检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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 pattern.Thus,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 change.In 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 correlation.We found a strong heterogeneity in spatio-temporal variation of aerosol and cloud parameters over the NIO that are more prominent for the coastal region.The 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 ocean.The 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(0.003 yr^(-1))suggesting a significant impact of s

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

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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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 tunnels.This approach considers the effect of uncertainties in both distribution parameters(mean and standard deviation)and types of input properties.Further,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 properties.It couples resampling statistical tool,i.***.jackknife,with advanced reliability tools like Latin hypercube sampling(LHS),Sobol’s global sensitivity,moving least square-response surface method(MLS-RSM),and Nataf’s transformation.The developed approach was demonstrated for four cases encompassing different types.Results were compared with a recently developed bootstrap-based resampling reliability approach.The results show that the approach is accurate and significantly efficient compared with the bootstrap-based approach.The 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 estimates.Further,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

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

在线全文

学校读者我要写书评

暂无评论

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)model.Sensitive 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 excavations.The 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 parameters.Spatial 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 Canada.Results 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 properties.Traditional methodologies underestimate/overestimate the excavation performance due to negligence of uncertainty and spatial variability.Finally,a parametric analysis was performed using developed methodology by varying the initial friction angle,scale of fluctuations(SOFs)and dilation angle.The effect of initial friction angle was observed to be more pronounced on the probability of failures as compared to SOFs and dilation angle.Similar 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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2023年第2期8卷 111-123页

作者： Raj kumar Ravi Shankar Verma Atul kumar tiwari Department of Mathematics Faculty of Engineering&TechnologyVeer Bahadur Singh Purvanchal UniversityJaunpur222003India Department of Mathematics Motihari College of EngineeringMotihari845401BiharIndia

This work is devoted to get a new family of analytical solutions of the(2+1)-coupled dispersive long wave equations propagating in an infinitely long channel with constant depth,and can be observed in an open sea or in wide channels.The solutions are obtained by using the invariance property of the similarity transformations method via one-parameter Lie group theory.The repeated use of the similarity transformations method can transform the system of PDEs into system of ODEs.Under adequate restrictions,the reduced system of ODEs is solved.Numerical simulation is performed to describe the solutions in a physically meaningful way.The profiles of the solutions are simulated by taking an appropriate choice of functions and constants involved therein.In each animation,a frame for dominated behavior is captured.They exhibit elastic multisolitons,single soliton,doubly solitons,stationary,kink and parabolic nature.The results are significant since these have confirmed some of the established results of S.kumar et al.(2020)and K.Sharma et al.(2020).Some of their solutions can be deduced from the results derived in this work.Other results in the existing literature are different from those in this work.

关键词： Dispersive long wave equations Solitons Invariants Lie-group Similarity solutions

Exploring the potential of artificial intelligence techniques in prediction of the removal efficiency of vortex tube silt ejector

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2023年第4期38卷 615-627页

作者： Sanjeev kumar Chandra Shekhar Prasad Ojha Nand kumar tiwari Subodh Ranjan Department of Civil Engineering Indian Institute of Technology Department of Civil Engineering National Institute of Technology

A vortex tube silt ejector is a curative hydraulic structure used to remove sediment deposits from canals and is recognized as one of the most efficient substitutes for physically removing canal sediment. The spatially varied flow in the channel and the rotational flow behavior in the tube make the silt removal process complex. It is even harder to accurately predict the silt removal efficiency by traditional models accurately. However, artificial intelligence(AI) and machine learning approaches have emerged as robust substitutes for studying complex processes. Therefore, this research makes use of AI approaches; support vector machine(SVM), random forest(RF), random tree(RT), and multivariate adaptive regression spline(MARS) to compute the vortex tube silt ejection efficiency using the laboratory data sets. The outcomes of the artificial intelligence(AI)-based techniques also were compared with traditional models. It was found that the RT model(root mean square error, RMSE = 2.165, Nash Sutcliffe efficiency, NSE = 0.98) outperforms the other applied approaches which had relatively more significant result errors. The sensitivity analysis of the process depicts the extraction ratio as the key parameter in the computation of vortex tube silt ejector removal efficiency. The findings of the AI-based approaches discussed in the current study might be helpful for hydraulic engineers as well as researchers in the assessment of the removal efficiency of vortex tube silt ejectors.

关键词： Vortex tube silt ejector Support vector machine Random forest Random tree Multivariate adaptive regression spline

In vitro antioxidant assessment and a rapid HPTLC bioautographic method for the detection of anticholinesterase inhibitory activity of Geophila repens

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Medicine 2017年第3期15卷 231-241页

作者： umesh Chandra Dash Atish kumar Sahoo Regional Plant Resource Centre Medicinal & Aromatic Plant Division Forest & Environment DepartmentGovt. of Odisha Nayapalli Bhubaneswar 751015 India

OBJECTIVE： Geophila repens （L.） I. M. Johnst. （Rubiaceae）, a small, creeping, perennial herb, is claimed to have memory-enhancing property. The goal of this study was to assess its antioxidant and anticholinesterase activity and conduct a rapid bioautographic enzyme assay for screening acetylcholinesterase （ACHE） and butyrylcholinesterase （BChE） inhibition of G. repens extracts. METHODS： Antioxidant activity of G. repens extracts was assessed by performing 1,1-diphenyl-2- picrylhydrazyl （DPPH）, nitric oxide （NO）, superoxide （SOD）, hydroxyl （OH） and total antioxidant capacity （TAC） assays. Anticholinesterase activity was investigated by quantifying the AChE and BChE inhibitory activities of chloroform （CGR）, ethyl acetate （EGR） and methanol （MGR） extract fractions from G. repens leaves. A rapid high-performance thin-layer chromatography （HPTLC） bioautographic method for the detection of AChE and BChE inhibition was performed. RESULTS： Among all extract fractions, EGR exhibited the highest half maximal inhibitory concentration （IC50） in DPPH, SOD, NO, OH and TAC assays, with IC50 of （38.33 ± 3.21）, （45.14 ±1.78）, （59.81± 1.32）, （39.45 ± 0.79） and （43.76 ± 0.81 ） μg/mL respectively. EGR displayed competitive, reversible inhibition of AChE and BChE activities with IC50 of （68.63±0.45） and （59.45 ±0.45）μg/mL, respectively. Total phenolic and flavonoids contents of EGR were found to be 360.42 mg gallic acid equivalents and 257.31 mg quercetin equivalents per gram of extract. Phytoconstituents of the EGR extract that were inhibitors of cholinesterase produced white spots on the yellow background of HPTLC plates in the bioautographic test. CONCLUSION： The results of this study revealed that phenols and flavonoids could be responsible for the antioxidant, anticholinesterase activities of G. repens.

关键词： Geophila repens Alzheimer disease acetylcholinesterase butyrylcholinesterase fingerprint bioautographic phenolic, antioxidant

Rate-dependent mechanical behavior of jointed rock with an impersistent joint under different infill conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1380-1393页

作者： Sachin kumar Gaurav tiwari Venkitanarayanan Parameswaran Arghya Das Department of Civil Engineering Indian Institute of TechnologyKanpurIndia

Transition in the rate-dependent mechanical response of rock was investigated due to the presence of impersistent joint with different infill conditions.Four types of samples,i.***.intact,jointed with no grouting,jointed and grouted with cement,and jointed and grouted with epoxy,were fabricated using model material.A series of dynamic split Hopkinson pressure bar(SHPB) tests was conducted on prepared samples with strain rates varying between 53-130 salong with static uniaxial compression tests(10s).Progression of fracture/failure along samples was monitored using high-speed imaging and digital image correlation(DIC).Strength was observed to be significantly lower for jointed samples as compared to intact samples.However,the increasing trend of strength with strain rates remained similar for all types of samples.Epoxy was observed to be a better grout due to greater improvement in the strength of epoxy grouted jointed samples than cement grouted samples under both static and dynamic conditions.Significant changes were observed in fracture behavior(initiation,pattern and mechanism)with strain rate for intact and jointed unfilled/grouted samples.Fracturing was dominated by shear and tensile cracks at high strain rates compared to tensile cracks at low strain rates in all samples.Unlike static loading conditions,the location of cracks initiation shifts away from joint tips with increasing strain rate and depending upon existing infill conditions(unfilled/grouted).

关键词： Jointed rocks Grouted joint Dynamic loading Strain rates

Performance assessment of aged binder rejuvenated with Polanga oil

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2019年第6期6卷 608-620页

作者： Sujit kumar Pradhan umesh Chandra Sahoo School of Infrastructure Indian Institute of Technology BhubaneswarOdisha 752050India

Presently,there is a necessity of increasing the reclaimed asphalt pavement(RAP)content in recycling of asphalt pavements to save material cost,preserve energy and protect the environment and efforts are being made to utilize 100%RAP in the mixes.RAP binder is usually stiff due to oxidation and loss of volatiles.So addition of high amount of RAP to the asphalt mix,may make it prone to fatigue failure.Due to this reason,rejuvenators are added to restore some of the physical and chemical properties for desired performance of the mixture.In this study,a locally available non-edible oil known as Polanga oil(biological name:Calophyllum inophyllum)has been explored as rejuvenator to study its effect on performance of the aged binders.Aged binder prepared in the laboratory using the Pressure Aging Vessel(PAV)and binder extracted from the RAP collected from a nearby source were used in this study for rejuvenation.Aged binder and RAP binder mixed with the rejuvenator at varying percentages.The rheological characterizations in terms of flow,rutting,fatigue and creep recovery of rejuvenated PAV aged&RAP binders were carried out using a dynamic shear rheometer(DSR)to determine the optimum dosage of the rejuvenator.It was observed that,5 percent of Polanga oil is able to divulge the desirable rheological properties of the rejuvenated binder.

关键词： Virgin bitumen Reclaimed asphalt pavement Rejuvenator Polanga oil Aged bitumen Rheology

Effects of in ovo delivered xylo-and mannan-oligosaccharides on growth performance,intestinal immunity,cecal short-chain fatty acids,and cecal microbiota of broilers

在线全文

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2022年第4期13卷 1099-1114页

作者： Amit kumar Singh Utsav Prakash tiwari Birendra Mishra Rajesh Jha Department of Human Nutrition Food and Animal SciencesUniversity of Hawaii at Manoa1955 East-West RdHonoluluHI 96822USA

Background:This study investigated a novel in ovo feeding strategy to determine the prebiotic effects of xylo-and mannan-oligosaccharides(XOS and MOS)differing in the degree of polymerization.A total of 192 fertilized eggs were divided into 6 treatment groups:i)normal saline control(NSC),ii)xylotriose(XOS3),iii)xylotetraose(XOS4),iv)mannotriose(MOS3),v)mannotetraose(MOS4),and vi)no injection control(NIC),each containing 4 replicate trays with 8 eggs per replicate.On d 17 of incubation,3 mg of oligosaccharides(except for controls)dissolved in 0.5 mL of 0.85%normal saline were injected into the amnion of Cobb 500 broilers eggs.After hatch,the chicks were raised for 28 d under standard husbandry practices and were fed a commercial broilers diet ad libitum,and samples were collected periodically.Results:The hatchability,growth performance,and relative weights of breast,drumstick,liver,and proventriculus were not different among the treatments(P>0.05).The XOS3 injection increased the total short-chain fatty acid production at d 28 compared with both control groups(P0.05).On the hatch day,the expression level of the CD3 gene(a T cell marker)was increased by XOS3,while the IL-10 gene(a marker of anti-inflammatory cytokine)was reduced by MOS4(P0.05),except XOS4 increased IL-4 compared with NSC(P<0.05).The broilers in the MOS4 group had higher operational taxonomic units(OTUs)and had more differentially abundant taxa,including order Lactobacillales and family Leuconostocaceae(P<0.05)than both controls on d 28.The predictive functional profiling indicated that the linoleic acid metabolism pathway was enriched in the cecal microbiota of the XOS3

关键词： Broilers Gut health Immunity in ovo Mannanoligosaccharides Microbiota Oligosaccharides Prebiotics Xylooligosaccharides