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In situ study on dendrite growth of metallic alloy by a synchrotron radiation imaging technology

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Science china(Technological Sciences) 2010年第5期53卷 1278-1284页

作者： wang TongMin1,XU JingJing1,LI Jun1,HUANG WanXia2,LIU Shengchu1 & LI TingJu1 1 school of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,china 2 Institute of High Energy Physics,chinese Academy of Sciences,beijing 100039,china school of Materials Science and Engineering Dalian University of Technology

This study was trying to observe the real-time dendrite growth of Sn-bi and Sn-Pb binary alloys by a synchrotron radiation imaging *** imaging system includes an intense and high brightness synchrotron radiation source,a high-resolution and fast-readout charge coupled device camera,an alloy sample and a bridgman solidification *** imaging experiments were done at beijing Synchrotron Radiation Facility with an updated synchrotron radiation imaging technique,diffraction-enhanced imaging,which was firstly used to study the dendrite growth of metallic alloy.A series of growth behavior and morphology evolution of dendrite have been in situ observed,such as columnar-to-equiaxed transition,dendrite competition,dendrite fragmentation and floating,etc.,which can offer the direct proofs to verify or improve the solidification theories of metallic *** research opens a novel window for the study of alloy solidification and enables the unambiguous understanding of solidification processes in optically opaque,metallic alloys.

关键词： dendritic growth synchrotron radiation solidification diffraction-enhanced imaging metal and alloys

The genus distributions for a certain type of permutation graphs in orientable surfaces

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Science china mathematics 2007年第12期50卷 1748-1754页

作者： Rong-xia HAO~(1+) Wei-li HE~1 Yan-pei LIU~1 Er-ling WEI~2 ~1 Department of mathematics,beijing Jiaotong University,beijing 100044,china ~2 school of Information,Renmin University of china,beijing 100872,china Department of mathematics Beijing Jiaotong University Beijing China school of Information Renmin University of China Beijing China

A circuit is a connected nontrivial 2-regular graph. A graph G is a permutation graph over a circuit c, if G can be obtained from two copies of c by joining these two copies with a perfect matching. In this paper, based on the joint tree method introduced by Liu, the genus polynomials for a certain type of permutation graphs in orientable surfaces are given.

关键词： graph, genus distribution, genus, surfaces

Limit theory of restricted range approximations of complex-valued continuous functions

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Science china mathematics 2007年第10期50卷 1427-1440页

作者： Xian-fa LUO~1 chong LI~(2+) ~1 school of mathematics and computer Science,Jishou University,Jishou 416000,china ~2 Department of mathematics,Zhejiang University,Hangzhou 310027,china school of mathematics and computer Science Jishou University Jishou China Department of mathematics Zhejiang University Hangzhou China

This paper is concerned with the problem of the best restricted range approximations of complex-valued continuous functions. Several properties for the approximating set PΩ such that the classical characterization results and/or the uniqueness results of the best approximations hold are introduced. Under the very mild conditions, we prove that these properties are equivalent that P is a Haar subspce.

关键词： restricted range approximation, Haar subspace, characterization, uniqueness

Aeroservoelastic model based active control for large civil aircraft

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Science china(Technological Sciences) 2010年第4期53卷 1126-1137页

作者： FAN Yong1,ZHU JiHong1,HU chunHua2,MENG XianYu1,wang Xiangyang2 & GE AiXue1 1 Department of computer Science and Technology,Tsinghua University,beijing 100084,china 2 school of Astronautics and Aeronautics,Tsinghua University,beijing 100084,china Department of computer Science and Technology Tsinghua University school of Astronautics and Aeronautics Tsinghua University

A modeling and control approach for an advanced configured large civil aircraft with aeroservoelasticity via the LQG method and control allocation is *** models and implementation issues for the multi-input/multi-output(MIMO) aeroservoelastic system simulation developed for a flexible wing with multi control surfaces are described.A fuzzy logic based optimization approach is employed to solve the constrained control allocation problem via intelligently adjusting the components of output vector and find a proper vector in the attainable moment set(AMS) *** basic idea is to minimize the L2 norm of error between the desired moment and achievable moment using the designing freedom provided by redundantly allocated actuators and control *** the constraints of control surfaces,in order to obtain acceptable performance of aircraft such as stability and maneuverability,the fuzzy weights are updated by the learning algorithm,which makes the closed-loop system ***,an application example of flight control designing for the advanced civil aircraft is discussed as a *** studies we have performed showed that the advanced configured large civil aircraft has good performance with the proper designed control law designed via the proposed *** gust alleviation and flutter suppression are applied with the synergetic effects of elevator,ailerons,equivalent rudders and *** results show good closed loop performance and meet the requirement of constraint of control surfaces.

关键词： modeling active control aeroelastic flutter suppression control allocation

Improvements on radiation-hardened performance of static induction transistor

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Science china(Information Sciences) 2010年第5期53卷 1089-1096页

作者： wang YongShun 1 , LUO XianLiang 1 , LI HaiRong 2 , wang ZiTing 1 , WU Rong 1 , ZHANG caiZhen 2 & LI SiYuan 2 1 school of Electronic and Information Engineering, Lanzhou Jiaotong University, Lanzhou 730070, china 2 Institute of Microelectronics, school of Physical Science and Technology, Lanzhou University, Lanzhou 730000, china school of Electronic and Information Engineering Lanzhou Jiaotong University Institute of Microelectronics School of Physical Science and Technology Lanzhou University

The radiation-hardened performances of static induction transistor (SIT) have been studied in depth in this paper. The effects of radiation of electron beam on the I-V characteristics, carrier distribution and potential distribution in the channel of SIT have been represented. A large number of electron-hole pairs are generated in the depletion region of reversely biased gate-channel PN junction. The radiation-generated electrons drift towards the drain region at high positive potential, while generated holes flow into gate region biased to the lowest potential. With the accumulation of holes in gate region, the gate potential is boosted, resulting in a decrease in the height of potential barrier in channel, and an increase in drain current. I-V characteristics of SIT in the presence of radiation have been theoretically derived, and compared with experimental results. With the increase in thickness of epitaxial layer, the radiation-hardened capability of SIT is continuously improved until the optimum thickness of 26 μm is reached. The optimum matching relationship among geometric, material and technological parameters has been represented to acquire excellent radiation-hardened performances of SIT.

关键词： static induction transistor radiation-resistant potential barrier electron beam radiationgenerated carriers

cu-catalyzed enantioselective assembly of axially chiral allylic boronates

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Science china chemistry 2024年

作者： Shuai wang jianbo Liu Wenyue Ma Qiuling Song Key Laboratory of Molecule Synthesis and Function Discovery Fujian Province University College of Chemistry at Fuzhou University State Key Laboratory of Organometallic chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences school of chemistry and chemical Engineering Henan Normal University

Highly enantioselective construction of axially chiral cyclohexylidenes is difficult and challenging due to their structural peculiarities. The development of efficient method for the assembly of novel axially chiral cyclohexylidenes becomes particularly important in axial chirality. chiral allylborons have become a focus of interest in chemical community as an important synthon as well as a backbone structure, yet an efficient and practical synthetic method for the synthesis of axially chiral allylborons have not been disclosed so far. Herein, we report a copper-catalyzed strategy which could readily access enantiopure axially chiral allylborons under mild conditions. The obtained axially chiral allylborons can also be subjected to a number of subsequent transformations as well as late modification of drug molecules, thus demonstrating the validity of the developed method.

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Applications of online monitoring technology for tailings dam on digital mine

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中国有色金属学会会刊：英文版 2011年第S3期21卷 604-609页

作者： YU Guang-ming1, SONG chuan-wang1, ZOU Jing-bo1, WU Yan-xia1, PAN Yong-zhan1, LI Liang1, LI Ran1, wang Pei-shou2, wang Yan-lei2 1. school of civil Engineering, Qingdao Technological University, Qingdao 266033, china 2. Hedong Goldmine, Zhaojin Mining Industry company, Zhaoyuan 265400, china school of civil Engineering Qingdao Technological University Qingdao 266033 China Hedong Goldmine Zhaojin Mining Industry Company Zhaoyuan 265400 China

considering its structural features, geometric shapes, service mode, environmental media, mechanical behavior, etc, the special nature and complexity of tailings dam were summarized. The technical approach to safety management for tailings dam was proposed, which is the on-line automated monitoring and early warning information. The results show that a strong theoretical basis can be provided for security monitoring and security management of tailings dam. Online automated monitoring system for tailings dam has full implementation of the information. It is applied widely in Lingnan gold mine, Xiadian gold mine and Hedong gold mine in Zhaoyuan, Shandong Province, and achieves good effect.

关键词： digital mine tailings dam online monitoring security monitoring digitization

Preparation,characterization and Visible Light Photocatalytic Activity of Nitrogen-doped TiO_2

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Journal of Wuhan University of Technology(Materials Science) 2006年第4期21卷 71-77页

作者：王正鹏 school of Environmental Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The N-doped TiO2 polycrystalline powder was synthesized through calcining the hydrolysis prodact of tetra-butyl titanate with ammonia. The photocatalytic activity of N-doped TiO2 powder with anatase phone calcined at 400℃ was 2.7 times higher than that of Degussa P25 for phenol decomposition under visible light. All samples had mesoporoas structures. X- ray photoelectron spectroscopy confirmed that a trace amount of N atoms remained in the anatase polycrystaUine TiO2 powder when calcined at 400 ℃ as substitutional atoms at the oxygen sites. UV-Vis and EPR analyses indicated that oxygen vacancy states were created during the course of N-doped TiO2 powder formation. It is considered that substitutional N atoms, oxygen vacancy, states, large bET surface areas and mesoporoas structure are important facwrs for the N-doped photocatalyst to present a high vis-activity.

关键词： photocatalyst visible Light nitrogen-doped TiO2 phenol

Advantageous properties of halide perovskite quantum dots towards energy-efficient sustainable applications

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Green Energy & Environment 2024年第6期9卷 949-965页

作者： Qian Zhao Shuo wang Young-Hoon Kim Shekhar Mondal Qingqing Miao Simiao Li Danya Liu Miao wang Yaxin Zhai jianbo Gao Abhijit Hazarika Guo-Ran Li school of Materials Science and Engineering Nankai UniversityTianjin300350China Department of Energy Engineering Hanyang UniversitySeoul04763Republic of Korea Polymers and Functional Materials Division CSIR-Indian Institute of Chemical TechnologyUppal RoadTarnakHyderabad500007India Institute of Process Engineering Chinese Academy of SciencesBeijing100190China Key Laboratory of Low-Dimensional Quantum Structures and Quantum control of Ministry of Education Department of PhysicsHunan Normal UniversityChangshHunan410081China Department of chemistry Brock University1812 Sir Isaac WaySt CatharinesOntarioCanada

As lead halide perovskite(LHP)semiconductors have shown tremendous promise in many application fields,and particularly made strong impact in the solar photovoltaic area,low dimensional quantum dot forms of these perovskites are showing the potential to make distinct marks in the fields of electronics,optoelectronics and *** so-called perovskite quantum dots(PQDs)not only possess the most important features of LHP materials,i.e.,the unusual high defect tolerance,but also demonstrate clear quantum size effects,along with exhibiting desirable optoelectronic properties such as near perfect photoluminescent quantum yield,multiple exciton generation and slow hot-carrier ***,we review the advantageous properties of these nanoscale perovskites and survey the prospects for diverse applications which include lightemitting devices,solar cells,photocatalysts,lasers,detectors and memristors,emphasizing the distinct superiorities as well as the challenges.

关键词： Perovskite quantum dot Light-emitting Detector Laser Solar cell