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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
Vol.6, No.1
TABLE OF CONTENTS
Articles
Research on Bifurcation and Modal Coupling in Nonlinear Vibrations of Symmetric and Asymmetric Perforated Beams Yue Liu, Shinichi Maruyama, Ken-ichi Nagai, Takao Yamaguchi, and Chihiro Kamio Journal of Mechanical and Electrical Intelligent System, Vol.6, No.1, pp.1-12, 2023. Abstract: Analytical results are presented on bifurcation and modal coupling in nonlinear vibrations of symmetrical and asymmetrical perforated beams in which both ends are clamped and subjected to lateral periodic force. In the analysis, the beam is divided into three segments, where the middle segment with a hole is modeled as a variable cross-section. The deflection of the beam is expanded with the mode shape function that is expressed with the product of truncated power series and trigonometric functions. Applying the Galerkin procedure, the nonlinear governing equation of the beam is reduced to a set of simultaneous nonlinear ordinary differential equation of motion in a multiple-degree-of-freedom system, by which nonlinear responses are obtained. The principal resonance of the lowest mode of the symmetrical beam is accompanied by the pitchfork bifurcation due to the sudden occurrence of super-harmonic resonance of the order-two of the 2nd mode. In contrast, the principal resonance of the lowest mode of the asymmetrical beam is accompanied by the saddle-node bifurcation, which is perturbed from the pitchfork bifurcation, because of the loss of symmetry of the beam. Furthermore, as the asymmetricity of the beam increases, the bifurcation occurs at the lower frequency.
Segmented DAC Unit Cell Selection Algorithm and Layout/Routing Based on Classical Mathematics Dan Yao, Xueyan Bai, Anna Kuwana, Kazuyuki Kawauchi, Yujie Zhao, Jianglin Wei, Shogo Katayama, Masashi Higashino, and Haruo Kobayashi Journal of Mechanical and Electrical Intelligent System, Vol.6, No.1, pp.13-30, 2023. Abstract: Semiconductor devices on silicon wafers suffer from random and systematic mismatches regarding the characteristics of MOSFETs, resistors, and capacitors, which can make the input and output relationship of the DAC non-linear. This paper investigates a unit cell selection algorithm based on the Euler Knight Tour algorithm as one of the random selection algorithms and also compares our previously proposed Magic Square and Latin Square unit cell selection algorithms. The Euler Knight Tour has properties of both the Knight Tour and the Magic Square. We show in simulation that it can improve the linearity of a segmented digital-to-analog converter (DAC) by cancelling systematic mismatch effects among unit cells, with comparable performance to the Magic Square and Latin Square algorithms. Also their layout and routing feasibilities are investigated.
Improvement of Physical Activity Estimation Using the Inertial Measurement Unit based Cane Measurement Device Takanori Yoshida and Chikamune Wada Journal of Mechanical and Electrical Intelligent System, Vol.6, No.1, pp.31-44, 2023. Abstract: Daily exercise is necessary for the elderly to stay healthy. In order for the elderly to engage in appropriate amount of activity, they need a way to record daily physical activity. Previous studies on physical activity estimation identified the need for new device as well as significant errors in physical activity as challenges. Therefore, in this study, we improved the problems of the inertial measurement unit (IMU)-based cane measurement devices that estimate physical activity in previous study. Specifically, we solved the dataset and activity recognition model. We also considered the data segment size and IMU combination patterns. We further evaluated the proposed method by physical activity estimation error. The 300 sample segment size was optimal, and there was no significant difference in accuracy by IMU combination patterns. The physical activity estimation error was 7.37%. The proposed system was more accurate and easier to estimate physical activity than existing activity meters.
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