Optimal behavior of viscoelastic flow at resonant frequencies

Optimal behavior of viscoelastic flow at resonant frequencies.

The global entropy generation rate in the zero-mean oscillatory flow of a Maxwell fluid in a pipe is analyzed with the aim of determining its behavior at resonant flow conditions. This quantity is calculated explicitly using the analytic expression for the velocity field and assuming isothermal conditions. The global entropy generation rate shows well-defined peaks at the resonant frequencies w...

Asymptotic Behavior of Linearized Viscoelastic Flow Problem

Estimation of -Factors and Resonant Frequencies

We estimate the quality factor and resonant frequency of a microwave cavity based on observations of a resonance curve on an equally spaced frequency grid. The observed resonance curve is the squared magnitude of an observed complex scattering parameter. We characterize the variance of the additive noise in the observed resonance curve parametrically. Based on this noise characterization, we es...

Heterodyne force microscopy of PMMA/rubber nanocomposites: nanomapping of viscoelastic response at ultrasonic frequencies

We present measurements of the nanoscale elastic and viscoelastic properties of samples of poly(methylmetacrylate) (PMMA)/rubber nanocomposites. For these studies we have used a new technique based on atomic force microscopy (AFM) with ultrasonic excitation, heterodyne force microscopy (HFM), which provides a means of testing the viscoelastic response of polymeric materials locally (in tip-prob...

Cellular muscle actuators with variable resonant frequencies

This paper presents the design and analysis of a novel variable stiffness and variable resonance actuator based on a cellular arrangement of piezoelectric devices. The cellular muscle actuator design concept is presented followed by a general dynamic model for establishing the theoretical bounds on achievable resonant frequencies. A model that is specific to the proposed design is then formulat...