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science china(information sciences) 2011年第3期54卷 460-468页

作者： LI HongBo , SUN ZengQi, MIN HaiBo & DENG JianQiu Department of Computer science and technology, tsinghua university, {3., china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China

In this paper, a fuzzy dynamic characteristic modeling and adaptive control method is proposed for a class of nonlinear systems. By employing fuzzy dynamic characteristic model, the controlled plant is described as a slowly time-varying fuzzy system, wherein the parameters are estimated online by using recursive Least-Squares algorithm. Under this framework, a fuzzy adaptive controller is constructed, and the stability condition of the closed-loop system is also derived. The main advantage of the proposed method lies in no requirement for the prior knowledge of system model and less parameters to tune, which allows engineers to operate it in a simple, straightforward manner. The proposed method is applied to the control of hypersonic vehicle, and simulation results are given to demonstrate the effectiveness of the obtained results.

关键词： fuzzy control dynamic characteristic model adaptive control hypersonic vehicle

Effect of carbon source on the denitrification in constructed wetlands

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Journal of Environmental sciences 2009年第8期21卷 1036-1043页

作者： LU Songliu, HU Hongying, SUN Yingxue, YANG Jia ESPC State Key Joint laboratory, Department of Environmental science and Engineering, tsinghua university, {3., china. [a]ESPC State Key Joint laboratory Department of Environmental Science and Engineering Tsinghua University Beijing 100084 China

The ability of constructed wetlands with different plants in nitrate removal were investigated. The factors promoting the rates of denitrification including organic carbon, nitrate load, plants in wetlands, pH and water temperature in field were systematically investigated. The results showed that the additional carbon source （glucose） can remarkably improve the nitrate removal ability of the constructed wetland. It demonstrated that the nitrate removal rate can increase from 20% to more than 50% in summer and from 10% to 3.% in winter, when the nitrate concentration was 3.-40 rag/L, the retention time was 24 h and 25 mg/L dissolved organic carbon （DOC） was ploughed into the constructed wetland. However, the nitrite in the constructed wetland accumulated a little with the supply of the additional carbon source in summer and winter, and it increased from 0.15 to 2 mg/L in the effluent. It was also found that the abilities of plant in adjusting pH and temperature can result in an increase of denitrification in wetlands. The seasonal change may also impact the denitrification.

关键词： constructed wetland carbon source denitrification nitrate nitrite

Inconsistency between WMAP data and released map

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Chinese science Bulletin 2010年第10期55卷 907-909页

作者： LIU Hao1 & LI TiPei1,2,3.1 Key laboratory of Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of sciences,beijing 100049,{3. 2 Department of Physics & Center for Astrophysics,tsinghua university,beijing 100084,{3. 3.Department of Engineering Physics & Center for Astrophysics,tsinghua university,beijing 100084,{3. Key laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of Physics & Center for Astrophysics Tsinghua University Beijing China Department of Engineering Physics & Center for Astrophysics Tsinghua University Beijing China

A remarkable inconsistency between the calibrated differential time-ordered data (TOD) of the Wilkinson Microwave Anisotropy Probe (WMAP) mission,which is the input for map-making,and the cosmic microwave background (CMB) temperature maps published by the WMAP team is revealed,indicating that there must exist a serious problem in the map making routine of the WMAP *** inconsistency is easy to be confirmed without the use of WMAP map-making *** view of the importance of this issue for cosmology study,we invite readers to check it by themselves.

关键词：威尔金森微波各向异性探测器 WMAP 地图制作宇宙微波背景有序数据制作软件 TOD CMB

KTN thin films prepared by pulsed laser deposition on transparent single crystal quartz(100)

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science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 33-43页

作者： WANG Xiaodong, PENG Xiaofeng & ZHANG Duanming laboratory of Phase Change and Interfacial Transport Phenomena, Department of Thermal Engineering, tsinghua university, beijing 100084, {3. Department of Physics, Huazhong university of science and technology, Wuhan 43.074, {3. 1. laboratory of Phase Change and Interfacial Transport Phenomena Department of Thermal Engineering Tsinghua University 100084 Beijing China 2. Department of Physics Huazhong University of Science and Technology 430074 Wuhan China

Using the Sol-Gel method to produce the KTN ultrafine powder and the sintering technique with K2O atmosphere to prepare KTN ceramics as the targets instead of the KTN single crystal, highly oriented KTN thin films were produced on the transparent single crystal quartz (100) by the pulsed laser deposition (PLD). Since the thermal stress sustained by the quartz is relatively small, the limit temperature of the quartz substrates(3.0℃) is much lower than that of the P-Si substrates (560℃); the prepared thin film is at amorphous state. Increasing the pulsed laser energy density in the process incorporated with annealing the film after deposition at different temperatures converts the amorphous films into crystal. The optimal pulsed laser energy density and annealing temperature were 2.0 J/cm2 and 600℃, respectively. A discussion was made to understand the mechanism of film production at relatively low substrate temperature by PLD and effects of the annealing temperatures on the forming of the perovskite phase, and optimal conditions for the orientation of the crystal grain.

关键词： PLD technology, KTN thin film, single crystal quartz, pulsed energy density, annealing, perovskitephase.

Cavitation-erosion resistance of arc ion-plated (Ti, Cr) N coatings

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science china Mathematics 2001年第S1期44卷 369-374页

作者： PAN Guoshun YANG Wenyan National Tribology laboratory, tsinghua university, beijing 100084, {3. tsinghua Univ Natl Tribol Lab Beijing 100084 Peoples R China

The cavitation-erosion behavior of (Ti,Cr)N multi-component coatings produced by arcion-plating on grey cast iron was studied by using an ultrasonic cavitation -erosion testing appara-tus and scanning electron microscopy. The test results indicated that surface roughness of thesubstrate, surface morphology of the coating, substrate bias voltage and the thickness of the coat-ing had certain influence on the erosion rate. Arc ion-plated (Ti,Cr)N multi-component coatingsshowed better cavitation -erosion resistance than single component coatings because of highermicrohardness and good adhesion.

关键词： cavitation-erosion ion plating (Ti, Cr) N coatings grey cast iron

Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

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Progress in Natural science:Materials International 2005年第6期15卷 538-544页

作者： CHENG Haobo1*, WANG Yingwei2, FENG Zhijing1 and CHENG Kai3.1. State Key laboratory of Tribiology, tsinghua university, beijing 100084, {3. 2. Department of Material sciences, Changchun university of science and technology, Changchun 13.021, {3. 3. Faculty of information and Engineering Systems, City Campus, Leeds LS1 3.E, UK) State Key laboratory of Tribiology Tsinghua University Beijing 100084 China Department of Material sciences Changchun University of Science and Technology Changchun 130021 China Faculty of information and Engineering Systems City Campus Leeds LS1 3HE UK

Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel, rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.22 nm root mean square (RMS) after 20 min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM) measurement on the polished surface can also verify the feasibility of the MRF technique.

关键词： magnetorheological finishing surface roughness computer controlled optical surfacing subsurface damage removal function.

State of the art:Mechanical behavior of soil-structure interface

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Progress in Natural science:Materials International 2009年第10期19卷 1187-1196页

作者： Ga Zhang,Jianmin Zhang State Key laboratory of Hydroscience and Engineering,tsinghua university,{3.,china [a]State Key laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

The monotonic and cyclic behavior of a soil-structure interface has a significant effect on the mechanical response of a soil-structure interaction ***,the behavior of the interface should be investigated with focusing on the individual characters different from other geomaterials.A brief introduction and critical review are presented on the state of the art of monotonic and cyclic behavior of soil- structure interface,including the test device and measurement techniques,fundamental rules and deformation mechanism,constitutive models and their applications in the numerical *** tendencies of the investigation on the interface are also predicted in this paper.

关键词： Interface Soil Mechanical behavior Test Constitutive model Numerical analysis

Study on internal quantum efficiency of blue InGaN multiple-quantum-well with an InGaN underneath layer

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science china(Technological sciences) 2010年第2期53卷 306-308页

作者： WANG JiaXing, WANG Lai, ZHAO Wei, ZOU Xiang & LUO Yi National laboratory for information science and {3./State Key laboratory on Integrated Optoelectronics, Department of Electronic Engineering, tsinghua university, beijing 100084, china 1. National laboratory for information science and {3./State Key laboratory on Integrated Optoelectronics Department of Electronic Engineering Tsinghua University Beijing 100084 China

Blue InGaN multiple-quantum-well (MQW) samples with different InxGa1-xN (x=0.01–0.04) underneath layers (ULs) were grown by metal organic vapor phase epitaxy (MOVPE). Temperature dependent photoluminescence showed that the InGaN UL can improve the internal quantum efficiency (IQE) of MQW effectively due to strain release. And a maximum IQE of 50% was obtained when the thickness and In content of the InGaN UL were 60 nm and 0.01, respectively. Furthermore, the larger In content or thickness of the InGaN UL makes the IQE lower. Arrhenius fit to the experiment data showed that the IQE fall was mainly caused by the quantity increase of the nonradiative recombination centers, which was believed related to the accumulated stress in InGaN ULs.

关键词： InGaN underneath layer (UL) multiple-quantum-well (MQW) internal quantum efficiency (IQE) Arrhenius formula

Microstructures and characteristics of deep trap levels in ZnO varistors doped with Y_2O_3

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science china(Technological sciences) 2009年第12期52卷 3668-3673页

作者： LIU Jun 1 ,HU Jun 1 ,HE JinLiang 1 ,LIN YuanHua 2 &LONG WangCheng 1 1State Key laboratory of Power Systems,Department of Electrical Engineering,tsinghua university,beijing 100084,{3. 2State Key laboratory of New Ceramics and Fine Processing,Department of Material science and Engineering,tsinghua university, beijing 100084,{3. 1. State Key laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China 2. State Key laboratory of New Ceramics and Fine Processing Department of Material Science and Engineering Tsinghua University Beijing 100084 China

In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y2O3.are *** on the phase and microstructures of the samples indicates that an additional phase is detected in the samples doped with Y2O3.and the average grain size of the specimens decreases from about 9.2μm to 4.5μm,with an increase in the addition of Y2O3.from 0 mol%to 3.mol%.The corresponding varistor’s voltage gradient markedly increases from 462 V/mm to 23.0 V/mm,while the nonlinear coefficient decreases from 22.3.to 11.5,***,the characteristics of deep trap levels in these ZnO samples are investigated by measuring their dielectric *** trap energy level and capture cross section evaluated by relaxation peak of the Cole-Cole plot vary slightly as the addition of Y2O3.*** traps may be ascribed to the intrinsic defects of ZnO lattice.

关键词： ZnO varistors Y2O3 electrical properties deep trap levels

Control allocation for a V/STOL aircraft based on robust fuzzy control

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science china(information sciences) 2011年第6期54卷 1321-1326页

作者： FAN Yong , MENG XianYu, YANG XiLi, LIU Kai & ZHU JiHong Department of science and technology, tsinghua university, {3., china 1. Department of science and technology Tsinghua University Beijing 100084 China

This study addresses the design of an output-feedback H-infinity and fuzzy mixed controller for an advanced vertical and/or short take-off and landing aircraft that exhibits satisfactory global stability criteria. A fuzzy logic based optimization approach is employed to solve autonomously the constrained control allocation problem by suitably adjusting the components of the output vector and finding a proper vector in the attainable moment set. Simulations show that the designed fuzzy controller is better suited to resist external disturbances, and is robust against parameter perturbations.

关键词： V/STOL tailless robust control fuzzy control allocation