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Decomposition of two classes of structural models

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Frontiers of Mathematics in China 2013年第6期8卷 1323-1349页

作者： Benchong LI Jianhua GUO key laboratory for applied statistics of moe and School of Mathematics and statistics Northeast Normal University Changchun 130024 China

The conditional independence structure of a common probability measure is a structural model. In this paper, we solve an open problem posed by Studeny [Probabilistic Conditional Independence Structures, Theme 9, p. 206]. A new approach is proposed to decompose a directed acyclic graph and its optimal properties are studied. We interpret this approach from the perspective of the decomposition of the corresponding conditional independence model and provide an algorithm for identifying the maximal prime subgraphs in a directed acyclic graph.

关键词： Combinatorial imset conditional independence model decomposition directed acyclic graph undirected graph

An Unprecedented Efficiency with Approaching 21%Enabled by Additive‑Assisted Layer‑by‑Layer Processing in Organic Solar Cells

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Nano-Micro Letters 2025年第2期17卷 372-375页

作者： Shuai Xu Youdi Zhang Yanna Sun Pei Cheng Zhaoyang Yao Ning Li Long Ye Lijian Zuo Ke Gao key laboratory of Advanced Green Functional Materials College of ChemistryChangchun Normal UniversityChangchun 130032People’s Republic of China Shandong Provincial key laboratory for Science of Material Creation and Energy Conversion School of Chemistry and Chemical EngineeringShandong UniversityQingdao 266237People’s Republic of China College of Polymer Science and Engineering Sichuan UniversityChengdu 610065People’s Republic of China State key laboratory and Institute of Elemento‑Organic Chemistry Centre of Nanoscale Science and Technology and Key Laboratory of Functional Polymer MaterialsRenewable Energy Conversion and Storage Center(RECAST)College of ChemistryNankai UniversityTianjin 300071People’s Republic of China Institute of Polymer Optoelectronic Materials and Devices State key laboratory of Luminescent Materials and Devices South China University of TechnologyGuangzhou 510640People’s Republic of China Tianjin key laboratory of Molecular Optoelectronic Sciences School of Materials Science and EngineeringTianjin UniversityTianjin 300350People’s Republic of China State key laboratory of Silicon Materials MOE Key Laboratory of Macromolecular Synthesis and FunctionalizationDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China

Recently published in Joule,Feng Liu and colleagues from Shanghai Jiaotong University reported a record-breaking 20.8%power conversion efficiency in organic solar cells(OSCs)with an interpenetrating fibril network active layer morphology,featuring a bulk p-in structure and proper vertical segregation achieved through additive-assisted layer-by-layer *** optimized hierarchical gradient fibrillar morphology and optical management synergistically facilitates exciton diffusion,reduces recombination losses,and enhances light capture *** approach not only offers a solution to achieving high-efficiency devices but also demonstrates the potential for commercial applications of OSCs.

关键词： Organic solar cells Additive-assisted layer-by-layer processing Three-dimensional fibril morphology Bulk p-i-n structure Optical management

Two-step Estimation for Longitudinal Data When the Working Correlation Matrix is a Linear Combination of Some Known Matrices

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Acta Mathematicae Applicatae Sinica 2019年第2期35卷 264-273页

作者： Yu-ling LI Wei GAO Man-Lai TANG Shu-rong ZHENG key laboratory for applied statistics of moe School of Mathematics and StatisticsNortheast Normal University School of applied Mathematics Beijing Normal University Department of Mathematics and statistics Hang Seng Management College

The generalized estimating equations(GEE) approach is perhaps one of the most widely used methods for longitudinal data analysis. While the GEE method guarantees the consistency of its estimators under working correlation structure misspecification, the corresponding efficiency can be severely affected. In this paper, we propose a new two-step estimation method in which the correlation matrix is assumed to be a linear combination of some known working matrices. Asymptotic properties of the new estimators are *** studies are conducted to examine the performance of the proposed estimators. We illustrate the methodology with an epileptic data set.

关键词： generalized estimating equations longitudinal data quadratic inference functions quasi-likelihood two-step estimation

Weighted estimating equation： modified GEE in longitudinal data analysis

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Frontiers of Mathematics in China 2014年第2期9卷 329-353页

作者： Tianqing LIU Zhidong BAI Baoxue ZHANG School of Mathematics Jilin University Changchun 130012 China key laboratory for applied statistics of moe and School of Mathematics and statistics Northeast Normal University Changchun 130024 China

The method of generalized estimating equations （GEE） introduced by K. Y. Liang and S. L. Zeger has been widely used to analyze longitudinal data. Recently, this method has been criticized for a failure to protect against misspecification of working correlation models, which in some cases leads to loss of efficiency or infeasibility of solutions. In this paper, we present a new method named as ＇weighted estimating equations （WEE）＇ for estimating the correlation parameters. The new estimates of correlation parameters are obtained as the solutions of these weighted estimating equations. For some commonly assumed correlation structures, we show that there exists a unique feasible solution to these weighted estimating equations regardless the correlation structure is correctly specified or not. The new feasible estimates of correlation parameters are consistent when the working correlation structure is correctly specified. Simulation results suggest that the new method works well in finite samples.

关键词： Consistency correlation efficiency (GEE) longitudinal data positive definite estimating equation (WEE) generalized estimating equation repeated measures weighted

Regression Analysis of Misclassified Current Status Data with Informative Observation Times

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Journal of Systems Science & Complexity 2023年第3期36卷 1250-1264页

作者： WANG Wenshan XU Da ZHAO Shishun SUN Jianguo Center for applied Statistical Research School of MathematicsJilin UniversityChangchun 130012China key laboratory of applied statistics of moe and School of Mathematics and statistics Northeast Normal UniversityChangchun 130024China Department of statistics University of MissouriColumbiaMO 65211USA

Misclassified current status data arises if each study subject can only be observed once and the observation status is determined by a diagnostic test with imperfect sensitivity and *** the situation,another issue that may occur is that the observation time may be correlated with the interested failure time,which is often referred to as informative censoring or observation *** is well-known that in the presence of informative censoring,the analysis that ignores it could yield biased or even misleading *** this paper,the authors consider such data and propose a frailty-based inference *** particular,an EM algorithm based on Poisson latent variables is developed and the asymptotic properties of the resulting estimators are *** numerical results show that the proposed method works well in practice and an application to a set of real data is provided.

关键词： Current status data EM algorithm informative censoring misclassification proportional hazard model

A Class of New Quadratic Vectorial Bent Functions

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Chinese Journal of Electronics 2020年第5期29卷 873-879页

作者： PANG Tingting ZENG Xiangyong LI Nian XU Yunge The Faculty of Mathematics and statistics Hubei Key Laboratory of Applied Mathematics Hubei University

A class of quadratic vectorial bent functions having the form F（x）=Trm~n(ax~(2s1+1))+Tr1~n(bx~(2s2+1)) is investigated,where n,m,s1,s2are positive integers and the coefficients a,b belong to the finite field F2~*** some discussions on the permutation property of certain linearized polynomials over F2~n,several classes of quadratic vectorial bent functions are presented for special cases of n,and it is also verified by computer that some vectorial bent functions proposed are extended affine inequivalent to all known quadratic vectorial bent functions.

关键词： Vectorial bent function Permutation polynomial Extended affine equivalence Finite field

Theory and calculation of stress transfer between fiber and matrix

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applied Mathematics and Mechanics(English Edition) 2015年第6期36卷 815-826页

作者： Jiayu WU Hong YUAN Renhuai LIU moe key laboratory of Disaster Forecast and Control in Engineering Institute of Applied Mechanics Jinan University

For the better use of composites and a deeper insight into the fracture propa- gation and stress transfer of the interface between fiber and matrix, a theoretical solution of closed form is presented with the assumed bilinear local bond-slip law and a parabolic shear stress distribution along the thickness of the matrix. The load-displacement re- lationship and interfacial shear stress are obtained for four loading stages. Finally, the effects of Young＇s modulus of fiber （matrix） and bond length on the performance of the interface are illustrated.

关键词： shear-lag method composite material interfacial mechanics

The effect of substrate on magnetic properties of Co/Cu multilayer nanowire arrays

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Chinese Physics B 2009年第8期18卷 3573-3576页

作者：任勇王建波刘青芳韩相华薛德胜 Institute of applied Magnetics Key Laboratory for Magnetism and Magnetic Materials of MOELanzhou University

Ordered Co/Cu multilayer nanowire arrays have been fabricated into anodic aluminium oxide templates with Ag and Cu substrate by direct current electrodeposition. This paper studies the morphology, structure and magnetic properties by transmission electron microscopy, selective area electron diffraction, x-ray diffraction, and vibrating sample magnetometer. X-ray diffraction patterns reveal that both as-deposited nanowire arrays films exhibit face-centred cubic structure. Magnetic measurements indicate that the easy magnetization direction of Co/Cu multilayer nanowire arrays films on Ag substrate is perpendicular to the long axis of nanowire, whereas the easy magnetization direction of the sample with Cu substrate is parallel to the long axis of nanowire. The change of easy magnetization direction attributed to different substrates, and the magnetic properties of the nanowire arrays are discussed.

关键词： multilayer nanowire Co/Cu anisotropy

A review of 20 years of naive tests of significance for high-dimensional mean vectors and covariance matrices

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Science China Mathematics 2016年第12期59卷 2281-2300页

作者： HU Jiang BAI ZhiDong key laboratory for applied statistics of Ministry of Education Northeast Normal University

We introduce the so-called naive tests and give a brief review of the new developments. Naive testing methods are easy to understand and perform robustly, especially when the dimension is large. We focus mainly on reviewing some naive testing methods for the mean vectors and covariance matrices of high-dimensional populations, and we believe that this naive testing approach can be used widely in many other testing problems.

关键词： naive testing methods hypothesis testing high-dimensional data multivariate analysis of variance(MANOVA)