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The Effect of an Incident Electron Beam on the I-V Characteristics of a Au-ZnSe Nanowire-Au Nanostructure

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Chinese Physics Letters 2013年第4期30卷 209-213页

作者： TAN Yu wang yan-guo Science College Hunan Agricultural UniversityChangsha 410128 Beijing Laboratory of Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesP.O.Box 603Beijing 100190

In order to the modify electron transport property of a metal-semiconductor nanowire(NW)-metal(M-S-M)nanostructure,the effect of high-energy electron irradiation on the current-voltage(I–V)characteristics of M-S-M nanostructure is investigated by in situ transmission electron *** measured I–V characteristics of an M-S-M nanostructure can be obviously modified under electron beam *** current increases rapidly due to increase of the carrier densities resulting from the electron-hole pair excitation in the NW irradiated by the electron *** the electron beam is focused on the NW(M-S)nanocontact,the electrons in the Au electrode are excited to higher energy states above the height of the Schottky barrier that becomes transparent to the conduction *** a result,the nonlinear to linear I–V characteristics can be *** experimentally revealed I–V characteristics corresponding to transformation from the rectification to Ohm strongly suggest that the intrinsic transport property of the M-S nanocontact can be completely modified by irradiation of the high-energy electron beam.

关键词： property Electron excited

Current Density-Sensitive Welding of a Semiconductor Nanowire to a Metal Electrode

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Chinese Physics Letters 2013年第1期30卷 199-203页

In situ welding of a single ZnSe nanowire(NW)to an Au electrode has been successfully achieved by means of current-induced Joule *** parameter governing the welding of semiconductor NW to the metal electrode is highly dominated by the current density at the Au-ZnSe NW(M-S)contact because current density at the M-S contact can change the temperature profile along the *** self-heating behaviors of the Au-ZnSe NW-Au(M-S-M)nanostructure can be changed from the electrical failure of the ZnSe NW to the melting of the Au electrode localized at the M-S contact when the current density at the M-S junction was adjusted to be larger than in the ***,the self-welding is the current density-sensitive and controllable since the current density at the M-S contact can be controlled by adjusting the contact area between the NW and metal *** controlled self-welding may have potential applications in the construction of a complex nanostructure and improvement of the thermal stability of the M-S contact as well as the enhanced performance of the nanodevices based on the M-S-M nanostructure.

关键词： welding electrode contact

Strain-Sensitive Current-Voltage Characteristics of ZnSe Nanowire in Metal-Semiconductor-Metal Nanostructure

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Chinese Physics Letters 2013年第11期30卷 175-179页

作者： TAN Yu wang yan-guo Science College Hunan Agricultural UniversityChangsha 410128 Beijing National Laboratory of Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesP.O.Box 603Beijing 100190

Experimental investigation of electrical transport properties is carried out by in situ transmission electron microscopy(TEM)to explore the effect of local strain in ZnSe nanowires(NWs)on improvement of electron transport of Au-ZnSe NW-Au(M-S-M)*** results show that the threshold voltage due to the Schottky barrier at the metal-semiconductor NW(M-S)nanocontact is found to decrease significantly when the ZnSe NW bends at the Au-ZnSe junction by the movable probe which can apply longitudinal compression,leading to current-voltage(I–V)characteristics of the M-S-M nanostructure being transformed from a nearly symmetrical to an asymmetrical *** of the I–V characteristic can be ascribed to significant depression of the Schottky barrier at the M-S nanocontact due to the band gap being narrowed by highly localized *** a result,the I–V characteristics of the M-S-M nanostructure are strain-sensitive and can be modified by local strain intentionally produced in the semiconductor *** modifiable I–V characteristics of M-S-M nanostructure confirm that the strain can be used for improvement of transport property of the semiconductor NW-based nanoelectronics with the M-S-M nanostructure.

关键词： transport barrier structure

Elimination of the Schottky Barrier at an Au-ZnSe Nanowire Nanocontact via in Situ Joule Heating

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Chinese Physics Letters 2013年第1期30卷 204-207页

In order to improve electron transport,in situ Joule heating of an Au-ZnSe nanowire-Au(M-S-M)nanostructure is conducted inside transmission electron microscopy(TEM)until the Au metal is molten at the reversely biased Au-ZnSe nanowire(M-S)*** observed microstructural evolution is responsible for the electron transport property changes,i.e.a nonlinear to linear transformation in the current-voltage(I–V)relationship was measured in situ before and after the Joule *** linear characteristic in the I–V relationship confirms elimination of the Schottky barrier at the M-S nanocontact and formation of ohmic ***,electron transport at the M-S nanocontact can be significantly improved by the removal of the Schottky barrier via in situ Joule heating.

关键词： Schottky ZnSe barrier

BEM/FDM Conjugate Heat Transfer Analysis of a Two-dimensional Air-cooled Turbine Blade Boundary Layer

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Journal of Thermal Science 2008年第3期17卷 199-206页

作者： wang Zhenfeng yan Peigang guo Zhaoyuan Han Wanjin School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China

A coupled boundary element method （BEM） and finite difference method （FDM） are applied to solve conjugate heat transfer problem of a two-dimensional air-cooled turbine blade boundary layer. A loosely coupled strategy is adopted, in which each set of field equations is solved to provide boundary conditions for the other. The Navier-Stokes equations are solved by HIT-NS code. In this code, the FDM is adopted and is used to resolve the convective heat transfer in the fluid region. The BEM code is used to resolve the conduction heat transfer in the solid region. An iterated convergence criterion is the continuity of temperature and heat flux at the fluid-solid interface. The numerical results from the BEM adopted in this paper are in good agreement with the results of analytical solution and the results of commercial code, such as Fluent 6.2. The BEM avoids the complicated mesh needed in other computation method and saves the computation time. The results prove that the BEM adopted in this paper can give the same precision in numerical results with less boundary points. Comparing the conjugate results with the numerical results of an adiabatic wall flow solution, it reveals a significant difference in the distribution of metal temperatures. The results from conjugate heat transfer analysis are more accurate and they are closer to realistic thermal environment of turbines.

关键词： Conjugate heat transfer Boundary elements Finite difference Air-cooled gas turbine.

Numerical Investigation on the Effects of Re-Organized Shock Waves on the Flow Separation for a Highly-Loaded Transonic Compressor Cascade

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Journal of Thermal Science 2012年第1期21卷 13-20页

作者： wang yan gang guo Rui Zhao Longbo Ren Siyuan School of Power ＆ Energy Northwestern Polytechincal University

This paper presents a detailed numerical investigation of the influence of re-organized shock waves on the flow separation for a highly-loaded transonic compressor cascade. The boundary layer suction (BLS) was used to control the location and strength of shock waves, with the aspirated slot locating at 49% chord, where is just downstream of the impingement point of shock wave at the leading edge. The numerical simulation is based on NUMECA, a commercial software, where the cell-centered control volume approach with third-order spatial accuracy is used to solve the 3-D Reynolds-averaged Navier-Stokes equations under the Cartesian coordinate system. Several conclusions can be made through the observation of the numerical results. (1) Multiple shock waves in cascade passage leaded the velocity deficits of boundary layer on suction surface downstream of shock wave, resulting in seriously separated flow on the suction side of blade, especially when the front shock wave is much stronger than the rest of the shocks. (2) BLS with small mass flow rate can not effectively improve the boundary layer. When the impingement point of oblique shock wave coming from cascade leading edge is bled to downstream of the passage shock wave by BLS, the boundary layer flow is greatly improved. However, if the BLS mass flow rate exceeds a critical value (1.2%), the boundary layer downstream of shock wave would separate from suction surface. (3) At the blade mid-span, the aerodynamic performance of compressor blade is improved as BLS mass flow rate increases. The optimum BLS is about 1.2%. Compared with the baseline case, the BLS with flow rate of 1.2% increases the total pressure recovery coefficient by 12%, and decreases diffusion factor by 18% and deviation angle to 7 ° while keeping the pressure rise constant. (4) The three dimensional flow structure of the compressor cascade ranged from 25% span to 75% span was improved greatly with the 1.2% BLS flow rate. However it could not control th

关键词： suction flow shock wave boundary layer interaction effects

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以学生为中心的“工程测量学”教学改革探索

教育教学论坛 2024年第20期 66-69页

作者：王国艳秦艳慧袁长丰青岛理工大学土木工程学院山东青岛266520

秉承“以学生为中心、持续改进”的教育教学理念,以能力培养为导向,对“工程测量学”课程内容和教学模式进行优化设计,搭建在线学习平台,为学生提供全方位的学习指导,以便学生随时随地完成学习任务;开发测量实验在线预约系统,为课程期... 详细信息

秉承“以学生为中心、持续改进”的教育教学理念,以能力培养为导向,对“工程测量学”课程内容和教学模式进行优化设计,搭建在线学习平台,为学生提供全方位的学习指导,以便学生随时随地完成学习任务;开发测量实验在线预约系统,为课程期间由于不可抗力未能完成测量实验的学生开辟渠道,完成实验内容;采用线上线下有机结合的方式,增强过程性考核的客观性,完善课程教学过程性考核的评价方式,提高教学效率,以此保障教学活动的顺利开展,提高教学质量,达到教学目的。

关键词：学习平台实验在线预约在线测试过程性考核

4-Amino-1,2,4-triazole Resin-supported Palladium Complex as Phosphine-free Catalyst for Suzuki Reaction in Aqueous Phase

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Chemical Research in Chinese Universities 2010年第2期26卷 331-334页

作者： WU Xiang-mei wang yan guo Sheng-rong College of Chemistry and Life Science Lishui University Lishui 323000 P. R. China

1 Introduction The Suzuki cross-coupling reaction is a powerful and versatile method for the generation of unsymmetrical biaryls from arylboronic acids and aryl halides in a single step. However, the reaction is usually performed in the presence of Pd catalyst along with phosphine ligand, which sometimes creates practical problems because organophosphines tend to be expensive, poisonous, and air sensitive. Recently, phos-phine-free ligands,

关键词： Suzuki reaction Phosphine-free ligand Palladium 4-Amino-1,2,4-triazole resin

Electrochemical performance of C-La^(3+) codoped LiFePO_4 synthesized by microwave heating

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Rare Metals 2009年第2期28卷 127-131页

作者： Cui yan wang Miao guo Ruisong Xu Zhaohe Tianjin Univ Key Lab Minist Educ Adv Ceram & Machining Technol Tianjin 300072 Peoples R China

La3+ was selected to elevate the lattice electronic conductivity of LiFePO4,and LiFePO4/(C+La3+) cathode powders were synthesized by microwave heating using a domestic microwave oven for 35 min. The microstructures and morphologies of the synthesized materials were investigated by XRD and SEM. The electrochemical performances were evaluated by galvanostatic charge-discharge. The electrochemical performance of LiFePO4 with different La3+ contents was studied. Results indicated that the initial specific disch...

关键词： LiFePO4 codoping microwave heating electrochemical performance