arXiv subjects

Navneet Kumar

Publications and source records attributed to Navneet Kumar.

6 recordsLinked to original sources

arXiv2024

Choice of Reference Surfaces to assess Plant Health through leaf scale temperature monitoring

We use infrared thermal imaging to remotely monitor the temperature of the leaves and plant which in turn is an indicative of their health and stress; in particular water stress. A series of experiments were conducted using Fluke TiX580 thermal imager on tomato plants to correlate the leaf temperature to different stages such as healthy, dying/wilted, and completely dead/dry. The leaf temperature was compared to a series of paper-based reference surface temperatures; these are of different colors and some are dry while some are wet. All the reference surfaces were insulated at the bottom ensuring the heat interaction between their top surfaces and ambient only. The surfaces were kept sufficiently far from one another. The healthy leaf temperature was found to be close to that of white dry and black wet reference surfaces whereas the wilted and dying leaves temperature were observed to range between yellow and red signifying that this temperature range can better predict the onset of water stress in the leaves. The completely dead/dry leaves were observed to range between green and blue dry surfaces, respectively. However, most of the dead leaf temperature data was found to be accumulated closer to the green surface signifying green dry surface can better indicate a dead leaf condition. The dying leaves were observed to exhibit 8-10 degree centigrade higher temperatures as compared to the healthy leaves in similar ambient conditions. Temperature-based health assessment provides us with a timely intervention to prevent leaf death compared to the optical monitoring since IR images revealed elevated leaf temperature 2-3 days before the optical unhealthiness (appearance of yellowness on the leaf) was noticed.

physics.bio-ph↗

arXiv2024

Evaporation limited spreading of ethanol on rectangular porous strips: an experimental and theoretical investigation

Wicking is a widely studied process in both natural and artificial systems. In many industrial applications, such as heat pipes, the wicking liquid evaporates to regulate temperature effectively. This study focuses on a simpler scenario where liquid ethanol climbs a vertically oriented filter paper FP under laboratory conditions, facilitating mass loss through evaporation and inducing cooling. Three filter papers with different permeability values were used, and three diagnostic methods optical imaging, thermal imaging, and precision weighing were employed to understand the dynamics of the process. The results showed a steady state height Lc significantly lower than Jurins limit in all cases, indicating that evaporative mass loss, and not gravity, limits the process. For instance, the filter paper 1005FP, with a capillary radius of 59microm and an average pore size of 2.50microm, would reach a Jurins height of 9.6cm with ethanol if evaporation were not allowed. However, when evaporation occurred, the height reduced to 1.2cm, an eightfold decrease, a similar reduction by a factor of 3 was observed for 1004FP. Further, thermal imaging revealed a non constant temperature distribution along the filter paper, with an unusual temperature inversion near the middle of the wicking liquid. This observation led to an improvement of the Constant Evaporation Model CEM by Fries et al 2008 by accounting for the nonlinear behavior of evaporation rates varying with vertical position. This new model termed the Non-Constant Evaporation Model NCEM, tested two power-law relations for evaporation rates , both of which successfully captured the key features of the process.

physics.flu-dyn↗

arXiv2024

Study of $\pi$, K, and p production in high multiplicity pp collisions at $\sqrt{s}$ = 13 TeV with ALICE at the LHC

High multiplicity proton-proton and proton-lead collisions at LHC energies exhibit similar signatures to those observed in Pb-Pb collisions (i.e. the strangeness enhancement, the ridge behaviours etc.), that were commonly attributed to the formation of the Quark-Gluon Plasma. In this contribution, the measurements of $\pi$, K, and p transverse momentum spectra in the rapidity region |y| < 0.5 for various multiplicity classes in pp, p-Pb and A-A collisions with the ALICE detector at the LHC will be presented. Various results, including the integrated particle yields and particle ratios as a function of charged particle multiplicity for different systems and energies, will be discussed.

hep-ex↗

arXiv2022

Experimental observations on interaction between a root and droplets in relation to aeroponic agriculture

Aeroponics or Soil-less agriculture is a relatively new and recent type of practice, where plants are grown without soil while nutrient-rich water is provided via an atomized spray system to the suspended roots. Spray nozzles are easy-to-use in supplying water (and fertilizers) to (mainly) the roots and root hairs of the desired crop (or plant) for production. We characterize a spray nozzle delivering water vertically above against the gravity by measuring, experimentally, its (a) spray drift, (b) spray height, (c) maximum spray angle, (d) spray width, and (e) droplets sizes. Experiments were carried out at different inlet pressures and a majority of the above mentioned parameters were obtained by processing the images captured using optical (or high speed) camera, sometimes along a plane lighted by a high-power laser source. We also studied the spray (or jet) behaviour at different vertical heights and different horizontal planes using a unique polythene sponge method. We studied the mass flow rate, the absorption rate, and droplet size dynamics (as a function of time and pressure) using this method. The water drop/droplet interaction was also studied in the case of simpler porous and impervious surfaces as well. We believe that this study can be extrapolated to other nozzles (especially sprays) to obtain similar characteristic parameters. This study, hence, is critical in selecting the desired spray system for a given canopy and is also expected to be of some use in controlled agricultural practices such as in greenhouses and apartment rooms.

physics.flu-dyn↗

arXiv2021

Samanantar: The Largest Publicly Available Parallel Corpora Collection for 11 Indic Languages

We present Samanantar, the largest publicly available parallel corpora collection for Indic languages. The collection contains a total of 49.7 million sentence pairs between English and 11 Indic languages (from two language families). Specifically, we compile 12.4 million sentence pairs from existing, publicly-available parallel corpora, and additionally mine 37.4 million sentence pairs from the web, resulting in a 4x increase. We mine the parallel sentences from the web by combining many corpora, tools, and methods: (a) web-crawled monolingual corpora, (b) document OCR for extracting sentences from scanned documents, (c) multilingual representation models for aligning sentences, and (d) approximate nearest neighbor search for searching in a large collection of sentences. Human evaluation of samples from the newly mined corpora validate the high quality of the parallel sentences across 11 languages. Further, we extract 83.4 million sentence pairs between all 55 Indic language pairs from the English-centric parallel corpus using English as the pivot language. We trained multilingual NMT models spanning all these languages on Samanantar, which outperform existing models and baselines on publicly available benchmarks, such as FLORES, establishing the utility of Samanantar. Our data and models are available publicly at https://ai4bharat.iitm.ac.in/samanantar and we hope they will help advance research in NMT and multilingual NLP for Indic languages.

cs.CL↗

arXiv2019

Formation of a hard surface layer during drying of a heated porous media

We report surface hardening or crust formation, unlike caking, during drying when a confined porous medium was heated from above using IR radiation. These crusts have higher strength than their closest counterparts such as sandcastles and mud-peels which essentially are clusters of partially wet porous medium. Observed higher strength of the crusts is mostly due to surface tension between the solid particles which are connected by liquid bridges (connate water). Qualitative (FTIR) and quantitative (TGA) measurements confirm the presence of trapped water within the crust. Amount of the trapped water was ~1.5% (this is about 10 times higher than in the samples with caking) which was confirmed using SEM images. Further, in the fixed particle sizes case, the crust thickness varied slightly (10-20 particle diameters only for cases with external heating) while with the natural sand whole porous column was crusted; surprisingly, crust was also found with the hydrophobic glass beads. Fluorescein dye visualization technique was used to determine the crust thickness. We give a power law relation between the crust thickness and the incident heat flux for various particle sizes. The strength of the crust decreases drastically with increasing hydrophilic spheres diameter while it increases with higher surface temperature.

cond-mat.soft↗