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Bounds on the entanglement attainable from unitary transformed thermal states in liquid-state nuclear magnetic resonance

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Physical Review A 2005年第3期71卷 032341-032341页

作者： Terri M. Yu Kenneth R. Brown Isaac L. Chuang Center for Bits and Atoms MIT Media Laboratory Cambridge Massachusetts 02139 USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Chemistry University of California Berkeley California 94720 USA Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA

The role of mixed-state entanglement in liquid-state nuclear magnetic resonance (NMR) quantum computation is not yet well understood. In particular, despite the success of quantum-information processing with NMR, recent work has shown that quantum states used in most of those experiments were not entangled. This is because these states, derived by unitary transforms from the thermal equilibrium state, were too close to the maximally mixed state. We are thus motivated to determine whether a given NMR state is entanglable—that is, does there exist a unitary transform that entangles the state? The boundary between entanglable and nonentanglable thermal states is a function of the spin system size N and its temperature T. We provide bounds on the location of this boundary using analytical and numerical methods; our tightest bound scales as N∼T, giving a lower bound requiring at least N∼22000 proton spins to realize an entanglable thermal state at typical laboratory NMR magnetic fields. These bounds are tighter than known bounds on the entanglability of effective pure states.

关键词： NMR QUANTUM COMPUTATION EXPERIMENTAL REALIZATION MIXED STATES INFORMATION computer ALGORITHM IMPLEMENTATION SEPARABILITY SEARCH PURIFICATION

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A novel shared segment protection method for guaranteed recovery time

A novel shared segment protection method for guaranteed reco...

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International Conference on Broadband Networks (BroadNets)

作者： J. Tapolcai P.-H. Ho D. Verchere T. Cinkler Department of Telecommunications and Media Informatics Budapest University슠of슠Technology슠and슠Economics Budapest Hungary Department of Electrical and Computer Engineering University of Waterloo Canada Alcatel Marcoussis France

Shared segment protection (SSP), compared to shared path protection (SPP) or shared link protection (SLP), provides an optimal protection configuration, since SSP can increase the number of connections sharing the same protection segments and can reduce the restoration time in case of single link failure. This paper provides a thorough study on SSP under the GMPLS-based recovery framework, where an effective survivable routing algorithm for SSP is proposed, called shared segment protection (SSP) algorithm. The main advantage of the SSP algorithm is to reduce the high computation complexity in solving the ILP formulation first introduced in P-H. Ho et al., (2004). With an efficient iterative approach the design space is significantly reduced by excluding all the links that result intolerably long routes. The tradeoff between the price (i.e., cost representing the amount of resources, and the blocking probability) and the restoration time is extensively studied by simulations on three networks with highly dynamic traffic. It is demonstrated that the SSP algorithm can be a powerful solution in the GMPLS-based recovery with a stringent delay upper bound for achieving high availability and restorability of the transport services. The comparison among the three protection types further verifies that SSP can yield significant advantages over SPP and SLP.

关键词： Protection Iterative algorithms Space power stations Routing Iterative methods Costs Telecommunication traffic Traffic control Delay Upper bound

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A study on multi-unit fingerprint verification

A study on multi-unit fingerprint verification

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5th International Conference on Audio - and Video-Based Biometric Person Authentication, AVBPA 2005

作者： Lee, Kangrok Park, Kang Ryoung Jang, Jain Lee, Sanghoon Kim, Jaihie Department of Electrical and Electronic Engineering Yonsei University 134 Sinchon-dong Seodaemun-gu Seoul 120-749 Korea Republic of Division of Media Technology Sangmyung University 7 Hongji-dong Chongro-gu Seoul 110-743 Korea Republic of Korea Republic of Division of Computer and Information Engineering Yonsei University 134 Sinchon-dong Seodaemun-gu Seoul 120-749 Korea Republic of

Previous fingerprint verification systems have achieved good results, but these have been affected by the quality of input data. Fingerprint verification systems that use many fingers or multiple impressions of the same finger are more efficient and reliable than systems that use a single finger. However, multiple impressions give inconvenience to the user and increase the overall verification time. Therefore, we use only two fingers (multi-unit fusion) to improve performance of the fingerprint verification system. We show that performance can be improved by selecting a better quality fingerprint image of two fingerprints. Also, we propose a new quality checking algorithm composed of three stages. Our experimental results show that when the quality checking algorithm is performed by selecting a better quality fingerprint image of two fingerprints, there is a significance improvement in performance of the fingerprint verification system. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Pattern recognition

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Effective memory reduction scheme used for reference frames in H.264/AVC video codec

Effective memory reduction scheme used for reference frames ...

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Midwest Symposium on Circuits and Systems (MWSCAS)

作者： Chih-Chang Chen Sheng-Shiung Chen O.T.C. Chen Chien-Fa Chen Fang-Chu Chen Department of Electrical Engineering Signal and Media Laboratories National Chung Cheng University Taiwan Digital Signal Processing Tech. Department of Computer & Communications Research Laboratory Industrial Technology and Research Institute Taiwan

In the H.264/AVC video codec, multiple reference frames are applied for motion estimation to provide good coding efficiency. However, multiple reference frames also require more memory cost than one reference frame used in a video codec. To minimize the amount of memory requirement, this work proposes to add a decision unit in the H.264/AVC codec to store these reference frames. The said decision unit would look closely at macroblock (MB) of the currently decoded frame to determine it's storage type to be compressed or reconstructed data, according to the encoding parameters of subblocks in this MB. Furthermore, an adaptive scheme is proposed to store the currently decoded frame as reconstructed picture for lowering the computational complexity and using the buffer in full. Experimental results reveal that the proposed memory reduction scheme requires lower complexity and better picture quality than the conventional work. Therefore, the proposed memory reduction scheme can be widely used in various applications of the H.264/AVC codec to minimize the memory requirement.

关键词： Automatic voltage control Video codecs Decoding Buffer storage Motion estimation Costs Computational complexity Videoconference Video compression Encoding

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Scalable temporal interest points for abstraction and classification of video events

Scalable temporal interest points for abstraction and classi...

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IEEE International Conference on Multimedia and Expo (ICME)

作者： Seung-Hoon Han ln-So Kweon Digital Media R&D Center Samsung Electronics Company Limited South Korea Robotics and Computer Vision Laboratory Division of Electrical Engineering Department of EECS Korea Advanced Institute of Science and Technology South Korea

The image sequence of a static scene includes similar or redundant information over time. Hence, motion-discontinuous instants can efficiently characterize a video shot or event. However, such instants (key frames) are differently identified according to the change of velocity and acceleration of motion, and such scales of change might be different on each sequence of the same event. In this paper, we present a scalable video abstraction in which the key frames are obtained by the maximum curvature of camera motion at each temporal scale. The scalability means dealing with the velocity and acceleration change of motion. In the temporal neighborhood determined by the scale, the scene features (motion, color, and edge) can be used to index and classify the video events. Therefore, those key frames provide temporal interest points (TIPs) for the abstraction and classification of video events.

关键词： Layout Acceleration Cameras Humans Research and development Robot vision systems computer vision Laboratories Image sequences Scalability

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Power splitters for ultralow refractive index metallic nanostructures waveguides

Power splitters for ultralow refractive index metallic nanos...

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SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics (IMOC)

作者： V.F. Rodriguez-Esquerre M. Koshiba H.E. Hernandez-Figueroa C.E. Rubio-Mercedes Division of Media and Network Technologies Hokkaido University Japan Department of Microwave and Optics School of Electrical and Computer Engineering State University of Campinas-UNICAMP Brazil Center of Exact Sciences and Technology State University of Mato Grosso do Sul Brazil

We investigated power splitters in air core waveguides with a metallic photonic crystal cladding. The mechanism of propagation in these guides is the total external reflection. The cladding is formed by a periodic arrangement of metallic wires on square or triangular lattices. Power splitters can be designed by modifying the geometry at the splitting region by introducing a reflecting structure in order to increase the transmission coefficient. Some splitters based on these structures are analyzed by an efficient frequency domain finite element approach.

关键词： Refractive index Nanostructures Optical waveguides Lattices Silver Copper Gold Electromagnetic waveguides Optical refraction Optical variables control

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Real time head tracking via camera saccade and shape-fitting

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2nd International Conference on Image Analysis and Recognition, ICIAR 2005

作者： Zhang, Jason Z. Lu, Ye Wu, Q.M. Jonathan Micro-technology and Sensing Group Institute for Fuel Cell Innovation National Research Council of Canada Vancouver BC V6T 1W5 Canada Vision and Media Laboratory School of Computing Science Simon Fraser University Burnaby BC V5A 1S6 Canada Department of Electrical and Computer Engineering University of Windsor Ont. N9B 3P4 Canada

ISBN: (纸本)3540290699

This paper presents a system that tracks human heads in real-time under unconstrained environments where target occlusion, varying illumination, and cluttered backgrounds exist. Tracking is formulated as an active visual servo problem based on the integration of a saccade and a smooth pursuit processes. The head is modelled as an ellipse computed from the color clusters of candidate targets using a robust least square ellipse fitting algorithm. The Farnsworth Perceptually Uniform Color Model is employed to represent the color information of the visual objects. Kalman filtering is applied to the head ellipse to track the evolution of the position, size, and orientation of the target such that the occlusion of objects with similar color and shape as those of the target are effectively accommodated. Experiments with tracking scenarios demonstrate the effectiveness of the system. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Tracking (position)

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Adaptive source and channel re-encoding to maximize tandem link performance

Adaptive source and channel re-encoding to maximize tandem l...

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2004 First International Symposium on Control, Communications and Signal Processing, ISCCSP 2004

作者： Gibson, Jerry D. Wei, Bo Media Arts Technology Program Electrical and Computer Engineering Univ. of California Santa Barbara Santa Barbara CA 93106-6065 Department of Electrical Engineering Southern Methodist University Dallas TX 75275

ISBN: (纸本)0780383796

We investigate the issues in voice communications over tandem heterogeneous network connections which require multiple source decoding/encoding operations. While it is known from speech coding research that tandem connections of different speech coders can extract a substantial performance penalty, it is shown that the use of error concealment and source re-encoding can improve system performance in the presence of channel impairments such as bit errors and packet losses. A new protocol is proposed for wireless LANs that reduces retransmissions and discarded packets, and hence reduces system delay and facilitates packet loss concealment.

关键词： Signal encoding

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Joint semi-blind channel estimation and data detection for MIMO-OFDM systems

Joint semi-blind channel estimation and data detection for M...

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Proceedings of the IEEE 6th Circuits and Systems Symposium on Emerging Technologies: Frontiers of Mobile and Wireless Communication

作者： Yue, Jiang Kim, Kyeong Jin Reid, Tony Gibson, Jerry D. Department of Electrical Engineering Southern Methodist University Dallas TX 75275 Nokia Research Center 6000 Connection Dr. Irving TX 75039 Media Arts and Technology Program Electrical and Computer Engineering University of California Santa Barbara Santa Barbara CA 93106-6065

ISBN: (纸本)0780379381

In MEMO systems, where multiple antennas are used at both transmitter and receiver to achieve high spectral efficiency, channel impulse reponses are often assumed to be constant over a block or packet This assumption of block stationarity on channels is valid for most fixed wireless scenarios. However, for communications in a high mobility environment, the assumption will result in considerable performance degradation. In this paper, we focus on channel estimation for a MIMO system with OFDM transmission technique. In our system, pilots are placed on NP subcarriers for a novel channel estimation at the receiver with Kalman filters. With the channels estimated by a Kalman filter, we apply the QRD-M algorithm for suboptimal data detection with reasonable computational cost The outputs of data detection are fed back to another Kalman filter for an improved channel estimation. By alternatively and iteratively using these two Kalman filters, a better channel estimation can be obtained. A simulation result of the bit error rate shows the improvement of 10 dB in SNR with four iterations over non-iteration.

关键词： Orthogonal frequency division multiplexing

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Robust bayesian cameras motion estimation using random sampling

Robust bayesian cameras motion estimation using random sampl...

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2004 International Conference on Image Processing, ICIP 2004

作者： Qian, Gang Chellappa, Rama Zheng, Qinfen Department of Electrical Engineering and Arts Media and Engineering Program Arizona State University Tempe AZ 85287-8706 Center for Automation Research Institute for Advanced Computer Studies University of Maryland College Park MD 20742-3275

In this paper, we propose an algorithm for robust 3D motion estimation of wide baseline cameras from noisy feature correspondences. The posterior probability density function of the camera motion parameters is represented by weighted samples. The algorithm employs a hierarchy coarse-to-fine strategy. First, a coarse prior distribution of camera motion parameters is estimated using the random sample consensus scheme (RANSAC). Based on this estimate, a refined posterior distribution of camera motion parameters can then be obtained through importance sampling. Experimental results using both synthetic and real image sequences indicate the efficacy of the proposed algorithm. ©2004 IEEE.

关键词： Motion estimation

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