摘要:

AbstractThis paper formalizes the operation of a monitor—one of the fundamental models for concurrent processing—in a framework which is an extension of CCS (the calculus of communication systems) proposed by Milner. The purpose of this paper is to define the mutual exclusion and synchronization control of a monitor based on formal computation mechanisms and to provide a basis for the verification of the properties of a monitor as a concurrent program.For this purpose, a programming language which directly represents the execution mechanism of the monitor and the syntactical translation from that language to a CCS expression are defined. Through this translation, the mutual exclusion of the monitor procedure as well as synchronization control by means of the conditional variable—the essential features of the monitor—are formalized within the CCS framework. As a result, by adopting an observable equivalence relation between the semantics of CCS operational expressions of the semantics of operation of the model, we show that it is possible to demonstrate the abstraction mechanism of th

ISSN:0882-1666    

DOI:10.1002/scj.4690230101

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe design problem of two‐level MOS networks with a minimum number of cells is reduced to the covering problem of graphs with a minimum number of cliques.When every node of the graph corresponds to a minterm, an algorithm which generates an MOS network with a minimum number of cells is presented. The time complexity of this algorithm isO(M)2, whereMis the number of minterms.When every node of the graph corresponds to a prime implicant, a procedure which generates near optimum solutions by selecting prime implicants with special properties is presented. About 2 percent of designed networks for four‐variable functions are not minimal o

ISSN:0882-1666    

DOI:10.1002/scj.4690230102

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes a method in which three kinds of stereo matching methods based on different image features are integrated by a cooperative processing to realize a matching search system applicable to a wide range of objects. In other words, the point‐based matching using correlation, the interval‐based matching using edges and the segment‐based matching using connected edges are combined. The module for dedicated execution of each algorithm is provided, and the modules execute the matching search in parallel. Whenever necessary, the partial result of the processing is exchanged to realize a complementary cooperation.Each module continues the processing for the part which can be processed without being assisted by other modules. Then, considering each local area of the image, the best‐suited algorithm is selected and applied automatically according to the situation. Each module evaluates the extent of confidence of its own processing, and the reliability score is attached when the result of processing is exchanged. The module receiving the data appropriately considers the received data into its own processing, according to the confidence. The disparity image generation module integrates the results of three matchings according to the extent of confidence. The method is applied to several stereo images, and the usefulness of the proposed method is demon

ISSN:0882-1666    

DOI:10.1002/scj.4690230103

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

年代:1992

数据来源: WILEY

摘要:

AbstractSome of the serious factors that deteriorate the reconstructed image in MRI are the static field inhomogeneity and the motion of the object (patient) during data acquisition. To prevent the deterioration of the reconstructed image by such factors,a prioriknowledge about the static field inhomogeneity and the motion of the patient is required.This paper considers the ultrahigh‐speed imaging using the time‐varying gradient magnetic field and proposes a method which estimates the static field inhomogeneity and the patient motion from the measured FID signal and thea prioriknowledge about the region of existence for the patient. When the patient is constrained within a certain region in the field of view, a strong constraint called consistency condition essentially is imposed on the functional form of the measured FID signal.In the proposed method, a simple mathematical model is applied to the static field inhomogeneity and the patient motion and the model parameters are estimated so that the consistency condition is satisfied. By the proposed method of estimation, the artifact due to the static field inhomogeneity and the patient motion can be reduced without performing an additional measurem

ISSN:0882-1666    

DOI:10.1002/scj.4690230104

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

年代:1992

数据来源: WILEY

摘要:

AbstractWith regard to competitive learning a neural network model consisting of two layers of neurons was constructed and a new energy (loss) function to ensure that the network will converge uniquely to the desired state is proposed. It was proved that when the number of cells in the hidden layer is equal to the number of the input patterns, this model does not have any local minima of the energy function other than the one that yields the global minimum and, consequently, converges to the global minimum from any initial values of the synaptic connections.In this equilibrium the network is organized to the state where only a single hidden cell responds to its corresponding input pattern. This model is compared with the other models of competitive learning proposed up to the present. Then a model of the associative memory based on this competitive learning model is proposed. In this model of the associative memory only output patterns that are presented during the learning are recalled even in response to an input that has never been presented during the learning. This model has an extra advantage in that the input patterns are requested to be neither orthogonal nor independent of each other.

ISSN:0882-1666    

DOI:10.1002/scj.4690230105

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe averaged projection filter (APF) is an optimal restoration filter proposed by the present authors in another paper. Here, properties of the APF are discussed in detail. For example, the image component of the restored image with the APF coincides with the original image if the original image belongs to a subspace. For the original images outside the subspace, the image component becomes the oblique projection onto a subspace of the original image in the mean square sense. A noise suppression mechanism of the APF also is clarified by using the null space of the APF. A simpler expression of the APF is given under some assumption. Finally, relations between the APF and the Wiener filter are discussed.

ISSN:0882-1666    

DOI:10.1002/scj.4690230106

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

年代:1992

数据来源: WILEY

摘要:

AbstractA restoration filter called the averaged projection filter (APF) is proposed for the linear degradation model. The proposed filter selects the image with the least deviation of noise component from among those minimizing the image component of the restored image in the averaged sense with respect to a set of original images. With the plain projection filter, the frequency of occurrence of images is ignored. In the averaged projection filter, the restoration quality of images occurring more frequently is improved at the expense of those occurring less frequently. A general form of the filter is obtained by using functional analysis. Some experimental results are illustrated which show the advantages of the proposed filter over the projection filter and the Wiener filter.

ISSN:0882-1666    

DOI:10.1002/scj.4690230107

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper proposes a novel method for acquiring a shape model from shape samples of the same class. In conventional approaches,a prioriknowledge and unique parts segmentation are needed because they perform generalization of predefined symbolic concepts. Moreover, they cannot form visual shape models because the model is represented as parts and parts relationships in the form of graph models such as semantic networks and multilevel graphs.The approach herein can directly acquire a visual model from a few samples withouta prioriknowledge because it is based on the generalization of multiscale convex/concave structure of a class of shapes.First, an optimal scale convex/concave segment structure common to shape samples using a multiscale segment matching method is extracted. Then the extracted segments are integrated to create generalized shapes. Finally, an importance measure based on the optimal scale is assigned to each convex/concave segment of the generalized shapes. That is, the proposed shape models consist of conjunctive descriptions as for the convex/concave segment structures, disjunctive descriptions as for the convex/concave segment forms, and the importance measure assigned to each segment of the shape model. A shape recognition method using the acquired models also is presented. Experimental results show the usefulness of the proposed method.

ISSN:0882-1666    

DOI:10.1002/scj.4690230108

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes the implementation of nonlinear optimization methods into the learning of neural networks (NN) and the speed efficiency of four proposed improvements into the backpropagation algorithm. The problems of the backpropagation learning method are pointed out first, and the efficiency of implementing a nonlinear optimization method as a solution to this problems is described.Two nonlinear optimization methods are selected after inspecting several nonlinear methods from the viewpoint of NN learning to avoid the problem of the backpropagation algorithm. These are the linear search method by Davies, Swann, and Campey (DSC), and the conjugate gradient method by Fletcher and Reeves.The NN learning algorithms with these standard methods being implemented are formulated. Moreover, the following four improvements of the nonlinear optimization methods are proposed to shorten the NN learning time: (a) fast forward calculation in linear search by consuming a larger amount of memories; (b) avoiding the trap to local minimum point in an early stage of linear search; (c) applying a linear search method suitable for parallel processing; and (d) switching the gradient direction using the conjugate gradient method. The evaluation results have shown that all methods described here are effective in shortening the learning time.

ISSN:0882-1666    

DOI:10.1002/scj.4690230109

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

年代:1992

数据来源: WILEY