电磁轨道发射器动态发射过程的数值模拟

针对电磁轨道发射器动态发射过程的数值模拟问题,基于矢量磁位A和时间积分标量电位V,采用节点单元法,并选择运动坐标系描述运动问题,推导出动态发射下的电磁轨道发射器三维涡流场有限元离散方程。结合温度场控制方程,建立电磁轨道发射器的三维电磁-温度耦合有限元模型。针对一个电磁轨道发射器动态发射问题,对模型进行数值模拟,得到了动态发射下轨道及电枢的温度场分布特点及发射器电感梯度随时间的变化规律。计算结果表明,模型计算出的脉冲电流峰值、出口电流大小、出口速度等参数均与试验结果吻合较好,验证了所开发的有限元程序代码的正确性。     

三关节机器人的神经网络补偿自适应控制器设计

三关节机器人广泛用于工业生产、轮式或履带式排爆机器人,为了补偿由于机器人结构参数、作业环境干扰等不确定性因素造成的机器人动力学模型的不确定性,将机器人动力学模型分解为名义模型和误差模型两部分,其误差模型采用RBF神经网络进行补偿,得到其估计信息,神经网络的输出权值根据Lyapunov稳定性理论采用自适应算法进行调整。所设计的神经网络补偿自适应控制器解决了不确定性机器人动力学系统控制器设计的不确定性问题,同时,通过定义Lyapunov函数,证明了控制器能渐近、稳定地跟踪期望轨迹。机器人的3个关节在控制器的作用下,约在5 s时达到期望轨迹,神经网络约在5 s时逼近机器人动力学模型的误差模型,实验结果表明了机器人关节对期望轨迹具有良好的轨迹跟踪性能。     

履带车辆动力性仿真研究

为仿真履带车辆动力性,建立了动力性评价指标的仿真模型,并以某型车为实例,应用Matlab语言编程计算得出理论值,通过与试验值比较验证了模型的有效性和准确性。     

一种防空自动化系统效能的模糊综合评估方法

针对防空自动化系统的组成,给出了防空自动化系统效能的指标体系,并通过分析防空自动化系统静态效能和动态效能的关系,运用模糊综合评估和系统性能评价等级划分的方法,在防空自动化系统静态效能评估的基础上,研究了防空自动化系统的动态效能,提出了一种静态效能与动态效能相结合的防空自动化系统模糊综合评估方法。     

基于动态逆的无人机机动控制律设计

针对现代无人机机动性的需求,基于动态逆系统理论,提出一种适合小型无人机机动指令跟踪的非线性控制方法,分别设计了慢变量和快变量动态逆控制律,并通过对无人机航迹倾斜角的实时导引控制,进一步提高无人机的整体机动性.仿真结果表明,基于动态逆的航迹倾斜角反馈控制能够达到期望的机动效果,具有良好的指令跟踪性能.该控制律可应用于无人侦察机规避高空障碍,具有重要的现实意义.     

Coordination of pricing and inventory control across products

We consider the joint pricing and inventory‐control problem for a retailer who orders, stocks, and sells two products. Cross‐price effects exist between the two products, which means that the demand of each product depends on the prices of both products. We derive the optimal pricing and inventory‐control policy and show that this policy differs from the base‐stock list‐price policy, which is optimal for the one‐product problem. We find that the retailer can significantly improve profits by managing the two products jointly as opposed to independently, especially when the cross‐price demand elasticity is high. We also find that the retailer can considerably improve profits by using dynamic pricing as opposed to static pricing, especially when the demand is nonstationary. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

Dynamic signatures and their use in comparing the reliability of new and used systems

The signature of a system with independent and identically distributed (i.i.d.) component lifetimes is a vector whose ith element is the probability that the ith component failure is fatal to the system. System signatures have been found to be quite useful tools in the study and comparison of engineered systems. In this article, the theory of system signatures is extended to versions of signatures applicable in dynamic reliability settings. It is shown that, when a working used system is inspected at time t and it is noted that precisely k failures have occurred, the vector s [0,1]^n‐k whose jth element is the probability that the (k + j)th component failure is fatal to the system, for j = 1,2,2026;,n ‐ k, is a distribution‐free measure of the design of the residual system. Next, known representation and preservation theorems for system signatures are generalized to dynamic versions. Two additional applications of dynamic signatures are studied in detail. The well‐known “new better than used” (NBU) property of aging systems is extended to a uniform (UNBU) version, which compares systems when new and when used, conditional on the known number of failures. Sufficient conditions are given for a system to have the UNBU property. The application of dynamic signatures to the engineering practice of “burn‐in” is also treated. Specifically, we consider the comparison of new systems with working used systems burned‐in to a given ordered component failure time. In a reliability economics framework, we illustrate how one might compare a new system to one successfully burned‐in to the kth component failure, and we identify circumstances in which burn‐in is inferior (or is superior) to the fielding of a new system. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

火控系统动态精度环绕测试设计方法

借鉴环绕BIT技术的思想,提出一种火控系统动态精度环绕测试的设计方法.该方法充分利用火控计算机的固有资源,通过增加少量接口转换电路(一组现在点坐标输出接口和一组射击诸元输入接口),来提高火控系统动态精度检查测试性水平.对于采用环绕测试设计的火控系统,只需使用两根外接电缆,无须外接检测计算机,即可完成动态精度检查的任务,从而显著降低了操作复杂性.该设计方法的一个优点是不会影响系统的可靠性.     

舰炮武器系统动态误差检测方法

舰炮武器系统动态误差是系统动态性能的重要指标,精确测量舰炮武器系统动态误差一直是比较困难的问题,提出一种比较先进的动态误差测量方法,可以按给定间隔时间连续测量和录取舰炮不稳定方向瞄准角和高低瞄准角动态误差,监测系统的动态过程.对舰炮武器系统动态检测和调试,提高系统射击精度有较大的现实意义.     

多操纵面战斗机动态控制分配策略研究(英文)

现代先进飞机配置多个操纵面且又冗余,这有利于实现非常规飞行,提高飞机敏捷性,使飞机在机动和故障时有更多的选择,但是同时也导致了飞机控制设计复杂度的增加.为了达到更好的效果,就必须利用控制分配器来充分利用多操纵面的不同带宽.从频率域角度出发,研究了动态控制分配方法,并将其应用于某型先进战斗机的控制分配器设计中,利用鸭翼的频率特性抵消府舱过载,经仿真验证,采用动态控制分配策略时,可以有效地减小座舱过载,同时还可以减小配平阻力,取得了良好的控制效果.