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27th International Congress on sound and Vibration, ICsV 2021

作者： Liu, Yu-Cheng Po-Chun, Ting Master's Program of Electro-Acoustics Feng Chia University Taiwan Bachelor's Program in Precision System Design Feng Chia University Taiwan Feng Chia University Taiwan

ISBN: (纸本)9788378807995

There are many various types of performances choosing to use indoor venues in recent years, but most of the arenas' acoustics in the early design is based on events, speeches and orchestra[1][2][3]. Now, due to the change of performance types, there is a need for change to increase the electro-sound and Louder-speaker system to enhance the sound pressure and music's dynamic at the venues[4]. At present, the venues for indoor performances are often in short supply, so the shows production team must perform in not so acoustically ideal conditions, such as balcony floor between the audience when in the large sound pressure, because the mezzanine factor caused the perception of the sound[5] and other roofless space is much worse, as the clarity and the overall sense of space are often a matter of audience reaction. © "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on sound and Vibration, ICsV 2021. All rights reserved.

关键词： Acoustic fields

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Quality Monitoring Methodology for Micro-shrinkage of Thick-Walled Injection Molded Components

SSRN

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ssRN 2022年

作者： Huang, Ming-shyan Chen, Jian-Yu Xiao, Yu-Qi Department of Mechatronics Engineering National Kaohsiung University of Science and Technology 1 University Road Yanchao Dist. Kaohsiung City824 Taiwan Bachelor’s Program of Precision System Design Feng Chia University 100 Wenhwa Road Seatwen Taichung City40724 Taiwan

sink mark degrades the surface quality of the thick-walled injection molded components. An effective method for quantifying sink marks, and predicting the occurrence of such defects as a function of the injection molding process parameters, are of significant interest in improving the molding quality. The present study proposes a method for measuring the micro-shrinkage using a simple image-processing technique. simulation and experimental trials are performed to investigate the effects of injection molding parameters on the quality of the polymer melt (as evaluated using quality indexes extracted from the pressure profiles within the chamber and the tie-bar elongation, respectively) and the quality of the final molded component. The sink mark is determined mainly by the holding pressure. The quality indexes revealed in this study are all highly correlated with micro-shrinkage. They provide a viable means of predicting the formation of sink marks and excessive micro-shrinkage in thick-walled injection molded components. © 2022, The Authors. All rights reserved.

关键词： Injection molding

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Optimal design of Investment Casting system for a stuffing Box with Pedestal of Centrifugal Pump: Computer simulations and Experimental Verification

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Journal of the Chinese society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao 2020年第5期41卷 551-563页

作者： Kuo, Jenn-Kun Huang, Pei-Hsing Tsai, Yu-Ting Zhong, Qi Chou, Chuen-shii Department of Greenergy National University of Tainan Tainan70005 Taiwan Department of Mechanical Engineering National Yunlin University of Science and Technology Yunlin64002 Taiwan Bachelor's Program in Precision System Design Feng Chia University Taichung40724 Taiwan Department of Mechanical Engineering National Pintung University of Science and Technology Pingtung91201 Taiwan

The stuffing box with pedestal (sBP) is a major component in centrifugal pumps (CPs). It is responsible for the transfer of load generated in the CP to the baseplate of the pump and finally to the ground. sBPs are usually fabricated using investment casting;however, this process is prone to residual casting defects, which can reduce mechanical strength and increase the likelihood of crack formation following long-term usage. In this study, the AnyCasting numerical simulation software package was used to optimize the investment parameters for the casting of an sBP in sUs304 alloy. Optimization efforts targeted the shrinkage cavity (based on retained melt modulus) and porosity defects (based on Niyama criterion). The results of preliminary simulations and experiments informed the establishment of five casting schemes for subsequent simulation. We used virtual thermo-dynamic sensors to determine the rate and direction of solidification in the mold cavity, and also investigated variations in the velocity of the molten metal at the inlets of the gating system as a function of time. The optimal casting parameters derived in simulations were assessed by fabricating an sBP via investment casting in a domestic foundry. Nondestructive testing based on X-ray analysis revealed none of the detrimental defects commonly associated with this type of casting. © 2020, Chinese Mechanical Engineering society. All right reserved.

关键词： Investment casting

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Finite Element simulation Analysis and Verification of Broadband silencers

Finite Element Simulation Analysis and Verification of Broad...

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2019 International Conference on Modeling, simulation, Optimization and Numerical Techniques(sMONT 2019)

作者： Y.C.Liu Y.C.Huang Yunjhe Tang Yungfang Chen Bachelor's Program in Precision System Design Feng Chia University

ISBN: (纸本)9781510885455

silencers have widespread applications. In industrial settings they are used at large-scale combustion, gas turbine, blower and compressor system junction points to control noise. The most common methods of noise elimination via silencer are varying of the size and cross-sectional area of the transmission pipe such that during sound wave transmission, non-uniform impedance is produced. Partial sound wave reflection is an echo source or consumes the energy of transmitted sound waves to achieve noise elimination. In this study, COMsOL Multiphysics, commercial finite element analysis and simulation software, was the main analytical tool. The aim of this study was to investigate the effects of variations in silencer structure on acoustic attenuation. Based on finite element method simulation, the optimal silencer geometry for noise cancellation was determined.

关键词： silencer transmission loss finite element simulation

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Variations in the acoustic measurement of earbud earphones in an ane-choic chamber due to changes in the earphone placement in ear Concha

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Canadian Acoustics - Acoustique Canadienne 2020年第4期48卷 29-40页

作者： Pawar, s.J. Liu, Y.C. Huang, Jin H. Department of Applied Mechanics Motilal Nehru National Institute of Technology Allahabad Prayagraj India Bachelor's Program in Precision System Design Feng Chia University Taichung Taiwan Department of Mechanical and Computer-Aided Engineering Feng Chia University Taichung Taiwan

The growth of consumer electronic products is encouraged by innovations and has stimulated the persistent development of earphones for high-quality sound reproduction. Earbud earphone is located in the concha of the human ear facing an ear-canal. The placement of earphones in the concha plays a remarkable role in the sound pressure level response of an earphone. In this study, ten earphones were tested for frequency response and total harmonic distortion using head and torso simulator in an anechoic chamber. Three positions and two orientations of earphones in the concha were identified for measurement. Based on the responses of all earphones at all orientations and positions, it is concluded that there is a variation in the frequency response and total harmonic distortion. Even though the variation is small in magnitude, its effect on sound perception, sound exposure, and the hearing threshold is phenomenal. Based on the proposition presented in this work and the safe daily sound exposure, it has been determined that the variation in the frequency response affects the perceived loudness of sound and can cause signif-icant differences in the daily sound exposure limit for a human being. © 2020, Canadian Acoustical Association. All rights reserved.

关键词： Frequency response

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Quality index design for online monitoring injection molding process 77

Quality index design for online monitoring injection molding...

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77th Annual Technical Conference of the society of Plastics Engineers, ANTEC 2019

作者： Chen, Jian-Yu Huang, Ming-shyan Nian, shih-Chih Tseng, Chien-Chou Bachelor Program of Precision System Design Feng Chia University Taiwan Dept. of Mechanical and Automation Engineering National Kaohsiung University of Science and Technology Taiwan Dept. of Power Mechanical Engineering National Taitung College Taiwan

Quality control is a crucial issue in the injection molding process with target of obtaining a high yield rate and reducing production cost. However, conventional injection molding acts like a black-box in which the flowing behavior of polymer melt within cavities is unseen, and the tuning of process parameters is heavily relied on operators' experience, design of experimental methods, or even trial- and-error. such approaches are not only time-consuming but also lack of assuring consistent injection molding qualities and quality control is then required. Nowadays with the advance of sensing technology, many sensors are available to detect the flowing behavior of polymer melt within mold cavities. Particularly the pressure, velocity, and temperature that affect the flowing ability of polymer melt can be detected in time. In other words, injection molding now has been transformed into a grey-box and a scientific viewpoint to tune process parameters can be realized. In this research, a quality index extracted from pressure profile is aimed for online quality monitoring. In addition, the clamping force increment quality index extracted from the tie-bar elongation which is detected by strain gauges attached on tie bars, free of invading injection mold structure, is paid much attention. To verify the feasibility of the designed quality index using to prediction the injection molded quality, varying barrel temperature, back pressure and rotational speed of plasticizing screw those can affect the plasticizing quality of raw materials are conducted in this investigation. Experimental results reveals that the clamping force increment as well as pressure peak index extracted from injection system pressure, nozzle pressure, end-of-filling cavity pressure profiles during injection molding are highly correlated with injection-molded qualities and thereby are feasible to be a good quality indicator. © 2019 society of Plastics Engineers. All rights reserved.

关键词： Polymer melts

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Tie-bar elongation based prediction of injection molding quality 77

Tie-bar elongation based prediction of injection molding qua...

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77th Annual Technical Conference of the society of Plastics Engineers, ANTEC 2019

作者： Huang, Ming-shyan Nian, shih-Chih Chen, Jian-Yu Dept. of Mechanical and Automation Engineering National Kaohsiung University of Science and Technology Taiwan Dept. of Power Mechanical Engineering National Taitung College Taiwan Bachelor Program in Precision System Design Feng Chia University Taiwan

Filling-to-packing switchover (also called as V/P switchover) is critical for assuring injection molding quality. An improper filling-to-packing switchover setting may result in various defects of injection-molded parts, such as excessive residual stress, flash, short shot, and warpage, etc. To enhance consistent molding quality, recent V/P switchover approach applies cavity pressure profiles requiring sensors embedded in mold cavities, which is invasive to mold cavities and even expensive. Instead of using cavity pressure sensors, this study thereby proposes a novel approach of identifying ideal V/P switchover timing using a tie-bar elongation profile. In this investigation, a dumbbell testing specimen mold is applied to experimentally verify the feasibility of the proposed method. The results showthat the mold filling and packing stages can be observed along the tie-bar elongation profile detected by mounting strain gauges on tie bars. Moreover, the varying process parameter settings including injection speed, filling-to-packing switchover point, and holding pressure, can be reflected in these profiles. By extracting their characteristics, the decision of filling-to-packing switchover is proved to be realistic. © 2019 society of Plastics Engineers. All rights reserved.

关键词： Filling

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Development of a systematic simulation procedure for 2D moving-coil loudspeaker by using COMsol multiphysics 25

Development of a systematic simulation procedure for 2D movi...

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25th International Congress on sound and Vibration 2018: Hiroshima Calling, ICsV 2018

作者： Liu, Y.C. Lin, Ku-sheng Feng Chia University Bachelor's Program in Precision System Design Taichung Taiwan Feng Chia University Master's Program of Electro-Acoustics Taichung Taiwan

ISBN: (纸本)9781510868458

This article develops a robust simulation procedure to predict the electromagnetic and acoustic properties of loudspeaker with commercial finite element software. The performance of loudspeaker is essentially difficult to analyse and predict, not to mention the conditions without the design specifications. With the aid of FEMM, FINEMotor, Klippel system, and soundCheck system, thus, a simulation procedure applied in the commercial finite element software-COMsOL Multiphysics is created in this article. Through the optimizations of magnetic resistance, relative permeability coefficient in the electromagnetic part, and Young's modulus and loss factor in the mechanical part, simulation results were in good agreement with actual measurements. After repeated verifications, this finite element simulation procedure is not only suitable for the predictions of loudspeaker performance, but also speed up the traditional simulation. © 25th International Congress on sound and Vibration 2018, ICsV 2018: Hiroshima Calling. All rights reserved.

关键词： Loudspeakers

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study on the Characteristics of Acoustic Radiation of Microspeaker Associated with Pattern of Diaphragm with Finite Element Method

Study on the Characteristics of Acoustic Radiation of Micros...

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2018 3rd International Conference on Computational Modeling, simulation and Applied Mathematics (CMsAM 2018)

作者： Yu-Cheng Liu En-Tzu Chang Hung-Wei Chen Bachelor's Program in Precision System Design Feng Chia University Master's Program of Electro-Acoustics Feng Chia University

The objective of this study is to investigate the acoustic radiation of Microspeaker based on various pattern geometries of diaphragm. The influence of first resonant frequency(f) is discussed, as are the radiation efficiency(sPL) and impedance curve(IMP). First, microspeaker geometry was reconstructed with CAD software(Creo). Four geometric pattern parameters, width, angle, depth, and quantity, of microspeaker diaphragm were defined and simulated with commercial finite element software-COMOsL Multiphysics. Results showed that the quantity and depth of pattern significantly influenced on the acoustic radiation, especially at lower frequencies. The stiffness of diaphragm decreased with increases in quantity and depth of pattern. In addition, f for both conditions shifted to lower frequency and bandwidth of microspeaker was extended. Increasing the angle of pattern, resulted in more solid diaphragm and slight increase in efficiency.

关键词： Microspeaker Pattern of diaphragm Finite element method

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Parametric Analysis on the Geometry of Magnetic system for subwoofer with FEMM

Parametric Analysis on the Geometry of Magnetic System for S...

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2018 3rd International Conference on Computational Modeling, simulation and Applied Mathematics (CMsAM 2018)

作者： Yu-Cheng Liu shu-Chien Wu Jiun-Yen Chen Bachelor's Program in Precision System Design Feng Chia University Master's Program of Electro-Acoustics Feng Chia University

The aim of this study is to investigate the distributions of magnetic flux and the variations in B curve for a novel design of loudspeaker magnetic system. Two different geometries, simulated with commercial finite element software-(FEMM) are presented, as well as an optimized design for the geometry of magnetic system. Results showed that changes in the inner side geometry obviously influence the distributions of magnetic field. In addition, the maximal magnetic force shifts to the position of lowest cross-sectional area. Meanwhile, B curve not only reduces the B level, but also loses the original uniformity in the air gap. Thus, the distortion caused from magnetic system will increase. Based on the original design, the new design not only maintains the flat B curve, but also saves on the amount of material of required for the magnetic system by around 31%.

关键词： subwoofer Magnetic flux B curve NRT Finite element method

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