检索结果-南通市图书馆

Spectral/hp element methods:Recent developments, applications, and perspectives

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 Hydrodynamics 2018年第1期30卷 1-22页

作者： Hui Xu Chris D.Cantwell Carlos Monteserin Claes Eskilsson Allan P.Engsig-Karup spencer j.sherwin Department of Aeronautics Imperial College London Department of Applied Mathematics and Computer Science Technical University of Denmark Department of Civil Engineering Aalborg University Division Safety and Transport Research Institutes of Sweden (RISE) Center for Energy Resources Engineering (CERE) Technical University of Denmark

The spectral/hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomial basis functions on coarse finite element-type meshes. The spatial approximation is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials,modified to accommodate a C~0-continuous expansion. Computationally and theoretically, by increasing the polynomial order p,high-precision solutions and fast convergence can be obtained and, in particular, under certain regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral/hp element method and provides an overview of its application to computational fluid dynamics. In particular, it focuses on the use of the spectral/hp element method in transitional flows and ocean engineering. Finally, some of the major challenges to be overcome in order to use the spectral/hp element method in more complex science and engineering applications are discussed.

关键词： High-precision spectral/hp elements continuous Galerkin method discontinuous Galerkin method implicit large eddy simulation

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

湍流的hp型谱元隐式大涡模拟

湍流的hp型谱元隐式大涡模拟

第十一届全国流体力学学术会议

作者：徐辉 Pierre Sagaut spencer j.sherwin 上海交通大学航空航天学院 Department of Aeronautics Imperial College London Aix-Marseille Université CNRSCentrale Marseille

基于高精度hp型谱元法,实施典型壁湍流问题隐式大涡模拟,隐式大涡模型基于正则化谱粘性消去法构建。针对壁湍流的流动特性,讨论了平均流动、雷诺应力、流动的各向异性特征及能谱。与典型的实验及数值模拟的基准结果相比较而言,上述物理... 详细信息

基于高精度hp型谱元法,实施典型壁湍流问题隐式大涡模拟,隐式大涡模型基于正则化谱粘性消去法构建。针对壁湍流的流动特性,讨论了平均流动、雷诺应力、流动的各向异性特征及能谱。与典型的实验及数值模拟的基准结果相比较而言,上述物理量与基准解具有良好的吻合。结果表明,基于正则化的谱粘性消去法所构建的物理模型无关的隐式大涡模型能够取得与经典模型相一致的结果,能够对具有大尺度分离的壁湍流问题实施良好的模拟。

关键词：壁湍流 hp型谱元法隐式大涡模拟

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

可压缩性及分离泡拓扑形状对转捩的影响

可压缩性及分离泡拓扑形状对转捩的影响

Selecting the most appropriate tractor using Analytic Hierarchy Process–An Iranian case study

第十一届全国流体力学学术会议

作者：徐辉 Shahid Mughal spencer j.sherwin 上海交通大学航空航天学院 Department of Aeronautics Imperial College London Department of Mathematics Imperial College London

本文研究了可压缩性对T-S波诱导层流-湍流转捩的影响作用,同时探讨了壁面缺陷诱导分离泡拓扑形状对流动稳定性及转捩的影响机制。文中考虑了两类壁面缺陷(凹陷和凸包)及两类缺陷诱导分离涡的拓扑特征。基于全局稳定性分析,研究了两类缺... 详细信息

本文研究了可压缩性对T-S波诱导层流-湍流转捩的影响作用,同时探讨了壁面缺陷诱导分离泡拓扑形状对流动稳定性及转捩的影响机制。文中考虑了两类壁面缺陷(凹陷和凸包)及两类缺陷诱导分离涡的拓扑特征。基于全局稳定性分析,研究了两类缺陷诱导分离涡对转捩的影响机制。研究表明,w针对可压缩性及分离泡对转捩影响作用的研究对流动控制具有一定的意义。

关键词：可压缩性分离泡转捩

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Information Processing in Agriculture 2016年第4期3卷 223-234页

作者： sherwin Amini Mohammad Amin Asoodar Department of Biosystems Engineering Ferdowsi University of MashhadMashhadIran Department of Agricultural Machinery and Mechanization Engineering KhuzestanRamin Agriculture and Natural Resources University of KhouzestanIran

With regard to the importance of selecting an appropriate tractor in rural areas which is one of the main tasks for most farmers,the aim of this study is to select the best tractor in Ghaemshahr and Ahvaz cities of *** methodology of the paper is descriptiveanalytic and data were collected through library and field works(interviews and questionnaires).The statistic population of this study was 25 tractors in Ghaemshahr and Ahvaz,in that 15 tractors were chosen randomly,and the data were analyzed using AHP(analytic hierarchy process).The results showed that the maximum effect regarding the selection of tractor belonged to the maintenance with 49.4%and the minimum went to ergonomic effect with 7%in Ahvaz and the maximum effect was related to price with 29.6%and the minimum went to ergonomic effect with 6.8%.ITM285 and Romania 650 with 83%were the best tractors in Ahvaz and john Deere 6150 with 83%was the best tractor in Ghaemshahr *** ratio for all the comparisons was zero,so the criteria are completely compatible with the aims and options.

关键词： Mechanization AHP technique Selecting tractor

Lumped Parameter Outflow Models for 1-D Blood Flow Simulations:Effect on Pulse Waves and Parameter Estimation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2008年第7期4卷 317-336页

作者： j.Alastruey K.H.Parker j.Peiro S.j.sherwin Department of Aeronautics Imperial College LondonSouth Kensington CampusLondon SW72AZU.K Department of Bioengineering Imperial College LondonSouth Kensington CampusLondon SW72AZU.K.

Several lumped parameter,or zero-dimensional(0-D),models of the microcirculation are coupled in the time domain to the nonlinear,one-dimensional(1-D)equations of blood flow in large arteries.A linear analysis of the coupled system,together with in vivo observations,shows that:(i)an inflow resistance that matches the characteristic impedance of the terminal arteries is required to avoid non-physiological wave reflections;(ii)periodic mean pressures and flow distributions in large arteries depend on arterial and peripheral resistances,but not on the compliances and inertias of the system,which only affect instantaneous pressure and flow waveforms;(iii)peripheral inertias have a minor effect on pulse waveforms under normal conditions;and(iv)the time constant of the diastolic pressure decay is the same in any 1-D model artery,if viscous dissipation can be neglected in these arteries,and it depends on all the peripheral compliances and resistances of the *** this analysis,we propose an algorithm to accurately estimate peripheral resistances and compliances from in vivo *** algorithm is verified against numerical data simulated using a 1-D model network of the 55 largest human arteries,in which the parameters of the peripheral windkessel outflow models are known a *** and flow waveforms in the aorta and the first generation of bifurcations are reproduced with relative root-mean-square errors smaller than 3%.

关键词： Pulse wave propagation one-dimensional modelling lumped parameter outflow models time-domain coupling arterial compliance peripheral compliance peripheral resistance multiscale modelling.

Himalayan Tectonics:Preface

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2019年第3期10卷 791-792页

作者： Kyle Larson Christopher j. spencer Tectonics and Geodynamics Earth Environmental and Geographical Sciences IKBSAS University of British Columbia Earth Dynamics Research Group The Institute for Geoscience Research (TIGeR) Department of Applied Geology Curtin University

The Himalayan-Tibetan orogen system serves as the modern paradigm for understanding convergence-related processes in orogenic belts. The advancements made studying the region have been applied to other ancient orogenic belts leading not only to a better understanding of their development, but also of secular changes in collisional processes. As more advanced methodologies are introduced and utilized in geological research, the type, scale, and quality of data available enable quantification of geological processes not previously possible. These complex and robust datasets now form the core of many of the research projects undertaken across the Himalaya and continue to provide unprecedented insight into the myriad different aspects of the evolution of the collisional system.

关键词： Himalayan-Tibetan system evolution

Stability of Projection Methods for Incompressible Flows Using High Order Pressure-Velocity Pairs of Same Degree:Continuous and Discontinuous Galerkin Formulations

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2014年第8期16卷 817-840页

作者： E.Ferrer D.Moxey R.H.j.Willden S.j.sherwin ETSIA–School of Aeronautics Universidad Politecnica de MadridPza.Cardenal Cisneros 3MadridE-28040Spain. Department of Aeronautics Imperial College LondonLondonSW72AZUK. Department of Engineering Science University of OxfordParks RoadOxfordOX13PJUK.

This paper presents limits for stability of projection type schemes when using high order pressure-velocity pairs of same *** high order h/p variational methods encompassing continuous and discontinuous Galerkin formulations are used to explain previously observed lower limits on the time step for projection type schemes to be stable[18],when h-or p-refinement strategies are *** addition,the analysis included in this work shows that these stability limits do not depend only on the time step but on the product of the latter and the kinematic viscosity,which is of particular importance in the study of high Reynolds number *** show that high order methods prove advantageous in stabilising the simulations when small time steps and low kinematic viscosities are *** upon this analysis,we demonstrate how the effects of this instability can be reduced in the discontinuous scheme by introducing a stabilisation term into the global ***,we show that these lower limits are compatible with CourantFriedrichs-Lewy(CFL)type restrictions,given that a sufficiently high polynomial order or a mall enough mesh spacing is selected.

关键词： Incompressible Navier-Stokes equations projection methods velocity-correction continuous Galerkin discontinuous Galerkin inf-sup LBB condition.

Sphere-forming corneal cells repopulate dystrophic keratoconic stroma:Implications for potential therapy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World journal of Stem Cells 2020年第1期12卷 35-54页

作者： Himanshu Wadhwa Salim Ismail jennifer j McGhee Bert Van der Werf Trevor sherwin Department of Ophthalmology Faculty of Medical and Health SciencesThe University of AucklandAuckland 1023New Zealand Department of Epidemiology and Biostatistics School of Population HealthFaculty of Medical and Health SciencesThe University of AucklandAuckland 1023New Zealand

BACKGROUND Keratoconus is a degenerative corneal disease characterised by aberrant cell behaviour and loss of matrix that can result in vision *** extracted from peripheral corneas can form stem cell-enriched spheres,which have shown the potential to repopulate the normal peripheral corneal stroma in vitro upon sphere implantation but have not been previously studied in keratoconic *** To investigate the therapeutic potential of stem cell-enriched spheres formed from extracted peripheral human corneal cells when introduced to keratoconic *** Stem cell-enriched spheres were formed from extracts of normal cadaveric human peripheral corneal *** spheres were implanted into incisions created in full thickness and onto the surface of 10μm thin sections of keratoconic and normal stromal tissues in *** sections were used to maximise use of limited keratoconic tissue available for *** cells were stained with Calcein-AM and visualised with stereo and fluorescence microscopy to assess survival and behaviours between the time of implantation day 0 and 14 d(D14)from *** cells in implanted tissues were characterised for stem cell and differentiation markers using immunohistochemistry and droplet digital PCR to assess the potential implications of these characteristics in the use of spheres in keratoconus *** Spheres were successfully implanted into full-thickness central corneal tissue and onto the surface of 10μm thin en face tissue *** observable differences were seen in sphere migration,proliferation or differentiation in keratoconic tissue compared to normal between day 0 and *** stained positively with Calcein-AM up to *** migration increased from day 0 to D14,occurring radially in three dimensions from the sphere and in alignment with tissue *** proliferation marker,EdU,was detected at day *** spheres stained positively for putative stem cell markersΔNp63

关键词： Keratoconus Cell culture Immunohistochemistry Quantitative PCR Digital PCR Spheroid Holoclone Neurosphere Regeneration

Visualising data distributions with kernel density estimation and reduced chi-squared statistic

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2017年第6期8卷 1247-1252页

作者： C.j.spencer C.Yakymchuk M.Ghaznavi Earth Dynamics Research Group The Institute of Geoscience ResearchDepartment of Applied GeologyCurtin UniversityPerthAustralia Department of Earth and Environmental Sciences University of WaterlooWaterlooCanada David R.Cheriton School of Computer Science University of WaterlooWaterlooCanada

The application of frequency distribution statistics to data provides objective means to assess the nature of the data distribution and viability of numerical models that are used to visualize and interpret *** commonly used tools are the kernel density estimation and reduced chi-squared statistic used in combination with a weighted *** to the wide applicability of these tools,we present a java-based computer application called KDX to facilitate the visualization of data and the utilization of these numerical tools.

关键词： Data visualisation Kernel density estimation Reduced chi-squared statistic Mean square weighted deviation Geostatistics