Results 251 to 260 of about 94,167 (304)
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Sound Propagation in a Surface Duct with a Rough Surface
The Journal of the Acoustical Society of America, 1973Sound propagating in a surface duct is partially scattered by surface reflections. This can be accounted for in propagation models by first using a surface reflection coefficient with modulus less than one and then by adding a ray theory correction representing sound scattered directly from the surface to the receiver.
H. P. Bucker, J. L. Thompson
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Redefining the Surface Anatomy of the Parotid Duct
Plastic and Reconstructive Surgery, 2012The surface anatomy of the parotid duct is important when assessing facial lacerations and in facial rejuvenation surgery but is inconsistently described in reference texts. The aim of this study was to map the surface anatomy of the adult parotid duct using ultrasound.Fifty healthy adults (31 women; mean age, 33 years) were scanned by an experienced ...
Mark D, Stringer +3 more
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Convection in a Rectangular Duct with a Corrugated Surface
SAE Technical Paper Series, 1999<div class="section abstract"><div class="htmlview paragraph">Numerical solutions for steady laminar thermally developing flow in a rectangular duct with a sinusoidally corrugated surface are presented. All surfaces are under uniform heat flux conditions (circumferentially and axially). Comparisons are made with previously published results
Carsie A. Hall +2 more
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The influence of a submerged duct on sound propagation in a surface duct
The Journal of the Acoustical Society of America, 1979Acoustic intensities at receivers in a surface duct and in a deep submerged duct are calculated using a normal-mode theory. The sound source is in the surface duct, which is 60 m thick, and the calculations are repeated for thicknesses of the submerged duct ranging from 0 to 150 m, at frequencies from 160 to 400 Hz.
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Acoustic transmission in an ocean surface duct
The Journal of the Acoustical Society of America, 1973An analysis is presented of acoustical transmission measurements which were performed in the oceanic surface duct in two areas of the Pacific Ocean. Three frequencies, three transmitter depths, and three receiver depths were employed. Both areas demonstrated a persistent surface duct but the water mass was more variable in one area than the other.
H. Frank Eden, James Nicol
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Acoustic attenuation in surface-based ducts
The Journal of the Acoustical Society of America, 1974Attenuation of underwater sound propagated in surface-based ducts has heretofore been analyzed for a bottomless underlying ocean into which “leaked” energy vanishes—an artificial assumption, and one untenable in shallow waters. An alternative concept is proposed.
A. O. Williams, R. D. Ryder
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Tropospheric Surface Ducting Phenomena in India
IETE Journal of Research, 1975This paper describes tropospheric surface ducting phenomena in India. Duct occurrence has been found to be associated with temperature inversions or isothermals, very high vapour pressure gradients, and generally high stability. Incidence of ducting has been observed to be highest during March to May in the coastal areas and during April-July in the ...
S. C. Majumdar +2 more
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Wave propagation in a duct with boundary scattering (with application to a surface duct)
The Journal of the Acoustical Society of America, 1980Scattering integrals are derived that represent the contribution of boundary scattering in a sound channel. These integrals are added to the normal mode sum which represents the coherent field in the channel. A comparison is made between experimental and calculated sound levels in a surface duct.
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Ambient noise in the surface duct
The Journal of the Acoustical Society of America, 1975On a number of occasions, and with a variety of instrumentation, the ambient noise level in an area north of St. Croix, VI, has been found to be higher, by amounts up to 8 dB, than at depths below the duct. The difference occurs at the frequencies greater than a few hundred hertz that are trapped in a 120–180-ft duct.
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Surface anatomy of the parotid duct and its clinical relevance
Clinical Anatomy, 2015The trajectory of the parotid duct (PD) makes it vulnerable to injuries during facial trauma and facial rejuvenation procedures. The PD is usually represented as a straight line, although its description in the literature varies. Our objective was to study the trajectory of the PD and to define reliable cutaneous landmarks.
Gaoussou, Toure +2 more
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