检索结果-南通市图书馆

Development of Asymmetric Convection in a Tropical Cyclone under Environmental Uniform Flow and Vertical Wind Shear

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第12期41卷 2399-2418页

作者： Yubin LI Yuncong JIANG Johnny C.L.CHAN kevin k.W.CHEUNG School of Atmospheric Physics Nanjing University of Information Science&TechnologyNanjing 210044China Asia-Pacific Typhoon Collaborative Research Center Shanghai 201306China School of Energy and Environment City University of Hong KongHong Kong 999077China School of Emergency Management Nanjing University of Information Science&TechnologyNanjing 210044China

Idealized numerical simulations have been carried out to reveal the complexity in the development of asymmetric convection in a tropical cyclone(TC)under the influence of an environment with either uniform flow,vertical wind shear(VWS),or *** show that rainwater is enhanced to the right of the motion in the outer rainband,but such enhancement occurs in the upshear-left area of the inner-core ***,due to the asymmetries introduced by environmental flow,wavenumber-1 temperature and height anomalies develop at a radius of~1000 km in the upper levels.A sub-vortex aside from the TC center encompassing the wavenumber-1 warm center appears,and asymmetric horizontal winds emerge,which,in turn,changes the storm-scale(within 400 km)*** convection in the inner core closely follows the changing storm-scale VWS when its magnitude is larger than 2 m s^(-1) and is located downshear of the storm-scale VWS in all the experiments with environmental *** the outer rainbands,the maximum boundary layer convergence is mainly controlled by the direction of motion and is located in the rear-right *** results extend upon the findings of previous studies in three aspects:(1)The discovery of the roughly linear combination effect from the uniform flow and large-scale VWS;(2)The development of upper-level asymmetric winds on a 1000-km scale through the interaction between the TC vortex and environmental flow,resulting in changes in the storm-scale VWS pattern within the TC area;(3)The revelation that TC asymmetric convection closely aligns with the direction-varying storm-scale VWS instead of the initially designated VWS.

关键词： tropical cyclone environmental flow vertical wind shear asymmetric convection inner core outer rainband

Petrology,genesis and geodynamic implication of the Mesoproterozoic-Late Cretaceous Timmasamudram kimberlite cluster,Wajrakarur field,Eastern Dharwar Craton,southern India

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2017年第3期8卷 541-553页

作者： Ashish Dongre N.V.Chalapathi Rao k.S.Viljoen B.Lehmann Department of Geology University of Johannesburg Department of Geology Centre of Advanced StudyBanaras Hindu University Mineral Resources Technical University of Clausthal

New mineralogical and bulk-rock geochemical data for the recently recognised Mesoproterozoic （ca. 1100 Ma） and late Cretaceous （ca. 90 Ma） kimberlites in the Timmasamudram cluster （TkC） of the Wajrakarur kimberlite field （WkF）, Eastern Dbarwar Craton, southern India, are presented. On the basis of groundmass mineral chemistry （phlogopite, spinel, perovskite and clinopyroxene）, bulk-rock chem- istry （SiO2, k20, low TiO2, Ba/Nb and La/Sm）, and perovskite Nd isotopic compositions, the TI（-1 （mac- rocrystic variety） and TI（-4 （Macrocrystic variety） kimberlites in this cluster are here classified as orangeites （i.e. Group II kimberlites）, with geochemical characteristics that are very similar to orangeites previously described from the Bastar Craton in central India, as well as the kaapvaal Craton in South Africa. The remaining kimberlites （e.g., Tk-2, Tk-3 and the Tk-1 microcrystic variant）, are more similar to other 1100 Ma, Group l-type kimberlites of the Eastern Dharwar Craton, as well as the typical Group I kimberlites of the kaapvaal Craton. Through the application of geochemical modelling, based on pub- lished carbonated peridotite/melt trace element partition coefficients, we show that the generation of the TI（C kimberlites and the orangeites results from low degrees of partial melting of a metasomatised, carbonated peridotite. Depleted mantle （TDM） Nd perovskite model ages of the 1100 Ma Timmasamudram kimberlites show that the metasomatic enrichment of their source regions are broadly similar to that of the Meso- proterozoic kimberlites of the EDC. The younger, late Cretaceous （ca. 90 Ma） TI（-1 （macrocrystic variant） and Tk-4 kimberlites, as well as the orangeites from the 8astar Craton, share similar Nd model ages of 1100 Ma, consistent with a similarity in the timing of source enrichment during the amalgamation of Rodinia supercontinent. The presence of late Cretaceous diamondiferous orangeite activity, presumably related to the location of the Marion hotspot

关键词： kimberlite Orangeite Diamond Timmasamudram Wajrakarur India

Numerical analysis of surface subsidence in asymmetric parallel highway tunnels

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 170-179页

作者： Ratan Das P.k.Singh Ashutosh kainthola Suman Panthee T.N.Singh Department of Earth Sciences Indian Institute of Technology Bombay Department of Civil Engineering National Institute of Technology Central Department of Geology Tribhuvan University

Tunnelling related hazards are very common in the Himalayan terrain and a number of such instances have been reported. Several twin tunnels are being planned for transportation purposes which will require good understanding for prediction of tunnel deformation and surface settlement during the engineering life of the structure. The deformational behaviour, design of sequential excavation and support of any jointed rock mass are challenging during underground construction. We have raised several commonly assumed issues while performing stability analysis of underground opening at shallow depth. For this purpose, kainchi-mod Nerchowck twin tunnels(Himachal Pradesh, India) are taken for in-depth analysis of the stability of two asymmetric tunnels to address the influence of topography, twin tunnel dimension and geometry. The host rock encountered during excavation is composed mainly of moderately to highly jointed grey sandstone, maroon sandstone and siltstones. In contrast to equidimensional tunnels where the maximum subsidence is observed vertically above the centreline of the tunnel, the result from the present study shows shifting of the maximum subsidence away from the tunnel centreline. The maximum subsidence of 0.99 mm is observed at 4.54 m left to the escape tunnel centreline whereas the maximum subsidence of 3.14 mm is observed at 8.89 m right to the main tunnel centreline. This shifting clearly indicates the influence of undulating topography and inequidimensional noncircular tunnel.

关键词： Twin tunnels Numerical analysis Stability Finite element method(FEM) Subsidence

INITIAL BOUNDARY VALUE PROBLEM FOR A NONCONSERVATIVE SYSTEM IN ELASTODYNAMICS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2018年第3期38卷 1043-1056页

作者： k.Divya JOSEPH P.A.DINESH Department of Mathematics M.S.Ramaiah Institute of Technology MSRIT P.O Department of Mathematics M.S.Ramaiah Institute of Technology MSRIT P.O

This article is concerned with the initial boundary value problem for a nonconservative system of hyperbolic equation appearing in elastodynamics in the space time domain x 〉 0, t 〉 0. The number of boundary conditions, to be prescribed at the boundary x = 0,depends on the number of characteristics entering the domain. Because our system is nonlinear, the characteristic speeds depends on the unknown and the direction of the characteristics curves are known apriori. As it is well known, the boundary condition has to be understood in a generalised way. One of the standard way is using vanishing viscosity method. We use this method to construct solution for a particular class of initial and boundary data, namely the initial and boundary datas that lie on the level sets of one of the Riemann invariants.

关键词： Elastodynamics viscous shocks

Nitrogen Mineralization in Soils Along a Vegetation Chronosequence in Hong kong

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2005年第2期15卷 181-188页

作者： L.M.MARAFA k.C.CHAU Centre for Environmental Policy and Resource Management Centre for Environmental Policy and Resource Management Department of Geography and Resource ManagementThe Chinese University of Hong KongShatinNew TerritoriesHong Kong (China)Department of Geography and Resource ManagementThe Chinese University of Hong KongShatinNew TerritoriesHong Kong (China)

This research examined nitrogen mineralization in the top 10 cm of soils along a vegetation gradient in Hong kong at sites where fire has been absent for 0, 1, 3, 6 and 17 years (at the time of the study), and the relationships between N mineralization and successional development of vegetation in the absence of fire. The sites including a newly burnt area (S1), short grassland (S2), tall grassland (S3), mixed tall grassland and shrubland (S4), and woodland (S5) were selected,and the in situ core incubation method was used to estimate nitrogen mineralization. Throughout the 60-day incubation in four periods, more nitrogen was mineralized at the S3 and S4 sites, the predominantly grassland sites, which contained the highest levels of soil organic matter (SOM) and total kjeldahl nitrogen (TkN), than the S1 site, while immobilization occurred at the S2 and S5 sites. Leaching loss decreased with successional development of the vegetation, in the order of S1 ＞ S2 ＞ S3 ＞ S4 ＞ S5. The pattern of nitrogen uptake with ecological succession was less conspicuous, being complicated by the immediate effect of fire and possibly the ability of the woodland species to extract nitrogen from the deeper *** the absence of fire for 3 to 6 years, the build-up of SOM and TkN was accompanied by active mineralization, thus paving the way for the invasion of shrub and tree species. A close relationship existed between nitrogen mineralization and ecological succession with this vegetation gradient. Inherent mechanisms to preserve nitrogen in a fire-prone environment including immobilization and uptake and the practical relevance of nitrogen mineralization to reforestation are discussed.

关键词： fire impact immobilization nitrogen mineralization successional development vegetation chronosequence

Photoluminescence properties of ZnSe_(1-x)Te_x thin films on GaAs/ITO substrates by electron beam evaporation technique

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2011年第1期54卷 52-57页

作者： J.SUTHAGAR N.J.SUTHAN kISSINGER M.BALASUBRAMANIAM k.PERUMAL Department of Physics Karunya University School of Advanced Materials Engineering Chonbuk National University Department of Physics Kongunadu College of Arts & Science Department of Physics Sri Ramakrishna Mission Vidyalaya College of Arts & Science

Zinc chalcogenide which includes zinc selenide,zinc sulphide,zinc telluride and mixed crystals of these shows a great potential as an optoelectronic device material. Zinc selenotelluride is a suitable material for visible light emitting devices which are expected to cover the spectral range from yellow to blue. In our present study the composition controlled ZnSe1-xTex films with different Te content x = 0,0.2,0.4,0.6,0.8 and 1.0 were deposited by electron beam (EB) evaporation technique. GaAs films were deposited by vacuum evaporation route on indium tin oxide (ITO) substrates which were used as base for depositing the ZnSe1-xTex film. The band-gap energy change in the entire composition range was determined at room temperature by photoluminescence (PL) spectroscopy. The peak observed at about 2.56 eV shows the effect of solid solution formation between ZnSe and ZnTe which modifies the lattice and consequently the band edge emission characteristics. The heterostructures showed three peaks in the visible region of white light spectrum.

关键词： semiconducting II-VI materials ZnSeTe electron beam evaporation photoluminescence

On the Plasma (ion) Carburized Layer of High Nitrogen Austenitic Stainless Steel

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第5期25卷 375-377页

作者： Y. Ueda N. kanayama k. Ichii T. Oishi H. Miyake Shimane Institute for Industrial Technology 1 Hokuryo-cho Matsue Shimane 690-0816 JapanShimane Institute for Industrial Technology 1 Hokuryo-cho Matsue Shimane 690-0816 JapanFaculty of Engineering Kansai University 3-3-35 Yamate-cho Suita Osaka 564-8680 JapanFaculty of Engineering Kansai University 3-3-35 Yamate-cho Suita Osaka 564-8680 JapanFaculty of Engineering Kansai University 3-3-35 Yamate-cho Suita Osaka 564-8680 Japan

The manganese concentration of austenitic stainless steel decreases from the inner layer towards the surface of the plasma (ion) carburized layer due to the evaporation of manganese from the specimen surface. The carbon concentration in the carburized layer is influenced by alloyed elements such as Cr, Ni, Si, and Mo, as well as Nitrogen. This study examined the effects of nitrogen on the properties of the carburized layer of high nitrogen stainless steel. Plasma (ion) carburizing was carried out for 14.4 ks at 1303 k in an atmosphere of CH4+H2 gas mixtures under a pressure of 350 Pa. The plasma carburized layer of the high nitrogen stainless steel was thinner than that of an austentric stainless steel containing no nitrogen. This suggested that the nitrogen raised the activity of carbon in the plasma carburized layer, GDOES measurement indicated that the nitrogen level in the layer did not vary after plasma (ion) carburizing.

关键词：等离子渗碳高氮不锈钢奥氏体 GDOES

Acceptor doping and actuation mechanisms in Sr-doped BiFeO_(3)-BaTiO_(3)ceramics

在线全文

学校读者我要写书评

暂无评论

Journal of Materiomics 2024年第1期10卷 57-69页

作者： Ziqi Yang Yizhe Li Bing Wang Juncheng Pan Annette k.kleppe David A.Hall Department of Materials University of ManchesterM139PLManchesterUK Diamond Light Source Ltd. Harwell Science and Innovation CampusOX110DEDidcotUK

BiFeO_(3)-BaTiO_(3)(BF-BT)ceramics are important multiferroic materials,which are attracting significant attention for potential applications in high temperature lead-free piezoelectric *** the present study,the effects of Sr^(2+)as an acceptor dopant for Bi^(3+),in the range from 0 to 1.0%(in mole),on the structure and ferroelectric/piezoelectric properties of 0.7BiFeO_(3)-0.3BaTiO_(3)ceramics were *** use of a post-sintering Ar annealing process was found to be an effective approach to reduce electrical conductivity induced by the presence of electron holes associated with reoxidation during cooling.A low Sr dopant concentration(0.3%,in mole)yielded enhanced ferroelectric(P_(max)∼0.37 C/m^(2),P_(r)∼0.30 C/m^(2))and piezoelectric(d_(33)∼178 pC/N,k_(p)∼0.27)properties,whereas higher levels led to chemically heterogeneous core-shell structures and secondary phases with an associated decline in *** electric field-induced strain of the Sr-doped BF-BT ceramics was investigated using a combination of digital image correlation macroscopic strain measurements and in-situ synchrotron X-ray *** of the intrinsic(lattice strain)and extrinsic(domain switching)contributions to the electric field induced strain indicated that the intrinsic contribution dominated during the poling process.

关键词： Bismuth ferrite-barium titanate Acceptor doping Electroceramics Piezoelectricity In-situ X-ray diffraction

Progress and Challenges for Live-cell Imaging of Genomic Loci Using CRISPR-based Platforms

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

Genomics, Proteomics & Bioinformatics 2019年第2期17卷 119-128页

作者： Xiaotian Wu Shiqi Mao Yachen Ying Christopher J.krueger Antony k. Chen Department of Biomedical Engineering College of Engineering Peking University Beijing 100871 China School of Life Sciences Peking University Beijing 100871 China Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology Atlanta GA 30332 USA

Chromatin conformation,localization,and dynamics are crucial regulators of cellular behaviors. Although fluorescence in situ hybridization-based techniques have been widely utilized for investigating chromatin architectures in healthy and diseased states,the requirement for cell fix-ation precludes the comprehensive dynamic analysis necessary to fully understand chromatin activ-ities. This has spurred the development and application of a variety of imaging methodologies for visualizing single chromosomal loci in the native cellular context. In this review,we describe currently-available approaches for imaging single genomic loci in cells,with special focus on clus-tered regularly interspaced short palindromic repeats (CRISPR)-based imaging approaches. In addition,we discuss some of the challenges that limit the application of CRISPR-based genomic imaging approaches,and potential solutions to address these challenges. We anticipate that,with continued refinement of CRISPR-based imaging techniques,significant understanding can be gained to help decipher chromatin activities and their relevance to cellular physiology and pathogenesis.

关键词： CRISPR Cas9 dCas9 Genomic imaging sgRNA