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1993 Proceedings IEEE Ultrasonics Symposium

31 Oct-3 Nov 1993

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Displaying Results 1 - 25 of 260
  • The SAW characteristics of sputtered aluminum nitride on silicon

    Publication Year: 1993, Page(s):267 - 271 vol.1
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    Epitaxial aluminum nitride (AlN) films grown by chemical vapor deposition (CVD) on sapphire have been used to fabricate high frequency surface acoustic wave (SAW) resonators and filters with near theoretical performance capabilities. The required substrate temperature of above 1000°C is high and incompatible with a typical semiconductor IC processing. An alternative method for the preparation ... View full abstract»

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  • The acoustic properties of PECVD thin-film silicon carbide

    Publication Year: 1993, Page(s):273 - 275 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    The elastic constants of amorphous thin-film silicon carbide (SiC) deposited on gallium arsenide (GaAs) were determined using surface acoustic wave (SAW) techniques. The SiC was deposited by low-pressure plasma-enhanced chemical vapor deposition (PECVD) at a substrate temperature of 380°C on high resistivity (001) oriented GaAs. Film thicknesses of 197 nm and 422 nm were selected for the SAW m... View full abstract»

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  • 1.5 GHz SAW bandpass filter using poly-crystalline diamond

    Publication Year: 1993, Page(s):277 - 280 vol.1
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    Due to its high Young modulus, diamond has the highest acoustic wave velocity among all materials and thus it can be expected to be a candidate of the substrate for high frequency surface acoustic wave (SAW) devices. 15 μm thick poly-crystalline diamond deposited on a silicon substrate by hot-filament CVD was used as a substrate. For the piezoelectric material, ZnO film was deposited by RF sput... View full abstract»

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  • Elastic surface wave devices based on piezoelectric thick films

    Publication Year: 1993, Page(s):281 - 285 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    A study has been performed for the development of elastic-wave structures, involving screen printed and fired piezoelectric layers on non-piezoelectric substrates, intended for new families of thick film sensors. This study considers electroacoustic effects, i.e. the coupling between the electromechanical parameters of the layers and the elastic properties of the substrate, related to wave propaga... View full abstract»

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  • Time development of multiple polarization zones in PVDF

    Publication Year: 1993, Page(s):529 - 532 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (256 KB)

    The polarization distribution in PVDF which causes the piezo- and pyroelectricity of this polymer depends strongly on the polarization distribution. Applying an electric field of E=60 MV/m causes a ca. 10 μm thick polarization zone in the middle of the sample. Applying the same field in opposite direction a bimorph structure results. If the same field is applied to a homogeneously prepolarized ... View full abstract»

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  • Elastic properties of SnO2 films

    Publication Year: 1993, Page(s):811 - 814 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    SnO2 films have been recently used as reactive materials in gas sensors based on change of the electrical resistivity under gas exposure. In view of potential application of these films to surface acoustic waves (SAW) sensors, knowledge of their elastic properties is of current interest. We report here on results of the elastic characterization of SnO2 films, with thicknesses... View full abstract»

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  • Enhancement of sonochemical reactions by second harmonic superimposition

    Publication Year: 1993, Page(s):917 - 920 vol.2
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (256 KB)

    Effect of second-harmonic superimposition on cavitation and sonochemical reaction was investigated in a propagation mode by using a plane wave transducer piezoelectrically active at both fundamental and second-harmonic frequencies. The rate of iodine release induced by ultrasound at 1 MHz with a superimposed wave at 2 MHz showed significant dependence on the phase relation between the two waves. T... View full abstract»

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  • Large k2 and good temperature stability for SAW on new double-rotated cut of α-quartz with gold film

    Publication Year: 1993, Page(s):323 - 326 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (256 KB)

    LST-cut α-quartz offers good temperature stability and small propagation loss. It has been also observed that if thickness cannot be ignored compared with SAW wavelength, propagation loss increases. We investigated the relation between the rotation angles of LST-cut quartz and SAW propagation characteristics theoretically and experimentally. We found that if the thickness of Au film electrod... View full abstract»

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  • Control of second order temperature coefficient of SAW propagating in two thin film layers

    Publication Year: 1993, Page(s):287 - 290 vol.1
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (196 KB)

    This study proposes a new control method of the 1st- and 2nd-order temperature coefficients of two-layer substrate composed of ZnO and Ta 2O5 thin films which have the 2nd-order temperature coefficients of delay time with the signs opposite to each other. As a result, a stable SAW substrate of ZnO/Ta2O5 /fused quartz showing the 3rd-order characteristics... View full abstract»

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  • Evaluation of a pulse coding technique for speckle reduction and structure characterization

    Publication Year: 1993, Page(s):1175 - 1180 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (524 KB)

    Pulse coding techniques have been used in the past primarily to improve signal to (electronic) noise ratio. However, the flexibility inherent in pulse coding can be exploited to solve several problems in medical imaging and nondestructive testing. We have experimentally examined its potential for two such problems: (i) speckle reduction with multispectral imaging and data averaging; (ii) structura... View full abstract»

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  • Acoustic modes in 2-dimensional self-similar composite plates

    Publication Year: 1993, Page(s):533 - 536 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    We present the first experimental investigation of a Sierpinski carpet structure. This was constructed from piezoelectric square plates embedded in a polymer matrix according to a 4th generation Sierpinski carpet. The resonant frequencies and vibrational displacement patterns have been measured. Experimental evidence for the existence of localised modes, together with a simple model for... View full abstract»

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  • A Bayesian approach to ultrasound Doppler spectral analysis

    Publication Year: 1993, Page(s):1055 - 1058 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    In this paper, we address the problem of power spectral density estimation of stationary Gaussian processes with Auto-Regressive (AR) models when only a short set of data is available for analysis. The AR coefficients are estimated through a regularized method proposed by Kitagawa and Gersch (1984). We describe an experimental study of this method and a comparison with the classical least squares ... View full abstract»

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  • Photoacoustic signals from the ion-implanted layer of silicon substrate

    Publication Year: 1993, Page(s):815 - 818 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB)

    A nonradiative transition in ion-implanted and epitaxially grown layers on Si substrate were measured by a piezoelectric photoacoustic (PA) spectroscopy. It is considered that the observed peak at 1.07 eV is caused by a nonradiative recombination of optically excited electrons from boron acceptor levels. The decrease of the 1.07 eV peak intensity by ion implantation is considered to be due to a fo... View full abstract»

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  • Development of small antenna duplexer using SAW filters for handheld phones

    Publication Year: 1993, Page(s):111 - 114 vol.1
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    For smaller handheld telephones, we have developed a small antenna duplexer. This paper describes the fabrication and characteristics of our duplexer. Our package, which comprises two cavities and impedance control circuits with a strip line, has a multilayered structure. The package is made of glass-ceramic of size 7.5×8.5×2.5 mm3. The conductor patterns of the package are ... View full abstract»

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  • Free radical activity and enhancement of chemotherapy by low-level ultrasound

    Publication Year: 1993, Page(s):921 - 924 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    The mechanism of enhancement of chemotherapy by low-level ultrasound (US) (1.62 MHz tone burst, 10% duty cycle, 0.25 W/cm2 , 0.28 MPa, and 2.0 MHz center frequency pulsed, 8-cycle wave form, 1 KHz prf, 0.18 W/cm2, 1 MPa) was investigated with respect to free radical activity. The cytotoxicity of Adriamycin and diaziquone was enhanced by US; both these compounds by themselves ... View full abstract»

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  • Velocity and attenuation effects in acoustic wave chemical sensors

    Publication Year: 1993, Page(s):379 - 383 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB)

    A variety of chemical sensors have been developed using surface acoustic wave (SAW) devices coated with sorptive films. Chemical uptake into the coating results in a change in the coating's physical properties. Typically, only the velocity response is used and responses are interpreted gravimetrically. Polymers are commonly used as the sorptive coatings due to the ease of forming thin films and to... View full abstract»

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  • Lamb wave propagation in 128° Y-X lithium niobate plates

    Publication Year: 1993, Page(s):847 - 851 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    This paper is concerned with the propagation of ultrasonic Lamb waves along the X-direction of a 128° rotated Y-cut lithium niobate plate. In this material, it is found that one of the modes, the first higher-order antisymmetric mode (called the A1 mode), shows an unusual and interesting behavior. The velocity of this mode remains nearly constant for all values of h/λ, where ... View full abstract»

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  • Phased array slow shear TeO2 Bragg cells: design and performance

    Publication Year: 1993, Page(s):479 - 484 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (436 KB)

    The phased array transducer, when combined with the anisotropic Bragg interaction, provides a unique combination of features not available with the usual acoustical or optical rotation schemes used in the design of slow shear TeO2 Bragg cells. A general theory for a phased array Bragg interaction in a birefringent medium is applied to the design of a 60 MHz bandwidth, 50 μs time-aper... View full abstract»

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  • Partially air coupled through transmission ultrasonic inspection of large solid rocket motors

    Publication Year: 1993, Page(s):659 - 661 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    Through transmission ultrasonic inspection techniques have many advantages as a survey technique. When solid rocket motors are inspected it is highly desirable not to contact the propellant with the transducer for reasons involving safety, damage to the product, and speed of inspection. The development of air coupled ultrasonic inspection techniques for large solid rocket motors is discussed. The ... View full abstract»

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  • Speckle tracking in high frequency ultrasound images with application to intravascular imaging

    Publication Year: 1993, Page(s):889 - 892 vol.2
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    Speckle tracking calibration studies have been performed using a 42 MHz intravascular imaging probe in order to investigate the potential of correlation based speckle tracking techniques for detecting small differential displacements in intravascular ultrasound images. Serial images were acquired of a tissue phantom material subjected to incremental displacements produced by a two-axis motion stag... View full abstract»

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  • Approximate quantification of detected fractional blood volume and perfusion from 3-D color flow and Doppler power signal imaging

    Publication Year: 1993, Page(s):1023 - 1026 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Ultrasound systems have been quite limited in the degree to which they facilitate quantification of reasonably available detected mean tumor flow characteristics such as: detected fractional blood volume, B v; speed-weighted, detected fractional blood volume, Bvv and mean speed of regionally-detected blood flow, v¯. This lack of quantification follows from the relative ... View full abstract»

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  • Characteristics of leaky surface acoustic waves propagating along liquid/layered-substrates and their application to liquid sensor

    Publication Year: 1993, Page(s):355 - 358 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (212 KB)

    We propose SiO2 (fused silica)/(36°rot.Y-X)LiNbO 3 substrate for a viscosity sensor, in which the shear horizontal (SH) component becomes larger than that of the case without SiO2. For glycerin/SiO2 (40 μm)/LiNbO3 the loss due to the viscosity of glycerin is four times larger than that for glycerin/LiNbO3 (30 MHz). Moreover,... View full abstract»

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  • A time domain diffraction analysis for SAW transducers

    Publication Year: 1993, Page(s):161 - 166 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    A time domain diffraction analysis for surface acoustic wave (SAW) transducers was previously developed based on Huygen's principle. The analysis was performed using an approximation to the scalar two dimensional impulse response of an ideal point source which allowed for fast computation of diffraction effects in the time domain. Because the diffraction analysis was performed in the time domain a... View full abstract»

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  • A point source/point receiver method for ultrasonic testing

    Publication Year: 1993, Page(s):291 - 295 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (372 KB)

    Much of the theory and practice of ultrasonic testing involves the use of the plane wave approximation and of transducers large enough to generate planar wavefronts. Motivated in part by the emergence of engineering materials for which conventional techniques become impractical, the research reported here addresses the use of spherical waves generated by appropriately small transducers. Numerical ... View full abstract»

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  • Application of autoregressive spectral analysis for ultrasound attenuation: interest in highly attenuating medium

    Publication Year: 1993, Page(s):1181 - 1186 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    A second-order autoregressive (AR2) model, whose parameters are estimated with the Burg algorithm, is used to estimate the center-frequency along echo signals and its evolution versus depth. Data simulation of independent A-lines reflected by a homogeneous medium of scatterers are generated by a computer model with attenuation values ranging from 1 to 5 dB/cm MHz and an ultrasonic frequency of 5 M... View full abstract»

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