نتایج جستجو برای: ultrasonic oscillations
تعداد نتایج: 76188 فیلتر نتایج به سال:
In this paper, we study the oscillation of nonlinear fractional nabla difference equations of the form [Formula: see text]where c and α are constants, [Formula: see text] is the Riemann-Liouville fractional nabla difference operator of order [Formula: see text] is a real number, and [Formula: see text]. Some sufficient conditions for oscillation are established.
Shear wave elasticity imaging (SWEI) is a new approach to imaging and characterizing tissue structures based on the use of shear acoustic waves remotely induced by the radiation force of a focused ultrasonic beam. SWEI provides the physician with a virtual "finger" to probe the elasticity of the internal regions of the body. In SWEI, compared to other approaches in elasticity imaging, the induc...
We consider a class of second-order Emden-Fowler equations with positive and nonpositve neutral coefficients. By using the Riccati transformation and inequalities, several oscillation and asymptotic results are established. Some examples are given to illustrate the main results.
We present some new criteria for the oscillation of even order dynamic equation[Formula: see text]on time scale T, where α is the ratio of positive odd integers a and q is a real valued positive rd-continuous functions defined on T.
A scanning probe microscope methodology, called resonant difference-frequency atomic force ultrasonic microscopy RDF-AFUM , has been developed. It employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope, driven at a frequency differing from the ultrasonic frequency by one of the contact resonance frequencies of the cantilever, engages t...
This paper describes the design, modelling and simulation of an acoustic microsystem in a pulse-echo ultrasonic application. The microsystem, used as emitter and receiver of ultrasonic signals, consists of a bulk micromachined suspended membrane. During emission, the membrane is placed in an oscillator loop and is thermally actuated at its resonance frequency (≈ 40 kHz). This frequency is sligh...
An air bubble driven by ultrasound can become shape-unstable through a parametric instability. We report time-resolved optical observations of shape oscillations (mode n=2 to 6) of micron-sized single air bubbles. The observed mode number n was found to be linearly related to the ambient radius of the bubble. Above the critical driving pressure threshold for shape oscillations, which is minimal...
Eric Yeatman Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, United Kingdom We propose a new way to deliver power to biomedical implants in order to address the higher energy requirements of microsystems with actuation functions such as drug release or mechanical adj...
This paper describes the interferometric methodology for determining the speed of ultrasonic wave’s propagation in a magnetic fluid. The technique uses acoustomagnetic effect, which can be observed in a magnetized magnetic fluid, when elastic oscillations inside it. We describe the experimental setup and the measurement technique in detail. We determined the speed of ultrasonic waves propagatio...
We have previously introduced an ultrasonic imaging approach that combines harmonic-sensitive pulse sequences with a post-beamforming quadratic kernel derived from a second-order Volterra filter (SOVF). This approach is designed to produce images with high sensitivity to nonlinear oscillations from microbubble ultrasound contrast agents (UCA) while maintaining high levels of noise rejection. In...
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