D-finder 2: Towards efficient correctness of incremental design

D-Finder 2 is a new tool for deadlock detection in concurrent systems based on effective invariant computation to approximate the effects of interactions among modules. It is part of the BIP framework, which provides various tools centered on a component-based language for incremental design. The presented tool shares its theoretical roots with a previous implementation, but was completely rewritten to take advantage of a new version of BIP and various new results on the theory of invariant computation. The improvements are demonstrated by comparison with previous work and reports on new results on a practical case study. © 2011 Springer-Verlag

Unified knowledge model for stability analysis in cyber physical systems

The amalgamation and coordination between computational processes and physical components represent the very basis of cyber-physical systems. A diverse range of CPS challenges had been addressed through numerous workshops and conferences over the past decade. Finding a common semantic among these diverse components which promotes system synthesis, verification and monitoring is a significant challenge in the cyber-physical research domain. Computational correctness, network timing and frequency response are system aspects that conspire to impede design, verification and monitoring. The objective of cyber-physical research is to unify these diverse aspects by developing common semantics that span each aspect of a CPS. The work of this thesis revolves around the design of a typical smart grid-type system with three PV sources built with PSCADʼ. A major amount of effort in this thesis had been focused on studying the system behavior in terms of stability when subjected to load fluctuations from the PV side. The stability had been primarily reflected in the frequency of the generator of the system. The concept of droop control had been analyzed and the parameterization of the droop constant in the shape of an invariant forms an essential part of the thesis as it predicts system behavior and also guides the system within its stable restraints. As an extension of a relationship between stability and frequency, the present study goes one step ahead in describing the sojourn of the system from stability to instability by doing an analysis with the help of tools called Lyapunov-like functions. Lyapunov-like functions are, for switched systems, a class of functions that are used to measure the stability for non linear systems. The use of Lyapunov-like functions to judge the stability of this system had been tested and discussed in detail in this thesis and simulation results provided --Abstract, page iii