Rendezvous search when marks are left at the starting points

Leaving marks at the starting points in a rendezvous search problem may provide the players with important information. Many of the standard rendezvous search problems are investigated under this new framework which we call markstart rendezvous search. Somewhat surprisingly, the relative difficulties of analysing problems in the two scenarios differ from problem to problem. Symmetric rendezvous on the line seems to be more tractable in the new setting whereas asymmetric rendezvous on the line when the initial distance is chosen by means of a convex distribution appears easier to analyse in the original setting. Results are also obtained for markstart rendezvous on complete graphs and on the line when the players' initial distance is given by an unknown probability distribution. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 722–731, 2001     

飞行器动力学环境预示技术应用研究

动力学环境试验技术已被广泛应用 ,但动力学环境预示技术还没有得到很好的重视和发展。讨论了几种动力学环境预示方法的特点 ,着重研究了统计能量分析 ( SEA)方法的原理及其应用 ,并以某型号发动机长尾喷管舱为例 ,具体给出其工程分析估计过程     

单基发射药的热自燃数值模拟与其剩余能量变化研究

建立了单基发射药柱热自燃的数学模型 ,根据模型利用数值模拟的方法计算了单基发射药的中心温度与其剩余能量 ,并对中心温度的模拟结果与实验结果进行了比较。解决了其热分解动力学参数的非唯一性问题 ,为装填有单基发射药各种弹药的热自燃计算提供了依据     

Birth of a norm champion: how South Africa came to support the NPT’s indefinite extension

In 1995, South Africa was in a special position. It was: a new party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the first country to voluntarily renounce nuclear weapons, led by a charismatic leader, and seen as a champion of disarmament principles. Yet South Africa’s new leaders were also interested in affirming their position within the Non-Aligned Movement, which was adamantly opposed to the NPT’s indefinite extension. Why, then, did South Africa decide to support the indefinite extension of the NPT in 1995? Existing scholarship has ascribed too much credit to pressure from the United States, overlooking domestic debates in South Africa and the bifurcation between professional diplomats and political elites. This article, building on new archival sources and in-depth oral-history interviews with major actors, demonstrates that South African diplomats opposed indefinite extension while South African policy elites allocated little attention to the topic until late in the game. The findings contribute to our understanding of South Africa’s norm entrepreneurship, as well as the politics of global nonproliferation.     

Optimizing natural gas pipeline transmission with nonuniform elevation: A new initialization approach

In this paper, we develop an iterative piecewise linear approximation approach with a novel initialization method to solve natural gas pipeline transmission problems with the nonuniform network elevation. Previous approaches, such as energy minimization methods, cannot be applied to solve problems with the nonuniform network elevation because they exclude pressure range constraints, and thus provide solutions far from optimum. We propose a new initialization model that considers pressure range constraints and improves the optimality of the solutions and the computational efficiency. Furthermore, we extend the energy minimization methods and provide the necessary conditions under which the extended methods operate in networks with the nonuniform elevation. We test the performances of the methods with previously reported pipeline networks from the literature, with the open data set GasLib, and with our industrial collaborator. The initialization approach is shown to be more efficient than the method with fixed initial breakpoints. The newly proposed initialization approach generates solutions with a higher accuracy than the extended energy minimization methods, especially in large‐size networks. The proposed method has been applied to natural gas transmission planning by the China National Petroleum Corporation and has brought a direct profit increase of 330 million U.S. dollars in 2015‐2017.     

等离子体与高功率微波相互作用中电子分布特性

电子数密度是表征等离子体物理特性的一项重要因素,在等离子体与高功率微波的相互作用中,等离子体对入射电磁波的吸收、衰减和屏蔽等电磁特性可通过电子数密度的变化进行表征。基于等离子体流体近似研究方法,利用COMSOL软件求解等离子体中的波动方程、电子传递方程和重粒子传递方程,计算分析了等离子体与高功率微波相互作用中的电子分布特性,重点分析了相互作用中平均电子数密度和平均电子能的数值和空间分布变化过程。研究表明,在高功率微波作用下,等离子体区域电子数密度在数值上会产生剧烈的阶跃变化,形成雪崩效应,在空间分布上电子数密度峰值产生趋于入射方向移动的变化;电子能的变化与入射波激励和电子数密度相关,随入射激励增加呈增长趋势,随电子数密度的增加而减小。     

电磁发射的出口速度及负载质量变化对导轨热量的影响

为分析不同发射出口速度、不同发射负载质量对导轨积累热量的影响,建立了导轨温度场模型,计算了导轨各点温度变化过程,并和光纤光栅温度传感器测量结果对比,验证了模型及测量结果的正确性。在此基础上,设计并进行了三种类型实验,分析了在不同发射速度、不同发射负载质量以及相同发射能级不同发射速度下的导轨热量积累差异。该结论为确定连发间隔、导轨冷却设计提供了有效参考。     

模糊控制理论在舰船制冷装置中的应用研究

以蒸发器和冷库作为被控对象,利用计算机进行了制冷系统模糊控制的研究.针对蒸发器过热度和库温控制问题设计了模糊控制器.在理论研究的同时,建立了制冷装置计算机控制和数据采集系统.在VisualBasic环境下开发了蒸发器过热度模糊控制程序.对比实验运行表明:利用模糊控制器和电子膨胀阀对蒸发器过热度和库温进行控制较之用热力膨胀阀控制,制冷剂流量调节范围大、过热度小、蒸发器面积利用率高、装置节能效果好.     

加工中心用触发式测头系统监测方法研究

主要研究了在数控加工中心ARROW500上使用触发式测头(英国Renishaw的MP12测头)实现零件加工的自动监测,通过深入研究用触发式测头在加工中心上实现在线监测的方法,使加工零件的序前调整、找正,序中监控及序后测量等可自动完成,实现了加工中心高效率、高自动化的监测。     

非接触爆炸作用下舰船动力系统生命力的研究方法

分析非接触爆炸作用下舰船动力系统中主要设备的破坏模式 ,建立了动力设备的冲击响应模式 ,并给出了在非接触爆炸作用下用于舰船动力系统生命力评估的系统破坏概率计算机仿真计算方法。