• Title/Summary/Keyword: power transducers

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Computation of the Mutual Radiation Impedance in the Acoustic Transducer Array: A Literature Survey

  • Paeng, Dong-Guk;Bok, Tae-Hoon;Lee, Jong-Kil
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.2E
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    • pp.51-59
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    • 2009
  • Mutual radiation impedance becomes more important in the design and analysis of acoustic transducers for higher power, better beam pattern, and wider bandwidth at low frequency sonar systems. This review paper focused on literature survey about the researches of mutual radiation impedance in the acoustic transducer arrays over 60 years. The papers of mutual radiation impedance were summarized in terms of transducer array structures on various baffle geometries such as planar, cylindrical, spherical, conformal, spheroidal, and elliptic cylindrical arrays. Then the computation schemes of solving conventional quadruple integral in the definition of mutual radiation impedance were surveyed including spatial convolution method, which reduces the quadruple integral to a double integral for efficient computation.

A Study on the Detection of Surface Acoustic Waves by Noncontact Method (비접촉 방법에 의한 표면탄성파의 검출)

  • You, I.H.;Yoon, J.S.;Kim, D.I.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.10 no.2
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    • pp.56-62
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    • 1990
  • Surface Acoustic Waves(SAW) are generated on silicon wafer and $YZ-LiTaO_3$ substrate and are detected by noncontact method. As wave sources two kinds of transducers are used : the wedge-type of 20.0 MHz and fabricated Interdigital Transducer(IDT) of 20.8 MHz. SAW are modulated by the optical chopper frequency and are syncronized with a laser beam. In signal processing, intensity variations of light due to the intensity of SAW are analyzed using lock- in amplifier. From the results, corresponding to the applied input power, the intensity variations of a deflected light by corrugations on the substrates are increased and saturation phenomenon is observed.

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Electret-based microgenerators under sinusoidal excitations: an analytical modeling

  • Nguyen, Cuong C.;Ranasinghe, Damith C.;Al-Sarawi, Said F.
    • Smart Structures and Systems
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    • v.21 no.3
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    • pp.335-347
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    • 2018
  • The fast-growing number of mobile and wearable applications has driven several innovations in small-scale electret-based energy harvesting due to the compatibility with standard microfabrication processes and the ability to generate electrical energy from ambient vibrations. However, the current modeling methods used to design these small scale transducers or microgenerators are applicable only for constant-speed rotations and small sinusoidal translations, while in practice, large amplitude sinusoidal vibrations can happen. Therefore, in this paper, we formulate an analytical model for electret-based microgenerators under general sinusoidal excitations. The proposed model is validated using finite element modeling combined with numerical simulation approaches presented in the literature. The new model demonstrates a good agreement in estimating both the output voltage and power of the microgenerator. This new model provides useful insights into the microgenerator operating mechanism and design trade-offs, and therefore, can be utilized in the design and performance optimization of these small structures.

Nonlinear Compensation of A Secondary Path in Active Noise Control Using A Modified Filtered-X LMS Algorithm (수정된 FXLMS 알고리듬을 이용한 능동소음제어 시스템 2차 경로 비선형 특성 적응보상 기법)

  • Jeong, I.S.;Ahn, K.Y.;Nam, S.W.
    • Proceedings of the KIEE Conference
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    • 2004.05a
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    • pp.22-25
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    • 2004
  • In active noise control (ANC) system, the convergence behavior of the Filtered- X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortion in the secondary path as in the power amplifiers (e.g., saturation), loudspeakers and transducers. This distortion may yields degrading the error reduction performance of the ANC systems. In this paper, the authors of this paper propose a more improved and stable FXLMS algorithm to compensate for the undesirable nonlinearity of the secondary-path, whereby the third-order Volterra model was employed for the identification of the nonlinear secondary-path. In particular, the proposed approach was based on the modification of the conventional FXLMS algorithm. Finally, the simulation results showed that the proposed approach yields better convergence property and more stable performance in the ANC systems.

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A research on Dynamic characteristic of Submerged pipe ; Support, Flange, Upper pump (수위변화에 따른 파이프 시스템의 진동 특성 변화에 대한 연구)

  • Jung, Hwee Kwon;Kim, Jong Yoon;Park, Gyuhae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.699-705
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    • 2013
  • This paper presents vibration testing, control, and finite element analysis of a piping system, which is subjected to the changes in fluid levels. Nuclear power plants typically employ a cooling system that uses sea water. These systems are subjected to dynamic characteristic changes caused by sea-level variations, which introduces failures of cooling system components. Therefore in this study, analytical and experimental studies were performed to understand the effect of sea-level changes on the dynamic characteristics of piping systems. It was shown that, as the sea-level increases, pipe's natural frequencies decreases in relation to its mode shape. A 1/14 scale model was also built to compare the results obtained by the analytical study. A good agreement between experiment and analytical studies were observed. Finally, an on-line resonant frequency identification system was proposed and developed, which utilizes piezoelectric transducers as sensors and actuators, in order to avoid catastrophic failure of piping systems.

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A Study on Design and Implementation of a Test System for Underwater Communication Equipment (수중 통신 장비를 위한 검사기 설계와 구현에 관한 연구)

  • Yun, Hyeontae;Seok, Jongwon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.22 no.1
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    • pp.42-48
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    • 2019
  • Since the underwater telephone was sold in a short time, there are few repair equipments. And equipment is difficult to locate fault. Equipment with transducers must be inspected underwater, and a relative naval vessels is required to perform an operational check. So we developed a tester device to test the transmission card through the spectrum and transmission power, and to develop a device that can conduct operational tests on land. Therefore, the development of the tester reduces the incidence of naval vessels and contributes to the development of domestic underwater communication test equipment.

In-situ fatigue monitoring procedure using nonlinear ultrasonic surface waves considering the nonlinear effects in the measurement system

  • Dib, Gerges;Roy, Surajit;Ramuhalli, Pradeep;Chai, Jangbom
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.867-876
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    • 2019
  • Second harmonic generation using nonlinear ultrasonic waves have been shown to be an early indicator of possible fatigue damage in nuclear power plant components. This technique relies on measuring amplitudes, making it highly susceptible to variations in transducer coupling and instrumentation. This paper proposes an experimental procedure for in-situ surface wave nonlinear ultrasound measurements on specimen with permanently mounted transducers under high cycle fatigue loading without interrupting the experiment. It allows continuous monitoring and minimizes variation due to transducer coupling. Moreover, relations describing the effects of the measurement system nonlinearity including the effects of the material transfer function on the measured nonlinearity parameter are derived. An in-situ high cycle fatigue test was conducted using two 304 stainless steel specimens with two different excitation frequencies. A comprehensive analysis of the nonlinear sources, which result in variations in the measured nonlinearity parameters, was performed and the effects of the system nonlinearities are explained and identified. In both specimens, monotonic trend was observed in nonlinear parameter when the value of fundamental amplitude was not changing.

Development of The New Analysis Methodology for Comprehensive Vibration Assessment Program for Reactor Internals (원자로 내부구조물 종합진동평가 고유 해석방법론 개발)

  • Do-young Ko;Kyu-hyung Kim
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.19 no.1
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    • pp.1-5
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    • 2023
  • This paper describes a newly-developed analysis methodology in comprehensive vibration assessment program (CVAP) of reactor internals to develop a valid-prototype for the design of nuclear power plants. The new analysis methodology developed in this study will be confirmed through a scale model testing (SMT). Based on the measurements obtained from dynamic pressure transducers in the SMT, a new non-dimensional equation is developed to apply the forcing functions at reactor internals for the prototype. In addition to the new non-dimensional equation, a computational fluid dynamics(CFD) is used to develop the application of the hydraulic loads at reactor internals for the prototype.

Development of Vibroacoustic Stimulation Seat for a Movie Theater Chair (영화관 의자용 음향진동자극 시트의 개발)

  • Moon, Deok-Hong
    • Journal of Power System Engineering
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    • v.17 no.1
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    • pp.42-49
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    • 2013
  • The global movie industry is continuing rapid growth through application of the latest technology. 3D movies are being produced and shown for a more effective viewing experience. Special chairs for audiences are being experimentally manufactured and installed for the greatest viewing effect. This special chair has a structure that applies vibrating stimuli to specific parts of the body by attaching vibration transducers to theater chairs and synchronizing it with each scene of the movie. In a previous study, it has been confirmed that we can analyze the vibration transfer characteristics of sponge seats through the application of an experimental modal analysis method and obtain design variables easily. In this paper, we examine the major design parameters needed in the development of a foaming sponge seat in which auxiliary springs are inserted to improve the vibration transfer effect of a chair seat. Through analyzing several prototypes by applying experimentation as well as the experimental modal analysis method, it was confirmed that the effect of vibration transfer can be improved through the use of an auxiliary member.

A Study on Property Distribution of [011] Poled Mn:PIN-PMN-PT Single Crystals Grown by Bridgeman Method (Bridgeman 성장 [011] 분극 Mn:PIN-PMN-PT 압전단결정의 물성 분포 연구)

  • Soohyun Lim;Yub Je;Yohan Cho;Sang-Goo Lee;Hee-Seon Seo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.4
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    • pp.412-419
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    • 2024
  • Mn-doped Pb(In1/2Nb1/2)O3-Pb(Mg2/3Nb1/3)O3-PbTiO3 (Mn:PIN-PMN-PT) single crystals, which exhibit improved phase transition temperatures and coercive field properties compared to Pb(In1/2Nb1/2)O3-Pb(Mg2/3Nb1/3)O3-PbTiO3 (PIN-PMN-PT) single crystals, are expected to be utilized in high-power acoustic transducers. Bridgeman method, growing single crystals along the axial direction from melt, is most widely used method for single crystal growth with large size and high quality. However, single crystal boules grown by the Bridgeman method demonstrate a PT compositional variation, giving rise a distribution of crystal structure and material properties along the growing axis. To employ piezoelectric single crystals grown by the Bridgeman method for acoustic transducers, it is essential to investigate their overall property distribution. In this study, the compositional distribution and property variation of Mn:PIN-PMN-PT single crystals grown by the Bridgeman method was investigated. Measured compositional distribution of PT was from 29% to 32.5% in the Rhombohedral crystal region of the boule. Two types of specimen, [011]-poled Mn:PIN-PMN-29PT and Mn:PIN-PMN-32PT single crystals, were fabricated and tested to obtain full property variation at both ends of the Rhombohedral crystal region. The properties related to the 32 directional vibration mode and the properties related to high-power driving were measured to confirm the overall distribution of properties by composition.