Bestimmung des Grenzumformgrades mit dem Torsionsversuch

Die Bestimmung des Grenzumformgrades eines Stahles, der während der plastischen Verformung nicht überschritten werden kann, ist von großer Bedeutung. Die vorliegende Arbeit berichtet über Ergebnisse von Warmtorsionsversuchen, aus denen der Grenzumformgrad als Funktion von Temperatur und Umformgeschwindigkeit ermittelt wurde. Die Versuche wurden an den Stählen X 10 CrNiTi 18 9, 10 CrMo 9 10, X 10 CrNiMoTi 18 12, X 20 CrMoV 12 1 und X 2 NiCrNb 25 18 durchgeführt.     

A simple video method for the quantification of microscopic objects

The design and operation of a simple, semi-automatic video system for the analysis of geometric parameters of microscopic specimens is described. The system consists of standard video equipment and a custom built Electronic Integrator. The video signal from a camera attached to a microscope is mixed with the video signal from a second camera focused on a drawing board. A contour outline of the specimen to be analysed is drawn with the aid of a video monitor display of the combined images. The contour image is passed into the Electronic Integrator and analysed automatically. Logic circuitry in the Electronic Integrator permits analysis of complex contours independent of their orientation in the video raster. The area or volume of complex, overlapping specimens with restricted grey scale range can be rapidly analysed. The Electronic Integrator also is suitable for densitometric and specimen motion analyses.     

Case Study: Refinement of Hydraulic Operation of a Complex CSO Storage/Treatment Facility by Numerical and Physical Modeling

The performance of a combined sewer overflow (CSO) storage/treatment facility in North Toronto, Ont., Canada, was investigated by conjunctive numerical and physical (hydraulic) modeling. The main objectives of the study were to (1) assess the feasibility of increasing the hydraulic loading of the CSO facility without bypassing; and (2) establish a verified numerical model of the facility for future work. The numerical model [a commercial computational fluid dynamics (CFD), PHOENICS] was validated and verified using results from a hydraulic scale model (1:11.6). The results obtained show that the CFD model can simulate hydraulic conditions in the facility well, as demonstrated by accurate reproduction of the filling rate, water levels at various locations, flow velocities in feed pipes, and overflows from the inflow channel. Numerical simulations identified excessive local head losses and helped select structural changes to reduce such losses. The analysis of the facility showed that with respect to hydraulic operation, the facility is a complex, highly nonlinear hydraulic system. Within the existing constraints, a few structural changes examined by numerical simulation could increase the maximum treatment flow rate in the CSO storage/treatment facility by up to 31%.     

Vascular permeability factor/vascular endothelial growth factor-mediated signaling in mouse mesentery vascular endothelium

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is a multifunctional cytokine and growth factor that has important roles in both pathological and physiological angiogenesis. VPF/VEGF induces vascular hyperpermeability, cell division, and other activities by interacting with two specific receptor tyrosine kinases, KDR/Flk-1 and Flt-1, that are selectively expressed on vascular endothelium. The signaling cascade that follows VPF/VEGF interaction with cultured endothelium is only partially understood but is known to result in increased intracellular calcium, activation of protein kinase C, and tyrosine phosphorylations of both receptors, phospholipase C-gamma (PLC-gamma) and phosphatidylinositol 3'-kinase. For many reasons, signaling events elicited in cultured endothelium may not mimic mediator effects on intact normal or tumor-induced microvessels in vivo. Therefore, we developed a system that would allow measurement of VPF/VEGF-induced signaling on intact microvessels. We used mouse mesentery, a tissue whose numerous microvessels are highly responsive to VPF/VEGF and that we found to express Flk-1 and Flt-1 selectively. At intervals after injecting VPF/VEGF i.p., mesenteries were harvested, extracted, and immunoprecipitated. Immunoblots confirmed that VPF/VEGF induced tyrosine phosphorylation of several proteins in mesenteric microvessels as in cultured endothelium: Flk-1; PLC-gamma; and mitogen-activated protein kinase. Similar phosphorylations were observed when mesentery was exposed to VPF/VEGF in vitro, or when mesenteries were harvested from mice bearing the mouse ovarian tumor ascites tumor, which itself secretes abundant VPF/VEGF. Other experiments further elucidated the VPF/VEGF signaling pathway, demonstrating phosphorylation of both PYK2 and focal adhesion kinase, activation of c-jun-NH2-kinase with phosphorylation of c-Jun, and an association between Flk-1 and PLC-gamma. In addition, we demonstrated translocation of mitogen-activated protein kinase to the cell nucleus in cultured endothelium. Taken together, these experiments describe a new model system with the potential for investigating signaling events in response to diverse mediators on intact microvessels in vivo and have further elucidated the VPF/VEGF signaling cascade.     

Throughput bounds for closed queueing networks

Analytical lower and upper bounds for the throughput of closed queueing networks with single and delay (infinite) servers are studied in this paper. The numerical evaluation of these bounds requires a small number of significant operations which is independent of the population N. This is in contrast to the exact computation of the throughput which requires at least O(N) operations as N tends to infinity. The bounds are given by simple closed-form analytical expressions and may be more suitable for various performance studies than the algorithmical form of the exact solution.In this paper, the previously known balanced-job bounds are generalized to networks containing delay servers (terminals) and a hierarchy of bounds is obtained for single and multiple class networks. For the single class network, further new bounds are derived: lower and upper bounds that require the evaluation of one square root and an upper bound that requires a constant number of exponentiations. This upper bound does not employ the balancing of server loadings and is especially useful for asymptotic analysis in the case of a large number of customers N.     

Ultrastructural localization of prostaglandin endoperoxide synthase (cyclooxygenase) to isolated, purified fractions of guinea pig peritoneal macrophage and line 10 hepatocarcinoma cell lipid bodies

The majority of equations used to predict values for basal metabolic rates (BMRs) are the result of indirect calorimetry measurements performed in the 1930s and 1950s. To assess the reliability of these equations in predicting the resting energy expenditure (REE) of the children in our community, indirect calorimetry was performed on 92 male and 107 female healthy children 2-3 h postprandial. Each individual was measured for a duration of 15-20 min. The data for analysis were obtained from 5-15 min steady-state periods. Subjects ranged in age from 5 to 16 years. The results were compared with BMRs calculated from the Harris-Benedict equation (Harris J, Benedict F. A biometric study of basal metabolism in man. Washington, DC: Carnegie Institute of Washington, publication no. 279, 1919.), the Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU) equations, and the equations proposed by Schofield for use by the 1985 FAO/WHO/UNU Nutrition Committee. The values predicted by the FAO/WHO/UNU and Schofield equations were consistent with the measured resting values for all the children in the study population. Ninety-two children weighed between 90-110% of their ideal body weight. When the measured REE and estimated BMR were compared by gender and age in these children, the Schofield equations provided the best estimates. Ninety-four of the study subjects weighed > 110% of their ideal body weight. The predicted estimates by all equations were consistent with the measured values in this subgroup of the population. We conclude that the FAO/WHO/UNU and Schofield equations are reliable estimates of metabolic rate in healthy children when measurement of REE is not possible.     

Analysis of the human respiratory system in hypoxic and anoxic hypoxia by analogue computer simulation

The goal of this work is to synthesise a model of an adaptive system of respiration control in man, which could be used for the prognosis of human performance under extreme conditions. The model was partly based on 428 experimental results from hypoxic and anoxic hypoxia. Simulation of the oxygen regulatory circuit was realised on the NADAC 100 and MEDA T 80 analogue computers with satisfactory results. Equations constituting a new version of the model are presented in some detail, together with the results of the simulation of ventilatory mechanics.     

Transmission parameters of a class of coupled distributed networks

It is shown how the equations of a class of coupled distributed networks can be decoupled, and their transmission parameters expressed in terms of those of an equivalent scalar system.     

Measurement of Electromagnetic Field Immunity

A short survey is given of various methods proposed for the measurement of equipment immunity to extraneous electromagnetic fields. Their relative merits are discussed and progress in international standardization within the IEC is reported.