摘要:

AbstractThis paper presents properties of Exclusive‐OR Sum‐of‐Products expressions (ESOPs) for multiple‐output functions and a simplification algorithm for ESOPs. First, lower bounds on the number of products in minimum ESOPs for multiple output functions are derived. Then, algorithms to simplify ESOPs and to prove their minimality are presented. Experimental results for arithmetic functions and randomly generated functions for up to ten variables ar

ISSN:0882-1666    

DOI:10.1002/scj.4690270901

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

年代:1996

数据来源: WILEY

摘要:

AbstractIn multiprocessor systems with a common bus arbiter, contention for access to the common bus and shared memory is a major cause of performance degradation. The first‐order moment match approximation is an effective technique of performance evaluation in such systems. Comparison with simulation results demonstrates that the first‐order moment match technique gives good accuracy. The performance of completely coupled multiprocessor systems is compared with that of bus‐arbitrated multiprocessor systems in order to determine the applications for which the latter is best s

ISSN:0882-1666    

DOI:10.1002/scj.4690270902

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

年代:1996

数据来源: WILEY

摘要:

AbstractThis paper proposes the “poly‐aspect data model,” which is an extension of the object‐oriented data model. The purpose of the poly‐aspect data model is to represent in a natural way the multimedia data in the database. One of the features of the multimedia data is the diversified representation of the entities of the real world. In the poly‐aspect data model, the entity is interpreted as an object, and a model is provided so that multiple complete representations are given to the object. Such an object is called the poly‐aspect object. In the poly‐aspect data model, an object may have more than one instance as its representation. The class defines the format of the instance. The multiple instance of the same object are distinguished by the class names. When the attributes of multiple instances are defined by the same superclass, those attributes are interpreted to have the same semantics. The same value is shared among the instances, and the consistency is retained.As a realization example of the poly‐aspect object, the architecture of the “Sarah” database management system, which is currently being constructed experi

ISSN:0882-1666    

DOI:10.1002/scj.4690270903

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

年代:1996

数据来源: WILEY

摘要:

AbstractAn attribute grammar is a formal system consisting of a context‐free grammar together with semantic rules, which enables us to describe not only the syntax but also the semantics of language. The limited framework of attribute grammar, however, is not conducive to expansion of the system and the many ambiguous definitions of attribute grammar make it difficult to examine its formal nature.We propose a generalized attribute grammar based on the following two grammatical viewpoints:•the use of type‐0 grammars in place of the basic, context‐free grammars.•relaxation of the restrictions of semantic rules.The generalization is a formal system that allows us to define computation derived from the attribute grammars. We can also use the generalization as a framework for discussing abstract characteristics of the attribute grammars.This paper provides a formal definition and classification of general attribute grammars. We define the semantics of general attribute grammars by using semantic functions whose inputs are structures derived from the underlying grammar and whose outputs are attributed structures. We provide classifications of general attribute grammars based on the abstract properties of semantic functions.We regard general attribute grammars as constraint satisfaction systems. Traditional attribute grammars are restricted in that underlying grammars are context free and semantic rules are solved by unidirectional local pr

ISSN:0882-1666    

DOI:10.1002/scj.4690270904

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

年代:1996

数据来源: WILEY

摘要:

AbstractThis paper proposes the recursive diagonal torus (RDT), which is the interconnection network for the massively parallel computer with 216or more processors. RDT can realize a small diameter (12 for 16 Knode) with a small number of links compared to the hypercube by adding links recursively along the diagonal direction of the two‐dimensional torus. The packet is routed by a simple algorithm called vector routing. RDT not only includes a torus, but also easily implements the emulation of the hypercube or tree as well as the packet broadcast. Considering a typical packet transfer method, the random transfer performance is evaluated. A satisfactory result is obtained compared to the 2‐D or 3‐D torus, although somewhat inferior to the hypercube with a large number of

ISSN:0882-1666    

DOI:10.1002/scj.4690270905

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

年代:1996

数据来源: WILEY

摘要:

AbstractImage representation using the random iterated function system (Random IFS) has a disadvantage in that it requires many iterations. This paper proposes image representation through a gray‐scale iterated function system. This method requires fewer iterations and it can obtain better images than the random IFS. The saving in iterations is realized first by the use of a deterministic method, whereas in the random IFS, each mapping is defined as a probablistic event, and it needs many iterations to satisfy the law of large numbers.In the proposed method, the reconstructed image converges faster than in the conventional method, and it is shown to yield better reconstructed images. Second, statistical characteristics of the IFS parameters are investigated to be used for further accelerating the IFS parameter search. The characteristics are shown to be stable among different images. Simulation results are included to demonstrate the effectiveness of the accelerated algorith

ISSN:0882-1666    

DOI:10.1002/scj.4690270906

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

年代:1996

数据来源: WILEY

摘要:

AbstractThresholding techniques are fundamental for region segmentation of a gray level image. It is often realistic to assume that gray pixel levels are subject to a mixture of normal distributions. This paper points out problems caused by the underestimation of variances from a frequency distribution and solves the problems by transforming a frequency distribution into a piecewise‐continuous distribution based on the maximum entropy criterion. This transformation improves conventional thresholding techniques. Experimental results showed the effectiveness of the transformatio

ISSN:0882-1666    

DOI:10.1002/scj.4690270907

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe derivation of mathematical models for robot vehicles is extremely difficult due to the high non‐linearity of the motion characteristics, making it hard to apply the conventional control theory without using approximation methods which assume constant speed, etc. In this paper, the motion control method using a neural model proposed by Uno, Kawato et al. is extended in such a way to allow its application to the travel control problem of a robot vehicle, which is highly nonlinear with respect to the driving force and steering angle, and a method that generates motion commands and performs trajectory planning at the same time is proposed. In this case, the internal coordinates of the identification module which learns the motion characteristics of the robot vehicle are viewed as motion coordinates, and a method to convert the absolute coordinates for each discrete time into motion coordinates is proposed, making it possible to reduce greatly the number of learning patterns. Furthermore, a variable target time algorithm is proposed that counteracts the centrifugal force effects which act on the robot vehicle when the curvature of the generated trajectory is large. The proposed algorithm restrains the centrifugal force and generates optimal motion commands and trajectory, producing results close to those obtained by a human driver. The effectiveness of the proposed method is demonstrated by computer simulatio

ISSN:0882-1666    

DOI:10.1002/scj.4690270908

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

年代:1996

数据来源: WILEY

摘要:

AbstractTheoretical studies on Iijima's “Theory of Pattern Recognition,” which is known as a method of multiple similarity, have shown clearly that there are situations when it is difficult to determine the viewpoint and visual field, important parameters to introduce topological aspects into the pattern space, observing a figure itself. To cope with this problem, this paper proposes transforming the observed image from a figuref(r) to a second‐order differential imagep(r), called “figure source.” The aim is to reconstruct the theory in such a way as to enable the application of similarity evaluation methods as in the conventional case, without compromising the current theory, and all the necessary proofs are given. In this paper, the figure source equation as well as rules representing its properties are developed, and several related physical quantities are

ISSN:0882-1666    

DOI:10.1002/scj.4690270909

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

年代:1996

数据来源: WILEY

摘要:

AbstractPost‐processing of character recognition refers to the processing used to correct the errors in character recognition. When the input is a string representing a sentence in the highly precise error correction, it is desired that the syntactic as well as semantic examinations should be made at the sentence level.This paper assumes that the morphemes, syntax and semantics of the input sentence can be analyzed, and proposes a method that uses the syntactic and semantic analysis in the post‐processing. The proposed method receives the list of candidate characters up to the fifth, and outputs the sentence that is adequate from the viewpoints of both syntax and semantics. The method features the following three points: (1) in word matching, it is examined also whether or not a sentence adequate from the viewpoints of syntax and semantics can be composed, and then the inadequate words extraction is inhibited; (2) characters having stronger syntactic and semantic constraints, such as the single‐character particle and the conjugational suffix, are estimated top‐down. Then, the case where the adequate character is not contained in the candidates can be handled; and (3) the words for which the adequateness cannot be determined from the syntactic or semantic viewpoint are selected by character re‐recognition processing. An experiment is executed for 50 sample sentences. The character recognition rate is improved from 83.0 percent to 98.0 percent, and the sentence recognition rate is improved from 10.0 percent to 94.0 percent. Compared to the method based only on word matching, the sentence recognition rate is improved by more than 20 percent. In other words, the effectiveness of the proposed method is dem

ISSN:0882-1666    

DOI:10.1002/scj.4690270910

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

年代:1996

数据来源: WILEY