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Effects of Si Content and the Addition Amount of Al-3B Master Alloy on the Solidification Structures of Hypoeutectic Al-Si Alloys

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Rare Metals 2001年第3期20卷 168-173页

作者： Donghui wang,Jianguo Li, Yankang Zheng, Bingzhe Bai department of {2. science and engineering, tsinghua university, beijing 100084, China 清华大学北京 100084

Effects of Si content and the addition amount of Al-3B master alloy on the solidification structures of hypoeutectic Al-Si alloys were studied. The addition amounts of the master alloy were 0.2., 0.4%, 0.7% and 1% (mass fraction, so as the follows), respectively. The Si content of Al-Si binary alloys investigated varied from 1% to 11%. The observation of macrostructures of non-refined samples showed that 3% Si constitutes a transition point at which the minimum grain size can be obtained. It was also found that Al-3B master alloy can shift the transition point towards a higher Si value when its addition amount increases, making this point appear at 4%, 5% and 6% Si as its addition amount increases up to 0.4%, 0.7% and 1%, respectively.

关键词： Al-3B master alloy hypoeutectic Al-Si alloy grain refinement

Synthesis,field emission and microwave absorption of carbon nanotubes filled with ferromagnetic nanowires

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science China(Technological sciences) 2010年第6期53卷 1453-1459页

作者： LV RuiTao1,KANG FeiYu1,GU JiaLin1,wang KunLin2.& WU DeHai2.1 Laboratory of Advanced materials,{2. of materials science and engineering,tsinghua university,beijing 100084,China 2.{2. of Mechanical engineering,tsinghua university,beijing 100084,China Laboratory of Advanced materials Department of Materials Science and Engineering Tsinghua University

Carbon nanotubes filled with ferromagnetic metal nanowires (M-CNTs) were synthesized by using chlorine-contained benzene (***) as *** wall thicknesses of M-CNTs synthesized by trichlorobenzene are much thinner than those by precursor without Cl (***).As-synthesized thin-walled M-CNTs exhibit remarkably enhanced field electron emission performance with a low turn-on field of 0.3 V/μm and better field-emission ***-absorption coatings were made by dispersing as-synthesized M-CNTs into epoxy resin *** is found that the reflection losses in S-band (2.4 GHz),C-band (4-8 GHz) and X-band (8-12.GHz) are enhanced in the order of FeCoNi-CNTs 2.35 kg/m2.when the coating thickness is 2.0 *** demonstrates that M-CNTs are promising to be used as lightweight and wide-band microwave absorbers.

关键词： carbon nanotubes ferromagnetic nanowires field emission microwave absorption

Density-functional formula for strongly correlated systems

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Progress in Natural science:materials International 2005年第5期15卷 395-401页

作者： wang Huaiyu1*, HAN Rushan2.and CHEN Nanxian1(1. department of Physics, {2., beijing 100084, China 2. department of Physics, Peking university, beijing 100871, China) department of Physics Tsinghua University Beijing 100084 China department of Physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

A Rationalization of Sympathetic Nucleation-Ledgewise Growth Theory of Bainite Transformation in Fe-C Alloys

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Journal of materials science & Technology 2001年第4期17卷 433-438页

作者： Zhigang YANG, Chi ZHANG, Hongsheng FANG, Jinbo YANG, Bingzhe BAI and Jiajun wang department of {2. science and engineering, tsinghua university beijing 100084, China Dept. of Mat. Sci. and Eng. Tsinghua Univ. Beijing 100084 China

Based on the classic diffusion controlled nucleation and goth theory, the sympathatic nucleation- ledgewise growth mechanism of bainite was studied theoretically for low carbon Fe-C alloys. The rationality of the occurrence of sympathetic nucleation on the terraces of ledges compating with lateral ledge growth and other sites nucleation was demonstrated by the present work quantita- tively The calculations indicated that low reaction temperatures and high carbon concentrations may favor the sympathetic nucleation, thus accounting for the formation of multilayer structures of bainite.

关键词： A Rationalization of Sympathetic Nucleation-Ledgewise Growth Theory of Bainite Transformation in Fe-C Alloys Fe

Implementation of a multiple round quantum dense coding using nuclear magnetic resonance

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science China(Physics,Mechanics & Astronomy) 2005年第6期48卷 706-715页

作者： ZHANG Jingfu1, XIE Jingyi2. wang Chuan1, DENG Zhiwei3, LU Zhiheng4, & LONG Guilu1,5 1. Key Laboratory For Quantum Information and Measurements of MOE, department of Physics, {2., beijing 100084,China 2. department of materials science and engineering, beijing Normal university, beijing 100875, China 3. Testing and Analytical Center, beijing Normal university, beijing 100875,China 4. department of Physics, beijing Normal university, beijing 100875, China 5. Key Laboratory For atomic and Molecular Nanosciences, {2., beijing 100084,China Key Laboratory For Quantum Information and Measurements Department of Physics Tsinghua University Beijing 100084 China department of materials {2. and engineering Beijing Normal University Beijing 100875 China Testing and Analytical Center Beijing Normal University Beijing 100875 China department of Physics Beijing Normal University Beijing 100875 China Key Laboratory for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China

A multiple round quantum dense coding scheme based on the quantum phase estimation algorithm is proposed and implemented in a three qubit nuclear magnetic resonance (NMR) quantum computer. Using an m + 1 qubit system, Bob can transmit one of 2.+1 messages to Alice, through manipulating only one qubit and exchanging it between Alice and Bob for m rounds. The information capacity is enhanced to m + 1 bits as compared to m bits in a classical scheme. The scheme has been demonstrated in NMR system, and the experimental results show a good agreement between theory and experiment.

关键词： quantum dense coding, multiple round, nuclear magnetic resorance

Measuring-basis-encrypted six-state quantum key distribution scheme

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Progress in Natural science:materials International 2006年第1期16卷 84-89页

作者： CHEN Pan1, DENG Fuguo1, wang Pingxiao1 and LONG Guilu1,2.(Key Laboratory for Quantum Information and Measurements and department of Physics, {2., beijing 100084, China 2. Key Laboratory for Atomic and Molecular Nanosciences, {2., beijing 100084, China) Key Laboratory for Quantum Information and Measurements and department of Physics Tsinghua University Beijing 100084 China

A six-state quantum key distribution scheme with measuring-basis encryption technique, which is based on the six-state protocol and the MBE protocol, is proposed. In this modified six-state quantum key distribution protocol, Alice and Bob use a control key to synchronize the use of their measuring-basis so that they always use the same measuring-basis. This modified six-state quantum key distribution protocol retains the advantage of higher security and at the same time has a higher efficiency.

关键词： quantum key distribution measuring-basis encrypted six-state security.

A normalized thoracic coordinate system for atlas mapping in 3D CT images

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Progress in Natural science:materials International 2008年第1期18卷 111-117页

作者： Hongkai wang,Jing Bai*,Yonghong Zhang department of Biomedical {2.,tsinghua university,beijing 100084,China department of Biomedical engineering Tsinghua University Beijing 100084 China

In this paper,a normalized thoracic coordinate system(NTCS)is defined for rapidly mapping the 4D thoracic organ atlas into indi- vidual CT volume *** coordinate system is defined based on the thoracic *** coordinate values are normalized by the size of the individual thorax so that this coordinate system is universal to different *** compensating the respiratory motion of the organs,a 4D dynamic torso atlas is introduced.A method for mapping this dynamic atlas into the individual image using the NTCS is also *** this method,the dynamic atlas was mapped into the clinical thoracic CT images and rough positions of the organs were found *** NTCS-based 4D atlas mapping method may provide a novel way for estimating the thoracic organ positions in low-resolution molecular imaging modalities,as well as in modern 4D medical images.

关键词： Atlas mapping Registration Segmentation Molecular imaging

Preparation of NiFe binary alloy nanocrystals for nonvolatile memory applications

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science China(Technological sciences) 2010年第9期53卷 2320-2322页

作者： wang Li,SUN HongFang,ZHOU HuiHua & ZHU Jing beijing National Center for Electron Microscopy Laboratory,{2. of materials science and engineering,tsinghua university,beijing 100084,China beijing National Center for Electron Microscopy Laboratory Department of Materials Science and Engineering Tsinghua University

In this work,an idea which applies binary alloy nanocrystal floating gate to nonvolatile memory application was *** relationship between binary alloy’s work function and its composition was discussed theoretically.A nanocrystal floating gate structure with NiFe nanocrystals embedded in SiO2.dielectric layers was fabricated by magnetron *** micro-structure and composition deviation of the prepared NiFe nanocrystals were also investigated by TEM and EDS.

关键词： nanocrystal nonvolatile memory work function magnetron sputtering

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural science:materials International 2005年第5期15卷 453-457页

作者： LI Chensha1*, wang Dazhi1, ZHANG Baoyou2. wang Xiaofeng1, CAO Maosheng3 and LIANG Ji1(1. {2. of Mechanical engineering, tsinghua university, beijing 100084, China 2. Center for Analysis and Measurement, Harbin Institute of Technology, Harbin 150001, China 3. School of Material science and engineering, tsinghua university, beijing 100084, China) department of Mechanical engineering Tsinghua University Beijing 100084 China Center for Analysis and Measurement Harbin Institute of Technology Harbin 150001 China School of Material science and engineering Tsinghua University Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.