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The Impingement Heat Transfer Data of Inclined Jet in Cooling Applications: A Review

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Journal of Thermal Science 2020年第1期29卷 1-12页

作者： PAWAR shashikant PATEL Devendra Kumar SMEC Vellore Institute of Technology

On the impingement heat transfer data,the experimental studies of air and liquid jets impingement to the flat surfaces were collected and critically *** oblique impingements of both single circular and planar slot jets were considered in *** review focused on the surface where the jet impingement cooling technique was *** nozzle exit Reynolds numbers based on the hydraulic diameter varied in the range of 1,500–52,*** oblique angles relative to the plane surface and the dimensionless jet-to-plate spacing vary in the range of 15°–90°and 2–12 *** review suggested that the magnitude of maximum heat transfer shifted more for air jets compared with the liquid *** drop in the inclination angle and the jet-to-plate separation led to the increase in the asymmetry of heat transfer *** displacement of maximum Nusselt number(heat transfer)locations was found to be sensitive to the inclination angle and the smaller jet-to-plate ***,the Nusselt number correlations proposed by various researchers were discussed and compared with the results of the cited references.

关键词： heat and fluid flow jet impingement Nusselt number oblique angle

Cosmology using long gamma-ray bursts: statistical analysis of errors in calibrated data

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Research in Astronomy and Astrophysics 2019年第2期19卷 143-150页

作者： Meghendra Singh shashikant Gupta Amit Sharma Satendra Sharma Dr.A.P.J.Abdul Kalam Technical University G.D.Goenka University Amity University Haryana Yobe State University

We investigate direction dependence and non-Gaussian features in high-z cosmological data using ?_(χ~2) and ?_χ statistics and the Kolmogorov-Smirnov test. These techniques are applied on a set of calibrated long gamma-ray bursts(GRBs) and its combination with recent Type Ia supernovae data(Union2). Our statistical analysis shows a weak but consistent direction dependence in both the data *** analysis also indicates a non-Gaussian nature of errors in both data sets.

关键词： gamma-ray bursts observational cosmology cosmological parameters Gaussian distribution supernovae

Measurement of Hubble constant: were differences in secondary distance indicators apparent as early as the HST Key Project?

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Research in Astronomy and Astrophysics 2021年第3期21卷 97-106页

作者： Rahul Kumar Thakur shashikant Gupta Rahul Nigam PK Thiruvikraman Birla Institute of Technology&Science Pilani-Hyderabad CampusIndia G D Goenka University GurgaonHaryana122103India

Different measurements of the Hubble constant(H_(0))are not consistent,and a tension between the CMB based methods and cosmic distance ladder based methods has been *** from various distance based methods are also *** aggravate the problem,the same cosmological probe(TypeⅠa SNe for instance)calibrated through different methods also provides different values of H_(0).We compare various distance ladder based methods through the already available unique data obtained from the Hubble Space Telescope(HST).Our analysis is based on parametric(t-test)as well as non-parametric statistical methods such as the Mann-Whitney U test and Kolmogorov-Smirnov *** results show that different methods provide different values of H_(0) and the differences are statistically *** biases in the calibration would not account for these differences as the data have been taken from a single telescope with a common calibration *** unknown physical effects or issues with the empirical relations of distance measurement from different probes could give rise to these differences.

关键词： Cosmology Supernovae Hubble constant

Investigating the Hubble Tension Through Hubble Parameter Data

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Research in Astronomy and Astrophysics 2023年第6期23卷 199-202页

作者： Rahul Kumar Thakur shashikant Gupta Rahul Nigam PK Thiruvikraman Avantika University Ujjain456006India G D Goenka University GurgaonHaryana122103India Birla Institute of Technology&Science Pilani-Hyderabad CampusIndia

The Hubble constant(H_0),which represents the expansion rate of the universe,is one of the most important cosmological *** recent measurements of H0using the distance ladder methods such as type Ia supernovae are significantly greater than the CMB measurements by *** difference points to a crisis in the standard model of cosmology termed Hubble *** this work we compare different cosmological models,determine the Hubble constant and comment on the Hubble tension using the data from differential ages of *** data we use are free from systematic effects as the absolute age estimation of the galaxies is not *** apply the Bayesian approach along with the commonly used maximum likelihood method to estimate H_0 and calculate the AIC scores to compare the different cosmological *** non-flat cosmological model provides a higher value for matter density as well as the Hubble constant compared to the flatΛCDM *** AIC score is smaller for the flatΛCDM cosmology compared to the non-flat model indicating the flat model a better *** best-fit values of H_0 for both these models are 68.7±3.1 km s^(-1)Mpc^(-1)and 72.2±4km s^(-1)Mpc^(-1),*** results are consistent with the CCHP ***,the flat model result does not agree with the SH0ES result,while the non-flat result is inconsistent with the Planck value.

关键词： (cosmology:)cosmological parameters galaxies:high-redshift (stars:)supernovae:general

On the non-Gaussian errors in high-z supernovae type Ia data

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Research in Astronomy and Astrophysics 2016年第11期16卷 53-56页

作者： Meghendra Singh Ashwini Pandey Amit Sharma shashikant Gupta Satendra Sharma Dr. A.EJ. Abdul Kalam Technical University Uttar Pradesh Lucknow 226021 India GD Goenka University Gurgaon Haryana 122103 India Yobe State University Damaturu Yobe State Nigeria

The nature of random errors in any data set is Gaussian, which is a well established fact according to the Central Limit Theorem. Supernovae type Ia data have played a crucial role in major discoveries in cosmology. Unlike in laboratory experiments, astronomical measurements cannot be performed in controlled situations. Thus, errors in astronomical data can be more severe in terms of systematics and non-Gaussianity compared to those of laboratory experiments. In this paper, we use the Kolmogorov-Smiruov statistic to test non-Gaussianity in high-z supernovae data. We apply this statistic to four data sets, i.e., Gold data （2004）, Gold data （2007）, the Union2 catalog and the Union2.1 data set for our analysis. Our results show that in all four data sets the errors are consistent with a Gaussian distribution.

关键词： cosmology - data analysis - statistics - probability

Investigating the Evolution of Amati Parameters with Redshift

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Research in Astronomy and Astrophysics 2024年第1期24卷 188-200页

作者： Meghendra Singh Darshan Singh Kanhaiya Lal Pandey Dinkar Verma shashikant Gupta Delhi Metro Rail Corporation Limited New Delhi 110001India GD Goenka University Gurugram 122103India Department of Physics Mata Raj Kaur Institute of Engineering and TechnologyRewari 123401India Department of Physics School of Advanced SciencesVellore Institute of TechnologyVellore 632014India

Gamma-ray bursts(GRBs) are among the brightest objects in the Universe and, hence, can be observed up to a very high redshift. Properly calibrated empirical correlations between intensity and spectral correlations of GRBs can be used to estimate the cosmological parameters. However, the possibility of the evolution of GRBs with redshift is a long-standing puzzle. In this work, we used 162 long-duration GRBs to determine whether GRBs below and above a certain redshift have different properties. The GRBs are split into two groups, and we fit the Amati relation for each group separately. Our findings demonstrate that estimations of the Amati parameters for the two groups are substantially dissimilar. We perform simulations to investigate whether the selection effects could cause the difference. Our analysis shows that the differences may be either intrinsic or due to systematic errors in the data, and the selection effects are not their true origin. However, in-depth analysis with a new data set comprised of 119 long GRBs shows that intrinsic scatter may partly be responsible for such effects.

关键词： Cosmology gamma rays:general (cosmology:)large-scale structure of universe galaxies:high-redshift

Combinations of electron and proton donors in transition-metal complex mediated nitrogen reduction reactions

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Science China Chemistry 2024年第7期67卷 2136-2154页

作者： Delong Han Li Yang Hao Huang Priyanka Chakraborty shashikant U.Dighe Kuo-Wei Huang KAUST Catalysis Center and Division of Physical Science and Engineering King Abdullah University of Science and TechnologyThuwal 23955Saudi Arabia Agency for Science Technologyand ResearchInstitute of Materials Research and Engineering and Institute of Sustainability for ChemicalsEnergy and EnvironmentSingapore 138634Singapore

Nitrogen fixation is a complex process involving the transfer of six electrons and *** from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with *** the synthesis of diverse catalytic progress,the categories of donors have seen rapid ***,existing literature only provides summaries regarding the metal,ligands,and *** the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this ***,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor *** review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related ***,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.

关键词： dinitrogen reduction reaction reducing donor combination transition metal complexes homogeneous catalysis

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Impact assessment of the seasonal hydrological loading on geodetic movement and seismicity in Nepal Himalaya using GRACE and GNSS measurements

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Geodesy and Geodynamics 2022年第5期13卷 445-455页

作者： Devendra shashikant Nagale Suresh Kannaujiya Param K.Gautam Ajay K.Taloor Tandrila Sarkar Indian Institute of Remote Sensing ISRODehradunUttarakhand 248001India Wadia Institute of Himalayan Geology DehradunUttarakhand 248001India Department of Remote Sensing and GIS University of JammuJammu 180006India Indian Institute of Technology(Indian School of Mines) Dhanbad 826004India

The Himalayan terrain is an epitome of ongoing convergence and geodetic deformation where both tectonic and non-tectonic forces *** this study,the Gravity Recovery and Climate Experiment(GRACE)and Global Positioning System(GPS)datasets are used to assess the impact of seasonal loading on deformation with seismicity in *** recorded GPS data from 21 Global Navigation Satellite System(GNSS)stations during 2017-2020 are processed with respect to ITRF14 and the Indian reference frame,and the Center for Space Research(CSR)mascon RL06 during 2002-2020 is adopted to estimate the terrestrial water storage(TWS)change over the Ganga-Brahmaputra River *** results indicate that the hydrological loading effect or TWS change shows high negative,high positive,and moderately positive values in pre-monsoon,co-monsoon,and post-monsoon months,*** detrended GPS data of both horizontal and vertical components correlate with the seasonal TWS change using the Pearson correlation coefficient at each GNSS *** addition,the correlation coefficient has been interpolated using inverse distance weighting to investigate the regional TWS influence on geodetic *** the north component,the correlation coefficient ranges from-0.6 to *** the same time,the TWS is positively correlated with geodetic displacement(0.82)in the east component,and the correlation coefficient is negative(-0.69)in the vertical *** negative correlation signifies an inverse relationship between seasonal TWS variation and geodetic *** strain rate is estimated,which shows higher negative values in pre-monsoon than in ***,the effect of seismicity is 47.90%for pre-monsoon,15.97%for co-monsoon,and 17.56%for *** we can infer that the seismicity decreases with the increase of seasonal hydrological ***,the effect of strain is much higher in pre-monsoon than in post-monsoon since the impact of co-monsoon continues to

关键词： Non-tectonic Terrestrial water storage GRACE Strain rate Seismicity

Potential of herbal constituents as new natural leads against helminthiasis: A neglected tropical disease

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Asian Pacific Journal of Tropical Medicine 2019年第7期12卷 291-299页

作者： Kiran D.Patil shashikant B.Bagade Sanjay R.Sharma Ketan V.Hatware NMIMS School of Pharmacy and Technology Management

The WHO reports that billions of people and animals in tropical and subtropical regions are affected by helminthiasis as neglected tropical disease. It is predominant in underdeveloped areas;nevertheless, the increase in the number of travelers and migrants has made this infection more common. The current mass drug treatment produces severe side effects and many strains of helminths are resistant to them. None of the chemotherapeutic drugs meets the ideal requirements of anthelmintics, such as broad spectrum of activity, single dose cure, free from side effect and cost-effectiveness. Today, many researchers are screening the traditional herbal system in search of the anthelmintic herbal constituents which overcome all the problems of synthetic drugs. Several researchers proclaim anthelmintic activity of herbal medicines by using different experimental models. The present review demonstrates natural product drug discovery, outlining potential of herbal constituents from natural sources as natural leads against helminthiasis.

关键词： Neglected tropical diseases Herbal constituents Helminthiasis Herbal anthelmintics