Download or read book Nonlinear Acoustics Reflection and Refraction Propagation in a Periodic Waveguide Scattering of Sound by Sound and Ellipsoidal Focusing written by and published by . This book was released on 1989 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflection and refraction of plane finite-amplitude waves at a plane interface between two fluids. The nonlinear equation for three-dimensional waves in a thermoviscous, relaxing fluid was derived. A second-order perturbation solution was obtained for the reflection-refraction problem for the case of a lossless fluid and an arbitrary source signal. Propagation in a periodic waveguide. Propagation has been measured in a plane wave tube loaded periodically with reactive branch elements. Experiments with small-signal waves verify in fine detail the dispersion relation that had been derived earlier (and this year modified to include thermoviscous boundary layer effects and the end correction for the branch elements). Scattering of sound by sound. Primary work had been on the role of source and boundary conditions. Experiments on single- beam and crossed-beams in the megahertz range is in progress. Ellipsoidal focusing. This work, which has applications to lithotripsy, is thus far mainly experimental. The experiments are carried out in air. An electric spark located at the near focus of an ellipsoidal reflector generates an N wave. The reflector concentrates the sound at the remote focus.
Download or read book Nonlinear Acoustics Propagation in a Periodic Waveguide and Scattering of Sound by Sound Second written by and published by . This book was released on 1990 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The two primary projects are (A) propagation in a periodic waveguide and (B) scattering of sound by sound. Project (A) is a combined theoretical and experimental study of acoustic Bloch waves in a rectangular, air-filled waveguide that is periodically loaded with reactive branch elements. A small- signal study of the system was done the previous year. This year second harmonic distortion was investigated. A quasilinear solution of the generalized Westervelt equation, with certain terms neglected, showed that although the fundamental Bloch wave is progressive, the second harmonic Bloch wave has both forward traveling and backward traveling components. Experimental measurements generally confirmed the theoretical predictions. In project (B) an analytical study was completed of the effect of various source boundary conditions on the scattered field. The project is mainly experimental, however. The tank facility where the experiments on scattering will be carried out, was completed. A series of three different experiments is planned. Besides the progress on Projects (A) and (B), some work was also done on (C) an upgrade of the Nonlinear Acoustics Laboratory and (D) measurements of ellipsoidal focusing of spark-produced N waves.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1990 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1989-10 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1989 with total page 1672 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1989 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Frequency and Pulse Scattering written by Allan D. Pierce and published by Academic Press. This book was released on 2013-10-22 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Frequency and Pulse Scattering investigates high frequency and pulse scattering, with emphasis on the phenomenon of echoes from objects. Geometrical and catastrophe optics methods in scattering are discussed, along with the scattering of sound pulses and the ringing of target resonances. Caustics and associated diffraction catastrophes are also examined. Comprised of two chapters, this volume begins with a detailed account of geometrically based approximation methods in scattering theory, focusing on waves transmitted through fluid and elastic scatterers and glory scattering; surface ray representations of scattering by shells and other smooth objects; and caustics and associated diffraction catastrophes. The second chapter deals with the relation between sound pulses and the vibrational spectra of elastic submerged objects. The theory of the scattering of sound pulses from elastic and impenetrable objects is described, together with the theory of surface wave pulses. Target resonances and the singularity expansion method are also analyzed. This book will be of interest to physicists.
Download or read book Soviet Physics written by and published by . This book was released on 1978 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear Acoustics Periodic Waveguide Finite Amplitude Propagation in a Medium Having a Distribution of Relaxation Processes and Production of an Isolated Negative Pulse in Water written by and published by . This book was released on 1993 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on nonlinear acoustics has been performed during the 12- month period ending 30 September 1993. The following projects were completed. (1) Propagation in a periodic waveguide (2) Finite-amplitude propagation in a medium having a distribution of relaxation processes (3) Production of an isolated negative pulse in water Public communication of the research was accomplished through three theses, four oral papers, one journal article published, four journal articles submitted, and one paper in a symposium proceedings. Nonlinear acoustics, Relaxing media, Unipolar negative pulse, Generalized Burgers' equation, Bloch waves, Diffraction, Dispersion. Periodic waveguide, Temperature rise due to absorption.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Refraction and Scattering of Sound by a Shear Layer written by Robert H. Schlinker and published by . This book was released on 1980 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The angle and amplitude changes for acoustic waves refracted by a circular open jet shear layer were determined. The generalized refraction theory was assessed experimentally for on axis and off axis acoustic source locations as source frequency varied from 1 kHz to 10 kHz and free stream Mach number varied from 0.1 to 0.4. Angle and amplitude changes across the shear layer show good agreement with theory. Experiments confirm that the refraction theory is independent of shear layer thickness, acoustic source frequency, and source type. A generalized theory is, thus, available for correcting far field noise data acquired in open jet test facilities. The effect of discrete tone scattering by the open jet turbulent shear layer was also studied. Scattering effects were investigated over the same Mach number range as frequency varied from 5 kHz to 15 kHz. Attenuation of discrete tone amplitude and tone broadening were measured as a function of acoustic source position and radiation angle. Scattering was found to be stronger at angles close to the open jet axis than at 90 deg, and becomes stronger as the acoustic source position shifts downstream. A scattering analysis provided an estimate of the onset of discrete tone scattering.
Download or read book Nonlinear Propagation in an Ocean Acoustic Waveguide written by and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sound Propagation Through Anisotropic Inhomogeneous and Intermittent Turbulence written by and published by . This book was released on 2001 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional models of anisotropic and inhomogeneous spectra of temperature and wind velocity fluctuations in unstable atmospheric boundary layers have been developed, modified or extended. Furthermore, theories of sound propagation through anisotropic, inhomogeneous, and intermittent atmospheric turbulence have been developed. These theories allow consideration of different geometries of sound propagation: line-of-sight sound propagation, interference of the direct and ground reflected waves, sound scattering into a refractive shadow zone, and waveguide sound propagation. Using the spectra developed or adopted from the literature, it was shown that anisotropy, inhomogeneity, and intermittency of atmospheric turbulence can significantly affect the statistical moments of a sound field for these geometries. Some of the theoretical results obtained have been verified experimentally. Two related tasks have also been accomplished. First, a new scheme of source localization in the atmosphere by means of acoustic tomography was proposed. The scheme accounts for sound refraction in the atmosphere and allows retrieval of vertical profiles of temperature and wind velocity. Secondly, it was shown that, in many cases, the effects of sound refraction on acoustic remote sensing of wind velocity and the structure parameters of temperature and velocity fluctuations are significant. Algorithms were developed to account for these effects in acoustic remote sensing of the atmosphere.
Download or read book Scattering and Radiation by Shells and Nonlinear Acoustics of Particle Suspensions written by and published by . This book was released on 1992 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research reported concerns three main areas: (a) Surface Guided Wave Contributions to the Scattering of Sound by Elastic Shells in Water Quantitative ray representations described for the scattering by shells give insight into the coupling of sound with structures. backscattering enhancement near the coincidence frequency was observed, modeled, shown to be due to a subsonic wave. Aspects of a high-frequency enhancement were investigated along with time-frequency spectrograms of the impulse response. (b) Radiation Mechanisms for Evanescent Tone Bursts on Fluid Loaded Membranes and Plates Subsonic flexural waves on unbounded plates ordinarily produce evanescent wavefields in the surrounding fluid that are trapped to the plate. Two mechanisms for radiating sound were investigated experimentally: (a) diffraction by a rigid barrier in an evanescent field in air and (b) transition radiation produced when a wave packet travels down a vertical plate through a water surface. (c) Acoustical Four-Wave Mixing in Suspensions Sound is shown to interact with sound in a suspension of microspheres. The spheres are attracted to pressure nodes of counter-propagating pump waves. The banded suspension acts as a diffraction grating and scatters a probe-wave when a Bragg condition is satisfied. Acoustical Scattering, Ray Methods, Elastic Shells, Evanescent Waves, Plates, Suspensions, Nonlinear Acoustics, Radiation Pressure.
Download or read book Nonlinear Acoustics Self Refraction in the Field of a Paraboloidal Reflector and Two Ellipsoid System to Enhance Cavitation Collapse written by and published by . This book was released on 1995 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on nonlinear acoustics has been performed during the 12-month period ending 30 September 1995. Progress is reported on the following projects: (1) Self-refraction in the field of a paraboloidal reflector (experimental), and (2) Two-ellipsoid system to enhance cavitation collapse (experimental). Public communication of the research includes one thesis, one oral paper, two journal articles submitted, and two technical reports.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1996 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:
