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  • Comparative Studies. Non-European Languages/Literatures  (2)
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  • Comparative Studies. Non-European Languages/Literatures  (2)
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  • 1
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2016
    In:  Journal of the Acoustical Society of America Vol. 140, No. 4_Supplement ( 2016-10-01), p. 3166-3166
    In: Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 140, No. 4_Supplement ( 2016-10-01), p. 3166-3166
    Abstract: The ultrasonic nonlinear parameter, β, has been known as effective for the evaluation of material degradation, and its correlation with material degradations such as thermal aging, fatigue, creep, and plastic deformation has been reported. However, most studies were limited to the relative measurements that is effective only for the relative comparison and not able to evaluate the degradation in quantitative. To overcome this limit, this study proposes a new algorithm which is able to evaluate the quantitative strength degradation. The proposed method mainly consists of four steps: 1) Measure the linear elastic modulus (E) from the longitudinal and shear wave velocities by using pulse echo method. 2) Measure the absolute ultrasonic nonlinear parameter, β, by using piezoelectric detection method. 3) Construct the stress-strain curve by substituting the measured linear elastic modulus (E) and absolute ultrasonic nonlinear parameter β to the nonlinear stress-strain equation. 4) Estimate the 0.01% offset yield strain and yield strength. The yield strengths estimated by the proposed technique in the heat-treated Al6061-T6 and SA508 showed good agreement with the yield strength obtained by tensile test. Consequently, the proposed method makes the quantitative evaluation of strength degradation using ultrasonic measurement possible. [This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (NRF-2013M2A2A9043241).]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2016
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2013
    In:  The Journal of the Acoustical Society of America Vol. 134, No. 5_Supplement ( 2013-11-01), p. 4109-4109
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 134, No. 5_Supplement ( 2013-11-01), p. 4109-4109
    Abstract: In this work, we are interested in tracking a rotating sound source using a Kalman filtering technique based on a set of non-linear time difference of arrival (TDOA) measurements. Array of microphones measure acoustic signal emitted from a rotating source and the TDOA estimates are calculated followed by a solution for hyperbolic position fix. The position estimation of sound source based on TDOA is a popular technique in source localization. The method involves calculation of a set of nonlinear equations and poor accuracy of TDOA estimates often results in inaccuracy in location. In this work, the range difference is expressed by a model movement on which a recursive extended Kalman Filter has been developed. The TDOA measurements optimize the estimated values which are reduced as observation in extended Kalman filtering algorithm. Location estimation is updated from TDOA measurements along with the time history data. The Cramer-Rao Lower Bound (CRLB) is derived and simulations are compared. [Work supported by National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2010-0014978).]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2013
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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