Modeling Cyber Physical Systems: A case study of Floodgate management system using Hybrid automata and State space analysis

This thesis seeks methods for modelling cyber physical systems (CPSs) and the related issues. They enable innovation in a wide range of domains including robotics, smart homes, vehicles, and buildings, medical implants, and future-generation sensor networks. Advances in CPS will enable capability, adaptability, scalability, resiliency, safety, security, and usability that will far exceed the simple embedded systems of today. In this thesis two methods are used to model and analyze the flood gate management system (FMS). Specific technologies described include hybrid automata and State space analysis, the use of domain-specific ontologies to enhance modularity, and the joint modelling of functionality and implementation

Module-based architecture for a periodic job-shop scheduling problem

AbstractThis paper addresses the Petri net (PN) based design and modeling approach for a periodic job-shop scheduling problem. Asynchronous synthesis for net-modules of the jobs is suggested in this paper for optimal allocation of shared resources to different operations. To make sure the completion of all the jobs in a single iteration of a production cycle and the correct calculation of a makespan, the synchronization problem among jobs is tackled by introducing the special synchronizing transition in the model. A timed-place PN is adopted for the purpose of finding the feasible schedule in terms of the firing sequence of the transitions of the PN model by using the heuristic search method. Further, the characterization of the PN model is performed and it is shown that the PN model for a periodic job-shop scheduling problem is equivalent to a class of PN known as parallel process net with resources (PPNRs). The modeling approach is demonstrated with a practical example and a makespan is calculated for the example

Qualitative and quantitative evaluation of stochastic Time Petri Nets

Time Petri Nets (TPN) are a well-known formalism for modelling time-dependent systems with timing constraints. This paper proposes an approach based on a stochastic extension of TPN (sTPN), which enables both qualitative assessment of feasible temporal behaviors through model checking, and quantitative evaluation of a probability measure of a given behavior, by statistical model checking. The experimental work rests on the use of the latest version of the UPPAAL toolbox which supports both exhaustive non deterministic analysis and statistical model checking of system properties. The approach is demonstrated through an example

Improving the construction of the DBM over approximation of the state spce of real-time preemptive systems

We present in this paper an algorithm allowing an efficient computation of the tightest DBM over-approximation of the state space of preemptive systems modeled by using Time Petri Nets with inhibitor arcs. First of all, we propose an algorithm that reduces the effort of computing the tightest DBM over-approximated graph. For this effect, each class of this graph is expressed as a pair (M, D), where M is a marking and D is the system of all DBM inequalities even the redundant ones. We thereby make it possible to compute the system D straightforwardly in its normal form, without requiring to compute the intermediary polyhedra. Hence, we succeed to remove the errors reported in the implementation of other DBM approximations. Then we show that by relaxing a bit in the precision of the DBM approximation, we can achieve to construct more compact graphs while reducing still more the cost of their computation. We provide for this abstraction a suitable equivalence relation that contract yet more the graphs. The experimental results comparing the defined constructions with other approaches are reported

Timed State Space Analysis of Real Time Preemptive Systems

A modeling notation is introduced which extends Time Petri Nets with an additional mechanism of resource assignment which makes the progress of timed transitions be dependent on the availability of a set of preemptable resources. The resulting notation, which we call Preemptive Time Petri Nets, permits natural description of complex real time systems running under preemptive scheduling, with periodic, sporadic and one-shot processes, with nondeterministic execution times, with semaphore synchronizations and precedence relations deriving from internal task sequentialization and from interprocess communication, running on multiple processors