摘要:

AbstractThis paper proposes a numerical approximation method for analyzing the steady state and the transient state of sinewave oscillator circuits. Since most oscillator circuits contain active and nonlinear elements (e.g., transistors), and inductive capacitive and by‐pass components, their circuit equations generally become high‐order nonlinear differential equations. the proposed method uses the Newton method to determine the operating point. the variation (ac component) about the operating point is used as a variable for establishing a nonlinear differential equation to be solved by means of the Krylov‐Bogolyubov‐Mitropolsky asymptotic method. the discrete Fourier transform is then applied repeatedly to obtain the second‐order approximation for the periodic solutions. the approximation method for transient solutions is also discussed. Finally, an example of a transistorized CR phase‐shift oscillator is used to demonstrate the usefulness of the proposed method. the periodic and transient solutions obtained by the proposed method are compared to those of the Runge‐Kutt

ISSN:8756-6621    

DOI:10.1002/ecja.4400670202

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

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper presents a polynomial‐time algorithm which can determine the multicommodity flows in a planar undirected graph G. It is assumed that G remains planar if an edge is added between each source‐sink pair. Given positive and real demand to each source‐sink pair, the algorithm determines whether or not there exists a multicommodity flow in G realizing the specified demand, i.e., feasibility, and if it exists, the multicommodity flow is determined. It is shown that by solving the maximum‐weight matching problem once for a graph which is a modification of the graph dual to the given graph G, the feasibility is determined, and by solving the problem for 0(kn) times, the multicommodity flows are determined. Consequently, if G has n vertices and k source‐sink pairs, the computation time required to determine the feasibility is 0(n2 log n), and the time required to determine the k‐commodity flow is 0(kn3 log n). the memory storage required is 0(kn). It is known that the maximum‐flow min‐cut theorem exists for the case of planar graph considere

ISSN:8756-6621    

DOI:10.1002/ecja.4400670203

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

年代:1984

数据来源: WILEY

摘要:

AbstractFor the purpose of extending the useful range of trapped‐energy resonators and filters up to the middle band less than a few MHz, the energy trapping of the width‐extensional vibrations in a thin piezoelectric strip is studied. Since the width‐extensional vibration exhibits a dispersion characteristic of the high‐cut type in most piezoelectric materials, the backward‐wave energy trapping needs to be applied. As realistic methods, two approaches are discussed. In one of them, the areas on both sides of the excitation part at the center of the strip are short‐circuited by the electrode. In the other method, this portion is made unpolarized. In each approach, the energy trapping of the width‐extensional vibration is realized if the electrode in the excitation part is made a partial electrode with its width narrower than the strip width. A clean resonant response with few unwanted modes is obtained. A method for fabrication and experimental results are reported for a ladder filter and a single‐mode three‐terminal filter. Effectiveness of this device for a filter in the middle

ISSN:8756-6621    

DOI:10.1002/ecja.4400670204

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

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper discusses the measurement results obtained with regard to atmospheric attenuation at 35 GHz using a sun tracker. the measurements are intended to provide an understanding of the atmospheric aborption attenuation characteristics of millimeter waves on high‐angle propagation paths. We first provide a simple description of the construction and performance of the sun tracker and then discusses the method of measuring atmospheric attenuation by means of solar radio observation. the annual, seasonal and monthly variability of measured atmospheric attenuation at 35 GHz are then clarified based on statistical analysis of measured data covering a period of nearly 5‐1/2 years. Regression analysis is performed on the relationship between the measured atmospheric attenuation and the surface meteorological data. Linear regression expressions are derived with respect to the surface vapor levels, and multiple regression equations are derived for the relationship between the surface vapor content and the oxygen content corresponding to the surface meteorological data. Using those equations, a study is made of the estimation precision that can be achieved in estimating atmospheric attenuation from surface meteorological data. Finally, a comparison is made between the measured attenuation and the calculated attenuations using aerological data in the theoretical equations of Bean et al., which are widely used in Ja

ISSN:8756-6621    

DOI:10.1002/ecja.4400670205

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

年代:1984

数据来源: WILEY

摘要:

AbstractMultiple scattering phenomena have been analyzed via analysis of scattering by several circular cylinders. However, most of these works treat only the far field for the cases where the cylinder radius is much smaller than the wavelength and the cylinder separation is much larger than the radius. In this paper, the effect of the multiple scattering on the near and far fields is studied when perfectly conducting circular cylinders with radius comparable to the wavelengths are placed at separations comparable to the radii. the analysis is based on the simulated charge method because it provides accurate solutions within a reasonable computational time. the following results have been obtained. the errors of the simulated charge method increase as the cylinder separations are reduced due to the effect of multiple scattering. the multiple scattering effect increases with the number of cylinders and it appears significantly in the scattering cross section. the scattering pattern receives a negligible effect of the cylinders in the shadow region for the incident wave. the direction of the lobe deviates from that expected from the first‐order approximation, neglecting the multiple scattering due to the effect of multiple scattering. the near field is affected only by the cylinders within the visible region from the observation point and receives a negligible effect from other cylinder

ISSN:8756-6621    

DOI:10.1002/ecja.4400670206

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

年代:1984

数据来源: WILEY

摘要:

AbstractA differential coding method regards the transmission line code as a kind of state and assigns the original codeword to each state transition. This method is used widely to regenerate the original codeword as an invariant for the state transition even if there exists state ambiguity during transmission. This paper derives a differential coding theorem as the necessary and sufficient condition for the existence of a differential code on the basis of the mathematical formulation of differential coding problems. According to the theorem, the necessary and sufficient condition for the existence of a differential code is that the set of ambiguity operators should be an irreducible and nonseparable group Gσ, and that a stationary successive operator, which is antihomomorphism on Gσ, should exist. the importance of the theorem is demonstrated through the differential coding for the staggered QAM transmission system, which has been considered difficult to code differentially. Since the theorem is derived under some general conditions, it is applicable to a variety of differential coding problems which may appear in the futur

ISSN:8756-6621    

DOI:10.1002/ecja.4400670207

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

年代:1984

数据来源: WILEY

摘要:

AbstractIt is proposed that electric charge stored in unscanned areas on the field of a high resolution camera tube can be removed by an electron beam with an elliptic cross section which is formed by a beam‐limiting aperture, or by applying vertical rf electric field on the beam, which is called wobbling. These effects have been discussed analytically. the beam‐limiting aperture is applicable to a magnetic focusing and deflecting tube in which, however, the beam spot direction differs slightly from point to point on the picture area; it is applicable also to an electrostatic focusing, magnetic deflecting tube which has rather poor resolution but in which the spot direction is independent of the position on the picture area. On the other hand, wobbling is applicable to a magnetic focusing, electrostatic deflecting t

ISSN:8756-6621    

DOI:10.1002/ecja.4400670208

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

年代:1984

数据来源: WILEY

摘要:

AbstractWe have developed an LSI especially suited to process image signals (Image Signal Processor (ISP)). It can process signals of a gray‐scale image having 256 levels as rapidly as TV images are scanned. the device features a kernel size which can easily be extended by either of two methods. the extension method adds ISPs like building blocks. For example, using four ISPs, a 4 × 4 spatial convolution for reconstruction of a gray‐scale image composed of 256 × 256 pixels takes 10.9 ms; the second method adopts our newly proposed image scanning system, the stick scanning system. This enables one ISP to execute a 4 × 4 spatial convolution. In addition, various image processing operations can be done by changing the contents of the programmable control registers within the ISP.Our ISP is fabricated using 3 μm CMOS technology and comprises about 61,000 transistors. the chip is 7.72 × 8.64 mm in size and is mounted in a 64

ISSN:8756-6621    

DOI:10.1002/ecja.4400670209

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

年代:1984

数据来源: WILEY

摘要:

AbstractScaling down of solid state devices is indispensable for large‐scale integration of circuits. Understanding the characteristic tendency and the limitation of the scaling down provides a useful guideline in recent scaling‐down efforts. This paper discusses scaling down of bipolar transistors, especially the I2L, for which little has been reported. the collector dimension of the I2L is chosen as the scale‐down parameter. Important characteristics such as the current gain, capacitance and delay time are studied by similarly reducing the device with an identical shape from 5 μm to 0.5 μm. In the analysis, the bandgap narrowing effect and the Auger recombination are considered and the two‐dimensional computer simulation program CADDET‐B is used. It is expected that the minimum delay time is reduced to about 200 ps and the power dissipation‐delay time product is improved to about 3 fJ when the collector dimension is scaled d

ISSN:8756-6621    

DOI:10.1002/ecja.4400670210

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe feedback circuit for stabilizing an avalanche electron injection current is controlled digitally, and its algorithm has been developed. the injection current can reach within 1% of the target value in a few minutes. the C‐V characteristics are measured during measurement of the injection current, and the data are stored on a mini‐floppy disk. A new method has been proposed for evaluating the area density of traps, in which a continuous distribution of the cross section has been assumed; reliability of the result is also estimated. It is noted that the cross section and the area density of types cannot be determined simultaneously, and hence the resolution must be predecided according to the purpose of the experim

ISSN:8756-6621    

DOI:10.1002/ecja.4400670211

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

年代:1984

数据来源: WILEY