摘要:

AbstractNonindexed queries in a relational database are performed by searching operations, i.e., read out all rows in a table from disks and repetitive condition judgment for each row. Therefore, it takes a long response time on software‐only systems.This paper discusses a searching architecture implemented in a RINDA system which is an attached processor of relational database management systems (DBMS). Performance evaluation indicates that RINDA enhances the response of nonindexed queries by as much as 100 times compared to software‐only systems.The proposed main features are as follows:(1) The effective functions to achieve a short response time are selected and then implemented as a CSP hardware; (2) for a cooperative process with both CSP and software, the internal format of searching conditions is translated in conjunctive canonical form; (3) by executing NOT operator in a logical equation directly in predicates, the SQL three‐value logic degenerates into two‐value; and (4) by using multiple CSPs, parallel search processing is pe

ISSN:0882-1666    

DOI:10.1002/scj.4690240901

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe authors have been developing a distributed operating system called Threads on Modules (ToM). It supports a programming model which is suited for distributed environments. For this purpose, modules, threads, houses, users, RPCs and capabilities are introduced.To make the ToM system as portable as possible, it was implemented using the microkernel technology. The ToM microkernel implements the minimal functionalities and the others are implemented as user level programs. Although the ToM microkernel is designed to support the ToM programming model, it has sufficient functionalities to implement other operating systems. This paper presents some of the main features of the ToM microkernel. A UNIX emulator also is presented.

ISSN:0882-1666    

DOI:10.1002/scj.4690240902

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSymmetrical Network Topologies (SNT's) for VLSI massively parallel computers are proposed. VLSI massively parallel computers can be expected to integrate more than dozens of processing elements. It is desired that the network in such a VLSI system is regular.SNT consists of a two‐dimensional end‐around mesh with supplementary symmetrical branch connections, and therefore, it satisfies the condition of regularity. In this paper it is shown that the SNT's have desirable characteristics with regard to diameter and average distance. That is, the SNTs have smaller diameters and average distance compared to the hypercubes with the same number of nodes. For example, for 4096 nodes, the degree, diameter and average distance of a hypercube are 12, 12 and 6.001, respectively. The degree, diameter and average distance of the SNT can be 8, 8 and 5.324, respectively. It is shown also that SNTs are maximally connected graphs resulting in a fault‐tolerant network. Results show that SNT's are well suited for the VSLI implementation of massively parallel comp

ISSN:0882-1666    

DOI:10.1002/scj.4690240903

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe EM‐4 is a highly parallel computer which achieves high performance in data communication as well as instruction execution. An EM‐4 prototype which consists of 80 processing elements (PEs) has been fully operational since April 1990.This paper evaluates the basic parallel execution performance of the EM‐4 prototype, considering the performance of instruction execution, network data transfer, and data synchronization. First, an attempt is made to achieve maximum performance by executing artificial programs and comparing them to the theoretical maximum performance. Next, the average performance is evaluated by executing simple programs. The results show that the instruction execution performance is 630 MIPS, the network data transfer is 400 Mpacket/s, and the data synchronization is 35 Ms

ISSN:0882-1666    

DOI:10.1002/scj.4690240904

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA system based on multiagents is proposed as an information processing model for robot programming. This model uses object‐oriented representation in which physical entities are described as logical objects. An agent is an active and independent logical entity which can control objects. Agents work cooperatively and concurrently, communicating with each other to perform the task assigned to the robot. An agent starts a new job or changes its behavior when a specific event occurs or when it receives a message from another agent. This multiagent system provides robot programmers with a useful mental model for dividing the task of a robot into several segments and distributing them to several personified processes which control subtasks.This paper presents an overview of an experimental system used for multiagent robot programming and describes its implementation on a Lisp machine which supports multiprogramming and object‐oriented programming. The Tower of Hanoi task is used to test the system. It demonstrates that the multiagent system, using function‐based and behavior‐based agents, provides a high‐level modular programming environment for robo

ISSN:0882-1666    

DOI:10.1002/scj.4690240905

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn handling the graphic data of a finite size, the minimal rectangle, which is the minimal rectangle surrounding the graphic data, or the minimal sphere, which is the minimal sphere surrounding the data, often is employed as the intermediary representation of the data to speed‐up the retrieval and manipulation of the graphic data. However, when most of the retrieval time is occupied by the check of the intersection rather than by the tracing of the data structure, as in the case of complex data or data placed on the external memory with a lower speed, a more efficient intermediary representationof the graphic data is required. This can reduce the number of intersection checks and speed‐up the retrieval, compared to the method based on the minimal rectangle or the minimal sphere.From such a viewpoint, this paper proposes an intermediary representation of the graphic data using dots on the minimal rectangle as one such intermediary representation of the data. Theoretical as well as experimental evaluations are presented. It is seen as a result of the theoretical calculation and simulation experiment that compared to the method based on the minimal rectangle, the proposed method can reduce drastically the number of intersection checks which helps to reduce the actual retrieval time. In the case of straight‐line data, for example, of length less than the edge length of the retrieval area, the number of intersection checks can be reduced to one‐fourth that of the method based on the minimal rectangle, even in the wor

ISSN:0882-1666    

DOI:10.1002/scj.4690240906

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents a test generation method using an optimization technique for a single stuck‐at fault in synchronous sequential circuits. This method utilizes a new real number simulation for defining the cost of an input pattern for a given fault and leads an input pattern to a test pattern by changing the input repeatedly to minimize its cost.Since a sequential circuit has internal states, a test pattern for a fault is a sequence of input vectors for several time frames. For generating the whole test pattern, the concept of forward test generation, which performs the convergence calculation process at multiple time frames, is introduced to avoid the problem of local optimum.Experimental results for ISCAS '89 benchmark sequential circuits show the effectiveness of the proposed method for sequential circuit test generatio

ISSN:0882-1666    

DOI:10.1002/scj.4690240907

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn an X‐ray computed tomography (CT), time to scan an object must be allowed to obtain its projection data. If the object is not steady during the scanning, its reconstructed image would contain errors called “motion artifacts.” Recently, two kinds of motion artifact, “blurred image” and “stroboscopic image,” have been found in clinical experience, and their theoretical analyses have been demanded. Assuming that an object is a rigid body, its motion can be divided into rotary and parallel motions.This paper analyzes the degradation of reconstructed images and artifacts due to the rotary motion of a rigid object. The degradation of a CT image caused by rotation of an arbitrarily shaped rigid object is formulated by using a point‐spread function. The characteristics of blurred images of a rigid object due to its rotation in a CT and the shape of blurred images also are analyzed. The cause of stroboscopic images is explained by using line sources. The theories have been confirmed by comp

ISSN:0882-1666    

DOI:10.1002/scj.4690240908

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn a document analysis system, block segmentation and block classification are very important. The former segments a particular document image into homogeneous rectangular blocks. The latter classifies the segmented blocks into categories. These classified blocks may then be processed by suitable recognition systems. In this paper, we formalize the structure styles of general documents, and then propose both a robust hierarchical method of block segmentation and a simple method of block classification. The proposed block segmentation method takes a top‐down hierarchical approach based on the spatial features and formalized concepts of document structure. This method is essentially independent of the document style, and can perform a type of structural analysis of the document image. The classification approach is based on a new scheme of statistical textual features, and classifies the segmented blocks into four categories: text blocks, title letter blocks, line drawing (or graphics) blocks, and halftone phonograph blocks. The proposed approaches were implemented using the C programming language in an X‐Window environment under the UNIX operating system. The performance of each approach was experimentally evaluated, for both effectiveness and computational efficiency, using actual test ima

ISSN:0882-1666    

DOI:10.1002/scj.4690240909

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper discusses the problem of the piecewise‐linear approximation of contour images. Almost all the piecewise‐linear approximation methods that have been proposed can be applied only for continuous contours. Methods that can work well for discontinuous contours, for instance, have not yet been found.In this paper, a new method is proposed based on clustering as a piecewise‐linear approximation method that can even be applied to discontinuous contour images. Specifically, the method uses hard clustering or fuzzy clustering, where the set of edge points in the image is partitioned into line segment groups and parameters of line segments are computed from the groups. Good results were obtained in the evaluation experiment to verify the effectiveness of the proposed m

ISSN:0882-1666    

DOI:10.1002/scj.4690240910

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY