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Search Results: 1 - 10 of 8712 matches for " Huifeng TAN "
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Fatigue Damage Accumulation of Steel/rubber Composite
Zhenhui TIAN,Huifeng TAN,Xingwen DU,
Zhenhui TIAN
,Huifeng TAN and Xingwen DU Center for Composite Materials,Harbin Institute of Technology,Harbin,China

材料科学技术学报 , 2006,
Abstract: The fatigue damage accumulation of ±20°] laminated steel cord reinforced rubber composite under T-T loading was studied. Results indicate that the increase in the cyclic maximum strain exhibits three-stage tendency in the process of fatigue. The macroscopic fatigue damage initiates from the ends of steel cords in the form of cylindrical crack. Damage propagates along with the increase in crack numbers, the cord/matrix interface debonding and the growth of interply cracks. By using the dynamic creep as parameter, a linear fatigue damage accumulation model was established. This model can be used under dual loading conditions to estimate the residual fatigue life of the specimen.
REVIEW OF METHODS OF WRINKLE STUDIES BASED ON TENSION FIELD THEORY
基于张力场理论的薄膜褶皱研究评述

LI Yunliang,TIAN Zhenhui,TAN Huifeng,
李云良
,田振辉,谭惠丰

力学与实践 , 2008,
Abstract: Tension field theory has been used to study membrane wrinkle for a long time. This theory ignores membrane's bending rigidity, and assumes that wrinkling region is in an uniaxial stress condition. Wrinkles are oriented in the direction of the local major principal stress, and the minor principal stress, in the direction perpendicular to the wrinkle direction, is zero. Many wrinkle models are based on this method. They modify the constitutive relation or deformation gradient, then through numerical method, obtain the stress distribution and the direction of wrinkle. The main disadvantage is that it can not obtain some information of wrinkles such as wavelength, amplitude and number. Wrinkle analysis based on energy method first assumes the deforming pattern, and then obtain the expression of wrinkle's amplitude and wavelength through energy relations. This paper compares different models of membrane wrinkle, and discusses development trends of membrane wrinkle research.
ANALYSIS OF WRINKLES'''' INFLUENCES ON MEMBRANE''''S VIBRATION CHARACTERISTICS
褶皱对薄膜振动特性的影响分析

LI Yunliang,WANG Changguo,TAN Huifeng,
李云良
,王长国,谭惠丰

力学与实践 , 2007,
Abstract: A mechanical model of membrane wrinkle is established in this paper.Relationship between the strains and the stresses in the wrinkled regions is analyzed based on the tension field theory and the stability theory.The NBA-UM (nonlinear buckling analysis-update matrix) method is proposed for the dynamic analysis of membrane wrinkles,and the study on the vibration characteristics of the membrane.The result shows that"excess shrink"phenomena is due to wrinkles,which in turn change the stress distribution in the membrane. Wrinkles greatly influence the vibration characteristics of the membrane,and large amplitude wrinkles will change the natural frequencies and modal forms of the membrane.In conclusion,it is shown that the NBA-UM method can effectively predict the dynamic behaviors of membrane wrinkles.
Non-destructive and Rapid Evaluation of CVD Graphene by Dark Field Optical Microscopy
Xianghua Kong,Hengxing Ji,Richard D. Piner,Huifeng Li,Carl W. Magnuson,Cheng Tan,Ariel Ismach,Harry Chou,Rodney S. Ruoff
Physics , 2013,
Abstract: Non-destructive and rapid evaluation of graphene directly on the growth substrate (Cu foils) by dark field (DF) optical microscopy is demonstrated. Without any additional treatment, graphene on Cu foils with various coverages can be quickly identified by DF imaging immediately after chemical vapor deposition growth with contrast comparable to scanning electron microscopy. The improved contrast of DF imaging compared to bright field optical imaging was found to be due to Rayleigh scattering of light by the copper steps beneath graphene. Indeed, graphene adlayers are readily distinguished, due to the different height of copper steps beneath graphene regions of different thickness.
可展开遮阳罩技术研究进展及其关键科学问题
卫剑征, 林秋红, 林国昌, 谭惠丰
WEI Jianzheng
, LIN Qiuhong, LIN Guochang, TAN Huifeng

- , 2018, DOI: 10.11887/j.cn.201801009
Abstract: 可展开遮阳罩一般是由多层轻质柔性高精度无褶皱薄膜和展开支撑臂及其控制装置组成,在轨后展开支撑臂有序展开多层大面积薄膜实现光控制和热控制性能,能有效改善和防护空间航天器。针对可展开遮阳罩结构,依据一维轴向、二维平面与三维周向的展开方式分类总结国内外可展开遮阳罩技术的研究进展,并对不同遮阳罩结构形状、薄膜材料、层数与展开方式等进行对比分析;梳理出遮阳罩在杂光抑制、折叠与展开变形机理、极端环境下薄膜多场耦合、低温热控、太阳辐射光压力矩及其计算方法等方面的关键科学问题,并给出了中国研究遮阳罩的发展建议。
A deployable sunshield generally consists of layers flexible, wrinkle free multilayer membranes with high precision, deployable booms and its control equipments. The deployable booms can orderly unfold the multilayer membrane after on-orbit to realize its light control and heat control performance, and it can effectively improve the protection on the aerospace systems. The state-of-the-art of domestic and international deployable sunshield structures were classified and summarized according to their deployable methods of one dimensional axial, two-dimensional plane and three-dimensional circumferential way, as well as the comparison to different structural design and the membrane materials. Some key scientific problems for the sunshields were presented in stray light suppression, folding and deployable deformation mechanism, more field coupling on membranes under the extreme environment, low temperature thermal control, and other aspects of solar pressure moment and computing methods. In addition, some recommendations were also given for the sunshield progress and research in China.
Dynamic Properties of Coupled Maps
Chunrui Zhang,Huifeng Zheng
Discrete Dynamics in Nature and Society , 2010, DOI: 10.1155/2010/905102
Abstract: Dynamic properties are investigated in the coupled system of three maps with symmetric nearest neighbor coupling and periodic boundary conditions. The dynamics of the system is controlled by certain coupling parameters. We show that, for some values of the parameters, the system exhibits nontrivial collective behavior, such as multiple bifurcations, and chaos. We give computer simulations to support the theoretical predictions. 1. Introduction Coupled maps is one of the most interesting topics on spatial extended systems. Bifurcation and chaos of coupled maps generated by iterated maps of nonlinear difference equations have attracted considerable attention in both theoretical studies and practical applications [1]. When many identical maps are coupled to a larger system (coupled map lattices or CML), the system can exhibit nontrivial collective behavior, such as stability, multiple bifurcations, and chaos [2–7]. In this paper, we extend this work by considering three-dimensional discrete dynamical systems which arise from three coupled one-dimensional maps with delay. In general, delayed coupled maps of three maps with symmetric nearest neighbor coupling and periodic boundary conditions can be described as where are parameters. Symmetry breaking Hopf bifurcations from steady states to periodic orbits can occur in systems with some symmetry. The coexistence of more chaotic attractors in phase space is phenomenon that has been proven to exist in many fields of science. There are many researches of equivariant bifurcations of ODEs. We refer the readers to the study by Golubitsky et al. in [8]. But, until now, there are fewer papers to discuss equivariant bifurcation problems in maps, which motivates us to write this paper. The goal of this paper is to investigate how parameters affect coupled maps with delay (1.1) by using the symmetric groups theory of Chossat and Golubitsky [9]. Accordingly, the paper is organized as follows. In Sections 2 and 3, we show that the structure of system (1.1) can be represented by a dihedral group . The generalized center subspace is invariant under the action of the symmetry group, and the center manifold reduction can be performed in such a way that the reduced equations commute with the restricted action of the symmetry group. We obtain some important results about the stability and chaos and spontaneous bifurcations of multiple branches of periodic solutions and their spatiotemporal patterns, which describe the oscillatory mode of each oscillator. Finally, some numerical simulations are carried out to support the
Hybrid partial least squares and neural network approach for short-term electrical load forecasting

Shukang YANG,Ming LU,Huifeng XUE,

控制理论与应用 , 2008,
Abstract: Intelligent systems and methods such as the neural network (NN) are usually used in electric power systems for short-term electrical load forecasting. However, a vast amount of electrical load data is often redundant, and linearly or nonlinearly correlated with each other. Highly correlated input data can result in erroneous prediction results given out by an NN model. Besides this, the determination of the topological structure of an NN model has always been a problem for designers. This paper presents a new artificial intelligence hybrid procedure for next day electric load forecasting based on partial least squares (PLS) and NN. PLS is used for the compression of data input space, and helps to determine the structure of the NN model. The hybrid PLS-NN model can be used to predict hourly electric load on weekdays and weekends. The advantage of this methodology is that the hybrid model can provide faster convergence and more precise prediction results in comparison with abductive networks algorithm. Extensive testing on the electrical load data of the Puget power utility in the USA confirms the validity of the proposed approach.
Honeypot Protection Detection Response Recovery Model for Information Security Management Policy
Shubao Xing,Huifeng Xue,Gang Li
Asian Social Science , 2010, DOI: 10.5539/ass.v6n12p50
Abstract: Focusing on characteristics of information management in SME that most information security models assign the detection function to the operational process of enterprise, this paper proposes an information security management model for SMEs ---- the HPDRR (Honeypot Protection Detection Response Recovery) model. By means of empirical studies, this paper summarizes the scheme for executing, maintaining, and improving the information security management policy in SMEs in China.
Design of Seven-core Photonic Crystal Fiber with Flat In-phase Mode for Yb: Fiber Laser Pumping  [PDF]
Ruijuan Dong, Peiguang Yan, Gelin Zhang, Huiquan Li, Shuangchen Ruan, Huifeng Wei, Jie Luo
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B047
Abstract:

We numerically investigate the seven-core photonic crystal fiber (PCF) with the zero dispersion wavelength designed in the range of 1000 - 1080 nm, particularly suitable for the ytterbium-doped fiber laser pumping. Also, the PCFs are well designed for obtaining a flat in-phase mode by carefully adjusting the diameter of inner layer six holes, and the corresponding empirical values of fiber structure are summarized and listed. The variations of inner six holes to the amplitude of in-phase mode are further investigated, and our results show that a better tolerance can be achieved in the fiber structures with lower filling ratio configuration.

Double Cladding Seven-core Photonic Crystal Fiber  [PDF]
Gelin Zhang, Fengfei Xing, Peiguang Yan, Huifeng Wei, Huiquan Li, Shisheng Huang, Rongyong Lin, Kangkang Chen
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B011
Abstract:

A double cladding seven-core PCF was presented for high power supercontinuum generation. The calculated zero dispersion wavelength is located at 912 nm, which has a good agreement with the measurement. The attenuation is measured 6 dB/km at 1590 nm and lower than 14.5 dB/km at 1060 nm, the water-loss peak at 1380 nm is about 134 dB/km; Supercontinuum spanning over more than 1500 nm was generated when the designed seven-core PCF was pumped by a gain-switching Yetterbium-doped fiber laser. These results will be helpful in the future design of multicore photonic crystal fibers (MCPCF) with proper guidance properties for high power supercontinuum generation.

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