This dissertation introduces an implantable LED microdisplay in the aim of returning a certain ability to see to blind people. The microdisplay is the basic device of the intraocular vision aid (IoVA) an implant developed for those whose cornea of the eye is considerably blurred due to accident or illness. This microdisplay consists of a LED-array which is connected to a CMOS driver circuit. By means of activating each pixel an image of the surroundings is generated and directly projected onto the retina. Within the scope of this dissertation the concepts and techniques of the intraocular vision aid are described. Physiological and technical parameters for application of the microdisplay are explained. That followed the material and applied technologies are defined. Finally the technological realization of the LED microdisplay is demonstrated as well as the first functional model on a worldwide scale.

We consider immersed hypersurfaces in euclidean $R^{n+1}$ which are stable with respect to an elliptic parametric functional with integrand $F=F(N)$ depending on normal directions only. We prove an integral curvature estimate provided that $F$ is sufficiently close to the area integrand, extending the classical curvature estimate of Schoen, Simon and Yau for stable minimal hypersurfaces in $R^{n+1}$. As a crucial point of our analysis we derive a generalized Simons inequality for the laplacian of the length of a weighted second fundamental form with respect to an abstract metric associated with $F$. Using Moser's iteration technique we finally prove a pointwise curvature estimate for $n leq 5$. As an application we obtain a new Bernstein result for complete stable hypersurfaces of dimension $n leq 5$.

The context of this work examines the influence of zinc sulfide (ZnS) and other inorganic substances (Sb2O3, Sb2S3, Sn, Zn ) on the cross-linking reactions of the conjugated double bond sequences, which are generated as a consequence of thermal dehydrochlorination reactions of poly(vinyl chloride) (PVC). With increasing cross-linking grade, the flammability of the corresponding PVC would be decreased due to the suppression of fragmentation reactions. In this work element balances of thermal degrading PVC samples with inorganic additives are analyzed, as well as thermogravimetric investigations are consulted. Apart from qualitative views a kinetic model of the dehydrochlorination reactions is developed using multivariate nonlinear regression analysis of thermogravimetric data. The changes in the thermally stressed polymer samples under argon and under oxygen admission are observed using different analytic techniques (visual video monitoring, infrared spectrometry, and scanning electron microscopy). It can be shown that during the thermal degradation of PVC the cross-linking reactions can be increased by several inorganic additives.

This thesis analyzes the impact of sustainable strategies on local politics in Germany. Making use of structuration theory and different approaches in organization theory, the dissertation argues that it would be very difficult to increase the ecological effectiveness of local government using the idea of sustainable development. The essential aspects of the theoretical assumptions are confirmed by evaluating a wide range of empirical studies on Local Agenda 21, the Environmental Management and Audit Scheme and environmental impact assessment. It can be shown that the ecological effects of local sustainability are limited. Bureaucratization and the growing dominance of economic principles determine the logic of sustainability on the local level. Drawing on the theoretical considerations discussed here, the author concludes by suggesting ways in which the ecological effectiveness of local government can be strengthened.

For circuit simulation and device optimisation it is necessary to have one consistent model which describes not only the DC-behaviour of the device correcty but also the the small-signal and noise behaviour. This work presents a rigorous modell-description of an InP based heterojunction bipolartransitor taking into account material specific effects for all bias conditions.

The development of analytical procedures for the analysis of selected reactive process gases in order to use them in the production of semiconductors without sample preparation is the main task of the presented work. Different atomic spectrometric methods e.g. Electrothermal Atomic Absorption Spectrometry (ETAAS), Microwave Induced Plasma Atomic Emission Spectrometry (MIP-AES), Non dispersive Atomic Fluorescence Spectrometry and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) have been used for the development of the procedures. The physico-chemical features of the matrix request a fitted sampling e.g. suitable, non corrosive material of the tubes and unions, and modified analytical system. The described ETAAS system with an automated sampling system allows the determination of Cu, Fe and Ni in gaseous HCl, Cl2, BCl3 and SiH2Cl2 without sample preparation. A comparison of calibration with standard aqueous solutions as well as standard additions and calibration with a gaseous standard has shown the negligible influence of the matrix on the calibration using the ETAAS system.

The effect of the group-V termination of GaAsSb(100) surfaces on the sharpness of InP/GaAsSb heterointerfaces was investigated. Lattice matched GaAsSb/InP(100)-layers were grown by metalorganic vapor phase epitaxy (MOVPE). Contamination free sample transfer from the MOVPE reactor into ultrahigh vacuum (UHV) allowed for the correlation of in-situ reflectance anisotropy/difference (RA/RD) spectra with low energy electron diffraction (LEED) and photoelectron spectra (XPS/UPS). The in-situ RA spectra indicated that the GaAsSb surface was Sb-rich during growth and turned preferably into an As-rich surface after growth. With LEED and XPS the Sb-rich and As-rich surfaces were correlated with (4×3) and c(4×4) symmetries, respectively. These are well known reconstructions from the related binaries GaAs and GaSb. The study of the InP/GaAsSb interfaces compared the two ordered GaAsSb(100) surfaces as templates for InP growth. XPS measurements of InP/GaAsSb interfaces taken in UHV and I-V curves of InP/GaAsSb resonant tunneling diodes indicated that Sb segregation into a subsequent InP layer was significantly lower when the InP film was grown on the c(4×4) reconstructed GaAsSb surface compared to the (4×3) reconstructed surface.

In the transition from an industrial society to a service society, particularly changes on the labour market are likely to occur. A number of authors assert that these changes will result in an increasing external-numerical flexibility, which is assumed to affect labour market processes in terms of generally higher labour market mobility and decreasing employment stabil-ity (Speeding-up-Thesis). The consequence of this process is said to be a levelling out of employment opportunities and risks; uncertainties that in industrial societies were unevenly distributed along clearly defined socio-economic demarcation lines are said to be becoming increasingly generalised. The old division between core and peripheral workforces is said to be dissolving into general employment instability (De-Structuring-Thesis). Therefore, the dissertation investigates into the individual and firm specific determinants of job stability and how these determinants maybe have changed over time by estimating transition rate models to test both hypotheses. For this reason the event history data of the IAB Employment Subsample (IABS) is used. The results are very different from those one would expect from the de-stabilisation hypothesis and the de-structuring hypothesis. There is no evidence for socio-economic de-structuring, but rather for a socio-economic re-structuring process. This restructuring process has simultaneously led to an increasing polarisation and to an increasing levelling out of employment chances and risks.

Modern driver assistance systems simultaneously increase the safety and the comfort of driving. These systems are designed to fulfil routine tasks and thus aid the driver. Critical situations are detected early and are prevented by direct intervention, i.e. active braking and in the future also active steering. With the complexity of the assistance systems the information demand increases as well. It must be ensured, that the information used, in particular the signals measured by the sensors, are proper. As redundant sensors are generally not acceptable for cost reasons, the sensors must be supervised reliably. In this work the application of model-based sensor-fault diagnosis is examined at the example of the sensors for lateral vehicle dynamics. The aim is to achieve a fast, model-based detection of sensor-faults while avoiding false alarms in any driving situation. This includes driving situations, where the models used are imprecise, and under the influence of an unknown input, the road bank angle. The basis for model-based fault diagnosis are suitable models of the vehicle with adequate accuracy. The process of modelling is thus revisited carefully leading to the two-track model with non-linear modelling of the tyre forces according to the HSRI-model. From this model the one-track model with consideration of vehicle rolling motion is deducted. The essential part of this work are two methods, that are developed. The first method is the normbased estimation of the effect of modelling errors on the state-variables, which are estimated with a model or an observer. The modelling errors of the one-track model in comparison to the two-track model with nonlinear modelling of tyre forces are described as a funcion of measured sensor signals. The method provides an estimate of the faults of the system variables, which can be utilized as well for the definition of a confidence interval as for the generation of adaptive thresholds for fault diagnosis. Subsequently a novel concept for fault diagnosis is presented, which is based on the evaluation of two residuals fro each sensor to be supervised. A detection residual is sensitive to the fault to be detected while a checking residual does not react on this fault but only on any other fault as well as on model uncertainties and unknown input variables. The checking residual is used to define a threshold for the detection residual. This threshold is based on the definition of fault areas in the vector-space spanned by the residuals. To avoid false alarms, the threshold is automatically increased in driving situations with restricted model accuracy. For the realisation of the concept the residuals are generated using Kalman-Filters. The validation of the method is accomplished using measurements from real driving maneuvers.

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