The Indian National Academy of Engineering (INAE), founded in 1987 comprises India's engineers, engineer-scientists and technologists covering the entire spectrum of engineering disciplines. The Academy is registered under the Societies Registration Act 1860 and is an autonomous institution supported partly through grant-in-aid by Department of Science & Technology , Government of India. As the only engineering Academy of the country, INAE represents India at the International Council of Academies of Engineering and Technological Sciences (CAETS) .INAE functions as an apex body and promotes the practice of engineering & technology and the related sciences for their application to solving problems of national importance. The Academy also provides a forum for futuristic planning for country's development requiring engineering and technological inputs and brings together specialists from such fields as may be necessary for comprehensive solutions to the needs of the country..
The influence of grain size, in the range of 10 to 180 mu m, on creep properties of 304HCu stainless steel (SS) was evaluated at 180 MPa and 923 K. A 30 mu m grain size showed a peak in creep life and minimum in steady-state creep rate with low damage potential. Detailed microstructural investigations revealed an increase in the tendency to intergranular fracture at grain sizes above 30 mu m, whereas 'transgranular fracture coupled with isolated intergranular cracks/cavities' have been observed with decreasing grain size from 30 to 10 mu m.
ABSTRACT Fluorine has many different potential sites and channels of production, making narrowing down a dominant site of fluorine production particularly challenging. In this work, we investigate which sources are the dominant contributors to the galactic fluorine by comparing chemical evolution models to observations of fluorine abundances in Milky Way stars covering a metallicity range of −2 < [Fe/H] < 0.4 and upper limits in the range of −3.4 < [Fe/H] < −2.3. In our models, we use a variety of stellar yield sets in order to explore the impact of varying both asymptotic giant branch (AGB) and massive star yields on the chemical evolution of fluorine. In particular, we investigate different prescriptions for initial rotational velocity in massive stars as well as a metallicity-dependent mix of rotational velocities. We find that the observed [F/O] and [F/Fe] abundance ratios at low metallicity and the increasing trend of [F/Ba] at [Fe/H] ≳ −1 can only be reproduced by chemical evolution models assuming, at all metallicities, a contribution from rapidly rotating massive stars with initial rotational velocities as high as 300 km s−1. A mix of rotational velocities may provide a more physical solution than the sole use of massive stars with vrot = 300 km s−1, which are predicted to overestimate the fluorine and average s-process elemental abundances at [Fe/H] ≳ −1. The contribution from AGB stars is predicted to start at [Fe/H] ≈ −1 and becomes increasingly important at high metallicity, being strictly coupled to the evolution of the nitrogen abundance. Finally, by using modern yield sets, we investigate the fluorine abundances of Wolf–Rayet winds, ruling them out as dominant contributors to the galactic fluorine.
We introduce GIZMO-SIMBA, a new suite of galaxy cluster simulations within THE THREE HUNDRED project. THE THREE IIUNDRED consists of zoom re-simulations of 324 clusters with M-200 greater than or similar to 10(14.8) M-circle dot drawn from the MultiDark-Planck N-body simulation, run using several hydrodynamic and semi-analytical codes. The GIZMO-SIMBA suite adds a state-of-the-art galaxy formation model based on the highly successful SIMBA simulation, mildly re-calibrated to match z = 0 cluster stellar properties. Comparing to THE THREE HUNDRED zooms run with GADGET-X, we find intrinsic differences in the evolution of the stellar and gas mass fractions, BCG ages, and galaxy colour-magnitude diagrams, with GIZMO-SIMBA generally providing a good match to available data at z approximate to 0. GIZMO-SIMBA'S unique black hole growth and feedback model yields agreement with the observed BH scaling relations at the intermediate-mass range and predicts a slightly different slope at high masses where few observations currently lie. GIZMO-SIMBA provides a new and novel platform to elucidate the co-evolution of galaxies, gas, and black holes within the densest cosmic environments.
Advanced ultra-supercritical (AUSC) fossil-fired power plants are envisaged to operate at a higher steam temperature (983–1023 K) and pressure (32–35 MPa) compared to existing supercritical and ultra-supercritical thermal power plants. One of the candidate materials currently considered for application in boiler tube circuit for India’s National Mission on AUSC is 304HCu stainless steel (SS). In the present study, the influence of grain size on the creep properties of 304HCu SS was evaluated at a temperature of 923 K in the stress range of 180–240 MPa. The grain sizes investigated were 10, 20, 30 and 60 µm. At all the stress levels, the grain size of 30 micron exhibited the lowest value of minimum creep rate and highest rupture life. The variation of minimum creep rate with applied stress for all the grain sizes followed Norton’s power law relation, $$\dot{\varepsilon }_{\min } = A\sigma^{n}$$ . The values of ‘A’ and ‘n’ were strongly dependent on the grain size. The creep curves were modelled using an improved theta projection approach wherein the mathematical formulations for primary and tertiary creep regimes were modified for better correlation with experimental creep curves. Further, the variation of theta parameters with respect to stress and grain size was established through an empirical correlation. The rupture lives predicted from modified theta projection approach are in close agreement with the experimental values. The formulation of improved model is generalized to predict creep curves/total strain curves irrespective of duration in the three stages of creep, and the predictions were also verified with creep data of 316 SS and P91 steel.
