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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 4 • Date April 2009

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Displaying Results 1 - 25 of 29
  • "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

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

    Page(s): ii
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  • Table of contents

    Page(s): iii - iv
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  • Information for contributors

    Page(s): 681 - 684
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  • A multimedia example

    Page(s): 686
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  • Influence of Pb and La contents on the lattice configuration of La-substituted Pb(Zr,Ti)O3 films fabricated by CSD method

    Page(s): 687 - 692
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    The influence of Pb and La contents on the lattice configuration in La-substituted Pb(Zr0.65,Ti0.35)O3 (La-PZT) films was systematically investigated. La-PZT films with various La and Pb contents were fabricated on Pt/Ti/SiO2/Si substrates by chemical solution deposition (CSD). In the La-PZT films with a Pb content ratio of 125% relative to a stoichiometric value, La ions were substituted for not only A-site ions but also B-site ions at La contents greater than 3 mol%. La substitution for B-site seems to cause larger reduction of the unit cell size. In addition, we found that in the La-PZT films with a La content of 3 mol%, the Pb content of 116 mol% (120% relative to a stoichiometric value) was optimum from the viewpoint of site occupancy. This indicates that excess Pb prevented the A-site substitution of La ions. View full abstract»

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  • Nonlinear pyroelectric energy harvesting from relaxor single crystals

    Page(s): 693 - 699
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    Energy harvesting from temperature variations in a Pb(Zn1/3Nb2/3)0.955Ti0.045O3 single crystal was studied and evaluated using the Ericsson thermodynamic cycle. The efficiency of this cycle related to Carnot cycle is 100 times higher than direct pyroelectric energy harvesting, and it can be as high as 5.5% for a 10degC temperature variation and 2 kV/mm electric field. The amount of harvested energy for a 60degC temperature variation and 2 kV/mm electric field is 242.7 mJmiddotcm-3. The influence of ferroelectric phase transitions on the energy harvesting performance is discussed and illustrated with experimental results. View full abstract»

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  • Adaptive spectral doppler estimation

    Page(s): 700 - 714
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    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch's method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pulsating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior performance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed. View full abstract»

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  • Fractional derivative models for ultrasonic characterization of polymer and breast tissue viscoelasticity

    Page(s): 715 - 726
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    The viscoelastic response of hydropolymers, which include glandular breast tissues, may be accurately characterized for some applications with as few as 3 rheological parameters by applying the Kelvin-Voigt fractional derivative (KVFD) modeling approach. We describe a technique for ultrasonic imaging of KVFD parameters in media undergoing unconfined, quasi-static, uniaxial compression. We analyze the KVFD parameter values in simulated and experimental echo data acquired from phantoms and show that the KVFD parameters may concisely characterize the viscoelastic properties of hydropolymers. We then interpret the KVFD parameter values for normal and cancerous breast tissues and hypothesize that this modeling approach may ultimately be applied to tumor differentiation. View full abstract»

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  • Basic considerations in the use of coded excitation for color flow imaging applications

    Page(s): 727 - 737
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    Coded excitation is now a well-established technique in medical ultrasound for B-mode imaging applications. It enables a gain in depth of penetration, without sacrificing the spatial resolution and maintaining an acceptable peak intensity for patient safety. The rationale of this technique for velocity estimation applications still has to be formulated in more precise terms. In particular, differences in the situation that arise in color flow imaging (CFI) applications from typical B-mode imaging conditions, such as signal-to-noise ratio conditions, pulsing strategy, and safety requirements, need to be specifically addressed to assess more quantitatively the potential of this technique. This paper discusses the potential improvement in sensitivity, resolution, and statistical performance provided by coded excitation for CFI applications from theoretical considerations and simulations. View full abstract»

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  • Numerical analysis of variability in ultrasound propagation properties induced by trabecular microstructure in cancellous bone

    Page(s): 738 - 747
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    The manner by which the trabecular microstructure affects the propagation of ultrasound waves through cancellous bone is numerically investigated by finite difference time-domain (FDTD) simulation. Sixteen 3-D numerical models of 6.45times6.45times6.45 mm with a voxel size of 64.5 mum are reconstructed using a 3-D microcomputed tomographic (muCT) image taken from a bovine cancellous bone specimen of approximately 20times20times9 mm. All cancellous bone models have an oriented trabecular structure, and their trabecular elements are gradually eroded to increase the porosity using an image processing technique. Three erosion procedures are presented to realize various changes in the trabecular microstructure with increasing porosity. FDTD simulations of the ultrasound pulse waves propagating through the cancellous bone models at each eroded step are performed in 2 cases of the propagations parallel and perpendicular to the major trabecular orientation. The propagation properties of the wave amplitudes and propagation speeds are derived as a function of the porosity, and their variability due to the trabecular microstructure is revealed. To elucidate an effect of the microstructure, the mean intercept length (MIL), which is a microstructural parameter, is introduced, and the correlations of the propagation properties with the MILs of the trabecular elements and pore spaces are investigated. View full abstract»

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  • Error in estimates of tissue material properties from shear wave dispersion ultrasound vibrometry

    Page(s): 748 - 758
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1385 KB) |  | HTML iconHTML  

    Shear wave velocity measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave velocity to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating shear waves are measured a few millimeters away from the excitation point. The shear wave velocity is measured using a repetitive pulse-echo method and Kalman filtering to find the phase of the harmonic shear wave at 2 different locations. A viscoelastic Voigt model and the shear wave velocity measurements at different frequencies are used to find the shear elasticity (mu1) and viscosity (mu2) of the tissue. The purpose of this paper is to report the accuracy of the SDUV method over a range of different values of mu1 and mu2. A motion detection model of a vibrating scattering medium was used to analyze measurement errors of vibration phase in a scattering medium. To assess the accuracy of the SDUV method, we modeled the effects of phase errors on estimates of shear wave velocity and material properties while varying parameters such as shear stiffness and viscosity, shear wave amplitude, the distance between shear wave measurements (Deltatau), signal-to-noise ratio (SNR) of the ultrasound pulse-echo method, and the frequency range of the measurements. We performed an experiment in a section of porcine muscle to evaluate variation of the aforementioned parameters on the estimated shear wave velocity and material property measurements and to validate the error prediction model. The model showed that errors in the shear wave velocity and material property estimates were minimized by maximizing shear wave amplitude, pulse-echo SNR, Deltatau, and the bandwidth used for shear wave measurements. The experimental model showed op- imum performance could be obtained for Deltatau = 3-6 mm, SNR ges35 dB, with a frequency range of 100 to 600 Hz, and with a shear wave amplitude on the order of a few microns down to 0.5 mum. The model provides a basis to explore different parameters related to implementation of the SDUV method. The experiment confirmed conclusions made by the model, and the results can be used for optimization of SDUV. View full abstract»

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  • The application of synthetic focusing for imaging crack-like defects in pipelines using guided waves

    Page(s): 759 - 771
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    This paper deals with quantifying the performance of a technique for detection, location, and sizing of circumferential crack-like defects in pipelines using synthetically focused guided waves. The system employs a circumferential array of piezoelectric transducer elements. A torsional probing guided wave is excited using the array, which subsequently interacts with the reflecting features of the pipe, such as defects or weld caps. The recorded backscattered signals are synthetically focused to every point of interest in the pipe wall, to form an image of the reflecting features of the pipe. The defect image amplitude is used to estimate the defect depth, and the full width at half maximum of the defect image circumferential profile is used to estimate the circumferential extent of the defect. The imaging system is tested with data from finite element simulations and from laboratory experiments. It is found that reliable sizing of circumferential cracks in finite element simulations and experiments can be achieved if the circumferential extent of the defect is greater than 1.5 lambdaS, where lambdaS is the shear wavelength at the frequency of inspection. This result is theoretically valid for any pipe size, any axial defect location, and any inspection frequency. Amplitude gains of around 18 dB over an unfocused system have been observed experimentally in an 8-inch pipe with a 9 dB SNR improvement. View full abstract»

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  • High-frequency tortuosity relaxation in open-cell foams

    Page(s): 772 - 778
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB) |  | HTML iconHTML  

    Propagation of ultrasounds through open-cell polymeric foams is studied using air-coupled ultrasound and Fourier spectral analysis (both phase and magnitude) in the frequency range 0.1 to 6 MHz. A detailed micrographic study is first performed to determine struts dimensions and cell geometry, hence, a unit cell model to describe these foams is proposed. Ultrasound phase velocity and transmission loss were then measured. Variation of these magnitudes with the frequency follows the shape of a sigmoid growth. This behavior of the phase velocity can be explained by introducing an apparent tortuosity with a relaxation-like behavior, which can be explained by considering a probabilistic tortuous walk, as it has recently been performed for other kind of foams. However and unlike in previous studies, the present one shows the whole transition of this sigmoid growth for all studied foams. This is achieved by a precise selection of the foam samples and by the fabrication of new air-coupled transducers that enlarge the experimental working frequency range to lower frequencies. The study of the measured sigmoid growth is used to determine the probability function, required by the probabilistic tortuous walk model, which best describes the variation of the apparent tortuosity. View full abstract»

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  • A lateral-field-excited LiTaO3 high-frequency bulk acoustic wave sensor

    Page(s): 779 - 787
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (922 KB) |  | HTML iconHTML  

    The most popular bulk acoustic wave (BAW) sensor is the quartz crystal microbalance (QCM), which has electrodes on both the top and bottom surfaces of an AT-cut quartz wafer. In the QCM, the exciting electric field is primarily perpendicular to the crystal surface, resulting in a thickness field excitation (TFE) of a resonant temperature compensated transverse shear mode (TSM). The TSM, however, can also be excited by lateral field excitation (LFE) in which electrodes are placed on one side of the wafer leaving a bare sensing surface exposed directly to a liquid or a chemi/bio selective layer allowing the detection of both mechanical and electrical property changes caused by a target analyte. The use of LFE sensors has motivated an investigation to identify other piezoelectric crystal orientations that can support temperature-compensated TSMs and operate efficiently at high frequencies resulting in increased sensitivity. In this work, theoretical search and experimental measurements are performed to identify the existence of high-frequency temperature-compensated TSMs in LiTaO3. Prototype LFE LiTaO3 sensors were fabricated and found to operate at frequencies in excess of 1 GHz and sensitively detect viscosity, conductivity, and dielectric constant changes in liquids. View full abstract»

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  • Pulse echo and combined resonance techniques: a full set of LGT acoustic wave constants and temperature coefficients

    Page(s): 788 - 797
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB) |  | HTML iconHTML  

    This work reports on the determination of langatate elastic and piezoelectric constants and their associated temperature coefficients employing 2 independent methods, the pulse echo overlap (PEO) and a combined resonance technique (CRT) to measure bulk acoustic wave (BAW) phase velocities. Details on the measurement techniques are provided and discussed, including the analysis of the couplant material in the PEO technique used to couple signal to the sample, which showed to be an order of magnitude more relevant than the experimental errors involved in the data extraction. At room temperature, elastic and piezoelectric constants were extracted by the PEO and the CRT methods and showed results consistent to within a few percent for the elastic constants. Both raw acquired data and optimized constants, based on minimization routines applied to all the modes involved in the measurements, are provided and discussed. Comparison between the elastic constants and their temperature behavior with the literature reveals the recent efforts toward the consistent growth and characterization of LGT, in spite of significant variations (between 1 and 30%) among the constants extracted by different groups at room temperature. The density, dielectric permittivity constants, and respective temperature coefficients used in this work have also been independently determined based on samples from the same crystal boule. The temperature behavior of the BAW modes was extracted using the CRT technique, which has the advantage of not relying on temperature dependent acoustic couplants. Finally, the extracted temperature coefficients for the elastic and piezoelectric constants between room temperature and 120degC are reported and discussed in this work. View full abstract»

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  • Ultrasonic trapping of small particles by a vibrating rod

    Page(s): 798 - 805
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    In this paper, the ultrasonic trapping of small particles by a vibrating rod is proposed and analyzed. An aluminum rod, which is driven by an actuator and operates in the 0th order vibration mode (back and forth vibration mode), can trap small particles in water. The experimental phenomena and the trapping mechanism are theoretically analyzed, and the acoustic radiation force acting on a spherical particle near the surface of the vibrating rod is estimated. The effects of operating frequency, rod radius, particle radius and other physical parameters are investigated experimentally and theoretically, and useful guidelines to optimize the trapping capability are proposed. View full abstract»

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  • Full-wave analysis of piezoelectric boundary waves propagating along metallic grating sandwiched between two semi-infinite layers

    Page(s): 806 - 811
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (743 KB) |  | HTML iconHTML  

    This paper describes full-wave analysis of piezoelectric boundary acoustic waves (PBAWs) propagating along a metallic grating sandwiched between 2 semi-infinite layers. In the analysis, the finite element method (FEM) is used for the grating region while the spectral domain analysis (SDA) is applied for an isotropic overlay region as well as a piezoelectric substrate region. The combination of the FEM and SDA makes the numerical analysis very fast and precise. As an example, the analysis was made on the PBAWs propagating in an SiO2 overlay/ Cu grating/rotated Y-cut LiNbO3 structure. It is shown that both the shear-horizontal (SH) type and Rayleigh-type PBAWs are supported in the structure, and that their velocities are very close to each other. Thus spurious responses due to the Rayleigh-type PBAW should completely be suppressed for device implementation. Discussions are made in detail on the influence of Cu grating thickness, substrate rotation angle, and metallization ratio on excitation and propagation characteristics of the SH- and Rayleigh-type PBAWs. View full abstract»

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  • Feasibility of ultra-wideband SAW RFID tags meeting FCC rules

    Page(s): 812 - 820
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1207 KB) |  | HTML iconHTML  

    We discuss the feasibility of surface acoustic wave (SAW) radio-frequency identification (RFID) tags that rely on ultra-wideband (UWB) technology. We propose a design of a UWB SAW tag, carry out numerical experiments on the device performance, and study signal processing in the system. We also present experimental results for the proposed device and estimate the potentially achievable reading distance. UWB SAW tags will have an extremely small chip size (<0.5 times 1 mm2) and a low cost. They also can provide a large number of different codes. The estimated read range for UWB SAW tags is about 2 m with a reader radiating as low as <0.1 mW power levels with an extremely low duty factor. View full abstract»

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  • The use of real or complex coupling coefficients for lossy piezoelectric materials

    Page(s): 821 - 826
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (274 KB) |  | HTML iconHTML  

    Two competing approaches for calculating coupling coefficients for lossy piezoelectric materials, one producing a real result and the other a complex result, are compared and analyzed. It is found that the complex coupling coefficient suffers from mathematical difficulties, which the real coupling coefficient does not exhibit. Moreover, it is pointed out that a prediction made by the complex coupling coefficient theory conflicts with experiment while the corresponding real coupling coefficient theory prediction does not. When a coupling coefficient of interest has been computed from the real coupling coefficient theory using piezoelectric equations having intensive independent variables, the resulting expression has the same algebraic form as the corresponding static coupling coefficient formula. Moreover, only the real parts of the piezoelectric, elastic, and dielectric material properties appear. View full abstract»

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  • Fabrication and performance of high-frequency composite transducers with triangular-pillar geometry

    Page(s): 827 - 836
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    A single-element, 40-MHz, 3-mm diameter transducer was fabricated with a geometric focus at 9 mm. The transducer was based on a piezo-composite substrate with triangular-shaped composite pillars. The 2-way bandwidth of 50% and impedance magnitude were in agreement with that predicted using finite-element modeling. A one-way radiation pattern was collected using a needle hydrophone. The one-way -3 dB beamwidth at the geometric focus was measured to be 120 mum and the -3 dB depth of field was 2.5 mm. This is in good agreement with the theoretical predictions of 112.5 mum and 2.4 mm. The triangular-pillar composite transducer was then compared with a transducer with square composite pillars with similar volume fraction of active ceramic. A 9.5 dB reduction in the amplitude of the secondary resonance was found for the triangular-pillar composite as well as a 30% gain in the 2-way pulse bandwidth. A 256-element 30-MHz linear array was fabricated as a preliminary investigation into the use of the triangular pillar as the substrate in a high-frequency linear array transducer. In vivo images were generated with both the single-element and linear-array transducers. View full abstract»

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  • A 256 x 256 2-D array transducer with row-column addressing for 3-D rectilinear imaging

    Page(s): 837 - 847
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1455 KB) |  | HTML iconHTML  

    We present simulation and experimental results from a 5-MHz, 256times256 2-D (65536 elements, 38.4times38.4 mm) 2-D array transducer with row-column addressing. The main benefits of this design are a reduced number of interconnects, a modified transmit/receive switching scheme with a simple diode circuit, and an ability to perform volumetric imaging of targets near the transducer with transmit beamforming in azimuth and receive beamforming in elevation. The final dimensions of the transducer were 38.4 mm times 38.4 mm times 300 mum. After a row-column transducer was prototyped, the series resonance impedance was 104 Omega at 5.4 MHz. The measured -6 dB fractional bandwidth was 53% with a center frequency of 5.3 MHz. The SNR at the transmit focus was measured to be 30 dB. At 5 MHz, the average nearest neighbor crosstalk was -25 dB. In this paper, we present 3-D images of both 5 pairs of nylon wires embedded in a clear gelatin phantom and an 8 mm diameter cylindrical anechoic cyst phantom acquired from a 256 times 256 2-D array transducer made from a 1-3 composite. We display the azimuth and elevation B-scans as well as the C-scan for each image. The cross-section of the wires is visible in the azimuth B-scan, and the long axes can be seen in the elevation B-scan and C-scans. The pair of wires with 1-mm axial separation is discernible in the elevational B-scan. When a single wire from the wire target phantom was used, the measured lateral beamwidth was 0.68 mm and 0.70 mm at 30 mm depth in transmit beamforming and receive beamforming, respectively, compared with the simulated beamwidth of 0.55 mm. The cross-section of the cyst is visible in the azimuth B-scan whereas the long axes can be seen as a rectangle in the elevation B-scan and C-scans. View full abstract»

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  • Airborne ultrasonic phased arrays using ferroelectrets: a new fabrication approach

    Page(s): 848 - 858
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    In this work, a novel procedure that considerably simplifies the fabrication process of ferroelectret-based multi-element array transducers is proposed and evaluated. Also, the potential of ferroelectrets being used as active material for aircoupled ultrasonic transducer design is demonstrated. The new construction method of multi-element transducers introduces 2 distinctive improvements. First, active ferroelectret material is not discretized into elements, and second, the need of structuring upper and/or lower electrodes in advance of the permanent polarization of the film is removed. The aperture discretization and the mechanical connection are achieved in one step using a through-thickness conductive tape. To validate the procedure, 2 linear array prototypes of 32 elements, with a pitch of 3.43 mm and a wide usable frequency range from 30 to 300 kHz, were built and evaluated using a commercial phased-array system. A low crosstalk among elements, below -30 dB, was measured by interferometry. Likewise, a homogeneous response of the array elements, with a maximum deviation of plusmn1.8 dB, was obtained. Acoustic beam steering measurements were accomplished at different deflection angles using a calibrated microphone. The ultrasonic beam parameters, namely, lateral resolution, side lobe level, grating lobes, and focus depth, were congruent with theory. Acoustic images of a single reflector were obtained using one of the array elements as the receiver. Resulting images are also in accordance with numerical simulation, demonstrating the feasibility of using these arrays in pulse-echo mode. The proposed procedure simplifies the manufacturing of multidimensional arrays with arbitrary shape elements and not uniformly distributed. Furthermore, this concept can be extended to nonflat arrays as long as the transducer substrate conforms to a developable surface. View full abstract»

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  • Reduced harmonic representation for continuous wave, shock-producing focused beams

    Page(s): 859 - 863
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (449 KB) |  | HTML iconHTML  

    An extension to the frequency domain solution to Burgers' equation (FDSBE) is presented in the context of a continuous wave, nonlinear beam propagation model. The extension adds a specified number of harmonics to each FDSBE nonlinear substep in the shock-bearing region. The extension harmonics have amplitudes given by a 1/n amplitude decay assumption. The corresponding phases are given by linear extrapolation. The extension scheme allows for stable and accurate, reduced harmonic focal beam modeling. An algorithm is also presented that allows this scheme to provide accurate heating rate and radiation force output. 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