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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.8, No.1
TABLE OF CONTENTS
Articles
Numerical Calculation of Sound Radiation from Structures Containing a Porous Layer Sandwiched by Double Walls with Krylov Type Acoustic Black Hole Takao Yamaguchi, Chihiro Kamio, Tomoki Tamura, and Yuta Hisamura Journal of Mechanical and Electrical Intelligent System, Vol.8, No.1, pp.1-11, 2025. Abstract: Noise reduction is an important technology to obtain comfort environment. In this report, we perform numerical computation of sound radiation from a structure containing a porous layer sandwiched by double walls. The cover plate in the double walls has a Krylov type acoustic black hole. All edges in the cover plate where the black hole exists, are set as free boundaries. Viscoelastic damping material is laminated on the top of the black hole. Numerical analysis is carried out to investigate sound radiation from this structure using FEM and MSKE method which is proposed by Yamaguchi et al.
Nonlinear response analysis for T-shaped structures having new acoustic black hole with residual thickness supported by nonlinear springs Takao Yamaguchi, Chihiro Kamio, Shinichi Maruyama, Tomohiro Tanaka, and Ryoichi Fujinuma Journal of Mechanical and Electrical Intelligent System, Vol.8, No.1, pp.12-23, 2025. Abstract: This paper reports numerical analysis using FEM with Model Strain Energy Method for structures having a T-shaped cross section supported by nonlinear concentrated springs under impact load. An edge of the rib plate in the T-shaped structure has an Acoustic Black Hole with residual thickness. A viscoelastic damping layer is covered on the black hole. Finite element for the nonlinear springs with hysteresis are expressed and are connected to the T-shaped structures modeled by linear solid finite elements in consideration of complex modulus of elasticity. We calculated modal loss factors and transient responses using eigenmodes including coupled motions between the nonlinear springs and the T-shaped structures. From the dominant modes and the impact responses, we clarified effects of the black hole with residual thickness on the nonlinear damped responses. By adding the black hole to the structures, modal loss factors increase. Higher modal loss factors are obtained due to set the residual thickness. As the amplitude of the impact force increases, the responses become complicated due to the nonlinearity, and include more super harmonic and subharmonic components. The nonlinear components are reduced by adding the black hole. The less nonlinear components are given due to set the residual thickness.
Development of an Evaluation System for the Flow Rate Characteristics of a Supply Unit in a Powered Air-Purifying Respirator: Dependency on Differential Pressure, Voltage, and PWM Duty Value Yusaku Fujii, Akihiro Takita, Seiji Hashimoto, Noriaki Yoshiura, Takao Yamaguchi, Kenji Amagai, Chihiro Kamio, Edwin Carcasona, and Ronald M Galindo Journal of Mechanical and Electrical Intelligent System, Vol.8, No.1, pp.24-34, 2025. Abstract: As a sustainable alternative to strict behavioral restrictions (lockdowns) during pandemics, the authors have been developing a low-cost, high-performance Powered Air-Purifying Respirator (PAPR) for public use. A PAPR supplies filtered air into a hood under positive pressure, thereby preventing the intrusion of external aerosols. To achieve both high protective performance and wearing comfort, it is essential to precisely understand and model the operating characteristics of the supply unit—specifically, how the airflow rate responds to differential pressure (ƒ¢P), applied voltage (V), and the duty value (n) of PWM control. In this study, the authors developed a dedicated evaluation system equipped with a pressure buffer that simulates the PAPR hood environment and a respiratory airflow simulator based on a piston-cylinder mechanism. Using this system, a multivariate polynomial regression model Qₑ(ƒ¢P, n) was derived to express the supply flow rate Q1 as a function of ƒ¢P and n. To validate the model, the estimated supply flow rate Qₑ was subtracted from the measured exhaust flow rate Q2 to obtain an estimated respiratory flow, which was then compared with the independently measured simulated respiratory flow Q3. The results demonstrated temporal and quantitative agreement between the two, confirming that noninvasive, real-time estimation of respiratory states, including inhalation/exhalation transitions, is feasible. The proposed evaluation system and regression model are promising not only for static performance testing of supply units but also as foundational tools for developing breathing-synchronized assistive control and enhancing the overall intelligence and comfort of PAPRs.
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