Inference of material properties of zooplankton from acoustic and resistivity measurements
Inference of material properties of zooplankton from acoustic and resistivity measurements
复制标题
从声学和电阻率测量推断浮游动物的材料特性
DOI：
10.1006/jmsc.2000.0800
复制
发表时间：
2000
影响因子：
4.5
通讯作者：
N. Copley
中科院分区：
文献类型：
--
作者：
D. Chu;P. Wiebe;N. Copley
已研制出一种实验室仪器，用于推断活体浮游动物的声速和密度对比。声速对比是由声波测量的传播时间（飞行时间）和体积分数的电阻率测量确定的。然后可以利用基于衰减测量的相位补偿畸变波玻恩近似（DWBA）模型来推断密度。对于十足虾（Palaemonetes vulgaris），采用两相射线模型（时间平均）、压缩率模型（Wood’s方程）和DWBA模型（散射理论）三种不同的方法推导出的声速对比具有较好的一致性，而推导出的密度对比与实测密度吻合较好。用压力容器测量了环境压力对声速和密度对比的影响。结果表明：不同压力下密度对比基本保持不变，声速对比在0 ~ 350 dbar压力范围内增加约2.0%；虽然这2.0%的声速对比变化只会导致十足虾估算生物量的适度变化，但它可能会对具有相同声速对比变化量（高达20 dB）的较弱散射体造成更大的偏差。这种新开发的材料特性测量系统最重要的优点是它在浮游动物声学特性的原位测定中具有潜在的适用性。
A laboratory apparatus has been developed and used to infer the sound speed and density contrasts of live zooplankton. The sound speed contrast is determined from acoustic measurements of travel time (time-of-flight) and from the resistivity measurements of volume fraction. The density can then be inferred by applying the phase-compensated distorted wave born approximation (DWBA) model based on the attenuation measurement. For the decapod shrimp (Palaemonetes vulgaris), the inferred sound speed contrast found by using three different methods, namely the two-phase ray model (time average), the compressibility model (Wood's equation), and the DWBA model (scattering theory), is quite consistent, while the inferred density contrast agrees with the measured density reasonably well. The influence of ambient pressure on the sound speed and density contrasts has also been measured using a pressure vessel. The results indicate that the density contrast remains essentially unchanged under different pressure, but the sound speed contrast increases about 2.0% with pressure changing from 0 dbar to about 350 dbar. Although this 2.0% change in sound speed contrast only causes a moderate change in estimating biomass for a decapod shrimp, it could cause a much larger bias for weaker scatterers with the same amount of change in sound speed contrast (up to 20 dB). The most important advantage of this newly developed material properties measuring system is its potential applicability to the in situ determination of acoustic properties of zooplankton.