Vessel allocation by linear programming

This paper presents a linear programming model of a fleet of vessels which is required to transport quantities of cargo, such as coal, iron ore, limestone, and salt from certain producing ports to specific destination ports. This model has been implemented and is currently being used both for planning purposes and as an aid in scheduling the trips to be made by each vessel.     

Application of renewal theory to continuous sampling plans

Renewal theory is used to study the effectiveness of a class of continuous sampling plans first introduced by Dodge. This approach provides a simple way of viewing and computing the long-run Average Outgoing Quality (AOQ) and its maximum AOQL. More importantly, it is used to study the average outgoing quality in a short production run through an approximation formula AOQ^*(t). Formulas for AOQ and AOQ^*(t) are provided. By simulation, it is found that AOQ^*(t) is sufficiently accurate in situations corresponding to actual practice.     

多退化模式下的电子装备可靠性建模

通常加速退化分析中退化失效只考虑或者假设只有一个退化通道,而实际上很多情况下会存在多退化模式.产品的各个退化通道间的关系存在随机性,即任意两个退化通道间不可能只是单一的相关或者独立.在考虑这种相关性的条件下,深入研究了电子产品的性能退化理论和机理,提出了两个多退化模式竞争失效的数学模型,分别阐述了退化通道相关与独立的两种不同情况下产品可靠度评估方法.     

基于圆阵的二维DOA估计新方法

通过分析圆阵阵列流形,提出一种新的圆阵二维谱估计模型,可以直接应用MUSIC算法进行二维DOA估计,从而避免了对圆阵输出信号进行模式激励.应用此模型仿真分析了均匀圆阵和均匀半圆阵的二维DOA估计性能,相比模式激励方法,减小了计算量;半圆阵与圆阵的DOA性能差别很小,但是半圆阵减少近一半的阵元数.     

飞机电传操纵系统控制律的神经网络实现

现代多功能战机多用电传操纵系统替代传统的机械杆系,但由于飞机的多变量、强耦合和不稳定等强非线性特点,使得其电传控制律的工程实现相当复杂.为此,对电传操纵系统控制律的神经网络实现方法进行了研究.通过利用径向基函数(RBF)网络良好的非线性跟踪性能,探讨了用RBF网络实现电传控制律的一般方法,并以某型飞机电传操纵系统纵向通道为例,对该方法进行了验证.     

水平集方法中速度停止项函数的改进

对速度停止项函数的研究发现,现今的速度停止项采用的单一全局阈值法很难使经典水平集算法得到较准确的分割效果。为此,提出了一种新的速度停止项函数,该函数通过引入变阈值较好的区分了图像的边缘区与同质区,以使采用该速度停止项函数的水平集方程实现在同质区加速演化,在边缘区停止演化的目的。实验结果表明,采用速度停止项函数能够使水平集方法获取更好的分割结果。     

地基C~4I系统的高空核爆电磁脉冲易损性分析

建立了C4I系统的毁伤等级,完成了毁伤机理与毁伤模式分析,运用毁伤树分析方法构建毁伤树模型,确定了C4I系统的致命性部件,对进一步开展新型号导弹武器系统系统易损性评估研究具有一定的参考应用价值。     

Exponential size neighborhoods for makespan minimization scheduling

We investigate the quality of local search heuristics for the scheduling problem of minimizing the makespan on identical parallel machines. We study exponential size neighborhoods (whose size grows exponentially with the input length) that can be searched in polynomial time, and we derive worst‐case approximation guarantees for the local optima of such neighborhoods. The so‐called split neighborhood splits a feasible schedule into two layers, and then recombines the two layers by finding a perfect matching. We show that the makespan of every local optimum for split is at most a factor of 2 away from the globally optimal makespan. We then combine the split neighborhood with two neighborhoods from the literature. The combination of split with the jump neighborhood only marginally improves the approximation guarantee, whereas the combination with the lexicographic‐jump neighborhood decreases the approximation guarantee from 2 to 3/2. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

基于信息模型的C4ISR系统需求集成方法

多视图需求工程中"分而治之"的需求开发方式,必然会产生"需要集成"和"如何集成"等问题.研究了基于多视图的C<'4>ISR系统需求框架及其视图产品,并在此基础上给出了C<'4>ISR系统需求集成的概念与范围.通过建立需求信息模型,从语法、语义和语用三个层次研究构建一个需求集成框架.通过需求产品之间的关联关系,分析不同视图产品在集成中存在的问题,并给出了需求集成框架中不同需求产品的集成过程,为C<'4>ISR系统需求集成问题的解决提供一个可供参考的方法.     

左手材料涂敷目标的RCS仿真研究

左手材料的介电常数和磁导率都为负值,电场、磁场和波矢量在左手材料中表现为左手螺旋关系,相速与群速方向相反。根据传输线理论分析了波入射到分层媒质上的表面反射系数,计算了随入射波频率、涂层厚度变化情况下的左、右手材料的反射率;基于非均匀有理B样条参数曲面模拟目标的几何外形,采用物理光学法计算了涂敷左手材料目标的雷达散射截面...