均匀圆阵主特征矢量分析解相干算法

为解决均匀圆阵的相干信源波达方向估计问题,提出一种适用于均匀圆阵的虚拟均匀线阵主特征矢量分析算法.采用模式空间变换将均匀圆阵转换为虚拟均匀线阵,对其数据协方差矩阵进行处理以构造主特征矢量矩阵;引入加权最小二乘法,通过重复迭代得到子空间各元素之间的线性预测系数,从而求得相干信源的波达方向估计值.理论分析和仿真结果表明,该...     

一维非均匀分布参数系统的渐近传递函数方法

提出了一维非均匀分布参数系统的一种通用解法：渐近传递函数方法。对一般的一维非均匀分布参数系统，引入状态变量将控制方程及边界方程写成状态空间形式。通过定义小参数和摄动方法，使之变成常系数微分方程，从而得到问题的摄动解。各阶摄动解均具有规范的形式，是一以传递函数为积分核的积分形式解析解。文中最后给出了一些数值算例，验证了方法的有效性。     

极化域-空域联合估计在反辐射导弹抗诱偏中的应用研究

提出了将极化阵列应用到反辐射导引头上,导引头利用目标与诱饵的极化差异,采用极化域-空域联合估计方法抗诱偏。首先,利用波达方向矩阵法,估算出雷达与诱饵的空间二维到达角和极化参数,将估算出来的二维到达角信息为反辐射导引头提供导引,极化参数用来鉴别雷达与诱饵,从而达到抗诱偏的目的。然后,结合导弹运动方程及导引方程对反辐射导弹抗三点源诱偏进行了全弹道数字仿真,并且采用Monte-Carlo方法对全弹道仿真进行了多次实验,仿真结果证明了将极化域-空域联合估计应用于反辐射导引头抗诱偏的可行性。     

A heuristic for maximizing the number of on‐time jobs on two uniform parallel machines

We consider the problem of maximizing the number of on‐time jobs on two uniform parallel machines. We show that a straightforward extension of an algorithm developed for the simpler two identical parallel machines problem yields a heuristic with a worst‐case ratio bound of at least . We then show that the infusion of a “look ahead” feature into the aforementioned algorithm results in a heuristic with the tight worst‐case ratio bound of , which, to our knowledge, is the tightest worst‐case ratio bound available for the problem. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

Polarization visualization for low-irradiance regions by perceptually uniform color space

Currently,polarization visualization strategies are accomplished by mapping polarization information into a perceptually uniform color appearance model CAM02-UCS.However,the deviation of the CAM02-UCS space from the lightness prediction results in an inaccurate match between the polarization in-formation and the perceptual information.In this paper,we propose a novel polarization visualization strategy based on the perceptual uniform space Jzazbz.The polarization visualization be completed by placing the polarization information into the lightness Jz,colorfulness Cz and hue angle hz channels of the Jzazbz space.The experimental results show that the proposed method can significantly improve the lightness of the low irradiance and high polarization region,hence more polarization information can be sensed by human visual system.     

基于DRFM的匀加速距离门拖引干扰信号的频谱分析

研究了基于DRFM的匀加速距离门拖引干扰信号的频谱。由于DRFM的离散化采样,导致干扰信号频谱有两个明显特征。首先,频谱相对于中心频率会出现微小可测的频移;其次,频谱由菲涅尔谱及其周期性的谐波组成,且在特定情况下会出现频谱的交叠。首先推导了匀加速距离门拖引的时域表达式并分析其频谱,并从理论上得出频移、谐波中心的位置以及频谱交叠的条件。最后通过对时域信号的fft仿真,验证所作理论推导的正确性。     

均匀试验设计在无人机关键参数设计中的应用

针对所采用CFD软件FLUENT对无人机的气动特性数值模拟,消耗大量时间这一问题,进行了试验设计,来减少试验次数。首先对各种常见的试验设计方法的优点局限性及试验次数进行了全面而详细的分析与总结,然后选取了均匀试验设计的方法来安排试验,实践了均匀试验设计在无人机关键参数设计中应用的案例,并通过曲线拟合建立了相应的模型,对均匀试验设计的可行性进行了验证。     

Solving generalized transportation problems via pure transportation problems

This paper investigates certain issues of coefficient sensitivity in generalized network problems when such problems have small gains or losses. In these instances, it might be computationally advantageous to temporarily ignore these gains or losses and solve the resultant “pure” network problem. Subsequently, the optimal solution to the pure problem could be used to derive the optimal solution to the original generalized network problem. In this paper we focus on generalized transportation problems and consider the following question: Given an optimal solution to the pure transportation problem, under what conditions will the optimal solution to the original generalized transportation problem have the same basic variables? We study special cases of the generalized transportation problem in terms of convexity with respect to a basis. For the special case when all gains or losses are identical, we show that convexity holds. We use this result to determine conditions on the magnitude of the gains or losses such that the optimal solutions to both the generalized transportation problem and the associated pure transportation problem have the same basic variables. For more general cases, we establish sufficient conditions for convexity and feasibility. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 666–685, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10034     

纯时滞三种群捕食系统持续生存与全局吸引性

研究了具有HollingⅡ功能性反应的纯时滞的两捕食者、一食饵生物系统,通过构造合理的Lyapunov函数讨论了系统的全局吸引性,并得到系统持续生存的充分条件。     

基于均匀设计的临近空间无动力攻击器运动参数响应面建模

为探求临近空间无动力攻击器运动参数的解析模型,采用均匀设计试验方法,以攻击器发射参数为设计变量,从设计空间中选择一些特定的设计点,构造了临近空间攻击器速度、射程以及飞行时间的响应面模型。通过仿真算例,对各响应面模型分别进行显著性检验,证明了所建立的响应面都具有较高的近似精度。