Thermal analysis of square pipes in a reactor vault

To find the effective thermal conductivity between concrete block and square pipe and to study the temperature variations in the concrete section of reactor vault. The experiments were conducted and analysed with the numerical results by using Computational fluid dynamics. The thermal conductivity is to be founded experimentally and numerically and is compared with the actual thermal conductivity of the concrete. With the help of thermal conductivity value for various grade cement with various mixtures, suitable grade concrete is selected for the Reactor Vault cooling system.     

Computational investigation on secondary flows in a linear turbine cascade with tapered dual fence

The focus of the present work is to minimize the secondary flow losses inside a linear turbine cascade by means of a novel design of streamwise dual fence. The leading edge and trailing edge of the fences have been modified so as to reduce the total pressure loss coefficient in the passage. The study has been carried out computationally based on RANS simulations with SST turbulence model. Numerous simulations have been undertaken with single fence and dual fence models and compared with the base case model. The dual fence model with tapered trailing edge exhibits significant loss reduction compared to the base case. A suitable fence height ratio (FHR) has been identified for the dual fence model. The FHR = 2 configuration reduces the secondary flow kinetic energy by 78 % within the blade passage and it reduces the exit angle deviation significantly throughout the span. Detailed flow field analysis has been carried out to understand the physical mechanism behind the loss reduction with dual fence models. It is observed that fence-1 breaks the pressure side leg of the horse shoe vortex at the beginning of their formation itself. The radial penetration of the suction side leg of the horse shoe vortex is restrained by fence-2. These combined effects prevent the formation and mixing of two prominent loss core regions thereby avoiding the accumulation of low energy fluid near the suction side of blade.

     

The effect of professor ethnicity and gender on student evaluations: Judged before met.

Ethnic minority academicians face a number of challenges in the “ivory tower.” One set of challenges arises from the racial stereotypes that others hold, and the current research investigates the stereotypes held by students before they even meet such professors. After providing college preparatory students with a CV of a professor (differing in their race—White, Black, or Asian; their gender—male or female; and their academic discipline—Science or Humanities), students evaluated the professor on measures of competence, legitimacy, and interpersonal skills. We found that students evaluated Black professors to be significantly less competent and legitimate than their White and Asian counterparts. Both Black and Asian professors were judged to have significantly less interpersonal skills than White professors. No gender main effects emerged. Professors in science were judged to be more competent and legitimate than professors in humanities. Very few interactions surfaced. We discuss our results in terms of previous stereotype research and the implications our results have for further compounding the challenges that Black professors face in academia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanoscale effects leading to non-Einstein-like decrease in viscosity

Nanoparticles have been shown to influence mechanical properties; however, transport properties such as viscosity have not been adequately studied. This might be due to the common observation that particle addition to liquids produces an increase in viscosity, even in polymeric liquids, as predicted by Einstein nearly a century ago. But confinement and surface effects provided by nanoparticles have been shown to produce conformational changes to polymer molecules, so it is expected that nanoparticles will affect the macroscopic viscosity. To minimize extraneous enthalpic or other effects, we blended organic nanoparticles, synthesized by intramolecular crosslinking of single polystyrene chains, with linear polystyrene macromolecules. Remarkably, the blend viscosity was found to decrease and scale with the change in free volume introduced by the nanoparticles and not with the decrease in entanglement. Indeed, the entanglements did not seem to be affected at all, suggesting unusual polymer dynamics.     

Role of Cerium on Transformation Kinetics and Mechanical Properties of Low Carbon Steels

Metallurgical and Materials Transactions A - The present study has focused on the detailed dilatometric and electron microscopic analysis of the formation of austenite and its decomposition in two...     

Role of Cerium on the Intricacies of Deformed State and Softening Mechanisms of Low-Carbon Steels

The present study investigates the softening kinetics of two cerium (Ce)-modified steels after 60% cold rolling and annealing at 600 °C for 2–16 h. Cold rolling accumulates substantial strain in the ferritic matrix of low Ce (LCe) steel (0.03 wt% Ce) compared to high Ce (HCe) steel (0.6 wt% Ce). The acicular ferrite and Fe₃C partition the imposed strain preferentially inside the ferrite matrix of LCe sample. Contrarily, a homogenous strain distribution in HCe sample is promoted by soft Ce₂O₃ particles embedded in ferrite. Both the steels achieve partial recovery and recrystallization even after 16 h of annealing. LCe steel experiences a softening fraction of ≈28 vol% after 16 h, inferior to HCe steel (≈34 vol%). During initial stage of annealing, nucleation of strain-free grains are observed in LCe sample due to availability of grain and interphase boundaries. Subsequently, recrystallization kinetics get delayed because of the pinning effect exerted by fine CeO₂ and Fe₃C particles. In HCe samples, the early stage of ferrite nucleation is hindered by the segregation of Ce at grain boundaries. However, at a later stage, the recrystallization kinetics are accelerated owing to the ineffective pinning of dislocations and boundaries by coarse Ce₂Fe₁₇ and Ce₂C₃ particles.     

Characterization of intermetallic precipitates in a Nimonic alloy by ultrasonic velocity measurements

Ultrasonic velocity measurements have been carried out in Nimonic 263 specimens thermally aged at 923 and 1073 K for durations up to 75 h and correlated with the results of hardness measurements and electron microscopy studies. The ultrasonic velocities and hardness results obtained in the specimens thermally aged at both temperatures clearly indicated that ultrasonic velocity is more sensitive to the initiation of the precipitation, whereas the influence of precipitation on hardness can be observed only after the precipitates attain a minimum size to influence the movement of dislocations. Further, ultrasonic velocity measurements also revealed faster kinetics and a lesser amount of precipitation at 1073 K compared to 923 K due to higher solubility of precipitate-forming elements.     

Phenomenal Effect of Stable (Ti,Mo)C Nano-Sized Precipitates in Retarding the Recrystallization and Grain Growth in High-Strength Ferritic Steel

Metallurgical and Materials Transactions A - The present study demonstrates remarkable retardation of recrystallization and grain growth during sub-critical annealing of 60 pct cold-rolled ferritic...