Department of Applied Mechanics

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

Colour transfer methodology is used in the field of image processing to transfer colour characteristics between images. In this study, colour transfer employing principal component analysis (PCA) is explored to circumvent the colour mismatch between application and calibration images in twelve fringe photoelasticity. For this, the images are considered as 3-D pixel clouds in RGB colour space. © Society for Experimental Mechanics, Inc. 2020.

World University root node

Conference Proceedings of the Society for Experimental Mechanics Series

Colour Transfer in Twelve Fringe Photoelasticity (TFP)

This work reports the growth of stable TiO2 nanotube arrays on flexible Kapton substrates by electrochemical anodization of a sputtered Ti (titanium) film. Although such nanotubes are conventionally fabricated on Ti foils, obtaining these on polymer-based flexible substrates remained a challenge because of higher annealing temperature not compatible with thermal stability of the substrates. Here, we demonstrate the fabrication of TiO2 nanotubes (1.5 μm long and 80 nm diameter) by anodization of the Ti film deposited using the RF sputtering technique at two different substrate temperatures (room temperature and 300 °C). Nanoindentation and nanoscratch techniques reveal better adhesion of the Ti film with an underlying Kapton substrate for 300 °C deposition temperature. Such investigations reveal a more than twofold enhancement of the "rear pileup"for the Ti film deposited at elevated temperature compared to that at room temperature. The amorphous TiO2 nanotubes are crystallized at 220 °C for 3 h using a solvothermal technique that allows crystallization at temperatures much lower than the annealing temperature. Application of these nanotubes for photo-electrochemical water splitting reveals a photocurrent density of 18 μA/cm2 under AM 1.5 G conditions. Furthermore, the charge density and flat band potential (VFB) are calculated from Mott-Schottky analysis, showing features comparable to the TiO2 nanotubes on the Ti foil crystallized through thermal annealing. The present work establishes a scalable approach for developing TiO2 nanotube arrays on the flexible substrate and its use for photo-electrochemical solar energy conversion. © 2020 American Chemical Society. All rights reserved.

Department Of Physics

ACS Applied Nano Materials

TiO2Nanotube Arrays on Flexible Kapton Substrates for Photo-Electrochemical Solar Energy Conversion

Polymer bi-layer systems are often exposed to different environmental service conditions which can potentially alter the mechanical properties as it approaches the glass transition temperature of an inaccessible substrate. However, since the substrate is inaccessible, it is difficult to measure or quantify the changes in these properties while in use. A methodology has been proposed in this work for prediction of glass transition temperature and Young's modulus of an inaccessible substrate in a bilayer system. The composite mechanical property of a bi-layer system is a function of the mechanical properties of coating, substrate and the depth at which it is measured. In the present work, poly-Methylmethacrylate (PMMA) coating of 900 nm is deposited on epoxy substrate. Nanoindentation experiments are conducted at different temperatures on the bi-layer system as well as on bulk PMMA. Finite element analysis has been used to obtain the material dependency of stress distribution coefficient (α) for deconvoluting the modulus of the substrate. The methodology developed by the present authors can predict the glass transition temperature as well the magnitudes of Young's modulus of an inaccessible substrate reasonably well. © 2020

Department of Mechanical Engineering

Polymer

Prediction of glass transition temperature and Young's modulus of an inaccessible polymer substrate in changing environment

It is now well established that most of the tumors are heterogeneous in nature that comprise a population of cancer stem cells (CSCs) and differentiated cancer cells. Like normal stem cells, CSCs have also self-renewal, proliferation, and differentiation capacities that are responsible for the development of drug resistance and relapse. Therefore, targeting CSCs is essential for the elimination of tumor recurrence condition. Although several anti-CSC therapeutics have been used in clinics, they are found to have limited efficacy due to poor solubility, lesser stability, and short circulation time in the blood. Therefore, tools in nanomedicines are being used to tackle these limitations. Recently, nanodrug carriers have been used to target CSCs and somewhat eliminate drug resistance by targeting CSC metabolism, inhibiting drug transporters, disturbing CSC survival pathways, etc. Even with these progress, the challenges for targeting CSCs by nanomedicines still remain and open up plenty of space for further development and improvement in synthesizing drug carriers with higher efficacy. In this chapter, we summarize about CSCs and their biological characterization toward resistance, then discuss several anti-CSC therapeutic approaches based on nanomedicines in the current state of research and development, and finally overview their future directions.

Department Of Biotechnology

Nanomedicine in Cancer Stem Cell Therapy

In the above paper [1], we proposed a novel framework that uses a constrained formulation of sum of squared correlation (SSCOR) approach as an alternative method for designing a spatial filter for steady-state visual evoked potential (SSVEP) based brain-computer interfaces (BCIs). To evaluate the target detection performance of the SSCOR method, the task-related component analyses (TRCA) were used as a benchmark [2]. The study used the SSVEP benchmark dataset containing 40 target data collected from 35 subjects [3]. During the evaluation of the proposed method, the SSCOR provided very high detection performance and outperformed the TRCA method and the results were reported. (Figure Presented). © 2001-2011 IEEE.

IEEE Transactions on Neural Systems and Rehabilitation Engineering

Erratum: Designing a sum of squared correlations framework for enhancing SSVEP based BCIs (IEEE Transactions on Neural Systems and Rehabilitation Engineering (2019) 27:10 (2044-2050) DOI: 10.1109/TNSRE.2019.2941349)

In this study, an attempt has been made to differentiate normal and cardiomegaly using cardio-mediastinal ratiometric features and machine learning approaches. A total of 60 chest radiographs including normal and cardiomegaly subjects are considered from a public dataset. The images are preprocessed using edge aware contrast enhancement technique to improve the edge contrast of lung boundaries. The mediastinal, cardiac and thoracic widths and their ratiometric indices are computed to characterize the morphological variations. The features are fed to three different classifiers for the differentiation of normal and cardiomegaly. Results show that the Linear discriminant analysis classifier is found to perform better with average values of recall 88.7%, precision 88.8%, and area under the curve 91.9%. Hence, the proposed computer aided diagnostic approach appears to be clinically significant to distinguish normal and cardiomegaly especially in remote and resource - poor settings. © 2020 European Federation for Medical Informatics (EFMI) and IOS Press.

Studies in Health Technology and Informatics

Classification of normal and cardiomegaly conditions in chest radiographs using cardio-mediastinal features

This study focuses on the failure of blades which is one of the critical parts of the compressor and turbine. Experiments are performed on the aero-engine compressor blade model of dovetail joint using the technique of photoelasticity. First, the high-stress concentration zone is found. This is along the contact surface of the blade and disc. Two different configurations of cracks located in this zone are studied further. The stress intensity factors for mixed mode loading are evaluated using over-deterministic nonlinear least squares approach. © 2020, Springer Nature Singapore Pte Ltd.

GENERAL

Lecture Notes in Mechanical Engineering

Evaluation of Fracture Parameters of Cracks in Compressor Blade Root Using Digital Photoelasticity

Intersecting sprays are important to several practical applications from rocket combustion to spray painting. The characteristics of these sprays are examined using water as the working fluid. Three types of atomizer configurations are used for this study: (i) Single spray (ii) Double spray- two pressure swirl atomizers of same type, separated by a distance in the exit orifice plane and (iii) Triple spray- three pressure swirl atomizers of same type, placed on the corners of an equilateral triangle. The Sauter mean diameter, joint velocity and diameter distributions as well as the radial and circumferential liquid distribution are experimentally measured using phase doppler interferometry (PDI) technique. From these results, it is observed that at low injection pressures the liquid sheets emerge from exit orifices interacts. As the injection pressure is increased, the breakup length tends to decrease and a regime is identified where the liquid sheets and droplet clouds interfere. In this regime, the drop clouds formed from the different sheets collide with each other resulting in further increases in velocity and drop size remain unaltered. As a result, the hollow cone nature of the overall spray is transformed into solid cone spray of almost an even mean drop size distribution downstream of the spray intersection region. The study demonstrates that the dynamics of wave propagation on the liquid sheets in intersecting sprays is markedly different from the non-intersecting spray. The superimposition of diameter and velocity distribution of two or more single spray is different from the mutual intersection of multiple sprays. © 2018 Solar Turbines Incorporated.

ICLASS 2018 - 14th International Conference on Liquid Atomization and Spray Systems

Dynamics of intersecting pressure swirl sprays

The transport and deposition of micrometer-sized particles in the lung is the primary mechanism for the spread of aerosol borne diseases such as corona virus disease-19 (COVID-19). Considering the current situation, modeling the transport and deposition of drops in human lung bronchioles is of utmost importance to determine their consequences on human health. The current study reports experimental observations on deposition in micro-capillaries, representing distal lung bronchioles, over a wide range of Re that imitates the particle dynamics in the entire lung. The experiment investigated deposition in tubes of diameter ranging from 0.3 mm to 2 mm and over a wide range of Reynolds number (10-2 ≤ Re ≤ 103). The range of the tube diameter and Re used in this study is motivated by the dimensions of lung airways and typical breathing flow rates. The aerosol fluid was loaded with boron doped carbon quantum dots as fluorophores. An aerosol plume was generated from this mixture fluid using an ultrasonic nebulizer, producing droplets with 6.5 μm as a mean diameter and over a narrow distribution of sizes. The amount of aerosol deposited on the tube walls was measured using a spectrofluorometer. The experimental results show that dimensionless deposition (δ) varies inversely with the bronchiole aspect ratio (L¯), with the effect of the Reynolds number (Re) being significant only at low L¯. δ also increased with increasing dimensionless bronchiole diameter (D¯), but it is invariant with the particle size based Reynolds number. We show that δL¯∼Re-2 for 10-2 ≤ Re ≤ 1, which is typical of a diffusion dominated regime. For Re ≥ 1, in the impaction dominated regime, δL¯ is shown to be independent of Re. We also show a crossover regime where sedimentation becomes important. The experimental results conclude that lower breathing frequency and higher breath hold time could significantly increase the chances of getting infected with COVID-19 in crowded places. © 2020 Author(s).

Department of Metallurgical and Materials Engineering

Fulltext

Physics of Fluids

An experimental study of respiratory aerosol transport in phantom lung bronchioles

Foraging and other natural phenomena show superdiffusive transport that are described by Lévy walks. We present a model experimental system, an octanoic acid (OA) drop on aqueous unsaturated OA solutions, for studying Lévy walks in controlled environments. The drop spontaneously moves due to unbalanced Marangoni forces, in a manner that mimics biological propulsion in living systems. The drop motion is shown to be a Lévy walk by demonstrating superdiffusive transport, Lévy-stable distributed step lengths, and power-law decay in the velocity autocorrelation function, with consistent exponents. © 2020 American Physical Society.