Bibliografias temáticas / Plane-Wave transducer

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Literatura científica selecionada sobre o tema "Plane-Wave transducer"

Autor: Grafiati

Publicado: 8 de fevereiro de 2025

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Artigos de revistas sobre o assunto "Plane-Wave transducer"

Zennaro, Marco, Dan J. O’Boy, Premesh Shehan Lowe e Tat-Hean Gan. "Characterization and Design Improvement of a Thickness-Shear Lead Zirconate Titanate Transducer for Low Frequency Ultrasonic Guided Wave Applications". Sensors 19, n.º 8 (18 de abril de 2019): 1848. http://dx.doi.org/10.3390/s19081848.

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Thickness-shear transducers for guided wave testing have been used in industry for over two decades and much research has been conducted to improve the resolution and sensitivity. Due to a geometric feature of the current state-of-the art transducer, there is an out-of-plane component in the propagation direction of the fundamental shear horizontal mode which complicates the signal interpretation. In such case, complex signal processing techniques need to be used for mode discrimination to assess the structural health with higher precision. Therefore, it is important to revise the transducer design to eliminate the out-of-plane components in the propagation direction of fundamental shear horizontal mode. This will enhance the mode purity of fundamental shear horizontal mode for its application in guided wave inspection. A numerical investigation has been conducted on a 3 mm thick 2 m circular steel plate to understand the behaviour and the characteristics of the state-of-the-art thickness-shear transducer. Based on the results, it is noted that the redesigning the electrode arrangement will suppress the out-of-plane components on the propagation direction of the fundamental shear horizontal mode. With the aid of this information current state-of-the-art transducers were redesigned and tested in laboratory conditions using the 3D Laser Doppler Vibrometer. This information will aid future transducer designers improve the resolution of thickness-shear transducers for guided wave applications and reduce the weight and cost of transducer array by eliminating the need of additional transducers to suppress spurious modes.

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Go, Dooyoung, Jinbum Kang, Ilseob Song e Yangmo Yoo. "Efficient Transmit Delay Calculation in Ultrasound Coherent Plane-Wave Compound Imaging for Curved Array Transducers". Applied Sciences 9, n.º 13 (8 de julho de 2019): 2752. http://dx.doi.org/10.3390/app9132752.

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The recently introduced plane-wave compounding method based on multiple plane-wave excitation has enabled several new applications due to its high frame rate (>1000 Hz). In this paper, a new efficient transmit delay calculation method in plane-wave compound imaging for a curved array transducer is presented. In the proposed method, the transmit delay is only calculated for a steering angle of 0° and is shifted along the element of the transducer to obtain other transmit delays for different steering angles. To evaluate the performance of the proposed method, the computational complexity was measured for various transmission conditions. For the number of elements and plane-wave excitations of 128 and 65, respectively, the number of operations was substantially decreased in the proposed method compared with the conventional method (256 vs. 8320). The benefits of the proposed method were demonstrated with phantom and in vivo experiments, where coherent plane-wave compounding with 65 excitations provided larger CR and CNR values compared to nine excitations (−22.5 dB and 2.7 vs. −11.3 dB and 1.9, respectively). These results indicate the proposed method can effectively reduce the computational complexity for plane-wave compound imaging in curved array transducers.

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Berthelot, J.-M., Souda M. Ben e J. L. Robert. "Study of wave attenuation in concrete". Journal of Materials Research 8, n.º 9 (setembro de 1993): 2344–53. http://dx.doi.org/10.1557/jmr.1993.2344.

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The experimental study of wave attenuation in concrete has been achieved in the case of the propagation of plane waves in concrete rods. Different mortars and concretes have been investigated. A transmitter transducer coupled to one of the ends of the concrete rod generates the propagation of a plane wave in the rod. The receiver transducer, similar to the previous one, is coupled to the other end of the rod. The experimental results lead to an analytical expression for wave attenuation as function of the concrete composition, the propagation distance, and the wave frequency.

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Theobald, Pete T., e F. Dar. "AE Sensor Calibration for Out-of-Plane and In-Plane Displacement Sensitivity". Advanced Materials Research 13-14 (fevereiro de 2006): 91–98. http://dx.doi.org/10.4028/www.scientific.net/amr.13-14.91.

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This paper proposes a method for both the out-of-plane and in-plane displacement sensitivity calibration of an acoustic emission (AE) sensor. In the method, a laser homodyne interferometer is used to measure the out-of-plane and in-plane displacement of the surface of a large test block excited by a repeatable source transducer. The out-of-plane displacement is measured by aligning the laser beam perpendicular to the surface with time gating of the receive waveform used to isolate only the direct arrival of the longitudinal wave produced by the piston source transducer. For the in-plane displacement measurement, the laser beam is aligned parallel to the surface to intersect a small optically reflective step with the time waveform being gated to measure only the direct shear arrival produced using a normal incidence shear wave source transducer. In each case, the interferometer measurement is followed by coupling the sensor under test to the measurement surface, which is then exposed to the same acoustic field and the sensor output signal measured. This substitution method allows the sensor sensitivity to be obtained in terms of volts per unit displacement for both the out-of-plane and in-plane surface displacement. The method allows a comprehensive description of an AE sensor response to different planes of displacement and offers the potential for a traceable sensor calibration to units of length.

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Liu, Zhi-Ying, Ping Zhang, Bi-Xing Zhang e Wen Wang. "Multi Spherical Wave Imaging Method Based on Ultrasonic Array". Sensors 22, n.º 18 (8 de setembro de 2022): 6800. http://dx.doi.org/10.3390/s22186800.

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The imaging range of traditional plane wave imaging is usually limited by the directivity of the plane wave. In this paper, a multi spherical wave imaging method based on an ultrasonic array is proposed, which radiates both compression and shear waves in a solid medium to form the multi spherical wave. Firstly, excitation characteristics of the multi spherical wave are analyzed theoretically and the calculation method of echo delay of multi spherical wave imaging is derived. Multi spherical wave imaging is compared with conventional ultrasonic plane wave imaging by designing experiments. Compared with ultrasonic plane wave imaging, multi spherical wave imaging is not limited to the size of the transducer and can greatly improve the detection range. In addition, compared with the multi plane wave imaging method, the multi spherical wave imaging algorithm is relatively simple, fast, and has high application value.

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Tang, Yujia, Zhangjian Li, Yaoyao Cui, Chen Yang, Jiabing Lv e Yang Jiao. "Micro Non-Uniform Linear Array (MNULA) for Ultrasound Plane Wave Imaging". Sensors 21, n.º 2 (18 de janeiro de 2021): 640. http://dx.doi.org/10.3390/s21020640.

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Ultrasound plane wave imaging technology has been applied to more clinical situations than ever before because of its rapid imaging speed and stable imaging quality. Most transducers used in plane wave imaging are linear arrays, but their structures limit the application of plane wave imaging technology in some special clinical situations, especially in the endoscopic environment. In the endoscopic environment, the size of the linear array transducer is strictly miniaturized, and the imaging range is also limited to the near field. Meanwhile, the near field of a micro linear array has serious mutual interferences between elements, which is against the imaging quality of near field. Therefore, we propose a new structure of a micro ultrasound linear array for plane wave imaging. In this paper, a theoretical comparison is given through sound field and imaging simulations. On the basis of primary work and laboratory technology, micro uniform and non-uniform linear arrays were made and experimented with the phantom setting. We selected appropriate evaluation parameters to verify the imaging results. Finally, we concluded that the micro non-uniform linear array eliminated the artifacts better than the micro uniform linear array without the additional use of signal processing methods, especially for target points in the near-field. We believe this study provides a possible solution for plane wave imaging in cramped environments like endoscopy.

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Cowes, Diego A., Juan I. Mieza e Martín P. Gómez. "Polyvinylidene fluoride transducer shape optimization for the characterization of anisotropic materials". Journal of the Acoustical Society of America 156, n.º 6 (1 de dezembro de 2024): 3943–53. https://doi.org/10.1121/10.0034601.

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In the context of ultrasonic determination of mechanical properties, it is common to use oblique incident waves to characterize fluid-immersed anisotropic samples. The lateral displacement of the ultrasonic field owing to leaky guided wave phenomena poses a challenge for data inversion because beam spreading is rarely well represented by plane wave models. In this study, a finite beam model based on the angular spectrum method was developed to estimate the influence of the transducer shape and position on the transmitted signals. Additionally, anisotropic solids were considered so that the beam skewing effect was contemplated. A small-emitter large-receiver configuration was chosen, and the ideal shape and position of the receiving transducer were obtained through a meta-heuristic optimization approach with the goal of achieving a measurement system that sufficiently resembles plane wave propagation. A polyvinylidene fluoride receiver was fabricated based on the findings and tested in three cases: a single-crystal silicon wafer, a lightly anisotropic stainless-steel plate, and a highly anisotropic composite plate. Good agreement was found between the measurements and the plane wave model.

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Annenkov, Alexander Yu, Sergey V. Gerus e Edwin H. Lock. "Superdirected beam of the backward volume spin wave". EPJ Web of Conferences 185 (2018): 02006. http://dx.doi.org/10.1051/epjconf/201818502006.

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Visualized patterns of the backward volume spin wave (BVSW) excited by arbitrarily oriented linear transducer in tangentially magnetized ferrite film are investigated experimentally in the plane of ferrite film for the case where the transducer length D is much larger than the wavelength λ0. Superdirected BVSW beam having zero angular width and minimal smearing of the beam energy along the film surface is observed experimentally. Thus, it is proved that such phenomenon as “superdirected propagation of the wave” exists in the nature.

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Harris, John G. "The Wavefield Radiated Into an Elastic Half-Space by a Transducer of Large Aperture". Journal of Applied Mechanics 55, n.º 2 (1 de junho de 1988): 398–404. http://dx.doi.org/10.1115/1.3173689.

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The wavefield radiated into an elastic half-space by an ultrasonic transducer, as well as the radiation admittance of the transducer coupled to the half-space, are studied. Two models for the transducer are used. In one an axisymmetric, Gaussian distribution of normal traction is imposed upon the surface, while in the other a uniform distribution of normal traction is imposed upon a circular region of the surface, leaving the remainder free of traction. To calculate the wavefield, each wave emitted by the transducer is expressed as a plane wave multiplied by an asymptotic power series in inverse powers of the aperture’s (scaled) radius. This reduces the wave equations satisfied by the compressional and shear potentials to their parabolic approximations. The approximations to the radiated waves are accurate at a depth where the wavefield remains well collimated.

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Wei, Yanfei, Xin Yang, Yukai Chen, Zhihe Zhang e Haobin Zheng. "Modeling of High-Power Tonpilz Terfenol-D Transducer Using Complex Material Parameters". Sensors 22, n.º 10 (16 de maio de 2022): 3781. http://dx.doi.org/10.3390/s22103781.

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The loss effect in smart materials, the active part of a transducer, is of significant importance to acoustic transducer designers, as it directly affects the important characteristics of the transducer, such as the impedance spectra, frequency response, and the amount of heat generated. It is therefore beneficial to be able to incorporate energy losses in the design phase. For high-power low-frequency transducers requiring more smart materials, losses become even more appreciable. In this paper, similar to piezoelectric materials, three losses in Terfenol-D are considered by introducing complex quantities, representing the elastic loss, piezomagnetic loss, and magnetic loss. The frequency-dependent eddy current loss is also considered and incorporated into the complex permeability of giant magnetostrictive materials. These complex material parameters are then successfully applied to improve the popular plane-wave method (PWM) circuit model and finite element method (FEM) model. To verify the accuracy and effectiveness of the proposed methods, a high-power Tonpilz Terfenol-D transducer with a resonance frequency of around 1 kHz and a maximum transmitting current response (TCR) of 187 dB/1A/μPa is manufactured and tested. The good agreement between the simulation and experimental results validates the improved PWM circuit model and FEA model, which may shed light on the more predictable design of high-power giant magnetostrictive transducers in the future.

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Mais fontes

Teses / dissertações sobre o assunto "Plane-Wave transducer"

Scott, Leigh-Ann. "Plane wave expansion analysis of lossy composite transducers incorporating anisotropic polymers". Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444097.

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Manoochehrnia, Pooyan. "Characterisatiοn οf viscοelastic films οn substrate by acοustic micrοscοpy. Direct and inverse prοblems". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH38.

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Dans le cadre de cette thèse de doctorat, la caractérisation des films épais et minces déposés sur un substrat a été réalisée à l'aide de la microscopie acoustique via des algorithmes de résolution de problèmes directs et inverses. La méthode de Strohm est utilisée pour la résolution directe des problèmes, tandis qu'une variété de modèles mathématiques comprenant le modèle de la série de Debye (DSM), le modèle de la ligne de transmission (TLM) et la méthode spectrale utilisant le modèle de la rapport entre les réflexions multiples (MRM) ont été utilisés pour résoudre les problèmes inverses. Une application spécifique de la microscopie acoustique a été utilisée, consistant à monter des transducteurs à ondes planes à haute fréquence (50 MHz et 200 MHz) au lieu d'utiliser les transducteurs à focalisation traditionnels utilisés pour l'imagerie acoustique, ainsi qu'à utiliser le A-Scan à ondes complètes, qui pourrait être étendu à l'analyse en vrac des A-Scan consécutifs. Les modèles ont été validés expérimentalement par un film épais en époxy-résine d'une épaisseur d'environ 100μm et un film mince en vernis d'environ 8μm. Les paramètres caractérisés comprennent des paramètres mécaniques (par exemple la densité et l'épaisseur) ainsi que des paramètres viscoélastiques (par exemple la vitesse longitudinale acoustique et l'atténuation acoustique) et parfois le déphasage du transducteur
In the framework of this PhD thesis, the characterisation of the thick and thin films deposited on asubstrate has been done using acoustic microscopy via direct and inverse problem-solving algorithms.Namely the Strohm’s method is used for direct problem-solving while a variety of mathematical modelsincluding Debye series model (DSM), transmission line model (TLM) and spectral method using ratiobetween multiple reflections model (MRM) have been used to solve inverse-problem. A specificapplication of acoustic microscopy has been used consisting of mounting the plane-wave high frequency(50 MHz and 200MHz) transducers instead of use of the traditional focus transducers used for acousticimaging as well as using full-wave A-scan which could be well extended to bulk analysis of consecutivescans. Models have been validated experimentally by a thick film made of epoxy-resin with thicknessof about 100μm and a thin film made of polish of about 8μm. The characterised parameters includemechanical parameters (e.g. density and thickness) as well as viscoelastic parameters (e.g. acousticlongitudinal velocity and acoustic attenuation) and occasionally transducer phase-shift

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Warriner, Renee. "Development of Methods for Retrospective Ultrasound Transmit Focusing". Thesis, 2012. http://hdl.handle.net/1807/34958.

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Single frame ultrasound B-mode image quality is largely governed by the ability to focus the ultrasound beam over a range in depths both in transmission and reception. By developing a comprehensive understanding of acoustic wave propagation two signal processing methods were identified for solving the transmission problem. We made use of both the impulse response using the classical point spread function (PSF) and the spatial sensitivity function (SSF) which describes the spatial distribution at a particular time. Using the angular spectrum method, an accurate analytical model was developed for the field distribution arising from a finite geometry, apodized and focused, plane piston transducer. While there is a thorough understanding of the radiated field arising from uniformly excited plane piston transducers, the focused equivalent (i.e., one that allows a continuous change in phase over the plane piston surface) is incomplete and assumes the Fresnel approximation. Our model addresses the effects of diffraction and evanescent waves without the use of the Fresnel approximation and is applicable at all near- and far-field locations in a lossless medium. The model was analyzed to identify new insights into wave propagation and compared with the Fresnel approximation and the spherically-focused, concave transducer. The piston transducer model was then extended to an attenuating and dispersive medium. After analysing existing models of power-law frequency dependent attenuation, a causal, spherical wave Green’s function was derived from the Navier-Stokes equation for a classical viscous medium. Modifications to the angular spectrum method were presented and used to analyze the radiated field of a focused, planar piston transducer. Finally, after presenting our signal processing strategy for improving imaging spatial resolution through minimization of the SSF, two signal processing methods were derived and analysed in simulation: a deconvolution technique to remove the effects of the ultrasound excitation wave and suppress additive noise from the received ultrasound signal, and a retrospective transmit focusing method that changed the response from a predefined transmit focus to an arbitrary transmit focal depth. Proof-of-concept simulations were presented using a variable number of scatterers and compared with the traditional matched filtering and envelope detection technique.

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Livros sobre o assunto "Plane-Wave transducer"

Hansen, Thorkild, e Arthur D. Yaghjian. Plane-Wave Theory of Time-Domain Fields: Near-Field Scanning Applications (IEEE Press Series on Electromagnetic Wave Theory). Wiley-IEEE Press, 1999.

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Capítulos de livros sobre o assunto "Plane-Wave transducer"

Schiffner, Martin F., e Georg Schmitz. "Plane Wave Pulse-Echo Ultrasound Diffraction Tomography with a Fixed Linear Transducer Array". In Acoustical Imaging, 19–30. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-2619-2_3.

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Cobbold, Richard S. C. "Scattering of Ultrasound". In Foundations of Biomedical Ultrasound, 268–328. Oxford University PressNew York, NY, 2006. http://dx.doi.org/10.1093/oso/9780195168310.003.0005.

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Abstract Because of the complex structure of most biological media, the scattered signal arising from an incident pulsed ultrasound beam is generally difficult to fully interpret, even when details of the structure are available. To address this problem, it is helpful to start by assuming a plane harmonic wave incident on a simple symmetrical scattering structure. Now any incident harmonic wave can be treated as a superposition of plane harmonic waves, and any pulse can be transformed into a spectrum of frequencies, so that a solution to the plane harmonic wave scattering problem enables a more general problem to be solved. Many methods of solution have been used, all of which are based on either exact or approximate solution of the wave equation. The boundary value method, initially used by Rayleigh [1,2] to obtain approximate solutions for spherical and cylindrical scatterers by acoustic waves, will first be studied. Small spherical scatterers are frequently used to model the structure of soft biological media [3], and in addition a simple spherical scatterer or a smalldiameter wire is sometimes used to measure the pulse-echo response of an ultrasound transducer. Moreover, an array of such objects can be used to determine the performance of an imaging system. A Green’s function approach can be used to arrive at an integral solution for the scattered wave, and this is especially helpful when the density and compressibility of the scattering region vary in a continuous manner. Since the integrand involves the sum of the incident and scattered fields, it is generally appropriate to make the Born approximation in which the scattered field is assumed to be small compared to that incident.

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Newnham, Robert E. "Acoustic waves II". In Properties of Materials. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780198520757.003.0026.

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Acoustic impedance, acoustic losses, acoustic waves in piezoelectric solids, and surface waves are discussed in this chapter, along with a number of nonlinear acoustic phenomena. The reflection and transmission of acoustic waves across a boundary is governed by acoustic impedance. One of the most important boundary value problems in acoustics concerns a plane wave incident upon a planar surface, dividing one medium from another. In the general case of an anisotropic medium, the incident beam consists of three waves (one quasilongitudinal, two quasitransverse), each traveling at a different velocity. Each of the three incident waves will be refracted and reflected at the boundary. If the second medium is also anisotropic, each incident wave will generate three reflected waves and three refracted waves, a total of 27 waves in all. Wave propagation in a polycrystalline solid where there are many grain boundaries becomes very complicated. The simpler case of a pure longitudinally-polarized wave at normal incidence to the boundary provides insight into the more general problem. In this case the reflection and transmission coefficients are governed by the relatively simple acoustic impedance parameter (ρc)1/2 = ρv, where ρ is the density, c the stiffness coefficient, and v the phase velocity. The reflection coefficient R at the interface between medium I and medium II is The MKS unit for acoustic impedance is the Rayl (=kg/m2 s). Atypical value for a solid is about 107 rayls. In many acoustic applications it is desirable to reduce reflection by matching the acoustic impedance of the two media. Lithium tantalate transducers are well-matched to iron, for example. Sound transmission from the transducer to the medium can be enhanced with composite materials or with graded coupling layers. Backing materials are often selected to promote reflection. In this case acoustic impedances are mismatched. Tungsten and air are two commonly used backing materials. In an isotropic material the acoustic impedance is (ρc11)1/2 for longitudinal waves and (ρc44)1/2 for shear waves. For anisotropic materials the wave velocities and acoustic impedance change with direction as indicated earlier.

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Kramer, S. M., D. A. Hutchins e H. D. Mair. "USE OF PLANE AND EDGE WAVE COMPONENTS TO CHARACTERIZE PVDF TRANSDUCERS". In Ultrasonics International 87, 838–43. Elsevier, 1987. http://dx.doi.org/10.1016/b978-0-408-02348-1.50144-x.

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Trabalhos de conferências sobre o assunto "Plane-Wave transducer"

Alomari, Zainab, Sevan Harput, Safeer Hyder e Steven Freear. "The Effect of the transducer parameters on spatial resolution in Plane-Wave imaging". In 2015 IEEE International Ultrasonics Symposium (IUS). IEEE, 2015. http://dx.doi.org/10.1109/ultsym.2015.0547.

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Nguyen, Man M., Sheng-Wen Huang, Shiwei Zhou, Chanzhona Hu, Nik Ledoux, Bernard Savord, Vijay Shamdasani e Hua Xie. "Real-Time X-Plane Shear Wave Elastography Feasibility on Philips 2D xMatrix Transducer". In 2018 IEEE International Ultrasonics Symposium (IUS). IEEE, 2018. http://dx.doi.org/10.1109/ultsym.2018.8580080.

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Герус, Sergey Gerus, Локк e Edvin Lokk. "Diffraction patterns of the backward spin wave exited in ferrite film by linear transducer". In XXIV International Conference. Москва: Infra-m, 2016. http://dx.doi.org/10.12737/23115.

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Visualized diffraction patterns describing in-plane distribution of the backward spin wave beam, excited by linear transducer, are investigated for the case when the spin wave length is much smaller than the transducer length. The angular width of the spin-wave beams is founded for several geometries experimentally and theoretically. There is good agreement between the experimental and theoretical values of the angular beam width.

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Герус, Sergey Gerus, Локк, Edvin Lokk, Анненков e A. Annenkov. "Diffraction patterns and angular width of the surface spin wave beams exited in ferrite film by linear transducer". In XXIV International Conference. Москва: Infra-m, 2016. http://dx.doi.org/10.12737/23117.

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Visualized diffraction patterns describing in-plane distribution of the surface spin wave beam, excited by linear transducer, are investigated for the case when the spin wave length is much smaller than the transducer length. On the basis of experimental diffraction patterns and on the basis of theoretical calculations (both numerically and based on obtained previously general formula) the angular width of the spin-wave beams is founded for several geometries. There is good agreement between the experimental and theoretical values of the angular beam width.

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Герус, Sergey Gerus, Локк, Edvin Lokk, Анненков e A. Annenkov. "Comparison of a diffraction pattern of the surface spin wave beam with distribution of its magnetic potential in the plane of ferrite film". In XXIV International Conference. Москва: Infra-m, 2016. http://dx.doi.org/10.12737/23116.

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The visualized diffraction pattern of the surface spin wave beam excited by the linear transducer in tangentially magnetized ferrite film was compared with calculated in-plane distribution of magnetic potential of this beam. It is found that distribution of the wave magnetic potential and experimental diffraction pattern (distribution) of the spin wave in the film plane are in good agreement not only for the film area, where is localized main diffractive beam, but also for the area where the maxima of lower order are located.

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Sadeghpour, Sina, Rui Amendoeira e Michael Kraft. "Ultrasound Imaging With a 128 Channels Piezoelectric Micromachined Ultrasound Transducer (pMUT): Single-Line-Transmission vs. Plane-Wave". In 2023 IEEE International Ultrasonics Symposium (IUS). IEEE, 2023. http://dx.doi.org/10.1109/ius51837.2023.10306475.

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Zhuang, Linqi, Adarsh Chaurasia e Ali Najafi. "Impact Damage Evaluations in a Composite Laminate Using Guided Wave-Based Simulation". In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-95057.

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Abstract In the present paper, guided wave propagation along a composite plate was simulated using a 3D Finite Element (FE) model in order to characterize the potential damage due to impact. The wave is induced by a piezoelectric transducer. A pristine composite case and various cases representing different commonly observed impact damage modes were created. The wavefield contour and out-of-plane displacement data at different sensors between the pristine and damage cases were then compared to differentiate type of damage existing within the composite plate. It is found that observed wave propagation pattern and signals had significant difference between delamination cases and pristine one and the maximum amplitude of out-of-plane displacement of the plate during wave propagation increases with increasing delamination size when wave reaches and passes damaged area. The wave propagation in a composite plate with earlier stage damage, i.e., matrix cracks simulated in the present study, however, shows little difference compared to the pristine case for the wavelet frequencies studied herein.

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ROUT, SURAJ KUMAR, e SANTOSH KAPURIA. "LAMB WAVE ACTUATION AND PROPAGATION USING FLEXOELECTRIC TRANSDUCERS". In Structural Health Monitoring 2023. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/shm2023/36848.

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In recent years, actuation and propagation using a relatively novel electromechanical effect, namely flexoelectricity, have become an emerging field of research. In this article, we explore the use of flexoelectric dielectrics for Lamb wave actuation and propagation for structural health monitoring (SHM) applications. Towards this objective, an analytical solution is presented for Lamb wave generation and propagation in plate-like structures using flexoelectric-piezoelectric transducers bonded to the host plate surface through an adhesive layer. The model considers both interfacial shear and peel stresses at the interface of the transducer and the plate. These interfacial stresses under applied electric actuation are determined based on a one-dimensional (1D) model, which assumes Kirchhoff plate-like behaviour for both the actuator and the host plate. A 2D elasticity solution is obtained for Lamb wave propagation in the host plate under the interfacial shear and peel stresses obtained from the above 1D model considering plane strain conditions. This solution is obtained in the wave number domain by applying Fourier transform spatially. Finally, the response is obtained in the physical domain by applying the inverse Fourier transform and residue theorem. The strain response at the plate surface is compared with the rigid bonding model to illustrate the effect of bonding compliance. The numerical study demonstrates the effect of the adhesive layer on the response for different excitation frequencies.

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Silva, Glauber T., e Mostafa Fatemi. "On the Calculation of Radiation Force on Spheres Due to Arbitrary Spatially Distributed Acoustic Beams". In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-85660.

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This work presents a theory for the acoustic radiation force exerted on a solid sphere by an arbitrary spatially distributed beam. The theory is developed for an sphere suspended in an ideal fluid. We assume that the acoustic beam can be decomposed in a set of plane waves with same frequency, propagating in different directions. The sphere radius is considered to be much smaller than the wavelength of the beam. Bulk properties of the sphere such as shear and compressional sound speed are taken into account. The radiation force is obtained by solving the linear acoustic scattering problem for the sphere. Theoretically, the radiation force depends on the sphere cross section area, the radiation force function, and the vector energy flux upon the sphere. The radiation force function is related to the sphere scattering properties. We apply the developed theory to study the radiation force produced by an spherical concave transducer. The generated radiation force can be decomposed into two components, namely, axial and transverse with respect to the wave propagation direction. The ratio between the transverse and axial components of the force depends on the transducer F-number and wave frequency. Results show that this ratio for a 2 MHz transducer with 3.5 F-number on the focal plane is less than 5%.

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Wojcik, Gregory L., John C. Mould e Laura M. Carcione. "Combined Transducer and Nonlinear Tissue Propagation Simulations". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0216.

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Abstract Ultrasonic imaging system evaluation is often based on models of the transducer as a distribution of baffled piston sources, and of the tissue as a homogeneous, linear acoustic medium, e.g., Jensen’s Field code. In reality, these are fairly gross idealizations, since the transducer exhibits more complicated response modes and real tissue is inhomogeneous and nonlinear. Greater model fidelity would be useful, especially in the context of transducer design qualification, second harmonic imaging, and acoustic power indices. To this end we combine 2D finite element models of transducer dynamics with highly accurate 2D finite difference propagation models in the large-scale inhomogeneous tissue cross-sections. Transducer models employ the time-domain code, PZFlex, and tissue models utilize a new pseudospectral solver to be included in PZFlex. The pseudospectral algorithm solves the inhomogeneous acoustic wave equation using FFTs for high order approximation of the spatial differential operator and a fourth-order, explicit time integrator. Second-order (B/A) nonlinearity and frequency-accurate, causal absorption are included. We describe the algorithmic and modeling issues, and present a suite of simulations in lossy, nonlinear abdominal cross sections and tissue showing coupling of the 1D medical array to the tissue model and scattering from deeper inhomogeneities and back to the transducer. In contrast to paraxial schemes, like the KZK method, details of the field transmitted from the transducer and all backscatter within the model are included. However, models are currently limited to 2D (plane or axisymmetric) on readily available hardware.

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