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Journal of Mechanical and Electrical Intelligent System (JMEIS, J. Mech. Elect. Intel. Syst.)

An international open-access peer-reviewed journal

ISSN 2433-8273




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Vol.3, No.2






Mathematical Analysis and Design of Parallel RLC Network in Step-down Switching Power Conversion System

Minh Tri Tran, Yifei Sun, Noriyuki Oiwa, Yasunori Kobori, Anna Kuwana, Haruo Kobayashi

Journal of Mechanical and Electrical Intelligent System, Vol.3, No.2, pp.1-30, 2020.

Abstract: This paper presents a novel circuit design technique and a stability test for an inductor type step-down buck converter. The model of this system is analyzed on both the time and frequency domains. The transfer function and the self-loop function of the power stage are derived and analyzed based on the widened superposition principle. The alternating current conservation technique is proposed to measure the self-loop function. Moreover, the charge and discharge voltages of the capacitor in the RLC of the power stage are analyzed by the energy propagation principle. Therefore, the balanced charge-discharge time condition is written by T = 2/ = 2(LC)1/2 = 4RC if the values of R, L, and C are chosen by the relation ǀZLǀ = ǀZCǀ = 2R. In overdamped case ǀZLǀ = ǀZCǀ < 2R, the power stage is unstable. The overshoot and undershoot phenomena of this network are improved by a parallel RLC circuit. Furthermore, the electro-magnetic interference noise of the switching control source is flat spread on every operation duty cycle of the control source by a frequency modulation technique. As a result, the step-down switching power network is designed so that the overshoot phenomena is perfectly controlled, the ripple level is very small (lower than 0.05 mV peak to peak), and the spectrum levels are kept below 10 V, which is compared to the desired set voltage of 5 V.

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Mathematical Model and Analysis of 4-Stage Passive RC Polyphase Filter for Low-IF Receiver

Minh Tri Tran, Nene Kushita, Anna Kuwana, Haruo Kobayashi 

Journal of Mechanical and Electrical Intelligent System, Vol.3, No.2, pp.31-51, 2020.

Abstract: The objective of this paper is to introduce a mathematical model of a 4-stage RC polyphase filter for a low intermediate frequency receiver in wireless communication systems. The transfer function of this filter is simply derived based on the widened superposition principle. In addition, the image rejection ratio of this network is also mathematically derived. At the baseband, the phase sequence orders of the wanted signals and the image signals are conflicted. The concepts of negative and positive Hilbert transform pairs divide the received signals into negative and positive polyphase signals. We express these signals on the angular frequency plane and plot the transfer function of this filter on both negative and positive frequency domains. The characteristics of the transfer function are mathematically analyzed and plotted on Matlab and SPICE. There is a tradeoff among signal to noise ratio, power loss and chip area. The values of resistors and capacitors are chosen based on the physical sizes of these components. The filter works at the 5 MHz center frequency and provides 36 dB image rejection ratio for a 10 MHz bandwidth receiver.

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Linear system identification of 1-dof vibratory system based on the Maximum Likelihood Estimation using the analytical solution of Fokker-Planck equation

Soichiro Takata 

Journal of Mechanical and Electrical Intelligent System, Vol.3, No.2, pp.52-60, 2020.

Abstract: This paper discusses a new identification method of linear single-degree-of-freedom system using Gaussian random vibration response. The propose method is based on the method of Maximum Likelihood Estimation (MLE). The likelihood function of proposed method is composed from the analytical solution of Fokker-Planck equation. The estimation formulas of unknown parameter are obtained by maximization of the original likelihood function. The obtained estimators correspond with population variance estimation of multivariate Gaussian model. Furthermore, the numerical identifications are conducted using the random vibration response by calculation result of 4th Runge-Kutta method. In the result, the estimation performance of the propose method is confirmed in terms of dependency of sample number and dependency of damping coefficient. Especially, the proposed method is implied the application to identification problem of large damping system. Quantification of large damping characteristic is important problem, because it is very difficult problem in conventional identification method. Moreover, the benchmark tests are conducted with Half-Power Method (HPM) based on the spectral analysis and Auto-Regressive Method (ARM) based on the time series analysis, respectively. The results of benchmark are shown in the accuracy of propose method is higher than its of HPM and ARM, respectively. Finally, the expansion to recursive estimation algorithm is conducted using MLE estimator of recurrence form. In addition, operation of the recursive algorithm is confirmed.

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International Space Station (ISS) Intelligent Human Centrifuge

Kazuhito Shimada, Yuji Kasai, Tomohisa Yuasa 

Journal of Mechanical and Electrical Intelligent System, Vol.3, No.2, pp.61-75, 2020.

Abstract: The International Space Station (ISS) astronauts need physiological countermeasures against microgravity (weightlessness on ISS). Recent abnormal findings in the eye (Space flight–Associated Neuro-ocular Syndrome, SANS) after 6-month-stay on the orbit tell us that current exercise measures are not complete. Ultimate solution should be the Artificial Gravity (AG) for astronauts.  Before closure of the ISS program, which is slated for 2024, we would like to have a test bed on the JAXA HTV-X cargo ship berthed to ISS, which verifies feasibility and usefulness of AG. ISS Multilateral Medical Operations Panel is interested in ISS AG for medical operations purpose.  Roscosmos, the Russian space agency, expresses intention to fly a human centrifuge on ISS. The overall design of AG by short-arm centrifuge with exercise function is not easy to come by, in terms of rotor cost savings. The authors propose to develop a human-powered centrifuge for ISS medical operations. To make AG effective and safe on manned spacecraft, incorporating advanced information processing mechanism into the AG machine should be the natural choice. Also, especially deep space exploration spacecraft which are exposed to high Linear Energy Transfer (LET) ion particle radiation, need to have onboard systems which are equipped with intelligent self-diagnosis and recovery function. Even low-earth-orbit (LEO) subsystems on ISS are known to be prone to space radiation damage.

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Leak-Before-Break and Plastic Collapse Strength Evaluation of Stainless Steel Piping with a Part-Through Notch by Using Double-Elastic-Deformation Method

Masato Ogawa, Masaaki Matsubara, Ryosuke Suzuki 

Journal of Mechanical and Electrical Intelligent System, Vol.3, No.2, pp.76-86, 2020.

Abstract: Nuclear power plants and chemical plants contain many piping, which degrades with age. As a result of a reduction in structural strength, guillotine breaking and rupturing can occur. Piping is subjected to tension and bending, but the influence of the load history on the integrity of piping is poorly understood. The present study is to develop an improved integrity assessment method for a stainless steel pipe with a part-through notch that takes into account the load history. This involved: (1) Determining the feasibility of the leak-before-break (LBB) concept for piping, (2) Evaluating the crack penetration stress and (3) Estimating the plastic collapse strength. Conclusions are as follows: (1) The LBB concept is found to be applicable, (2) The crack penetration stress is approximately equal to the maximum stress and (3) The plastic collapse strength of a part-through notched specimen can be safely estimated using the theoretical plastic collapse strength of a through-wall notched pipe.

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Short-Time INL Testing Methodology for High-Resolution ADC

Jianglin Wei, Nene Kushita, Keno Sato, Takashi Ishida, Toshiyuki Okamoto, Tamotsu Ichikawa, Hirotaka Arai, Lei Sha, Anna Kuwana, Takayuki Nakatani,

Kazumi Hatayama, Haruo Kobayashi

Journal of Mechanical and Electrical Intelligent System, Vol.3, No.2, pp.87-101, 2020.

Abstract: This paper describes a mass production testing methodology for integral nonlinearity (INL) of a high precision analog-to-digital converter (ADC) in short time. We consider its INL testing by separating its analog and digital parts: AD modulator and digital filter. The digital filter can be tested with the scan-path method. For the AD modulator part, its nonlinear curve of the DC input-output characteristics can be obtained using a DC input varying with a fine step, but it takes an enormously long time; it is not practical for mass production testing. So we consider a polynomial model of the AD modulator input-output characteristics and estimate its coefficient values from the fundamental and harmonics power by applying a cosine input and obtaining the modulator 1-bit output power spectrum with FFT. Its INL can be estimated from the coefficients accurately when the modulator I/O characteristics is continuous. Our simulation and experimental results show that significant testing time reduction can be achieved with the proposed method.

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