The self and mutual radiation impedances for rectangular piston(s) arbitrarily located on a rigid prolate spheroidal baffle are formulated. The pistons are assumed to vibrate with uniform normal velocity and the solution is expressed in terms of a modal series representation in spheroidal eigenfunctions. The prolate spheroidal wave functions are obtained using computer programs that have been recently developed to provide accurate values of the wave functions at high frequencies. Results for the normalized self and mutual radiation resistance and reactance are presented over a wide frequency range for different piston sizes and spheroid shapes.
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http://dx.doi.org/10.1121/1.1420384 | DOI Listing |
J Prosthet Dent
February 2024
Professor and Associate Chair, Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Ala.
Statement Of Problem: Dental zirconia is often marketed and selected for restorative use based upon the biaxial flexural strength of prefabricated specimens (disks) without considering other mechanical and physical properties.
Purpose: The purpose of this in vitro study was to test whether 4-point flexural strength, biaxial flexural strength, and/or hardness may correlate with failure loads for crowns made of different zirconia materials.
Material And Methods: Three brands of zirconia (BruxZir, Cercon, and Katana) were used to fabricate anatomically contoured crowns, rectangular bars, and circular disks.
J Prosthet Dent
September 2022
Associate Professor, Department of Substitutive Dental Sciences, Taibah University, Madina, Saudi Arabia; Fullbright Scholar, Department of Materials Science and Engineering, The University of Alabama at Birmingham, Birmingham, Ala. Electronic address:
Statement Of Problem: Glass-ceramics are often selected for use in dental restorations based upon advertised flexural strengths obtained from standardized tests on prefabricated specimens (bars and disks); these may not accurately reflect their performance in dental applications.
Purpose: The purpose of this in vitro study was to determine and compare 4-point flexural strength, biaxial flexural strength, hardness, and crown failure loads for 3 commercially available glass-ceramics.
Material And Methods: Specimens were pressed and prepared from 3 brands of glass-ceramics: Celtra (CEL), IPS e.
Sci Rep
June 2021
Department of Pharmacology and Physiology, School of Medicine and Health Science, The George Washington University, 2300 Eye Street NW, Washington, DC, 20037, USA.
Liebau pump is a tubular, non-peristaltic, pulsatile pump capable of creating unidirectional flow in the absence of valves. It requires asymmetrical positioning of the pincher relative to the attachment sites of its elastic segment to the rest of the circuit. Biological feasibility of such valveless pumps remains a hotly debated topic.
View Article and Find Full Text PDFJ Acoust Soc Am
September 2019
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba Meguro-ku, Tokyo 153-8505
A method to confine the acoustic pressure distribution near a loudspeaker array is investigated for potential application to personal audio devices. The surface velocity distribution of the loudspeaker array is determined so that more reactive than active acoustic power can be generated. The design is based on the theory of radiation modes, i.
View Article and Find Full Text PDFUltrasonics
August 2019
Shanghai Institute of Ultrasound in Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China.
The purpose of this work was to present the results of a theoretical and experimental study in which a new acoustic output power measurement method was developed for a strongly diverged ultrasonic beam (ka < 3, where k is the circular wave number and a is the radius of transducer) using acoustic radiation force. To the best of our knowledge, there is no acceptable and effective method to measure acoustic power P for diverging piston transducers from 20 kHz to 100 kHz in the range ka < 3, it is a unsolved problem acutely. In the study, we used radiation force balance (RFB) method with a novel concave semi-spherical absorbing target in far field to measure the acoustic power up to 54 W.
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