Monitoring and fault diagnosis of hybrid systems.

Many networked embedded sensing and control systems can be modeled as hybrid systems with interacting continuous and discrete dynamics. These systems present significant challenges for monitoring and diagnosis. Many existing model-based approaches focus on diagnostic reasoning assuming appropriate fault signatures have been generated. However, an important missing piece is the integration of model-based techniques with the acquisition and processing of sensor signals and the modeling of faults to support diagnostic reasoning. This paper addresses key modeling and computational problems at the interface between model-based diagnosis techniques and signature analysis to enable the efficient detection and isolation of incipient and abrupt faults in hybrid systems. A hybrid automata model that parameterizes abrupt and incipient faults is introduced. Based on this model, an approach for diagnoser design is presented. The paper also develops a novel mode estimation algorithm that uses model-based prediction to focus distributed processing signal algorithms. Finally, the paper describes a diagnostic system architecture that integrates the modeling, prediction, and diagnosis components. The implemented architecture is applied to fault diagnosis of a complex electro-mechanical machine, the Xerox DC265 printer, and the experimental results presented validate the approach. A number of design trade-offs that were made to support implementation of the algorithms for online applications are also described.     

Gekoppelte Modellierung geohydraulischer und limnophysikalischer Vorgänge in Tagebaurestseen und ihrer Umgebung

In the abandoned lignite mine of Merseburg-Ost in Central Germany, the lakes 1a and 1b have been filled the natural recovery of the artificially lowered groundwater level for a period of several years. Recently the flooding from a nearby small river has started. The long-term conditions of the developing lakes, especially the degree of salt accumulation from deep saline groundwaters and the behaviour in time of the highly saline monimolimnia which formed at the base of the lakes were assessed. To reproduce the interaction between the groundwater flow and physical processes within the lakes, a 3D density-sensitive hydrogeological model to predict groundwater inflows and outflows was coupled with a limnophysical model of high vertical resolution. The results of a coupled hundred-years-prognosis is shown. Evidence is provided that the different behaviour of the two lakes is a consequence of the differences in the groundwater inflows.     

Membranen in der medizinischen Verfahrenstechnik

Membranes in medical process engineering . Synthetic membranes not only represent the essential components of an artificial kidney or an artificial lung but are also used as wound dressing and in systems for controlled release of drugs in certain long-term therapeutic measures or as part of an artificial pancreas. By far the greatest present economic significance of membranes is their use in the so-called artificial kidney. Considerable cost saving would result if patients could undertake ?home dialysis”?. This requires the development of new, simpler artificial kidneys and thus higher-performance membranes. The latest trend in ?artificial kidneys”?, the so-called method of ?hemodiafiltration”? warants special mention. The separation process is no longer effected only by diffusion but also by convection, i.e. the driving force is the pressure difference between the two sides of the membrane. This paper addresses problems encountered in the development and use of membranes in medicine, recent applications such as the controlled release of active components, or plasma separation, and demonstrates the potential of membranes in medicine.     

The risk of chronic progressive radiation myelopathy

5-year cure rates after radiotherapy of nasopharingeal carcinomas in the own patients are reported. The 5-year cure rate in squamous cell carcinoma is about 30% and in lymphoepithelial carcinoma Schmincke-Regaud about 50%. These results are comparable to those which are published in the recent literature. The base of the skull should be included in the high-dose volume even in T1 and T2 cases.     

Arene—onium cations—V. Preparative investigation concerning yields and selectivities for the anodic formation of some selected trisarene sulphonium cations

Based on kinetic data for the anodic oxidation of bisarenesulphonium cations[1] the preparative anodic oxidation of bisanisolesulphide, bisbenzenesulphide and bistoluenesulphide was performed in acetonitrile in presence of different arenes as coupling partners aiming to show that higher selectivities for the formation of desired trisarene sulphonium cations can be obtained provided appropriate process parameters are chosen. It is decisive to establish a concentration ratio {c(arene)/c(bisarenesulphide)} in the reaction layer which is high enough to keep the rate of anodic self-coupling vs the coupling with the desired arene low enough. For the formation of trisanisole sulphonium cations, where not self-coupling but coupling with water (yielding bisanisole oxide) is the most important competing reaction, a selectivity of 80% is already obtained if the ratio of the bulk concentrations of the competing coupling partners water and anisole is unity. In the case of the formation of tristoluenesulphide further advantage for obtaining a higher selectivity may be drawn from heterogeneous catalysis of the coupling reaction at carbon anodes. The yield for tristoluene sylphonium cations can be raised to nearly 90% at carbon anodes whereas oxidizing 0.1 M bistoluenesulphide in the presence of 0.1 M toluene at platinum anodes yields only undesired self-coupling products. From bisbenzenesulphide no trisbenzene sulphonium cations could be obtained; however, coupling with mesitylene, xylene and toluene was achieved.     

Probleme der Kriechstromfestigkeitsprüfung

Problems of Tracking Tests. The influence of the electrolyte, the material of the electrodes and the test voltage on the results were explored. Furthermore tracking tests with D. C. were described. A table of test results, obtained with D. C. and A. C. and also different electrolytes allows a comparision of the tracking behavior of a large number of materials.     

On change detection and displacement vector estimation in image sequences

Recent developments in the areas of displacement vector estimation as well as dissimilarity grading by a maximum likelihood ratio can be related to each other quantitatively in such a way that dissimilarity grading is reduced to interframe displacement estimation.