Bedeutung der Vakuumtechnik in der Metallpulver-Technologie

Powder-Technology has developed into a significant and still increasing market. There is a demand for high quality meaning highest purity and spherical particle shape of the powder. In order to reach this aim metal alloys are melted under vacuum and atomized with intertgas. To improve the chemical purity the produced powder is treated under vacuum for instance by the static or dynamic degassing process.     

An initial approach to establishing an experimentally proven ‘leak before rupture criterion’ for SNR-300 components

Examination of experimental results and fracture mechanics analysis has shown the sudden rupture of one of the SNR-300 main coolant pipes to be impossible. The analysis indicates that, excluding small leaks, the integrity of the sodium filled heat transfer system under normal operating conditions will also be maintained. With regard to small leaks it is considered that if these are smaller than those which would give a leak rate of less than about 1 kg/h, they can be detected.     

Stacking fault energy and mechanical properties

Several deformation mechanisms are discussed which may be influenced by the stacking fault energy: forest cutting at the beginning of plastic deformation in fcc and hex metals, cross slip in fee metals, prismatic slip in hexagonal metals, and slip in bee metals. Existing experimental data for the temperature and strain rate dependence of the shear stress at which the relevant deformation mechanism begins are analyzed. It is shown that the data for cross slip in fee metals, for prismatic slip, and for slip in bee metals can be described by an Arrhenius equation with an activation energy that is proportional to the logarithm of the stress. Stacking fault energies are determined from the strain rate sensitivity of the shear stress.     

Untersuchungen über den Einfluß des Gefügezustandes auf das Korrosionsverhalten hochlegierter,rost- und säurebeständiger Stähle in reiner sowie in chloridhaltiger Schwefelsäure

Corrosion Properties of High Alloyed Stainless Steels in Pure as well as in Chloride Containing Sulfuric Acid The corrosion behaviour of the high alloyed stainless steels material no. 1.4439 (X3CrNiMoN17135), 1.4539 (X2NiCrMoCu25205), 1.4503(X3NiCrMoCuTi2723) as well as the reference materials AlSI 316 L and alloy 825 was tested in diluted sulfuric acid (5, 10, 20 and 50%) at 50, 100 and 150°C. The test solutions additionally contained impurities as chlorides and cupric ions. On the material side the effect of various microstructures was checked as well: material as received (commercial production), solution annealed under laboratory conditions, cold deformed and for two selected steels electroslag remelted. Corrosion testing methods are: the immersion test will sheet coupons and the measurement of the weightloss; electrochemical testing, i.e. Current potential-and free corrosion potential-time-curves. No pitting corrosion is observed in the presence of chloride ions. In some cases the general corrosion rate is lowered if chloride ions are present. This beneficial effect of chloride ions, however, is observed only at low chloride concentrations (500 ppm). Annealing under laboratory conditions as well as electroslag remelting does not generally improve the corrosion resistance. A negative effect by cold deformation is only observed for standard stainless steel AlSI 316. Cupric ions added to the 20% sulfuric acid solution improve the corrosion resistance of all steels investigated to that extent, that they can be used in practice up to 100°C provided that the concentration of cupric ions in the solution is sufficiently high (2000 ppm). Electrochemical test results indicate that the positive effect of cupric ions is due to the shift of the free corrosion potential into the potential range of stable passivity. Copper alloyed stainless steels show the highest corrosion resistance.     

Investigations into the oral lead exposure of adults in the former German Democratic Republic

The lead content of a representative assortment of foodstuffs and drinking water as well as the lead intake of adults were systematically investigated in 1988 in order to judge the oral lead exposure of the inhabitants of the former German Democratic Republic (GDR). The food-stuffs as well as the drinking water contained normal lead concentrations. Levels exceeding the limits set by the Federal Office of Health and the Decree on Drinking Water were not obtained. The lead intake was 34 g/day in adult men and 25 g/day in adult women according to the results of the basket study, amounting to 11–13% of the PTWI provisional tolerable weekly intake value of lead. An oral lead exposure of the adult population in the former GDR can be excluded.

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Zusammenfassung Zur Beurteilung der oralen Bleibelastung der Bevölkerung der ehemaligen DDR wurde der Bleigehalt eines repräsentativen Lebensmittelsortimentes und des Trinkwassers sowie die Bleiaufnahme Erwachsener im Jahre 1988 systematisch untersucht. Die Lebensmittel sowie das Trinkwasser enthielten normale Bleimengen. Überschreitungen der BGA-Richtwerte bzw. des Grenzwertes der Trinkwasserverordnung wurden nicht beobachtet. Die Bleiaufnahme Erwachsener betrug nach den Ergebnissen der Markkorbstudie 34 g/Tag bei den Männern und 25 g/Tag bei den Frauen. Die Ausschöp-fungsrate des PTWI-Wertes der Bleiaufnahme belief sich auf 11 bis 13%. Eine orale Bleibelastung der erwachsenen Bevölkerung der ehemaligen DDR ist auszuschließen.

     

Lexical paraphrases in multilingual sentence generation

We describe the architecture of a sentence generation module that maps a language-neutral deep representation to a language-specific sentence-semantic specification, which is then handed over to a conventional front-end generator. Lexicalization is seen as the main task in the mapping step, and we specifically examine the role of verb semantics in the process. By separating the various kinds of knowledge involved, for related languages (such as English and German) the task of multilingual sentence generation can be treated as a variant of the monolingual paraphrasing problem.     

A Parallel Dynamically Reconfigurable Architecture Designed for Flexible Application-Tailored Hardware/Software Systems in Future Mobile Communication

The evolving of current and future broadband access techniques into the wireless domain introduces new and flexible network architectures with difficult and interesting challenges. The system designers are faced with a challenging set of problems that stem from access mechanisms, energy conservation, error rate, transmission speed characteristics of the wireless links and mobility aspects. This paper presents first the major challenges in realizing flexible microelectronic system solutions for future mobile communication applications. Based thereupon, the architecture design of flexible system-on-chip solutions in the digital baseband processing for future mobile radio devices is discussed. The focus of the paper is the introduction of a new parallel and dynamically reconfigurable hardware architecture tailored to this application area. Its performance issues and potential are discussed by the implementation of a flexible and computation-intensive component of future mobile terminals.An erratum to this article can be found at     

Multifunctional software systems: Structured modeling and specification of functional requirements

This paper deals with the structured specification of interface behavior of multifunctional systems, which are systems that offer a variety of functions for different purposes and use cases. It introduces a theory and first concepts of a methodology for the identification, structured modeling, and formalization of functional requirements of multifunctional systems. Service hierarchies specify multifunctional systems in terms of their provided sub-functions called services together with their mutual relationships and dependencies. A service hierarchy describes the functionality of multifunctional systems in a structured way. Each service is specified independently and the specification is added to the service hierarchy. Modes help to specify the feature interactions and by that functional dependencies between the services. The approach is based on the Focus theory for modeling interface behavior and services.