摘要:

AbstractThis paper considers the design and implementation of a Unix‐based global network system named X25 Net: X25 Net uses X.25 protocol and has the following characteristics:1A compatible network interface with Unix 4.2 BSD is provided.2The amount of packet transmission is small.3It is not required to establish additional expensive hardware devices.We describe the design policy, layer, implementation, and measured performance of X25 Ne

ISSN:0882-1666    

DOI:10.1002/scj.4690190701

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

年代:1988

数据来源: WILEY

摘要:

AbstractWhen a telewriting signal of handwritten text and graphics shares a common telephone channel with voice, the data rate of the telewriting must be curtailed to maintain the quality of the audio portion. A fixed rate sampling method with linear interpolation has been used in telewriting because of its simplicity. However, this method does not perform well when distortions are caused by higher drawing speed of line strokes. To overcome such a shortcoming, this paper: (1) investigates the distortions associated with the fixed rate sampling method; (2) derives quantitative measures of interpolation distortion and truncation distortion; and (3) proposes an adaptive sampling algorithm. A writing tablet (4 dots/mm resolution) was used in the experiments to validate the objective measures, and to assess the performance of the adaptive algorithm. Experimental results indicate that while the data rates of the fixed rate sampling method and the adaptive method are almost the same, the adaptive method scores higher in the subjective image quality assessment tests.

ISSN:0882-1666    

DOI:10.1002/scj.4690190702

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper discusses the design of the fast data encipherment algorithm (FEAL). FEAL is a conventional encipherment algorithm using the same key for enciphering and deciphering. It is a block cipher algorithm which produces 64 bit ciphertext from 64 plaintext, using a 64‐bit key. The main feature of the cipher processing in FEAL is that it is based on 8‐bit data manipulations such as addition with modulo 256, and data cycle and data transfer commands for 1‐byte. The program performance of FEAL is improved greatly compared with that of DES. The security of FEAL is based on the characteristic value representing the trace of the plaintext and ciphering key remaining in the ciphertext, as well as on the algorithm stru

ISSN:0882-1666    

DOI:10.1002/scj.4690190703

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

年代:1988

数据来源: WILEY

摘要:

AbstractWith the recent remarkable development of VLSI technology, the study and the experimental development of multiprocessors composed of a large number of processors have actively been performed. A serious problem in such systems is the contention (conflict) in communication. A clustered system is proposed as a means to ameliorate the problem, where processors are grouped into several units. This paper derives a theoretical expression for the processing efficiency of the clustered multiprocessor system. An experimental system was constructed, which is composed of 32 processors, being grouped into 4 clusters, each of which is composed of 8 processors. The design of the software and the result of implementation are described. As a practical example, the summation of a series and the solution of a system of linear equations are considered. The processing efficiencies of the clustered and nonclustered systems were measured and compared. It is shown as a result that the clustered system can improve the system efficiency considerably by adding a small amount of hardware.

ISSN:0882-1666    

DOI:10.1002/scj.4690190704

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper proposes cautious schedulersCS(WW(k))andCS(WRW(k)), which are generalizations of the recently proposed cautious schedulersCS(WW), CS(WRW)and their multi‐version modelsCSm(MWW), CSm(MWRW).Here, it is assumed that onlykversions of each data item are available. It is shown that their completion test can be performed in polynomial time, and that their fixed point setsWW*(k)andWRW(k)form infinite hierarchies, respectively, whenkis increased from 1 to ∞. It is shown also that neitherCS(W(k))norCS(WRW(k))exhibits cancellation anomaly. These results indicate the practical importance of the cautious schedulers proposed her

ISSN:0882-1666    

DOI:10.1002/scj.4690190705

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper discusses the tomographic reconstruction processing from the incomplete projection data with limited projection angle, based on the estimation of the missing data by extrapolation. Essentially, there is a kind of correlation, called consistency condition, among the projection data of different directions. Mathematically, it is possible to reconstruct the image by estimating the missing data from the measured data utilizing this correlation. The algorithm proposed in this paper is based on such a mathematical principle. In this kind of inverse problem, however, the measurement noise and the computational error are greatly amplified. By applying the constrained extrapolation, which combines the known information concerning the smoothness of the object image, the processing is stabilized. As a result of the simulation experiment using a model image, it was demonstrated that the proposed method is more useful and practical for this problem, from the viewpoints of the quality of the reconstructed image, the computational complexity, and the stability against the measurement noise.

ISSN:0882-1666    

DOI:10.1002/scj.4690190706

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn actual image recognition, one does not always view the whole image, but often subjectively selects a certain subregion on the image to obtain some useful information. This paper clarifies theoretically the reason why such an ability possessed by humans is naturally carried out, by using a mathematical analysis regarding the fundamental properties of a visual pattern. A mathematical formula showing multilayer structures of a visual pattern is obtained by the foregoing analysis. The results obtained in this paper may contribute to elucidating the aspect of the basic process of the feature extraction from the pattern.

ISSN:0882-1666    

DOI:10.1002/scj.4690190707

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper considers the Japanese speech input system which recognizes the continuously uttered speech by the standard syllable patterns. In such a system, the dictionary matching procedure is required, where all possible combinations of syllable candidates contained in the recognition result are compared with the Japanese dictionary to select the combinations of syllables contained in the dictionary (i.e., word candidates). Usually, however, there exists a tremendous number, up to several thousands, of possible combinations of syllable candidates obtained from the recognition of continuous speech. On the other hand, a Japanese dictionary, in general, contains several tens of thousands of words. Consequently, the matching procedure requires about 1 s which should be improved from the viewpoint of the system response time. This paper proposes a high‐speed algorithm which directly matches the result with the dictionary. In this algorithm, the kinds of syllable candidates contained in the recognition result of speech are mapped on the RAM address space to be compared with the dictionary, making it unnecessary to expand the result of recognition into a large number of syllable candidate combinations, as in the traditional methods. The design of LSI is discussed which realizes the proposed algorithm by a hardware. The LSI can compare 10 speech recognition results, which contain the syllable sequence length up to 7 and up to 4 candidates for each syllable, with a dictionary of 30, 000 words, in approximately 13 ms. Thus, the processing speed is improved almost by two orders of magnitude, compared with the traditional method

ISSN:0882-1666    

DOI:10.1002/scj.4690190708

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper presents a vectorization processing method for circuit analyses using a vector computer. It had been difficult in circuit analyses to evaluate device models with an adequately long vector length, which is the most expensive task in the computation. Therefore use of a vector computer could improve the computation time only a few times. In the proposed method, the evaluation of device models is carried out at the level of a basic element and each evaluation is vectorized throughout the circuit matrix. It is shown that neither the forward nor backward substitutions can be ignored in solving a sparse matrix with the LU decomposition method. Therefore, the vectorization is applied to the whole matrix‐solving process. These algorithms are realized in a user‐defined model circuit analysis program FINAP‐VP. As a result, all the main processes of the analysis loop are vectorized with the length of the order of a hundred to ten thousand so that the analysis time for the scalar mode was improved by a factor of more than 10. This paper describes the method of vectorization of the device‐models evaluation and the circuit matrix solution (which are the main process in a circuit analysis). The results of the benchmark tests using the vector‐computer FACOM‐VP, are als

ISSN:0882-1666    

DOI:10.1002/scj.4690190709

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

年代:1988

数据来源: WILEY

摘要:

AbstractTwo‐person zero‐sum games with perfect information can be represented by minimax game trees. By solving such game trees, it is possible to compute the game values that are realized when both players always choose the best moves. Various search algorithms, such as α ‐β, SSS*, dual SSS*, B*, H*, are known for this purpose. Let A and B be two search algorithms; A surpasses B if, for any game tree, the region explored by A before computing the game value is contained in the region explored by B; A strictly surpasses B if A surpasses B and the region explored by A is properly contained in the region explored by B for at least one game tree. In this paper, we prove that no search algorithm strictly surpasses SSS* or du

ISSN:0882-1666    

DOI:10.1002/scj.4690190710

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

年代:1988

数据来源: WILEY