摘要:

AbstractVarious sensitivities necessary for prediction and evaluation of changes in characteristics of networks due to the changes in the value of elements and for optimization of networks, can be computed by using the derivatives of denominators and numerators of network functions with respect to elements. However, existing computing methods of derivatives are not suitable when the number of elementsmism>n(where the size of the matrix representing the network isn×n), that is, the sensitivity analysis which must be computed with respect to many elements. This paper presents a method to compute higher‐order derivatives of denominators and numerators of digital, analog and switched capacitor networks, using Vlach's redundancy improved method. Also, the proposed method and existing methods are compared with respect to the memory size and the number of multiplications required. It is shown that this method is more effective for analyzing the sensitivity for many elements. Finally, the method is implemented here and applied to several examples for element sensitivity analys

ISSN:8756-6621    

DOI:10.1002/ecja.4410691001

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper describes the properties of the second‐order digital bandpass filter functions which are obtained from the secondorder analog bandpass functions by the bilinearz‐transformation. Taking note of the magnitude and the argument of the poles of the bilinear‐transformed transfer function, we can express the center frequency, the bandwidth and the variable range of the center frequency of the bandpass filter as simple functions of these parameters. In particular, when the poles are complex conjugate, it can be shown that the bandwidth does not change with the argument of the poles if the magnitude of the poles is constant. It seems that in the past the quality factorQof digital filters has not been investigated fully. In this paper we introduce two definitions ofQfrom the time and frequency domains, and show that they are numerically equivalent if the ratio of the product of the center frequency and sampling rate toQis less than a certain value. Finally, we discuss the relation between the pole argument and the filter dynamic range when the second‐order digital bandpass function is realized in dire

ISSN:8756-6621    

DOI:10.1002/ecja.4410691002

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

年代:1986

数据来源: WILEY

摘要:

AbstractBy means of autoassociative memory we can read out (or associate) original complete information from incomplete memorized information. If we assume that incomplete memorized information is made of additive noise and original information, autoassociative memory can be regarded as a noise attenuation filter. In this paper, using the twostepped association procedure we proposed earlier, we compose autoassociative memory and with its characteristics, propose a new method to improve the ability of noise attenuation in associative memory. This method restricts the width of the associative output space by changing the dimensionality of the mediate vectors in the twostepped association procedure in accordance with noise condition. This minimizes the influence of noise on the associative output as long as inferiority of information will not occur. In this paper, to examine the ability of this noise attenuation method, we calculate the mean square error (that is, correctness of association or ability of noise attenuation) of association theoretically and execute the association experiment (computer simulation) using the actual image information as the memorized information. From the results, it is clear that our proposed method has high ability of association (ability of noise attenuation) compared with the conventional methods.

ISSN:8756-6621    

DOI:10.1002/ecja.4410691003

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

年代:1986

数据来源: WILEY

摘要:

AbstractIt is well known that a GT cut quartz crystal resonator coupled between two extensional mode vibrations has a cubic curve in frequency‐temperature characteristics as well as an AT cut quartz crystal resonator. This paper studies frequency‐temperature characteristics and electrical characteristics of the GT cut quartz crystal resonator with the supporting portions at both ends of the vibrational portion.First, a secular equation is derived from a vibration analysis of the resonator consisting of the vibrational portion and the supporting portions, by applying the energy method. From this secular equation, a relationship of resonant frequency, frequency temperature coefficients vs. a cut angle, a dimensional ratio and a mass ratio for the GT cut quartz crystal resonator is clarified theoretically. At the same time, from comparison of the calculated values with the experimental values, it is confirmed that they agree very well. Next, electrical characteristics of the quartz crystal resonators manufactured for trial experiments are measured. As a result, it is confirmed that a GT cut quartz crystal resonator with excellent frequency temperature characteristics, low crystal impedance and a high quality factor is reali

ISSN:8756-6621    

DOI:10.1002/ecja.4410691004

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the rational approximation of multivariable time‐invariant discrete‐time linear dynamical systems. An efficient method is developed for approximating given matrix Markov parameters (impulse response) by a low‐order rational function. This is a generalization of the approximation theory reported by Mullis and Roberts, and obtainable by extending their technique for single‐input single‐output systems to multiinput multi‐output case. The parameters of a rational function can be obtained by solving linear equations by means of a recursive algorithm. In addition, the stability of the approximating rational function is alw

ISSN:8756-6621    

DOI:10.1002/ecja.4410691005

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe quality of synthesized speech in the speech analysis‐synthesis system based on the mel‐cepstrum method is described. Mel‐cepstrum is defined as the Fourier coefficients of the log spectrum on a nonlinear frequency scale approximating the mel scale. The true mel‐log spectral envelope is estimated in this system by an improved cepstral method in the analysis part and a mel‐log spectrum approximating filter is used in the synthesis part. The preference score by pair comparison tests is used for subjective evaluation and spectral distortion on a nonlinear frequency scale is used for an objective evaluation. Using this system, 1.7 kbit/s, high‐quality synthesized speech

ISSN:8756-6621    

DOI:10.1002/ecja.4410691006

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe charge simulation method is used to obtain an approximate solution of the Laplace equation and others but it has several problems including the charge arrangement. This method determines the charge quantitites, the unknown coefficients, by satisfying the boundary values only at the constraint points arranged on the boundary. For a smooth boundary, a small number of charges suffices; however, for a complex boundary the number of constraint points must be increased to represent the boundary shape. The product paper proposes a new charge simulation method with the boundary shape taken into account by utilizing the orthogonal property of the equipotential lines and electric force lines at the constraint points in order to represent a given boundary shape. In other words, the charge quantities are determined such that not only the boundary values but also the forementioned orthogonality are satisfied at the constraint points. It is shown that in this way the boundary shape is taken into account and the error dependence on the charge arrangement as seen in the conventional method can be relaxed.

ISSN:8756-6621    

DOI:10.1002/ecja.4410691007

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe introduction of a storage function for subscribers' messages into switching systems improves serviceability, thereby enabling nonrealtime and called party oriented communication. However, the analysis method and the traffic performance of this voice message switching system, for example, the mail‐box storage system, has not been clarified yet. This paper presents the traffic design principle of the voice message switching system. The traffic analysis model of this system is proposed as a threestage serial model consisting of message writing, storing, and reading for the mailbox storage file. Next, this model is approximated to the separate model ofM/H2/S(0) loss systems and its validity is evaluated by using a simulation method, etc. Finally, some traffic characteristics of the mailbox storage file are studied by theoretical analysis and simulation method

ISSN:8756-6621    

DOI:10.1002/ecja.4410691008

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn conventional spread spectrum communication systems characterized by asynchronous multiple access SSRA (spread spectrum random access), interchannel interference is not zero and consequently the number of simultaneously communicable channels is small and the frequency utilization efficiency is low. The near‐far problem is also important. For performance improvement SSSA (spread spectrum synchronous access) systems with orthogonal sequences have been proposed. This paper discusses performance of an SSSA communication system which is based on the use of a set of orthogonal sequences formed by adding +1 to each of theM sequences. Because interference does not exist under the condition of perfect synchronism between channels, it may be expected that the multiple access capability is improved, the constraints of the nearfar problem are loosened, and the system will be immune to jamming. The performance in the absence of synchronism between channels and with imperfect demodulation of the spread code is studied by theoretical analysis and simulatio

ISSN:8756-6621    

DOI:10.1002/ecja.4410691009

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

年代:1986

数据来源: WILEY

摘要:

AbstractTraffic forecasting is used for circuit dimensioning and income prediction. Traffic forecasting in Japan has been carried out mainly by multiple regression models. However, recently, a traffic forecasting method using the Kalman filter for a state space model was proposed by David and Pack. When such a forecasting method is used, it is necessary to cope with outliers caused by various factors, such as social and/or economic factors, and observation errors. In this paper, because outliers correspond to the outliers of noises in the state space model, an algorithm for detecting and discriminating outliers by considering the noise distributions is developed. A new traffic forecasting method with a state space model including this algorithm is proposed. This method detects and discriminates changes in traffic patterns, and applies the necessary dispositions. The validity of this method is confirmed by applying it to field data.

ISSN:8756-6621    

DOI:10.1002/ecja.4410691010

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

年代:1986

数据来源: WILEY