检索结果-内蒙古大学图书馆

em algorithms for Gaussian mixtures with split-and-merge operation

PATTERN RECOGNITION 2003年第9期36卷 1973-1983页

作者： Zhang, ZH Chen, CB Sun, J Chan, KL Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Beijing Sigma Ctr MSR Microsoft Res Asia Beijing 100080 Peoples R China

In order to alleviate the problem of local convergence of the usual em algorithm, a split-and-merge operation is introduced into the em algorithm for Gaussian mixtures. The split-and-merge equations are first presented theoretically. These equations show that the merge operation is a well-posed problem, whereas the split operation is an ill-posed problem because it is the inverse procedure of the merge. Two methods for solving this ill-posed problem are developed through the singular value decomposition and the Cholesky decomposition. Accordingly, a new modified em algorithm is constructed. Our experiments demonstrate that this algorithm is efficient for unsupervised color image segmentation. (C) 2003 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.

关键词： Gaussian mixtures em algorithms split-and-merge operation statistical computer vision image segmentation

来源：评论

学校读者我要写书评

暂无评论

em algorithms FOR ML FACTOR-ANALYSIS

引用

PSYCHOMETRIKA 1982年第1期47卷 69-76页

作者： RUBIN, DB THAYER, DT Educational Testing Service Rosedale Road 08540 Princeton New Jersey

The details of em algorithms for maximum likelihood factor analysis are presented for both the exploratory and confirmatory models. The algorithm is essentially the same for both cases and involves only simple least squares regression operations; the largest matrix inversion required is for aq ×q symmetric matrix whereq is the matrix of factors. The example that is used demonstrates that the likelihood for the factor analysis model may have multiple modes that are not simply rotations of each other; such behavior should concern users of maximum likelihood factor analysis and certainly should cast doubt on the general utility of second derivatives of the log likelihood as measures of precision of estimation.

关键词： factor analysis em algorithms maximum likelihood

来源：评论

学校读者我要写书评

暂无评论

PROBLemS WITH em algorithms FOR ML FACTOR-ANALYSIS

引用

PSYCHOMETRIKA 1983年第2期48卷 247-251页

作者： BENTLER, PM TANAKA, JS Department of Psychology University of California 90024 Los Angeles California

Rubin and Thayer recently presented equations to implement maximum likelihood (ML) estimation in factor analysis via the em algorithm. They present an example to demonstrate the efficacy of the algorithm, and propose that their recovery of multiple local maxima of the ML function “certainly should cast doubt on the general utility of second derivatives of the log likelihood as measures of precision of estimation.” It is shown here, in contrast, that these second derivatives verify that Rubin and Thayer did not find multiple local maxima as claimed. The only known maximum remains the one found by Jöreskog over a decade earlier. The standard errors obtained from the second derivatives and the Fisher information matrix thus remain appropriate where ML assumptions are met. The advantages of the em algorithm over other algorithms for ML factor analysis remain to be demonstrated.

关键词： factor analysis em algorithms maximum likelihood

来源：评论

学校读者我要写书评

暂无评论

DOA Estimation for Low-Cost Array Antenna System Based on GROUSE and em algorithms

DOA Estimation for Low-Cost Array Antenna System Based on GR...

引用

IEEE Asia Pacific Conference on Circuits and Systems (APCCAS)

作者： Yamada, Keita Ichige, Koichi Yokohama Natl Univ Dept Elect & Comp Engn Hodogaya Ku Yokohama Kanagawa 2408501 Japan

ISBN: (纸本)9781479952304

This paper proposes a high-resolution DOA (Direction Of Arrival) estimation method using GROUSE and em algorithms for low-cost array antenna system. The low-cost array antenna system, which uses less receiver modules than array elements, often leads worse DOA estimation accuracy when comparing with the full-cost array antenna system. The proposed method first employs the modified GROUSE algorithm to pre-estimate DOAs, and then the em algorithm is applied to further improve the DOA estimation accuracy. Performance of the proposed approach is evaluated through computer simulation.

关键词： antenna arrays direction-of-arrival estimation expectation-maximisation algorithm DOA estimation method em algorithms array antenna system direction of arrival modified GROUSE algorithm Accuracy Antenna arrays Arrays Direction-of-arrival estimation Estimation Receivers Signal to noise ratio Direction of arrival estimation expectation-maximisation algorithm Antenna arrays signal to noise ratios Receivers Grouse Angle of arrival ANTENNA SYSTem

来源：评论

学校读者我要写书评

暂无评论

An efficient particle-based online em algorithm for general state-space models

引用

IFAC-PapersOnLine 2015年第28期48卷 963-968页

作者： Olsson, Jimmy Westerborn, Johan KTH Royal Institute of Technology Sweden

Estimating the parameters of general state-space models is a topic of importance for many scientific and engineering disciplines. In this paper we present an online parameter estimation algorithm obtained by casting our recently proposed particle-based, rapid incremental smoother (PaRIS) into the framework of online expectation-maximization (em) for state-space models proposed by Cappé (2011). Previous such particle-based implementations of online em suffer typically from either the well-known degeneracy of the genealogical particle paths or a quadratic complexity in the number of particles. However, by using the computationally efficient and numerically stable PaRIS algorithm for estimating smoothed expectations of timeaveraged sufficient statistics of the model we obtain a fast algorithm with very limited memory requirements and a computational complexity that grows only linearly with the number of particles. The efficiency of the algorithm is illustrated in a simulation study. © 2015

关键词： Parameter estimation Computational efficiency Image segmentation Maximum principle State space methods Computationally efficient em algorithms Engineering disciplines On line parameter estimations Online expectation maximizations Particle filter Recursive estimation State space models

来源：评论

学校读者我要写书评

暂无评论

Solving weak transduction with em

引用

ROBOTICS AND AUTONOMOUS SYSTemS 2002年第3-4期39卷 129-143页

作者： Ivanov, YA Blumberg, BM MIT Media Lab Cambridge MA 02139 USA

In this paper we describe an algorithm designed for learning perceptual organization of an autonomous agent. The learning algorithm performs incremental clustering of a perceptual input under reward. The distribution of the input samples is modeled by a Gaussian mixture density, which serves as a state space for the policy learning algorithm. The agent learns to select actions in response to the presented stimuli simultaneously with estimating the parameters of the input mixture density. The feedback from the environment is given to the agent in the form of a scalar value, or a reward, which represents the utility of a particular clustering configuration for the action selection. The setting of the learning task makes it impossible to use supervised or partially supervised techniques to estimate the parameters of the input density. The paper introduces the notion of weak transduction and shows a solution to it using an em-based framework. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： em algorithms weak transduction weakly labeled data

来源：评论

学校读者我要写书评

暂无评论

A Fusion Method for Marine Radar Images Using em Algorithm

A Fusion Method for Marine Radar Images Using EM Algorithm

引用

World Automation Congress (WAC)

作者： Mita, Hokuto Kobashi, Syoji Nakagawa, Kazuya Nishiyama, Kohji Maeno, Hitoshi Kuramoto, Kei Hata, Yutaka Univ Hyogo Grad Sch Engn Himeji Initiat Computat Med & Hlth Care Technol Himeji Hyogo 6712280 Japan Osaka Univ WPI Immunol Res Ctr Suita Osaka 5650871 Japan Univ Penn Med Image Processing Grp Dept Radiol Philadelphia PA 19104 USA Furuno Elect Corp Nishinomiya Hyogo 6628580 Japan

ISBN: (纸本)9781467344975

Marine radar systems have been equipped by almost sea vehicles. However, radar image quality can be easily deteriorated by signal strength decay with increasing distance, blurring due to side lobes, signals of behind objects and of shaded area. And it is difficult to recover the artifacts. This paper proposes a new approach to improve radar image quality by image fusion. The fusion method generating high quality radar images is based on em algorithm. Performance was validated using radar images acquired from a single radar system at multiple locations. The experimental results showed that the proposed method constructed high quality radar images, and recovered signal decay and blurring due to side lobes.

关键词： component em algorithms marine radar radar image image fusion

来源：评论

学校读者我要写书评

暂无评论

Variational algorithms for biclustering models

引用

COMPUTATIONAL STATISTICS & DATA ANALYSIS 2015年 89卷 12-24页

作者： Duy Vu Aitkin, Murray Univ Melbourne Dept Math & Stat Melbourne Vic 3010 Australia

Biclustering is an important tool in exploratory statistical analysis which can be used to detect latent row and column groups of different response patterns. However, few studies include covariate data directly into their biclustering models to explain these variations. A novel biclustering framework that considers both stochastic block structures and covariate effects is proposed to address this modeling problem. Fast approximation estimation algorithms are also developed to deal with a large number of latent variables and covariate coefficients. These algorithms are derived from the variational generalized expectation-maximization (em) framework where the goal is to increase, rather than maximize, the likelihood lower bound in both E and M steps. The utility of the proposed biclustering framework is demonstrated through two block modeling applications in model-based collaborative filtering and microarray analysis. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Biclustering Stochastic block models em algorithms Generalized em algorithms Variational em algorithms MM algorithms

来源：评论

学校读者我要写书评

暂无评论

Large-scale simultaneous hypothesis testing in monitoring carbon content from French soil database - A semi-parametric mixture approach

引用

GEODERMA 2014年 219卷 117-124页

作者： Chauveau, Didier Saby, Nicolas P. A. Orton, Thomas G. Lemercier, Blandine Walter, Christian Arrouays, Dominique Univ Orleans CNRS MAPMO UMR 7349 Orleans France INRA Unite Infosol US1106 F-45000 Orleans France INRA UMR SAS F-35042 Rennes France

Investigating the information of the French National Soil Tests database for soil monitoring produces multiple hypothesis testing problems with hundreds or thousands of test responses to consider simultaneously. A largely used concept of error control in such multiple testing is the expected proportion of falsely rejected hypotheses, or False Discovery Rate (FOR). A related notion of local FDR (lFDR) can be appropriately represented by considering that the observed p-values come from a two-component mixture model where the component corresponding to the null hypothesis is known. In this work, we explore different solutions for FDR estimation. In particular, we introduce a specific version of a semi-parametric Expectation-Maximization (em) algorithm for lFDR estimation, and compare it to classical 1FDR estimation using parametric mixtures, and conventional FDR approaches. The performances of the different models for estimating the FDR and related criteria are first illustrated on the results of simulated multiple comparison tests. These approaches are then applied to soil carbon content monitoring on our database. The results show that not taking into account the FDR estimation can lead to over-estimation of the number of cantons (locations) subject to a significant change. However, we have detected large numbers of significant changes in the database that occurred during the time period of this study. Globally, losses in organic carbon are observed in Northern France, along the Atlantic coastal regions, and to a lesser extent for the data collected over the North-Eastern regions. The OC increases are more scattered over the territory. We also use the data to estimate the minimum number of samples needed at each period to detect a given change. (c) 2014 Elsevier B.V. All rights reserved.

关键词： em algorithms FDR Finite mixture France Semi-parametric mixtures Soil carbon monitoring

来源：评论

学校读者我要写书评

暂无评论

Protein classification by matching and clustering surface graphs

引用

PATTERN RECOGNITION 2006年第4期39卷 539-551页

作者： Lozano, MA Escolano, F Univ Alicante Dept Ciencia Computac & Inteligencia Artificial E-03080 Alicante Spain

In this paper, we address the problem of comparing and classifying protein surfaces with graph-based methods. Comparison relies on matching surface graphs, extracted from the surfaces by considering concave and convex patches, through a kernelized version of the Softassign graph-matching algorithm. On the other hand, classification is performed by clustering the surface graphs with ail em-like algorithm, also relying on kernelized Softassign, and then calculating the distance of an input surface graph to the closest prototype. We present experiments showing the Suitability of kernelized Softassign for both comparing and classifying surface graphs. (c) 2005 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.

关键词： protein classification graph matching energy minimization graph clustering em algorithms

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：