IEEE Journal of Oceanic Engineering

Issue 2 • April 1987

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Displaying Results 1 - 24 of 24
  • [Front cover and table of contents]

    Publication Year: 1987, Page(s): 0
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  • Guest editorial and overview

    Publication Year: 1987, Page(s):313 - 316
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  • Properties of superresonant systems of spherical scatterers

    Publication Year: 1987, Page(s):327 - 332
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (569 KB)

    Systems of identical precisely spaced bubbles or similar monopole scatterers in water-e.g., inflated balloons or thin-walled shells-insonified at frequenciesomega_{SR}dose to their fundamental radial resonanceomega_{0}(bubble) frequency may themselves display resonance modes or superresonances (SR's) [1]. Ordinary single-bubble resonances magnify the local free-field pressure... View full abstract»

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  • Shear modulus effect on acoustically transparent materials

    Publication Year: 1987, Page(s):333 - 338
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (469 KB)

    Materials have been developed that match densitypand dilatational sound speedcto the values of water as closely as possible while maintaining sufficient rigidity to serve for structural purposes. Matching of density and speed results in transparency for fluids only; the shear modulus in a solid admits the presence of a shear wave which causes deviation from idealpc... View full abstract»

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  • Simultaneous reception of long-range low-frequency backscattered sound by a vertical and a horizontal array

    Publication Year: 1987, Page(s):362 - 367
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (571 KB)

    Simultaneous measurements of low-frequency sound generated by an explosive source and backscattered from the seafloor in the eastern Mediterranean were made with two receiver configurations: a towed horizontal array and a vertical array. Images of the scattering features on the beam-time data of the horizontal array were useful in the interpretation of the scattering process and in estimating area... View full abstract»

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  • Acoustic resonance scattering by large-aspect-ratio solid targets

    Publication Year: 1987, Page(s):368 - 379
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1004 KB)

    The transition-matrix (T-matrix) approach to acoustic scattering is used to investigate scattering by high-aspect-ratio solid elastic targets. Results for several different materials are presented over aKL/2range of 0.5-16.0 for targets with aspect ratios from 1 to 10. It is demonstrated that the phase velocity of the Rayleigh resonances on solid spheroids is closely related ... View full abstract»

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  • Scattering from objects submerged in unbounded and bounded oceans

    Publication Year: 1987, Page(s):380 - 394
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1266 KB)

    We present a study of scattering from objects in a free unbounded ocean and for objects near an interface and in a waveguide. Major emphasis is on results and discussion of theoretical development is limited to the essentials. An examination of backscattered echoes is presented for elastic targets. Angular distributions are examined for all target types, as well as environments, with the exception... View full abstract»

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  • Resonances of elastic scatterers in fluid half-spaces

    Publication Year: 1987, Page(s):395 - 403
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (671 KB)

    A methodology is presented for the spectral analysis of the echo returns from elastic spheres submerged in a fluid half-space. The influence of a target depth on its resonances as manifested in the scattered field is assessed. Results are expressed in terms of Debye potentials in the fluid and in the solid. The unknown coefficients arising in these potentials are determined by the application of a... View full abstract»

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  • An integral eigenvalue approach to three-dimensional field problems--A low-frequency variation of SEM

    Publication Year: 1987, Page(s):466 - 475
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (733 KB)

    The three-dimensional (3-D) eddy-current transient field problem is formulated first using theu-vmethod. This method breaks the vector Helmholtz equation into two scalar Helmholtz equations. Null-field integral equations and the appropriate boundary conditions germane to the problem are used to set up an identification matrix which is independent of null-field point locations. Embedded ... View full abstract»

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  • The Visual Display of Quantitative Information

    Publication Year: 1987, Page(s): 478
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    First Page of the Article
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  • [Back cover]

    Publication Year: 1987, Page(s): c4
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  • Reduction of radar cross section by multiple passive impedance loadings

    Publication Year: 1987, Page(s):453 - 457
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    A general formulation to reduce scattering from conducting objects by multiple passive impedance loadings is derived. The method of moments is used to analyze the conducting objects, and biquadratic programming as an iterative minimization method is used to find the optimum passive impedance. Computer programs to reduce the bistatic radar cross section for arbitrarily shaped thin-wire scatterers b... View full abstract»

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  • Techniques for sonar target identification

    Publication Year: 1987, Page(s):419 - 422
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    We describe bistatic and mostly monostatic techniques that are useful for target classification by means of active sonar. The echoes returned by any submerged elastic body, exemplified here by a wolfram carbide (WC) sphere, contain features caused by the poles of the scattering amplitude of the problem. We have found these poles and shown that they naturally split into two large sets from which on... View full abstract»

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  • Target strength: Some recent theoretical developments

    Publication Year: 1987, Page(s):443 - 452
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (928 KB)

    Some recent developments in the theory of diffraction of transient wavefields with high or moderate, but not excessively low, frequency content are reviewed here. Examples are cited to demonstrate that combinations of wavefronts and resonances, which organize the wave process according to progressing and oscillatory events, respectively, can furnish building blocks for interpretation of transient ... View full abstract»

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  • Variational method for computing surface acoustic pressure on vibrating bodies, applied to transversely oscillating disks

    Publication Year: 1987, Page(s):412 - 418
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (664 KB)

    A variational principle derived from the Kirchhoff-Helmholtz integral relation can be applied to acoustic radiation and diffraction problems. An illustrative example discussed here is that of sound radiation from a flat rigid circular disk in transverse oscillation. The variational formulation has the surface pressure as the unknown variable, with the normal velocity of the surface taken as given.... View full abstract»

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  • Radiation reflected from random rough surfaces

    Publication Year: 1987, Page(s):357 - 361
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    By means of the Wiener-Hermite (W-H) expansion, we are able to represent stochastic field functions using the Gaussian reflecting surface as the basic element. We include three terms. Multiple reflection effects are visible, even for these low-order terms in the expansion. Such reflections can be expected to greatly enhance backscatter at near grazing incidence. View full abstract»

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  • A direct inversion scheme for computing the velocity profile from reflected data

    Publication Year: 1987, Page(s):433 - 442
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (608 KB)

    A simple direct inversion scheme for computing the velocity profile of an inhomogeneous slab from reflected data using the order-of-scattering method of solving the Riccati equation for a lossless medium is presented. Extension of this method to the estimation of the constant attention in a low-loss dispersive medium is also indicated. View full abstract»

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  • Iterative-based computational methods for electromagnetic scattering from individual or periodic structures

    Publication Year: 1987, Page(s):458 - 465
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (960 KB)

    In this paper we review the use of iterative approaches for the numerical analysis of many electromagnetic scattering problems. In a variety of cases, iteration can be used to greatly extend the range of problems easily treated by a numerical solution of the conventional integral equations. Since the resulting matrix equations are not sparse, a special structure must be built into the discrete sys... View full abstract»

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  • A field examination of acoustical scattering from marine organisms at 70 kHz

    Publication Year: 1987, Page(s):339 - 348
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1184 KB)

    Acoustical scattering from aquatic organisms is an extremely complicated problem and can only be dealt with by empirical or semi-empirical models. In order to use sonars as a remote-sensing tool to study biological sound scatterers in the ocean, one must rely on such models. Our research at the Gulf Stream Boundary near Cape Hatteras, North Carolina, involves studying heterogeneous distributions o... View full abstract»

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  • Identification of resonances of an acoustically rigid sphere

    Publication Year: 1987, Page(s):317 - 326
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (912 KB)

    Identification of resonances of an acoustically rigid sphere from simulated input-output data is presented. Scattering from the sphere is formulated using the classic Mie series and the singularity expansion method (SEM). A parametric inverse based on the SEM is discussed. The scattered velocity potential is divided into reflection, first creeping-wave, and second creeping-wave components. The eff... View full abstract»

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  • Stationary variational expressions for radiated and scattered acoustic power and related quantities

    Publication Year: 1987, Page(s):404 - 411
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (864 KB)

    The construction of stationary expressions for quantities of physical interest such as radiated power and target strength is discussed broadly for acoustic problems involving radiation or scattering from finite objects of arbitrary shape. The Kirchhoff-Helmholtz integral corollaries of the wave equation, which express acoustic pressure at either interior or exterior points in terms of pressure and... View full abstract»

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  • Comments on "Current velocity measurements using acoustic doppler backscatter: A Review"

    Publication Year: 1987, Page(s):476 - 477
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (144 KB)

    Omissions in the subject paper, especially lack of reference to one 1968 paper by the author of this letter, may tend to mislead the reader. The subject paper was perhaps too brief to clear the record. View full abstract»

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  • Vertical spatial coherence of backscatter from bubbles

    Publication Year: 1987, Page(s):349 - 356
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (712 KB)

    A basic formalism is developed to treat the vertical spatial coherence of backscatter from wind-generated microbubbles beneath the ocean surface. This formalism treats signals multiply scattered by the sea surface and the subsurface scatterers, as well as absorption in the bubble layer. Approximate solutions are obtained for the case of narrow beamwidth sources and are applied to study the influen... View full abstract»

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  • A layer-stripping fast algorithm for reconstructing an elastic medium from its compressional wave reflection response

    Publication Year: 1987, Page(s):423 - 432
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (776 KB)

    A fast algorithm for recovering profiles of density and compressional (P) and shear-vertical (SV) wave speeds as functions of depth for the inverse seismic problem in a continuous layered elastic medium is obtained. This algorithm differs from previous fast algorithms for this problem since it requires only the compressional wave P-P reflection response at the surface of the medium, for three diff... View full abstract»

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Aims & Scope

The IEEE Journal of Oceanic Engineering (ISSN 0364-9059) is the online-only quarterly publication of the IEEE Oceanic Engineering Society (IEEE OES). The scope of the Journal is the field of interest of the IEEE OES, which encompasses all aspects of science, engineering, and technology that address research, development, and operations pertaining to all bodies of water. This includes the creation of new capabilities and technologies from concept design through prototypes, testing, and operational systems to sense, explore, understand, develop, use, and responsibly manage natural resources.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
N. Ross Chapman
School of Earth & Ocean Sciences
University of Victoria
3800 Finnerty Road
Victoria, BC V8P 5C2 Canada
chapman@uvic.ca