高压动态标定用的水激波管

本文介绍了一种用于对1000MPa 以下的高压传感器进行动态特性标定的水激波管装置,装置内径30mm,管长550mm,用叠氮化铅点火头为爆源,用 PVF_2压电薄膜做成色散压杆传感器监测其压力波形。利用该装置对二种不同原理的高压传感器进行了动态标定试验,得到了初步的频率响应特性的试验结果。

Effect of rapid cold stamping on fracture behavior of long strip S′phase in Al−Cu−Mg alloy

High-angle annular dark-field scanning transmission electron microscopy and selected area electron diffraction techniques were used to study the mechanism that underlies the influence of rapid cold-stamping deformation on the fracture behavior of the elongated nanoprecipitated phase in extruded Al−Cu−Mg alloy.Results show that the interface between the long strip-shaped S′phase and the aluminum matrix in the extruded Al−Cu−Mg alloy is flat and breaks during rapid cold-stamping deformation.The breaking mechanisms are distortion and brittle failure,redissolution,and necking.The breakage of the long strip S′phase increases the contact surface between the S′phase and the aluminum matrix and improves the interfacial distortion energy.This effect accounts for the higher free energy of the S′phase than that of the matrix and creates conditions for the redissolution of solute atoms back into the aluminum matrix.The brittle S′phase produces a resolved step during rapid cold-stamping deformation.This step further accelerates the diffusion of solute atoms and promotes the redissolution of the S′phase.Thus,the S′phase necks and separates,and the long strip-shaped S′phase in the extruded Al−Cu−Mg alloy is broken into a short and thin S′phase.

一种新兴的仿真技术──分布式交互仿真(一)

为适应高技术作战环境下武器群体或攻防体系对抗的仿真，系统仿真已由单武器平台的性能仿真发展为多武器平台在作战环境下体系对抗的仿真。分布式交互仿真（DIS）即是在这种需求背景下产生的新兴仿真技术。DIS所构筑的综合仿真环境，大大扩展了仿真的应用领域。文中全面论述了DIS的概念、定义、结构组成与技术特点，以及DIS的设计原则与体系结构，详细分析了实现DIS综合环境应解决的关键技术问题以及应用领域。

Modelling of vehicle interaction behavior during discretionary lane-changing preparation process on freeway

In order to increase the accuracy of microscopic traffic flow simulation,two acceleration models are presented to simulate car-following behaviors of the lane-changing vehicle and following putative vehicle during the discretionary lanechanging preparation( DLCP) process, respectively. The proposed acceleration models can reflect vehicle interaction characteristics. Samples used for describing the starting point and the ending point of DLCP are extracted from a real NGSIM vehicle trajectory data set. The acceleration model for a lanechanging vehicle is supposed to be a linear acceleration model.The acceleration model for the following putative vehicle is constructed by referring to the optimal velocity model,in which optimal velocity is defined as a linear function of the velocity of putative leading vehicle. Similar calibration,a hypothesis test and parameter sensitivity analysis were conducted on the acceleration model of the lane-changing vehicle and following putative vehicle,respectively. The validation results of the two proposed models suggest that the training and testing errors are acceptable compared with similar works on calibrations for car following models. The parameter sensitivity analysis shows that the subtle observed error does not lead to severe variations of car-following behaviors of the lane-changing vehicle and following putative vehicle.

基层情报工作的新动向和展望

在新的技术革命和国内经济体制改革的影响下,我国基层情报工作正在进行各项改革,酝酿着新的发展。分析新形势下基层情报工作的动向和展望工作前景,对于加强工作信心和拟定工作计划具有重要意义。一、现状和动向新技术革命和国内经济体制改革的新形势。