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  • Comparative Studies. Non-European Languages/Literatures  (4)
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  • Comparative Studies. Non-European Languages/Literatures  (4)
RVK
  • 1
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2013
    In:  The Journal of the Acoustical Society of America Vol. 133, No. 6 ( 2013-06-01), p. 3838-3845
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 133, No. 6 ( 2013-06-01), p. 3838-3845
    Abstract: In this study, a reference-free damage characterization technique is developed not only to identify but also to locate and quantify damage in composite structures subject to varying temperature conditions. First, damage is characterized in terms of a damage index (m-value) defined as the ratio of damage size to the wavelength of the A0 mode within the damage. Then, a feasible solution space defining all possible combinations of the damage location and size are estimated without using any prior baseline data obtained from the pristine condition of a structure or different paths. When additional information such as the A0 mode group velocity within the pristine region of the structure becomes available, the estimates for the damage location and size are updated with better accuracy. The uniqueness of this study lies in that damage localization and quantification as well as identification are all performed without comparing current Lamb wave signals with the ones obtained from the pristine condition of the target structure, making the proposed technique more attractive for online monitoring. Numerical and experimental tests are presented to demonstrate the effectiveness of the proposed damage detection technique under varying temperature.
    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
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  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2001
    In:  The Journal of the Acoustical Society of America Vol. 109, No. 5_Supplement ( 2001-05-01), p. 2313-2314
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 109, No. 5_Supplement ( 2001-05-01), p. 2313-2314
    Abstract: The strong early reflections and short delay times have been known to improve the intelligibility of speech heard in rooms. D50 and C80, the most frequently used physical parameters, were developed taking this fact into consideration. However, these monaural parameters have limited applications for the practical design of rooms because of their lack of spatial information. The present work investigates how temporal changes in three-dimensional distribution of early reflections influence speech intelligibility in rooms. A new measurement method, using a five microphone array and an omnidirectional source setup, is employed, and a series of post-processing procedures are involved, for getting different early reflections in their spatial distributions. The changes were made for the impulse responses obtained through a five microphone array in the arrival times of early reflections from all, and the horizontal and vertical directions, respectively. Anechoic samples of the Korean language were convolved binaurally with the reproduced impulses by applying a head-related transfer function. A series of speech intelligibility tests, conducted for 22 university students, found that the percentage of correct responses significantly deteriorated by increasing delay times of early reflections from the vertical direction. The result suggests that vertical components of early reflections play a significant role in improving speech intelligibility. [Work supported by Korean Research Foundation Grant KRF-1999-1-310-004-3.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2001
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2006
    In:  The Journal of the Acoustical Society of America Vol. 120, No. 5_Supplement ( 2006-11-01), p. 3111-3111
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 120, No. 5_Supplement ( 2006-11-01), p. 3111-3111
    Abstract: It is already known that the ultrasound speed and attenuation coefficient are increasing during the blood clotting process. A pulse echo system was set up to measure the sound speed and attenuation coefficient of human blood at 37 C. From ten healthy volunteers, the blood was taken to measure sound speed and attenuation coefficient during blood coagulation without and with heparin. For ten stroke patients, sound speed and attenuation were measured with aPTT or PT for comparison. The variation of sound speed and attenuation coefficient of blood after adding heparin was small. Sound speed of plasma from healthy volunteers was increased to 7 from 1535 m/s over 50 min without heparin, but to 1 m/s during the first 5 min for heparin-added blood. Sound speed of plasma from stroke patients was changed little compared to that from healthy volunteers without heparin. Attenuation coefficient was increased linearly during plasma coagulation for both volunteers and stroke patients, but its temporal slopes were much smaller for stroke patients. The blood samples from the stroke patients that investigated how heparin affects sound speed and attenuation as a function of time before and after taking the heparin and the results will be discussed.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2006
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2001
    In:  The Journal of the Acoustical Society of America Vol. 109, No. 5_Supplement ( 2001-05-01), p. 2389-2389
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 109, No. 5_Supplement ( 2001-05-01), p. 2389-2389
    Abstract: Numerous investigations have demonstrated that diffuse reflection is one of the most important factors in predicting room acoustics by computer simulation. Recent studies have suggested several computational algorithms in order to account for diffuse reflections in the ray-tracing or beam-tracing method. In this study, a computational algorithm for the calculation of diffuse sound reflections in the image method is suggested and a computer simulation system is developed based on the suggested algorithm. The methodology adopted in our computer simulation system is similar to the extended radiosity method, which was developed for computer graphics. Various descriptions of room acoustics, including spatial distribution of image sound sources, impulse responses and other commonly used room acoustical measures, can be obtained from the MLS based monaural room acoustics measurement system. The measured results in a midsized rectangular classroom with/without chairs on the floor were compared with the predicted results using the computer simulation in which diffuse reflection coefficients of the floor were varied. [Work supported by Korean Research Foundation Grant KRF-1999-1-310-004-3.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2001
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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