bluuebunny/crossref_metadata_2025 huggingface dataset:
A construction of single error correcting and multiple unidirectional error detecting codes
Authors: Itoh Hideo , Nakamichi Matsuroh
Published: July 2007

This paper proposes a construction method for a code (SEC‐MUED code) which corrects single errors and detects multiple unidirectional errors. It is a kind of concatenated code which can be obtained by concatenating the check bits of a Hamming single error correcting code, Berger code, parity code and Berger code with natural number weight assigned to logic value 0 with the information bits. Another method of construction of an SEC‐MUED code has already been proposed by Bose et al. This paper first discusses the construction of the proposed code, proof of the code and construction of the encoder and the decoder. Then a quantitative comparison is made of the proposed code and the code by Berger et al. from the viewpoint of the number of check bits, the number of gates in the signal path of the encoder and decoder, and the complexity of hardware from the implementation viewpoint. As a result, it is shown that the proposed code results in fewer check bits than the code by Bose et al., fewer gates in the encoder and the decoder and less hardware complexity. For example, for information bit length of 64, the number of gates is 69% and 58% of the Bose code in encoding and decoding, respectively, and the hardware complexity is 51% of the Bose code. The proposed code is thus shown to be a more efficient SEC‐MUED code.
Adaptive channel equalizer with frequency sampling filter
Authors: Fujii Tetsurou , Harashima Hiroshi , Miyakawa Hiroshi
Published: July 2007

This paper proposes a new method of circuit construction for the adaptive channel equalizer using frequency sampling filter, together with the result of analysis of its characteristics. In the proposed method, the discrete Fourier transform is applied successively to the received signal and, by adjusting the tap coefficients according to the energy in each DFT coefficient, high‐speed convergence is realized. A discrete Fourier transform using a frequency sampling filter is adopted in the proposed system, whereby an adaptive equalizer with arbitrary number of taps can easily be constructed. From the result obtained by using a simulated sequence, it is seen that the proposed system has the same order of convergence speed with approximately half the number of multiplications and divisions required with the lattice‐type adaptive equalizer. A parallel construction is possible for the adaptive channel equalizer with frequency sampling filter and the method is applicable to existing equipment.
Thin film fresnel light modulators
Authors: Takizawa Kuniharu
Published: July 2007

Thin film Fresnel modulators were analyzed and studied experimentally. These devices, which can electrically control the phase of the diffracted light from a one‐dimensional Fresnel lens, have the following advantages: (1) they can perform simultaneous focusing and optical modulation; (2) the light output is unaffected by temperature variation; (3) no analyzer is required; (4) a high optical input power can be used. The light modulator may be of the amplitude type, using a channel waveguide, or the phaseshift type, using a slab waveguide. The former has a better light extinction ratio and consumes less power, while the latter has a high light output and is easy to fabricate. A LiNbO3 crystal was cut in the Y direction and thermally diffused with Ti,producing one‐dimensional lens 2 mm wide with a total length of 5 mm, having 13 zones. Electrodes were placed on the even‐numbered zones by photolithography. In the amplitudetype, the diameter of the focal spot used 56 μm, the extinction ratio was 18.1 dB, the half‐wave voltage was 28 V and an efficiency of ‐10.1 dB was obtained. In the phase‐shift type, the spot diameter was 53 μm, the extinction ratio was 11.7 dB, the half‐wave voltage was 39 V and an efficiency of ‐10.6 dB was obtained. The focal length of both types was 12.4 cm.
Frequency weighted LPC spectral matching measures
Authors: Sugiyama Masahide , Shikano Kiyohiro
Published: July 2007

Spectral matching is a powerful method of calculating the distance between two frames in speech data which is used in speech analysis, speech recognition and the evaluation of speech quality. Since the introduction of LPC [linear prediction coefficient] analysis, several LPC spectral matching measures have been proposed. It is widely known that human hearing has greater sensitivity in the low‐frequency region than in the high‐frequency region. However, it is impossible to assign frequency weighting using conventional LPC spectral matching measures. This paper proposes two types of frequency weighted LPC spectral matching. The first method is applicable only to the peak weighted measure, while the second is applicable to a more general LPC spectral matching measure. The theoretical relation between these two types of frequency weighting methods is discussed and vowel identification experiments are carried out to examine the effectiveness of these methods. It is seen that the first method is effective in assigning the same frequency weighting to all frames and the second method is effective in assigning different frequency weightings to frames with different phonemic reference patterns.
Time‐optimal transmission of time‐variant particle flow streams through time‐invariant networks
Authors: Onaga Kenji
Published: July 2007

This paper deals with the dynamic flow problem in the time‐optimal transmission of time‐variant input particle flow streams through the time‐invariant networks with edge capacity c and edge delay d. The minimum‐cost static flow problem is first solved by the successive assignment method to obtain the routing information i = 1, 2,…, k}, where pi is the i‐th minimum‐cost path, Δi is the maximum flow augmentation is the cost. The routing information is next used to find an algorithm for constructing the maximum flow and preserving time optimality. In the first half of the paper a solution is found for the case in which both time and flow are discrete; in the second half, the result is extended to the case in which time and flow are continuous.
Propagation properties of dielectric waveguides with optically induced plasma layers
Authors: Ogusu Kazuhiko , Itoh Hidetoshi , Tanaka Ikuo
Published: July 2007

Propagation of millimeter waves in a semiconductor dielectric waveguide is controlled by illuminating the waveguide by light with a photon energy larger than the forbidden gap because of the generation of plasma. A theoretical and experimental study is made of this and the effects of waveguide size and plasma layer thickness on attenuation and phase shift are analyzed for various illumination intensities. Further, the modulation characteristics are examined in relation to the response of the plasma density. A shorter plasma recombination time is found to be favorable for high speed control, but this requires intense illumination to maintain the required plasma density. A test made with a Si waveguide at 50 GHz substantiates the usefulness of this technique and the validity of the theory.
Design of CMOS masterslice logic LSI
Authors: Asano Michio , Masaki Akira , Itoh Tsuneo , Takechi Makoto , Fujita Minoru , Ikuzaki Kunihiko , Murata Shingo
Published: July 2007

This paper describes the design of a masterslice LSI with two‐input equivalent 6000 gates (three‐input 4000 gates). It uses 2 μm CMOS dual Al interconnect process technology and has application to medium and small computers, terminals and peripheral equipment. It is shown that a three‐input bent‐type gate basic cell effectively realizes high integration because various logic gates can be constructed with small areas. to realize high speed, the chip is designed in several blocks. the intra‐block net uses short interconnects, whereas the inter‐block net is driven by buffers with high load drive capability. Special clock supply circuits for small clock signal skew and a register‐file to accommodate a small capacity RAM into LSI are designed. the number of wiring channels is determined based on the theoretical wiring length, and it has been confirmed that channel utilization agrees with the theoretical value. Since it is important that a masterslice LSI be designed to its specifications within a short time, a method is developed to calculate accurately the circuit delay time during the design. Evaluation of the test LSIs shows that the average gate delay time of 1.81 ns is obtained; this agrees to within 5.4% of the calculated delay time.
Wave digital filters for second and fourth order basic reactance sections
Authors: Suzuki Masatoshi , Wakabayashi Hiroyuki , Miki Nobuhiro , Nagai Nobuo
Published: July 2007

One way to realize a low coefficient sensitivity digital filter is to simulate a resistively terminated LC ladder network. This is called a wave digital filter. However, the transfer functions realized with a resistively terminated LC ladder network are limited. A resistively terminated reactance network realizing an arbitrary transfer function may be synthesized by cascading basic reactance sections. In this paper, we use Brune, Types C, E and D sections with 2‐wire lines as the models for the basic reactance section. These basic sections are represented using modal decomposition by equivalent circuits made of ideal transforming networks (including gyrators for nonreciprocal circuits) and uncoupled lossless lines. Then we derive basic wave digital filters of reciprocal and nonreciprocal second‐order sections and reciprocal fourth‐order sections. the digital filters realized from the basic wave digital filters in the present method do not correspond exactly to the original analog circuit as long as they are constructed with multipliers with finite word length; however, they become low coefficient sensitivity digital filters with as good performance as the wave digital ladder filters.
Power spectral density of multilevel digital signals in nonlinear channels
Authors: Okamoto Eiji
Published: July 2007

In digital microwave communication, a power amplifier is located at the transmitting side. Generally, such a power amplifier has a nonlinear input‐output characteristic. However, the greatest problem with this kind of nonlinear transmission system is the spectrum width of the signals. Until now, a spectrum has been obtained by approximating the input‐output characteristics of a power amplifier by third‐order equations. When third‐order equations are used, however, only one sidelobe appears in the spectrum. to obtain a more detailed spectrum, the input‐output characteristics of the power amplifier must be approximated by equations of higher than third‐order. This paper presents equations for the power spectral density of multilevel digital output signals of a transmission system. the system consists of a power amplifier having an input‐output characteristic which can be approximated by a filter and fifth‐order equations. Consequently, it has become possible to compute a power spectral density, for example, for quadrature amplitude modulation (QAM) having more than 32 levels, which was difficult to obtain by the simulation method. Examples show the results of computations for power spectral densities of 16‐ and 32‐level QAMs.
Effect of axial misalignment and multiple reflection on jones matrix of a four‐crystal light modulator
Authors: Moritani Akihiro , Nakai Junkichi
Published: July 2007

The latest off‐the‐shelf 45 X‐cut (ADP or KDP) four‐crystal light modulators with low driving voltage consist of four crystal units to accomplish temperature compensation and to make possible a low driving voltage. Therefore, axial misalignment is not uncommon. Also, because there are many interfaces between the crystals and the matching dielectric fluid, multiple reflection may cause problems. the effects of these phenomena on the Jones matrix describing the fundamental characteristics of optical phase modulation are examined. First, the dielectric tensor of the crystals with axial misalignment and the characteristic plarizations in the crystal are derived. Then, using Berreman's 4 × 4 matrix formulation, the Jones matrix representation of a four‐crystal light modulator with axial misalignment is derived. It is pointed out that the off‐diagonal terms arise from axial misalignment, which is one cause of temperature variation of the light modulator characteristics. A numerical estimate is made of the effect of multiple reflection. It is pointed out that the effect of multiple reflection on the off‐diagonal elements of the Jones matrix is negligible while the effect of the diagonal elements is substantial. an experimental example with an actual modulator is given to determine the location of the axial misalignment.
Bandpass filters using electrically‐coupled TM010dielectric rod resonators
Authors: Kobayashi Yoshio , Kojima Katsuto , Yoshida Shinichiro
Published: July 2007

The authors previously described the design of shielded TM010dielectric rod resonators (below referred to as “TM010resonators”), a new configuration of small‐size resonators for microwave frequencies. This paper describes the design of bandpass filters using coaxially oriented electrically‐coupled TM010dielectric rod resonators. First, the resonant frequency of electrically‐coupled TM010resonators is analyzed by applying the Ritz‐Galerkin method to the integral equations that express the boundary conditions. This method is shown to be effective in numerical calculation of the coupling coefficients and center frequency of the coupled resonators and the resonant frequencies for inserted TM010resonators which are required for filter design. Next the characteristics of the coupling probe which effectively produces the strong coupling of the axially symmetric TM010mode of resonators and suppresses the excitation of the higher modes are determined experimentally, making it possible to estimate the center frequency for a filter which takes the variation of the resonant frequency produced by the excitation and coupling hole into consideration. Finally, design of 2‐ and 3‐stage filters of various bandwidths at 2.7 GHz demonstrates the suitability of the approach. Relative bandwidths of 1 to 10%, low losses of. 15 to. 6 db, and absence of spurious responses over bands wider than 1 octave are obtained.
Radiation of millimeter waves from a corrugated ferrite‐slab waveguide
Authors: Ohira Takashi , Yuasa Tetsuji , Tsutsumi Makoto , Kumagai Nobuaki
Published: July 2007

A theoretical analysis based on the multiple scale method is presented for the behavior of the leaky wave in a corrugated ferrite image guide. the attenuation of the guided mode due to leakage is given analytically as a complex perturbation of the propagation constant. As an application of this structure, a millimeter wave leaky wave antenna has been considered and its radiation efficiency and directivity have been studied. Next, experiments are carried out for a leaky wave antenna using a poly‐crystalline YIG slab. the radiation pattern has been measured in the 40‐GHz band and compared with theoretical values. A change in dc magnetic bias by 1 Wb/m2 shifts the main beam to be scanned by 17.5 degrees. the experimental results agree well with theoretical data.
Low‐loss faraday cell for a laser gyro with brewster‐angle quarter‐wave plates
Authors: Izumi Yoshinori , Uchiyama Taro , Fujioka Tomoo
Published: July 2007

A new type of low‐loss Faraday bias cell has been designed to overcome the lock‐in phenomenon, which is the weak point of conventional ring laser gyros. Low loss has been achieved by shaping a quarter‐wave plate into a Brewster‐type plate. Experiments using this cell for internal modulation have confirmed that the cell is sufficiently effective as a bias modulation element in eliminating the lock‐in phenomenon.
Analytical expressions for the electric field constants at cathode of electron gun
Authors: Kajiyama Yoshino
Published: July 2007

The electrical characteristics of the cathode immersion lens in an electron gun can be clearly expressed in terms of four electric field constants. This paper proposes a method for analytical derivation of these constants in contrast to the conventional simulation methods. It is shown that the electric field constants can be determined in practice by a simple procedure of calculating the potential distribution function corresponding to its linear function approximation on the cylindrical surface along the electrode hole. By means of this procedure, dependence of the electric field constants on the electrode dimensions can be clearly understood. an integral equation was derived that connects the potential distributions corresponding to the planar space and the cylindrical space. By computer solution, accurate values of the potential distribution on the cylindrical surface along the electrode hole were determined. Repeating the calculation with these correct boundary values, we can derive accurate electrical field constants. Comparing these results with those obtained by a simplified method, reliability of the latter has been confirmed. It is also possible to analytically calculate the potential distributions in the entire space. Many applications are expected based on unique features of the method enabling a good perspective of the problem.
Anti‐fading polygonal cylinder passive repeater
Authors: Numano Yuji
Published: July 2007

For economical construction of general microwave communication channels passive repeaters are used. Effective improvement in avoiding momentary interruptions cannot be expected unless measures are adopted to prevent fading at passive repeaters and space diversity is employed at the antenna side.

The radiation field of an aperture type antenna is represented by the product of the amplitude distribution and the phase distribution of the field at the aperture. Amplitude distribution has been the main area considered in analyses to date. This paper discusses a method for controlling the phase distribution and shows that this method is best suited to prevent fading. the method modifies the shape of a conventional flat reflector excited by plane waves into a polygonal cylinder which inscribes a shallow parabolic cylinder, so that a near‐axis directional beam is formed in even the direction of the first null point of the reflected waves. the level at the first null point of a polygonal cylindrical reflector designed to keep the gain reduction directly on the axis below about 1 dB agrees well with the predicted mean field intensity due to fading at a receiving point. the use of a polygonal cylinder reflector is economical and prevents momentary interruptions due to fading so that the communication channels remain stable and possess high quality with improved reliability.
Statistical time lag of gas discharge in electrostatic recording
Authors: Kimura Masatoshi , Wanou Masahiro , Nakajima Junzo
Published: July 2007

Electrostatic recording is applied widely to facsimiles and printers because of its high speed and high resolution. the time lag in gas discharge formation causes dots to be missed, which must be improved for high‐speed, high resolution recording. We tested the latent image formation by using an aluminum drum coated with a dielectric film uniformly charged to positive potential and a pin electrode. the effects of the pin electrode material, the recording pulse repetition period, and the recording voltage on the statistical time lag on initiating discharges have been investigated. the following results were obtained: (1) A phosphor bronze electrode causes the smallest time lag, followed by nickel and tungsten. (2) the logarithm of the mean statistical time lag is proportional to that of the repetition period. (3) the logarithm of the mean statistical time lag is inversely proportional to the air gap electric field. (4) When the recording pulsewidth is larger than 15 μs for a gap field of 55 MV/m and a recording pulse period of 10 s, the dots missing probability becomes less than 1%.
Evaluation of characteristics of meander heat elements for a thermal printing head
Authors: Shibata Susumu , Ito Masanobu
Published: July 2007

This paper describes the evaluation of characteristics of meander type heat elements for facsimile thermal printing heads. Mainly rectangular type heat elements have been used for this purpose to date. However, they have some inherent weak points, such as difficulty in obtaining a uniform temperature distribution in a desired heating region and difficulty in obtaining a resistance value suitable for driving them. the authors have manufactured samples of meander type heat elements and investigated them mainly from the point of view of their applicable range and reliability. It is known that (1) in meander type heat elements, if the thickness of the element is greater than a certain value and if the elements are covered with protective layers, the elements withstand heat pulses independently from the thickness of the elements. This also prevents the deterioration of elements due to oxidation. (2) the protective layer on a meander type heat element has greater resistance to thermal shock and better printing characteristic than those of a rectangular type heat element. (3) the meander type heat element does not cause local fusion in the heat insulation layer because of uniform heating. Therefore, this has a higher reliability over a wide range of driving pulse widths. (4) the meander type heat element is inherently superior to the rectangular heat element and will make a greater contribution to improvement of the quality of thermal printing.
An arrangement of transmitter and receiver arrays for synthesizing acoustical holograms
Authors: Nagai Keinosuke , Kimura Minoru
Published: July 2007

A method is discussed for synthesizing acoustic holograms consisting of MN pieces of data with M transmitters and N receivers in an acoustic hologram imaging system. Several methods similar to the approach presented here for reducing the total number of transmitters and receivers are examined. the distinctive feature of the proposed method lies in the arrangement of transmitter and receiver arrays on separate planes. the point‐spread function of the synthesized holographic imaging system is computed and the arrangement of transmitter and receiver arrays is restricted so that the grating lobe providing narrower separation is eliminated. the arrangement obtained is a generalization of the well‐known multibeam method in that the transmitter and receiver surfaces are separated. Hence it is applicable not only to reflection holograms but also to transmission holograms. It is also shown that under these conditions the numerical image reconstructed from a hologram can be realized by a single application of the discrete Fourier transform of the MN data. Finally, the results of experimental and numerical simulations are shown and the validity of the proposed method is confirmed.
Analysis of the GI/G/1 queue by the supplementary variables approach
Authors: Komota Yasuo , Nogami Shinya , Hoshiko Yukio
Published: July 2007

This paper analyzes the GI/G/ 1 queue on FIFO discipline by the supplementary variables approach. Using the residual interar‐rival time and the remaining service time of a customer being served as supplementary variables, we derive the basic equations describing the behavior of the system. From the basic equations, characteristic quantities of the system in the steady state are discussed. On the basis of Laplace transform and generating function expression, Laplace transform of actual waiting time is obtained by performing a Wiener‐Hopf decomposition. From this result, Laplace transforms of virtual waiting time, length of an idle period and inter‐departure time and the distributions of the number of customers at the moment just before an arrival and at an arbitrary moment, are derived. Furthermore, it is revealed that the analysis of busy period is reduced to a generalized Wiener‐Hopf decomposition problem. Finally, an application of the general results to the GI/Kn/1 queue is considered and by indicating that the results agree with the known results, the validity of this approach is confirmed.
A type of centrality functions for a directed graph
Authors: Kishi Genya , Takeuchi Masashi
Published: July 2007

In an undirected graph obtained by abstracting traffic and communication networks, evaluation of the centrality of a vertex is interesting from the viewpoint of graph theory. the purpose of discussion of the centrality function is to provide a theoretical basis for solution of the problem. This paper is an attempt to extend the notion of the centrality function defined for the ujidirected graph to the directed graph. the existence conditions of the quasi‐stable and unstable graphs for the centrality functions with general coefficients are derived from the viewpoint of structural stability of the undirected graphs, for which the classification of the graphs is made by the shift of the center by adding an edge with the central vertex as an end point. Furthermore, the stability of the directed graphs is discussed.
A synthesis method for the variable equalizers containing two kinds of variable parameters
Authors: Kawakami Atsushi , Takahashi Shin‐Ichi
Published: July 2007

This paper describes a synthesis method for the two‐variable variable equalizer which contains the parameter μ corresponding to the line length, and the parameter α which is independent of μ and represents the effect of the external factor. the variable transmission characteristic is represented approximately by a polynomialtype transfer function which is a mixed function of μ and a function containing α, which represents approximately the reference attenuation. This characteristic is realized by the state‐space method. By this method, an approximated transfer function is obtained taking the frequency band for the equalization into consideration, and the stability of the approximated function is secured. In addition, the construction with the minimal number of both the network providing the reference attenuation and the variable element corresponding to μ is impossible and the values of the elements are obtained directly from the coefficients of the transfer function. These are the merits of the proposed method over the traditional ones.
Strength assurance of optical fiber based on screening test
Authors: Mitsunaga Yutaka , Katsuyama Yutaka , Kobayashi Hirokazu , Ishida Yukinori
Published: July 2007

One of the most important problems in the practical application of optical transmission systems is to evaluate the reliability of the fiber in optical cable. This paper discusses reliability assurance by screening test, which is the most effective method for reliability evaluation of optical fiber strength. the condition for reliability assurance is discussed, considering the effect of such environments as water and of temperature, time‐varying strain and the distribution of strain along the longitudinal direction of the fiber. the parameters used in representing the strength distribution and fatigue characteristics of the optical fiber, which are needed in the reliability assurance, are quantitatively evaluated based on various kinds of test data. Through discussion of the permissible failure probability of the optical fiber which is required in reliability assurance of the optical transmission system, the condition for the screening test is stated.
A proposed adaptive control method for packet transmission delay in packet speech system
Authors: Suzuki Michio , Kashio Jiro , Toki Ryuichi , Kato Takao
Published: July 2007

There are two basic problems in speech packet switching systems. One is how to guarantee the synthesized speech quality against fluctuation of the mean and variance of packet transmission delay in the network due to traffic fluctuation in packet switching. the other is the problem of deciding the beginning time of the talkspurt synthesis (i.e., when to begin talkspurt synthesis at the receiver side). Under the assumption that the packet transmission delay time is approximated by an exponential function, it is shown that the jitter absorbing time for each talkspurt can be calculated by observation of the packet arrival time at the receiver side. Using this result, an adaptive control method is presented to cope with the above two problems, where the jitter absorbing time is changed according to network traffic changes and the talkspurt synthesis time is determined from several packet arrival times. It is shown from simulation and numerical calculation that application of this control method to a speech packet switching system permits guaranteeing the voice quality in spite of traffic fluctuation in the network and reducing the probability of late beginning of talkspurt synthesis.
Quasi‐one‐dimensional volume‐type hologram memory
Authors: Chang Jon‐Chi , Okoshi Takanori
Published: July 2007

When two different wavelengths are used for recording and reading in a volumetype hologram memory, construction of a space modulator and photodiode array becomes difficult because unwanted patches appear on a reconstructed image. This can be avoided in a one‐dimensional hologram; however, storage density is reduced. This paper proposes a quasi‐one‐dimensional volume‐type hologram which preserves thick film memory (high density memory) while configuration of a space modulator and a photodiode array is simplified and simultaneous reading at different wavelengths is possible. With a PMMA film with thickness 400 μm a storage density of (0.3 ∼ 1.0) × 105 bits/mm2 was realized, Conditions for simultaneous reading at a different wavelength have been clarified.
An ultra‐high‐voltage high‐speed switching power transistor with new fine emitter structure
Authors: Nakatani Yasutaka , Kuryu Isanu
Published: July 2007

Along with the trend toward smaller size and lower energy consumption in electronic equipment, the dc stabilized power supply has been changed from the series dropping to the switching version, which tan he made more compact and light with high efficiency. the switching frequency in these efforts has increased with each year.

Component parts are required for performance in higher frequency regions and it is also hoped that switching transistors will be improved in terms of high speed and large safe operating area. High‐speed switching and large safe operating area have hitherto progressed in a trade‐off relation. This was overcome by decreasing the base resistance via S‐parameter analysis. A newly developed fine emitter structure and oxide planar structure have led to creation of an excellent switching power transistor possessing ultra‐high voltage (1200 V), high‐speed switching characteristics (rise time tr = 200 ns, storage time tstg 2500 nsec, fall time tf = 70 nsec), and large safe operating area (secondary breakdown onset current Isb = 8 A, collector * emitter clamp voltage VCEX(clamp) = 90 V).
Arithmetically symmetrical digital bandpass and band‐elimination filter design by frequency transformation
Authors: Takebe Tsuyoshi , Wakabayashi Masakazu , Nishikawa Kiyoshi
Published: July 2007

In transmission systems of modulated data or picture signals, bandpass filters are required with symmetrical amplitude and delay characteristics around their own center frequencies on an arithmetic frequency scale. In variable attenuation equalizers, etc., band‐elimination filters are required with arithmetically symmetrical stopband amplitude characteristics around the center frequency. This paper proposes frequency transformations to make an analog bandpass filter and a band‐elimination filter (with geometrically symmetrical amplitude characteristics around the center frequencies that are obtained through reactance frequency transformation from analog lowpass filters) into a digital bandpass filter and a band‐elimination filter with arithmetically symmetrical amplitude characteristics. This transformation maps the positive imaginary axis and the negative real axis of analog frequency S to the real axis and the upper half of the unit circle on the z‐plane. the interval on the unit circle of the z‐plane mapping of the positive imaginary axis of the S‐plane is designed to cover the specified frequency region. This is done by controlling the locations of geometrically symmetrical two frequency points around the center frequency of bandpass (band‐elimination) filter by adjusting the parameters of lowpass‐bandpass (band‐elimination) transformation. Some design examples are also shown.
SbEC‐DbED codes derived from experiments on a computer for semiconductor memory systems
Authors: Itoh Hideo , Nakamichi Matsuroh
Published: July 2007

Single byte (= b bits) error‐correcting and double byte error‐detecting (SbEC‐DbED) codes are useful for semiconductor memory systems with memory chips of b‐bit output per one address. In this paper, codes with information length k up to k = 128 bit for 2 b 8 are derived experimentally using a computer. As a result, codes with longer code lengths than before are obtained. In particular, as for the codes of b = 2 and k = 64, 12 check bits were required in the conventional codes, but the codes requiring only 10 check bits are derived by experiments and are an excellent result from a practical viewpoint too. In the derivation, each column in an H matrix of the code is regarded as an element in a Galois field GF (qr) where q = 2b (b is the number of bits in a byte) and r is the number of check bytes. to obtain codes with large code length, as many elements as possible are selected in GF(qr) satisfying the code condition. Here, a subset in a GF(qr) whose elements are linearly independent, is used to select the columns of the H matrix. Moreover, all the elements of GF(qr) arising as operation results in the derivation process can be in correspondence to the elements of the subset. Consequently, the objective sets are restricted and the derivation through computer experiments is facilitated.
Scattering of plane electromagnetic waves by conducting rectangular cylinders ‐a horizontal polarization case ‐
Authors: Hinata Takahashi , Yamasaki Tsuneki , Tamura Masahiko , Hosono Toshio
Published: July 2007

This paper presents a numerical analysis for the scattering of horizontally polarized waves incident on a conducting rectangular cylinder (cross‐section = 2a × 2b) by using the point matching method (PMM). the order of simultaneous equations in the analysis has been reduced to one‐fourth by using the four‐phase symmetrical coordinate method. This has led to a high accuracy of the analysis even for large values of kp0 (k: wavenumber, p0 = √a2 + b2. This paper presents also the numerical results of scattering electromagnetic fields by a conducting rectangular cylinder lying on a flat ground (x‐z plane) which are derived from the two components of four‐phase symmetrical coordinate analysis satisfying the boundary conditions on the x‐z plane. to obtain our numerical results, we did the following: (1) made comparison with the results and discussions of others on similarities and discrepancies among those results, which have led to the justification of PMM, (2) presentation of high‐precision results by PMM for the problems which were analyzed with poor accuracy by other researchers; (3) presentation of scattered far‐field patterns by the skyscraper “Sunshine‐60” in Tokyo as an example for a large value of kp0 = 84.73, comparing vertical polarization. Lastly, a simple method is proposed to calculate approximate scattering fields for large values of kp0 the applicability limit if shown for this approximation method by comparing those results with the accurate results by PMM.
Mutual coupling effects on characteristics of turnstile spherical array antenna
Authors: Horiguchi Susumu , Ishizone Takayuki , Mushiake Yasuto
Published: July 2007

Mutual coupling between antenna elements is one of the greatest problems when a hemispherical scan coverage array antenna of the spherical type is used. Study of mutual coupling of antenna beam scanning has not been thoroughly investigated. This paper studies the method of analysis for the impedances of dipole antennas over a conducting sphere. Theoretical results have been confirmed by experiments. the active impedance distribution and its scanning characteristics are discussed taking into account mutual coupling in the turnstile spherical array antenna with this method. It is shown that mismatching of the impedance is very small at feeding points. Analysis has been extended to the effects of mutual coupling on scanning characteristics of the power gain and the axial ratio of the polarization. It is found that the turnstile spherical array antenna is suitable for wide scanning from the standpoint of the feeding system.
A realization of low‐power supplies using switched‐capacitor transformers and its analysis
Authors: Oota Ichirou , Inoue Takahiro , Ueno Fumio
Published: July 2007

A switched‐capacitor transformer is a coil‐less transformer in which stepping‐up and ‐down of voltage is handled by switching the connections between capacitors alternately into series and parallel. This paper demonstrates that a low‐power coil‐less power supply can be created with these transformers. the proposed circuit has the following features: (1) High efficiency, comparable to that of a switching regulator, can be obtained easily. (2) Because of its coil‐less construction, it can be made small and light. Hybrid integration is also possible. (3) Coil‐less construction significantly reduces generation of magnetic fields. the operating principle is first shown for the circuit with ideal elements. State equations are then derived in which the on‐resistance of the switch element is considered, and these are numerically analyzed. an SC transformer with a transformer ratio of 1/2 and an SC dc‐dc converter with an output voltage regulator already have been constructed with discrete components. Results of the average output voltage and efficiency have been confirmed numerically by experiments on constructed circuits. A comparison of the above two circuits demonstrates that although the latter has an efficiency of about 80% (which is lower than that of the former), both have less than ±0.06% in input‐output variation. the voltage variation is at most ‐0.16% for the temperature variation of −20° ∼ 80°.
Decoding method for doubly encoded reed‐solomon codes and their error probabilities
Authors: Imai Hideki , Yashiro Mitsuhiko
Published: July 2007

A doubly encoded Reed‐Solomon (RS) code is a code obtained by encoding the RS code twice. In general, doubly encoded codes are derived from some simple codes to achieve high error correctability. Each step of the double decoding can be implemented easier than a single step decoding of codes with long code length which have a comparable error‐correctability. Furthermore, the doubly encoded codes are suitable for correcting both random and burst errors. This paper describes a decoding scheme for doubly encoded RS codes and discusses its performance. Data and facts obtained during the first step of decoding are used in the second step of the decoding. Even though it is difficult to obtain the optimum decoding scheme, this paper describes an algorithm that renders near‐optimum outcomes. Using CIRC as an example, the selection of a decoding scheme and its superior performance compared to that of the existing scheme are demonstrated. Furthermore, equations are presented for the approximations of various decoding performance parameters. These approximations are quite accurate compared to the exact values, and can reduce a considerable amount of computation time.
Traffic analysis of PRT gradecrossed intersection
Authors: Kurihara Masahito , Kaji Ikuo , Nakada Katsuhiro , Hamamatsu Yoshio
Published: July 2007

A gradecrossed intersection of the personal rapid transit system (PRT), which is one of the automated guideway transit systems, is modeled. Its control algorithm which assigns moving cells to avoid vehicle collision at intersection part or the merging part is presented. the algorithm is based on a “first‐come, first‐served” principle and no priority between the two intersected lines is introduced. In both lines, the same upper bound is set for the length of forward and backward maneuvering. When the maneuver length is likely to exceed this upper bound, the vehicle is forced to diverge even if it was to go straight, so that the maneuver length does not exceed the upper bound.

To analyze the behavior of this model from the probability theoretical viewpoint, the state is defined based on the maneuver length of vehicles at each time instance synchronous to cell arrival. Thus, the model is formulated as a finite Markov chain (one‐dimensional random walk). As a result, the relation between vehicle traffic density and (1) delay distribution and expected delay time due to intersection passing, (2) abort rate, and (3) throughput, is obtained explicitly.
Distribution of absorbed power inside a sphere simulating the human head in the near field of of a λ/2 dipole antenna
Authors: Amemiya Yoshifumi , Uebayashi Shinji
Published: July 2007

In the new radio frequency protection guide for human exposures to electromagnetic fields recently accepted by ANSI C95, low power devices such as portable radio transmitters are treated as exceptions. This is based on the consideration that these devices may generate fields which, although exceeding the protection guide locally, result in a significantly lower rate of energy absorption for whole body. However, we consider that the localized fields have serious effect at least on the eyes where heat convection due to blood flow is very small. This paper presents the distribution of the absorbed power in the model of a human head exposed in the immediate vicinity of a portable transmitter. In our calculation, the head is simulated by a homogeneous lossy sphere, and λ/2 dipole antenna is used for a portable transmitter. It is found that the local absorbed power is extremely large at the nearest surface of the sphere to the antenna, although the average value is sufficiently small. the peak absorbed power is so large that we believe the reason for excluding low power devices from the ANSI guideline should be reconsidered.
Performance analysis of CSMA/CD protocol with Backoff algorithms
Authors: Iida Ichiro , Yasuda Yasuhiko
Published: July 2007

In recent years the CSMA/CD level area network has been in wide use. However, most of the performance analyses treating stability made so far have been based on the model of a nonpersistent protocol slotted by the propagation delay, which does not represent exactly the actual system. This paper presents the delay and stability analyses of an asynchronous 1‐persistent CSMA/CD scheme with the binary exponential backoff used in the Ethernet. Since this analysis method can be applied to a nonpersistent CSMA/CD scheme or the slotted scheme under the same model, the characteristic difference between the schemes can be clarified. Further, the backoff algorithms can be analyzed under the model representing the actual system. the results of this analysis show that the 1‐persistent CSMA/CD scheme gives smaller throughput and stability than the nonpersistent scheme, and that the previous model gives results that are too optimistic.

It is shown also that the binary exponential backoff is far from optimum in the throughput‐delay characteristics and the noadaptation scheme works satisfactorily under the usual condition with small propagation delay.
Fabrication of master‐slice LSIs using electron‐beam direct writing and photolithography
Authors: Kawashiro Sanji , Suzuki Shin‐Ichi , Suemitsu Takashi , Niriki Takashi
Published: July 2007

As progress in LSI technology has expanded LSI application fields, it has become important to decrease the developmental turn‐around time and cost. One means of achieving this is to employ the masterslice LSI approach. This paper describes a master‐slice LSI fabrication method which uses both electron‐beam direct waiting and conventional photolithography to decrease the SLI development time. In this method, the common portion of a master‐slice LSI is prepared with photolithography. Then custom design of the LSI is done with electron‐beam direct writing. Alignment of patterns formed by electron‐beam direct writing and photolithography is investigated to show that the overlay error in 4‐μm design rules can be made negligibly small without compensation for the wafer expansion/contraction occurring during processing. Al‐gate CMOS LSIs fabricated by this method have shown higher yield and better performance than similar LSIs fabricated wholly by photolithography.
Analysis of parasitic resistance effects in MOS LSI
Authors: Anami Kenji , Yoshimoto Masahiko , Shinohara Hirofumi , Tomisawa Osamu , Nakano Takao
Published: July 2007

This paper describes simplified analysis of the effects of transistor source and drain parasitic resistances and interconnect resistance in MOS LSI's, and their application to the circuit designs for MOS LSI circuits and mask patterns. Heretofore the analysis of parasitic resistance effects has been complex and could only be calculated numerically with circuit analysis programs. However, in this paper, a simple expression is given for the effect of the source and drain parasitic resistances by using a linear approximation to the MOS transistor drain i‐v characteristics. Furthermore, the delays caused by interconnection resistance are analyzed under assumptions that are actually obtained in practical LSI's. the rules for optimum design of the crossunders used frequently in LSI's are obtained using the result. Finally, experimental results from MOS transistors which agreed well with the source and drain parasitic resistance effect analysis. A ring oscillator experiment which also resulted in good agreement with the interconnect resistance delay analysis shows the applicability of both analysis methods.
Decentralized adaptive control of large‐scale systems—a parameter adaption method
Authors: Yoshikawa Tetsuto , Ikeda Masao
Published: July 2007

A way of controlling large‐scale systems that have unknown parameters is a decentralized version of the model reference adaptive control. the idea is to construct adaptive controllers for each subsystem so that the overall system becomes an adaptive control system. the strategy does not always work successfully, however, because the information structure for control is decentralized. This paper aims to provide conditions under which we can construct such decentralized adaptive control systems. We first clarify the constraints to which the given system must conform whichever scheme of adaptive control we employ at the subsystem level, and present conditions which must be satisfied between the given system and the reference model. Then we consider adaptive control laws of the parameter adaption type and give classes of reference models with which they can be implemented.
Vector labelling method in fixed points algorithm and array processors
Authors: Oishi Shin'Ichi , Takase Tadaaki , Yamamura Kiyotaka
Published: July 2007

Studies of fixed point algorithms have advanced greatly in the last decade. These algorithms have been developed to construct globally fixed points of finite‐dimensional continuous maps, to which existence of fixed points is guaranteed by, for instance, Brouwer's fixed point theorem. However, it is pointed out that these algorithms become progressively slower with increasing dimension. In this paper it is shown that the vector labelling algorithm, one of the typical fixed point algorithms, can be performed efficiently in parallel on a suitable array processor system. Under certain conditions, the time complexity of the vector labelling algorithm is determined by pivot operations. It is shown that high parallel efficiency about 0.9 is attained by executing these pivot operations on our array processor. to further speed up the algorithm, a method is also shown for evading matrix inversion formerly needed at the beginning of the vector labelling algorithm.
Transmission characteristics of image fiber
Authors: Hosono Toshio
Published: July 2007

Transmission characteristics of a long image fiber with square of hexagonal periodic multifiber structure have been analyzed. the diffusion process of a light beam incident on a center fiber into the surrounding fibers has been clarified. Finally, a formula has been derived for dependence of the cross‐talk on the core diameter, the core refractive index, and the distance between the cores.