arXiv subjects

Karthik R

Publications and source records attributed to Karthik R.

14 recordsLinked to original sources

arXiv2025

Controlled Growth of Bronze Telluride for Scalable Thermoelectric Energy Harvesting

With the growing demand for sustainable and decentralized energy solutions, thermoelectric energy harvesting has emerged as a promising technology for directly converting waste heat into electricity through solid state, environmentally friendly means. Among copper chalcogenides, Cu2Te is a notable p-type material due to its degenerate semiconducting nature and low thermal conductivity. In this study, we present a sustainable synthesis strategy for Sn-doped Cu2Te referred to as bronze telluride (BT) via a chemical vapor deposition (CVD) assisted tellurization process using pre-alloyed Cu Sn (bronze) powder. The resulting BT exhibited an enhanced thermoelectric figure of merit (ZT) of 1 at 500 K. To assess practical applicability, BT was integrated with n type galena (PbS) in a cascaded p n thermoelectric module, which generated 2.8 mV across a temperature gradient of 35 K, demonstrating its potential for medium- to high-temperature waste heat recovery. Furthermore, thermodynamic calculations and density functional theory (DFT) simulations provided insights into the formation mechanism of Cu2Te and the thermoelectric behaviour of BT. This work introduces an efficient, scalable, and environmentally responsible pathway for developing copper-based thermoelectric materials using industrially relevant precursors.

cond-mat.mtrl-sci↗

arXiv2025

Pyrite Bismuth Telluride Heterojunction for Hybrid Electromagnetic to Thermoelectric Energy Harvesting

The rapid proliferation of wireless networks and connected devices has led to pervasive electromagnetic (EM) energy dissipation into the environment, an underutilized resource for energy harvesting. Here, we demonstrate a pyrite (FeS$_2$)-bismuth telluride (Bi$_2$Te$_3$) heterojunction that enables hybrid electromagnetic-to-thermoelectric energy conversion. Fabricated via a simple cold-press compaction of powders, the heterojunction forms a Schottky interface at FeS$_2$, facilitating efficient RF absorption and localized heating. This heat is harvested by Bi$_2$Te$_3$ through thermoelectric conversion. Under 35~MHz RF irradiation at 1~W input power, the device achieved a local temperature rise of 46~$^\circ$C and a thermal gradient of 5.5~K across the Bi$_2$Te$_3$, resulting in a peak power density of approximately 13~mW/cm$^2$. Molecular dynamics (MD) simulations and density functional theory (DFT) calculations further elucidate the heat transport behavior and interfacial thermoelectric performance. This work introduces a new class of heterostructures for RF-responsive energy harvesting, offering a scalable route toward self-powered IoT and wireless sensing systems.

cond-mat.mtrl-sci↗

arXiv2025

Localized Radiofrequency Heating for Enhanced Thermoelectric Energy Generation Using Natural Galena Ore

The efficiency of thermoelectric devices can be significantly enhanced by maintaining a stable temperature gradient, which can be achieved through localized heating. Radio waves serve as an ideal heat source for this purpose. In this study, we demonstrate the enhancement of thermoelectric performance in earth-abundant natural ore Galena (PbS) through localized radio frequency (RF) heating. RF heating experiments conducted at frequencies between \SI{35}{MHz} and \SI{45}{MHz} induced substantial localized heating in PbS, generating a temperature gradient of \SI{32}{K}. This resulted in a Seebeck voltage of \SI{-5.8}{mV/K}, approximately 13 times greater than the conventional Seebeck coefficient of PbS (\SI{440}{\micro V/K}). Additionally, a power factor of \SI{151}{mWm^{-1}K^{-2}} and an overall RF to thermoelectric conversion efficiency of 15\% were achieved. Molecular dynamics simulations corroborate the experimental findings, providing insights into the mechanism of thermal transport and RF-induced heating in PbS. These results highlight the potential of localized RF heating as an effective strategy for enhancing thermoelectric performance, with promising implications for ambient thermoelectric energy harvesting applications.

cond-mat.mtrl-sci↗

arXiv2024

Perturbations of Black Holes Surrounded by Anisotropic Matter Field

Our research aims to probe the anisotropic matter field around black holes using black hole perturbation theory. Black holes in the universe are usually surrounded by matter or fields, and it is important to study the perturbation and the characteristic modes of a black hole that coexists with such a matter field. In this study, we focus on a family of black hole solutions to Einstein's equations that extend the Reissner-Nordstr\"{o}m spacetime to include an anisotropic matter field. In addition to mass and charge, this type of black hole possesses additional hair due to the negative radial pressure of the anisotropic matter. We investigate the perturbations of the massless scalar and electromagnetic fields and calculate the quasinormal modes (QNMs). We also study the critical orbits around the black hole and their properties to investigate the connection between the eikonal QNMs, black hole shadow radius, and Lyapunov exponent. Additionally, we analyze the grey-body factors and scattering coefficients using the perturbation results. Our findings indicate that the presence of anisotropic matter fields leads to a splitting in the QNM frequencies compared to the Schwarzschild case. This splitting feature is also reflected in the shadow radius, Lyapunov exponent, and grey-body factors.

gr-qc↗

arXiv2024

Enhanced heat dissipation and lowered power consumption in electronics using two-dimensional hexagonal boron nitride coatings

Miniaturization of electronic components has led to overheating, increasing power consumption and causing early circuit failures. Conventional heat dissipation methods are becoming inadequate due to limited surface area and higher short-circuit risks. This study presents a fast, low-cost, and scalable technique using 2D hexagonal boron nitride (hBN) coatings to enhance heat dissipation in commercial electronics. Inexpensive hBN layers, applied by drop casting or spray coating, boost thermal conductivity at IC surfaces from below 0.3 W/m-K to 260 W/m-K, resulting in over double the heat flux and convective heat transfer. This significantly reduces operating temperatures and power consumption, as demonstrated by a 17.4% reduction in a coated audio amplifier circuit board. Density functional theory indicates enhanced interaction between 2D hBN and packaging materials as a key factor. This approach promises substantial energy and cost savings for large-scale electronics without altering existing manufacturing processes.

cond-mat.mtrl-sci↗

arXiv2024

Spinning LQG black hole as a particle accelerator

We demonstrate that the spinning LQG black hole can act as a cosmic particle accelerator. The LQG solution is singularity-free and can possess spin greater than that of a Kerr black hole. The additional black hole hair, arising from quantum effects, significantly influences the particle dynamics around the black hole. Under suitable physical conditions, the center-of-mass energy can grow arbitrarily high during the collision of two generic particles in the spacetime of an extremal black hole. In the non-extremal case, there exists a finite upper bound on the center-of-mass energy, the maximum value of which depends on the LQG parameter. These results are particularly interesting from an astrophysical perspective, especially in the context of probing Planck-scale physics.

gr-qc↗

arXiv2020

Speech Emotion Recognition using Support Vector Machine

In this project, we aim to classify the speech taken as one of the four emotions namely, sadness, anger, fear and happiness. The samples that have been taken to complete this project are taken from Linguistic Data Consortium (LDC) and UGA database. The important characteristics determined from the samples are energy, pitch, MFCC coefficients, LPCC coefficients and speaker rate. The classifier used to classify these emotional states is Support Vector Machine (SVM) and this is done using two classification strategies: One against All (OAA) and Gender Dependent Classification. Furthermore, a comparative analysis has been conducted between the two and LPCC and MFCC algorithms as well.

eess.AS↗

arXiv2020

Performance Analysis of Adaptive Noise Cancellation for Speech Signal

This paper gives a broader insight on the application of adaptive filter in noise cancellation during various processes where signal is transmitted. Adaptive filtering techniques like RLS, LMS and normalized LMS are used to filter the input signal using the concept of negative feedback to predict its nature and remove it effectively from the input. In this paper a comparative study between the effectiveness of RLS, LMS and normalized LMS is done based on parameters like SNR (Signal to Noise ratio), MSE (Mean squared error) and cross correlation. Implementation and analysis of the filters are done by taking different step sizes on different orders of the filters.

cs.SD↗

arXiv2020

Medicine Strip Identification using 2-D Cepstral Feature Extraction and Multiclass Classification Methods

Misclassification of medicine is perilous to the health of a patient, more so if the said patient is visually impaired or simply did not recognize the color, shape or type of medicine strip. This paper proposes a method for identification of medicine strips by 2-D cepstral analysis of their images followed by performing classification that has been done using the K-Nearest Neighbor (KNN), Support Vector Machine (SVM) and Logistic Regression (LR) Classifiers. The 2-D cepstral features extracted are extremely distinct to a medicine strip and consequently make identifying them exceptionally accurate. This paper also proposes the Color Gradient and Pill shape Feature (CGPF) extraction procedure and discusses the Binary Robust Invariant Scalable Keypoints (BRISK) algorithm as well. The mentioned algorithms were implemented and their identification results have been compared.

cs.CV↗

arXiv2020

Radial Based Analysis of GRNN in Non-Textured Image Inpainting

Image inpainting algorithms are used to restore some damaged or missing information region of an image based on the surrounding information. The method proposed in this paper applies the radial based analysis of image inpainting on GRNN. The damaged areas are first isolated from rest of the areas and then arranged by their size and then inpainted using GRNN. The training of the neural network is done using different radii to achieve a better outcome. A comparative analysis is done for different regression-based algorithms. The overall results are compared with the results achieved by the other algorithms as LS-SVM with reference to the PSNR value.

cs.CV↗

arXiv2018

Image Segmentation and Processing for Efficient Parking Space Analysis

In this paper, we develop a method to detect vacant parking spaces in an environment with unclear segments and contours with the help of MATLAB image processing capabilities. Due to the anomalies present in the parking spaces, such as uneven illumination, distorted slot lines and overlapping of cars. The present-day conventional algorithms have difficulties processing the image for accurate results. The algorithm proposed uses a combination of image pre-processing and false contour detection techniques to improve the detection efficiency. The proposed method also eliminates the need to employ individual sensors to detect a car, instead uses real-time static images to consider a group of slots together, instead of the usual single slot method. This greatly decreases the expenses required to design an efficient parking system. We compare the performance of our algorithm to that of other techniques. These comparisons show that the proposed algorithm can detect the vacancies in the parking spots while ignoring the false data and other distortions.

eess.IV↗

arXiv2018

Cubic Spline Interpolation Segmenting over Conventional Segmentation Procedures: Application and Advantages

To design a novel method for segmenting the image using Cubic Spline Interpolation and compare it with different techniques to determine which gives an efficient data to segment an image. This paper compares polynomial least square interpolation and the conventional Otsu thresholding with spline interpolation technique for image segmentation. The threshold value is determined using the above-mentioned techniques which are then used to segment an image into the binary image. The results of the proposed technique are also compared with the conventional algorithms after applying image equalizations. The better technique is determined based on the deviation and mean square error when compared with an accurately segmented image. The image with least amount of deviation and mean square error is declared as the better technique.

eess.IV↗

arXiv2018

Automatic Phone Slip Detection System

Mobile phones are becoming increasingly advanced and the latest ones are equipped with many diverse and powerful sensors. These sensors can be used to study different position and orientation of the phone which can help smartphone manufacture to track about their customers handling from the recorded log. The inbuilt sensors such as the accelerometer and gyroscope present in our phones are used to obtain data for acceleration and orientation of the phone in the three axes for different phone vulnerable position. From the data obtained appropriate features are extracted using various feature extraction techniques. The extracted features are then given to classifier such as neural network to classify them and decide whether the phone is in a vulnerable position to fall or it is in a safe position .In this paper we mainly concentrated on various case of handling the smartphone and classified by training the neural network.

cs.CY↗

arXiv2013

W3-Scrape - A Windows based Reconnaissance Tool for Web Application Fingerprinting

Web Application finger printing is a quintessential part of the Information Gathering phase of (ethical) hacking. It allows narrowing down the specifics instead of looking for all clues. Also an application that has been correctly recognized can help in quickly analyzing known weaknesses and then moving ahead with remaining aspects. This step is also essential to allow a pen tester to customize its payload or exploitation techniques based on the identification so to increase the chances of successful intrusion. This paper presents a new tool "W3-Scrape" for the relatively nascent field of Web Application finger printing that helps automate web application fingerprinting when performed in the current scenarios.

cs.CR↗