Department of Electrical 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

Early detection of corona discharge plays a critical role in avoiding catastrophic failure of transformer insulation. In this study, we explore the use of two-dimensional material coated fluorescent fiber for early detection of corona discharge. Specifically, Molybdenum disulphide (MoS2) material is dip coated over a commercial grade fluorescent since the bandgap of the coated MoS2 material corresponds to the visible and ultraviolet (UV) spectral regions. Corona inception voltage detection adopting MoS2 coated fluorescent fiber exhibits detection efficiency with the percentage difference of 32% in comparison to the UHF technique. Also, fiber coating enhances the energy content of the discharge signal by the difference of 150% with respect to uncoated fluorescent fiber. The phase resolved partial discharge studies reveal that the discharge is observed at the peak of the applied AC voltage. © 2017 IEEE.

World University root node

IEEE Sensors Letters

Molybdenum Disulphide Coated Fluorescent Fiber for Detection of Corona Discharges in Transformer Oil

Highly metalized fuel-rich propellants containing 40–50% nano-micro aluminum and the catalyzed compositions comprise ultra-fine iron oxide (UFIO) content of 0.3–2.0% were considered. Primary combustion features and mechanical properties of these propellants were investigated for water ramjet propulsion applications. These propellants exhibit almost 70% burning rate enhancement at all the tested pressures with UFIO catalyzed ones as compared with uncatalyzed compositions. Simultaneously, the burning rate pressure exponent of these UFIO catalyzed propellants was considerably reduced. The quenched agglomerates from the primary combustion exhibit over wider size ranges from few microns to few millimeters, which are of several times larger as compared with parent Al particles. The number density effect of Al particles causing the agglomeration at the burning surface outweighs the particle size and catalyzer effect in these highly aluminized propellant compositions. The crack free propellant grain structure was achieved by optimizing the molding pressure range and the rate of compaction. Addition of UFIO increased the compressive strength marginally whereas it reduced the elastic properties of the propellant grain marginally. © 2023.

Department of Aerospace Engineering

International Journal of Energetic Materials and Chemical Propulsion

EFFECT OF CATALYZER ON PRIMARY COMBUSTION AND MECHANICAL PROPERTIES OF HIGHLY METALIZED FUEL-RICH PROPELLANTS

Low-light image enhancement has been an actively researched area for decades and has produced excellent night-time single-image, video, and Light Field restoration methods. Despite these advances, the problem of extreme low-light stereo image restoration has been mostly ignored and addressing it can enable night-time capabilities to several applications such as smartphones and self-driving cars. We propose an especially light-weight and fast hybrid U-net architecture for extreme low-light stereo image restoration. In the initial few scale spaces, we process the left and right features individually, because the two features do not align well due to large disparity. At coarser scale-spaces, the disparity between left and right features decreases and the network's receptive field increases. We use this fact to reduce computations by simultaneously processing the left and right features, which also benefits epipole preservation. As our architecture does not use any 3D convolution for fast inference, we use a Depth-Aware loss module to train our network. This module computes quick and coarse depth estimates to better enforce the stereo epipolar constraints. Extensive benchmarking in terms of visual enhancement and downstream depth estimation shows that our architecture not only restores dark stereo images faithfully but also offers 4-60× speed-up with 15-100× lower floating point operations, necessary for real-world applications. © 2023 IEEE.

Proceedings - 2023 IEEE Winter Conference on Applications of Computer Vision, WACV 2023

Real-Time Restoration of Dark Stereo Images

A static potential game is a non-cooperative game for which there exists a fictitious function, also referred to as a potential function, whose optimizers provide a Nash equilibrium of the associated non-cooperative game. In this paper, we study non-zero-sum finite-horizon difference games with feedback information structure which admit a potential game structure. We provide conditions for the existence of an optimal control problem such that the optimal solution of this problem provides a feedback Nash equilibrium of the corresponding non-cooperative game. We specialize the obtained results to a linear-quadratic setting so as to obtain these verifiable existence conditions in terms of the problem data. Finally, we illustrate our results using a network flow control problem. IEEE

IEEE Transactions on Automatic Control

On the Structure of Feedback Potential Difference Games

Massive multiple-input-multiple-output (MIMO) is a key enabler for obtaining higher data rates in the next generation wireless technology. While it has the power to transform cellular communication, with potential for spatial diversity and multiplexing, a bottleneck that often gets overlooked is the fronthaul capacity. The fronthaul link that connects a massive MIMO Remote Radio Head (RRH) and carries in-phase and quadrature (IQ) samples to the Baseband Unit (BBU) of the base station can throttle the network capacity/speed if appropriate data compression techniques are not applied, particularly in the uplink. This paper proposes an iterative technique for fronthaul load reduction in the uplink for massive MIMO systems utilizing the convolution structure of the received signals. The proposed algorithm provides compression ratios of about 30- 50×. This work provides extensive analysis of the performance of the proposed method for a plethora of practical scenarios and constraints, such as different channel parameters and models, receive antenna correlation, and under imperfect channel information. It also discusses the numerical convergence and complexity of the proposed algorithm and compares the performance against other existing compression techniques. © 2023 IEEE.

IEEE Open Journal of the Communications Society

Fronthaul Compression for Uplink Massive MIMO Using Matrix Decomposition

During a false data injection attack (FDIA), the attacker compromises the meter readings to corrupt the state estimator's output. One method of managing FDIA is by securing meters that are most vulnerable to attacks. The existing methods may not secure the most vulnerable meters, and may not work in practical scenarios where the utility has budget and time constraints. To solve these issues, a novel vulnerability index is proposed in this paper. The advantage of using the proposed index in finding meters to be secured is demonstrated using IEEE test systems. © 2022 Elsevier Ltd

International Journal of Electrical Power and Energy Systems

A novel vulnerability index to select measurements for defense against false data injection attacks

Indium gallium zinc oxide (IGZO)-based ferroelectric thin-film transistors (FeTFTs) are being vigorously investigated for being deployed in computing-in-memory (CIM) applications. Content-addressable memories (CAMs) are the quintessential example of CIM, which conduct a parallel search over a queue or stack to obtain the matched entries for a given input data. CAM cells offer the ability for massively parallel searches in a single clock cycle throughout an entire CAM array for the input query, thereby enabling pattern matching and searching functionality. Therefore, CAM cells are used extensively for pattern matching or search operations in data-centric computing. This paper investigates the impact of retention degradation on IGZO-based FeTFT on the multibit operation in content CAM cell applications. We propose a scalable multibit 1FeTFT-1T-based CAM cell composed of only one FeTFT and one transistor, thus significantly improving the density and energy efficiency compared with conventional complementary metal-oxide-semiconductor (CMOS)-based CAM. We successfully demonstrate the operations of our proposed CAM with storage and search by exploiting the multilevel states of the experimentally calibrated IGZO-based FeTFT devices. We also investigate the impact of retention degradation on the search operation. Our proposed IGZO-based 3-bit and 2-bit CAM cell shows 104 s and 106 s retention, respectively. The single-bit CAM cell shows lifelong (10 years) retention. © 2023 The Authors. Published by American Chemical Society

ACS Applied Electronic Materials

Ferroelectric Content-Addressable Memory Cells with IGZO Channel: Impact of Retention Degradation on the Multibit Operation

A high-frequency sensor-based system is proposed for evaluating the degradation of the transformer insulation through the measurement of moisture concentration. The proposed system employs an intelligent open-ended coaxial probe microwave technique. An optimized artificial neural network (ANN) model is designed by selecting appropriate features to obtain accurate dielectric characterization. Redundant feature elimination reduces the computational burden and also bypasses the repeated calibration refresh required to complete RF measurement in the conventional technique. The ANN model is trained in such a way that measured impedance mismatch due to the termination by the sample at the probe end is related to its permittivity. The introduction of an intelligent standardization procedure led to a low error in the measurement of moisture (±3%) with a sensitivity of 0.027/ppm. This method is found to be simple and faster compared with other existing techniques. Due to the advantage of high-speed measurement and low error, this sensing technique is very suitable for transformer condition monitoring. © 1963-2012 IEEE.

IEEE Transactions on Instrumentation and Measurement

Measurement of Moisture in Transformer Insulation Using the Intelligent High-Frequency Sensor System

The effect of corona aging on the surface potential dynamics and charge trap characteristics of silicone rubber alumina nanocomposite are examined using surface potential decay measurement. The aging was carried out by exposing the specimens to corona stress generated by a high-frequency AC multi needle-plane electrode system. The results show that the addition of alumina filler increases the surface potential decay time and maximum trap energy. A reduction in trap depth is observed with the corona aging, and the addition of alumina filler limits the degradation and change in charge trap distribution. The results of an analysis of the space charge behavior of different nanocomposites and their comparison are presented. The space charge variation analysis was carried out under the applied electric field of 20 kV/mm at room temperature using the pulsed electro-acoustic technique (PEA). Based on the results, the charge density, electric field, and charge trap distribution were deduced. It is concluded that the space charge concentration and enhancement in the electric field of the aged material increases with aging duration and it is maximum in the case of 60 min corona-aged pure silicone rubber. Analysis of the recovery of the charge dynamics of the sample after corona discharges at the different time intervals shows that the recovery of trap distribution is faster for a virgin sample and slower for the sample with 5 wt% of alumina. © 2023 Society of Plastics Engineers.

Polymer Composites

Investigation of charge dynamics in the corona-aged silicone rubber alumina nanocomposite

Zn1-xNixO nanoparticles at a concentration (2%) with pH variation (4, 5, 8 and 9) are successfully synthesized using the solvothermal method. ZnO nanoparticle has a hexagonal wurtzite structure when synthesized at acidic and basic conditions. In pH, the solution is calculated from 4 to 9 by the composed addition of NaOH and HCl. The structural properties are studied from XRD and TEM. The average particle size is found to be 13.2 nm using the Debye Scherrer formula and optical properties are analyzed through UV–Visible, FTIR, & PL. From the absorption spectra, it is observed that the bandgap energy is inversely proportional to the particle size. UV–Vis and PL are used to study the optical behavior of the samples. The magnetic behavior of Zn1-xNixO exhibit changing behavior from paramagnetic to superparamagnetic structure with increases in their pH values. © 2023 Indian Chemical Society