The dynamic interplay between static and sliding friction is fundamental to many animal movements. One interesting example of stick-slip friction is found in the sound-producing apparatus of many spiny lobster species (Palinuridae). The acoustic movements of the spiny lobster's plectrum over the file are generated by stick-slip friction between the two surfaces. We examined the microscopic anat...

Geoacoustic inversion requires a generic knowledge of the frequency-dependence of compressional wave properties in marine sediments, the nature of which is still under debate. The use of in situ probes to measure sediment acoustic properties introduces a number of experimental difficulties that must be overcome. To this end, a series of wellconstrained in situ acoustic transmission experiments ...

The current study presents the results of the aerodynamic noise prediction of the flow field around a NACA 0012 airfoil at a chord-based Reynolds number of 100,000 and at 8.4 degree angle of attack. An incompressible Large Eddy Simulation (LES) turbulence model is applied to obtain the instantaneous turbulent flow field. The noise prediction is performed by the Ffowcs Williams and Hawkings (FW-...

Alginate beads are one of the most common vehicles for encapsulation. When designing bioartificial organs, they are used as matrix for cell culture. Cell survival and activity depend essentially on the bead physical and mechanical properties. Our objective is to study the feasibility of evaluating mechanical properties of millimetric beads using an ultrasound technique. We show that Lamé’s firs...

Underwater acoustic transducers often include a stack of thickness polarized piezoelectric material pieces of alternating polarity interspersed with electrodes and bonded together. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency, so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidt...

This paper presents the findings of a design, modeling, and fabrication study of ZnO and PbZr0 3Ti0 7O3 thin-film bulk acoustic resonators and filters. Measurements of the high-frequency responses of ZnO resonators having different area are used to develop an acoustic model that accurately represents resonator impedance data. The models are also used to interpret -parameter measurements on thin...

BACKGROUND This study describes a series of experimental work completed towards characterizing candidate materials for fabricating brain and muscle tissue mimicking phantoms. METHODS The acoustic speed, attenuation, impedance, thermal diffusivity, specific heat and thermal conductivity were measured. RESULTS The resulting brain (2% w/v agar-1.2% w/v Silica Dioxide-25%v/v evaporated milk) an...

Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause discrepancies between the measured value and the theoretical random incidence absorption coefficien...

The acoustic transmission coefficient of a resonant sonic crystal made of hollow bamboo rods is studied experimentally and theoretically. The plane wave expansion and multiple scattering theory (MST) are used to predict the bandgap in transmission coefficient of a non-resonant sonic crystal composed of rods without holes. The predicted results are validated against experimental data for the aco...