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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,department of Materials Science and Engineering,tsinghua university,beijing 100084,china 2 department of Mechanical Engineering,tsinghua university,beijing 100084,china 1. Laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua University Beijing 100084 China2. Department of Mechanical Engineering Tsinghua University Beijing 100084 China

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

Extremal functions for the Moser-Trudinger inequalities on compact Riemannian manifolds

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Science china Mathematics 2005年第5期48卷 618-648页

作者： LI Yuxiang department of Mathematical Sciences, tsinghua university, beijing 100084, china 1. department of Mathematical Sciences Tsinghua University 100084 Beijing China

Let (M,g) be a compact Riemannian manifold without boundary, and (N,g) a compact Riemannian manifold with boundary. We will prove in this paper that the and can be attained. Our proof uses the blow-up analysis.

关键词： Moser-Trudinger inequality extremal function n-Lapalace Green function.

APPLICATION OF MOLECULAR ORBITAL THEORY TO ANALYSIS OF PHASE STABILITY FOR ALLOYS

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Acta Metallurgica Sinica(English Letters) 1993年第3期6卷 145-152页

作者： YIN Hong TAO Kun PAN Jinsheng LI Hengde tsinghua university,beijing,china professor.department of Materials Science and Engineering,tsinghua university,beijing 100084,china tsinghua Univ Beijing China

The critical _d vahues ( _ ) of the γ/(γ+σ).γ/(γ+μ) and γ/(γ+γ') phase boundaries in some ternar alloy phase diagrams at various temperatures are calculated by averaging the _d values of sererai selected characteristic points at the phase *** equations for the temperature dependence of the critical _d of γ/(γ+σ).γ/(γ+μ) and γ/(γ+γ') phase boundaries are *** accuracy of the analysis is discussed in detail. It is found for the first time that the average value of the bond order _ at the phase boundaries ts also approximatelr a constant and therefore a critical average bond order _ like - can be introduced for the analysts of phase stability

关键词： molecular orbital theory allov phase stabilitv

EXTRACTION KINETICS,SYNERGISTIC EFFECTS AND INTERFACIAL CHEMISTRY FOR D_2 EHPA MPA-Fe^(3+) MIXED EXTRACTION SYSTEM

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Acta Metallurgica Sinica(English Letters) 1993年第12期6卷 405-410页

作者： YU Jingfen LIU Difei tsinghua university,beijing,china professor,Dept.of Chemical Engineering,tsinghua university,beijing 100084,china tsinghua Univ Beijing China

The thermodynamics of micella formation,interfacial characteristics,synergistic effects and interfacial kinetics for synergistic extraction system D_2 EHPA-MPA-Fe^(3+) have been *** was found that D_2EHPA in the mixed system strongly exhibits the effect on the micella formation thermodynamics and interracial characteristics of *** ther- modynamic parameters for constants of micelles formation(K_m).free energies of micelles formation(ΔG_m)and critical micella concentrations(CMC)were *** inter- facial adsorption behaviour of D_2EHPA is opposite to that of *** emulsification for single MPA and the mixed system was *** synergistic effects were found in this mixed extraction *** is proved that the process of the Fe^(3+) extraction for non-mixed extraction system is controlled by chemical reaction and the controlling reaction occurs at the interface.

关键词： interfacial chemistry synergistic effect Fe^(3+) extraction kinetics

Real-time reliability prediction for dynamic systems with both deteriorating and unreliable components

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Science in china(Series F) 2009年第11期52卷 2234-2246页

作者： XU ZhengGuo1,2, JI YinDong2,3 & ZHOU DongHua1,2? 1 department of Automation, tsinghua university, beijing 100084, china 2 tsinghua National Laboratory for Information Science and Technology, tsinghua university, beijing 100084, china 3 Research Institute of Information Technology (RIIT), tsinghua university, beijing 100084, china department of Automation Tsinghua University Beijing 100084 China tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China Research Institute of Information Technology (RIIT) Tsinghua University Beijing 100084 China

As an important technology for predictive maintenance, failure prognosis has attracted more and more attentions in recent years. Real-time reliability prediction is one effective solution to failure prognosis. Considering a dynamic system that is composed of normal, deteriorating and unreliable components, this paper proposes an integrated approach to perform real-time reliability prediction for such a class of systems. For a deteriorating component, the degradation is modeled by a time-varying fault process which is a linear or approximately linear function of time. The behavior of an unreliable component is described by a random variable which has two possible values corresponding to the operating and malfunction conditions of this component. The whole proposed approach contains three algorithms. A modified interacting multiple model particle filter is adopted to estimate the dynamic system＇s state variables and the unmeasurable time-varying fault. An exponential smoothing algorithm named the Holt＇s method is used to predict the fault process. In the end, the system＇s reliability is predicted in real time by use of the Monte Carlo strategy. The proposed approach can effectively predict the impending failure of a dynamic system, which is verified by computer simulations based on a three-vessel water tank system.

关键词： reliability failure prognostics dynamic systems fault prediction particle filtering interacting multiple model exponential smoothing,predictive maintenance

RECOGNITION AND CLASSIFICATION FOR O(n)-EQUIVARIANT BIFURCATIONS WITH O(n)-CODIMENSION LESS THAN 5

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Chinese Annals of Mathematics,Series B 1998年第4期19卷 391-400页

作者： WANG XIAOFENG (department of Applied Mathematics, tsinghua university, beijing 100084, china.)TANG YUN (department of Applied Mathematics, tsinghua university, beijing 100084, china.)WANG DUO (School of Mathematical Science, Peking universityl Beliing 10 Tsing Hua Univ Dept Appl Math Beijing 100084 Peoples R China Peking Univ Sch Math Sci Beijing 100080 Peoples R China

Bifurcation problems equivariant under the standard action of the orthogonal group O(n) up to O(n)-codimension 4 are classified into 19 classes. For each class the normal form and one universal unfolding are calculate... 详细信息

关键词： O(n)-equivariant bifurcation Normal form Universal unfolding Recognition problem

Building a next generation Internet with source address validation architecture

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Science in china(Series F) 2008年第11期51卷 1681-1691页

作者： WU JianPing1,3,REN Gang1,3 & LI Xing2,3 1 department of Computer Science,tsinghua university,beijing 100084,china 2 department of Electronic Engineering,tsinghua university,beijing 100084,china 3 tsinghua National Laboratory for Information Science and Technology(TNList) ,beijing 100084,china department of Computer Science Tsinghua University Beijing 100084 China department of Electronic Engineering Tsinghua University Beijing 100084 China tsinghua National Laboratory for Information Science and Technology (TNList) Beijing 100084 China

The IP packet forwarding of current Internet is mainly destination based. In the forwarding process, the source IP address is not checked in most *** causes serious security, management and accounting problems. Based on the drastically increased IPv6 address space, a ＂source address validation architecture＂（SAVA） is proposed in this paper, which can guarantee that every packet received and forwarded holds an authenticated source IP address. The design goals of the architecture are lightweight, loose coupling, ＂multi-fence support＂ and incremental deployment. This paper discusses the design and implementation for the architecture, including inter-AS, intra-AS and local subnet. The performance and scalability of SAVA are described. This architecture is deployed into the CNGI-CERNET2 infrastructure a large-scale native IPv6 backbone network of the china Next Generation Internet project. We believe that the SAVA will help the transition to a new, more secure and dependable Internet.

关键词： IP source address validation network architecture network security

Particle tunnels across the horizon of Garfinkle-Horowitz-Strominger dilaton black hole

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Science china(physics,Mechanics & Astronomy) 2007年第5期50卷 601-610页

作者： FANG HengZhong1 & ZHAO Zheng2 1 department of physics, china university of Petroleum, Dongying 257061, china 2 department of physics, beijing Normal university, beijing 100875, china department of physics China University of Petroleum Dongying 257061 China department of physics Beijing Normal University Beijing 100875 China

We promote the work of Parikh and Wilczek on the black hole radiation to the emission of massive and charged particles from Garfinkle-Horowitz-Strominger black hole. The energy and charge of the space-time are conservational during the course of the evaporation. The calculation shows that the emission spectrum is not precisely thermal, while has a correction, and the conclusion supports the view- point of information conservation.

关键词： Hawking radiation, black body spectrum, barrier, information loss, entropy of black hole, Komar energy

Fractal Characteristics of Round Jets in Steady Crossflow

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Communications in Nonlinear Science and Numerical Simulation 1998年第3期3卷 183-186页

作者： Yuhang LI Chaoquan CHEN and Chunbo JIANG(Hydraulic department, tsinghua university, beijing 100084, china) Hydraulic department Tsinghua University Beijing 100084 China

The fractal dimensions of turbulent round jets in steady crossflow has beenanalyzed by using planar laser-induced fluorescence (PLIF) method. The relation betweenthe fractal dimension and the momentum ratio, the variation of the fractal dimension withthe elevation of jet and the dilution have been investigated. The comparison of the fractalcharacteristics between the multiple jets and the signal jet has been carried out.

关键词： steady crossflow turbulent jet measurement of fractal dimension