基于位置矢量的大椭圆导航参数计算方法

基于椭球体的大椭圆航行是一种经济可行的远洋航法,为确保船舶沿期望的大椭圆航线航行,提出了一种大椭圆航线导航参数计算方法。该方法采用位置矢量法求解大椭圆顶点,进而定义了长轴矢量和短轴矢量,并在此基础上推导了形式更为紧凑的航向角、航程和偏航距计算公式。算例分析表明:该方法推导的公式计算简洁,可有效解决航海中大椭圆导航的计算问题。     

双层随机机会约束规划的通信干扰任务分配优化仿真

研究不确定条件下的通信干扰任务分配优化问题具有重要的军事意义。基于干扰效益因子的概念,剖析了影响通信干扰任务分配的不确定性因素,建立了基于双层随机机会约束规划的通信干扰任务分配优化模型,设计了遗传蚁群智能算法,实例计算得到了通信干扰任务分配的最佳策略。     

《英语诗歌》课程教学探析——以叶芝为例

《英语诗歌》作为国内普通高校英语专业的专业选修课程,其课堂教学方式一直以传统的讲授为主。本文从认知诗学的视角,以著名的英语诗人叶芝为例,探讨《英语诗歌》课程教学中形式诗学与文化诗学方式方法的结合,在学科建设、课程设置和课堂教学等方面提出建议和参考。     

完善旅游管理专业课程体系的若干思考

构建科学合理的专业课程体系是旅游高校教育的重点。高等旅游教育要合理定位,明确专业培养目标,提高教师素质,改革教学内容,改进教学方法与手段是培养高素质旅游人才的重要方面。     

Optimal control of noncollaborative servers in two‐stage tandem queueing systems

We consider two‐stage tandem queueing systems with dedicated servers in each station and a flexible server that is trained to serve both stations. We assume no arrivals, exponential service times, and linear holding costs for jobs present in the system. We study the optimal dynamic assignment of servers to jobs assuming a noncollaborative work discipline with idling and preemptions allowed. For larger holding costs in the first station, we show that (i) nonidling policies are optimal and (ii) if the flexible server is not faster than the dedicated servers, the optimal server allocation strategy has a threshold‐type structure. For all other cases, we provide numerical results that support the optimality of threshold‐type policies. Our numerical experiments also indicate that when the flexible server is faster than the dedicated server of the second station, the optimal policy may have counterintuitive properties, which is not the case when a collaborative service discipline is assumed. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 435–446, 2014     

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     

具有模糊系数约束的多目标线性规划

研究了一类具有模糊系数约束的多目标线性规划问题.根据各目标函数的梯度方向来量化目标之间的冲突程度,以此提出了一种确定目标权重的新方法,然后基于惩罚函数运用梯度上升算法求问题的有效解.最后给出了一个数值例子.     

线性规划的一种并行修正松弛算法

对求解线性规划问题的松弛算法进行了修正,在此基础上提出了一种基于cluster结构的并行算法,分析了算法的性能;基于曙光3000大规模并行计算机,给出了算法用于求解线性规划问题实例的实验结果.理论分析和实验结果表明,修正算法改进了松弛算法的实际性能,同时具有较好的并行性和稳定性,可用于求解此类大规模科学与工程规划问题的高性能计算.     

给定人员情况下最小化开发时间和成本的软件项目调度

给出了一种软件项目的随机调度模型.它明确地把调度策略作为输入,一旦调度策略确定,模型就可以输出关于项目的完成时间或成本的一个概率分布.利用随机最优化技术,能够计算出软件项目的一个调度策略,它使得项目在人员给定的情况下开发时间和成本最小.     

Concave envelopes of monomial functions over rectangles

The construction of convex and concave envelopes of real‐valued functions has been of interest in mathematical programming for over 3 decades. Much of this interest stems from the fact that convex and concave envelopes can play important roles in algorithms for solving various discrete and continuous global optimization problems. In this article, we use a simplicial subdivision tool to present and validate the formula for the concave envelope of a monomial function over a rectangle. Potential algorithmic applications of this formula are briefly indicated. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004