arXiv subjects

Ruchi Pandey

Publications and source records attributed to Ruchi Pandey.

21 records · Page 2Linked to original sources

arXiv2022

Parametric Models for DOA Trajectory Localization

Directions of arrival (DOA) estimation or localization of sources is an important problem in many applications for which numerous algorithms have been proposed. Most localization methods use block-level processing that combines multiple data snapshots to estimate DOA within a block. The DOAs are assumed to be constant within the block duration. However, these assumptions are often violated due to source motion. In this paper, we propose a signal model that captures the linear variations in DOA within a block. We applied conventional beamforming (CBF) algorithm to this model to estimate linear DOA trajectories. Further, we formulate the proposed signal model as a block sparse model and subsequently derive sparse Bayesian learning (SBL) algorithm. Our simulation results show that this linear parametric DOA model and corresponding algorithms capture the DOA trajectories for moving sources more accurately than traditional signal models and methods.

eess.SP↗

arXiv2021

Photoionization modeling of the dusty nova V1280 Scorpii

We perform photoionization modeling of the dusty nova V1280 Scorpii (V1280 Sco) with an aim to study the changes in the physical and chemical parameters. We model pre and post dust phase, optical and near-Infrared (NIR), spectra using the photoionization code \textsc{cloudy}, v.17.02, considering a two-component (low density and high density region) model. From the best-fit model, we find that the temperature and luminosity of the central ionizing source in the pre-dust phase are in the range 1.32 - 1.50 $\times 10^4$ K and 2.95 - 3.16 $\times 10^{36}$ ergs$^{-1}$, respectively, which increase to 1.58 - 1.62 $\times 10^4$ K and 3.23 - 3.31 $\times 10^{36}$ ergs$^{-1}$, respectively, in the post-dust phase. It is found that a very high hydrogen density ($\sim 10^{13} - 10^{14}$ cm$^{-3}$) is required for the generation of spectra properly. Dust condensation conditions are achieved at high ejecta density ($\sim 3.16 \times 10^{8}$cm$^{-3}$) and low temperature ($\sim$2000 K) in the outer region of the ejecta. It is found that a mixture of small (0.005 - 0.25$μ$m) amorphous carbon dust grains and large (0.03 - 3.0$μ$m) astrophysical silicate dust grains iis present n the ejecta in the post-dust phase. Our model yields very high elemental abundance values as C/H = 13.5 - 20, N/H = 250, O/H = 27 - 35, by number, relative to solar in the ejecta, during the pre-dust phase, which decrease in the post-dust phase.

astro-ph.SR↗

arXiv2018

Deep Learning For Computer Vision Tasks: A review

Deep learning has recently become one of the most popular sub-fields of machine learning owing to its distributed data representation with multiple levels of abstraction. A diverse range of deep learning algorithms are being employed to solve conventional artificial intelligence problems. This paper gives an overview of some of the most widely used deep learning algorithms applied in the field of computer vision. It first inspects the various approaches of deep learning algorithms, followed by a description of their applications in image classification, object identification, image extraction and semantic segmentation in the presence of noise. The paper concludes with the discussion of the future scope and challenges for construction and training of deep neural networks.

cs.CV↗