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A variational method for contour tracking via covariance matching

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science china(Information sciences) 2012年第11期55卷 2635-2645页

作者： WU YuWei,MA Bo & LI Pei beijing Laboratory of Intelligent Information technology,school of computer science,beijing Institute of technology,beijing 100081,china 1. beijing Laboratory of Intelligent Information technology School of Computer Science Beijing Institute of Technology Beijing 100081 China

This paper presents a novel formulation for contour *** model the second-order statistics of image regions and perform covariance matching under the variational level set ***,covariance matrix is adopted as a visual object representation for partial differential equation(PDE) based contour ***-Euclidean calculus is used as a covariance distance metric instead of Euclidean distance which is unsuitable for measuring the similarities between covariance matrices,because the matrices typically lie on a non-Euclidean manifold.A novel image energy functional is formulated by minimizing the distance metric between the candidate object region and a given template,and maximizing the one between the background region and the *** corresponding gradient flow is then derived according to a variational approach,enabling partial differential equations(PDEs) based contour *** on several challenging sequences prove the validity of the proposed method.

关键词： contour tracking covariance region descriptor level set Log-Euclidean Riemannian metric

Human knowledge acquisition from 3D interaction in virtual environments

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science china(Information sciences) 2012年第7期55卷 1528-1540页

作者： CHENG Cheng,JIANG Ru & DONG XueMei beijing Laboratory of Intelligent Information technology,school of computer science,beijing Institute of technology,beijing 100081,china 1. beijing Laboratory of Intelligent Information technology School of Computer Science Beijing Institute of Technology Beijing 100081 China

Recently,virtual environment (VE) based design and planning,which is a kind of interaction intensive computing,has shown great *** users of such systems are specialists or technicians and their 3D interactions with the system embed a great deal of knowledge and ***,how to integrate human knowledge and skills into VE is a great challenge to researchers in the human computer interaction *** paper proposes a method for acquiring user knowledge from *** main ideas and work include,abstracting the interactive process and formalizing the interactive semantics,as well as providing a semantic model of an interactive information repository,from which user interactive processes can be retrieved and all kinds of application logics can be established.A virtual assembly planning system is introduced as an example of a practical application of this *** show that the related models can well capture user knowledge and retrieve the interaction process.

关键词： human computer interaction interactive semantics virtual environment temporal logic virtual manufacturing virtual assembly

Technical framework for Internetware: An architecture centric approach

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science in china(Series F) 2008年第6期51卷 610-622页

作者： YANG FuQing1,2, Lü Jian3,4 & MEI Hong1,2 1 Key Laboratory of High Confidence Software Technologies (Peking university), Ministry of Education, beijing 100871, china 2.school of Electronics engineering and computer science, Peking university, beijing 100871, china 3 State Key Laboratory for Novel Software technology, Nanjing 210093, china 4 Department of computer science and technology, Nanjing university, Nanjing 210093, china 1. Key Laboratory of High Confidence Software Technologies (Peking university) Ministry of Education Beijing 100871 China 2. school of Electronics engineering and computer science Peking University Beijing 100871 China 3. State Key Laboratory for Novel Software technology Nanjing 210093 China 4. Department of computer science and technology Nanjing University Nanjing 210093 China

Being a new software paradigm evolved by the Internet, Internetware brings many challenges to the traditional software methods and techniques. Sponsored by the national basic research program （973）, researchers in china have developed an architecture centric technical framework for the definition, incarnation and engineering of Internetware. First of all, a software model for Internetware is defined for what to be, including that Internetware entities should be packaged as components, behaving as agents, interoperating as services, collaborating in a structured and on demand manner, etc. Secondly, a middleware for Internetware is designed and implemented for how to be, including that Internetware entities are incarnated by runtime containers, structured collaborations are enabled by runtime software architecture, Internetware can be managed in a reflective and autonomic manner, etc. Thirdly, an engineering methodology for Internetware is proposed for how to do, including the way to develop Internetware entities and their collaborations by transforming and refining a set of software architectures which cover all the phases of software lifecycle, the way to identify and organize the disordered software assets by domain modeling, etc.

关键词： Internetware component software architecture agent middleware

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A user-space file system for on-demand legacy desktop software

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science china(Information sciences) 2011年第6期54卷 1142-1150页

作者： ZHANG YouHui 1,2 , SU GeLin 1,2 & ZHENG WeiMin 1,2 1 Department of computer science and technology, Tsinghua university, beijing 100084, china 2 Tsinghua National Laboratory for Information science and technology, Tsinghua university, beijing 100084, china 1. Department of computer science and technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China

Some user-level virtualization technologies have been used to convert legacy software (like the existing Windows desktop applications) into the on-demand software without any modification. To give the client a friendly and compatible method to access on-demand legacy software across the Internet, this paper presents a clientend file system for this usage case. It is a Windows user-space file system based on the cloud storage (where the on-demand software is stored), which converts the local file system accesses into remote visits. Quite a few optimizations are adopted and adjusted to suit the file-access-pattern of on-demand software, including the local cache, metadata/data/software prefetch and content-addressable storage (CAS), to decrease the number of remote visits and/or to overlap IO (input/output) operations with software execution. Detailed access-pattern analyses are also presented. This file system has been implemented and tests show that it is practical for much daily-used software-a local cache of limited size can provide up to 80% hit ratio and the corresponding overhead of running-time is about 37%. Owing to this method, on any compatible and networked computer, a user can use his/her personalized software conveniently although it does not exist on the local host.

关键词： on-demand software software as a service user-space file system cloud storage

An algorithm to compute maximal contractions for Horn clauses

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science china(Information sciences) 2011年第2期54卷 244-257页

作者： LUO Jie & LI Wei State Key Laboratory of Software Development Environment, school of computer science and technology, Beihang university, beijing 100191, china 1. State Key Laboratory of Software Development Environment School of Computer Science and Technology Beihang University Beijing 100191 China

In the theory of belief revision, the computation of all maximal subsets (maximal contractions) of a formula set with respect to a set of facts is one of the key problems. In this paper, we try to solve this problem by studying the algorithm to compute all maximal contractions for Horn clauses. First, we point out and prove the conversion relationship between minimal inconsistent subsets of union of the formula set and the set of facts and maximal contractions of the formula set with respect to the set of facts. Second, we prove a necessary condition of a set of Horn clauses to be minimal inconsistent. Then, based on these two conclusions, we propose an interactive algorithm to enumerate all minimal inconsistent subsets of a given set of Horn clauses and a second algorithm to compute maximal contractions from these minimal inconsistent subsets. Finally, we proposed an interactive algorithm to compute maximal contractions for Horn clauses by composing the above two algorithms.

关键词： maximal contraction minimal inconsistent set minimal subtraction Horn clause

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

Fuzzy dynamic characteristic model based attitude control of hypersonic vehicle in gliding phase

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science china(Information sciences) 2011年第3期54卷 448-459页

作者： LUO Xiong 1,2 & LI Jiang 1 1 Department of computer science and technology, Key Laboratory of Advanced Control of Iron and Steel Process (Ministry of Education), university of science and technology beijing, beijing 100083, china 2 National Laboratory of Space Intelligent Control, beijing 100190, china 1. Department of computer science and technology Key Laboratory of Advanced Control of Iron and Steel Process (Ministry of Education) University of Science and Technology Beijing Beijing 100083 China2. National Laboratory of Space Intelligent Control Beijing 100190 China

The intelligent autonomous control of hypersonic vehicles has aroused great interest from the field of spacecraft. To solve the problem of longitudinal attitude control of hypersonic vehicle in gliding phase, a new intelligent controller is proposed in this paper. This new controller is based on the fuzzy dynamic characteristic modeling method. The fuzzy logic is introduced into the characteristic modeling by dividing the whole restriction range into several subspaces. Simulations show that this modification greatly improves the performance of the original method. With the same whole restriction range the fuzzy dynamic characteristic modeling decreases the time of convergence, and at the same time makes the attitude angle tracing more precise and robust. Since the sub-model is a characteristic model that has stronger adaptiveness than a fixed local model, the number of fuzzy rules is greatly reduced. Our model sharply reduces the complexity in constructing a fuzzy dynamic model. Finally, simulation results are given to show the effectiveness of the proposed approach in dealing with the attitude control problem of hypersonic vehicle in gliding phase.

关键词： hypersonic vehicle gliding attitude control fuzzy dynamic characteristic modeling

Augmented reality registration algorithm based on nature feature recognition

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science china(Information sciences) 2010年第8期53卷 1555-1565页

作者： CHEN Jing 1 , WANG YongTian 1,2 , GUO JunWei 1 , LIU Wei 1 , LIN JingDun 1 , XUE Kang 1 , LIU Yue 1 & DING GangYi 31 school of Optoelectronics, beijing Institute of technology, beijing 100081, china 2.school of computer science and technology, beijing Institute of technology, beijing 100081, china 3 school of Software, beijing Institute of technology, beijing 100081, china 1. school of Optoelectronics Beijing Institute of Technology Beijing 100081 China2. School of Computer Science and Technology Beijing Institute of Technology Beijing 100081 China3. School of Software Beijing Institute of Technology Beijing 100081 China

This paper presents an improved key frame based augmented reality registration algorithm for real-time motion tracking in outdoor environment. In such applications, wide-baseline feature matching is a critical problem. In this paper, we apply randomized tree method to match key points extracted from the input image to those key frames as a classification problem. Extended Kalman filter is also utilized for jitter correction. A video see-through mobile augmented reality system is built for the on-site digital reconstruction of Yuanmingyuan Garden. Experimental results demonstrate that this algorithm is real-time, robust and effective for outdoor tracking.

关键词： outdoor augmented reality camera tracking randomized tree

(2,n)secret sharing scheme for gray and color images based on Boolean operation

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science china(Information sciences) 2012年第5期55卷 1151-1161页

作者： DONG Lin 1,WANG DaoShun 1,LI ShunDong 2 & DAI YiQi 1 1 Department of computer science and technology,Tsinghua university,beijing 100084,china 2.school of computer science,Shaanxi Normal university,Xi'an 710062,china 1. Department of computer science and technology Tsinghua University Beijing 100084 China2. School of Computer Science Shaanxi Normal University Xi’an 710062 China

Traditional secret sharing (SS) schemes can reconstruct the secret precisely,but have high com-putation *** secret sharing (VSS) schemes use human visual system to reconstruct the secret without cryptographic computation,but have pixel expansion and loss of *** et *** a (2,n)-SS scheme for binary images based on Boolean operation,which has low computation complexity,no pixel expansion and the contrast is 1/*** this paper,we first construct an r runs (2,n)-SS scheme to improve the contrast of Wang et al.'s binary (2,n)-SS *** we present two approaches to construct r runs (2,n)-SS schemes for grayscale image and color *** two approaches are both based on Boolean operation,while one approach uses halftone technology and the other uses bit level *** proposed schemes have low computation complexity and almost ideal contrast.

关键词： secret sharing scheme Boolean operation halftone contrast