An acoustic target of constant density pt and variable index of refraction is imbedded in a surrounding acoustic fluid of constant density pa. A time harmonic wave propagating in the surrounding fluid is incident on the target. We consider two limiting cases of the target where the parameter e = pa/p, + 0 (the nearly rigid target) or E + ~0 (the nearly soft target). When the frequency of the in...

We analyze the geometry of Lagrangian motion and material barriers in a time-dependent, three-dimensional, Ekman-driven, rotating cylinder flow, which serves as an idealization for an isolated oceanic eddy and other overturning cells with cylindrical geometry in the ocean and atmosphere. The flow is forced at the top through an oscillating upper lid, and the response depends on the frequency an...

The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the a...

Pairs of unequal strength, counter-rotating vortices were produced in order to examine the inception, dynamics, and acoustic emission of cavitation bubbles in rapidly stretching vortices. The acoustic signatures of these cavitation bubbles were characterized during their inception, growth, and collapse. Growing and collapsing bubbles often produced a sharp, broadband, pop sound. The spectrum of...

power system overvoltages due to switching, lightning and other disturbances are the main problem for designers of the power transformers. once some frequencies of the incoming surges match with some of the natural frequencies of transformer winding, the resonance phenomenon is expected in transformer winding. the resonant overvoltages may destroy the insulation between turns and cause to insul...

In this work, we present a dual-band band-pass filter with fixed low-band resonant frequency and tunable high-band resonant frequency. The proposed filter consists of two split-ring resonators (SRRs) with a stub and microfluidic channels. The lower resonant frequency is determined by the length of the SRR alone, whereas the higher resonant frequency is determined by the lengths of the SRR and t...

above equation the first order formula for the resonant frequency of elliptical microstrip antenna on ferrite sub-strate is found to be (7) The effective permeability of the substrate is expressed as9 = (+ J , where C and D are a function of b/h. Similarly the effective permittivity is expressed as +*(I + 12h/b)-'j2 e, + I &e// = 2 2 which is also a function of b/h. Since b is not uniform throu...

Tympanograms for probes ranging from 250 through 2000 Hz were evaluated for 467 older adults. Measures of middle ear resonant frequency were compared across age groups (48-59, 60-69, 70-79, 80-90 years) and gender. No significant age group trends were observed for middle ear resonant frequency. Middle ear resonant frequencies were significantly higher for older women than for older men, but the...

Resonant modes and magnetoelectric performance of layered PZT/Ni and Ni/PZT/Ni cylindrical composites are considered. The first and the second resonant frequencies in the 1–150 kHz range correspond to the axial and the radial modes. Experimental results and theoretical analysis indicate that one should choose the trilayered structure and the first resonant frequency as the working frequency. Th...