Showing papers by "Indian Institute of Technology Guwahati published in 1998"

Radiative heat transfer in participating media — A review

Abstract: This paper presents an overview of various exact analytic and approximate numerical methods for the solution of radiative heat transfer problems in participating media. Review of each method is followed by its strengths and limitations. Importance of radiative heat transfer analysis and difficulties in the solution of radiative transfer problems have been emphasized.

Learning while solving problems in best first search

Abstract: We investigate the role of learning in search-based systems for solving optimization problems. We use a learning model, where the values of a set of features can be used to induce a clustering of the problem state space. The feasible set of h* values corresponding to each cluster is called h*set. If we relax the optimality guarantee, and tolerate a risk factor, the distribution of h*set can be used to expedite search and produce results within a given risk of suboptimality. The off-line learning method consists of solving a batch of problems by using A* to learn the distribution of the h*set in the learning phase. This distribution can be used to solve the rest of the problems effectively. We show how the knowledge acquisition phase can be integrated with the problem solving phase. We present a continuous online learning scheme that uses an "anytime" algorithm to learn continuously while solving problems.

Efficient computation of Euclidean distance transform for applications in image processing

Abstract: The paper presents a new parallel algorithm for computing Euclidean distance transform of a binary image. For an image of size n/spl times/n, the algorithm runs in O(n) time and takes O(n/sup 2/) space. The Euclidean distance transform is computed by repeatedly performing identical local operations within a small neighbourhood of each pixel. The algorithm is therefore suitable for VLSI implementation in a cellular like structure.

Accelerated spectral approximation

Abstract: A systematic development of higher order spectral analysis, introduced by Dellwo and Friedman, is undertaken in the framework of an appropriate product space Accelerated analogues of Osborn's results about spectral approximation are presented Numerical examples are given by considering an integral operator

On Ramanujan asymptotic expansions and inequalities for hypergeometric functions

Abstract: In this paper we first discuss refinement of the Ramunujan asymptotic expansion for the classical hypergeometric functionsF(a,b;c;x), c ≤a + b, near the singularityx = 1. Further, we obtain monotonous properties of the quotient of two hypergeometric functions and inequalities for certain combinations of them. Finally, we also solve an open problem of finding conditions ona, b > 0 such that 2F(−a,b;a +b;r 2) < (2−r 2)F(a,b;a +b;r 2) holds for all r∈(0,1).

A parallel skeletonization algorithm and its VLSI architecture

Abstract: This paper presents a new algorithm to extract the skeleton and its Euclidean distance values from a binary image. A VLSI implementation of the algorithm in a locally connected cellular array is also given. The algorithm runs in O(n) time for an image of size n/spl times/n. The extracted skeleton reconstructs the objects in the image exactly.

DOA estimation by least squares approach

Abstract: A least squares estimation technique for finding the directions of arrival (DOAs) of signals corrupted by additive white noise using a uniform linear array is developed Although the estimates are not as accurate as those of subspace methods, the computations involved are simpler, and prior knowledge of the number of sources is not required

Apportioning: a technique for efficient reachability analysis of concurrent object-oriented programs

Abstract: The object-oriented paradigm has been found to be useful for the construction of large and complex concurrent systems. Reachability analysis is an important and well-known tool for static (pre-run-time) analysis of concurrent programs. However, direct application of traditional reachability analysis to concurrent object-oriented programs has many problems, such as incomplete analysis for reusable classes (not safe) and increased computational complexity (not efficient). We have proposed a novel technique called apportioning, for effective reachability analysis of concurrent object-oriented programs, that integrates the techniques of abstraction (considering a reduced representation of the system) and partitioning (dividing the system into smaller units). The given program is apportioned into a reduced version of each of its classes, as well as a reduced version of the program. The error to be checked is also decomposed into appropriate sub-properties for checking in the reachability graphs corresponding to the apportioned program. We have developed a number of apportioning-based algorithms, having different degrees of safety and effectiveness. In this paper, we present the details of one of these algorithms.

Computation of penetration measures for convex polygons and polyhedra for graphics applications

Abstract: Algorithms to compute measures of penetration between convex polygonal objects in /spl Rfr//sup 2/ and convex polyhedral objects in /spl Rfr//sup 3/ are presented. The algorithms are analyzed for their asymptotic complexity. Details of implementation on a single processor machine are given. Parallelization of the algorithms is discussed.