Volume 18, 1999, No. 6


Object-oriented parallel software for radio wave propagation simulation in urban environment

F. Guidec, P. Calégari, P. Kuonen, M. Pahud

Abstract. The objective of the European project STORMS (Software Tools for the Optimization of Resources in Mobile Systems) is to develop a software tool to be used for design and planning of the future Universal Mobile Telecommunication System (UMTS). In this context the ParFlow method permits the simulation of outdoor radio wave propagation in urban environment, modeling the physical system in terms of the motion of fictitious microscopic particles over a lattice. This paper gives an overview of the Parflow method, and reports the design, the implementation, and the performance analysis of ParFlow++, an object-oriented irregular parallel software for urban outdoor radio wave propagation prediction.

 

A morphological approach to Hough transform on an instruction systolic array

B. Schmidt, M. Schimmler, H. Schröder

Abstract. Instruction systolic arrays have been developed in order to combine the speed and the simplicity of systolic arrays with the flexibility of MIMD parallel computer systems. Instruction systolic arrays are available as quadratic arrays of small RISC processors capable of performing integer and floating point arithmetic. In this paper a new algorithm for line detection is presented which applies the morphological approach to the well-known Hough transform. The quality of its results is significantly higher than that of the classical Hough transform. Our algorithm has an AT-complexity of O(N3). This matches the one of the best known alternatives in the literature. It will be shown that the new algorithm is more efficient in practical applications. It has been tailored towards the capabilities of the instruction systolic array. This leads to a high-speed implementation on Systola 1024, the first low cost parallel computer of this particular architecture on the market.

 

Nonspecificity degrees of basic probability assignments in dempster-shafer theory

I. Kramosil

Abstract. Basic probability assignment is a probability distribution on the power-set  (set of all subsets) of a finite set S and the nonspecificity degree of this basic probability assignment is the normalized expected value of the size (cardinality) of subsets of S with respect to this probability distribution. This notion enables to express formally and to prove the intuitive feelings of improving one's basic probability assignment and belief function when combining it with another one by the Dempster combination rule. It enables also to define a basic probability assignment which can be used, at least in certain relations, as an inverse basic probability assignment to the given one with respect to Dempster rule, even if we know that such an inverse element cannot be defined up to the most trivial case of the vacuous basic probability assignment. Analogous properties of the combination rule dual to the Dempster rule are also briefly investigated.

 

A computational model of evolution: Haploidy versus diploidy

P. Isasi, A. Sanchis, J. Molina, A. Berlanda

Abstract. In this paper, the study of diploidy is introduced like and important mechanism for memory reinforcement in artificial environments where adaptation is very important. The individuals of this ecosystem are able to genetically "learn" the best behaviour for survival. Critical changes, happening in the environmental conditions, require the presence of diploidy to ensure the survival of species. By means of new gene-dominance configurations, a way to shield the individuals from erroneous selection is provided. These two concepts appear like important elements for artificial systems which have to evolve in environments with some degree of instability.

 

Possibilistic information measures and selection approach

Do Van Thanh

Abstract. The aim of this paper is to introduce a use of both the principle of minimal specificity (mS) and maximal buoyancy (MB) for selecting a distribution from a given set of quantitative possibility distributions. In this paper some conditions of a set of possibility distributions and weights which guarantee "always selected situation" of a possibility distribution selected by the use of these principles from the given distribution set are proposed.


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