Department of Mechanical Engineering

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Tropical cyclones (TCs) that make landfall over India’s east coast are responsible for significant loss of life along affected coastlines. TCs forming over the Bay of Bengal (BoB) region in October, November, and December have, in the past, intensified significantly at the time of landfall. The effects of climate change on TCs of different strengths and their characteristics such as track, intensity, precipitation, and convective available potential energy over the BoB region have not been well studied. This study explores the effects of climate change on two TCs of very severe cyclonic storm (VSCS) category (TC Vardah and TC Madi), and two other TCs of extremely severe cyclonic storm (ESCS) category (TC Hudhud and TC Phailin) formed over BoB, both in the short term (2035) and long term (2075). The high-resolution Weather Research and Forecasting (WRF) model is used to simulate the TCs under current and future climate conditions. The simulated TC track and intensity in the current climate agree well with the observations. To explore the impacts of climate change on TCs, the mean climate change signal, computed from future projections of the Community Climate System Model (CCSM4) in different representative concentration pathway (RCP) scenarios, is added to current climate conditions by using the pseudo global warming method. Results show a climate change-related reduction in TC translation speed, deepening of TC core, increased maximum surface wind, and increased precipitation over land in future RCP (4.5, 6.0, and 8.5) scenarios. The TCs in future RCP scenarios are seen to be more intensified compared to current climate simulations. Results demonstrate that all VSCS and ESCS category TCs considered in this study are likely to further intensify to the next higher category level with respect to their current classification, particularly in the far future RCP 6.0 and in the far future RCP 8.5 scenarios. The cyclone damage potential index of TC Vardah, TC Hudhud, and TC Phailin is projected to increase in a future warming climate. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.

Department Of Civil Engineering

World University root node

Climate Dynamics

Impact of climate change on intense Bay of Bengal tropical cyclones of the post-monsoon season: a pseudo global warming approach

Optimal support layout design of structures under forced vibration is determined using topology optimization method. The vibrations of a structure can be reduced by adding external supports to the structure. Linear elastic springs are used as the external supports and the objective function used is dynamic compliance of structure. Solid Isometric Material with Penalty (SIMP) method is employed to solve the topology optimization problem. The optimal support locations are determined for cantilever beam and plate structures subjected to harmonic loads. © 2021, Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

Optimum Support Layout Design for Periodically Loaded Structures Using Topology Optimization

Age-related hearing loss (ARHL) is a common condition in humans marking the gradual decrease in hearing with age. Perturbations in the tip-link protein cadherin-23 that absorbs the mechanical tension from sound and maintains the integrity of hearing is associated with ARHL. Here, in search of molecular origins for ARHL, we dissect the conformational behavior of cadherin-23 along with the mutant S47P that progresses the hearing loss drastically. Using an array of experimental and computational approaches, we highlight a lower thermodynamic stability, significant weakening in the hydrogen-bond network and inter-residue correlations among β-strands, due to the S47P mutation. The loss in correlated motions translates to not only a remarkable two orders of magnitude slower folding in the mutant but also to a proportionately complex unfolding mechanism. We thus propose that loss in correlated motions within cadherin-23 with aging may trigger ARHL, a molecular feature that likely holds true for other disease-mutations in β-strand-rich proteins. © 2021 The Author(s).

Department Of Biotechnology

Fulltext

Biochemical Journal

Weakening of interaction networks with aging in tip-link protein induces hearing loss

In this work, a non-imaging low concentrating 2.5X Compound Parabolic Concentrator (CPC) truncated to 1.7X has been explored. CPCs inherently form non-uniform distribution of flux on the PVT module which has been mitigated by the integration of optimized homogenizer referred to as Elongated CPC (ECPC). The study involves detailed optical, thermal, and electrical modeling of the ECPC based Low Concentrating Photovoltaic Thermal (LCPVT) system. Optical simulations provide insight into the flux distribution on the PVT panel surface, which is further coupled with a thermal and electrical model for precise prediction of the performance of the system. These models are validated experimentally with a 315 Wp solar panel integrated with ECPC based LCPVT system. Performance evaluation of the system has shown peak thermal efficiency of ∼40% at ΔT of 16 °C, peak electrical efficiency of 12%, and an overall peak exergy efficiency of 15% at 38 Liters per hour (LPH) flow rate. A comparison of outlet water temperature results obtained from the numerical model and experiments has shown an excellent match with a relative error of 4%. Results also show that the increase in mass flow rate from 22 LPH to 38 LPH improves the electrical efficiency by 3% however a drop in ΔT of 2–3 °C is observed. © 2020 Elsevier Ltd

Renewable Energy

Numerical modeling and performance assessment of elongated compound parabolic concentrator based LCPVT system

Closed form expressions for the domination number of an n× m grid have attracted significant attention, and an exact expression has been obtained in 2011 [7]. In this paper, we present our results on obtaining new lower bounds on the connected domination number of an n× m grid. The problem has been solved for grids with up to 4 rows and with 6 rows and the best currently known lower bound for arbitrary m, n is [11]. Fujie [4] came up with a general construction for a connected dominating set of an n× m grid. In this paper, we investigate whether this construction is indeed optimum. We prove a new lower bound of for arbitrary m, n≥ 4. © 2021, Springer Nature Switzerland AG.

Department of Computer Science and Engineering

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

The Connected Domination Number of Grids

Experimental and numerical studies of downward flame spread over polymethyl methacrylate (PMMA) with and without addition of triphenyl phosphate (TPP) are reported. Using the micro-thermocouple technique and molecular beam spectrometry, detailed flame structures of PMMA and PMMA+10%TPP were measured. From the experiments and quantum chemistry calculations, the retardancy capability of TPP on gas-phase reaction is proposed. Addition of flame retardant (10%, 20% TPP) results in reduction of the flame spread rate, the mass burning rate and conductive heat flux from the flame to the polymer surface. Numerical calculation was carried out to simulate the downward flame spread over PMMA and PMMA-TPP slabs. Based on the assumption of the TPP gas phase retardancy performance, a modified one-step reaction rate constant with pre-exponent dependent on the TPP mass content in the polymer and TPP retardancy effectivity is proposed. The predicted results have been compared with the data from sophisticated experimental measurement on thermal and chemical structures of both PMMA and PMMA+TPP flames. © 2021 Elsevier Ltd. All rights reserved.

Department of Aerospace Engineering

Proceedings of the Combustion Institute

Experimental and numerical studies of downward flame spread over PMMA with and without addition of tri phenyl phosphate

The levels of hydrogen peroxide (H 2O 2) in human blood is of great relevance as it has emerged as an important signalling molecule in a variety of disease states. Fast and reliable measurement of H 2O 2 levels in the blood, however, continues to remain a challenge. Herein we report an automated method employing a microfluidic device for direct and rapid measurement of H 2O 2 in human blood based on laser-induced fluorescence measurement. Our study delineates the critical factors that affect measurement accuracy—we found blood cells and soluble proteins significantly alter the native H 2O 2 levels in the time interval between sample withdrawal and detection. We show that separation of blood cells and subsequent dilution of the plasma with a buffer at a ratio of 1:6 inhibits the above effect, leading to reliable measurements. We demonstrate rapid measurement of H 2O 2 in plasma in the concentration range of 0–49 µM, offering a limit of detection of 0.05 µM, a sensitivity of 0.60 µM−1, and detection time of 15 min; the device is amenable to the real-time measurement of H 2O 2 in the patient’s blood. Using the linear correlation obtained with known quantities of H 2O 2, the endogenous H 2O 2 concentration in the blood of healthy individuals is found to be in the range of 0.8–6 µM. The availability of this device at the point of care will have relevance in understanding the role of H 2O 2 in health and disease. © 2021, The Author(s).

Scientific Reports

Direct and rapid measurement of hydrogen peroxide in human blood using a microfluidic device

Detail characterization of the liquid jet core in a model cross-stream airblast atomizer by application of the Optical Connectivity (OC) technique is the goal of the present paper. The unique ability of the technique in imaging the fluorescence signal exclusively from the jet core region facilitates simultaneous visualization of the liquid jet from the side- and the front-view with high background contrast. This allows measurement of some important primary breakup characteristics. The jet penetration and breakup length are obtained from the side-view images, while the front view images provides the jet width and the spreading angle. The above parameters are measured for a wide range of injector operating conditions. The measurement of mean jet trajectory and mean penetration/breakup length indicated large difference in comparison to the past studies based on experiments conducted in wind-tunnels. This is attributed to air flow confinement within the atomizer in the present case and also accurate measurement of breakup location in the OC technique. The range of the measured mean width of the jet and spreading angle indicated ’sheet breakup mode’ of the liquid jet for all injector operating conditions. Correlations are obtained to describe the evolution of different mean quantities with respect to relevant non-dimensional numbers. The fluctuations of jet breakup parameters are also measured. Some interesting correlations are obtained between fluctuations of different primary breakup characteristics which are discussed in the paper. © 2021 Elsevier Ltd

International Journal of Multiphase Flow

Liquid jet core characterization in a model crossflow airblast atomizer

FDAPT (2-formyl-5-(4′-N,N-dimethylaminophenyl)thiophene) is an efficient environment-sensitive fluorescent probe, which senses the alteration of its microenvironment with six different fluorescent parameters, namely, emission intensity, wavelength, fluorescence anisotropy, and corresponding three time-dependent parameters fluorescence lifetime, time-resolved emission spectrum, and anisotropy decay. In the present work, the nature of saccharide-induced dehydration of a F127 polymeric micelle is investigated in detail with FDAPT emission. Using a multiparametric fluorescence approach, it is observed that the saccharide molecules not only decrease the critical micellization temperature of the F127 solution but also strongly alter the physical properties inside the micellar structures. The local polarity and fluidity significantly decrease in the saccharide-induced micelle as compared to the normal F127 micelle. The probe solvation dynamics study reveals that the water content in the core as well as corona domain diminishes significantly in the saccharide-induced micelle as compared to the normal micelle. More precisely, dehydration occurs more in the core region than in the corona region. Also, the saccharide-induced dehydration alters the relative size of the core and corona regions. The extent of dehydration varies with different saccharide molecules. It is also found that the dehydration efficiency order is trisaccharide (raffinose) > disaccharide (sucrose) > monosaccharide (glucose and fructose). © 2021 American Chemical Society.

Department Of Chemistry

Langmuir

Nature of Saccharide-Induced F127 Micellar Dehydration: An Insight with FDAPT (2-Formyl-5-(4′- N, N-dimethylaminophenyl)thiophene), a Multiparametric Fluorescent Probe

For high precision laser surgery, noninvasive tool for prediction of laser ablation profile beforehand is imperative. The present study proposed a method to utilize nondestructive FTIR and Raman probes for predicting laser ablation profile overcoming the challenge of heterogeneity on individual target tissue. By ascribing the chemical heterogeneity of teeth drive their differential machining capability, the study establishes a correlation between the chemical composition and their ablation parameters (ω0,Deff and Fth). The chemical composition of teeth was obtained by noninvasive tools (FTIR and Raman) in terms of absorption peak intensity. To further correlate with key laser ablation parameters, the laser irradiation study was carried out using 800 nm, 100 fs, Ti:Sapphire laser. The surface morphology of irradiated sample was measured by optical profiler. A strong correlation was observed between laser ablation parameters and peak intensity of phosphate group for both FTIR and Raman spectroscopy. The concentration of phosphate group shows a positive relationship to ablation threshold fluence, while the effective Gaussian beam radius and effective energy penetration depth show negative correlation. Both nondestructive probes show good linearity which enable us to extrapolate the key laser ablation parameters for predicting laser ablation profile on random dentin and enamel samples. The ablation profiles predicted based on both FTIR and Raman are well-matched in dentin, whereas it shows a slight deviation in enamel. The predicted profiles are consistent with experimental results at lower power whereas it shows a slight deviation at higher power due to screening effect. Thus, FTIR and Raman probes can be used to predict laser ablation profile nondestructively in real-time and obviate the need for trial runs. Furthermore, the present study has predicted the laser ablation rate and ablation efficiency for performing laser surgery in optimum laser processing conditions irrespective of teeth heterogeneity. © 2020 Elsevier Ltd