Cold drawing of elastic-thermoviscoplastic polymeric films and fibres

Finite element analyses of the process of polymer drawing for elastic-thermoviscoplastic material behaviour are performed. The deformation-induced heat generation and its softening effect are accounted for. Non-adiabatic thermal effects are examined from the beginning of the loading process, to the attainment of the nearly steady-state neck propagation stages. Solutions for both polymeric films as well as fibres are presented.     

The Effects of Various Heat Treating Parameters on the Hardness and Microstructures of the Experimental 18% Nickel Maraging Steels

The effect of the parameters of heat treatment on the experimental 18% maraging steels was studied using hardness tester, optical, scanning electron and transmission electron microscopy and X-ray metallography techniques. The specimens were solution treated at 815, 900, 1000, 1060°C for periods between 1 and 4 h. After air-cooling to room temperature, a bcc martensitic structure was obtained. The higher temperature (1060°C) and longer time (4 h) of the solution treatment caused essentially homogeneous, massive martensitic structure. The aging of the steels was studied between 240 and 480°C from 1 to 41 h. As indicated by the results, the hardness vs. aging time curves show a rapid rate of hardening at 480°C while the response at 240 to 320°C is slower. The time required to reach peak hardness increases with decreasing temperature. The increase in hardness during aging can be explained by the precipitation of hardening phases. So, it is necessary to use a high temperature solution treatment to obtain a better alloy distribution and a tough martensitic structure, and an aging treatment at 480 °C between 4 and 10 h to achieve the desired properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the use of the photoacoustic technique for the measurement of the thermomechanical properties of semiconductor two-layer systems

The photoacoustic technique is used in semiconductor two-layer systems for the determination of thermal properties and thermal expansion coefficient. The two-layer systems studied were amorphous silicon-glass and Al_0.2Ga_0.8As---GaAs. Our results show that the proposed method is a reliable technique for the characterization of other semiconductor two-layers systems.     

关于带有完全对称函数的广义数值域

本文给出了矩阵Ａ的带有完全对称函数Ｃｋ的ｍ－数值域在复平面上为线段的充分必要条件．     

Stabilité de la Cohomologie LP au Voisinage de 2 pour les Espaces Localement Symétriques

We give a sufficient condition for stability around 2 of L^p cohomology of a system over locally symmetric space.     

薄膜电子隧穿几率的数值计算方法

文章对电子透射几率问题进行了数值求解，这种方法能够处理形状复杂的一维势垒。首先利用龙格一库塔法和Numerov方法，联立求解薛定谔方程，然后利用得到的结果计算电子的透射几率，并考虑了计算误差的影响和减小方法。将该方法得到的数值解与精确值进行了比较，并用此方法考虑了不同双势垒结构中的共振隧穿问题。     

MODIFIED PARALLEL ROSENBROCK METHODS FOR STIFF DIFFERENTIAL EQUATIONS

1. IntroductionIn many fields of science and engineering technology, we often meet with stiff ordinarydifferential equations. In order to solve these systems, we have to use the implicit methods,which lneans that nonlinear implicit equations must be solve…     

Controlled vapor-pressure heat-treatment effect on deep levels in liquid-encapsulated czochralski-grown GaP crystals

Photocapacitance (PHCAP) measurements have been carried out on GaP crystals grown by the liquid-encapsulated Czochralski (LEC) method with heat treatment under various phosphorus-vapor pressures at different temperatures. Electron traps of E_C−1.1 eV, E_C−1.6 eV, E_C−1.9 eV, and a hole trap of E_V+2.26 eV are mainly detected. The phosphorus-vapor pressure dependence of the E_C−1.9 eV trap density and their diffusion behavior indicate that they are interstitial phosphorus atoms. The densities of both E_C−1.1 eV and E_C−1.6 eV traps are strongly dependent on the shallow impurity concentrations. Moreover, the density of E_C−1.1 eV traps increases with increasing phosphorus-vapor pressure. From these results, we suggest that E_C−1.1 eV traps are the complexes of shallow donors and antisite phosphorus atoms. Deep-level densities in GaP crystals after annealing at 860°C or 960°C for 60 min are decreased almost one order of magnitude lower than those in untreated substrate crystals, which should have occurred via out-diffusion of interstitial phosphorus atoms. However, such an effect is not prominent for 800°C treatment for 60 min.     

电磁问题中几种减少计算时间的方法和比较性研究

在电磁理论问题的求解中，往往会遇到大系统问题，如何减少大系统问题的计算时间是一个具有共性的重要课题，本文对求解大系统问题的几秒方法进行了介绍和比较性研究，其中包括矩量法，网络分解法，矩阵分块法和空域分解法，文章在简述了这些方法的原理之后，给出了用上述方法以及用普通的矩量法计算同一问题的计算时间和储存量，并且比较了各种方法的特点。     

Sorption-enhanced steam reforming of hydrocarbons with autothermal sorbent regeneration in a moving heat wave of a catalytic combustion reaction

A novel technological concept of sorption-enhanced steam reforming of hydrocarbons is suggested. The peculiarity of the concept is the autothermal regeneration of the carbon dioxide scavenger in the moving super-adiabatic heat wave of an exothermic catalytic combustion reaction performed directly inside the adsorption-catalytic bed. The capability and high efficiency of the proposed technological approach are confirmed by process simulation. The approach proposed is shown to open a way for the creation of an inexpensive, reliable and energy-saving adiabatic packed bed methane processors of unlimited processing capacity.