bluuebunny/crossref_metadata_2025_split huggingface dataset:
An analysis of a CVS multiberth station model via markov renewal theory
Authors: Kurihara Masahito , Kaji Ikuo , Nakada Katsuhiro 
Published: July 2007

AbstractA stochastic model has been developed for a CVS (Computer‐controlled Vehicle System) station with multiple parallel berths. In this model to study the effects of the number of berths on the behavior of a station, the following simplification is made in contrast to the conventional single‐berth station models. That is, loading and unloading times for each berth are assumed to follow the same exponential distribution regardless of the vehicle type, and the vehicle departure condition does not depend on the vehicle either. This type of model is formulated as a Markov renewal process and analyzed. As a result we have clarified the fundamental relationships between the number of berths and measures for evaluating a station such as the expected interval time of entrances, the departure rate, the entrance factor and the utilization factor of berths. Also, by examining the asymptotic characteristics of the expected interval time of entrances we have found the fundamental differences between a single berth station and a multiberth station, we have shown trade‐offs between the entrance factor and the departure rate and we have investigated the implications of increasing the number of berths. On the other hand, by simulations with a normal loading and unloading time distribution, we examined the effectiveness of the results of this paper for which an exponential distribution was assumed for the loading and unloading times.
An adaptive digital filter as a sinusoidal noise canceller
Authors: Ohmuro Takashi , Tachibana Yasuo 
Published: July 2007

AbstractAn adaptive filter is capable of varying its parameters adaptively in response to change in the characteristics of noise components. Thus it is effective for filtering out the nonstationary noise. This paper proposes an adaptive moving average filter (AMAF) for the extraction of desirable signal from the mixture of low‐frequency signal, white noise and narrowband sinusoidal noise. The implementation of AMAF is simply an extension of a moving average filter, and therefore is easy to implement and yet very effective for sinusoidal noise removal. As a special case, when the desired signal is a sinusoidal waveform, the design characteristics such as the noise attenuation index and the distortion rate of the AMAF are evaluated via computer simulation. The simulated results match the results obtained through theoretical analysis.
Design and performance of interference cancellation circuit
Authors: Kaitsuka Toshiyuki , Inoue Takeo 
Published: July 2007

AbstractThis paper presents an interference cancellation circuit based on a side‐lobe canceller. A new interference canceller is investigated in which the receiving interference signal of the auxilary antenna is modulated by a low‐frequency signal. When this signal is combined with the main antenna receiving signal, envelope detection is used and the error voltage of the interference canceller will be obtained from the detection of the low‐frequency signal and the phase. The interference cancellation effect is measured. The results show that above suppression ratio above 40 dB over a band‐with of 50 MHz can be achieved regardless of whether the signal is CW, FM or PSK or the undesired and desired signals are co‐channel signals. For a PSK signal even with D/U = −10 dB prior to cancellation, the bit error rate after cancellation can still be maintained equal to that without interference at all. Also a good suppression ratio can even be achieved in outdoor situations and the circuit presented here has obvious practical value.
Computer analysis of microwave planar circuit with impedance matrix
Authors: Jui‐Pang Hsu , Anada Tetsuo , Kaneko Hitoshi 
Published: July 2007

AbstractComputation of the wideband frequency characteristics of a microwave planar circuit with arbitrary shape requires computer processing because there are many parameters involved. However, if numerical calculations are carried out by computer from beginning to end, it is difficult to detect the amount of error and the error locations. The present paper resolves this problem. In addition conventional network theory is applied to the planar circuit and a computational method for easy understanding is introduced. To this end, the mode impedance looking at the planar circuit from the transmission line is defined Using this mode inpedance, network theory is employed to derive an expression of the effective impedance of the planar circuit projected on the dominant mode of the transmission line. Once the effective impedance is given,the frequency characteristics (S‐matrix) of the circuit can be computed over a wide frequency range. A computer program is developed for this procedure and applied to the analysis of a corner‐cut right‐angle bend. Potential problematic points of the program are discussed. It is also found that the optimum cut of the right‐angle bend can be computed and that the results so obtained agree with those known to date. Finally, it is pointed out that the present method is not only effective for the analysis of planar circuits, but also permits the analysis of higher‐order modes of planar circuits.
Optimum spatial filter for optical defocus sensing
Authors: Takemura Kohji , Tsutsumi Suteo 
Published: July 2007

AbstractSpatial filters for optical defocus sensing are discussed. The transfer function of the optimum spatial filter is derived from the condition that the gradient of the output with respect to the defocus distance is maximum. As an example of near‐ideal, physically realizable spatial filters, a plus‐minus checkerboard detector array is proposed. Dimensions of the detector elements for the checkerboard array are discussed in relation to the blur circle which is determined by factors other than defocusing, such as aberrations. Furthermore, a complex plus‐minus checkerboard reticle is proposed with a view to the wide range of Wiener spectrum of the input scenes from white spectrum to color spectrum. Experiments carried out using a plus‐minus checkerboard reticle demonstrated the capability of defocus sensing for a representative input scene, and the feasibility as a relatively short range finder.
Error probability analysis for multilevel digital signals in nonlinear channels
Authors: Okamoto Eiji 
Published: July 2007

AbstractIn digital microwave communication, the signal power is first amplified and then transmitted. However, power amplifiers have, in general, nonlinear characteristics. If such an amplifier is used in a linearly modulated tranmission system, the signal is subjected to nonlinear distortion. This makes analysis of the channel extremely difficult. If the number of levels in the transmission channel is few, the method of simulation can be applied for analysis. If the number of levels is large, the calculation becomes unwieldy. In this paper a simple analytical method to compute the intersymbol interference distribution and error probability of the output signal for a nonlinear transmission channel consisting of an amplifier with assumed cubic approximation for the input‐output characteristics, a transmitter filter and a receiver filter. This simplicity, derived from the fact that small intersymbol interference can be regarded as Gaussian noise in the aggregate, becomes the theoretical base. Also, the validity of the method is shown in comparing the error probability of the 4‐ary PSK system computed from the proposed method with that obtained by the simulation method.
Studies on the URN scheme for multiple access packet communication systems
Authors: Fukuda Akira , Hasegawa Yuji 
Published: July 2007

AbstractResearch on random‐access systems has been mainly based on the ALOHA system. However, such systems have an inherent risk of channel saturation due to the avalanche phenomenon of retransmitted packets. Therefore, several access systems, such as the URN scheme, have been proposed with consideration of adaptability to operational stability and load variation. In this paper we conduct a detailed study of the characteristics of the URN scheme, which is quite attractive in using the concept of direct access instead of random delay. Particularly, we study the influence of errors in estimating the number of packets awaiting transmission and the number of working terminals. It is concluded that these estimations need not be highly accurate. We then propose the H‐URN scheme, which has a slight overhead allowance for state estimation and is simply realizable. It will also be shown that the system characteristics are only slightly degraded compared with the ideal case. Further, the optimally controlled ALOHA system is studied with similar assumptions and methods and it is concluded that the URN scheme is superior in many respects. In addition, brief consideration will be devoted to several points which have not been studied sufficiently (e.g., problems of Ack and comparison with the TDMA system).
Long‐span installation machine for optical cables
Authors: Harada Kazuhiro , Saegusa Kentaro , Nakahira Mizuho , Tsuchiya Yuzo , Saito Takeo , Kurashima Takeshi 
Published: July 2007

AbstractLong‐span installation of optical cables is realizable by virtue of their light weight, small outer diameter, lower transmission line loss due to reduction of the number of splices, effective installation operations, etc. The authors have developed a novel long‐span installation machine for optical cables and a practical method of installation using this machine. The machine is found to be applicable in practice based on its fundamental composition of a pair of upper and lower caterpillars and a drive motor. The machine is distinguished by the following performance characteristics and functions: (i) it can pull cables of different OD and a pulling rope with a constant speed; (ii) the maximum pulling load is 300 kgf; (iii) the small, light‐weight equipment can be installed in any kind of manhole; (iv) the equipment can be operated by a utility power supply or portable generator; (v) there are control provisions for pulling force limitation and cable slack detection to facilitate automatic cable installation. Another advantage is the “distributed pull system,” wherein the pulling force needed for cable installation is distributively loaded over the cable length. In combination with these features, 14 optical cable sections were actually installed in a duct section of 18 km length. The average section length was 1,300 m and the maximum was as long as 2,500 m. As a result, the practical applicability of the above equipment was proved, showing that they satisfy the design criteria and functions and that there is no significant increase in cable losses after the installation operations.
Performance of millimeter‐wave detector using hot carriers in semiconductor
Authors: Kikuchi Kazuo , Furukawa Seijiro 
Published: July 2007

AbstractThis paper confirms in practice the wideband property of hot‐carrier microwave and millimeter‐wave detectors based on one of the high‐field effects in semiconductors. The dectection sensitivity as related to the diode structure and material is clarified. A p‐type Ge hot carrier diode is fabricated and its detection properties in the 10 GHz and 100 GHz bands investigated. Experiments show that the detection output is close to the value predicted from the structure and that the critical field of the semiconductor is obtainable from the bias‐voltage dependence of the detection characteristics. Finally, the figure of merit of materials for hot carrier bias is defined and guidlines for selection of materials are presented.
Reliability analysis and light preventive maintenance for a two‐unit parallel redundant system with bivariate exponential failure distribution
Authors: Sugasawa Yoshio , Kaji Ikuo 
Published: July 2007

AbstractThe degree of reliability is analyzed for the case where the preventive maintenance is applied to a parallel redundant system with two mutually related and repairable units. The bivariate exponential distribution (BVE) is introduced to describe the failure time distribution of two units that are not independent and mutually related. The reliability analysis of a repairable two‐unit parallel redundant system assuming a BVE failure distribution has already been reported. In this report, two methods of preventive maintenance are considered in the system with the BVE failure distribution. (1) Mutually related preventive maintenance is applied to the system only when both units obey the BVE distribution in failure time distribution. (2) Simultaneous preventive maintenance is applied to two units at prescheduled times. In the reliability analysis, the limiting availability of the system is calculated by using an extended regeneration point method in Markov renewal processes (MRP). In numerical examples, actual figures are assigned to each distribution and the time ratio of preventive maintenance for the two units is defined. Then the relationship between variations of the time ratios and the limiting availability is shown.
A new realization of a digital filter using a number theory transform
Authors: Edanami Takafumi , Tsujii Shigeo 
Published: July 2007

AbstractWith the number theory transform it is possible to perform a high‐speed convolution operation without multiplication and without numerical errors. For this reason, applications of the number theory transform to FIR digital filters have drawn attention. However, when the number theory transform is applied to digital filters, the operating word length becomes extremely large to prevent overflow at the output and this becomes a serious problem in actual hardware implementation. A method is proposed for expanding the dynamic range of the input and output in which the higher order difference of the impulse response is made another impulse response. It is shown that the proposed technique can greatly expand the input and output dynamic ranges. The method can also be combined with other techniques to improve its effectiveness.
Electromagnetic fields in twisted coordinate system
Authors: Yabe Hatsuo , Mushiake Yasuto 
Published: July 2007

AbstractThis paper introduces the twisted coordinate system and presents theoretical investigations of the existence of EM fields whose polarization plane rotates helically. First, concrete expressions for vector operations are derived and the vector wave equations in homogeneous and isotropic media are given in terms of covariant and contravariant components. Then the EM wave whose polarization plane rotates with the coordinate axis is investigated. The results show that propagating rotating polarized wave fields do not exist if the electric field has only a single twisted coordinate component and that the TEM wave exists only as circular‐polarized plane wave fields. By combining two circular‐polarized waves propagating in opposite directions, parallel electric and magnetic fields exist. The Hertz vectors suitable for this type of coordinate are derived and general equations for TE and TM mode EM fields are obtained.
Image bandwidth compression by pre‐compensative interpolation
Authors: Yanaka Kazuhisa , Saeki Norio , Saito Tadao , Inose Hiroshi 
Published: July 2007

AbstractIn the interpolative coding method, the pixels constituting the image are divided into “transmitted points” and “interpolated points,” and the former only are transmitted to the receiving end from the sending end. The latter are reconstructed by interpolation at the receiving end. Commonly, the original image values have been used for the transmitted point values as they are, or, the original image values have been properly lowpass filtered for the transmitted point values. However, judging from the entire image transmission system, the problem of how to determine the transmission point values at the sending end is closely related to the interpolation method at the receiving end.In this paper, we propose a pre‐compensative interpolation coding method such that given the interpolation method at the receiving end, the transmission point values at the sending end are determined so that the sum of the squared error between the transmitted points and interpolated points is minimized. We introduce two kinds of pre‐compensative interpolation coding methods for the case where the interpolation at the receiving end is linear, that is, a locally pre‐compensative interpolation coding method and a globally pre‐compensative interpolation coding method. According to a simulation using a standard image, the following effects have been recognized: the improvement of the SN ratio in comparison with existing simple linear interpolation which uses the original image values as the transmitted point values, and the decrease of the image quality degradation which seems to be caused by noise.
Edge effects in dipole phased arrays
Authors: Tokumaru Shinobu , Miyamoto Takuji 
Published: July 2007

AbstractIn the conventional analysis of the phased array, the array structure is considered infinite. This kind of approach is effective only for the investigation of the pattern from the centrally located elements and is not applicable for edge elements. In this paper, the edge effect of the dipole phased array is studied by introducing virtual generators in the analysis. The analysis method is applied for the calculation of the element pattern, current distribution, and active impedance of edge elements.
10 × 10 optical matrix switch
Authors: Yamamoto Hisao , Yokoyama Masaaki , Ogiwara Haruo 
Published: July 2007

AbstractThe design and test results of low‐loss optical matrix switches capable of switching between input and output of many fibers are described. Regarding the lens system, it is pointed out that if a large switching system is designed with the conventional optical collimating system used in small‐scale switches, loss due to caliber eclipse or mode conversion appears. However, if the telescopic lens system is used, it is theoretically possible to design a large‐scale switching method that the angular errors and pointed out regarding the optical path switching method that the angular errors and parallel motion errors of the optical lines after the optical paths are switched may possibly be reduced by using a pentagonal prism flexibly supported at an appropriate position and pushing it to a plane. Finally, a design method and the test results for a trial 10 × 10 matrix switch designed in accordance with this method are discussed.
Measurements and imaging method of blood flow profile in human heart
Authors: Chihara Kunihiro , Sakurai Yoshifumi , Matsuo Hirohide , Kitabatake Akira , Abe Hiroshi 
Published: July 2007

AbstractMeasurement and imaging of medical information invisible directly to human eyes are indispensable to improved diagnoses and to the delivery of quality medical care. This paper discusses development of a multichannel Doppler flowmeter for noninvasive measurement of blood flow in the human heart and the use of a computing system for visual representation of the blood flow profile. Data acquisition from multiple sites of the human body has been greatly simplified by the use of multichannel data acquisition systems developed through research. Also, a new method for discriminating the direction of blood flow, which is far better suited to digital computer processing, is here proposed and methods for displaying the flow using a color/gray level displaying system and a graphic terminal as a data output device are discussed to represent the flow information in a three‐dimensional and dynamic manner. Since it has been said in general that Doppler flowmetry is to some extent quantitatively inadequate the accuracy of the developed measuring method is determined by a simulated experiment. Although the data acquired from the measuring system are as yet processed off‐line, real‐time processing seems to be feasible if an arrow processor is employed.
Design of Pel adaptive DPCM coding based upon image partition
Authors: Saitoh Takahiro , Harashima Hiroshi , Miyakawa Hiroshi 
Published: July 2007

AbstractPel Adaptive DPCM Coding is an encoding method in which an appropriate DPCM coding loop is selected for every picture element. This is done by referring to only the past decoded values in the previously available multiple coding loops. Since each DPCM loop has been determined experimentally, it has been difficult to achieve efficient encoding, and the location of its compression limit remains unclear. In this paper, we have modified the previously proposed Block Adaptive DPCM coding method based on image partition and introduced a Pel adaptive DPCM coding method using multiple DPCM coding loops. In this method, nonhierarchical cluster analysis plays an important role. The coding performances of a Pel adaptive DPCM coding method differ depending on the subject images. The Pel adaptive DPCM designed by the above method yields a maximum performance advantage of 2.9 dB for the Girl and Couple images, 1.5 dB for the Aerial image, and none for the Moon. This is an improvement over the optimally designed block adaptive DPCM coding method proposed previously by the authors.
Synthesis and Properties of Tetrasubstituted 1,10‐Phenanthrolines and Their Ruthenium Complexes
Authors: Schäfer Bernhard , Görls Helmar , Meyer Susann , Henry William , Vos Johannes G. , Rau Sven 
Published: July 2007

AbstractThe synthesis and the photophysical properties of a series of tetrasubstituted phenanthroline (phen) ruthenium complexes of the type [Ru(tbbpy)2(phen‐R4)]2+ (tbbpy = 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine; phen = 1,10‐phenanthroline; R represents the substitution at 3‐, 5‐, 6‐ and 8‐positions with phenyl, 4‐tert‐butylphenyl and para‐biphenyl) and of a homoleptic [Ru(phen‐R′4)3]2+ (R′ = 4‐tert‐butylphenyl) are described. The phen‐R4 ligands were obtained in high yields usingSuzuki‐type coupling reactions. The solid‐state structure of 3,5,6,8‐tetraphenylphenanthroline is reported. The investigation of the photophysical properties of the free ligands reveals a pronounced effect of the aryl substitution on absorption and emission properties. These properties are mirrored in the corresponding complexes, which possess room‐temperature emission lifetimes of up to 2833 ns.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
On the Synthesis and Reactivity of Enantiopure Azetidines
Authors: Banide Emilie , Lemau de Talancé Vincent , Schmidt Grégory , Lubin Hodney , Comesse Sébastien , Dechoux Luc , Hamon Louis , Kadouri‐Puchot Catherine 
Published: July 2007

Abstractβ‐Amino alcohols with an (E)‐vinylsilane moiety were cyclized in the presence of N‐bromosuccinimide to afford diastereomerically pure azetidines. The chemo‐ and stereoselectivities of this bromocyclization are discussed. AM1 calculations support the observed chemoselectivity. The reactivity of the azetidines towards fluorinated reagents was studied. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Solid‐State Fluorescence Properties of Structural Isomers of Novel Benzofuro[2,3‐c]oxazolocarbazole‐Type Fluorescent Dyes (Eur. J. Inorg. Chem. 22/2007)
Authors: Ooyama Yousuke , Kagawa Yusuke , Harima Yutaka 
Published: July 2007

AbstractThe cover picture shows photophysical properties of structural isomers of novel benzofuro[2,3‐c]oxazolo[4,5‐a]carbazole‐type (3) and benzofuro[2,3‐c]oxazolo[5,4‐a]carbazole‐type fluorophores (4), which differ in the position of the oxygen and nitrogen atoms on the oxazole ring. Considerable differences in the absorption and fluorescence spectra were observed between structural isomers both in solution and in the solid state. The background shows the “Itsukushima Shinto Shrine” (in the UNESCO World Heritage List) in Hiroshima, Japan, where the research reported in the article by Y. Harima et al. on p. 3613 ff was performed.