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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 4 • Date July 1994

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Displaying Results 1 - 22 of 22
  • Historical note: Warren P. Mason (1900-1986) physicist, engineer, inventor, author, teacher

    Page(s): 425 - 434
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    This paper is based on an invited talk in the Warren P. Mason Memorial Session at the 117th meeting of the Acoustical Society of America, Syracuse, NY, May 22-26, 1989. Warren Perry Mason, a Charter Member, Fellow, President, and Gold Medalist of the Acoustical Society of America, consistently applied his understanding of fundamentals to explain physical processes and create practical devices. As a physicist, he led us to a better understanding of fundamental effects in liquids and solids. He made the first measurement of shear elasticity in liquids and helped establish the type of motion that polymer chains can make. In solids, he contributed to quantitative understandings of phonon drag on charge carriers in semiconductors, fatigue of metals, and damping of acoustic waves in metals, insulators, semiconductors, alloys, and rocks. As an engineer and inventor, he led advances in mufflers and noise control, electromechanical filters for carrier frequency telephony, piezoelectric crystals and ceramics for electromechanical transducers, and semiconductor strain gauges. With about 200 patents, he is the most prolific inventor in the history of Bell Labs. As an author and teacher, he wrote more than 200 papers and four reference books that teach fundamental concepts, give complete tensorial descriptions of numerous physical interactions in crystals, describe research results, and guide the reader to the related literature. In this paper, we show some early pictures of Mason and his family, transmit some stories, and give an example of a communication device in which Mason would surely have been interested, namely an acoustically tuned optical filter.<> View full abstract»

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  • Non-Gaussian versus non-Rayleigh statistical properties of ultrasound echo signals

    Page(s): 435 - 440
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    Parameters expressing the non-Gaussian and the non-Rayleigh properties of ultrasound echo signals are derived for the case of a pulsed transducer insonifying a medium containing randomly distributed scatterers. Both parameters depend on the measurement system, including the transducer field and pulse frequency content, as well as on the medium's properties. The latter is expressed in terms of the number of scatterers per unit volume and the second and fourth moments of the medium's scattering functions. A simple relationship between the parameters describing the non-Gaussian and non-Rayleigh properties is derived and verified experimentally.<> View full abstract»

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  • Quantitative modeling of the anisotropy of ultrasonic backscatter from canine myocardium

    Page(s): 441 - 450
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    Reports extensions and new results of the First Time Domain Born approximation model used by Mottley and Miller (1982) to describe the anisotropy of ultrasonic backscatter measured in canine myocardium. The interaction of an ultrasonic plane wave impulse with a single cylindrical scatterer using time and frequency domain approaches is reviewed. Myocardial tissue is modeled as a suspension of aligned cylindrically shaped scatterers uniformly distributed in a homogeneous medium. The authors propose extensions to this model to deal with nonideal scatterer orientation, by introducing axial distribution functions and scatterer size distributions based on histology, modeled as a uniform distribution. The backscatter coefficient in the range 2.0-8.0 MHz is calculated. An algorithm to compute the average differential scattering cross section is presented. Ultrasonic elastic properties of myocardial tissue are discussed. Results of the anisotropy of the numerically computed backscatter parameters for model media having nominal mechanical and acoustic properties of canine myocardial tissue are presented and compared to available experimental data along with discussion of possible conclusions.<> View full abstract»

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  • Acoustic microscopy: a study of contrast in fresh tissue

    Page(s): 451 - 457
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    The scanning laser acoustic microscope (SLAM), which exhibits a resolution of about 15 /spl mu/m in biological materials, was operated at a frequency of 100 MHz to evaluate the source of image contrast. Specifically, the SLAM's quantitative capabilities yielded the ultrasonic propagation properties of attenuation coefficient and propagation speed of rat brain tissue (white versus gray matter) and these properties mere correlated with tissue constituents and image contrast. The SLAM's image contrast between the two brain layers in both fresh and fixed specimens was analyzed subjectively by an experienced microscopist. It was determined that ethanol fixation decreased the image contrast between the brain layers. Additionally, the propagation speed was the least affected property in the fresh tissue specimens yet increased in both brain layers after fixation whereas the attenuation coefficient of white matter in unfixed brain tissue was higher than that of gray matter. These results indicate that the SLAM's acoustic image contrast is a direct reflection of the difference in attenuation coefficient whereas the propagation speed is not a significant contributor to the image contrast.<> View full abstract»

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  • Longitudinal critical angle singularities and their effect on V(Z) of the line-focus-beam acoustic microscope

    Page(s): 458 - 466
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    In order to investigate a mechanism which causes a velocity difference between the longitudinal wave and leaky surface skimming compressional wave (LSSCW) observed in a line-focus-beam acoustic microscope, the analytic property of an acoustic reflection coefficient and its effect on a V(z) analysis were studied. A pole hidden in the unphysical Riemann sheet close to the longitudinal branch point is found to be responsible for the abrupt phase change at the longitudinal critical angle. This, together with an effect of a dominant Rayleigh wave pole, affects the V(z) measurement of the LSSCW. A method to estimate the longitudinal and shear wave velocities is discussed.<> View full abstract»

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  • International round robin in infrared alpha measurements on slices of synthetic quartz

    Page(s): 467 - 472
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    An International Round Robin (IRR) has been completed in the measurement of three infrared extinction coefficients (alphas) used in the recent quality specification for synthetic quartz as revised and augmented by the International Electrotechnical Commission (IEC), to be known as the Second Edition of IEC Publication 758. These results, more comprehensive than from earlier round robins, have enabled an improved standardization and coordination of alpha test limits at the three wavenumbers in international use: 3410, 3500, and 3585 cm/sup -/. The IRR revealed that among the 17 participating infrared instruments used each had its individual three long term biases (within the claimed ranges of instrument accuracy). Low range corrections to the alphas for participating instruments have been reported by the IRR committee to participants and at a 1992 US Electronic Industries Association meeting. The alpha interrelationships from this round robin also enable improved coordination of 5 MHz Q indication formulas in the three measured alphas for those who need to refer to alpha-indicated Q's. The grade test limits as stated in alphas, now accepted for direct standard test use, bypass Q calibrations and other potential sources of grading confusion. The convergence of alpha averages as the IRR results were recorded suggests that they are stable and, will contribute to improved coordination of synthetic quartz grading.<> View full abstract»

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  • Pure-mode measurements of Li/sub 2/B/sub 4/O/sub 7/ material properties

    Page(s): 473 - 478
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    Recent measurements of doubly rotated plate resonators have highlighted the need for more accurate material constants for use in dilithium tetraborate resonator design. In this paper, we report on the room-temperature determination of the elastic, piezoelectric, and dielectric constants of dilithium tetraborate using frequency domain measurements of primarily pure-mode vibrations in thin, flat plates.<> View full abstract»

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  • Deposition and piezoelectric characteristics of ZnO films by using an ECR sputtering system

    Page(s): 479 - 483
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    Piezoelectric properties of ZnO films, were investigated by using an Electron Cyclotron Resonance (ECR) sputtering system. It was confirmed that this system was capable of depositing a ZnO film with a large specific resistance, and good c-axis orientation on an interdigital transducer (IDT)/glass substrate at a low temperature (less than 200/spl deg/C) and in a low gas pressure (/spl sim/10/sup -4/ torr). Furthermore, these ZnO films exhibited excellent SAW characteristics (insertion losses) and effective electromechanical coupling factors (k/sub eff/) compared with ZnO films deposited by a conventional RF magnetron sputtering system. Further, this ECR sputtering system was capable of depositing a ZnO film, without heating the substrate, that was capable of propagating a Rayleigh SAW at 700 MHz for the first time.<> View full abstract»

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  • Analytic evaluation of sampled aperture ultrasonic imaging techniques for NDE

    Page(s): 484 - 493
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    This paper presents a theoretical comparison of three generic sampled aperture ultrasonic imaging systems for nondestructive evaluation. The imaging systems are categorized according to their source-receiver combination for data acquisition: common-source, back-scatter, and full-array imaging. First, forward modeling is performed for a point source and a point receiver. This is then used to model the received data set for each of the imaging categories. Subsequently, the inversion algorithm for each category is derived, and their performance is evaluated in terms of resolution, noise, and computation. We show that in terms of resolution, back-scatter imaging is the best, followed by full-array and common-source imaging. However, in terms of material noise, full-array imaging is the best, with back-scatter and common-source imaging having the same material noise response. Full-array imaging is the only system with inherent redundancy to reduce electronic noise, but at the expense of significantly more computation. The physical transducer is in the full-array category, allowing mechanical scanning to be traded for dynamic focusing and computational power.<> View full abstract»

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  • Measurement of acoustic reflection coefficients by an ultrasonic microspectrometer

    Page(s): 494 - 502
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    An ultrasonic microspectrometer (UMSM) was developed in order to evaluate the elastic properties of a solid specimen at a small spot on its surface. In this system, spherical-planar-pair (SPP) lenses were used, by which the acoustic reflection coefficient of a liquid/solid interface was measured as a function of the incident angle in the frequency range from 20 to 140 MHz. Using a specimen of fused quartz whose material constants were well known, the measurement accuracy was examined. The phase velocity of a leaky Rayleigh wave was obtained from the phase change of the reflection coefficient with 0.4% accuracy in this frequency range. For a specimen of steel with a large acoustic attenuation, bulk attenuation factors and their frequency dependence were successfully estimated by computer-fitting of the reflection coefficient. As an example of anisotropic materials, the reflection coefficient of X-cut quartz was also measured. Measured phase of the reflection coefficient was in good agreement with numerical calculation.<> View full abstract»

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  • A discrete one component wave model and its application to SAW resonator filters

    Page(s): 503 - 511
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    A one component acoustic bulk wave model is presented for the description of SAW devices using plane waves or waveguide modes. No equivalent circuit components are used, and the calculations always remain on the level of acoustic waves. As fundamental elements the transfer matrix and the source vector of one electrode region are derived. Using these elements, the particle displacements in an array consisting of striplike electrodes can be calculated as a function of all single capacitor voltages taking into account the boundary conditions including the amplitudes of foreign waves meeting the array. After determining the waveguide mode velocities and profiles the model is applied to transversely coupled waveguide resonator filters resulting in the admittance matrix which is needed to calculate the filter insertion loss. Two filter examples are investigated, and a sufficiently good agreement of the theoretical and experimental results is found. The resonance splitting due to cascading of two (or more) single resonator filters can be increased by a coupling inductor yielding a smaller insertion loss under matched conditions at a given bandwidth.<> View full abstract»

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  • Scanning electron microscopy observation of surface acoustic wave propagation in the LiNbO/sub 3/ crystals with regular domain structures

    Page(s): 512 - 517
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    This paper reports a scanning electron microscopy investigation of surface acoustic wave propagation in the LiNbO/sub 3/ crystals with regular domain structures. The regular domain structures in the LiNbO/sub 3/ crystals were formed by the method of the thermo-electric treatment after growth. We investigated two modes of the interaction between the surface acoustic waves and regular domain structures in the LiNbO/sub 3/ crystals: excitation of the surface acoustic waves by the curved regular domain structure, and propagation of the surface acoustic waves along and across the regular domain structures. It is shown that the regular domain structure in the first case can be used as an interdigital transducer for excitation of the surface acoustic waves through the longitudinal piezoelectric effect. In the second mode of the interaction we observed that the regular domain structure can be used as an acoustic wave-guide in the process of the propagation of the traveling surface acoustic waves along the regular domain structure. Also, we demonstrate the reflection of the surface acoustic waves from the domain walls in the process of surface acoustic wave propagation across the regular domain structure.<> View full abstract»

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  • Reducing local oscillator phase noise limitations on the frequency stability of passive frequency standards: tests of a new concept

    Page(s): 518 - 521
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    We report on the experimental test of a new concept for reducing the limitation on short-term frequency stability of passive frequency standards due to local oscillator phase noise. This concept is general and can be applied to many passive frequency standards. Systems that use sinewave modulation to interrogate a stable resonance are limited in short-term frequency stability by phase noise at the second harmonic of the modulation, f/sub m/. This effect limits the fractional frequency stability to approximately /spl sigma//sub v/(/spl tau/7)=0.9(f/sub m///spl nu//sub 0/) (S/sub /spl phi//(2f/sub m/))/sup 1/2//spl tau//sup -1/2/, where /spl nu//sub 0/ is the carrier frequency and S/sub /spl phi//(2f/sub m/) is the phase noise at twice the modulation frequency. (Contributions from higher even harmonics of the modulation generally can be neglected). This new concept uses notch filters at /spl plusmn/2f/sub m/ from the carrier to reduce this effect. Tests on a modified passive rubidium standard demonstrate an improvement of approximately 18 in /spl sigma//sub y/(/spl tau/). The dual notch filters proved to be feasible and were obtained commercially. Measurements suggest that ultimate performances of less than 2/spl times/10/sup -14//spl tau//sup -1/2/ are possible if the atomic resonance has sufficient quality.<> View full abstract»

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  • Multifrequency Doppler: improving the quality of spectral estimation by making full use of the information present in the backscattered RF echoes

    Page(s): 522 - 531
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    This paper investigates the application of the two-dimensional Fourier transform in the context of pulsed wave Doppler. It is shown that two-dimensional spectral analysis of the backscattered RF echoes provides individual Doppler spectra corresponding to the whole range of transmitted frequencies which can be combined, after proper scaling, to form a "multifrequency" spectral estimate. Theoretical expressions are derived for the signal-to-noise ratio of the multifrequency sonogram which predict substantial gains over the conventional (one-dimensional) approach for Doppler processing. These predictions are verified by means of extensive simulations, which also provide an insight into the effect of electronic noise.<> View full abstract»

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  • The use of linear programming for the design of SAW filters and filterbanks

    Page(s): 532 - 541
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    A linear programming algorithm is proposed for designing surface acoustic wave (SAW) filters or filterbanks with arbitrary amplitude and phase responses. A modified sampling theorem representation is employed for the transducer frequency responses which allows the number of independent variables to be minimized without degrading the filter characteristics. The method can also be used as part of an iterative procedure to generate optimal corrections for second order effects such as diffraction and circuit loading. A simplified algorithm for this procedure is given, and the method is illustrated with theoretical and experimental data from a three channel contiguous SAW filterbank design. Although the method given in this paper is formulated primarily for SAW filters, it is equally applicable to FIR digital filter design.<> View full abstract»

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  • Calculation of quasi-static electromechanical coupling coefficients for electrostrictive ceramic materials

    Page(s): 542 - 551
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    The quasi-static coupling coefficients, k/sub 13/ and k/sub 33/, for electrostrictive ceramics are computed analytically. The calculation is based on a three-dimensional constitutive relation that models both electrostriction and nonlinear dielectric behaviors. The results show that the coupling factors depend on the amplitudes of the applied ac field and the dc bias, as well as the mechanical prestress. For an actuator without bias voltage or prestress, the coupling coefficients approach an asymptotic value with increasing electric field. The primary coefficients, k/sub 13/ and k/sub 33/, for a lead magnesium niobate, Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/BaTiO/sub 3/(PMN-PT-BT), based relaxor ferroelectric are computed as an example. The results show that the coupling coefficients for PMN-PT-BT materials are roughly comparable with those of existing piezoelectrics. These coefficients are important parameters for material section and power source design for transducer devices.<> View full abstract»

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  • Surface-micromachined pyroelectric infrared imaging array with vertically integrated signal processing circuitry

    Page(s): 552 - 555
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    Surface-micromachining techniques have been used in the fabrication of a 64/spl times/64 element PbTiO/sub 3/ pyroelectric infrared imager. Polysilicon microbridges of 1.2 /spl mu/m-thickness have been formed 0.8 /spl mu/m above the surface of a silicon wafer. Each of the 4096 polysilicon microbridges measures 50/spl times/50 /spl mu/m/sup 2/ and forms a low thermal mass support for a 30/spl times/30 /spl mu/m/sup 2/ PbTiO/sub 3/ pyroelectric capacitor with a thickness of 0.36 /spl mu/m. The air-bridge formed reduces the thermal conduction path between the detector element and substrate. An NMOS preamplifier cell is located directly beneath each microbridge element. The measured blackbody voltage responsivity at 30 Hz is 1.2/spl times/10/sup 4/ V/W. The corresponding measured normalized detectivity (unamplified) D* is 2/spl times/10/sup 8/ cm-Hz/sup 1/2/W at 30 Hz. The test chip fabricated measures 1/spl times/1 cm/sup 2/ and contains more than ten thousand transistors and 4096 micromechanical structures with integrated ferroelectric microsensors. The technique of stacking of microsensors and integrated circuits represents a new approach for achieving high-density and high-performance integrated pyroelectric microsensors through minimization of circuit to sensor interconnection with extremely small thermal crosstalk.<> View full abstract»

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  • Piezoelectric performance of piezoceramic-polymer composites with 2-2 connectivity-a combined theoretical and experimental study

    Page(s): 556 - 564
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    The piezoelectric performance of piezoceramic-polymer composites with 2-2 connectivity at low frequency has been analyzed theoretically. Due to the elastic coupling between the ceramic and polymer phases, the strain components in directions perpendicular and parallel to the ceramic-polymer interface are not uniform in either phase. As a result, most of the stress transfer between the two phases occurs at the region near the surface of the composite. In order to improve the piezoelectric performance of a composite, the polymer matrix should have a small Young's modulus and a large shear modulus, and a large aspect ratio. It may be also desirable to have the polymer matrix made of two different polymers with the stiffer one near the surface and the softer one in the interior of the composite. To compare with the theoretical calculations, surface profiles of a series of 2-2 composites with different aspect ratios were measured, and the experimental results show excellent agreement with the theoretical calculations. The nonuniform strain and stress in the direction parallel to the ceramic-polymer interface of a composite were also confirmed by experiments.<> View full abstract»

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  • Thermal effects in scanning acoustic microscopy for fine resolution applications

    Page(s): 565 - 568
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    A novel scanning acoustic microscopy technique for achieving high resolution acoustic images by employing thermal effects and image subtraction has been studied and demonstrated. Experiments were performed on a perspex block patterned with a machined grid on the reverse surface, and on a buried channel in similar material. If was found that using the image subtraction technique, short periods of sample heating can lead to a stronger pattern selectivity, because of the strong temperature dependency of the elastic parameters of the polymer. In previous SAM techniques improvement in signal has been achieved through the use of special liquids as acoustic coupling media between the acoustic lens and the sample. The reported technique retains water as the coupling medium and the acoustic impedance matching is performed by varying the elastic parameters of the sample itself through direct heating. The temperature increase in the sample decreases the velocity of propagation of acoustic waves in the solid, and brings the acoustic impedance close to that of water. A theoretical model, including expressions for the acoustic aberrations, depth dependence and acoustic impedance matching has been derived. Examples of the results obtained are presented.<> View full abstract»

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  • Comments on "Efficient angular spectrum decomposition of acoustic sources-parts I and II"[with reply]

    Page(s): 568 - 571
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    Problems with the angular spectrum analysis of a recent pair of papers (see ibid., vol. 40, p. 238-49, 1993 and vol. 40, p. 250-57, 1993)are described. An alternative numerically correct approach is described and is used to efficiently and accurately re-compute a result considered in the original papers. The original authors give their reply to the comments.<> View full abstract»

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  • Dynamic analysis of modulated oscillators

    Page(s): 571 - 573
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    This paper provides a dynamic analysis method and model for analyzing oscillator circuits which may be modulated by nonlinear signals, or by linear signals which interact with nonlinear resonator elements to produce spurious modes. This method proves to be more general than a traditional static analysis and more accurately predicts oscillator performance over a wide range of modulation conditions.<> View full abstract»

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  • Frequency spectra of extensional vibration in isotropic short columns and thick circular disks

    Page(s): 573 - 576
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    A simple analytical method based on the equivalent elastic theory is presented for predicting the natural frequencies of a short column or a thick circular disk of axially symmetrical coupled vibration in which the longitudinal, the radial and the thickness extensional vibrations are considered. A critical value of thickness/diameter ratio is given that defines a boundary between a short column and a thick disk. Theoretical analyses show that the longitudinal and radial vibrations in infinite length rods, the radial and thickness extensional vibrations in thin plate are the special vibrating modes of a short column or a thick disk. The calculated frequencies for an isotropic column or a disk are in good agreement with the measured results.<> View full abstract»

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Aims & Scope

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control focuses on the theory, design, and application on generation, transmission, and detection of bulk and surface mechanical waves.

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Editor-in-Chief
Steven Freear
s.freear@leeds.ac.uk