Ambient vibration test is one of the most applicable and reliable methods among vibration tests due to recently fast evolvement of measurement, sensor technologies and data processing, and economical benefit as well. Modal identification methods of the ambient vibration structures are output-only identification techniques which have commonly been branched into either the frequency domain or the...

Surface quality including surface roughness and edge chipping is a key process measure in micro ultrasonic machining (Micro-USM) as an efficient process for micromachining of hard and brittle materials. Process parameters such as ultrasonic vibration amplitude, static load, type of tool material, type and size of abrasive particles and slurry concentration can influence the surface quality. How...

This study deals with the vibration and stability analysis of double-graphene nanoribbon-system (DGNRS) based on different nonlocal elasticity theories such as Eringen's nonlocal, strain gradient, and modified couple stress within the framework of Rayleigh beam theory. In this system, two graphene nanoribbons (GNRs) are bonded by Pasternak medium which characterized by Winkler modulus and shear...

We present a quantum theory of nondegenerate phase-sensitive parametric amplification in a χ nonlinear medium. The non-zero response time of the Kerr (χ) nonlinearity determines the quantum-limited noise figure of χ parametric amplification, as well as the limit on quadrature squeezing. This non-zero response time of the nonlinearity requires coupling of the parametric process to a molecular-vi...

The dynamic characteristics and parametric instability of a rotating electrorheological ER sandwich beam with rotary oscillation are numerically analyzed. Assuming that the angular velocity of an ER sandwich beam varies harmonically, the dynamic equation of the rotating beam is first derived based on Hamilton’s principle. Then the coupling and nonlinear equation is discretized and solved by the...

Surface quality including surface roughness and edge chipping is a key process measure in micro ultrasonic machining (Micro-USM) as an efficient process for micromachining of hard and brittle materials. Process parameters such as ultrasonic vibration amplitude, static load, type of tool material, type and size of abrasive particles and slurry concentration can influence the surface quality. How...

A computational study of helicopter vibration and rotor shaft power reduction is conducted using activelycontrolled trailing-edge flaps (acfs), implemented in single and dual flap configurations. Simultaneous vibration reduction and performance enhancement is demonstrated under level flight condition at high advance ratios, where dynamic stall effects are significant. Power reduction is achieve...

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonl...