Extending Petri net to reduce control strategies of railway interlocking system

In our previous articles we gave step by step refinement process towards the development of safety properties of moving block interlocking system (MBRIS). The refinement process started from abstraction to fuzzy based safety properties using Z and then fuzzy multi agent specification language. However, one dimensional control of train passing through a switch and level crossing were not discussed. This paper reduces the existing two dimensional controls along the switch and level crossing to one dimensional for shifting it to a train only. For example, in the existing model the train movement along components switches and level crossings depends on both the train and components control. Whereas, in one dimensional control train is the only authority to control a switch and level crossing required for its desired operation. For this reduction, concurrent and mobile agent concepts are required. Therefore, we integrate mobile agent concepts with Petri nets to develop the mobile Petri net (MPN) a new class of PNs. This supports both mobility and concurrency. Further, we prove that the collection of different MPNs in a connected network is a PN. This proof allowed us to use the properties of PN to verify the system. Finally, we use MPN to model the safety properties of MBRIS along the switch and level crossing. This provides one dimensional control to a train along a switch and level crossing which increases the safety of the railway interlocking system. Moreover, we use reachability graph (RG) to verify the switch and level crossing models.     

装备战场抢修的模糊随机Petri网建模和分析

针对装备的战场抢修要求恢复状态可以具有多样性的特点,对原有模型进行了改进,提出了模糊随机Petri网模型,并且验证了模型实用性和有效性.     

A Petri net approach to the modelling and analysis of flexible manufacturing systems

In this paper we present an approach for modelling and analyzing flexible manufacturing systems (FMSs) using Petri nets. In this approach, we first build a Petri net model (PNM) of the given FMS in a bottom-up fashion and then analyze important qualitative aspects of FMS behaviour such as existence/absence of deadlocks and buffer overflows. The basis for our approach is a theorem we state and prove for computing the invariants of the union of a finite number of Petri nets when the invariants of the individual nets are known. We illustrate our approach using two typical manufacturing systems: an automated transfer line and a simple FMS.A shorter version of this paper was presented at the 1st ORSA/TIMS Special Interest Conference on FMSs, University of Michigan, Ann Arbor, August 1984.     

Selection of parameters for a fuzzy logic controller

The fuzzy logic controller is reviewed and its parameter are explicitly identified. The problem of initial selection and subsequent adjustment of the parameters are discussed in detail by example.     

Supervisory controller design to enforce some basic properties in timed-transition Petri nets using stretching

Supervisory controller design to enforce boundedness, reversibility, and liveness in timed-transition Petri nets with firing durations is considered. It is assumed that both controllable and uncontrollable transitions may be present and more than one transition may fire simultaneously. The approach of stretching is used to represent the state of the system. Algorithms are presented to design a supervisory controller using the forbidden states approach to enforce boundedness and reversibility simultaneously. The designed controller also guarantees T-liveness for the largest possible subset T of the set of transitions. In particular, boundedness, reversibility, and liveness are simultaneously enforced whenever it is possible. The designed controller is also the least restrictive controller which enforces boundedness and reversibility simultaneously.     

模糊拓扑空间的m—收敛理论

本文在模糊拓扑空间中引进了模糊网和模糊滤子的ｍ－收敛概念，探讨了模糊网的ｍ－收敛与模糊滤子的ｍ－收敛之间的关系，得到了Ｈａｕｓｄｏｒｆｆ拓扑与模糊网的ｍ－收敛和模糊滤子的ｍ－收敛之间的关系以及刻画Ｈａｕｓｄｏｒｆｆ拓扑几何特征的定理。     

Modeling the process of human body iron homeostasis using a variant of timed Petri nets

The body iron homeostasis is one of the most important processes in the human body. This complex process is not fully understood and until recently only some parts of it have been described in the literature. In our recent papers the main part of the process has been described and a model based on Petri net theory has been proposed. However, in this model any time dependencies occurring in the biochemical process have not been taken into account. In the present paper the model is enriched in the way that durations of biochemical reactions composing this process have been included into the model. A variant of Petri net where with each place a time interval is associated has been used in order to describe these dependencies. The time interval associated with a place corresponds to a time lag of biochemical conditions which must be fulfilled in order to enable a biochemical reaction to start.     

Fuzzy controller of the air system of a diesel engine: Real-time simulation

In this paper a fuzzy controller is proposed to regulate the intake manifold pressure and the fresh mass airflow of diesel engines simultaneously. The instrumentation set usually embedded in a mass-produced passenger car has been considered. Unlike many multi-variable controllers, the proposed structure requires neither an internal model nor identification algorithms. In comparison to controllers embedded at present in standard engine control units (ECUs), it improves the trajectory tracking of desired outputs during simulation of EURO cycles. Because of its performance, the fuzzy controller has been implemented in an electronics control unit. Some real-time results are presented.     

区间值模糊集之间一种新距离的完备性

定义区间值模糊集之间的一种新距离d*∞,讨论了这种距离的基本性质,并证明区间值模糊数的距离空间(IΦ*(R),d*∞)是完备的,但它却是不可分的。     

赋模糊权的拟强连通有向网络中的最佳树形图

本文在赋模糊数为弧权的拟强连通有向网络中，建立了根据模糊决策来求解最佳树形图的网络模型，并给出了这一模型的有效算法。     

Specification and verification of safety properties along a crossing region in a railway network control

Modeling the controller of the railway network, having resource sharing based on mutual exclusion constraints, is an important problem. This paper firstly addresses the specification of safety properties for the model of a complex railway crossing. The operations, i.e., occupied, free and block, are formalized to describe the safety properties along railway crossing. Second, to develop the control model of the crossing system we construct the subnet representing the train flow along the tracks in the crossing region and the set of monitors or supervisors are also modeled as subnets. Arc-constant colored Petri net (ac-CPN) is used to construct the train flow subnet while the monitors are modeled using the place/transition-net. Arc-constant colored Petri net enforces the specification of not to shift the train from a track to another one. Bottom-up approach is adopted to model the control for railway crossing as a synchronous synthesis of the subnets is applied to build the final model. Finally, to verify the safety properties in the developed controller, the coverability tree method is used for the analysis of the final model.     

R0-代数(NM-代数)的模糊MP-滤子格

在R0-代数中,从模糊集出发构造了模糊MP-滤子,作为应用证明了如下结果:R0-代数的所有模糊MP-滤子构成一个完备模格。     

ETSK模糊模型辨识及模糊控制算法

本文提出一种基于扩张原理的ＥＴＳＫ（ＥｘｔｅｎｄｅｄＴＳＫ）模型,导出了该模型的输入输出解析式,给出了辨识这种模型的方法。本文还导出了ＥＴＳＫ模型的一种等价形式——变权ＴＳＫ模型,从而将ＥＴＳＫ模型规则后件中的模糊数及其扩展运算转化为普通数的运算,使基于ＥＴＳＫ模型的模糊控制算法ＭＢＦＣ（Ｍｏｄｅｌ－ＢａｓｅｄＦｕｚｚｙＣｏｎｔｒｏｌ）易于实现。仿真辨识结果表明,ＥＴＳＫ模型的辨识效果和预报精度优于ＴＳＫ和ＬＭ模型;ＭＢＦＣ算法的控制效果优于通常模型ＰＩ控制算法     

新序结构下函数列的伪依集值模糊测度收敛

在m维正欧氏空间中引入一种新序结构,并由此序结构在集值模糊测度空间上给出可测函数序列伪依集值模糊测度收敛、(伪)依集值模糊测度几乎处处收敛、PS性和PS'性等概念,进而研究了伪依模糊测度收敛和(伪)几乎处处收敛之间的关系,获得相应的Lebesgue定理和Riesz定理.     

模糊推理三I算法的逻辑基础

在模糊推理理论中，近期问世的三I推理方法以逻辑蕴涵运算取代传统的合成运算，从根本上改进了传统的合成推理规则(即CRI方法)。本文基于模糊命题逻辑的形式演绎系统L^*和模糊谓词逻辑的一阶系统K^*，构建了一个完备的多型变元一阶系统Kms^*，并且将三I算法完全纳入了模糊逻辑的框架之中，从而为模糊推理奠定了严格的逻辑基础。     

h-准正则半环的广义直觉模糊理想刻画

介绍了h-准正则半环的概念,对其主要性质进行了探讨,并利用半环上有边界值的直觉模糊h-理想和直觉模糊双理想,得到了h-准正则半环的若干刻画定理.     

模糊测度在山区开挖岩体移动分析中的应用

将山区地下开挖所引起的上覆岩土体的移动视为一模糊事件,应用模糊数学中的模糊测度理论,推导了相应的地表下沉及水平移动的理论计算公式,对煤矿开采所引起的地表移动进行了计算分析。通过工程实例计算分析表明,理论计算结果与工程实测资料吻合的很好。     

模糊综合评判在哈萨克文点阵库中的应用

哈萨克文的每个字母分四种字体，用于句子的不同位置，当用计算机处理哈文信息时，每个字母间靠近程度是模糊的。本文提出一种用模糊综合评判法来评价字库，且提出改进方案的方法。     

模糊技术在可靠性工程中的应用

本文主要介绍模糊集合理论和技术在可靠性工程中的应用现状及其发展趋势，尤其是在系统故障诊断，故障树分析（ＦＴＡ）系统可靠性分配，人的可靠性，软件可靠性，结构可靠性以及系统安全性工程中的应用和技术关键，并从工程应用的需要出发针对存在问题预测和提出各种解决途径。     

模糊条件下的决策单元相对有效性评价

研究了模糊条件下决策单元的相对有效性评价问题。首先分析了模糊性因素对决策单元相对有效性的影响;然后根据模糊规划取截集方法和DEA评价的经济含义,给出了模糊DEA模型的求解方法;最后定义了决策单元的模糊DEA有效性以及进行有效性排序的平均置信有效性。文末是一个模糊DEA应用的例子。