In a significant academic achievement, Dr Soumyajyoti Biswas, Assistant Professor and Scholars  Ms Diksha and Mr Gunnemeda Eswar in the Department of Physics, has published an insightful paper in the prestigious Q1 journal, Physical Review E. The paper, titled “Prediction of depinning transitions in interface models using Gini and Kolkata indices,” presents a novel approach to understanding the complex phenomena of depinning transitions in physical systems.

The research introduces the use of Gini and Kolkata indices as predictive tools, offering a fresh perspective that could pave the way for new discoveries in the field. This publication not only underscores Dr. Biswas’s expertise but also enhances the university’s reputation as a hub for cutting-edge research.
The Department of Physics congratulates Dr. Biswas on this remarkable accomplishment and looks forward to the continued impact of his work on the scientific community.

Abstract

The intermittent dynamics of driven interfaces through disordered media and its subsequent depinning for large enough driving force is a common feature for a myriad of diverse systems, starting from mode-I fracture, vortex lines in superconductors, and magnetic domain walls to invading fluid in a porous medium, to name a few. In this work, we outline a framework that can give a precursory signal of the imminent depinning transition by monitoring the variations in sizes or the inequality of the intermittent responses of a system that are seen prior to the depinning point. In particular, we use measures traditionally used to quantify economic inequality, i.e., the Gini index and the Kolkata index, for the case of the unequal responses of precritical systems.

The crossing point of these two indices serves as a precursor to imminent depinning. Given a scale-free size distribution of the responses, we calculate the expressions for these indices, evaluate their crossing points, and give a recipe for forecasting depinning transitions.We apply this method to the Edwards-Wilkinson, Kardar-Parisi-Zhang, and fiber bundle model interface with variable interaction strengths and quenched disorder. The results are applicable for any interface dynamics undergoing a depinning transition.

Explanation of Research in Layperson’s Terms

Many different physical systems, from cracking in materials to the movement of magnetic fields, share a common underlying behavior – they all involve an “interface” or boundary that moves through a disordered, or irregular, medium. As this interface moves, it often gets “pinned” or stuck in place by the disorder in the medium. However, as the driving force on the interface increases, there comes a point where the interface suddenly “depins” and starts moving much more freely. This transition from a pinned to a depinned state is called the “depinning transition” and it’s an important phenomenon in many areas of science and engineering.

In this work we have found a way to detect when this depinning transition is about to happen, before it actually occurs. We do this by looking at the sizes or magnitudes of the intermittent, or irregular, responses of the system as the driving force increases. Specifically, we use two measures that are traditionally used to quantify economic inequality – the Gini index and the Kolkata index. These give a way to track how “unequal” or unevenly distributed the sizes of the responses are. We found that when these two inequality measures cross each other, it serves as a precursor or early warning sign that the depinning transition is imminent. This is a powerful result because being able to predict when depinning will happen is very useful in fields like material science, superconductivity, and fluid dynamics, where controlling these phase transitions is important. By monitoring these inequality measures, one can may be able to forecast depinning events before they occur, which could lead to better design and control of these systems.

Title of Research paper in the Citation Format

Diksha, G. Eswar, and S. Biswas, Prediction of depinning transitions in interface models using Gini and Kolkata indices, Physical Review E 109, 044113 (2024).
DOI: https://doi.org/10.1103/PhysRevE.109.044113

Practical Implementation or the Social Implications Associated with it

Prediction of imminent transition has implications in a wide range of disciplines, including stability of mechanical structures (buildings, aircraft, bridges, etc.), extraction of oil (fracking) to the largest scale of mechanical failure i.e., earthquakes.

In this fig. the time series of avalanche sizes is shown along with the time variations of g and k for the quenched Edwards-Wilkinson model as a prototype. Here the crossing of g and k occurs prior to the depinning transition point (the last avalanche in the series). Therefore, the crossing of g and k can serve as a good indicator of an imminent depinning transition.

Collaborations

This work is done with the PhD student Ms Diksha and the BSc student Mr Gunnemeda Eswar.

Future Research Plans

Future research plans include applications of the methods developed here to be applied to real-life physical structures for their stability analysis and predictions of impending catastrophes.

The Department of Physics is thrilled to announce a remarkable milestone in sustainable technology. Dr Sabyasachi Mukhopadhyay, Associate Professor and Ms Sreelekha Bhuvaneswari, BSc student has been officially granted a patent for their groundbreaking invention: “A fibre material with moisture retention capacity with thermal tolerance and a method for manufacture of the same.”

This pioneering material, distinguished by its Application Number 202141023375, stands at the forefront of cooling technology. It promises to enhance thermal regulation while prioritising environmental sustainability.

Dr Mukhopadhyay’s invention is poised to make significant contributions to the field of material science, offering a versatile solution that holds potential applications across various industries. The department extends its heartfelt congratulations to the duo on this significant achievement and looks forward to the positive impact his work will continue to have on our community and beyond.

Abstract:

The project, with the patent application number 202141023375, develops a methodology to design a fabric cloth that would replace the use of air conditioners. This cloth design is inspired by Saharan silver ants which regulate their body temperatures in the scorching desert heat and also from the cooling properties of clay. This research would significantly scale down the usage of AC and other cooling devices in warm places, thus reducing the use of electricity and emission of greenhouse gases to the environment. As this cloth would be environment friendly with long durability and cost-efficiency, Sreelekha hopes that this research would bridge the socioeconomic divide of haves and have-nots between communities.

Explanation of the Research in Layperson’s Terms :

Using room conditioning AC during these times, especially with lower temperatures is very risky. Virus spread with closed circulated air or prolonged cold temperatures while breathing, so thus using air conditioning is bad. With this in mind, we need an efficient way of cooling in the snoring temperatures. We propose developing a fabric that integrates clay (Its primary mineral is kaolinite; clay may be generally described as 40% aluminium oxide, 46% silicon oxide, and 14% water.) in its synthesis; clay is known for its cooling properties given enough water to retail and proper reflection techniques for heat throughout the fabric inspired from uniquely shaped hairs with triangular cross-sections as in arrangement employed by the Saharan silver ants. This model not only conserves energy compared to room cooling but also is very practical, wherein we can dampen the fabric with the least water and retain its cooling for long hours. This Fabric could be employed in a variety of settings, for example, in making carpets and curtains in a house to keep the room temperature regulated.

Practical Implementation and Social Implications:

The research would significantly scale down the usage of AC and other cooling devices in warm places, thus reducing the use of electricity and emission of greenhouse gases to the environment. As this cloth would be environment friendly with long durability and cost-efficiency, Sreelekha hopes that this research would bridge the socioeconomic divide of haves and have-nots between communities.

The Title of Patent in the Citation Format

“A fibre material with moisture retention capacity with thermal tolerance and a method for manufacture of the same” with Application Number: 202141023375

Collaborations:

Prof. Seeram Ramakrishna, Professor of Materials, National University of Singapore

Future Research Plans:

The forthcoming endeavour encompasses the commercialisation of this pioneering concept to render it widely accessible and applicable on a larger scale.