Graph transformation for verification and concurrency

The talk will begin with a brief introduction to Rewriting Logic and use of the Maude language. A case study based on modeling security aspects a remote service toolkit will be used to illustrate the approach to formal modeling and analysis in more detail

The ss-semantics approach; theory and applications

AbstractThis paper is a general overview of an approach to the semantics of logic programs whose aim is to find notions of models which really capture the operational semantics, and are, therefore, useful for defining program equivalences and for semantics-based program analysis. The approach leads to the introduction of extended interpretations which are more expressive than Herbrand interpretations. The semantics in terms of extended interpretations can be obtained as a result of both an operational (top-down) and a fixpoint (bottom-up) construction. It can also be characterized from the model-theoretic viewpoint, by defining a set of extended models which contains standard Herbrand models. We discuss the original construction modeling computed answer substitutions, its compositional version, and various semantics modeling more concrete observables. We then show how the approach can be applied to several extensions of positive logic programs. We finally consider some applications, mainly in the area of semantics-based program transformation and analysis

A PVS-Simulink Integrated Environment for Model-Based Analysis of Cyber-Physical Systems

This paper presents a methodology, with supporting tool, for formal modeling and analysis of software components in cyber-physical systems. Using our approach, developers can integrate a simulation of logic-based specifications of software components and Simulink models of continuous processes. The integrated simulation is useful to validate the characteristics of discrete system components early in the development process. The same logic-based specifications can also be formally verified using the Prototype Verification System (PVS), to gain additional confidence that the software design complies with specific safety requirements. Modeling patterns are defined for generating the logic-based specifications from the more familiar automata-based formalism. The ultimate aim of this work is to facilitate the introduction of formal verification technologies in the software development process of cyber-physical systems, which typically requires the integrated use of different formalisms and tools. A case study from the medical domain is used to illustrate the approach. A PVS model of a pacemaker is interfaced with a Simulink model of the human heart. The overall cyber-physical system is co-simulated to validate design requirements through exploration of relevant test scenarios. Formal verification with the PVS theorem prover is demonstrated for the pacemaker model for specific safety aspects of the pacemaker design

Process-Based Design and Integration of Wireless Sensor Network Applications

Abstract Wireless Sensor and Actuator Networks (WSNs) are distributed sensor and actuator networks that monitor and control real-world phenomena, enabling the integration of the physical with the virtual world. They are used in domains like building automation, control systems, remote healthcare, etc., which are all highly process-driven. Today, tools and insights of Business Process Modeling (BPM) are not used to model WSN logic, as BPM focuses mostly on the coordination of people and IT systems and neglects the integration of embedded IT. WSN development still requires significant special-purpose, low-level, and manual coding of process logic. By exploiting similarities between WSN applications and business processes, this work aims to create a holistic system enabling the modeling and execution of executable processes that integrate, coordinate, and control WSNs. Concretely, we present a WSNspecific extension for Business Process Modeling Notation (BPMN) and a compiler that transforms the extended BPMN models into WSN-specific code to distribute process execution over both a WSN and a standard business process engine. The developed tool-chain allows modeling of an independent control loop for the WSN.

Experimental and simulation study on the effect of geometrical and flow parameters for combined-hole film cooling

Film cooling method was applied to the turbine blades to provide thermal protection from high turbine inlet temperatures in modern gas turbines. Recent literature discovers that combining two cylindrical holes of film cooling is one of the ways to further enhance the film cooling performances. In the present study, a batch of simulations and experiments involving two cylindrical holes with opposite compound angle were carried out and this two cylindrical hole also known as combined-hole film cooling. The main objective of this study is to determine the influence of different blowing ratio, M with a combination of different lateral distance between cooling holes (PoD), a streamwise distance between cooling holes (LoD) and compound angle of cooling hole (1/2) on the film cooling performance. The simulation of the present study had been carried out by using Computational Fluid Dynamic (CFD) with application of Shear Stress Transport (SST) turbulence model analysis from ANSYS CFX. Meanwhile, the experimental approach makes used of open end wind tunnel and the temperature distributions were measured by using infrared thermography camera. The purpose of the experimental approach in the present study is to validate three cases from all cases considered in the simulation approach. As the results shown, the lateral coverage was observed to be increased as PoD and 1/2 increased due to the interaction between two cooling air ejected from both cooling holes. Meanwhile, film cooling performance insignificantly changed when different LoD was applied. As the conclusion, a combination of the different geometrical parameters with various flow parameters produced a pattern of results. Therefore, the best configuration has been determined based on the average area of film cooling effectiveness. For M = 0.5, PoD = 1.0, LoD = 2.5 and 1 / 2 = -45o /+45o case is the most effective configuration. In the case of M = 1.0 and M = 1.5, PoD = 0.0, LoD = 3.5, 1 / 2 = -45o /+45o and PoD = 0.0, LoD = 2.5, 1 / 2 = -45o /+30o are the best configurations based on the overall performance of film cooling