RAY REPRESENTATION OF SOUND-SCATTERING BY WEAKLY SCATTERING DEFORMED FLUID CYLINDERS - SIMPLE PHYSICS AND APPLICATION TO ZOOPLANKTON

被引:39
作者
STANTON, TK [1 ]
CLAY, CS [1 ]
CHU, DZ [1 ]
机构
[1] UNIV WISCONSIN, DEPT GEOL & GEOPHYS, MADISON, WI 53706 USA
关键词
D O I
10.1121/1.407199
中图分类号
O42 [声学];
学科分类号
070206 ; 082403 ;
摘要
Data indicate that certain important types of marine organisms behave acoustically like weakly scattering fluid bodies (i.e., their material properties appear fluidlike and similar to those of the surrounding fluid medium). Use of this boundary condition, along with certain assumptions, allows reduction of what is a very complex scattering problem to a relatively simple, approximate ray-based solution. Because of the diversity of this problem, the formulation is presented in two articles: this first one in which the basic physics of the scattering process is described where the incident sound wave is nearly normally incident upon a single target (i.e., the region in which the scattering amplitude is typically at or near a maximum value for the individual) and the second one [Stanton et al., J. Acoust. Soc. Am. 94, 3463-3472 (1993)] where the formulation is heuristically extended to all angles of incidence and then statistically averaged over a range of angles and target sizes to produce a collective echo involving an aggregation of randomly oriented different sized scatterers. In this article, a simple ray model is employed in the deformed cylinder formulation [Stanton, J. Acoust. Soc. Am. 86, 691-705 (1989)] to describe the scattering by finite length deformed fluid bodies in the general shape of elongated organisms. The work involves single realizations of the length and angle of orientation. Straight and bent finite cylinders and prolate spheroids are treated in separate examples. There is reasonable qualitative comparison between the structure of the data collected by Chu et aL [ICES J. Mar. Sci. 49, 97-106 (1992)] involving two decapod shrimp and this single-target normal-incidence theory. This analysis forms the basis for successful comparison (presented in the companion article) between the extended formulation that is averaged over an ensemble of realizations of length and angle of orientation and scattering data involving aggregations of up to 100's of animals.
引用
收藏
页码:3454 / 3462
页数:9
相关论文
共 28 条
[1]  
Abramowitz M., 1964, HDB MATH FUNCTIONS
[2]   FREQUENCY-DEPENDENCE OF SOUND BACKSCATTERING FROM LIVE INDIVIDUAL ZOOPLANKTON [J].
CHU, D ;
STANTON, TK ;
WIEBE, PH .
ICES JOURNAL OF MARINE SCIENCE, 1992, 49 (01) :97-106
[3]   LOW-RESOLUTION ACOUSTIC SCATTERING MODELS - FLUID-FILLED CYLINDERS AND FISH WITH SWIM BLADDERS [J].
CLAY, CS .
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 1991, 89 (05) :2168-2179
[4]   3-DIMENSIONAL GREENS-FUNCTION FOR FLUID-LOADED THIN ELASTIC CYLINDRICAL-SHELL - FORMULATION AND SOLUTION [J].
FELSEN, LB ;
HO, JM ;
LU, IT .
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 1990, 87 (02) :543-553
[5]   3-DIMENSIONAL GREENS-FUNCTION FOR FLUID-LOADED THIN ELASTIC CYLINDRICAL-SHELL - ALTERNATIVE REPRESENTATIONS AND RAY ACOUSTIC FORMS [J].
FELSEN, LB ;
HO, JM ;
LU, IT .
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 1990, 87 (02) :554-569
[6]   SPEED OF SOUND IN EUPHAUSIA-SUPERBA [J].
FOOTE, KG .
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 1990, 87 (04) :1405-1408
[8]   TARGET STRENGTHS OF ANTARCTIC KRILL (EUPHAUSIA-SUPERBA) AT 38-KHZ AND 120-KHZ [J].
FOOTE, KG ;
EVERSON, I ;
WATKINS, JL ;
BONE, DG .
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 1990, 87 (01) :16-24
[9]  
FOOTE KG, IN PRESS CCAMLR SELE
[10]   SONAR CROSS-SECTIONS OF BODIES PARTIALLY INSONIFIED BY FINITE SOUND BEAMS [J].
GAUNAURD, GC .
IEEE JOURNAL OF OCEANIC ENGINEERING, 1985, 10 (03) :213-230