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STATISTICAL METHODS IN MEDICAL RESEARCH 2010年第1期19卷 53-70页

作者： Zhang, Zhigang Sun, Jianguo Univ Missouri Dept Stat Columbia MO 65211 USA Mem Sloan Kettering Canc Ctr Dept Epidemiol & Biostat New York NY 10065 USA

Interval-censored failure time data occur in many medical investigations as well as other studies such as demographical and sociological studies. They include the usual right-censored failure time data as a special case but provide much more complex structure and less relevant information than the right-censored data. This article reviews some basic concepts, issues and the corresponding statistical approaches related to the analysis of interval-censored data as well as recent advances. In particular, we discuss estimation of a survival function, comparison of several treatments and regression analysis as well as competing risks analysis and truncation in the presence of interval censoring. A well-known example of interval-censored data is described and analysed to illustrate some of the statistical procedures discussed..

关键词： FAILURE TIME DATA PROPORTIONAL HAZARDS MODEL MAXIMUM-LIKELIHOOD ESTIMATOR LINEAR TRANSFORMATION MODELS SELF-CONSISTENT ESTIMATOR ODDS REGRESSION-MODEL LOG-RANK TESTS EFFICIENT ESTIMATION EM algorithm MULTIPLE IMPUTATION expectation-maximisation algorithm WELLS regression analysis maximum likelihood estimation complex structure Cutoffs fault time Proportional Hazards Models Arsenic

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Blind detection of severely blurred 1D Barcode

Blind detection of severely blurred 1D Barcode

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IEEE Global Telecommunications Conference (GLOBECOM 2010)

作者： Dridi, Noura Delignon, Yves Sawaya, Wadih Septier, Francois Univ Lille Nord France Inst TELECOM TELECOM Lille1 LAGISFRE 3303CNRS F-59653 Villeneuve Dascq France

ISBN: (纸本)9781424456383

In this paper, we present a joint blind channel estimation and symbol detection for decoding a blurred and noisy 1D barcode captured image. From an information transmission point of view, we show that the channel impulse response, the noise power and the symbols can be efficiently estimated by taking into account the signal structure such as the cyclostationary property of the hidden Markov process to estimate. Based on the expectation-maximisation method, we show that the new algorithm offers significative performance gain compared to classical ones pushing back the frontiers of the barcode technology.

关键词： blind detection channel estimation channel impulse response expectation-maximisation algorithm expectation-maximisation method hidden Markov models hidden Markov process image denoising image restoration joint blind channel estimation noisy 1D barcode cap

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ToA Estimation for MB-OFDM UWB by Suppressing Energy Leakage

ToA Estimation for MB-OFDM UWB by Suppressing Energy Leakage

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MILCOM Military Communications Conference

作者： Xu, Huilin Yang, Liuqing Univ Florida Dept ECE Gainesville FL 32611 USA

ISBN: (纸本)9781424481804

In this paper, we estimate the time-of-arrival (ToA) of wireless channels by using the widely adopted equally-spaced channel estimator for the multi-band orthogonal frequency-division multiplexing (MB-OFDM) ultrawide-band (UWB) system. By suppressing the energy leakage due to the imperfect sampling of the leading channel paths, a novel ToA estimator is proposed for the MB-OFDM UWB system. This ToA estimator is evaluated and compared with the space alternating generalized expectation maximization (SAGE) algorithm in IEEE 802.15.4a UWB channels. Simulation results show that the proposed ToA estimator performs well in all channel models and outperforms SAGE by directly locating the first channel path.

关键词： IEEE 802.15.4a MB-OFDM UWB OFDM modulation ToA estimation UWB channels Zigbee energy leakage suppression equally-spaced channel estimator expectation-maximisation algorithm imperfect sampling orthogonal frequency division multiplexing space alternating ge

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A Grouped Ranking Model for Item Preference Parameter

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NEURAL COMPUTATION 2010年第9期22卷 2417-2451页

作者： Hino, Hideitsu Fujimoto, Yu Murata, Noboru Waseda Univ Sch Sci & Engn Shinjuku Ku Tokyo 1698555 Japan Aoyama Gakuin Univ Dept Integrated Informat Technol Kanagawa 2298558 Japan

Given a set of rating data for a set of items, determining preference levels of items is a matter of importance. Various probability models have been proposed to solve this task. One such model is the Plackett-Luce model, which parameterizes the preference level of each item by a real value. In this letter, the Plackett-Luce model is generalized to cope with grouped ranking observations such as movie or restaurant ratings. Since it is difficult to maximize the likelihood of the proposed model directly, a feasible approximation is derived, and the em algorithm is adopted to find the model parameter by maximizing the approximate likelihood which is easily evaluated. The proposed model is extended to a mixture model, and two applications are proposed. To show the effectiveness of the proposed model, numerical experiments with real-world data are carried out.

关键词： expectation-maximisation algorithm Cinema Rating model parameters Likelihood Mixture models Restaurants

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A Novel Equivalent Circuit for On Chip Transmission Lines Modeling

A Novel Equivalent Circuit for On Chip Transmission Lines Mo...

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32nd Annual Custom Integrated Circuits Conference CICC

作者： Zeng, Dajie Wang, Hongrui Yang, Dongxu Zhang, Li Wang, Yan Yu, Zhiping Zhang, Yaohui Chinese Acad Sci Inst Sinano Suzhou Peoples R China Tsinghua Univ Inst Microelect Beijing Peoples R China

ISBN: (纸本)9781424457601

Microstrip transmission line (MS), coplanar waveguide transmission line (CPW), grounded coplanar waveguide transmission line (GCPW), slow-wave transmission line with slotted grounded shields (GSCPW), slow-wave transmission line with slotted floating shields (FSCPW) are widely used in the silicon technology. Because the quasi-TEM assumption is still valid in these structures, an equivalent circuit is proposed to model all these structures. In this work, we notice that for some types of transmission lines, say GCPW and GSCPW, the per unit length capacitance increases with frequency. An LC series subcircuit is proposed to model this phenomenon. For CPW, GCPW, GSCPW and FSCPW, the model has very good accuracy and fits the measurement results very well up to the highest measurement frequency (40GHz). For MS, the results from the 3D EM simulation software are adopted and the model shows a great agreement with the simulation results up to the highest simulation frequency (100GHz).

关键词： 3D EM simulation software FSCPW model GSCPW model LC series subcircuit coplanar transmission lines coplanar waveguide components equivalent circuit equivalent circuits expectation-maximisation algorithm frequency 40 GHz grounded coplanar waveguide transmission line integrated circuit modelling microstrip lines microstrip transmission line on chip transmission lines modeling quasiTEM assumption silicon technology slot lines slotted floating shield slotted grounded shield slow wave structures slow-wave transmission line

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Localization of Wireless Sensor Nodes with erroneous anchors via EM algorithm

Localization of Wireless Sensor Nodes with erroneous anchors...

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IEEE Global Telecommunications Conference (GLOBECOM 2010)

作者： Leng, Mei Wu, Yik-Chung Univ Hong Kong Dept Elect & Elect Engn Hong Kong Hong Kong Peoples R China

ISBN: (纸本)9781424456383

Finding locations of the sensor nodes in Wireless Sensor Network has been an active research area in recent years. One important category of approaches uses distance measurements between anchors and sensors to localize the unknown node. However, most approaches assume that the anchor positions are perfectly known, while in practice the anchor positions may not be accurate due to estimation errors as well as observation errors. In this paper, we study the localization of wireless sensor node with erroneous anchors, and propose an EM estimator which iteratively refines the anchor positions and estimates the sensor location. Simulation results shows that the EM estimator converges in a few iterations and outperforms the existing robust least squares algorithm.

关键词： EM algorithm EM estimator anchor positions distance measurement distance measurements erroneous anchors estimation errors estimation theory expectation-maximisation algorithm iterations least squares algorithm least squares approximations observation erro

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Condition prognosis of mechanical drives based on nonlinear dynamical models

Condition prognosis of mechanical drives based on nonlinear ...

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Conference on Control and Fault-Tolerant Systems (SysTol)

作者： Gasperin, Matej Juricic, Dani Boskoski, Pavle Jozef Stefan Inst Dept Syst & Control Jamova 39 Ljubljana Slovenia

ISBN: (纸本)9781424481545

Forecasting the condition of the equipment is becoming an important ingredient of the advanced maintenance and asset management systems. In this paper a probabilistic approach to the prognosis of damage progression in gearboxes is presented. It is based on a stochastic nonlinear grey-box model of the underlying wear phenomena. Model parameters are estimated from the available vibration records by using an iterative Maximum Likelihood procedure. The procedure relies on the expectation-Maximization algorithm and the Unscented Kalman filter for estimation of hidden system states. The algorithm has been used to predict the normal operating horizon of a single-stage gearbox system. Several test runs of the system have been preformed to validate the algorithm.

关键词： asset management systems condition monitoring condition monitoring condition prognosis damage progression drives expectation-maximisation algorithm expectation-maximization algorithm gearboxes gears maximum likelihood estimation maximum likelihood procedure mechanical drives nonlinear dynamical models stochastic nonlinear model unscented Kalman filter vibration vibrations wear wear

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Joint Iterative Channel Estimation and Data Detection for MIMO-CDMA Systems over Frequency-Selective Fading Channels

Joint Iterative Channel Estimation and Data Detection for MI...

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IEEE Global Telecommunications Conference (GLOBECOM 2010)

作者： Assra, Ayman Hamouda, Walaa Youssef, Amr Concordia Univ Dept Elect & Comp Engn Montreal PQ H3G 1M8 Canada Concordia Univ Concordia Inst Informat Syst Engn Montreal PQ H3G 1M8 Canada

ISBN: (纸本)9781424456383

In this paper, we present an iterative joint channel estimation and data detection technique for multiple-input multiple-output (MIMO) code-division multiple-access (CDMA) systems over frequency-selective fading channels. Based on the expectation-maximization (EM) algorithm, the proposed iterative receiver achieves a performance close to the optimum maximum-likelihood (ML) receiver. In addition, the performance of the proposed receiver is optimized through weight coefficients using the minimum mean-square error (MMSE) criterion. Compared to the single-user bound, our results show that the proposed receiver can mitigate the multiple-access interference and attain the full system diversity. Furthermore, our simulation results confirm that the proposed receiver is near-far resistant and offers fast convergence in severe near-far scenarios.

关键词： MIMO communication MIMO-CDMA system channel estimation code division multiple access data detection technique diversity reception expectation maximization algorithm expectation-maximisation algorithm fading channels frequency selective fading channel full

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Estimation and Modelling of NLoS Time-Variant Multipath for Localization Channel Model in Mobile Radios

Estimation and Modelling of NLoS Time-Variant Multipath for ...

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IEEE Global Telecommunications Conference (GLOBECOM 2010)

作者： Wang, Wei Jost, Thomas Dammann, Armin German Aerosp Ctr DLR Inst Commun & Nav D-82234 Wessling Germany

ISBN: (纸本)9781424456383

Time Based (TB) localization in terrestrial communications mobile radio as a complementation to global navigation satellite systems has gained recently plenty of interests. As an essential tool to develop suitable algorithms for joint communications and localizations in mobile radio networks, the wireless channel model has a growing significance. For both communications and localizations, the time evolution of multipath components is essential especially for tracking applications. Moreover, the Non Line-of-Sight (NLoS) error due to an undetectable line-of-sight path introduces an additional range error for TB localizations, which needs to be taken into account in the channel model. In this paper we present a space-alternating generalized expectation-maximization based Kalman filter method to efficiently estimate and track the time-variant multipath components based on a channel measurement campaign. The modeling of time-variant multipath characteristics, in terms of NLoS error, variance of path number, and the life span, are presented in this paper as well.

关键词： Kalman filter method Kalman filters NLoS time-variant multipath estimation NLoS time-variant multipath modelling channel measurement campaign expectation-maximisation algorithm global navigation satellite systems joint communications localization channel

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New reconstruction algorithm, distance dependent exact, with reduced statistical α error, dedicated to emission tomography using a collimator with large and long holes

New reconstruction algorithm, distance dependent exact, with...

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32nd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBC 10)

作者： Jeanguillaume, Christian Simonnet, Richard Rakotonirina, Herve Loeb, Jean Jacques Loeb, J. J. Univ Angers Lab Ingn Syst Automatises 62 Ave Notre Dame Lac F-49000 Angers France CHU Angers Serv Med Nucl F-49933 Angers France LAREMA Lab Angevin REcherche MAth F-49045 Angers France

ISBN: (纸本)9781424441242

SPECT (single photon emission computerized tomography) is physically one of the worst medical imaging modalities. Despite a considerable and still increasing medical impact, its spatial resolution (beyond 1 cm) and its sensitivity (less than 10(-4)) are both awful. This situation is mainly due to the use of a thin parallel hole collimator. In addition the application of the unfitted radon-transform worsens the figure. We already suggested a different approach of collimation called CACAO in French standing for computer aided collimation gamma camera. This approach uses a large and long hole collimator, a different sequence of acquisition with a linear scanning motion and a dedicated reconstruction program taking full account of the depth dependent response function. Up to now, however, the CACAO project has failed to convince the scientific community of its superiority over the conventional thin hole collimator. This is due of a lack of a good reconstruction algorithm. In this paper we depict a new tomographic reconstruction algorithm for the CACAO problem. In addition to the former cited advantages, this new algorithm is exact, it takes full account of the finite geometry of the collimator holes, it reduces the type 1 statistical error (false positive) and reduces the hindering effect of points with large errors (outliers). Example of reconstruction with exact data and with a limited number of detected photons are provided. Comparison with MLEM algorithm is provided.

关键词： CACAO MLEM algorithm SPECT collimators computer aided collimation gamma camera depth dependent response function distance dependent exact emission tomography expectation-maximisation algorithm image reconstruction large hole collimator linear scanning motion long hole collimator medical image processing medical imaging reconstruction algorithm reduced statistical Î± error single photon emission computed tomography single photon emission computerized tomography statistical analysis

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