The STEREO IMPACT Boom

An essential component of the STEREO IMPACT investigation is its nearly 6 m long boom that provides several of the instruments with a sufficiently clean magnetic environment and minimally restricted fields of view, while having the required rigidity to ensure the spacecraft pointing accuracy for the STEREO imaging investigations. Details of the customized telescoping IMPACT Boom design, construction and testing are described in this review. The successful completion and verification of the IMPACT Booms represents a demonstration of the use of Stacers as motive forces for rigid boom deployment.     

军用涡轮螺旋桨飞机内部装饰降噪设计与试验研究

叙述了涡轮螺旋桨飞机的噪声来源及主要传播途径 ,阐述了舱内噪声的控制与降噪设计原理 ,并进行了降噪试验研究     

固体发动机药柱燃速估算的试验研究

本文叙述了由112mm发动机估算880mm发动机药柱燃速的试验研究.经统计分析,给出了大、小发动机药柱燃速之间的三个关系式,以及相应的估算误差.采用有效燃速可使估算误差t·S_y/(?)(%)减小至1.5%左右.     

Shock Tube Instrumentation Techniques for Study of Hypervelocity Entry Problems

Shock tube instrumentation techniques developed for the study of convective heat transfer and the radiative properties of high temperature gases at conditions simulating hypervelocity entry into planetary atmospheres are described. An electrically heated helium driven shock tube is used; measurement methods suitable for conventional shock tubes must be modified before they can be used in the hypervelocity shock tube. Extremely high shock velocities necessary for proper simulation are associated with very short test times imposing requirements for fast response instrumentation systems. Methods for evaluating test gas quality are illustrated. Techniques described have been applied to several studies; typical results are shown and instrumentation requirements for the extension of aerothermodynamic investigation in the hypervelocity regime are outlined.     

Noise effects on centroid tracker aim point estimation

An investigation of errors due to noise in centroid tracker aim-point estimation is presented. The centroid tracker discussed is similar to the tracker described by A.L. Gilbert et al. (1980). Simplifications to this algorithm were made so that the derived models would be consistent with the actual tracker algorithm. Two statistical models are derived which relate image noise effects to computation of the target centroid. The first model, the simplified aim-point error model, is derived by assuming that the probabilities of incorrectly classifying target and background pixels are equal. The second model, the extended aim-point error model, is derived by assuming that the probability of incorrectly classifying a target pixel can differ from the probability of incorrectly classifying a background pixel. These models are described and their mathematical implication is discussed. Simulation results which verify the models are presented     

Performance of Likelihood Ratio Processors

Summarized by its ROC curve, the performance of a Bayes optimal detector is a function of two joint a priori probability density functions on the uncertain parameters involved. An investigation is made to determine at what point in the generation of an ROC curve for a given pair of priors sufficient information is retained for the calculation of a new ROC based on a different pair of priors.     

TECHNIQUE USED INDETECTING EXTRANEOUS HARMONICS FOR VARIABLE SPEED CONSTANT FREQUENCY（VSCF）POWER SUPPLY

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用Walsh函数方法的阶梯波式DC/AC变换器的设计与实现

讨论了阶梯波式 DC/AC变换器的一种新的设计与实现方法 ,即用 Walsh函数方法及矢量合成原理分析、综合和设计。试验结果表明实现了逆变器结构的简化及其输出电压频率稳定 ,幅值便于调节与自动稳定。给出了有关硬件、软件框图与说明、试验结果及进一步设想     

Analysis of Multimodal Systems

The estimation of a multimodal linear system whose mode-to-mode transitions are described by a finite-state Markov chain is described. The problem has application in studying separation standards in an air traffic control environment. An optimal solution is formulated which is computationally infeasible. A suboptimal estimator is then derived which closely approximates the optimal estimator. An example is presented to illustrate the technique.     

Electrical power on a 30 kW space-based radar satellite

An electrical power system for a space-based radar satellite is described. When the radar is on, its transmitter needs an average DC power of 30 kW. The problem of distributing the power efficiently in pulses to many transmit/receive modules is addressed. System requirements include a high-voltage battery and transmission line, load-sharing between the solar array, and the battery during sunlit periods, and a 25-kW solar array. A scaled-down version of the power system for a proof-of-concept demonstration is described     

Evaluation of built-in test

Built-in test (BIT) provides fault finding as a means to aid in system assembly, test, and maintenance. An investigation to evaluate BIT of a particular electronics board used in the in-flight entertainment system for Boeing 777s is described. We found BIT proved useful when failure occurrences were uniquely associated with the operating environment, situations which can result in no-fault found, or could-not duplicate (CND) failures upon test. We also observed cases where the BIT failed to observe failures, and in some cases pointed to the wrong cause of failure. These and other advantages and disadvantages of BIT implementation are discussed     

燃油在稳定器尾缘的二次雾化研究

本文总结了激光测雾仪测定稳定器尾缘燃油二次雾化分布的结果,描述了其特点,研究了影响二次雾化的主要因素,探讨了稳定器尾缘二次雾化机理及其对燃烧性能的影响。      

GTE gas temperature determination with the use of indirect measurements

An algorithm for indirect measurement of difficult-to-measure GTE parameters on the basis of its mathematical model is described. Different principles of constructing GTE gas temperature meters based on indirect measurements are considered and simulation results are presented.     

飞行管理计算机ATE综合测试系统设计

介绍了对飞行管理计算机进行自动测试的ATE8000系统。重点描述了系统的硬件组成及各部分功能、测试软件的组成、测试流程和实现方法。该系统较好地满足了测试手册的要求。     

基于真空羽流试验的洁净真空系统设计

研制的洁净真空系统可用于真空羽流试验及热真空试验研究.详细介绍了真空系统的组成、方案设计及工作模式;计算了不同工作模式下的真空抽气时间;分别对罗茨泵机组、分子泵及低温泵进行了容器极限抽速测试,测试结果表明,满足技术指标;最后对真空容器压力维持能力进行了测试,测得容器平均压升率为0.111Pa/h,对应的平均漏气率为7.24Pa·L/s,真空容器达到了较高的工艺水平.真空系统有多种工作模式供选择,可根据试验需求及故障模式选取,增加了“真空羽流效应实验系统”运行的实用性和经济性.      

二元紊流发生器实验研究

本文给出了二元紊流发生器实验研究的结果,对不同文氏管通道型面所提供的一些典型的出口流场作了分析,并对某些工作状态下的激波振荡的特征作了介招。紊流发生器出口边界条件可以是音速出口,也可以是等压出口,尽管这方面的区别对于激波振荡特征以及分离包的尺度有显著的影响,但是对于出口流场的影响却是令人惊奇地微不足道。紊流发生器中常使用的提供总压图谱的畸变网可以使出口紊流度大幅度衰减。如果采用模拟板来代替畸变网,这一情况卽可以避免。     

Optimum Constrained Image Restoration Filters

An optimum image restoration filter is described which minimizes the radius of gyration of the corrected or composite system point-spread function subject to constraints on the radius of gyration of the restoration fitter point-spread function, the total noise power in the restored image, and the shape of the composite system frequency spectrum. The filter function is obtained as the solution to a set of simultaneous differential equations subject to nonlinear integral constraints. Except for an assumption regarding the general shape of noise spectral density, the filter design is data independent. By constraining the radius of gyration of the restoration filter point-spread function, truncation errors resulting from edge effects are controlled. An iterative technique is introduced which virtually eliminates the sidelobes of the composite system point-spread function. The resulting suboptimal restoration filter effectively suppresses undesirable secondary oscillations which may otherwise appear in the composite system point-spread function and introduce "ghosts" in the restored data. A detailed study of the restoration filter performance as a function of its parameter variations is described and a number of examples are provided to demonstrate the fundamental properties of the restoration filter.     

Periodic Job Scheduling in a Distributed Processor System

This investigation considers the problem of the nonpreemptive scheduling of a set of independent periodic jobs in a computer system characterized by a collection of processors, memories, and interconnection mechanisms. Such a collection of resources can be used to perform the functions of a process control environment as are found, for example, in the avionics of a military or commercial aircraft. The distribution of these resources permits weight, volume, power, cost, and reliability requirements to be satisfied. Each periodic job is characterized by its frequency and its execution time. The inverse of the frequency, the period, is assumed to be an integer, and the initiation time and the completion time of job must be strictly met. An optimal algorithm is developed for a job set whose members are related by a binary frequency distribution. That is, if the jobs in the set are ordered in terms of decreasing job execution frequency, then fi = 2fi+1. The optimal result is generalized to include conditions in which the jobs are related by fi = kfi+1, where k is an integer.     

非线性飞机参数化模型与控制有效率的实时检测

针对非线性飞机方程的控制有效率进行了故障检测与诊断，通过将吹风表格数据处理成一种参数化非线性函数，找出了飞机状态量与控制律分离的控制有效率表达式和检测方法，算法中将检测结果与对应故障模式进行了分类处理，提高了算法的鲁棒性，最后用飞机的实例进行了仿真验证，结果表明，该算法具有较高的检测精度和较快的检测速度。     

基于MORT的航空维修工程调查系统设计

针对目前航空维修企业工程调查管理现状，提出应用MORT分析技术建立航空维修工程调查系统，分析设计了该系统的总体框架，应用知识库原理设计了系统的数据库结构和相关数据表，阐述了具体事故的分析推理过程，提出在维修管理中应用假设风险的理念。具体事故的分析结果表明，所设计的系统切实可行，可以应用到具体的维修管理中。