前飞旋翼三维湍流场的数值模拟

采用计算流体力学CFD(Computational Fluid Dynamics)方法,分析正常前飞和近地前飞时直升机的流场与性能.在直角坐标系中,采用有限体积法和压力耦合方程的半隐式法SIMPLER(Semi-Implicit Method for Pressure-Linked Equations Revised)算法求解三维定常不可压的湍流N-S(Navier-Stokes)方程.在分析中,旋转的螺桨被描绘成沿螺桨桨叶展向分布、与本地流动参数相关以及时间平均的动量源项.计算方法还包括K-ε湍流模型和壁面函数法等措施.流场分析和性能预测同实验测量数据的良好的一致性表明,这种CFD方法可以有效的分析直升机的具体设计问题.      

LDMS系统在核压力容器检测和生产中的应用

比较了两种测量方法检测压力容器的可行性，阐述了ＬＤＭＳ系统在压力容器焊接定位和加工过程中的应用。     

一种研究电弧风洞等离子体密度的诊断方法

用微波探针法研究了等离子体密度变化。一般情况下，它除了不对等离子体产生干扰外，还可以对等离子体进行实时监测。本文利用这种方法对电弧风洞等离子体的形成以及不同状态下的密度变化作了观测，并同扫描朗谬探针在相同实验条件下的结果进行了比较。实验结果表明，微波探针是研究特殊环境下等离子体密度变化的一种好方法。     

用于微光探测器的天文杜瓦

综述了天文用ＣＣＤ激光探测器对天文杜瓦的要求，介绍了研制的ＴＷＤ型杜瓦的特点和试验情况。试验结果表明，在无探测腔时，Ⅱ型和Ⅲ型杜瓦容器的技术指标分别达到：有效容积２．５Ｌ和１．２５Ｌ；质量２．０５ｋｇ和３．０２ｋｇ；液氮保存期１１０ｈ和１１６ｈ．真空寿命达２年以上．接探测腔后，Ⅱ型杜瓦液氮保存期为４０ｈ；ＣＣＤ冷盘温度可达到－１００～－１２０℃．     

两项美国"人-机-环"军用标准简介

概述了两项美国关于“人-机-环”军用标准的编制背景及实施要求,简介和分析了不同版本标准的有关内容与差异,并概述了我国“人-机-环”军用标准的发展简况。     

三坐标测量机的现状、发展与未来

叙述了三坐标测量机的基本构成、国内外上产现状、发展与未来。包括测量机的准确度、分类及丰富的软件。尤其对测量机的发展作了较详细的介绍。最后，预测厂测量机的未来。     

Fault tolerant small satellite attitude control using adaptive non-singular terminal sliding mode

The Attitude Control System (ACS) plays a pivotal role in the whole performance of the spacecraft on the orbit; therefore, it is vitally important to design the control system with the performance of rapid response, high control precision and insensitive to external perturbations. In the first place, this paper proposes two adaptive nonlinear control algorithms based on the sliding mode control (SMC), which are designed for small satellite attitude control system. The nonlinear dynamics describing the attitude of small satellite is considered in a circle reference orbit, and the stability of the closed-loop system in the presence of external perturbations is investigated. Then, in order to account for accidental or degradation fault in satellite actuators, the fault-tolerant control schemes are presented. Hence, two adaptive fault-tolerant control laws (continuous sliding mode control and non-singular terminal sliding mode control) are developed by adopting the nonlinear analytical model to describe the system, which can guarantee global asymptotic convergence of the attitude control error with the existence of unknown external perturbations. The nonlinear hyperplane based Terminal sliding mode is introduced into the control law design; therefore, the system convergence performance improves and the control error is convergent in “finite time”. As a result, the study on the non-singular terminal sliding mode control is the emphasis and the continuous sliding mode control is used to compare with the non-singular terminal sliding mode control. Meanwhile, an adaptive fuzzy algorithm has been proposed to suppress the chattering phenomenon. Moreover, several numerical examples are presented to demonstrate the efficacy of the proposed controllers by correcting for the external perturbations. Simulation results confirm that the suggested methodologies yield high control precision in control. In addition, actuator degradation, actuator stuck and actuator failure for a period of time are simulated to demonstrate the fault recovery capability of the fault tolerant controllers. The numerical results clearly demonstrate the good performance of the adaptive non-singular terminal control in the event of actuator fault compare with the continuous sliding mode control.