bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of microwave amplifier or frequency multiplier tube with a multipactor electron gun
Authors: Yokoo Kuniyoshi , Ono Shoichi , Tai Don Zhe 
Published: July 2007

AbstractThe electron beam emitted from a so‐called multipactor cathode operated on the basis of the multipactor effect forms narrow pulses repeated at an RF frequency identical to that of the signal driving the cathode. By accelerating the beam, one can create a high‐efficiency microwave tube for amplification and multiplication having a simple construction without the velocity modulation required of a dc electron beam in such a tube as a multicavity klystron. This paper describes a simulation study of a multipactor cathode and the acceleration region of the electron beam. the study provides a guideline for an expected dynamic operation. the conversion efficiencies from the dc input power to the fundamental wave and the second and third harmonics are expected to be as high as 86%, 56% and 31%.
Effects of desired signal arrival angle errors on the steady‐state performance of a howells‐applebaum adaptive array
Authors: Ohmiya Manabu , Ogawa Yasutaka , Itoh Kiyohiko 
Published: July 2007

AbstractWhen a Howells‐Applebaum adaptive array is used in a communication system, the receiving side must know the frequency and arrival angle of the desired signal. However, it is often impractical to assume that the arrival angle is accurately known. It is of importance to determine the degradation of output characteristics due to the angular error in arrival angle of the desired signal. This paper first presents a theoretical analysis of the steady‐state performance of the array when only the desired signal exists and angular error is contained in it. A condition is found under which the desired SNR is obtainable from the angle error profile. A formula is derived by which the upper limit of the amplifier gain or the allowable upper limit in the angle error is obtained. These limits are important criteria in the array design. Some numerical calculations are conducted for angle error characteristics in the presence of interference and the effectiveness of the derived design criteria. It is found that these criteria are sufficiently useful if the amplifier gain g normalized by the thermal noise power is larger than unity or if for a small g the interference power is reasonably large. This is because the angle error characteristics are better than those in the absence of interference.
The number of dichotomies and the separating capacity of a set of parallel hyperplanes–The information processing capability of the multithreshold threshold elements
Authors: Takiyama Ryuzo 
Published: July 2007

AbstractTo represent the intrinsic information processing capability of the learning machine or the pattern classification system, Cover [1] has defined the separating capacity, and calculated it for the linear machine and the so‐called ψ machine. In this paper the separating capacity of a pattern classification system by a multi‐threshold threshold element is obtained. It is shown that the capacity of a multithreshold threshold element with k thresholds in n dimensional space is 2(n + k). A linear machine is a special case of such a threshold element with k = 1; therefore, its capacity becomes 2(m + 1). Although it is intuitively apparent that the larger the number of thresholds, the more powerful the k‐threshold element is in information processing, this is interpreted to mean that the capacity of the k‐threshold element increases linearly with respect to the number k.
On a preprocess to facsimile transmission code for rejection of isolated background noise and notches in images
Authors: Hosaka Kenichi , Tominaga Hideyoshi 
Published: July 2007

AbstractMost digital facsimile scanners scan the input documents and generate black and white pixels by thresholding. This process often creates isolated background noise and notches on the edges of contour lines. In addition to the degradation in image quality, the noise and notches tend to decrease the efficiency of the encoding scheme. This paper utilizes the notion of rectangular points on a C‐dot pattern to remove isolated background noise and notches. the relationship between the rectangular points and the original image is investigated. Experiments are conducted which show a reduction of about 10% in the number of bits needed to represent the raster‐scanned image.
Transmission loss planning for digital networks
Authors: Sawakuri Tatsuya , Yamamoto Yutaka , Satoh Naoshi 
Published: July 2007

AbstractThis paper describes the transmission loss plan for a digital network on the basis of transmission quality evaluation data for telephone, modern and facsimile services. First, reference equivalent distribution of a subscriber loop and terminal return loss distribution at 2‐wire/4‐wire conversion circuit of digital local exchange subscriber circuit, which are network parameters for transmission loss planning, are estimated based on investigations of the actual conditions. Next, with respect to the telephone, the relation between transmission loss and opinion is clarified both for a short length of connection where degradation due to echo is negligible and for medium and long length of connections where the echo performance is taken into account. With respect to modem and facsimile, the relation between openloop loss and quality degradation is evaluated experimentally. As a result of total evaluation of network parameters and evaluation data with respect to telephone, modem and facsimile, it is revealed that the transmission loss in EO‐EO all‐digital network should be set at 4 dB for intra‐office connecnection. Here, degradation due to echo is negligible and 8 dB for medium and long length of connections where echo performance is taken into account to maintain good telephone and modem‐facsimile transmission quality. Finally, the transmission loss plan from existing analog network to EO‐EO all digital network is shown.
Access time analysis of dynamic MOS RAM
Authors: Nagayama Yasuji , Works Kitaitami , Mashiko Koichiro , Yoshihara Tsutomu , Nakano Takao 
Published: July 2007

AbstractAmong the high‐performance factors of dynamic MOS RAM's, high speed is the most important and its research and development has been carried out actively. However, a model for access time analysis which serves as a guide for the realization of high‐speed access time has not been proposed extensively nor is its quantitative analysis sufficient. It is shown in this paper from the factor analysis of 64K dynamic MOS RAM access time that approximately 50% of the access time is spent on the sense time to read a small signal. Further, an analytical relation for the delay time of basic clock circuits is derived. Also, a model for the access time analysis is proposed which represents the access time as a sum of word line delay, bit line delay, sense time, and signal delay in the peripheral circuits. It is shown that the calculated value and the measured value of the access time of the fabricated 64K dynamic RAM agree to within 15% error. This confirms the effectiveness of the model. Further, from the access time sensitivity analysis using the access time analysis model, the simplicity of the peripheral circuits, the increase of the conductance value, and the reduction of the threshold voltage are shown to be effective for high speed.
A packet transfer control method using circuit switching function
Authors: Hiramatsu Yukio , Mase Kenichi , Kajiwara Masaichi 
Published: July 2007

AbstractAs the scale of the packet switching network and the number of pac̀ket transit nodes increases, the packet switching load and packet delay in the network increase in general. Technologies to suppress these tendencies and to construct the packet network economically are becoming more and more important. This paper assumes transit switches (TS) with both circuit and packet switching functions in a packet switched network. Then a packet transfer method is proposed in which the transit switches set up the direct channel between a pair of source and destination nodes if the traffic between the node pair increases beyond a threshold. First, newly introduced controls for setting up and releasing the direct channels and their desired realization methods are clarified. Next, direct channel set‐up/release characteristics and packet delay characteristics are clarified through numerical calculations of the source switch model and simulation. From these results it is shown that this control method reduces the transit switching load and shortens the packet delay in the transit network. Furthermore, an approximate formula is derived to determine the threshold value of traffic between source and destination switches.
Bifurcations and chaos in sampled data systems with dead zone
Authors: Ushio Toshimitsu , Hirai Kazumasa , Hirayama Hiroshi 
Published: July 2007

AbstractDepending on the parameter values various kinds of bifurcations can be produced in a nonlinear system. Although there have been many studies made on the bifurcations of fixed points, many problems remain unsolved for bifurcations of invariant closed curves. On the other hand, it has recently been noted that deterministic systems sometimes exhibit chaotic solutions. This phenomenon is called chaos, which is becoming one of the important problems in engineering. However, little attenuation has been devoted to bifurcation and chaos in sampled data systems. This paper discusses the relation between the bifurcation, chaos and sampling period in a sampled data system with dead zone. As the first step, the fold bifurcation set and the range of existence for chaos are determined for a one‐dimensional sampled data system. Then the fold bifurcation set and the Hopf bifurcation set are determined for a two‐dimensional sampled data system. It is verified by numerical experiment that transition of the invariant closed curve to chaos by Hopf bifurcation is closely related to the stable and unstable manifolds of saddle‐type fixed point.
Characterization of Si MIS solar cell
Authors: Okuno Tetsuhiro , Osaka Yukio , Hirose Masataka 
Published: July 2007

AbstractThe MIS solar cell has an advantage in that its open‐circuit voltage is high. However, its operation has not been understood fully as yet. We have investigated the effects of an Si02 thin layer and of an Si/Si02 interface on the quality of the MIS solar cell. We found that suppression of majority carrier currents by the Si02 layer caused a high open‐circuit voltage. Furthermore, a means is discussed to determine whether the conduction mechanism which determines the open‐circuit voltage is due to tunneling currents of majority carriers or to diffusion currents due to minority carriers.
Delayed random access schemes ‐an improvement method of delay distributions for packet broadcasting systems ‐
Authors: Mukumoto Kaiji , Fukuda Akira 
Published: July 2007

AbstractIn many cases, the characteristics of random access schemes have been evaluated using average quantities such as average transmission delay, throughput, etc. Random access systems usually have packet delay distributions with long exponential (geometrical) tails. This may be a serious drawback when the suitable criterion is not the average delay but some high percentile (90%) value of delay. We propose delayed random access schemes which improve delay characteristics. In this modified system, a terminal which has just generated a packet does not enter the random access state immediately but enters the state after a delayed time determined by some procedure. Hence, queueing discipline tends to be like FIFO and distribution for transmission delay is improved. For three typical delayed time determination procedures, the extensive effect of this modification is demonstrated using the O‐ALOHA. the three procedures are shown to be effective for improving transmission delay distributions. Some practical studies showing a practical implementation example of a delayed random access scheme are included.
Analysis of broadside‐coupled strip lines with anisotropic substrate
Authors: Kitazawa Toshihide , Hayashi Yoshio , Fujita Kenji , Mukaihara Hiroshi 
Published: July 2007

AbstractTwo analytical approaches are presented for broadside‐coupled strip lines with anisotropic substrates. One is based on the quasi‐static approximation which uses the Fourier transformation and the Ritz procedure. the other is based on the rigorous hybrid‐mode formulation, and the frequency dependent solutions are obtained by using the network analytical methods of electromagnetic fields and Galerkin's procedure. Some numerical results are presented for sapphire and Epsilam‐10 substrates. the effect of the inclination of the optical axis is not so large, and the effect of the shift of central axes of strip lines S/W in the odd modes is larger than that in the even modes. the rigorous frequency dependent solutions converge to quasi‐static values at lower frequencies, and the dispersion of the even modes, which cannot be neglected at higher frequencies.
Numerical technique of perturbation method for computing periodic solution of piecewise‐linear autonomous system
Authors: Okumura Kohshi , Kishima Akira 
Published: July 2007

AbstractThis paper discusses the numerical method of computation in the perturbation for periodic solution of piecewise‐linear autonomous system, which we can calculate up to higher‐order approximations. In many cases of autonomous equations for electrical and electronic circuits, linear and nonlinear terms can be separated leading to the equation of the form × = Ax + f(x) where = d/dt, is a small parameter. This paper considers the case where the coefficient matrix A is of the simple structure and f(x) can be represented by a practically effective piecewise‐linear function. the differential equation is transformed by the mode matrix of A, and using the discrete Fourier transform, an algorithm is constructed which determines the periodic solution up to higher‐order approximations. As the first step, a discussion is made on the relation between Jacobian matrix for Newton's method to solve the determining equation for the amplitude and phase of the zeroth‐order approximation and Jacobian matrix for the piecewise‐linear function. Then it is shown that the first‐ and the higher‐order approximation can be determined by solving the linear equation with Jacobian matrix of Newton's method in determining the zeroth‐order approximation as the coefficient matrix. It is shown also that to improve the computation time for determining the solution, a faster search of the simplex for the periodic solution is necessary, resulting in a proposal for the search method. In the proposed solution method, Newton's method does not converge when the value of the periodic solution at a time point matches a corner of the simplex. A remedy for such a situation is shown.
Synthesis of minimum quantization error digital filters using floating‐point arithmetic
Authors: Akamine Masami , Higuchi Tatsuo 
Published: July 2007

AbstractQuantization error arising from roundoff and coefficient quantization presents a serious problem in realizing a digital filter with finite‐word length arithmetic. This paper proposes floating‐point realizations of digital filters that minimize quantization error. A filter synthesis problem is formulated with the relationship between round‐off error and coefficient quantization error that has recently been investigated by the authors. the formulation reveals that a combination of the minimum‐ coefficient‐sensitivity structure and the optimum order of additions leads to a realization of a digital filter with the minimum quantization noise. the proposed synthesis consists of transformations in a state space. the optimum ordering of additions is found with the assumption of the use of the successive addition that is amiable to hardware implementation. Finally, the effectiveness of the proposed method is illustrated by an example.
An interferometer direct‐coupled Josephson logic gate
Authors: Hohkawa Kohji , Ishida Akira 
Published: July 2007

AbstractNew interferometer direct‐coupled Josephson logic gates are proposed which have good input‐output signal separation and stable, high‐gain, wide‐margin operation. Formulas for evaluating the threshold characteristics and conditions for high gain and high sensitivity are derived. Dynamic properties such as switching times and waveforms are obtained by computer simulation. These gates were tested‐fabricated with a lead alloy whose properties agreed with the results of computer simulation: sensitivity was 2.5 over a bias range of more than 50%. Thus, they can be used as basic logic elements in buffers and OR gates.
Stability of switched capacitor filter possessing periodic parameter
Authors: Sato Chikara , Fujisaka Hisato 
Published: July 2007

AbstractGenerally, the switched capacitor filter (SCF) is composed of capacitors and switches which operate with constant period T and sometimes contain operational amplifiers. This paper considers an SCF having an extra switch which operates by the period 2MT (M; integer). the stability of the circuit is investigated when two SCF characteristics are switched alternately in the time domain by the newly added switch. Zeroinput response of the second‐order SCF with an additional switch is expressed by the linear difference equation with periodic coefficient. the stability of the solution of this difference equation is investigated. As a result it is shown that even if each characteristic of the SCF is stable individually, the system may become unstable when the two characteristics are switched in the time domain by the newly added switch. the stability conditions and the boundary curves from stability to instability are obtained. Further, corresponding instability phenomena are confirmed by experiment.
An expression of equivalent circuit in active RC filters
Authors: Okine Mitsuo 
Published: July 2007

AbstractMany second‐order active filters with operational amplifiers have been proposed. Modeling the operational amplifier with nullators and norators, or else with an equivalent circuit with controlled sources, the transfer function is determined and matched with the desired filter function.In this paper, a new equivalent circuit is given for these filters. This is done by selecting three terminals in the circuit—the input and output terminals, together with another arbitrary terminal within the circuit—yielding a structure formed by a fundamental inverse‐L circuit and a controlled source. the voltage transfer function is then given as the product of the inverse‐L voltage ratio and the amplifier gain.Using this equivalent circuit, any filter may be represented by an inverse‐L structure with any of the following two sets of elements: (1) inductance or FDNR, or (2) negative RC elements. Since the operation of the inverse‐L filter can be analyzed easily merely by comparison with the operation of LC filters, the properties and operation of the active RC filters can be explained.
Design and characteristics of optical power meter high‐density fiber unit
Authors: Maekawa Eiji , Yoshida Koji , Nihei Fumihiro 
Published: July 2007

AbstractProperties of a power meter for a fivefiber cable unit are investigated. Light sources which are amplitude modulated are connected to the fibers and separated after being detected by a single photodetector; this system requires a photosensor, a current‐voltage converter, and bandpass filters for separating amplitude‐modulated signals. A test fabricated system has been used to confirm that the photodetecting system meets the design requirements and that errors caused by the bandpass filters are less than 0.01 dB; the temperature characteristics and reproducibility of the measurement are equivalent to the conventional power meter for a single fiber.
A hierarchical neural network model for associative memory
Authors: Fukushima Kunihiko 
Published: July 2007

AbstractThe author has previously proposed (neo) cognitron, which is a multi‐layered neural network model with hierarchical structure, and has shown that the model can acquire a higher‐order pattern recognition ability by self‐organization. This paper reports on a new neural network model which has a junction of associative memory as well as an ability of pattern recognition. the new model is realized by adding positive feedback efferent connections to the cognitron‐type multi‐layered neural network model. Even if a fragment of a training pattern is given to the network after completing its self‐organization, the positive feedback signal acts to produce the correct entire pattern gradually with the course of time in the first cell layer. When more than one training patterns are presented together, a competition arises among the patterns, but one of them survives with the course of time, with the others vanishing. At the same time, one cell, corresponding to the pattern ultimately recalled in the initial layer, responds in the deepest layer, indicating the result of recognition. When the positive feedback is interrupted for a moment at this stage, the response for the suppressed pattern appears. By repeating such a procedure, patterns simultaneously presented can be separately and successively recalled.
Error performance improvement of QDPSK in the presence of cochannel or multipath interference using diversity
Authors: Horikoshi Jun 
Published: July 2007

AbstractThe quadriphase PSK system is thought to show the highest spectrum efficiency among M‐ary PSK systems for mobile communication purposes and is a noted digital radio system. the diversity effect of the QDPSK system using differential detection has been analyzed approximately. However, since no exact analysis has been done, approximation accuracy has not been clarified. This paper first compares the exact analytical value under cochannel interference and the approximate formula. As a result, it is shown by the method of least squares that the error rate is approximated very closely in precision with a simple formula. Analysis of multipath interference, which simulates frequency selective fading, is carried and the performance difference from that under cochannel interference is discussed. the diversity effect for multipath interference is lessened slightly compared with cochannel interference. It is also indicated that when the average power of a first‐coming wave is nearly equal to that of a delaying wave (often the case in multipath interference) and the error rate is degraded, the diversity effect cannot be expected practically. Finally, the need for a technique to alleviate degradation caused by this difficult‐to‐control propagation characteristic is mentioned.
Coupling of electromagnetic waves to transmission lines
Authors: Kami Yoshio , Sato Risaburo 
Published: July 2007

AbstractThe problem of coupling between the transmission line and the external electromagnetic waves is analyzed more easily and more effectively if it is treated via transmission line theory rather than scattering theory if the cross section of the transmission line is much smaller than the wavelength and the principal mode of the induced current is TEM. This paper derives the transmission line equations by which the induced current is excited by the electric field components in the transmission direction and between the lines among the electromagnetic field components. the relation with the conventional theory, physical meanings and the equivalent circuits are discussed. In the experiment in which a plane wave is used as the external electromagnetic field, the results agree well with the present theory and the validity of the theory is confirmed if the transmission line cross section is extremely small. Further, a compensation method is discussed for the transmission line height for which the principal mode is considered TEM. the theoretical accuracy is shown and the fact that the line width restricts the range of applicability of this theory is confirmed experimentally.