井下工具零件应力分析及其软件设计

针对井下工具零件结构复杂、形状怪异，且多为非标准件和非通用件，利用现行手册和常规分析方法难以进行应力分析的情况，依照这类工具零件的力学特征将其分为七大类进行应力分析，并编制了应力分析软件。在编制软件过程中，恰当地选择了软硬件环境和菜单技术，合理地设计了总体框图和分割了屏幕，使得软件具有友好的用户界面。     

A fast Gibbs sampler for synthesizing constrained fractals

It is well known that the spatial frequency spectrum of membrane and thin plate splines exhibit self-affine characteristics and, hence, behave as fractals. This behavior was exploited in generating the constrained fractal surfaces, which were generated by using a Gibbs sampler algorithm in the work of Szeliski and Terzopoulos (1989). The algorithm involves locally perturbing a constrained spline surface with white noise until the spline surface reaches an equilibrium state. We introduce a fast generalized Gibbs sampler that combines two novel techniques, namely, a preconditioning technique in a wavelet basis for constraining the splines and a perturbation scheme in which, unlike the traditional Gibbs sampler, all sites (surface nodes) that do not share a common neighbor are updated simultaneously. In addition, we demonstrate the capability to generate arbitrary order fractal surfaces without resorting to blending techniques. Using this fast Gibbs sampler algorithm, we demonstrate the synthesis of realistic terrain models from sparse elevation data     

B—DMB快速分组交换机的性能分析

由于不能预先对进入B-DMB交换机的各分组进行调整,可能出现同一时隙有2个或2个以上的分组都要到达某一输出端的情形,因此在B-DMB交换机中不可避免地要加进一些缓冲器。本文对B-DMB交换机的输入、输出缓冲器长度和分组时延进行了分析和计算,得出了一些有用的结论。     

周边简支组合折板屋盖的自由振动和受迫振动的级数解

本文首先借助两套局部斜坐标系和广义函数－－符号函数和阶跃函数，建立了组合折板屋盖的曲面方程，然后应用弹性薄壳振动理论和变分法求得了四边简支组合折板屋盖受迫振动响应的挠度和内力表达式。本文还可解决组合折板的自由振动和静力问题，以及Ｖ型折板和长方形双向折板的静力、自由振动和受近振动等问题。故本文实际上包含了九个问题的解。     

Increased prevalence of hypertension and long-term arsenic exposure

A possible role of endothelin (ET)-1 in mediating hypoxic pulmonary vasoconstriction (HPV) was examined by comparing haemodynamic differences between ET-1-induced vasoconstriction and HPV in isolated perfused rat lungs. An ETA receptor antagonist (BQ123) was also employed to assess the effects of ET-1. The pulmonary arterial pressure (Ppa) was significantly increased by alveolar hypoxia (3% O2) and by ET-1 (5 nM). The pulmonary microvascular pressure was not changed by hypoxia, but increased more than two-fold by ET-1 (P < 0.01). Hypoxia significantly increased pulmonary arterial resistance (P < 0.01) while ET-1 significantly increased pulmonary venous resistance (P < 0.01), and slightly increased arterial resistance. Lung weight was increased by ET-1 and decreased by hypoxia, accompanied by similar Ppa responses in both cases. BQ123 (10(-6) M and 10(-5) M) did not influence the changes in Ppa and lung weight induced by hypoxia or angiotensin II (0.3 micrograms). BQ123 did, however, suppress (P < 0.05) the increase in Ppa and lung weight induced by 5 nM ET-1. Thus, it appears unlikely that ET-1 is involved in changes in pulmonary vascular tone during acute HPV.     

CRACK PROPAGATION BEHAVIOR AND LIFETIME PREDICTION IN ALUMINA AND ZIRCONIA

The lifetime prediction of ceramics is discussed on the basis of the relationship between stress intensity factorK1 and crack velocity ν. The effects of water environment, the cyclic loading and microstructure of material on K1-ν characteristics are studied by carrying out the crack growth tests by the double torsion (DT) method under the static andcyclic loading in both environments of air and water for alumina and zirconia. K1-ν characteristics determined by the double torsion method are used to predict time-to-failure under the cyclic loading of alumina and zirconia ceramics. The predictions agree qualitatively with the experimental results.     

Characteristics of 0.8- and 0.2-μm gate length InxGa1-xAs/In0.52Al0.48As/InP(0.53⩽x⩽0.70) modulation-doped field-effect transistorsat cryogenic temperatures

The performance characteristics of InP-based pseudomorphic MODFETs with varying the In composition (0.53⩽x⩽0.70), which changes the strain in the channel, were studied. The temperature was varied in the range of 40-300 K, and the devices had gate lengths L _g of 0.8 and 0.2 μm. The analysis predicts an increase in the intrinsic cutoff frequency with increasing In composition and decreasing temperature and gate length. Also, the analysis predicts that the increase in cutoff frequency with decreasing temperature is less significant with increasing In composition and decreasing gate length. Preliminary experimental results show that as In composition increases from 0.53 to 0.70, f_T increases by 30-40%, and as the temperature decreases from 300 to 40 K, f_T improves by 15-30%, both for 0.8- and 0.2-μm devices     

A novel process to form cobalt silicided p+ poly-Sigates by BF2+ implantation into bilayeredCoSi/a-Si films and subsequent anneal

A novel process that implants BF₂⁺ ions into thin bilayered CoSi/a-Si films has been shown to form cobalt silicided p ⁺ poly-Si gates with excellent gate oxide integrity and very small flatband shift. The effects of not only using the CoSi layer as an implantation barrier but also keeping the a-Si underlayer during the initial silicide formation both significantly suppress the boron penetration through thin gate oxide     

Durable electrochromic coatings prepared from electronically conductive poly(3HT-co-3TPP)-silica hybrid materials

In this paper, a series of organic-inorganic hybrid materials, consisting of heterocyclic conjugated poly(3-hexylthiophene), P3HT, network, and silica particles, were successfully prepared for electrochromic studies. First, the heterocyclic co-polymer of poly[3-hexylthiophene-co-N-(3-trimethoxysilylpropyl) pyrrole], P(3HT-co-3TPP), containing trimethoxysilyl functional groups in the co-polymer backbone as the sol-gel precursor were prepared by conventional oxidative polymerization. Subsequently, P(3HT-co-3TPP)-silica hybrid sol-gel materials in the form of coatings were prepared by baking the microslides and ITO-coated electrodes that had been cast with homogeneous blending solutions containing co-polymer, acid-dopant, tetraethyl orthosilicate (TEOS), and a few drops of water. The microstructures of silica particles formed in the P(3HT-co-3TPP)-silica hybrid materials were investigated by transmission electron microscopy (TEM). The as-prepared hybrid coatings had improved adhesion capability on inorganic glass substrates relative to the pure P3HT on the basis of electrochemical cyclic voltammetric studies and Scotch tape test evaluations. During potential cycling, the film color of P(3HT-co-3TPP)-silica hybrid materials and P3HT coated on ITO electrode changed from orange yellow (i.e., reduced form) to dark blue (i.e., oxidized form) as the redox reactions proceeded. Effects of the material composition of P3HT along with hybrid materials on the electrochemistry, spectroelectrochemistry, thermal stability, and electrical conductivity were also studied.