Ad Hoc网中的OLSR路由协议研究

本文主要描述了优化链路状态路由算法(Optimized Link State Routing Protocol：“OLSR”)的特点，并且对OLSR路由算法的性能进行仿真分析。主要评估的参数有：数据分组成功接收率，数据分组投递的平均端到端时延，点到点数据传输平均速率。在此基础上研究了OLSR在传统的链路状态路由算法上引入的优化策略多点中继站(multipoint relay，MPR)：采用选择一部分邻居节点来转发控制信息。     

RIP路由协议分析及配置简述

介绍RIP(Routing Information Protocol)路由协议的基本内容,分析RIP协议的工作原理,路由环路的产生及解决方法,通过实验阐述如何在路由器上配置RIP协议。     

一种新的基于移动预测的MANET路由协议

移动自组网是一种由一系列可以自由移动的节点主机聚集而成的一个临时性动态网络。它没有固定基站，也没有作为控制管理中心的节点主机，由于其拓扑的动态性，其路由协议与其他传统网络有很大的区别。为了能更有效地移动自组网中实现数据的传送，本文提出了一种基于移动预测下的MANET路由协议，该协议综合考虑了传输路径的延时和稳定性，选择在延时限制下平均拥有最稳特性的传输路径，模拟结果表明，这种方法比基于移动预测量稳路径路由协议的传输时延要短，传送成功概率要高，而控制开销却相关不大。     

一种基于改进蚁群优化算法的WSNs路由协议

面对无线传感网络(wireless sensor network,WSN)路由问题,提出新颖生物激励-自我组织的安全自适应路由协议(biological inspired self-organized secure autonomous routing protocol,BIOSARP)。BIOSARP采用改进蚁群优化算法(improved ant colony optimization,IACO),利用端到端传输时延、剩余电量和链路质量计算信息素,并据此信息决策最优转发节点,从而减小广播次数和数据包负担,降低时延、数据包丢失率和功率消耗。仿真结果表明:提出的BIOSARP在数据包传递率、能量消耗优于安全实时负荷分配协议(secure real-time load distribution,SRTLD),数据包传递率提高24.75%,能量消耗降低31.8%。     

基于能量有效的Ad hoc路由协议的研究

Ad hoc网络是一种无基础设施,由无线移动终端组成的临时多跳自治网络。本文从能量有效的目标出发,对3类不同策略的路由协议进行比较,评价各个协议之间的性能优劣。     

Ad Hoc网络中CBRP路由协议研究

CBRP是Ad Hoc网络中一种基于分簇的按需路由协议。本文阐述了CBRP协议的数据结构、簇的形成过程、路由机制以及如何在NS2中添加该协议,并分析了该协议的优缺点,表明了该协议在大规模网络中性能良好。     

移动网络安全技术及其在AdHoc路由协议中的应斥

AdHoc网络安全路由的安全稳定性直接对网络的正常运行产生影响,采取合适的措施提高其路由协议的稳定与安全是十分必要的。主要对移动网络安全技术在AdHoc路由协议中的应用进行分析探讨,供相关人参考。     

移动网络安全技术及其在Ad Hoc路由协议中的应用

Ad Hoc网络安全路由的安全稳定性直接对网络的正常运行产生影响,采取合适的措施提高其路由协议的稳定与安全是十分必要的。主要对移动网络安全技术在Ad Hoc路由协议中的应用进行分析探讨,供相关人参考。     

IP路由技术与RIP 协议探析

随着计算机网络规模的不断扩大和大型互联网络的迅猛发展,路由技术在网络技术中已逐渐成为关键部分,路由器也随之成为最重要的网络设备。本文介绍了IP路由算法,分析了RIP路由协议的基本原理与处理过程。     

浅谈数字视频广播协议实现

数字视频广播(DVB)是一种重要的数字电视系统业务,在以后的信息社会中数字广播技术将占据重要的位置。对DVB数据广播的具体协议实现进行研究。     

An efficient approach for reliability-based topology optimization

This article presents an efficient approach for reliability-based topology optimization (RBTO) in which the computational effort involved in solving the RBTO problem is equivalent to that of solving a deterministic topology optimization (DTO) problem. The methodology presented is built upon the bidirectional evolutionary structural optimization (BESO) method used for solving the deterministic optimization problem. The proposed method is suitable for linear elastic problems with independent and normally distributed loads, subjected to deflection and reliability constraints. The linear relationship between the deflection and stiffness matrices along with the principle of superposition are exploited to handle reliability constraints to develop an efficient algorithm for solving RBTO problems. Four example problems with various random variables and single or multiple applied loads are presented to demonstrate the applicability of the proposed approach in solving RBTO problems. The major contribution of this article comes from the improved efficiency of the proposed algorithm when measured in terms of the computational effort involved in the finite element analysis runs required to compute the optimum solution. For the examples presented with a single applied load, it is shown that the CPU time required in computing the optimum solution for the RBTO problem is 15–30% less than the time required to solve the DTO problems. The improved computational efficiency allows for incorporation of reliability considerations in topology optimization without an increase in the computational time needed to solve the DTO problem.     

机动车检测设备通信接口的设计与实现

针对目前机动车检测行业中存在的计算机管理控制系统与检测仪器设备之间的双向交互数字接口因检测仪器的型号、规格不同而标准不一的问题,采用异步全双工工作方式的接口标准和数据校验方式,设计了一种规范的通信接口协议.根据机动车检测流程要求,重点介绍了通信接口协议的指令格式和功能,对机动车检测流程和检测仪器设备的状态进行了规范.统一通信接口协议的使用对确保检测数据的准确合理、规范机动车检测行业有重要的作用和深远的意义.     

An enhanced genetic algorithm for structural topology optimization

Genetic algorithms (GAs) have become a popular optimization tool for many areas of research and topology optimization an effective design tool for obtaining efficient and lighter structures. In this paper, a versatile, robust and enhanced GA is proposed for structural topology optimization by using problem‐specific knowledge. The original discrete black‐and‐white (0–1) problem is directly solved by using a bit‐array representation method. To address the related pronounced connectivity issue effectively, the four‐neighbourhood connectivity is used to suppress the occurrence of checkerboard patterns. A simpler version of the perimeter control approach is developed to obtain a well‐posed problem and the total number of hinges of each individual is explicitly penalized to achieve a hinge‐free design. To handle the problem of representation degeneracy effectively, a recessive gene technique is applied to viable topologies while unusable topologies are penalized in a hierarchical manner. An efficient FEM‐based function evaluation method is developed to reduce the computational cost. A dynamic penalty method is presented for the GA to convert the constrained optimization problem into an unconstrained problem without the possible degeneracy. With all these enhancements and appropriate choice of the GA operators, the present GA can achieve significant improvements in evolving into near‐optimum solutions and viable topologies with checkerboard free, mesh independent and hinge‐free characteristics. Numerical results show that the present GA can be more efficient and robust than the conventional GAs in solving the structural topology optimization problems of minimum compliance design, minimum weight design and optimal compliant mechanisms design. It is suggested that the present enhanced GA using problem‐specific knowledge can be a powerful global search tool for structural topology optimization. Copyright © 2005 John Wiley & Sons, Ltd.     

Design and implementation of an offload engine for internet group messaging protocol multicast snooping

As internet protocol (IP) networks in the enterprise space continue to mature, with regards to stability and availability, the desire for these networks to deliver multimedia content will grow. Although IP networks have long had enough bandwidth to support multimedia streams, the deployment of this content seems to have been somewhat limited in the enterprise. The control mechanisms for multicast traffic, both at the IP layer and the data link layer, are still the areas that have not been adopted as widely as their more common unicast counterparts. The authors examine the internet group messaging protocol (IGMP) snooping process that currently runs on enterprise switches and propose an offload hardware engine to accelerate it. Currently, many enterprise switches handle this task with a general-purpose processor within the switch. Although this process adds very little to the overall load of systems currently, as multicast transmissions become more commonplace, the need for this process to be offloaded onto specialised hardware will be a necessity, in order to maintain the stability of the switch and the surrounding network. The proposed hardware model simulations reveal significant increase in the number of packets per second that can be handled compared to software implementations.     

An accurate and fast regularization approach to thermodynamic topology optimization

In a series of previous works, we established a novel approach to topology optimization for compliance minimization based on thermodynamic principles known from the field of material modeling. Hamilton's principle for dissipative processes directly yields a partial differential equation (referred to as the evolution equation) as an update scheme for the spatial distribution of density mass describing the topology. Consequently, no additional mathematical minimization algorithms are needed. In this article, we introduce a regularization scheme by penalization of the gradient of the spatial distribution of mass density. The parabolic evolution equation (owing to a similar structure to the transient heat-conduction equation) is solved most efficiently by an explicit time discretization. The Laplace operator is discretized via a Taylor series expansion yielding an operator matrix that is constant for the entire optimization process. This method shares some similarities to meshless methods and allows for an accurate application also on unstructured finite element meshes. The minimal size of the structure member can directly be controlled, a priori, by a numerical parameter introduced along with the regularization, similar to classical filter radii.     

Design procedures and implementation of the segmented flow topology (SFT) for discrete material flow systems

In this paper, both the single pick-up and delivery station (SPDS) and the multiple pick-up and delivery station (MPDS) cases of the segmented flow topology (SFT) system configuration are presented. These system's configurations serve as the backbone of a heuristic design procedure for SFT. This design procedure consists of an upper and lower bound calculation and a search procedure that minimizes the total system cost (transportation, setting up pick-up and/or delivery stations, and material handling devices). Two examples of the implementation of the procedure are given.     

An implementation of no-slip boundary conditions in DPD

We report an implementation of the no-slip boundary condition in the modeling of solid boundaries by dissipative particle dynamics (DPD) method. Stimulated by a model for several types of solid boundaries, we develop an implementation that satisfies no-slip boundary condition with practically no-density distortion near the boundaries. The model is implemented to simulate the planar Poiseuille and Couette flows, as well as the flow through a contraction and diffusion channel. Results compare excellently with the previous methods.     

An implementation perspective of applying object-oriented database technologies

As a result of improvements in information technology, more system designs and implementations require data-intensive applications. The most promising approach to solving these problems is the object-oriented database architecture. Unfortunately, object-oriented database management systems have not matured. Lack of agreements in the data models and formal foundations have created problems in using them. However, systems are being designed and developed with object-oriented philosophies even though important issues still need to be resolved. This paper examines the important issues in designing an object-oriented database prototype from three perspectives: object technologies, database technologies, and application environments. Each issue is discussed separately and illustrated with C++/Versant.