Analysis of regular and irregular acoustic streaming patterns in a rectangular enclosure

This study reports an experimental investigation of the non-linear phenomena of regular (classical) and irregular streaming patterns generated in an air-filled rigid-walled square channel subjected to the acoustic standing waves of different frequencies and intensities. The interaction of acoustic waves and thermoviscous fluids is responsible for these phenomena. The resonator’s walls are maintained at isothermal condition. Synchronized particle image velocimetry (PIV) technique has been used to measure the streaming velocity fields. The experimental results show that at a given excitation frequency, regular streaming flow patterns are observed up to a certain value of the excitation amplitude. As the amplitude increases beyond this limit, the regular streaming is distorted to an irregular flow structure. The regular and irregular streaming are classified in terms of streaming Reynolds number . It is found that for Re_s2<50, classical streaming flow patterns are established and then deform to irregular and complex shapes as Re_s2 exceeds 50.     

A Promising Material for Selective Sensing Biomarker Gas Molecules

Russian Journal of Physical Chemistry A - The interaction of many biomarker gas molecules on pure, AlB-doped and GaB-doped boron nitride nanotube was studied by the density functional theory method...     

Analytical solution of the quasi-static thermoelasticity problem in a pressurized thick-walled cylinder subjected to transient thermal loading

Thermoelasticity problem in a thick-walled cylinder is solved analytically using the finite Hankel transform. Time-dependent thermal boundary conditions are assumed to act on the inner surface of the cylinder. For the mechanical boundary conditions two different cases are assumed: Traction–displacement problem (traction is prescribed on the inner surface and the fixed displacement boundary condition on the outer one) and Traction–Traction problem (tractions are prescribed on both the inner and outer surfaces of the hollow cylinder). The quasi-static solution of the thermoelasticity problem is derived analytically, i.e., the transient thermal response of the cylinder is derived and then, quasi-static structural problem is solved and closed form relations are extracted for the thermal stresses in the two problems. The results show to be in accordance with that cited in the literature in the special cases.     

Smart Phase Tuning in Microwave Photonic Integrated Circuits Toward Automated Frequency Multiplication by Design

The author investigates the monitoring methods for fine adjustment of the previously proposed on-chip architecture for frequency multiplication and translation of harmonics by design. Digital signal processing (DSP) algorithms are utilized to create an optimized microwave photonic integrated circuit functionality toward automated frequency multiplication. The implemented DSP algorithms are formed on discrete Fourier transform and optimization-based algorithms (Greedy and gradient-based algorithms), which are analytically derived and numerically compared based on the accuracy and speed of convergence criteria.     

Surface Chemistry of Nanometric Ceria Particles in Aqueous Dispersions

The oxide/water interface of nanometric ceria particles has been studied through titration of the surface sites. The adsorption and desorption of protons, hydroxyls, and anions have been measured through potentiometry and chemical analysis. It has been found that these processes cause reactions between surfaces. Conversely, the loss of reactive surfaces which results from chemical treatments changes the charge behavior of the dispersions and reduces it to that of the pure fired oxide.     

Circulant weighing matrices of weight 22t

A weighing matrix of weight k is a square matrix M with entries 0, ± 1 such that MM ^T = kI _n . We study the case that M is a circulant and k = 2^2t for some positive integer t. New structural results are obtained. Based on these results, we make a complete computer search for all circulant weighing matrices of order 16.