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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 11 • Date November 2006

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  • IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control - Nov. 2006

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

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  • IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society

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  • Table of contents - Vol 53 No 11

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  • Information for Contributors with Multimedia Addition

    Page(s): 1963 - 1967
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  • A multimedia example

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  • Electrostrictive and photoluminescent properties in Pr-doped (Ba,Sr)(Ti,Al)O/sub 3/ ceramics

    Page(s): 1969 - 1973
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    Pr3+-doped (Ba,Sr)(Ti,Al)O3 ceramics were prepared using a conventional solid-state reaction technique. Multiple functions of electrostriction and photoluminescence were realized in the ceramics. Red emission (614 nm) was observed in the samples, and the intensity reached its largest value in the sample of 40 mol% Sr addition. Although the electrostrictive strain decreased in the Pr and Al doped samples, the temperature dependence is remarkably improved comparable to the undoped sample View full abstract»

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  • Relations between single-domain and multidomain piezoelastic properties in single crystals

    Page(s): 1974 - 1981
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    This paper presents a new method to compute the piezoelastic properties of multidomain single crystals from the single-domain constants. Based on a quasi static assumption, a PMN-xPT multidomain is defined as a periodic medium with a lattice composed of layers of two domains in a twin structure. Such a structure is assumed to have charged domain walls that imply specific lattice media and boundary conditions. A numerical computation has been performed for a PMN-33PT single crystal in the rhombohedral phase. The effective elastic, piezoelectric, and dielectric constants of the macroscopic structure have been calculated, as well as the wave velocities in different configurations of domain patterns View full abstract»

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  • Experimental study of phase noise in FBAR resonators

    Page(s): 1982 - 1987
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    Phase noise of micromachined bulk acoustic wave resonators is investigated. A measurement bench, able to characterize the phase noise of a single resonator on-wafer, is set up. The experimental data demonstrate the existence of a 1/f phase noise component, the amplitude of which is strongly dependent on the resonator geometry. Particularly, the apodized resonators have shown the best phase noise performance, with no degradation of the Q factor View full abstract»

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  • Diophantine frequency synthesis

    Page(s): 1988 - 1998
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    A methodology for fine-step, fast-hopping, low-spurs phase-locked loop based frequency synthesis is presented. It uses mathematical properties of integer numbers and linear Diophantine equations to overcome the constraining relation between frequency step and phase-comparator frequency that is inherent in conventional phase-locked loop based frequency synthesis. The methodology leads to fine-step, fast-hopping, modular-structured frequency synthesizers with potentially very low spurs, especially in the vicinity of the carrier. The paper focuses on the mathematical principles of the new methodology and the related number theoretic algorithms View full abstract»

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  • 3-D ultrasound guidance of surgical robotics: a feasibility study

    Page(s): 1999 - 2008
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    Laparoscopic ultrasound has seen increased use as a surgical aide in general, gynecological, and urological procedures. The application of real-time, three-dimensional (RT3D) ultrasound to these laparoscopic procedures may increase information available to the surgeon and serve as an additional intraoperative guidance tool. The integration of RT3D with recent advances in robotic surgery also can increase automation and ease of use. In this study, a 1-cm diameter probe for RT3D has been used laparoscopically for in vivo imaging of a canine. The probe, which operates at 5 MHz, was used to image the spleen, liver, and gall bladder as well as to guide surgical instruments. Furthermore, the three-dimensional (3-D) measurement system of the volumetric scanner used with this probe was tested as a guidance mechanism for a robotic linear motion system in order to simulate the feasibility of RT3D/robotic surgery integration. Using images acquired with the 3-D laparoscopic ultrasound device, coordinates were acquired by the scanner and used to direct a robotically controlled needle toward desired in vitro targets as well as targets in a post-mortem canine. The rms error for these measurements was 1.34 mm using optical alignment and 0.76 mm using ultrasound alignment View full abstract»

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  • Nonlinear viscoelastic properties of tissue assessed by ultrasound

    Page(s): 2009 - 2018
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    A technique to assess qualitatively the presence of higher-order viscoelastic parameters is presented. Low-frequency, monochromatic elastic waves are emitted into the material via an external vibrator. The resulting steady-state motion is detected in real time via an ultra fast ultrasound system using classical, one-dimensional (1-D) ultrasound speckle correlation for motion estimation. Total data acquisition lasts only for about 250 ms. The spectrum of the temporal displacement data at each image point is used for analysis. The presence of nonlinear effects is detected by inspection of the ratio of the second harmonics amplitude with respect to the total amplitude summed up to the second harmonic. Results from a polyacrylamide-based phantom indicate a linear response (i.e., the absence of higher harmonics) for this type of material at 65 Hz mechanical vibration frequency and about 100 mum amplitude. A lesion, artificially created by injection of glutaraldehyde into a beef specimen, shows the development of higher harmonics at the location of injection as a function of time. The presence of upper harmonics is clearly evident at the location of a malignant lesion within a mastectomy View full abstract»

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  • Phase series echography with prior waveform distortion for evaluating posterior waveform distortion

    Page(s): 2019 - 2025
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    We describe a pulse-echo ultrasound method for measuring nonlinear waveform distortion. First, two artificially distorted ultrasound pulses, one of which is transformed into the other by using a linear transform, are prepared prior to the measurement. The linear relationship does not hold for nonlinear propagation. Second, different initial-phase versions of the two pulses are separately transmitted to a specimen one after another, then the echoes with the same turnaround time are placed in order of the initial phase. The placed echoes, called a phase series, have complete information on the posterior waveform distortion. We formulate a waveform distortion index by using these two techniques. The waveform distortion index has a monotonic increasing relationship with the nonlinear parameter B/A. As an example application, we performed tissue characterization of boiled eggs. As a result, egg whites and yolks were clearly distinguished. This method should be useful for biological tissue characterization View full abstract»

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  • Continuous delay estimation with polynomial splines

    Page(s): 2026 - 2035
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    Delay estimation is used in ultrasonic imaging to estimate blood flow, determine phase aberration corrections, and to calculate elastographic images. Several algorithms have been developed to determine these delays. The accuracy of these methods depends in differing ways on noise, bandwidth, and delay range. In most cases relevant to delay estimation in ultrasonics, a subsample estimate of the delay is required. We introduce two new delay algorithms that use cubic polynomial splines to continuously represent the delay. These algorithms are compared to conventional delay estimators, such as normalized cross correlation and autocorrelation, and to another spline-based method. We present simulations that compare the algorithms' performance for varying amounts of noise, delay, and bandwidth. The proposed algorithms have better performance, in terms of bias and jitter, in a realistic ultrasonic imaging environment. The computational requirements of the new algorithms also are considered View full abstract»

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  • Estimation of velocity vector angles using the directional cross-correlation method

    Page(s): 2036 - 2049
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    A method for determining both velocity magnitude and angle in any direction is suggested. The method uses focusing along the velocity direction and cross-correlation for finding the correct velocity magnitude. The angle is found from beamforming directional signals in a number of directions and then selecting the angle with the highest normalized correlation between directional signals. The approach is investigated using Field II simulations and data from the experimental ultrasound scanner RASMUS and a circulating flow rig with a parabolic flow having a peak velocity of 0.3 m/s. A 7-MHz linear array transducer is used with a normal transmission of a focused ultrasound field. In the simulations the relative standard deviation of the velocity magnitude is between 0.7% and 7.7% for flow angles between 45deg and 90deg. The study showed that angle estimation by directional beamforming can be estimated with a high precision. The angle estimation performance is highly dependent on the choice of the time kappatprfmiddotTprf (correlation time) between signals to correlate. One performance example is given with a fixed value of kappatprf for all flow angles. The angle estimation on measured data for flow at 60deg to 90deg yields a probability of valid estimates between 68% and 98%. The optimal value of kappatprf each flow angle is found from a parameter study; with these values, the performance on simulated data yields angle estimates with no outlier estimates and with standard deviations below 2deg View full abstract»

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  • Modification of the phased-tracking method for reduction of artifacts in estimated artery wall deformation

    Page(s): 2050 - 2064
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    Noninvasive measurement of mechanical properties, such as elasticity, of the arterial wall, is useful for diagnosis of atherosclerosis. For assessment of mechanical properties, it is necessary to measure the deformation of the arterial wall. In this study, a modification of the previously proposed phased-tracking method was conducted to improve measurement of the small change in thickness (deformation) of the arterial wall due to the heartbeat. In our previous method, a set of two points along an ultrasonic beam was initially assigned, and the change in thickness of the layer between these two points during an entire cardiac cycle was estimated. In motion estimation with ultrasound, the motion of an interface or a scatterer, which generates an echo, can be obtained by estimating the change in time delay of the echo. For example, in the case of a carotid artery of a healthy subject, there are only two dominant echoes from the lumen-intima and media-adventitia interfaces. Thus, only the displacements of the lumen-intima and media-adventitia interfaces can be estimated, which means that ultrasound can estimate only the change in distance (thickness) between these two interfaces. However, even in this case, our previous method gives different estimates of the change in thickness, depending on the depths (positions in the arterial radial direction) of the two initially assigned points. In this study, modifications of the previous method in terms of the strategy for assignment of layers and the required thickness of an assigned layer were made to reduce such an artificial spatial variation in the estimated changes in thickness. Using the proposed method, errors in estimated changes in thickness were reduced from 21.2 plusmn 24.1% to 0.19 plusmn 0.04% (mean plusmn standard deviation) in simulation experiments. As in the case of the simulation experiments, the spatial variation in estimated changes in thickness also was reduced in in vivo experiments in a carotid artery of - - a healthy subject and in vitro experiments using two excised, diseased arteries View full abstract»

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  • Dynamic mechanical response of elastic spherical inclusions to impulsive acoustic radiation force excitation

    Page(s): 2065 - 2079
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    Acoustic radiation force impulse imaging has been used clinically to study the dynamic response of lesions relative to their background material to focused, impulsive acoustic radiation force excitations through the generation of dynamic displacement field images. Dynamic displacement data are typically displayed as a set of parametric images, including displacement immediately after excitation, maximum displacement, time to peak displacement, and recovery time from peak displacement. To date, however, no definitive trends have been established between these parametric images and the tissues' mechanical properties. This work demonstrates that displacement magnitude, time to peak displacement, and recovery time are all inversely related to the Young's modulus in homogeneous elastic media. Experimentally, pulse repetition frequency during displacement tracking limits stiffness resolution using the time to peak displacement parameter. The excitation pulse duration also impacts the time to peak parameter, with longer pulses reducing the inertial effects present during impulsive excitations. Material density affects tissue dynamics, but is not expected to play a significant role in biological tissues. The presence of an elastic spherical inclusion in the imaged medium significantly alters the tissue dynamics in response to impulsive, focused acoustic radiation force excitations. Times to peak displacement for excitations within and outside an elastic inclusion are still indicative of local material stiffness; however, recovery times are altered due to the reflection and transmission of shear waves at the inclusion boundaries. These shear wave interactions cause stiffer inclusions to appear to be displaced longer than the more compliant background material. The magnitude of shear waves reflected at elastic lesion boundaries is dependent on the stiffness contrast between the inclusion and the background material, and the stiffness and size of the inclusion dictate when s- - hear wave reflections within the lesion will interfere with one another. Jitter and bias associated with the ultrasonic displacement tracking also impact the estimation of a tissue's dynamic response to acoustic radiation force excitation View full abstract»

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  • Frequency-temperature behavior of flexural quartz resonators by means of Timoshenko's model

    Page(s): 2080 - 2085
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    The frequency of a flexural resonator and its frequency-temperature behavior usually are computed by Bernoulli's classical approximation. This approach is valid for beams with a large length-over-thickness-ratio. For shorter beams, the effects of shear stress and rotary inertia may play a significant role for temperature-compensated resonators. These effects have been taken into account for isotropic beams. The aim of this paper is to discuss the extension of the shear coefficient in the case of an anisotropic material and to compute the frequency-temperature characteristic of an (XYt)thetas cut resonator when the shear stress and the rotary inertia have been taken into account. Comparisons between the classical approximation arid this treatment are given for quartz. Furthermore, the numerical predictions obtained by means of different sets of data available for thermal sensitivities of elastic coefficients are compared View full abstract»

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  • A perturbation method for predicting the temperature and stress sensitivities of quartz vibrating structures simulated by finite-element analysis

    Page(s): 2086 - 2094
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    Thermal and mechanical sensitivities of vibrating structures arid wave guides are key parameters for the optimization of high stability resonant devices operating in the ultrasonic frequency range (from a few tenth of kilohertz to a few gigahertz). In this paper, the possibility to simulate arid predict temperature coefficients of frequency (TCF) of quartz transducers of any shape as well as their stress sensitivity coefficients is addressed. The theoretical developments based on harmonic finite-element analysis coupled with a variational perturbation method are detailed, showing how to derive the regarded parameters. The proposed approach is validated using a two-dimensional (2-D) model of a plane face-bulk acoustic resonator for which an analytical model can give access to both TCF and stress sensitivity coefficients. It is then applied to a 2-D model of convex plane bulk acoustic resonator of singly rotated quartz and used to compute the first order TCF of a 3-D model of a tuning fork structure. In the latter case, the importance of considering the actual excitation of the device is demonstrated, allowing for the accurate definition of angular loci for which thermal compensation can be expected, in agreement with literature. Possible extensions arid improvements of the proposed method is discussed in conclusion View full abstract»

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  • Synthesis of textured thin piezoelectric AlN films with a nonzero C-axis mean tilt for the fabrication of shear mode resonators

    Page(s): 2095 - 2100
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    A method for the deposition of thin piezo-electric aluminum nitride (AlN) films with a nonzero c-axis mean tilt has been developed. The deposition is done in a standard reactive magnetron sputter deposition system without any hardware modifications. In essence, the method consists of a two-stage deposition process. The resulting film has a distinct tilted texture with the mean tilt of the c-axis varying roughly in the interval 28 to 32 degrees over the radius of the wafer excluding a small exclusion zone at the center of the latter. The mean tilt angle distribution over the wafer has a circular symmetry. A membrane-type shear mode thickness-excited thin film bulk acoustic resonator together with a micro-fluidic transport system has been subsequently fabricated using the two stage AlN de-position as well as standard bulk micro machining of Si. The resonator consisted of a 2-mum-thick AlN film with 200-nm-thick Al top and bottom electrodes. The resonator was characterized with a network analyzer when operating in both air and water. The shear mode resonance frequency was about 1.6 GHz, the extracted device Q around 350, and the electromechanical coupling kt 2 2% when the resonator was operated in air, whereas the latter two dropped down to 150 and 1.8%, respectively, when the resonator was operated in pure water View full abstract»

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  • Determination of an ultrasonic transducer's sensitivity and impedance in a pulse-echo setup

    Page(s): 2101 - 2112
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    The role that an ultrasonic piezoelectric transducer plays in an ultrasonic measurement system can be described in terms of the transducer's input electrical impedance and its sensitivity. Here, a new model-based approach is proposed to determine both the transducer impedance and sensitivity in a pulse-echo setup. This new method is much simpler to apply than previous "self-reciprocity" calibration methods for determining sensitivity and generalizes those methods. It is demonstrated that sensitivities obtained with this new method agree well with the sensitivities obtained by a three-transducer method commonly used in calibration studies. It is demonstrated that at the megahertz frequencies at which ultrasonic transducers operate it is important to compensate for cabling effects in these measurements. The influence of the pulser/receiver settings on the results obtained were also discussed View full abstract»

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  • New method of change in temperature coefficient delay of acoustic waves in thin piezoelectric plates

    Page(s): 2113 - 2120
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    As is well-known, the development of highly effective and thermostable acoustic devices assumes using the acoustic waves with high coefficient of electromechanical coupling (K2) and low temperature coefficient of delay (TCD). At present, it also is well-known that fundamental shear horizontal (SH0) acoustic waves in thin piezoelectric plates possess significantly more electromechanical coupling compared to surface acoustic waves (SAW) in the same material. However, although the value of TCD of SH0 waves is insignificantly less than for SAW, this is not enough for development of thermostable devices. This paper suggests a new way of decreasing TCD of SH0 waves in piezoelectric plates at a high level of electromechanical coupling. This way assumes to use the structure containing the piezoelectric plate and liquid with the special dependence of permittivity on temperature. Theoretical and experimental investigation showed that, for SH0 wave in YX LiNbO3 plate at hf=700 m/s (h=plate thickness, f=wave frequency) the presence of butyl acetate can decrease the value of TCD by six times at K2=30%. In a whole the obtained results open the wide prospect of using SH0 wave in thin piezoelectric plate for development of highly effective and thermo-stable acoustic devices View full abstract»

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  • A successive parameter estimation algorithm for chirplet signal decomposition

    Page(s): 2121 - 2131
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    In ultrasonic imaging systems, the patterns of detected echoes correspond to the shape, size, and orientation of the reflectors and the physical properties of the propagation path. However, these echoes often are overlapped due to closely spaced reflectors and/or microstructure scattering. The decomposition of these echoes is a major and challenging problem. Therefore, signal modeling and parameter estimation of the nonstationary ultrasonic echoes is critical for image analysis, target detection, arid object recognition. In this paper, a successive parameter estimation algorithm based on the chirplet transform is presented. The chirplet transform is used not only as a means for time-frequency representation, but also to estimate the echo parameters, including the amplitude, time-of-arrival, center frequency, bandwidth, phase, and chirp rate. Furthermore, noise performance analysis using the Cramer Rao lower bounds demonstrates that the parameter estimator based on the chirplet transform is a minimum variance and unbiased estimator for signal-to-noise ratio (SNR) as low as 2.5 dB. To demonstrate the superior time-frequency and parameter estimation performance of the chirplet decomposition, ultrasonic flaw echoes embedded in grain scattering, and multiple interfering chirplets emitted by a large, brown bat have been analyzed. It has been shown that the chirplet signal decomposition algorithm performs robustly, yields accurate echo estimation, and results in SNR enhancements. Numerical and analytical results show that the algorithm is efficient and successful in high-fidelity signal representation View full abstract»

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  • Piezoelectric love waves on rotated Y-cut mm2 substrates

    Page(s): 2132 - 2139
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    Consider a layer consisting of a m3m dielectric crystal, with faces cut parallel to a symmetry plane. Then bond it onto a semi-infinite mm2 piezoelectric substrate. For an X- or Y-cut of the substrate, a Love wave can propagate in the resulting structure and the corresponding dispersion equation is derived analytically. It turns out that when the upper (free) face of the layer is metalized, a fully explicit treatment can also be conducted in the case of a Y-cut rotated about Z. In the case of a germanium layer over a potassium niobate substrate, the wave exists at any wavelength for X- and Y-cuts but this ceases to be the case for rotated cuts, with the appearance of forbidden ranges. By playing on the cut angle, the Love wave can be made to travel faster than, or slower than, or at the same speed as, the shear bulk wave of the layer. A by-product of the analysis is the derivation of the explicit secular equation for the Bleustein-Gulyaev wave in the substrate alone, which corresponds to an asymptotic behavior of the Love wave. The results are valid for other choices for the layer and for the substrate, provided they have the same, or more, symmetries View full abstract»

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  • Numerical field intensity factor calculations for 1-3 piezocomposite structures

    Page(s): 2140 - 2151
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    The 1-3 piezocomposite transducers used in specific medical applications-as lithotripsy-must be excited by intense electrical impulses. By inference, the composite material is subjected to high-stress levels. To explain possible failure, a numerical tool for analyzing singular two- and three-dimensional stress fields in piezocomposite structures is proposed. Following a finite-element iterative method, singularity parameters values and intensity factors for the mechanical stresses and the electrical field are computed in several bimaterial configurations. The finite-element analysis uses commercial software 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