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A fusion of least squares and empirical likelihood for regression models with a missing binary covariate

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Science China Mathematics 2016年第10期59卷 2027-2036页

作者： duan xiaogang WANG Zhi Department of Statistics Beijing Normal UniversityBeijing 100875China

Multiply robust inference has attracted much attention recently in the context of missing response data. An estimation procedure is multiply robust, if it can incorporate information from multiple candidate models, and meanwhile the resulting estimator is consistent as long as one of the candidate models is correctly specified. This property is appealing, since it provides the user a flexible modeling strategy with better protection against model misspecification. We explore this attractive property for the regression models with a binary covariate that is missing at random. We start from a reformulation of the celebrated augmented inverse probability weighted estimating equation, and based on this reformulation, we propose a novel combination of the least squares and empirical likelihood to separately handle each of the two types of multiple candidate models,one for the missing variable regression and the other for the missingness mechanism. Due to the separation, all the working models are fused concisely and effectively. The asymptotic normality of our estimator is established through the theory of estimating function with plugged-in nuisance parameter estimates. The finite-sample performance of our procedure is illustrated both through the simulation studies and the analysis of a dementia data collected by the national Alzheimer's coordinating center.

关键词： calibration covariate adjustment effect modification missing at random multiple robustness refitting

A weighted Wilcoxon estimate for the covariate-specific ROC curve

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Science China Mathematics 2017年第9期60卷 1705-1716页

作者： ZHANG QingZhao duan xiaogang ZHOU XiaoHua School of Economics and Wang Yanan Institute for Studies in Economics Xiamen University Department of Statistics Beijing Normal University Department of Biostatistics University of Washington

The covariate-specific receiver operating characteristic(ROC) curve is an important tool for evaluating the classification accuracy of a diagnostic test when it is associated with certain covariates. In this paper,a weighted Wilcoxon estimator is constructed for estimating this curve under the framework of location-scale model for the test result. The asymptotic normality is established, both for the regression parameter estimator and the estimator for the covariate-specific ROC curve at a fixed false positive point. Simulation results show that the Wilcoxon estimator compares favorably to its main competitors in terms of the standard error, especially when outliers exist in the covariates. As an illustration, the new procedure is applied to the dementia data from the national Alzheimer's coordinating center.

关键词： covariates location-scale model receiver operating characteristic curve Wilcoxon method

A Model-Embedded Trend Test with Incorporating Hardy-Weinberg Equilibrium Information

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Journal of Systems Science & Complexity 2017年第1期30卷 101-110页

作者： HU Xiaonan duan xiaogang PAN Dongdong ZHANG Sanguo LI Qizhai School of Mathematical Sciences University of Chinese Academy of Sciences Beijing 100049 China KeyLaboratory of Big Data Mining and Knowledge Management Chinese Academy of Sciences Beijing 100190China. School of Statistics Beijing Normal University Beijing 100875 China. Department of Statistics Yunnan University Kunming 650091 China Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy ofSciences Beijing 100190 China.

The genetic models are greatly important in the analysis of genetic epidemiologic studies and many of the studies are conducted using the trend test under the additive model. However, for many complex diseases and traits, the underlying genetic model for a genetic locus is usually uncertain. So a robust test free of genetic model is appropriate. In this paper, the authors propose a model-embedded trend test by incorporating Hardy-Weinberg equilibrium information and obtain the explicit formula to calculate its statistical significance. Extensive simulation studies show the proposed test is more robust than the existing procedures. Finally, a real application is further analyzed to show the performance of the proposed test.

关键词： Genetic model hardy-weinberg equilibrium power robust trend test.

Three-dimensional fuzzy logic system for process modeling and control

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控制理论与应用（英文版） 2010年第3期8卷 280-285页

作者： Han-Xiong LI xiaogang duan Zhi LIU Department of Manufacturing Engineering and Engineering Management City University of Hong Kong Hong Kong China School of Mechanical and Electrical Engineering Central South University Changsha Hunan 410083 China School of Automation Guangdong University of Technology Guangzhou Guangdong 510006 China

The traditional fuzzy logic system （FLS） can only model and control the process in two-dimensional nature. Many of real-world systems are of multidimensional features, such as, thermal and fluid processes with spatiotemporal dynamics, biological systems, or decision-making processes that contain stochastic and imprecise uncertainties. These types of systems are difficult for the traditional FLS to model and control because they require a third dimension for spatial or probabilistic information. The type-2 fuzzy set provides the possibility to develop a three-dimensional fuzzy logic system for modeling and controlling these processes in three-dimensional nature.

关键词： Three-dimensional fuzzy logic system Spatiotemporal system Modeling

Synergistic effects and kinetics analysis for co-pyrolysis of vacuum residue and plastics

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 71-81页

作者： Chao Wang xiaogang Shi Aijun duan Xingying Lan Jinsen Gao Qingang Xiong State Key Laboratory of Heavy Oil Processing China University of Petroleum-BeijingBeijing 102249China State Key Laboratory of Pulp and Paper Engineering South China University of TechnologyGuangzhou 510640China

This study utilizedathermogravimetric analyzer to assess the thermal decomposition behaviors and kinetics properties of vacuum residue(VR)and low-density polyethylene(LDPE)*** kinetic parameters were calculated using the Friedman *** demonstrate the interactive effects between LDPE and VR during the co-pyrolysis process,the disparity in mass loss and mass loss rate between the experimental and calculated values was *** co-pyrolysis curves obtained through estimation and experimentation exhibited significantdeviations,whichwerei influencedby temperature and mixing ratio.A negative synergistic interaction was observed between LDPE and VR,although this inhibitory effect could be mitigated or eliminated by reducing the LDPE ratio in the mixture and increasing the ***-pyrolysisprocess resulted in a reduction in carbon residue,which could be attributed to the interaction between LDPE and the heavy fractions,particularly resin and asphaltene,present in *** findings align with the pyrolysis behaviors exhibited by the four VR ***,it was observed that the co-pyrolysis process exhibited lower activation energy as the VR ratio increased,indicating a continuous enhancement in the reactivity of the mixed samples during co-pyrolysis.

关键词： co-pyrolysis heavy residual oil polyethylene thermogravimetric analysis synergistic effects

Evaluation of lightning-induced overvoltage on a 10 kV distribution line based on electromagnetic return-stroke model using finite-difference time-domain

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High Voltage 2024年第2期9卷 356-366页

作者： Pan duan Lianfang Zhang xiaogang Huang Jian Sun Yue Qi Qing Yang School of Automation Chongqing University of Posts and TelecommunicationsChongqingChina Chongqing Power Co Tongnan BurChongqingChina China Southern Power Grid Science Research Institute GuangzhouChina State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina

Accurate simulation of lightning-induced overvoltage for overhead distribution lines is helpful to prevent lightning trip *** electromagnetic return-stroke model was used to represent lightning and then a 3D finite-difference time-domain(FDTD)method was adopted to simulate the lightning-induced overvoltage on a distribution line without a field-line coupling *** lightning-induced overvoltage behave for different ground conductivity and varying distance between the distribution line and the lightning channel was *** results showed that the overvoltage waveforms at the centre point of the line corresponding to lightning strikes on the lossy ground and an ideal ground(σ=∞)were similar;however,the peak amplitudes of the waveform were affected by soil conductivity at a close *** relationship between magnitude of the overvoltage and distance can be described by a second-order exponential decay ***,the overvoltage calculated using the proposed model was compared with those obtained based on Agrawal's model and measurements made using the newly developed intelligent insulator on *** these comparisons,it could be concluded that the FDTD method with the electromagnetic return-stroke model produces reasonably accurate results of the attenuated oscillation waveform,which can better reproduce the overvoltage on operational distribution lines.

关键词： lightning distribution return

模糊PID双层参数整定及其在固化炉中的应用

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重庆大学学报（自然科学版） 2018年第1期41卷 78-87页

作者：沈平段小刚中南大学高性能复杂制造国家重点实验室长沙410083

提出了一种模糊PID(proportion integration differentiation)控制器的双层参数整定方法。将模糊PID控制器的参数整定分为比例因子的整定与模糊隶属度函数参数整定2部分。推导出模糊PID控制器的解析模型,该解析模型包括线性部分和非线... 详细信息

提出了一种模糊PID(proportion integration differentiation)控制器的双层参数整定方法。将模糊PID控制器的参数整定分为比例因子的整定与模糊隶属度函数参数整定2部分。推导出模糊PID控制器的解析模型,该解析模型包括线性部分和非线性补偿2个部分。整定的过程中,把模糊PID控制器解析模型的非线性补偿看作过程扰动,由线性部分和被控对象的二阶纯时滞模型,基于系统的增益裕度关系,导出模糊PID控制器的比例因子。再基于粒子群优化算法(PSO,particle swarm optimization)对三角隶属度函数进行优化,使控制器进一步适应被控对象的动态特性。仿真结果表明了研究方法的有效性以及应用在芯片固化炉的温度控制过程中,提升温度控制的效果。

关键词：模糊PID 参数整定增益裕度 PSO

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简单随机抽样中的“虚拟普查”技术

应用概率统计 2023年第6期39卷 802-812页

作者：段小刚北京师范大学统计学院北京100875

简单随机抽样,包括有无放回两种形式,是最基础的抽样设计.本文基于“虚拟普查”想法,对简单估计量的抽样方差给出了新的计算思路,并揭示了有无放回简单随机抽样之间的内在联系.“虚拟普查”想法的核心在于虚拟普查矩阵.该矩阵记录了逐... 详细信息

简单随机抽样,包括有无放回两种形式,是最基础的抽样设计.本文基于“虚拟普查”想法,对简单估计量的抽样方差给出了新的计算思路,并揭示了有无放回简单随机抽样之间的内在联系.“虚拟普查”想法的核心在于虚拟普查矩阵.该矩阵记录了逐一抽取的无放回简单随机抽样,假设拓展为普查时--“虚拟普查”名称的由来,所有总体单元的入样轨迹.论文构建的“虚拟普查”技术框架,可以看作已有对称化论证方法和以入样指示变量为工具的论证方法的融合,对增进理解传统抽样策略,看起来具有潜在价值.作为示例,论文针对实践中常用的两个抽样策略,有放回不等概抽样和自适应整群抽样,给出了基于简单随机抽样的解读视角.

关键词：自适应抽样虚拟扩充多元超几何分布与规模成比例抽样概率对称性

贝叶斯模型平均及其在北京降雨预报中的一个应用

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北京师范大学学报（自然科学版） 2016年第2期52卷 134-138页

作者：段小刚曹伟华北京师范大学统计学院北京100875 中国气象局北京城市气象研究所北京100089

贝叶斯模型平均(Bayesian Model Averaging:BMA)是动态建模中融合集合预报信息的一种重要统计后处理方法.本文首先系统论述了BMA的建模分析过程,包括模型架构、参数估计方法、训练期的选择准则以及典型预报分布的抽样原理.然后,结合北京... 详细信息

贝叶斯模型平均(Bayesian Model Averaging:BMA)是动态建模中融合集合预报信息的一种重要统计后处理方法.本文首先系统论述了BMA的建模分析过程,包括模型架构、参数估计方法、训练期的选择准则以及典型预报分布的抽样原理.然后,结合北京市2011年5—8月份逐日累积降雨量实例,我们详细描述了BMA的实现过程.实例分析结果表明,BMA统计后处理,无论是精度还是校准度,相对于原始集合预报都有优势.

关键词：集合预报统计后处理混合模型 EM算法抽样分布累积降雨量