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Bifurcation analysis of polynomial models for longitudinal motion at high angle of attack

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Chinese Journal of Aeronautics 2013年第1期26卷 151-160页

作者： Shi Zhongke fan li School of Automation Northwestern Polytechnical University

To investigate the longitudinal motion stability of aircraft maneuvers conveniently, a new stability analysis approach is presented in this paper. Based on describing longitudinal aerodynamics at high angle-of-attack （a ＆lt; 50 ） motion by polynomials, a union structure of two-order differential equation is suggested. By means of nonlinear theory and method, analytical and global bifurcation analyses of the polynomial differential systems are provided for the study of the nonlinear phenomena of high angle-of-attack flight. Applying the theories of bifurcations, many kinds of bifurcations, such as equilibrium, Hopf, homoclinic （heteroclinic） orbit and double limit cycle bifurcations are discussed and the existence conditions for these bifurcations as well as formulas for calculating bifurcation curves are derived. The bifurcation curves divide the parameter plane into several regions; moreover, the complete bifurcation diagrams and phase portraits in different regions are obtained. Finally, our conclusions are applied to analyzing the stability and bifurcations of a practical example of a high angle-of-attack flight as well as the effects of elevator deflection on the asymptotic stability regions of equilibrium. The model and analytical methods presented in this paper can be used to study the nonlinear flight dynamic of longitudinal stall at high angle of attack.

关键词： Bifurcation High angle of attack Longitudinal motion Polynomials Stability

Holographic superfluid ring with a weak link

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 29-38页

作者： Zhi-Hong li Huai-fan li Department of Physics Shanxi Datong UniversityDatong 037009China Institute of Theoretical Physics Shanxi Datong UniversityDatong 037009China

We explore the generation of topological defects in the course of a dynamical phase transition in a ring with a weak link, i.e., a SSS Josephson junction, from the AdS/CFT correspondence. By setting different parameters of the junction(width, steepness,depth) and the final temperature of the quench, the configurations of the charge density and condensate of the order parameters of the dual field theory are presented. Meanwhile, we observe that in the final equilibrium state, variations in parameters of the junctions only affect the configurations of the charge density and condensate of the order parameters, without altering their values outside the junction. However, variations in the final temperature will directly affect the values of the charge density and condensate of the order parameters outside of the junction. Moreover, in the final equilibrium state, we propose an analytic relation between the gauge-invariant velocity in the two superconducting states in the SSS Josephson junction, which agrees well with the numerical results.

关键词： AdS/CFT correspondence holographic superfluid holographic Josephson junction

Self-converse Large Sets of Pure Hybrid Triple Systems

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Acta Mathematicae Applicatae Sinica 2017年第2期33卷 515-528页

作者： Bing-li fan Institute of Mathematics Beijing Jiaotong University Beijing 100044 China

A hybrid triple system of order v, briefly by HTS （v）, is a pair （X,/3） where X is a v-set and /3 is a collection of cyclic and transitive triples （called blocks） on X such that every ordered pair of X belongs to exactly one block of/3. An HTS （v） is called pure and denoted by PHTS （v） if one element of the block set {（x,y,z）, （z,y, ss）, （z,sc,y）, （y,x,z）, （y,z,x）, （x,z,y）, （x,y,z）, （z,y,x）} is contained in 13 then the others will not be contained in/3. A self-converse large set of disjoint PHTS （v）s, denoted by LPHTS＊（v）, is a collection of 4（v - 2） disjoint PHTS （v）s which contains exactly （v - 2）/2 converse octads of PHTS （v）s. In this paper, some results about the existence for LPHTS＊（v） are obtained.

关键词： large set hybrid triple system pure converse

Analysis on the deformation and fracture behavior of carbon steel by in situ tensile test

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Journal of University of Science and Technology Beijing 2006年第6期13卷 504-507页

作者： fan li Haibo Huang College of Material Science and Engineering Southeast University Nanjing 210096 China

The deformation and fracture behaviors of low-carbon steel, medium-carbon steel, and high-carbon steel were studied on internal microstructure using the scanning electron microscopy in situ tensile test. The microstructure mechanism of their deformation and fracture behavior was analyzed. The results show that the deformation and fracture behavior of low-carbon steel depends on the grain size of ferrite, the deformation and fracture behavior of medium-carbon steel depends on the size of ferrite grain and pearlite lump, and the deformation and fracture behavior of high-carbon steel depends on the size of pearlite lump and the pearlitic interlamellar spacing.

关键词： carbon steel deformation fracture microstructure mechanism in situ tensile test

Primary amine coupling on nanocarbon catalysts: Reaction mechanism and kinetics via fluorescence probe analysis

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Green Energy & Environment 2020年第4期5卷 453-460页

作者： fan li Xueya Dai Wei Qi Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

Non-metallic nanocarbon materials catalyzed coupling reactions of primary amines to produce imine is an efficient,green and sustainable synthetic route,which has a wide application prospect in fine chemicals or pharmaceutical *** the present study,we show firstly the relatively high catalytic activity of graphene oxide in the reaction of oxidative coupling of benzylamine(OCB),which is even comparable with typical metal-based catalysts,indicating the great potential of nanocarbon materials in this reaction *** importantly,a novel twophoton fluorescence probe molecule(N-propyl-4-hydrazinyl-1,8-naphthalimide,NA)with special chemical structure of hydrazine functionality was *** probe NA could selectively react with aldehyde or ketone compounds,leading to the photoluminescence enhancement via inhibition of photo induced electron transfer(PET)*** synthesized NA was applied as probe in carbon catalyzed OCB system to predict the existence of reaction intermediate benzaldehyde(BA),indicating the reaction pathway of oxidation-deamination-condensation in nanocarbon catalyzed OCB *** proposed luminescence-probe strategy for revealing the kinetics and mechanism may also shed light in other reaction systems concerning the intermediates or products of ketones or aldehydes.

关键词： Nanocarbon Benzylamine coupling reaction Fluorescence probe Reaction mechanism

Boosting carrier dynamics of BiVO_(4) photoanode via heterostructuring with ultrathin BiOI nanosheets for enhanced solar water splitting

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Journal of Materials Science & Technology 2021年第20期79卷 21-28页

作者： Can li fan Feng Jie Jian Youxun Xu fan li Hongqiang Wang lichao Jia Key Laboratory of Applied Surface and Colloid Chemistry National Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal University620 West Chang’an StreetXi’anShaanxi710119China State Key Laboratory of Solidification Processing Center for Nano Energy MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical University and Shaanxi Joint Labortary of GrapheneXi’an710072China

Bismuth vanadate(BiVO_(4))has been one of the most promising candidates for solar water splitting while still suffers from poor bulk charge transport that limits its solar to hydrogen conversion *** demonstrate in this work an efficient strategy for boosting bulk charge transport of BiVO_(4) through the facile impregnation of as-prepared BiVO_(4) photoanode in the precursor solution of ultrathin BiOI *** impregnation creates increased oxygen vacancies in the bulk of BiVO_(4) through the reduction of V^(5+)to V^(4+)by I^(-),which greatly improves bulk separation efficiency for BiVO_(4)-BiOI up to 65.9%at 1.23 V_(RHE) from the original 51.9%of pure BiVO_(4).Moreover,the decoration of the BiOI nanosheets on BiVO_(4) photoanode is also beneficial for addressing the carrier dynamics at surface due to the matched energy levels of BiOI nanosheets and BiVO_(4).The introduced plenty of oxygen vacancies in the bulk of BiVO_(4) and the built-in electric field in BiVO_(4)-BiOI synergistically improve the photocurrent density at 1.23 V_(RHE) up to 3.88 mA cm^(-2).We believe that such facile impregnation strategy will pave an alternative way to the development of highly efficient BiVO_(4) photoanode.

关键词： Bismuth vanadate BiOI nanosheets Heterojunction Solution impregnation Oxygen vacancy

Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials

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Chinese Journal of Aeronautics 2007年第2期20卷 157-161页

作者： li fan ZHAO Jian-hui School of Instrument Science and Opto-electronics Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

Preisach model is widely used in modeling of smart materials. Although first order reversal curves （FORCs） have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards：（1） giving the reason a first order reversal curve is introduced; （2） presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution＇s uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to.

关键词： first order reversal curve Preisach model smart material discrete identify

Energy Efficient Social Routing Framework for Mobile Social Sensing Networks

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Tsinghua Science and Technology 2016年第4期21卷 363-373页

作者： fan li Chenfei Tian Ting li Yu Wang School of Computer Science Beijing Institute of TechnologyBeijing 100081China Department of Computer Science the University of North Carolina at Charlotte9201 University City Blvd.CharlotteNC 28223USA

Mobile social sensing network is one kind of emerging networks in which sensing tasks are performed by mobile users and sensing data are shared and collected by leveraging the intermittent inter-contacts among mobile users. Traditional ad hoc routing protocols are inapplicable or perform poorly for data collection or data sharing in such mobile social networks because nodes are seldom fully connected. In recent years, many routing protocols （especially social-based routing） are proposed to improve the delivery ratio in mobile social networks, but most of them do not consider the load of nodes thus may lead to unbalanced energy consumption among nodes. In this paper, we propose a simple Energy Efficient framework for Social-based Routing （EE-SR） in mobile social sensing networks to balance the load of nodes while maintaining the delivery ratio within an acceptable range by limiting the chances of forwarding in traditional social-based routing. Furthermore, we also propose an improved version of EE-SR to dynamically adjust the controlling parameter. Simulation results on real-life mobile traces demonstrate the efficiency of our proposed framework.

关键词： energy efficient social-based routing delay tolerant networks mobile social sensing networks

A framework for equipment systems-of-systems effectiveness evaluation using parallel experiments approach

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Journal of Systems Engineering and Electronics 2015年第2期26卷 292-300页

作者： Zilong Cheng li fan Yulin Zhang College of Aerospace Science and Engineering National University of Defense Technology Academy of Equipment

Equipment systems-of-systems （SOS） effectiveness evaluation can provide important reference for construction and optimization of the equipment SoS. After discussing the basic theory and methods of parallel experiments, we depict an SoS effectiveness analysis and evaluation method using parallel expe- riments theory in detail. A case study is carried out which takes the missile defense system as an example. An artificial system of the missile defense system is constructed with the multi-agent modeling method. Then, single factor, multiple factors and defense position deployment computational experiments are carried out and evaluated with the statistical analysis method. Experiment re- sults show that the altitude of the secondary interception missile is not the key factor which affects SoS effectiveness and putting the defense position ahead will increase defense effectiveness. The case study demonstrates the feasibility of the proposed method.

关键词： agent based modeling parallel experiments computational experiments missile defense system effectiveness evaluation