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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 4 • Date April 2010

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Displaying Results 1 - 25 of 30
  • "IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control - Front cover"

    Page(s): c1 - c2
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  • IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society - Staff

    Page(s): i
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  • IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society - committee

    Page(s): ii
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  • Table of contents

    Page(s): iii - v
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  • Information for contributors with multimedia addition

    Page(s): 769 - 772
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  • A multimedia example

    Page(s): 773
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  • Modeling and experimentation on an electrostrictive polymer composite for energy harvesting

    Page(s): 774 - 784
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (830 KB) |  | HTML iconHTML  

    The harvesting of energy from ambient environments is an emerging technology with potential for numerous applications, including portable electronic devices for renewable energy. Most of the current research activities refer to classical piezoelectric ceramic materials, but more recently the development of electrostrictive polymers has generated novel opportunities for high-strain actuators. At present, the investigation of using electrostrictive polymers for energy harvesting (a conversion of mechanical to electrical energy) is beginning to show potential for this application. This paper discusses the development of a model that is able to predict the energy harvesting capabilities of an electrostrictive polymer composite (EPC). An equivalent electrical scheme has been developed by using the model of current that was recently developed by our group. After the validation of the model on a macroscopic level, an empirical relationship was established to predict the value of power from the electrostriction coefficient, the dielectric permittivity, and the compliance of the material. Finally, results indicated that the dielectric permittivity was the crucial parameter for energy harvesting. View full abstract»

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  • Wireless ferroelectric resonating sensor

    Page(s): 785 - 791
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB) |  | HTML iconHTML  

    This paper presents a passive wireless resonating sensor that is based on a ferroelectric varactor. The sensor replies with its data at an intermodulation frequency when a reader device illuminates it at 2 closely located frequencies. The paper derives a theoretical equation for the response of such a sensor, verifies the theory by simulations, and demonstrates a temperature sensor based on a ferroelectric varactor. View full abstract»

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  • Ferroelectric and ferroelastic domain wall motion in unconstrained Pb(Zr,Ti)O3 microtubes and thin films

    Page(s): 792 - 800
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    Ferroelectric polarization switching of high aspect ratio (>80:1) PbZr0.52Ti0.48O3 (PZT) microtubes with a wall thickness of ~200 nm was investigated. A charge-based technique was used to assess the dielectric and ferroelectric properties of individual mechanically-unconstrained PZT microtubes with interdigitated electrodes. An enhancement in the degree of ferroelastic (non-180??) domain wall motion was observed in the tubes relative to films of similar thickness on rigid substrates. The dielectric response of the tubes showed a Rayleigh-like ac field dependence over a wide temperature range; the extent of the extrinsic contribution to the dielectric response dropped as the temperature approached 10K, but remained finite. This work demonstrates a general methodology for directly electrically addressing small, unconstrained ferroelectric devices, extending the range of driving fields and temperatures over which these materials can be probed. View full abstract»

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  • Coupling-of-modes analysis of thin film plate acoustic wave resonators utilizing the S0 Lamb mode

    Page(s): 801 - 807
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    In this work the applicability of the coupling-of-modes (COM) approach to the analysis of thin AlN film plate acoustic resonators (FPAR), utilizing the S0 Lamb wave, is discussed. Analysis based on the Floquet-Bloch theorem as well as COM parameter extraction from a micromachined FPAR test structure are simultaneously used to verify the applicability of the COM approach. Finite element model simulation is used to further study the contribution of the higher order mass loading effects over the Lamb wave propagation under a periodical grating. A possibility to achieve zero sensitivity of the FPAR resonance with respect to the grating strip thickness is identified and physically interpreted for the first time. View full abstract»

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  • Elastic and piezoelectric properties of AlN and LiAlO2 single crystals

    Page(s): 808 - 811
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    We have successfully grown high-quality AlN piezoelectric single crystal using the sublimation technique. Transparent crack-free boules of approximately 15 mm in diameter and 25 mm in length along the [0001] direction were obtained, with coloring from amber to dark brown depending on growth temperature. Full sets of material parameters of grown AlN and commercially available LiAlO2 bulk crystals were measured at room temperature. Temperature coefficients of the material parameters of LiAlO2 were also obtained in a temperature range from -70 to +50??C. View full abstract»

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  • Time-reversal acoustic focusing system as a virtual random phased array

    Page(s): 812 - 817
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (655 KB) |  | HTML iconHTML  

    This paper compares the performance of two different systems for dynamic focusing of ultrasonic waves: conventional 2-D phased arrays (PA) and a focusing system based on the principles of time-reversed acoustics (TRA). Focused ultrasound fields obtained in the experiments with the TRA focusing system (TRA FS), which employs a liquid-filled reverberator with 4 piezotransducers attached to its wall, are compared with the focused fields obtained by mathematical simulation of PAs comprised from several tens to several hundreds of elements distributed randomly on the array surface. The experimental and simulated focusing systems had the same aperture and operated at a frequency centered about 600 kHz. Experimental results demonstrated that the TRA FS with a small number of channels can produce complex focused patterns and can steer them with efficiency comparable to that of a PA with hundreds of elements. It is shown that the TRA FS can be realized using an extremely simple means, such as a reverberator made of a water-filled plastic bottle with just a few piezotransducers attached to its walls. View full abstract»

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  • An approximate nonlinear model for time gain compensation of amplitude modulated images of ultrasound contrast agent perfusion

    Page(s): 818 - 829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1402 KB) |  | HTML iconHTML  

    Microbubble ultrasound contrast agents allow blood perfusion to be imaged at the cost of an increased attenuation that is not properly handled by existing time gain compensation methods. An automatic TGC has been developed that is able to account for different microbubble concentrations. The technique is an extension of a previously tested approach for modeling the nonlinear dependence of microbubble backscattering upon insonating pressure. The proposed method involves modeling in amplitude of the nonlinear attenuation for both forward and backward propagation, and the solution is achieved through an approximation set to overestimate the attenuation. The resulting equations are used to model and compensate amplitude modulation (AM) images; they are tested on radiofrequency data acquired using a clinical scanner from a gelatin tissue-mimicking phantom submerged in a contrast agent solution in the 0.08 MI to 0.51 MI range at 2 MHz. The nonlinear estimation equation presented here provides a significantly improved amplification profile compared with standard TGC algorithms, resulting in more accurate attenuation correction of the AM image. View full abstract»

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  • Reducing color flow artifacts caused by parallel beamforming

    Page(s): 830 - 838
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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1999 KB) |  | HTML iconHTML  

    In color flow imaging for medical diagnosis, the inherent trade-off between frame rate and image quality may often lead to suboptimal images. Parallel receive beamforming is used to help overcome this problem, but this introduces artifacts in the images. In addition to the parallel beamforming artifacts found in B-mode imaging, we have found that a difference in curvature of transmit and receive beams gives a bias in the Doppler velocity estimates. This bias causes a discontinuity in the velocity estimates in color flow images. In this work, we have shown that interpolation of the autocorrelation estimates obtained from overlapping receive beams can reduce these artifacts significantly. Because the autocorrelation function varies quite slowly, the beams can be acquired with a considerable time difference, for instance across interleaving groups or across scan planes in a 3-D scan. We have shown that a high frame rate of color flow images can be maintained with parallel beam acquisition with minimal deterioration of the image quality. View full abstract»

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  • 3-D phantom and in vivo cardiac speckle tracking using a matrix array and raw echo data

    Page(s): 839 - 854
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2358 KB) |  | HTML iconHTML  

    Cardiac motion has been tracked using various methods, which vary in their invasiveness and dimensionality. One such noninvasive modality for cardiac motion tracking is ultrasound. Three-dimensional ultrasound motion tracking has been demonstrated using detected data at low volume rates. However, the effects of volume rate, kernel size, and data type (raw and detected) have not been sufficiently explored. First comparisons are made within the stated variables for 3-D speckle tracking. Volumetric data were obtained in a raw, baseband format using a matrix array attached to a high parallel receive beam count scanner. The scanner was used to acquire phantom and human in vivo cardiac volumetric data at 1000-Hz volume rates. Motion was tracked using phase-sensitive normalized cross-correlation. Subsample estimation in the lateral and elevational dimensions used the grid-slopes algorithm. The effects of frame rate, kernel size, and data type on 3-D tracking are shown. In general, the results show improvement of motion estimates at volume rates up to 200 Hz, above which they become stable. However, peak and pixel hopping continue to decrease at volume rates higher than 200 Hz. The tracking method and data show, qualitatively, good temporal and spatial stability (for independent kernels) at high volume rates. View full abstract»

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  • Methodical study on the estimation of strain in shearing and rotating structures using radio frequency ultrasound based on 1-D and 2-D strain estimation techniques

    Page(s): 855 - 865
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    This simulation study is concerned with: 1) the feasibility of measuring rotation and 2) the assessment of the performance of strain estimation in shearing and rotating structures. The performance of 3 different radio frequency (RF) based methods is investigated. Linear array ultrasound data of a deforming block were simulated (axial shear strain = 2.0, 4.0, and 6.0%, vertical strain = 0.0, 1.0, and 2.0%). Furthermore, data of a rotating block were simulated over an angular range of 0.5?? to 10??. Local displacements were estimated using a coarse-to-fine algorithm using 1-D and 2-D precompression kernels. A new estimation method was developed in which axial displacements were used to correct the search area for local axial motion. The study revealed that this so-called free-shape 2-D method outperformed the other 2 methods and produced more accurate displacement images. For higher axial shear strains, the variance of the axial strain and the axial shear strain reduced by a factor of 4 to 5. Rotations could be accurately measured up to 4.0 to 5.0??. Again, the free-shape 2-D method yielded the most accurate results. After reconstruction of the rotation angle, the mean angles were slightly underestimated. The precision of the strain estimates decreased with increasing rotation angles. In conclusion, the proposed free-shape 2-D method enhances the measurement of (axial shear) strains and rotation. Experimental validation of the new method still has to be performed. View full abstract»

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  • A hybrid displacement estimation method for ultrasonic elasticity imaging

    Page(s): 866 - 882
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2213 KB) |  | HTML iconHTML  

    Axial displacement estimation is fundamental to many freehand quasistatic ultrasonic strain imaging systems. In this paper, we present a novel estimation method that combines the strengths of quality-guided tracking, multi-level correlation, and phase-zero search to achieve high levels of accuracy and robustness. The paper includes a full description of the hybrid method, in vivo examples to illustrate the method??s clinical relevance, and finite element simulations to assess its accuracy. Quantitative and qualitative comparisons are made with leading single- and multi-level alternatives. In the in vivo examples, the hybrid method produces fewer obvious peak-hopping errors, and in simulation, the hybrid method is found to reduce displacement estimation errors by 5 to 50%. With typical clinical data, the hybrid method can generate more than 25 strain images per second on commercial hardware; this is comparable with the alternative approaches considered in this paper. View full abstract»

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  • Three-dimensional computer-controlled acoustic pressure scanning and quantification of focused ultrasound

    Page(s): 883 - 891
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1231 KB) |  | HTML iconHTML  

    We propose an automated needle hydrophonebased scanning system to measure high-resolution 3-D acoustic pressure distributions generated by high-intensity focused ultrasound (HIFU). The hardware consists of a host computer, subsystems for HIFU generation, and an oscilloscope to sample the pressure response from a sensor in a water tank. Software was developed to control the hardware subsystems, to search for the initial scan position, and to design the scanning path and volume. A preoperative scanning plan with three perpendicular planes is used to manipulate the position of the HIFU transducer and to automate the acquisition of the spatial acoustic pressure distribution. The post-processing process displays the scanning results, compensates time delays caused by continuous linear scans, and quantifies the focal region. A method to minimize the displacement error induced by the time delay improves the scanning speed of a conventional needle hydrophone-based scanning system. Moreover, a noiserobust, automatic-focus searching algorithm using Gaussian function fitting reduces the total number of iterations and prevents the initial scanning position search from diverging. Finally, the minimum-volume enclosing ellipsoid approximation is used to quantify the size and orientation of the 3-D focal region thresholded by the minimum pressure of interest for various input conditions and to test the reproducibility of the scanning system. View full abstract»

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  • 2-D finite difference time domain model of ultrasound reflection from normal and osteoarthritic human articular cartilage surface

    Page(s): 892 - 899
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (711 KB) |  | HTML iconHTML  

    Quantitative high-frequency ultrasonic evaluation of articular cartilage has shown a potential for the diagnosis of osteoarthritis, where the roughness of the surface, collagen and proteoglycan contents, and the density and mechanical properties of cartilage change concurrently. Experimentally, these factors are difficult to investigate individually and thus a numerical model is needed. The present study is the first one to use finite difference time domain modeling of pulse-echo measurements of articular cartilage. Ultrasound reflection from the surface was investigated with varying surface roughness, material parameters (Young's modulus, density, longitudinal, and transversal velocities) and inclination of the samples. The 2-D simulation results were compared with the results from experimental measurements of the same samples in an identical geometry. Both the roughness and the material parameters contributed significantly to the ultrasound reflection. The angular dependence of the ultrasound reflection was strong for a smooth cartilage surface but disappeared for the samples with a rougher surface. These results support the findings of previous experimental studies and indicate that ultrasound detects changes in the cartilage that are characteristic of osteoarthritis. In the present study there are differences between the results of the simulations and the experimental measurements. However, the systematic patterns in the experimental behavior are correctly reproduced by the model. In the future, our goal is to develop more realistic acoustic models incorporating inhomogeneity and anisotropy of the cartilage. View full abstract»

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  • Estimating the total ultrasound attenuation along the propagation path by applying multiple filters to backscattered echoes from a single spherically focused source

    Page(s): 900 - 907
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    Quantifying the correlation length of the tissue microstructure has shown potential for differentiating between benign and malignant tumors. To implement these advances in the clinic, the total frequency-dependent attenuation along the propagation path must be determined on a patient specific basis. Previously, an algorithm was developed to estimate this attenuation using echoes from multiple sources. In this study, the developed algorithm was extended to echoes from a single source by filtering the echoed signal into multiple frequency bands. This step was needed because it would be challenging to scan exactly the same tissue region using multiple sources in the clinic. Computer simulations and phantom experiments were conducted to verify the attenuation could be determined by filtering the echoes from a single source. The simulations utilized a spherically focused single-element source (5 cm focal length, f/4, 14 MHz center frequency, 50% bandwidth) exposing a homogeneous tissue region (Gaussian scattering structures with effective radii of 5 to 55 ??m at a density of 250/mm3, attenuation of 0.1 to 0.9 dB/cm.MHz). The phantom experiments utilized a spherically focused single-element source (5.08 cm focal length, f/4, 7.5 MHz center frequency) exposing a 0.5 dB/cm.MHz homogeneous glass bead phantom. The computer simulations and phantom experiment confirmed that the total attenuation along the propagation path can be determined by appropriately applying multiple filters to the backscattered echoes from a single source. View full abstract»

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  • Piezoelectric MEMS energy harvesting systems driven by harmonic and random vibrations

    Page(s): 908 - 919
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1672 KB) |  | HTML iconHTML  

    Switching power conditioning techniques are known to greatly enhance the performance of linear piezoelectric energy harvesters subject to harmonic vibrations. With such circuits, little is known about the effect of mechanical stoppers that limit the motion or about waveforms other than harmonic vibrations. This work presents SPICE simulations of piezoelectric micro energy harvester systems that differ in choice of power conditioning circuits and stopper models. We consider in detail both harmonic and random vibrations. The nonlinear switching conversion circuitry performs better than simple passive circuitry, especially when mechanical stoppers are in effect. Stopper loss is important under broadband vibrations. Stoppers limit the output power for sinusoidal excitations, but result in the same output power whether the stoppers are lossy or not. When the mechanical stoppers are hit by the proof mass during high-amplitude vibrations, nonlinear effects such as saturation and jumps are present. View full abstract»

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  • Laser ultrasonic technique for evaluating solder bump defects in flip chip packages using modal and signal analysis methods

    Page(s): 920 - 932
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1969 KB) |  | HTML iconHTML  

    Current techniques for nondestructive quality evaluation of solder bumps in microelectronic packages have their own limitations and are unsuitable for in-line inspection because of high cost and low throughput. In order to meet requirements of quality inspection of electronic packages, a nondestructive and noncontact solder bump inspection system is being developed using laser ultrasound and interferometer techniques. This system uses a pulsed Nd:YAG laser to induce ultrasound in electronic packages in the thermoelastic regime; it then measures the transient out-of-plane displacement responses with an ultrasonic arrival on the surface of the packages using laser interferometer technique. This paper presents a systematic study of defect detection in flip chip solder bumps using a combined modal and signal analysis method. The correlation between the finite element (FE) modal analysis and wavelet analysis of laser ultrasound signals has been studied. With the help of FE modal analysis, the modes of flip chip packages sensitive to open bumps were predicted for further signal processing before conducting any experiments. The decomposed signal components sensitive to specific defects were extracted and analyzed with discrete wavelet transform. The results show that wavelet analysis increases the measurement sensitivity of the flip chip solder bump inspection compared with existing methods. View full abstract»

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  • Transducer loading effect on the performance of PZT-based SHM systems

    Page(s): 933 - 941
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (902 KB) |  | HTML iconHTML  

    In the last years, the piezoelectric transducers of lead zirconate titanate (PZT) have been widely used in structural health monitoring (SHM) systems based on the electromechanical (E/M) impedance technique. Although many studies indicate the successful use of PZT in damage detection, some practical considerations still have to be considered in real applications. In this work, the effect of the transducer loading caused by mechanical impedance of the host structure is analyzed using an equivalent electromechanical circuit. Tests were performed on structures with various sizes and the results show that the transducer loading significantly reduces the sensitivity of the system for detecting structural damages. View full abstract»

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  • Vibration analysis of an isotropic elastic sphere contacting a semi-infinite cubic solid

    Page(s): 942 - 950
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (647 KB) |  | HTML iconHTML  

    Vibration analysis of an isotropic elastic-sphere oscillator contacting a semi-infinite cubic solid is investigated by considering dynamic deformation at the contact interface. Assuming sufficiently small oscillation amplitude of the sphere compared with the static indentation deformation, the dynamic maximum contact pressure and the variable contact radius yield a dynamic-contact pressure distribution of constant contact radius. The combination of the sphere oscillation and the solid motion at the contact interface through contact-displacement conditions gives resonance frequencies of the elastic sphere. Unlike the conventional quasi-static model, this dynamic contact model agrees well with the measurements, which will benefit the quantitative evaluation of the local Young's modulus and the orientation of micro-scaled anisotropic grains by the resonance-frequency shifts of a vibrating oscillator in resonance ultrasound microscopy and the efficient removal of micron or sub-micron particles from the substrate in the dry laser cleaning technique. View full abstract»

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  • Oscillation propagating in non-contact linear piezoelectric ultrasonic levitation transporting system---from solid state to fluid media

    Page(s): 951 - 956
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    Non-contact ultrasonic motors (USM) show potential for future use, especially in the industrial fields because of its simple structure and quick response. It is therefore important to comprehensively understand their theoretical background so as to push this research forward. In this study, we shall fully explain and deduce the driving mechanism of a linear ultrasonic levitation transporting system. Oscillation equations from the initial exciting Langevin transducer and flexural traveling wave propagation on the linear guide were first established. Then the squeezing fluid movement between the linear guide and the levitating slider was analyzed. Next, after being excited by the progressing wave under corresponding boundary conditions, the related tangential velocity of the middle flow field was obtained. Finally, the validated experiment was set up to test slider velocity. 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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Meet Our Editors

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