转轴位置对俯仰动态特性的影响

研究了转轴位置对机翼、机身和三个组合体上翼面的动态特性的影响，对于机翼和机身，当转轴位置后移时其动态迟滞效应更为强烈。当翼面处于转轴之前，上仰时会出现更为的动态迟滞效应。因此鸭翼达到失速状态较晚。而当翼面处于转轴之后时，如尾翼，将会更早地出现动失速，转轴位置对动态迟滞特性的影响可以认为主要是由于俯仰运动时的动态洗流影响所导致的实际有效迎角的变化。由此影响了动态分离涡及其发展。     

受均匀内压作用的偏置孔边径向裂纹的应力强度因子的一种求解方法

本文利用一种新的混合法——光弹性实验与权函数解法相结合求解了孔壁受均匀内压作用偏置圆孔边径向裂纹的应力强度因子,该方法具有简单、经济、精度高等优点,对分析复杂应力场中圆孔边穿透裂纹问题,该方法同样适用,且优点更为突出.     

THE RESEARCH OF INCREASING LIFT ANDREDUCING DRAG FOR WING-TIP SAILS

ＴＨＥＲＥＳＥＡＲＣＨＯＦＩＮＣＲＥＡＳＩＮＧＬＩＦＴＡＮＤＲＥＤＵＣＩＮＧＤＲＡＧＦＯＲＷＩＮＧ－ＴＩＰＳＡＩＬＳＣｈｅｎＭｉｎｇｙａｎ，ＱｉＭｅｎｇｂｕ（ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙｏｆＡｅｒｏｎａｕｔｉｃｓａｎｄＡｓｔｒｏｎａｕｔｉｃｓ，...     

壁压法在低速闭口回流式风洞中的应用

本文介绍了由Hackett提出的一种估算大攻角洞壁干扰修正的壁压信息法。并利用四个几何相似、尺寸不同的平板机翼和翼-身组合体模型在南航NH-2风洞中进行了试验。试验和计算结果表明,该方法使用方便,修正结果准确可靠。但必须指出,对于试验段下游带有平衡缝的闭口回流风洞,洞壁测压数据需经适当的修正才能获得满意的结果。     

某型飞机同时存在两种惯性耦合问题的探讨

根据稳定性理论，对某型高速飞机的惯性耦合进行初步研究，首先，对飞机的滚转－偏航耦合－俯仰耦合的机理进行分析，然后，在不影响问题本质的前提下提出了一些假设条件，将研究惯性耦合的六自由度全量方程进行简化，求出急滚稳定性判据，以某型机为例，计算出其惯性耦合特性，用急滚稳定性判据进行了分析，并进行了验证 。     

一种分析稳态压力畸变对多级轴流压缩系统稳定性影响的新方法

发展了一种分析进口稳态压力畸变对多级轴流压缩系统稳定性影响的逐级平行压缩系统模型；建立了一种稳态压力畸变进气条件下，多级轴流压缩系统对燃烧室燃油瞬时脉冲的气动响应及气动稳定性分析的新方法；导出了基于ＭａｃＣｏｒｍａｃｋ隐式格式的新的数值计算方法。应用新的模型方法对一个三级实验压气机进行了数值分析，给出了稳态压力畸变与压缩系统稳定裕度损失及不稳定发生时间之间的定量关系，定量给出了压气机失稳首发级的识别方法。     

Nondestructive Characterization of RBSOA of High-Power Bipolar Transistors

Reverse-bias safe operating area (RBSOA) of high-power Darlington transistors is characterized using a 120 A/1000 V nondestructive reverse-bias second breakdown tester designed and fabricated at Virginia Polytechnic Institute and State University. Elaborate RBSOA characteristics are generated with different forward/reverse base drives and collector current levels. The effects of elevated case temperature and second-base drive on RBSOA of four-terminal Darlington devices are also discussed.     

A Detection Algorithm for Optical Targets in Clutter

There is active interest in the development of algorithms for detecting weak stationary optical and IR targets in a heavy opticalclutter background. Often only poor detectability of low signal-to-noise ratio (SNR) targets is achieved when the direct correlation method is used. In many cases, this is partly obviated by using detection with correlated reference scenes [1, 2].This paper uses the experimentally justified assumption that most optical clutter can be modeled as a whitened Gaussian randomprocess with a rapidly space-varying mean and a more slowlyvarying covariance [2]. With this assumption, a new constant falsealarm rate (CFAR) detector is developed as an application of the classical generalized maximum likelihood ratio test of Neyman and Pearson. The final CFAR test is a dimensionless ratio. This test exhibits the desirable property that its probability of a false alarm(PFA) is independent of the covariance matrix of the actual noiseencountered. When the underlying noise processes are complex intime, similar considerations can yield a sidelobe canceler CFARdetection criterion for radar and communications. Performance analyses based on the probability of detection (PD)versus signal-to-noise ratio for several given fixed false alarm probabilities are presented. Finally these performance curves are validated by computer simulations of the detection process which use real image data with artificially implanted signals.     

DO 28飞行试验数据一致性检验

 本文研究DO28试验机飞行试验数据一致性检验及其误差校正。建立了由非线性运动学方程及内容广泛的校正环节构成的一致性检验模型,解决了大地风场重构、测量信号时间延迟估计、ψ转换及测量控制信号的校正。为DO28参数估计提供了可靠、准确的飞行试验数据。     

环向圈连带冠叶片的动态分析

 本文将动态子结构方法中链式加载技术与群论算法相结合,提出环向固连带冠叶片动力特性分析的一种新方法。文中列出了分析步骤与具体公式,并有实例的计算结果。该方方法适用于研究具有带冠叶片的单级转子中,“冠”的整体效应。