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Aeroservoelastic model based active control for large civil aircraft

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 {2.,beijing 100084,china 2.School of Astronautics and Aeronautics,tsinghua {2.,beijing 100084,china 1. department of Computer Science and Technology Tsinghua University Beijing 100084 China2. School of Astronautics and Aeronautics Tsinghua University Beijing 100084 China

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

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A verifiable low-level concurrent programming model based on colored Petri nets

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Science china(Information Sciences) 2011年第10期54卷 2013-2027页

作者： WANG ShengYuan & DONG Yuan department of Computer Science and Technology,tsinghua {2.,beijing 100084,china 1. department of Computer Science and Technology Tsinghua University Beijing 100084 China

Concurrent programs written in a machine-level language are being used in many areas,but the verification of such programs brings various new challenges to the programming language *** of existing contributions on verifying the safety properties of concurrent programs are for high-level languages,specifications,or calculi in the *** to the lack of abstraction at a low level,additional work is needed to extend these methods to machine-level *** paper describes an approach to integrate Petri nets into low-level concurrent programs to form a new programming model (abstract machine).A program in the programming model is a restricted version of colored Petri net,with transitions colored by assembly codes for machine-level threads,and places colored by shared data consisting of memory locations or *** analysis and verification approaches for usual Petri nets can be applied indirectly for such a low-level concurrent program.

关键词： low-level concurrent programs colored Petri nets abstract machine verification

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Unramified extensions of quadratic fields

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Progress in Natural Science:Materials International 2008年第3期18卷 323-324页

作者： Wei Li, Dong Yang, Xianke Zhang department of Mathematical Sciences, tsinghua university,{2., china department of Mathematical Sciences Tsinghua University Beijing 100084 China

Let K be a global quadratic field, then every unramified abelian extension of Kis proved to be absolutely Galois when Kis a number field or under some natural conditions when Kis a function field. The absolute Galois ... 详细信息

关键词： Global quadratic fields Unramified extensions

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Non-linear Identification Based on the Method of Gauss Functions

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Communications in Nonlinear Science and Numerical Simulation 1997年第3期2卷 39-44页

作者： Qing ZHANG & Chongde LU (department of Thermal Engineering, tsinghua university ,{2., 100084) department of Thermal Engineering Tsinghua University Beijing 100084 China

ＮｏｎｌｉｎｅａｒＩｄｅｎｔｉｆｉｃａｔｉｏｎＢａｓｅｄｏｎｔｈｅＭｅｔｈｏｄｏｆＧａｕｓＦｕｎｃｔｉｏｎｓ１１ＴｈｅｐａｐｅｒｗａｓｒｅｃｅｉｖｅｄｏｎＪｕｌ．２０ｔｈ，１９９７ＱｉｎｇＺＨＡＮＧ＆Ｃｈｏｎｇｄｅ... 详细信息

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关键词： identification the method of gauss functions whole optimization

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A NEW APPROACH TO THE SIMULATION OF UNSTEADY SUBCRITICAL FLOW

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Journal of Hydrodynamics 1995年第3期7卷 84-93页

作者： Mao Ze-yu(department of Hydraulic Engineering, tsinghua university{2., P. R. china) tsinghua Univ Beijing China

The use of the specified time interval numerical schemes has been popular in applying the method of characteristics to unsteady oped-channel flow problem. Studies and analyses of several variants of those schemes have led to the derivation of a complete set of timeline-interpolation scheme in applying the method of characteristics to Saint-Venant equations. A computer model based upon this scheme has ben successfully developed for predicting free surface unsteady flow, and has been verified by field experiment. Timeline interpolations, where the characteristic lines are projected back before the current time step,demonstrate much less damping than the corresponding spatial interpolation scheme at the same discretization.

关键词： open-channel flow unsteady flow simulation characteristics method,timeline interpolation scheme

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Novel Experimental Method in the Study of Double Rydberg States by Laser Resonance Excitation

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Chinese Journal of Lasers 1997年第2期B6卷 141-146页

作者： XU Xiangyuan HUANG Wen(department of Modern Applied Physics, tsinghua university,{2., china) tsinghua Univ Beijing China

We describe a novel experimental method by introducing sequential ionization with a pulsed and a strong constant electric field in a time-of-flight mass spectrometer. This method is applied to study laser-excited double Rydberg states of neutral ytterbium atom, with the ionic resonance background in the spectrum of the double Rydberg states of Yb being greatly suppressed.

关键词： atomic double Rydberg state laser excitation field ionization

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An overview of computational photography

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Science china(Information Sciences) 2012年第6期55卷 1229-1248页

作者： SUO JinLi,JI XiangYang & DAI QiongHai department of Automation,tsinghua {2.,beijing 100084,china 1. department of Automation Tsinghua University Beijing 100084 China

Computational photography is an emerging multidisciplinary *** the last two decades,it has integrated studies across computer vision,computer graphics,signal processing,applied optics and related *** are exploring new ways to break through the limitations of traditional digital imaging for the benefit of photographers,vision and graphics researchers,and image processing *** to much effort in various associated fields,the large variety of issues related to these new methods of photography are described and discussed extensively in this *** give the reader the full picture of the voluminous literature related to computational photography,this paper briefly reviews the wide range of topics in this new field,covering a number of different aspects,including:(i) the various elements of computational imaging systems and new sampling and reconstruction mechanisms;(ii) the different image properties which benefit from computational photography,*** of field,dynamic range;and(iii) the sampling subspaces of visual scenes in the real *** on this systematic review of the previous and ongoing work in this field,we also discuss some open issues and potential new directions in computational *** paper aims to help the reader get to know this new field,including its history,ultimate goals,hot topics,research methodologies,and future directions,and thus build a foundation for further research and related developments.

关键词： computational photography computational imaging plenoptic function light field

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Co-adaptability solution to conflict events in construction projects by segmented hierarchical algorithm

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Science china(Technological Sciences) 2008年第7期51卷 932-939页

作者： HOU XueLiang1 & LU Mei2.1 department of Construction Management, tsinghua university,{2., china 2.College of Management, Xi’an university of Architecture and Technology, Xi’an 710055, china 1. department of Construction Management Tsinghua University Beijing 100084 China 2. College of Management Xi’an University of Architecture and Technology Xi’an 710055 China

In order to seek the co-adaptability solution to conflict events in construction engineering projects, a new method referred to as segmented hierarchical algorithm is proposed in this paper by means of comparing co-adaptability evolution process of conflict events to the stackelberg model. By this new algorithm, local solutions to the first-order transformation of co-adaptability for conflict events can be obtained, based upon which, a global solution to the second-order transformation of co-adaptability for conflict events can also be decided by judging satisfaction degree of local solutions. The research results show that this algorithm can be used not only for obtaining co-adaptability solution to conflict events efficiently, but also for other general decision-making problems with multi-layers and multi-subsidi-aries in project management field.

关键词： conflict co-adaptability segmented hierarchical algorithm

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SURFACE MODIFICATION OF CaCO_3 WITH DENDRITIC CARBOXYLIC ACIDS

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Chinese Journal of Polymer Science 2002年第3期20卷 231-235页

作者： Zhao-xia Guo Jian Yu Institute of Polymer Science and Engineering department of Chemical Engineering tsinghua university{2. china Tsing Hua Univ Dept Chem Engn Inst Polymer Sci & Engn Beijing 100084 Peoples R China

Nanometer calcium carbonate was modified with Frechet type polyether dendrons bearing a COOH group at thefocal point by a wet-coating technique in dichloromethane at room temperature. The interaction between CaCO;and thedendritic modifier was proven by IR and mass spectroscopy of the modified CaCO;after thorough extraction withdichloromethane. The amount of tightly bonded organic modifier was estimated by TGA. It was shown that the amount ofbonded molecules decreased with increasing generation number due to the larger number of branches. Compared tounmodified CaCO;, the modified CaCO;possess different dispersibility in water and in organic solvents.

关键词： calcium carbonate surface modification polyether dendrimer dendritic carboxylic acid

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The Fuzzy Cluster Analysis in Identification of Key Temperatures in Machine Tool

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厦门大学学报（自然科学版） 2002年第S1期41卷 88-89页

作者： ZHAO Da-quan 1, ZHENG Li 1, XIANG Wei-hong 1, LI Kang 1, LIU Da-cheng 1, ZHANG Bo-peng 2.(1. department of Industrial Engineering, tsinghua university, {2., tsinghua university, B eijing 100084, china)

The thermal-induced error is a very important sour ce of machining errors of machine tools. To compensate the thermal-induced machin ing errors, a relationship model between the thermal field and deformations was needed. The relationship can be deduced by virtual of FEM (Finite Element Method ), ANN (Artificial Neural Network) or MRA (Multiple Regression Analysis). MR A is on the basis of a total understanding of the temperature distribution of th e machine tool. Although the more the temperatures measured are, the more accura te the MRA is, too more temperatures will hinder the analysis calculation. So it is necessary to identify the key temperatures of the machine tool. The selectio n of key temperatures decides the efficiency and precision of MRA. Because of th e complexities and multi-input and multi-output structure of the relationships , the exact quantitative portions as well as the unclear portions must be taken into consideration together to improve the identification of key temperatures. I n this paper, a fuzzy cluster analysis was used to select the key temperatures. The substance of identifying the key temperatures is to group all temperatures b y their relativity, and then to select a temperature from each group as the repr esentation. A fuzzy cluster analysis can uncover the relationships between t he thermal field and deformations more truly and thoroughly. A fuzzy cluster ana lysis is the cluster analysis based on fuzzy sets. Given U={u i|i=0,...,N}, in which u i is the temperature measured, a fuzzy matrix R can be obta ined. The transfer close package t(R) can be deduced from R. A fuzzy clu ster of U then conducts on the basis of t(R). Based on the fuzzy cluster analysis discussed above, this paper identified the k ey temperatures of a horizontal machining center. The number of the temperatures measured was reduced to 4 from 32. and then the multiple regression relationshi p models between the 4 temperatures and the thermal deformations of the spind

关键词： The Fuzzy Cluster Analysis in Identification of Key Temperatures in Machine Tool

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