检索结果-南通市图书馆

An approach to detecting abnormal vehicle events in complex factors over highway surveillance video

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第S2期51卷 199-208页

作者： SHENG Hao1,XIONG Zhang1,WENG JingNong2 & WEI Qi1 1 college of Computer,beihang university,beijing 100191,china 2.college of software,beihang university,beijing 100191,china college of Computer Beihang University Beijing 100191 China college of software Beihang University Beijing 100191 China

The detection of abnormal vehicle events is a research hotspot in the analysis of highway surveillance *** of the complex factors,which include different conditions of weather,illumination,noise and so on,vehicle's feature extraction and abnormity detection become *** paper proposes a Fast Constrained Delaunay Triangulation(FCDT) algorithm to replace complicated segmentation algorithms for multi-feature *** on the video frames segmented by FCDT,an improved algorithm is presented to estimate background *** the estimation,a multi-feature eigenvector is generated by Principal Component Analysis(PCA) in accordance with the static and motional features extracted through locating and tracking each *** abnormity detection,adaptive detection modeling of vehicle events(ADMVE) is presented,for which a semi-supervised Mixture of Gaussian Hidden Markov Model(MGHMM) is trained with the multi-feature eigenvectors from each video *** normal model is developed by supervised mode with manual labeling,and becomes more accurate via iterated *** abnormal models are trained through the adapted Bayesian learning with unsupervised *** paper also presents experiments using real video sequence to verify the proposed method.

关键词： background estimation abnormity detection adaptive detection modeling a semi-supervised MGHMM

Probabilistic composition of cone-based cardinal direction relations

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第S1期51卷 81-90页

作者： LIU Yu1,TIAN Yuan1 & WENG JingNong2 1 Institute of Remote Sensing and Geographical Information Systems,Peking university,beijing 100871,china 2.college of software,beihang university,beijing 100083,china Peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China beihang Univ Coll Software Beijing 100083 Peoples R China

Composition tables play a significant role in qualitative spatial reasoning (QSR). At present,a couple of composition tables focusing on various spatial relations have been developed in a qualitative approach. However,the spatial reasoning proc-esses are usually not purely qualitative in everyday life,where probability is one important issue that should be considered. In this paper,the probabilistic compo-sitions of cone-based cardinal direction relations (CDR) are discussed and esti-mated by making some assumptions. Consequently,the form of composition result turns to be {(R1,P1),(R2,P2),…,(Rn,Pn)},where Pi is the probability associated with relation Ri. Employing the area integral method,the probabilities in each composi-tion case can be computed with the assumption that the target object is uniformly distributed in the corresponding cone regions.

关键词： spatial reasoning cardinal direction relations probabilistic composition

3D building modeling,organization and application in digital city system

在线全文

学校读者我要写书评

暂无评论

中国科学：技术科学英文版 2010年第S1期53卷 134-142页

作者： YANG Xue 1,WENG JingNong 1,2,XIA YuBin 2,WU Lun 3 & SUI ZhengWei 3 1 college of software,beihang university,beijing 100191,china 2.college of Computer,beihang university,beijing 100191,china 3 Institute of Remote Sensing and GIS,Peking university,beijing 100871,china beihang Univ Coll Software Beijing 100191 Peoples R China beihang Univ Coll Comp Beijing 100191 Peoples R China Peking Univ Inst Remote Sensing & GIS Beijing 100871 Peoples R China

The real world is a three-dimensional(3D)space requiring that 3D geospatial information applications be developed in alignment with the observer’s visual and perceptive ***,3D building model data are required in a wide range of areas such as urban planning,environmental protection,real estate management and emergency *** the same time,the development of Web service[LU1]technologies allows the possibility of the widely distributed 3D geospatial data on the web.3D city building model with its related information is an important part in the construction of a digital city system,and has become a staple resource on the web *** view of the hierarchical representation of a 3D building model,an abstract of a 3D building model based on structure details is studied,and a novel representation approach named 3D transparent building hierarchical model is presented in this *** approach fully uses both the existing 3D modeling technologies and CAD constructing mapping *** the spatial relationship description,structural components inside a building can be represented and integrated as hierarchical models in a unified 3D *** addition,based on the characteristics of the 3D building model data,a service-oriented architecture and Web service technologies for 3D city building models are *** aim of the approach is that 3D city building models can be used as a kind of data resource service on the web,and can also exist independently in various different web applications.

关键词： 3D modeling 3D transparent building hierarchical models china Star web services

General solution to diagonal model matching control of multiple-output-delay systems and its applications in adaptive scheme

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2009年第1期19卷 79-90页

作者： Yingmin Jia The Seventh Research Division,beihang university,beijing 100083,china [a]The Seventh Research Division Beihang University Beijing 100083 China

This paper mainly studies the model matching problem of multiple-output-delay systems in which the reference model is assigned to a diagonal transfer function matrix.A new model matching controller structure is first developed,and then,it is shown that the controller is feasible if and only if the sets of Diophantine equations have common *** obtained controller allows a parametric representation,which shows that an adaptive scheme can be used to tolerate parameter variations in the *** resulting adaptive law can guarantee the global stability of the closed-loop systems and the convergence of the output error.

关键词： Model matching control Decoupling Adaptation Time delays Multivariable systems Diophantine equations

Stabilization control of a bumblebee in hovering and forward flight

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第1期25卷 13-21页

作者： Yan Xiong Mao Sun Institute of Fluid Mechanics, beihang university,beijing 100083, china Institute of Fluid Mechanics Beihang University Beijing 100083 China

Our previous study shows that the hovering and forward flight of a bumblebee do not have inherent stability （passive stability）. But the bumblebees are observed to fly stably. Stabilization control must have been applied. In this study, we investigate the longitudinal stabilization control of the bumblebee. The method of computational fluid dynamics is used to compute the control derivatives and the techniques of eigenvalue and eigenvector analysis and modal decomposition are used for solving the equations of motion. Controllability analysis shows that at all flight speeds considered, although inherently unstable, the flight is controllable. By feedbacking the state variables, i.e. vertical and horizontal velocities, pitching rate and pitch angle （which can be measured by the sensory system of the insect）, to produce changes in stroke angle and angle of attack of the wings, the flight can be stabilized, explaining why the bumblebees can fly stably even if they are passively unstable.

关键词： Insect - Hovering and forward flight - Stabilization control Navier-Stokes simulation Modal analysis

Filterless Photosensors with Intrinsic Color Perception and Flexibility

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2024年第5期40卷 894-900页

作者： ZHOU Hongtao XU beihang ZHENG Xinjia GONG Jinchao ZHANG Kaitong HE Yonglin Key Laboratory of Advanced Light Conversion Materials and Biophotonics School of Chemistry and Life ResourcesRenmin University of ChinaBeijing100872P.R.China School of Mathematics Renmin University of ChinaBeijing100872P.R.China

Sensing materials possessing intrinsic color perception are indispensable prerequisites for the development of filterless photosensors,which could eliminate the need for complex device designs and avoid color distortion in *** materials are constrained by complex processing methods and limited ***,a color-photosensitive array based on ionic liquid with selective photothermal conversion(ILSPC)has been developed for intrinsic color *** on the selective absorption,photothermal conversion,and thermosensitivity of ILSPC,a photo-thermo-electric sensing system has been ***,the versatility of the two algorithms has been validated in color reconstruction and electrical signal *** an exploration,the photosensitive array showcases promising color recognition capabilities,potentially propelling the evolution of flexible photosensors.

关键词： Ionic liquid Filterless Intrinsic color perception Selective photothermal conversion Photosensitive array

A heuristic path-estimating algorithm for large-scale real-time traffic information calculating

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第S1期51卷 165-174页

作者： L WeiFeng1,ZHU TongYu1,WU DongDong2,DAI Hong3 & HUANG Jian1 1 State Key Laboratory for software Development Environment,beihang university,beijing 100083,china 2 beijing Transportation Information Center,beijing 100055,china 3 college of Arts & Science,beijing Union university,beijing 100083,china 1. State Key Laboratory for software Development Environment Beihang University Beijing 100083 China 2. beijing Transportation Information Center Beijing 100055 China 3. college of Arts & Science Beijing Union University Beijing 100083 China

As the original Global Position System (GPS) data in Floating Car Data have the accuracy problem,this paper proposes a heuristic path-estimating algorithm for large-scale real-time traffic information calculating. It uses the heuristic search method,imports the restriction with geometric operation,and makes comparison between the vectors composed of the vehicular GPS points and the special road network model to search the set of vehicular traveling route candidates. Finally,it chooses the most optimal one according to weight. Experimental results indicate that the algorithm has considerable efficiency in accuracy (over 92.7%) and com-putational speed (max 8000 GPS records per second) when handling the GPS tracking data whose sampling rate is larger than 1 min even under complex road network conditions.

关键词： path-estimating floating car data (FCD) road network vector GPS

Vertex solution theorem for the upper and lower bounds on the dynamic response of structures with uncertain-but-bounded parameters

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第3期25卷 367-379页

作者： Zhiping Qiu Xiaojun Wang Institute of Solid Mechanics, beihang university, 100083 beijing, china Institute of Solid Mechanics Beihang University 100083 Beijing China

The aim of this paper is to evaluate the effects of uncertain-but-bounded parameters on the dynamic response of structures. By combining the interval mathematics and the finite element analysis, the mass matrix, damping matrix, stiffness matrix and the external loads are represented as interval matrices and vector. With the help of the optimization theory, we present the vertex solution theorem for determining both the exact upper bounds or maximum values and the exact lower bounds or minimum values of the dynamic response of structures, in which these parameters reach their extreme values on the boundary of the interval mass, damping, stiffness matrices and the interval extemal loads vector. Three examples are used to illustrate the computational aspects of the presented vertex solution theorem.

关键词： Dynamic response Vertex solution theorem ,Uncertain-but-bounded parameters

An eigenelement method and two homogenization conditions

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第3期25卷 345-351页

作者： Yufeng Xing Xingming Wang The Solid Mechanics Research Center, beihang university, 100083 beijing, china The Solid Mechanics Research Center Beihang University 100083 Beijing China

Under inspiration from the structure-preserving property of symplectic difference schemes for Hamiltonian systems, two homogenization conditions for a representative unit cell of the periodical composites are proposed, one condition is the equivalence of strain energy, and the other is the deformation similarity. Based on these two homogenization conditions, an eigenelement method is presented, which is characteristic of structure-preserving property. It follows from the frequency comparisons that the eigenelement method is more accurate than the stiffness average method and the compliance average method.

关键词： Composites Homogenization ,The equivalence of strain energy Deformation similarityEigenelement method