Robust fuzzy-sliding mode based UPFC controller for transient stability analysis in autonomous wind-diesel-PV hybrid system

This study presents a comparative study of transient stability and reactive power compensation issues in an autonomous wind–diesel-photovoltaic based hybrid system (HS) using robust fuzzy-sliding mode based unified power flow controller (UPFC). A linearised small-signal model of the different elements of the HS is considered for the transient stability analysis in the HS under varying loading conditions. An IEEE type 1 excitation system is considered for the synchronous generator in the HS, with negligible saturation characteristic, for detailed voltage stability analysis. It is noted from the simulation results that the performance of UPFC is superior to static VAR compensator and static synchronous compensator in improving the voltage profile of the HS. Further, fuzzy and fuzzy-sliding mode based UPFC controller is designed in order to improve the transient performance. Simulation results reflect the robustness of the proposed fuzzy-sliding mode controller for better reactive power management to improve the voltage stability in comparison with the conventional PI and fuzzy-PI controllers. In addition to this, system stability analysis is performed based on eigenvalue, bode and popov for supporting the robustness of the proposed controller

Ultralight (Lμ−Lτ)(L_\mu-L_\tau) vector dark matter interpretation of NANOGrav observations

The angular correlation of pulsar residuals observed by NANOGrav and other pulsar timing array (PTA) collaborations show evidence in support of the Hellings-Downs correlation expected from stochastic gravitational waves (SGW). In this paper, we offer a non-gravitational wave explanation of the observed pulsar timing correlations as caused by an ultra-light $L_{\mu} - L_{\tau}$ gauge boson dark matter (ULDM). ULDM can affect the pulsar correlations in two ways. The gravitational potential of vector ULDM gives rise to a Shapiro time-delay of the pulsar signals and a non-trivial angular correlation (as compared to the scalar ULDM case). In addition, if the pulsars have a non-zero charge of the dark matter gauge group then the electric field of the local dark matter causes an oscillation of the pulsar and a corresponding Doppler shift of the pulsar signal. We point out that pulsars carry a significant charge of muons and thus the $L_{\mu} - L_{\tau}$ vector dark matter contributes to both the Doppler oscillations and the time-delay of the pulsar signals. Our analysis shows that the NANOGrav data has a better fit to the $L_{\mu} - L_{\tau}$ ULDM scenario compared to the SGW or the SGW with Shapiro time-delay hypotheses.Comment: 10 pages, 4 figures. Comments are welcom

SYNTHESIS, CHARACTERIZATION AND ANTIOXIDANT ACTIVITY OF POTASSIUM CIS-DIAQUA-BIS (OXALATO) CHROMATE (III) WITH LEVODOPA AND CARBIDOPA

Objective: These studies focus on the interaction between two clinically active antiparkinsonian drugs L-dopa (L) and carbidopa (C) with the cis-[Cr(C2O4)2(H2O)2]-and evaluation of the synthesized product from a coordination chemistry aspect with respect to the possibility of its antioxidant activity and its therapeutic application in the treatment of Parkinson disease.Methods: The resulting synthesized complexes were characterized by UV-VIS and FTIR spectroscopy. Evaluation of antioxidant activities of this cis-[Cr(C2O4)2(H2O)2]--L-dopa(ML), cis-[Cr(C2O4)2(H2O)2]--carbidopa(MC) and standard butylated hydroxytoluene (BHT) were carried out by using 1,1-diphenyl-1-picrylhydrazyl free radical (DPPH), 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cations and hydrogen peroxide method.Results: The results of spectral analysis of the synthesized products indicate that complexes have a Cr(III) ion coordinated via the carboxylic and amino group. In the reduction of radical DPPH· and the formation of radical monocation ABTS·+the ability to scavenge radical was measured in these experiments by the discoloration of the solution. However, in hydrogen peroxide method, the increased in absorbance showing its scavenging potential. The scavenging capacity of the test compounds and standard on the DPPH, ABTS·+, H2O2 decreased in the order BHT>ML>MC>C>L which were 98.4, 96.4, 86.4, 68.3, 49.7% for DPPH, BHT>ML>L>MC>C which were 99.3, 96.9, 96.3,66.6, 53.4% for ABTS·+, BHT>ML>MC>L>C which were 68.8%, 52.4%, 49.6%, 43.1% and 37.7% for H2O2 at the concentration of 50 µg/ml, respectively.Conclusion: The experimental findings showed that cis-[Cr(C2O4)2(H2O)2]--levodopa and cis-[Cr(C2O4)2(H2O)2]--carbidopa are having higher antioxidant potential than Levodopa and carbidopa although not superior to that of standard compound

Bacterial Foraging Optimized STATCOM for Stability Assessment in Power System

This paper presents a study of improvement in stability in a single machine connected to infinite bus (SMIB) power system by using static compensator (STATCOM). The gains of Proportional-Integral-Derivative (PID) controller in STATCOM are being optimized by heuristic technique based on Particle swarm optimization (PSO). Further, Bacterial Foraging Optimization (BFO) as an alternative heuristic method is also applied to select optimal gains of PID controller. The performance of STATCOM with the above soft-computing techniques are studied and compared with the conventional PID controller under various scenarios. The simulation results are accompanied with performance indices based quantitative analysis. The analysis clearly signifies the robustness of the new scheme in terms of stability and voltage regulation when compared with conventional PID

Bacterial Foraging Optimized STATCOM for Stability Assessment in Power System

This paper presents a study of improvement in stability in a single machine connected to infinite bus (SMIB) power system by using static compensator (STATCOM). The gains of Proportional-Integral-Derivative (PID) controller in STATCOM are being optimized by heuristic technique based on Particle swarm optimization (PSO). Further, Bacterial Foraging Optimization (BFO) as an alternative heuristic method is also applied to select optimal gains of PID controller. The performance of STATCOM with the above soft-computing techniques are studied and compared with the conventional PID controller under various scenarios. The simulation results are accompanied with performance indices based quantitative analysis. The analysis clearly signifies the robustness of the new scheme in terms of stability and voltage regulation when compared with conventional PID

What’s for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago

Amphibian invasions have considerable detrimental impacts on recipient ecosystems. However, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We carried out diet analyses of the invasive H. tigerinus and native anurans, across four habitat types and two seasons; we hypothesized that (i) small vertebrates constitute a majority of the H. tigerinus diet, particularly by volume and (ii) the diet of H. tigerinus significantly overlaps with the diet of native anurans, thereby, leading to potential competition. We assessed the diet of the invasive H. tigerinus (n = 358), and individuals of the genera Limnonectes (n = 375) and Fejervarya (n = 65) and found a significant dietary overlap of H. tigerinus with only Limnonectes. Small vertebrates, including several endemic species, constituted the majority of H. tigerinus, diet by volume, suggesting potential impact by predation. Prey consumption and electivity of the three anurans indicated a positive relationship between predator-prey body sizes. Individuals of H. tigerinus and Fejervarya chose evasive prey, suggesting that these two taxa are mostly ambush predators; individuals of Limnonectes chose a mixture of sedentary and evasive prey indicating that the species employs a combination of ‘active search’ and ‘sit and wait’ foraging strategies. All three species of anurans mostly consumed terrestrial prey. This intensive study on a genus of newly invasive amphibian contributes to knowledge of the impact of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We also stress the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians

An overview of treatment options for COVID-19

Severe acute respiratory syndrome- coronavirus-2 (SARS-CoV-2) which emerged in Wuhan initially as pneumonia of unknown origin in December 2019, later spread to whole world and became pandemic on 11th March, 2020. Many drugs have been proposed but are backed without clinical evidence. Scientific bodies are in the row to discover a reliable vaccine and effective drugs against the novel coronavirus. Many antiviral and anti-parasitic drugs which were thought to have some effect on Coronavirus disease 2019 (COVID-19) have been tried during the crisis but none have shown concrete evidence of action. Randomized clinical trials on the repurposed drugs are now registered under clinical trial registry to look at the safety profile and efficacy of the drugs to be used against SARS-CoV-2. Many meta-analyses are being conducted worldwide to frame evidence for the fight against this novel coronavirus. We are providing below a review of various drugs that have been tried for treatment of COVID-19 as well as different clinical trials which are underway

HIV status among presumptive tuberculosis cases attending tertiary care centre in South India

Introduction: In India, to increase human immunodeficiency virus (HIV) case detection, the National Technical Working Group onTB /HIV had made it mandatory to screen for HIV infection among presumptive tuberculosis (TB) cases. Material and methods: Our study was a cross-sectional study, conducted between June 2015 and December 2016 in a tertiarycare institute (JIPMER), in South India, to estimate the prevalence of HIV among presumptive TB cases. Results: Among the 964 presumptive TB cases who attended pulmonary medicine OPD, 189 patients were sputum acid-fastbacilli (AFB) positive. Among the 189 sputum positive cases, 9 were HIV positive. Of the 964 presumptive TB cases, 879 gaveconsent for HIV testing and 33 (3.7%) turned out to be HIV positive. If only sputum positive cases had been screened for HIV,we would have missed 24 new HIV positive cases. The number needed to screen was 27 among presumptive TB cases and 18among TB patients. Conclusions: The uptake of HIV testing (91%) and the diagnostic yield of 3.7% of HIV positive cases among the presumptiveTB patients is quite high compared to that of the Revised National Tuberculosis Control Programme (RNTCP) mechanism of Puducherry.This reinforces the need to screen all the presumptive cases for HIV infection, to increase HIV case detection so thatanti-retroviral therapy (ART) can be initiated early

Integrating Apparent Conductance in Resistivity Sounding to Constrain 2D Gravity Modeling for Subsurface Structure Associated with Uranium Mineralization across South Purulia Shear Zone, West Bengal, India

South Purulia Shear Zone (SPSZ) is an important area for the prospect of uranium mineralization and no detailed geophysical investigations have been carried out in this region. To delineate the subsurface structure in the present area, vertical electrical soundings using Schlumberger array and gravity survey were carried out along a profile perpendicular to the SPSZ. Apparent conductance in the subsurface revealed a possible connection from SPSZ to Raghunathpur. The gravity model reveals the presence of a northerly dipping low density zone (most likely the shear zone) extending up to Raghunathpur under a thin cover of granitic schist of Chotanagpur Granite Gneissic Complex (CGGC). The gravity model also depicts the depth of the zone of density low within this shear zone at ~400 m near Raghunathpur village and this zone truncates with a steep slope. Integration of resistivity and gravity study revealed two possible contact zones within this low density zone in the subsurface at depth of 40 m and 200 m. Our study reveals a good correlation with previous studies in Raghunathpur area characterized by medium to high hydro-uranium anomaly. Thus the conducting zone coinciding with the low gravity anomaly is inferred to be a possible uranium mineralized zone