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Latitudinal fluctuation in global concentration of CO2 and CH4 from shortwave infrared spectral observation by GOSAT during COViD-19

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international Journal of Digital Earth 2021年第12期14卷 1882-1896页

作者： Laxmi kant Sharma Rajani kant Verma Department of Environmental Science School of Earth SciencesCentral University of RajasthanAjmerIndia

Various countries have rapidly implemented strict actions to slow the blowout of *** events were dis-regarded,and anthropogenic activities such as industrial and transport systems were at a *** countries were on lockdown,including the largest emitters of carbon *** to these lockdowns,anthropogenic activities have been reduced and reported that air quality improves at a regional scale in many countries,including ***,the current study using Greenhouse Gases Observing Satellite(GOSAT/iBUKi)datasets to monitor the fluctuation of the average global concentration of dry mole fractions of atmospheric Methane(CH_(4))and Carbon Dioxide(CO_(2))during these pandemic lockdowns from January to June *** emphasize no significant reduction in the average concentration of dry mole fractions of atmospheric CH_(4) over the globe,but a minor reduction was observed in global CO_(2) *** average concentration of both gases compares at each ten-degree *** study reveals that,against the regional breakdowns,these short time lockdowns are not enough to control the concentration of these greenhouse gases at a larger scale,such as 10°latitude and globally,except for a minor reduction in CO_(2) concentration.

关键词： Lockdown pandemic air quality greenhouse gas methane carbon dioxide

Cosmological parameters for spatially flat dust filled Universe in Brans-Dicke theory

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Research in Astronomy and Astrophysics 2017年第3期17卷 55-66页

作者： Gopi kant Goswami Department of Mathematics Kalyan E G.CollegeBhilai-490 006C.G.India

We have investigated late time acceleration for a spatially fiat dust filled Universe in Brans- Dicke theory in the presence of a positive cosmological constant A. Expressions for Hubble＇s constant, luminosity distance and apparent magnitude have been obtained for our model. The theoretical results are compared with observed values of the latest 287 high redshift （0.3 ≤ z ≤1.4） Type ia supernova data taken from the Union 2.1 compilation to estimate present values of matter and dark energy parame- ters, （Ωm）0 and （ΩA）0. We have also estimated the present value of Hubble＇s constant H0 in light of an updated sample of Hubble parameter measurements including 19 independent data points. The results are found to be in good agreement with recent astrophysical observations. We also calculated various physical parameters such as matter and dark energy densities, present age of the Universe and decelera- tion parameter. The value for Brans-Dicke-coupling constant ω is set to be 40 000 based on accuracy of solar system tests and recent experimental evidence.

关键词： cosmology osmological parameters - cosmology observations- dark energy-Brans-Dicke theory

Reconstructing Missing Hourly Real-Time Precipitation Data Using a Novel intermittent Sliding Window Period Technique for Automatic Weather Station Data

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Journal of Meteorological Research 2017年第4期31卷 774-790页

作者： Nagaraja HEMA Krishna kant Department of Computer Science and Engineering/information Technology Jaypee Institute of Information Technology Noida 201307 India

Precipitation is the most discontinuous atmospheric parameter because of its temporal and spatial variability. Precipitation observations at automatic weather stations（AWSs） show different patterns over different time periods. This paper aims to reconstruct missing data by finding the time periods when precipitation patterns are similar, with a method called the intermittent sliding window period（iSWP） technique—a novel approach to reconstructing the majority of non-continuous missing real-time precipitation data. The iSWP technique is applied to a 1-yr precipitation dataset（January 2015 to January 2016）, with a temporal resolution of 1 h, collected at 11 AWSs run by the indian Meteorological Department in the capital region of Delhi. The acquired dataset has missing precipitation data amounting to 13.66%, of which 90.6% are reconstructed successfully. Furthermore, some traditional estimation algorithms are applied to the reconstructed dataset to estimate the remaining missing values on an hourly basis. The results show that the interpolation of the reconstructed dataset using the iSWP technique exhibits high quality compared with interpolation of the raw dataset. By adopting the iSWP technique, the root-mean-square errors（RMSEs）in the estimation of missing rainfall data—based on the arithmetic mean, multiple linear regression, linear regression,and moving average methods—are reduced by 4.2%, 55.47%, 19.44%, and 9.64%, respectively. However, adopting the iSWP technique with the inverse distance weighted method increases the RMSE by 0.07%, due to the fact that the reconstructed data add a more diverse relation to its neighboring AWSs.

关键词： automatic weather station intermittent sliding window period interpolation mean absolute error reconstruction of missing precipitation data

Effect of pulse slippage on density transition-based resonant third-harmonic generation of short-pulse laser in plasma

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Frontiers of physics 2016年第4期11卷 163-170页

作者： Vishal Thakur Niti kant Department of Physics Lovely Professional University Phagwara-144411 Punjab India

The resonant third-harmonic generation of a tion was investigated. Because of self-focusing self-focusing laser in plasma with a density transi- of the fundamental laser pulse, a transverse intensity gradient was created, which generated a plasma wave at the fundamental wave frequency. Phase matching was satisfied by using a Wiggler magnetic field, which provided additional angular too- mentum to the third-harmonic photon to make the process resonant. An enhancement was observed in the resonant third-harmonic generation of an intense short-pulse laser in plasma embedded with a magnetic Wiggler with a density transition. A plasma density ramp played an important role in the self-focusing, enhancing the third-harmonic generation in plasma. We also examined the ef- fect of the Wiggler magnetic field on the pulse slippage of the third-harmonic pulse in plasma. The pulse slippage was due to the group-velocity mismatch between the fundamental and third-harmonic pulses.

关键词： short pulse laser pulse slippage third harmonic generation plasma

Characterization and modification of waste magnesium chip utilized as an Mg-rich intermetallic composite

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Particuology 2014年第6期12卷 158-164页

作者： Aysel kantürk Figen Sabriye Piskin Department of Chemical Engineering Yildiz Technical University

in this study,the characterization and modification of waste magnesium chips（WMCs）,which were produced by plastic molding in a gold manufacturing factory and are used as Mg-rich intermetallic composites in storing hydrogen,were discussed in *** were analyzed using X-ray diffraction（XRD）,X-ray fluorescence（XRF） spectroscopy,differential scanning calorimetry（DSC）,scanning electron microscopy（SEM）,and Brunauer-Emmett-Teller（BET） analysis to characterize the materials’ structural *** milling,organic treatment,and inorganic salt addition were carried out to modify the WMCs’ surface to prepare Mg-rich intermetallic composites for storing *** modified samples were analyzed using high-pressure volumetric analyses to calculate their hydrogen storage *** authors conclude that modified WMC was promising as an Mg-rich intermetallic composite that was suitable for use in hydrogen storage with a 4.59 wt%capacity at 320 C under a hydrogen pressure of 60 bar.

关键词： Waste magnesium chip Characterization Modification Hydrogen storage intermetallic composite

Comparison of eigensensitivity and ANN based methods in model updating of an eight-story building

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Earthquake Engineering and Engineering Vibration 2015年第3期14卷 453-464页

作者： Prabakaran K Ashok Kumar Shashi kant Thakkar Department of Civil Engineering PSG College of Technology Department of Earthquake Engineering IIT Roorkee

Analytical models prepared from field drawings do not generally provide results that match with experimental *** error may be due to uncertainties in the property of materials,size of members and errors in the modelling *** is important to improve analytical models using experimentally obtained *** the past several years,data obtained from ambient vibration testing have been successfully used in many cases to update and match dynamic behaviors of analytical models with real *** paper presents a comparison between artificial neural network(ANN) and eigensensitivity based model updating of an existing multi-story building.A simple spring-mass analytical model,developed from the structural drawings of the building,is considered and the corresponding spring stiffness and lumped mass of all floors are chosen as updating *** advantages and disadvantages of these updating methods are *** advantage is that both methods ensure a physically meaningful model which canbe further employed in determining structural response and health monitoring.

关键词： ambient vibration measurement model updating artif

Self-Focusing/Defocusing of Chirped Gaussian Laser Beam in Collisional Plasma with Linear Absorption

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Communications in Theoretical Physics 2016年第9期65卷 349-354页

作者： Manzoor Ahmad Wani Niti kant Department of Physics Lovely Professional University

This paper presents an investigation on the self-focusing/defocusing of chirped Gaussian laser beam in collisional plasma with linear absorption. We have derived the differential equation for the beam width parameter by using WKB and paraxial approximations and solved it numerically. The effect of chirp and other laser plasma parameters is seen on the behavior of beam width parameter with dimensionless distance of propagation. The results are discussed and presented graphically. Our simulation results show that the amplitude of oscillations decreases with the distance of propagation. Due to collisional frequency, the laser beam shows fast divergence which can be minimized by the introduction of chirp parameter. The chirp decreases the effect of defocusing and increases the ability of self-focusing of laser beam in collisional plasma.

关键词： self-focusing/defocusing chirped Gaussian laser beam collisional plasma linear absorption

Multivariable regression model for Fox depth correction factor

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 103-109页

作者： Ravi kant MiTTAL Sanket RAWAT Piyush BANSAL Department of Civil Engineering Birla Institute of Technology & SciencePilani 333031India Department of Civil and Environmental Engineering Virginia TechBlacksburgVA 24061USA

This paper presents a simple and efficient equation for calculating the Fox depth correction factor used in computation of settlement reduction due to foundation *** solution of Boussinesq theory was used originally to develop the Fox depth correction factor equations which were rather complex in *** equations were later simplified in the form of graphs and tables and referred in various international code of practices and standard texts for an unsophisticated and quick ***,these tables and graphs provide the factor only for limited values of the input variables and hence again complicates the process of automation of ***,this paper presents a non-linear regression model for the analysis of effect of embedment developed using "iBM Statistical Package for the Social Sciences" *** multiple iterations,the value of coefficient of determination is found to reach *** equation is straightforward,competent and easy to use for both manual and automated calculation of the Fox depth correction factor for wide range of input *** the developed equation,parametric study is also conducted in the later part of the paper to analyse the extent of effect of a particular variable on the Fox depth factor.

关键词： settlement embedment Fox depth correction factor regression multivariable

A Comparative Assessment of Temperature Data from Different Sources for Dehradun, Uttarakhand, india

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Journal of Meteorological Research 2016年第6期30卷 1019-1032页

作者： Atul kant PiYOOSH Sanjay Kumar GHOSH Department of Civil Engineering Indian Institute of Technology Roorkee

A comparative study of extreme temperature parameters from different sources is carried out by examining standardized anomalies, trends, correlation, and equivalence of datasets. Maximum temperature （Tmax） and minimum temperature （Wmln） for Dehradun, from two different sources such as computed and gridded data from Climatic Research Unit （CRU） and observed data from india Meteorological Department （iMD） are used for 1901-2012. The CRU data are compared initially with iMD, by graphical assessment of standardized anomalies. Subsequently, change points are identified by using Cumulative Sum （CUSUM）-chart technique for trend analysis. The magnitude and significance of trends are determined by applying Sen＇s slope test, and on the basis of these, trends are compared. Further, correlation analysis is carried out and datasets are tested for equivalence by using Wileoxon-Mann Whitney test. The result shows that annual standardized anomalies of CRU data follow the pattern of annual standardized anomalies of iMD data. The CRU data exhibit similar trends and are well correlated with iMD dataset. Moreover, CRU anomaly data are identical with iMD anomaly data in the recent decades. High resolution gridded CRU data have open access and may be more useful due to its spatio-temporal continuity for land areas of the world.

关键词： cumulative sum Sen's slope temperature trend temperature anomaly correlation Wilcoxon Mann-Whitney test