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Long-term optical flux and colour variability in quasars

Research in Astronomy and Astrophysics 2016年第2期16卷 63-68页

作者： N.sukanya C.s.stalin s.Jeyakumar D.Praveen Amab Dhani R.Damle Department of Physics Bangalore UniversityBangalore 560 056India Indian Institute of Astrophysics Bangalore 560 034India Departmento de Astronomia Universidad de GuanajuatoMexico Department of Physics Amrita School of EngineeringBangalore 560 035India Indian Institute of Technology Roorkee 247 667India

We have used optical V and R band observations from the Massive Compact Halo Object （MACHO） project on a sample of 59 quasars behind the Magellanic clouds to study their long term optical flux and colour variations. These quasars, lying in the redshift range of 0.2 〈 z 〈 2.8 and having apparent V band magnitudes between 16.6 and 20.1 mag, have observations ranging from 49 to 1353 epochs span- ning over 7.5 yr with frequency of sampling between 2 to 10 days. All the quasars show variability during the observing period. The normalised excess variance （Fvar） in V and R bands are in the range 0.2% 〈 F^r 〈 1.6% and 0.1% 〈 Fnr 〈 1.5% respectively. In a large fraction of the sources, Fvar is larger in the V band compared to the R band. From the z-transformed discrete cross-correlation function analysis, we find that there is no lag between the V and R band variations. Adopting the Markov Chain Monte Carlo （MCMC） approach, and properly taking into account the correlation between the errors in colours and mag- nitudes, it is found that the majority of sources show a bluer when brighter trend, while a minor fraction of quasars show the opposite behaviour. This is similar to the results obtained from another two independent algorithms, namely the weighted linear least squares fit （FITEXY） and the bivariate correlated errors and intrinsic scatter regression （BCEs）. However, the ordinary least squares （OLs） fit, normally used in the colour variability studies of quasars, indicates that all the quasars studied here show a bluer when brighter trend. It is therefore very clear that the OLs algorithm cannot be used for the study of colour variability in quasars.

关键词： time lag -- periodicity -- active galaxies -- quasars

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Detonation initiated disintegration of coal particle due to the maxi- mum strain energy theory

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Journal of Coal science & Engineering(China) 2013年第4期19卷 435-440页

作者： Patadiya D M Jaisankar s sheshadri T s Department of Aerospace Engineering Indian Institute of Science Bangalore India

Fragmentation behaviour of coal particles subjected to detonation wave is being studied. Detonation wave is initiated by a plasma cartridge at one end of a detonation tube. Coal particles are subjected to a shock whose temperature depends on the Mach number of the detonation wave. Temperature shock is found to generate thermal stresses which may fragment the coal particles. A non-dimensional mathematical model for the heat transfer process in the coal particle is proposed. Thermal stresses are calculated at various times and radii while maximum strain energy theory is used to understand the failure behavior viz., the time, temperature and location of fracture. A physical model for coal particle fragmentation when subjected to detonation wave is also proposed. The study suggests that detonation combustion of coal is qualitatively different from conventional method.

关键词： coal particle detonation wave spontaneous fragmentation

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Web Page Recommendation Using Distributional Recurrent Neural Network

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Computer systems science & Engineering 2023年第4期45卷 803-817页

作者： Chaithra G.M.Lingaraju s.Jagannatha Department of Computer science&Engineering Sapthagiri College of EngineeringBangaloreIndia Department of Information science and Engineering Sahyadri College of Engineering&ManagementMangaluruIndia Department of Computer Applications MSRITBangaloreIndia

In the data retrieval process of the Data recommendation system,the matching prediction and similarity identification take place a major role in the *** that,there are several methods to improve the retrieving process with improved accuracy and to reduce the searching ***,in the data recommendation system,this type of data searching becomes complex to search for the best matching for given query data and fails in the accuracy of the query recommendation *** improve the performance of data validation,this paper proposed a novel model of data similarity estimation and clustering method to retrieve the relevant data with the best matching in the big data *** this paper advanced model of the Logarithmic Directionality Texture Pattern(LDTP)method with a Metaheuristic Pattern searching(MPs)system was used to estimate the similarity between the query data in the entire *** overall work was implemented for the application of the data recommendation *** are all indexed and grouped as a cluster to form a paged format of database structure which can reduce the computation time while at the searching ***,with the help of a neural network,the relevancies of feature attributes in the database are predicted,and the matching index was sorted to provide the recommended data for given query *** was achieved by using the Distributional Recurrent Neural Network(DRNN).This is an enhanced model of Neural Network technology to find the relevancy based on the correlation factor of the feature *** training process of the DRNN classifier was carried out by estimating the correlation factor of the attributes of the *** are formed as clusters and paged with proper indexing based on the MPs parameter of similarity *** overall performance of the proposed work can be evaluated by varying the size of the training database by 60%,70%,and 80%.The parameters that are considered for performance analysis are Precision

关键词： Ontology data mining in big data logarithmic directionality texture pattern metaheuristic pattern searching system distributional recurrent neural network query recommendation

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Nonlinear three-dimensional stretched flow of an Oldroyd-B fluid with convective condition, thermal radiation, and mixed convection

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Applied Mathematics and Mechanics(English Edition) 2017年第7期38卷 969-980页

作者： B. MAHANTHEsH B. J. GIREEsHA s.A. sHEHZAD F.M. ABBAsI R. s. R. GORLA Department of Mathematics Christ University Bangalore 560029 Karnataka India Department of studies and Research in Mathematics Kuvempu University Shankarghatta 577451 Karnataka India Department of Mathematics COMSATS Institute of Information Technology Sahiwal 57000 Pakistan Department of Mathematics COMSATS Institute of Information Technology Islamabad 44000 Pakistan Department of Mechanical and Civil Engineering Purdue University Northwest Indiana 46391 U. S. A

The effect of non-linear convection in a laminar three-dimensional Oldroyd-B fluid flow is addressed. The heat transfer phenomenon is explored by considering the non-linear thermal radiation and heat generation/absorption. The boundary layer as- sumptions are taken into account to govern the mathematical model of the flow analy- sis. some suitable similarity variables are introduced to transform the partial differen- tial equations into ordinary differential systems. fifth-order techniques with the shooting method The Runge-Kutta-Fehlberg fourth- and are used to obtain the solutions of the dimensionless velocities and temperature. The effects of various physical parameters on the fluid velocities and temperature are plotted and examined. A comparison with the exact and homotopy perturbation solutions is made for the viscous fluid case, and an excellent match is noted. The numerical values of the wall shear stresses and the heat transfer rate at the wall are tabulated and investigated. The enhancement in the values of the Deborah number shows a reverse behavior on the liquid velocities. The results show that the temperature and the thermal boundary layer are reduced when the non- linear convection parameter increases. The values of the Nusselt number are higher in the non-linear radiation situation than those in the linear radiation situation.

关键词： nonlinear thermal convection nonlinear thermal radiation Oldroyd-B fluid,convective boundary condition heat source/sink

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Development of Palmprint Verification system Using Biometrics

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软件学报 2006年第8期17卷 1824-1836页

作者： G. shobha M. Krishna s.C. sharma R.V. College of Engineering Mysore Road Bangalore 560059 India

Palmprint verification system using Biometrics is one of the emerging technologies, which recognizes a person based on the principle lines, wrinkles and ridges on the surface of the palm. These line structures are stable and remain unchanged throughout the life of an individual. More importantly, no two palmprints from different individuals are the same, and normally people do not feel uneasy to have their palmprint images taken for testing. Therefore palmprint recognition offers a promising future for medium-security access control systems. In this paper, a new approach for personal authentication using hand images is discussed. Gray-scale palm images are captured using a digital camera at a resolution of 640×480. Each of these gray-scale images is aligned and then used to extract palmprint and hand geometry features. These features are then used for authenticating users. The image acquisition setup used here is inherently simple and it does not employ any special illumination nor does it use any pegs that might cause any inconvenience to users. Experimental results show that the designed system achieves an acceptable level of performance.

关键词：灰色图象边缘追踪顶点检测验证系统

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Effects of variable viscosity and temperature modulation on linear Rayleigh-Bénard convection in Newtonian dielectric liquid

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Applied Mathematics and Mechanics(English Edition) 2019年第11期40卷 1601-1614页

作者： P.G.sIDDHEsHWAR D.UMA s.BHAVYA Department of Mathematics Bangalore UniversityBengaluru 560056India Department of Computer science and Engineering PES UniversityBengaluru 560085India Department of Mathematics Atria Institute of TechnologyBengaluru 560024India

The linear Rayleigh-Bénard electro-convective stability of the Newtonian dielectric liquid is determined theoretically subject to the temperature modulation with time.A perturbation method is used to compute the critical Rayleigh number and the wave *** critical Rayleigh number is calculated as a function of the frequency of modulation,the temperature-dependent variable viscosity,the electric field dependent variable viscosity,the Prandtl number,and the electric Rayleigh *** effects of all three cases of modulations are established to delay or advance the onset of the convection *** addition,how the effect of variable viscosity controls the onset of convection is studied.

关键词： dielectric liquid temperature dependent variable viscosity electric field dependent variable viscosity electric Rayleigh number temperature modulation

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study on the Performance Deterioration of Mixed Flow Impeller due to Change in Tip Clearance

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Journal of Thermal science 2013年第6期22卷 532-538页

作者： Ramesh Rajakumar.D Ramamurthy.s Govardhan.M National Aerospace Laboratories-bangalore-560017 NCAD National Aerospace Laboratories Thermal Turbomachines laboratory Department of Mechanical EngineeringIndian Institute of Technology Madras

Performance of mixed flow compressor with un-shrouded impeller strongly depends upon unsteady, asymmetrical flow fields in the axial directions. The flow through the mixed flow impeller is complex due to three-dimensional nature of geometry. In mixed flow impeller, there are clearances between the rotating impeller blades and the casing as the high pressure ratio compressors are usually open shrouded impellers. As a result, certain amount of reduction in the performance is unavoidable due to clearance flows. In the present investigations, numerical analysis is performed using a commercial code to investigate tip clearance effects on through flow. The performance of mixed flow impeller with four different clearances between impeller and stationary shroud are evaluated and compared with experimental results. The impeller performance map was obtained for different operating speeds and mass flow rates with different tip clearances. The result shows that the tip leakage flow strongly interacts with mainstream and contributes to total pressure loss and performance reduction. The pressure and performance decrement are approximately linearly proportional to the gap between impeller and stationary *** analysis showed scope for improvement in design of the compressor for better performance in terms of efficiency and operating range.

关键词： Mixed Flow Compressor surge stall Choke CFD Tip Clearance Compressible Flow Periodic Grids and Jet-Wake

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Gender disparity in COVID-19: Role of sex steroid hormones

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Asian Pacific Journal of Tropical Medicine 2021年第1期14卷 5-9页

作者： Anuja Lipsa Jyothi s Prabhu st Johns Research Institute and st Johns Medical College St Johns National Academy of Health SciencesBangalore-560034.KarnatakaIndia

The emerging pandemic of COVID-19 caused by the novel pathogenic human coronavirus sARs-CoV-2 has caused significant morbidity and mortality across the globe,prompting the scientific world to search for preventive measures to interrupt the disease *** data indicates gender-based differences in COVID-19 morbidity with better outcome amongst *** in sex-dependent morbidity and mortality in COVID-19 patients may be attributed to difference in levels of sex steroid hormones-androgens and *** suggests that apart from the regulation of viral host factors,immunomodulatory and cardioprotective roles exerted by estrogen and progesterone may provide protection to females against *** the underlying mechanisms and beneficial effects of these hormones as an adjuvant to existing therapy may be a step towards improving the *** article aims to review studies demonstrating the role of sex steroidal hormones in modulating sARs-CoV-2 host factors and summarize plausible biological reasons for sex-based differences seen in COVID-19 mortality.

关键词： sARs-CoV-2 COVID-19 Gender differences steroid hormones Estrogens Androgens

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Prevalences of oligozoospermia and azoospermia in male partners of infertile couples from different parts of India

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Asian Journal of Andrology 2006年第1期8卷 89-93页

作者： Rajvi H.Mehta sanjay Makwana Geetha M. Ranga R.J.srinivasan s.s.Virk Hope Infertility Clinic and Research Foundation Bangalore 560042India Vasundhara Hospital and Fertility Research Centre Jodhpur 342003India Karthekeya Medical Research and Diagnostic Centre Kalina Mumbai 400098India Dr Tilak's Laboratory Kurnool Andhra Pradesh 518001India Virk Hospital Jalandhar 144003India

Aim： To determine whether there was any regional variation in the prevalence of azoospermia, oligozoospermia and mean sperm counts in male partners of infertile couples from different parts of India. Methods： Data on 16 714 semen samples analyzed over the past five years from six different laboratories located in five cities of India were collated and evaluated. Results： There was a regional variation in the prevalence of azoospermia. The prevalence of azoospermia was extremely high in Kurnool and Jodhpur （38.3% and 37.4%, respectively）. There was also a regional variation in the prevalence of oligozoospermia （51%） in Kurnool. There was no significant difference in the mean sperm counts in normospermic men. Conclusion： There is a regional variation in the prevalence of azoospermia and oligozoospermia in the male partners of infertile couples from different regions of India. The prevalence of azoospermia in Kumool and Jodhpur is higher than any other worldwide reported literature, Further studies need to be carded out to determine the cause of this. （Asian J Androl 2006 Jan; 8： 89-93）

关键词： oligospermia male infertility prevalence studies

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spectroscopic study of Be-shell stars:4 Her and 88 Her

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Research in Astronomy and Astrophysics 2016年第5期16卷 47-58页

作者： shruthi s Bhat Paul KT Annapumi subramaniam Blesson Mathew Department of Physics Christ UniversityBangalore 560029India Indian Institute of Astrophysics II BlockKormangalaBangalore 560034India Department of Astronomy&Astrophysics Tata Institute of Fundamental ResearchHomi Bhabha RoadMumbai400005India

We present an optical spectroscopic study based on 41 spectra of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotational velocity of these stars from HeI lines in the blue spectral region （4000-4500 A）. We find that these stars are likely to be rotating at a fractional critical rotation of -0.80. We measure the average Ip/lc ratio to quantify the strength of the Ha line and obtain 1.63 for 4 Her and 2.06 for 88 Her. The radius of the Ha emission region is estimated to be Ra/R. -5.0, assuming a Keplerian disk. These stars are thus found to be fast rotators with a relatively small Hoe emission region. We detect V/R variation of the Ha spectral line during the observed period. We re-estimate the periods for both stars and obtain a period of ,-46 d and its harmonic of 23.095 d for 4 Her, and a period of -86 d for 88 Her. As these two cases are shell stars with binaries and have low Ha EW with the emission region closer to the central star, the V/R variation and a change in period may be an effect of the binary on the circumstellar disk.

关键词： stars: emission-line Be -- circumstellar matter -- stars: individual (4 Her 88 Her) -- stars:rotation -- techniques: spectroscopic

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