静态压力试验自动控制系统

该系统是为校检各种压力传感器和数字式压力计而试制的。使用它,使校检过程完全自动化,大大地提高了校检的速度和准确度。 本系统由157/100型压力标准、IBM-PC微机和高低温箱等近十台设备组成。软件是用FORTRAN语言、宏汇编语言和关系数据库dBASFⅢ写成的。计算机采用人-机对话方式     

A hazard analysis via an improved timed colored petri net with time–space coupling safety constraint

Petri nets are graphical and mathematical tools that are applicable to many systems for modeling, simulation, and analysis. With the emergence of the concept of partitioning in time and space domains proposed in avionics application standard software interface(ARINC 653), it has become difficult to analyze time–space coupling hazards resulting from resource partitioning using classical or advanced Petri nets. In this paper, we propose a time–space coupling safety constraint and an improved timed colored Petri net with imposed time–space coupling safety constraints(TCCP-NET) to fill this requirement gap. Time–space coupling hazard analysis is conducted in three steps: specification modeling, simulation execution, and results analysis. A TCCP-NET is employed to model and analyze integrated modular avionics(IMA), a real-time, safety-critical system. The analysis results are used to verify whether there exist time–space coupling hazards at runtime. The method we propose demonstrates superior modeling of safety-critical real-time systems as it can specify resource allocations in both time and space domains. TCCP-NETs can effectively detect underlying time–space coupling hazards.     

振动试验和颤振分析的一体化——颤振实时分析系统

 <正> “颤振实时分析系统”是航空航天工业部振动环境课题组于1985年～1988年期间组织研制的一项课题,它是参考80年代美国波音公司的振动和颤振分析方法,吸收国内最新研究成果而发展的一套计算机辅助工程软件。     

A 5-DOF Model for Aeroengine Spindle Dual-rotor System Analysis

This paper develops a five degrees of freedom(5-DOF) model for aeroengine spindle dual-rotor system dynamic analysis.In this system,the dual rotors are supported on two angular contact ball bearings and two deep groove ball bearings,one of the latter-mentioned bearings works as the inter-shaft bearing.Driven by respective motors,the dual rotors have different co-rotating speeds.The proposed model mathematically formulates the nonlinear displacements,elastic deflections and contact forces of bearings with consideration of 5-DOF and coupling of dual rotors.The nonlinear equations of motions of dual rotors with 5-DOF are solved using Runge-Kutta-Fehlberg algorithm.In order to investigate the effect of the introduced 5-DOF and nonlinear dy-namic bearing model,we compare the proposed model with two models:the 3-DOF model of this system only considering three translational degrees of freedom(Gupta,1993,rotational freedom is neglected);the 5-DOF model where the deep groove ball bearings are simplified as linear elastic spring(Guskov,2007).The simulation results verify Gupta’s prediction(1993) and show that the rotational freedom of rotors and nonlinear dynamic model of bearings have great effect on the system dynamic simula-tion.The quantitative results are given as well.     

An intelligent control method for a large multi-parameter environmental simulation cabin

The structure and characteristics of a large multi-parameter environmental simulation cabin are introduced.Due to the diffculties of control methods and the easily damaged characteristics,control systems for the large multi-parameter environmental simulation cabin are diffcult to be controlled quickly and accurately with a classical PID algorithm.Considering the dynamic state characteristics of the environmental simulation test chamber,a lumped parameter model of the control system is established to accurately control the multiple parameters of the environmental chamber and a fuzzy control algorithm combined with expert-PID decision is introduced into the temperature,pressure,and rotation speed control systems.Both simulations and experimental results have shown that compared with classical PID control,this fuzzy-expert control method can decrease overshoot as well as enhance the capacity of anti-dynamic disturbance with robustness.It can also resolve the contradiction between rapidity and small overshoot,and is suitable for application in a large multi-parameter environmental simulation cabin control system.     

基于等高线图与小波变换的3D地形匹配算法研究

提出一种新的基于边缘的3D地形匹配算法。在算法中，一种结构紧凑的特征“等高线图”，用于表示参考高程图(DEM)及从实时数据恢复的高程图，这样3D地形匹配转化为基于等高线的匹配，即边缘(平面曲线)匹配问题。在边缘匹配过程中，首先用一种具有平移，旋转，尺度不变性的规范化小波描述子描述边缘。其次提出了一种基于小波系数域的快速边缘匹配算法，并分析了运算复杂性。由匹配成功的边缘对提取控制点的坐标。讨论了图像变换模型及基于最小均方根误差准则的图像变换参数估计方法。用真实地形实验表明该算法匹配精度高，计算速度快。最显著的特点是该算法抗噪声能力强。     

潜入式摆动喷管两相内流场数值模拟

气相采用三维薄层近似N-S方程，固相采用拉格朗日坐标系下颗粒轨道模型，计算方法采用显式ENO差分格式和分区多块网格技术，建立了固体火箭发动机内流场模拟软件。对轴对称JPL喷管进行模拟，计算结果与文献进行比较，符合较好。推广到实际三维装药型面时，发现颗粒数目增加导致计算效率降低。采用软件中的气相计算模块对潜入式摆动喷管内流场进行数值模拟，比较了喷管摆动角在发动机喉道附近引起流动变化，研究了非对称流动对喷管内表面压强的影响。     

20CrNi2Mo齿轮传动轴局部剥落失效分析

通过对20CrNi2Mo齿轮传动轴料齿轮局部剥落处进行宏观分析和微观断口分析，对比剥落处与完好处的宏观硬度与显微硬度分布以及金相组织和渗层深度，结合磁粉探伤检验结果，结果表明，齿轮轴经过渗碳热处理，在随后的机械磨齿过程中，由于磨削过多，致使渗层只有0．5mm，达不到技术要求，齿轮在交变接触应力的作用下，首先在齿面产生极小的显微裂纹，小裂纹进一步扩展，最终造成齿面剥落，此失效为接触疲劳失效导致的局部剥落。     

弹性飞机平衡的阵风外载荷计算与分析

连续紊流是适航规范中阵风载荷分析必须考虑的一种阵风模型,但其引起的阵风载荷在飞机结构设计中的应用一直存在困难.在平稳随机过程的假设下,基于von Karman连续紊流功率谱模型和线性系统连续紊流响应的功率谱方法,使用载荷累加法获得外载荷形式的阵风载荷.在此基础上,通过引入载荷响应的相关性推导并建立了一种生成多组连续紊流平衡外载荷分布的方法.垂向连续紊流情况下的算例结果表明:连续紊流外载荷分布是全机平衡的.平衡的外载荷分布可通过机动飞行载荷分析中的载荷包线方法识别载荷设计情况,从而应用于飞机结构的强度分析与设计.     

基于神经网络的电磁干扰的预测

提出了一种应用神经网络预测电磁干扰的方法.针对遗传算法总体搜索能力较强但容易陷入局部最优,而模拟退火算法具有较强的局部搜索能力,又能避免搜索陷入局部最优解的特点,将模拟退火算法与遗传算法相结合,优化多层前馈(BP, Back Propagation)神经网络,获取最优的权值和阈值,并采用模拟退火的思想确定隐含层神经元的个数,进而建立基于神经网络的电磁干扰预测模型.以双平行导线间的电磁干扰问题为实例,明确干扰要素,建立训练样本和测试样本,对比期望输出和预测输出之间的误差,结果表明该方法可以准确有效地进行电磁干扰预测.