Automating the refinement of specifications for distributed systems via syntactic transformations

The idea of successively refining an abstract specification until it contains enough detail to suggest an implementation has been investigated by numerous researchers. The emphasis to date has been on techniques that, unfortunately, lead to a large amount of manual formal labour for each refinement step. With such techniques, both the cost and the possibility of errors arising informal manipulation are high. Using a theorem prover can reduce the number of manipulation errors, but, given current technology, the amount of labour is still daunting. This research explores an alternative solution to the refinement problem, namely the use of syntactic transformations to realize each refinement step. We reduce formal labour by employing automatic transformations that guarantee the preservation of desirable properties—e.g., deadlock-freedom. Automatic transformations are particularly appealing for the development of large, complex distributed systems, where a manual approach to refinement would be prohibitively expensive. Distributed computations are, by nature, reactive and concurrent, so their correctness cannot be specified as a simple functional relationship between inputs and outputs. Instead, specifications must describe the time-varying behaviour of the system. Further difficulty is caused by the fact that such important characteristics of distributed systems as deadlock-freedom are global properties that cannot be achieved through considering local structures only. Transformations generally must encompass the entire system. This paper presents two syntactic transformations—the left-sequence introduction and the right-sequence introduction—and demonstrates that they preserve deadlock-freedom.     

Relative reflectance data from preprocessed multispectral photography

Abstract

Photographic image tone is an indicator of surface reflectance. If adequately preprocessed, photographic image tone can be used to provide a quantitative measureof relative surface reflectance,essential for many remotesensingapplications. The three preprocessing steps proposed are, first the standardization of the film data to a gamma of 1, second scene to scene ratioing, and third band to band ratioing. This methodology is reviewed and an example of its application provided in the preprocessing of a large multispectral photographic data set.     

A comparison between two photographic methods for the determination of relative bidirectional reflectance

Two simple photographic methods have recently been proposed for the measurement of relative bidirectional reflectance (Lillesand and Kiefer 1979, Curran 1980). These two methods were used to calculate the relative bidirectional reflectance of ten contrasting surfaces. The photographic relative bidirectional reflectance so recorded, was then compared with the radiometric bidirectional reflectance for each surface. Two conclusions were drawn: first, that relative bidirectional reflectance can be measured using these simple photographic techniques, and second, that there was no significant difference between the Lillesand and Kiefer and Curran methods for photographically deriving relative bidirectional reflectance.     

Enhanced thermal conductivity of nano-SiC dispersed water based nanofluid

Silicon carbide (SiC) nanoparticle dispersed water based nanofluids were prepared using up to 0·1?vol% of nanoparticles. Use of suitable stirring routine ensured uniformity and stability of dispersion. Thermal conductivity ratio of nanofluid measured using transient hot wire device shows a significant increase of up to 12% with only 0·1?vol% nanoparticles and inverse dependence of conductivity on particle size. Use of ceramic nanoparticles appears more appropriate to ensure stability of dispersion in nanofluid in closed loop single-phase heat transfer applications.     

Review Article Remote sensing methodologies and geography

Abstract

Remote sensing is a technique used in scientific and technological approaches to geographical research. In the scientific approaches (of which the empirical are the most popular) the motivation is curiosity, the goal is knowledge and the methodology is often induction to derive theory and then deduction to verify theory. In the technological approaches the motivation is human need, the goal is the application of knowledge and the methodology is design. This review discusses both approaches, concentrating on the problems of taking a scientific approach and the unwillingness of geographers to accept an often more suitable technological approach. It is argued throughout that both types of approach can be valid, both can be useful and both are suitable methodologies for remote sensing in geography.     

A quantitative analysis of pattern production and its relationship to expert performance

Abstract. The modelling and measurement of expertise is a relatively new research area in artificial intelligence and cognitive science. Many domains do not have a formal method for evaluating expertise. When formal methods exist, they are frequently inefficient. Using an extension to the IAM program, a pattern recognition and acquisition method for evaluating the level of expertise for the domain of chess is developed. Chess players, as well as experts in other domains, use cognitive chunks of perceptual patterns to gain a cognitive economy that enables them to evaluate complex domain situations faster and more accurately than novices. The IAM program acquires a representative collection of the perceptual patterns demonstrated by a domain expert and uses those patterns to analyse skill level. A longitudinal study of a developing player and a comparison of the developing player to an established expert demonstrates the utility of the developed method for evaluating expertise.     

COMMENT: THEORY AND EXISTENCE

The papers in this volume generally represent new developments in anthropology and cultural theory. Inevitably, in an evolutionary flowering, divergence can occur. Two of the papers represent a very new approach to theory for anthropology. This note discusses issues related to construction of theory that distinguish those papers.