Acta Medica Okayama 47 1 2005 Convergence acceleration and accuracy improvement in power bus impedance calculation with a fast algorithm using cavity modes 2 9 EN Zhi Liang Wang Osami Wada Yoshitaka Toyota Ryuji Koga Based on the cavity-mode model, we have developed a fast algorithm for calculating power bus impedance in multilayer printed circuit boards. The fast algorithm is based on a closed-form expression for the impedance Z matrix of a rectangular power bus structure; this expression was obtained by reducing the original double infinite series into a single infinite series under an approximation. The convergence of the single series is further accelerated analytically. The accelerated single summation enables much faster computation, since use of only a few terms is enough to obtain good accuracy. In addition, we propose two ways to compensate for the error due to the approximation involved in the process of reducing the double series to the single series, and have demonstrated that these two techniques are almost equivalent. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 39 1 2005 A Scheme to Classify Clouds with the Depolarization Ratio andBackscattering Coeffcient Measured by Lidar 93 101 EN Kengo Iokibe Yoshitaka Toyota Osami Wada Ryuji Koga The optical properties of clouds were measured with a polarization Mie lidar during April, 2004 and investigated to categorize the particles detected by the lidar. The cloud layers were categorized into five types according to the depolarization ratios, as follows: (I) constant and small (less than 5%); increasing with height (II) nearly from 0% and (III) from about 50%; (IV) large and varying with the backscattering coefficient; and (V) sharply decreasing. This categorization of clouds enabled us to separate aerosols from clouds in a lidar signal. Comparison of the backscattering coefficients between clouds of types (I) and (II) suggested that the depolarization ratio induced by multiple scattering in dense clouds does not depend on the particle density. Estimation of the particle phase for the five cloud categories was also examined. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 2003 Analysis of resonance characteristics of a power bus with rectangle and triangle elements in multilayer PCBs 73 76 EN Zhi Liang Wang Osami Wada Yoshitaka Toyota Ryuji Koga <p>One of the major sources of radiated EMI is attributed to power bus resonance in a printed circuit board (PCB). A fast algorithm, combined with the segmentation method, is applied for calculating resonance characteristics of a power bus whose pattern consists of several segments of rectangles and/or right-angled triangles. Good agreement between the calculated and measured results demonstrates the usefulness and accuracy of the fast algorithm and the segmentation method. </p> No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 37 2 2003 Aerosol Extinction Coefficient Continuously Measured with Polarized Mie Scattering Lidar 89 97 EN Kengo Iokibe Yoshitaka Toyota Osami Wada Ryuji Koga Aerosol extinction coefficients of clouds and dust were continuously measured in the year of 2002 with a polarized Mie-scattering lidar controlled by an automatic and remotely operating system utilizing internet services. Measured cloud extinctions were greater than 1.0 km(-1) below the altitude 6 km, 0.17 - 1.0 km(-1) between 6 and 10 km, and 0.091 - 0.3 km(-1) beyond 10km. Extinction of dust were 0.10 and 0.20 km(-1) for Asian dust and 0.057 km(-1) for urban dust. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 2002 Application of segmentation method to analysis of power/ground plane resonance in multilayer PCBs 775 778 EN Zhi Liang Wang Osami Wada Yoshitaka Toyota Ryuji Koga <p>The fast algorithm developed for calculating the resonant characteristics of the power/ground planes in multilayer PCBs, is extended to the case of that the pattern of the power/ground planes consists of several "segments" of rectangles, using the so-called segmentation method. Good agreements between the calculated and measured results have demonstrated the usefulness and accuracy of our fast algorithm and the segmentation method.</p> No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 37 1 2002 Pulse Timing Control of Multiple Signal Interconnections for Reduction of EMI 51 60 EN Akihiro Namba Yoshitaka Toyota Osami Wada Ryuji Koga This paper presents pulse timing control method to reduce electromagnetic emission from multiple signal interconnections. Pulse timing control gives intentional skew between signals. Higher order harmonics are canceled because of the difference of the phase between the signals. Using this property, pulse timing control can reduce the EMI in wide frequency range. In this paper, we show that radiated electromagnetic field from multiple signal lines reduces its intensity to the same level of the field from one line by using pulse timing control. The result of measurement shows that EMI from four differential transmission lines can be reduced more than 9 dB in the 200 MHz to 800 MHz frequency range. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 36 2 2002 Application of Transfer Matrix Method with Signal Flow-Chart to Analyze Optical Multi-Path Ring-Resonator 73 82 EN Iip Syarif Hidayat Yoshitaka Toyota Osamu Torigoe Osami Wada Ryuji Koga A multi-path ring-resonator (MPRR) was proposed to extend FSR of ring resonator. However, it is complicated to analyze the MPRR by using well-known analysis techniques such as scattering matrix or other numerical methods. This paper describes procedure for deriving transfer matrix by means of signal flow-chart to analyze the MPRR. We do not need complicated calculation for steady state analysis because transfer matrix elements are formulated clearly. As a result, The calcultaion time in this method can be reduced 1/3 to 1/20 times compared with using scattering matirx method. Furthermore, a transmittance characteristics of the MPRR at FSR extension-factor of 10 will also be shown. This suggests that analysis of other types of the MPRR by using this method can be performed simply and take a shorter time. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 36 2 2002 Experimental Verification of Common-Mode Excitation Model for PCB Having Partially Narrow Return Path 83 89 EN Tetsushi Watanabe Osami Wada Ryuji Koga Yoshitaka Toyota Takuya Miyashita Suppression of common-mode current is important to achieve electromagnetic compatibility of high-speed and high-density electronic circuits. The authors have focused on the common mode current flowing on a printed circuit board (PCB) to explain the excitation mechanism. A narrow ground pattern in microstrip structure excites common-mode current. In the previous paper, the authors explained the mechanism of common mode generation by means of "current division factor" for simple PCBs. The estimated radiation from a simple PCB agreed well with measured one. In this paper, the authors extend the theory to be applied to generalize ground structure. The validity of the theory is confirmed by comparing the measured radiation and the estimated value using the common-mode model for a test PCB. The estimated radiation agrees well with the measured one within 3 dB up to 900 MHz. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 34 1-2 2000 Depolarization properties of Asian dust (KOSA) measured hyLIDAR in Okayama in the spring of 1998 27 37 EN He Wei Ryuji Koga Kengo Iokibe Osami Wada Yoshitaka Toyota In spring of 1998, Asian dust was observed with a Mie LIDAR in Okayama University, which can measure depolarization ratio. Three events of intense Asian dust were occurred in the period and medially detailed structure of atmosphere was found after examining records. Asian dust was distinguished from water droplets and the possibility to study three dimensional dynamic structure of atmosphere were demonstrated. No potential conflict of interest relevant to this article was reported.