超视距协同空战信息协同效果评估模型

为解决超视距协同空战中的信息协同效果评估问题,结合信息协同度的概念以信息协同范围、协同信息强度和协同信息质量3个方面作为一级指标建立了信息协同评估指标体系,并依据超视距协同空战特点对各指标进行了量化处理;基于该指标体系建立信息协同评估模型,具体以预警机指挥引导下超视距协同空战感知网络的信息协同度量进行了实例验证,分析结果表明分布式指挥结构较树型指挥结构更能体现信息协同效果。     

小尺寸应变天平设计方法研究

Φ0.3m高超声速低密度风洞测力试验模型尺寸小、天平载荷小、流场总温高,天平防热结构设计难,刚度要求和灵敏度要求矛盾突出,测力天平的研制难度大。采用数值仿真和风洞试验相结合的研究方法,对应用于该情况下的内式天平在温度影响和结构设计方面进行了研究。采用有限元方法对天平温度影响和结构应力分布做了详细分析,并对分析结果进行了风洞试验验证。结果表明：在实现天平结构优化设计及提高天平设计的准确性和可靠性方面,有限元分析设计方法是非常有效的技术途径。     

接触摩擦力对叶片减振能力的影响

在频域内利用谐波平衡法,分别通过理论分析和有限元分析方法对某涡轮叶片缘板-阻尼结构进行了减振效果分析,并就接触摩擦力对叶片减振能力的影响进行了进一步探索.研究发现带阻尼装置叶片由于阻尼块附加质量作用,对叶片有明显的避振作用,并也起到了一定的减振作用,但对叶片振动响应耗能影响最大的是叶片缘板-阻尼装置接触面的非线性摩擦力,且摩擦系数较小时叶片减振效果对其变化更敏感一些.另外从分析方法探索中发现,含接触等非线性问题的结构,忽略接触特性进行振动响应分析具有较大的偏差性.这些研究结论和研究方法可为阻尼结构的设计提供一定的参考.     

Modified fast Fourier transform in FBMC for satellite communications

In this paper,a Doppler scaling fast Fourier transform (Doppler-FFT) algorithm for filter bank multi-carrier (FBMC) is proposed,which can efficiently eliminate the impact of the Doppler scaling in satellite communications.By introducing a Doppler scaling factor into the butterfly structure of the fast Fourier transform (FFT) algorithm,the proposed algorithm eliminates the differences between the Doppler shifts of the received subcarriers,and maintains the same order of computational complexity compared to that of the traditional FFT.In the process of using the new method,the Doppler scaling should be estimated by calculating the orbital data in advance.Thus,the inter-symbol interference (ISI) and the inter-carrier interference (ICI) can be completely eliminated,and the signal to interference and noise ratio (SINR) will not be affected.Simulation results also show that the proposed algorithm can achieve a 0.4 dB performance gain compared to the frequency domain equalization (FDE) algorithm in satellite communications.     

爆破战斗部对超音速导弹毁伤效应研究

通过对不同弹目相对距离、交会角工况下,爆破战斗部冲击起爆超音速导弹战斗部临界距离和结构毁伤发动机舱效应的数值模拟计算,研究、评估了爆破战斗部爆炸产生的冲击波和爆轰产物对超音速导弹的毁伤效应。结果表明:爆破战斗部对超音速导弹的毁伤以结构毁伤为主,冲击起爆超音速导弹战斗部能力较弱;爆破战斗部对超音速导弹发动机舱的毁伤效应,随弹目相对距离的增加而迅速减小;弹目相对距离相同时,各工况下的毁伤效应,先随弹目交会角的增大而增大,而后随弹目交会角的增大而减小。     

小电阻对测量结果的影响

电阻是电路的基本物理参数,电阻很小时,分析计算常忽略不计.但在许多场合下如果忽略电路中存在的小电阻,将会带来测量结果的不准确,此时必须消除小电阻影响.文中介绍了几种不同测量环境下微小电阻对测量结果的影响及消除方法.     

激波加速的密度分层流体交界面的演化

采用了自适应的非结构网格和基于有限体积法的二阶Godunov格式，数值模拟了在不同强度的激波作用下两种不同密度流体交界面的演化过程，详细给出了交界面上由于斜压效应产生的涡列的演化过程。     

Blockage effect on the flow around a cylinder probe in calibration

Flow around a 2-D cylinder pressure probe placed in uniform flow,free jet flow,and wind tunnel flow was analyzed with potential flow theory and simulated with numerical method.Blockage effect was investigated under several typical flow Mach numbers.The result from numerical simulation shows a similar trend to the one from potential flow method while varies in quantity.Wind tunnel walls accelerate the flow near the probe and thus produce a blockage effect;Boundary of free jet flow,however,decelerates the flow and thus produces a "negative" blockage effect.A maximum incoming Mach number exists when the probe is calibrated in wind tunnel in high subsonic condition due to choking caused by shocks and shock induced separation.The critical Mach number varies with blockage ratio,which makes high Mach number impossible to achieve in large blockage ratio condition.The blockage effect itself is unavoidable for calibration or measurement although a sufficiently small blockage ratio brings minor effect.Correction can be implemented based on the numerical simulation result presented in this paper and further works.      

Positioning error compensation for parallel mechanism with two kinematic calibration methods

Compared with serial mechanisms, the parallel mechanism (PM) theoretically exhibited higher positioning accuracy, dynamic performance, strength-to-weight ratio, and lower manufacturing cost, but they had not been widely used in the practical application. One key issue, positioning accuracy, which directly affected their performance and was greatly influenced by the errors of kinematic structure parameters was analyzed. To effectively enhance the positioning precision of PMs, a novel modeless kinematic calibration method, namely the split calibration, was presented and its compensation effect of the positioning error was comprehensively compared with that of an integrated method on two different types of PMs. A strange phenomenon-correct and incorrect identified results were derived from two different PMs by the same integrated method, respectively-which had not been reported yet was discovered, and the origin of it was revealed utilizing numerical simulations. Finally, respective merits and drawbacks of these two methods obtained in this paper provided underlying insights to guide the practical application of the kinematic calibration for PMs.