Effect of hold times on crack retardation in aluminum alloys

Hold time effects on fatigue crack retardation in two high strength aluminum alloys (2219 and 7075) were studied for different metallurgical conditions. Experiments were performed in humid air as well as in vacuum. It was observed that as the hold time at zero load increased, the number of delay cycles decreased in general. This observation is then explained in terms of a strain relaxation phenomenon and a crack closure model. The data indicates that the relaxation effects were greater in humid air than in vacuum. Some visual evidence of surface hammering during retardation was found.     

Estimating the Number of Items on Life Test

If n items are on life test where n is unknown, and failures are observed either until time T has elapsed or until r failures have occurred, then an estimate of n can be obtained. Both maximum likelihood and Bayes estimates are obtained and both known and unknown failure distributions are considered.     

Postinfectious antirabic vaccination of children with duck embryo vaccine and heterologous rabies hyperimmunity serum (author's transl)

After contact with a rabies-infected rabbit, 31 Persons were submitted to complete vaccination treatment with duck embryo vaccine, comprising of injections of 1.0 ml each every fast night and two booster injections of 1.0 ml each, which were administered 10 and 20 days, respectively, after the end of the 14 days' vaccination series. After performance of intracutaneous and ophthalmic tests, 18 children received heterologous rabies immunserum (Behring) in a dose of 0.2 ml per kg of body weight before the beginning of the vaccination series. Six weeks after the start of the vaccination series neutralizing and complement-fixing antibodies (rate of conversion 100 per cent) were detected in all patients. The mean titre of neutralizing antibodies (mouse test 200 LD 50 Fixed virus, strain CVS) amounted to 1:140, that of complement-fixing antibodies to 1:41. Severe incompatibility reactions were not observed. Outpatient treatment with duck embryo vaccine therefore seems to be fully justified.     

Asymptotic expansions and Lie algebras for some nonlinear filtering problems

State estimation problems for systems involving small parameters are treated by both analytical and Lie algebraic approximation techniques. An asymptotic expansion for the unnormalized conditional density corresponding to the case of observations of a Gauss-Markov process through a (weak) polynomial nonlinearity is computed and a convergence result is derived. The expansion is related to certain approximations of the associated estimation Lie algebra. The convergence result is based on arguments used recently to prove existence and uniqueness and to estimate the tail behavior of solutions to nonlinear filtering problems with unbounded coefficients. These arguments are, in turn, adapted from the analytical theory of parabolic PDE's. Simulation results are presented to further assess the performance of the resulting approximate filters.     

Platten-Modellversuche zur Erklärung des Entstehens von Eigenspannungen beim Schweißen

Ermittlung von Temperaturverteilung, Abkühlungsverlauf, Gefüge, Härte und Eigenspannungen bei mittig erwärmten Stahlplatten aus St 37-3 und StE 70. Einfluß des Umwandlungsverhaltens auf die Eigenspannungen. Deutung der Eigenspannungsentstehung beim Zusammenwirken von Wärme- und Umwandlungsspannungen.     

Der Einfluß des Umwandlungsverhaltens auf die Schweißeigenspannungen bei Stahl

Untersuchung des Schrumpfungs- und Umwandlungsverhaltens von Schweißproben aus austenitischem und hochfestem Grund- und Schweißzusatzwerkstoff. Messung von Eigenspannungen im Schweißnahtbereich. Erklärung der Eigenspannungen aus Temperaturverläufen und Härtemessungen im Schweißnahtbereich sowie aus Weg-Zeit-Aufschreibungen für das freie Ende einseitig eingespannter Schweißproben. Deutung der Umwandlungsvorgänge durch Zeit-Temperatur-Umwandlungsschaubilder.     

Self-assembling of atomic vacancies at an oxide/intermetallic alloy interface

Oxide layers grown on the surface provide an effective way of protecting metallic materials against corrosion for sustainable use in a broad range of applications. However, the growth of cavities at the metal/oxide interface weakens the adherence of the protective layer and can promote its spallation under service conditions, as observed for alumina layers formed by selective oxidation of aluminide intermetallic alloys used in high-temperature applications. Here we show that direct atomic-scale observations of the interface between an ultrathin protective oxide layer (alumina) grown on an intermetallic titanium aluminide substrate (TiAl) can be performed with techniques sensitive to the topmost atomic layers at the surface. Nanocavities resulting from the self-assembling of atomic vacancies injected at the interface by the growth mechanism of the protective oxide are observed for the first time, bringing new insight into the understanding of the fate of injected cavities in oxidation processes.     

Sonification supports eyes-free respiratory monitoring and task time-sharing

Three experiments explored the effectiveness of continuous auditory displays, or sonifications, for conveying information about a simulated anesthetized patient's respiration. Experiment 1 established an effective respiratory sonification. Experiment 2 showed an effect of expertise in the use of respiratory sonification and revealed that some apparent differences in sonification effectiveness could be accounted for by response bias. Experiment 3 showed that sonification helps anesthesiologists to maintain high levels of awareness of the simulated patient's state while performing other tasks more effectively than when relying upon visual monitoring of the simulated patient state. Overall, sonification of patient physiology beyond traditional pulse oximetry appears to be a viable and useful adjunct to visual monitors. Actual and potential applications of this research include monitoring in a wide variety of busy critical care contexts.     

Designing the Face of an Interface

Application of the principles of graphic design can bring friendly and effective communication to the Human/computer interface.     

Integrated planning of acquisition,disassembly and bulk recycling: a case study on electronic scrap recovery

Abstract. Due to national and supranational legislation activities, the recovery of discarded products will attain an increasing momentum. Electronic equipment consists of many different parts and materials. Therefore, the related recovery process is often divided into disassembly to remove harmful substances or reusable parts and into bulk recycling to recover ferrous and non-ferrous metals. In order to consider the interactions between choice of scrap to be recovered (acquisition problem), disassembly and bulk recycling, a mixed-integer linear programming model for integrated planning of these stages is presented in this case study. It is applied to determine the daily allocation of products to processes for a major electronic scrap recovery centre that faces limited processing capacities and market restrictions. The optimization calculations covering typical discarded electronic products to be recycled in the related centre lead to a relevant improvement of the economic success. RID="*" ID="*" The authors would like to thank the German “Bundesministerium für Bildung und Forschung” (Federal Ministry of Education and Research) for supporting the research project “Substance Flow Oriented Closed Loop Supply Chain Management in the Electrical and Electronic Equipment Industry (STREAM)rdquo;. Correspondence to: T. Spengler