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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 7 • Date July 2003

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Displaying Results 1 - 25 of 29
  • 2002 Rayleigh award of the IEEE ultrasonics, ferroelectrics and frequency Control Society ultrasonics committee Calvin F. Quate

    Publication Year: 2003 , Page(s): 758 - 759
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  • 2002 achievement award of the IEEE ultrasonics, ferroelectrics, and frequency Control Society John A. Kusters

    Publication Year: 2003 , Page(s): 760 - 761
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  • 2002 distinguished service award of the IEEE ultrasonics, ferroelectrics, and fyequency Control Society Jan Brown

    Publication Year: 2003 , Page(s): 762 - 763
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  • 2001 outstanding paper award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society

    Publication Year: 2003 , Page(s): 764
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  • Two-dimensional equations for electroelastic plates with relatively large shear deformations

    Publication Year: 2003 , Page(s): 765 - 772
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB) |  | HTML iconHTML  

    A set of two-dimensional, nonlinear equations for electroelastic plates in moderately large thickness-shear deformations is obtained from the variational formulation of the three-dimensional equations of nonlinear electroelasticity by expanding the mechanical displacement vector and the electric potential into power series in the plate thickness coordinate. As an example, the equations are used to study nonlinear thickness-shear vibrations of a quartz plate driven by an electrical voltage. Nonlinear electrical current amplitude-frequency behavior near resonance is obtained. The equations and results are useful in the study and design of piezoelectric crystal resonators and the measurement of nonlinear material constants of electroelastic materials. View full abstract»

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  • Transmitting electric energy through a metal wall by acoustic waves using piezoelectric transducers

    Publication Year: 2003 , Page(s): 773 - 781
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB) |  | HTML iconHTML  

    The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piezoelectric layers. One of these layers models the driving transducer for generating acoustic wave, and the other layer models the receiving transducer for converting the acoustic energy into electric energy to power a load circuit. The output voltage, the output power, and the efficiency of this system are expressed as explicit functions of the system parameters. A numerical example is included to illustrate the dependence of the system performance upon the physical and geometrical parameters. View full abstract»

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  • A 1.6-mm, metal tube ultrasonic motor

    Publication Year: 2003 , Page(s): 782 - 786
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB) |  | HTML iconHTML  

    A miniaturized metal tube ultrasonic motor, the dimensions of which are 1.6 mm in diameter and 6 mm in length, was developed. Two flattened surfaces with 90 degrees were ground on the outer surface of the stator. Two PZT-based piezoelectric ceramics were bonded onto these flat surfaces. The asymmetrical surface of the stator developed the split of the two degenerated orthogonal bending modes, resulting in a wobble motion. The working frequency of the 1.6-mm motor with 6 mm in length was 130 kHz. A torque of 0.5 mNm was reached at a maximum power of 45 mW with a speed of 45 rad/sec. The maximum efficiency was 16%. View full abstract»

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  • AO-spectrum analyzer implementation into CDMA- telecommunications with enhanced SIR-factors

    Publication Year: 2003 , Page(s): 787 - 794
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    The devices for real-time narrowband interference measurements within the code division multiple access (CDMA) cellular communication system on the base of the acousto-optic spectrum analyzer (AOSA) with satisfactory performances can be designed. The overlay model giving significant advantages in the interference immunity for simultaneous operation of the wideband (CDMA) and the narrowband time division multiple access (TDMA) cellular systems is proposed. View full abstract»

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  • Autofocusing in medical ultrasound: the scaled covariance matrix algorithm

    Publication Year: 2003 , Page(s): 795 - 804
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    This work develops a class of ultrasound phase aberration correction/autofocusing algorithms that are based upon the properties of the covariance matrix of the channel signals for time-delay focused resolution/speckle cells. The scaled covariance matrix SCM algorithms are designed to blindly estimate and correct focusing timing errors due to thin layers of unanticipated fatty tissue located in the near field of the transducer array. An important aspect of the algorithm is that the scaling of the covariance matrix elements fundamentally establishes a channel independent phase reference relative to which the aberrant channel phases are estimated. The model development involved the combination of a rigorous mathematical analysis of the scattering of ultrasound in random scattering media and extensive statistical simulation studies with phase aberrations imposed upon both the transmit and received channel signals. Under the assumption of a near field aberration model, the statistical simulation analyses showed that the SCM algorithms in simulation are capable of accurately estimating relative time delay channel errors with RMS timing errors up to /spl sim/62 ns, with interchannel correlation lengths as short as 1.4 mm. View full abstract»

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  • Coded EXcitation with spectrum inversion (CEXSI) for ultrasound array imaging

    Publication Year: 2003 , Page(s): 805 - 823
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    In this paper, a scheme called coded excitation with spectrum inversion (CEXSI) is presented. An established optimal binary code whose spectrum has no nulls and possesses the least variation is encoded as a burst for transmission. Using this optimal code, the decoding filter can be derived directly from its inverse spectrum. Various transmission techniques can be used to improve energy coupling within the system pass-band. We demonstrate its potential to achieve excellent decoding with very low (<80 dB) side-lobes. For a 2.6 /spl mu/s code, an array element with a center frequency of 10 MHz and fractional bandwidth of 38%, range side-lobes of about 40 dB have been achieved experimentally with little compromise in range resolution. The signal-to-noise ratio (SNR) improvement also has been characterized at about 14 dB. Along with simulations and experimental data, we present a formulation of the scheme, according to which CEXSI can be extended to improve SNR in sparse array imaging in general. View full abstract»

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  • Adaptive clutter rejection filtering in ultrasonic strain-flow imaging

    Publication Year: 2003 , Page(s): 824 - 835
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2171 KB) |  | HTML iconHTML  

    This paper introduces strain-flow imaging as a potential new technique for investigating vascular dynamics and tumor biology. The deformation of tissues surrounding pulsatile vessels and the velocity of fluid in the vessel are estimated from the same data set. The success of the approach depends on the performance of a digital filter that must separate echo signal components caused by flow from tissue motion components that vary spatially and temporally. Eigenfilters, which are an important tool for naturally separating signal components adaptively throughout the image, perform very well for this task. The method is examined using two tissue-mimicking flow phantoms that provide stationary and moving clutter associated with pulsatile flow. View full abstract»

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  • Sample volume misregistration in linear array-based dual beam Doppler ultrasound systems

    Publication Year: 2003 , Page(s): 836 - 847
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3746 KB) |  | HTML iconHTML  

    Large velocity estimation errors can occur in dual beam Doppler ultrasound velocity measurement systems when there is left/right sample volume misregistration, particularly when the interbeam angle is small. Such misregistration will occur when there is tissue inhomogeneity. This is investigated for a typical type of inhomogeneity-a layer of fat-by calculating the amount of both angle and translation misregistration occurring in such a system realized using a single linear array transducer. The complex sample volume sensitivity is calculated using a modified time domain approach, combining the spatial impulse response method with ray tracing. The effects on these misregistrations of altering the aperture sizes and their relative positions on the array is then investigated to derive an improved aperture configuration for dual beam velocity estimation. Arrangements with transmit apertures wider than the receive apertures are shown to be preferable in this context. View full abstract»

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  • In-vivo synthetic aperture flow imaging in medical ultrasound

    Publication Year: 2003 , Page(s): 848 - 856
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (451 KB) |  | HTML iconHTML  

    A new method for acquiring flow images using synthetic aperture techniques in medical ultrasound is presented. The new approach makes it possible to have a continuous acquisition of flow data throughout the whole image simultaneously, and this can significantly improve blood velocity estimation. Any type of filter can be used for discrimination between tissue and blood flow without initialization, and the number of lines used for velocity estimation is limited only by the nonstationarity of the flow. The new approach is investigated through both simulations and measurements. A flow rig is used for generating a parabolic laminar flow, and a research scanner is used for acquiring RF data from individual transducer elements. A reference profile is calculated from a mass flow meter. The parabolic velocity profile is estimated using the new approach with a relative standard deviation of 2.2% and a mean relative bias of 3.4% using 24 pulse emissions at a flow angle of 45 degrees. The 24 emissions can be used for making a full-color flow map image. An in-vivo image of flow in the carotid artery for a 29-year-old male also is presented. The full image is acquired using 24 emissions. View full abstract»

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  • Directional velocity estimation using focusing along the flow direction. I: theory and simulation

    Publication Year: 2003 , Page(s): 857 - 872
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (915 KB) |  | HTML iconHTML  

    A new method for directional velocity estimation is presented. The method uses beam formation along the flow direction to generate data in which the correct velocity magnitude can be directly estimated from the shift in position of the received consecutive signals. The shift is found by cross-correlating the beamformed lines. The approach can find the velocity in any direction, including transverse to the traditionally emitted ultrasound beam. The velocity estimation is studied through extensive simulations using Field II. A 128-element, 7-MHz linear array is used. A parabolic velocity profile with a peak velocity of 0.5 m/s is simulated for different beam-to-flow angles and for different emit foci. At 45/spl deg/ the relative standard deviation over the profile is 1.6% for a transmit focus at 40 mm. At 90/spl deg/ the approach gave a relative standard deviation of 6.6% with a transmit focus of 80 mm, when using 8 pulse-echo lines and stationary echo canceling. Pulsatile flow in the femoral artery was also simulated using Womersley's flow model. A purely transverse flow profile could be obtained with a relative standard deviation of less than 10% over the whole cardiac cycle using 8 pulse emissions for each imaging direction, which is sufficient to show clinically relevant transverse color flow images. View full abstract»

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  • Directional velocity estimation using focusing along the flow direction. II: experimental investigation

    Publication Year: 2003 , Page(s): 873 - 880
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2832 KB) |  | HTML iconHTML  

    For pt. I see ibid., vol. 50, no. 7, p. 857 (2003). A new method for directional velocity estimation is investigated through a number of flow rig measurements. The method uses beam-formation along the flow direction to generate data, where the correct velocity magnitude can directly be estimated from the shift in position of the received consecutive signals. The shift is found by cross-correlating the beamformed lines. The approach can find the velocity in any direction, including transverse to the traditionally emitted ultrasound beam. The method is investigated using a flow rig with a peak velocity of 0.15 m/s. A 7-MHz linear array transducer is used together with a dedicated sampling system to acquire signals from 64 transducer elements simultaneously. A technique for obtaining 128-element data using multiplexing is also presented. The data is beamformed off-line on a PC. A relative standard deviation of 1.4% can be obtained for a beam-to-flow angle of 45/spl deg/ and 4.3% at 90/spl deg/. Color flow images are displayed showing that the correct velocity magnitude can be obtained with the method for beam-to-flow angles of 60 and 90/spl deg/ with an accuracy of 3 to 4%. View full abstract»

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  • Multifrequency ultrasound transducers for conformal interstitial thermal therapy

    Publication Year: 2003 , Page(s): 881 - 889
    Cited by:  Papers (7)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    Control over the pattern of thermal damage generated by interstitial ultrasound heating applicators can be enhanced by changing the ultrasound frequency during heating. The ability to change transmission frequency from a single transducer through the use of high impedance front layers was investigated in this study. The transmission spectrum of multifrequency transducers was calculated using the KLM equivalent circuit model and verified with experimental measurements on prototype transducers. The addition of a quarter-wavelength thick PZT (unpoled) front layer enabled the transmission of ultrasound at two discrete frequencies, 4.7 and 9.7 MHz, from a transducer with an original resonant frequency of 8.4 MHz. Three frequency transmission at 3.3, 8.4, and 10.8 MHz was possible for a transducer with a half-wavelength thick front layer. Calculations of the predicted thermal lesion size at each transmission frequency indicated that the depth of thermal lesion could be varied by a factor of 1.6 for the quarter-wavelength front layer. Heating experiments performed in excised liver tissue with a dual-frequency applicator confirmed this ability to control the shape of thermal lesions during heating to generate a desired geometry. Practical interstitial Designs that enable the generation of shaped thermal lesions are feasible. View full abstract»

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  • A complex virtual source approach for calculating the diffraction beam field generated by a rectangular planar source

    Publication Year: 2003 , Page(s): 890 - 897
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1155 KB) |  | HTML iconHTML  

    In this paper, a complex virtual source approach for calculating the ultrasound field generated by a rectangular planar source is presented. Instead of using a real rectangular plane source, the equivalent sources that have complex amplitudes in complex space are used to compute the sound field distribution. The parabolic equation first is solved in the k-space domain by applying Fourier transform. The k-space domain source is then expressed as a set of Gaussian functions, and the related coefficients is determined by the optimization method. The analytic solution then is derived, and the effect of the parameters on the calculation accuracy is discussed. The comparison between the proposed fast numerical scheme and previous methods (Fresnel integral and Ocheltree's method) and are given in an example. The numerical results reveal that the computation time in obtaining accurate calculations is greatly reduced by using the proposed method. View full abstract»

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  • An acoustic proximity ranging system for monitoring the cavity thickness

    Publication Year: 2003 , Page(s): 898 - 910
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (767 KB) |  | HTML iconHTML  

    To control high speed underwater vehicles, a proximity ranging system is needed to monitor the cavity thickness. In this paper, we study a time-of-flight (TOF) principle based acoustic proximity ranging system. By taking into account the acoustically hard boundary at the air-water interface, we first present a two-stage computationally efficient time delay estimation algorithm, referred to as the PEARS (Parameter Estimation for Acoustic Ranging Systems) algorithm, which is applicable to arbitrary transmitted waveforms. Numerical results based on a simulated waveform demonstrate that the PEARS estimates can approach the Cramer-Rao bound as the signal-to-noise ratio increases. We then present experiments performed by using commercially available acoustic transducers to further verify our method. To update TOF estimates quickly, a specially designed continuous wave (CW) is applied to the transducer. Experimental results show that PEARS can achieve high measurement accuracy for ranging distances less than 100 mm with an achievable parameter update rate of approximately 1.5 kHz. View full abstract»

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  • Robust control of linear ceramic motor drive with LLCC resonant technique

    Publication Year: 2003 , Page(s): 911 - 920
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1797 KB) |  | HTML iconHTML  

    This study presents a robust control system for a linear ceramic motor (LCM) that is driven by a high-frequency voltage source inverter using two-inductance two-capacitance (LLCC) resonant technique. The structure and driving principle of the LCM are introduced. Because the dynamic characteristics and motor parameters of the LCM are nonlinear and time varying, a robust control system is designed based on the hypothetical dynamic model to achieve high-precision position control. The presentation of robust control for the LCM drive system is divided into three parts, which comprise state feedback controller, feed-forward controller, and uncertainty controller. The adaptation laws of control gains in the robust control system are derived in the sense of Lyapunov stability theorem such that the stability of the control system can be guaranteed. It not only has the learning ability similar to intelligent control, but also its control framework is more simple than intelligent control. With the proposed robust control system, the controlled LCM drive possesses the advantages of good tracking control performance and robustness to uncertainties. The effectiveness of the proposed robust control system is verified by experimental results in the presence of uncertainties. In addition, the advantages of the proposed control system are indicated in comparison with the traditional integral-proportional (IP) position control system. View full abstract»

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  • Electric poling and electromechanical characterization of 0.1-mm-thick sensor films and 0.2-mm-thick cable layers from poly(Vinylidene Fluoride-Trifluroethylene)

    Publication Year: 2003 , Page(s): 921 - 931
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1719 KB) |  | HTML iconHTML  

    Piezoelectric polymers have been proposed for many sensor and actuator applications. Among these, piezoelectric polymer films with thicknesses between several tens and a few hundreds of micrometers as well as coaxial cables with piezoelectric polymer layers are highly suitable and attractive for the detection of mechanical loads. In addition to good piezoelectric properties, materials for such sensors should have high mechanical strength. Therefore, the most common materials are nonporous piezoelectric polymers, such as polyvinylidene fluoride (PVDF) or its copolymer with trifluoroethylene (P(VDF-TrFE)). Here, P(VDF-TrFE) polymer films as well as the operating principle and the geometry of piezoelectric polymer cables are described. As active piezoelectric cable layer, P(VDF-TrFE) (76/24) was employed. After electrical poling with one or more point-to-cable corona discharges, the polarization in the P(VDF-TrFE) layer was investigated. Poling parameters, such as electric field and poling time, were varied. The resulting polarization was characterized with measurements of polarization profiles across the film or the cable-layer thickness as well as with the determination of other electromechanical quantities. The optimized poling process yields good piezoelectric properties in the piezoelectric polymer layers as well as useful sensor properties of the piezoelectric polymer cable, which are assessed and discussed. View full abstract»

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  • In-air and underwater performance and finite element analysis of a flextensional device having electrostrictive poly(vinylidene fluoride-trifluoroethylene) polymers as the active driving element

    Publication Year: 2003 , Page(s): 932 - 940
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1510 KB) |  | HTML iconHTML  

    A flextensional transducer, in which the electrostrictive poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer was used as the active driving element, was fabricated and characterized. The results show that transducers of several millimeters thick can produce an axial displacement of more than 1 mm in air along the thickness direction, and a transmitting voltage response of 123 dB re 1 /spl mu/Pa/V at 1 m in water at frequencies of several kilohertz. A finite element code (ANSYS, Inc., Canonsburg, PA) was used to model the in-air and underwater responses of the flextensional transducer over a broad frequency range. The calculated resonance frequencies and transmitting voltage response spectra show good agreement with the experimental data. In addition, the performance of both the in-air actuator and underwater transducer was analyzed for different design parameters of the flextensional structure. These results show that the performance of the flextensional transducer could be tailored readily by adjusting the parameters of the flextensional metal shell. View full abstract»

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  • [Front cover]

    Publication Year: 2003 , Page(s): i
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  • [Inside front cover]

    Publication Year: 2003 , Page(s): ii
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  • [Inside back cover]

    Publication Year: 2003 , Page(s): iii
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  • Table of contents

    Publication Year: 2003 , Page(s): iv
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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