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IEEE Asia-Pacific Conference on Circuits and Systems

作者： Youquan Liu Shaohui Jiao Wen Wu Suvranu De State Key Lab of Computer Science Institute of Software Chinese Academy and Sciences Beijing China Faculty of Science and Technology University of Macau Macao China Department of Computer Science and Engineering Chinese University of Hong Kong Hong Kong China Faculty of Information Technology Macau University of Science and Technology Macao China Department of Mechanical Aerospace and Nuclear Engineering Rensselaer Polytechnic Institute Troy NY USA

In this paper we present a general FEM (finite element method) solution that enables fast dynamic deformation simulation on the newly available GPU (graphics processing unit) hardware with compute unified device architecture (CUDA) from NVIDIA. CUDA-enabled GPUs harness the power of 128 processors which allow data parallel computations. Compared to the previous GPGPU, it is significantly more flexible with a C language interface. We not only implement FEM deformation computation algorithms with CUDA but also analyze the performance in detail. Our test results indicate that the GPU with CUDA enables about 4 times speedup for FEM deformation computation on an Intel(R) Core 2 Quad 2.0 GHz machine with GeForce 8800 GTX.

关键词： Acceleration Deformable models Computational modeling Finite element methods Graphics Hardware computer architecture Concurrent computing Performance analysis Algorithm design and analysis

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Breaking instance I of new TTM cryptosystems

Breaking instance I of new TTM cryptosystems

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International Conference on Communications, Circuits and Systems (ICCCAS)

作者： Xuyun Nie Xin Jiang Lei Hu Jintai Ding Fengli Zhang University of Electronic Science and Technology of China Chengdu CN State Key Lab. of Inf. Security Grad. Sch. Chinese Acad. of Sci. Beijing Chinese Academy of Sciences Beijing Beijing CN School of Computer Science and Engineering University of Electronic Science and Technology Chengdu China

TTM is a type of multivariate public key cryptosystem. In 2007, the inventor of TTM proposed two new instances of TTM to resist the existing attack, in particular, the Nie et al attack. The two instances are claimed to achieve a security of 2 109 against Nie et al attack. In this paper, we show that the instance I is still insecure, and in fact, it do not achieve a better design in the sense that we can find a ciphertext-only attack utilizing the First Order Linearization Equations while for the previous version of TTM, only Second Order Linearization Equations can be used in the beginning stage of the previous attack. Different from previous attacks, we use an iterated linearization method to break the instances I. For any given valid ciphertext, we can find its corresponding plaintext within 2 31 F 2 to power of 8 -computations after performing once for any public key a computation of complexity less than 2 44 . Our experiment result shows we have unlocked the lock polynomials after several iterations, though we do not know the detailed construction of lock polynomials.

关键词： Equations Polynomials Cryptography Public key Public key cryptography Construction industry Security

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Adaptive foreground and shadow segmentation using hidden conditional random fields

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2007年第4期8卷 586-592页

作者： CHU Yi-ping YE Xiu-zi QIAN Jiang ZHANG Yin ZHANG San-yuan School of Computer Science State Key Lab. of CAD ＆ CG Zhejiang University Hangzhou 310027 China

Video object segmentation is important for video surveillance, object tracking, video object recognition and video editing. An adaptive video segmentation algorithm based on hidden conditional random fields (HCRFs) is proposed, which models spatio-temporal constraints of video sequence. In order to improve the segmentation quality, the weights of spatio-temporal con- straints are adaptively updated by on-line learning for HCRFs. Shadows are the factors affecting segmentation quality. To separate foreground objects from the shadows they cast, linear transform for Gaussian distribution of the background is adopted to model the shadow. The experimental results demonstrated that the error ratio of our algorithm is reduced by 23% and 19% respectively, compared with the Gaussian mixture model (GMM) and spatio-temporal Markov random fields (MRFs).

关键词： Video segmentation Shadow elimination Hidden conditional random fields （HCRFs） On-line learning

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Solution of Large Scale Matrix Inversion on Cluster and Grid

Solution of Large Scale Matrix Inversion on Cluster and Grid

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International Conference on Grid and Cooperative Computing (GCC)

作者： Ling Shang Zhijian Wang S.G. Petiton Feng Xu Laboratoire d'Informatique Fondamentale de Lille University of Science and Technology of Lille France College of Computer and Information Engineering Hohai University HHU Nanjing China Grand-Large Team INRIA Futurs and Laboratory RI UMR CNRS 5800 France State Key Lab for Novel software Technology Nanjing University Nanjing China

ISBN: (纸本)9781424432806;9780769534497

Large scale matrix inversion has been used in many domains and block-based Gauss-Jordan (G-J) algorithm as a classical method of large matrix inversion has become the focus of many researchers. Many people show us their parallel version of G-J. But the large parallel granularity in those algorithms restricts the performance of parallel block-based G-J algorithm, especially in the cluster environment consisting of PCs or workstations. This paper presents a fine-grained parallel G-J algorithm to settle the problem presented above. Experiments are made based on YML a framework which enables using different middleware to make large scale parallel computing for its feathers of components reuse, easy programmability for noncomputer professionals. Cluster and Grid environments are based on Grid'5000 platform, France. Experiments show us that the better performance of fine-grained parallel G-J algorithm and YML though overhead existing is a good solution for large scale parallel computing.

关键词： Large-scale systems Clustering algorithms Middleware Parallel processing Personal communication networks Libraries Grid computing Gaussian processes Workstations Algebra

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Robust Adaptive Neural Control of a Class of MIMO Nonlinear Systems

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Tsinghua science and Technology 2007年第1期12卷 14-21页

作者：胡亭亮朱纪洪孙增圻 State Key Lab of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University

In this paper we present a robust adaptive control for a class of uncertain continuous time multiple input multiple output （MIMO） nonlinear systems. Multiple multi-layer neural networks are employed to approximate the uncertainty of the nonlinear functions, and robustifying control terms are used to compensate for approximation errors. All parameter adaptive laws and robustifying control terms are derived based on Lyapunov stability analysis so that, under appropriate assumptions, semi-global stability of the closed-loop system is guaranteed, and the tracking error asymptotically converges to zero. Simulations performed on a two-link robot manipulator illustrate the approach and its performance.

关键词： direct adaptive control neural networks nonlinear system stability

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Accelerated Parallel Texture Optimization

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Journal of computer science & Technology 2007年第5期22卷 761-769页

作者：黄浩达童欣王文成 State Key Lab of Computer Science Institute of Software Chinese Academy of SciencesBeijing 100080China Graduate University of Chinese Academy of SciencesBeijing 100080China Microsoft Research Asia Beijing 100080 China State Key Lab of Computer Science Institute of Software Chinese Academy of SciencesBeijing 100080China

Texture optimization is a texture synthesis method that can efficiently reproduce various features of exemplar textures. However, its slow synthesis speed limits its usage in many interactive or real time applications. In this paper, we propose a parallel texture optimization algorithm to run on GPUs. In our algorithm, k-coherence search and principle component analysis （PCA） are used for hardware acceleration, and two acceleration techniques are further developed to speed up our GPU-based texture optimization. With a reasonable precomputation cost, the online synthesis speed of our algorithm is 4000＋ times faster than that of the original texture optimization algorithm and thus our algorithm is capable of interactive applications. The advantages of the new scheme are demonstrated by applying it to interactive editing of flow-guided synthesis.

关键词： texture synthesis energy minimization parallel GPU flow visualization

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Projection function for driver fatigue monitoring with monocular camera

Proceedings of the ACM Symposium on Applied Computing

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Proceedings of the ACM Symposium on Applied Computing 2007年 82-83页

作者： Bao, Depei Yang, Zehong Song, Yixu State Key Lab of Intelligent Technology and Systems Department of Computer Science Tsinghua University Beijing China

ISBN: (纸本)1595934804;9781595934802

The image projection has been proven to be an effective method for extracting image features. This paper utilizes multiple facial cues extracted by the projection function for driver vigilance monitoring. To measure vigilance, we calculate two metrics: PERCLOS and PERROTAT from facial state estimation. The main advantage of the presented system in contrast to existing ones is the usage of cheap equipment (only one monocular camera) to achieve a good cost-performance ratio and fast computation time. Copyright 2007 ACM.

关键词： Fatigue testing

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Efficient and robust camera extrinsic parameters calibration algorithm

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Journal of Computational Information Systems 2007年第1期3卷 285-293页

作者： Shi, Xifan Diao, Changyu Lu, Dongming College of Computer Science and Technology Zhejiang University Hangzhou 310027 China State Key Lab. of CAD and CG Zhejiang University Hangzhou 310027 China

The camera extrinsic parameters are composed of 3 rotation angles and a translation vector, which has 3 components, and the calibration process identifies these 6 parameters. It is proved that at least 3 corresponding points should be given for the process and when more than 3 points are given, the system is over determined and has to be solved by minimizing the RMS error. In this paper, a camera extrinsic parameters calibration algorithm or camera pose estimation algorithm is studied. The algorithm ensures its efficiency (20 milliseconds if no more than 9 corresponding points are given) and robustness by a good initial value guess and an omnidirectional search for poor input data. It has been successfully used in texture mapping for cultural relics such as a jade chisel from Jinsha (an archaeological site in the western suburbs of Chengdu) and a Buddha statue from Zhejiang Provincial Museum.

关键词： Virtual reality

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Feature analysis and texture synthesis

Feature analysis and texture synthesis

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2007 10th IEEE International Conference on computer Aided Design and computer Graphics, CAD/Graphics 2007

作者： Gu, Yuanting Wu, Enhua State Key Lab of Computer Science Institute of Software Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781424415793

Most texture synthesis algorithms explicitly or implicitly adopt Markov Random Field or similar distribution as their basic model to guide the synthesis process. However, MRF-like models can't handle textures wellw ith large scale structure or unstable structure due to their inherent local and stable assumptions. To make improvement in this regard, we propose a new texture analysis/synthesis framework that combines two main ideas. Firstly, in material space we decompose the texture contente into units with "basic shape" and "feature vector" Based on this, the space spanned by a set of sampled textons is constructed to help introduce additional changes upon textons. Secondly, in pattern space, using the idea of "feature texture" acquiredfrom texture swatch for different properties especially for distribution rules of textons, we may capture and manipulate the global structure flexibly. By this formalization, we are able to obtain a satisfactory texture appearance, and also a rich control ability as well. © 2007 IEEE.

关键词： Vector spaces

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Autonomous virtual human evacuation model in a fire building

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Journal of Computational Information Systems 2007年第2期3卷 759-765页

作者： Ji, Qingge Deng, Ye Lin, Xiaola Li, Bo Department of Computer Science School of Information Science and Technology Sun Yat-Sen University Guangzhou 510275 China State Key Lab. of CAD and CG Zhejiang University Hangzhou 310027 China

This paper describes an autonomous virtual human evacuation model in a fire accident scene. Based on the human's specific psychological and behavior response to the fire accident scene, we give the perceptions and describe details of the rules in which behavior planning is presented. We also show how the non-leadership agents' path planning method can be applied to virtual human evacuation model. Finally experiment results are presented to evaluate the proposed model.

关键词： Autonomous agents

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