Innovative Services for Electric Mobility Based on Virtual Sensors and Petri Nets

About 60%of emissions into the earth’s atmosphere are produced by the transport sector,caused by exhaust gases from conventional internal combustion engines.An effective solution to this problem is electric mobility,which significantly reduces the rate of urban pollution.The use of electric vehicles(EVs)has to be encouraged and facilitated by new information and communication technology(ICT)tools.To help achieve this goal,this paper proposes innovative services for electric vehicle users aimed at improving travel and charging experience.The goal is to provide a smart service to allow drivers to find the most appropriate charging solutions during a trip based on information such as the vehicle’s current position,battery type,state of charge,nearby charge point availability,and compatibility.In particular,the drivers are supported so that they can find and book the preferred charge option according to time availability and the final cost of the charge points(CPs).To this purpose,two virtual sensors(VSs)are designed,modeled and simulated in order to provide the users with an innovative service for smart CP searching and booking.In particular,the first VS is devoted to locate and find available CPs in a preferred area,whereas the second VS calculates the charging cost for the EV and supports the driver in the booking phase.A UML activity diagram describes VSs operations and cooperation,while a UML sequence diagram highlights data exchange between the VSs and other electromobility ecosystem actors(CP operator,EV manufacturer,etc.).Furthermore,two timed Petri Nets(TPNs)are designed to model the proposed VSs,functioning and interactions as discrete event systems.The Petri Nets are synchronized by a single larger TPN that is simulated in different use cases and scenarios to demonstrate the effectiveness of the proposed VSs.

Boundedness and liveness enforcement for labeled Petri nets using transition priority

This paper deals with the supervisory control problem of discrete event systems modeled by labeled Petri nets. The system is originally unbounded. First, the solvability of the problem is confirmed. A necessary condition is given and proven for the existence of a feasible priority-based controller based on the notions of liveness and transition invariants. Next, a cyclic behavior graph is constructed, which shows the reachable markings that guarantee the maximum liveness of the system within a given bound vector. Finally, an on-line control strategy is proposed to enforce boundedness and liveness to the given system by appending priority relations to transitions. The dynamic priority relation changes flexibly according to the current state of the system and enforces the system evolving in a bounded and live manner. In addition, numerical examples are studied to verify the validity of the proposed approach that remains the structure of the plant net and is efficient for on-line control.

Research on Petri Net Based Modeling and Analyzing Methods for Workflow Process

Workflow management is an important aspect in CSCW at present. The elementary knowledge of workflow process is introduced, the Petri nets based process modeling methodology and basic definitions are provided, and the analysis and verification of structural and behavioral correctness of workflow process are discussed. Finally, the algorithm of verification of process definitions is proposed.

Resource Allocation Using Timed Petri Nets and Heuristic Search

Traditional models for project management have not adequately incorporated a number of factors that are important for resource allocation. This paper proposed a unified timed Petri net model in which scheduling and planning were collectively carried out to take full advantages of the flexibility of the FMS. Through the lens of system theory, two types of resources were distinguished: major role and auxiliary role, and the major role was used to construct the FMS' Petri net. The method simplified the Petri net's construction and gave a clear flow chart for scheduling. Hence, the auxiliary resource allocation could be easily carried out according to the schedule, which was proposed by heuristic search algorithm. At last, the efficacy of the Petri net model for online scheduling in a resource constrained environment was discussed.

Structural Complexity Analysis of Information Systems Based on Petri Nets

Aim To present a quantitative method for structural complexity analysis and evaluation of information systems. Methods Based on Petri net modeling and analysis techniques and with the aid of mathematical tools in general net theory(GNT), a quantitative method for structure description and analysis of information systems was introduced. Results The structural complexity index and two related factors, i.e. element complexity factor and connection complexity factor were defined, and the relations between them and the parameters of the Petri net based model of the system were derived. Application example was presented. Conclusion The proposed method provides a theoretical basis for quantitative analysis and evaluation of the structural complexity and can be applied in the general planning and design processes of the information systems.

An Effective Approach to Verify the Correctness of Workflow Process Models Based on Petri Net

Along with the extensive use of workflow, analysis methods to verify the correctness of the workflow are becoming more and more important. In the paper, we exploit the verification method based on Petri net for workflow process models which deals with the verification of workflow and finds the potential errors in the process design. Additionally, an efficient verification algorithm is given.

Study of Object Oriented Petri Net and Its Application in Flexible Manufacturing Cells

This paper presents an object oriented Petri net (OOPN) schema to model the dynamic behaviors of a flexible manufacturing cells (FMCs). The OOPN paradigm incorporates the characteristics of a Petri net and OOP. It increases the maintainability and reusability of objects in Petri net modeling, thus it has more powerful modeling and analysis abilities.

Controller Design of DES Petri Nets with Mixed Constraint

The problem of constructing a Petri net feedback controller, which enforces the conjunction of a set of linear inequalities on the reachable marking of the place and transition modeled by Petri net, is discussed. A new method of controller design with mixed constraint is presented, and a net reduction technique of Petri net fuses all the constrained places into one place whose marking is equal to the sum of the markings of the constrained places, and then compared with the constrained transitions. The net reduction eases the design of controller and holds remarkable advantages especially for systems with large scale. The method is proved to be simpler and more efficient than the method presented by Yamalidou, et al, using an applied case used by Yamalidou, et al.

Integrated automatic HAZOP analysis and fault diagnosis based on Petri net

Based on systematically analyzing the procedure of hazard and operability (HAZOP) study, the author introduces a method of modeling fault diagnosis with the Petri net with fuzzy colors, in which the fuzzy information can be represented effectively in the process of analysis. The author proposes the architecture of a knowledge base, which integrates HAZOP analysis and fault diagnosis, and provides the conditions for constructing the knowledge-based expert system. The author also presents a method of knowledge representation for on-line HAZOP analysis and on-line fault diagnosis is presented based on the technology of Petri net with fuzzy colors, which establishes a technological fundamental for integrating the automatic HAZOP analysis and fault diagnosis.

Methods for behavior descriptions of structure-complex Petri nets

Petri net language is a powerful tool for describing dynamic behaviors of physical systems. However, it is not easy to obtain the language expression for a given Petri net especially a structure-complex net. In this paper, we first analyze the behaviors of S-nets, which are structure-simple. With the decomposition method based on a given index function on the place set, a given structure-complex Petri net can be decomposed into a set of structure-simple S-nets. With the language relationships between the original system and the decomposed subnets, an algorithm to obtain the language expression of a given structure-complex net system is presented, which benefits the analysis of physical systems based on the Petri net language.

Petri Nets—A Versatile Modeling Structure

Petri Nets (PNs) are an effective structure for modeling and analyzing asynchronous systems with concurrent and parallel activities. A Petri net models the static properties of a discrete event system concentrating on two basic concepts: events and conditions. Most of the theoretical work on Petri nets is a formal definition of Petri nets structures, which consist of a set of places, representing conditions, a set of transitions, representing events, an input function and an output function. For practical purposes, a graphical representation is more useful. Two types of nodes portray places and transitions. A circle is a place and a bar is a transition. There is no inherent measure of time in a classical Petri net. To approach time-based evaluation of system performances, Timed Petri Nets (TPNs) were introduced. Modeling the notion of time is not straightforward. There are several possibilities for introducing time in PNs, among them timed transitions and timed places. This paper reviews several published examples where Petri Nets were used in different circumstances such as estimating expected utilization of processing resources at steady state in open queueing networks, verifying computerized simulations and batch planning in textile industry.

基于不完备信息系统规则提取和Petri Nets的电力变压器故障诊断

鉴于电力变压器故障信息具有不完备性及复杂性,将不完备信息系统规则的提取与Petri Nets(PNs)有机结合在一起进行变压器故障诊断。利用不完备信息规则提取对信息表进行知识的简化与故障特征的压缩,获得最小诊断规则,并利用此规则建造PNs的模型。同时利用PNs实现并行推理,对变压器进行快速分析。故障实例分析表明,文中所提出的智能方法具有准确性,有效性。

基于Time Petri Nets的实时系统资源冲突检测

Time Petri Nets在实时系统的建模和性能分析中得到广泛应用,而冲突是Petri网及其扩展模型的重要行为,解决冲突是正确分析模型动态行为的关键.目前随机Petri网、混合Petri网和区间速率连续Petri网的冲突检测方法由于没有考虑到时间约束因此无法在TPN网中使用.时间约束的引入使得Time Petri Nets模型的使能和触发语义比Petri网模型的语义复杂,冲突检测变得更加困难.为了计算冲突发生的时间和概率,首先根据时间约束,给出了变迁持续使能时延迟区间的计算方法,并证明了该方法的合理性和完备性;然后在此基础上定义并证明了Time Petri Nets模型中不冲突的检测方法;并提出了Time Petri Nets模型的冲突检测方法,给出了冲突时间区间和变迁实施概率的计算方法;最后通过实例验证说明了该方法的正确性和有效性.

An Attack Modeling Based on Colored Petri Net

A color petri net (CPN) based attack modeling approach is addressed. Compared with graph-based modeling, CPN based attack model is flexible enough to model Internet intrusions, because of their static and dynamic features. The processes and rules of building CPN based attack model from attack tree are also presented. In order to evaluate the risk of intrusion, some cost elements are added to CPN based attack modeling. This extended model is useful in intrusion detection and risk evaluation. Experiences show that it is easy to exploit CPN based attack modeling approach to provide the controlling functions, such as intrusion response and intrusion defense. A case study given in this paper shows that CPN based attack model has many unique characters which attack tree model hasn’t.

基于D-Petri Net和动态调度的网格工作流

提出了网格工作流体系结构;给出了基于DPetriNet的网格工作流建模语言和验证方法,利用该建模语言生成的过程模型适合网格资源动态性的特点;分析了根据网格性能动态产生并行任务和动态调度的算法;最后介绍了在Globus上实现的原型系统和在基因测序中的应用.该系统具有良好的效果.

基于Time Petri Net的实时系统冲撞检测与消解

time Petri net(TPN)在实时控制系统的建模中得到广泛应用,而冲撞是Petri网及其扩展模型的重要行为,解决冲撞是正确分析模型动态行为的关键.由于引入时间约束,使得TPN模型的使能和触发语义比Petri网模型的语义复杂,冲撞的检测及消解变得更加困难.首先根据时间约束,给出了变迁持续使能时延迟区间的计算方法,并证明了该方法的正确性;然后在此基础上定义并证明了TPN模型中冲撞的检测方法;给出了冲撞时间区间及修改时间约束的冲撞消解方法;最后通过实例验证说明了该方法的有效性和正确性.

基于Petri net的故障诊断理论研究

首先将故障概率的概念引入基于Petri net的故障诊断方法中,针对Place和Transition,提出了P概率和T概率的概念;然后给出了它们的定义和计算定理;最后,在P概率和T概率的基础上,对故障树分析(FTA)中"重要度"的概念略加调整,并将其引入所提出的故障诊断方法中,为Place和Transition定义了"重要度",同时给出了计算方法.

基于Petri net建模的资源调度的蚁群算法

利用了受控赋时Petri net建立了分布式系统中的资源调度的模型,并应用仿真器进行了仿真。由于在进行大规模的模型分析时,不适合采用仿真器来模拟,因而引进了蚁群算法来优化模型,可以得到较好的结果。

Petri Nets算法在电力系统恢复中的应用

通过对电力系统恢复的不同恢复策略、方法和恢复阶段的研究,发现恢复过程中存在一系列的“普遍恢复动作”,而将这一系列的普遍恢复动作组织起来即可形成恢复方案。提出应用PetriNets算法组织电力系统恢复过程中的普遍恢复动作。PetriNets算法对系统恢复时各电力元件状态和恢复操作进行建模,可以在时域上直接仿真系统恢复的全过程。该算法考虑了不同恢复阶段的目标、每个操作措施的估计时间和操作员的经验,具有灵活的冲突处理机制和并行处理特性,形成的恢复方案准确而直观。对给定的一个电网算例进行了仿真计算。

一种基于Petri net的分布式入侵容忍系统模型研究

入侵容忍是新兴的第三代网络安全技术。针对现有入侵容忍系统模型的不足,以Petri net为建模工具,提出了一种分布式入侵容忍系统的模型,给出了该模型的具体解释,并通过实例详细分析了模型的多个性能。分析结果表明,该模型能够扩展对现有入侵容忍系统的描述范围,同时也细化了对入侵容忍系统各个属性的描述。