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Multi features combination for pedestrian detection

Journal of Multimedia 2010年第1期5卷 79-84页

作者： Hu, Bin Wang, Shengjin Ding, Xiaoqing State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University Beijing 10084 China

In this paper, we propose a new approach for pedestrian detection in crowded scene from static images. The method is based on hybrid features, one type of middle-level features, which compose of multi features include gradient features, Edgelet features and haar-like features, three low-level feature sets. The gradient features focus on the local point information, the Edgelet features focus on the local edge information and the haar-like features focus on the local region information of the image. We use two stages of Adaboost to train the final classifier. In the first stage, the whole image is divided into many small windows which all include numerous low-level features. Adaboost is used in each window to get one middle-level feature which composes of some best features including gradient features, Edgelet features and haar-like features in this window. Secondly, from all middle-level features, Adaboost is used again to get the final classifier. Experiment results on common datasets and comparisons with some previous methods are given. © 2010 ACADEMY PUBLISHER.

关键词： Adaptive boosting

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Optimal simulation of a perfect entangler

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Physical Review A 2010年第3期81卷 032328-032328页

作者： Nengkun Yu Runyao Duan Mingsheng Ying State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Computer Science and Technology Tsinghua University Beijing 100084 People's Republic of China Centre for Quantum Computation and Intelligent Systems (QCIS) Faculty of Engineering and Information Technology University of Technology Sydney NSW 2007 Australia

A 2⊗2 unitary operation is called a perfect entangler if it can generate a maximally entangled state from some unentangled input. We study the following question: How many runs of a given two-qubit entangling unitary operation are required to simulate some perfect entangler with one-qubit unitary operations as free resources? We completely solve this problem by presenting an analytical formula for the optimal number of runs of the entangling operation. Our result reveals an entanglement strength of two-qubit unitary operations.

关键词： Quantum entanglement

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Collaborative filtering: Weighted nonnegative matrix factorization incorporating user and item graphs

Collaborative filtering: Weighted nonnegative matrix factori...

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10th SIAM International Conference on Data Mining, SDM 2010

作者： Gu, Quanquan Zhou, Jie Ding, Chris State Key Laboratory on Intelligent Technology and Systems Department of Automation Tsinghua University Beijing 100084 China Department of Computer Science and Engineering University of Texas at Arlington 416 Yates Street Arlington TX 76019 United States

Collaborative filtering is an important topic in data mining and has been widely used in recommendation system. In this paper, we proposed a unified model for collaborative filtering based on graph regularized weighted nonnegative matrix factorization. In our model, two graphs are constructed on users and items, which exploit the internal information (e.g. neighborhood information in the user-item rating matrix) and external information (e.g. content information such as user's occupation and item's genre, or other kind of knowledge such as social trust network). The proposed method not only inherits the advantages of model-based method, but also owns the merits of memory-based method which considers the neighborhood information. Moreover, it has the ability to make use of content information and any additional information regarding user-user such as social trust network. Due to the use of these internal and external information, the proposed method is able to find more interpretable low-dimensional representations for users and items, which is helpful for improving the recommendation accuracy. Experimental results on benchmark collaborative filtering data sets demonstrate that the proposed methods outperform the state of the art collaborative filtering methods a lot. Copyright © by SIAM.

关键词： Collaborative filtering

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Electromagnetic performance analysis and optimal design of modular machine with Halbach permanent-magnet array

Electromagnetic performance analysis and optimal design of m...

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作者： Zhang, Xinhua Ji, Nghua Sun, Yukun Zhu, Jihong Hua, Wei Zhao, Wenxiang School of Electrical and Information Engineering Jiangsu University Zhenjiang China State Key Laboratory of Intelligent Technology and Systems Tsinghua University Beijing China School of Electrical Engineering Southeast University Nanjing China

ISBN: (纸本)9788986510119

A modular permanent magnet (MPM) machine is a remerging fault tolerant machine, offering the advantages of fault tolerance, high power density and high efficiency. In this paper, the analytical design of a MPM motor with halbach PM array is investigated and a general design procedure is presented. Moreover, finite element method (FEM) is adopted to compare the electromagnetic performance of the designed machine with that of the conventional one, including flux density, PM fluxes and back-EMF. Furthermore, a co-simulation model of the MPM motor drive is developed to predict the system perform, in which magnetic circuit and the electric circuit are coupled in time-domain. Finally, the designed four-phase MPM motor is prototyped and test. The experimental results are given to verify the theoretical analysis.

关键词： Magnetic circuits

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Optimal Beamforming in MIMO Two-Way Relay Channels

Optimal Beamforming in MIMO Two-Way Relay Channels

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2010 IEEE Global Telecommunications Conference GLOBECOM 2010

作者： Xiyuan Wang Xian-Da Zhang State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory of Information Science and Technology Department of Automation Tsinghua University Beijing China

In this paper, the optimal analog network coding strategy (or relay beamforming) in MIMO two-way relay channels is studied. The weighted sum rate is used as the optimization criterion. Motivated by the classic Arimoto-Blahut algorithm, an iterative algorithm, which monotonically improves the cost function, is designed to update the relay beamformer. This relay beamforming algorithm is further extended to the case of joint source and relay beamforming. We show that in the iteration of the algorithms, the updates of the relay beamforming matrix and the source beamforming matrices are accomplished by solving a series of quadratic programs and quadratically constrained quadratic programs, which are of low complexity. Simulations are presented to compare the proposed algorithms with the performance upper bounds and the existing algorithms.

关键词： Relays Array signal processing Upper bound MIMO Algorithm design and analysis Joints Signal to noise ratio

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A Cooperative Spectrum Sensing Scheme Based on Linear PAC in Cognitive Radio Networks

A Cooperative Spectrum Sensing Scheme Based on Linear PAC in...

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IEEE Conference on Vehicular technology (VTC)

作者： Zhong Chen Xianda Zhang State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory of Information Science and Technology Department of Automation Tsinghua University Beijing China

In this paper, we consider a cognitive radio (CR) system in non-ideal fading wireless channels and propose a cooperative spectrum sensing scheme based on linear parallel access channel (PAC),serving as an alternative way to improve the cooperative spectrum sensing performance. We assume that the gains of the observation and transmission channels are all known which is available since we use standard preamble-aided channel estimation techniques to require channel state information. The key feature of the proposed scheme is that the observations are transmitted by amplify and forward transmissions from part of cognitive users (CUs) to a fusion center (FC) while the other CUs keep silent. The optimal weighting coefficients are obtained by maximizing the deflection coefficient under transmit power constraint and the optimal number and set of CUs in cooperation is searched by a sequential forward selection algorithm. Simulation results illustrate that the proposed optimal cooperative spectrum sensing scheme can significantly improve the spectrum sensing performance.

关键词： Sensors Copper Cognitive radio Optimization Signal to noise ratio Wireless sensor networks Chromium

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Feedback-enhanced ant colony routing algorithm for wireless sensor networks

Feedback-enhanced ant colony routing algorithm for wireless ...

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International Conference on Communications and Networking in China (CHINACOM)

作者： Chao Li Zhidong Deng State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory of Information Science and Technology Department of Computer Science and Technology Tsinghua University Beijing China

Routing problem in wireless sensor network (WSN) is challenging because WSN has distributed feature, transmission requirement, data redundancy and energy restriction. The idea of ant colony optimization (ACO) has been used in design of routing algorithms for WSN. However, ant colony routing algorithms (ACRs) generally have a serious problem of slow routing discovery so far. In this paper, a feedback-enhanced ant colony routing algorithm (FACR) making use of timed-out forward ants and backward broadcasting ants is proposed to accelerate the routing process. This algorithm is simulated on NS2 and is compared to traditional ant colony routing algorithm (TACR). The results indicate that FACR achieves lower packet loss rate than TACR under the same experimental conditions. Moreover, FACR shows a shorter end to end delay and higher residual energy rate.

关键词： Wireless sensor networks Routing

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A CWT-based SSVEP classification method for brain-computer interface system

A CWT-based SSVEP classification method for brain-computer i...

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International Conference on intelligent Control and Information Processing (ICICIP)

作者： Zimu Zhang Xiuquan Li Zhidong Deng State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Computer Science and Technology Tsinghua University Beijing China

Continuous wavelet transform (CWT) is used in this paper for steady-state visual evoked potential (SSVEP) detection in a brain-computer interface (BCI) system. The developed BCI system is designed for the remote control of humanoid robot through wireless sensor networks (WSN). A new CWT-based feature extraction method is presented and the whole framework of the BCI system is described. We investigated the feature extraction perfomance for different kinds of mother wavelets. Performance comparison was also conducted between CWT and fast Fourier transform (FFT). The experimental results show that the CWT-based method outperforms the FFT-based one in the SSVEP feature extraction scheme, specifically for short EEG segments. Moreover, the complex Morlet wavelet has significant superiority over several other mother wavelets in the CWT-based SSVEP feature extraction.

关键词： Continuous wavelet transforms Electroencephalography Feature extraction Wavelet analysis Wireless sensor networks

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Performance improvement of force feedback in bilateral teleoperation with PD controller

Performance improvement of force feedback in bilateral teleo...

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2010 IEEE/RSJ International Conference on intelligent Robots and systems

作者： Yuji Wang Fuchun Sun Huaping Liu Haibo Min Tsinghua National Laboratory of Information Science and Technology State Key Laboratory of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing China

This paper deals with the performance improvement of force feedback in bilateral teleoperation with PD controller. In traditional PD structures, the force feedback is simply determined by the position and velocity of the master and the slave manipulators, which may induce large resistance forces to the operator even in free motion. In this paper, a novel PD bilateral controller is proposed to tackle this problem. By incorporating a distance variable in the controller, we show that the appropriate force feedback can be obtained which still guarantees the system stability. To validate the proposed algorithm, an experiment is also carried out on our single degree of freedom teleoperation system. The results indicate that this strategy is effective for safe teleoperation missions.

关键词： Force PD control Force feedback Delay effects Voltage control Manipulator dynamics

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General image classification based on sparse representation

General image classification based on sparse representation

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IEEE International Conference on Cognitive Informatics

作者： Yuanyuan Zuo Bo Zhang State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory of Information Science and Technology Department of Computer Science and Technology Tsinghua University Beijing China

Sparse representation based classification algorithm has been used to solve the problem of human face recognition. The image database is confined to human frontal faces with only illumination and slight expression changes. Cropping and normalization of the face need to be done in advance. In this paper, we apply the sparse representation based algorithm to the problem of general image classification, with a certain degree of intra-class variations and background clutter. Experiments have been done with the sparse representation based algorithm and SVM classifiers on 25 object categories selected from Caltech101 dataset. Experimental results show that without the time-consuming parameter optimization, the sparse representation based algorithm achieves comparable performance with SVM. We argue that the sparse representation based algorithm can also be applied to general image classification task when appropriate image feature is used.

关键词： Classification algorithms Training Support vector machines Feature extraction Visualization Vocabulary Testing

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