Petri net modeling and performance analysis of can fieldbus

The CAN FB (Controller Area Network FieldBus) has been in existence for ten years. It supports automated manufacturing and process control environments to interconnect intelligent devices such as valves, sensors, and actuators. CAN FieldBus has a high bit rate and the ability to detect errors. It is immune to noise and resistant to shock, vibration, and heat. Two recently introduced mechanisms, Distributed Priority Queue (DPQ) and Priority Promotion (PP) enable CAN FieldBus networks to share out the system bandwidth and grant ail upper bound on the transmission times so as to meet the requirements in real-time communications. Modeling and analysis of such networks are an important research area for their wide applications in manufacturing automation. This thesis presents a Petri net methodology which models and analyzes CAN FieldBus access protocol. A Reachability Graph of the Petri net model is -utilized to study the behavioral properties of the protocol. A timed Petri net simulator is used to evaluate the performance of the protocol. Performance measures include the completion time for successful events and operations. Operational parameters investigated using the Petri Net model are FieldBus speed, the length of each frame, and the number of frames in a message

Using the floor control mechanism in distributed multimedia presentation system

[[abstract]]Establishing a Web-based distributed multimedia presentation system environment is technical challenge. In this paper, we describe how to present different multimedia objects indispensably on a Web presentation system with a floor control mechanism, to be used in a distance learning environment. The distributed approach is based on an extended timed Petri net model. Using the characterization of extended timed Petri nets, we express the temporal behavior of multimedia objects. Then we introduce the concepts of user interaction. The main goal of our system is to provide a feasible method to represent a schedule and navigate different multimedia objects with user interaction. In addition, users can dynamically modify and verify different kinds of conditions during the presentation. To verify the structural mechanism, we implement an algorithm using the Petri net diagram, analyzing the model by a time schedule of multimedia objects, and we produce a synchronous set of multimedia objects with respect to the time duration. In particular, we consider the interactive facilities needed to support the distance learning requirements. We propose a floor control mechanism which provides four types of control (free access, equal control, group discussion and direct contact). These control mechanisms are sufficient for use in a distance learning environment[[notice]]補正完畢[[conferencetype]]國際[[conferencedate]]20010416~20010416[[conferencelocation]]Mesa, United State

A Distributed Multimedia Presentation System with Floor Control Mode Based on Extended Timed Petri Nets

[[abstract]]Communication over Internet is growing increasingly and will have profound implications for our economy, culture, society and education. Currently, multimedia presentation technologies among the network are most often use in many communication services. Examples of those applications include video-on demand, interactive TV and the communication tools on a distance learning system and so on. In this paper, we describe how to present different multimedia objects on a web presentation system with floor control mechanism as a result of the distance learning environment indispensably. The distributed approach is based on an extended timed Petri net model. Using characterization of extended time Petri net, we express the temporal behavior of multimedia objects; on the other hand, we introduce the concepts of user interaction. The main goal of our system is to provide a feasible method to represent a schedule and navigation of different multimedia objects with user interaction. In addition, users can dynamically modify and verify different kinds of conditions during the presentation. To verify the structural mechanism, we implement an algorithm using the Petri net diagram, analyzing the model by timeschedule of multimedia objects, and produce a synchronous set of multimedia objects with respect to time duration. Specially, we consider the interactive facilities to support the distance learning requirement. We propose a floor control mechanism, which provides four types of control (free access, equal control, group discussion, and direct contact). These control mechanisms are sufficient to the use of distance learning environment.[[sponsorship]]Ministry of Education,Republic of China; National Science Council,Republic of China; The Computer Society of the Republic of China[[notice]]補正完畢[[conferencetype]]國際[[conferencedate]]20001206~20001208[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]嘉義縣, 臺

Modeling interactive memex-like applications based on self-modifiable petri nets

This paper introduces an interactive Memex-like application using a self-modifiable Petri Net model – Self-modifiable Color Petri Net (SCPN). The Memex (“memory extender”) device proposed by Vannevar Bush in 1945 focused on the problems of “locating relevant information in the published records and recording how that information is intellectually connected.” The important features of Memex include associative indexing and retrieval. In this paper, the self-modifiable functions of SCPN are used to achieve trail recording and retrieval. A place in SCPN represents a website and an arc indicates the trail direction. Each time when a new website is visited, a place corresponding to this website will be added. After a trail is built, users can use it to retrieve the websites they have visited. Besides, useful user interactions are supported by SCPN to achieve Memex functions. The types of user interactions include: forward, backward, history, search, etc. A simulator has been built to demonstrate that the SCPN model can realize Memex functions. Petri net instances can be designed to model trail record, back, and forward operations using this simulator. Furthermore, a client-server based application system has been built. Using this system, a user can surf online and record his surfing history on the server according to different topics and share them with other users

Analyzing safety and fault tolerance using time Petri nets

The application of time Petri net modelling and analysis techniques to safety-critical real-time systems is explored and procedures described which allow analysis of safety, recoverability, and fault tolerance. These procedures can be used to help determine software requirements, to guide the use of fault detection and recovery procedures, to determine conditions which require immediate miti gating action to prevent accidents, etc. Thus it is possible to establish important properties duing the synthesis of the system and software design instead of using guesswork and costly a posteriori analysis