检索结果-内蒙古大学图书馆

Growth of amorphous SiO₂ nanowires on Si using a Pd/Au thin film as a catalyst

APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 2004年第3期79卷 461-467页

作者： Elechiguerra, JL Manriquez, JA Yacaman, MJ Univ Texas Dept Chem Engn Austin TX 78712 USA Univ Texas Texas Mat Inst Austin TX 78712 USA Ctr Sistemas Integrados Mfg Tecnol Monterrey Monterrey 64849 NL Mexico

Nanowires of amorphous SiO2 were synthesized by thermal processing of a Si(100) substrate at 1100degreesC in the presence of a nitrogen flow, and using a 15 nm thick high silicon-solubility Pd/Au film as a catalyst. The substrate itself was the only source of silicon for the nanowire growth. The nanostructures produced were characterized by high resolution transmission and scanning electron microscopy and by X-ray diffraction. The nanowire growth is consistent with the vapor-liquid-solid (VLS) mechanism, with particles of Pd2Si and Au(Pd) being observed to form from the reaction between silicon and the catalytic film, and to remain at the tip of the wires. The synthesized nanowires showed a well defined morphology which could be very interesting for lasing applications.

关键词： noncrystalline Virtual Linkage Subsystem terminal interface processor thin films Catalysts Nanowire

来源：评论

学校读者我要写书评

暂无评论

Performance Robustness of Turbine Squealer Tip Designs Due to Manufacturing and Engine Operation

引用

JOURNAL OF PROPULSION AND POWER 2017年第3期33卷 740-749页

作者： De Maesschalck, C. Lacor, C. Paniagua, G. Lavagnoli, S. Remiot, A. Bricteux, L. von Karman Inst Fluid Dynam Turbomachinery & Prop Dept B-1640 Rhode St Genese Belgium Vrije Univ Brussel Dept Mech Engn Triomflaan 43 B-1050 Brussels Belgium Purdue Univ Dept Mech Engn Zucrow Labs W Lafayette IN 47906 USA Univ Mons Dept Mech Engn Polytech Fac B-7000 Mons Belgium

This paper quantifies the changes in turbine performance due to manufacturing tolerances and profile degradation of the blade-tip region during engine operation. An extensive numerical study was conducted on a modern high-pressure turbine rotor, operating at high Reynolds and high subsonic outlet conditions. The stochastic collocation method was used to investigate the effects of the geometrical variability of a single squealer tip design. The variation of three geometrical characteristics was investigated: tip clearance size, squealer depth, and rim corner radius. Three-dimensional Reynolds-averaged Navier-Stokes simulations were performed to predict the aerodynamic and heat transfer characteristics. The results highlight the influence of the combined geometrical variability on the overtip flow structures, heat transfer signatures, loss development, and downstream flow characteristics. This study measures the robustness of squealer tip designs to changes in its geometry and demonstrates the necessity of anticipating the consequences of these unavoidable tip geometry variabilities in an early development stage of the turbine design optimization.

关键词： terminal interface processor turbines Precocious Development Turbine performance manufacturing tolerances Robustness manufacturing Optimal design TURBINE ROTOR flow characteristics Engine operation geometry BLADE TIPS

来源：评论

学校读者我要写书评

暂无评论

OVERVIEW OF THE SINGULAR BEHAVIOR OF ELECTROMAGNETIC-FIELDS AT EDGES AND TIPS IN BI-ISOTROPIC AND SPECIAL BIANISOTROPIC MEDIA

引用

RADIO SCIENCE 1995年第5期30卷 1349-1354页

作者： OLYSLAGER, F Electromagnetics Group Department of Information Technology University of Ghent Ghent Belgium

An overview of some recent work concerning the singular behavior of electromagnetic fields at edges and tips in bi-isotropic and some bianisotropic materials is presented. Special emphasis will be placed on the singular behavior at the tip of concentric metal cones embedded in a special bianisotropic material. Some new results for this case are presented. Finally, some general conclusions regarding the effect of chirality and anisotropy are discussed.

关键词： Singular Anisotropy terminal interface processor chirality

来源：评论

学校读者我要写书评

暂无评论

Local dielectric and strain measurements in YBa₂Cu₃O₇-_δ thin films by evanescent microscopy and Raman spectroscopy

引用

SUPERCONDUCTOR SCIENCE & TECHNOLOGY 2005年第9期18卷 1197-1203页

作者： Kleismit, RA Elashry, M Kozlowski, G Amer, MS Kazimierczuk, MK Biggers, RR Wright State Univ Dept Elect Engn Dayton OH 45435 USA MLPSO Air Force Res Labs Wright Patterson AFB OH 45433 USA Wright State Univ Dept Mech & Mat Engn Dayton OH 45435 USA Wright State Univ Dept Phys Dayton OH 45435 USA

The near-field evanescent microwave microscope is based on a coaxial transmission line resonator with a silver-plated tungsten tip protruding through an end-wall aperture. The sensor is used to measure local dielectric properties of thin-film YBa2Cu3O7-delta deposited on three different SrTiO3 bi-crystal substrates having mismatch grain boundary angles of 3 degrees, 6 degrees, and 12 degrees. The measurements in the superconducting state are below critical temperature at T = 79.4 K. The dielectric property of the superconductor within the near field of the tip frustrates the electric field and measurably changes the transmission line's resonant frequency. The shift of the resonator's frequency is measured as a function of tip-sample separation and associated changes in quality factor (A Q) image scans of the thin film are presented. A quantitative relationship between the real and imaginary parts of the local dielectric constant and the frequency shift using the method of images is established. The comparison between experimental data and theory based on this method is given and discussed. Raman measurements of the intergranular strain within the YBa2Cu3O7-delta thin film deposited on each SrTiO3 substrate in the region of the bi-crystal junction showed excellent correlation between grain boundary mismatch and induced grain boundary strain. Compressive strains normal to the a axis (i.e. tensile strains normal to the b axis) were detected across the grain boundary. The magnitude of induced strain as well as its spread away from the grain boundary increased as the mismatch angle increased.

关键词： terminal interface processor Raman spectrometry grain dielectric properties B-Axis transmission line resonator thin films granulation superconducting state Boundary FREQUENCY SHIFT Ray tracing Resonator Device Component Strain measurement Protrusion

来源：评论

学校读者我要写书评

暂无评论

Plastic deformation at the tip of a tensile crack in a non-linear kinematic hardening material

引用

INTERNATIONAL JOURNAL OF FRACTURE 2000年第2期102卷 L39-L44页

作者： Wang, CH Goldstraw, MW Aeronaut & Maritime Res Lab Fishermans Bend Vic 3207 Australia Aerostruct Technol Pty Ltd Fishermans Bend Vic 3207 Australia

The plastic deformation at the tip of a tensile crack in a nonlinear kinematic hardening material under small-scale yielding conditions is investigated, with a view to quantifying the functional dependence of crack-tip plastic blunting size on material's strain hardening parameters. It is shown by dimensional analysis that, for materials being characterised by the Armstrong-Frederick non-linear kinematic hardening rule, the crack-tip blunting parameter depends parametrically on only two non-dimensional parameters;the functional dependence is determined using a parametric finite element analysis.

关键词： Plastic strain terminal interface processor functional dependence hardening (materials) heat treating technology parameters dimensional analysis cracks kinematic hardening Finite element method METTL8 gene

来源：评论

学校读者我要写书评

暂无评论

Double sublimation system to deposit molecules from solid organic compounds onto a cryogenic substrate: Thymine on solid argon

引用

REVIEW OF SCIENTIFIC INSTRUMENTS 2005年第10期76卷 103901-1-103901页

作者： Levesque, PL Michaud, M Sanche, L Univ Sherbrooke Fac Med Grp Sci Radiat Dept Med Nucl & Radiobiol Sherbrooke PQ J1H 5N4 Canada

We report on the design, operation, and performance of a double sublimation system for the deposition of a submonolayer up to a few layers of a low-vapor pressure molecular solid compound onto a cryogenic substrate. The system consists of a primary oven (i.e., crucible type) to degas and first sublimate the compound onto the tip of a secondary oven (i.e., finger type), which is then used to transport the purified compound inside an analysis chamber and sublimate it just in front of the cryogenic substrate. The latter is kept at exactly the same position all the time, which is essential for experiments sensitive to target position. Besides, the negligible radiant heat transfer from the tip of the secondary oven allows operation in the presence of a cryogenic substrate consisting of an inert gas solid. The overall performance of the system is studied by EEL spectroscopy for thymine deposited onto a multilayer film of Ar used as an inert cryogenic substrate.

关键词： SCANNING-TUNNELING-MICROSCOPY EVAPORATION SOURCE THIN-FILMS DESORPTION SCATTERING ELECTRONS terminal interface processor Scanning Tunneling Microscope molecules solidified gases compounds mercuric chloride thin films multilayers Surjective Thymine Substrates desorption design operation Ovens

来源：评论

学校读者我要写书评

暂无评论

THE INITIAL-STAGES OF ORDERING IN CUAUI AND CUAUII

引用

JOURNAL OF MATERIALS SCIENCE 1986年第12期21卷 4395-4402页

作者： VANTENDELOO, G AMELINCKX, S JENG, SJ WAYMAN, CM UNIV ILLINOIS MAT RES LABURBANAIL 61801 UNIV ILLINOIS DEPT MET & MINING ENGNURBANAIL 61801

The initial ordering stages of CuAu have been studied by electron microscopy. At 250° C, in the CuAuI stability range, ordering proceeds fast and initially very little twinning is observed. At 390° C, in the CuAuII stability range, a long incubation time is required before CuAull platelets are nucleated. (1 1 0) twinning takes place immediately after the plate formation and is observed down to the tip of the plate. The fine structure of the periodic antiphase boundaries in CuAuII is studied by HREM; it reveals the disorder along the boundary.

关键词： terminal interface processor stream stage Antiphase boundaries plate Plates High resolution electron microscopy twinning Crystal twinning PLATES Bone Plate stability region maladjustment incubation time Twin towns and villages Twins

来源：评论

学校读者我要写书评

暂无评论

CRACK-TIP ENERGY-ABSORPTION PROCESSES IN FIBER COMPOSITES

引用

JOURNAL OF MATERIALS SCIENCE 1985年第8期20卷 2735-2749页

作者： WELLS, JK BEAUMONT, PWR UNIV CAMBRIDGE DEPT ENGNCAMBRIDGEENGLAND

Energy-absorbing processes which operate at the tip of a crack in lamina within a composite are investigated. Previous models are reviewed and revised to take account of new analyses of debonding and pull-out processes. The toughness of the lamina is then predicted using the new models and compared with the properties of the fibre, matrix and interface. Results are presented in the form of a fracture map which clearly shows the effect of constituent material properties on the lamina toughness. A parametric study identifies important variables which affect the toughness, impact performance, and notch sensitivity of laminates.

关键词： terminal interface processor Composites LAMINATE Notch sensitivity TOUGHNESS IMPACT PROPERTIES cracks Parametric study Material properties CRACK TIP

来源：评论

学校读者我要写书评

暂无评论

Single Cell Analysis with Probe ESI-Mass Spectrometry: Detection of Metabolites at Cellular and Subcellular Levels

引用

ANALYTICAL CHEMISTRY 2014年第8期86卷 3809-3816页

作者： Gong, Xiaoyun Zhao, Yaoyao Cai, Shaoqing Fu, Shujie Yang, Chengdui Zhang, Sichun Zhang, Xinrong Tsinghua Univ Dept Chem Beijing Key Lab Microanalyt Methods & Instrumenta Beijing 100084 Peoples R China

Molecular analysis at cellular and subcellular levels, whether on selected molecules or at the metabolomics scale, is still a challenge now. Here we propose a method based on probe ESI mass spectrometry (PESI-MS) for single cell analysis. Detection of metabolites at cellular and subcellular levels was successfully achieved. In our work, tungsten probes with a tip diameter of about 1 mu m were directly inserted into live cells to enrich metabolites. Then the enriched metabolites were directly desorbed/ionized from the tip of the probe for mass spectrometry (MS) detection. The direct desorption/ionization of the enriched metabolites from the tip of the probe greatly improved the sensitivity by a factor of about 30 fold compared to those methods that eluted the enriched analytes into a liquid phase for subsequent MS detection. We applied the PESI-MS to the detection of metabolites in single Allium cepa cells. Different kinds of metabolites, including 6 fructans, 4 lipids, and 8 flavone derivatives in single cells, have been successfully detected. Significant metabolite diversity was observed among different cells types of A. cepa bulb and different subcellular compartments of the same cell. We found that the inner epidermal cells had about 20 fold more fructans than the outer epidermal cells, while the outer epidermal cells had more lipids. We expected that PESI-MS might be a candidate in the future studies of single cell "omics".

关键词： tip diameter Subcellular SINGLE CELL Epidermis terminal interface processor metabolites Fructans Cells Single-Cell Analysis cell type

来源：评论

学校读者我要写书评

暂无评论

Two-parameter (J-M) description of crack tip stress-fields for an idealized weldment in small scale yielding

引用

INTERNATIONAL JOURNAL OF FRACTURE 1998年第4期88卷 315-333页

作者： Ranestad, O Zhang, ZL Thaulow, C NTNU Dept Machine Design & Mat Technol N-7034 Trondheim Norway SINTEF Mat Technol N-7034 Trondheim Norway

The crack tip stress-field in a trimaterial finite element model has been examined. The model represents an idealised steel weldment with a crack located at the fusion line. The model was loaded with a KI displacement field to simulate small scale yielding conditions. The effect of changing the weld metal plastic properties and the HAZ layer thickness on the crack tip stress-field was studied, keeping the material properties of the HAZ and base metal constant. The results show that the calculated J-integral remains path independent in the trimaterial model. It is confirmed that the crack tip stress-fields can be normalised by the J-integral. The mismatch constraint can be characterised by a difference field, which is independent of the normalised distance from the crack tip. The results show that changes of HAZ thickness only have a small effect on the stress-fields close to the crack tip. The hardenability of the weld metal influences on the slope of the crack tip stress distribution, but for small changes in hardenability, this effect can be neglected. The results indicate that the difference fields show some radial dependence when a homogeneous reference field is used, but the radial dependence was removed by introducing an inhomogeneous reference field. The effect of changes in the weld metal yield strength has been described with a two parameter (J-M) formulation using the inhomogeneous reference field.

关键词： Elastic-plastic analysis Bimaterial interfaces Fracture Toughness ELASTOPLASTIC ANALYSIS terminal interface processor Cocaine TOUGHNESS cracks Reference Fields WELD METAL Heat affected zones WELDMENTS model cars Material properties Bone Fracture Hardenability CRACK TIP Fissure

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：