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A marked graph-based control synthesis method is proposed for discrete event systems. The proposed approach solves the forbidden state problems characterized by a set of General Mutual Exclusion Constraints (GMEC) and takes into account unobservable transitions. It exploits the structural dependence of places involved in GMEC constraints. For each case, analytical expression of the GMEC in its worst case, in terms of reachable marking, is given according to the observable firing sequence of the system. These constraints are then evaluated on-line by the supervisor. The proposed approach is illustrated on a real example. [ABSTRACT FROM AUTHOR]

The shapes of the CH-CH and CH-CH binary phase diagrams were analyzed. In the CH-CH binary system the increased stability of the binary compounds with increasing temperature can be explained by the much larger heat capacity and entropy of the binary compounds compared to that of the components CH and CH. In the CH-CH system this effect is much less pronounced. The measured enthalpy data of n-alkanes CH to CH and of the binary system CH-CH were analyzed to obtain the 'excess' heat capacity per atom of carbon {[ C/( Rm)]-3} ( Rm being the number of carbon atoms). The 'excess' heat capacity per carbon atom is the value of the heat capacity above the Debye high temperature value of 3R. At low temperatures (below 280 K) one is in the Debye temperature θ region. At higher temperatures the large 'excess' heat capacity of the solids explains the movements in the carbon chains. In the liquid the excess heat capacity is small and corresponds numerically to the anharmonic vibrations in low melting metals. In contrast to metals, where the difference in heat capacity between liquid and solid below the melting point is positive C( L-s)>0, in the alkanes studied it is strongly negative C( L-s)≪0. This explains the shape of the binary phase diagrams CH-CH, CH-CH, CH-CH and CH-CH. [ABSTRACT FROM AUTHOR]

Differential enthalpy analyses were performed on the binary n-alkane system n-C24H50- n-C26H54 with a Setaram DSC111 calorimeter of Tian Calvet type. The measurements provided enthalpy data from 260 to 260 K on n-tetracosane, n-hexacosane and 19 binary mixtures. An analytical expression, derived from the Einstein model, is proposed for every pure phase in its temperature domain, to represent the variation in the enthalpy with temperature. A general expression for the enthalpy as a function of temperature and composition is also given. [ABSTRACT FROM AUTHOR]