Verification of Complex Real-time Systems using Rewriting Logic

This paper presents a method for model checking dense complex real-time systems. This approach is implemented at the meta level of the Rewriting Logic system Maude. The dense complex real-time system is specified using a syntax which has the semantics of timed automata and the property is specified with the temporal logic TLTL (Timed LTL). The well known timed automata model checkers Kronos and Uppaal only support TCTL model checking (a very limited fragment in the case of Uppaal). Specification of the TLTL property is reduced to LTL and its temporal constraints are captured in a new timed automaton. This timed automaton will be composed with the original timed automaton representing the semantics of the complex real-time system under analysis. Then, the product timed automaton will be abstracted using partition refinement of state space based on strong bi-simulation. The result is an untimed automaton modulo the TLTL property which represents an equivalent finite state system to be model checked using Maude LTL model checking. This approach is successfully tested on industrial designs

Generating Diagnoses for Probabilistic Model Checking Using Causality

One of the most major advantages of Model checking over other formal methods of verification, its ability to generate an error trace in case of a specification falsified in the model. We call this trace a counterexample. However, understanding the counterexample is not that easy task, because model checker generates usually multiple counterexamples of long length, what makes the analysis of counterexample time-consuming as well as costly task. Therefore, counterexamples should be small and as indicative as possible to be understood. In probabilistic model checking (PMC) counterexample generation has a quantitative aspect.  The counterexample in PMC is a set of paths in which a path formula holds, and their accumulative probability mass violates the probability bound. In this paper, we address the complementary task of counterexample generation which is the counterexample diagnosis in PMC. We propose an aided-diagnostic method for probabilistic counterexamples based on the notion of causality and responsibility. Given a counterexample for a Probabilistic CTL (PCTL) formula that doesn’t hold over Discreet-Time-Markov-Chain (DTMC) model, this method guides the user to the most responsible causes in the counterexample.</p

Decision Support Technique for Supply Chain Management

In this paper, we propose a method for supporting decision makers in the domain of supply chain management. Our objective is the global optimization instead of optimizing independent subsystems of the supply chain. The method architecture is based on combination of the simulation and optimization techniques which includes a multi-objectives optimization module and a simulation module. The optimization module is based on genetic algorithms and the simulation module uses effective alternative designs proposed by strategic and tactic decisions to find global optimal solution using the optimal scheduling solution proposed by the genetic algorithm for operational decisions. The experimental results show the efficiency and the feasibility of the proposed approach

Performance evaluation of masonry Infilled RC frame structures under lateral loads

Brojne studije o zidanim ispunskim panelima uvelike su doprinijele razvoju istraživanja nosivosti, krutosti i sposobnosti disipacije energije raznih građevina. Zanemarivanje utjecaja zidanih ispuna može uzrokovati oštećenosti konstrukcije u slučaju značajnijih pomaka tla, pa čak i do rušenja čitave građevine. Način sloma uvelike ovisi o međusobnom djelovanju zidane ispune i AB okvira. U ovom se radu predlaže metoda za ocjenjivanje koeficijenta učinkovitosti zidane ispune na AB okvirne konstrukcije pod utjecajem bočnih opterećenja.Numerous studies on masonry infill panels have greatly contributed to the research of strength, stiffness and energy dissipation capacity of various buildings. If the effects of masonry panels are disregarded, structural damage will occur under any significant ground motion, and even lead to collapse of the entire structure. The mode of failure is strongly dependent on the masonry and RC frame interaction. This work proposes an evaluation method for determining the participation ratio of masonry infill panels on RC frames under lateral loads

Verification of Real-time Systems by Abstraction of Time Constraints

This paper presents a new methodology for model checking real-time systems based on the abstraction of time predicates. A real-time system is modeled with a timed automaton which is translated to a real-time program. The properties are specified with the temporal logic TCTL (Timed Computational Tree Logic). The real-time program and the TCTL property are used first, for producing a new automaton which augments the original with auxiliary clocks capturing the timing constraints in the TCTL specification that is reduced to an equivalent CTL specification. Second, the augmented real-time program is converted to a well timed system by removing the zeno runs (that are executions in which time does not diverge). Then the time predicates in the augmented automaton which is represented by an augmented and no-zeno real-time program will be abstracted to generate an untimed automaton representing an equivalent finite state system to be model checked using existing tools