摘要:

AbstractFor a switching system which must operate 24 hours a day with high reliability, the requirements are secure recovery from a fault and minimization of the effect of the fault recovery (i.e., system down time). On the other hand, when a multiprocessor system is employed, competition may be produced among processors, leading to complex and difficult problems in the fault recovery. Several techniques are shown in this paper concerning the following points: (1) local fault processing in the unit processor; (2) the upper‐level fault processing, realized by combining the local fault processing; and (3) improvement of reliability of the fault recovery by a hierarchical monitoring of the overall system. With regard to the effect of the fault recovery, the factors affecting the down time are analyzed. The relations among those factors, the performance of the processor, and the fault rate are modeled. The effect of the fault recovery is compared between the proposed system and the existing single‐processor control system. As the result of comparison, it is shown that the proposed multiprocessor control system can localize the effect of the fault, and is more desirable than the traditional single‐processor control s

ISSN:8756-6621    

DOI:10.1002/ecja.4410720601

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the diffraction region of a microwave landing system (MLS) elevation guidance, the field strength fluctuates due to such objects as buildings and hence the measuring error increases. This paper describes experiments to determine the effect of diffraction caused by the upper edges of a building. The results show that the field has a typical diffraction characteristic which can be calculated by regarding the building as a knife edge. It was found that the diffraction error cannot be ignored when measuring an angle, since the scanning beam is sharp in the vertical direction and flat in the horizontal direction. Hence, both the component proportional to the amplitude of the diffraction wave and that proportional to the partial differentiation of its incident angle (slope diffraction component) increase. It was found also that the measurement error characteristic around the shadow boundary, calculated by using the uniform geometrical theory of diffraction taking account of the slope diffraction, agrees well with the observational results. Generally, this method can be applied to the diffraction field strength and its measuring error estimation such as hangers.

ISSN:8756-6621    

DOI:10.1002/ecja.4410720602

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe metallic subscriber line is composed of the cascade connection of cables with different core radius and the openended branch line called bridge‐tap. Previously, the line equalizer for such a line has been constructed by combining thefequalizer, which has the equalization function for the single core cable, and the DFE circuit. The DFE circuit has a structure suited to LSI implementation, but has a problem in that a decision error propagates to succeeding bits, since the result of the decision is fed back as the compensation waveform for the intersymbol interference. This paper proposes a line equalizer based on the DFE circuit, which includes the DFE pre‐equalizer to stabilize the DFE circuit. The design principle is presented. More precisely, the error propagation in the DFE circuit is analyzed. Combined with the analysis of the subscriber line characteristics, the required characteristics for the DFE equalizer are shown. Then a discussion is made on the number of taps in the DFE circuit, which determines the scale of the DFE circuit. Finally, a design example is presented for 320 kbit/s TCM transmission‐line equalizer based on the design method presented. By experiment, the desired characteristics are ver

ISSN:8756-6621    

DOI:10.1002/ecja.4410720603

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

年代:1989

数据来源: WILEY

摘要:

AbstractIt is possible to employ nonmetallic optical cables in regions with strong electromagnetic disturbances such as the vicinity of railroads, etc. However, the method to evaluate the reliability of the strength members of FRP in these cables is not yet known. In this paper, experimental investigations are carried out on bending strain characteristics, which is the main problem in reliability of FRPs. The method to estimate the lifetime of FRP with known temperature and humidity conditions and under fixed bending radius is described. Next, using this method, experiments on evaluation of FRPs with different comprising materials are carried out. It is indicated that there is a remarkable improvement in reliability by using glass fibers of high strength which are very suitable to be used as highly reliable FRPs in optical cables. As the result, it is shown that by using these FRPs in optical cables, the allowable bending radius of the optical cable is reduced by the factor of one‐half and the modulus of elasticity of the optical cable is increased by a factor of 1.4, compared to the optical cables with previous FRP

ISSN:8756-6621    

DOI:10.1002/ecja.4410720604

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the design of a radio link for terrestrial mobile communication, the transmitter power and the cluster size are determined based on the specification derived from the quality requirement and the outage. In the traditional design, the required quality and the outage are allocated according to the two degrading factors, i.e., the noise and the co‐channel interference, and the transmitter power and the cluster size are determined independently. The method is employed widely because of its simplicity, even though there is a certain error in the designed values. By contrast, this paper proposes an exact design for the radio link, where the reliability of the designed value is emphasized, aiming at a more efficient utilization of the frequencies. The concept of the prescribed quality transmission curve which considers simultaneously the two degrading factors, is newly introduced. The expression for the outage is derived from the prescribed transmission quality curve and the joint probability of the carrier‐to‐noise power ratio (CNR) and the carrier‐to‐interference power ratio (CIR). The relations among the outage, transmitter power and the cluster size are determined. As a precise method of calculation, a method is presented which gives the graphical relation between the transmitter power and the outage, with the cluster size as the parameter. Using a design example, it is shown that the minimum cluster size, which has been 12 in the traditional method, is now 9 by the proposed method. Thus, the usefulness of the method in the frequency utilization is

ISSN:8756-6621    

DOI:10.1002/ecja.4410720605

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

年代:1989

数据来源: WILEY

摘要:

AbstractOne of the factors determining the performance of the digital radio‐relay system is the interference from the existing FDM‐FM systems. Traditionally, the FDM‐FM interference characteristics have been evaluated by analyzing the effect on the error rate by the interference wave which is approximated by a sinusoidal wave. The method tends to underestimate the effect on the error rate in a digital system when the analysis is compared with the case where an interference wave is actually given. This paper proposes a method for evaluation in which the FDM‐FM interference wave is divided into the carrier and the sideband components. Based on the new method, the interference characteristics have been analyzed. It is found from a laboratory experiment that the present evaluation method i

ISSN:8756-6621    

DOI:10.1002/ecja.4410720606

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe malfunction of a digital circuit has been investigated from the viewpoint of the IC as its constituent. However, little has been reported from the viewpoint of electrical contact which is one of the principal causes of the malfunction. In the research reported here, simple automatic measurement equipment has been developed which counts the malfunctions of a digital circuit. Measurement has been done with this equipment under various circuit conditions. As a result, it was found that malfunctions of digital circuits not only increase with the load circuit current, but may decrease when the circuit current exceeds a certain value depending on the parallel capacitance between contacts. As the parallel capacitance between contacts increases, the region in which malfunctions are likely to occur shifts toward a larger current side. It was found that these elements are related closely to the region of showering arc generation which is one of the discharge modes at the time electrical contacts open. Also, since the parallel capacitance between contacts is larger, the 0 percent malfunction rate is approached while the wiring spacing between the inductive and induced wires is closer. For this characteristic, the frequency spectrum of the dielectric breakdown region of the showering arc voltage waveform has been derived.

ISSN:8756-6621    

DOI:10.1002/ecja.4410720607

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

年代:1989

数据来源: WILEY

摘要:

AbstractA layered free access network is proposed. This network is composed of multichannel circuits of bus type, such as LAN, satellite channel, etc., and traffic nodes which access multichannel circuits. By combining the nodes which can access all circuits and the circuits used only by a part of the nodes, a layered network structure can be constructed in accordance with the internode traffic distribution pattern. The number of access equipment in a node is evaluated and the existence of the optimum network configuration for an internode traffic distribution pattern is shown. An algorithm for obtaining the optimum network configuration is presented and an example of the optimum network configuration based on the traffic model is shown.

ISSN:8756-6621    

DOI:10.1002/ecja.4410720608

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper considers the highly efficient coding of the gray‐level image. The extrapolative prediction‐discrete sine transform scheme, which was previously proposed by the authors for the case of one‐dimensional coding, is extended to the case of two‐dimensional coding. In the proposed method, the image is partitioned into square blocks. The correlations among blocks are eliminated by applying the two‐dimensional extrapolative prediction for each block from the restored boundary pixel. The correla‐in the block is eliminated by applying the orthogonal transformation to the prediction errors. In this paper, the correlation function of the image is assumed as the isotropic exponential function, and a two‐dimensional extrapolative prediction method is derived, which can be realized as a simple manipulation. The transformation of the prediction errors is performed by the variable‐separation type two‐dimensional extrapolative prediction‐discrete sine transform, where the one‐dimensional extrapolative prediction‐discrete sine transform is applied to rows and columns. Then the rate‐distortion characteristic is calculated, indicating that the proposed method is useful. It is shown that the proposed method with 4 × 4 block size has almost the same coding efficiency as the discrete cosine transform coding with 16 × 16 block size. A computer simulation was made for the actual image, leading to a result validating the theoretical estimation. The proposed method requires less computation per pixel, compared with the discrete cosine transform coding. The method is especially useful from the viewpoint of hardware implementation, since the blo

ISSN:8756-6621    

DOI:10.1002/ecja.4410720609

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper discusses the flexibility of a cable when it is bent to the range of plastic deformation of the cable material. Considering the situation where the cable material exhibits elastic or plastic deformation, the expression for the maximum bending moment, which represents the flexibility of the cable, is derived in terms of the following parameters: The strain‐hardening exponentnand the plastic modulus which are material parameters; and the outside and the inside radiir1andr2, respectively, which are the structural parameters. As a method to determine the foregoing material parameters experimentally, the three‐point bending test is discussed. A method is presented which determines the strain‐hardening exponentnand the plastic modulus from the relation between the loadPand flexion δ. The method is verified experimentally. The case is considered where the cable is composed of several materials such as sheath, core, and tension member, and it is demonstrated that the bending moment of the whole cable is given as a sum of the bending moments of the component materials. Thus, it is shown that if the material parameters of the cable components are known, the maximum bending moment of the whole cable, representing the flexibility, can easily be de

ISSN:8756-6621    

DOI:10.1002/ecja.4410720610

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

年代:1989

数据来源: WILEY