bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on IDT for acoustic imaging uses
Authors: Kikuchi Tsuneo , Moriizumi Toyosaka , Yasuda Tsutomu , Members Regular , Nomura Toru , Toda Kohji 
Published: July 2007

AbstractA piezoelectric interdigital transducer (IDT) normally used for SAW devices can emit high frequency ultrasonic waves into water. To make use of this phenomenon in an acoustic imaging system, characteristics of longitudinal waves radiated from the IDT into water and the radiation mechanisms using the ASPW method were investigated. It was found that two types of longitudinal waves are radiated from the IDT and one of them can be beam‐scanned by changing the frequency. Finally, a focussed ultrasonic wave was obtained from an arched IDT in water and the surfaces of several objects were observed with good resolution.
Spatial‐domain design of separable‐denominator two‐dimensional digital filters
Authors: Hinamoto Takao , Makita Yoshihiro , Maekawa Sadao 
Published: July 2007

AbstractThis paper describes a method for determining the coefficients of a transfer function. In this description when the ideal two‐dimensional Markov parameters and the orders of the separable‐denominator two‐dimensional transfer function are given, the two‐dimensional Markov parameters generated from this transfer function will give the best approximation to the ideal two‐dimensional Markov parameters over a designated finite interval. To minimize the performance measures in this paper, the optimization technique proposed by Evans and Fischl for the time‐domain design of one‐dimensional digital filters is extended to this two‐dimensional case. Their technique has the merit of easy judgement of stability because the two‐dimensional digital filters are designed using a separable‐denominator two‐dimensional transfer function.
Theoretical treatment of arbitrarily shaped cut‐ends of dielectric optical waveguide
Authors: Nishimura Eiichi , Morita Nagayoshi , Kumagai Nobuaki 
Published: July 2007

AbstractA theoretical analysis is presented for the problem of reflection, transmission and radiation at an arbitrarily shaped discontinuity in a dielectric slab waveguide. An integral equation is derived for the electromagnetic field at the discontinuity and is solved by successive approximation. Of the Green's functions for this procedure, the one on the waveguide side is not the complicated form taking into account the exact boundary condition on the waveguide but an approximate form derived from geometrical optics approximations and mirror images. It is shown that the scattered wave is readily obtained once the electromagnetic field at the discontinuity is found. After discussing the numerical accuracy, numerical results are obtained for the reflected and transmitted waves and the scattering patterns for several shapes of discontinuity.
A study of twin‐waveguide systems for efficient surface wave excitation
Authors: Kitajima Hiroe 
Published: July 2007

AbstractIn general the transmitted wave in a twin‐film waveguide exists as even and odd modes when the higher order modes are absent. In this paper we consider the bandwidth of the propagation constant determined by the Gaussian beam diffraction angle and show the possibility of efficient surface wave excitation by means of a prism under the condition that the propagation constant difference between the even and odd modes can be suitably specified. When the transmitted wave passes through the gap and leaks into the side of the prism, the phase velocities of the even and odd modes become degenerate. When the coupling mode with degenerate velocity is excited by a Gaussian beam, the phase angle shift of the plane reflection constant with respect to the incidence angle is linear over the greatest range of incidence angles, so that the reflected beam will be very little distorted from the Gaussian type and a large beam shift can be obtained. Consequently the parameter accuracy required for high coupling efficiency can be relaxed. For simplicity, the two‐dimension problem is solved, the thicknesses of the gap and buffer film between the two guides for efficient surface wave excitation are obtained, and the amplitude of the reflected beam and the beam coupling efficiency for a Gaussian incident beam are found and investigated. For the optimum case the coupling efficiency can be as high as 94.7%.
A method of coding for correlative transmission systems and its application to a continuous phase modulation system
Authors: Yamada Takahiro , Harashima Hiroshi , Miyakawa Hiroshi 
Published: July 2007

AbstractTo transmit data reliably over band‐limited channels, several correlation digital transmission techniques such as continuous phase FSK, and partial response signaling have been developed. The reliability of correlative transmission systems can further be enhanced by utilizing the error correcting codes. However, it is very important to select a coding scheme that is suitable for a given transmission system. This paper proposes an encoding scheme using block code to improve the performance of certain correlative transmission systems whose transmitters' states can be represented by a simple shift register. The Viterbi algorithm is used in the decoding. The detection of symbols and the soft decision for the decoding of the proposed scheme are combined into a single process. The performance of the proposed method is demonstrated through its application to a duobinary FSK system with modulation index h = 0.5. The results indicate that the proposed scheme outperforms the MSK scheme in both the power spectral distribution and the error rate.
The design and radiation characteristics of dielectric‐loaded H‐plane cosecant‐square‐beam horn antenna
Authors: Sha Kokusho , Sato Kiyomi , Suzuki Michiya , Adachi Saburo 
Published: July 2007

AbstractAn H‐plane cosecant‐square‐beam horn antenna with a non‐planar aperture is described. A dielectric material is inserted into the horn and the aperture surface design is based on geometrical optics. The E‐plane pattern is easily controlled by changing the E‐plane aperture length. Nine antennas with various H‐ and E‐plane lengths are examined with respect to variations of several characteristics as a function of aperture length. A compact wide‐band H‐plane cosecant‐square‐beam horn with good characteristics was realized with an aperture angle of 60 degrees and an H‐plane aperture length of about 10 wavelengths. By changing the E‐plane aperture length the E‐plane pattern can be varied without degrading the cosecant characteristics in the H‐plane. In the tests the E‐plane half‐width was varied from about 44o to 72o by appropriate setting of the parameters. Hence the antenna can easily be designed in conformity with the service area and should therefore be useful for SHF broadcast and multiplex communications base stations. Further, in conjunction with an E‐plane cosecant‐beam horn antenna, both horizontal and vertical polarizations can be used in contiguous service areas to provide efficient use of the frequency spectrum.
Pattern separability of an analog threshold neuron model
Authors: Member Hisashi Mizuno, Regular 
Published: July 2007

AbstractIn the learning of a neural network model, the excitatory and inhibitory synapses and the threshold are modified. There is little discussion, however, as to what function the neural model can realize in the pattern separation when the synapses or the threshold is modifiable. This paper considers the analog‐threshold neuron model, and discusses the pattern separation performance of the neuron when excitatory synapse, inhibitory synapse and threshold are modifiable. As a result of the discussion, it is shown that the pattern‐separating function of the neuron is maximized when the excitatory and inhibitory synapses as well as the threshold are modifiable. Then a learning system is proposed where the excitatory and inhibitory synapses as well as the threshold are simultaneously modifiable. A model with the proposed learning scheme is analyzed. Finally, it is shown by computer simulation that the proposed model operates as the analysis predicts.
An associative memory model based on adaptive feature‐detecting cells
Authors: Ikeda Nobuhiko , Torioka Toyoshi 
Published: July 2007

AbstractThis paper extends the function of Amari‐Takeuchi's model by adding an inhibitory cell with nonlinear characteristics to their self‐organizing model of the feature‐detecting cell. The generalized model is shown to separate even patterns in mutually inclusive relation, forming the feature‐detecting cells for each of the patterns. It is shown that when a learning parameter in the model is modified, it can perform classifications under various criteria based on the similarity. Then an associative model based on the feature‐detecting cell is proposed. The model is composed of three subsystems: the feature‐detecting cell formation subsystem to convert in a self‐organizing way the input pattern to the specified feature set; the learning subsystem, which associates in a multiple way two kinds of signals by cross‐correlation; and the decoding learning subsystem, which restores the original pattern from the coded signal. The behavior of the model was examined under a multiple‐associative environment. The model can handle the mutual and self recalls in a unified way, and the memorized patterns associated with the key pattern are recalled successively. The result indicates a role of the feature‐detecting cell in the associative memory. It is also suggested that the model can be a basis for accounting for the high‐level associative function through association of high‐level notions.
Reliability of v‐grove optical fiber mass splice. improvement of splice loss temperature characteristics
Authors: Nagasawa Shinji , Sankawa Izumi 
Published: July 2007

AbstractWith the development of multiple optical cable and its high‐density assembly technology, the need for establishment of a technology for the mass splice of optical fibers has become urgent. Although the V‐groove mass splice method has been investigated, it has a special problem in terms of reliability because of the splice loss change with temperature. This paper proposes to determine the mechanism of change of the splice loss in order to solve this problem. The investigation has been carried out with the V‐groove mass splice which has been considered to be an important component for the mass splice of a high‐density ribbon fiber, and by examining in detail the splice‐loss temperature characteristic experimentally. The main cause of the variation of the splice loss has been found to be the change of the distance between the ends of two fibers due to the temperature change of the dimensions of the V‐grooved substrate. Although there is a slight effect due to the change of dimensions of the adhesive, it is useful to: 1) employ a material for the V‐grooved substrate which can form the substrate precisely and at the same time has a low thermal‐pansion rate; 2) to minimize the irregularity of the cut‐end surface of the fibers; and 3) to use an adhesive having a low thermal expansion rate. It has been found that even with the maximum initial cut‐end distance of 40 μm, the variation of the splice loss can be reduced to less than 0.05 dB against a temperature change between ‐30°C and +60°C by choosing the thermal expansion rate of the substrate to less than 3.3 × 10‐6/°C. This has been confirmed by the experiments with a prototype splicer using a ceramic V‐grooved substrate and epoxy‐based adhesive.
A new approach to time series analyses of chaotic orbits in one‐dimensional maps
Authors: Murao Kenji , Kohda Tohru 
Published: July 2007

AbstractThe one‐dimensional map is the simplest system in which there can be produced a random orbit called chaos. In the theoretical discussion of chaos, it is important to examine statistics and statistical properties of the chaotic orbit. In general, however, it is difficult, except for some special one‐dimensional maps, to examine analytically the statistics. This paper proposes a new method of time‐series analysis in order to obtain approximately the various kinds of statistics of the chaotic orbit, such as invariant density, autocorrelation function, power spectrum, and K‐S entropy. The essential idea of the proposed method is to replace the integral operator by the finite‐dimensional constant matrix ∼P, which is the finite‐element approximation to the integral operator. The approximate expressions for the statistics are given explicitly by the eigenvalues and eigenvectors of ∼P. Applying the proposed method to several mixing one‐dimensional maps and determining their statistics, it is concluded that the proposed method is useful in the time‐series analysis of the chaos in the mixing one‐dimensional map.
Long‐term reliability assurance for arc‐fusion spliced fiber
Authors: Matsumoto Michito , Haibara Tadashi , Katsuyama Yutaka , Tokuda Masamitsu , Members Tadatoshi Tanifuji, Regular , Member Mitsuru Miyauchi, Regular 
Published: July 2007

AbstractThe technology of low‐loss splicing for optical fibers is well established, but the long‐term reliability assurance of splices has not been studied sufficiently. With the wide introduction of optical cables much effort is being devoted to improve the reliability of arc‐fusion splicing and to estimate its lifetime. In this paper, improvement of the reliability of arc‐fusion splices by proof test is studied theoretically as well as experimentally and optimum conditions to assure long‐term reliability are established. As a result: (1) proof test theory can be applied to the arc‐fusion splice and it is possible to estimate the lifetime by knowing the values of parameters n and m; (2) the effect of proof testing is greatly dependent on proof stress as compared to proof time; (3) it is shown that the 20‐year failure probability can be suppressed below 10‐5 by applying proof stress of 0.15 GPa to the spliced fiber before being reinforced by the heat‐shrinkable tube method.
Movement perception of the chromaticness channel
Authors: Member Haruo Sakata, Regular 
Published: July 2007

AbstractPattern movement perception was investigated for the chromaticness channel with a random pattern consisting of two different colors, and the following results have been obtained.(1) With an isoluminant chrominance pattern, the movement was not perceived, but it was perceived when luminance difference was given to it.(2) Luminance difference needed for perception of pattern movement was larger for the (r‐g) channel than the (y‐b) channel; there is a component in the (r‐g) channel which works inphase with r and counter‐phase with g.(3) An intermittent movement chrominance pattern was masked by a continuous movement brightness pattern.A model is proposed which can explain the mechanism of perception of pattern movement.
Parallel‐pathway at periphery by spatio‐temporal frequency response
Authors: Member Haruo Sakata, Regular 
Published: July 2007

AbstractThis paper presents the result of measurement of the spatio‐temporal frequency response at the periphery (9 deg. from the fovea) on the retina. It is concluded from the following two points that the transmission characteristics of the peripheral vision are composed of a parallel combination of the temporal‐dominant system and the spatio‐dominant system. (1) Drawing equisensitivity curves on the temporal‐spatial frequency plane, the locus at high frequency is not a circle with the low‐frequency point as the center, but is approximately a straight‐line connecting the two axes. (2) There is a dip in the sensitivity near spatial frequency 1.2 cpd and temporal frequency 4.5 Hz. This indicates that the transmission is a combination of two systems (i.e., a spatio‐dominant system and temporal‐dominant system) with a phase difference in the temporal frequency response.
Theoretical analysis of optical fiber mode exciters constructed with alternate concatenation of step‐index and graded‐index fibers
Authors: Koyamada Yahei , Horiguchi Tsuneo , Tokuda Masamitsu , Uchida Naoya 
Published: July 2007

AbstractMode exciters which consist of alternate concatenation of step‐index (S) and graded‐index (G) fibers are used widely for the measurement of transmission characteristics (optical loss and baseband frequency response) of multimode fibers. This paper presents a theoretical analysis for the mode exciters based on geometrical ray optics approximation. The mode power distribution controlling effect of the exciters, excited mode power distribution in the test fiber, and accuracy and reproducibility of optical loss measurements are clarified theoretically. It is shown that optical loss measurements under steady‐state distribution can be done by using either SGS or GSG mode exciters which consist of either small core or low NA fibers.
Induced voltages on buried coaxial cable by direct lightning strokes
Authors: Member Toshiharu Nagano, Regular 
Published: July 2007

AbstractLarge numbers of failures occur in coaxial line repeaters which are located in areas subject to high thunderstorm activity. J. Kemp [3] has calculated the voltage induced in coaxial cables which undergo direct lightning strokes, but it has been found that the failure rate that occurs in actual installations may, in some cases, be as great as 100 times the failure rate calculated by Kemp's method. Transient phenomena are generally calculated by means of transforms using Heaviside's operational method, but in the case of transmission lines, because of the need to employ approximations, very significant errors can be introduced. In particular, many of the buried cables installed in recent years have metallic sheaths which are insulated from the earth and it has become necessary to take this fact into account to arrive at accurate results.Using line constants which take into account the skin effect, the induced voltage is here determined by numerical computation of the inverse Laplace transform and from this the failure rate is computed. The results are in almost perfect agreement with actual conditions. In addition, comparing the results obtained by this method with those obtained by the conventional method, we see that when the metallic sheath is insulated from earth the induced voltage becomes large because the lightning wave flowing into the metallic sheath is not attenuated very much and a high excitation voltage is therefore distributed over a long distance. Since this method permits quite complicated computations, it is expected that its application will facilitate development of suitable lightning protection methods.
An efficient algorithm for computing steady‐state response of nonlinear systems with time‐varying frequency inputs
Authors: Ushida Akio , Kume Tomohiro 
Published: July 2007

AbstractIn the steady‐state response in the nonlinear circuit, a number of frequency components is greatly affected by the amplitude and the frequency components contained in the forced input. In general, when there is only one frequency component as the input, only its harmonic components are produced. However, when it contains more than one frequency, the circuit will produce many frequency components by sum and difference as well as harmonics of the input frequencies. Especially, in the case of an FM input signal, in which the frequency is time‐varying, it is known that the input contains a large number of frequency components, depending on the modulation index. In the analysis of such a nonlinear system containing a large number of frequency components as the input, the solution method in the frequency domain such as harmonic balance, is not effective. This paper discusses the method of solution in the time domain for the nonlinear circuit with time‐varying frequency input. The waveform in the steady‐state response is expanded into Fourier series with periodically time‐varying coefficients, and the initial value is determined which produces the steady‐state response. The method is suited to the analysis of a nonlinear system with two frequency components as the input. In particular, it is seen that the method is especially effective in the analysis of steady‐state response in the nonlinear system with time‐varying frequency input.
A data flow control electronic exchange dataflex‐1
Authors: Yamashita Mikio , Members Minoru Akiyama, Regular 
Published: July 2007

AbstractThe controllers of the majority of existing stored‐program control switching systems employ architecture of Von Neumann. Shortcomings associated with such architecture include high OS overhead in multiprocessing, and difficulties in understanding the relationship between the control structure and the data flow of sequential programming. To overcome these problems this paper proposes a data flow architecture for controlling the switching system and describes the implementation of a prototype DATAFLEX‐1 (data flow exchange‐1). The basic operators of this prototype are implemented to approximate the task macro of the cell processing programs by using seven Z80A microprocessors to provide the necessary functions for intra‐office switching. The self‐documentary feature of the proposed programming technique, the clarity of data flow, the architectural modularity, the expandability of both the control functions and the scale of the proposed scheme are verified.
Power deposition in a block model of man exposed to the near field of a λ/2 dipole antenna
Authors: Uebayashi Shinji , Members Yoshifumi Amemiya, Regular 
Published: July 2007

AbstractIn a previous paper the authors calculated the power absorbed in the head of man holding a portable radio transmitter. It was found that the local absorbed power level exceeded the provisional safety level for ocular damage. For the calculations, however, the head of man was modeled as an isolated lossy sphere, and the effects of the human body and the ground on the absorbed power were not considered. This paper deals with numerical calculations of the absorbed powers in a realistic block model of a man taking into account the effects of the body and the ground. First, some fundamental characteristics are clarified for the calculations using a block model. Second, the absorbed powers in the head of a block model of a man standing on the ground are calculated for both cases when the model is in a plane‐wave field and in the near field of a dipole antenna. The numerical results are compared with those obtained in the previous paper employing the isolated sphere model. It is found from the results that the effects of the body and the ground are less in the near field of an antenna very close to the head than in the field of a plane wave, and that the local specific absorption rate in the eye exceeds the provisional safety level for ocular damage on several cases.