Acoustic scattering by nonmetallic and metallic cubes in the elastic resonance regime: Experimental measurements and combined finite element/boundary element modeling

Chinnery, Paul A.; Zhang, Jingdong; Humphrey, Victor F.

doi:10.1121/1.419734

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…Potential applications of this result include certain inverse problems ͑such as the approximation of backscattering amplitudes from measurements taken at other angles at sufficiently low frequencies͒ or it may provide a computational test of numerical algorithms for evaluating scattering amplitudes. 7,8 Symmetry, reciprocity, and energy conservation are widely used in general formulations for acoustic scattering; 9,10 however, the result described here does not appear to be widely utilized in acoustics. For quantummechanical scattering amplitudes, Heisenberg 11 is reputed to have derived a theorem similar to the one considered here which is now commonly known as the generalized optical theorem.…”

Section: Introductionmentioning

confidence: 68%

Generalized optical theorem for scatterers having inversion symmetry: Applications to acoustic backscattering

Marston

2001

The Journal of the Acoustical Society of America

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The far-field acoustic scattering amplitudes for the scattering of plane waves by targets having inversion symmetry obey a generalized optical theorem in the absence of dissipation. The theorem allows a component of the complex scattering amplitude in an arbitrary direction to be expressed in terms of an angular integration involving scattering amplitudes evaluated at different angles. The result reduces to the usual optical theorem in the case of forward scattering. The theorem is applied to the backscattering by a perfectly soft sphere as a numerical example. The relevant integrand is shown to be oscillatory. Some potential applications to inverse problems, multiple scattering, and the verification of numerical algorithms are noted.

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Section: Introductionmentioning

confidence: 68%

Generalized optical theorem for scatterers having inversion symmetry: Applications to acoustic backscattering

Marston

2001

The Journal of the Acoustical Society of America

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“…The modelling of physiotherapy transducers has also been carried out (Hughes, 2001). Additionally both scattering problems (Chinnery et al 1997) and diffraction problems (Macey, 1994) have been tackled. PAFEC has also been used in the defence sector to tackle the numerical modelling of active sonar arrays (Morgan, 2004).…”

Section: A2 Program For Automatic Finite Element Calculationsmentioning

confidence: 99%

A comparison of methods for focusing the field of a HIFU array transducer through human ribs

2014

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A forward model, which predicts the scattering by human ribs of a multi-element high-intensity focused ultrasound transducer, was used to investigate the efficacy of a range of focusing approaches described in the literature. This forward model is based on the boundary element method and was described by Gélat et al (2011 Phys. Med. Biol. 56 5553-81; 2012 Phys. Med. Biol. 57 8471-97). The model has since been improved and features a complex surface impedance condition at the surface of the ribs. The inverse problem of focusing through the ribs was implemented on six transducer array-rib topologies and five methods of focusing were investigated, including spherical focusing, binarized apodization based on geometric ray tracing, phase conjugation and the decomposition of the time-reversal operator method. The excitation frequency was 1 MHz and the array was of spherical-section type. Both human and idealized rib topologies were considered. The merit of each method of focusing was examined. It was concluded that the constrained optimization approach offers greater potential than the other focusing methods in terms of maximizing the ratio of acoustic pressure magnitudes at the focus to those on the surface of the ribs whilst taking full advantage of the dynamic range of the phased array.

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“…32,33 Exact solutions exist only for simple shapes, 34 the infinite length circular and elliptic cylinders, ellipsoids, spheres, spheroids in either or some of the following cases: rigid, soft, fluid, and elastic. 35 Numerical techniques based on finite difference, finite element and boundary element methods have also been developed 33,[36][37][38][39][40][41] to overcome the difficulty in obtaining approximate solutions for the acoustic scattering by complex geometries. However, these methods can be computationally expensive for the modeling of porous materials.…”

Section: Introductionmentioning

confidence: 99%

The direct problem of acoustic diffraction of an audible probe radiation by an air-saturated porous cylinder

Ogam

Dépollier

Fellah

2010

Journal of Applied Physics

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International audienceGas-saturated, solid skeleton, porous media like geomaterials, polymeric and metallic foams or biomaterials are fundamental in a diverse range of applications, from structural materials to energy technologies. Most polymeric foams are used for noise control applications and knowledge of the manner in which the energy of sound waves is dissipated with respect to the intrinsic acoustic properties is important for the design of sound packages. Foams are often employed in the audible, low frequency range where modeling and measurement techniques for the recovery of physical parameters responsible for energy loss, are still few. Accurate acoustic methods for the characterization of porous media are based on the measurement of the transmitted and/or reflected acoustic waves by platelike specimens at ultrasonic frequencies. In this study we have developed a method based on the theory and experiment of diffraction of acoustic waves by a rigid-frame, air-saturated polymeric foam in cylindrical form in the audible frequency regime. A dispersion relation for sound wave propagation in the porous medium is derived from the propagation equations and a model solution is sought based on plane-wave decomposition using orthogonal cylindrical functions. The explicit analytical solution equation of the scattered field show that it is also dependent on the intrinsic microstructural parameters of the porous cylinder namely, porosity, tortuosity, and the flow resistivity (related to permeability)

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Acoustic scattering by nonmetallic and metallic cubes in the elastic resonance regime: Experimental measurements and combined finite element/boundary element modeling

Cited by 6 publications

References 10 publications

Generalized optical theorem for scatterers having inversion symmetry: Applications to acoustic backscattering

Generalized optical theorem for scatterers having inversion symmetry: Applications to acoustic backscattering

A comparison of methods for focusing the field of a HIFU array transducer through human ribs

The direct problem of acoustic diffraction of an audible probe radiation by an air-saturated porous cylinder

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