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SAR images classification method based on Dempster-Shafer theory and kernel estimate

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Journal of Systems Engineering and Electronics 2007年第2期18卷 210-216页

作者： he Chu xia Guisong Sun Hong Electronic Information School Wuhan Univ. Wuhan 430079 P.R. China

To study the scene classification in the Synthetic Aperture Radar （SAR） image, a novel method based on kernel estimate, with the Maxkov context and Dempster-Shafer evidence theory is proposed. Initially, a nonpaxametric Probability Density Function （PDF） estimate method is introduced, to describe the scene of SAR images. And then under the Maxkov context, both the determinate PDF and the kernel estimate method axe adopted respectively, to form a primary classification. Next, the primary classification results are fused using the evidence theory in an unsupervised way to get the scene classification. Finally, a regularization step is used, in which an iterated maximum selecting approach is introduced to control the fragments and modify the errors of the classification. Use of the kernel estimate and evidence theory can describe the complicated scenes with little prior knowledge and eliminate the ambiguities of the primary classification results. Experimental results on real SAR images illustrate a rather impressive performance.

关键词： Image classification Synthetic aperture Radar (SAR) Dempster-Shafer theory Kernel estimate.

A Train-Bridge Dynamic Interaction Analysis Method and Its Experimental Validation

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Engineering 2016年第4期2卷 528-536页

作者： Nan Zhang Yuan Tian he xia School of Civil Engineering BeijingJiaotong University Beijing 100044 China

The train-bridge dynamic interaction problem began with the development of railway technology, and requires an evaluation method for bridge design in order to ensure the safety and stability of the bridge and the running train. This problem is studied using theoretical analysis, numerical simulation, and experimental study. In the train-bridge dynamic interaction system proposed in this paper, the train vehicle model is established by the rigid-body dynamics method, the bridge model is established by the finite element method, and the wheel/rail vertical and lateral interaction are simulated by the corresponding assumption and the Kalker linear creep theory, respectively. Track irregularity, structure deformation, wind load, collision load, structural damage, foundation scouring, and earthquake action are regarded as the excitation for the system. The train-bridge dynamic interaction system is solved by inter-history iteration. A case study of the dynamic response of a CRH380BL high-speed train running through a standard-design bridge in China is discussed. The dynamic responses of the vehicle and of the bridge subsystems are obtained for speeds ranging from 200 km-b-1 to 400 km.h-1, and the vibration mechanism are analyzed.

关键词： Train-bridge dynamic interaction Wheel/rail relationship Inter-history iteration Field measurement Experimental validation

An Isometric Embedding of Mbius Band with Positive Gaussian Curvature

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Acta Mathematica Sinica,English Series 2004年第6期20卷 961-964页

作者： Hui xia he Zi Zhou TANG Department of Mathematical Sciences Tsinghua University College of Mathematical Sciences Beijing Normal University

The main purpose of this paper is to show that there is an isometric embedding from M?bius band to ?4 with positive Gaussian curvature.

关键词： Veronese map Gaussian curvature Isometric immersion

Evaluation of vehicle-track-bridge interacted system for the continuous CRTS-II non-ballast track slab

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Science China(Technological Sciences) 2014年第10期57卷 1895-1901页

作者： ZHANG Nan ZHOU Shuang xia he SUN Lu School of Civil Engineering Beijing Jiaotong University School of Transportation Southeast University

Considering the CRTS-II track slab,which is commonly used in the Chinese high-speed railway system,a vehicle-track-bridge dynamic analysis method is proposed in which the vehicle subsystem equations are established by the rigid body dynamics method,the track subsystem and the bridge subsystem equations are established by the FEM,the wheel-rail contact relation is defined by the corresponding assumption in vertical direction and the Kalker linear creep theory in lateral *** in-span spring element is derived to model the track-bridge interaction;the equal-band-width storage is adopted to fit the track structure with multilayer uniform section beam;and the dynamic equilibrium equations are solved by the inter-history iteration *** a case study,the response of a CRH2 high-speed train transverses a simply-supported bridge with successive 31.5m double bound pre-stress beams is *** result shows that using the vehicle-track-bridge interaction model instead of the vehicle-bridge interaction model helps predict the rotation angle at beam ends and choose an economic beam vertical stiffness.

关键词： vehicle-track-bridge interacted system CRTS-II track slab in-span spring element equal-band-width storage

Hom-Gel'fand–Dorfman Super-bialgebras and Hom-Lie Conformal Superalgebras

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Acta Mathematica Sinica,English Series 2017年第1期33卷 96-116页

作者： La Mei YUAN Sheng CheN Cai xia he Academy of Fundamental and Interdisciplinary Sciences Harbin Institute of Technology Harbin 150080 P. R. China Department of Mathematics Harbin Institute of Technology Harbin 150001 P. R. China

The aim of this paper is to introduce and study Hom-Gel＇fand-Dorfman super-bialgebras and Hom-Lie conformal superalgebras. In this paper, we provide different ways for constructing Hom- Gel＇fand-Dorfman super-bialgebras. Also, we obtain some infinite-dimensional Hom-Lie superalgebras from affinization of Hom-Gel＇fand-Dorfman super-bialgebras. Finally, we give a general construction of Hom-Lie conformal superalgebras from Hom-Lie superalgebras and establish the equivalence between quadratic Hom-Lie conformal superalgebras and Hom-Gel＇fand-Dorfman super-bialgebras.

关键词： Lie conformal superalgebra Horn-Lie superalgebra Hom-Lie conformal superalgebra,Hom-Gel'fand-Dorfman super-bialgebra

Lagrangian Bonnet Problems in Complex Space Forms

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Acta Mathematica Sinica,English Series 2019年第8期35卷 1357-1366页

作者： Hui xia he Hui MA Er xiao WANG School of Mathematics and Systems Science Beihang University LIMB of the Ministry of Education Beijing 100083 P. R. China Department of Mathematical Sciences Tsinghua University Beijing 100084 P. R. China Department of Mathematics Hong Kong Univ of Sci. and Tech. Clear Water Bay Kowloon Hong Kong P. R. China

In this note we consider Lagrangian Bonnet problem for Lagrangian surfaces in complex space forms. We first give a Bonnet type theorem for conformal Lagrangian surfaces in complex space forms, then we show that any compact Lagrangian surface in the complex space form admits at most one other global isometric Lagrangian surface with the same mean curvature form, unless the Maslov form is conformal. These two Lagrangian surfaces are then called Lagrangian Bonnet pairs. We also studied Lagrangian Bonnet surfaces in complex space forms, and obtain some characterizations of such surfaces.

关键词： Lagrangian submanifolds complex space forms. Bonnet pairs

Experimental investigation of railway train-induced vibrations of surrounding ground and a nearby multi-story building

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Earthquake Engineering and Engineering Vibration 2009年第1期8卷 137-148页

作者： xia he Chen Jianguo Wei Pengbo xia Chaoyi G. De Roeck G. Degrande School of Civil Engineering Beijing Jiaotong University Beijing 100044 China Department of Civil Engineering Catholic University of Leuven B-3001 Heverlee Belgium

In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing- Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration （FTA） criteria for acceptable ground-borne vibrations expressed in terms ofrms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.

关键词： train building ground environmental vibration field experiment

Wearable gas/strain sensors based on reduced graphene oxide/linen fabrics

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Frontiers of Materials Science 2019年第3期13卷 305-313页

作者： xia he Qingchun LIU Jiajun WANG Huiling CheN School of Art and Design Zhejiang Sci-Tech UniversityHangzhou 310018China School of Art Design Zhejiang A&F UniversityHangzhou 311300China

Multifunctional wearable e-textiles have been a focus of much attention due to their great potential for healthcare,sportswear,fitness,space,and military *** them,electroconductive textile yarn shows great promise for use as the next-generation flexible sensors without compromising properties and comfort of usual ***,a myriad of efforts have been devoted to improving performance and functionality of wearable ***,the current manufacturing process of metal-based electroconductive textile yarn is expensive,unscalable,and environmentally *** this work,we report the preparation of multifunctional reduced graphene oxide/linen(RGO/LN)fabrics through the reduction and the followed suction *** RGO/LN fabric could serve as the methane gas sensor,which exhibited high sensitivity,remarkable reliability and ***,the RGO/LN fabric sensor exhibited good moisture permeability and air *** present work reveals that RGO/LN fabric has great potential as wearable smart devices in personal healthcare applications.

关键词： wearable sensor reduced graphene oxide linen fabric methane

Wind tunnel test on aerodynamic effect of wind barriers on train-bridge system

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Science China(Technological Sciences) 2015年第2期58卷 219-225页

作者： GUO Wei Wei WANG Yu Jing xia he LU Shan School of Civil Engineering Beijing Jiaotong University Beijing Key Laboratory of Structural Wind Engineering and Urban Wind Environment

To investigate the aerodynamic effect of wind barriers on a high-speed train-bridge system,a sectional model test was conducted in a closed-circuit-type wind *** different cases,including with and without barriers,with different barrier heights and porosity rates,and with different train arrangements on the bridge were taken into consideration;in addition,the aerodynamic coefficients of the train-bridge system were *** is found that the side force and rolling moment coefficients of the vehicle are efficiently reduced by a single-side wind barrier,but for the bridge deck these values are *** height and porosity rate of the barrier are two important factors that influence the windbreak *** arrangement on the bridge will considerably influence the aerodynamic properties of the train-bridge *** side force and rolling moment coefficients of the vehicle at the windward side are larger than at the leeward side.

关键词： wind barrier train-bridge system wind tunnel aerodynamic coefficient windbreak effect