空间飞行体与压缩区内等离子体非稳态相互作用的控制方程

本文详细研究了压缩区内飞行体与等离子体之间的非稳态相互作用，得到了这种相互作用的控制方程。作为辐射源的飞行体天线系统，可以激发出可探测到的电磁弧波。带电粒子密度扰动对电磁弧波的影响表现为一个振幅的衰减因子。这表明，可通过对这种电磁弧波的探测而发现隐身飞行体的踪迹。     

Investigation of straightforward impedance eduction method on single-degree-of-freedom acoustic liners

In order to address the current aircraft noise problem, the knowledge of impedance of acoustic liners subjected to high-intensity sound and grazing flow is of crucial importance to the design of high-efficiency acoustic nacelles. To this end, the present study is twofold. Firstly, the StraightForward impedance eduction Method (SFM) is evaluated by the strategy that the impedance of a liner specimen is firstly experimentally educed on a flow duct using the SFM, and then its accuracy is checked by comparing the numerical prediction with the measured wall sound pressure of the flow duct. Secondly, the effects of grazing flow and high-intensity sound on the impedance behavior of two single-layer liners are investigated based on comparisons between educed impedance and predictions by three impedance models. The performance of the SFM is validated by showing that the educed impedance leads to excellent agreement between the simulation and the measured wall sound pressure for different grazing flow Mach numbers and Sound Pressure Levels (SPLs) and over a frequency range from 3000?Hz down to 500?Hz. The grazing flow effect generally has the tendency that the acoustic resistance exhibits a slight decrease before it increases linearly with an increase in Mach, predicted successfully by the sound-vortex interaction theoretical model and the Kooi semi-empirical impedance model. However, the Goodrich semi-empirical impedance model gives only a simple linear relation of acoustic resistance starting from Mach zero. Additionally, when the SPL increases from 110 to 140?dB in the present investigation, the acoustic resistance exhibits a significant increase at all frequencies in the absence of flow; however, the resistance decreases slightly under a grazing flow of Mach 0.117. It indicates that the SPL effect can be greatly inhibited when flow is present, and the grazing flow effect can be reduced partly as well at a relatively high SPL.     

同轴探针对称激励矩形波导模式谱图研究

文章用输入阻抗方法探讨同轴探针中心对称激励矩形波导在多模传输时所能激发的传输模式。说明采取一定的措施,可以避免产生某些高次模式。并应用分式线性变换检测法,以精心设计的实验验证了理论分析的正确性。     

多种材料双层 EFP数值仿真对比研究

以双层药型罩形成的串联爆炸成型弹丸（EFP）为研究对象，运用数值仿真软件AUTODYN，对不同材料组成的双层药型罩产生的串联EFP成型与侵彻靶板过程进行数值模拟计算。通过比较双层EFP形状、速度、长径比、动能等参数，得出内外罩材料冲击阻抗之差对于双层EFP侵彻能力的影响，其侵彻能力最强的材料组合为外钽内铝组合。     

一种航天接口芯片静电防护电路的软击穿现象

接口阻抗测试是航天产品中对产品状态是否正常来进行判断的常用方法。在航天产品应用中，通常认为接口芯片阻抗测试异常即代表该接口芯片已经失效。本文针对一种LVDS接口发送芯片由静电导致阻抗测试异常，但功能正常的现象进行分析。在元器件失效分析的基础上，定位静电损伤的位置为芯片内部静电防护电路，从而建立了对应的电路模型，对芯片静电损伤的现象进行理论分析。分析说明：该芯片在被静电打击时，其静电防护电路中一个NMOS管受损，但该电路保护了芯片的功能电路，被击穿的NMOS管等效为一个电阻，因此导致阻抗测试异常，但芯片功能电路未受损的现象，为静电软击穿现象。且可认为该芯片在受静电影响后并未失效，相关电路仍具有正常工作的能力。即阻抗异常现象并不是芯片失效的充分条件。