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A nonautonomous mat hematical model to assess the impact of algae on the abatement of atmospheric carbon dioxide

International Journal of Biomathematics 2021年第7期14卷 227-264页

作者： pankaj kumar tiwari Rajesh kumar Singh Debaldev Jana Yun Kang Arvind kumar Misra Department of Basic Science and Humanities Indian Institute of Information Technology Bhagalpur 813210 India Government Shahid Kedamath P.G.College Mauganj Rewa 486331India Department of Mathematics&SRM Research Institute SRM Institute of Science and Technology Kattankulathur 603203 Tamil NaduIndia Science and Mathematics Faculty Arizona State University Mesa AZ 85212USA Department of Mathematics Institute of Science Banaras Hindu UniversityVaranasi 221005India

The world's oceans have played an important role in sequestering atmospheric carbon dioxide through solubility and the action of *** of atmospheric carbon dioxide by photoautotrophic algal cultures has the potential to diminish the release of carbon dioxide into the atmosphere,thereby helping to alleviate the trend toward global *** work investigates the role of algae in controlling the level of atmospheric carbon *** Rank Correlation Coefficients(PRCCs)technique is used to address how the concentration of atmospheric carbon dioxide is affected by changes in a specific parameter disregarding the uncertainty over the rest of the model *** related to algal growth are shown to significantly reduce the level of atmospheric CO_(2).Further,we explore the dynamics of nonautonomous system by incorporating the seasonal variations of sonic ecologically important model *** nonautonomous system exhibits globally attractive positive periodic solution,and also the appearance of double periodic solution is ***,by letting the seasonally forced parameters as almost periodic functions of time,we show almost periodic behavior of the *** findings suggest that the policy makers should focus on continuous addition of nutrients in the ocean to accelerate the algal growth thereby reducing the level of carbon dioxide in the atmosphere.

关键词： Mathematical model algae atmospheric CO2 sensitivity analysis:seasonality periodic solution

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Comprehensive studies on dielectric properties of p-methoxy benzylidene p-decyl aniline with function of temperature and frequency in planar geometry: A potential nematic liquid crystal for display devices

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Chinese Physics B 2021年第6期30卷 329-333页

作者： pankaj kumar Tripathi Kunwar Vikram Mithlesh tiwari Ajay Shriram Department of Physics Lovely Professional UniversityPhagwara-144411PunjabIndia Department of Allied Science Graphic Era(Deemed to be university)Dehradun-248002 India Department of Physics and Electronics Dr.Ram Manohar Lohia Avadh UniversityAyodhya-224001U.P.India School of Computer Science&Information Technology Jain(Deemed-to-be-University)Bengaluru-560069KarnatakaIndia

The dielectric properties of the nematic mesophase, p-methoxy benzylidene p-decyl aniline(MBDA), measured in planar geometry with a function of frequency and temperature are investigated in detail. The complex dielectric permittivity(ε' and ε'') is also studied at a bias voltage of 10 V for planar aligned sample cell of nematic mesophase. The dielectric permittivity with bias voltage attains a higher(> 2 times) value than that without bias voltage at a temperature of 56℃,which is due to the fact that the linking group of nematic molecules is internally interacted with an applied bias *** is supported by observing an enhanced dielectric permittivity of nematic liquid crystal(LC) in the presence of bias voltage, which can be fully explained as the increasing of the corresponding dipole moment. The dielectric relaxation behaviors of nematic LC are also demonstrated for planar aligned sample cell. The remarkable results are observed that the relaxation frequency shifts into low frequency region with the increase of the bias voltage applied to the planar aligned sample cells. The dielectric relaxation spectra are fitted by Cole–Cole nonlinear curve fitting for nematic mesophase in order to determine the dielectric strength.

关键词： dielectric permittivity dielectric loss relaxation frequency nematic mesogen

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Reliability assessment of deep excavations in spatially random cohesion weakening friction strengthening massive rocks:Application to nuclear repositories

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Underground Space 2023年第6期13卷 48-73页

作者： Akshay kumar Gaurav tiwari Department of Civil Engineering Indian Institute of Technology KanpurKanpurUttar Pradesh 208016India

An augmented methodology is developed to estimate the reliability of deep excavations along spatially variable massive rock masses using the cohesion weakening friction strengthening(CWFS)*** parameters of the CWFS model were initially identified using Sobol’s global sensitivity analysis based on their influence on the displacements and excavation damage zone around *** probability of failure was estimated by performing Mont–Carlo Simulations on random finite difference models of excavations generated via MATLAB-FLAC2D coupling,considering the spatial variation of these sensitive *** variation was modeled by generating anisotropic random fields of sensitive CWFS parameters via the recently developed Fourier series method and updated correlations suggested by Walton(2019).The proposed methodology was demonstrated for a proposed deep nuclear waste repository to be located in *** from the developed methodology were systematically compared with those of traditional reliability(ignoring spatial variation)and deterministic methods(ignoring uncertainty).Although the developed methodology was computationally complex,it was judged to be the most realistic due to the realistic consideration of heterogeneous distributions of rock *** methodologies underestimate/overestimate the excavation performance due to negligence of uncertainty and spatial ***,a parametric analysis was performed using developed methodology by varying the initial friction angle,scale of fluctuations(SOFs)and dilation *** effect of initial friction angle was observed to be more pronounced on the probability of failures as compared to SOFs and dilation *** observations were made related to the excavation damage zone(EDZ)development quantified using yield area ratio.

关键词： Deep excavations Brittle failures CWFS model Sobol’s sensitivity Moving least square response surface Fourier series random field

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Numerical Algorithm Based on Quintic Nonpolynomial Spline for Solving Third-Order Boundary Value Problems Associated with Draining and Coating Flows

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Chinese Annals of Mathematics,Series B 2012年第6期33卷 831-840页

作者： pankaj kumar SRIVASTAVA Manoj kumar Department of Mathematics Jaypee Institute of Information Technology Department of Mathematics Motilal Nehru National Institute of Technology

A numerical algorithm is developed for the approximation of the solution to certain boundary value problems involving the third-order ordinary differential equation associated with draining and coating flows. The authors show that the approximate so- lutions obtained by the numerical algorithm developed by using uonpolynomial quintic spline functions ave better than those produced by other spline and domain decomposition methods. The algorithm is tested on two problems associated with draining and coating flows to demonstrate the practical usefulness of the approach.

关键词： Third-order boundary value problem Spline functions Nonpolynomial quartic spline Nonpolynomial quintic spline Draining and coating flows

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Robertson-Walker cosmological models with perfect fluid in general relativity

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Research in Astronomy and Astrophysics 2011年第7期11卷 767-775页

作者： Rishi kumar tiwari Department of Mathematics Govt.Model Science College Rewa(M.P.) 486001India

Einstein＇s field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for a Robertson-Walker universe by assuming the cosmological term to be proportional to R-m（R is a scale factor and m is a constant）.A variety of solutions is *** physical significance of the cosmological models has also been discussed.

关键词： cosmological parameters—cosmology:variable cosmological term

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Jackknife based generalized resampling reliability approach for rock slopes and tunnels stability analyses with limited data:Theory and applications

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第3期14卷 714-730页

作者： Akshay kumar Gaurav tiwari Department of Civil Engineering IIT KanpurIndia

An efficient resampling reliability approach was developed to consider the effect of statistical uncertainties in input properties arising due to insufficient data when estimating the reliability of rock slopes and *** approach considers the effect of uncertainties in both distribution parameters(mean and standard deviation)and types of input ***,the approach was generalized to make it capable of analyzing complex problems with explicit/implicit performance functions(PFs),single/multiple PFs,and correlated/non-correlated input *** couples resampling statistical tool,***,with advanced reliability tools like Latin hypercube sampling(LHS),Sobol’s global sensitivity,moving least square-response surface method(MLS-RSM),and Nataf’s *** developed approach was demonstrated for four cases encompassing different *** were compared with a recently developed bootstrap-based resampling reliability *** results show that the approach is accurate and significantly efficient compared with the bootstrap-based *** proposed approach reflects the effect of statistical uncertainties of input properties by estimating distributions/confidence intervals of reliability index/probability of failure(s)instead of their fixed-point ***,sufficiently accurate results were obtained by considering uncertainties in distribution parameters only and ignoring those in distribution types.

关键词： Statistical uncertainty Resampling reliability Moving least square response surface(MLSRSM) Sobol’s global sensitivity Correlation coefficient

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Climatology, trend of aerosol-cloud parameters and their correlation over the Northern Indian Ocean

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Geoscience Frontiers 2023年第4期14卷 173-186页

作者： Harshbardhan kumar Shani tiwari Academy of Scientific and Innovative Research(AcSIR) Ghaziabad201002India Aerosol and Cloud Research Lab Geological Oceanography DivisionCSIR–National Institute of OceanographyGoa403004India

Aerosols are one of the important atmospheric constituents and exert indirect impact on climate through the modification of microphysical and radiative properties of clouds that in turn perturb the precipitation ***,the long term quantification of changes in aerosol and cloud characteristics and their interactions on both temporal as well as spatial scale will provide a crucial information for the better assessment of future climate *** present study,18 years(2003-2020)MODerate Resolution Imaging Spectro-radiometer(MODIS)derived aerosol-cloud dataset over the Northern Indian Ocean(NIO)were analysed to assess climatology and trend of aerosol,cloud characteristics and their *** found a strong heterogeneity in spatio-temporal variation of aerosol and cloud parameters over the NIO that are more prominent for the coastal *** climatological mean of aerosol loading is found high(AOD≥0.5)over the outflow region along the Indian sub-continent and low(AOD≤0.2)over the northern equatorial open *** climatological mean of cloud properties shows dominance of optically thicker deep convective(CTP700 hPa and CTT>273 K)over the northwestern Arabian Sea(AS).Similarly,bigger effective radii(>17µm)observed along the equatorial open ocean whereas smaller CER(0.

关键词： Aerosol Cloud properties Northern Indian Ocean Climatology Trend Correlation

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A Bayesian multi-model inference methodology for imprecise momentindependent global sensitivity analysis of rock structures

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 840-859页

作者： Akshay kumar Gaurav tiwari Department of Civil Engineering Indian Institute of Technology(IIT)KanpurKanpur208016India

Traditional global sensitivity analysis(GSA)neglects the epistemic uncertainties associated with the probabilistic characteristics(*** of distribution type and its parameters)of input rock properties emanating due to the small size of datasets while mapping the relative importance of properties to the model *** paper proposes an augmented Bayesian multi-model inference(BMMI)coupled with GSA methodology(BMMI-GSA)to address this issue by estimating the imprecision in the momentindependent sensitivity indices of rock structures arising from the small size of input *** methodology employs BMMI to quantify the epistemic uncertainties associated with model type and parameters of input *** estimated uncertainties are propagated in estimating imprecision in moment-independent Borgonovo’s indices by employing a reweighting approach on candidate probabilistic *** proposed methodology is showcased for a rock slope prone to stress-controlled failure in the Himalayan region of *** proposed methodology was superior to the conventional GSA(neglects all epistemic uncertainties)and Bayesian coupled GSA(B-GSA)(neglects model uncertainty)due to its capability to incorporate the uncertainties in both model type and parameters of *** Borgonovo’s indices estimated via proposed methodology provide the confidence intervals of the sensitivity indices instead of their fixed-point estimates,which makes the user more informed in the data collection *** performed with the varying sample sizes suggested that the uncertainties in sensitivity indices reduce significantly with the increasing sample *** accurate importance ranking of properties was only possible via samples of large ***,the impact of the prior knowledge in terms of prior ranges and distributions was significant;hence,any related assumption should be made carefully.

关键词： Bayesian inference Multi-model inference Statistical uncertainty Global sensitivity analysis(GSA) Borgonovo’s indices Limited data

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Masked Face Recognition Using MobileNet V2 with Transfer Learning

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Computer Systems Science & Engineering 2023年第4期45卷 293-309页

作者： Ratnesh kumar Shukla Arvind kumar tiwari Department of Computer Science&Engineering Dr.APJ Abdul Kalam Technical UniversityLucknow226021India Department of Computer Science&Engineering KNITSultanpur228118Uttar PradeshIndia

Corona virus(COVID-19)is once in a life time calamity that has resulted in thousands of deaths and security *** are using face masks on a regular basis to protect themselves and to help reduce corona virus *** the on-going coronavirus outbreak,one of the major priorities for researchers is to discover effective *** important parts of the face are obscured,face identification and verification becomes exceedingly *** suggested method is a transfer learning using MobileNet V2 based technology that uses deep feature such as feature extraction and deep learning model,to identify the problem of face masked *** the first stage,we are applying face mask detector to identify the face ***,the proposed approach is applying to the datasets from Canadian Institute for Advanced Research10(CIFAR10),Modified National Institute of Standards and Technology Database(MNIST),Real World Masked Face Recognition Database(RMFRD),and Stimulated Masked Face Recognition Database(SMFRD).The proposed model is achieving recognition accuracy 99.82%with proposed *** article employs the four pre-programmed models VGG16,VGG19,ResNet50 and *** extract the deep features of faces with VGG16 is achieving 99.30%accuracy,VGG19 is achieving 99.54%accuracy,ResNet50 is achieving 78.70%accuracy and ResNet101 is achieving 98.64%accuracy with own *** comparative analysis shows,that our proposed model performs better result in all four previous existing *** fundamental contribution of this study is to monitor with face mask and without face mask to decreases the pace of corona virus and to detect persons using wearing face masks.

关键词： Convolutional Neural Network(CNN) deep learning face recognition system COVID-19 dataset and machine learning based models

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Flow past a bluff body subjected to lower subcritical Reynolds number

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Journal of Ocean Engineering and Science 2020年第2期5卷 173-179页

作者： pankaj kumar Santosh kumar Singh Department of Mechanical Engineering SRM Institute of Science and TechnologyKattankulathur 603203India

The paper aimed to study the flow structure at the wake of the bluff body with altered blockage ratio(BR)keeping the fixed aspect ratio(AR).The study was conducted by a finite volume technique using commercial software *** CFD analysis of the bluff body is mainly subjected to the lower subcritical Reynolds number range(5000 to 15,000)along with blockage ratio as an important *** flow parameters such as drag coefficient,pressure,and kinetic energy variations are analyzed here for the Reynolds number(Re)and *** was observed that at fixed Re,t he drag coefficient(C_(D))increases with an increase in the BR while decrease with increasing Re for a fixed value of BR.

关键词： Blockage ratio Bluff body Drag coefficient Reynolds number

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