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Radiance-based color calibration for image-based modeling with multiple cameras

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Science china(Information Sciences) 2012年第7期55卷 1509-1519页

作者： zhao Xu 1,2 ,zhou zhong 1,2 & WU Wei 1,2 1 state key laboratory of virtual reality technology and systems,beihang university,beijing 100191,china 2 School of Computer Science and Engineering,beihang university,beijing 100191,china 1. state key laboratory of virtual reality technology and systems Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

Photo-consistency estimation is an important part for many image-based modeling *** paper presents a novel radiance-based color calibration method to reduce the uncertainty of photo-consistency estimation across multiple *** idea behind our method is to convert colors into a uniform radiometric color space in which multiple image data are *** results demonstrate that our method can achieve comparable color calibration effect without adjusting camera parameters and is more robust than other existing ***,we obtain an auto-determined threshold for photo-consistency check,which will lead to a better performance than existing photo-consistency based reconstruction algorithms.

关键词： color calibration photo-consistency estimation multi-camera system image-based modeling

Displacement residual based DDM matching algorithm

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Science china(Information Sciences) 2012年第9期55卷 2090-2101页

作者： ZHANG lin 1,2,zhou zhong 1,2,lIU lin 1,2 & WU Wei 1,2 1 state key laboratory of virtual reality technology and systems,beihang university,beijing 100191,china 2 School of Computer Science and Engineering,beihang university,beijing 100191,china 1. state key laboratory of virtual reality technology and systems Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

High level architecture(HlA) is the prevailing standard for modeling and *** data distribution management(DDM) service of HlA is defined for reducing the delivery of irrelevant *** key in DDM implementation is the region overlap computation,*** matching between update and subscription *** algorithms usually make a compromise between region fidelity and network *** paper takes both the matching algorithm efficiency and bandwidth cost into *** main contributions are:1) illustrating the relationship between region changes and overlap changes,as helps reduce the number of region matching and then improves the total matching efficiency;2) classifying region updates into two types of data expression,snapshot and *** network traffic will be reduced by transmitting only residual data instead of full region representations ***,a region matching algorithm called displacement residual-based DDM matching(DRBM) is proposed in the *** analysis,algorithm implementation and experiment evaluation are *** results show that DRBM provides better matching performance and significant network payload reductions especially when there is a large number of changing regions.

关键词： distributed simulation high level architecture data distribution management region snapshot region residual

Data acquisition and simulation of natural phenomena

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Science china(Information Sciences) 2011年第4期54卷 683-716页

作者： zhao qinping state key laboratory of virtual reality technology and systems,beihang university,beijing 100191,china 1. state key laboratory of virtual reality technology and systems Beihang University Beijing 100191 China

virtual natural phenomena obtained through mathematical-physical modeling and simulation as well as graphics emulation can meet the user’s requirements for sensory experiences to a certain extent but they can hardly have the same accurate physical consistency as real natural *** technology for data acquisition and natural phenomena simulation can enable us to obtain multi-dimensional and multi-modal data directly from real natural phenomena and,based on these real data,to establish digital models highly consistent with real natural phenomena in appearance,physics,behavior or many other aspects,thus making a virtual natural phenomenon a direct mapping of real natural *** approach is conducive to resolving problems concerning the reliability and availability of virtual *** present the technology for acquiring and simulating dada of natural phenomena is still in its initial *** paper gives a review of the related ***,we briefly introduce the basic methods and techniques concerned,then,based on the difference between the basic elements of various natural phenomena,we discuss the current studies on such natural phenomena as light,water,fire,smoke,dynamic terrain,etc.,and finally,in connection with issues in the present research and possible future direction of development,we put forth a number of theoretical and technical problems,hoping they can be resolved in the near future.

关键词： natural phenomena data acquisition simulation data driven reliability

Potential risks of spectrum whitening deconvolution——compared with well-driven deconvolution

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Petroleum Science 2009年第2期6卷 146-152页

作者： li Guofa zhou Hui zhao Chao state key laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China key laboratory of CNPC Geophysical Exploration China University of Petroleum Beijing 102249 China

Deconvolution is widely used to increase the resolution of seismic data. To compare the resolution ability of conventional spectrum whitening deconvolution to thin layers with that of welldriven deconvolution, a complex sedimentary geological model was designed, and then the simulated seismic data were processed respectively by each of the two methods. The amplitude spectrum of seismic data was almost white after spectrum whitening, but the wavelet resolution was low. The amplitude spectrum after well-driven deconvolution deviated from white spectrum, but the wavelet resolution was high. Further analysis showed that if an actual reflectivity series could not well satisfy the hypothesis of white spectrum, spectrum whitening deconvolution had a potential risk of wavelet distortion, which might lead to a pitfall in high resolution seismic data interpretation. On the other hand, the wavelet after well- driven deconvolution had higher resolution both in the time and frequency domains. It is favorable for high resolution seismic interpretation and reservoir prediction.

关键词： Well-driven high resolution spectrum whitening deconvolution seismic wavelet

Progress of lyman-alpha-based beam emission spectroscopy(ly BES)diagnostic on the Hl-2A tokamak

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Plasma Science and technology 2024年第3期26卷 118-125页

作者：周艺轩余羿许敏柯锐聂林徐皓赵光义刘灏袁子豪肖晨雨李继全肖池阶 the Hl-2A Team Southwestern Institute of Physics Chengdu 610041People's Republic of China Sino-French Institute of Nuclear Engineering and technology Sun Yat-sen UniversityZhuhai 519082People's Republic of China state key laboratory of Nuclear Physics and technology School of PhysicsPeking UniversityBeijing 100871People's Republic of China

An edge lyman-alpha-based beam emission spectroscopy(lyBES)diagnostic,using a heating NBI(neutral beam injection)system,is currently under development on the Hl-2A *** 20-channel edge lyBES,which is intended to measure the density fluctuation in plasma edge(from R=1960 mm to R=2026 mm)with an improved spatial resolution of 3.3 mm,is a complement to the existing conventional beam emission spectroscopy(BES)*** this article,we introduce the progress of lyBES diagnostic,including the collection optics,the monochromator,and the detector *** reflectance of the collection mirrors is measured to be~82%at 122 nm,and the aberration geometrical radius of the collection optics is tested to be~150μm in the aimed *** linear dispersion of the lyBES monochromator is designed to be~0.09 nm mm^(-1).The bandwidth of the detector system with the 5×10^(7)V A^(-1)preamplifier gain is measured to be~280 kHz,and the peak-to-peak noise of the detector system is tested to be~16 *** finalized design,components development and testing of the lyBES diagnostic have been completed at present,and an overall performance of the lyBES diagnostic is to be confirmed in the next Hl-2A campaign.

关键词： density fluctuation ly BES BES vacuum ultraviolet

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 laboratory of virtual reality technology and systems, School of Computer Science and Engineering, beihang university, beijing 100191, china 1. state key laboratory 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

loI:Effcient relevance evaluation and filtering for distributed simulation

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Science in china(Series F) 2009年第3期52卷 470-489页

作者： zhou zhong1,2 & WU Wei1,2 1 state key laboratory of virtual reality technology and systems, beihang university, beijing 100191, china 2 School of Computer Science and Engineering, beihang university, beijing 100191, china

In large-scale distributed simulation, thousands of objects keep moving and interacting in a virtual environment, which produces a mass of messages. High level architecture （HlA） is the prevailing standard for modeling and simulation. It specifies two publish-subscribe mechanisms for message filtering： class-based and value-based. However, the two mechanisms can only judge whether a message is relevant to a subscriber or not. lacking of the ability to evaluate the relevance, all relevant messages are delivered with the same priority even when congestion occurs. It significantly limits the scalability and performance of distributed simulation. Aiming to solve the relevance evaluation problem, speed up message filtering, and filter more unnecessary messages, a new relevance evaluation mechanism layer of Interest （lol） was proposed by this paper. lol defines a relevance classifier based on the impact of spatial distance on receiving attributes and attribute values. An adaptive publish-subscribe scheme was built on the basis of loh This scheme can abandon most irrelevant messages directly. Run-time infrastructure （RTI） can also apply congestion control by reducing the frequency of sending or receiving object messages based on each objects＇ loh The experiment results verify the efficiency of message filtering and RTI congestion control.

关键词： distributed simulation high level architecture (HlA) relevance evaluation layer of interest (lol) run-time infrastructure (RTI)

Re-delocalization of localized d-electrons in VO_(2)(R)-VS_(4)hetero-structure enables high performance of rechargeable Mg-ion batteries

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Journal of Magnesium and Alloys 2024年第5期12卷 1830-1840页

作者： lijiao zhou Chao Shen Xueyang Hou zhao fang Ting Jin keyu Xie School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

Rechargeable Mg-ion batteries(MIBs)have attracted much more attentions by virtue of the high capacity from the two electrons ***,the reversible Mg^(2+)diffusion in cathode materials is restricted by the strong interactions between the high-polarized bivalent Mg^(2+)ions and anionic ***,we design and propose a hetero-structural VO_(2)(R)-VS_(4)cathode,in which the re-delocalized d-electrons can effectively shield the polarity of Mg^(2+)***,the electrons should spontaneously transfer from VS_(4)to VO_(2)(R)through the interfaces of hetero-structure due to the lower work function value of VS_(4).Furthermore,the internal electrons transfer lead to the electronic injection into VO_(2)(R)from VS_(4)and the partially broken V-V dimers,indicating the presence of lone pair electrons and charge *** from the shield effect of re-delocalized electrons,and the weakened attraction between cations and O/S anions enables more S^(2-)-S_(2)^(2-)redox groups to participate the electrochemical reactions and compensate the double charge of Mg^(2+)***,VO_(2)(R)-VS_(4)hetero-structure exhibits a high specific capacity of 554 mA h g^(-1)at 50 mA g^(-1).It is believed that the charge re-delocalization of cathode extremely boost the Mg^(2+)ions migration for the high-capacity of MIBs.

关键词： Mg-ion batteries Cathode Charge delocalization Electronic structure Heterostructure

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BH RTI中可靠传输机制的研究

系统仿真学报 2009年第16期21卷 5065-5071页

作者：刘冬梅周忠刘鹂吴威虚拟现实技术与系统国家重点实验室北京航空航天大学北京100083 北京航空航天大学计算机学院北京100083

组播是大规模分布交互仿真中的主要技术之一,仿真中数据的可靠传输要求使可靠组播成为其中的重要问题。在多对多可靠组播RMMS系统研究的基础上,改进TCP单播备份机制,提出了可靠单播恢复丢失的组播备份报文的报文备份机制,消除了TCP备份... 详细信息

组播是大规模分布交互仿真中的主要技术之一,仿真中数据的可靠传输要求使可靠组播成为其中的重要问题。在多对多可靠组播RMMS系统研究的基础上,改进TCP单播备份机制,提出了可靠单播恢复丢失的组播备份报文的报文备份机制,消除了TCP备份带来的瓶颈,提高了可靠组播的性能。介绍了可靠组播集成到BHRTI的设计。实验结果表明,集成可靠组播的BHRTI在时延、吞吐量、多对多传输方面具有良好的性能。

关键词：多对多可靠组播报文备份分布交互仿真 BHRTI