基于扩展Petri网的雷达组网系统的建模与分析

利用扩展Petri网建立了雷达组网系统模型,通过模型的分析,解决了各雷达之间的同步问题,给出了系统冲突的处理方法,然后将扩展Petri网与排队论结合起来,定量描述了系统的统计性能;最后运用建立的模型进行了仿真实验。研究表明,扩展Petri网是雷达组网系统建模与分析的一种有效途径,为系统的结构优化与效能评估提供了依据。     

基于FPGA的有色Petri网仿真系统设计

为了实现大规模有色Petri网模型的性能测试,设计了基于FPGA的高速仿真系统。该系统实现了库所、变迁模块到硬件结构的映射,采用C语言实现了有色Petri网的硬件自动生成工具。通过分析有色Petri网的特征,该工具生成对应的Verilog代码和基于Quartus的自动脚本。以通信中"包传输"的模型为例,在FPGA中对生成的代码进行测试,验证了设计的正确性。     

基于层次实时有色Petri网的实时系统建模与分析方法研究

Petri网是一种基于图形进行模拟和分析的数学工具,能够描述系统的异步和并发行为,但是现有高级Petri网不能对嵌入式实时系统进行完整的模拟与实时性分析。该文首先通过扩展有色Petri网提出了层次实时有色Petri网模型,然后描述了嵌入式实时系统的建模和实时性分析方法。最后,将该文提出的方法应用于硬实时系统列车通信网络MVB总线控制器的建模和实时性分析过程,仿真和分析结果表明,该方法能够满足列车通信网络系统设计对MVB总线控制器的功能验证和实时性分析需求。     

基于模糊神经Petri网的武器装备效能评估模型

将模糊Petri与神经网络理论相结合,提出了一种关于武器装备效能评估的模糊神经Petri网模型.将模糊逻辑规则应用到专家评判中得到模糊Petri网,建立基于模糊Petri网的武器装备效能评估模型,并在此基础上将人工神经网络引入到模糊Petri中,在模糊Petri模型上,用迭代最速下降法对模型的参数进行学习和训练,经过学习和训练的模型具有很强的学习能力以及对外界环境的自适应能力.以某型雷达对抗装备为例进行仿真验证,仿真结果表明该模型是可行和有效的.     

门户网自助系统的扩展有色Petri网建模与分析

文章探讨了一种基于扩展有色Petri网的门户网自动生成系统,详细论述了有色Petri网与面向对象技术的融合方式,给出了面向对象的扩展有色Petri网的映射规则和形式化定义,并构建了门户网自动生成系统的ECPN模型,最后利用状态空间法和系统在实际生产中的效率统计,证明了模型的可用性、高效性。     

基于Petri网的入侵检测模型研究

随着计算机网络的广泛应用,非法的入侵与攻击行为不断发生,严重威胁着网络信息的安全,对入侵和攻击进行检测与防范已经成为刻不容缓的重要课题。讲述了Petri网(PN)和有色Petri网(CPN),通过将入侵分为“存在”,“顺序”,“偏序”三种类型,描述入侵检测系统(IDS)中的攻击模式用Petri网实现,并且给出了使用有色Petri网描述攻击模式。     

模糊Petri网的推理式算法在雷达电子战装备效能评估中的应用

基于模糊Petri网，研究了约束条件下的推理算法，将模糊Petri网与矩阵运算相结合．给出了雷达电子战装备效能评估的形式化推理算法。推理过程采用矩阵运算实现，并充分利用了模糊Petri网的并行处理能力．最后利用MATLAB语言对仿真实例进行分析计算，结果表明孩方法简单、快速和有效．不仅能评估单台电子战装备的作战效能，还能对同类型的多台装备进行作战效能的优劣排序。     

自适应OFDMA系统无线资源管理的CPN建模与仿真

基于自适应OFDMA系统,对多业务系统中基于总发射功率最小化的无线资源管理问题进行研究,并使用着色Petri网(CPN,coloured Petri nets)以及CPN分析工具CPN Tools对其进行建模。采用Monitor监控器对模型进行仿真分析,并将仿真结果与随机Petri网(SPN,stochastic Petri nets)模型以及基于吞吐量最大化的CPN模型进行比较,验证了该系统模型的正确性和优越性。     

相控阵雷达T/R组件的效费比随机petri网维修模型

针对T/R组件在备件库存、保障模式以及维修策略方面的特点,建立了两级维修保障体制下相控阵雷达的效费比随机Petri网模型。首先对随机Petri网性能存在的不足进行分析,并对其进行改进,引入抑制弧和全局时间,建立了多部件条件下不同连接方式的系统Petri网模型;其次以多部件当中的k/N系统连接方式为基础,建立了相控阵雷达系统的Petri网模型并进行实例验证;最后对模型中的使用可用度和单位时间维修费用进行分析。实例仿真表明,该Petri网模型可信度高,可以分析基层级和基地级初始备件数量、维修策略参数(m,NG)对系统保障效能的影响,克服了传统解析方法建模的局限,更加贴合实际。     

反射式需求工程过程演化建模

用反射机制为软件系统需求工程过程演化建模,将需求工程过程的开发活动作为反射系统的基层,实现软件系统的功能需求,将软件系统的非功能需求作为反射系统的元层,对需求工程过程的开发活动进行调节、控制,并将非功能需求的性质反射到功能需求.定义了有色Petri网及其范畴,并用有色Petri网范畴描述软件系统非功能需求性质的模拟、保持和反射机制;用有色Petri网建立反射式需求工程过程演化形式化模型,模拟了软件系统需求工程过程中功能需求和非功能需求的迭代、增量、演化,为软件系统需求工程过程演化建模提出了一种新的方法.     

基于赋时层次有色Petri网的Multi-Agent调度系统建模

介绍了基于Multi-Agent的分布式环境扫描系统的结构模型.依据赋时层次有色Petri网(HTCP-net)的理论,应用建模、仿真工具CPN Tools建立了基于优先级的任务调度算法和最短等待队列动态负载均衡调度算法的系统调度模型.仿真结果表明,该调度模型有效满足了系统周期性重复访问网站的任务需求.     

Modeling radio resource management in cognitive radio system based on OFDMA using colored Petri Net

Cognitive Radio (CR) system based on Orthogonal Frequency Division Multiple Access (OFDMA), such as Wireless Regional Area Networks (WRAN) and Worldwide Interoperability for Microwave Access (WiMAX), often attempt to improve performance via dynamic radio resource management, which is characterized as concurrent processing of different traffic and nondeterministic system capacity. It is essential to design and evaluate such complex system using proper modeling and analysis tools. In the previous work, most of the communication systems were modeled as Markov Chain (MC) and Stochastic Petri Nets (SPN), which have the explicit limitation in evaluating adaptive OFDMA CR system with wide area traffic. In this paper, we develop an executable top-down hierarchical Colored Petri Net (CPN) model for adaptive OFDMA CR system, and analyze its performance using CPN tools. The results demonstrate that the CPN can model different radio resource management algorithms in CR Systems, and the CPN tools require less computational effort than Markov model using Matlab, with its flexibility and adaptability to the traffics which arrival interval and processing time are not exponentially distributed.     

TCP拥塞控制建模分析方法

随着互联网技术的迅猛发展,传输控制协议(TCP)传输面临越来越严重的拥塞问题。为了更深入了解拥塞现象发生的原因,设计有效的拥塞控制机制,基于着色Petri网性能评价理论,论述了TCP传输控制建模分析的方法,分析了拥塞发生中拥塞窗口和缓存队列的变化过程。在分析结果的基础上,提出了在设计拥塞机制时应综合考虑窗口大小和缓存大小,在控制发送速率的基础上,达到较好的带宽利用率。     

一种新型的LTE-A网络切换认证协议

针对典型蜂窝网络LTE-A网络的切换认证问题,本文通过引入SDN（Software Defined Network,软件定义网络）,提出了软件定义LTE-A异构网络架构,在中心控制器中共享UE（User Equipment,用户设备）的安全上下文信息,以实现简化切换认证过程,提高认证效率的目标.中心控制器的加入,使蜂窝与核心网通信时需要增加一次信令开销,而LTE-A网络的标准切换认证方法过于复杂,应用在软件定义LTE-A异构网络中,会产生较多的信令开销.基于代理签名的切换认证方法,使UE在验证身份时不用经过核心网,减少了信令开销.在安全性相同的情况下,基于椭圆曲线的加密体系比基于RSA的加密体系计算量更小,有利于减少中心控制器的计算压力.本文采用椭圆曲线代理签名方法,提出了一种新型的切换认证协议,并运用着色Petri网进行建模和仿真分析.仿真结果表明,该协议是有效的,且安全性更高.     

基于Petri网的复杂可修复系统可靠性仿真研究

为了在复杂可修复系统的可靠性模型中引入修复过程,实现系统使用维修保障全过程仿真,使用Petri网建立了一种可修复系统的可靠性模型,通过模型内部token的移动控制系统组成单元的状态。以某型飞机为例进行了仿真。仿真结果表明,模型易于实现,具有较好的拓展性,可以有效地反映系统的修复过程,从而为系统的使用维修保障全过程仿真提供条件。     

Modeling and Performance Analysis of Cognitive Radio Networks Using Stochastic Timed Colored Petri Nets

Cognitive radio (CR) is currently one of the most promising information transmission technologies to deal with the problem of spectrum scarcity and spectrum underutilization in wireless communications. CR networks aim to enhance spectrum efficiency to meet the ever-increasing demands of end users. The principle is to provide the opportunity for unlicensed users (secondary users, SUs) to temporarily and dynamically access the unused or sparsely used bandwidth while ensuring that it never interferes or degrades the performance of the incumbent license holders, commonly called primary users (PUs). This raises several challenges to be addressed in CR networks and performance of secondary users is one of the critical issues tackled in this paper. That is, we propose to devise CR networks as a retrial queueing system where PUs have preemptive priority over SUs. To calculate performance measures of the devised model under quite general assumptions about the model parameters, analytical methods are known to require hard calculations and the obtained results are generally not exploitable. For this reason, simulation modeling becomes the last resort to assess the dependability indicators. To this extend, we build the simulation model of the queueing system using Timed Stochastic Colored Petri Nets. Various useful results will be hence drawn while varying network conditions. Both exponential and Erlang distributions are considered for modeling service time of SUs. The obtained results with restrictive assumptions fit the analytical outcomes experienced for quite similar queuing models, which demonstrate the effectiveness of the proposed STCPN simulation model.

     

A Security Protocol Resistant to Intermittent Position Trace Attacks and Desynchronization Attacks in RFID Systems

Radio frequency identification (RFID) technology will become more popular in various applications in the near future. But the security issues in RFID systems have hindered this technical promotion seriously. The extant RFID security protocols have serious insufficiency and flaws to resistance trace attacks and desynchronization attacks. In this paper, we propose a security protocol that can against the intermittent position trace attacks and desynchronization attacks. We prove the security of the proposed protocol by data reduction method with the learning parity with noise and formally verify the functionality of the proposed scheme by using Colored Petri Nets.     

含有非马尔可夫过程的排队Petri网模型和性能分析

本文提出了一种新的高级性能模型技术,称作NM-QPN(含有非马尔可夫过程的排队Petri网,Queuing Petri Net including Non-Markovian processes),它综合了排队网,随机Petri网以及模拟求解各自的特点.NM-QPN以模拟模型为总体框架,发挥排队网和随机Petri网各自的优势对系统进行建模.提出了一套完整的NM-QPN模型求解方案,通过流等价方法将模型中的马尔可夫过程进行化简,这样可以大大减少模型的状态,最后再用模拟求解方法求解剩下的非马尔可夫过程.     

Modeling multi-traffic admission control in OFDMA system using Colored Petri Net

Call Admission Control (CAC) is one of the key traffic management mechanisms that must be deployed in order to meet the strict requirements for dependability imposed on the services provided by modern wireless networks. In this paper, we develop an executable top-down hierarchical Colored Petri Net (CPN) model for multi-traffic CAC in Orthogonal Frequency Division Multiple Access (OFDMA) system. By theoretic analysis and CPN simulation, it is demonstrated that the CPN model is isomorphic to Markov Chain (MC) assuming that each data stream follows Poisson distribution and the corresponding arrival time interval is an exponential random variable, and it breaks through MC??s explicit limitation, which includes MC??s memoryless property and proneness to state space explosion in evaluating CAC process. Moreover, we present four CAC schemes based on CPN model taking into account call-level and packet-level Quality of Service (QoS). The simulation results show that CPN offers significant advantages over MC in modeling CAC strategies and evaluating their performance with less computational complexity in addition to its flexibility and adaptability to different scenarios.     

A Smart Card Based Efficient and Secured Multi-Server Authentication Scheme

Increasing popularity of the multi-server architecture has propelled the research on the multi-server authentication schemes. Current dominating authentication schemes are smartcard based, verification table free schemes with passwords. Although these schemes have developed to be robust against most of the popular malicious attacks, they still have security weaknesses and their efficiency is generally low. In this paper, we analyze and formulate security issues in previously proposed schemes. And based on the formulation, an enhanced efficient and secure scheme is proposed. In the proposal, a novel “redundant key protection” is proposed to utilize. The proposed scheme is validated and verified by Colored Petri Nets.