P — A logic — a compositional proof system for distributed programs

Summary This paper describes a compositional proof system called P-A logic for establishing weak total correctness and weak divergence correctness of CSP-like distributed programs with synchronous and asynchronous communication. Each process in a network is specified using logical assertions in terms of a presuppositionPre and an affirmationAff as a triple {Pre}S{Aff}. For purely sequential programs, these triples reduce to the familiar Hoare triples. In distributed programs, P-A triples allow the behaviour of a process to be specified in the context of assumptions about its communications with the other processes in the network. Safety properties of process communications, and progress properties such as finiteness and freedom from divergence can be proved. An extension of P-A logic allowing proof of deadlock freedom is outlined. Finally, proof rules for deriving some liveness properties of a program from its P-A logic specification are discussed; these properties have the form Q untilR, whereQ, R are assertions over communication traces. Other liveness properties may be derived from these properties using the rules of temporal logic. Paritosh Kulin Pandya received his Master's degree in Computer Science from the Indian Institute of Technology, Kanpur in 1982, and a Ph.D. from the Tata Institute of Fundamental Research in 1988 where he is currently employed. He has worked as a Research Officer in the Programming Research Group of the Oxford University from 1988 to 1991. Mathai Joseph has since 1985 been professor of Computer Science at the University of Warwick where he leads a group working on developing formal techniques for specifying and implementing realtime and fault-tolerant systems.Supported in part by Visiting Fellowships awarded by the Science and Engineering Research Council (research grant GR/D 90918) and the British Council     

Doping and Surface Modification Enhance the Applicability of Nanostructured Fullerene–MWCNT Hybrid Draped LiNi0.1Mg0.1Co0.8O2 as High Efficient Cathode Material for Lithium-Ion Batteries

Journal of Inorganic and Organometallic Polymers and Materials - Development of high performance cathode materials, layer-structured ternary LiNixCoyM1?x?yO2 cathode materials have...     

Strontuim titanate aided water splitting: An overview of current scenario

Addressing the ever-growing global energy demands and environmental concerns by switching over to sustainable and renewable energy resources have been the thrust area of research in the past few decades. Harnessing the abundant solar energy has been the most viable option in this regard. Perovskites, especially strontium titanate have been among the most explored photocatalytic catalytic systems due to their unique properties. The present review summarises the state of art in the solar assisted water splitting using strontium titanate as catalyst. Strategies adopted in enhancing the visible light sensitivity and performance has been discussed giving emphasis to the mechanistic pathway     

Dual-cavity spectrometer for monitoring broadband light extinction by atmospheric aerosols

Abstract

Atmospheric Aerosols affect Earth’s climate directly by scattering and absorbing solar radiation. In order to study the optical properties of aerosols, we developed a broadband cavity-enhanced spectrometer that uses a supercontinuum laser source and a compact spectrometer, to measure simultaneously the extinction coefficient of aerosols over a broad wavelength region from 420 to 540?nm. The system employs a dual cavity approach with a reference and a sample cavity, accounting for changes in gases background and for laser spectral and intensity fluctuations. We tested the system with aerosolized salt particles and polystyrene latex spheres. We performed calculations using Mie theory and found good agreement with the measured extinction. We also found that the extinction coefficient of non-absorbing aerosol favorably compares with the scattering coefficient measured by a nephelometer. Finally, we generated soot particles and found an extinction Ångström exponent in good agreement with values reported in the literature. Wavelength dependent detection limits (1σ) for the instrument at 5?nm wavelength resolution and for an integration time of ～10?min were found to be in the range ～5?Mm^?1 to 13?Mm^?1. The broadband dual-cavity extinction spectrometer is simple and robust and might be particularly useful for laboratory measurements of the extinction coefficient of brown carbon aerosol. The laboratory tests suggest that the prototype is promising for future developments of a field-deployable instrument.

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