基于节点方程的舰船电力系统数学建模

针对舰船电力系统的特点,建立了发电机、电动机等负载的电流微分方程组,并推导出其导纳、剩余电流微分量的表达式.根据基尔霍夫电流定律,建立了基于节点电流微分平衡关系的节点方程.在系统数学建模基础上,得到了舰船电力系统动态过程的计算方法.     

各向异性介质体目标电磁散射分析的快速算法

利用体积分方程矩量法(MoM)及其多层快速多级子算法(MLFMA)研究了各向异性的电介质体或/和磁介质体目标的电磁散射问题,将多层快速多级子算法的计算结果与解析方法(Mie)或矩量法结果进行了对比分析.不但验证了MLFMA算法的高效性和精确性,同时该算法还适合于分析模拟任意复杂介质体(如各向异性磁化等离子体)目标的电磁散射问题,为进一步实现电大尺寸的任意复杂各向异性介质体/金属组合目标电磁散射分析的精确高效算法奠定了基础.     

穿浪双体船尾板减阻数值分析

基于RANS方程,采用RNG k-ε湍流模型和VOF两相流模型,研究了尾板长度与安装角度对穿浪双体船总阻力的影响规律.计算结果表明:尾板可以调整穿浪双体船的航态,达到有效降低阻力的目的;减阻在一定速度范围内有效,减阻的效果取决于尾板安装角度和长度,但阻力的减少并不与安装角度和长度成比例,最佳的安装角度约为3°～6°,长度约为1％～2％ LWL.     

基于非齐次线性方程组的认证协议的研究

认证技术是信息安全理论与技术的一个重要方面.认证技术主要包括用户认证和信息认证2个方面.前者用于鉴别用户身份,后者用于保证信息的真实来源.本文基于线性代数的方程组的解的理论建立了一种身份认证协议和一种消息认证协议.通过安全性分析结果表明这个新的身份认证协议能够保证用户身份的正确认证,新的信息认证协议能够保证数据的机密性、完整性,同时能够防止重传攻击认证信息来源.     

Approximations and empirics for stochastic war equations

The article develops a theorem which shows that the Lanchester linear war equations are not in general equal to the Kolmogorov linear war equations. The latter are time‐consuming to solve, and speed is important when a large number of simulations must be run to examine a large parameter space. Run times are provided, where time is a scarce factor in warfare. Four time efficient approximations are presented in the form of ordinary differential equations for the expected sizes and variances of each group, and the covariance, accounting for reinforcement and withdrawal of forces. The approximations are compared with “exact” Monte Carlo simulations and empirics from the WWII Ardennes campaign. The band spanned out by plus versus minus the incremented standard deviations captures some of the scatter in the empirics, but not all. With stochastically varying combat effectiveness coefficients, a substantial part of the scatter in the empirics is contained. The model is used to forecast possible futures. The implications of increasing the combat effectiveness coefficient governing the size of the Allied force, and injecting reinforcement to the German force during the Campaign, are evaluated, with variance assessments. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

非定常超音速流动数值计算方法比较

为适用于非定常流场计算 ,在保证时、空二阶精度的前提下 ,通过引入变系数残值光顺技术 ,提高了四步Runge Kutta方法的计算效率 ;并针对球锥简谐振动过程 ,数值比较Runge Kutta多步法和“双时间法”的计算精度。     

旋转弹丸空气动力特性数值解法

为提高在弹道计算和弹丸设计中弹丸空气动力系数精度,采用隐式LU算法求解N S方程并考虑代数湍流模型,在旋转物面边界条件下计算弹丸的阻力、升力、俯仰力矩、滚转阻尼力矩、马格努斯力和力矩。通过对美国T388等弹丸的气动力系数计算并与弹道靶试验数据进行比较,以及对某榴弹的气动力计算结果在弹道计算中进行应用分析,表明用数值模拟得到的旋转弹丸空气动力系数好于以前用工程方法给出的结果。     

三对角方程组的分布式SPP算法

发展了单向并行分裂法(SPP)用于求解三对角和块三对角线性方程组,算法考虑了三对角线性系统求解中文件IO及结果传输通信所占时间比例较大的特点,充分利用了计算、文件IO与通信三者之间的重叠。分析了SPP算法的计算与通信开销。在工作站机群上进行了测试分析,结果表明SPP算法适合于分布式计算     

正扰动下一类RN上临界增长的椭圆型方程的正解的存在性

本文讨论了如下方程:并得到了它的正解的存在性,其中g(x,U)为U~(P-1)的低阶扰动。它是文[1]的继续。     

Applying Lanchester's linear law to model the Ardennes campaign

In modern warfare, many believe the decisive factor in winning a battle is seizing the right moment to shift from defense to attack, or vice versa. This paper attempts to bring that perspective to Lanchester's differential equations of warfare, and continues the application of Lanchester's linear law to the analysis of the World War II battle of Ardennes, as reported in earlier issues of Naval Research Logistics by Bracken and by Fricker. A new variable, shift time, accounting for the timing of the shift between defense and attack is explicitly included in our version of the model, and it helps obtain improved goodness of fit to historical data. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48:653–661, 2001