支持高效组播的高性能路由器QoS机制研究与实现

研究并提出一种有效支持组播的高性能路由器QoS机制QoS RESM,该机制以多阈值机制为基础,考虑远程转发引擎的拥塞状态信息,引入全局控制反馈机制,有效完成了高性能路由器上支持组播的流量控制。最后描述QoS RESM在基于网络处理器的核心路由器上的实现方法。     

Network disconnection problems in a centralized network

We consider three network disconnection problems in a centralized network where a source node provides service to the other nodes, called demand nodes. In network disconnection problems, each demand node gets a certain benefit when connected to a source node and a network attacker destroys edges to prevent demand nodes from achieving benefits. As destroying edges incurs expenses, an attacker considers the following three different strategies. The first is to maximize the sum of benefits of the disconnected nodes while keeping the total edge destruction cost no more than a given budget. The second is to minimize the total destruction cost needed to make a certain amount of benefits not accomplished. The last is to minimize the ratio of the total destruction cost to the benefits not accomplished. In this paper, we develop exact algorithms to solve the above three problems. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

On the first come–first served rule in multi‐echelon inventory control

A two‐echelon distribution inventory system with a central warehouse and a number of retailers is considered. The retailers face stochastic demand and replenish from the warehouse, which, in turn, replenishes from an outside supplier. The system is reviewed continuously and demands that cannot be met directly are backordered. Standard holding and backorder costs are considered. In the literature on multi‐echelon inventory control it is standard to assume that backorders at the warehouse are served according to a first come–first served policy (FCFS). This allocation rule simplifies the analysis but is normally not optimal. It is shown that the FCFS rule can, in the worst case, lead to an asymptotically unbounded relative cost increase as the number of retailers approaches infinity. We also provide a new heuristic that will always give a reduction of the expected costs. A numerical study indicates that the average cost reduction when using the heuristic is about two percent. The suggested heuristic is also compared with two existing heuristics. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

超音速外流与塞式喷管形成的干扰流场数值模拟

从考虑了k ε湍流模型和双组分气体模型的三维薄层近似NS方程出发 ,采用高效ENO差分格式 ,数值模拟了超音速空气外流与塞式喷管燃气形成的内外流干扰流场。部分计算结果与国外文献相比一致。在此基础上论证了应用计算流体力学开展塞式喷管研究的可行性。     

巡航导弹地形跟踪系统仿真的研究

基于预见控制理论,采用零相位误差跟踪控制器,实现巡航导弹的前馈控制,能使导弹飞行良好地跟踪地形,还给出了前馈控制器的设计方法,并对导弹飞行过程作了系统仿真.     

综合孔径雷达系统设计的关键技术

从综合孔径雷达 SAR成像的基理出发 ,分析了 SAR系统中相位误差对 SAR图像质量的影响和系统中产生相位误差的重要因素 ,从而分析了 SAR系统设计的关键技术和实施的基本途径。     

剪切来流条件下的涡生振荡机理

将指数极坐标系建立在运动的圆柱上,推导了运动坐标中剪切来流条件下,涡生振荡的涡量-流函数守恒方程、其初始和边界条件、圆柱表面的水动力表达式、圆柱振荡方程。对圆柱从静止开始振荡到发展为稳定振荡状态进行了计算和讨论,描述了脱体涡街的发展过程、升阻力相图的连续变形和漂移、圆柱振荡和平衡位置的变化过程。研究了涡生振荡终态随剪切度K的变化。结果表明:剪切来流给流场加入了背景涡,使圆柱的上涡增强、下涡减弱,流场的对称性被破坏。随着剪切度K的增大,涡街的倾斜程度增大,压力曲线的漂移量增大,由此导致升力的绝对值增大,圆柱的振幅增大且平衡位置向圆柱下侧的漂移也增大。     

一步法制备石蜡微胶囊的中试研究及性能表征

采用一步法在100L反应釜内进行石蜡微胶囊制备的中试，表征了石蜡微胶囊的微胶囊化率、粒径和热性能，探讨了中试工艺对产品性能的影响。结果表明中试产品与实验室小试产品的性能基本接近。中试石蜡微胶囊的微胶囊化率为70％，平均粒径为54．0μm，相变范围为40～80℃，相变峰值和热焓分别为65℃，114J／g，分解温度达250℃。     

超声速气液两相流液化升压装置研究

基于超声速气液两相流升压原理的水蒸气液化升压装置具有液化迅速、出口压力高的特点,但是两相流升压的物理过程十分复杂,目前分析模型中考虑的参数较少,对细节刻画不够全面.针对这一问题,文章建立了两相流分析模型,考虑了液滴与水蒸气的传热、传质过程,分析了冷却水温度、引射比、混合室收缩比、过冷度和速度滑移比对性能的影响;得到了激波前的压力、干度、空泡份额与引射比的关系,以及凝结激波前后的温度和压力与引射比的关系.计算结果表明:为提高系统性能.需要尽可能地提高液体的雾化程度,降低冷却水的温度,同时将引射比控制在6～8附近;如果设计合理,装置的升压系数可达3倍以上.     

基于DOB和二自由度控制器的某火炮稳定控制系统设计

火炮稳定控制系统性能会受到如路况、火炮射击时产生的冲击力矩等外部扰动以及摩擦力矩变化、测量噪声、转动惯量变化等内部参数摄动的影响。针对此问题,引入一种DOB观测器和二自由度控制算法,来减少摩擦对系统性能的影响,提高系统对载体扰动的隔离能力。仿真和实验结果表明,所提出的算法可以有效提高系统的稳定精度和速度伺服性能。