Acoustic fluctuations due to shallow thermal microstructure

by James Burgess Hagen

Publisher: Naval Postgraduate School in Monterey, California

Written in English
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Acoustic fluctuations due to shallow thermal microstructure. Acoustic fluctuations due to shallow thermal microstructure. () ().jpg × ; kB. Acoustic fluctuations due to shallow thermal microstructure. () ().jpg × ; kB. Acoustic propagation in the Somali basin. GOODMAN: ACOUSTIC SCATTERING FROM OCEAN MICROSTRUCTURE regions of increased intensity were observed at depths corresponding to the temperature gradient maximum, sug- gesting that microstructure may be a contributing factor in strong thermal gradient environments [Orr and Hess, ]. The ABYSS was also used in conjunction with both physical. e). In the time domain, acoustic Green’s functions and tensors corresponding to wave propagation in either direction between two given points are expressed as time derivatives of cross-correlation functions of thermal fluctuations of respective acoustic observables. Remarkably, the parameters. Propagation of beamed signals through inhomogeneous media: A diffraction theory the excitation is due to a line source and fluctuations are omitted. of an acoustic signal due to scattering.

An acoustic scattering model for turbulent oceanic microstructure is presented in which the current theory, which only accounts for fluctuations in the sound speed, has been extended to include. Spontaneous otoacoustic emissions, threshold microstructure, and psychophysical tuning over a wide frequency range in humans a Rachael R. Baiduc a) Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Cited by: To measure bearing accuracy and the fine-scale fluctuations in bearing (phase difference) and amplitude of sound waves due to inhomogeneities in the ocean such as thermal microstructure and internal waves, a manned spar buoy was proposed as an ideal platform to make such measurements. The original requirements established for the platform were.   Introduction. Thermal barrier coatings (TBCs) are one of the most widely applied coating systems to improve thermal, oxidation and corrosion resistances of metallic components which are used in the high temperature sections of industrial equipment such as gas turbines and aero-engines [1, 2].TBCs typically consist of three layers: yttria-stabilized zirconia (YSZ) top coat, MCrAlY (M is Cited by:

High-frequency acoustic scattering from turbulent oceanic microstructure: The importance of density fluctuations Andone C. Lavery,a) Raymond W. Schmitt, and Timothy K. Stanton Woods Hole Oceanographic Institution, Woods Hole, Massachusetts ~Received 27 July ; accepted for publication 11 August ! Acoustic scattering techniques. Acoustic scattering from inhomogeneities in the body of the ocean is discussed for both back-scattering and for one-way propagation effects. The main theoretical and experimental descriptions concentrate on the smaller scatterers, especially fish, since internal waves and other wave motions will be covered else-where. The theoretical model of 2-D spectrum analysis builds upon the theoretical framework for 1-D spectra. 14 Under those assumptions, tissue scattering is related to acoustic impedance fluctuations. The acoustic impedance (Z) is defined as the product of sound speed (c) and density (ρ) in a medium. The calibrated 1-D power spectrum of the ROI Cited by:

Acoustic fluctuations due to shallow thermal microstructure by James Burgess Hagen Download PDF EPUB FB2

Enter the password to open this PDF file: Cancel OK. File name:. Predicting Sound Phase and Amplitude Fluctuations Due to Microstructure in the Upper Ocean.

[Herman Medwin] on *FREE* shipping on qualifying offers. Predicting Sound Phase and Amplitude Fluctuations Due to Microstructure in the Upper : Herman Medwin. Taylor thermal microscales from spatial correlation analyses determined vertically across the thermocline varied from to cm. Temporal stochastic analyses showed horizontal acoustic path losses were ten times vertical losses because of diffraction by: 2.

Taylor thermal microscales from spatial correlation analyses determined vertically across the thermocline varied from to cm. The measured variance of the index of refraction ranged from x to xl Temporal stochastic analyses showed horizontal acoustic path losses were ten times vertical losses because of diffraction : James Burgess Hagen.

Acoustic fluctuations due to shallow water thermal microstructure / (Monterey, Calif.: Naval Postgraduate School, ), by James Burgess Hagen (page images at HathiTrust) Acoustic techniques for ocean pollution studies ; and their easy transferability to developing nations / (Washington: National Technical Information Service, [?]), by.

Download PDF: Sorry, we are unable to provide the full text but you may find it at the following location(s): ersitylibrary (external link)Author: James Burgess.

Hagen. Acoustic Fluctuations Thermal Microstructure Shallow Water Thermal Mlcrostructure AtSTRACT fConMiMM on nrf» «Id«II naestMqr an«UtntHr»r Slack numkt) Simultaneous measurements of waves, orthogonal water particle velocities, temperature, conductivity and acoustic phase and amplitude measurements at 20 and ^O kHz overFile Size: 8MB.

Journal of Sound and Vibration () 64(3), SOUND AMPLITUDE FLUCTUATIONS DUE TO A TEMPERATURE MICROSTRUCTUREt N. CHOTIROS AND B. SMITH Department of Electronic and Electrical Engineering, University Birmingham, Birmingham B15 2TT, England (Received 10 Octoberand in revised,/m 9 January ) The experiments reported in this paper were carried out in a.

This paper reports measurements and analysis of thermal microstructure effects on ping-to-ping amplitude and phase variability of shallow-water direct-path acoustic propagation in. Books at Amazon. The Books homepage helps you explore Earth's Biggest Bookstore without ever leaving the comfort of your couch.

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Acoustic fluctuations due to shallow-water internal waves. Oscillations of up to 20 dB in level with total duration of about 1 1/2 hours have been extensively seen in acoustic propagation experiments, and are due to internal waves.

The transmission distances varied from 2 to 23 km in water 35 m deep, with frequency typically about 2 by: 4. The mechanisms for temporal and spatial coherence loss are many, but include internal waves, ocean surface motion in shallow water acoustic waveguides, thermal microstructure and others.

The coherence loss of a wavefront, as described above for the ocean case, also applies to the case for biomédical ultrasonic imaging, with similar results Cited by: 5. Dynamic ocean processes produce small thermal variations that induce spatial and temporal variability in the ocean's index of refraction and in the spatial scale along an acoustic propagation path.

This paper reports measurements and analysis of thermal microstructure effects on ping-to-ping amplitude and phase variability of shallow-water direct-path acoustic propagation in the Author: R.W. Meredith, S.J. Stanic, R.R. Goodman, E.T. Kennedy, N.G. Pace. Acoustic transmission in this short‐range, high‐frequency regime is subject to weak scattering due to thermal microstructure.

The mean temperature at mid‐depth is near 4°C with superimposed microstructure. During some periods, the temperature gradients were strong enough to cause several dB of short‐term acoustic : Paul T. Arveson, J. Michael McKisic. When sound is transmitted in the sea the amplitude of the received signal is found to fluctuate.

Various causes of signal fluctuations are discussed a Cited by: 4. Effects of the Microstructure of Fibrous Media on their Acoustic Properties C. Peyrega*,1 and D. Jeulin1 1Center of Mathematical Morphology, Mathematics and Systems, Mines ParisTech *Charles Peyrega: 1Center of Mathematical Morphology, 35 Rue St-Honoré, Fontainebleau (France), [email protected] Abstract: This study is a part of the Silent WallA.

acoustic signal fluctuations caused by random medium inhomogeneities. The results of these measurements were shown to correlate acoustic signal phase variability with small-scale water column thermal variability and ocean swell conditions [12].

In Juneanother series of shallow-water broadband propagation measurements were conducted. The mechanisms for temporal and spatial coherence loss are many, but include internal waves, ocean surface motion in shallow water acoustic waveguides, thermal microstructure and others.

Ralph R. Goodman's 39 research works with citations and reads, including: Attenuation Measurements Across Surface-Ship Wakes and Computed Bubble Distributions and Void Fractions.

The effects of thermal aging of stainless steel weld-overlay claddings of nuclear reactor pressure vessels on the microstructure and hardness of the claddings were investigated using atom probe tomography and nanoindentation testing.

The claddings were aged at °C for periods of –10, by: Epoxy resin/hollow glass microsphere (HGM) composite acoustic materials for potential applications in the acoustic and electronic fields were prepared with epoxy resin as the matrix and HGMs as the filler.

The effects of the HGM content on the sound propagation characteristics and dielectric properties of the composites were : Guangpeng Gao, Yan Hu, Hongyu Jia, Peng Liu, Peng Du, Dongyu Xu.

The effect of temperature fluctuations on the attenuation of the transmitted pressure field and its mutual coherence is examined.

Experimental results are compared with theoretical estimates based on a solution of the stochastic Helmholtz equation in the parabolic or paraxial by: 2. The amplitude of the resonance is reduced somewhat due to the small impedance mismatch between air and the metamaterial and also the inherent viscous and thermal effects in the heterogeneous structure, but the ability to significantly reduce the resonant frequency (or equivalently reduce the size of the resonator) is undoubtedly of significant Cited by: 3.

Goal 1: To measure high-frequency broadband acoustic backscattering in an energetic shallow water. environment dominated by strong temperature gradients and high levels of turbulence, such as during. the generation, propagation, and dissipation of non-linear.

At the microscopic scale the absorption of the acoustic wave is mainly due to viscous and thermal damping into the boundary layer at the interface between fibers and pores.

Therefore, fully coupled harmonic compressible flow equations for velocity, pressure and temperature must be solved within the \"thermo-acoustic\" module of COMSOL. While the source of scatter remains unclear in Figure 1a due to poor matching between kHz ship‐board sounder data and microstructure data collected meters behind the ship, the kHz echogram gives a striking visual example of how well acoustic scatter correlates with temperature by: Acoustic tomography in a shallow ultrasonic waveguide is demonstrated at the laboratory scale between two source-receiver arrays.

At a 1/1, scale, the waveguide represents a km-long, m. In situ measurements of the bubble field within wakes generated by a small motorboat show that the bubble field, shortly after the initial turbulent generation period, consists mainly of bubbles with radii between 20 and μm.

The subsequent dispersion of the wake field can be described using a model that includes bubble buoyancy and dissolution only, and the air volume fraction within the Cited by:   Purchase Thermal and Acoustic Insulation - 1st Edition.

Print Book & E-Book. ISBNBook Edition: 1. Environmental sensors moored on the New Jersey continental shelf tracked constant density surfaces (isopycnals) for 35 days in the summer of Sound-speed fluctuations from internal-wave vertic Cited by:. Internal waves of a given strength will produce acoustic effects that vary from water mass to water mass.

Presented here is a means of predicting the strength of acoustic fluctuations due to.Acoustic fluctuations and their harmonic structure; R. Field, et al. Group and phase speed analysis for predicting and mitigating the effects of fluctuations; W.A. Kuperman, et al. High-frequency propagation for acoustic communications; M.B.

Porter, et al. Channel impulse response fluctuations at 6 kHz in shallow water; W.S. Hodgkiss, et al.Acoustic fluctuations due to shallow thermal microstructure. () ().jpg 2 × 2 ; KB () ().jpg 1 × 1 ; KB.