Mushy zone equilibrium solidification of a semitransparent layer subject to radiative and convective cooling

Equilibrium solidification in a semitransparent planar layer is studied using an isothermal mushy zone model. The layer is made up of a pure material being emitting, absorbing and isotropically scattering and is subject to radiative and convective cooling. The model involves solving simultaneously the transient energy equation and the radiation transport equation. An implicit finite volume scheme is employed to solve the energy equation, with the discrete ordinate method being used to deal with the radiation transport. A systematical parametric study is performed and the effects of various materials optical properties and processing conditions are investigated. It is found that decreasing the optical thickness and increasing the scattering albedo both lead to a wider mushy zone and a slower rate of solidification.     

A functional-dependencies-based Bayesian networks learning method and its application in a mobile commerce system.

This paper presents a new method for learning Bayesian networks from functional dependencies (FD) and third normal form (3NF) tables in relational databases. The method sets up a linkage between the theory of relational databases and probabilistic reasoning models, which is interesting and useful especially when data are incomplete and inaccurate. The effectiveness and practicability of the proposed method is demonstrated by its implementation in a mobile commerce system.     

TEM study of PLZT ceramics

The microscopic structures of PLZT(7.9/70/30 and x/65/35, x = 7 or 8) ceramics were studied by means of transmission electron microscopy. The presence of micro-regions in PLZTs was first verfied.     

乳化炸药混装车水孔爆破的优越性

该文分析了应用袋装炸药装填水孔爆破产生拒爆、"冲天炮"、根底偏高和爆破效果差等问题,然而应用乳化炸药混装车装填水孔可以解决这些问题,并且爆破后具有根底平整、大块率低、毒气少和综合效益高等优点.以三峡永久船闸旁侧泄水箱涵工程和江苏田湾核电站工程为例进行了分析.     

装备工作性能模糊评判新方法

阐述了虚拟样机技术的优越性及其在机械系统研究领域应用中的必要性,总结了火炮可靠和安全工作的三个基本准则.将模糊的观点引入到火炮研究领域,定义了单因素与火炮工作性能等级间的隶属度函数,建立了基于虚拟样机的火炮工作性能模糊综合评判模型.     

Ni-Mo-O催化剂中协同作用对丙烷氧化脱氢的影响

在 Ni-Mo-O体系中 ,加入 Mo O3 能极大地提高丙烷氧化脱氢制丙烯的反应活性。选用固混法、沉淀法、柠檬酸法制备了 Mo O3 过量 1 5 % (摩尔分数 )的α -Ni Mo O4催化剂 ,其中用沉淀法制得催化剂在 5 0 0℃ ,V( C3 H8) /V ( O2 ) /V ( N2 ) =1 0 /1 0 /5 0 ,反应气流量为 70 m L/min的条件下丙烷转化率可达 38.7% ,丙烯选择性达 70 .1 4 %。经 XRD,XPS,TPR表征说明 ,在含有过量 Mo O3 的催化剂中 ,α -Ni Mo O4与 Mo O3 两种晶体之间可产生微小的相互吸引 ;从而发挥协同作用 ,是提高催化剂活性     

超高相对分子质量聚乙烯纤维研究进展

介绍了超高分子质量聚乙烯纤维的制备、表面改性及应用的研究进展 ,指出了今后超高分子质量聚乙烯纤维的研究及应用的发展方向     

Combined shape and sizing optimization of truss structures

 In this paper, an evolutionary optimization method is presented for weight minimum problem of a 3-dimensional truss structure in terms of nodal coordinates and element cross-sectional areas. The structure is subject to stress, local buckling and displacement constraints. Two types of design variables with different natures are optimized separately: (1) a fully stressed design (FSD) and scaling techniques are applied to sizing variables and (2) the evolutionary node shift method is applied to shape variables. Alternating procedure is utilized to couple the two types of variables and to combine the results. The optimum solution is achieved gradually from the initial configuration design. Two typical truss structures are examined to illustrate the validity of the method. Received: 22 October 2001 / Accepted: 04 June 2002 This research work is supported by the National Natural Science Foundation of China under the guarantees no. 10072050 and 10172072, respectively.     

超低密度早强水泥浆在天然气井固井中的应用

在天然气井固井中,上部固井质量一直存在问题。为了提高固井质量,达到保护套管的目的,研制了新型水泥浆体系。经室内研究,选择了减轻剂的种类与粒级配比;根据低密度水泥浆的性能要求,确定了配方,并对该配方进行了触变防漏特性及稳定性分析,形成了具有体系稳定、水泥浆密度波动对水泥浆体系产生影响较小、抗漏失能力强、早期强度发展快等特点的超低密度水泥浆体系。经现场试验,获得了较好的效果。     

高速遥传系统配接DTB总线仪器的接口设计

FPGA（field programmable gate array）技术已经成为当今实现电子线路集成化的重要方法之一。通过应用PFGA和单片机技术，设计一种接口电路，用于将CSU和SKC数控系统中DTB总线的井下仪器挂接到高速 遥传系统上，从而大大提高高速电缆遥传系统的兼容性，使其应用范围更广，市场前景更好。