多基准站相对定位算法及先验基线向量偏差影响分析

为提高单基准站短基线相对定位解算的可靠性,研究了多基准站约束的相对定位算法。将基准站间可提前测量的先验基线信息融入观测模型中,给出了多基准站相对定位的函数模型和随机模型,在此基础上推导了模糊度精度因子的解析表达式,揭示了基准站数量的增加对模糊度浮点解精度提升的作用;从理论上分析了基准站间先验基线信息中的偏差对模糊度解算的影响,分析表明,当先验基线各分量偏差的绝对值之和小于5 cm时,模糊度解算几乎不受影响;通过仿真和实测数据进行了验证。试验结果表明,增加基准站数量不仅能有效提升模糊度解算成功率和收敛速度,并且对先验基线信息中的偏差具有较好的抑制作用,当基线各分量偏差均增加到4 cm时,实测数据模糊度解算成功率仍能达到92%以上。研究结论为特殊场景下多基准站间的快速非精确标定提供了理论依据。     

Optimal patrol to uncover threats in time when detection is imperfect

Consider a patrol problem, where a patroller traverses a graph through edges to detect potential attacks at nodes. An attack takes a random amount of time to complete. The patroller takes one time unit to move to and inspect an adjacent node, and will detect an ongoing attack with some probability. If an attack completes before it is detected, a cost is incurred. The attack time distribution, the cost due to a successful attack, and the detection probability all depend on the attack node. The patroller seeks a patrol policy that minimizes the expected cost incurred when, and if, an attack eventually happens. We consider two cases. A random attacker chooses where to attack according to predetermined probabilities, while a strategic attacker chooses where to attack to incur the maximal expected cost. In each case, computing the optimal solution, although possible, quickly becomes intractable for problems of practical sizes. Our main contribution is to develop efficient index policies—based on Lagrangian relaxation methodology, and also on approximate dynamic programming—which typically achieve within 1% of optimality with computation time orders of magnitude less than what is required to compute the optimal policy for problems of practical sizes. © 2014 Wiley Periodicals, Inc. Naval Research Logistics, 61: 557–576, 2014     

求解面向进攻的武器-目标分配问题的蚁群算法

面向进攻的武器-目标分配问题是军事运筹学研究中的重要课题,旨在制定合理的打击策略以最大程度摧毁敌方目标。采用一种融合局部搜索和信息素控制的蚁群算法,兼顾控制解的局部收敛速度和全局收敛质量。在解的构造过程中直接处理约束条件,提高生成解的可行性,并大大缩小了搜索空间,提高了算法效率。通过采用多种算法对不同规模的武器-目标分配问题进行实验,结果表明改进的蚁群算法在收敛速度和求解质量上表现优异。     

基于代理模型的卫星系统仿真优化平台

针对既定目标,采用卫星系统进行协同观测可以最大化卫星系统的整体效能,如何对卫星系统的轨道或载荷参数设计是一个设计空间大、设计变量多的优化问题。对此,采用基于代理模型的仿真优化,通过改进广义模式搜索算法在设计空间中搜索最优解,并以此为核心设计开发卫星系统仿真优化平台。该平台集成问题建模、仿真优化和结果评估显示,为用户提供设计和改进卫星系统方案的方法和依据。采用该平台对卫星系统设计实例进行优化,通过对比发现,平台的优化结果稳定性和优化效率优于STK-Analyzer。     

分布式消磁系统绕组补偿电流快速调整

随着现代舰船的大型化和舰船消磁技术要求的日益提高,消磁系统向分布式发展,消磁线圈的数目越来越多,绕组补偿电流调整的实时性要求也愈来愈高.针时这一特点,建立了消磁绕组磁场的数学模型,引入二分搜索法来快速调整绕组补偿电流.实验结果表明:该算法能够快速调整消磁绕组补偿电流,且消磁效果好.此外,该算法原理浅显易懂,编程简单明了...     

基于上下文的快速自适应运动估计算法

高效的运动估计算法是实时视频编解码技术的研究重点。为降低视频编码中运动估计的高计算复杂度问题,提出了基于上下文的快速自适应运动估计算法。该算法在运动估计过程中引入了次最佳匹配点,并且使用了一种基于平行四边形模式的方向性搜索策略。该算法的基本思想是:在块运动矢量估计过程中,利用前面搜索步中得到的块运动矢量及次最佳匹配点与最佳匹配点之间的位置关系,自适应选择一种平行四边形搜索模式,并确定下一步搜索的方向,进行更精确运动矢量的搜索。实验结果表明,该算法有效降低了视频压缩编码中运动估计的运算复杂度。     

Search and the introduction of improved technologies

Modeling R&D as standard sequential search, we consider a monopolist who can implement a sequence of technological discoveries during the technology search process: he earns revenue on his installed technology while he engages in R&D to find improved technology. What is not standard is that he has a finite number of opportunities to introduce improved technology. We show that his optimal policy is characterized by thresholds ξ_i(x): introduce the newly found technology if and only if it exceeds ξ_i(x) when x is the state of the currently installed technology and i is the number of remaining introductions allowed. We also analyze a nonstationary learning‐by‐doing model in which the monopolist's experience in implementing new technologies imparts increased capability in generating new technologies. Because this nonstationary model is not in the class of monotone stopping problems, a number of surprising results hold and several seemingly obvious properties of the stationary model no longer hold. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

空域频域不确定条件下电磁探测卫星规划方法研究

电磁探测卫星对区域目标的覆盖搜索在反恐及海上搜救等领域发挥着重要作用.针对电磁探测卫星区域搜索任务中存在的空域频域不确定性,构建了电磁探测卫星区域搜索问题(EDSASP)中不确定因素的量化描述模型及决策要素模型,提出了基于贝叶斯决策的电磁卫星任务规划方法,并以信息探测收益和前端截获收益为优化目标,建立了空域频域不确定条...     

A note on the optimality of index priority rules for search and sequencing problems

We show that the linear objective function of a search problem can be generalized to a power function and/or a logarithmic function and still be minimized by an index priority rule. We prove our result by solving the differential equation resulting from the required invariance condition, therefore, we also prove that any other generalization of this linear objective function will not lead to an index priority rule. We also demonstrate the full equivalence between two related search problems in the sense that a solution to either one can be used to solve the other one and vice versa. Finally, we show that the linear function is the only function leading to an index priority rule for the single‐machine makespan minimization problem with deteriorating jobs and an additive job deterioration function. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

攻击型无人机巡弋搜索航路优化设计与仿真

为改进攻击型无人机待机段的飞行搜索性能,应用以最大值原理为基础的最优搜索理论对无人机待机搜索路线进行研究,得出光栅式、螺旋式和扫雪式三种搜索路线,并通过计算机仿真与传统的8字式搜索方式进行了比较.仿真结果表明,优化设计结果是合理的,证实了其有效性和可行性.