We measured the target strength （TS） of three commercial fish species： whitespotted spinefoot （Siganus canaliculatus）, black porgy （Acanthopagrus schlegelii）, and creek red bream （Lutjanus argentimaculatus）, ...We measured the target strength （TS） of three commercial fish species： whitespotted spinefoot （Siganus canaliculatus）, black porgy （Acanthopagrus schlegelii）, and creek red bream （Lutjanus argentimaculatus）, in the South China Sea. The TS of caged or tethered fish （n=76 total） was measured using a Simrad EY60 portable scientific echosounder at 120 kHz. We evaluated the relationship between TS and total length （TL, cm） for the three species. This is the first attempt to use split-beam acoustics to measure single-fish TS in the South China Sea by Chinese researchers. Our results will improve the accuracy and precision of acoustic abundance estimates of commercially important species and fi.trther the development of underwater acoustic survey techniques in fisheries in the South China Sea.展开更多
Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength （TS in dB re l m^2...Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength （TS in dB re l m^2） with the different body size to accurately estimate ice krill stocks. However, there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual, formalin-preserved, tethered ice krill was measured in a freshwater test tank at 38, 120, and 200 kHz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths （L： 13-36 iron）. The length （L, mm） to wet weight （W; mg） relationship for ice krill was 11/=0.001 21g^103~L35s （R2=0.96）. The mean TS-to-length relationship were TS38kHz=-177.4＋57log10（L）, （R^2=0.86）; TS120kHz= -129.9＋31.561ogf0（L）, （R2=0.87）; and TS200kHz=-117.6＋24.661ogre（L）, （R2=0.84）. Empirical estimates of the relationship between the TS and body length of ice krill were established at 38, 120, and 200 kHz and compared with predictions obtained from both the linear regression model of Greene et al. （1991） and the Stochastic Distorted Wave Born Approximation （SDWBA） model. This result might be applied to improve acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.展开更多
Target strength(TS)and circular synthetic aperture sonar(CSAS)images provide essential information for active acoustic detection and recognition of non-cooperative unmanned undersea vehicles(UUVs),which pose a signifi...Target strength(TS)and circular synthetic aperture sonar(CSAS)images provide essential information for active acoustic detection and recognition of non-cooperative unmanned undersea vehicles(UUVs),which pose a significant threat to underwater preset facilities.To access them,we propose an iterative physical acoustics(IPA)-based method to simulate the multiple acoustic scattered fields on rigid surfaces in high-frequency cases.It uses the Helmholtz integral equation with an appropriate Green's function in terms of the Neumann series,and then incorporates the ideas of triangulation and iteration into a numerical implementation.Then two approximate analytic formulae with precise physical meanings are derived to predict the TS and CSAS images of concave targets,respectively.There are no restrictions on the surface's curvature and the order of multiple scattering.The method is validated against the finite element method(FEM)for acoustic scattering from a sphere segment and against an experiment involving an X-rudder UUV's stern.On this basis,we simulate and analyze the TS and CSAS images of an X-rudder UUV.In addition,the influence of the angle of adjacent rudders on the multiple scattering characteristics is discussed.Results show that this method can potentially predict accurate UUV features,especially the multiple scattered features.展开更多
A model as well as its numerical method to calculate target strength of rigid body using Lighthill's acoustic analogy approach which developed from the propeller aircraft sound field study have been presented. The...A model as well as its numerical method to calculate target strength of rigid body using Lighthill's acoustic analogy approach which developed from the propeller aircraft sound field study have been presented. The cases of ellipsoid target has been used to demonstrate the approach. The comparison of the numerical results with that of analytical formulation provides a satisfactory check for the validity of the approach. Some reasonable results have been discussed. The advantage of the present model is that it is suitable for any arbitrarily shaped rigid body moving with small Mach number.展开更多
This study proposes a numerically efficient technique for computing the far-field scattered by a spherical target placed near the seabed.The bottom is supposed to be a homogeneous liquid attenuating half-space.The tra...This study proposes a numerically efficient technique for computing the far-field scattered by a spherical target placed near the seabed.The bottom is supposed to be a homogeneous liquid attenuating half-space.The transmitter and receiver are situated at different points of a homogeneous water half-space.The distances between the transmitter,receiver,and object of interest are assumed to be much larger than the acoustic wavelength in water.The scattered far-field is ascertained using Hackman and Sammelmann’s general approach.The arising scattering coefficients of a sphere are assessed using the steepest descent approach.The branch cut contribution is also considered.The obtained formulas for the form-function can be used for acoustically rigid or soft scatterers,as well as elastic targets or spherical elastic shells.Numerical simulations are conducted for an acoustically rigid sphere.Asymptotic expressions for the scattering coefficients allow a decrease in the number of summands in the formula for the target strength and a significant reduction in computational time.展开更多
Acoustic scattering as the perturbation of an incident acoustic field from an arbitrary object is a critical part of the targetrecognition process in synthetic aperture sonar(SAS)systems.The complexity of scattering m...Acoustic scattering as the perturbation of an incident acoustic field from an arbitrary object is a critical part of the targetrecognition process in synthetic aperture sonar(SAS)systems.The complexity of scattering models strongly depends on the size and structure of the scattered surface.In accurate scattering models including numerical models,the computational cost significantly increases with the object complexity.In this paper,an efficient model is proposed to calculate the acoustic scattering from underwater objects with less computational cost and time compared with numerical models,especially in 3D space.The proposed model,called texture element method(TEM),uses statistical and structural information of the target surface texture by employing non-uniform elements described with local binary pattern(LBP)descriptors by solving the Helmholtz integral equation.The proposed model is compared with two other well-known models,one numerical and other analytical,and the results show excellent agreement between them while the proposed model requires fewer elements.This demonstrates the ability of the proposed model to work with arbitrary targets in different SAS systems with better computational time and cost,enabling the proposed model to be applied in real environment.展开更多
Determine the location of a target has gained considerable interest over the past few years. The Received Signal Strength(RSS) measurements and Differential RSS(DRSS) measurements can be converted to distance or dista...Determine the location of a target has gained considerable interest over the past few years. The Received Signal Strength(RSS) measurements and Differential RSS(DRSS) measurements can be converted to distance or distance ratio estimates for constructing a set of linear equations. Based on these linear equations, a constrained weighted least Squares(CWLS) algorithm for target localization is derived. In addition, an iterative technique based on Newton's method is utilized to give a solution. The covariance and bias of the CWLS algorithm is derived using perturbation analysis. Simulation shows that the proposed estimator achieves better performance than existing algorithms with reasonable complexity.展开更多
在基于接收信号强度(received signal strength,RSS)的定位中,传感器量测的系统偏差及锚节点位置的不确定性会对定位结果造成严重影响。对此,提出一种面向不确定量测的鲁棒定位方法。首先,针对传感器量测有偏差及锚节点位置不确定的定...在基于接收信号强度(received signal strength,RSS)的定位中,传感器量测的系统偏差及锚节点位置的不确定性会对定位结果造成严重影响。对此,提出一种面向不确定量测的鲁棒定位方法。首先,针对传感器量测有偏差及锚节点位置不确定的定位问题,建立相应的量测模型;其次,基于经典的极大似然估计准则建立关于目标位置的估计问题;最后,对所建立的非凸位置估计问题,采用合理的近似、松弛数学手段,将其转化为凸的半正定规划问题,从而保证得到全局最优解。仿真实验表明,在不同定位场景和条件下,所提方法的定位精度相比文献中的几种定位方法均有明显的优势,最高可提升约50%,证明其能有效降低量测不确定性对定位结果的不利影响,具有良好的鲁棒性。展开更多
基金Supported by the National High Technology Research and Development Program of China (863 Program) (No. 2006AA100303)the Science and Technology Project of Guangdong Province, China (No.2007B020708001)+1 种基金the Special Funds for Operating Expenses of Basic Researches in the Central Nonprofit Scientific Research Institutes (Nos.2008TS01, 2007ZD03)the Natural Science Foundation of Guangdong Province, China (No. 04001263)
文摘We measured the target strength （TS） of three commercial fish species： whitespotted spinefoot （Siganus canaliculatus）, black porgy （Acanthopagrus schlegelii）, and creek red bream （Lutjanus argentimaculatus）, in the South China Sea. The TS of caged or tethered fish （n=76 total） was measured using a Simrad EY60 portable scientific echosounder at 120 kHz. We evaluated the relationship between TS and total length （TL, cm） for the three species. This is the first attempt to use split-beam acoustics to measure single-fish TS in the South China Sea by Chinese researchers. Our results will improve the accuracy and precision of acoustic abundance estimates of commercially important species and fi.trther the development of underwater acoustic survey techniques in fisheries in the South China Sea.
基金Supported by the Korea Polar Research Institute(No.PP14020)the Korea Institute of Ocean Science and Technology(No.PN65250)
文摘Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength （TS in dB re l m^2） with the different body size to accurately estimate ice krill stocks. However, there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual, formalin-preserved, tethered ice krill was measured in a freshwater test tank at 38, 120, and 200 kHz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths （L： 13-36 iron）. The length （L, mm） to wet weight （W; mg） relationship for ice krill was 11/=0.001 21g^103~L35s （R2=0.96）. The mean TS-to-length relationship were TS38kHz=-177.4＋57log10（L）, （R^2=0.86）; TS120kHz= -129.9＋31.561ogf0（L）, （R2=0.87）; and TS200kHz=-117.6＋24.661ogre（L）, （R2=0.84）. Empirical estimates of the relationship between the TS and body length of ice krill were established at 38, 120, and 200 kHz and compared with predictions obtained from both the linear regression model of Greene et al. （1991） and the Stochastic Distorted Wave Born Approximation （SDWBA） model. This result might be applied to improve acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.
基金supported by the National Youth Science Foundation of China(Grant No.52001211).
文摘Target strength(TS)and circular synthetic aperture sonar(CSAS)images provide essential information for active acoustic detection and recognition of non-cooperative unmanned undersea vehicles(UUVs),which pose a significant threat to underwater preset facilities.To access them,we propose an iterative physical acoustics(IPA)-based method to simulate the multiple acoustic scattered fields on rigid surfaces in high-frequency cases.It uses the Helmholtz integral equation with an appropriate Green's function in terms of the Neumann series,and then incorporates the ideas of triangulation and iteration into a numerical implementation.Then two approximate analytic formulae with precise physical meanings are derived to predict the TS and CSAS images of concave targets,respectively.There are no restrictions on the surface's curvature and the order of multiple scattering.The method is validated against the finite element method(FEM)for acoustic scattering from a sphere segment and against an experiment involving an X-rudder UUV's stern.On this basis,we simulate and analyze the TS and CSAS images of an X-rudder UUV.In addition,the influence of the angle of adjacent rudders on the multiple scattering characteristics is discussed.Results show that this method can potentially predict accurate UUV features,especially the multiple scattered features.
基金This work is supported by the National Defence Foundation of China.
文摘A model as well as its numerical method to calculate target strength of rigid body using Lighthill's acoustic analogy approach which developed from the propeller aircraft sound field study have been presented. The cases of ellipsoid target has been used to demonstrate the approach. The comparison of the numerical results with that of analytical formulation provides a satisfactory check for the validity of the approach. Some reasonable results have been discussed. The advantage of the present model is that it is suitable for any arbitrarily shaped rigid body moving with small Mach number.
基金Supported by the Ministry of Science and Higher Education of the Russian Federation as a part of World-class Research Center Program:Advanced Digital Technologies(contract No.075-15-2022-312 dated 20 April 2022).
文摘This study proposes a numerically efficient technique for computing the far-field scattered by a spherical target placed near the seabed.The bottom is supposed to be a homogeneous liquid attenuating half-space.The transmitter and receiver are situated at different points of a homogeneous water half-space.The distances between the transmitter,receiver,and object of interest are assumed to be much larger than the acoustic wavelength in water.The scattered far-field is ascertained using Hackman and Sammelmann’s general approach.The arising scattering coefficients of a sphere are assessed using the steepest descent approach.The branch cut contribution is also considered.The obtained formulas for the form-function can be used for acoustically rigid or soft scatterers,as well as elastic targets or spherical elastic shells.Numerical simulations are conducted for an acoustically rigid sphere.Asymptotic expressions for the scattering coefficients allow a decrease in the number of summands in the formula for the target strength and a significant reduction in computational time.
文摘Acoustic scattering as the perturbation of an incident acoustic field from an arbitrary object is a critical part of the targetrecognition process in synthetic aperture sonar(SAS)systems.The complexity of scattering models strongly depends on the size and structure of the scattered surface.In accurate scattering models including numerical models,the computational cost significantly increases with the object complexity.In this paper,an efficient model is proposed to calculate the acoustic scattering from underwater objects with less computational cost and time compared with numerical models,especially in 3D space.The proposed model,called texture element method(TEM),uses statistical and structural information of the target surface texture by employing non-uniform elements described with local binary pattern(LBP)descriptors by solving the Helmholtz integral equation.The proposed model is compared with two other well-known models,one numerical and other analytical,and the results show excellent agreement between them while the proposed model requires fewer elements.This demonstrates the ability of the proposed model to work with arbitrary targets in different SAS systems with better computational time and cost,enabling the proposed model to be applied in real environment.
文摘Determine the location of a target has gained considerable interest over the past few years. The Received Signal Strength(RSS) measurements and Differential RSS(DRSS) measurements can be converted to distance or distance ratio estimates for constructing a set of linear equations. Based on these linear equations, a constrained weighted least Squares(CWLS) algorithm for target localization is derived. In addition, an iterative technique based on Newton's method is utilized to give a solution. The covariance and bias of the CWLS algorithm is derived using perturbation analysis. Simulation shows that the proposed estimator achieves better performance than existing algorithms with reasonable complexity.
文摘在基于接收信号强度(received signal strength,RSS)的定位中,传感器量测的系统偏差及锚节点位置的不确定性会对定位结果造成严重影响。对此,提出一种面向不确定量测的鲁棒定位方法。首先,针对传感器量测有偏差及锚节点位置不确定的定位问题,建立相应的量测模型;其次,基于经典的极大似然估计准则建立关于目标位置的估计问题;最后,对所建立的非凸位置估计问题,采用合理的近似、松弛数学手段,将其转化为凸的半正定规划问题,从而保证得到全局最优解。仿真实验表明,在不同定位场景和条件下,所提方法的定位精度相比文献中的几种定位方法均有明显的优势,最高可提升约50%,证明其能有效降低量测不确定性对定位结果的不利影响,具有良好的鲁棒性。
