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Analysing Mark-Recapture-Recovery Data in the Presence of Missing Covariate Data Via Multiple Imputation

JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS 2015年第1期20卷 28-46页

作者： Worthington, Hannah King, Ruth Buckland, stephen T. Univ St Andrews Sch Math & Stat St Andrews KY16 9LZ Fife Scotland Univ St Andrews Ctr Res Ecol & Environm Modelling St Andrews KY16 9LZ Fife Scotland

We consider mark-recapture-recovery data with additional individual time-varying continuous covariate data. For such data it is common to specify the model parameters, and in particular the survival probabilities, as a function of these covariates to incorporate individual heterogeneity. However, an issue arises in relation to missing covariate values, for (at least) the times when an individual is not observed, leading to an analytically intractable likelihood. We propose a two-step multiple imputation approach to obtain estimates of the demographic parameters. Firstly, a model is fitted to only the observed covariate values. Conditional on the fitted covariate model, multiple "complete" datasets are generated (i.e. all missing covariate values are imputed). Secondly, for each complete dataset, a closed form complete data likelihood can be maximised to obtain estimates of the model parameters which are subsequently combined to obtain an overall estimate of the parameters. Associated standard errors and 95 % confidence intervals are obtained using a non-parametric bootstrap. A simulation study is undertaken to assess the performance of the proposed two-step approach. We apply the method to data collected on a well-studied population of Soay sheep and compare the results with a Bayesian data augmentation approach. Supplementary materials accompanying this paper appear on-line.

关键词： Individual time-varying continuous covariates Mark-recapture-recovery data Missing values Multiple imputation two-step algorithm

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Calibration of three-axis fluxgate magnetometers with nonlinear least square method

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MEASUREMENT 2013年第4期46卷 1600-1606页

作者： Pang, Hongfeng Li, Ji Chen, Dixiang Pan, Mengchun Luo, Shitu Zhang, Qi Luo, Feilu Natl Univ Def Technol Coll Mechatron Engn & Automat Changsha 410073 Hunan Peoples R China

The accuracy of three-axis magnetometers is limited by different scales, bias of each axis and nonorthogonality between axes, which is usually lower than that of scalar magnetometers. In this paper, the nonlinear least square method is proposed to calibrate three-axis magnetometers. The validity of this method was proved by simulation, in which the estimated parameters of the error model are close to prearranged parameters. In experiment, a three-axis fluxgate magnetometer (DM-050), a two dimensional nonmagnetic rotation equipment and a proton magnetometer (GSM-19T) were used. The scalar value of magnetic field was obtained by proton magnetometer and considered to be the true value. The calibration performance of unscented Kalman filter (UKF), two-step algorithm and nonlinear least square were compared. Experimental results show that the error average and standard deviation of nonlinear least square are the least among the three methods. After calibration, the average of scalar error is reduced from -76.2 nT to -0.00093 nT and the standard deviation is reduced from 10.832 nT to 4.298 nT. The results suggest an effective way for the calibration of three-axis fluxgate magnetometers. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Three-axis magnetometers Nonlinear least square Unscented Kalman filter two-step algorithm Nonmagnetic rotation equipment

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Practical linear precoder design for finite alphabet multiple-input multiple-output orthogonal frequency division multiplexing with experiment validation

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IET COMMUNICATIONS 2013年第9期7卷 836-847页

作者： Zheng, Yahong Rosa Wang, Mingxi Zeng, Weiliang Xiao, Chengshan Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA

A low complexity precoding method is proposed for practical multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. Based on the two-step optimal precoder design algorithm that maximises the lower bound of the mutual information with finite-alphabet inputs, the proposed method simplifies the precoder design by fixing the right singular vectors of the precoder matrix, eliminating the iterative optimisation between the two steps, and discretising the search space of the power allocation vector. For a 4 x 4 channel, the computational complexity of the proposed precoder design is reduced to 3 and 6% of that required by the original two-step algorithm with quadrature phase shift keying (QPSK) and 8 phase-shift keying (8PSK), respectively. The proposed method achieves nearly the same mutual information as the two-step iterative algorithm for a large range of signal-to-noise ratio (SNR) region, especially for large MIMO size and/or high constellation systems. The proposed precoding design method is applied to a 2 x 2 MIMO-OFDM system with 2048 subcarriers by designing 1024 precoders for extended channel matrices of size 4 x 4. A transceiver test bed implements these precoding matrices in comparison with other existing precoding schemes. Indoor experiments are conducted for fixed-platform non-line-of-sight channels, and the data processing results show that the proposed precoding method achieves the lowest bit error rate compared with maximum diversity, classic water-filling and channel diagonalisation methods.

关键词： channel coding codecs computational complexity indoor radio iterative methods linear codes MIMO communication multiplexing OFDM modulation optimisation phase shift keying precoding radio transceivers transceivers channel diagonalisation methods water-filling methods maximum diversity bit error rate precoding method data processing fixed-platform nonline-of-sight channels indoor experiments precoding matrices transceiver test bed extended channel matrices MIMO-OFDM system MIMO size SNR region 8PSK QPSK quadrature phase shift keying two-step algorithm computational complexity precoder matrix finite-alphabet inputs two-step optimal precoder design algorithm MIMO OFDM systems low complexity precoding method frequency division multiplexing experiment validation finite alphabet multiple-input multiple-output orthogonal linear precoder design

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A two-step algorithm for solving singular linear systems with index one

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APPLIED MATHEMATICS AND COMPUTATION 2006年第1期175卷 472-485页

作者： Zhou, Jieyong Wei, Yimin Fudan Univ Dept Math Shanghai 200433 Peoples R China Shanghai Univ Finance & Econ Dept Appl Math Shanghai 200433 Peoples R China Shanghai Jiao Tong Univ Dept Math Shanghai 200240 Peoples R China

In this paper, a two-step algorithm for solving singular linear systems is presented. We compare this algorithm with a DGCR type algorithm [A. Sidi, A unified approach to Krylov subspace methods for the Drazin-inverse solution of singular non-symmetric linear systems, Linear Algebra Appl. 298 (1999) 99-113] by numerical experiments. An error analysis is given. (c) 2005 Elsevier Inc. All rights reserved.

关键词： iterative methods DGMRES two-step algorithm singular linear system Drazin inverse index

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Modification of two-step Monte Carlo algorithms based on the symmetry of the first step

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COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2009年第11期49卷 1921-1929页

作者： Mikhailov, G. A. Rozhenko, S. A. Russian Acad Sci Inst Computat Math & Math Geophys Siberian Branch Novosibirsk 630090 Russia Novosibirsk State Univ Novosibirsk 630090 Russia

two-step Monte Carlo algorithms are modified taking into account the symmetry (i.e., invariance) of the first step about some initial vector parameter of the modeled trajectory. In the modification, the modeling of this parameter is formally transferred to the second step of the algorithm. In the "splitting method," this means the randomization of the initial points of auxiliary trajectories. It is shown that the randomization can be improved by applying the Bellman principle.

关键词： Monte Carlo method two-step algorithm splitting method complexity estimation for algorithms

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Cloud Service and Service Selection algorithm Research 09

Cloud Service and Service Selection Algorithm Research

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World Summit on Genetic and Evolutionary Computation (GEC 09)

作者： Zeng, Wenying Zhao, Yuelong Zeng, Junwei S China Univ Technol Sch Comp Sci & Engn Guangdong Inst Sci & Technol Guangzhou 510640 Guangdong Peoples R China

ISBN: (纸本)9781605583266

This paper describes the cloud service architecture and key technologies for service selection algorithm. Cloud computing is a hot topic on software and distributed computing based on Internet, which means users can access storages and applications from remote servers by web browsers or other fixed or mobile terminals. Because the constrained resources of fixed or mobile terminals, cloud computing will provide terminals with powerful complementation resources to acquire complicated services. The paper discusses the cloud service architecture and key algorithms about service selection with adaptive performances and minimum cost. The cloud service architecture is reasonable and the proposed service selection algorithms are available, scalable, and adaptive to different types of environments of services and clients.

关键词： Cloud Service Cloud Computing Architecture Service Selection two-step algorithm

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A new non-linear algorithm for complete pre-flight calibration of magnetometers in the geomagnetic field domain

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING 2009年第G6期223卷 729-739页

作者： Asl, H. Ghanbarpour Pourtakdoust, S. H. Samani, M. Sharif Univ Technol Ctr Res & Dev Space Sci & Technol Dept Aerosp Engn Tehran 113658639 Iran Islamic Azad Univ Sci & Res Branch Tehran Iran

A new algorithm for complete pre-flight calibration of triple magnetometers is developed. The traditional approach for calibrating these sensors are based on a cumbersome procedure called 'swing' that involves levelling and rotating the vehicle containing the magnetometers through a series of known headings. Application of such a procedure is difficult and costly. Recently, new approaches have been developed to calibrate magnetometers without the need of attitude information. Such methods are used mostly for the calibration of biases and scale factors. Additionally in situations where misalignment errors are also to be estimated, they are usually modelled as errors of a non-orthogonal frame relative to an orthogonal frame creating six additional unknown parameters to be estimated. The presented approach in this article utilizes a three-step algorithm to fully calibrate triple magnetometers without the need of attitude information through a batch least-square non-linear estimator. Since misalignment parameters are not all identifiable through attitude-independent techniques, the measurement equation is initially factorized such that the non-observable parameters are removed. This would allow identification of three parameters through attitude-independent techniques, while identification of the other three that require horizon information is carried out using a secondary procedure. In step one of the proposed scheme, the non-linear observation equation is transformed, via two non-linear functions, to a linear space with respect to the unknown parameters and the new unknown parameters are estimated with batch least-square estimator. In the second step, the first non-linear function is solved for nine parameters that have non-linear relationships with respect to the desired biases, scale factors, and misalignments. Subsequently, the second non-linear function is solved giving the main unknown calibration parameters in a non-physical frame. Finally, in the third step, to

关键词： magnetometer calibration non-linear estimator two-step algorithm three-step algorithm

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MODIFIED algorithm FOR STEADY-STATE INTEGRATED SYSTEM OPTIMIZATION AND PARAMETER-ESTIMATION

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IEE PROCEEDINGS-D CONTROL THEORY AND APPLICATIONS 1988年第2期135卷 119-126页

作者： LIN, J CHEN, S ROBERTS, PD Control Engineering Centre City University London UK

The paper proposes an alternative modified two-step algorithm for steady state optimisation and parameter estimation. The aim is to simplify the model optimisation computation in the presence of general inequality constraints. Another advantage is that the existence of a model based optimal solution is ensured during the course of iteration. Optimality properties and convergence conditions are investigated. A simulation study is presented.

关键词： optimisation Simulation, modelling and identification general inequality constraints iterative methods Optimisation techniques iteration Interpolation and function approximation (numerical analysis) parameter estimation model based optimal solution steady state optimisation two-step algorithm

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