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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 3 • Date May 1991

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Displaying Results 1 - 21 of 21
  • Use of longitudinal ultrasonic velocity as a predictor of elastic moduli and density of sintered uranium dioxide

    Publication Year: 1991 , Page(s): 161 - 165
    Cited by:  Papers (1)
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    Nondestructive characterization of sintered uranium dioxide using ultrasonics is addressed. The values of elastic moduli and ultrasonic velocity of uranium dioxide as a function of pore volume fraction are compared with the predicted values of elasticity and self-consistent scattering theories. Analysis of data shows that the longitudinal ultrasonic velocity may be used as a predictor of density and elastic moduli and that the relationship between the elastic moduli and longitudinal velocity is linear over a change of Young's modulus by 50%.<> View full abstract»

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  • Temperature effects in the focal region of acoustic microscope

    Publication Year: 1991 , Page(s): 166 - 171
    Cited by:  Papers (1)
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    New analytical expressions that account for radial and axial heat flow in a medium and immersion liquid are derived for the case of a Gaussian-shaped ultrasonic beam pattern near a focus of an acoustic microscope in thin or semi-infinite absorbing materials for two cases corresponding to the studying of biological or solid-state samples. In the first case, it is assumed that the sample together with the immersion represents a medium uniform in its thermal properties. In the second case, it is supposed that heat conductivity of a sample material is much more than that of the immersion liquid. Solutions are given for temperature growth along the axis of symmetry of acoustic lenses. The use of these equations in estimation of the temperature growth gives a maximum value of one degree for biological samples with the absorption coefficient ten times more than that of water and 10/sup -3/ degrees C for samples of silicon for the microscope with a maximum ultrasonic intensity of 10/sup 3/ W/cm/sup 2/ at 500 MHz and with water as an immersion liquid.<> View full abstract»

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  • Estimation of mean frequency and variance of ultrasonic Doppler signal by using second-order autoregressive model

    Publication Year: 1991 , Page(s): 172 - 182
    Cited by:  Papers (16)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (982 KB)  

    In order to estimate the mean frequency and variance of the diagnostic ultrasound Doppler signal in the presence of clutter noise, a new estimator using a second-order autoregressive (AR) model, called the AR estimator, is proposed. The sampled signal that contains information of both the Doppler signal and clutter is described by the second-order AR model with two poles. The mean frequency and variance of a unidirectional Doppler signal can be estimated, respectively, from the phase and the magnitude of the pole, with larger phase between the two poles. If the clutter is not completely rejected, all conventional estimators, including the autocorrelation (AC) estimator, result in erroneous estimations for the mean frequency and variance of the Doppler signal, whereas the AR estimator gives an accurate estimation. In the absence of clutter, however, the performance of both the AC and AR estimators are similar. If the blood flows in both directions in a sample volume and the clutter is rejected to the extent that it no longer obscures the Doppler signal, the proposed method can estimate simultaneously the mean frequencies and variances of both the forward and reverse blood flows. The performance of the proposed AR estimator was compared with that of the AC estimator by computer simulations and experiments, and it was found that when the number of available sampled data is small, the AR estimator does not require the use of a clutter filter, which simplifies Doppler signal detection.<> View full abstract»

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  • Planar-structure microscope-lens for simultaneous acoustic and optical imaging

    Publication Year: 1991 , Page(s): 183 - 187
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB)  

    A new type of combined acoustic and optical microscope lens with a planar structure is proposed. It can meet the demand for simultaneously obtaining both an acoustic image and its optical counterpart. The lens is composed by uniting a Fresnel-zone-type acoustic lens developed by the authors with a rod-type gradient-index optical lens (SELFOC). An acoustic beam is converged to a focal point in water by an acoustic planar lens that is composed of annular grooves formed on the end of the SELFOC rod. An optical beam, emitted by a He-Ne laser source and guided into the rod, converges due to the gradient of the refractive index and focuses on a spot in water. By designing the length of the rod properly, the focal spot of the optical beam is set to coincide with that of an acoustic beam. The design and fabrication of the lens are described, and results of some preliminary experiments for simultaneous observation of acoustic and optical images of the same portion of a specimen are shown.<> View full abstract»

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  • Characteristics of a hybrid transducer-type ultrasonic motor

    Publication Year: 1991 , Page(s): 188 - 193
    Cited by:  Papers (25)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (523 KB)  

    The hybrid transducer-type ultrasonic motor previously proposed by the authors (1989, 1991) uses two ultrasonic transducers to control the Lissajous figure at the contact surface of the stator. This motor is stable, even at low speed, and realizes a large output with a high efficiency due to the high controllability of the Lissajous figure. The experimental investigation of the characteristics of this hybrid transducer-type ultrasonic motor is presented. In addition, the maximum torque is roughly estimated by means of a simple model. The dependence of the diameter of the motor (transducer) on the maximum torque is discussed and demonstrated experimentally.<> View full abstract»

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  • A surface transverse wave-based MSK system

    Publication Year: 1991 , Page(s): 194 - 198
    Cited by:  Papers (4)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    A minimum-shift-keyed (MSK) system using one 1-GHz surface-transverse-wave (STW) resonator in the transmitter and two identical STW resonators in the receiver is described. It is shown to operate with data rates of over 100 kb/s and consume 150 mW. The system has a very high sensitivity and is tolerant to additive noise. Since the signal is never up- or down-converted. this system eliminates high power consumption. The system should find applications in cellular radios and in industrial communications.<> View full abstract»

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  • Motional capacitance of layered piezoelectric thickness-mode resonators

    Publication Year: 1991 , Page(s): 199 - 206
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    The Butterworth-Van Dyke equivalent circuit for description of the electrical behavior of piezoelectric bulk resonators is considered. The motional capacitance, C/sub 1/, in the circuit characterizes the strength of piezoelectric excitability of a vibration mode. For layered one-dimensional (1-D) structures this parameter can be calculated from the admittance given by the transfer matrix description of H. Nowotny and E. Benes (1987). Introducing the equivalent area of a vibration mode, the calculation is generalized for the three-dimensional (3-D) case of thickness-mode vibration amplitudes varying only slowly in the lateral directions. Detailed formulae are given for the case of singly rotated quartz crystals or ultrasonic transducers with additional layers on one or two sides. Good agreement of the calculated C/sub 1/ with experimental data is shown for mass-loaded planoconvex AT-cut quartz crystals.<> View full abstract»

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  • The feasibility of using electrically focused ultrasound arrays to induce deep hyperthermia via body cavities

    Publication Year: 1991 , Page(s): 207 - 219
    Cited by:  Papers (14)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1091 KB)  

    The results of a simulation study and subsequent experimental verification on the feasibility of using electrically focused arrays for intracavitary ultrasound hyperthermia are presented. The relative acoustic pressure fields from these cylindrical phased arrays were calculated for different dimensions and acoustic parameters to determine relevant design criteria. A thermal model based on the bioheat transfer equation was used to compute the resulting steady-state temperature distributions in tissue for various array configurations. This study has shown that cylindrical arrays of a practical size (75 mm long, 15 mm OD), resonating at 0.5 MHz with individual elements that are 1.5-mm wide, can preferentially heat regions that are between 20 and 50 mm from the surface of the array. In addition, it was shown that the temperature distribution can be further controlled by varying the focal position within the target volume, producing heated regions up to 40 mm wide. If practical constraints (i.e. number of amplifiers available or minimum element size attainable) become a limiting factor, arrays with wider elements would also be functional, but with certain restrictions applied to their flexible heating patterns. Thus, these electrically focused ultrasound arrays appear to offer a significant improvement over the existing intracavitary hyperthermia methods by producing a deeper and more controlled energy deposition.<> View full abstract»

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  • Arbitrarily oriented SAW gratings: network model and the coupling-of-modes description

    Publication Year: 1991 , Page(s): 220 - 230
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1015 KB)  

    A network model for surface-acoustic-wave (SAW) structures fabricated along arbitrary and hence nonsymmetric orientations, including natural single-phase unidirectional transducer (NSPUDT) directions, is described. From the predictions of this model for SAW gratings. the frequently used coupling of modes (COM) phenomenological description is evaluated. The network model consists of the usual sequence of mismatched transmission lines with susceptance loading at discontinuities to account for energy storage, plus a new additional reactive element calculated using a perturbation formula, to account for the asymmetry that exists for arbitrary orientations. The circuit elements are determined by geometrical and material parameters. It is demonstrated that the incremental COM description can be derived from the unit-cell-based network model, and analytical formulas quoted in the literature for the COM coefficients are compared with the values calculated from the ABCD network model description. An analytically tractable approximation for the network model is also described, from which rather simple explicit formulas for the COM coefficients that predict their dependence on material parameters and on frequency are derived. The analysis and numerical calculations indicate that these formulas may yield results that are valid over almost 30% relative bandwidths.<> View full abstract»

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  • On the tracking of resonance and antiresonance of a piezoelectric resonator

    Publication Year: 1991 , Page(s): 231 - 236
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (503 KB)  

    A quantitative analysis of the tracking of the zero-phase resonance frequency, f/sub r/, and antiresonance frequency, f/sub a/, of a piezoelectric resonator reported previously by the author (1990) is presented. Integral and integrodifferential equations for the system angular frequency omega (t) are derived, and numerical calculations are carried out for a model in which the voltage-controlled oscillator (VCO) is of first order and the phase angle of the piezoelectric resonator is represented by a single square-well function of omega . In order to confirm the plausibility of the model, the resulting omega (t) and VCO input waveforms and phase-plane trajectories are compared with the corresponding results for the exact phase angle function. Lock-in conditions and lock-acquisition time are expressed in terms of dimensionless quantities involving the difference between initial frequency and either of f/sub r/ or f/sub a/, the difference f/sub a/-f/sub r/, the loop gain, the VCO delay time constant, and the loop filter time constant. The results are consistent with the experimental data for a sample PZT resonator.<> View full abstract»

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  • Modelling the transverse-mode response of a two-port SAW resonator

    Publication Year: 1991 , Page(s): 237 - 242
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (501 KB)  

    An equation is derived for the transverse-mode frequencies of a two-port surface-acoustic-wave (SAW) resonator with uniform reflection gratings. It is postulated that only odd-order (symmetric) transverse modes should be excited in such a grating, due to its symmetrical placement with respect to the interdigital transducer (IDT). Frequency response modeling involves a summation of one-dimensional transmission-matrix computations for the fundamental mode and participating transverse ones. Excellent agreement is obtained between theory and experiment for a 360-MHz resonator with three close-in transverse modes, attributed to symmetric modes of odd order m=3, 5, 7.<> View full abstract»

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  • Efficient analysis tool for coupled-SAW-resonator filters

    Publication Year: 1991 , Page(s): 243 - 251
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (807 KB)  

    The advantages of the coupled-mode (COM) formalism and the transmission-matrix approach are combined in order to create exact and computationally efficient analysis and synthesis tools for the design of coupled surface acoustic wave resonator filters. The models for the filter components, in particular gratings, interdigital transducers (IDTs) and multistrip couplers (MSCs), are based on the COM approach that delivers closed-form expressions. To determine the pertinent COM parameters, the COM differential equations are solved and the solution is compared with analytically derived expressions from the transmission-matrix approach and the Green's function method. The most important second-order effects, such as energy storage, propagation loss, and mechanical and electrical loading, are fully taken into account. As an example, a two-pole, acoustically coupled resonator filter at 914.5 MHz on AT quartz is investigated. Excellent agreement between theory and measurement is found.<> View full abstract»

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  • A 200-kHz ultrasonic transducer coupled to the air with a radiating membrane

    Publication Year: 1991 , Page(s): 252 - 255
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB)  

    The development of a 200-kHz air ultrasonic transducer that consists of a piezoceramic disc and metal housing, the latter acting as a radiating membrane, is discussed. Theoretical analysis of the axially symmetric transducer structure is based upon the finite-element method. Calculations of the resonance frequencies, corresponding transducer deformations and input electrical admittance are performed using triangular ring elements with six degrees of freedom. Measured values on experimentally built transducers show good agreement with theory.<> View full abstract»

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  • The constituent equations of piezoelectric heterogeneous bimorphs

    Publication Year: 1991 , Page(s): 256 - 270
    Cited by:  Papers (73)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1128 KB)  

    The electromechanical characteristics of a heterogeneous piezoelectric bender subjected to various electrical and mechanical boundary conditions are discussed based on the results of the free bender analysis. The mechanical boundary conditions considered are: a mechanical moment at the end of the bender, a force applied perpendicularly to the tip of the bender, and a uniform load applied over the entire length of the bender. The constituent equations of the bender under these electromechanical influences are derived by calculating the internal energy assuming thermodynamic equilibrium.<> View full abstract»

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  • Piezoelectric beams and vibrating angular rate sensors

    Publication Year: 1991 , Page(s): 271 - 280
    Cited by:  Papers (9)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1061 KB)  

    A tuning fork angular rate sensor made out of a single piece of quartz has been studied. The piezoelectric effect is used both to excite a reference vibration in the plane of the tuning fork and to detect a vibration normal to this plane. The amplitude of the second vibration is directly proportional to the applied angular velocity. The structure is made rigid in order for it to survive in a harsh environment. This implies that the only vibrationally active areas are the tines of the tuning fork. The performance of the sensor is predicted with the help of a phenomenological piezoelectric beam theory. This theory shows that it suffices to study the two-dimensional (2-D) dielectric field in the cross-sections of the beams in order to obtain the values of the piezoelectric equivalent components. Estimates of these values can be obtained without the use of special computer programs. The predictions are shown to be in agreement with measurements.<> View full abstract»

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  • Hysteresis in quartz resonators-a review

    Publication Year: 1991 , Page(s): 281 - 290
    Cited by:  Papers (9)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1073 KB)  

    The literature on the frequency versus temperature characteristics of quartz crystal resonators is reviewed. Three papers that deal with frequency versus pressure hysteresis are included, as these may possibly have relevance to frequency versus temperature hysteresis. It is seen that the causes of hysteresis are not well understood. The evidence to date is inconclusive. The mechanisms that can cause hysteresis include: strain changes changes in the quartz, contamination redistribution, oscillator circuitry hysteresis, and apparent hysteresis due to thermal gradients. The results to date seem to indicate that lattice defects are somehow related to thermal hysteresis. Stress relief in the mounting structure can also produce significant hysteresis. As crystal processing techniques have improved. contamination has become less of a problem.<> View full abstract»

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  • Vibration of infinite piezoelectric cylinders with anisotropic properties using cylindrical finite elements

    Publication Year: 1991 , Page(s): 291 - 296
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    Natural frequencies for free vibration of infinite piezoelectric cylinders are computed using finite elements that are formulated in cylindrical coordinates. The finite-element method is used to model the cross-section of the cylinder in r, theta coordinates using circular sectors. Material constants that are functions of theta are allowed to vary in each circular sector and are computed using standard tensor transformations. The accuracy of the finite-element formulation is verified using previous results for isotropic cylinders and axisymmetric piezoelectric cylinders. New results are tabulated for frequencies of free vibration of solid and hollow piezoelectric cylinders of LiNbO/sub 3/ of crystal class 3m. Displacements for typical mode shapes are illustrated graphically.<> View full abstract»

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  • Acoustoionic interaction of SH surface waves with dilute ionic solutions

    Publication Year: 1991 , Page(s): 297 - 304
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (751 KB)  

    A theory describing the acoustoionic interaction of shear horizontal (SH) surface waves with viscous conductive ionic liquid is presented. A Green's function formulation that accounts for the acoustoelectric interaction with ions and dipoles in the solution is obtained for the surface potential in terms of the liquid and piezoelectric crystal parameters. For dilute ionic solutions, simple closed-form expressions for the velocity change and attenuation are obtained in terms of liquid conductivity and dielectric constant and the piezoelectric coupling coefficient. It is shown that SH surface waves in particular and acoustic waves in general can be used to perform microanalysis of dilute ionic solutions, detecting conductivity, dielectric constant, and relaxation frequency. The analysis, which was done for a simple crystal class, the hexagonal (6 mm), shows results which compare very well with exact numerical computations.<> View full abstract»

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  • Electrical reflection coefficient and velocity shift for groove gratings

    Publication Year: 1991 , Page(s): 305 - 310
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (517 KB)  

    The electrical reflection coefficient r/sub e/ and velocity shift ( Delta nu / nu )/sub e/ for grooves has never been formulated. All previous calculations for r/sub e/ and ( Delta nu / nu )/sub e/ have used formulas valid for the reflection of a surface acoustic wave (SAW) from an array of conducting strips. However, the discontinuity in electrical boundary conditions leading to these formulas does not exist in groove gratings. A new expression for the electrical reflection coefficient and velocity shift for some material overlays is derived from both the variational principle and perturbation theory. The results for various substrates are compared to show the agreement between the two approaches. The implications of this new formulation for the design of grooved arrays on various materials are discussed, effectively resolving the discrepancy between theory and experiment.<> View full abstract»

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  • On acoustic sensor sensitivity

    Publication Year: 1991
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB)  

    Acoustic sensor sensitivity expressed as frequency change per unit of measurand can result in the erroneous conclusion that higher-frequency sensors are superior to lower-frequency ones. It is argued that, when compared on the bases of reproducibility and resolution capability, good low-frequency sensors are superior to good high-frequency ones.<> View full abstract»

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  • An analysis of thin-rod flexural acoustic wave gravimetric sensors immersed in liquid

    Publication Year: 1991 , Page(s): 312 - 314
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (231 KB)  

    A perturbation analysis of acoustic wave propagation properties for a stiff thin rod surrounded by a liquid is presented. A study is made of the velocity sensitivity of the lowest flexural acoustic mode, F/sub 11/, along a thin rod due to mass changes in the rod and variations in the surrounding liquid density. It is shown that the presence of the liquid decreases the velocity of the F/sub 11/ mode and also the mass sensitivity.<> 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