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JD Cheeke

Publications and source records attributed to JD Cheeke.

5 recordsLinked to original sources
PubMed2000

Measurement of the acoustic nonlinearity parameter in 1-alkanols

We present a harmonic generation method based on a pitch-catch experimental setup and the calculation of the corresponding nonlinear parameter in 1-alkanols, from methanol to 1-decanol. By focusing a 14 MHz ultrasonic toneburst through a spherical quartz lens in these alcohols, a second harmonic is produced and measured as a function of distance by a 28 MHz piezoelectric transducer placed near the focus. By extracting the point where the second harmonic power is at a maximum in each liquid, the corresponding nonlinear parameter is then computed with a model developed by Germain et al. The preliminary results from this experiment are in reasonable agreement with the values found in the literature for primary alcohols and support the idea that the nonlinear parameter is dependent on the chain structure.

Journal Article↗
PubMed2000

Simulation of electromechanical coupling coefficient by modified modal frequency spectrum method including the electrode effect

An approximate formula has been developed to determine the electromechanical coupling coefficient of the piezoelectric film in a four-layer composite resonator, which includes two electrodes. In this formula, the coupling coefficient can be calculated from the distribution of the effective coupling coefficients, k2eff, which are given by the modal frequency spectrum of the composite resonator. The feasibility of this method has been demonstrated with a ZnO/SiO2 composite resonator for different electrode thickness. The effect of mechanical propagation loss in both piezoelectric layer and substrate has also been studied.

Journal Article↗
PubMed2000

Dependence of single-bubble sonoluminescence on ambient pressure

Kondic et al.'s theory makes several specific predictions on the dependence of single-bubble sonoluminescence (SBSL) on ambient pressure. We have carried out experiments to verify these predictions for air bubbles in a water-glycerine mixture at about 17.5 kHz. The results show an increase in SBSL with reduced ambient pressure down to a critical value below which SBSL is extinguished. The results are all in good agreement with Kondic et al.'s theory and are also compatible with the dissociation hypothesis of Lohse et al.

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