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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 4 • Date July 2001

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Displaying Results 1 - 25 of 36
  • Recent developments and understanding of ferroelectric and piezoelectric materials and their applications

    Publication Year: 2001 , Page(s): 851 - 852
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (105 KB) |  | HTML iconHTML  

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  • Comments on a study of drift in cesium frequency standards

    Publication Year: 2001
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (98 KB) |  | HTML iconHTML  

    This letter comments on a recent study of the drift rate of 115 cesium standards. The conclusion here is that no aging effect is visible in the results of the study. View full abstract»

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  • Two-dimensional noise-robust blind deconvolution of ultrasound images

    Publication Year: 2001 , Page(s): 861 - 866
    Cited by:  Papers (21)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (946 KB) |  | HTML iconHTML  

    This paper presents a new method for 2-D blind homomorphic deconvolution of medical B-scan ultrasound images. The method is based on noise-robust 2-D phase unwrapping and a noise-robust procedure to estimate the pulse in the complex cepstrum domain. Ordinary Wiener filtering is used in the subsequent deconvolution. The resulting images became much sharper with better defined tissue structures compared with the ordinary images. The deconvolved images had a resolution gain of the order of 3 to 7, and the signal-to-noise ratio (SNR) doubled for many of the images used in our experiments. The method gave stable results with respect to noise and gray levels through several image sequences. View full abstract»

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  • Three-dimensional blind deconvolution of ultrasound images

    Publication Year: 2001 , Page(s): 867 - 871
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1155 KB) |  | HTML iconHTML  

    Three-dimensional ultrasound images are blurred by the ultrasound pulse through the convolution between the 3-D tissue signal and the 3-D pulse. The blurring reduces the spatial resolution of the 3-D ultrasound images and, consequently, their diagnostic value. This paper presents a method for 3-D blind homomorphic deconvolution of medical 3-D ultrasound images to improve their spatial resolution. The blind estimate of the 3-D pulse is necessary because the pulse changes in spatial extent and frequency composition as it passes through the tissues and because the pulse is not separable in its spatial dimensions. The method was tested on a 3-D image of a phantom with anechoic spheres of known size in a uniform diffuse scattering matrix. The spheres were clearly better defined and had volumes much closer to the true volume in the deconvolved image than in the original image. View full abstract»

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  • Finite element simulation of piezoelectric transformers

    Publication Year: 2001 , Page(s): 872 - 878
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (685 KB) |  | HTML iconHTML  

    Piezoelectric transformers are nothing but ultrasonic resonators with two pairs of electrodes provided on the surface of a piezoelectric substrate in which electrical energy is carried in the mechanical form. The input and output electrodes are arranged to provide the impedance transformation, which results in the voltage transformation. As they are operated at a resonance, the electrical equivalent circuit approach has traditionally been developed in a rather empirical way and has been used for analysis and design. The present paper deals with the analysis of the piezoelectric transformers based on the three-dimensional finite element modelling. The PIEZO3D code that we have developed is modified to include the external loading conditions. The finite element approach is now available for a wide variety of the electrical boundary conditions. The equivalent circuit of lumped parameters can also be derived from the finite element method (FEM) solution if required. The simulation of the present transformers is made for the low intensity operation and compared with the experimental results. Demonstration is made for basic Rosen-type transformers in which the longitudinal mode of a plate plays an important role; in which the equivalent circuit of lumped constants has been used. However, there are many modes of vibration associated with the plate, the effect of which cannot always be ignored. In the experiment, the double resonances are sometimes observed in the vicinity of the operating frequency. The simulation demonstrates that this is due to the coupling of the longitudinal mode with the flexural mode. Thus, the simulation provides an invaluable guideline to the transformer design. View full abstract»

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  • Optical resonant ultrasound spectroscopy for fluid properties measurement [fuel capsules]

    Publication Year: 2001 , Page(s): 879 - 885
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    The properties of fluids are studied using unusually small containment spherical resonators. Proper identification of resonant fluid signatures allows determination of pressure and density of the internal gas with great accuracy using an appropriate equation of state (EOS). Low noise and high sensitivity detection of vibration are critical parameters to characterizing the contained gas when its pressure approaches 1 atm. or less. The benefits of using spherical resonators to determine fluid properties are discussed, and some example calculations of sound speed are presented. In addition to measuring fluids, a comparative experimental approach is taken to explore and, eventually, to optimize vibration detection. In the experiments, two detection methods, a contact piezoelectric transducer (PZT) device and a non-contact optical device, are compared simultaneously and quantitatively. This is done in a unique manner without change in vibration coupling to the sample between tests. A commercially available resonant ultrasound spectroscopy system is used as the contact system, while another commercial device (used as the non-contact vibration detector) combined with the same excitation source (used in the contact system) comprises the other system. The non-contact detector is an optical interferometric receiver that provides adaptation to optically rough surfaces and high sensitivity to acoustic displacements through optical interference in photorefractive GaAs. Both vibration detection systems are compared with particular emphasis on displacement sensitivity, frequency response, and noise level. Furthermore, the results from comparing detection modalities are presented, and their effects on fluid properties measurement are discussed. View full abstract»

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  • A new estimator for vector velocity estimation [medical ultrasonics]

    Publication Year: 2001 , Page(s): 886 - 894
    Cited by:  Papers (26)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (998 KB) |  | HTML iconHTML  

    A new estimator for determining the two-dimensional velocity vector using a pulsed ultrasound field is derived. The estimator uses a transversely modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new estimator automatically compensates for the axial velocity when determining the transverse velocity. The estimation is optimized by using a lag different from one in the estimation process, and noise artifacts are reduced by averaging RF samples. Further, compensation for the axial velocity can be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce the influence of a spatial velocity spread. Examples for different velocity vectors and field conditions are shown using both simple and more complex field simulations. A relative accuracy of 10.1% is obtained for the transverse velocity estimates for a parabolic velocity profile for flow transverse to the ultrasound beam and a SNR of 20 dB using 20 pulse-echo lines. The overall bias in the estimates was -4.3%. View full abstract»

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  • Finite element analysis of the behavior of the scanning microdeformation microscope

    Publication Year: 2001 , Page(s): 895 - 899
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    The scanning microdeformation microscope, as many other scanning probe microscopes developed in the last years, is a kind of ac force microscope using the near-field acoustic interaction. The heart of the system is an electromechanical oscillator made of a silicon cantilever, a diamond or sapphire tip, associated with a bimorph piezoelectric transducer and a specific amplifier. The specificity of the system is the way of detection of the oscillation frequency performed electrically through the admittance of the piezoelectric transducer. In this paper, we describe the technique of detection involved in the microscope. A modelling of the complete behavior of the electromechanical oscillator performed with the finite element method (FEM) (of simulation) is presented. A comparison between experimental and theoretical behavior shows a very good agreement. View full abstract»

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  • Recurrent fuzzy neural network control for piezoelectric ceramic linear ultrasonic motor drive

    Publication Year: 2001 , Page(s): 900 - 913
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (658 KB) |  | HTML iconHTML  

    In this study, a recurrent fuzzy neural network (RFNN) controller is proposed to control a piezoelectric ceramic linear ultrasonic motor (LUSM) drive system to track periodic reference trajectories with robust control performance. First, the structure and operating principle of the LUSM are described in detail. Second, because the dynamic characteristics of the LUSM are nonlinear and the precise dynamic model is difficult to obtain, a RFNN is proposed to control the position of the moving table of the LUSM to achieve high precision position control with robustness. The back propagation algorithm is used to train the RFNN on-line. Moreover, to guarantee the convergence of tracking error for periodic commands tracking, analytical methods based on a discrete-type Lyapunov function are proposed to determine the varied learning rates of the RFNN. Then, the RFNN is implemented in a PC-based computer control system, and the LUSM is driven by a unipolar switching full bridge voltage source inverter using LC resonant technique. Finally, the effectiveness of the RFNN-controlled LUSM drive system is demonstrated by some experimental results. Accurate tracking response and superior dynamic performance can be obtained because of the powerful on-line learning capability of the RFNN controller. Furthermore, the RFNN control system is robust with regard to parameter variations and external disturbances. View full abstract»

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  • Frequency-dependent open-circuit acoustic sensitivity of fluid-filled, coated, radially polarized piezoelectric ceramic cylindrical shells of arbitrary thickness and infinite length

    Publication Year: 2001 , Page(s): 914 - 921
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    The frequency-dependent free-field open-circuit voltage generated by radially polarized piezoelectric ceramic fluid-filled shells of infinite length coated with an elastic layer and excited by a plane acoustic wave is studied. The shell and the coating are of arbitrary thickness and are anisotropic. It is shown that the charge density in the piezoelectric shell is zero by using the electrostatic and open-circuit conditions. General expressions for the pressures and radial velocities in the interior and exterior fluids are obtained by using the finiteness and radiation conditions, respectively. General expressions for the radial stresses and velocities in the piezoelectric shell and elastic coating are also determined by using two-dimensional equations of state and axisymmetric equations of motion. The coefficients in the general expressions are then determined by using the continuity conditions at the various interfaces. Finally, an expression for the open-circuit sensitivity is obtained by using a piezoelectric equation of state. Numerical results are presented for air, water, and vacuum in the interior, two types of elastic coating, and piezoelectric shells with various thicknesses. The effect of neglecting anisotropy on the sensitivity is also illustrated. View full abstract»

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  • Digital phased array beamforming using single-bit delta-sigma conversion with non-uniform oversampling

    Publication Year: 2001 , Page(s): 922 - 931
    Cited by:  Papers (17)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1195 KB) |  | HTML iconHTML  

    Digital beamforming based on oversampled delta-sigma (/spl Delta//spl Sigma/) analog-to-digital (A/D) conversion can reduce the overall cost, size, and power consumption of phased array front-end processing. The signal resampling involved in dynamic /spl Delta//spl Sigma/ beamforming, however, disrupts synchronization between the modulators and demodulator, causing significant degradation in the signal-to-noise ratio. As a solution to this, we have explored a new digital beamforming approach based on non-uniform oversampling /spl Delta//spl Sigma/ A/D conversion. Using this approach, the echo signals received by the transducer array are sampled at time instants determined by the beamforming timing and then digitized by single-bit /spl Delta//spl Sigma/ A/D conversion prior to the coherent beam summation. The timing information involves a nonuniform sampling scheme employing different clocks at each array channel. The /spl Delta//spl Sigma/ coded beamsums obtained by adding the delayed 1-bit coded RF echo signals are then processed through a decimation filter to produce final beamforming outputs. The performance and validity of the proposed beamforming approach are assessed by means of emulations using experimental raw RF data. View full abstract»

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  • A new detection method for capacitive micromachined ultrasonic transducers

    Publication Year: 2001 , Page(s): 932 - 942
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1396 KB) |  | HTML iconHTML  

    Capacitive micromachined ultrasonic transducers (cMUT) have become an alternative to piezoelectric transducers in the past few years. They consist of many small circular membranes that are connected in parallel. In this work, we report a new detection method for cMUTs. We model the membranes as capacitors and the interconnections between the membranes as inductors. This kind of LC network is called an artificial transmission line. The vibrations of the membranes modulate the electrical length of the transmission line, which is proportional to the frequency of the signal through it. By measuring the electrical length of the artificial line at a high RF frequency (in the gigahertz range), the vibrations of the membranes can be detected in a very sensitive manner. For the devices we measured, we calculated the minimum detectable displacement to be in the order of 10/sup -5/ /spl Aring///spl radic/Hz with a possible improvement to 10/sup -7/ /spl Aring///spl radic/Hz. View full abstract»

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  • Optimization of wide-band linear arrays

    Publication Year: 2001 , Page(s): 943 - 952
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB) |  | HTML iconHTML  

    An optimization method is proposed for linear arrays to be used in ultrasound systems under wide-band operation. A fast algorithm, the threshold accepting, has been utilized to determine the element positions and weight coefficients of a linear array that generates a desired beam pattern. To reduce the computational burden in the optimization procedure, an efficient numerical routine for the beam pattern evaluation has been implemented. We address the optimization problem of both dense and sparse wideband arrays. In the first case, the goal is to minimize the side-lobe energy by varying the element weights; we compare the optimized beam pattern with that obtained with classical shading functions, showing that better results can be achieved with a wide-band optimization. We also consider the optimization of the layout (positions and weights) of a sparse linear array to achieve a desired beam pattern with a fixed or minimum number of array elements. The comparison of the proposed method with a narrow-band optimization algorithm is presented, showing that better performances (about -7 dB further reduction of the side-lobe level) can be achieved with a wide-band sparse array optimization. Further numerical simulations are given, showing that the proposed method yields better results than wideband sparse random arrays and periodic arrays with the same aperture width. View full abstract»

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  • On modeling biomedical ultrasound RF echoes using a power-law shot-noise model

    Publication Year: 2001 , Page(s): 953 - 968
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1043 KB) |  | HTML iconHTML  

    We propose a new model for the RF ultrasound echo, namely the power-law shot-noise process. Based on this model, the in-phase and quadrature components of the echo are shown to exhibit 1/f β-type spectral behavior, in a sense that is defined in the paper. The envelope also exhibits this type of spectral behavior, but with a different exponent. This result explains the experimental observations by other researchers of the power-law trend of the RF echo spectrum. Although the shot-noise model has been used in the past for modeling the RF echo, this is the first time that a power-law impulse response filter is used and that the resulting 1/f β-type spectral behavior of the RF echo has been investigated. The model parameters are linked to tissue characteristics, such as scatterer density and attenuation; thus, they have the potential to be used as tissue characterization features. The validity of the proposed model is tested based on a database of 100 clinical ultrasound images of the breast. View full abstract»

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  • Acoustical diffraction tomography in a finite form and its computer simulations

    Publication Year: 2001 , Page(s): 969 - 975
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    Until now, all acoustical diffraction reconstruction algorithms are in infinite forms. All of these algorithms have disadvantages: severe limitations on scatterers or tedious calculations. In this paper, we present a new reconstruction algorithm in a finite form using the method of formal parameter, which is very simple. This new algorithm gives an exact reconstruction when the amplitude of the scattered wave is smaller than that of the incident wave everywhere. This assumption is much less restrictive than that for the first and second-order Born approximations. Although this new algorithm is in a finite form, it is still an approximate one when the amplitude of the scattered wave is not smaller than that of the incident wave everywhere. However, it still gives a good reconstruction when the amplitude of the scattered wave is a little greater than that of the incident wave in some area. Some numerical examples have confirmed these conclusions. View full abstract»

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  • Admittance matrix of asymmetric piezoelectric bimorph with two separate electrical ports under general distributed loads

    Publication Year: 2001 , Page(s): 976 - 984
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    The dynamic admittance matrix of the asymmetric triple-layer piezoelectric bimorph subjected to the general distributed harmonic loads as well as the flexural moments and the vertical loads at the tip are presented. The top and bottom piezoelectric layers have two separate electrical ports such that each layer can be used as either a sensor or an actuator. The variation principle is used for deriving the motion equations and the conjugate parameters that maintain the symmetry of the admittance matrix. The mechanical displacements and forces at the tip are expressed in a matrix form, which, together with the reciprocal condition, greatly simplify the analysis procedure. The derived admittance matrix under the cantilevered condition is presented by a five-by-five matrix, each row representing the relationships of the displacement and rotation at the tip, the volume averaged displacement, the separate electrical charges with the flexural moment and vertical load at the tip, the magnitude of the distributed load, and the voltages. The matrices, which reduce to simpler forms for several special cases, are then used to determine the two-port electrical admittance. It is shown that the derived admittance matrix covers the various boundary conditions, the electrical parallel and series connections, and the arbitrary lay-up, including the unimorph, used as both sensors and actuators. View full abstract»

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  • Parametric modeling with beamspread compensation and MIMO frequency domain inversion applied to fine saturated sands

    Publication Year: 2001 , Page(s): 985 - 997
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (828 KB) |  | HTML iconHTML  

    A system identification technique is applied to estimate the intrinsic absorption and dispersion of two fine sands. The method is based on the parametric modeling of the wave propagation through a Plexiglas tank filled with the sediment under investigation. The applicability of various porous models is discussed. The viscoelastic constant Q model and viscoelastic rational form model are applied and compared. Closed form expressions describing the wave propagation are replaced by Debye series expansions with correction coefficients that consider the beamspread caused by the finite aperture of the emitter. A multiple input multiple output (MIMO) representation is used in conjunction with the maximum likelihood estimator (MLE) for the estimation of the sediment parameters. The estimated absorption and dispersion curves are depicted. View full abstract»

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  • Surface acoustic waves propagating over a rotating piezoelectric half-space

    Publication Year: 2001 , Page(s): 998 - 1004
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (419 KB) |  | HTML iconHTML  

    Surface acoustic waves (SAW) propagating over a piezoelectric half-space rotating at a constant angular rate about a fixed axis are analyzed using the linear theory of piezoelectricity, including Coriolis and centrifugal forces. Rotation sensitivity, the rotation induced change of wave speed, is studied. The dependence of the rotation sensitivity on the orientation of the rotation axis and the orientation of the material is examined. Numerical results for polarized ceramics PZT-5H are presented to show the detailed characteristics of the rotation sensitivity. The implications of the numerical results are discussed for different applications. View full abstract»

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  • A simplified approach for real-time detection of arterial wall velocity and distension

    Publication Year: 2001 , Page(s): 1005 - 1012
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1099 KB) |  | HTML iconHTML  

    Arterial stiffness is known to increase with age and with many vascular diseases, but its noninvasive assessment in patients still represents a difficult task. The measurement of diameter change during the cardiac cycle (distension) has been proposed as a means to estimate arterial compliance and stiffness. Therefore, we have developed a simple PC-based device and algorithm for noninvasive quantification of vessel wall motion and diameter change in humans. This goal is achieved in real-time by processing the base-band signals from a commercial ultrasound Doppler system. Real-time operation is of crucial importance, because it allows a rapid achievement of optimal measurement conditions. The system was evaluated in a laboratory using a string phantom and was tested on the carotid arteries of 10 volunteers. Wall velocities from 0.05 to 600 mm/s and displacements lower than 2 μm were detected with phantoms. The measured carotid diameter change in the volunteers ranged from 7.5 to 11.8% (mean=9.8%) and agrees closely with values reported in the literature. The difference between values taken one hour apart ranged from 0.2 to 0.5%. We conclude that the new system provides rapid, accurate, and repeatable measurements of vessel distension in humans. View full abstract»

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  • Three-stage approach to ultrasound contrast detection

    Publication Year: 2001 , Page(s): 1013 - 1022
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB) |  | HTML iconHTML  

    A new method for detecting ultrasound contrast agents using a three-stage pulsing sequence is proposed. The method is based on observations showing that the scattering properties of contrast agents are modified by ultrasonic insonation at high power, but remain unchanged at low power. The objective of the first stage of the pulsing sequence is to use low power pulses to obtain a high resolution reference image without altering the agent. Higher power pulses in the second stage modify the contrast agent. The third stage detects the changes imposed to the contrast agent using low power pulses. A temporal filter is proposed to discriminate contrast response from clutter signal. The method is similar to power Doppler methods in that it uses several pulses to survey the target while destroying the agent. The new idea is to separate detection and destruction to circumvent a trade-off between sensitivity and resolution. Results from in vitro experiments with three different contrast agents are presented. The results are compared with harmonic power Doppler processed from the same data and show that an improvement in sensitivity is achievable by including the high power burst in the pulsing sequence. The results also show that the proposed filter reduces clutter artifacts from moving tissue. View full abstract»

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  • Ultrasound scattering model: 2-D cross-correlation and focusing criteria-theory, simulations, and experiments

    Publication Year: 2001 , Page(s): 1023 - 1030
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    A microscopic scattering model is developed to expedite simulation studies of ultrasound imaging in soft tissue using multichannel transducer probes. The model fully accounts for the physics of broadband signals, propagating wave packets, and time delay focusing. Analytical results are presented for 2-D transducer arrays; 1-D results can be trivially extracted by setting the number of rows equal to unity. The 2-D cross-correlation and the 2-D form of the Mallart-Fink (MF) focusing factor are calculated. It is demonstrated that the scattering model reduces to the 2-D form of the monochromatic van Cittert Zernike (VCZ) analysis. Simulation results for the focusing factor are presented, and comparisons are given between the values obtained from simulation, analytical theory, and actual water tank experiments. The comparative results are ail in close accord with each other. View full abstract»

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  • Ultrasonic six-axis deformation sensing

    Publication Year: 2001 , Page(s): 1031 - 1045
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1840 KB) |  | HTML iconHTML  

    In this paper, we describe a newly developed deformation sensing scheme in a soft medium, which is based on precise encoding and decoding of deformation components into ultrasound wavefronts. It can detect three translational components and three rotational components of displacement around a transmitter position nearly simultaneously. We assume a cell structure that consists of a 2/spl times/2 ultrasonic transmitter matrix and a 2/spl times/2 ultrasonic receiver matrix, which are placed face to face at a distance of a few tens of wavelengths. All of the transmitter elements are driven sinusoidally and simultaneously, but they are switched into the same, reversed, or quadrature phases to generate a particular shape of wavefront on the receiver matrix. The receiver elements are connected in such a way to obtain amplitude and spatial gradients of the wavefront at a center of the receiver matrix. First, we describe the transduction theory for the six dimensions and show the orthogonality, locality, and simultaneity of this sensing scheme. Then, we describe the fabrication and experimental evaluation of the cell. We also describe a prototype tactile sensor in which a single cell is embedded in a flexible hemispherical fingertip-like body. View full abstract»

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  • The generation and detection of longitudinal guided waves in thin fibers using a conical transformer

    Publication Year: 2001 , Page(s): 1046 - 1053
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (702 KB) |  | HTML iconHTML  

    This paper describes a technique to couple ultrasonic energy from a piezoceramic disc transducer into a fiber waveguide to induce longitudinal propagation. A polymer cone is utilized to bond the fiber waveguide onto the surface of the disc and to behave as a mechanical transformer, converting lateral displacements at its base into longitudinal displacements at its apex. Wideband finite element analysis (FEA) results are provided to show that the bond efficiently couples the radial modes of a disc transducer into fiber waveguides for longitudinal mode excitation. Furthermore, narrowband FEA is utilized to investigate how the geometry and material properties of the bond and waveguide influence the coupling efficiency. The technique is then quantified in terms of signal-to-coherent noise ratio (SCNR), reflecting its ability to generate the desired longitudinal waveguide mode and reject erroneous modes. Finally, design parameters are outlined for the successful implementation of this technique. View full abstract»

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  • Traveling wave excitation in a flexural vibration ring by using a torsional-flexural composite transducer

    Publication Year: 2001 , Page(s): 1054 - 1059
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB) |  | HTML iconHTML  

    This paper presents a new mechanism for traveling wave excitation of the flexural vibration in a ring. A torsional-flexural composite transducer was used to excite two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the ring. The prototype, composed of a 32-mm diameter composite transducer attached along the outer edge of an 180-mm diameter aluminum annular ring, was designed, constructed, and tested. The ring was designed via finite element analysis to operate using a (0,8) transverse flexural traveling wave, and the motion was confirmed experimentally. View full abstract»

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  • Improved ultrasonic spectroscopy methods for characterization of dispersive materials

    Publication Year: 2001 , Page(s): 1060 - 1065
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    Transmission ultrasonic spectroscopy method has been successfully implemented for the characterization of piezoceramics at high frequencies. There are, however, still some intrinsic error sources that limit the accuracy of the method. In this paper, two improved ultrasonic spectroscopy methods are presented, which can reduce the number of pre-required parameters and reduce another error source. The two improved methods were used to measure the frequency dispersion of phase velocity and attenuation of doped piezoceramic lead zirconate titanate (PZT-5A); results were compared with those obtained from the conventional method. The advantages and limitations of each method are discussed. 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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