A discrete event system (DES) is a dynamic system that evolves in accordance with the abrupt occurrence, at possibly unknown irregular INTERVALs, of physical events. Because of the special nature of these systems, different tools are currently used for their analysis, design and modeling. The main focus of this paper is the presentation of a new modeling approach of Discrete Event Systems. The proposed approach is based on hybrid model which combines INTERVAL Constrained PETRI NETS (ICPN) and Timed Automata. These tools allow us to evaluate, respectively, the quality variations and to manage the flow type disturbance. An example analysis illustrates our approach.

An urban traffic network is, in fact, a discrete event system in which traffic light is an efficient tool to control the flow of traffic. Proper timing of traffic lights can make a big impact on the flow of vehicles, the number of cars waiting behind the light, and on the citizen commuting time. In this paper, to achieve the timing of traffic lights, using colored PETRI NETS, a traffic model is built. The proposed model captures the control logic of traffic lights and flow of vehicles. Using computer simulation, different timing scenarios have been modeled and evaluated. Moreover, to demonstrate the application of the proposed model, an important intersection has been studied within the city of Bushehr. A suitable timing of traffic lights is determined based on simulation outputs. The proposed timing scenario was able to gain a great improvement on the intersection performance.

Secure Electronic Transaction (SET) protocol is an open protocol, which has the potential to emerge as a powerful tool in securing of electronic transactions. The quality of a design of an Ecommerce protocols has a great influence on achieving non-functional requirements (NFRs) to the system. An increasingly important non-functional attribute of complex software systems is adaptability. Software for adaptive software systems should be flexible enough to allow components to change their behaviors depending upon the environmental and stakeholders' changes and goals of the system. Evaluating adaptability at software to identify the weaknesses of the software and further to improve adaptability of their, are very important tasks. This paper presents a method based on the use of Colored PETRI NETS for evaluating Adaptability in SET protocol. We try to see how we can apply the way formalize CPN in terms of quality attributes to evaluate some of them, on the SET protocol.

Recently, numerous attempts have been made to obtain intelligent process planning systems and to increase the efficiency of computer aided process planning (CAPP) system using new mathematical methods. Graph theories, PETRI NETS, and fuzzy logic are powerful tools that are employed in this research to model different feasible states for performing a process and to obtain the best process performance path using exertion of the process designer's criteria. Then with the transformation of obtained model to machine language or other states which are capable for applying on tool machine controller can automatically do main pan of generation procedure and optimal path selection of process performance. The main idea of this research is the automation of assembly of industrial part using robots. In this paper it will be shown that several ideas and approaches which are proposed in the field of robotic assembly are applicable to the planning procedure modeling with minor modifications.

In highly competitive industrial market, the concept of failure analysis is an unavoidable fact in complex industrial systems. Reliability of such systems not only depends on the reliability of each element of these systems, but also depends on occurrence of sequence of failures. In this paper, a novel approach to sequential failure analysis is proposed which is based upon fuzzy logic and the concept of PETRI NETS which is utilized to track all the risky behaviors of the system and to determine the potential failure sequences and then prioritizing them in order to perform corrective actions. The process of prioritizing failure sequences in this paper is done by a novel similarity measure between generalized fuzzy numbers. The proposed methodology is demonstrated with an example of two automated machine tools and two input/output buffer stocks.