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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 3 • Date May 1989

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Displaying Results 1 - 15 of 15
  • The power reflected in a SAW RAC

    Page(s): 297 - 299
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (291 KB)  

    Considerations relating to the design of surface-acoustic-wave (SAW) reflective array pulse compressors (RACS), including the effect of array width on power reflected, the transmitted beam profile and the effect of randomized arrays, are discussed. Only a first-order analysis is used. Potential misunderstandings of these issues that could arise from the existing literature are clarified.<> View full abstract»

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  • Continuous-wave surface-acoustic-wave delay-difference device

    Page(s): 300 - 306
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    A novel surface-acoustic-wave (SAW) device for continuous-wave (CW) delay-difference measurement or wideband interference-rejection at VHF frequencies is described and test results are given. The delay-difference device (DDD) operates at a center frequency of 160 MHz with a 31-MHz bandwidth over which root-mean-square amplitude ripple is 0.13 dB and need not be operated in a gated mode. A pair of input signals to the CW DDD may be at any frequency within the bandwidth of the DDD, modulated in any form, and even amplitude unbalanced to some degree by system amplifiers and still the CW DDD and its associated electronics will accurately measure the relative delay of the signals and interpret that as direction of arrival or phase as desired. Used in an interference cancelling mode the device tested shows an average 25-dB signal rejection over its 31-MHz bandwidth.<> View full abstract»

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  • High K BaTiO/sub 3/ films from metalloorganic precursors

    Page(s): 307 - 312
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    Crack-free and dense BaTiO/sub 3/ films 4 to 8 mu m thick were prepared by spinning a solution of metalloorganic precursors onto an appropriate substrate, and firing and annealing the film in air at certain temperatures to obtain appropriate grain sizes. The electrical properties of the films were studied as a function of grain size, temperature, frequency, and DC bias. Films with a grain size of 0.2 mu m showed ferroelectric properties similar to bulk BaTiO/sub 3/.<> View full abstract»

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  • Ultrasound transducer models for piezoelectric polymer films

    Page(s): 313 - 318
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    A method is presented for determining the piezoelectric constants and the frequency-dependent dielectric properties of the polymers from a five-step algorithm based on analysis of air-loaded broadband impedance measurements. It is shown how to account for the frequency-dependent lossy properties of these films in an equivalent impedance circuit model and a modified Mason's model. Comparisons between the models and actual film transducers show excellent broadband simulation of both electrical input impedance and ultrasonic pulse-echo performance.<> View full abstract»

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  • Analysis of a multielement ultrasound hyperthermia applicator

    Page(s): 319 - 325
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    An unfocused multielement ultrasound applicator was developed for hyperthermia treatment of superficial tumors. The applicator contains sixteen 3.8-cm/sup 2/ individually controllable elements on a 15.2-cm/sup 2/ piezoelectric ceramic plate. The acoustical power output of each element can be independently applied to facilitate uniform heating throughout the treatment area while minimizing undesired heating in normal tissues. The performance of the applicator was examined by measuring acoustical power output and beam profiles. The results of this analysis indicated that the applicator is capable of producing required therapeutic output levels with excellent localization and control of the power deposition.<> View full abstract»

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  • An acoustic micrometer and its application to layer thickness measurements

    Page(s): 326 - 331
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    The principle and system of the acoustic micrometer are described. Its basic performance, with respect to the stability, accuracy, spatial resolution, and temperature dependence, is also discussed. Gold layers electroplated on substrates of 42% Ni-Fe alloy were taken as test specimens in the present study. The measurable range of the thickness for gold layers covered from 1 to 20 mu m when a frequency range of 10-200 MHz was used. Stability and accuracy were achieved to within +or-0.2% and +or-1%, respectively.<> View full abstract»

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  • The use of metallic glass scroll as an acoustic transducer element

    Page(s): 332 - 336
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    A study was made of the piezomagnetic and elastic properties of scrolls of Metglas 2605 SC, used as an acoustic transducer element. This study involved quasi-DC magnetic induction measurements and ultrasonic complex plane analysis of scrolls of various annealing histories. An optimum effective magnetomechanical coupling coefficient. K/sub eff/, of 0.75, was found. The best magnetomechanical response in air obtained for metallic glass scroll during the study was for the unconsolidated case. However, preliminary experiments have shown that structural weakness and corrosion problems are significant when using the unconsolidated scrolls in water.<> View full abstract»

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  • Design and implementation of mixed-mode transducers

    Page(s): 337 - 341
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (465 KB)  

    In order to design a mixed-mode transducer with high efficiency and broad bandwidth for both longitudinal and shear wave modes, a theory is developed to determine the properties of this transducer with arbitrary acoustic loads at both ends of the piezoelectric element. Several Y-cut lithium niobate (LiNbO/sub 3/) transducers were made on both [110] single-crystal bismuth germanium oxide (Bi/sub 12/GeO/sub 20/) and fused quartz. The piezoelectric plates were attached to indium bonding and later polished to operate in the 100-MHz frequency range. The experimental data of round-trip insertion loss for both longitudinal and shear modes showed an excellent agreement with theoretical predictions.<> View full abstract»

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  • A comparative study of analytical and numerical transient force excitations on an elastic half-space

    Page(s): 342 - 350
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    The numerical modeling of ultrasonic wave propagation in elastic solids is discussed for nondestructive testing applications because of the relative ease with which the boundaries of realistic defect shapes and testing geometries can be handled. Two-dimensional (2-D) finite-element code has been developed for this purpose yielding good qualitative agreement between numerical predictions and experimental measurements. However, as a major step n the development of a full three-dimensional formulation, the 2-D code requires some quantitative form of validation. Here a direct transient comparison of analytical and numerical predictions of ultrasonic wave propagation in an elastic half-space is given that clearly validates the 2-D numerical code quantitatively and provides a useful theoretical benchmark against which future numerical codes can be evaluated.<> View full abstract»

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  • Orientation of doubly rotated quartz plates

    Page(s): 351 - 355
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    A derivation from classical spherical trigonometry of equations to compute the orientation of doubly-rotated quartz blanks from Bragg X-ray data is discussed. These are usually derived by compact and efficient vector methods, which are reviewed briefly. They are solved by generating a quadratic equation with numerical coefficients. Two methods exist for performing the computation from measurements against two planes: a direct solution by a quadratic equation and a process of convergent iteration. Both have a spurious solution. Measurement against three lattice planes yields a set of three linear equations the solution of which is an unambiguous result.<> View full abstract»

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  • A theoretical approach for inverse filter design in ultrasonic applications

    Page(s): 356 - 364
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (657 KB)  

    A comparison between simulation- and measurement-based characterization is provided for the design of one-dimensional, nonadaptive, inverse filters for ultrasonic applications. Both prefiltering and postfiltering are considered by means of two different filtering strategies performed in the time and frequency domains. The results clearly indicate that theoretical methods can be used successfully, provided that the physical limitations of the simulation process are fully appreciated. In some instances, the simulation-based approach is shown to provide superior results, and the reasons for this are explained.<> View full abstract»

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  • Analysis of homomorphic processing for ultrasonic grain signal characterization

    Page(s): 365 - 375
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    A model for the grain signal is presented, which includes the effect of frequency-dependent scattering and attenuation. This model predicts that the expected frequency increases with scattering and decreases with attenuation. Homomorphic processing was used for spectral smoothing, and the selection of parameters for optimal performance was examined. Experimental results are presented that show both the upward shift in the expected frequency with grain boundary scattering and the downward shift with attenuation. Furthermore, it is shown that the expected frequency shift can be correlated with the grain size of the material. It is important to point out that the quantitative relationship between the average grain size and the expected frequency shift (either upward or downward) is dependent on the type of material, the quality of grain boundaries, and the characteristics of the measuring instruments.<> View full abstract»

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  • Ultrasound holographic B-scan imaging

    Page(s): 376 - 383
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (852 KB)  

    An ultrasound holographic B-scan (UHB) imaging apparatus comprising a minicomputer system, a data acquisition unit, and a special 64-element UHB transducer has been developed. Simulation studies and real experiments with a tissue-equivalent phantom show that lateral and longitudinal resolution (-6 dB) of about 1 mm was achieved in the entire image. Furthermore, results from clinical evaluation, including diagnostic and neurosurgical imaging, suggest that the UHB imaging method is operational and has some special advantages in patient diagnosis. Theoretically, the addition of phase information to the ultrasound images can result in enhanced tissue characterization, which is extremely important in tumor diagnosis and treatment.<> View full abstract»

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  • Multidepth synthetic aperture processing of ultrasonic data

    Page(s): 384 - 385
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    The characterization of the size, shape, and location of subsurface discontinuities in metals using multidepth synthetic aperture processing of ultrasonic data is considered. A technique is proposed to increase the lateral resolution and signal-to-noise ratio when metals of large thickness are tested. The first technique to achieve multidepth was dynamic focusing. The aperture in the proposed technique is simultaneously focused at several depths by means of a computer program, thus avoiding the fixed hardware required in the dynamic focusing technique. Experimental evidence is presented to indicate the improvement in resolution, due to multidepth processing, over the single-focus technique.<> View full abstract»

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  • Addendum to 'Possible design procedure for low-loss 180 degrees reflecting arrays in SAW devices' (Jan 88 57-60)

    Page(s): 385 - 386
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (146 KB)  

    The original paper (ibid., vol.35, no.1, p.57-60, 1988) describes how multiple reflections can be allowed for in SAW reflecting arrays. Comments are now made on the error in frequency response due to truncation of the array to finite length, and on multiple transits between transducers via the array.<> 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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Meet Our Editors

Editor-in-Chief
Steven Freear
s.freear@leeds.ac.uk