摘要:

AbstractThis paper proposes a method for analyzing the transient and steady states of a sine wave oscillator circuit with reactive elements which have large differences in their values. These reactive elements can be divided broadly into three categories: elements for determining the frequency of the oscillation; very small elements such as stray capacitors in the transistor; and very large elements such as by‐pass capacitors. The circuit equation is represented by an autonomous nonlinear differential equation with the values of these elements. There are remarkable differences in magnitude between the eigenvalues of the linear parts of the equation. In this paper, first, we describe the method for solving numerically the differential equation regardless of the stiffness by the asymptotic method developed by Krylov, Bogolyubov and Mitropolskiy. Second, we present the method for obtaining solutions of the differential equation with regard to the stiffness by combining the asymptotic method with numerical integration. Especially, when we obtain the transient solution, we demonstrate that the application of the interpolation method to the asymptotic method reduces the computing time considerably. As examples, we consider the CR sine wave oscillator circuit using the Ebers–Moll model of transist

ISSN:8756-6621    

DOI:10.1002/ecja.4410701001

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper deals with a design of digital transmitter and receiver IIR Nyquist low‐pass filter pairs for data transmission. The transmitter and receiver filters are required to limit the spectrum bandwidth of a transmitting signal and a received signal, respectively, and to have zero intersymbol interference when the filters operate in a cascade. Due to the bandlimiting requirements, the sampling frequencyFs= 1/Tsfor the filters must be larger than twice the data transmission rate 1/T.This paper supposes the receiver filter followed by the time domain equalizer. The filter design proceeds as follows: first, the transmitter and receiver filters are designed to have the same transfer function with a stopband equiripple attenuation, considering the amplitude characteristics only. The filter transfer function is designed by usings–ztransformation of the known analog elliptic filter, realizing the transition band characteristics with the preassigned roll‐off factor. The method does not require any iterative approximation. Secondly, the output of the receiver filter is decimated to the data symbol repetition rateT, then equalized in the time domain. The time domain equalizer consists of a linear or a decision feedback circuit, using an MS adaptive algorithm. The amount of delay given to the training signal supplied to the equalizer affects the residual errors. Let the order of the equalizer (numerator and denominator has the same order) denoted byn.Then an optimum delay is found to be equal tonTfor the linear feedback circuit and (n/2)Tfor the decision feedback ci

ISSN:8756-6621    

DOI:10.1002/ecja.4410701002

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

年代:1987

数据来源: WILEY

摘要:

AbstractAssume a situation in which a block is required to change its relative position at the step where placement and routing in the VLSI layout design has been completed. We formulate a problem of minimizing the number of steps for modification, assuming that we need a step of one unit for rerouting one channel. Then we obtain a solution. For routing, we assume a channel routing style performed channel by channel on the grid determined by a design rule, and that a block movement is required by such slight increase of the width that a new wiring requirement is generated between blocks. The problem is reduced to that of finding anA‐confluent cut with total minimum weights for an arbitrarily specified edge setAin a directed graph with weighted edges. By anA‐confluent cut we mean a cut such that the orientation of each constituent edge is the same with respect to edges inA.Although it is a fundamental notion in graph theory, it appears to have been given little considerat

ISSN:8756-6621    

DOI:10.1002/ecja.4410701003

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

年代:1987

数据来源: WILEY

摘要:

AbstractNumerous works have been reported on the facility location problem to minimize or maximize various objective functions for the locations of one or more facilities on graphs. A general approach to these problems is algorithmic, but solutions are seldom found in an explicit manner. By restricting the object graph to grid graphs, this paper gives solutions in an explicit manner to the center problem and the median problem which are fundamental in facility location problems.Strictly speaking: (i) we derive the relationship between the center and median of general graphsG1andG2and the center and median of the product graphG1xG2; then (ii) we find a multicenter and multimedian of the path graphPnonnvertices and from the results, solve a kind of multicenter and multimedian problem for grid graphs; and (iii) we solve a distance minimization problem on grid graphs.

ISSN:8756-6621    

DOI:10.1002/ecja.4410701004

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

年代:1987

数据来源: WILEY

摘要:

AbstractAs lower‐order approximation methods for discrete‐time linear systems, Mullis and Roberts have proposed two methods: the so‐called modified least‐square approximation (MLSA), and the interpolatory approximation (IA). The characteristics of the two methods were investigated considering their relationships. In this paper, a lower‐order approximation method for continuous‐time linear systems is presented in a form corresponding to MLSA, with its property, algorithm and state‐space representation discussed in correspondence with the discrete‐time case. The approximation can also be regarded as corresponding to IA, and thus the proposed method is called the continuous‐time Mullis‐Roberts‐type approximation (CMRA). The latter half of this paper presents a formulation for the limiting case (as sampling time ← 0) from a lower‐order approximation method for discrete‐time systems to one for continuous‐time systems. Thus it is shown that CMRA is obtained as a common limit of MLSA and LA, thereby providing a physical interpretation to the formal correspond

ISSN:8756-6621    

DOI:10.1002/ecja.4410701005

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe time‐series analysis (called indirect method) based on the Perron‐Frobenius operator is well known as a theoretical method which can determine the statistics for various chaos in one‐dimensional distance dynamical systems without determining the trajectory. However, it is rare that a strict solution for the statistic can be determined explicitly and consequently, the indirect method is not practical at present. To remedy this situation, previously we proposed an indirect method based on Galerkin's approximation to the operator, and verified its usefulness. However, the method was not effective for the intermittent chaos with 1/fpower spectrum. This paper extends the indirect method using Galerkin's method by introducing the singular function in the approximation to the unbounded invariant density. As a result, the power spectrum is obtained which agrees fairly well with the data calculated directly from the trajectory over a wide frequency range. An interesting result was obtained by the recent study wherein the spectrum of the intermittent chaos has the form of 1/fδin the limit of zero frequency, where the exponent δ is related explicitly to the nonlinearity of the one‐dimensional discrete dynamical system. However, the forementioned result refers only to the spectrum of the chaos in the limit. By contrast, the proposed method can serve as a practical method to estimate the power spectrum of 1/fnoise over a w

ISSN:8756-6621    

DOI:10.1002/ecja.4410701006

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

年代:1987

数据来源: WILEY

摘要:

AbstractTheoretical and experimental studies are made on an antenna mounted on the roof of an automobile. The theoretical model of an automobile body and a calculation technique based on GTD are developed to calculate the input impedance and vertical plane patterns of a quarter‐wavelength monopole in the 300–900 MHz band. The theoretical model consists of three perfectly conducting plates. From a comparison of calculated and measured results it is seen that the effect of the body and the earth can be examined well with the theoretical model. The results of the pattern calculation show that the radiation patterns depend largely on the configuration of the automobile b

ISSN:8756-6621    

DOI:10.1002/ecja.4410701007

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn integrated digital pair‐loop network with ring topology of optical fiber cables as a new type of communication systems for interoffice trunk networks in regional service areas is proposed. The pairloop network has a feature in that several switching offices share bidirectional transmission channels, and thus the channels can be utilized in common by several trunk groups of offices belonging to the system. However, if vacant channels are selected arbitrarily and assigned to any calls, blocking probability depends on the office location and a definite grade of service can not be expected. This paper shows that the channel assignment following an algorithm called the channel‐pair selection rule makes it possible for the trunk group to achieve a definite grade of service and improves channel efficiency. It is shown also that analytical results are in good agreement with simulation resu

ISSN:8756-6621    

DOI:10.1002/ecja.4410701008

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe stored‐program control system presently forms the main‐stream of the switching control system because of the flexibility in function modifications, compared with the wired‐logic hardware. One of the problems which has manifested recently is the large number of steps of the software modifications, which accompany with the modifications of the switching system architecture and the additions of functions. One of the major reasons for the large number of modification steps is the traditional modularisation, where the switching system architecture and the signaling systems are assumed to be retained. Because of this assumption, the modifications have to be made at various scattered points in the software systems, or have to be made at unexpected points, thereby increasing the number of steps in the modifications. This paper aims at improving the versatility of the software, and describes the modular breakdown, where the modification is localized by making the switching system architecture and the signaling system implicit and virtualized. By the same idea as in the hardware architecture, the software component technique is realized, where the program‐unit is subdivided into a set of units depending on the starting conditions of the programs and a set of units not depending on the starting conditions, and the module is composed by combining those two sets of units. By an example, it is shown that the proposed software architecture is

ISSN:8756-6621    

DOI:10.1002/ecja.4410701009

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn the field of mobile communication, the transmission of picture and data signals in addition to conventional speech transmission requires modulators that are suitable to both analog and digital FM. In the present paper such a quadrature modulator is proposed which provides stable transmission characteristics by digital signal processing (DSP) techniques. The analysis is mainly aimed at additional noise effects due to the digital generation of analog FM signals.The relations between the sampling frequency used in the D‐A conversion of analog speech signals and the sideband noises accompanying modulation are developed. The relations are given between the number of bits used for quantization in the A‐D conversion and the baseband signal/noise ratio in the case of FM or PM reception of the analog FM wave generated by the proposed modulator.Based on the results of this analysis, a modulator design method providing sufficiently high noise suppression is presented in a flowchart form. The results of measurement of a quadrature modulator realized by the proposed method are shown to agree well with the results of analysis. The agreement demonstrates that the required modulator characteristics can be obtained without tun

ISSN:8756-6621    

DOI:10.1002/ecja.4410701010

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

年代:1987

数据来源: WILEY