Optimal design of savonius wind turbines using ensemble of surrogates and CFD analysis

Structural and Multidisciplinary Optimization - Current study presents fluid flow analysis using CFD and a surrogate based framework for design optimization of Savonius wind turbines. The CFD model...     

Effect of diesel soot on lubricant oil viscosity

Soot related lubricant oil thickening is a primary concern for heavy-duty diesel engines. Engines which produce a relatively low level of particulate matter in exhaust emissions show a significant level of soot contamination in the lubricant. This contamination results in lubricant breakdown. The soot contaminates the lubricant and changes the chemical properties resulting in the lubricant ceasing to perform its functions. This causes an increase in viscosity of the engine oil causing pumpability problems. Hence, it is necessary to study the effects of soot and lubricant oil additives and their interactions on engine oil viscosity.Statistically designed experiments were developed to study the effect of soot contamination on engine oil viscosity. The oil samples used for the study differed in the base stock, dispersant level, and Zinc Dithiophosphate (ZDP) level. These three variables were formulated at two levels: Low (−1) and High (1), which resulted in a 2³ matrix (8 oil blends). Soot was considered as a variable at three levels: low/0% weight (−1), medium/2% by weight (0), and high/4% by weight (1). This resulted in 24 oil samples, and soot at three levels helped in determining the non-linear effect of soot on oil viscosity.Experiments were conducted at 40 and 90 °C to study the effect of the various factors on viscosity with temperature variation. The results showed that viscosity of the oil samples increased with increase in soot at both 40 and 90 °C. The analysis indicated a nonlinear behavior of viscosity as the amount of soot increased at 40 °C, whereas a linear variation at 90 °C.The results obtained were analyzed using the general linear model (GLM) procedure of the statistical analysis system (SAS) package to determine the significance of variables on viscosity. The statistical analysis system also highlighted the significance of various interactions among the variables on viscosity. The statistical analysis results at 40 and 90 °C showed that the effect of base stock and ZDP levels were negligible at 40 °C, whereas the dispersant level and soot level influenced the viscosity of the oil samples at both temperatures.     

Age-Dependent Contributions of NMDA Receptors and L-Type Calcium Channels to Long-Term Depression in the Piriform Cortex

In the hippocampus, the contributions of N-methyl-D-aspartate receptors (NMDARs) and L-type calcium channels (LTCCs) to neuronal transmission and synaptic plasticity change with aging, underlying calcium dysregulation and cognitive dysfunction. However, the relative contributions of NMDARs and LTCCs in other learning encoding structures during aging are not known. The piriform cortex (PC) plays a significant role in odor associative memories, and like the hippocampus, exhibits forms of long-term synaptic plasticity. Here, we investigated the expression and contribution of NMDARs and LTCCs in long-term depression (LTD) of the PC associational fiber pathway in three cohorts of Sprague Dawley rats: neonatal (1–2 weeks), young adult (2–3 months) and aged (20–25 months). Using a combination of slice electrophysiology, Western blotting, fluorescent immunohistochemistry and confocal imaging, we observed a shift from an NMDAR to LTCC mediation of LTD in aged rats, despite no difference in the amount of LTD expression. These changes in plasticity are related to age-dependent differential receptor expression in the PC. LTCC Cav1.2 expression relative to postsynaptic density protein 95 is increased in the associational pathway of the aged PC layer Ib. Enhanced LTCC contribution in synaptic depression in the PC may contribute to altered olfactory function and learning with aging.