Effect of the kind of heat tent of tools on friction in plastic deformation of automobile sheet

In sheet stamping, friction appears between the tool and the deformed preform. It is of interest to evaluate the difference in the friction coefficient in stamping by tools subjected to different kinds of heat treatment and chemical heat treatment.     

Electrophile and antioxidant regulation of enzymes that detoxify carcinogens

Detoxication (phase 2) enzymes, such as glutathione S-transferases (GSTs), NAD(P)H:(quinone-acceptor) oxidoreductase (QR), and UDP-glucuronsyltransferase, are induced in animal cells exposed to a variety of electrophilic compounds and phenolic antioxidants. Induction protects against the toxic and neoplastic effects of carcinogens and is mediated by activation of upstream electrophile-responsive/antioxidant-responsive elements (EpRE/ARE). The mechanism of activation of these enhancers was analyzed by transient gene expression of growth hormone reporter constructs containing a 41-bp region derived from the mouse GST Ya gene 5'-upstream region that contains the EpRE/ARE element and of constructs in which this element was replaced with either one or two consensus phorbol 12-tetradecanoate 13-acetate (TPA)-responsive elements (TREs). When these three constructs were compared in Hep G2 (human) and Hepa 1c1c7 (murine) hepatoma cells, the wild-type sequence was highly activated by diverse inducers, including tert-butylhydroquinone, Michael reaction acceptors, 1,2-dithiole-3-thione, sulforaphane,2,3-dimercapto-1-propanol, HgCl2, sodium arsenite, and phenylarsine oxide. In contrast, constructs with consensus TRE sites were not induced significantly. TPA in combination with these compounds led to additive or synergistic inductions of the EpRE/ARE construct, but induction of the TRE construct was similar to that induced by TPA alone. Transfection of the EpRE/ARE reporter construct into F9 cells, which lack endogenous TRE-binding proteins, produced large inductions by the same compounds, which also induced QR activity in these cells. We conclude that activation of the EpRE/ARE by electrophile and antioxidant inducers is mediated by EpRE/ARE-specific proteins.     

Recursive simulation models of the semiconductor laser modulationcharacteristics for accurate performance evaluation of coherent opticalCPFSK systems

Modeling of the semiconductor laser nonuniform FM response and residual IM modulation is essential for the computer-aided design of coherent optical communication systems. This paper presents an accurate simulation model, in which the FM and IM responses are represented by recursive digital filters derived directly from measurements. A comparison with previous models of the bibliography reveals the advantages of the current approach. The proposed modeling procedure is applied in the case of a single-electrode DFB laser. This DFB model, in combination with a semi-analytical technique for the evaluation of the error probability, is used to study the influence of the modulation characteristics on the performance of a coherent heterodyne CPFSK system with differential receiver operating at 1 Gb/s. Theoretical and experimental results are in excellent agreement     

The visualization of water transport through hydrophobic polymer coatings applied to building sandstones by broad line magnetic resonance imaging

It is shown that broad line gradient echo magnetic resonance imaging is an ideal tool with which to study the ingress of hydrophobic polymer surface treatments into porous building materials, specifically in this case sandstone. It is further shown that the method can be used to quantitatively visualize the movement of water into and through the treated material, both from the surface and bulk, as a function of time. The influence of treatment cure time, cure temperature and substrate hydration on the subsequent water transport have been investigated. For the first time direct evidence of water pumping through a treated surface is presented.     

Finite-element analysis of hyperelastic thin shells with large strains

The objective of this contribution is the development of theoretical and numerical models applicable to large strain analysis of hyperelastic shells confining particular attention to incompressible materials. The theoretical model is developed on the basis of a quadratic displacement approximation in thickness coordinate by neglecting transverse shear strains. In the case of incompressible materials this leads to a three-parametric theory governed solely by mid-surface displacements. The material incompressiblity is expressed by two equivalent equation sets considered at the element level as subsidiary conditions. For the simulation of nonlinear material behaviour the Mooney-Rivlin model is adopted including neo-Hookean materials as a special case. After transformation of nonlinear relations into incremental formulation doubly curved triangular and quadrilateral elements are developed via the displacement method. Finally, examples are given to demonstrate the ability of these models in dealing with large strain as well as finite rotation shell problems.The present study is supported by a research grant of the German National Science Foundation (DFG) under Ba 969/3-1.dedicated to Prof. Dr. Dr. Erwin Stein for his 65th birthday anniversary     

A structured procedure for analysis and design of order pick systems

We present a structured procedure for order pick system (OPS) analysis and design that has been established on literature review and interviews with and presentations to OPS experts. In particular, we attempt to include the thinking processes that occur between OPS designers and owners. The design procedure and related issues are discussed in the order of input, selection, and evaluation stages.     

Effect of oil viscosity on transformer loading capability at lowambient temperatures

The applicability of the ANSI loading guide for power transformers is limited to ambient temperatures above 0°C because the thermal model does not account for variations in the oil viscosity and winding resistance. A practical calculation method based on the bottom-oil temperature and the surface temperature at the top of the cooling duct has been developed. Results indicate that the proposed thermal model could provide a sound basis for calculating the overload capacity for ambient temperatures below 0°C or for severe overloads of short duration