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14,933 results on '"Rao, N."'

75. The carbon star DY Persei may be a cool R Coronae Borealis variable

Author

Garcia-Hernandez, D. A., Rao, N. Kameswara, Lambert, D. L., Eriksson, K., Reddy, A. B. S., and Masseron, T.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Optical and near-IR photometry suggests that the carbon star DY Persei exhibits fadings similar to those of R Coronae Borealis (RCB) variables. Photometric surveys of the Galaxy and Magellanic Clouds uncovered new DY Per variables with infrared photometry identifying them with cool carbon stars, perhaps, with an unusual tendency to shed mass. In an attempt to resolve DY Per's identity crisis -- a cool carbon giant or a cool RCB variable? -- we analyze a high-resolution H&K band spectrum of DY Per. The CO first-overtone bands in the K-band of DY Per show a high abundance of 18O such that 16O/18O = 4 +- 1, a ratio sharply at odds with published results for `regular' cool carbon giants with 16O/18O ~ 1000 but this exceptionally low ratio is characteristic of RCB-variables and HdC stars. This similarity suggests that DY Per indeed may be a cool RCB variable. Current opinion considers RCB-variables to result from merger of a He onto a CO white dwarf; observed abundances of these H-deficient stars including the exceptionally low 16O/18O ratios are in fair accord with predicted compositions for white dwarf merger products. A H-deficiency for DY Per is not directly observable but is suggested from the strength of a HF line and an assumption that F may be overabundant, as observed and predicted for RCB stars., Comment: Accepted for publication in ApJ (16 pages and 4 figures)

Published
2023
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76. UOCS-IX. AstroSat/UVIT study of the open cluster NGC 2818: Blue Stragglers, Yellow Stragglers, Planetary Nebula, and their membership

Author

Rani, Sharmila, Pandey, Gajendra, Subramaniam, Annapurni, and Rao, N. Kameswara

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

We present the first far-UV (FUV) imaging results of the intermediate-age Galactic open cluster NGC 2818 that has a Planetary nebula (PN) within the field using images taken from the Ultra-violet Imaging Telescope (UVIT) aboard AstroSat. We identify cluster members by combining UVIT-detected sources with Gaia EDR3 data. We detect four bright and hot blue straggler stars (BSSs) and two yellow straggler stars (YSSs) based on their location in the optical and FUV-optical color-magnitude diagrams. Based on the parameters estimated using Spectral Energy Distribution (SED), we infer that BSSs are either collisional products or might have undetectable white dwarf (WD) companions. Our photometric analysis of YSSs confirms their binarity, consistent with the spectroscopic results. We find YSSs to be formed through a mass-transfer scenario and the hot components are likely to be A-type subdwarfs. A comparison of the radial velocity (RV), Gaia EDR3 proper motion of the PN with the cluster, and reddening towards the PN and the cluster does not rule out the membership of the PN. Comparing the central star's position with theoretical pAGB models suggest that it has already entered the WD cooling phase, and its mass is deduced to be ~0.66Msun. The corresponding progenitor mass turns out to be ~2.1Msun, comparable to the turn-off mass of the cluster, implying that the progenitor could have formed in the cluster. We suggest that the NGC 2818 might be one of the few known clusters to host a PN, providing a unique opportunity to test stellar evolution models., Comment: 20 pages, 12 figures, 4 tables, Accepted for publication in ApJ

Published
2023
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83. Globular Cluster UVIT legacy Survey (GlobUleS) III. Omega Centauri in Far-Ultraviolet

Author

Prabhu, Deepthi S., Subramaniam, Annapurni, Sahu, Snehalata, Chung, Chul, Leigh, Nathan W. C., Dalessandro, Emanuele, Chatterjee, Sourav, Rao, N. Kameswara, Shara, Michael, Cote, Patrick, Choudhury, Samyaday, Pandey, Gajendra, Valcarce, Aldo A. R., Singh, Gaurav, Postma, Joesph E., Rani, Sharmila, Bandyopadhyay, Avrajit, Geller, Aaron M., Hutchings, John, Puzia, Thomas, Simunovic, Mirko, Sohn, Young-Jong, Thirupathi, Sivarani, and Yadav, Ramakant Singh

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

We present the first comprehensive study of the most massive globular cluster Omega Centauri in the far-ultraviolet (FUV) extending from the center to ~ 28% of the tidal radius using the Ultraviolet Imaging Telescope aboard AstroSat. A comparison of the FUV-optical color-magnitude diagrams with available canonical models reveals that the horizontal branch (HB) stars bluer than the knee (hHBs) and the white dwarfs (WDs) are fainter in the FUV by ~ 0.5 mag than model predictions. They are also fainter than their counterparts in M13, another massive cluster. We simulated HB with at least five subpopulations, including three He-rich populations with a substantial He enrichment of Y up to 0.43 dex, to reproduce the observed FUV distribution. We find the He-rich younger subpopulations to be radially more segregated than the He-normal older ones, suggesting an in-situ enrichment from older generations. The Omega Cen hHBs span the same effective temperature range as their M13 counterparts, but some have smaller radii and lower luminosities. This may suggest that a fraction of Omega Cen hHBs are less massive than those of M13, similar to the result derived from earlier spectroscopic studies of outer extreme HB stars. The WDs in Omega Cen and M13 have similar luminosity-radius-effective temperature parameters, and 0.44 - 0.46 M$_\odot$ He-core WD model tracks evolving from progenitors with Y = 0.4 dex are found to fit the majority of these. This study provides constraints on the formation models of Omega Cen based on the estimated range in age, [Fe/H] and Y (in particular), for the HB stars., Comment: Accepted for publication in ApJL; 13 pages, 5 figures, 1 table

Published
2022
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84. Effects of Solar Activity, Solar Insolation and the Lower Atmospheric Dust on the Martian Thermosphere

Author

Rao, N. V., Leelavathi, V., Yaswanth, Ch., Bhardwaj, Anil, and Rao, S. V. B.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

A diagnosis of the Ar densities measured by the Neutral Gas and Ion Mass Spectrometer aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) and the temperatures derived from these densities shows that solar activity, solar insolation, and the lower atmospheric dust are the dominant forcings of the Martian thermosphere. A methodology, based on multiple linear regression analysis, is developed to quantify the contributions of the dominant forcings to the densities and temperatures. The results of the present study show that a 100 sfu (solar flux units) change in the solar activity results in approx. 136 K corresponding change in the thermospheric temperatures. The solar insolation constrains the seasonal, latitudinal, and diurnal variations to be interdependent. Diurnal variation dominates the solar insolation variability, followed by the latitudinal and seasonal variations. Both the global and regional dust storms lead to considerable enhancements in the densities and temperatures of the Martian thermosphere. Using past data of the solar fluxes and the dust optical depths, the state of the Martian thermosphere is extrapolated back to Martian year (MY) 24. While the global dust storms of MY 25, MY 28 and MY 34 raise the thermospheric temperatures by approx. 22-38 K, the regional dust storm of MY 34 leads to approx. 15 K warming. Dust driven thermospheric temperatures alone can enhance the hydrogen escape fluxes by 1.67-2.14 times compared to those without the dust. Dusts effects are relatively significant for global dust storms that occur in solar minimum compared to those that occur in solar maximum., Comment: 23 pages, 10 figures, 1 table, submitted for publication in JGR Planets

Published
2022

86. The Detection and Analysis of Rice Kernel Parameters Conducted by the Application of Cluster Segmentation Techniques

Author

Vijendra Kumar, D., Srinivas Raja, B., Gowri, Ch., Ramalingeswara rao, N. M., Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Bhateja, Vikrant, editor, Lin, Hong, editor, Simic, Milan, editor, Tang, Jinshan, editor, and Sivakumar Reddy, Vustikayala, editor

Published
2024
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87. Decentralized Crowdfunding Application Using Blockchain Technologies

Author

Vadlana, Nagu, Thirupathi Rao, N., Bhattacharyya, Debnath, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Ranganathan, G., editor, Papakostas, George A., editor, and Shi, Yong, editor

Published
2024
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88. Comparative Analysis of Morphological Functions for Object Detection in Video Processing

Author

Sanagala, Siva Skandha, Rao, N. Eleswara, Bhaskar, Nuthanakanti, Nayak, Sanjib Kumar, Kumar, Sheo, Syamsundar, C., Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Simic, Milan, editor, Bhateja, Vikrant, editor, Murty, M. Ramakrishna, editor, and Panda, Sandeep Kumar, editor

Published
2024
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90. Investigations on Live-Line Strengthening of Transmission Line Towers by Using GFRP Angle Sections

Author

Balagopal, R., Prasad Rao, N., Palani, G. S., Rokade, R. P., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Cui, Zhen-Dong, Series Editor, Lu, Xinzheng, Series Editor, Goel, Manmohan Dass, editor, Vyavahare, Arvind Y., editor, and Khatri, Ashish P., editor

Published
2024
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91. Assessment of Random Testing Circuits Utilizing the LFSR Technique for a Sparse Neural Network

Author

Vijendra Kumar, D., Saritha Devi, M., Vyas Omkar, P., Ramalingeswara Rao, N. M., Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Bhateja, Vikrant, editor, Tang, Jinshan, editor, Sharma, Dilip Kumar, editor, Polkowski, Zdzislaw, editor, and Ahmad, Afaq, editor

Published
2024
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92. Implementation of a Density-Optimized High-Throughput and Efficient Built-In Self-Test (BIST) System Using Multiple Instruction Stream Computing (MISC) Architecture

Author

Ramalingeswara Rao, N. M., Vinod, G. V., Raja, B. Srinivas, Saritha Devi, M., Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Bhateja, Vikrant, editor, Tang, Jinshan, editor, Sharma, Dilip Kumar, editor, Polkowski, Zdzislaw, editor, and Ahmad, Afaq, editor

Published
2024
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95. Wind Analysis of Tall-Reinforced Concrete Chimney Considering the Effect of Soil–Structure Interaction

Author

Dhoolappanavar, Dhariyappa, Vadiraj Rao, N. R., Hulagabali, Anand M., Dodagoudar, G. R., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Cui, Zhen-Dong, Series Editor, Lu, Xinzheng, Series Editor, Sivakumar Babu, G. L., editor, Mulangi, Raviraj H., editor, and Kolathayar, Sreevalsa, editor

Published
2024
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97. Evaluation of Hardness Properties of Al7475/B4C/Fly Ash Hybrid Composites Using Friction Stir Process

Author

Mahesh, G., Domakonda, Vinay Kumar, Farooq, Shaik, Subbiah, Ram, Rajkumar, D. R., Rao, N. Srinivasa, Vijayakumar, S., Pisello, Anna Laura, Editorial Board Member, Hawkes, Dean, Editorial Board Member, Bougdah, Hocine, Editorial Board Member, Rosso, Federica, Editorial Board Member, Abdalla, Hassan, Editorial Board Member, Boemi, Sofia-Natalia, Editorial Board Member, Mohareb, Nabil, Editorial Board Member, Mesbah Elkaffas, Saleh, Editorial Board Member, Bozonnet, Emmanuel, Editorial Board Member, Pignatta, Gloria, Editorial Board Member, Mahgoub, Yasser, Editorial Board Member, De Bonis, Luciano, Editorial Board Member, Kostopoulou, Stella, Editorial Board Member, Pradhan, Biswajeet, Editorial Board Member, Abdul Mannan, Md., Editorial Board Member, Alalouch, Chaham, Editorial Board Member, Gawad, Iman O., Editorial Board Member, Nayyar, Anand, Editorial Board Member, Amer, Mourad, Series Editor, Sumesh, M., editor, R. S. Tavares, João Manuel, editor, Vettivel, S. C., editor, and Oliveira, Mario Orlando, editor

Published
2024
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98. Friction Stir Welded Magnesium AZ31B Alloy Used to Evaluate Mechanical Properties at Various Rotational Speeds

Author

Gugulothu, Bhiksha, Kumar, P. S. Satheesh, Rao, N. Srinivasa, Vijayakumar, S., Rajkumar, D. R., Rao, T. V. Janardhana, Naga Swapna Sri, M., Pisello, Anna Laura, Editorial Board Member, Hawkes, Dean, Editorial Board Member, Bougdah, Hocine, Editorial Board Member, Rosso, Federica, Editorial Board Member, Abdalla, Hassan, Editorial Board Member, Boemi, Sofia-Natalia, Editorial Board Member, Mohareb, Nabil, Editorial Board Member, Mesbah Elkaffas, Saleh, Editorial Board Member, Bozonnet, Emmanuel, Editorial Board Member, Pignatta, Gloria, Editorial Board Member, Mahgoub, Yasser, Editorial Board Member, De Bonis, Luciano, Editorial Board Member, Kostopoulou, Stella, Editorial Board Member, Pradhan, Biswajeet, Editorial Board Member, Abdul Mannan, Md., Editorial Board Member, Alalouch, Chaham, Editorial Board Member, Gawad, Iman O., Editorial Board Member, Nayyar, Anand, Editorial Board Member, Amer, Mourad, Series Editor, Sumesh, M., editor, R. S. Tavares, João Manuel, editor, Vettivel, S. C., editor, and Oliveira, Mario Orlando, editor

Published
2024
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99. Control Strategies for Blood Pressure Regulation in the Diabetic Patients Post Surgery

Author

Gopi Krishna Rao, P. V., Hanuma Naik, R., Sreenivasa Rao, N., Sowmya, G., Rajasekhar, M. V., Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Tan, Kay Chen, Series Editor, Shrivastava, Vivek, editor, Bansal, Jagdish Chand, editor, and Panigrahi, B. K., editor

Published
2024
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