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MOVING RATIO TEST FOR MULTIPLE CHANGES IN PERSISTENCE

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Journal of Systems Science & Complexity 2012年第3期25卷 582-593页

作者： Zhanshou CHEN zheng tian Department of Mathematics Qinghai Normal University Department of Applied Mathematics Northwestern Polytechnical University

This paper proposes a moving ratio test, which is a modified version of ratio test by involving a bandwidth parameter, to detect multiple changes in persistence, and to determine the direction of switch. The asymptotic distribution as well as its consistency are established. In order to estimate the change points, the authors propose a two step estimate approach. Simulations illustrate the performance of the test and estimate procedures in finite samples. An application to the analysis of Sweden/US foreign exchange rate demonstrates the validity of the procedure in practice.

关键词： Bandwidth multiple changes in persistence moving ratio test.

LEARNING GRANGER CAUSALITY GRAPHS FOR MULTIVARIATE NONLINEAR TIME SERIES

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Journal of Systems Science and Systems Engineering 2009年第1期18卷 38-52页

作者： Wei GAO zheng tian Department of Applied Mathematics Northwest Polytechnical University Xi'an Shanxi 710072 China estate Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China

An information theory method is proposed to test the. Granger causality and contemporaneous conditional independence in Granger causality graph models. In the graphs, the vertex set denotes the component series of the multivariate time series, and the directed edges denote causal dependence, while the undirected edges reflect the instantaneous dependence. The presence of the edges is measured by a statistics based on conditional mutual information and tested by a permutation procedure. Furthermore, for the existed relations, a statistics based on the difference between general conditional mutual information and linear conditional mutual information is proposed to test the nonlinearity. The significance of the nonlinear test statistics is determined by a bootstrap method based on surrogate data. We investigate the finite sample behavior of the procedure through simulation time series with different dependence structures, including linear and nonlinear relations.

关键词： Multivariate nonlinear time series Granger causality graph conditional mutual information surrogate data

New determination of the gravitational constant G

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National Science Review 2020年第12期7卷 1796-1797页

作者： zheng-tian Lu Hefei National Laboratory for Physical Sciences at the Microscale CAS Center for Excellence in Quantum Information and Quantum PhysicsUniversity of Science and Technology of China

A new and so far the most precise determination of the gravitational constant G has been made by Jun Luo and colleagues at the Huazhong University of Science and Technology(HUST) [1].The combination of G with two other most fundamental physical constants,the speed of light c and Planck’s constant h,can together construct the natural units(*** units) of time,length and *** relationships inform us that,

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A structural variation genotyping algorithm enhanced by CNV quantitative transfer

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Frontiers of Computer Science 2022年第6期16卷 159-165页

作者： tian zheng Xinyang QIAN Jiayin WANG Department of Computer Science and Technology School of Electronic and Information EngineeringXi’an Jiaotong UniversityXi’an710049China Institute of Data Science and Information Quality Shaanxi Engineering Research Center of Medical and Health Big DataXi’an Jiaotong UniversityXi’an710049China

Genotyping of structural variations considering copy number variations(CNVs)is an infancy and challenging ***,a prevalent form of critical genetic variations that cause abnormal copy numbers of large genomic regions in cells,often affect transcription and contribute to a variety of *** characteristics of CNVs often lead to the ambiguity and confusion of existing genotyping features and algorithms,which may cause heterozygous variations to be erroneously genotyped as homozygous variations and seriously affect the accuracy of downstream *** the allelic copy number increases,the error rate of genotyping increases *** instances with different copy numbers play an auxiliary role in the genotyping classification problem,but some will seriously interfere with the accuracy of the *** by these,we propose a transfer learning-based method to genotype structural variations accurately considering *** method first divides the instances with different allelic copy numbers and trains the basic machine learning framework with different genotype *** maximizes the weights of the instances that contribute to classification and minimizes the weights of the instances that hinder correct *** adjusting the weights of the instances with different allelic copy numbers,the contribution of all the instances to genotyping can be maximized,and the genotyping errors of heterozygote variations caused by CNVs can be *** applied the proposed method to both the simulated and real datasets,and compared it to some popular algorithms including GATK,Facets and *** experimental results demonstrate that the proposed method outperforms the others in terms of accuracy,stability and *** source codes have been uploaded at github/TrinaZ/CNVtransfer for academic use only.

关键词： genotyping copy number variations transfer earning

LEARNING CAUSAL GRAPHS OF NONLINEAR STRUCTURAL VECTOR AUTOREGRESSIVE MODEL USING INFORMATION THEORY CRITERIA

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Journal of Systems Science & Complexity 2014年第6期27卷 1213-1226页

作者： WEI Yuesong tian zheng XIAO Yanting School of Mathematical Science Huaibei Normal University Department of Applied Mathematics Northwest Polytechnical University

Detection and clarification of cause-effect relationships among variables is an important problem in time series analysis. Traditional causality inference methods have a salient limitation that the model must be linear and with Gaussian noise. Although additive model regression can effectively infer the nonlinear causal relationships of additive nonlinear time series, it suffers from the limitation that contemporaneous causal relationships of variables must be linear and not always valid to test conditional independence relations. This paper provides a nonparametric method that employs both mutual information and conditional mutual information to identify causal structure of a class of nonlinear time series models, which extends the additive nonlinear times series to nonlinear structural vector autoregressive models. An algorithm is developed to learn the contemporaneous and the lagged causal relationships of variables. Simulations demonstrate the effectiveness of the nroosed method.

关键词： Causal graphs conditional independence conditional mutual information nonlinear struc-tural vector autoregressive model.

LEARNING MULTIVARIATE TIME SERIES CAUSAL GRAPHS BASED ON CONDITIONAL MUTUAL INFORMATION

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Journal of Systems Science and Systems Engineering 2013年第1期22卷 38-51页

作者： Yuesong WEI zheng tian Yanting XIAO School of Mathematical Science Huaibei Normal University Department of Applied Mathematics Northwest Polytechnical University

Detection and clarification of cause-effect relationships among variables is an important problem in time series *** paper provides a method that employs both mutual information and conditional mutual information to identify the causal structure of multivariate time series causal graphical models.A three-step procedure is developed to learn the contemporaneous and the lagged causal relationships of time series causal *** to conventional constraint-based algorithm, the proposed algorithm does not involve any special kinds of distribution and is *** properties are especially appealing for inference of time series causal graphs when the prior knowledge about the data model is not *** and case analysis demonstrate the effectiveness of the method.

关键词： Multivariate time series causal graphs conditional independence conditional mutual information

Distribution function estimates by Wasserstein metric and Bernstein approximation for C^(-1) functions

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Applied Mathematics(A Journal of Chinese Universities) 2015年第2期30卷 141-150页

作者： WU Zong-min tian zheng Shanghai Key Laboratory for Contemporary Applied Mathematics School of Mathematical SciencesFudan University

The aim of the paper is to estimate the density functions or distribution functions measured by Wasserstein metric, a typical kind of statistical distances, which is usually required in the statistical learning. Based on the classical Bernstein approximation, a scheme is presented. To get the error estimates of the scheme, the problem turns to estimating the L1 norm of the Bernstein approximation for monotone C-1 functions, which was rarely discussed in the classical approximation theory. Finally, we get a probability estimate by the statistical distance.

关键词： Wasserstein metric Bernstein approximation L1 norm approximation confidence interval

Functions and behaviors of activated sludge extracellular polymeric substances (EPS): a promising environmental interest

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Journal of Environmental Sciences 2006年第3期18卷 420-427页

作者： tian Yu zheng Lei SUN De-zhi Department of Environmental Science and Engineering Harbin Institute of Technology Harbin 150090 China.

Extracellular polymeric substances （EPS） are the predominant constituents of activated sludge and represent up to 80% of the mass of activated sludge. They play a crucial role in the flocculation, settling and dewatering of activated sludge. Furthermore, EPS also show great efficiency in binding heavy metals. So EPS are key factors influencing reduction in sludge volume and mass, as well as activity and utilization of sludge. EPS are of considerable environmental interest and hundreds of articles on EPS have been published abroad, while information on EPS in China is limited. In this paper, results of over 60 publications related to constituents and characteristics of EPS and their influences on flocculation, settling and dewatering of sludge are compiled and analyzed. Metal-binding ability of EPS is also discussed, together with a brief consideration of possible research interests in the future.

关键词： activated sludge environmental interest extracellular polymeric substances (EPS)

Multiscale stochastic hierarchical image segmentation by spectral clustering

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Science in China(Series F) 2007年第2期50卷 198-211页

作者： LI XiaoBin tian zheng Department of Applied Mathematics Northwestern Polytechnical University Xi'an 710072 China National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Science Beijing 100080 China

This paper proposes a sampling based hierarchical approach for solving the computational demands of the spectral clustering methods when applied to the problem of image segmentation. The authors first define the distance between a pixel and a cluster, and then derive a new theorem to estimate the number of samples needed for clustering. Finally, by introducing a scale parameter into the similarity function, a novel spectral clustering based image segmentation method has been developed. An important characteristic of the approach is that in the course of image segmentation one needs not only to tune the scale parameter to merge the small size clusters or split the large size clusters but also take samples from the data set at the different scales. The multiscale and stochastic nature makes it feasible to apply the method to very large grouping problem. In addition, it also makes the segmentation compute in time that is linear in the size of the image. The experimental results on various synthetic and real world images show the effectiveness of the approach.

关键词： spectral clustering graph multiscale random tree image segmentation