bluuebunny/crossref_metadata_2025_split huggingface dataset:
Near field distributions around free ends of dielectric waveguide
Authors: Matsumura Kazuhito , Kawamura Hajime 
Published: July 2007

AbstractThe field intensities near the free ends of circular and rectangular waveguides with various end profiles are measured in the microwave frequency range. It is found that there exist characteristic field profiles in front and rear of the free ends depending on the shape, slant angle and normalized frequency. the field is measured by scanning a probe antenna near the free end. the measurement process is semi‐automated with a microcomputer which controls the antenna location and processes measured data. In general, analytical treatment of the discontinuities in a dielectric waveguide is complicated. In this paper, a simplified analysis is introduced for finding approximate values of the field near the free end. From the physical requirement on the field near the free end and the phase distribution on the free end, the electromagnetic field on the free end is assumed. This field distribution is used as a source from which the near field is numerically obtained. the numerical results exhibit characteristics of the measured field except for those near the extremities. the measurement technique and the approximate analysis reported here may be applied to free ends with different shapes.
Recursive ϵ‐nonlinear digital filter
Authors: Arakawa Kaoru , Harashima Hiroshi , Miyakawa Hiroshi 
Published: July 2007

AbstractA recursive ϵ‐nonlinear filter that removes random noise from signals with sharp discontinuities is proposed. It consists of a linear recursive low‐pass filter with the addition of simple nonlinear fuctions. the proposed filter with a smaller number of taps is as effective as the nonrecursive ϵ‐filter repored previously. Methodologies, realizations, and stability problems of the proposed filter are discussed. It is shown that the filter must be realized in cascade form for stable operation. Realizations of the multistage recursive ϵ‐filter should be used from consideration of stability.
Algorithms for solving systems of nonlinear equations by Kevorkian's decomposition method and their quadratic convergence property
Authors: Yamamura Kiyotaka , Oishi Shin'Ichi , Horiuchi Kazuo 
Published: July 2007

AbstractKevorkian's decomposition method is known as one of the methods to decompose a large‐scale system of nonlinear equations into systems of equations with lower dimensions. However, his method suffers from the property that errors are included in the decomposed equations, function values, and the Jacobian matrix. Consequently, it is important to discuss the convergence of the solution algorithm and to improve the convergence speed, taking those errors into account. This paper presents an algorithm for the solution of systems of nonlinear equations using Kevorkian's decomposition method. the convergence property of the proposed method is discussed, indicating that the algorithm gives local quadratic convergence under some suitable conditions. A sufficient condition is given first for the existence and differentiability of the mapping G obtained by decomposition. Then a discussion is made of the errors in the equations and the function values by Kevorkian's method. A solution algorithm is proposed which retains the quadratic convergence under those errors, leading to a theorem for convergence. A numerical example is given, indicating that the quadratic convergence can be realized by the proposed method. A comparison is made with the case without using the proposed method, demonstrating its effectiveness.
An LC simulation active RC low‐pass notch filter by minimum number of capacitors
Authors: Ishibashi Yukio 
Published: July 2007

AbstractThe most important measure in judging the advantages or disadvantages of a synthesis method for an active RC filter is the element sensitivity. One of the powerful methods for minimizing element sensitivity is the well‐known leapfrog‐type synthesis which simulates a doubly terminated LC filter.In this paper, a method for the synthesis of an LC simulation active RC filter is proposed which can realize a low‐pass notch filter with a minimum number of capacitors. First, how the signs are taken for the node voltages and inductor currents so as to minimize not only the number of capacitors but also the number of operational amplifiers is described; voltage and current relations are derived; and a circuit for realizing these relations and a method for synthesizing an odd‐order filter are shown. Next, the effects of the variation of RC elements and the GB product of the operational amplifiers are described. Finally, a fifthorder low‐pass notch filter is designed and an experiment is carried out. Furthermore, sensitivity calculation is performed using a computer and it is shown that the element sensitivity of this circuit is about 80% that of a circuit realized by conventional leapfrog synthesis.
Analysis of the stability of oscillation modes in parallel‐running oscillators
Authors: Hamaya Susumu 
Published: July 2007

AbstractThere are several oscillation modes in multiple parallel‐running oscillator circuits. to reduce the adjustment of oscillators and coupling circuits, it is important to obtain single‐mode oscillation in the parallel‐running circuits for power combining so that only the desired mode of oscillation is stable and all the remaining modes are unstable. In this paper, all of the oscillation modes existing in a parallel‐running system consisting of several oscillators with identical Rieke diagrams are extracted and their stability is studied. It is shown that single‐mode oscillation can be easily obtained if the operating point of the desired mode is located at a point away from the origin of the Rieke diagram and the operating points of other modes are at the origin. In this case the operating points of different unwanted modes are necessarily found at points away from the origin and these modes may be stable. However, they are not detrimental in the multiple oscillator system. Analysis and experiment are performed for three representative parallel‐ running systems using hybrid elements.
Analysis of optical waveguide junctions by means of an integral equation method
Authors: Nobuyoshi Terumi , Morita Nagayoshi , Kumagai Nobuaki 
Published: July 2007

AbstractUsing a slab waveguide model we analyze the problem of waveguide mode transmission and reflection that occurs at the junctions of dielectric optical waveguide due to lateral offset, angular tilt, and gap between the guides, and deformations of the end faces. the analysis first develops a set of integral equations for the unknown equivalent electric and magnetic surface currents over the end faces. the integral equations are discretized through partitioning of the boundaries of both ends into small elements, and their solutions are expanded in a Neumann series, which makes it possible to obtain the solutions iteratively. Using reciprocity and mode orthogonality properties appropriately, the mode coupling coefficients are obtained. After discussing the relation between partition number of the boundaries and convergence of solutions, and the satisfaction of energy relations, we give numerical examples for the reflection and transmission coefficients of guided modes, the radiation losses and the radiation power patterns, choosing end shapes and their locations as the parameters.
Stacked analog—I2L LSI
Authors: Kaneko Kenji , Okabe Takahiro , Nagata Minoru , Ogura Setsuo , Furihata Makoto , Matsumoto Keizo 
Published: July 2007

AbstractRecently, with the advance of microfabrication techniques, extremely many circuits are integrated in a silicon chip. As a result, the power density is increased and the processing of this power density becomes a key to realize a VLSI. As a means to resolve this problem, this paper discusses a method for reducing the power consumption in the entire analog‐digital LSI by resuing in the I2L circuit, the current already used in the analog circuit. Several representative analog circuits are studied in this paper and a stacking of the analog circuit and the I2L circuit is investigated. As an example, when an I2L circuit is combined in the constant current souce side of the differential amplifier with the signal gain of 36 dB, the noise leakage from the I2L circuit to the output of the differential amplifier is about ‐14 dB (about 2 mV). This stacked analog ‐I2L is applied to an actual integrated circuit. Without losing the function and characteristics of the original integrated circuit the apparent power consumption of the I2L circcuit is made zero and the power consumption of the entire integrated circuit is reduced from 65 mW to 34 mW, which is about a 50% reduction.
An improved method of estimating electron density profiles in the lower ionosphere with VLF reflection coefficients
Authors: Mambo Masayoshi , Nagano Isamu , Okada Syunji , Fukami Tetsuo 
Published: July 2007

AbstractPreviously, we reported a method (the previous method) for estimating by successive iterations electron density profile in the D layer in which if the absolute phase of the ionospheric reflection coefficient for the VLF wave is known, the perturbation of the reflection coefficient is found to solve the integral equation or the perturbation of the electron density by full‐wave analysis. In the present paper, the previous method has been studied theoretically and the following methods adopted: 1) successive calculation at each frequency; 2) restriction of the computed perturbation of the electron density and the successive extension to the altitude range for the corrected values of the electron density by use of the restricted value; 3) smoothing of the computed density by use of the restricted value; 3) smoothing of the computed results of the electron density; and 4) use of specific initial profile of the electron density. These methods have been applied to the exponential distributions and the measured profiles and simulations have been performed. Improved results over the previous method have been obtained. For instance, the cases that could not have been estimated by the previous method can now be estimated. the estimation range has been increased or the accuracy improved.
Study on contact mechanism and electric resistance characteristics of twisted conductors
Authors: Kuribayashi Masashi , Taguchi Morihiko 
Published: July 2007

AbstractThis paper analyzes the mechanical and electrical characteristics of the hand‐twisted conductor splices in communication cables. the validity of the analysis is verified by experiment. Concerning the mechanical characteristics, it is shown that in the physical contact of the conductors the central axis is twisted with an arbitrary pitch angle on a quasi‐cylinder with the radius equal to that of the conductor. Based on such representation of the contact mechanism, the contact pressure and contact width of the twisted conductors are calculated. Concerning the electrical characteristics, it is assumed that there is a similarity between the current distribution through the twisted conductor contact and the electric lines of force produced by the charge on the surface of contact. Based on such assumption, the constriction resistance of the twisted contact is calculated with consideration of the contact pressure and contact width. Estimation is also made on the growth process of the film resistance and the boundary film thickness due to the chemical substances formed on the conductors in contact. the electrical equivalent circuit for the twisted conductor contact is derived, including the constriction resistance, film resistance and conductor resistance. Using the derived equivalent circuit, an expression is derived for estimation of the contact resistance of the twisted conductors.
Modal expansion theory by almost periodic functions for dielectric gratings
Authors: Yamauchi Norikatsu 
Published: July 2007

AbstractA new model expansion method is given for analyzing the diffraction of a TE‐polarized plane wave due to a planar dielectric grating in which the dielectric constant varies sinusoidally in the transverse direction. the field components of the incident plane wave and the diffracted wave on the grating surface can be expanded in an infinite series in terms of grating mode functions. Applying the electromagnetic boundary conditions and using the orthogonality of the Mathieu functions representing the grating modes as almost periodic functions, we obtain a system of simultaneous equations which provides the physical meaning of the amplitudes of the reflected and transmitted diffraction waves. Numerical examples are shown for the diffraction efficiency vs. grating thickness and the efficiency vs. incident angle for the grating with the average dielectric constant larger than that of the ambient when the incident angle coincides with the first‐order Bragg diffraction angle as well as when it does not. It was found in each case that a slow undulation occurs due to diffraction in addition to the periodic undulation due to interference from both surfaces of the grating as the grating thickness is changed. It was shown also that anomalous diffractions due to surface wave excitation occur at a specific grating thickness.
Design of two‐dimensional digital filters with complex coefficients
Authors: Baba Yoshiaki , Takahashi Shin‐Ichi , Imamura Kazuo 
Published: July 2007

AbstractIn the field of one‐dimensional signal processing, the concept of analytic signal has been introduced in order to yield a low‐pass expression for band‐pass‐type signals. This analytic signal is obtained by adding the Hilbert transform of the real numbers as the imaginary part to the original signal. One important property of this signal is that its Fourier transform vanishes for negative frequencies, i.e., it “appears only in the positive frequency axis.” This property is applied to the design of one‐dimensional digital filters.In this paper, a signal processing algorithm using two‐dimensional digital filters with complex coefficients is proposed. This is done by extending the concept of analytic signal to two dimensions; the processing uses the fact that its Fourier Transform “exists only in the right half‐plane of the two‐dimension frequencies plane” or, in the case of quadrantal symmetry, “only in the first quadrant of the two dimension frequencies plane.” Using this algorithm, the degree of freedom for the design of 2D filters is increased and closed design methods for circularly symmetric filters and various new fan filters are possible. Moreover, difficulties of presently known methods such as high‐order requirements and limitations upon the cutoff frequency are greatly relaxed.
Separating capacity of a general two‐layered network of threshold elements
Authors: Takiyama Ryuzo 
Published: July 2007

AbstractUpper bounds of the number of dichotomies and the capacity of a general two‐layered network of threshold elements are obtained. the network considered is one of the fundamental networks which realize piecewise‐linear machines. In the discussion the equivalent transformation theory from the general two‐layered network to a two‐layered network of committee machine type is positively utilized. As a result, it is shown that an upper bound for the capacity of the general two‐layered network with k threshold elements is equal to 2 (2k‐1 + kn), where n is the number of the dimension of patterns to be classified.
Approximation of two‐dimensional digital filters by separable‐denominator rational function
Authors: Hinamoto Takao , Kukita Hiroshi , Maekawa Sadao 
Published: July 2007

AbstractAn efficient procedure is presented for obtaining a rational function having separable denominator from a given twodimensional (2‐D) impulse response over the first quadrant. First, it is shown that the class of rational functions with separable denominator can be characterized by two 1‐D systems and the given 2‐D impulse response is expressed formally in terms of those of two 1‐D systems. Next, a 1‐D rational approximation is done to each of the impulse responses of two formally 1‐D systems using first‐ and second‐order data from it and the coefficients in the numerator of 2‐D rational function are calculated such that the impulse response of the approximating 2‐D rational function coincides with the given one around the origin. Finally, it is proved that the BIBO stability of the approximating filters is always ensured for given BIBO‐stable 2‐D impulse responses.
Intra‐frame coding equipment using LSI oriented coding algorithm
Authors: Kuroda Hideo , Mukawa Naoki , Okubo Sakae 
Published: July 2007

AbstractCompact and low‐cost video coding equipment is indispensable for the economical realization of visual communication services such as traffic monitoring entertainment relay, etc. This paper describes an LSI oriented coding algorithm which is effective for the compact and economical realization of intra‐frame coding equipment. First, an intra‐frame combinational difference coding algorithm is proposed. the encoded picture quality obtained using this coding algorithm is sufficient even for complicated scenes of TV signals. the predictive coding circuit LSIs for realizing this coding algorithm are also developed. Moreover, the variablelength word multiplexing circuit is shown to be suitable for LSI, and LSIs for this are also developed. Furthermore, coding equipment using the coding algorithm and the LSIs were developed, and its compactness is confirmed. A coding experiment was performed by using the developed equipment and it is shown that the equipment is capable of transmitting good quality ITV signals at a 32‐Mb/s rate.
Network structure and minimum number of elements in the topological realization of generalized immitance converters
Authors: Matsumoto Tadashi , Hibino Kazuhisa 
Published: July 2007

AbstractThis paper presents a basic discussion for all possible topological minimal realizations of the generalized immittance converter (GIC), which is one of the most important functional two‐ports. In other words, a systematic derivation is presented for the lower bounds for the number of necessary elements in the topological realization of a GIC using nullors and positive resistors, as well as for all of the two‐graphs (voltage and current graphs) for the minimal realization of a GIC from the port characteristics, based on the necessary and sufficient condition for the port‐parameter of an N‐port to be topologically non‐zero. As is anticipated from the general expressions for the port‐parameters, the network structure essentially depends on whether or not the gain of the GIC has unit magnitude. Consequently, the discussion is divided into the cases where the gain of the GIC is of unit magnitude and where it is not. Using the result of this paper, all minimal realizations for GIC, including the newly derived ones, can be derived systematically and easily [4, 9].
Synthesis of wideband switched‐capacitor filter based on approximation theory
Authors: Uno Shintaro , Ikeda Yukio , Takahashi Shin‐Ichi 
Published: July 2007

AbstractSwitched‐capacitor filter (SCF) design methods reported so far fall into one of the following categories: design from the s‐do‐main, in which a filter is synthesized based on a direct approximation to the s‐transfer function; or design from the z‐domain, in which the system is regarded as being discrete and z‐transfer function is used. This paper proposes a new method of SCF synthesis based on an approximate s‐z conversion, starting from a given frequency characteristic. Characteristics of equivalent capacitors and SC integrators are expressed in a variable p(z). The desired characteristic F(s) is then approximated by the least‐square method with a rational function of p, FC(p).An SCF is constructed from FC(p) using the element substitution method in active FC filter networks. Previously proposed methods of synthesis from the s‐domain based on linear approximation or bilinear transformation result in large substitution errors, especially when relatively low sampling frequency is used. The present method minimizes substitution errors and extends signal bandwidth close to its theoretical limit.
Fluctuation and scattering properties of RF sputtered glass thin film optical waveguides
Authors: Imai Masaaki , Ohtsuka Yoshihiro , Koseki Mamoru 
Published: July 2007

AbstractThe fluctuating scattering properties of a Corning 7059 glass thin‐film waveguide RF‐sputtered on pyrex glass are studied theoretically and experimentally. Light propagating in the thin film waveguide is radiated owing to imperfections of the thin film boundaries and refractive index irregularities in the film. It is thus possible to estimate the imperfection characteristics of the waveguide by comparing the measured scattering pattern with the computed data. An example of the measured results indicates that the correlation lengths of each irregularity are bx/λ ∼ 0.1 and bz/λ ∼ 1.0 and the ratio of the dispersions is G (= Vf/(Vλ)) ∼ 1.0. Here bx and bz are the correlation lengths in the film thickness direction and in the propagation direction, Vf and V are the rms values of the boundary and refractive irregularities, and λ is the wavelength. From these results it is found that both the refractive index irregularity in the thin film and the boundary irregularity contribute to the scattering loss in the glass thin‐film waveguide created by RF sputtering.
An advanced SSBL‐acoustic reference system using a planar hydrophone array
Authors: Igarashi Masao , Nitadori Kazuhiko 
Published: July 2007

AbstractSSBL (super‐short‐base‐line) is an acoustic reference system in which the angle of incidence (direction cosine) and the slant range of the acoustic wave are estimated to locate the source position. A new SSBL acoustic reference system differing from conventional systems is proposed. The new system uses a planar hydrophone array consisting of many hydrophone elements. When a maximum likelihood estimate is implemented for the direction cosine and slant range measured by a planar hydrophone array, the estimate is given so that the envelope of the spatial‐temporal correlation between the array output and the reference signals is maximized. When the short array condition is satisfied for a planar hydrophone array, this spatial‐temporal correlation is given by the temporal correlation, phase compensation and addition. We obtained the lower bound of the mean‐square error of estimates of the direction cosine and slant range and compared the performance of the system with that of conventional systems. For example, when a square planar array of 4 × 4 = 16 elements is used, system gains of about 16 dB for the direction cosine and 12 dB for the slant range are attainable.
Dynamic MOS RAM by midpoint precharge
Authors: Fujishima Kazuyasu , Shimotori Kazuhiro , Ichiyama Toshio , Mashiko Koh‐Ichiro , Ozaki Hideyuki , Nakano Takao 
Published: July 2007

AbstractIt is shown that a high‐speed, high‐voltage‐level readout is achieved with a dynamic MOS RAM by combining two systems: a precharge system in which the bit line is precharged at VDD/2 and an active store system in which VDD is written into a memory cell while a word line is kept above VDD + VT. It is also shown that the midpoint precharge system is favorable for reducing substrate voltage fluctuations. A 256‐refreshing 64‐kbit RAM was fabricated and the effects of the recharge voltage of the bit line on the refresh characteristic and the effects of precharge voltage fluctuations on the readout voltage were investigated. As a result, the authors obtain a 64‐kbit dynamic MOS RAM with a cell size of 190 μm2, VDD = 5 V, readout voltage of 340 mV for “H” and “L”, VBB fluctuation of 600 mV and access time of 120 ns.