两类模式匹配问题的并行解决方案

文章基于Intel网络处理器IXP1200,在生物信息科学领域,实现了用于蛋白质数据库或DNA数据库相似性比较的BLAST算法的第一阶段;在网络安全领域,实现了一个拦截可疑特征码的入侵检测系统,提供完全TCP流重构,在单张网络处理器板卡上实现完全报文内容过滤。     

Ad Hoc网络数据链路层协议的研究

本文主要研究二进制指数退避算法BEB及乘性增加线性减少算法MILD,重点分析两种算法在Ad Hoc网络中的效能。采用计算机仿真软件OPNET验证此算法,通过仿真平台了解两种算法的优缺点,比较不同的算法对网络的公平性、吞吐量、延迟及系统丢包率的影响。仿真结果表明,MILD算法能够在高负载场景的网络下使移动Ad Hoc网络有效的提高吞吐量、降低平均时延和丢包量等。但是MILD算法也有自身的缺点,在轻负荷网络中,该算法的因无法快速调节竞争窗口而导致性能急剧下降。     

TCP链接中有限状态机变化情况详细分析

TCP是一种面向连接的、可靠的、基于字节流的传输层通信协议.它在网络传输中起到非常重要的作用.本文详细分析了客户/服务器在TCP连接建立、数据传输过程与连接释放时,正、异常情况下的有限状态机的变化情况.文中对11种状态进行了介绍,着重分析了异常状况下处理情况,分析了连接时的3次握手与连接释放时的4次握手的必要性.在此基础上给出了TCP协议的优缺点,列出了TCP面临的多个问题.对于SYN FLOOD、LAND攻击和CC攻击等问题,分析了它们的攻击原理,给出了应对措施.     

分层分布式算法求解物流配送网络流问题研究

扩展端到端的建模方法到物流配送网络中,通过构建节点最优影子价格这个双重问题,利用分层分布式算法来解决物流配送网络最优流计算的问题.它考虑分布计算和信息共享,增强了系统的健壮性.首先阐述了物流配送网络最优流计算问题,然后引入分层分布式算法来解决物流网络配送问题,并对分层分布式算法的软件实现进行了详细阐述,最后用实例证明了算法的有效性和可行性.     

TCP拥塞控制算法的NS仿真研究

随着网络技术的发展,网络拥塞日益严重。而TCP拥塞控制对如何解决网络拥塞问题,提高网络资源至关重要。文章首先对NewReno、Sack和Vegas拥塞算法从改进策略、延时、网络利用率、应用范围等进行了理论分析。接着通过NS仿真的方法,从拥塞窗口,吞吐量来分析具体分析它们的性能,最后比较这几种算法的优缺点及适用性。     

基于ORwgh的无线传感器网络定位算法在军事物流可视化中的应用研究

针对无线传感器网络的定位技术应用于军事物流可视化建设当中存在着非视距传播误差定位的问题,在传统的残差加权算法的基础上,提出了对原有算法的改进算法,即优先残差加权算法。该算法避免了由于距离测量值组合穷举时会消耗大量能量的缺陷,从而大大延长无线传感器网络的生存期,提高了军事物流可视化的后勤保障能力。     

基于ORwgh的无线传感器网络定位算法在军事物流可视化中的应用研究

针对无线传感器网络的定位技术应用于军事物流可视化建设当中存在着非视距传播误差定位的问题,在传统的残差加权算法的基础上,提出了对原有算法的改进算法,即优先残差加权算法,该算法避免了由于距离测量值组合穷举时会消耗大量能量的缺陷,从而大大延长无线传感器网络的生存期,提高了军事物流可视化的后勤保障能力.     

基于K-Means聚类算法的配送中心物流成本分析

文章提出了一种基于聚类算法的配送中心选址问题。针对复杂的配送中心选址问题,利用聚类算法中的K-means算法解决配送中心选址问题,该算法的实证中解决了125个配送点的配送中心寻优问题,而且在选择配送中心时充分考虑客户的需求和各地实际情况(各地的消费能力、地理位置以及交通等),通过定量分析和定性分析结合的方式,建立起了二级配送网络。实证结果表明,该配送网络具有实际应用价值并具有良好的经济效果。     

一个基于命名网络的自稳定的选举算法

选举问题是分布式计算中的一个基本问题。它一直受到广泛关注,先后发表了一大批研究论文。但是,现有的研究较少涉及选举算法的自稳定性,已经提出的自稳定选举算法的性能还不能令人满意。针对两个经典的自稳定选举算法———AG算法和DIM算法进行了分析。AG算法适用于命名网络,算法虽然简单,但算法需要假设网络的大小是已知的并且时间复杂度为O(n2),其中n表示网络结点数目。DIM算法虽不需要网络大小假设是已知的,但其时间复杂度仍然需要O(ΔDlogn),其中Δ和D分别表示结点最大的度和树的深度。利用DIM算法的思想,在AG算法的基础上,提出了一个基于命名网络的自稳定选举算法。该算法不需要知道网络的大小,而且时间复杂度为O(δ)(δ为网络直径)。     

配电网络重构及其优化算法的研究

配电网络重构是提高电网运行效率、供电可靠性和供电质量的有效手段。该问题的求解属于一个大规模、混合整数、非线性的组合优化问题。文章阐述配电网络重构的相关概念，介绍各种配电网络重构的优化算法，包括数学优化理论、最优流模式法、开关交换法和各种智能优化算法的应用，并分析了各种算法的优缺点，对配电网络重构中要注意的问题进行了讨论。     

The network structure of knowledge sharing among physicians

This paper applies social network analysis in order to model knowledge sharing among hospital physicians. Drawing on the literature on the diffusion of innovation and cooperation in clinical settings, it aims to furnish better understanding of knowledge sharing in two directions: describing how knowledge flows and identifying individual and contextual factors which facilitate its spontaneous spreading. Used to address these issues is a link- tracing sample of about 800 Italian hospital physicians, potentially involved in prescribing a new drug. The paper represents knowledge sharing about the innovation as a network. It therefore specifies Exponential Random Graphs (ERG) or p* models to reconstruct the network structure of knowledge sharing and to test the effect of exogenous factors on the tendency to take action in the network. The results show that knowledge flows informally, exploiting mutual information-seeking relationships, and, consistently with previous studies, locally, with physicians tending to cluster in small groups of proximate and similar peers. Moreover empirical evidence is provided that the propensity to share information with colleagues is greatly affected by individual-specific characteristics, mainly by the experience in the field and the attitude toward the innovation, and by exposure to commercial communication.     

FTP用户隔离及应用

FTP是TCP/IP网络中计算机用于传输文件的协议,是Internet上出现最早,使用最为广泛的一种服务,基于客户机/服务器模式。本文详细介绍用IIS配置用户隔离的FTP服务器的两种方法,以及用户隔离的FTP服务器在计算机教学中的应用。     

Policy impacts on the propensity to travel by HSR in the Amsterdam – London market

This paper investigates the impacts of possible measures to enhance HSR market share in the London-Amsterdam market. To this aim, we adopted a two-level aggregate nested logit model able to jointly model trip distribution and trip generation, thus taking into account that the tested policies may increase or decrease the overall demand. The model was applied to an extensive dataset about passenger flows traveling between London airports and HSR station and Amsterdam in the period 2015–2019. The results show that both the reduction of HSR fares and the application of an air ticket tax, albeit with different impacts in terms of stimulus or reduction effect on overall demand, are ineffective in increasing HSR market share, if not adequately supported by improving HSR service. Increasing HSR frequency and reducing HSR travel times constitute the best opportunities to increase HSR ridership by stimulating a higher substitution effect than modifications in relative fares. Lastly, the recent queueing at airports, following staff shortages and strikes, significantly lower air transport demand and potentially has a substantial upward effect on HSR market share.     

Java网络编程:连接网络数据库的多种方法

Java是一种跨平台、健壮、安全、可移植,适合于分布式计算机环境的面向对象的编程语言,由于用Java开发的程序可以在网络上传输,并运行于任何客户机上,所以使用Java语言开发网络应用程序得到了越来越广泛的应用。本文结合Java网络编程的特点,介绍了基于TCP/IP协议如何建立TCPSocker实现与网络数据库连接的几种常用方法。     

Practical estimation of multivariate densities using wavelet methods

This paper describes a practical method for estimating multivariate densities using wavelets. As in kernel methods, wavelet methods depend on two types of parameters. On the one hand we have a functional parameter: the wavelet Ø (comparable to the kernel K ) and on the other hand we have a smoothing parameter: the resolution index (comparable to the bandwidth h ). Classically, we determine the resolution index with a cross-validation method. The advantage of wavelet methods compared to kernel methods is that we have a technique for choosing the wavelet Ø among a fixed family. Moreover, the wavelets method simplifies significantly both the theoretical and the practical computations.     

Interdicting interdependent contraband smuggling,money and money laundering networks

This paper focuses on the problem of interdicting the interdependent contraband smuggling, money and money laundering (ICSML) networks of a transnational criminal organization (TCO). There are four interdependencies among these networks: money flows from the physical contraband smuggling network to the money network, monetary support from the money network flows to the smuggling network, money flows from the money network to the laundering network and incentives from the laundering network flow to the physical and money networks. The goal of the TCO is to maximize a (weighted) balance between the profit and scale of the contraband smuggling business. The goal of law enforcement is to minimize the best possible performance of the TCO. A bi-level integer programming model is built to address the two-player nature of this decision-making environment that specifically captures the interdependencies of the criminal networks. A dual-based reformulation is applied to address the bi-level problem. Case studies of applying this reformulation technique to realistic data sets are presented with a particular focus on understanding how inaccurate information about the structure of the ICSML networks impacts the performance of interdiction decisions. Sensitivity analysis is performed to analyze this impact by examining selected interdictions for perturbations of the network. Insights obtained include an understanding of effective interdiction policies for these types of networks and what type of information is most critical to capture in order to make effective interdiction decisions.     

一种基于Winsock API实现实时通讯的新方法

TCP/IP协议是目前网络操作系统中主要的通讯协议,也是Internet的通讯协议。文章通过Winsock编程技术实现了对基于TCP/IP协议的面向连接的流方式套接字网络通讯程序的设计,并通过异步通讯和多线程等手段提高了程序的运行效率,避免了阻塞的发生。     

基于知识管理的企业技术创新集成网络模式

论述了基于知识管理的企业技术创新集成络模网式,指出知识管理的核心是知识集成与知识激活。分析建立了通过信息技术直接进行信息、知识和技术的积累、筛选、传递、共享和整合,使分散的专业知识转换为系统的、具体的知识的知识集成机制,以及使外界信息、知识在创新主体中传播、反射、折射,传输不同观点和意见,最后形成基于企业文化和人员素质之上的新创意的知识激活机制。具有紧密压缩的知识管理立体结构的集成络模网式,为企业技术创新信息化、网络化提供了存在的技术平台。     

浅析TCP/IP协议及其安全

本文主要讨论TCP/IP协议内容,以及TCP/IP协议的安全问题和几种常见的网络攻击手段。     

知识网络结构特性对知识流动作用分析

知识主体间相互联系、相互作用构成知识网络,知识在网络中流动,网络结构对知识流动的水平、效率和范围都有重要影响。网络结构从微观层面的节点维度和宏观层面的整体维度两个层次上影响知识流动。将知识网络结构特性对知识流动的作用做深入分析,对构建和动态演化知识网络的过程中改善网络结构,提高网络内知识流动的效率有重要意义。