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

Microwave hyperthermia makes use of microwaves to deliver heat to biological tissues. Real time temperature monitoring during treatment is important for efficacy and effectiveness of the treatment. Non-invasive methods such as CT, MR and ultrasound (US) have been actively researched for use in hyperthermia monitoring. US has inherent advantages of real-time imaging, portability and non-ionizing nature. It is also known from the literature that acoustic properties of tissue are sensitive to temperature and this has been harnessed to track the evolution of hotspot and temperature in high temperature zones encountered in ablation treatments. However, their usage in low temperature zones typically observed in hyperthermia appears to be less explored. This study introduces an improved method of regularized Kurtosis imaging (RKI) and compares its performance against regularized log spectral difference (RLSD) and regularized Nakagami imaging methods. The performance of these methods is compared against the ground truth estimated from IR thermal images in an experimental study on tissue-mimicking PAG-agar based phantoms. The error in the area estimated by RKI was 10.6%. The error in the lateral and axial co-ordinate of the centroid was 5.92% and 0.47%, respectively. The structural similarity index was 0.82 for RKI when compared with RLSD and RNI having score of 0.76 and 0.72, respectively. The results are promising and offer an alternative way to track the hotspot during microwave hyperthermia treatment. © 2020 IEEE.

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Department Of Biotechnology

Department of Engineering Design

Proceedings - International Symposium on Biomedical Imaging

Regularized Kurtosis Imaging and its Comparison with Regularized Log Spectral Difference and Regularized Nakagami Imaging for Microwave Hyperthermia Hotspot Monitoring

Design and performance analysis of a novel Transcritical Regenerative Series Two stage Organic Rankine Cycle for dual source waste heat recovery

In this work, an attempt has been made to assess the texture variations of brainstem occurring in the Early Mild Cognitive Impairment (EMCI) condition. Fractal dimension is calculated for the segmented brainstem volume using Higuchi's and Detrending moving average (DMA) method. These measures are validated using Random forest classifier. DMA shows better performance when compared to Higuchi's method in categorising EMCI stage. Thus, the proposed approach using brainstem image's DMA fractal measures with random forest can be used in diagnosis of EMCI. © 2020 European Federation for Medical Informatics (EFMI) and IOS Press.

Studies in Health Technology and Informatics

Identification of EMCI in MR brainstem structure using fractal measures and random forest approach

Multiple cores in a tiled multi-core processor are connected using a network-on-chip mechanism. All these cores share the last-level cache (LLC). For large-sized LLCs, generally, non-uniform cache architecture design is considered, where the LLC is split into multiple slices. Accessing highly shared cache blocks from an LLC slice by several cores simultaneously results in congestion at the LLC, which in turn increases the access latency. To deal with this issue, we propose a congestion management technique in the LLC that equips the NoC router with small storage to keep a copy of heavily shared cache blocks. To identify highly shared cache blocks, we also propose a prediction classifier in the LLC controller. We implement our technique in Sniper, an architectural simulator for multi-core systems, and evaluate its effectiveness by running a set of parallel benchmarks. Our experimental results show that the proposed technique is effective in reducing the LLC access time. © 2020 IEEE.

Department of Computer Science and Engineering

Proceedings - IEEE International Conference on Computer Design: VLSI in Computers and Processors

Router Buffer Caching for Managing Shared Cache Blocks in Tiled Multi-Core Processors

In the current study, experiments are performed on the aero-engine compressor blade model which is fastened to the disc using dovetail joint. Using the technique of photoelasticity, the highly stressed zone is found to be at the interface of the disc and the blade. Cyclic loading is then applied to the disc-blade assembly. Initial experimental observations showed formation of small cracks leading to crack growth and subsequent failure. In this region, a small crack is put and then the growth of crack during cyclic loading is studied till the failure of the specimen. The variation of stress intensity factor with respect to crack length and the number of cycles is evaluated for crack perpendicular to the contact length. Â© 2020, Society for Experimental Mechanics, Inc.

Conference Proceedings of the Society for Experimental Mechanics Series

Analysis of Crack Growth in Compressor Blade Root Subjected to Fatigue

In this study, an attempt has been made to analyze uterine Electromyography (uEMG) signals during Term conditions (pregnancy duration more than 37 weeks of gestational age) using Empirical Mode Decomposition based Detrended Fluctuation Analysis (EMD-DFA). The Term delivery signals are considered from a publicly available database, grouped as T1 (<26 weeks gestational age) and T2 (≥26 weeks gestational age) based on the time of recording, and are subjected to an EMD-DFA algorithm. The double logarithmic plot of the detrended fluctuation function against the scale is analyzed, and the Hurst exponent feature is computed for both groups. The features are statistically analyzed using the Student s t-test. Results show that the EMD-DFA method is able to capture the variations in the fluctuations of uEMG signals under these conditions. The Hurst exponent feature is found to be statistically significant (p-value < 0.005) for both groups. There is an increase in the Hurst exponent feature value in the T2 group, which indicates that T2 signals possess smoother characteristics than T1 signals. Hence, it appears that the proposed approach could aid in investigating variations in the fluctuations of Term delivery signals, differentiating T1 and T2 conditions.. © 2020 Institute of Electronics and Information Engineers. All rights reserved.

IEIE Transactions on Smart Processing and Computing

Empirical Mode Decomposition based Detrended Fluctuation Analysis of Uterine Electromyography Signals in Term Conditions

Department of Aerospace Engineering

Intermittency in a Pitch-Plunge Aeroelastic System

Flexible structures are continuum modeled as infinite degrees of freedom. Most of the time finite element models are made with large number of degrees-of-freedom to analyse flexible structures. Continuous monitoring, analysis and control of dynamics of flexible structures need simulation of large degrees of freedom in real time. This is computationally expensive and realtime control fails. This study focuses on the development of a reduced order framework for dynamics of flexible structures and use the reduced order model for controlling the structure. Essentially, in the proposed framework, full order state space obtained from finite element modeling of the flexible structure has been reduced to lower subspace using a reduced order algorithm keeping the dynamical characteristic intact. The transformation matrix for reduction has been calculated using system equivalent reduction expansion process (SEREP). Traditionally, full order dynamical system is being used to find the gain matrix to suppress the uncontrolled dynamics associated with the dynamical system. Here in this methodology, the reduced dimension of state space of the system is used for estimating the gain matrix using optimal linear quadratic regulator (LQR). The gain obtained through the reduced system is subsequently used as a feedback to the attached actuators which produce the required force to control the system. A numerical example of a flexible cantilever beam has been shown to investigate the effectiveness of the algorithm. © 2020, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

Fulltext

IFAC-PapersOnLine

SEREP Integrated Control of Flexible Structures

Recently, researchers have shown an increased interest in ultrasound imaging methods alternate to conventional focused beamforming (CFB). One such approach is based on the synthetic aperture (SA) scheme; more popular are the ones based on synthetic transmit aperture (STA) schemes with a single-element transmit or multielement STA (MSTA). However, one of the main challenges in translating such methods to low-cost ultrasound systems is the tradeoffs among image quality, frame rate, and complexity of the system. These schemes use all the transducer elements during receive, which dictates a corresponding number of parallel receive channels, thus increasing the complexity of the system. A considerable amount of literature has been published on compressed sensing (CS) for SA imaging. Such studies are aimed at reducing the number of transmissions in SA but still recover images of acceptable quality at high frame rate and fail to address the complexity due to full-aperture receive. In this work, we adopt a CS framework to MSTA, with a motivation to reduce the number of receive elements and data. The CS recovery performance was assessed for the simulation data, tissue-mimicking phantom data, and an example in vivo biceps data. It was found that in spite of using 50% receive elements and overall using only 12.5% of the data, the images recovered using CS were comparable to those of reference full-aperture case in terms of estimated lateral resolution, contrast-to-noise ratio, and structural similarity indices. Thus, the proposed CS framework provides some fresh insights into translating the MSTA imaging method to affordable ultrasound scanners. © 1986-2012 IEEE.

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

Compressed Sensing Approach for Reducing the Number of Receive Elements in Synthetic Transmit Aperture Imaging

Event-related patterns (EPs) play an essential role in detecting motor imagery (MI) movements of the subject. Due to the difference in the spatial and temporal distribution of brain signals among the subjects, the extraction of EP is a major issue. To rectify this problem, the Hilbert transform (HT) was used for the detection of EPs, and the machine learning (ML) models were implemented for decoding MI movements. The proposed method comprises two steps: initially, μ (8–12 Hz) and β (12–30 Hz) frequency bands were extracted from the raw electroencephalogram (EEG) signal. The HT was implemented on extracted μ and β bands signals and the EPs were calculated. Finally, the EPs were fed into two ML models such as support vector machine (SVM) and logistic regression (LR) for the detection of MI movements. The proposed method was tested on two benchmark datasets (BCI competition-III and IV). The results show that the mean classification accuracy (%CA) and Cohen's kappa coefficient (K) for BCI competition-III and IV were 86.11% & 0.72 and 82.50% & 0.65 respectively, which are higher than several existing methods. © 2020 Elsevier Ltd