一种随机Petri网性能等价化简与分析方法

随机Petri网模型是系统性能评价的有力工具,但其状态空间随模型规模的增长而指数性增长的问题限制了其对复杂和大规模系统模型的性能数量分析能力.因此,在对模型进行分析之前,先对其进行适当的性能等价化简,是一种更为可行的分析方法.本文首先讨论了一类随机Petri网-基本随机Petri网(ESPN)的性能等价分析方法,这类随机Petri网由顺序、并行、选择和循环等四种基本结构及其组合构成.作者推导出这四种基本结构的性能等价公式,并运用自底向上逐步综合替代的分层分析方法,给出这类随机Petri网模型的性能等价化简分析方法,该方法的复杂性随模型增长而线性增长,有效解决了其性能数量分析问题.然后,讨论了两种非基本结构到基本结构的转换规则,使得复杂的随机Petri网模型也可能转换为ESPN模型,从而使性能等价算法可应用于一般随机Petri网.     

MapReduce的随机Petri网模型研究

首次提出用随机Petri网为MapReduce逻辑模型建立Petri网模型的思想,目的在于采用随机Petri网工作流性质对其进行分析。因此,在研究MapReduce逻辑模型的基础上,为其建立了随机Petri网模型。该随机Petri网模型符合随机Petri网工作流系统的性质,本文利用随机Petri网的工作流系统的性能等价公式,分析了模型的性能,最终求出整个系统的性能参数。该性能参数能够很好地说明MapReduce处理大数据集的优势。     

随机Petri网模型中变迁的串、并联性能等价化简技术

随机Petri网的状态空间爆炸问题的研究始终是Petri网研究的主要问题之一.在随机Petri网模型中,变迁的串、并联是Petri网模型的主要基本形式,对它的化简不仅有助于解决随机Petri网状态空间的爆炸问题,而且也为其他随机Petri网的化简技术提供一个坚实的基础.另外在诸如工作流、多媒体等重要的随机Petri网模型中也存在大量的变迁的串、并联结构,所以对随机Petri网模型变迁的串、并联的化简,特别是能够推导出它的性能等价的数学公式就显得很有必要.本文详细阐述了随机Petri网变迁的串并联的模型化简技术,推导出了变迁的串、并联化简的性能等价公式,并给出一个化简的例子,最后对结果的相关问题进行了分析.     

一种基于逻辑Petri网的过程挖掘方法

逻辑Petri网是抑制弧Petri网和高级Petri网的抽象和扩展,可在过程挖掘中简洁准确的表示活动之间复杂的业务逻辑关系.本文在传统Petri网挖掘方法的基础上,为了进一步提高复杂系统挖掘模型的简洁度和拟合度,尤其是对并行活动间存在复杂与或关系的系统,提出了一种基于逻辑Petri网的过程挖掘方法,并给出了逻辑Petri网中逻辑变迁的挖掘算法.它可以充分挖掘活动之间的业务逻辑,并且业务逻辑可用逻辑表达式表示.通过与相应Petri网模型的实例比较分析,例证了本文方法的正确性和有效性,且逻辑Petri网模型更加适合日志行为.     

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。     

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.     

扩展的模糊时间Petri网

网络实时系统对时间和QoS有严格要求.扩展的模糊时间Petri网是一种对网络实时系统进行建模和分析的形式化模型,Petri网数学理论基础能保证并发系统的可靠性和正确性.本文介绍了扩展的模糊时间Petri网的定义,模型检验方法,仿真工具,网精简技术和应用领域,并探讨了进一步研究的方向.     

城市公交故障抢修的随机Petri网建模及分析

针对城市公交运行过程中紧急抢修故障车的效率问题,本文基于随机Petri网建立了城市公交运行故障的抢修模型,利用随机Petri网与马尔可夫链的同构关系,得到了抢修模型稳定的状态空间及各状态出现的概率,进而分析了抢修过程各环节的利用率及各状态的时间属性,为抢修效率的提高提供了相关依据.实例验证模型分析的有效性,通过对某些抢修环节的改善和提高,进而提高公交故障抢修的效率.     

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。     

基于Petri网的入侵检测技术研究

Petri网是一种非常广泛的建模工具.文中研究了Petri网在入侵检测技术中的应用,分析了基于Petri网的入侵检测系统的主要优势以及随着网络的发展给入侵检测系统带来的问题.基于这些问题,提出了基于Petri网的入侵检测系统的改进方法,设计了一个入侵检测系统的原型并进行了实例分析.     

物元分析方法在通信网可靠性评价中的应用

本文主要研究物元分析方法在通信网可靠性评价中的应用，首先应用物元变换方法对通信网可靠性评价的研究思路进行了转换，提出了分析可靠性增长与通信网发展的相关适应性的物元评价方法。这种方法的应用在实际中显示出较好的效果。     

System Effectiveness Models: An Annotated Bibliography

A state-of-the-art survey on system effectiveness models is presented. A variety of system effectiveness models dealing with military and space systems have been developed by the US Air Force, Army, and Navy. Each model has different attributes in its definition of system effectiveness. This survey classifies these attributes and definitions and presents their relationship to system effectiveness. Attributes included are reliability, availability, operational readiness, repairability, maintainability, serviceability, design adequacy, capability, dependability, human performance, and environmental effects. The system effectiveness models and their computer codes are also classified and reviewed.     

Public networks-dependable?

The dependability of public networks is analyzed. The growing reliance of all segments of society on public telecommunications networks is described. The challenge in maintaining traditional dependability levels in the face of new network constructs having less inherent reliability is discussed. A new measurement for network quality and standards for public network dependability are proposed     

基于BPN和SPN模型的系统性能分析方法

本文讨论了ＢＰＮ的基本概念，给出了ＢＰＮ典型的Ｐｃｔｒｉ网模型、分析方法和分析性质，描述了由ＢＰＮ扩展的ＳＰＮ和ＤＴＳＰＮ的概念，结合ＳＰＮ和ＤＴＳＰＮ模型实例给出了它们同构的ＭａｒｋｏｖＣｈａｉｎ（ＭＣ）、标记概率和标志概率的计算结果。实践表明，ＳＰＮ能为具有随机过程的系统进行建模和定量分析，是扩展的ＢＰＮ中一种十分有用的分析工具．     

Dependable computing: From concepts to design diversity

This paper is composed of two sections. The first provides a conceptual framework for expressing the attributes of what constitutes dependable and reliable computing: a) the impairments to dependability (faults, errors, and failures), b) the means for dependability (fault avoidance, tolerance, removal, and forecasting), and c) the measures of dependability (reliability, availability, safety). The second section focuses on one of the most challenging problems for dependable computing: coping with design faults.     

基于SPN的5G承载网的网络切片规划方案

5G担负着转型升级赋能千行百业的重要使命,对5G承载网提出新需求。本文先介绍SPN网络的能力,包括灵活调度、高可靠性、低时延等,接着结合业务需求,提出SPN网络切片管理要求、规划思路和方案,为网络建设提供参考。     

Supporting Mobile Commerce Applications Using Dependable Wireless Networks

Mobile commerce (m-commerce) is an emerging discipline involving applications, mobile devices, middleware, and wireless networks. While most of existing e-commerce applications can be modified to run in a wireless environment, m-commerce also involves many more new applications that become possible only due to the wireless infrastructure. These applications include mobile financial services, user and location specific mobile advertising, mobile inventory management, wireless business re-engineering, and mobile interactive games. In addition to device and wireless constraints, mobile commerce would also be impacted by the dependability of wireless infrastructure. Unlike e-commerce applications that usually run on fixed networking infrastructure of fairly high dependability (approaching to about 100%), m-commerce applications may not receive such high dependability from the existing and emerging wireless infrastructure. So far, most of the m-commerce research focuses on applications, devices, and security issues. We believe that some work is necessary in addressing the dependability challenges of the wireless infrastructure. In this paper, we present (a) the dependability issues of wireless infrastructure, (b) several architectures to improve the dependability of wireless networks, and (c) a simulation model and results on wireless dependability for m-commerce. The results show that a significant improvement is possible in wireless dependability for supporting m-commerce applications.     

基于SPN模型的卫星网络性能评价

基于随机Petri网(SPN)模型方法,分别对LEO单层卫星网络和LEO/MEO双层卫星网络进行了性能分析.首先分析了卫星网络的特点,并在此基础上建立了半双工通信模式下LEO单层卫星网络的SPN模型、全双工通信模式下LEO/MEO双层卫星网络的SPN模型.然后,选取平均时延作为网络性能评价指标、采用SPNP6.0软件对上述两个SPN模型进行了性能评价.最后,对两个模型的性能评价结果进行了对比分析,得出了有关在网络负载变化情况下LEO单层卫星网络和LEO/MEO双层卫星网络的性能优劣比较结论.     

Multilevel fault tolerance in infrastructure‐oriented wireless networks: framework and performance evaluation

Significant advances have been made in the design and implementation of dependable systems and networks over the last several years. However, many wireless networks have not been designed for highly dependable operation owing to network cost and complexity, and a lack of regulatory requirements on wireless service quality. One way to address this significant challenge is by introducing fault tolerance; however, very limited work has been done so far in the fault‐tolerant design of wireless networks. In this paper, we address how to utilize fault tolerance in the design of infrastructure‐oriented wireless networks. More specifically, an architectural design scheme is presented for multilevel fault tolerance using adaptable building blocks. The scheme utilizes ‘selective’ redundancy at component, link and block levels and a fault‐tolerant architecture for interconnection of building blocks. The design scheme has been implemented in both analytical and simulation models. The detailed performance results show that fault tolerance at component, link, block, and interconnection levels can significantly improve the overall dependability performance. One interesting observation is that, to achieve highest dependability, fault tolerance at link, component or block level is not sufficient and must be combined with the interconnection level fault‐tolerance. Copyright © 2006 John Wiley & Sons, Ltd.     

基于随机Petri网模型的低轨卫星网络性能分析

基于随机Petri网(SPN)模型方法,对LEO单层卫星网络进行了性能分析.首先建立了半双工通信模式下LEO单层卫星网络的SPN模型,并选取平均时延作为网络性能评价指标、采用SPNP6.0软件对该SPN模型进行了性能评价,分析了数据包到达速率、网络负载以及消息数等参数对网络平均时延的变化关系.该建模与性能评价方法将有助于卫星网络的构建和进一步的性能分析.