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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 6 • Date June 2012

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  • IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control - Cover

    Publication Year: 2012 , Page(s): c1
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  • IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society - Elected Administrative Committee

    Publication Year: 2012 , Page(s): c2
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  • IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society

    Publication Year: 2012 , Page(s): c3
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  • Table of contents

    Publication Year: 2012 , Page(s): c4
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  • Information for contributors with multimedia addition

    Publication Year: 2012 , Page(s): 1071 - 1074
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  • A multimedia example

    Publication Year: 2012 , Page(s): 1075
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  • Surface periodic domain structures for waveguide applications

    Publication Year: 2012 , Page(s): 1076 - 1084
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB) |  | HTML iconHTML  

    We report the results of fabrication and investigations of surface periodic domain structures created by a set of quasi-point e-beam irradiations both on the Y- and X-cuts of LiNbO3, and on Ti:LiNbO3 and Zn:LiNbO3 planar waveguides. Domain gratings with spatial periods from 4.75 to 7.25 μm were formed by a 25-keV e-beam. Doses from 500 to 2000 μC/cm2 were used for different structures to estimate optimal fabrication conditions. The investigations allowed the visualization of the formed surface domain structures, estimation of their uniformity, and determination of waveguide generation of the second optical harmonic. The surface structures can be used in optical devices for the realization of quasi-phasematched frequency conversion, which includes the creation of compact radiation sources based on waveguides. View full abstract»

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  • Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications

    Publication Year: 2012 , Page(s): 1085 - 1092
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    The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads. View full abstract»

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  • Ultrasound beam simulations in inhomogeneous tissue geometries using the hybrid angular spectrum method

    Publication Year: 2012 , Page(s): 1093 - 1100
    Cited by:  Papers (2)
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    The angular spectrum method is a fast, accurate and computationally efficient method for modeling wave propagation. However, the traditional angular spectrum method assumes that the region of propagation has homogenous properties. In this paper, the angular spectrum method is extended to calculate ultrasound wave propagation in inhomogeneous tissue geometries, important for clinical efficacy, patient safety, and treatment reliability in MR-guided focused ultrasound surgery. The inhomogeneous tissue region to be modeled is segmented into voxels, each voxel having a unique speed of sound, attenuation coefficient, and density. The pressure pattern in the 3-D model is calculated by alternating between the space domain and the spatial-frequency domain for each plane of voxels in the model. The new technique was compared with the finite-difference time-domain technique for a model containing attenuation, refraction, and reflection and for a segmented human breast model; although yielding essentially the same pattern, it results in a reduction in calculation times of at least two orders of magnitude. View full abstract»

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  • The effects of transducer geometry on artifacts common to diagnostic bone imaging with conventional medical ultrasound

    Publication Year: 2012 , Page(s): 1101 - 1114
    Cited by:  Papers (2)
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    The portability, low cost, and non-ionizing radiation associated with medical ultrasound suggest that it has potential as a superior alternative to X-ray for bone imaging. However, when conventional ultrasound imaging systems are used for bone imaging, clinical acceptance is frequently limited by artifacts derived from reflections occurring away from the main axis of the acoustic beam. In this paper, the physical source of off-axis artifacts and the effect of transducer geometry on these artifacts are investigated in simulation and experimental studies. In agreement with diffraction theory, the sampled linear-array geometry possessed increased off-axis energy compared with single-element piston geometry, and therefore, exhibited greater levels of artifact signal. Simulation and experimental results demonstrated that the lineararray geometry exhibited increased artifact signal when the center frequency increased, when energy off-axis to the main acoustic beam (i.e., grating lobes) was perpendicularly incident upon off-axis surfaces, and when off-axis surfaces were specular rather than diffusive. The simulation model used to simulate specular reflections was validated experimentally and a correlation coefficient of 0.97 between experimental and simulated peak reflection contrast was observed. In ex vivo experiments, the piston geometry yielded 4 and 6.2 dB average contrast improvement compared with the linear array when imaging the spinous process and interlaminar space of an animal spine, respectively. This work indicates that off-axis reflections are a major source of ultrasound image artifacts, particularly in environments comprising specular reflecting (i.e., bone or bonelike) objects. Transducer geometries with reduced sensitivity to off-axis surface reflections, such as a piston transducer geometry, yield significant reductions in image artifact. View full abstract»

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  • Effects of frequency and bandwidth on diagnostic information transfer in ultrasonic B-Mode imaging

    Publication Year: 2012 , Page(s): 1115 - 1126
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1022 KB) |  | HTML iconHTML  

    Transmitted pressure pulses in ultrasonic Bmode imaging systems are commonly characterized by their center frequency and bandwidth. Both parameters are associated with tradeoffs in spatial resolution and signal-to-noise in ultrasonic system design, with no general understanding of where they are optimal when applied to specific clinical exams. We use the ideal observer and simple psychophysical studies with human observers to evaluate the efficiency of information transfer in B-mode imaging as a function of the transmitted pulse center frequency and fractional bandwidth. Our approach uses a statistical model of backscatter relevant to breast imaging, and a 2-D model of pulse propagation based on Rayleigh-Sommerfeld diffraction theory. The statistics of the backscattered signal are combined in an ideal observer calculation that quantifies the task-relevant information contained in the radio-frequency (RF) signal after delay-andsum beamforming. This is followed by a psychophysical evaluation of observer performance on B-mode envelope-detected images in three simple tasks. This experimental design allows us to track the flow of diagnostic information through RF acquisition and subsequent reading of the envelope image. In a low-contrast detection task and a high-contrast boundary discrimination task, optimal efficiency for human observers is observed at the highest center frequencies tested (15 MHz) and at moderate bandwidth (40%). For detection of scattering material in a high-contrast hypoechoic lesion, optimal efficiency was observed at lower center frequencies (5 MHz) and higher bandwidth (80%). The ideal observer analysis shows that this task dependence does not arise in the acquisition stage, where efficiency is maximized at 15 MHz with bandwidths of 60% or greater, but rather in the subsequent processing and reading of the envelope image. In addition, at higher frequencies more information is lost in the processing and reading than in the acquisition of reflecte- signals. View full abstract»

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  • A CMUT probe for medical ultrasonography: from microfabrication to system integration

    Publication Year: 2012 , Page(s): 1127 - 1138
    Cited by:  Papers (5)
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    Medical ultrasonography is a powerful and costeffective diagnostic technique. To date, high-end medical imaging systems are able to efficiently implement real-time image formation techniques that can dramatically improve the diagnostic capabilities of ultrasound. Highly performing and thermally efficient ultrasound probes are then required to successfully enable the most advanced techniques. In this context, ultrasound transducer technology is the current limiting factor. Capacitive micromachined ultrasonic transducers (CMUTs) are micro-electro-mechanical systems (MEMS)-based devices that have been widely recognized as a valuable alternative to piezoelectric transducer technology in a variety of medical imaging applications. Wideband operation, good thermal efficiency, and low fabrication cost, especially for those applications requiring high-volume production of small-area dice, are strength factors that may justify the adoption of this MEMS technology in the medical ultrasound imaging field. This paper presents the design, development, fabrication, and characterization of a 12-MHz ultrasound probe for medical imaging, based on a CMUT array. The CMUT array is microfabricated and packed using a novel fabrication concept specifically conceived for imaging transducer arrays. The performance of the developed probe is optimized by including analog front-end reception electronics. Characterization and imaging results are used to assess the performance of CMUTs with respect to conventional piezoelectric transducers. View full abstract»

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  • An approach to multibeam covariance matrices for adaptive beamforming in ultrasonography

    Publication Year: 2012 , Page(s): 1139 - 1148
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    Medical ultrasound imaging systems are often based on transmitting, and recording the backscatter from, a series of focused broadband beams with overlapping coverage areas. When applying adaptive beamforming, a separate array covariance matrix for each image sample is usually formed. The data used to estimate any one of these covariance matrices is often limited to the recorded backscatter from a single transmitted beam, or that of some adjacent beams through additional focusing at reception. We propose to form, for each radial distance, a single covariance matrix covering all of the beams. The covariance matrix is estimated by combining the array samples after a sequenced time delay and phase shift. The time delay is identical to that performed in conventional delay-and-sum beamforming. The performance of the proposed approach in conjunction with the Capon beamformer is studied on both simulated data of scenes consisting of point targets and recorded ultrasound phantom data from a specially adapted commercial scanner. The results show that the proposed approach is more capable of resolving point targets and gives better defined cyst-like structures in speckle images compared with the conventional delay-and-sum approach. Furthermore, it shows both an increased robustness to noise and an increased ability to resolve point-like targets compared with the more traditional per-beam Capon beamformer. View full abstract»

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  • Direct phase projection and transcranial focusing of ultrasound for brain therapy

    Publication Year: 2012 , Page(s): 1149 - 1159
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    Ultrasound can be used to noninvasively treat the human brain with hyperthermia by focusing through the skull. To obtain an accurate focus, especially at high frequencies (>;500 kHz), the phase of the transmitted wave must be modified to correct the aberrations introduced by the patient's individual skull morphology. Currently, three-dimensional finite-difference time-domain simulations are used to model a point source at the target. The outward-propagating wave crosses the measured representation of the human skull and is recorded at the therapy array transducer locations. The signal is then time reversed and experimentally transmitted back to its origin. These simulations are resource intensive and add a significant delay to treatment planning. Ray propagation is computationally efficient because it neglects diffraction and only describes two propagation parameters: the wave's direction and the phase. We propose a minimal method that is based only on the phase. The phase information is projected from the external skull surface to the array locations. This replaces computationally expensive finite-difference computations with an almost instantaneous direct phase projection calculation. For the five human skull samples considered, the phase distribution outside of the skull is shown to vary by less than λ/20 as it propagates over a 5 cm distance and the validity of phase projection is established over these propagation distances. The phase aberration introduced by the skull is characterized and is shown to have a good correspondence with skull morphology. The shape of this aberration is shown to have little variation with propagation distance. The focusing quality with the pro- posed phase-projection algorithm is shown to be indistinguishable from the gold-standard full finite-difference simulation. In conclusion, a spherical wave that is aberrated by the skull has a phase propagation that can be accurately described as radial, even after it has been - istorted. By combining finite- difference simulations with a phase-projection algorithm, the time required for treatment planning is significantly reduced. The correlation length of the phase is used to validate the algorithm and it can also be used to provide guiding param- eters for clinical array transducer design in terms of transducer spacing and phase error. View full abstract»

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  • Two-wave propagation imaging to evaluate the structure of cancellous bone

    Publication Year: 2012 , Page(s): 1160 - 1166
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    The two-wave phenomenon reflects not only bone mass but also the complex bone structure of cancellous bone. We propose a new simple imaging technique based on the two-wave phenomenon for investigating the anisotropic structure of cancellous bone. A cylindrical specimen of cancellous bone was obtained from a bovine femur. The structure (alignment of trabeculae) of the specimen was obtained from 3-D X-ray micro computed tomography imaging. Using a conventional ultrasonic pulse technique, we rotated the receiver around the specimen to investigate the ultrasonic fields after propagation within the specimen. The ultrasonic propagation image clearly showed the effect of the bone structure. We found that the fast wave showed apparent refraction, whereas the slow wave did not. Fast-wave propagation imaging is thus a simple and convenient technique for easy interpretation of the anisotropic structure. This imaging technique has the potential to become a powerful tool to investigate the structure of trabeculae during in vivo measurements. View full abstract»

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  • Imaging feedback of histotripsy treatments using ultrasound shear wave elastography

    Publication Year: 2012 , Page(s): 1167 - 1181
    Cited by:  Papers (5)
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    Histotripsy is a cavitation-based ultrasound therapy that mechanically fractionates soft solid tissues into fluid-like homogenates. This paper investigates the feasibility of imaging the tissue elasticity change during the histotripsy process as a tool to provide feedback for the treatments. The treatments were performed on agar tissue phantoms and ex vivo kidneys using 3-cycle ultrasound pulses delivered by a 750-kHz therapeutic array at peak negative/positive pressure of 17/108 MPa and a repetition rate of 50 Hz. Lesions with different degrees of damage were created with increasing numbers of therapy pulses from 0 to 2000 pulses per treatment location. The elasticity of the lesions was measured with ultrasound shear wave elastography, in which a quasi-planar shear wave was induced by acoustic radiation force generated by the therapeutic array, and tracked with ultrasound imaging at 3000 frames per second. Based on the shear wave velocity calculated from the sequentially captured frames, the Young's modulus was reconstructed. Results showed that the lesions were more easily identified on the shear wave velocity images than on B-mode images. As the number of therapy pulses increased from 0 to 2000 pulses/location, the Young's modulus decreased exponentially from 22.1 ± 2.7 to 2.1 ± 1.1 kPa in the tissue phantoms (R2 = 0.99, N = 9 each), and from 33.0 ± 7.1 to 4.0 ± 2.5 kPa in the ex vivo kidneys (R2 = 0.99, N = 8 each). Correspondingly, the tissues transformed from completely intact to completely fractionated as examined via histology. A good correlation existed between the lesions' Young's modulus and the degree of tissue fractionation as examined with the percentage of remaining structurally intact cell nuclei (R2 = 0.91, N = 8 each). These results indicate that lesions produced by histotripsy can be detected with high sensitivity using shear wave elastography. Because the decrease in the tissue- elasticity corresponded well with the morphological and histological change, this study provides a basis for predicting the local treatment outcomes from tissue elasticity change. View full abstract»

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  • Spectral doppler estimation utilizing 2-D spatial information and adaptive signal processing

    Publication Year: 2012 , Page(s): 1182 - 1192
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    The trade-off between temporal and spectral resolution in conventional pulsed wave (PW) Doppler may limit duplex/triplex quality and the depiction of rapid flow events. It is therefore desirable to reduce the required observation window (OW) of the Doppler signal while preserving the frequency resolution. This work investigates how the required observation time can be reduced by adaptive spectral estimation utilizing 2-D spatial information obtained by parallel receive beamforming. Four adaptive estimation techniques were investigated, the power spectral Capon (PSC) method, the amplitude and phase estimation (APES) technique, multiple signal classification (MUSIC), and a projection-based version of the Capon technique. By averaging radially and laterally, the required covariance matrix could successfully be estimated without temporal averaging. Useful PW spectra of high resolution and contrast could be generated from ensembles corresponding to those used in color flow imaging (CFI; OW = 10). For a given OW, the frequency resolution could be increased compared with the Welch approach, in cases in which the transit time was higher or comparable to the observation time. In such cases, using short or long pulses with unfocused or focused transmit, an increase in temporal resolution of up to 4 to 6 times could be obtained in in vivo examples. It was further shown that by using adaptive signal processing, velocity spectra may be generated without high-pass filtering the Doppler signal. With the proposed approach, spectra retrospectively calculated from CFI may become useful for unfocused as well as focused imaging. This application may provide new clinical information by inspection of velocity spectra simultaneously from several spatial locations. View full abstract»

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  • Time-domain calculation of spectral centroid from backscattered ultrasound signals

    Publication Year: 2012 , Page(s): 1193 - 1200
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (331 KB) |  | HTML iconHTML  

    Spectral centroid estimation from backscattered ultrasound RF signals is the preliminary step for quantitative ultrasound analysis in many medical applications. The traditional approach of estimating the spectral centroid in the frequency domain takes a long time because discrete Fourier transform (DFT) processing for each RF segment is required. To avoid this, we propose time-domain methods to estimate the spectral centroid in this paper. First, we derive the continuous-time-domain equations for the spectral centroid estimation using Parseval's theorem and Hilbert transform theory. Then, we extend the method to the discrete-time domain to ease the implementation while maintaining the same accuracy as the calculation in the frequency domain. From the result, we observe that it is not practical to apply the discrete-time equations directly, because a high sampling rate is needed to approximate the time derivative in the discrete-time domain. Therefore, we also derive the feasible version of the discrete- time equations using a circular autocorrelation function, which has no constraints on the sampling rate for real RF signals acquired from pulse-echo ultrasound systems. Simulation results using numerical phantoms show that the time-domain calculation is approximately 4.4 times faster on average than the frequency-domain method when the software's built-in functions were used. The average estimation error compared with that of the frequency-domain method using DFT is less than 0.2% for the entire propagation depths. The proposed time-domain approach to estimate the spectral centroid can be easily implemented in real-time ultrasound systems. View full abstract»

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  • Volumetric real-time imaging using a CMUT ring array

    Publication Year: 2012 , Page(s): 1201 - 1211
    Cited by:  Papers (4)
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    A ring array provides a very suitable geometry for forward-looking volumetric intracardiac and intravascular ultrasound imaging. We fabricated an annular 64-element capacitive micromachined ultrasonic transducer (CMUT) array featuring a 10-MHz operating frequency and a 1.27-mm outer radius. A custom software suite was developed to run on a PCbased imaging system for real-time imaging using this device. This paper presents simulated and experimental imaging results for the described CMUT ring array. Three different imaging methods-flash, classic phased array (CPA), and synthetic phased array (SPA)-were used in the study. For SPA imaging, two techniques to improve the image quality-Hadamard coding and aperture weighting-were also applied. The results show that SPA with Hadamard coding and aperture weighting is a good option for ring-array imaging. Compared with CPA, it achieves better image resolution and comparable signal-tonoise ratio at a much faster image acquisition rate. Using this method, a fast frame rate of up to 463 volumes per second is achievable if limited only by the ultrasound time of flight; with the described system we reconstructed three cross-sectional images in real-time at 10 frames per second, which was limited by the computation time in synthetic beamforming. View full abstract»

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  • High-resolution imaging of gigahertz polarization response arising from the interference of reflected surface acoustic waves

    Publication Year: 2012 , Page(s): 1212 - 1218
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    The surface polarization caused by traveling SAWs at 1.585 GHz has been imaged using a dynamic homodyne electrostatic force microscope technique. Instead of measuring topographic changes caused by the SAW, the reported technique measures polarization in the piezoelectric substrate arising from mechanical stress caused by the SAW. The polarization associated with this stress field modulates the scanning probe cantilever deflection amplitude, which is extracted using a lock-in-based technique. High-resolution imaging is presented with images of the interference arising from a metal reflector on a SAW device. A mathematical model combining SAW generation and force interactions between the probe and the substrate was used to verify the experimental data. In addition to overcoming the challenge associated with detecting and imaging polarization effects at gigahertz frequencies, this imaging technique will greatly assist the development of SAW-based devices that exploit the reflection and interference of SAWs in areas as diverse as microfluidic mixing, cell sorting, and quantum entanglement. View full abstract»

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  • High-frequency resonant characteristics of triple-layered piezoceramic bimorphs determined using experimental measurements and theoretical analysis

    Publication Year: 2012 , Page(s): 1219 - 1232
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    This is an experimental, theoretical, and numerical investigation of vibration characteristics in high-frequency resonance, which are studied for parallel- and series-type piezoelectric bimorphs. In the experimental measurements, the full-field optical technique known as electronic speckle pattern interferometry (ESPI) is used to measure the transverse (out-of-plane) and planar (in-plane) resonant frequencies and corresponding mode shapes for piezoelectric bimorphs. In addition, in-plane resonant frequencies are obtained from impedance analysis and the response curves of the frequency spectra show different vibration characteristics of the piezoelectric bimorphs with different electrical connections. Piezoelectric bimorphs with normal connections have three-dimensional coupled vibration characteristics and the out-of-plane vibration dominates the motion. However, only in-plane vibration motions can be excited in the high-frequency range for abnormal connections, and the resonant characteristics are similar to the single-layered piezoelectric plate. The triple-layered piezoelectric bimorphs with abnormal connection are also analyzed using theoretical analysis. The resonant frequencies, mode shapes, and normalized displacements are calculated based on the analytical solution. The experimental results and the theoretical analysis are in good agreement with the numerical calculations using the finite element method. From the discussion of the results for the parallel- and series-type piezoelectric bimorphs with normal and abnormal connections, the vibration characteristics at high frequencies are completely analyzed in this study. View full abstract»

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  • Detection of laser-induced nanosecond ultrasonic pulses in metals using a pancake coil and a piezoelectric sensor

    Publication Year: 2012 , Page(s): 1233 - 1238
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    A piezoelectric sensor and a pancake coil sensor were used for broadband detection of laser-induced ultrasound in single-crystal aluminum and polycrystalline nickel. Pressure pulses with pronounced compression phases were induced by laser pulses of 5 ns duration from one side of the specimens and detected from the opposite side. A coupling layer of water was required for the piezoelectric method, whereas the pancake coil placed in the biasing permanent field of a cylindrical magnet ~0.25 T allowed noncontact detection. The signals detected by a piezoelectric transducer showed bipolar form and their spectra covered the range from 5 to 90 MHz. The signal measured in aluminum by a pancake coil was assigned to the eddy current sources and had single polarity. The peak-to-peak value of the signal in nickel was higher and had bipolar form because of the inverse magnetostrictive effect. The high-frequency limit detected by the pancake coil approached 200 MHz. View full abstract»

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  • A generic hybrid model for bulk elastodynamics, with application to ultrasonic nondestructive evaluation

    Publication Year: 2012 , Page(s): 1239 - 1252
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    Practical ultrasonic inspection requires modeling tools that enable rapid and accurate visualization; because of the increasing sophistication of practical inspection, it is becoming increasingly difficult to use a single modeling method to represent an entire inspection process. Hybrid models that utilize different or interacting numerical schemes in different regions, to use their relative advantages to maximal effect, are attractive in this context, but are usually custom-made for specific applications or sets of modeling methods. The limitation of hybrid schemes to particular modeling techniques is shown here to be related to their fundamental formulation. As a result, it becomes clear that a formalism to generalize hybrid schemes can be developed: an example of the construction of a generic hybrid modeling interface is given for the abstraction of bulk ultrasonic wave phenomena, common in practical inspection problems. This interface is then adapted to work within a prototype hybrid model consisting of two smaller finite element model-domains, and explicitly demonstrated for bulk ultrasonic wave propagation and scattering examples. Sources of error and ways to improve the accuracy of the interface are also discussed. View full abstract»

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  • Effect of gradient dielectric coefficient in a functionally graded material (FGM) substrate on the propagation behavior of love waves in an FGM-piezoelectric layered structure

    Publication Year: 2012 , Page(s): 1253 - 1257
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (487 KB) |  | HTML iconHTML  

    The propagation behavior of Love waves in a layered structure that includes a functionally graded material (FGM) substrate carrying a piezoelectric thin film is investigated. Analytical solutions are obtained for both constant and gradient dielectric coefficients in the FGM substrate. Numerical results show that the gradient dielectric coefficient decreases phase velocity in any mode, and the electromechanical coupling factor significantly increases in the first- and second- order modes. In some modes, the difference in Love waves' phase velocity between these two types of structure might be more than 1%, resulting in significant differences in frequency of the surface acoustic wave devices. View full abstract»

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  • Array-controlled ultrasonic manipulation of particles in planar acoustic resonator

    Publication Year: 2012 , Page(s): 1258 - 1266
    Cited by:  Papers (3)
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    Ultrasonic particle manipulation tools have many promising applications in life sciences, expanding on the capabilities of current manipulation technologies. In this paper, the ultrasonic manipulation of particles and cells along a microfluidic channel with a piezoelectric array is demonstrated. An array integrated into a planar multilayer resonator structure drives particles toward the pressure nodal plane along the centerline of the channel, then toward the acoustic velocity maximum centered above the subset of elements that are active. Switching the active elements along the array moves trapped particles along the microfluidic channel. A 12-element 1-D array coupled to a rectangular capillary has been modeled and fabricated for experimental testing. The device has a 300-μm-thick channel for a half-wavelength resonance near 2.5 MHz, with 500 μm element pitch. Simulation and experiment confirm the expected trapping of particles at the center of the channel and above the set of active elements. Experiments demonstrated the feasibility of controlling the position of particles along the length of the channel by switching the active array elements. 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