层流预混滞止火焰结构及传播速度的数值模拟

在考虑了甲烷与空气燃烧过程中17种分子、原子和基团的46个基元反应的基础上，采用数值模拟方法求解了甲烷层流滞止火焰结构，给出了各种组分与温度的空间分布，计算了不同拉伸率下的甲烷滞止火焰的传播速度，导出了层流预混火焰的传播速度。

单脉冲激波管中全氟乙烯在有氢条件下的分解

在单脉冲激波管中研究了有H_2条件下C_2F_4的分解。对于分解反应C_2F_4+Ar→2CF_2+Ar，利用CF_2插入H_2的后续结果，产生稳定的CH_4作为上述反应的进行度的标识，结果显示温度在1000～1080K分解速率与Modica和LaGraff的速率常数相合。直接测定反应后C_2F_4的剩余浓度，则显示有多于直接热解10倍的C_2F_4消耗。这是由于CF_2与H_2的反应的后果将导致有H原子释入系统内，它引发了C_2F_4的链式聚合。

Al2O3颗粒对Al—Zn合金激光快凝组织的影响

通过比较Ａｌ－Ｚｎ合金和Ａｌ２Ｏ３ｐ／Ａｌ－Ｚｎ复合材料的激光重熔组织。分析Ａｌ２Ｏ３颗粒对Ａｌ－Ｚｎ合金激光快凝组织的影响规律。实验结果表明，Ａｌ２Ｏ３颗粒可以显著经激光熔区的晶粒。基于凝固界面与颗粒交互的理论分析，给出了晶粒细化的临界条件。

Anomalous Thermal Stability of Nd-Fe-Co-Al Bulk Metallic Glass

The thermal stability of Nd60Fe20Co10Al10 bulk metallic glass (BMG) has been studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), isochronal dilatation and compression tests. The results show that the glass transition of the BMG takes place quite gradually between about 460 and 650 K at a heating rate of 0.17 K/s. Several transformation processes are observed during continuous heating with the first crystallization process beginning at about 460 K, while massive crystallization takes place near the solidus temperature of the alloy. The positive heat of mixing between the two major constituents, Nd and Fe, and, consequently, a highly inhomogeneous composition of the attained amorphous phase are responsible for the anomalous thermal stability in this system. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

The thermo-visco-plastic instability analysis of saturated soil

A theoretical analysis of instability of saturated soil is presented considering the simple shearing of a heat conducting thermo-visco-plastic material. It is shown that the instability is mainly the consequence of thermal softening which overcomes the strain hardening and the other type of instability is controlled by strain softening. The effects of other factors such as permeability to the instability are discussed in this paper.

水—沙两相流的激光多普勒分相测量和试验研究

探讨泥沙颗粒在水流中的悬浮运动机理和水、沙两相之间的相互作用,首先需要分别了解水流和泥沙颗粒的运动特性及相互关系。因此,怎样分相观测水流和泥沙颗粒的运动参数成为泥沙运动基本理论研究的一个重要问题。本文集中介绍了利用激光多普勒技术分相测量水流和泥沙运动参数的基本原理和方法,以及利用常见的一维激光器(无声光频移) 测量水流和颗粒垂向(垂直于水流运动方向) 脉动速度的实验方法。使用该技术对水平方管内的水- 沙两相流运动进行了试验观测,给出了两相速度、纵向及垂向湍流度,以及泥沙浓度的测量结果。

JF—10氢氧爆轰驱动激波风洞自由流的测量和诊断

针对ＪＦ－１０氢氧爆轰驱动风洞动行的高焓高速状态，采用吸收光谱技术、皮托压力瞬态测量技术、电离探针等的测试方法，测量了自由流中一氧化氮的含量和离子浓度、皮托压力及其沿喷管出口半径方向的分布。并根据以上各项测量结果判断了自由流的非平衡程度。

有限元平面三角形网格自动划分

提出了一种采用单元尺寸函数进行有限元平面三角形网格自动划分的方法，根据给定的几何或物理条件，计算待划分区域上每点的单元尺寸，并以此整个区域划分为单元尺寸各不相同的若干个子域，在各个子域内部生成均匀网格。

An Amino Acid Substitution Matrix for Protein Conformation Identification

Amino acid substitution matrices play an essential role in protein sequence alignment, a fundamental task in bioinformatics. Most widely used matrices, such as PAM matrices derived from homologous sequences and BLOSUM matrices derived from aligned segments of PROSITE, did not integrate conformation information in their construction. There are a few structure-based matrices, which are derived from limited data of structure alignment. Using databases PDB_SELECT and DSSP, we create a database of sequence-conformation blocks which explicitly represent sequence-structure relationship. Members in a block are identical in conformation and are highly similar in sequence. From this block database, we derive a conformation-specific amino acid substitution matrix CBSM60. The matrix shows an improved performance in conformational segment search and homolog detection.

Liquid phase epitaxy growth of AlxGayIn1-x-yPzAs1-zGaAs with direct band gap up to 2.0 eV

III-V pentenary semiconductor AlGaInPAs with a direct band gap of up to 2.0 eV has been grown successfully on GaAs substrates by liquid phase epitaxy;(LPE). With the introduction of the energy bowing parameters of quaternaries, the theoretical calculations agree well with the measured PL peak energy data from pentenary samples.

Micro-Fracture Toughness in a Nanoceramic Composite

Micro-fracture toughness in one nanoceramic composite, Al_2O_3/SiC_{nano}, is measured by Nanoindentation tests. Microscopy is adopted to probe that all nanoindentations are local at Al_2O_3, matrix component of the current composite and measure length of radial micro-cracks at corriers of nanoindentation. The measured fracture toughness at the shallow indentation is higher than those at deeper ones. Relations between micro-toughness and peak loads as well as peak depths are discussed. And an analysis to the energy consumed during the indentation and fracture toughness explained that, the lower fracture toughness measured in the deeper impression probably resulted from its fracture modes yielded by higher load and larger depth.

Effects of Graphitization on the Synthesis of Ultrafine Diamond by Explosive Detonation

金刚石的石墨化对于炸药爆轰过程中金刚石的产出率有重要的影响。对碳相图进行了讨论,提出采用金刚石2石墨的动力学平衡线来评价炸药爆轰过程中金刚石的石墨化。通过数值模拟,对炸药爆轰过程中金刚石的石墨化进行了分析和讨论。