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1st International Conference on Pervasive Technologies Related to Assistive Environments, PETRA 2008

作者： Caridakis, George Diamanti, Olga Karpouzis, Kostas Maragos, Petros Image Video and Multimedia Systems Lab. National Technical University of Athens Iroon Polytexneiou 9 15780 Athens Greece Computer Vision Speech Communication and Signal Processing Group National Technical University of Athens Iroon Polytexneiou 9 15780 Athens Greece

ISBN: (纸本)9781605580678

This work focuses on two of the research problems comprising automatic sign language recognition, namely robust computer vision techniques for consistent hand detection and tracking, while preserving the hand shape contour which is useful for extraction of features related to the handshape and a novel classification scheme incorporating Self-organizing maps, Markov chains and Hidden Markov Models. Geodesic Active Contours enhanced with skin color and motion information are employed for the hand detection and the extraction of the hand silhouette, while features extracted describe hand trajectory, region and shape. Extracted features are used as input to separate classifiers, forming a robust and adaptive architecture whose main contribution is the optimal utilization of the neighboring characteristic of the SOM during the decoding stage of the Markov chain, representing the sign class. Copyright 2008 ACM.

关键词： Image segmentation

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Analysis of empirical bayesian methods for neuroelectromagnetic source localization 19

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20th Annual Conference on Neural Information processing systems, NIPS 2006

作者： Wipf, David Ramírez, Rey Palmer, Jason Makeig, Scott Rao, Bhaskar Signal Processing Intelligent Systems Lab. University of California San Diego 92093 United States Swartz Center for Computational Neuroscience University of California San Diego 92093 United States

ISBN: (纸本)9780262195683

The ill-posed nature of the MEG/EEG source localization problem requires the incorporation of prior assumptions when choosing an appropriate solution out of an infinite set of candidates. Bayesian methods are useful in this capacity because they allow these assumptions to be explicitly quantified. Recently, a number of empirical Bayesian approaches have been proposed that attempt a form of model selection by using the data to guide the search for an appropriate prior. While seemingly quite different in many respects, we apply a unifying framework based on automatic relevance determination (ARD) that elucidates various attributes of these methods and suggests directions for improvement. We also derive theoretical properties of this methodology related to convergence, local minima, and localization bias and explore connections with established algorithms.

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Compliance of Single Frequency Ionospheric Delay Estimation and Cycle Slip Detection with Civil Aviation Requirements

Compliance of Single Frequency Ionospheric Delay Estimation ...

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2007 National Technical Meeting of the Institute-of-Navigation

作者： Ouzeau, Christophe Macabiau, Christophe Escher, Anne-Christine Roturier, Benoit ENAC TéSA DTI ENAC DSNA-DTI Signal Processing Lab. ENAC GNSS Navigation Subdivision DGAC DTI (Direction de la Technique et de l'Innovation) STNA Technical Group of ICAO Navigation Systems Panel

Ionosphere is a dispersive medium that can strongly affect GPS and GALILEO signals. Ionospheric delay affecting the GPS and GALILEO single frequency pseudorange measurements is the largest source of ranging error. In addition, this perturbation is difficult to model and thus difficult to predict. Nominal dual frequency measurements provide a good estimation of ionospheric delay. In addition, the combination of GPS and GALILEO navigation signals at the receiver level is expected to provide important improvements for civil aviation. It could, potentially with augmentations, provide better accuracy and availab.lity of ionospheric correction measurements. Indeed, GPS users will be able to combine GPS L1 and L5 frequencies, and future GALILEO signals will bring their contribution as some of them will be transmitted at the same frequencies as the GPS signals. However, if affected by radio frequency interference, a receiver can lose one or more frequencies leading to the use of only one frequency to estimate ionospheric code delay. Therefore, it is felt by the authors as an important task to investigate the performance of techniques trying to sustain multi-frequency performance when a multi-constellation receiver installed in an aircraft loses dual frequency capability, during critical phases of flight. After a loss of several frequencies leading to a single frequency degraded mode, a receiver can use code and carrier phase pseudoranges made on only one carrier frequency to estimate the ionospheric delay. To achieve this estimation, the receiver can use the difference between code and carrier phase measurements. Indeed, this quantity can be modelled as twice the ionospheric delay plus noise, multipath, and the carrier phase ambiguity. The ionospheric delay can then be extracted from this, provided the ambiguity is properly removed. This can be achieved after convergence of a Kalman Filter for example, but then cycle slips need to be monitored. The probability of a cycle sl

关键词： Ionospheric electromagnetic wave propagation

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Method of ICA based on estimating the PDF of signals

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Xi'an Dianzi Keji Daxue Xuebao/Journal of Xidian University 2005年第4期32卷 574-578页

作者： Li, Xiao-Jun Lou, Shun-Tian Zhang, Xian-Da Key Lab. of Radar Signal Processing Xidian Univ. Xi'an 710071 China State Key Lab. of Intelligent Technology and Systems Dept. of Automation Tsinghua Univ. Beijing 100084 China

Independent component analysis (ICA) is a method for finding independent components from multivariate (multidimensional) statistical data. Based on the optimal estimation function, a method for the estimation of the score function is developed. By using the Gaussian mixture model, an EM algorithm for approximating the probability density of the data is presented, and a stochastic gradient method is given to separate the independent components. To improve the accuracy and stability of the algorithm, an iterative method for estimating the PDF of data is presented, which can perform the separation of mixed sub-Gaussian from super-Gaussian sources. The performance of the method is shown by computer simulations.

关键词： Independent component analysis

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Processor Enhancements for Media Streaming Applications

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Journal of VLSI signal processing systems for signal, image and video technology 2005年第2期41卷 225-234页

作者： Bilavarn, S. Debes, E. Vandergheynst, P. Diguet, J. P. Signal Processing Institute Swiss Federal Institute of Technology (EPFL) Switzerland Architecture Research Lab Intel U.S.A. Lab. of Electronics and REal Time Systems LESTER University of South Britanny U.S.A.

The development of more processing demanding applications on the Internet (video broadcasting) on one hand and the popularity of recent devices at the user level (digital cameras, wireless videophones, ...) on the other hand introduce challenges at several levels. Today, such devices present processing capabilities and bandwidth settings that are inefficient to manage scalab.e QoS requirements in a typical media delivery framework. In this paper, we present an impact study of such a scalab.e data representation optimized for QoS (Matching Pursuit 3D algorithms) on processor architectures to achieve the best performance and power efficiency. A review of state of the art techniques for processor architecture enhancement let us expect promising opportunities from the latest developments in the reconfigurable computing research field. We present here the first design steps of an efficient reconfigurable coprocessor especially designed to cope with future video delivery and multimedia processing requirements. Architecture perspectives are proposed with respect to low development cost constraints, backward compatibilty and easy coprocessor usage using an original strategy based on a hardware/software codesign methodology.

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Journal of Information Science and Engineering: Editorial notice

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Journal of Information Science and Engineering 2005年第5期21卷 i-ii页

作者： Lee, Der-Tsai Amato, Nancy M. Chang, Shih-Fu Chen, Homer H. Chen, Tsuhan Hsu, Tsan-Sheng Hwang, Jenq-Neng Kuo, Sy-Yen Kuo, Tei-Wei Li, Chung-Sheng Tokuyama, Takeshi Wing, Jeannette Wu, Tzong-Chen Yen, John Computer Science at Texas A and M University United States Parasol Laboratory United States IEEE Transactions on Parallel and Distributed Systems Computing Research Association's Committee on the Status of Women in Computing Research CRA-W's Distributed Mentor Program United States Department of Electrical Engineering Columbia University United States Lab. United States College of Electrical Engineering and Computer Science National Taiwan University Taiwan IEEE Transactions on Circuits and Systems for Video Technology IEEE Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA United States ACM ACM SIGACT IEEE Computer Society IICM Austria Research and Development of the Department Multimedia Signal Processing Technical Committee IEEE Signal Processing Society United States IEEE Transactions on Circuits and systems for Video Technology College of Electrical Engineering and Computer Science National Taiwan Ocean University Keelung Taiwan Department of Electrical Engineering National Taiwan University Taiwan Department of Computer Science and Information Engineering National Taiwan University Taipei Taiwan IEEE Technical Committee on Real-Time Systems Computer Science Division IBM T.J. Watson Research Center United States IBM Research Division Graduate School of Information Sciences Tohoku University Japan ACM IPSJ Mathematical Society of Japan Japan Department of Computer Science Computer Science Department Carnegie Mellon University United States National Academies of Science's Computer Science and Telecommunications Board United States Microsoft's Trustworthy Academic Advisory Board Intel Research Pittsburgh's Advisory Board United States Dartmouth's Institute for Security Technology Studies Advisory Committee Canada Sloan Research Fellowships Program Committee United States ACM Taiwan China Information Sciences and Technology Pennsylvania State University United States Laboratory for Intelligent Agents Penn State's School of Info

No abstract availab.e

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Isolated word, speaker dependent recognition under the presence of noise, based on an audio retrieval algorithm

Isolated word, speaker dependent recognition under the prese...

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Conference Record of the Thirty-Eighth Asilomar Conference on signals, systems and Computers

作者： Vasiloglou, Nikolaos Schafer, Ronald W. Hans, Mat C. Georgia Institute of Technology Center for Signal and Image Processing Atlanta GA 30332 Hewlett-Packard Laboratories Mobile and Media Systems Lab. Palo Alto CA 94304

With rapidly increasing storage and computational capacity, a common PC can store and index hundreds of hours of speech. This suggests that new approaches based on database techniques might be useful in speech recognition and speech indexing. This paper presents a first step in such a direction. The algorithm developed relies on an indexed single-speaker database. The database consists of spoken utterances transcribed into text. The waveforms of these utterances are converted off-line to binary symbols called fingerprints through a nonlinear frequency-domain transform. The fingerprints are associated with the transcribed text. Given the fingerprint of a new waveform, the best word match from the database can be retrieved. A 3255 word database is used as a test bed. All the words from this database are mixed with white noise and time-scale modified to provide test data. The database is queried with the fingerprint of the test words and the best match is retrieved. The results of the experiments conducted are promising, showing a 99.5% recognition rate for a 20dB signal to Noise Ratio (SNR). © 2004 IEEE.

关键词： Speech recognition

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Controling the false positive detection rate in fuzzy clustering of fMRI data

Controling the false positive detection rate in fuzzy cluste...

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2004 2nd IEEE International Symposium on Biomedical Imaging: Macro to Nano

作者： Jahanian, Hesamoddin Soltanian-Zadeh, Hamid Hossein-Zadeh, Gholam A. Signal and Image Processing Group School of Intelligent Systems IPM Tehran Iran Contr./Intelligent Proc. Ctr. E. Elec. Eng. Dept. University of Tehran Tehran Iran Image Analysis Lab. Radiology Dept. Henry Ford Health System Detroit MI United States

ISBN: (纸本)0780383885

Despite its potential advantages for fMRI analysis, fuzzy C-means (FCM) clustering suffers from limitations such as the need for a priori knowledge of the number of clusters, and unknown statistical significance and instability of the results. We propose a randomization-based method to control the false positive rate and estimate statistical significance of the FCM results. Using this novel approach, we develop an fMRI activation detection method. The ability of the method in controlling the false positive rate is shown by analysis of false positives in activation maps of resting-state fMRI data. Controlling the false positive rate in FCM allows comparison of different fuzzy clustering methods, using different feature spaces, to other fMRI detection methods. In this paper, using simulation and real fMRI data, we compare a novel feature space that takes the variability of the hemodynamic response function into account (HRF-based feature space) to the conventional cross-correlation analysis and FCM using the cross-correlation feature space. © 2004 IEEE.

关键词： Magnetic resonance imaging

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On the log determinant of non-central Wishart matrices

On the log determinant of non-central Wishart matrices

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Proceedings 2003 IEEE International Symposium on Information Theory (ISIT)

作者： Kim, Young-Han Lapidoth, Amos Information Systems Laboratory Stanford University Stanford CA 94305 United States Signal and Info. Processing Lab. Swiss Federal Inst. of Technol. CH-8092 Zurich Switzerland

We show that the expected log determinant of a complex non-central Wishart matrix is an increasing function of the non-centrality parameter. This demonstrates that the mutual information corresponding to an isotropically distributed Gaussian input to a multi-antenna Ricean fading channel is non-decreasing in the line-of-sight component.

关键词： Matrix algebra

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Modeling respiration from blood pressure waveform signals: An independent component approach

Modeling respiration from blood pressure waveform signals: A...

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Proceedings of the 2002 IEEE Engineering in Medicine and Biology 24th Annual Conference and the 2002 Fall Meeting of the Biomedical Engineering Society (BMES / EMBS)

作者： Shannon, T.T. McNames, J. Ellenby, M.S. Goldstein, B. Biomedical Signal Processing Lab. Portland State University Portland OR United States Complex Systems Laboratory Doernbecher Children's Hospital Oregon Health and Science University Oregon OR United States

We describe a method for extracting the additive effect of respiration from arterial blood pressure and central venous pressure waveform signals. Our method estimates a finite impulse response (FIR) separating filter using an independent component approach, analogous to minimizing the coherence of the separated components. We compare the extracted respiration component with the impedance based respiration signal and with a respiration estimate extracted using an LMS-optimal bandpass filter of comparable order.

关键词： Respiratory mechanics

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