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Estimation of the size and structure of the broad line region using Bayesian approach
Understanding the geometry and kinematics of the broad line region (BLR) of active galactic nuclei (AGN) is important to estimate black hole masses in AGN and study the accretion process. The technique of reverberation mapping (RM) has provided estimates of BLR size for more than 100 AGN now; however, the structure of the BLR has been studied for only a handful number of objects. Towards this, we investigated the geometry of the BLR for a large sample of 57 AGN using archival RM data. We performed systematic modelling of the continuum and emission line light curves using a Markov chain Monte Carlo method based on Bayesian statistics implemented in PBMAP (Parallel Bayesian code for reverberation-MAPping data) code to constrain BLR geometrical parameters and recover velocity integrated transfer function. We found that the recovered transfer functions have various shapes such as single-peaked, double-peaked, and top-hat suggesting that AGN have very different BLR geometries. Our model lags are in general consistent with that estimated using the conventional cross-correlation methods. The BLR sizes obtained from our modelling approach is related to the luminosity with a slope of 0.583 0.026 and 0.471 0.084 based on H ? and H ? lines, respectively. We found a non-linear response of emission line fluxes to the ionizing optical continuum for 93 per cent objects. The estimated virial factors for the AGN studied in this work range from 0.79 to 4.94 having a mean at 1.78 1.77 consistent with the values found in the literature. 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. -
Diagnosis and prediction of iigps countries bubble crashes during brexit
We herein employ an alternative approach to model the financial bubbles prior to crashes and fit a log-periodic power law (LPPL) to IIGPS countries (Italy, Ireland, Greece, Portugal, and Spain) during Brexit. These countries represent the five financially troubled economies of the Eurozone that have suffered the most during the Brexit referendum. It was found that all 77 crashes across the five IIGPS nations from 19 January 2015 until 17 February 2020 strictly followed a log-periodic power law or other LPPL signature. They all had a speculative bubble phase (following the power law growth) that was then followed by a sudden crash immediately after reaching a critical point. Furthermore, their pattern coefficients were similar as well. This study would surely assist policymakers around the Eurozone to predict future crashes with the help of these parameters. 2021 by the authors. Licensee MDPI, Basel, Switzerland. -
Significance of nonlinear Boussinesq approximation and non-uniform heat source/sink on nanoliquid flow with convective heat condition: sensitivity analysis
The quadratic convective flow of nanoliquid over an elongating plate subjected to non-uniform heat source/sink, partial slip, and Newton boundary conditions is studied by using the modified Buongiorno model. The correlation for effective thermal conductivity and viscosity of nanoliquid are taken from the experimental work of Corcione. The dimensionless velocity, temperature, rate of heat transport, and mass transport distributions are simulated by solving the nonlinear boundary value problem using the finite difference method. The additional novelty of the present study is an application of response surface methodology to scrutinize the interactive impact of key parameters on the rate of heat transfer. Further, the influence of key parameters is deliberated on various flow fields using the surface and streamline plots. The higher velocities are noticed for the case of nonlinear Boussinesq approximation as compared with the usual Boussinesq approximation. The temperature enhances with a non-uniform heat source/sink aspect. The sensitivity of the heat transfer to the nanoparticle volume fraction remains positive. 2021, The Author(s), under exclusive licence to SocietItaliana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature. -
Smartphone based indoor localization and tracking model using bat algorithm and Kalman filter
In recent days, accurate localization becomes essential for enabling smartphone-based navigation to attain maximum accuracy in the construction of the real world.Fingerprint-based localization is the widespread solution to achieve and assure effective performance. In this study, a new fingerprint-based localization model using a bat algorithm (BA) is presented stimulated by the echolocation nature of microbats. The presented model adapts BA for estimating the location information. Initially, the presented model applies a Bayesian-rule based objective function. Then, the BA is used for improving the accuracy and analyzing the effects of the initial position of the bats on the localization outcome. For mitigating the estimation error, the Kalman filter is employed for updating the initially determined position using the BA for tracking purposes. The experimental analysis indicated an improvement in real-time performance and decrease in computation complexity. The presented model also obtained maximum localization accuracy with minimum localization error over the compared methods. 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature. -
Heavy metal stress influence the andrographolide content, phytochemicals and antioxidant activity of Andrographis paniculata
Heavy metals (HM) are toxic components present in the earth's crust that can have a negative impact on plants as well as animals. Andrographis paniculata or 'King of bitters' belonging to the family Acanthaceae, is a medicinal herb traditionally used in the treatment of fever, common cold etc. In the present study, the effect of heavy metals (copper, tin and cobalt) on the andrographolide content, biochemical parameters like chlorophyll, carotenoid, protein, Total phenolic content (TPC), Total flavonoid content (TFC) and antioxidant activity in A. paniculata were analysed. Saplings of A. paniculata were treated at 50 and 100 mM concentrations, three different times at a time interval of 7 days. Andrographolide production was found to increase in copper and cobalt treated saplings when compared with the control. From the results, maximum andrographolide concentration was found in the saplings treated with 50 mM copper (8.51 mg/gm of DW) and 50 mM tin (8.10 mg/gm of DW) respectively. 50 mM cobalt treated plants have shown the highest concentration of TPC (17.21 mg/g of extract) and TFC (6.97 mg/gm of extract). Notable variations in other biochemical parameters like total chlorophyll, carotenoid content and antioxidant activities were observed in all treatments compared with the control. Antony & Nagella (2021). This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited (https://creativecommons.org/licenses/by/4.0/). -
Real hypersurfaces of complex space forms satisfying FischerMarsden equation
Let M be a real hypersurface of a complex space form of constant curvature c. In this paper, we study the hypersurface M which admits a nontrivial solution to FischerMarsden equation, that is, the induce metric g of M satisfies Hessg(?) = (?g?) g+ ?Sg, where ? is a nontrivial function. We prove that there does not exist a complete Hopf real hypersurface in a non-flat complex space form satisfying FischerMarsden equation. Finally, we show that a complete real hypersurface with A?= ??, ?? 0 , of a complex Euclidean space Cn satisfying FischerMarsden equation is locally congruent to a sphere or S1R2n-2. 2021, Universitdegli Studi di Ferrara. -
Tunable graphene nanopatch antenna design for on-chip integrated terahertz detector arrays with potential application in cancer imaging
Aim: Further to our reports on chip-integrable uncooled terahertz microbolometer arrays, compatible with medium-scale semiconductor device fabrication processes, the possibility of the development of chip-integrable medical device is proposed here. Methods: The concept of graphene-based nanopatch antennas with design optimization by the finite element method (FEM) is explored. The high-frequency structure simulator (HFSS) utilized fine FEM solver for analyzing empirical mode decomposition preprocessing and for modeling and simulating graphene antennas. Results: Graphene nanopatch antennas exhibited tunable features with varying patch dimensions and dependence on substrate material permittivity. Conclusion: This work implements reconfigurable graphene nanopatch antenna compatible with terahertz microbolometer arrays. This design concept further develops on-chip medical devices for possible screening of cancer cell with terahertz image processing. 2021 Future Medicine Ltd. -
Analysis and predictions of spread, recovery, and death caused by COVID-19 in India
The novel coronavirus outbreak was first reported in late December 2019 and more than 7 million people were infected with this disease and over 0.40 million worldwide lost their lives. The first case was diagnosed on 30 January 2020 in India and the figure crossed 0.24 million as of 6 June 2020. This paper presents a detailed study of recently developed forecasting models and predicts the number of confirmed, recovered, and death cases in India caused by COVID-19. The correlation coefficients and multiple linear regression applied for prediction and autocorrelation and autoregression have been used to improve the accuracy. The predicted number of cases shows a good agreement with 0.9992 R-squared score to the actual values. The finding suggests that lockdown and social distancing are two important factors that can help to suppress the increasing spread rate of COVID-19. 2018 Tsinghua University Press. -
Effects of reduced graphene oxide on nonlinear absorption and optical limiting properties of spin coated aluminium doped zinc oxide thin films
In this work, we investigate the nonlinear absorption and optical limiting properties of reduced graphene oxide (rGO) incorporated aluminum doped zinc oxide (AZO) composite thin films by open aperture z-scan technique using Q-switched Nd:YAG laser at 532 nm. The structural and spectral properties were also systemically analyzed. The composite thin films were synthesized by spin coating technique with online infrared curing facility. Studies on nonlinear optical responses of the investigated samples proved a substantial enhancement in the nonlinear absorption coefficient of AZO:rGO composites compared to AZO thin film. The nonlinear absorption is attributed to the two photon absorption with reverse saturable absorption. The strong nonlinear absorption and nonlinear scattering effects result in the optical limiting property of the composite material. The AZO:rGO thin film exhibits lower optical limiting threshold value (32 MW/cm2) as compared to AZO (59 MW/cm2). Hence it is an excellent optical limiter which explores applications in the field of optoelectronics as protecting material for sensitive photonic devices. 2021 -
Bioconvection of a radiating hybrid nanofluid past a thin needle in the presence of heterogeneous-homogeneous chemical reaction
The photocatalytic nature of TiO2 finds applications in medicinal field to kill cancer cells, bacteria, and viruses under mild ultraviolet illumination and the antibacterial characteristic of Ag makes the composition Ag - TiO2 applicable for various purposes. It can also be used in other engineering appliances and industries such as humidity sensor, coolants, and in footwear industry. Hence, this study deals with the analysis of the effects of magnetic field, thermal radiation, and quartic autocatalysis of heterogeneous-homogeneous reaction in an electrically conducting Ag - TiO2 - H2O hybrid nanofluid. Furthermore, the gyrotactic microorganisms are used as active mixers to prevent agglomeration and sedimentation of TiO2 that occurs due to its hydrophobic nature. The mathematical model takes the form of partial differential equations with viscosity and thermal conductivity being the functions of volume fraction. These equations are converted to ordinary differential equations by using similarity transformation and are solved by RKF-45 method with the aid of shooting method. It is observed that the increase in the size of the needle enhances the overall performance of the hybrid nanofluid. Furthermore, the temperature of the hybrid nanofluid increases with the increase in volume fraction. It is observed that the friction produced by the Lorentz force increases the temperature of the nanofluid. It is further observed that the heterogeneous reaction parameter has more significant effect on the concentration of bulk fluid than the homogeneous reaction parameter. Copyright 2021 by ASME. -
Antiferromagnetism of CoO-NiO bilayers studied by XMLD spectroscopy
CoO-NiO epitaxial bilayer system grown on MgO(001) substrate is investigated using x-ray magnetic linear dichroism (XMLD) spectroscopy with varying CoO overlayer thickness. An analysis of the Ni L 2 edge XMLD spectra using anisotropic XMLD formulation within a two-domain model reveals that the Ni moments undergo a spin reorientation with increasing CoO thickness. Such a spin reorientation is attributed to the competing magnetic interactions at both the NiO film interfaces, suggesting the existence of a sharp horizontal domain wall separating the in-plane and out-of-plane NiO domains. Our study also demonstrates a possible way to investigate the spin-structure along the thickness within the same chemical structure using a model-based approach, in a noninvasive manner. 2021 IOP Publishing Ltd. -
C-CORDIAL LABELING OF BIPARTITE SIGNED GRAPHS
Let ?:= (V, E) be a graph and ?:= (?, ?) be a signed graph with underling graph ?. Let : V (?) ?? {+, ?} be a C-marking. Then the function is called C-cordial labeling of signed graph ?, if |e? (?1) ?e? (1)| ? 1 and |v (?) ?v (+)| ? 1, where v (+) and v (?) are the number of vertices of ? having label + and ?, respectively under . In this paper, we have characterized signed cycles with given number of negative sections, which admit C-cordial labeling. We have also obtained a characterization of signed bistars which admit C-cordial labeling. 2021 Allahabad Mathematical Society. -
Future search algorithm for optimal integration of distributed generation and electric vehicle fleets in radial distribution networks considering techno-environmental aspects
In this paper, a new nature-inspire meta-heuristic algorithm called future search algorithm (FSA) is proposed for the first time to solve the simultaneous optimal allocation of distribution generation (DG) and electric vehicle (EV) fleets considering techno-environmental aspects in the operation and control of radial distribution networks (RDN). By imitating the human behavior in getting fruitful life, the FSA starts arbitrary search, discovers neighborhood best people in different nations and looks at worldwide best individuals to arrive at an ideal solution. A techno-environmental multi-objective function is formulated using real power loss, voltage stability index. The active and reactive power compensation limits and different operational constraints of RDN are considered while minimizing the proposed objective function. Post optimization, the impact of DGs on conventional energy sources is analyzed by evaluating their greenhouse gas emission. The effectiveness of the proposed methodology is presented using different case studies on Indian practical 106-bus agriculture feeder for DGs and 36-bus rural residential feeder for simultaneous allocation of DGs and EV fleets. Also, the superiority of FSA in terms of global optima, convergence characteristics is compared with various other recent heuristic algorithms. 2021, The Author(s). -
An empirical analysis of sustainability of public debt among BRICS nations
The main objective of this paper is to verify the sustainability of public debt among Brazil, Russia, India, China and South Africa (BRICS) in a political economy framework. Annual panel data have been used for BRICS countries from World Development Indicators of World Bank for the period 19802017 for the analysis. Bohn's sustainability framework is used to examine the sustainability of public debt in BRICS nations and verify the influence of political economic variables such as election year, coalition dummy, ideology of the government and unemployment on public debt sustainability. The results suggest that public debt sustainability is weak for BRICS as a whole. China and India have a better public debt sustainability coefficients compared to the same for Brazil, Russia and South Africa. Structural change dummy included in the model suggests that debt sustainability is severely affected after the 2008 crisis period. Political factors have influence on debt sustainability in BRICS. Electoral cycle year and coalition dummy variables adversely affect public debt sustainability in BRICS. While centrist political ideology is found to be significant and negative, left and right ideologies are not significant for debt sustainability. Since debt sustainability is found to be weak in BRICS, countries in the region need to adopt necessary measures to improve their primary balance through appropriate fiscal and debt management. Besides, it is important for the governments to prioritize fiscal prudence irrespective of their ideologies and political compulsions. 2020 John Wiley & Sons, Ltd -
Green Synthesis of Reduced Graphene Nanostructure from Cinnamomum Camphora
A facile green synthesis for carbon nanoparticle production using Cinnamomum camphora (Camphor) is presented. Camphor upon carbonization and chemical oxidation leads to the formation of nano-carbon structures with lateral size 7.33nm to 4.14nm, respectively. The nanomaterial's stacking height is about 2.76nm and 3.10nm, leading to the formation of about 10 layers of carbon. The AFM analysis confirms that the graphene layer formed is wrinkled or folded. Developments of a layered structure with spheroids are observed on the sample's surface, confirming the graphitization of the amorphous carbon. The relative intensity of the defect to the graphite band is found to be 0.98 for the nanostructure indicating a lesser degree of defects. The C1s band of the nanostructure is deconvoluted to components at 284.7, 286.5, 287.3, and 289 eV, which are assigned to non-oxygenated ring carbon (sp2 carbon), C in C-O (bound to O either as epoxy or hydroxyl), C in C=O (of alcohols, phenols or ether), and C in C(O)O (carboxylic acid) respectively. The study reveals the formation of few-layer oxygenated carbon layers from the botanical hydrocarbon. 2020 by the authors. -
Characterization of Line-Cut Signed Graphs
A signed graphS= (Su, ?) consists of an underlying graph Su and a function ?: E(Su) ? { + , - }. For a graph G, its lict graph written as Lc(G) is the intersection graph ?(E(G) ? C(G)). For a signed graph S, its line-cutsigned graph (in short called lict signed graph) is denoted by Lc(S) has underlying graph Lc(Su) and two vertices u and v joint by negative edge if u and v both are negative adjacent edges of S or u is a negative edge incident to a cut-vertex v of negative degree odd in S and by positive edge otherwise, here C(S) is the set of cut-vertices of S. In this paper, we establish structural characterization of lict signed graphs Lc(S). 2020, The National Academy of Sciences, India. -
Moderating effects of academic involvement in web-based learning management system success: A multigroup analysis
While several educational institutions in India, in accordance to global practices, have adopted Web-Based Learning Management Systems (WLMS) to supplement classroom courses, it is largely seen that these WLMSs fail in their objectives, leading to little or no return on investments. The study aims to define the factors that affect students acceptance of a web-based learning management system and test the moderating effect of their academic involvement in the success of a WLMS. 477 valid questionnaires were collected from university/college students to empirically test the research model using the structural equation modelling approach. The results concludes that indirect and direct effects account for 49% of the variation in the intention to use, which is explained by technical system quality, information quality, educational quality, service quality of the technical support team and user satisfaction. High academic involvement moderates the impact of different service qualities of the WLMS on user satisfaction, intention to use the system, and success of the WLMS. Based on the findings, theoretical and managerial implications are discussed. 2021 -
A study of quadratic thermal radiation and quadratic convection on viscoelastic material flow with two different heat source modulations
In many practical applications such as plastic manufacturing and the polymer industries, the temperature difference is substantially large as a result the density of the working fluid alters nonlinearly with temperature. Therefore, the nonlinear Boussinesq (NBA) approximation cannot be ignored, as it has a considerable impact on the flow and heat transport characteristics of the working fluid. Here, the non-Newtonian viscoelastic material flow driven by stretching of elastic sheet subjected to NBA and quadratic form of Rosseland thermal radiation is investigated. Two different heat source modulations, viz., exponential space-dependent heat source, and a temperature-related heat source are analyzed. The viscoelastic material obeys the quadratic Boussinesq approximation. The fluctuation of plate temperature is linear and the transpiration (plate mass suction) is also accounted. The Darcy law is employed for a porous medium. The dimensionless profiles of the velocity, heat transport rate, and temperature are simulated by solving the nonlinear two-point boundary value system by employing the finite difference-based routine. The significance of key parameters involved in the problem is studied on various flow fields via surface and streamline plots. It is found that the quadratic convection mechanism enhanced the Nusselt number; however, the quadratic thermal radiation aspect reduced the Nusselt number. The higher velocities are captured in the case of quadratic thermal convection as compared with its absence. Whereas this trend is quite opposite for the thermal field. The velocity of viscoelastic material positively correlated with the viscoelastic material parameter. Further, the outcome of this investigation helps in determining the key parameters which facilitate the desired heat transport rate. 2021 Elsevier Ltd -
Micro and nano Bi2O3 filled epoxy composites: Thermal, mechanical and ?-ray attenuation properties
Polymer composites have attracted considerable attention as potential light-weight and cost-effective materials for radiation shielding and protection. In view of this, the present work focusses on development of lead-free composites of diglycidyl ether of bisphenol A (DGEBA) epoxy resin with micro (~ 10 ?m) and nano (~ 20 nm) bismuth (III) oxide (Bi2O3) fillers, using solution casting technique. Thermal, mechanical and ?-ray attenuation properties of the composites were studied by varying the filler loading. Inclusion of the fillers into epoxy matrix was confirmed both structurally and morphologically by XRD and SEM, respectively. Thermogravimetric analysis (TGA) showed the thermal stability of composites to be as high as 400 C. The nanocomposites exhibited relatively higher thermal stability than their micro counterparts. Among the composites, 14 wt% nano-Bi2O3/epoxy composites showed highest tensile strength of 326 MPa, which is about 38% higher than 30 wt% micro Bi2O3/epoxy composites. Mass attenuation coefficients (?/?) of the composites were evaluated at ?-ray energies ranging from 0.356 to 1.332 MeV. Nanocomposites showed better ?-ray shielding at all energies (0.356, 0.511, 0.662, 1.173, 1.280 and 1.332 MeV) than micro composites with same filler loading. These studies revealed the significance of nano-sized fillers in enhancing overall performance of the composites. 2021 Elsevier Ltd -
TenzinNet for handwritten Tibetan numeral recognition
Tibet is known for its enumerable collection of Nalanda based Buddhism manuscripts that need to be digitized for immortalization of the teachings of Buddha and various Buddhist scholars. Handwritten Tibetan numeral recognition is relatively unexplored as compared to Roman and Chinese numerals. Recognition of handwritten documents for digitalization has been under study from past many years. This work proposes a novel model using convolutional neural networks architecture named as TenzinNet to recognize handwritten Tibetan numerals. TenzinNet achieved an accuracy of 90.76% in recognizing Tibetan numerals using the proposed model. 2021, Bharati Vidyapeeth's Institute of Computer Applications and Management.