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Controlled free radical polymerization of styrene initiated from the alkoxyamine-functionalized silicon surface

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Science china Chemistry 2005年第5期48卷 449-458页

作者： CHEN Zhijun1, ZHOU Sikai1, LU Wenzhong1, FANG Shaoming1, JIANG Xiqun2 & YANG Changzheng2 1. college of Materials and Chemical engineering, Zhengzhou University of Light Industry, Zhengzhou 45.002, china 2. Laboratory of Mesoscopic Material Science and Department of Polymer Science & engineering, college of Chemistry & Chemical engineering, nanjing University, nanjing 210093, china 1. college of Materials and Chemical engineering Zhengzhou University of Light Industry 450002 Zhengzhou China 2. Laboratory of Mesoscopic Material Science and Department of Polymer Science & engineering College of Chemistry & Chemical Engineering Nanjing University 210093 Nanjing China

We describe a new method of fabricating a brush-like polystyrene layer anchored on the surface of the silicon substrate, which involves three steps, namely (i) the attachment of 3-methacryloxypropyltrimethoxysilane onto the silicon surface; (ii) the reaction of vinyl moiety at another extremity of the anchored 3-methacryloxypropyltrimethoxysilane to 4-Hydroxyl-2, 2, 6, 6-tetramethyl-1-piperidinyloxy (HTEMPO?) catalyzed by azobisisobutyronitrile (AIBN); (iii) living free radical grafting polymerization of styrene in the presence of HTEMPO?. The controllable living free radical polymerization permits accurate control of both the molecular weight and the polydispersity. X-photoelectron spectroscopy measurement proved that the alkoxyamine initiator layer forms on the silicon surface. XPS and Ellipsometry measurements showed that the poly-styrene chains were covalently anchored onto the silicon surface. The thickness of the grafted polymer layer can be accurately manipulated by altering the polymerization time. The new method allows synthesizing random copolymer and block copolymers by the sequential growth of monomers from the substrate surface.

关键词： polymer brush, controlled living free radical polymerization, thickness, atomic force microscopy, 3-methacryloxypropyltrimethoxysilane.

Adsorption of surfactants onto acrylic ester resins with different pore size distribution

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Science china Chemistry 2006年第5期49卷 445-453页

作者： YANG Weiben1,2,3,LI Aimin1,3,CAI Jianguo1,3,MENG Guanhua1,3 & ZHANG Quanxing1,3 1. State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,nanjing University,nanjing 210093,china 2. nanjing college of Chemical Technology,nanjing 210048,china 3. Jiangsu engineering & Technology Research Center for Organic Toxicant Control and Resource Reuse,nanjing 210038,china 1. State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University Nanjing 210093 China 2. nanjing college of Chemical Technology Nanjing 210048 China 3. Jiangsu engineering & Technology Research Center for Organic Toxicant Control and Resource Reuse Nanjing 210038 China

In this study, a series of acrylic ester resins with different pore size distribution were prepared successfully by varying the type and the amount of pore-forming agents. In order to inves-tigate the adsorption behavior and mechanism of surfactants on acrylic ester resins, three kinds of surfactants were utilized as adsorbates that were sodium 6-dodecyl benzenesulfonate (6-NaDBS), sodium 1-dodecyl benzene sulfonate (1-NaDBS) and sodium 1-dodecyl sulfonate, respectively. It was observed that the surface area was available in a particular pore size and an appropriate pore size of resins appeared to be more important for the adsorption of surfactants. As compared to commercial acrylic ester resins XAD-7 and HP2MG, 5.# and 38# resins exhibited more excellent adsorption properties toward 1-NaDBS and 6-NaDBS. The experimental equilibrium data were fitted to the Langmuir, and double-Langmuir models. Two models provided very good fittings for all resins over the temperature range studied. The investigation indicated that electrostatic attraction and hydrogen bond between resins and surfactants were the main forces and had an obvious effect on adsorption proc-ess.

关键词： acrylic ester resin, surfactant, adsorption, pore size distribution, isotherm.

Asynchronous double-precision windows based unmanned aerial vehicle real-time path planning

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Science china(Information Sciences) 2010年第2期53卷 215-222页

作者： REN Min 1 & HUO XiaoHua 2 1 college of Mechatronic engineering and automation, National University of Defense Technology, Changsha 410073, china 2 Communication Institute, Equipment Academy of Air Force, Beijing 100085. china 1. college of Mechatronic engineering and automation National University of Defense Technology Changsha 410073 China2. Communication Institute Equipment Academy of Air Force Beijing 100085 China

A real-time path planning approach based on asynchronous double-precision windows is proposed for unmanned aerial vehicles (UAVs). In this proposed method, cursory paths and elaborate paths are planned respectively in the global and local windows. Specifically, global cursory path planner and local elaborate path planner are integrated by rolling two windows on different frequencies with different modes. Simulation results demonstrate that the proposed approach is effective for realizing a balance between the optimality and the time efficiency of online path planning by adapting the range of windows and the precision of samples.

关键词： unmanned aerial vehicle (UAV) path planning rolling optimizing asynchronous double-precision windows

Preparation and characterization of nanostructured Al_2O_3-13wt.%TiO_2 ceramic coatings by plasma spraying

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Rare Metals 2009年第5期28卷 465-470页

作者： WANG Dongsheng TIAN Zongjun SHEN Lida LIU Zhidong HUANG Yinhui Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China college of Mechanical and Electrical engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Nanostructured and conventional Al2O3-13wt.%TiO2 ceramic coatings were prepared by plasma spraying with nanostructured agglomerated and conventional powders, respectively. The microstructure and microhardness of the coatings were investigated using scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and microhardness measurement. Meanwhile, the friction and wear behaviors were analyzed and compared using a ball-on-disk tribometer. The results show that the conventional coating has lamellar stacking characteristic and has some pores. However, the nanostructured coating shows a bimodal microstructure, which is composed of both fully melted regions and partially melted regions. According to the microstructural difference, the partially melted regions can be divided into liquid-phase sintered regions （a three-dimensional net or skeleton-like structure： Al2O3-rich submicron particles embedded in the TiO2-rich matrix） and solid-phase sintered regions （remained nanoparticles）. The microstructural characteristics of the liquid-phase sintered region are formed due to the selective melting of TiO2 nanoparticles during plasma spraying. On the other hand, the TiO2 and Al2O3 nanoparticles of the solid-phase sintered regions are all unmelted during plasma spraying. Due to the existence of nanostructured microstructures, the nanostructured coating has a higher microhardness, a lower friction coefficient, and a better wear resistance than the conventional coating.

关键词： surface coating nanostructured coating plasma spraying microstructure microhardness wear resistance

A new look at the response surface method for reliability analysis using chaos theory

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Earthquake engineering and engineering Vibration 2008年第3期7卷 329-335页

作者： Ding Youliang, Li Aiqun and Deng Yang college of Civil engineering, Southeast University, nanjing 210096, china Lecturer Professor PhD Student college of Civil engineering Southeast University Nanjing 210096 China

To overcome excessive computation errors and convergence failures encountered in an iterative calculation of the reliability index using the response surface method （RSM） for some nonlinear limit state functions, this study investigates an essential factor based on chaotic dynamics theory. The bifurcation diagrams of the reliability index are presented for some typical nonlinear limit state functions, and the computation results from the mapping functions due to the RSM iterations show the complicated dynamic phenomena such as the periodic oscillation, as well as bifurcation and chaos. From the numerical examples, it is concluded that the parameter of selection range fplays an important role in the convergence of the RSM iteration, and an improved RSM iterative algorithm is proposed with regard to the incorporation of the iterative sequential function of selection rangef The proposed method is shown to be efficient and to yield accurate results.

关键词： structural reliability response surface method chaotic dynamics convergence failure selection range nonlinearity

Sensitization and Intra-molecular Energy Transfer of Eu^(3+) by Tb^(3+) in Eu-Tb Binuclear Complexes/PMMA

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Journal of Wuhan University of Technology(Materials Science) 2011年第3期26卷 398-402页

作者：韩晶 college of Mechatronic engineering North University of China

A series of Eu0.5.b0.5.TTA）3Phen/PMMA （TTA=thenoyltrifluoroacetone,Phen=phenanthroline） and Eu0.5.b0.5.TTA）3Dipy/PMMA （Dipy=2,2’-dipyridyl） were prepared by in-situ *** structures of the composites were characterized by IR spectra and electron *** properties were investigated by UV-Vis spectra and fluorescence ***,the energy transfer models were set *** results indicated that polymer parts were attached with the rare-earth molecular parts in the composite luminescent ***0.5.b0.5.TTA）3Phen/PMMA and Eu0.5.b0.5.TTA）3Dipy/PMMA emitted mostly characteristic fluorescence of europium ion and intense red fluorescence with peak wavelength at 611.8 nm and bandwidth of 10.4 nm under UV excitation at 365.*** intensity of Eu0.5.b0.5.TTA）3Phen/PMMA was found to be influenced with the content of *** fluorescence emission of europium ions was greatly sensitized by terbium ions and the enhancement of red emission was most likely due to the energy transfer enhancement from Tb3＋ to Eu3＋.

关键词： sensitization energy transfer rare-earth polymer in-situ polymerization

Theoretical analysis of alloy multiplying factor by the empirical electron theory of solids and molecules

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Science china(Technological Sciences) 2007年第6期50卷 807-814页

作者： SONG YuePeng1,2, LIU GuoQuan2, LI ZhiLin3, FENG ChengMing1 1 Mechanical and Electronic engineering college, Shandong Agricultural University, Tai’an 271018, china 2 college of Materials Science and engineering, University of Science and Technology, Beijing 100083, china 3 college of Material Science and engineering, Beijing University of Chemical Technology, Beijing 100029, china Mechanical Electronic engineering college Shandong Agricultural University Tai’an 271018 China college of Materials Science engineering University of Science Technology Beijing 100083 China college of Material Science engineering Beijing University of Chemical Technology Beijing 100029 China

By introducing the distribution probability of structural units in austenite contain- ing alloying elements and considering its effects on phase transformation, this paper establishes a calculation model of distribution probability of structural units. A new valence electron structure (VES) parameter-transformation effect coefficient of alloying elements (HL), is defined and then studied both theoretically and ex- perimentally. The relationship between the parameter HL and the multiplying factor (the quenching capability factor) of alloying elements is studied. The results indi- cate that the two parameters (HL and the quenching capability factor) have the same variation characteristic and substance feature. Therefore, the multiplying factor virtually expresses the relative quantity of structural units in the alloying elements-containing austenite.

关键词： multiplying factor (the quenching capability factor), empirical electron theory of solids and molecules, transformation effect coefficient of alloying elements, structural units in austenite containing alloying elements

Heuristic for no-wait flow shops with makespan minimization based on total idle-time increments

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Science in china(Series F) 2008年第7期51卷 896-909页

作者： LI XiaoPing1,2 & WU Cheng3 1 School of Computer Science & engineering, Southeast University, nanjing 210096, china 2 Key Laboratory of Computer Network and Information Integration (Southeast University), Ministry of Education, nanjing 210096, china 3 Department of {5., Tsinghua University, Beijing 100084, china 1. School of Computer Science & engineering Southeast University Nanjing 210096 China 2. Key Laboratory of Computer Network and Information Integration (Southeast University) Ministry of Education Nanjing 210096 China 3. Department of automation Tsinghua University Beijing 100084 China

No-wait flow shops with makespan minimization are classified as NP-hard. In this paper, the optimization objective is equivalently transformed to total idle-time minimization. The independence relationship between tasks is analyzed, and objective increment properties are established for the fundamental operators of the heuristics. The quality of the new schedules generated during a heuristic is judged only by objective increments and not by the traditional method, which computes and compares the objective of a whole schedule. Based on objective increments, the time complexity of the heuristic can be decreased by one order. A seed phase is presented to generate an initial solution according to the transformed objective. Construction and improvement phases are introduced by experimental analysis. The FCH （fast composite heuristic） is proposed and compared with the most effective algorithms currently available for the considered problem. Experimental results show that the effectiveness of the FCH is similar to that of the best methods but requires far less computation time. The FCH can also be efficient in real time scheduling and rescheduling for no-wait flow shops.

关键词： no-wait flow shops heuristic makespan Tabu search

Large eddies induced by local impulse at wall of boundary layer with pressure gradients

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Progress in Natural Science:Materials International 2008年第7期18卷 873-878页

作者： Changgen Lu a,b,*, Weidong Caob, Yanmei Zhang b, Jintao Pengb a college of Atmospheric Science, nanjing University of Information Science & Technology, nanjing 210044, china b college of Environmental Science and {5., Hohai University, nanjing 210098, china college of Atmospheric Science Nanjing University of Information Science & Technology Nanjing 210044 China college of Environmental Science and engineering Hohai University Nanjing 210098 China

Large eddies induced by local impulse at the wall with pressure gradients in the boundary layer was studied by direct numerical sim- ulations. The results show that the amplitude evolution, the high and low speed stripes, the formation of streamwise vortices, the ejection and sweeping, inflexions and distortion at the mean velocity profiles, as well as other characteristics, are consistent with the experimental and other numerical results. It is also found that large eddies are easy to be excited with adverse pressure gradient in the boundary layer, and the growth of amplitudes, formation of streamwise vortices and the influencing area etc., are much larger than those with favorable pressure gradient in the boundary layer. In contrast, large eddies are hardly to be induced through local impulse disturbance at the wall with favorable pressure gradients in the boundary layer.

关键词： Boundary layer Pressure gradients Impulse Large eddies