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| 2. |
- van Deventer, Jan, et al.
(author)
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PSpice simulation of ultrasonic systems
- 2000
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-3010 .- 1525-8955. ; 47:4, s. 1014-1024
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Journal article (peer-reviewed)abstract
- The usage of electrical analogies for the simulation of wave generation and propagation in ultrasound transducers is well established. In this paper a PSpice approach that includes the temperature and frequency dependency of the transducer performance is proposed. The analogy between acoustic wave propagation and wave propagation in an electric transmission line is given. Further ways to deduce temperature and frequency dependencies are discussed. The simulation approach is applied to a pulse-echo setup for the determination of speed of sound and attenuation in liquids and solids. Experiments and simulations are made for three temperatures and in the frequency range 1-12 MHz using water, glycerine, and polymers (PMMA and PEEK) as test samples. Comparison shows a good agreement between simulation and experiments. Results for glycerine indicates that the available attenuation models for high viscosity liquids is inappropriate
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| 3. |
- van Deventer, Jan, et al.
(author)
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Thermostatic and dynamic performance of an ultrasonic density probe
- 2001
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-3010 .- 1525-8955. ; 48:3, s. 675-682
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Journal article (peer-reviewed)abstract
- The thermally static and dynamic performance of an ultrasonic density probe for liquids is investigated in the density range of 750 to 1300 kg/m3 at temperature ranging from 0 to 40°C. The single transducer probe uses a pulse echo technique to obtain the characteristic acoustic impedance of the liquid and, subsequently, the speed of sound through the liquid to obtain the density of the liquid. Variations in the initial sound amplitude are addressed by the design of a layered two material probe. It is shown that it is possible to obtain an accuracy of 0.4% in the experiments carried out. For changing temperature, the probe exhibits large errors because of problems in estimating the temperatures in certain regions of the probe
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| 5. |
- Jansson, Tomas, et al.
(author)
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Frequency dependence of speckle in continuous-wave ultrasound with implications for blood perfusion measurements.
- 2002
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010. ; 49:6, s. 715-725
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Journal article (peer-reviewed)abstract
- Speckle in continuous wave (CW) Doppler has previously been found to cause large variations in detected Doppler power in blood perfusion measurements, where a large number of blood vessels are present in the sample volume. This artifact can be suppressed by using a number of simultaneously transmitted frequencies and averaging the detected signals. To optimize the strategy, statistical properties of speckle in CW ultrasound need to be known. This paper presents analysis of the frequency separation necessary to obtain independent values of the received power for CW ultrasound using a simplified mathematical model for insonation of a static, lossless, statistically homogeneous, weakly scattering medium. Specifically, the autocovariance function for received power is derived, which functionally is the square of the (deterministic) autocorrelation function of the effective sample volumes produced by the transducer pair for varying frequencies, at least if a delta correlated medium is assumed. A marginal broadening of the modeled autocovariance functions is expected for insonation of blood. The theory is applicable to any transducer aperture, but has been experimentally verified here with 5-MHz, 6.35-mm circular transducers using an agar phantom containing small, randomly dispersed glass particles. A similar experimental verification of a transducer used in multiple-frequency blood perfusion measurements shows that the model proposed in this paper is plausible for explaining the decorrelation between different channels in such a measurement.
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| 6. |
- Thornell, G, et al.
(author)
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X-cut miniature tuning forks realized by ion track lithography
- 2000
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In: IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0885-3010. ; 47:1, s. 8-15
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Journal article (peer-reviewed)abstract
- With the recently developed ion track lithography based on the selective etching, widening, and merging of ion-induced defects collectively resembling a superimposed anisotropy in certain areas as defined by a stencil mask, 39-kHz x-cut miniature tuning f
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