Modelling & Simulation of Power Oscillation Damping Controller

The main aim of this paper is to regulate power oscillation that is major concern associated with facility operation. During this analysis work is on SSSC-based power oscillation damping controller, which may damp the ability oscillations occurring because of the any modification within the line like unforeseen modification in load of line, prevalence of fault, transmission line switch and short circuit. During this work Simulation model of the 2 machine infinite bus system exploitation SSSC & power oscillation damping controller has been drained MATLAB/SIMULIINK and facility tool chest is employed for simulation purpose. These simulation models are setup into MATLAB primarily based power grid tool cabinet (PST) for his or her transient stability analysis. it's determined that with the correct modification of section of the injection of voltages through SSSC, electrical phenomenon & inductive compensation is provided by that enlarged and cut within the active power severally of line is done consistent with the mentioned power demand, however once solely the SSSC is employed within the line the subsiding time and amplitude of power oscillations area unit a lot of as compared once SSSC is employed with power oscillation damping controller. Once in 2 machine infinite bus systems 3-phase fault analysis is finished then it's determined that that the clearance time is a smaller amount once the system is supplied with SSSC and power oscillation damping controller along or togethe

A Null-model Exhibiting Synchronized Dynamics in Uncoupled Oscillators

The phenomenon of phase synchronization of oscillatory systems arising out of feedback coupling is ubiquitous across physics and biology. In noisy, complex systems, one generally observes transient epochs of synchronization followed by non-synchronous dynamics. How does one guarantee that the observed transient epochs of synchronization are arising from an underlying feedback mechanism and not from some peculiar statistical properties of the system? This question is particularly important for complex biological systems where the search for a non-existent feedback mechanism may turn out be an enormous waste of resources. In this article, we propose a null model for synchronization motivated by expectations on the dynamical behaviour of biological systems to provide a quantitative measure of the confidence with which one can infer the existence of a feedback mechanism based on observation of transient synchronized behaviour. We demonstrate the application of our null model to the phenomenon of gait synchronization in free-swimming nematodes, C. elegans

The Tracking Tapered Gridded Estimator (TTGE) for the power spectrum from drift scan observations

Intensity mapping with the redshifted 21-cm line is an emerging tool in cosmology. Drift scan observations, where the antennas are fixed to the ground and the telescope's pointing center (PC) changes continuously on the sky due to earth's rotation, provide broad sky coverage and sustained instrumental stability needed for 21-cm intensity mapping. Here we present the Tracking Tapered Grided Estimator (TTGE) to quantify the power spectrum of the sky signal estimated directly from the visibilities measured in drift scan radio interferometric observations. The TTGE uses the data from the different PC to estimate the power spectrum of the signal from a small angular region located around a fixed tracking center (TC). The size of this angular region is decided by a suitably chosen tapering window function which serves to reduce the foreground contamination from bright sources located at large angles from the TC. It is possible to cover the angular footprint of the drift scan observations using multiple TC, and combine the estimated power spectra to increase the signal to noise ratio. Here we have validated the TTGE using simulations of $154 \, {\rm MHz}$ MWA drift scan observations. We show that the TTGE can recover the input model angular power spectrum $C_{\ell}$ within $20 \%$ accuracy over the $\ell$ range $40 < \ell < 700$.Comment: Accepted for publication in MNRA

COVID-19 lockdown induced changes in NO2 levels across India observed by multi-satellite and surface observations

© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.We have estimated the spatial changes in NO 2levels over different regions of India during the COVID-19 lockdown (25 March-3 May 2020) using the satellite-based tropospheric column NO 2observed by the Ozone Monitoring Instrument (OMI) and the Tropospheric Monitoring Instrument (TROPOMI), as well as surface NO 2concentrations obtained from the Central Pollution Control Board (CPCB) monitoring network. A substantial reduction in NO 2levels was observed across India during the lockdown compared to the same period during previous business-as-usual years, except for some regions that were influenced by anomalous fires in 2020. The reduction (negative change) over the urban agglomerations was substantial (~20 %-40 %) and directly proportional to the urban size and population density. Rural regions across India also experienced lower NO 2values by ~15 %-25 %. Localised enhancements in NO 2associated with isolated emission increase scattered across India were also detected. Observed percentage changes in satellite and surface observations were consistent across most regions and cities, but the surface observations were subject to larger variability depending on their proximity to the local emission sources. Observations also indicate NO 2enhancements of up to~25%during the lockdown associated with fire emissions over the north-east of India and some parts of the central regions. In addition, the cities located near the large fire emission sources show much smaller NO 2reduction than other urban areas as the decrease at the surface was masked by enhancement in NO 2due to the transport of the fire emissions.Peer reviewedFinal Published versio

On a model-based approach to improve intranasal spray targeting for respiratory viral infections

The nasopharynx, at the back of the nose, constitutes the dominant initial viral infection trigger zone along the upper respiratory tract. However, as per the standard recommended usage protocol (“Current Use”, or CU) for intranasal sprays, the nozzle should enter the nose almost vertically, resulting in sub-optimal nasopharyngeal drug deposition. Through the Large Eddy Simulation technique, this study has replicated airflow under standard breathing conditions with 15 and 30 L/min inhalation rates, passing through medical scan-based anatomically accurate human airway cavities. The small-scale airflow fluctuations were resolved through use of a sub-grid scale Kinetic Energy Transport Model. Intranasally sprayed droplet trajectories for different spray axis placement and orientation conditions were subsequently tracked via Lagrangian-based inert discrete phase simulations against the ambient inhaled airflow field. Finally, this study verified the computational projections for the upper airway drug deposition trends against representative physical experiments on sprayed delivery performed in a 3D-printed anatomic replica. The model-based exercise has revealed a new “Improved Use” (or, IU) spray usage protocol for viral infections. It entails pointing the spray bottle at a shallower angle (with an almost horizontal placement at the nostril), aiming slightly toward the cheeks. From the conically injected spray droplet simulations, we have summarily derived the following inferences: (a) droplets sized between 7–17 μm are relatively more efficient at directly reaching the nasopharynx via inhaled transport; and (b) with realistic droplet size distributions, as found in current over-the-counter spray products, the targeted drug delivery through the IU protocol outperforms CU by a remarkable 2 orders-of-magnitude

On a model-based approach to improve intranasal spray targeting for respiratory viral infections

The nasopharynx, at the back of the nose, constitutes the dominant initial viral infection trigger zone along the upper respiratory tract. However, as per the standard recommended usage protocol (“Current Use”, or CU) for intranasal sprays, the nozzle should enter the nose almost vertically, resulting in sub-optimal nasopharyngeal drug deposition. Through the Large Eddy Simulation technique, this study has replicated airflow under standard breathing conditions with 15 and 30 L/min inhalation rates, passing through medical scan-based anatomically accurate human airway cavities. The small-scale airflow fluctuations were resolved through use of a sub-grid scale Kinetic Energy Transport Model. Intranasally sprayed droplet trajectories for different spray axis placement and orientation conditions were subsequently tracked via Lagrangian-based inert discrete phase simulations against the ambient inhaled airflow field. Finally, this study verified the computational projections for the upper airway drug deposition trends against representative physical experiments on sprayed delivery performed in a 3D-printed anatomic replica. The model-based exercise has revealed a new “Improved Use” (or, IU) spray usage protocol for viral infections. It entails pointing the spray bottle at a shallower angle (with an almost horizontal placement at the nostril), aiming slightly toward the cheeks. From the conically injected spray droplet simulations, we have summarily derived the following inferences: (a) droplets sized between 7–17 μm are relatively more efficient at directly reaching the nasopharynx via inhaled transport; and (b) with realistic droplet size distributions, as found in current over-the-counter spray products, the targeted drug delivery through the IU protocol outperforms CU by a remarkable 2 orders-of-magnitude

Gold nanoparticles-reduced graphene oxide based electrochemical immunosensor for the cardiac biomarker myoglobin

A composite consisting of gold nanoparticles and reduced graphene oxide (AuNPs@rGO) was electrochemically prepared in-situ on a screen printed electrode (SPE) which then was used as an immunosensor for the cardiac biomarker myoglobin. The nanocomposite was characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM), atomic force microscopy, FTIR and electrochemical impedance spectroscopy. For FTIR, TEM and SEM, the deposition was done on indium tin oxide coated glass plates. The immunosensor was obtained by immobilization of in-house generated antibody against cardiac myoglobin on the electrode surface. The immunosensing response was monitored using differential pulse voltammetry, which showed a reduction peak at ~ −0.5 V (vs. Ag/AgCl). The reduction peak arises from the reduction of iron moiety present in the heme group of myoglobin. The immunosensor exhibited dynamic linearity range from 1 ng.mL−1 to 1400 ng.mL−1 with the detection limit of ~0.67 ng.mL−1 for cardiac myoglobin. The obtained result was almost eight times better (in terms of detection limit) than that obtained with ELISA tests (with detection limit of ~4 ng.mL−1) using the same antibodies. The immunosensor was applied to analyze spiked serum samples also

Climate hazards are threatening vulnerable migrants in Indian megacities

In recent decades, India has witnessed a rapid pace of migration from areas with intensive agriculture to populated megacities, which are faced with increasing threat from climate hazards. Greater attention is needed for vulnerable new migrants who lack necessary resources when designing adaptation and mitigation policies

Enhanced frequency upconversion in Ho3+/Yb3+/Li+:YMoO4 nanophosphors for photonic and security ink applications

The YMoO4 nanophosphors codoped with Ho3+/Yb3+/Li+ ions synthesized by the chemical coprecipitation method have been structurally characterized by using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM) techniques. The TEM bright field imaging shows that the developed nanophosphors are crystalline in nature with particle size similar to 45 nm. The upconversion (UC) emission spectra upon excitation at 980 nm of the nanophosphors at low pump power (<900 mW) show the emission peaks in the UV, green, and red regions, whereas at high pump power (>= 900 mW) an intense broad band ranging from 400-900 nm along with a UV band has been observed. The enhancement of about similar to 104 times corresponding to the green band in the Ho3+-Yb3+-Li+ codoped nanophosphors compared to that of the Ho3+ singly doped nanophosphors has been observed. This enhancement is caused by the energy transfer from the Yb3+ to Ho3+ ions and modified the local crystal field developed around the rare earth ions. A higher value of the slope (i.e., n similar to 6.38) for broad band emission within the 944 mW-1200 mW pump power region in the Ho3+-Yb3+-Li+ codoped nanophosphors is found to be due to the involvement of the photon avalanche population process but it is not related to the black body radiation. The intense peak at similar to 564 nm and similar to 648 nm for the broad band emission is attributed to the charge transfer luminescence of codoped nanophosphors, which is related to the oxygen ion present in the MoO4 group and Yb3+ ion. The observations described in this paper may be of significant interest for developing the visible upconverters, security ink, and novel devices for displays in the low and high pump power region. Published by AIP Publishing