摘要:

AbstractFor fundamental research on image filtering, spectral estimation, identification, coding etc., it is beneficial to use a digital computer to generate a random image satisfying a given statistical property. The present paper defines random image as a random field satisfying a stochastic difference equation. The image is linearly syhthesized from a white‐noise field, namely, a series of independent random numbers. In terms of the 2‐dimensional prediction theory a detailed method to determine the 2‐dimensional autoregressive representation for the random field is given. Next, a hybrid method is given which uses Fourier transform in one dimension and 1‐dimensional prediction theory in the other dimension. The method of Green function is given for a special application, and a method which uses 2‐dimensional Fourier transform is described briefly. A concrete calculation is given using the cross‐type partial difference equation for the random field with an isotropic spectrum. Comparison of these four methods shows that there is little difference in the number of multiplications in the processing. However, the first method aids in generation of a large image by a computer with s

ISSN:8756-6621    

DOI:10.1002/ecja.4410650502

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

年代:1982

数据来源: WILEY

摘要:

AbstractAs the first step to detect laryngeal cancer by acoustic means (especially cancer of the vocal chords), this paper analyzes the pitch period perturbation quotient (PPQ), pitch amplitude perturbation quotient (APQ) and pitch correlation amplitude (PA) measure, from the outer‐tracheal waves. The results are compared with the result of TNM classification, which is widely used as a clinical classification. The 49 samples were examinees, in which normals were 16 and patients with laryngeal cancer were 15. Among the 15 patients with laryngeal cancer, 14 had cancer of the vocal chords. As the result of analysis, the following conclusions were made. (1) Both PPQ and APQ exhibit correlations with TNM classification, but APQ will be more effective in the detection of cancer of the vocal chords. (2) PA is not very effective in detection at an early stage (T1). (3) Pathologically developed vocal chord cancer (T2) can completely be detected. (4) If allowance is made for 37.5% (6/16) of false positive for the normal, 92.9% (13/14) of the vocal chord cancer can correctly be detecte

ISSN:8756-6621    

DOI:10.1002/ecja.4410650503

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe problem of providing the required numbers riof paths between specified q pairs of sources siand sinks ti(i = 1, 2,…, q) in a graph with edges having capacities which limit the numbers of their usages is called the realization problem of multi‐source‐sink pair connection in a network. Since this is an NP‐hard problem there are no suitable heuristic algorithms to solve it; however, it has a wide range of applications. This paper presents a heuristic algorithm based on Onaga's necessary and sufficient condition (called supply‐consumption inequality). Its effectiveness is examined by measuring its speed and accuracy with computational experiments. The connection time per a connection was proportional to the number of nodes of a graph (≦ 132) and accuracy was mo

ISSN:8756-6621    

DOI:10.1002/ecja.4410650504

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe relation between spectral distortion and the quality of synthesized speech in a speech analysis‐synthesis system based on the cepstrum method (cepstral vocoder) is described. In this system, the true logarithmic spectral envelope is estimated by an improved cepstral method in the analysis part and a logarithmic amplitude characteristic approximated filter is used in the synthesis part. The transmission rate for spectral information is reduced using the differential of the cepstrum due to the differential of the spectral envelope, because the spectra do not change very rapidly. The preference score by pair comparison tests is employed as a subjective evaluation and spectral distortion is used as an objective evaluation to establish the relations among the quantization width, word length, frame rate, cepstrum order, spectral distortion and synthesized speech quality. Furthermore, the factors of spectral distortion and its characteristics are clarified and it is shown that spectral distortion can be estimated from the transmission condition. The result is that 2.8‐kbit/s, high‐quality synthesized speech can be obtained by this synthesis s

ISSN:8756-6621    

DOI:10.1002/ecja.4410650505

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

年代:1982

数据来源: WILEY

摘要:

AbstractIt is possible to detect the point of breakdown and to obtain the loss of optical fibers by measuring the backscattered light caused by Rayleigh scattering. This paper describes design and test results for a small, light‐weight, high‐performance optical time‐domain reflectometer. To obtain masking functions for excessive pulses such as those obtained by Fresnel reflection, we use an image dissector as the detector and obtain a 50‐dB masking attenuation. A digital averager is used to improve the S/N ratio. The time required for 1000 averagings is only 40 seconds. To prevent drift, an AC coupled amplifier and a zero‐level sampling system are used and sufficient temperature stability is realized. The experimental reflectometer is able to detect the breakdown point as far away as 8 km with backscattered light and at 14 km with perfect end Fresnel reflection. The error in the loss measurement is less than 0.05 dB for the distances up to 4 km. From these results, the tested reflectometer is found usable in

ISSN:8756-6621    

DOI:10.1002/ecja.4410650506

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

年代:1982

数据来源: WILEY

摘要:

AbstractOne of the important problems in the design of switching systems is to arrive at a switching network with high efficiency. In order to obtain a switching network satisfying economical requirement for the total switching system including the processing devices, the system must be evaluated from the viewpoint of the amount of processing in path‐hunting, as well as traffic efficiency and hardware cost. From such a viewpoint, the authors conducted evaluations based largely on simulation of the path‐hunting processing in the switching network. However, since simulation involves practical difficulties in the evaluation of a large‐scale switching network, a simple and theoretical method is desired to evaluate the amount of processing in path‐hunting. This paper presents a theoretical method of evaluation for the homing‐type path‐hunting system, which is superior from the viewpoint of blocking probability and the amount of processing. The effectiveness of the proposed method is demonstrated. Using the proposed method, the relation between the path‐hunting scheme and the blocking probability is derived and actual large‐scale T‐S‐T switching networks are evaluated from the viewpoint of the amount of processing in path‐hunting. The result of evaluation indicates that a switching network with higher traffic efficiency tends to require a larger amount of processing in a large‐scale switching network as well. The optimum switching network type is indicated, considering the amount of pro

ISSN:8756-6621    

DOI:10.1002/ecja.4410650507

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn the phased array system, excitation amplitudes and phases based on the design are specified for each antenna element in order to synthesize desired beam scannings and radiation patterns. However, due to fluctuations of antenna and feed network characteristics, the amplitude and phase of each antenna element deviate from the desired values. To correct these deviations, the amplitude and phase of each antenna element must be accurately measured under specific operating conditions. In this paper, we employ variable phase shifters connected to the antenna elements and measure only the amplitude variation of the composite electric field of the entire array when the phase of each element is modified. The rotating element electric field vector method in which the measured amplitude variation is numerically processed for obtaining the amplitude and phase of the particular element is theoretically discussed and experimentally tested for its usefulness. The present method can be easily attained by simply adding software to the computer‐controlled phased array syste

ISSN:8756-6621    

DOI:10.1002/ecja.4410650508

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe error extension of 4B‐3T code causes some problems to destuff error of the stuff indicating pulses. This paper investigates the characteristics of error extension associated with 4B‐3T code transmission, and proposes a method to eliminate the adverse effects of the error. Involved are the interlease and rearrangement of the stuff indicators, pulses in the binary code before conversion to ternary code. The optimum conversion method is described. An experimental 4B‐3T code transmission system is constructed to evaluate the characteristics of error extension and destuff error. Further, this system demonstrates that the proposed 16 bits interleave method results in a destuff error rate comparable to that of the AMI transmission method and only a few hundredth of that of the conventional 4B‐3T code transmission without int

ISSN:8756-6621    

DOI:10.1002/ecja.4410650509

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

年代:1982

数据来源: WILEY

摘要:

AbstractAmong the principal approaches to electromagnetic field analysis in an homogeneous medium are numerical methods. The homogeneous multilayer approximation used in numerical methods is invalid when there is wave equation singularity. This paper demonstrates that the finite difference method is equivalent to the homogeneous multilayer approximation methods when the number of subdivision is increased; further, it is shown that finite difference methods also can be invalid. To analyze electromagnetic fields in the medium for which the wave equation contains a singularity, we propose here an inhomogeneous multilayer approximation method (a piecewise linear approximation) based on the power series solutions. A technique is presented for improving the homogeneous multilayer approximation method and the finite difference method by using the results of piecewise linear approximations. We further propose a modified multilayer approximation method by combining advantages of various methods. The principal features of the modified multilayer approximation method are as follows: 1) Calculations are possible even when the wave equation has several singularities; 2) the method is applicable to the structure with arbitrary medium profile; 3) the solution near the singularities can be obtained relatively easily; 4) a desired degree of accuracy can be obtained by increasing the number of subsections; and 5) no extensive mathematical background is required.The modified multilayer approximation method is used to analyze the reflection of a plane wave from an inhomogeneous plasma slab. Presented in graphical manner are the power reflection coefficient, the energy absorption, the electromagnetic field distribution inside the slab and the power flow.

ISSN:8756-6621    

DOI:10.1002/ecja.4410650510

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

年代:1982

数据来源: WILEY

摘要:

AbstractFor high‐speed facsimile with redundant supression code, the intermittent variable scanning system has traditionally been used, accompanied by the start/stop function for the vertical scanning. However, the system requires a certain settling time in stopping and a limitation is imposed on the speed when the vertical scanning mechanism is heavily loaded. From such a viewpoint, this paper proposes a nonstop vertical scanning system, which realizes a smooth vertical scanning operation without stopping the vertical scanning. In the proposed system, the vertical scanning speed is predetermined in N steps and, by comparing the stored bits in buffer memory and threshold values for the buffer memory, the vertical scanning speed is determined as the same as the previous one or one step faster or slower. By this elaboration, a high‐speed system can be realized even when the load is heavy, at the same time achieving low‐noise operation. In the present system, however, selection of the vertical scanning speed is limited to one of three, which prevents the system from complete follow‐up change in the code information, necessitating a line memory and buffer memory. This paper first describes the design method and control scheme for the vertical scanning speed and then presents the result of calculation and computer simulation for the relation between various parameters and the memory capacity. The effectiveness of the proposed system is verified by an implementation. The memory capacity is evaluated at the same time, comparing the capacities of the two kinds of m

ISSN:8756-6621    

DOI:10.1002/ecja.4410650511

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

年代:1982

数据来源: WILEY