bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transmission characteristics of polarization‐maintaining optical fiber with three‐layer elliptical cross section
Authors: Kuroda Michiko 
Published: July 2007

AbstractTo realize a single‐polarization, single‐mode optical fiber for high‐speed, long‐distance transmission, a three‐layer elliptical optical fiber is investigated and found to possess the characteristics of absolute single‐polarization and birefringence. Analysis of numerical computations is conducted by the eigenmatrix method using the Mathieu function for a three‐layer fiber with elliptical cross section and with common confocal point for the layers. The difference between propagation constants of the eHE11 and oHE11 modes is examined by using u ‐ w curves. The three‐layer structure permits a W‐type refractive index distribution, with the result that the HE11 modes have a cutoff region. The difference of cutoff frequencies between the eHE11 and oHE11 modes is produced due to the elliptical cross section. It is shown that this fiber can be used as an absolute single‐polarization fiber. Considering a nonaxially symmetric fiber with three‐layer elliptical cross section and flat cladding it is possible to obtain a large value of AB, the difference of propagation constants. This shows the theoretical possibility of achieving long‐distance transmission characteristics with a polarization‐maintaining optical fiber with three‐layer elliptical cross section.
Analysis of tap weight variance in FIA adaptive algorithms
Authors: Sakurai Masaru , Murakami Junzo 
Published: July 2007

AbstractThis paper analyzes the tap weight variance for the FIA‐ZF algorithm and the ADA‐MSE algorithm. The covariance matrix of the FIA algorithms is solved and the features of these algorithms are clarified. Covarianec matrices are also solved statistically for both the FIA Zero Forcing (ZF) algorithm and the FIA Mean Squared Error (MSE) algorithm. Comparisons are made with the simulation result. Finally, tap weight variance is studied for various noise levels and for the case of distorted input signals.
Unified analysis of sound field involving the driving system in time domain
Authors: Takagi Akira , Yoshida Norinobu , Fukai Ichiro 
Published: July 2007

AbstractRecently, it has become important, with the development of electroacoustic devices, to provide a systematic analysis of the electrical circuit, the electromechanical transducer part and sound field, taking their interactions into consideration. When the boundary condition of the sound field or the shape of the scattering object is complicated, numerical computation is more effective, especially when the analysis of time variation is required. This paper presents a numerical method of computation for the electrical circuit, transducer part and sound field, in which the entire system is represented by an electrical equivalent circuit. A formulation is made of the wave propagation and circuit element characteristics by Bergeron's method, with the time‐axis analyzed by the node equation. As a result, it became possible to analyze the entire system by electrical circuit analysis, clearly indicating the interactions among various parts. The method is based on the time‐response analysis, and the response to the pulse wave, for example, can be calculated on the time axis. As examples, some basic problems with sinusoidal input in two‐ and three‐dimensional space are analyzed, and the results are compared with those of theoretical analysis. A computation is also made for the case where the voltage and current at the transducer input are affected by the reflected wave of the sound field through the vibrating membrane, indicating the feature of the proposed method where the interactions in the system can clearly be demonstrated.
Automatic rounding error estimation and its applications. Solution of linear equations, Newton's and Mcauley's methods
Authors: Kinoshita Eisuke , Kosako Hideo , Kojima Yoshiaki 
Published: July 2007

AbstractNumerical computations are usually performed by floating arithmetic. Since the operations are performed by a finite number of digits, inevitably a rounding error is produced which is difficult mathematically to handle. This is because associative and distributive laws do not in general apply to the rounding operation. This paper describes a method which estimates the rounding error without using an analytical method. The number is represented by describing simultaneously the approximate value and the error. In parallel to the result of operation, the rounding error produced in that operation is determined and then summed for each operation. When a series of operations is completed, the range of existence for the result can be determined from the result of computation and the sum of errors. From the viewpoint that an unreliable number should not be given as output, the upper and lower limits of the range of existence for the result are given as output, indicating the extent to which the result of computation can be relied upon. It is shown that the proposed method is applicable to the sweeping‐out method, Gauss‐Seidel's method, Newton's method, and McAuley's method.
Absorbing rubber sheet mixed with carbon for X‐band marine radar frequencies
Authors: Shimizu Yasutaka , Nishikata Atsuhiro , Suzuki Shoichi 
Published: July 2007

AbstractThe conventional rubber radio wave absorber consisting of a rubber sheet mixed with ferrite is quite heavy. In order to reduce its weight the authors use chloroprene rubber with carbon added. The dielectric constants are measured using such absorbers with various kinds of carbon. Anisotropy generated in the dielectric constant during rolling is also investigated. Based on these data a radio wave absorber is designed and fabricated for X‐band marine radar (9.4 GHz). The practical utility of this radio wave absorber is confirmed. The present absorber has half the weight of the ferrite‐rubber absorber and hence is useful for covering large bridge structures.
Phenomenon of synchronization in a multimode oscillator with rational ratio frequencies
Authors: Kuramitsu Masami , Takase Fuyuto , Nitta Hiroyuki 
Published: July 2007

AbstractThis paper describes the synchronous oscillation in a multimode oscillator composed of an active element and several resonators with rational ratio frequencies. Using the concept of the averaged potential we proposed previously, we show that the ideal waveform minimizing the loss of the active element is generally the square wave or the stair‐step wave switching the minimal voltages of the active element voltage potential. Then, we can predict that the system has rational frequencies, the approximate square waves composed of these frequency components are excited stably by the synchronization. This synchronization phenomenon is confirmed by the simulation. An efficient algorithm for obtaining all of the stable synchronous oscillations is presented. The algorithm is performed by expressing all the synchronous oscillation waveforms by symbol trains according to their peculiar waveforms and calculating the initial values from the symbol trains. This method is applied successfully to the simulation of the oscillator where the active element is expressed by the cubic‐ or fifth‐power nonlinearity.
Traffic analysis of TSTST time division speech paths
Authors: Akiyama Minoru , Tanaka Yoshiaki , Seguel Julio , Fukushima Hideaki 
Published: July 2007

AbstractThis paper describes the traffic analysis of TSTST type building block speech paths. The main component of this configuration is the switch module. It consists of a small‐sized T‐switch and part of an S‐switch. TSTST configuration is used to make a large capacity switching system with these switch modules. Conventionally, TST configuration was used mainly for speech paths. However, the number of stages must be increased in order to make a large capacity switching system using switch networks with small channel multiplicity. The traffic handling characteristics of TSTST are almost the same as those of TST with the same size T‐switch and the same total number of channels, and this configuration can be applied to a wide range of speech path sizes. Furthermore, flexibility and reliability can be improved by adding alternative links to the fundamental TSTST configuration, and thereby link efficiency can be improved by a few percent compared with the configuration without alternative links.
Stable power‐combining mode operation of a cylindrical cavity multiple‐device oscillator
Authors: Fukui Kiyoshi , Nogi Shigeji , Sato Toru 
Published: July 2007

AbstractPresented in this paper is a discussion of the output power combining capability and the stable operation of the desired mode in a cylindrical cavity multiple‐device oscillator, in which several devices are placed inside a cylindrical cavity to combine the output of all devices by way of coupling with the TM020 mode of the cavity. A lumped element equivalent circuit is first derived that has the fundamental characteristic of the oscillator structure. From the modal analysis based on this equivalent circuit, it is found that the oscillation output as the sum of the available powers of individual devices can be obtained in principle at TM010 and TM020 modes. It is also noted that the TM020 mode cannot be a stable mode when it is chosen as the desired mode and the TMm10 mode (m ≧ 1) is generated as a stable rotational or standing wave mode. Then we discuss the method of loading the resistor for suppressing unwanted modes in which only the desired output combining mode is stable. Finally, an eight‐device oscillator with a simple structure fabricated for trial is used in experiments of power combining and unwanted mode suppression and the results of the analysis of the modal analysis are qualitatively confirmed.
Scattering of a plane electromagnetic wave by the discontinuity of impedance planes
Authors: Kage Yoshio , Aoki Kazuo , Yoshidomi Kuniaki 
Published: July 2007

AbstractA method often used for analyzing the problem of scattering by a lossy dielectric slab is an approximate one in which the dielectric slab is replaced with an impedance plane with an infinitesimal thickness. We analyzed rigorously the problem of scattering from the discontinuity between two dielectric slabs by means of the Wiener‐Hopf method. The numerical calculations in such a method is quite complicated. If this problem can be replaced with that of two impedance planes, the analysis and computation can be simplified significantly.In this paper, the scattered field of the E wave by the discontinuity of two impedance planes is analyzed by the Wiener‐Hopf technique. The results are compared with the rigorous solution of the scattered E wave by the discontinuity of two dielectric slabs. From the numerical results of the two problems, it is found that the scattering patterns agree well if the slabs are lossy (σ/ω ⩾ 1.0) and the thickness is more than the skin depth. It is also found that the magnitude of the scattered wave almost agrees if the thickness is about one wavelength. Hence, if the slab thickness is more than a certain value for the E wave with the electric field component normal to the incident plane, the impedance plane approximation is effective for the lossy dielectric slab problem.
Minimum round‐off noise realizations of separable‐denominator two‐dimensional digital filters
Authors: Kawamata Masayuki , Higuchi Tatsuo 
Published: July 2007

AbstractIn real‐time two‐dimensional digital filters using a special‐purpose processor with fixed‐point arithmetic, the word length should be as small as possible to realize the desired processing accuracy. A digital filter which is affected least by quantization should be used. From such a viewpoint, this paper aims at the synthesis of the two‐dimensional digital filter structure with the separable denominator and with the minimum round‐off error. As the first step, the two‐dimensional digital filter with the separable denominator is represented by the local state‐space model. The result of analysis for the round‐off error already made by the authors is outlined. Based on these results, the synthesis of the structure with the minimum round‐off noise is formulated by equivalent transformation. A method of synthesis is presented. The two‐dimensional digital filter with the separable denominator and with the minimum roundoff noise, which is obtained by the synthesis method in this paper, is shown to be of a structure which does not produce an overflow oscillation for zero input. Finally, the effectiveness of the proposed method is shown by a numerical example.
Performance of a coded 8PSK modem with a viterbi decoder using simplified metric calculation
Authors: Miyake Makoto , Fujino Tadashi , Umeda Yoshiaki , Yamazaki Eizo , Fujiwara Ken‐Ichi 
Published: July 2007

AbstractRecently, there has been increased interest in coded octal phase‐shift keying (8PSK) modulation for satellite communications, in which convolutional encoding and Viterbi decoding are combined with 8PSK modulation and demodulation. The problem in this paper is how to simplify the process of metric calculation in a Viterbi decoder and realize reduced hardware complexity and increased operating speed of a coded 8PSK modem. An analytical expression is introduced for the performance of a coded 8PSK model with such a simplified Viterbi decoder. The expression is then applied to a typical coded 8PSK modem employing the Ungerboeck code of rate 2/3 and with constraint length ν=2. Effects of simplifications in the Viterbi decoder on the bit error rate (BER) performance of the model have been evaluated. Results in this paper would be useful in the design of future coded PSK modems, since it enables a designer to assess the tradeoffs involved in the simplifications and to realize modems with reduced hardware complexity for highspeed applications.
A proposal for searching for electromagnetic wave sources by using a synthetic aperture technique
Authors: Kikuchi Jun‐Ichi , Sato Motoyuki , Nagasawa Yoji , Sato Risaburo 
Published: July 2007

AbstractUnwanted electromagnetic waves radiated from equipment making use of electromagnetic energy create numerous societal problems. The prevention of these problems has been studied extensively. In this paper, a method for estimating the location of the unwanted electromagnetic waves is studied. Since it is difficult to make the antenna aperture large especailly at low frequencies, a search for electromagnetic wave source via a synthetic aperture technique is proposed. In the estimated electromagnetic source distribution by this method, images similar to the antenna sidelobes appear. It is demonstrated by computer simulation that the images can be suppressed by use of the synthetic aperture method with subarrays or use of Mill's cross method. Discrepancies between the true source location and the estimated location have been found in regard to the synthetic aperture length and the geometrical relationship with respect to the aperture center. It has been found that the antenna configuration with the synthetic aperture length of 10 λ can estimate an electromagnetic wave source within 10 λ square with accuracy of less than 1/4 λ square. Therefore this method is sufficiently practical if the location of the source is restricted somewhat.
Finite–element analysis of discontinuities in a dielectric slab waveguide
Authors: Hirayama Koichi , Koshiba Masanori , Suzuki Michio 
Published: July 2007

AbstractFor discontinuity problems in a dielectric waveguide, a method for analysis is proposed in which a finite element technique and an analytical solution are combined. A systematic formulation is carried out for both the TE and TM modes. A hypothetical wall is provided in the region outside the waveguide so that the open region waveguide is treated as a closed system. In such a closed system, the mode spectrum becomes discrete and the analysis is simplified. However, the location of the hypothetical wall needs to be chosen carefully. The solution changes violently near the cutoff point of a higher order mode. In the present method, the location of the cutoff points of the higher order modes is calculated beforehand and the hypothetical wall is placed near the midpoint of the two adjacent cutoff points. If the hypothetical wall is placed at such locations, the solution depends much less on the locations. Hence, even if the hypothetical wall is located relatively close to the waveguide, the approximate solution is accurate. In order to demonstrate the fact that the present method can be easily applied to an arbitrary discontinuity, a complicated discontinuous structure such as the core deformation at the splicing point of fibers has been treated. The analytical results have been shown for the scattering characteristics of the TE and TM modes at such junctions.
General expressions for the numbers of spanning trees in interative graphs classified by contact patterns of cells
Authors: Sato Kimio , Onodera Rikio 
Published: July 2007

AbstractThis paper presents a general formula for the number of spanning trees in an iterative graph. This graph is obtained by connecting k m‐cycles Cm and k n‐complete graphs Kn by branch‐contact or by point‐contact into ladder, prism, wheel, step, sector or mill‐wheel types, and 2 × k of them into a lattice type, respectively. A conventional method using a determinant with k, m and n as parameters is used to determine the number of trees in these iterative graphs. In this method there are many cases where the expansion of the determinant is not easy. Thus as an alternative method for such cases we introduce for the first time an electrical network calculation method for driving point resistance conductance in a unit resistance network whose interconnection structure is represented by a graph. In addition, we introduce a series parallel partition method of branches of a graph, so that the derivation of a general formula for the number of trees in an iterative graph is simplified. Then for individual iterative graphs, we show concrete examples and the results of the determination method obtained by mixing the above‐mentioned three methods appropriately.
Markov chain analysis of a single‐stage transfer‐type automated manufacturing system—two‐machine parallel system
Authors: Nakamura Takashi , Ohuchi Azuma , Kaji Ikuo 
Published: July 2007

AbstractFrom a microscopic viewpoint in consideration of the loading control of work‐pieces and the machine layout, the dynamic behavior of a single‐stage transfer‐type automated manufacturing system with two same‐type machine tools placed in parallel at both sides of a loop conveyor is modeled and analyzed. The processing time obeys a general distribution and to avoid the collision, workpieces are assigned at random to moving slots at regular intervals on the conveyor. The state is defined on the basis of the physical states of the two machines at the arrival epoch of each slot and the system behavior is formulated as a Markov chain. Performance measures such as production rate and inflow rate are obtained by finding the equilibrium state probabilities. Especially, in case of exponential processing time distribution, their explicit expressions are derived. Numerical examples are shown and the difference between the two‐machine parallel system and the two‐machine series system [5] is discussed. Moreover, the production rates for the cases of normally distributed processing time and fixed processing time are calculated numerically and then the validity of the analysis results under the exponential assumption is discussed.
Loss reduction of the magnetostatic forward volume wave delay line using the YIG film
Authors: Tsutsumi Makoto , Tanaka Katsuyuki , Kumagai Nobuaki 
Published: July 2007

AbstractThis paper describes from the experimental viewpoint the group delay characteristics, particularly, loss characteristic (both propagation loss and transducer conversion loss) of the magnetostatic forward volume wave in a YIG film nonuniformly magnetized with a conical pole piece. The maximum time delay of 3 m̈s has been observed at 4 GHz and the propagation loss has been found to be 15 dB/m̈s. It has been found that the delay time minimizing the loss increases with the degree of nonuniformity of the magnetic field. A theoretical study has been made for the experimental results. It is assumed that a lens‐like medium is formed in a YIG film by means of the nonuniform magnetic field. From the lens theory, the focal length for the magnetostatic wave beam has been obtained and the focal length is estimated as a function of the delay and the degree of nonuniformity of the magnetic field. It is concluded that the focal point of the magnetostatic wave beam is formed on the receiving transducer if the loss is minimum, and that the loss is related mainly to the conversion loss.
A method using a trial function with unknowns to solve approximately fredholm integral equations of the first kind
Authors: Kurosu Takashi 
Published: July 2007

AbstractThis paper discusses the approximate solution of Fredholm's integral equation of the first kind, using the trial function containing unknown parameters. The unknown parameters are determined from the observed data and the estimated values using the least‐square method. The method is applied to the remote sensing problem, where the method can be applied without a priori knowledge about the true solution, even if few observed data are available to estimate the correct change of the physical variable (true solution). A method is demonstrated which can examine the adequateness of the chosen trial function. Discussions are made for the accuracy of the approximate solution and the error of the physical variable which is estimated from the approximate solution.
Both E‐ and H‐plane converging lens applicator for deep and localized microwave hyperthermia
Authors: Nikawa Yoshio , Moris Shinsaku , Katsumata Tohru , Kikuchi Makoto 
Published: July 2007

AbstractIn hyperthermia which has recently been considered as a promising cancer therapy, heating of tissue is produced by dielectric heating by microwave energy. On the other hand, owing to the substantial attenuation of electromagnetic waves within a biological body, it is not possible to heat a cancer located deep inside the body. The authors have proposed an antenna (applicator) for electromagnetic irradiation of the biological body with a converging effect in the magnetic field plane (H‐plane). In this paper, a new applicator is proposed which has a converging effect in the electric field plane (E‐plane) in addition to the previous effect in the H‐plane. Such an E‐ and H‐plane converging lens applicator has been fabricated. In addition to the theoretical analysis, a heating experiment has been performed for a phantom model of human muscle. The theoretical and experimental results agree well. If a surface cooling device is added in the applicator, the depth of the maximum temperature point is found to be more than twice that of the conventional waveguide with an identical aperture size. A similar theory has been used at 2450 MHz in the simulation of heating of a biological model considering the presence of cancer. Although the skin depth of the muscle layer at this frequency is 17 mm, the range of heating in the hyperthermia reached more than 30 mm (about twice the surface skin depth), indicating the effectiveness of the applicator developed here.