exible, large area and low-cost electronic devices are now developed for the near future or even already commercialized. Organic light-emitting-diode (OLED) displays, for example, are now implemented in portable devices and have higher performance than the traditional LCD displays [9]. OLED displays are self illuminating and do not need back lightening, therefore they have higher brightness, contrast and viewing angle in comparison to LCD displays [9]. Many electronic devices producers implemented OLED displays in their high-end smartphones and SLR cameras [10], and recently LG (a Korean company) introduced a 55-inch OLED television [11]. Large-area solar cells based on organic materials have also found their way to commercialization [12].All of these innovations were only possible after the introduction of organic conductors and semiconductors. Organic (semi)-conductors have the advantage of their low-cost processing technologies (e.g. printing or spray-coating). However, they have lower electrical conductivity, free charge carriers mobility [13] and packaging density than their inorganic counterparts. Therefore they are normally used in lowcost and low-performance applications, except in the case of OLED where they have clear advantages compared with other technologies.In order to produce fully exible devices, elementary devices for electronic circuits (e.g. transistors and diodes) need to be made with exible materials. The performance of these devices needs to be enhanced and their fabrication processes should be optimized to ensure their commercialization as switching elements in OLED displays or in other circuits. These tasks are principally a material issue, that means new materials with higher performance and easier processability are sought after. Most of the work done in this direction is devoted to synthesize new semiconducting materials with higher mobility and solution-processability. Parallel to these investigations, new dielectric materials with good dielectric properties even in thin films, solution-processability and good interface properties to the semiconductors should be developed. Cross-linked polymers are advantageous for organic field-effect transistors (OFETs) because of their electrical and chemical properties, specially their high volume resistivity and their stability towards solvents, acids and bases. This work shows that the application of cross-linked materials can also reduce or even eliminate the use of the volatile organic compounds (VOC), for which legal limitations are yearly augmented.

The stabilization of the carrier-envelope phase of ultrashort laser pulseswent through a rapid development from the first publication of a feasibleconcept in 1999 to being a mature tool for frequency metrology and attosecondscience now. Using this technique, stabilization of the timing between thecarrier wave and the envelope of a laser pulse with residual jitters of only 100attoseconds has become possible. Naturally, the questions arises whether andhow this can be further improved.The current work is devoted to determining the physical mechanisms whichgenerate jitter in carrier-envelope phase stabilization. Furthermore, it is investigatedwhether there is a fundamental limitation to the achievable accuracy.To this end, two methods for removal of technical noise contributions areinitially discussed. Different interferometer topologies are investigated andspurious interferometer noise is reduced by more than 40% using a commonpathlayout. A novel two-detector based carrier-envelope phase retrieval techniquefor amplified laser pulses is demonstrated enabling the circumvention ofthe shot-noise constraint of the conventional extraction method to the maximumextent possible. Next, a novel feed-forward stabilization concept isdeveloped that enables carrier-envelope phase stabilizations with only 20 attosecondresidual timing jitter between carrier and envelope of the laser pulse.This feed-forward method is unconditionally stable against drop-out and permitsthe generation of a train of pulses with identical electric field structurewith no additional measures. As the feed-forward concept widely avoids thetechnical noise sources of the conventional feedback stabilization, the resultingnoise spectra exhibit only two unavoidable residual noise mechanisms: a highfrequencywhite noise floor stemming from shot noise in the carrier-envelopephase detection and a drift-like contribution with 1/f noise characteristics.Finally, the drift-like residual noise mechanism is found to induce phasenoise below the level expected for the conversion of pump laser shot noise intocarrier-envelope phase jitter. A feedback based squeezing, a photon-numbersqueezing process and a quantum non-demolition like conversion are discussedas possible explanations for this striking finding. It is shown that either thefeedback squeezing or the quantum non-demolition process is the probableorigin for the observed sub-shot-noise signatures of the carrier-envelope phasejitter.

The boiling line of diesel fuels is relevant for the combustion in modern engines. Biodiesel shows a boiling behavior that is very different to diesel fuel. To adapt the boiling line, metathesis reactions were carried out. Different products were obtained by varying the catalysts and the ratio of biodiesel to 1-hexene. As 20%-blends in diesel fuel some metathesis products were quite similar to the diesel fuel boiling line. The metathesis fuels were tested regarding interactions with other fuel components and engine oil. Additionally, the material compatibility was in focus. Corrosion effects on copper were within the specification for diesel fuel. Exhaust gas emissions from 20%-blends as well as mutagenicity showed no significant deviations versus diesel fuel.In the result, no significant disadvantages for metathesis fuels were found. However, there production occurs currently only in lab-scale.

Being organized into five chapters, this research detects the utilization of global and regional land use regimes by national bureaucracies. This research identifies domestic political background on utilizing international regimes within specific Indonesian land use change settings, a topic which has to date been neglected in this research field, with a few exceptions. Subsequently, the research poses several sub-questions to break down the main research question, which are as follows:1. What are the bureaucracies and their tasks as well as their legal options to pursue actual and potential interests in steering land use transformation systems in Indonesia?2. How did the domestic bureaucracy, together with international actors, use and adapt national instruments and international support to pursue their own (international and domestic) interests in several cases of land use transformation in Indonesia, such as (a) certification of palm oil and (b) Forest Management Units (FMU) and community forestry (CF)?3. How did the domestic bureaucracy utilize the Association of Southeast Asian Nations¿ (ASEAN) regional forest and environmental regime complex?4. How is the relevance of international and regional regimes used in domestic bureaucratic politics?

The present thesis aimed to investigate the effects of psychological stress on the microbicidal potential of human macrophages in order to shed more light on the mechanisms that underlie stress-induced delays in the progress of wound healing. For this purpose, two studies were conducted. In a first study, we implemented an in vitro assay to assess the microbicidal potential of human macrophages. In a second study, we set out to examine the influence of an acute psychological stressor on the microbicidal potential of human macrophages within a wound paradigm.STUDY IQuantitative and qualitative changes in circulating leukocytes are known to be linked to psychological states. However, there is little information regarding comparable results with leukocytes in peripheral tissues, such as associations between the microbicidal potential of macrophages and psychological states. In this study, we implemented an inexpensive, simple-to-use and valid in vitro method for measuring the microbicidal potential of ex vivo isolated human monocyte-derived macrophages (HMDM).The method was implemented and validated using 21 healthy male subjects (M = 35.0 yrs; SEM = 2.32). The assay principle is based on the reduction of 2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1) by superoxide anions (O2-.), the first in a series of pathogen-killing reactive oxygen species produced by activated macrophages. First, freshly-isolated human monocytes were chemically stimulated to differentiate into macrophages. Subsequently, the HMDM were activated with phorbol 12-myristate 13-acetate to induce a microbicidal or O2- response.The WST-1 macrophage assay induced O2- responses by HMDM in all of the subjects. Furthermore, the WST-1 reduction scores correlated closely with results obtained by a reference method. The findings suggest that the in vitro method implemented investigates the microbicidal potential of ex vivo isolated HMDM in a simple, cost-efficient and valid manner.STUDY IIAcute psychological stress induces changes in circulating blood leukocytes, but its effect on leukocytes in peripheral tissues is largely unknown. Activated tissue macrophages are important in early phases of wound healing, in particular by killing microbes. We hypothesized that (a) acute psychological stress reduces the microbicidal potential of HMDM, and (b) these reductions are related to stress hormone release.Forty-one healthy men (mean age 35 ± 1 yr) were randomized to either the stress (n = 24) or control group (n = 17). While the stress group underwent the Trier Social Stress Test (TSST; combination of mock job interview and mental arithmetic task), controls did not. Assessing the microbicidal potential, we investigated PMA-activated O2- production by ex vivo isolated HMDM immediately before and after stress, and during recovery up to 60 min after TSST / rest. Moreover, we repeatedly measured plasma norepinephrine and epinephrine levels as well as salivary cortisol.The groups differed significantly in their HMDM microbicidal potential (p =.01) in reaction to stress. Post hoc testing revealed that while HMDM of the control group displayed a significant increase in O2- production over time (p =.02), the cells of the stress group did not (p =.83). Immediately and 10 minutes after stress, O2- production by HMDM was lower in stressed subjects as compared to controls (p¿s

The Preliminary Aircraft Design and Optimisation tool, PrADO, is an in-house program of the Institute of Aircraft Design and Lightweight Structures, TU Braunschweig, Germany, which covers a wide range of aspects of aircraft preliminary design. An initial aircraft concept serves as a basis for various analysis modules. Each module is designated to fulfil one special task e.g. aerodynamic analysis, estimation of structural mass, etc. The available methods grouped within those modules range from statistical methods to physics based models. From an aircraft developer¿s point of view PrADO is used within both, the conceptual and the preliminary design phase.The aim of this thesis is to introduce methods and methodologies to aircraft conceptual and preliminary design, more precisely to PrADO, that allow to judge supersonic aircraft concepts. Therefore, the aerodynamic analysis module, the structural analysis module and the propulsion module are extended. An inviscid flow solver is integrated to obtain aerodynamic coefficients. The calculated data serves as input to other analysis modules of PrADO. While the aerodynamic analysis module solely uses the outer geometry of the aircraft, the structural analysis module uses its internal structural layout as additional input to a herein developed finite element model generator. The distribution of secondary mass, fuel loading and payload distributions as well as loads for ground cases and trimmed flight cases are taken from the PrADO database, whereas the aerodynamic forces are calculated by solving the inviscid Euler equations. The model serves as basis for structural sizing and consequently the estimation of structural mass. The purpose of the propulsion module is to size the engine, to calculate the engine performance map and to provide reliable mass data based on the thermodynamic cycle. PrADO provides various models for the analysis of turbojet, turbofan and turboprop engines. It is extended by a turbofan engine with mixed exhaust flow.The verification of the aerodynamic data is solely based on its expected qualitative distribution, since data from higher order methods was not available for the time being. The results compare well with the expected behaviour. The structural sizing process is verified based on an example from literature. The results of the developed sizing algorithm show extraordinary agreement with the reference data. The extended aircraft design process is finally applied to an aircraft from the European research project HISAC. The results compare well with global aircraft data. An excursion into the field of temperature effects in supersonic flight is provided, since no relevant literature is found on the topic with regard to conceptual and preliminary aircraft design. The results are translated into helpful information on thematerial selection process in the stage of aircraft pre-design.Eventually, the tool chain is applied to analyse a supersonic business jet and the results are presented. Based on the results of this basic design, a parameter study is conducted. A combination of cruise Mach number and design range is varied. Global design parameters show expected sensitivity to such variations.