Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Population & Thin film. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

SVM-PGSL coupled approach for statistical downscaling to predict rainfall from GCM output

Abstract: [1] Hydrological impacts of climate change are assessed by downscaling the General Circulation Model (GCM) outputs of predictor variables to local or regional scale hydrologic variables (predictand). Support Vector Machine (SVM) is a machine learning technique which is capable of capturing highly nonlinear relationship between predictor and predictand and thus performs better than conventional linear regression in transfer function-based downscaling modeling. SVM has certain parameters the values of which need to be fixed appropriately for controlling undertraining and overtraining. In this study, an optimization model is proposed to estimate the values of these parameters. As the optimization model, for selection of parameters, contains SVM as one of its constraints, analytical solution techniques are difficult to use in solving it. Probabilistic Global Search Algorithm (PGSL), a probabilistic search technique, is used to compute the optimum parameters of SVM. With these optimum parameters, training of SVM is performed for statistical downscaling. The obtained relationship between large-scale atmospheric variables and local-scale hydrologic variables (e.g., rainfall) is used to compute the hydrologic scenarios for multiple GCMs. The uncertainty resulting from the use of multiple GCMs is further modeled with a modified reliability ensemble averaging method. The proposed methodology is demonstrated with the prediction of monsoon rainfall of Assam and Meghalaya meteorological subdivision of northeastern India. The results obtained from the proposed model are compared with earlier developed SVM-based downscaling models, and improved performance is observed.

The South Tibetan detachment system facilitates ultra rapid cooling of granulite-facies rocks in Sikkim Himalaya

Abstract: [1] The eastern Himalaya is characterized by a region of granulites and local granulitized eclogites that have been exhumed via isothermal decompression from lower crustal depths during the India-Asia collision. Spatially, most of these regions are proximal to the South Tibetan detachment system, an orogen-parallel normal-sense detachment system that operated during the Miocene, suggesting that it played a role in their exhumation. Here we use geo- and thermochronological methods to study the deformation and cooling history of footwall rocks of the South Tibetan detachment system in northern Sikkim, India. These data demonstrate that the South Tibetan detachment system was active in Sikkim between 23.6 and ~13 Ma, and that footwall rocks cooled rapidly from ~700 to ~120 °C between ~15-13 Ma. While active, the South Tibetan detachment system exhumed rocks from mid-crustal depths, but an additional heat source such as strain heating, advected melt and/or crustal thinning is required to explain the observed isothermal decompression. Cessation of movement on the South Tibetan detachment system produced rapid cooling of the footwall as isotherms relaxed. A regional comparison of temperature-time data for the eastern South Tibetan detachment system indicates a lack of synchronicity between the Sa'er-Sikkim-Yadong section and the NW Bhutan section. To accommodate this requires either strike-slip tear faulting or local out-of-sequence thrusting in the younger segment of the orogen.

Hybrid adaptive layer manufacturing: An Intelligent art of direct metal rapid tooling process

Abstract: A direct metal rapid tool making process, hybrid-layered manufacturing (HLM), was developed for building metallic dies and molds. This unique methodology has a numerical controlled system that integrates the TransPulse Synergic Metal Inert Gas (MIG)/Metal Active Gas (MAG) welding process for near-net layer deposition and Computer Numerical Control (CNC) milling process for net shaping. A customized software program was made to calculate the required adaptive slice thickness for the deposition of the filler metal with welding process as successive layers from the lowest to the topmost layer direction and to generate the required NC codes for machining from the top to the bottom layer direction of the deposited metallic layers for attaining the required contour profile shape. To implement this proposed process, a low-cost three-axis manipulator was fabricated with stepper motor divers in open-loop control and integrated with the weld machine. Adequate isolation to protect the motion control electronics from welding spike was incorporated. Synchronization of this two-step processing of each layer, yielding near-net deposition with welding process and near-net shaping with CNC milling operation offers a new accelerator way of building metal tools and dies.

MMP proteolytic activity regulates cancer invasiveness by modulating integrins

Abstract: Cancer invasion through dense extracellular matrices (ECMs) is mediated by matrix metalloproteinases (MMPs) which degrade the ECM thereby creating paths for migration. However, how this degradation influences the phenotype of cancer cells is not fully clear. Here we address this question by probing the function of MMPs in regulating biophysical properties of cancer cells relevant to invasion. We show that MMP catalytic activity regulates cell spreading, motility, contractility and cortical stiffness by stabilizing integrins at the membrane and activating focal adhesion kinase. Interestingly, cell rounding and cell softening on stiff gels induced by MMP inhibition is attenuated on MMP pre-conditioned surfaces. Together, our results suggest that MMP catalytic activity regulates invasiveness of cancer cells by modulating integrins.

Predictions of Bound Water Content in Poly(N-isopropylacrylamide) Gel†

Abstract: We have quantitatively predicted the bound water content in the poly(N-isopropylacrylamide) gel by using the extended lattice-fluid hydrogen-bond theory. The calculations indicate that the bound water content in the gel is about 0.4g/g at temperatures above the LCST, whereas the free water content below the LCST is at least 2-4 times greater than the bound water content