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101.
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任务规划系统研究综述 总被引：4，自引：0，他引：4
任务规划系统作为举世瞩目的高科技技术,已经引起了广泛的关注和应用。目前世界上一些主要国家都在研制任务规划系统,且进展很快。为了更好地推进我国学者对于任务规划系统的研究,对任务规划系统的研究进行了全面综述。主要内容包括任务规划系统的发展、应用、主要实现方法及未来发展方向。在应用中,综述了任务规划系统在战场态势评估、无人飞行器、机器人领域的应用。在主要实现方法中,主要描述了数学规划、D*优化算法、A gen t方法和遗传算法四种方法。最后给出了任务规划系统未来发展方向:现代技术的融合、发展战略级任务规划系统及未来社会任务规划系统预研。 相似文献
103.
用非线性规划求解有限推力最优交会 总被引：8，自引：0，他引：8
利用非线性规划方法研究了航天器的有限推力最优交会问题。这种方法利用了近年来发展起来的直接优化技术,用分段多项式来表示整个轨道的状态和控制向量,将最优控制问题转化为非线性规划问题。在应用这种方法时,先将整个轨道分为若干推力段和无推力段,然后利用配置方法产生推力段的约束段,利用状态转移矩阵来产生无推力段的约束。最后,对共面轨道情况下的交会进行了数值仿真,验证了方法的有效性和鲁棒性。 相似文献
104.
Joni Driessen;Joost de Kruijff;Joachim Arts;Geert-Jan van Houtum; 《海军后勤学研究》2024,71(2):189-209
A line replaceable unit (LRU) is a collection of connected parts in a system that is replaced when any part of the LRU fails. Companies use LRUs as a mechanism to reduce downtime of systems following a failure. The design of LRUs determines how fast a replacement is performed, so a smart design reduces replacement and downtime cost. A firm must purchase/repair a LRU upon failure, and large LRUs are more expensive to purchase/repair. Hence, a firm seeks to design LRUs such that the average costs per time unit are minimized. We formalize this problem in a new model that captures how parts in a system are connected, and how they are disassembled from the system. Our model optimizes the design of LRUs such that the replacement (and downtime) costs and LRU purchase/repair costs are minimized. We present a set partitioning formulation for which we prove a rare result: the optimal solution is integer, despite a nonintegral feasible polyhedron. Second, we formulate our problem as a binary linear program (BLP). The article concludes by numerically comparing the computation times of both formulations and illustrates the effects of various parameters on the model's outcome. 相似文献
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Dimitri P. Bertsekas 《海军后勤学研究》2019,66(1):15-37
In this article, we consider shortest path problems in a directed graph where the transitions between nodes are subject to uncertainty. We use a minimax formulation, where the objective is to guarantee that a special destination state is reached with a minimum cost path under the worst possible instance of the uncertainty. Problems of this type arise, among others, in planning and pursuit‐evasion contexts, and in model predictive control. Our analysis makes use of the recently developed theory of abstract semicontractive dynamic programming models. We investigate questions of existence and uniqueness of solution of the optimality equation, existence of optimal paths, and the validity of various algorithms patterned after the classical methods of value and policy iteration, as well as a Dijkstra‐like algorithm for problems with nonnegative arc lengths.© 2016 Wiley Periodicals, Inc. Naval Research Logistics 66:15–37, 2019 相似文献
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Sanjay Mehrotra Hamed Rahimian Masoud Barah Fengqiao Luo Karolina Schantz 《海军后勤学研究》2020,67(5):303-320
We present a stochastic optimization model for allocating and sharing a critical resource in the case of a pandemic. The demand for different entities peaks at different times, and an initial inventory for a central agency are to be allocated. The entities (states) may share the critical resource with a different state under a risk-averse condition. The model is applied to study the allocation of ventilator inventory in the COVID-19 pandemic by FEMA to different U.S. states. Findings suggest that if less than 60% of the ventilator inventory is available for non-COVID-19 patients, FEMA's stockpile of 20 000 ventilators (as of March 23, 2020) would be nearly adequate to meet the projected needs in slightly above average demand scenarios. However, when more than 75% of the available ventilator inventory must be reserved for non-COVID-19 patients, various degrees of shortfall are expected. In a severe case, where the demand is concentrated in the top-most quartile of the forecast confidence interval and states are not willing to share their stockpile of ventilators, the total shortfall over the planning horizon (until May 31, 2020) is about 232 000 ventilator days, with a peak shortfall of 17 200 ventilators on April 19, 2020. Results are also reported for a worst-case where the demand is at the upper limit of the 95% confidence interval. An important finding of this study is that a central agency (FEMA) can act as a coordinator for sharing critical resources that are in short supply over time to add efficiency in the system. Moreover, through properly managing risk-aversion of different entities (states) additional efficiency can be gained. An additional implication is that ramping up production early in the planning cycle allows to reduce shortfall significantly. An optimal timing of this production ramp-up consideration can be based on a cost-benefit analysis. 相似文献
108.
普通物理学实验是公共必修课,随着电子技术迅速发展,多媒体已被广泛的运用,使人机交互能力大大提高,它正作为一种重要的教学媒体迅速应用于教学过程中,对促进教学现代化起着十分重要的作用.因此,制作CAI课件使学生由被动学习变主动学习,并能加深学生对实验内容的理解,对实验现象的观察和规范学生的实验操作技能,从而达到有效提高教学质量和教学效率的目的. 相似文献
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We consider a ship stowage planning problem where steel coils with known destination ports are to be loaded onto a ship. The coils are to be stowed on the ship in rows. Due to their heavy weight and cylindrical shape, coils can be stowed in at most two levels. Different from stowage problems in previous studies, in this problem there are no fixed positions on the ship for the coils due to their different sizes. At a destination port, if a coil to be unloaded is not at a top position, those blocking it need to be shuffled. In addition, the stability of ship has to be maintained after unloading at each destination port. The objective for the stowage planning problem is to minimize a combination of ship instability throughout the entire voyage, the shuffles needed for unloading at the destination ports, and the dispersion of coils to be unloaded at the same destination port. We formulate the problem as a novel mixed integer linear programming model. Several valid inequalities are derived to help reducing solution time. A tabu search (TS) algorithm is developed for the problem with the initial solution generated using a construction heuristic. To evaluate the proposed TS algorithm, numerical experiments are carried out on problem instances of three different scales by comparing it with a model‐based decomposition heuristic, the classic TS algorithm, the particle swarm optimization algorithm, and the manual method used in practice. The results show that for small problems, the proposed algorithm can generate optimal solutions. For medium and large practical problems, the proposed algorithm outperforms other methods. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 564–581, 2015 相似文献