基于NS的移动网络仿真研究

仿真技术在现代通信网络设计中的作用越来越大,为了在仿真环境下对网络协议进行性能评价,必需对仿真结果进行有效的分析和处理。文中通过介绍网络仿真软件NS体系结构及安装过程,并结合具体仿真实例,着重讨论了其在移动网络仿真过程中的应用。在分析NS的跟踪输出格式的基础上讨论了仿真结果的处理,这对于NS软件的使用及网络协议的研究具有较强的实用价值。     

基于NS的移动网络仿真研究

仿真技术在现代通信网络设计中的作用越来越大,为了在仿真环境下对网络协议进行性能评价,必需对仿真结果进行有效的分析和处理.文中通过介绍网络仿真软件NS体系结构及安装过程,并结合具体仿真实例,着重讨论了其在移动网络仿真过程中的应用.在分析NS的跟踪输出格式的基础上讨论了仿真结果的处理,这对于NS软件的使用及网络协议的研究具有较强的实用价值.     

基于Adalines的模型跟踪自适应控制

本文根据双层Ａｄａｌｉｎｅｓ逼近任意非线性函数的特性构造神经网络控制器，并采用一参考模型的输出与实际被控系统的输出之差对该神经网络控制器进行ＢＰ算法学习训练。从而在保证控制系统稳态性能的同时提高了控制系统的动态响应性能。最后把此基于Ａｄａｌｉｎｅｓ的模型跟踪自适应控制策略用于车削系统并进行了仿真实验。     

基于状态观测器的单相逆变电源仿真技术研究

基于单相逆变电源的数学模型,设计了一种能保证系统渐进稳定的控制方案。方案根据李氏稳定理论进行设计,并利用观测器观测控制律中的状态变量,同时采用滤波器对原始参考输出信号进行处理,用以产生控制律所需的连续光滑的输出信号及其微分量,设计保证了系统的稳定性及输出电压跟踪误差的收敛性。利用仿真工具MATLAB/SIMULINK对所设计的方案进行仿真,仿真结果验证上述方案的正确性。     

规模化养殖场全程监控系统的应用

规模化养殖场生产环境自动监控、监视、产品运输监控跟踪信息系统,全方位监视监控产品生产、销售的各个环节,提高产品质量。全场测控信息通过控制网络传至监控计算机,进行存储、显示、分析、输出,管理者能实时监控生产现场。利用GPS卫星定位跟踪和视频监视监控技术,在运输车辆内安装信号发射仪、视频监控设备、自动控温控湿设备、车辆运输控制等设备,对企业的运输车辆运行位置进行卫星定位跟踪,运输车辆内环境监控,确保鲜活产品运输过程中健康安全。     

基于目标跟踪的双层结构工业预测控制

针对基于二次规划的稳态目标跟踪问题,给出一种统一的处理方法.该方法不仅可以通过加权协调各个目标的跟踪,还可通过惩罚跟踪偏差体现对输出目标跟踪的偏重.分析该方法的可行性,得到了同时适合于多优先级稳态目标优化的无静差控制的结论.仿真结果验证了所提出方法的有效性.     

基于自动识别系统的长江控制河段船舶视觉伺服跟踪方法

针对狭窄弯曲的控制河段目标船舶跟踪监视难度大,直接采用现有海事视频跟踪监视方法存在跟踪滞后、对准误差,乃至目标丢失的问题,提出了采用船舶自动识别系统(AIS)与多个云台摄像机联动的方式对控制河段船舶进行主动跟踪监视。云台摄像机根据目标船舶的经纬度进行初始对准;同时结合船舶航速、航向进行动态预测跟踪以平滑图像并消除跟踪滞后;进一步运用目标船舶图像识别进行误差校正,以保证目标船舶始终处于最佳监视区域。仿真结果表明,该算法可对目标船舶进行连续、动态跟踪,实时性好,准确性高。     

TCAS Ⅱ与ADS-B数据融合新算法

针对空中交通流量越来越大,TCAS Ⅱ无法满足日益增长的防撞需求,提出了根据估计误差协方差最大特征值加权的数据融合算法.该算法首先分析TCAS Ⅱ和ADS-B的原理和特点,阐述了结合ADS-B优势发展组合监视的必要性,重点介绍组合监视区域,采用Kalman滤波对飞机进行目标跟踪,对局部滤波得到的航迹进行加权融合,得到最优估计,对算法进行仿真,结果验证该算法能够得到较高精度数据,黾高监视能力,增强防撞性能.     

具有减少辨识参数的随机多变量极点配置自适应控制器

本文提出了一种新的限制输出个数减少随机多变量自适应控制中辨识参数的方法，并给出了减少辨识参数的极点配置自适应算法。虽然采用ｎ个输入１个输出的减少辨识参数的模型来设计控制器，但所提出的控制器能够保证被控系统的几个输出跟踪参考输入信号，仿真结果表明，所提出的方法是成功的。     

隐层神经元饱和化与稳健性研究

本文通过对多层前向网络（ＭＬＦＮＮ）中隐层神经元激活函数的中强迫饱和化,降低了网络输出对输入的敏感性,进而改善了网络瓣稳健性（Ｒｏｂｕｓｔｎｅｓｓ）。文中给出了相关概念和理论分析,同时以函数逼近问题为例进行了相应的计算机仿真,其结果证明了理论分析的正确性。     

An analysis of conformance issues in implementations of standardized security protocols

In the last years the amount of information being transmitted through communication networks has increased, and this has lead to an increased use of security protocols. The implementations of security protocols do not accurately follow the standards and this causes many malfunctions and security flaws. In this paper we will analyze the different approaches followed by the scientific community to evaluate security protocols' implementations, and will also analyze the special characteristics of security protocols, in order to deduce which are the key points for such an evaluation, how they can be evaluated and also if existing evaluation techniques can be used.     

Adaptive Threat Modeling for Secure Ad Hoc Routing Protocols

Secure routing protocols for mobile ad hoc networks provide the required functionality for proper network operation. If the underlying routing protocol cannot be trusted to follow the protocol operations, additional trust layers, such as authentication, cannot be obtained. Threat models drive analysis capabilities, affecting how we evaluate trust. Current attacker threat models limit the results obtained during protocol security analysis over ad hoc routing protocols. Developing a proper threat model to evaluate security properties in mobile ad hoc routing protocols presents a significant challenge. If the attacker strength is too weak, we miss vital security flaws. If the attacker strength is too strong, we cannot identify the minimum required attacker capabilities needed to break the routing protocol. In this paper we present an adaptive threat model to evaluate route discovery attacks against ad hoc routing protocols. Our approach enables us to evaluate trust in the ad hoc routing process and allows us to identify minimum requirements an attacker needs to break a given routing protocol.     

概率转发的移动自组织网络路由协议

Ad Hoc网络节点能量受限的路由协议的研究是目前的一个热点,IETF的MANET小组提出的几种经典的路由协议,属于最短路由,即最小跳数路由,没有考虑能量因素。由于Ad Hoc网络中的节点是由电池供电,整个网络是一个能量受限系统,如何节省节点的能量,尽可能延长网络的可操控时间逐渐成为衡量路由协议性能的重要指标。基于移动节点的能量级别,采取不同的转发概率,提出了一种Ad Hoc网络基于概率的路由协议——PBR,并与AODV协议进行了性能比较,仿真结果显示,PBR明显改善了系统的能量消耗,延长了网络的存活时间,并且具有较优的可扩展性。     

Intra-domain routing convergence with centralized control

The decentralized control scheme for routing in current IP networks has been questioned, and a centralized routing scheme has been proposed as an alternative. In this paper, we compare the convergence of centralized control scheme with decentralized link-state routing protocols. We first review the architectural advantages and challenges of centralized control. Thereafter, we identify and discuss the components of the convergence time in both schemes. We present how to achieve fast routing convergence in networks with centralized control. In particular, we analyze how to distribute forwarding information efficiently. Finally, we perform simulation studies on the convergence time for both real and synthetic network topologies and study the impact of control element location, link weights, and number of failures on the convergence time. The results show that the centralized control scheme can provide faster routing convergence than link-state routing protocols.     

Performance analysis of CSMA and BTMA protocols in multihop networks (I). Single channel case

Busy tone multiple access protocols have been used in multihop networks to reduce the effect of the hidden terminal problem. Due to complexity, the performance of these protocols for large networks has not been analyzed. In this paper, using a Markov chain model and an approximation, we are able to analyze and evaluate the throughput performance of the non-persistent CSMA protocol, the conservative busy tone multiple access (C-BTMA) protocol and the ideal destination-based busy tone multiple access (ID-BTMA) protocol for large networks. The throughput comparison of the protocols is given. The results show that in a large multihop network, the BTMA protocols have a better performance than the non-persistent CSMA protocol and the ID-BTMA protocol has a better performance than the C-BTMA protocol at light channel loads.     

NBPSim:基于NS2的P2P仿真框架

为了推进拓扑感知的P2P算法的研究,提出了一个基于NS2的P2P仿真框架:NBPSim.可以通过扩展NBPSim给出的扩展点方便地开发P2P协议模拟程序,并进行包括底层网络细节的仿真验证.描述了NBPSim的框架结构,同时给出了在此平台上仿真Chord协议的结果.     

Message logging: pessimistic, optimistic, causal, and optimal

Message-logging protocols are an integral part of a popular technique for implementing processes that can recover from crash failures. All message-logging protocols require that, when recovery is complete, there be no orphan processes, which are surviving processes whose states are inconsistent with the recovered state of a crashed process. We give a precise specification of the consistency property “no orphan processes”. From this specification, we describe how different existing classes of message-logging protocols (namely optimistic, pessimistic, and a class that we call causal) implement this property. We then propose a set of metrics to evaluate the performance of message-logging protocols, and characterize the protocols that are optimal with respect to these metrics. Finally, starting from a protocol that relies on causal delivery order, we show how to derive optimal causal protocols that tolerate f overlapping failures and recoveries for a parameter f (1⩽f⩽n)     

Configuration of network management for energy efficiency in optical transport networks using GMPLS and OBS techniques

The suboptimal distribution of the traffic load over the high-speed optical network channels results in poor overall channel utilization and leads to the increased energy consumption. This means that configuration of the network management system including traffic engineering protocols and traffic management mechanisms may have indirect but significant impact on the overall energy efficiency of the particular optical transport network setup. Therefore, we aim in this paper to estimate how energy efficiency of the optical transport network depends on the configuration of the management protocols and mechanisms deployed into the GMPLS and OBS technologies. In addition, we analyze particular configurations of specific mechanisms those allow to increase energy efficiency of the optical transport network without compromising the parameters of the quality of service (QoS).