PEDESTRIAN POTENTIAL RISK WHILE CROSSING AT SIGNALIZED INTERSECTIONS

SOME INSIGHTS ON ROADWAY INFRASTRUCTURE DESIGN FOR SAFE ELDERLY PEDESTRIAN TRAVEL

Petri Nets are tools for the modelling and analysis of the behaviour of systems and analysis of the Petri Net can then reveal important information about the structure and dynamic behaviour of the modelled system. In this article, the author argues that Petri Net concepts (when used qualitatively) are not fundamentally different from those of ANT. For example, the ‘places’ from Petri Nets bear a strong resemblance to the actors in ANT, and the ‘triggers’ or ‘transitions’, are somewhat analogous to ANT’s translations. In modelling, places represent conditions and transitions represent events. Tokens may model the resources or data items that are associated with a place or places. The original research that this article is based on was undertaken using an actor-network framework to develop a model for e-Learning for students with Learning Difficulties. This article explores the qualitative use of Petri Nets to supplement this ANT treatment.

Petri nets have proved their effectiveness in modeling and formal verification of a large number of applications: control systems, communication protocols, application workflows, hardware design, etc. In the present days, one important focus of computer science is on security and secure communications. The use of Petri nets for verifying security properties is not a mature field due to a lack of convenient modeling and verification capabilities. So far, in the Petri Net field there is only CPN Tools that is mature enough for modeling, using the colored Petri nets formalism. Nevertheless such verifications cannot be performed on large systems as CPN Tools is based on an exhaustive way of computing the semantics of a model. In this paper we present the use of AlPiNA, another candidate for this task. AlPiNA is a symbolic model checker that uses the formalism of algebraic Petri nets. We have used it successfully for modeling ad hoc networks and for verifying security protocols designed for this type of networks. As a case study and benchmark we have chosen the ARAN secure routing protocol. We managed to find all the attacks that were already reported for this protocol. To our knowledge this work is also the first successful attempt to use Petri nets for model checking the security properties of ad hoc networks protocols.

Petri Nets are tools for the modelling and analysis of the behaviour of systems and analysis of the Petri Net can then reveal important information about the structure and dynamic behaviour of the modelled system. In this article, the author argues that Petri Net concepts (when used qualitatively) are not fundamentally different from those of ANT. For example, the ‘places’ from Petri Nets bear a strong resemblance to the actors in ANT, and the ‘triggers’ or ‘transitions’, are somewhat analogous to ANT’s translations. In modelling, places represent conditions and transitions represent events. Tokens may model the resources or data items that are associated with a place or places. The original research that this article is based on was undertaken using an actor-network framework to develop a model for e-Learning for students with Learning Difficulties. This article explores the qualitative use of Petri Nets to supplement this ANT treatment.

The use of Petri nets for modelling, analysing and simulating complex distributed production systems meets serious problems when the size of the model grows. Therefore, it would be very useful to decompose a Petri net based model into smaller models linked with one another. The aim of this paper is to suggest and discuss some possible definitions of Modular Petri nets. This is accomplished by introducing the concept of Petri subnet. Two possible definitions are proposed and the meaning and the usefulness with respect to both model definition and model executability for simulation are pointed out. All definitions are given for the basic model of Petri nets. The extension of modularity concepts to high level Petri nets is shown to be possible in the second part of the paper, where an application is illustrated. In particular an algorithm is given which allows automatic composition of subnets into a larger model

The demand for energy is constantly growing: analysts forecast that it will increase by 50% by 2040. New deposits being discovered and the elaboration of new methods of hydrocarbons extraction will allow using these resources for a long time. Nevertheless, most countries have begun to think about using solar power. This interest is caused not only by environmental problems, but also by the fact that annually 178.000 TW of solar radiation reaches our planet. To use solar energy, two methods – thermal and photovoltaic – are used. The first one involves heating up used liquid, the second one implies the conversion of sunlight into electrical energy. Containers for storing fossil fuels are installed at oil terminals. This hydrocarbon can be crude or refined oil in a form of heavy (mazut) or light (diesel) fuel. Solar energy can be used at oil terminals both for heating hydrocarbons (in order to reduce viscosity to operating parameters), and for storing electrical power. The use of solar energy will improve energy efficiency and the environmental component of a terminal. The paper presents the functioning of an oil product heating system as a sequence of events based on cause-effect relations. For a formal description of the logical structure of processes of solar energy use, the authors proposed a solution using the Petri net machine. Prerequisites for the use of Petri nets are: the presence of random and deterministic components in the process of generation of solar energy; the possibility of representing the conversion of solar energy in the form of sets of technologically homogeneous parallel processes; situational control related to the randomness of the possibility of converting solar energy. With the help of the model and by using the Petri net, conflict situations were found that could be solved by situational control. As practice shows, such kind of local situations is solved within the framework of automated control.

Mapping patterns of pedestrian fatal accidents in Israel

Half a century after Carl Adam Petri’s Ph.D. thesis: A perspective on the field

Petri nets have proven to be a valuable tool for modelling concurrent systems. As such, they should be suitable for modelling agent and multi-agent systems, as these are inherently concurrent. Nevertheless, there are not many systems that allow modelling of the whole multi-agent system in Petri nets. The use of Petri nets is usually limited to sub-problems, such as verification of interaction protocols. This paper describes the main concepts of PNagent - a tool for modelling BDI agents using the formalism of object oriented Petri nets (OOPN). PNagent allows development, testing and running software agents in a consistent graphical environment. The framework is suitable for prototyping and experiments with both multi-agent applications and the particular agent architecture itself. At the same time, thanks to the formal nature of its underlying paradigm, it provides means for verification of agentpsilas properties.

Unmanned aerial vehicle safety assessment modelling through petri Nets

This paper presents a unified design environment of concurrent logic controllers, based on the use of Petri nets, rule-based description languages and PL4 specification languages (especially AMD Palasm 4). The straightforward templates are presented that made possible a rule-based Petri net specification to be simulated and then efficiently synthesised with modern programmable devices. Though the example presented in this paper is relatively trivial, the concepts are directly applicable in the more realistic designs.

Proposes the use of Petri nets during computer-aided design of microaccelerometers on the system level and presents an example of using Petri nets for inter-digital microaccelerometers.

Petri net-based modeling of a class of complex digital systems

In this paper we describe how the completion time distribution for short TCP connections can be computed using Deterministic Stochastic Petri Net (DSPN) models of TCP protocol. A DSPN model of TCP is a representation of the finite state machine description of the TCP transmitter behavior, and provides an accurate description of the TCP dynamics. The DSPN requires as input only the packet loss probability, and the average round trip time for the TCP connections being considered. The proposed model has been validated by comparing it against simulation results in various network scenarios, thus proving that the model is accurate. Numerical results are presented to prove the flexibility and the potentialities of the proposed methodology.KeywordsPerformance EvaluationCommunication Network PlanningTransport Control ProtocolDeterministic Stochastic Petri NetsCompletion Time Distribution

This paper presents an approach to systems analysis and design called the operations-oriented methodology (OOM). It was developed with the objectives of being comprehensive in terms of scale and detail, easy to understand by a nonexpert and capable of formal analysis. The methodology was tested at seven field sites. The paper describes the fundamentals of OOM, and more particularly focuses on its use of Petri nets and playscript formats, and how these enable us to satisfy our objectives. Limitations of the methodology and future research directions are also mentioned.