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The present work deals with a comparative study concerning the combined influence of ER fluid lubrication and surface texturing on the performance of two-lobe/circular non-recessed hybrid journal bearings compensated with various types of flow control devices respectively. In order to describe the behavior of electro-rheological lubricant, Continuous Bingham model has been used. Further, the solution of modified Reynolds equation has been obtained with the help of FEM approach. The comparative study revealed that the ER fluid lubricated CFV compensated two-lobe (δ = 1.1) non-recessed journal bearings gives superior performance vis-à-vis other compensating elements like capillary, orifice and slot-entry. Besides this, it has been noticed that the textured non-recessed journal bearings (two-lobe/circular) improves the bearing performance significantly for capillary, orifice and slot-entry restrictor except CFV restrictor. The numerically simulated results presented in this paper may help in proper selection of restrictor, lubricant and bearing configuration so as to get the desired performance. [ABSTRACT FROM AUTHOR]

In the present work, a comparative study between textured surface and non-textured surface non-recessed hybrid journal bearing configurations is presented. To obtain the performance characteristics parameters of non-recessed hybrid journal bearing, the Reynolds equation, which governs the flow of lubricant in the clearance space, is solved using FEM and the performance parameters are computed. The shear stress–strain relation of lubricant is modeled with the help of a power-law fluid model. The numerically simulated results show that the textured non-recessed hybrid journal bearing provides improved stability parameter than that of journal bearing with non-texturing. [ABSTRACT FROM AUTHOR]

Abstract: Fluoride is a common contaminant in a variety of industrial wastewaters. Available information on the potential toxicity of fluoride to microorganisms implicated in biological wastewater treatment is very limited. The objective of this study was to evaluate the inhibitory effect of fluoride towards the main microbial populations responsible for the removal of organic constituents and nutrients in wastewater treatment processes. The results of short-term batch bioassays indicated that the toxicity of sodium fluoride varied widely depending on the microbial population. Anaerobic microorganisms involved in various metabolic steps of anaerobic digestion processes were found to be very sensitive to the presence of fluoride. The concentrations of fluoride causing 50% metabolic inhibition (IC50) of propionate- and butyrate-degrading microorganisms as well as mesophilic and thermophilic acetate-utilizing methanogens ranged from 18 to 43mg/L. Fluoride was also inhibitory to nitrification, albeit at relatively high levels (IC50 =149mg/L). Nitrifying bacteria appeared to adapt rapidly to fluoride, and a near complete recovery of their metabolic activity was observed after only 4d of exposure to high fluoride levels (up to 500mg/L). All other microbial populations evaluated in this study, i.e., glucose fermenters, aerobic glucose-degrading heterotrophs, denitrifying bacteria, and H2-utilizing methanogens, tolerated fluoride at very high concentrations (>500mg/L). [Copyright &y& Elsevier]