Influence of the position of InGaAs quantum dot array on the spectral characteristics of AlGaAs/GaAs photovoltaic converters

Results of a comparative study of the internal quantum yield of AlGaAs/GaAs photovoltaic converters (PVCs) with variable position of the array of vertically coupled InGaAs quantum dots (QDs) are presented. It is established that the QD array placed immediately at the i-region/base interface does not change the PVC sensitivity compared to that for QDs arranged inside the i-region of the p-n junction. However, the QD array shifted to the base or the back potential barrier decreases the contribution of a base layer to the PVC photocurrent and reduces the photosensitivity of the QD-based medium.     

Turbulent flow of a chemically reactive gas suspension in a channel with a blow

The influence of the chemical reactions occurring in the gas phase of a gas suspension flowing in a channel with penetrable walls and the combustion of the condensed-impurity particles in this flow on its gasdynamic structure has been investigated. It is shown that the order of the system of equations defining a flow of a chemically reactive gas suspension with a homogeneous exothermic reaction proceeding at a definite rate and a heterogeneous combustion of the condensed-phase particles can be decreased if certain assumptions are mode. The distributions of the parameters of the gas and dispersed phases were calculated as functions of the rate of blow and the sizes of the particles. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 91–98, July–August, 2007.     

Respirometric Assessment of Primary Sludge Fermentation Products

This study investigates the potential of primary sludge fermentation for the generation of readily biodegradable substrate. Experimental evaluation indicates that uncontrolled fermentation converted 22% of the initial volatile suspended solids in the sludge into soluble biodegradable chemical oxygen demand (COD). More than 85% of the soluble COD generated was associated with the formation of short chain volatile fatty acids (VFAs). The recoverable fraction of the fermented sludge supernatant may potentially increase the biodegradable COD content of the primary effluent by 5%. The VFA composition predominantly involved acetic and propionic acids as reported in the literature. Due to the high VFA content, activated sludge Model No. 1 could not predict the COD fractionation in the primary sludge; activated sludge Model No. 3 provided a better interpretation of the oxygen uptake profile through initial storage of the VFAs in the sludge.     

Investigation into the froth flotation and selection of reagents on the basis of the mechanism of their action report 2. A comparison of flotation properties of millimeter,micrometer, and nanometer bubbles based on equations of capillary physics (Part Two)

The influence of the capillary pressure P _ca of gas in microbubbles on bubble spread over a substrate (particle) after adhesion is considered (for bubbles ranging in size from 2 mm to 20 nm). The dimensionless parameter K _a characterizes the microbubble spread with decrease in the bubble form factor β by no more than 0.000001 of its initial value. There is a clear symbatic relation between P _ca and K _a. The microbubble begins to spread when it measures 200 μm; its motion increases markedly as it becomes smaller. With decrease in bubble size, the rock and slurry particles adhering to its surface are removed. Of course, this enhances the foam quality.     

Effect of nanosphere size on the luminescence of synthetic opal

We have studied the effect of the stop band and coupled photonic modes on the visible luminescence of synthetic opal photonic crystals. The results demonstrate that the position of the photonic stop band in the luminescence spectrum of opal depends on the nanosphere diameter. Optical measurements have been used to determine the refractive index of the photonic crystals and the silica sphere diameter. We have assessed the effect of coupled modes in opal on its intrinsic luminescence spectrum. Coupled modes of visible light in opal can be visualized by applying a matte sapphire plate to the opal surface.     

Measurement of forming trajectories during drilling

Results are provided for an experimental study of forming trajectories during drilling and the effect on them of cutting speed and drilling depth. __________ Translated from Izmeritel’naya Tekhnika, No. 8, pp. 31–33, August, 2006.