Shun-Shan Tsai

Parallel clustering algorithms on a reconfigurable array of processors with wider bus networks

Clustering techniques are usually used in pattern recognition, image segmentation and object detection. For N patterns and k centers each with M features, in this paper, we first design an O(kM) time optimal parallel algorithm for one pass process of clustering with the k-means method on a linear array of processors with a wider bus network using N/sup 1+1/c/ processors with one bus network, where c is any constant and c/spl ges/1. Then, based on the proposed algorithm, two O(k) and O(1) time optimal parallel clustering algorithms are also derived using MN/sup 1+1/c/ and kMN/sup 1+1/c/ processors with M row and MN row bus networks, respectively. These results improve the best known bounds and achieve cost optimal in their time and processor complexities.

Building a quadtree and its applications on a reconfigurable mesh

Abstract Quadtree is an efficient method to represent binary images. How to build a quadtree for a binary image is worthy of study. The major contribution of this paper is that we first use the Hilbert mapping technique to represent the binary image. Then, based on the reconfigurability of the reconfigurable mesh, a constant time algorithm for building a quadtree for an n × n binary image using n × n processors is derived. For applications of this algorithm two methods for compressing and decompressing binary images are also proposed.

Optimal Speed-Up Parallel Image Template Matching Algorithms on Processor Arrays with a Reconfigurable Bus System,

The image template matching problem is one of the fundamental problems of and has many practical applications in image processing, pattern recognition, and computer vision. It is a useful operation for filtering, edge detection, image registration, and object detection 13]. In this paper, we first design twoO(M2/p2)log logM] andO(M2/p2)+(M/p)log logp] time parallel image template matching algorithms on a 3-D processor array with a reconfigurable bus system usingp2N2processors with each processor containingO(1) andO(M/p) restricted memory for 1 ?p?M?N, respectively, for anN×Ndigital image and anM×Mtemplate. By increasing the number of processors, these two proposed algorithms can be run inO(M2/p2) time for speeding up the time complexity usingp2M1/cN2andp2+1/cN2processors, respectively, wherecis a constant andc?1. Furthermore, anO(1) time can be also obtained from these two proposed algorithms by usingM2+1/cN2processors. These results improve the best known bounds and achieve both optimal and optimal speed-up in their time and processor complexities.

Solving an algebraic path problem and some related graph problems on a hyper-bus broadcast network

The parallel computation model upon which the proposed algorithms are based is the hyper-bus broadcast network. The hyper-bus broadcast network consists of processors which are connected by global buses only. Based on such an improved architecture, we first design two O(1) time basic operations for finding the maximum and minimum of N numbers each of size O(log N)-bit and computing the matrix multiplication operation of two N/spl times/N matrices, respectively. Then, based on these two basic operations, three of the most important instances in the algebraic path problem, the connectivity problem, and several related problems are all solved in O(log N) time. These include the all-pair shortest paths, the minimum-weight spanning tree, the transitive closure, the connected component, the biconnected component, the articulation point, and the bridge problems, either in an undirected or a directed graph, respectively.

Fundamental data movement operations and its applications on a hyper-bus broadcast network

A hyper-bus broadcast network (HBBN) consists of processors only sharing by some global buses, and there are no local links between processors. Based on such an architecture, we will exploit several efficient time parallel algorithms for solving the well-known fundamental data movement problems which had been extensively studied by researchers and widely applied to the field of image processing, digitized geometry and computer graphics. These include the leftmost one problem, the prefix maxima/minima problem, the m-contour problem, the all nearest neighbor problem and the all nearest smaller values problem, respectively. Note that the proposed algorithms not only can be implemented on the HBBN but also can be easily modified to run on other broadcast-based networks with the same time and processor complexities.

PARALLEL SORTING ALGORITHMS ON A HYPER-CHANNEL BROADCAST COMMUNICATION MODEL

This paper presents a new improved architecture, named a hyper-channel broadcast communication model, as a computational model. The hyper-channel broadcast communication model consists of processors shared by some channels, and there are no local links between processors. Based on such an improved architecture, we first design two O(log N) cycles basic operations for finding the maximum/minimum of N real numbers and the ranks of a linked list using N and N×N processors, respectively. Then based on these proposed operations, two O(log N) cycles sorting algorithms are derived by either using N×N processors for the concurrent-write case or using N×N×N processors for the conflict-free case, respectively.

Parallel connectivity algorithms on permutation graphs

In this paper, we shall present several algorithms for determining the maximum number of vertex connectivity, testing k-vertex connectivity, determining the maximum number of vertex disjoint s-t paths and finding k-vertex disjoint s-t paths problems on a permutation graph, respectively. We first give several O(n/sup 2/) time sequential algorithms for determining the maximum number of vertez connectivity, testing k-vertex connectivity and determining the maximum number of vertex disjoint s-t paths problems, respectively. Then, an O(kn/sup 2/) time algorithm for finding k-vertex disjoint s-t paths problem on a permutation graph is also proposed. Moreover, we also derive the corresponding parallel algorithms for these problems from the proposed sequential algorithms. On the EREW PRAM model, we first propose several O(log n) time optimal speed-tip parallel algorithms for determining the maximum m number of vertez connectivity, testing k-vertex connectivity and determining the maximum number of vertex disjoint s-t paths problems, all with O(n/sup 2/log n) processors, respectively. Then, an O(nlog n) time parallel algorithm for finding k-vertex disjoint s-t paths problem using O(n/sup 2/log n) processors is also developed, where k is a fixed integer.<<ETX>>