检索结果-南通市图书馆

China Communications 2024年第9期21卷 292-320页

作者： Gulab Sah Sweety Singh subhasish banerjee Computer Science and Engineering National Institute of Technology Arunachal PradeshIndia

The key objective of intrusion detection systems(IDS)is to protect the particular host or network by investigating and predicting the network traffic as an attack or *** IDS uses many methods of machine learning(ML)to learn from pastexperience attack *** based and identify the new *** though these methods are effective,but they have to suffer from large computational costs due to considering all the traffic features,***,emerging technologies like the Internet of Things(Io T),big data,*** getting advanced day by day;as a result,network traffics are also increasing ***,the issue of computational cost needs to be addressed ***,in this research,firstly,the ML methods have been used with the feature selection technique(FST)to reduce the number of features by picking out only the important ones from NSL-KDD,CICIDS2017,and CIC-DDo S2019datasets later that helped to build IDSs with lower cost but with the higher performance which would be appropriate for vast scale *** experimental result demonstrated that the proposed model *** tree(DT)with Recursive feature elimination(RFE)performs better than other classifiers with RFE in terms of accuracy,specificity,precision,sensitivity,F1-score,and G-means on the investigated datasets.

关键词： CICIDS2017 dataset classifiers IDS ML NSL KDD dataset RFE

维普期刊数据库

Fluid Inclusion Characteristics of Tungsten Mineralization in the Agargaon Area of Sakoli Fold Belt, Central India

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2020年第3期31卷 559-570页

作者： Girish Kumar Mayachar subhasish Ghosh National Centre for Excellence in Geoscience Research Remote Sensing and Aerial SurveyGeological Survey of IndiaBangalore 560078India

The Lower to Middle Proterozoic Sakoli fold belt in Central India forms a triangular belt with significant mineralization of strategic *** Sakoli fold belt comprises metasediments,felsic and mafic volcanics with metabasalts bounded by the gneissic-migmatitic *** last pulses of granitic activity in the form of quartz lenses intrude the metasediments and are associated with tungsten *** metasediments are intruded by the quartz veins and tourmaline breccias trending 60°N to 65°E and 60°S to 65°W and are parallel to the regional structural *** tungsten mineralization in this area is restricted to tourmaline-quartz mica greisens and quartz *** NE-SW trending foliated contact zones of chlorite mica schist and porphyritic granite/gneisses have served as easy channels for the mineralizing vapours and solutions to percolate,which formed ore bearing greisens and quartz *** mineralization is erratic and manifested by sparse and sporadic disseminations of wolframite and scheelite associated with minor amount of molybdenite and *** fluid inclusion microthermometry on mineralized quartz veins and quartz-tourmaline veins reveals the existence of a metamorphogenic aqueous-gaseous(H2O-CO2+NaCl)fluid that underwent phase separation and gave rise to gaseous(CO2)*** salinity of tungsten mineralizations varies from low to high(1.32 wt.%to 40.44 wt.%NaCl eq.).The estimated P-T range of tungsten mineralization varies from 1.2 to 2.2 kbar at 280 to 390℃.Raman spectroscopy reveals that the fluid inclusions mainly contain H2O and CO2 with rarely H2S and *** isotopic data reveal that the sulfur isotope fractions from the depositsδ^34S ranging from+3.1‰to+3.35‰,suggesting the deep crustal source for the sulfur,which can be further interpreted as a single(magmatic)supply of sulfur during magmatic-hydrothermal *** studies reveal the presence of chlorides such as FeCl2/MgCl2 and CaCl2,indicating t

关键词： Sakoli fold belt fluid inclusions tungsten

维普期刊数据库

Influence of bank vegetation and gravel bed on velocity and Reynolds stress distributions

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2009年第2期24卷 236-246页

作者： Hossein AFZALIMEHR subhasish DEY Department of Water Engineering Isfahan University of Technology Department of Civil Engineering Indian Institute of Technology

This paper presents the results of a laboratory flume experimental study on the interaction of bank vegetation and gravel bed on the flow velocity(primarily on the location of the maximum velocity,Umax) and the Reynolds stress distributions. The results reveal that the dip of the maximum velocity below the water surface is up to 35% of flow depth and the difference between Umax and the velocity at the water surface is considerable in the presence of vegetation on the walls. The zone of the log-law varies from y/h=2 up to 15 percent of flow depth and it does not depend on distance from the wall. Deviation of the velocity profile in the outer layer over a gravel bed with vegetation cover on the walls is much larger than the case of flow over a gravel bed without vegetation cover on the walls. The presence of vegetation on the walls changes uniform flow to non-uniform flow. This fact can be explained by considering the nonlinear Reynolds stress distribution and location of maximum velocity in each profile at different distances across the flume. The Reynolds stress distributions at the distance 0.02 m from the wall have negative values and away from the wall,they change the sign taking positive values with specific convex form with apex in higher location. Average of von Karman constant κ for this study is equal to 0.16. Based on κ=0.16,the methods of Clauser and the Reynolds stress are compatible for determination of shear velocity.

关键词： Bank vegetation Uniform flow Reynolds stress Gravel bed Von Karman constant

Circulation characteristics of horseshoe vortex in scour region around circular piers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Water Science and Engineering 2013年第1期6卷 59-77页

作者： subhasish DAS Rajib DAS Asis MAZUMDAR School of Water Resources Engineering Jadavpur University

This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV）. Velocity vector plots and vorticity contours of the flow field on the upstream plane of symmetry （y = 0 cm） and on the planes ：e3 cm away from the plane of symmetry Cv = ~3 cm） are presented. The vorticity and circulation of the horseshoe vortices were determined using the forward difference technique and Stokes theorem, respectively. The results show that the magnitudes of circulations are similar on the planes y = 3 cm and y = -3 cm, which are less than those on the plane y = 0 cm. The circulation decreases with the increase of flow shallowness, and increases with the densimetric Froude number. It also increases with the pier Reynolds number at a constant densimetric Froude number, or at a constant flow shallowness. The relative vortex strength （dimensionless circulation） decreases with the increase of the pier Reynolds number. Some empirical equations are proposed based on the results. The predicted circulation values with these equations match the measured data, which indicates that these equations can be used to estimate the circulation in future studies.

关键词： experimental investigation," open channel turbulent flow," scour," horseshoe vortex,"circulation," circular pier forward difference technique," Stokes theorem

维普期刊数据库

Interfacial instability of sand patterns induced by turbulent shear flow

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2021年第4期36卷 449-456页

作者： Sk Zeeshan Ali subhasish Dey Department of Civil Engineering Indian Institute of Technology Hyderabad Department of Civil Engineering Indian Institute of Technology Kharagpur Department of Hydraulic Engineering State Key Laboratory of Hydro-Science and Engineering Tsinghua University

When a turbulent shear flow above a plane sand surface entrains sand grains, it generates a variety of sand patterns. Fluvial sand forms two major interfacial patterns: meso-scale dunes and antidunes, and large-scale bars. Measurements have evidenced that under erosive conditions, meso-scale patterns either change to or coexist with large-scale patterns. However, it remains elusive what exactly drives the switching of interfacial patterns and how the switching occurs. Here, we showdcombing a flow model with a grain transport model, allowing for both the surface and suspended sand fluxes dthat the switching of patterns emerges from the shear-driven complex feedback between grain transport and topographic perturbations. The switching predominantly depends on the magnitudes of the Rouse number and the grain size to undisturbed flow depth ratio. The model offers quantitative predictions of the maximum amplification of sand patterns and unveils a new attraction erepulsion phenomenon.

关键词： Instability Sand patterns Turbulent flow Sediment transport

Suspended load in flows on erodible bed

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2009年第3期24卷 315-324页

作者： Sujit K. BOSE subhasish DEY Visiting Fellow Department of Civil Engineering Indian Institute of Technology Chair Prof. Department of Civil Engineering Indian Institute of Technology

Steady state suspended-load of sediment transported in flow over erodible beds usually is treated by the advection-diffusion approach, though in recent years, it is being treated as a two-phase flow phenomenon incorporating kinetics of sediment particles. Among the advection-diffusion approaches, Rouse’s equation is the well-known, although a number of researchers in later periods have attempted to improve it by modifying the mixing length concept taking into account other aspects. In this paper, the advection-diffusion approach and associated logarithmic law of flow velocity are revisited. It is concluded from the logarithmic law that the Reynolds shear stress is a linear function of height above the bed, which reduces to bed shear stress in the case of a long horizontal channel. As a consequence, it is shown that the volumetric concentration of sediment is best approximated by the sum of two power laws of height above the bed. An equation is derived for the suspended-load transport rate in terms of elementary functions.

关键词： Sediment transport Fluvial hydraulics Suspended load Open channel flow

Bedload transport from analytical and turbulence phenomenological perspectives

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2019年第6期34卷 509-530页

作者： subhasish Dey Sk Zeeshan Ali Ellora Padhi Department of Civil Engineering Indian Institute of Technology Kharagpur Department of Hydraulic Engineering State Key Laboratory of Hydro-Science and EngineeringTsinghua University Physics and Applied Mathematics Unit Indian Statistical Institute Kolkata

In this paper,we present the dynamics of bedload transport from two different *** are the analytical perspective and the turbulence phenomenological *** bedload transport from the analytical perspective,we highlight the systematic advances in the analytical modelling of bedload transport over the *** advances are principally classified into three broad foundations,namely,the deterministic foundation,that includes the bed shear stress concept,stream power concept,force balance concept and bedform concept,and the probabilistic foundation and the turbulence phenomenological foundation of bedload *** bedload transport from the turbulence phenomenological perspective brings into focus the bedload-induced turbulence phenomenology,including the hydrodynamics of mobile-bed and water-worked bed *** also discuss the recent advances in the biofilm-coated bedload ***,conclusion is drawn,highlighting the major research challenges.

关键词： Bedload transport Fluvial hydraulics Sediment transport Turbulent flow

Electronic correlation in nearly free electron metals with beyond-DFT methods

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 1756-1762页

作者： subhasish Mandal Kristjan Haule Karin M.Rabe David Vanderbilt Department of Physics and Astronomy West Virginia UniversityMorgantownWVUSA Department of Physics and Astronomy Rutgers UniversityPiscatawayNJUSA

For more than three decades,nearly free-electron elemental metals have been a topic of debate because the computed bandwidths are significantly wider in the local density approximation to density-functional theory(DFT)than indicated by angle-resolved photoemission(ARPES)***,we systematically investigate this using first principles calculations for alkali and alkaline-earth metals using DFT and various beyond-DFT methods such as meta-GGA,G0W0,hybrid functionals(YS-PBE0,B3LYP),and LDA+*** find that the static non-local exchange,as partly included in the hybrid functionals,significantly increase the bandwidths even compared to LDA,while the G0W0 bands are only slightly narrower than in *** agreement with the ARPES is best when the local approximation to the self-energy is used in the LDA+eDMFT *** infer that even moderately correlated systems with partially occupied s orbitals,which were assumed to approximate the uniform electron gas,are very well described in terms of short-range dynamical correlations that are only local to an atom.

关键词： metals assumed narrow

Response of Reynolds stresses and scaling behavior of high-order structure functions to a water-worked gravel-bed surface and its implication on sediment transport

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 2022年第1期37卷 1-13页

作者： Nadia Penna Ellora Padhi subhasish Dey Roberto Gaudio Dipartimento di Ingegneria Civile Università Della Calabria Department of Civil Engineering Shiv Nadar University Department of Civil Engineering Indian Institute of Technology Kharagpur

The aim of this experimental study is to investigate the interaction between turbulent flow and a gravelbed that mimics the actual roughness structures of a natural bed and its implication on sediment *** particular,the response of the Reynolds stresses and the role of intermittency to the bed roughness is the primary focus of the current *** this end,the flow field,measured with an Acoustice Doppler Velocimeter (ADV),is thoroughly examined,considering the conditional Reynolds shear stresses and the high-order structure functions of *** study results show that the features and the roughness structure of the water-worked gravel-bed (WWGB) have a strong impact on bursting *** reason for this is attributed to the flow layer above the crest in the WWGBs being primarily affected by sweep events rather than ejection events,although the latter events are prevalent in this flow layer in an immobile,man-made,*** coherent structures,which are primarily responsible for sediment transport,also are the key cause of the presence of an intermittency excess that breaks the Kolmogorov self-similarity hypothesis,leading to multi-fractal behavior of the velocity structure functions.

关键词： Water-worked bed Turbulent flow Sweeps Ejections High-order structure functions

Systematic beyond-DFT study of binary transition metal oxides

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2019年第1期5卷 124-131页

作者： subhasish Mandal Kristjan Haule Karin M.Rabe David Vanderbilt Department of Physics and Astronomy Rutgers UniversityPiscatawayNJUSA

Various methods going beyond density functional theory(DFT),such as DFT+U,hybrid functionals,meta-GGAs,GW,and DFTembedded dynamical mean field theory(eDMFT),have been developed to describe the electronic structure of correlated materials,but it is unclear how accurate these methods can be expected to be when applied to a given strongly correlated *** is thus of pressing interest to compare their accuracy as they apply to different categories of *** we introduce a novel paradigm in which a chosen set of beyond-DFT methods is systematically and uniformly tested on a chosen class of *** a first application,we choose the target materials to be the binary transition metal oxides FeO,CoO,MnO,and NiO in their antiferromagnetic phase and present a head-to-head comparison of spectral properties as computed using the various *** also compare with available experimental angle-resolved photoemission spectroscopy(ARPES),inverse-photoemission spectroscopy,and with optical *** the class of compounds studied here,we find that both B3LYP and eDMFT reproduce the experiments quite well,with eDMFT doing best,in particular when comparing with the ARPES data.

关键词： materials oxides transition