Cylindrical Acoustic Gas Thermometry

Acoustic gas thermometry

We review the principles, techniques and results from primary acoustic gas thermometry (AGT). Since the establishment of ITS-90, the International Temperature Scale of 1990, spherical and quasi-spherical cavity resonators have been used to realize primary AGT in the temperature range 7 K to 552 K. Throughout the sub-range 90 K < T < 384 K, at least two laboratories measured (T − T90). (Here T i...

Acoustic Heating and Thermometry in Microfluidic Channels

This paper presents the results of the work performed in establishing closed loop temperature control of fluids in microfluidic channels. Acoustic energy is used to introduce heat into localized regions of‘ the channel. The temperature of the fluid in these regions is determined by using the relationship between the attenuation and speed of sound propagating in the fluid with temperahue. The ab...

Acoustic phonon engineering in coated cylindrical nanowires

We have theoretically investigated the effect of a coating made of the elastically dissimilar material on the acoustic phonon properties of semiconductor nanowires. It is shown that the acoustic impedance mismatch at the interface between the nanowire and the barrier coating affects dramatically the phonon spectra and group velocities in the nanowires. Coatings made of materials with a small so...

Waveguide Simulation of Non-Cylindrical Acoustic Tubes

Rotational acoustic resonances in cylindrical waveguides

An investigation is made into the existence of rotational acoustic resonances in a circular cylindrical waveguide, and their frequencies of oscillation are calculated numerically. The guide is assumed to contain a number of radial fins which have finite extent, and which are distributed at equal azimuthal angles around the guide. A variational principle is used to prove the existence of differe...