Results 251 to 260 of about 183,094 (279)
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Multiple field acoustic focuser
The Journal of the Acoustical Society of America, 1984The invention provides a highly focussed ultrasonic wave throughout a large depth of field without any mechanical motion. One embodiment of the invention providing two focussed fields includes a front to back arrangement of a converging lens, a transducer without any backing material to dissipate ultrasound, a converging lens, and a transducer.
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Focused Acoustic Wave (FAW) Channelizer
SPIE Proceedings, 1986The architecture, operation, and performance of a new integrated acoustic RF channelizer are described. The all-acoustic device uses a phased array piezoelectric transducer to generate frequency dispersed bulk acoustic waves over a 500 MHz bandwidth. The waves are focused onto a 25 channel receiver electrode array by a cylindrical reflector formed on ...
Dennis R. Pape +3 more
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Ear-focused acoustic reflector
The Journal of the Acoustical Society of America, 1991An acoustic device for mechanically reflecting sound waves into the ear in an undistorted and directionally selective manner has a pair of movable acoustic reflectors constructed, configured and mounted to preserve accurately phase, frequency and image information in the sound waves of interest to the front of the user, secured to a headband or helmet ...
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Electronically focused acoustic imaging device
Applied Physics Letters, 1973A new type of acoustic imaging device, which scans a large array of piezoelectric detectors is described. Scanning is carried out by a signal traveling along an acoustic surface wave delay line. The device can be electronically focused, and has given images of objects 20 cm from the detector array, illuminated with a 5-MHz acoustic wave, with a ...
J. F. Havlice, G. S. Kino, C. F. Quate
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Alternate focusing fluids for passive acoustic targets
The Journal of the Acoustical Society of America, 1990Fluid-filled, focusing spheres are often used as passive acoustic targets because of their relatively high target strength and aspect-independent characteristics. A fluid mixture consisting of equal parts by weight of trichlorotrifluoroethane and carbon tetrachloride provides a near-optimum index of refraction.
H, Boehme, J E, Stockton
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Self-focused acoustic ejectors for viscous liquids
Review of Scientific Instruments, 2010Self-focused acoustic ejectors using the Fresnel zone plate (FZP) have been developed for ejecting viscous liquids, without nozzle, in the drop-on-demand mode. The FZP is composed of a lead zirconate titanate piezoelectric plate patterned with a series of annular electrodes, with the unelectroded region of the plate removed.
Hon, SF, Kwok, KW, Li, HL, Ng, HY
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Acoustic Focusing with Spherical Structures
The Journal of the Acoustical Society of America, 1963A variety of structures in the form of spheres can provide sharp focusing and directivity gains comparable to those from a circular piston with the same diameter. With an isotropic refractive sphere, spherical aberration does not impair focusing except for angular resolutions of the order of a few degrees and less.
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Nonlinear acoustic propagation and focusing
Radiophysics and Quantum Electronics, 1993Two model equations of nonlinear acoustics are considered. The implications of a point transformation between forms of the generalised Burgers equation (GBE) is discussed. New exact and asymptotic solutions are obtained. The dissipative Zabolotskaya-Khokhlov (DZK) equation describing acoustic wave propagation with allowance for transverse amplitude ...
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Bidirectional asymmetric acoustic focusing with two flat acoustic metasurfaces
Chinese Physics B, 2018We design an asymmetric transmission system (ATS) with two flat acoustic metasurfaces (AMs) to yield bidirectional asymmetric acoustic focusing (BAAF). The acoustic waves could be focused on both sides of the ATS with different focal lengths and intensities. To achieve high intensity energy concentration, the accelerating acoustic beams are selected to
Di-Chao Chen +3 more
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Acoustic focusing of microplastics in microchannels: A promising continuous collection approach
Sensors and Actuators B: Chemical, 2020Yoshitake Akiyama, Hiroshi Moriwaki
exaly