Passive target tracking using maximum likelihood estimation

Estimation of target trajectory from passive sonar bearings and frequency measurements in the presence of multivariate normally distributed noise, with unknown inhomogeneous general covariance, is modeled as a nonlinear multiresponse parameter estimation problem. It is shown that maximum likelihood estimation in this case is identical to optimizing a determinant criterion which has a concise form and contains no elements of unknown covariance matrix. A Gauss-Newton type algorithm using only the first-order derivatives of the model function and a new convergence criterion, is presented to implement such estimation. The simulation results demonstrate that performance of the maximum likelihood estimation method with the above noise model is superior to that with the traditional noise assumption     

星载嵌入式处理器软件在轨重配置技术研究

文章主要介绍了星载嵌入式处理器软件在轨重配置技术,给出了在轨重配置的基本原理、方法及处理流程。     

旋转带肋回转通道换热实验研究

为深入掌握高压涡轮叶片带肋回转通道在旋转状态下的换热分布,建立了旋转内通道实验系统,利用瞬态液晶测量方法研究了动叶回转内通道模型的换热机理,比较了三维数值模拟和实验的换热结果。通道入口雷诺数为5000~17000,旋转数为0~0.09,旋转半径与水力直径之比为46.4。结果表明:不同雷诺数下回转内通道的局部换热系数分布相似,局部、平均换热系数均随雷诺数增加而增大;沿程展向平均换热系数呈多波峰状分布,肋的扰动强化换热沿流向逐渐减弱;径向出流通道的努赛尔数随旋转数增加明显增大,径向入流通道的努赛尔数随旋转数的增加略有减小;哥氏力使转弯下游通道的局部换热系数改变,肋间的高换热区域由前肋的背风面附近向两肋之间偏移。     

某型压差活门的动态特性分析

压差活门是航空发动机数控系统燃油计量装置中重要的液压部件,其稳定性和动态性能直接影响控制系统的整体性能。根据压差活门非线性微分方程,采用小偏差线性化方法,推导出了压差活门的动态数学模型,得到了压差活门的方框图以及传递函数。选取某压差活门参数建立了Simulink仿真模型,分别在频域和时域分析了其动态性能。结果表明:在频域上,比较了有无节流器时的回路增益函数伯德图,认为敏感油路上的节流器可以改善稳定性且提高控制精度,通过设计节流器的尺寸可以调节穿越频域,从而改善系统的动态性能;在时域上,分析了不同节流器尺寸下阶跃响应的动态性能,其试验结果与实际工程经验一致。     

民用飞机空气起动系统性能评估方法

根据民用飞机起动系统设计特点,分别给出了起动轴功率检查和起动机进口参数检查2种起动性能评估方法,并对2种方法进行了对比,起动轴功率检查方法可以直接反映起动机轴功率的设计状态;而起动机进口参数检查方法可以直接反映出起动关键参数(流量、总温和总压)的设计状态。最后,以某型辅助动力装置供气的起动性能计算为例验证了基于起动机进口参数的计算方法。     

飞机自动着陆纵向块对角控制器设计

在阐述了块对角控制理论和分析飞机运动特性的基础上,把飞机纵向运动方程转化为块对角非线性系统,并设计了飞机自动着陆纵向块对角控制器。仿真结果表明,该控制器能够控制飞机自动着陆,跟踪性能良好。     

TDICCD时序设计在FPGA中的工程实现

文章结合TDICCD和FPGA器件特点，主要从设计目标分析，VHDL算法描述、综合、布线、仿真、代码优化、代码测试验证等几方面，阐述了TDICCD时序设计的全过程；利用同步设计的思想避免了竞争与冒险；利用RC延迟模块实现了时序的精确调整；利用模块化思想提高了代码的可重用性、可测试性、可读性。最终，实现了一个6MHz像元输出速率下能正常工作的TDICCD的成像系统。     

UWB radar for patient monitoring

During the last few years the Moscow Aviation Institute (Russia) and the Industrial Technology Research Institute (Taiwan) have worked jointly on the development of ultrawideband (UWB) medical radars for remote and contactiess monitoring of patients in hospitals. Preliminary results of these works were published in [1]. As of the present, several radars have been produced and tested in real conditions in hospitals in Russia and Taiwan. Some results of these tests are given.     

Distributed decision fusion in the presence of link failures

The problem of optimal data fusion involving detector unit communication link failures is considered. Two strategies for decision making in presence of link failures are examined and an optimal decision making scheme in the sense of the Neyman-Pearson (N-P) test is proposed. The performance of q+1 reliable links versus q reliable links are examined theoretically, as well as, numerically using the receiver operating characteristics (ROCs)     

NiAl合金的热爆合成及其反应机制

本文研究了NiAl合金的热爆合成,其反应过程为液相控制,产物为β-NiAl,密度较高。本文给出了不同条件下合成的起爆时间及主要影响因素。