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A low power and small area all digital delay-locked loop based on ring oscillator architecture

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science china(Information sciences) 2012年第2期55卷 453-460页

作者： ZHENG JiaPeng1,LI Wei2,LU XueQing2,CHENG YuHua1 & WANG YangYuan1 1Department of Microelectronics,school of electronics engineering and computer science,peking university,beijing 100871,china 2Semiconductor Manufacturing International Corp,Shanghai 201203,china Department of Microelectronics School of Electronics Engineering and Computer Science Peking University Semiconductor Manufacturing International Corp

A 133-500 MHz,5.2 mW @500 MHz,0.021 mm2 all digital delay-locked loop(ADDLL)is *** power and area reduction of the proposed ADDLL are achieved by implementing a high frequency ring oscillator(ROSC)to count the reference clocks such that the one-clock cycle delay chain and the phase detector in a conventional Master block are no longer *** proposed ADDLL has better immunity to PVT(process,voltage,and temperature)than most conventional DLLs,which do not update the control word signals after the locking process,since the control signals for slave delay line are updated in every 256 reference *** in 0.13 um CMOS process,the measured RMS jitter is 10.83 ps at 500 MHz while the RMS jitter of the input signal is 9.97 ps.

关键词： all digital delay locked loop(DLL) phase locked loop(PLL) ring oscillator

Complex conforming Delaunay triangulation

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science china(Information sciences) 2010年第6期53卷 1130-1140页

作者： MENG XianHai 1, LI JiGang 1, YANG Qin 1, CAI Qiang 2 & CHEN QiMing 3 1 NLSDE, school of computer science and engineering, BeiHang university, beijing 100083, china 2 school of computer sciences, beijing Technology and Business university, beijing 100037, china 3 school of Mechanical engineering and Automation, BeiHang university, beijing 100083, china NLSDE School of Computer Science and Engineering BeiHang University

A novel algorithm of conforming Delaunay triangulation for curved geometry is presented in the paper.A progress has been made for the problem puzzled Delaunay refinement where curved constraints cannot be accepted as input *** algorithm is based on a new sufficient condition for the existence of constraints in *** requires computing only the intersection between constraints and Voronoi edges or faces instead of the circum-sphere of curved *** the termination of the algorithm when small input angles exist in constraints, a weighted method is applied to ensure that the algorithm can terminate under any *** two-dimensional and three-dimensional results are also *** is shown that the algorithm has the capability of dealing with both linear and nonlinear constraints in a consistent way, without the need of maintaining triangular meshes on face constraints.

关键词： mesh generation Delaunay triangulation conforming curved constraints tetrahedralization weight

A novel computing model of the maximum clique problem based on circular DNA

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science china(Information sciences) 2010年第7期53卷 1409-1416页

作者： YANG Jing, ZHANG Cheng, XU Jin*, LIU XiangRong & QIANG XiaoLi Institute of Software, school of electronics engineering and computer science, Key Laboratory of High Confidence Software Technologies, Ministry of Education, peking university, beijing 100871, china Institute of Software School of Electronics Engineering and Computer Science Key Laboratory of High Confidence Software Technologies Ministry of Education Peking University

A novel DNA-based model is developed to calculate NP-complete problems, which is made of circular DNA molecules, streptavidin-coated magnetic beads and DNA circligase. To test the feasibility of the model, we apply it to compute a five-node maximum clique problem (MCP). During the computation, DNA molecule structures were transformed between linear DNA and circular DNA by streptavidin-coated magnetic beads and circligase, in order to search for the truth solutions. This greatly reduces the quantity of time and space consumed in calculation, and its time and space complexity both are O(n + m). Compared with the brute force method, using this algorithm searching process at most needs in n + 1 test tubes for an MCP with n vertices, while brute force method requires 2n test tubes. Furthermore, the constructed unenumerable initial solution space greatly improved the processing ability of the DNA computer. This novel model indicates that it may be a powerful DNA-based computer for solving some NP-complete problems.

关键词： DNA-based computing model circular DNA molecules NP-complete problem circligase streptavidin-coated magnetic beads

Improved taboo search algorithm for designing DNA sequences

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Progress in Natural science:Materials International 2008年第5期18卷 623-627页

作者： Kai Zhang a, Jin Xu a,b, Xiutang Geng a, Jianhua Xiao a, Linqiang Pana, a The Key Laboratory of Image Processing and Intelligent Control, Department of Control science and engineering, Huazhong university of science and Technology, Wuhan 430074, china b school of Electronic engineering and computer science, peking university, beijing 100871, china The Key Laboratory of Image Processing and Intelligent Control Department of Control Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China school of Electronic engineering and computer science Peking University Beijing 100871 China

The design of DNA sequences is one of the most practical and important research topics in DNA computing. We adopt taboo search algorithm and improve the method for the systematic design of equal-length DNA sequences, which can satisfy certain combinatorial and thermodynamic constraints. Using taboo search algorithm, our method can avoid trapping into local optimization and can nd a set of good DNA sequences satisfying required constraints.

关键词： DNA computing Taboo search algorithm DNA sequence design

Formation control for networked spacecraft in deep space:with or without communication delays and with switching topology

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science china(Information sciences) 2011年第3期54卷 469-481页

作者： WANG Nan 1,2, ZHANG TianWu 2 & XU JieQiong 1 1 school of Aeronautic science and engineering, beijing university of Aeronautics and Astronautics, beijing 100191, china 2 Department of computer science and engineering, Henan Institute of engineering, Zhengzhou 451191, china school of Aeronautic science and engineering Beijing University of Aeronautics and Astronautics Department of computer science and engineering Henan Institute of Engineering

In this paper, several formation controllers are developed with constant and variable connected communication topology for six-degree-of-freedom (6-DOF) networked spacecraft flying in deep space with constant and time-varying communication delays considered. In the control algorithm, any explicit leader does not exist in the formation team and it is required that each spacecraft communicate only with its neighbors and therefore the required communication loads of the whole formation is greatly reduced. The proposed control strategies allow that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtain its desired relative attitudes with its neighbors. Simulation results demonstrate the effectiveness of the proposed controllers.

关键词： deep space graph theory formation control communication topology delays

Algorithm of simulation time synchronization over large-scale nodes

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science in china(Series F) 2008年第9期51卷 1239-1255页

作者： ZHAO QinPing1,2,ZHOU Zhong1,2 & Lü Fang1,2 1 State Key Laboratory of Virtual Reality Technology and Systems,Beihang university,beijing 100083,china 2 school of computer science and engineering,Beihang university,beijing 100083,china State Key Laboratory of Virtual Reality Technology and Systems Beihang University school of computer science and engineering Beihang University

In distributed simulation, there is no uniform physical clock. And delay cannot be estimated because of jitter. So simulation time synchronization is essential for the event consistency among nodes. This paper investigates time synchronization algorithms over large-scale distributed nodes, analyzes LBTS （lower bound time stamp） computation model described in IEEE HLA standard, and then presents a grouped LBTS model. In fact, there is a default premise for existing algorithms that controi packets must be delivered via reliable transportation. Although, a theorem of time synchronization message＇s reliability is proposed, which proves that only those control messages that constrain time advance need reliability. It breaks out the default premise for reliability. Then multicast is introduced into the transmis- sion of control messages, and algorithm MCTS （multi-node coordination time synchronization） is proposed based on multicast. MCTS not only promotes the time advance efficiency, but also reduces the occupied network bandwidth. Experiment results demonstrate that the algorithm is better than others in both time advance speed and occupied network bandwidth. Its time advance speed is about 50 times per second when there are 1000 nodes, approximately equal to that of similar systems when there are 100 nodes.

关键词： distributed simulation time synchronization multi-node coordination LBTS multicast

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Salient region detection and segmentation for general object recognition and image understanding

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science china(Information sciences) 2011年第12期54卷 2481-2490页

作者： HUANG TieJun 1 , TIAN YongHong 1 , LI Jia 2 & YU HaoNan 11 National engineering Laboratory for Video Technology, school of Electrical engineering and computer science, peking university, beijing 100871, china 2 Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of sciences, beijing 100190, china National engineering Laboratory for Video Technology School of Electrical Engineering and Computer Science Peking University Key Laboratory of Intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences

General object recognition and image understanding is recognized as a dramatic goal for computer vision and multimedia retrieval. In spite of the great efforts devoted in the last two decades, it still remains an open problem. In this paper, we propose a selective attention-driven model for general image understanding, named GORIUM (general object recognition and image understanding model). The key idea of our model is to discover recurring visual objects by selective attention modeling and pairwise local invariant features matching on a large image set in an unsupervised manner. Towards this end, it can be formulated as a four-layer bottom-up model, i.e., salient region detection, object segmentation, automatic object discovering and visual dictionary construction. By exploiting multi-task learning methods to model visual saliency simultaneously with the bottom-up and top-down factors, the lowest layer can effectively detect salient objects in an image. The second layer exploits a simple yet effective learning approach to generate two complementary maps from several raw saliency maps, which then can be utilized to segment the salient objects precisely from a complex scene. For the third layer, we have also implemented an unsupervised approach to automatically discover general objects from large image set by pairwise matching with local invariant features. Afterwards, visual dictionary construction can be implemented by using many state-of-the-art algorithms and tools available nowadays.

关键词： object recognition image understanding visual saliency salient object segmentation visual dictionary

Optimization of Fractal Iterated Function System(IFS) with Probability and Fractal Image Generation

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Journal of university of science and Technology beijing 2001年第2期8卷 152-156页

作者： Berthe Kya, Yang Yang (Information engineering school, university of science and Technology beijing, beijing 100083, china) Information engineering school University of Science and Technology Beijing 100083 China

There are several methods for rendering fractal images based on IFS (Iterated Function System) in computer graphic; but one concern of the computer graphic community has been the efficiency rendering algorithms. The invariant measures arising from IFSP (Iterate Function System with Probability) using the probabilistic algorithm are also known as chaos games. The role of these probabilities to generate the image of the attractor has been investigated using a multi-fractal analysis. The conventional choice of probability associated with each set /S/ to generate the attractor in least time possible is introduced, then a new method based on the self similarity and multi-fractal analysis is presented. The efficiency of the new method has been proved over the conventional method.

关键词： optimization of fractal IFS compression IFSP multi-fractal analysis

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Development of SPM Quantitative Micromorphology Analysis Software

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 136-138页

作者： Suozai Li Libing Liao(school of Materials science and engineering, china university of Geosciences, beijing 100083, china) school of Materials science and engineering China University of Geosciences Beijing 100083 China

Scanning Probe Microscope (SPM) has great advantages in quantitative micromorphology analysis because of its conveniencein obtaining micromorphology information of materials on nanometer or atomic scale under control of a computer. Based on an established SPM quantitative micromorphology analysis model, an SPM image analysis software Which can calculate both two- and three-dimensional micromorphology parameters is developed.

关键词： SPM quantitative micromorphology analysis software

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