Communicating Processes with Data for Supervisory Coordination

We employ supervisory controllers to safely coordinate high-level discrete(-event) behavior of distributed components of complex systems. Supervisory controllers observe discrete-event system behavior, make a decision on allowed activities, and communicate the control signals to the involved parties. Models of the supervisory controllers can be automatically synthesized based on formal models of the system components and a formalization of the safe coordination (control) requirements. Based on the obtained models, code generation can be used to implement the supervisory controllers in software, on a PLC, or an embedded (micro)processor. In this article, we develop a process theory with data that supports a model-based systems engineering framework for supervisory coordination. We employ communication to distinguish between the different flows of information, i.e., observation and supervision, whereas we employ data to specify the coordination requirements more compactly, and to increase the expressivity of the framework. To illustrate the framework, we remodel an industrial case study involving coordination of maintenance procedures of a printing process of a high-tech Oce printer.Comment: In Proceedings FOCLASA 2012, arXiv:1208.432

Modelling Clock Synchronization in the Chess gMAC WSN Protocol

We present a detailled timed automata model of the clock synchronization algorithm that is currently being used in a wireless sensor network (WSN) that has been developed by the Dutch company Chess. Using the Uppaal model checker, we establish that in certain cases a static, fully synchronized network may eventually become unsynchronized if the current algorithm is used, even in a setting with infinitesimal clock drifts

A Process Algebra for Supervisory Coordination

A supervisory controller controls and coordinates the behavior of different components of a complex machine by observing their discrete behaviour. Supervisory control theory studies automated synthesis of controller models, known as supervisors, based on formal models of the machine components and a formalization of the requirements. Subsequently, code generation can be used to implement this supervisor in software, on a PLC, or embedded microprocessor. In this article, we take a closer look at the control loop that couples the supervisory controller and the machine. We model both event-based and state-based observations using process algebra and bisimulation-based semantics. The main application area of supervisory control that we consider is coordination, referred to as supervisory coordination, and we give an academic and an industrial example, discussing the process-theoretic concepts employed.Comment: In Proceedings PACO 2011, arXiv:1108.145

Reactions of (1,3,3-Trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl Chloride with Some S- and O-Nucleophiles

The sterically crowded 3,3-trichloro-2,2,4,4-tetramethylcyclobutanethione (2c) easily reacts with phosphorus pentachloride in CCl4 yielding the relatively stable (1,3,3-trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl chloride (3c). The reactions of 3c with benzylsulfane (4) and thiocamphor (5) occur with elimination of HCl leading to the unsymmetrical disulfanes 6 and 9. In the case of the sulfenates 10 and 12, which are formed as intermediates in the reactions of 3c with propargyl and allyl alcohol, respectively, the subsequent [2,3]-sigmatropic rearrangement yields the corresponding sulfoxides 11 and 13

Preparation And Characterization Of Polymer Supported Goethite Sorbent For Arsenate Removal

The aim of this work is to present a novel functionalized high surface area, macro porous material for selective removal of arsenic from water solution. A simple and room temperature reaction with controlled precipitation is applied in the process of iron (III)-oxide/poly (glicydil methacrylate-co-glycol dimethacrylate) amino modified sorbent material synthesis. Methods and processes for preparation of novel adsorbent were defined and obtained material was characterized by XRD, SEM and FTIR analysis

Li2(Se2O5)(H2O)1.5·CuCl2: a salt-inclusion diselenite structurally based on tetranuclear Li4 complexes

International audienceA new lithium copper diselenite chloride hydrate, Li 2 Se 2 O 5 (H 2 O) 1.5 ·CuCl 2 , was prepared from aqueous solution

Binary Permutation Polynomial Inversion and Application to Obfuscation Techniques

International audienceWhether it is for constant obfusation, opaque predicate or equation obfuscation, Mixed Boolean-Arithmetic (MBA) expressions are a powerful tool providing concrete ways to achieve obfuscation. Recent papers [22, 1] presented ways to mix such a tool with permutation polynomials modulo 2 n in order to make the obfuscation technique more resilient to SMT solvers. However, because of limitations regarding the inversion of such permutations, the set of permutation polynomials presented suffers some restrictions. Those restrictions allow several methods of arithmetic simplification, decreasing the effectiveness of the technique at hiding information. In this work, we present general methods for permutation polynomials inversion. These methods allow us to remove some of the restrictions presented in the literature, making simplification attacks less effective. We discuss complexity and limits of these methods, and conclude that not only current simplification attacks may not be as effective as we thought, but they are still many uses of polynomial permutations in obfuscation that are yet to be explored