Restricted overlapping balancing domain decomposition methods and restricted coarse problems for the Helmholtz problem

Overlapping balancing domain decomposition methods and their combination with restricted additive Schwarz methods are proposed for the Helmholtz equation. These new methods also extend previous work on non-overlapping balancing domain decomposition methods toward simplifying their coarse problems and local solvers. They also extend restricted Schwarz methods, originally designed to overlapping domain decomposition and Dirichlet local solvers, to the case of non-overlapping domain decomposition and/or Neumann and Sommerfeld local solvers. Finally, we introduce coarse spaces based on partitions of unity and planes waves, and show how oblique projection coarse problems can be designed from restricted additive Schwarz methods. Numerical tests are presented.     

基于OPNET的高速列车控制网络负载平衡研究

随着工业以太网应用于高速列车并成为其控制网络,将可能出现带宽、吞吐量等一系列技术问题。采用基于流水线R—R的负载平衡调度算法,通过OPNET软件建模并调用该算法进行仿真。仿真结果表明,该算法在列车控制网络中的应用是可行的,能较好地解决列车控制网络的负载平衡问题。     

Simultaneous solving of balancing and sequencing problems with station-dependent assembly times for mixed-model assembly lines

In spite of many studies, investigating balancing and sequencing problems in Mixed-Model Assembly Line (MMAL) individually, this paper solves them simultaneously aiming to minimize total utility work. A new Mixed-Integer Linear Programming (MILP) model is developed to provide the exact solution of the problem with station-dependent assembly times. Because of NP-hardness, a Simulated Annealing (SA) is applied and compared to the Co-evolutionary Genetic Algorithm (Co-GA) from the literature. To strengthen the search process, two main hypotheses, namely simultaneous search and feasible search, are developed contrasting Co-GA. Various parameters of SA are reviewed to calibrate the algorithm by means of Taguchi design of experiments. Numerical results statistically show the efficiency and effectiveness of the proposed SA in terms of both the quality of solution and the time of achieving the best solution. Finally, the contribution of each hypothesis in this superiority is analyzed.     

集群系统负载均衡性能测试研究

分析影响集群系统性能的关键因素,提出在Linux下架设负载均衡系统,获取集群系统关键性能参数,加权计算真实服务器的负载。根据服务器负载由负载均衡器动态分配连接请求,使集群达到负载均衡。使用不同的客户端进行测试,分析比较不同测试软件的测试结果,为改进集群系统的负载均衡性能提供支持。     

常规游梁式抽油机摇杆平衡装置

摇杆平衡节能装置,是通过在游梁抽油机游梁尾端及连杆中部(或横梁)安装可变臂的平衡装置,有效改变抽油机平衡力臂长度,使得光杆负荷峰值扭矩与抽油机平衡峰值扭矩能够相对同步产生,从而达成消除电流峰值,达到节能降耗的目的。摇杆平衡节能装置在使用时,抽油机的冲次应不高于5次,上下冲程中光杆载荷差应小于4t;该装置不适应玻璃杆抽油井,不适应在已进行过节能改造的抽油机上应用。     

A Jacobi-type method for computing balanced realizations

A new numerical scheme for computing balancing coordinate transformations in linear systems theory is presented. The method is closely related to the Jacobi method for diagonalizing symmetric matrices. Here the minimization of the sum of traces of the Gramians by orthogonal and nonorthogonal Jacobi-type rotations is considered. The algorithm is shown to be globally convergent to a balancing transformation that arranges the Hankel singular values in a prescribed ordering. Local quadratic convergence of the algorithm is shown.     

分级移动IPv6中一种新的自适应MAP选择算法*

分级移动IPv6中存在单点故障和负荷集中问题。提出一种基于分布式MAP结构的自适应MAP选择算法,综合考虑移动节点的当前速度、会话到达率、MAP负荷及距离等因素,以MN注册后将产生的移动性管理信令开销最小为依据进行选择。仿真结果表明,自适应MAP选择算法能够根据移动节点和网络的当前特性优化地选择不同的MAP进行注册,使移动性管理信令开销最小,具有较好的负荷分担效果,并一定程度上增强了分级结构的鲁棒性。与最远/近MAP选择方案相比,自适应MAP选择算法能够提高网络的吞吐量及减少平均切换时延。     

基于集群的可伸缩网络服务体系结构研究与实现*

在分析现在和将来网络服务需求的基础上, 提出基于集群的可伸缩网络服务体系结构Linux Virtual Server, 分为负载调度器、服务器池和后端存储三层结构。负载调度器采用IP 负载均衡技术和基于内容请求分发技术。LVS 集群提供了负载平衡、可伸缩性和高可用性, 可以应用于建立很多可伸缩网络服务。进而提出地理分布的LVS 集群系统, 可节约网络带宽, 改善网络服务质量, 具有良好的抗灾害性。     

请求速率对集群Web服务器调度的影响

讨论了集群Web服务器的几种常见请求调度策略，针对目前大多数的请求调度策略都是只考虑服务器的内在指标，而忽略了请求速率等输入指标对负载调度的影响，即使考虑了请求速率，也很少考虑请求速率变化突发性对Web服务器的影响。通过分析请求速率对Web服务器的性能影响，可以利用输入指标结合服务器指标来调度请求输入，从而有效地解决服务器间的负载不平衡。     

网络入侵检测系统中动态负载平衡策略的设计

随着互联网的广泛应用,网络信息量迅猛增长,网络攻击数量和方式大大增加,网络入侵检测系统需要部署多个感知器(Sensor)时网络监测和保护,通过增加Sensor,可以增强系统分析检测能力。然而,为了充分利用系统处理能力,需要动态分配处理节点任务,实现动态负载平衡。该文在分析网络入侵检测系统的基础上,提出负载值计算方法,结合通用负载平衡策略,提出了分布式入侵检测系统的动态负载平衡策略,实现了良好的动态负载平衡效果,提高了系统性能。