检索结果-南通市图书馆

INStABILItY Of HAGEN—POISEUILLE fLOW fOR AXISYMMEtRIC MODE

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1987年第11期8卷 1037-1044页

作者：王发民,J.t.stuart(f.R.S) Institute of Applied Math. Sinica Beijing Imperial college U.K.

An investigation is described for instability problem of flow through a pipe of circularcross *** a disturbance motion,we consider an axisymmetric nonlinear *** amplitude or modulation equation has been derived for this *** belongs to the diffusion *** coefficient of it can be negative with Reynoldsnumber increasing,because of the complex interaction between molecular diffusion *** negative diffusion,when it occurs,causes a concentration and focusing ofenergy within the decaying slug,acting as a role of reversing natural decays.

关键词： POISEUILLE fLOW fOR AXISYMMEtRIC MODE INStABILItY Of HAGEN

Responsive envelope tessellation and stochastic rotation of 4-fold penttiles

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

frontiers of Architectural Research 2014年第2期3卷 192-198页

作者： Sambit Datta stuart Hanafin Robert f. Woodbury School of Built Environment Curtin University Perth Australia School of Architecture and Building Deakin University Geelong Australia School of Interactive Arts and technology Simon Fraser University Vancouver Canada

this paper reports on the design and control of tessellated components. the study investigates a responsive envelope based on the rotation of responsive and dynamic approaches for building facades and envelopes to regulate solar shading, light control, views and thermal gain within the building. It is well known that near real-time visual output from computational simulation can significantly impact the prediction of dynamic building-environment interactions and lead to the development of smart, adaptable, net zero energy buildings. to address these motivations, this paper reports the development of an experimental simulation of a responsive envelope based on using a 4-fold penttile scheme. the simulation is developed using a novel pentagonal approach involving component （tile） design, tessellation and control methods. the paper further elaborates on the geometry and control aspects of the facade subdivision and presents the results of applying this tessellation geometry to a building envelope shading study based on facade components with rotation. finally, it tests the ＂responsiveness＂ to multiple performance metrics by applying a non-deterministic exploration method for the stochastic rotation of individual panels. the sophisticated evaluation of alternative envelope configurations for a set of performance criteria require a tighter computational coupling between modelling and control of dynamic geometry.

关键词： facade tessellation Stochastic rotation Responsive envelopesMoveable facadecomponents Parametric modelling

INStABILItY Of HAGEN-POISEUILLE fLOW fOR NON-AXISYMMEtRIC MODE

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1989年第5期10卷 407-417页

作者：王发民 J. t. stuart (f. R. S.) Institute of Mech. Academia Sinica Beijing Imperial College U. K.

An investigation is described for instability problem of flow through a pipe of circular cross section. As a disturbance motion, we consider a general non-axisym-metric mode. An associated amplitude or modulation equation has been derived for this disturbance motion. this equation belongs to a diffusion *** coefficient of it can be negative while Reynolds number increases, because of the complex interaction between molecular diffusion and convection. the negative diffusivity, when it occurs, causes a concentration and focussing of energy within decaying slugs, acting as a role of reversing natural decays.

关键词： INStABILItY Of HAGEN-POISEUILLE fLOW fOR NON-AXISYMMEtRIC MODE

Concentrations of organophosphate flame retardants in dust from cars, homes, and offices: An international comparison

在线全文

学校读者我要写书评

暂无评论

Emerging Contaminants 2016年第2期2卷 66-72页

作者： stuart Harrad Sandra Brommer Jochen f.Mueller School of Geography Earth&Environmental SciencesUniversity of BirminghamBirminghamB152TTUnited Kingdom National Centre for Environmental toxicology The University of QueenslandKessels RoadBrisbaneQueenslandAustralia

Concentrations of a number of organophosphate flame retardants(PfRs)were measured in floor dust collected from living rooms in Australia(n=42),Canada(n=14),Germany(n=22),and Kazakhstan(n=9);cars from Australia(n=39)and Germany(n=19);and offices from Germany(n=25)and Kazahkstan(n=8).PfR concentrations in these samples were compared with each other and with previously reported data for PfRs in dust from similar microenvironments in the *** data reveal significant between-country differences in both absolute concentrations and the relative abundance of specific PfRs in each of the microenvironments *** notably,concentrations of tCIPP in UK living room dust(median=21 μg g^-1)exceeded significantly(pthose in all other countries studied here;a substantial number of car dust samples contained elevated concentrations of tDCIPP,and German samples generally contained lower levels of PfRs in all microenvironments *** addition,PfRs were determined in dust samples collected from living room couches in both Australia(n=41)and the UK(n=10).the elevated concentrations of tCIPP in UK living room dust are likely attributable to the favoured use of this PfR in UK couch *** is indicated by concentrations of tCIPP in UK couch dust(median=610 μg g^-1)exceeding significantly those in Australian couch dust(median=2.9 μg g^-1).Moreover,concentrations of tCIPP in UK couch dust originating from couches 15 years old or less,display a marked relationship with the age of the couch,with concentrations in such samples increasing significantly(pth couch age.

关键词： PfRs Indoor dust Australia Germany Canada Kazakhstan

Impacts of degrading permafrost on streamflow in the source area of Yellow River on the Qinghai-tibet Plateau,China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2019年第4期10卷 225-239页

作者： MA Qiang JIN Hui-Jun Victor f.BENSE LUO Dong-Liang Sergey S.MARCHENKO stuart A.HARRIS LAN Yong-Chao State Key Laboratory of frozen Soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China College of Resources and Environment University of Chinese Academy of SciencesBeijing100049China School of Civil Engineering Harbin Institute of TechnologyHarbin150090China Hydrology and Quantitative Water Management Group Department of Environmental SciencesWageningen UniversityWageningen6708PBthe Netherlands Geophysical Institute(GIPL) University of Alaska FairbanksFairbanks99775USA Department of Geography University of CalgaryCalgaryT3A 1E4Canada

Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the tanag hydrological station)on the northeastern Qinghai-tibet Plateau,West *** and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River *** show that permafrost degradation may have released appreciable meltwater for recharging *** potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at ***/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the *** hydraulic connectivity is expected to occur during and after certain degrees of permafrost *** impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice *** evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.

关键词： Streamflow Warming climate Permafrost degradation Streamflow patterns Source area of Yellow River(SAYR)

WEAK ERROR EStIMAtES fOR tRAJECtORIES Of SPDEs UNDER SPECtRAL GALERKIN DISCREtIZAtION

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 Computational Mathematics 2018年第2期36卷 159-182页

作者： Charles-Edouard Brehier Martin Hairer Andrew M. stuart Univ Lyon CNRS Universite Claude Bernard Lyon 1 UMR5208 Institut Camille Jordan F-69622 Villeurbanne France Department of Mathematics Imperial College London London SW7 2AZ UK Computing and Mathematical Sciences California Institute of Technology 1200 E. California Blvd. MC 305-16 Pasadena CA 91125 USA

We consider stochastic semi-linear evolution equations which are driven by additive, spatially correlated, Wiener noise, and in particular consider problems of heat equation （analytic semigroup） and damped-driven wave equations （bounded semigroup） type. We discretize these equations by means of a spectral Galerkin projection, and we study the approximation of the probability distribution of the trajectories： test functions are regular, but depend on the values of the process on the interval [0, t]. We introduce a new approach in the context of quantative weak error analysis for discretization of SPDEs. the weak error is formulated using a deterministic function （It6 map） of the stochastic convolution found when the nonlinear term is dropped. the regularity properties of the It6 map are exploited, and in particular second-order taylor expansions employed, to transfer the error from spectral approximation of the stochastic convolution into the weak error of interest. We prove that the weak rate of convergence is twice the strong rate of convergence in two situations. first, we assume that the covariance operator commutes with the generator of the semigroup： the first order term in the weak error expansion cancels out thanks to an independence property. Second, we remove the commuting assumption, and extend the previous result, thanks to the analysis of a new error term depending on a commutator.

关键词： Stochastic Partial Differential Equations Weak approximation Spectral Galerkin discretization

Correlating Bladder Cancer Risk Genes with their targeting MicroRNAs Using MMiRNA-tar

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 2015年第3期13卷 177-182页

作者： Yang Liu Steve Baker Hui Jiang Gary stuart Yongsheng Bai Department of Electrical and Computer Engineering Rose-Hulman Institute of Technology Department of Math and Computer Science Indiana State University Department of Biostatistics University of Michigan Department of Biology Indiana State University the Center for Genomic Advocacy Indiana State University

the Cancer Genome Arias （tCGA）（http：//***） is a valuable data resource focused on an increasing number of well-characterized cancer genomes. In part, tCGA provides detailed information about cancer-dependent gene expression changes, including changes in the expression of transcription-regulating microRNAs. We developed a web interface tool MMiRNA-tar （http：f/***-tar） that can calculate and plot the correlation of expression for mRNA-microRNA pairs across samples or over a time course for a list of pairs under different prediction confidence cutoff criteria. Prediction confidence was estab- lished by requiring that the proposed mRNA-microRNA pair appears in at least one of three target prediction databases： targetProfiler, targetScan, or miRanda. We have tested our MMiRNA-tar tool through analyzing 53 tumor and 11 normal samples of bladder urothelial carcinoma （BLCA） datasets obtained from tCGA and identified 204 microRNAs. these microRNAs were correlated with the mRNAs of five previously-reported bladder cancer risk genes and these selected pairs exhib- ited correlations in opposite direction between the tumor and normal samples based on the cus- tomized cutoff criterion of prediction. furthermore, we have identified additional 496 genes （830 pairs） potentially targeted by 79 significant microRNAs out of 204 using three cutoff criteria, i.e.,false discovery rate （fDR）〈 0.1, opposite correlation coefficient between the tumor and normal samples, and predicted by at least one of three target prediction databases. therefore, MMiRNA- tar provides researchers a convenient tool to visualize the co-relationship between microRNAs and mRNAs and to predict their targeting relationship. We believe that correlating expression profiles for microRNAs and mRNAs offers a complementary approach for elucidating their interactions.

关键词： the Cancer Genome Atlas Bladder cancer MicroRNA mRNA Correlation target prediction

Validation of a discrete element model using magnetic resonance measurements

在线全文

学校读者我要写书评

暂无评论

Particuology 2009年第4期7卷 297-306页

作者： Christoph R.Müller stuart A.Scott Daniel J.Holland Belinda C.Clarke Andrew J.Sederman John S.Dennis Lynn f.Gladden Department of Chemical Engineering and Biotechnology University of CambridgePembroke StreetCambridge CB2 3RAUnited Kingdom

the discrete element model （DEM） is a very promising modelling strategy for two-phase granular systems. However, owing to a lack of experimental measurements, validation of numerical simulations of two-phase granular systems is still an important issue. In this study, a small two-dimensional gas- fluidized bed was simulated using a discrete element model. the dimensions of the simulated bed were 44mm × 10mm × 120 mm and the fluidized particles had a diameter dp = 1.2 mm and density ρp = 1000 kg/m^3. the comparison between DEM simulations and experiments are performed on the basis of time-averaged voidage maps. the drag-law of Beetstra et al. [Beetstra, R., van der Hoef, M.A., ＆ Kuipers,J. A. M. （2007b）. Drag force of intermediate Reynolds number flow past mono- and bidispersed arrays of spheres. AIChE Journal, 53,489-501 ] seems to give the best results. the simulations are fairly insensitive to the coefficient of restitution and the coefficient of friction as long as some route of energy dissipation during particle-particle and particle-wall contact is provided. Changing the boundary condition of the gas phase at the side-walls from zero-slip to full-slip does not affect the simulation results. Care is to be taken that the cell sizes are chosen so that a reasonable number of particles can be found in a fluid cell.

关键词： Discrete element modelling Magnetic resonance imaging Voidage Gas-fluidized beds

Habitat specialization and phylogenetic structure of tree species in a coastal Brazilian white-sand forest

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2014年第2期7卷 134-144页

作者： Alexandre A.de Oliveira Alberto Vicentini Jerome Chave Camila de t.Castanho stuart J.Davies Adriana M.Z.Martini Renato A.f.Lima Ricardo R.Ribeiro Amaia Iribar Vinicius C.Souza Instituto de Biociências Universidade de São PauloRua do Matão321Travessa 14São PauloSP 0550890Brazil Instituto Nacional de Pesquisas da Amazônia Av.AndréAraújo2936CP 478.ManausAM 69060001Brazil Evolution et DiversitéBiologique Bâtiment 4R1 UniversitéPaul Sabatier118 route de Narbonne31062 ToulouseFrance Smithsonian tropical Research Institute PO Box 37012WashingtonDC 20013-7012USA ESALQ Universidade de São Paulo.Avenida Pádua Dias11PiracicabaSP 13418900Brazil

Aims the coastal Brazilian rainforest on white-sand(restinga)ranks among the most fragmented forest types in the tropics,owing to both the patchy distribution of sandy soils and widespread coastal development *** we study the environmental and evolutionary determinants of a forest tree assemblage at a single restinga forest in Southeastern *** also explore the ability of competing hypotheses to explain the maintenance of species diversity in this forest type,which includes contrasting extremes of edaphic conditions associated with flooding *** the study was conducted in a white-sand forest permanent plot of 10.24 ha on the coastal plain of Southeastern *** plot was divided into 256 quadrats of 20×20 m,which were classified into two main edaphic habitats(flooded and drained).trees with a diameter≥1 cm at breast height were *** assembled DNA sequence data for each of the 116 morphospecies recognized using two chloroplast markers(rbcL and matK).A phylogenetic tree was obtained using the maximum likelihood method,and a phylogenetic distance matrix was produced from an ultrametric *** analyzed similarity in floristic composition and structure between habitats and related them to cross-plot distances using permutation *** model torus shift simulations were performed to obtain a statistical significance level for habitat association for each *** phylogenetic structure for the two habitats and for each 20×20 m quadrat was calculated using the mean phylogenetic distance weighted by species abundance and checked for significance using the standardized effect size generated by 5000 randomizations of phylogenetic tip *** findings Our results indicate that partitioning among edaphic habitats is important for explaining species distributions and coexistence in restinga *** distributions within the plot were found to be non-random:there was greater floristic similarity within than betwe

关键词： habitat association torus-translation test phylogenetic community structure niche partitioning edaphic condition