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Simultaneous structure and geometry detail completion based on interactive user sketches

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science china(Information sciences) 2012年第5期55卷 1123-1137页

作者： YANG Shen 1,QI Yue 1 & QIN Hong 2.1 state key {2. of Virtual Reality technology and systems,Beihang University,beijing 100191,china 2.department of computer science,state University of New York at Stony Brook,Stony Brook,New York 11794-4400,USA 1. state key {2. of Virtual Reality technology and systems Beihang University Beijing 100191 China2. Department of Computer Science State University of New York at Stony Brook Stony Brook New York 11794-4400 USA

We articulate a novel approach to geometric model completion via interactive sketches in this ***,the initial incomplete model (with holes) is decomposed into a base model and a high-frequency component,which represents global rough shape and geometric details,*** then repair the base model via smooth hole-filling,and compute the geometry detail image using high frequency *** novel element of our approach is that we allow users to interactively sketch a few structural curves that span across hole regions,with a goal to repair both local geometric details and global *** the help of local parameterization,we convert detailed geometry into gradient-domain images which can propagate along user-specified *** integrating recovered gradient-domain images and base shape,we can generate a complete model that faithfully recovers both global structure and local *** salient contribution of this paper is the unified approach for user interaction,global structure,and geometry details towards high-fidelity model *** demonstrate our new approach using a number of examples that exhibit salient global structure as well as local geometry details.

关键词： model repair geometric modeling interactive sketch 3D graphics

A heuristic algorithm for cube packing with time schedule

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science china(Information sciences) 2010年第1期53卷 18-29页

作者： LI Wei1, HUANG WenQi2. JIANG DongChen1 & LIU XiangLong1 1state key {2. of Software Development Environment, Beihang University, beijing 100191, china 2.chool of computer science and technology, Huazhong University of science and technology, Wuhan 430074, china 1. state key {2. of Software Development Environment Beihang University Beijing 100191 China2. School of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

Packing problem has been proved to be an NP-hard problem. Many algorithms such as simulation annealing algorithm, genetic algorithm and other heuristic algorithms have been proposed to solve twodimensional and three-dimensional packing problem. To solve the cube packing problem with time schedule, this paper first introduces some concepts such as packing level, space distance and average neighbor birth order and then proposes a greedy algorithm. The algorithm tries every feasible corner greedily to calculate the space utilization, packing level, space distance, average neighbor birth order of this placement, and chooses the best placement according to these criteria. Theoretical analysis indicates that the time complexity of this algorithm is O(A2.2.2. 2.5). The experiments show that the average space utilization of non-guillotine cutting test cases is 98.81%, and the average space utilization of guillotine cutting test cases achieves 99.87%. Furthermore, optimal solutions of more than half cases are achieved by this algorithm. The experimental results show that this algorithm can solve the problem of cube packing with time schedule effectively and effciently.

关键词： cube packing problem time schedule packing level space distance average neighbor birth order

Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

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Progress in Natural science:Materials International 2005年第6期15卷 538-544页

作者： CHENG Haobo1*, WANG Yingwei2. FENG Zhijing1 and CHENG Kai3(1. state key {2. of Tribiology, tsinghua University, beijing 100084, china 2. department of Material sciences, Changchun University of science and technology, Changchun 13002., china 3. Faculty of Information and Engineering systems, City Campus, Leeds LS1 3HE, UK) state key {2. of Tribiology Tsinghua University Beijing 100084 China department of Material sciences Changchun University of Science and Technology Changchun 130021 China Faculty of Information and Engineering systems City Campus Leeds LS1 3HE UK

Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel, rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.2. nm root mean square (RMS) after 2. min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM) measurement on the polished surface can also verify the feasibility of the MRF technique.

关键词： magnetorheological finishing surface roughness computer controlled optical surfacing subsurface damage removal function.

Another ID-Based Proxy Signature Scheme and Its Extension

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Wuhan University Journal of Natural sciences 2007年第1期12卷 33-36页

作者： ZHANG Jianhong1,2., ZOU Wei3 1. College of science, North china University of {2., beijing 100041,china 2. Institute of Software of Chinese Academy of sciences /state key laboratory of Information Security, beijing 100080, china 3. Institute of computer science and {2., Peking University, beijing 100871, china College of science North China University of Technology Beijing China state key {2. of Information Security Institute of Software of Chinese Academy of Sciences Beijing China Institute of computer science and {2. Peking University Beijing China

So fur, the security of many proxy signatures has seldom been considered in a formal way and most of them cannot satisfy nonepudiation. In this work, a novel ID-based （Identity-based） proxy signature scheme is proposed by combining the proxy signature with ID-based public cryptography, and they formalize the notion of security for ID-based proxy signature schemes. And show that the security of the proposed scheme is secure. Compured with other proxy signature schemes, it does not need a secure channel. Thus, it is particularly suitable for the unreliable network computation environment. Finally, they extend proposed scheme to a proxy multi-signature which has the following advantages （1） the size of proxy multi- signature is independent of the number of delegating users; （2. the computation cost of proxy multi-signature only need two Weil paring.

关键词： proxy signature multisignature security proof

Geophysical methods for the study of sedimentary cycles

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Petroleum science 2009年第3期6卷 259-265页

作者： Xu Jingling Liu Luofu Wang Guiwen Shen Jinsong Zhang Chunhua School of Resources and Information technology China University of Petroleum Beijing 102249 China state key {2. of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China department of computer {2. and technology China University of Petroleum Beijing 102249 China

We present the wavelet depth-frequency analysis and variable-scale frequency cycle analysis methods to study sedimentary cycles. The spectrum analysis, variable-scale frequency cycle analysis, and wavelet depth-frequency analysis methods are mainly discussed to distinguish sedimentary cycles of different levels. The spectrum analysis method established the relationship between the spectrum characteristics and the thickness and number of sedimentary cycles. Both the variable-scale frequency cycle analysis and the wavelet depth-frequency analysis are based on the wavelet transform. The variable-scale frequency cycle analysis is used to obtain the relationship between the periodic changes of frequency in different scales and sedimentary cycles, and the wavelet depth-frequency analysis is used to obtain the relationship between migration changes of frequency energy clusters and sedimentary cycles. We designed a soft-ware system to process actual logging data from the Changqing Oilfield to analyze the sedimentary cycles, which verified the effectiveness of the three methods, and good results were obtained.

关键词： Sedimentary cycles spectrum analysis wavelet depth-frequency analysis variable-scale frequency cycle analysis

Video motion stitching using trajectory and position similarities

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science china(Information sciences) 2012年第3期55卷 600-614页

作者： CHEN XiaoWu, LI Qing , LI Xin & ZHAO QinPing state key {2. of Virtual Reality technology and systems, School of computer science and Engineering, Beihang University, beijing 100191, china 1. state key {2. of Virtual Reality technology and systems School of Computer Science and Engineering Beihang University Beijing 100191 China

Stitching motions in multiple videos into a single video scene is a challenging task in current video fusion and mosaicing research and film production. In this paper, we present a novel method of video motion stitching based on the similarities of trajectory and position of foreground objects. First, multiple video sequences are registered in a common reference frame, whereby we estimate the static and dynamic backgrounds, with the former responsible for distinguishing the foreground from the background and the static region from the dynamic region, and the latter functioning in mosaicing the warped input video sequences into a panoramic video. Accordingly, the motion similarity is calculated by reference to trajectory and position similarity, whereby the corresponding motion parts are extracted from multiple video sequences. Finally, using the corresponding motion parts, the foregrounds of different videos and dynamic backgrounds are fused into a single video scene through Poisson editing, with the motions involved being stitched together. Our major contributions are a framework of multiple video mosaicing based on motion similarity and a method of calculating motion similarity from the trajectory similarity and the position similarity. Experiments on everyday videos show that the agreement of trajectory and position similarities with the real motion similarity plays a decisive role in determining whether two motions can be stitched. We acquire satisfactory results for motion stitching and video mosaicing.

关键词： video fusion video mosaicing video registration background estimation motion stitching

Parallel Computing of Ocean General Circulation Model

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Wuhan University Journal of Natural sciences 2001年第Z1期6卷 568-573页

作者： Zhang Li lun 1, Song Jun qiang 1, Li Xiao mei 2.1. School of computer science, National University of Defense {2., Changsha 410073, china 2. department of computer, Institute of Command {2., beijing 100081, china School of computer science National University of Defense Technology Changsha 410073 P.R. China

This paper discusses the parallel computing of the third generation Ocean General Circulation Model (OGCM) from the state key {2. of Numerical Modeling for Atmospheric science and Geophysical Fluid Dynamics(LASG),Institute of Atmosphere Physics(IAP). Meanwhile, several optimization strategies for parallel computing of OGCM (POGCM) on Scalable Shared Memory Multiprocessor (S2.P) are presented. Using Message Passing Interface (MPI), we obtain super linear speedup on SGI Origin 2.00 for parallel OGCM(POGCM) after optimization.

关键词： parallel computing OGCM optimization strategy S2.P

Dynamic image stabilization precision test system based on the Hessian matrix

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science china(Information sciences) 2012年第9期55卷 2056-2074页

作者： LI Jing ,WANG JunZheng,WANG ShouKun,MA LiLing & SHEN Wei key laboratory of Complex {2. intelligent Control and Decision,School of Automation,beijing Institute of technology,beijing 100081,china 1. key laboratory of Complex {2. intelligent Control and Decision School of Automation Beijing Institute of Technology Beijing 100081 China

Dynamic image stabilization precision of an optical image-stable device is a key technical ***,a fast dynamic image stabilization precision test system for an optical image-stable device is developed.A large-aperture collimator with a designed cross divisional board is used to simulate the infinity *** image-stable device is installed on the motion simulator with six degrees of freedom which is used to simulate the moving {2. of the *** CCD camera installed behind the eyepiece lens of the image-stable device acquires images rapidly and in real *** local energy maxima center of the cross light spot can be acquired accurately through the proposed algorithm using the Hessian *** addition,to deal with the CCD non-uniformity,an adaptive non-uniformity correction algorithm based on bi-dimensional empirical mode decomposition is *** actual test results for the proposed method show that the test error of dynamic image stabilization is less than 0.7,and the time for the frame image acquisition and processing is less than 10 ms,which demonstrates the effectiveness of the test system.

关键词： image stabilization precision adaptive non-uniformity correction empirical mode decomposition local energy maxima Hessian matrix

A New Transductive Support Vector Machine Approach to Text Categorization

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A New Transductive Support Vector Machine Approach to Text C...