检索结果-南通市图书馆

Tomographic PIV investigation of coherent structures in a turbulent boundary layer flow

Acta Mechanica Sinica 2012年第3期28卷 572-582页

作者： Zhan-Qi Tang Nan Jiang andreas schroder Reinhard Geisler Department of Mechanics Tianjin University300072 TianjinChina Tianjin Key Laboratory of Modern Engineering Mechanics 300072 TianjinChina Institute of Aerodynamics and Flow Technology Department of Experimental MethodsBunsenstrasse 1037073 GiSttingenGermany

Tomographic particle image velocimetry was used to quantitatively visualize the three-dimensional co- herent structures in the logarithmic region of the turbulent boundary layer in a water tunnel. The Reynolds number based on momentum thickness is Reo = 2 460. The in- stantaneous velocity fields give evidence of hairpin vortices aligned in the streamwise direction forming very long zones of low speed fluid, which is flanked on either side by high- speed ones. Statistical support for the existence of hairpins is given by conditional averaged eddy within an increasing spanwise width as the distance from the wall increases, and the main vortex characteristic in different wall-normal re- gions can be reflected by comparing the proportion of ejec- tion and its contribution to Reynolds stress with that of sweep event. The pre-multiplied power spectra and two-point cor- relations indicate the presence of large-scale motions in the boundary layer, which are consistent with what have been termed very large scale motions （VLSMs）. The three dimen-sional spatial correlations of three components of veloc- ity further indicate that the elongated low-speed and high- speed regions will be accompanied by a counter-rotating roll modes, as the statistical imprint of hairpin packet structures, all of which together make up the characteristic of coherent structures in the logarithmic region of the turbulent boundary layer （TBL）.

关键词： Tomographic particle image velocimetry Tur-bulent boundary layer Coherent structures Hairpin vortex Very large scale motion

来源：

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

Investigation of Unsteady Flow Fields for Flow Control Research by Means of Particle Image Velocimetry

引用

Journal of Flow Control, Measurement & Visualization 2014年第2期2卷 42-54页

作者： Reinhard Geisler andreas schroder Jurgen Kompenhans Department of Experimental Methods Institute of Aerodynamics and Flow TechnologyGerman Aerospace Center(DLR)GottingenGermany

Unsteady three-dimensional flow phenomena must be investigated and well understood to be able to design devices to control such complex flow phenomena in order to achieve the desired behavior of the flow and to assess their performance, even in harsh industrial environments. Experimental investigations for flow control research require measurement techniques capable to resolve the flow field with high spatial and temporal resolution to be able to perceive the relevant phenomena. Particle Image Velocimetry (PIV), providing access to the unsteady flow velocity field, is a measurement technique which is readily available commercially today. This explains why PIV is widely used for flow control research. A number of standard configurations exist, which, with increasing complexity, allow capturing flow velocity data instantaneously in geometrical arrangements extending from planes to volumes and in temporal arrangements extending from snapshots to temporarily well resolved data. With increasing complexity these PIV systems require advancing expertise of the user and growing investment costs. Using typical problems of flow control research, three different standard PIV systems will be characterized briefly. It is possible to upgrade a PIV system from a simple planar to a “high end” tomographic PIV system over a period of time, if sufficient PIV expertise can be built up and budget for additional investments becomes available.

关键词： Flow Control Flow Velocity Particle Image Velocimetry Stereo PIV Tomographic PIV

来源：

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

Manufacture and characterization of graphene membranes with suspended silicon proof masses for MEMS and NEMS applications

引用

Microsystems & Nanoengineering 2020年第1期6卷 1050-1066页

作者： Xuge Fan Anderson D.Smith Fredrik Forsberg Stefan Wagner Stephan schroder Sayedeh Shirin Afyouni Akbari andreas C.Fischer Luis Guillermo Villanueva Mikael Ostling Max C.Lemme Frank Niklaus Division of Micro and Nanosystems School of Electrical Engineering and Computer ScienceKTH Royal Institute of TechnologySE-10044 StockholmSweden Division of Integrated Devices and Circuits School of Electrical Engineering and Computer ScienceKTH Royal Institute of TechnologySE-16440 KistaSweden Faculty of Electrical Engineering and Information Technology RWTH Aachen UniversityOtto-Blumenthal-Str.2552074 AachenGermany Advanced NEMS Group École Polytechnique Fédérale de Lausanne(EPFL)1015 LausanneSwitzerland Silex Microsystems AB 17526 JärfällaSweden AMO GmbH Advanced Microelectronic Center Aachen(AMICA)Otto-Blumnethal-Str.2552074 AachenGermany

Graphene’s unparalleled strength,chemical stability,ultimate surface-to-volume ratio and excellent electronic properties make it an ideal candidate as a material for membranes in micro-and nanoelectromechanical systems(MEMS and NEMS).However,the integration of graphene into MEMS or NEMS devices and suspended structures such as proof masses on graphene membranes raises several technological challenges,including collapse and rupture of the *** have developed a robust route for realizing membranes made of double-layer CVD graphene and suspending large silicon proof masses on membranes with high *** have demonstrated the manufacture of square graphene membranes with side lengths from 7µm to 110µm,and suspended proof masses consisting of solid silicon cubes that are from 5µm×5µm×16.4µm to 100µm×100µm×16.4µm in *** approach is compatible with wafer-scale MEMS and semiconductor manufacturing technologies,and the manufacturing yields of the graphene membranes with suspended proof masses were>90%,with>70%of the graphene membranes having>90%graphene area without visible *** measured resonance frequencies of the realized structures ranged from tens to hundreds of kHz,with quality factors ranging from 63 to *** graphene membranes with suspended proof masses were extremely robust,and were able to withstand indentation forces from an atomic force microscope(AFM)tip of up to~*** proposed approach for the reliable and large-scale manufacture of graphene membranes with suspended proof masses will enable the development and study of innovative NEMS devices with new functionalities and improved performances.

关键词： proof characterization hundreds

来源：

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

The Giant Radio Array for Neutrino Detection(GRAND):Science and design

引用

Science China(Physics,Mechanics & Astronomy) 2020年第1期63卷 1-43页

作者： Jaime Alvarez-Muniz Rafael Alves Batista Aswathi Balagopal V. Julien Bolmont Mauricio Bustamante Washington Carvalho Jr. Didier Charrier Ismael Cognard Valentin Decoene Peter B.Denton Sijbrand De Jong Krijn D.De Vries Ralph Engel Ke Fang Chad Finley Stefano Gabici Quan Bu Gou Jun Hua Gu Claire Guépin Hong Bo Hu Yan Huang Kumiko Kotera Sandra Le Coz Jean-Philippe Lenain Guo Liang Léü Olivier Martineau-Huynh Miguel Mostafá Fabrice Mottez Kohta Murase Valentin Niess Foteini Oikonomou Tanguy Pierog Xiang Li Qian Bo Qin Duan Ran Nicolas Renault-Tinacci Markus Roth Frank G.schroder Fabian Schüssler Cyril Tasse Charles Timmerman Matías Tueros Xiang Ping Wu Philippe Zarka andreas Zech B.Theodore Zhang Jian Li Zhang Yi Zhang Qian Zheng Anne Zilles Departamento de Fisica de Particulas&lnstituto Galego de Fisica de Altas Enerxias Universidad de Santiago de CompostelaSantiago de Compostela 15782Spain Instituto de Astronomia Geofisica e Ciencias AtmosfericasUniversidade de Sao PauloSao Paulo-SP 05508-090Brazil Department of Physics-Astrophysics University of OxfordDWBOxford 0X13RHUK Institute of Experimental Particle Physics(ETP) Karlsruhe Institute of Technology(KIT)Karlsru he D-76021Germany Laboratoire de Physique Nucleeaire et de Hautes Energies(LPNHE) Sorbonne UniversiteUniversite Paris DiderotSorbonne Paris CiteCNRS place Jussieu F-75252Paris Cedex 5France Niels Bohr International Academy and DARK Niels Bohr InstituteCopenhagen 2100Denmark Discovery Center Niels Bohr InstituteCopenhagen 2100Denmark Center for Cosmology and AstroParticle Physics(CCA.PP)&Department of Physics Ohio State UniversityColumbus OH 43210USA Universidade de Santiago de Compostela Santiago de Compostela 15782Spain 0SUBATECH Institut Mines-Telecom Atlantique-CNRS/IN2P3-Universite de NantesNantes 44300France Laboratoire de Physique et Chimie de KEnvironnement et de VEspace LPC2E CNRS-Universite d'Orleans Orleans F-45071France Station de Radioastronomie de Nancay Observatoire de ParisCNRS/INSU F-18330 NangayFrance Sorbonne Universite UMR 7095Institut d'Astrophysique de Paris98 bis bd AragoParis 75014France Institute for Mathematics Astrophysics and Particle Physics(IMAPP)Radboud UniversiteitNijmegen 6500Netherlands Nationaal Instituut voor Kemfysica en Hoge Energie Fysica(NIKHEF) Amsterdam NL-1009Netherlands IIHE/ELEM Vrije Universiteit BrusselPleinlaan 2Brussels 1050Belgium Institute for Nuclear Physics(IKP) Karlsruhe Institute of Technology(KIT)Karlsruhe D-76021Germany Einstein Fellow Stanford UniversityStanford CA 94305USA Department of Astronomy University of MarylandCollege Park MD 20742-2421USA Joint Space-Science Institute College Park MD 20742-2421USA Oskar Klein Centre Stockholm UniversityStockholm SE-10691Sweden Department of Phy

The Giant Radio Array for Neutrino Detection(GRAND)is a planned large-scale observatory of ultra-high-energy(UHE)cosmic particles,with energies exceeding 10~8 Ge *** goal is to solve the long-standing mystery of the origin of UHE cosmic *** do this,GRAND will detect an unprecedented number of UHE cosmic rays and search for the undiscovered UHE neutrinos and gamma rays associated to them with unmatched *** will use large arrays of antennas to detect the radio emission coming from extensive air showers initiated by UHE particles in the *** design is modular:20 separate,independent sub-arrays,each of 10000 radio antennas deployed over 10000 km^2.A staged construction plan will validate key detection techniques while achieving important science goals *** we present the science goals,detection strategy,preliminary design,performance goals,and construction plans for GRAND.

关键词： radio telescopes neutrinos in astronomical observations cosmic rays in astronomical observations radiowave radiation:sources galactic and extragalactic cosmic rays:galactic and extragalactic

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：