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A New Classifier for Imbalanced Data Based on a Generalized Density Ratio Model

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Communications in Mathematics and Statistics 2023年第2期11卷 369-401页

作者： Junjun Li wenquan.cui Department of Statistics and Finance School of ManagementUniversity of Science and Technology of ChinaHefei 230026People’s Republic of China

Achieving higher true positive rate when decreasing false positive rate is always a great challenge to the imbalance learning *** work combines penalized empirical likelihood method,lower bound algorithm and Nyströmmethod and applies these techniques along with kernel method to density ratio *** resulting classifier,density ratio classifier(DRC),is a combination of kernelization,regularization,efficient implementation and threshold moving,all of which are critical to enable DRC to be an effective and powerful method for solving difficult imbalance *** with other methods,DRC is competitive in that it is widely applicable and it is simple and easy to use without additional imbalance handling *** addition,the convergence rate of the estimate of log density ratio is discussed as *** the results of numerical analysis also show that DRC outperforms other methods in AUC and G-mean score.

关键词： Classifier Density ratio model Imbalance problems Kernel method ROC curve

Correcting for biases in affected sib-pair linkage analysis caused by uncertainty in sibling relationship

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Science China Mathematics 2012年第6期55卷 1127-1135页

作者： YUAN Min cui wenquan YANG YaNing School of Mathematics University of Science and Technology of ChinaHefei 230026China Department of Statistics and Finance University of Science and Technology of ChinaHefei 230026China

When there is uncertainty in sibling relationship,the classical affected sib-pair(ASP) linkage tests may be severely *** can happen,for example,if some of the half sib-pairs are mixed with full *** genomic control method has been used in association analysis to adjust for population *** show that the same idea can be applied to ASP linkage analysis with uncertainty in sibling *** that,in addition to the candidate marker,null markers that are unlinked to the disease locus are also genotyped,we may use the information on these loci to estimate the proportion of half sib-pairs and to correct for the bias and variance distortion caused by the heterogeneity of sibling *** in association studies,the null loci are not required to be matched with the candidate marker in allele frequency for ASP linkage *** makes our approach flexible in selecting null *** our simulations,using a number of 30 or more null loci can effectively remove the bias and variance *** is also shown that,even the null loci are weakly linked to the disease locus,the proposed method can also provide satisfactory correction.

关键词： affected sib-pairs bias null marker half sib-pairs variance distortion identical-by-descent (IBD)

A simple construction of optimal estimation in multivariate marginal Cox regression

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Science China Mathematics 2012年第9期55卷 1827-1857页

作者： cui wenquan YING ZhiLiang ZHAO LinCheng Department of Statistics and Finance University of Science and Technology of China Hefei 230026 China Department of Statistics Columbia University New York NY 10027 USA

The multivariate extension of the Cox model proposed by Wei,Lin and Weissfeld in 1989 has been widely used for analyzing multivariate survival *** the model assumption,failure times from an individual are assumed to marginally follow their respective proportional hazards regression relation,leaving the joint distribution completely *** paper presents a simple approach to efficiency improvement through segmentation of stochastic integrals in the marginal estimating equations and incorporation of the limiting covariance *** is shown that when partition of the time interval is done at a suitable rate,the resulting estimator is consistent and asymptotically *** the reproducing kernel Hilbert space arising from the covariance function of the limiting Gaussian process,it is also shown that the proposed estimator is asymptotically optimal within a reasonable class of estimators under marginal *** are conducted to assess the finite-sample performance of the proposed method.

关键词： multivariate survival data marginal proportional hazards regression WLW method estimatingequations empirical processes martingale reproducing kernel Hilbert spaces limit theorem of reproducingkernels

Geodetic constraints on contemporary three-dimensional crustal deformation in the Laji Shan—Jishi Shan tectonic belt

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Geodesy and Geodynamics 2023年第6期14卷 589-596页

作者： wenquan Zhuang Duxin cui Ming Hao Shangwu Song Zhangjun Li The Second Monitoring and Application Center China Earthquake AdministrationXi'an 710054China

The Laji Shan—Jishi Shan tectonic belt(LJTB),located in the southern part of the northeastern Tibetan Plateau(NETP),is a tectonic window to reveal regional tectonic deformation in the ***,its kinematics in the Holocene remains *** obtain the latest and dense horizontal velocity field based on data collected from our newly constructed and existing GNSS *** with fault kinematics from geologic observations,we analyze the crustal deformation characteristics along the *** results show that:(1)The Laji Shan fault(LJF)is inactive,and the northwest-oriented Jishi Shan fault(JSF)exhibits a significant dextral and thrust slip.(2)The transpression along the arc-shaped LJTB accommodates deformation transformation between the dextral Riyue Shan fault and the sinistral west Qinling fault.(3)With the continuous pushing of the Indian plate,internal strains in the Tibetan Plateau are continuously transferred in the northeast via the LJTB as they are gradually dissipated near the LJTB and translated into significant crustal uplift in these regions.

关键词： Laji Shan-Jishi Shan tectonic belt Three-dimensional crustal deformation Fault slip rate GNSS Velocity field

Random weighting method for Cox’s proportional hazards model

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Science China Mathematics 2008年第10期51卷 1843-1854页

作者： cui wenquan LI Kai YANG YaNing WU YueHua Department of Statistics and Finance University of Science and Technology of ChinaHefei 230026China Department of Mathematics and Statistics York UniversityTorontoOntario M3J 1P3Canada

Variance of parameter estimate in Cox’s proportional hazards model is based on asymptotic variance. When sample size is small, variance can be estimated by bootstrap method. However, if censoring rate in a survival data set is high, bootstrap method may fail to work properly. This is because bootstrap samples may be even more heavily censored due to repeated sampling of the censored observations. This paper proposes a random weighting method for variance estimation and confidence interval estimation for proportional hazards model. This method, unlike the bootstrap method, does not lead to more severe censoring than the original sample does. Its large sample properties are studied and the consistency and asymptotic normality are proved under mild conditions. Simulation studies show that the random weighting method is not as sensitive to heavy censoring as bootstrap method is and can produce good variance estimates or confidence intervals.

关键词： bootstrap Cox model censoring rate random weighting consistency asymptotic normality 62N01 62N02 62N03 62F40 62G09

Corrosion Behavior of Pre-oxidized GH4169 Alloy with Solid NaCI Deposited in a Wet Oxygen Flow at 600 ℃

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Acta Metallurgica Sinica(English Letters) 2024年第7期37卷 1249-1264页

作者： Weidong Zhang Yu cui Li Liu wenquan Wang Wenzheng Chen Rui Li Fuhui Wang Shenyang National Laboratory for Materials Science Northeastern UniversityShenyang110819China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The corrosion behavior of the pre-oxidized GH4169 alloy was studied after 20 h of exposure under a solid NaCl deposit film in a wet O_(2) environment at 600℃ by mass-gain measurements,X-ray diffraction,scanning electron microscopy,transmission electron microscopy *** results indicate that the pre-oxidized GH4169 alloy undergoes serious corrosion in the corrosive *** preformed Cr_(2)O_(3) layer is gradually destroyed by deposit NaCl,and the inner Nb2O5 layer beneath the complete outer Cr_(2)O_(3) layer also reacts with NaCl to form NaNbO_(3).The electrochemical test results testified the existence of electrochemical reactions during this corrosion *** corrosion behavior of pre-oxidized GH4169 under a solid NaCl deposit film in a wet O_(2) environment at 600℃has been discussed in detail.

关键词： Pre-oxidation Solid NaCl Wet O2 Electrochemical corrosion

Enhancing electrical conductivity of single-atom doped Co_(3)O_(4) nanosheet arrays at grain boundary by phosphor doping strategy for efficient water splitting

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Nano Research 2022年第10期15卷 9511-9519页

作者： Yaohang Gu Xuanyu Wang Ateer Bao Liang Dong Xiaoyan Zhang Haijun Pan wenquan.cui Xiwei Qi School of Materials Science and Engineering Northeastern UniversityShenyang 110189China College of Metallurgy and Energy North China of Science and TechnologyTangshan 063210China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province Northeastern University at QinhuangdaoQinhuangdao 066004China College of Chemical Engineering Hebei Provincial Key Laboratory of Environmental Photocatalytic and Electrocatalytic MaterialsNorth China University of Science and TechnologyTangshan 063210China

High electrical conductivity guarantees a rapid electron transfer and thus plays an important role in *** particular,for the single atom catalysts(SACs),to facilitate interaction between the single atom and supports,precisely engineering the conductivity represents a promising strategy to design SACs with high electrochemical *** we show rhodium(Rh)SAC anchored on Co_(3)O_(4) nanosheets arrays on nickel foam(NF),which is modified by a facile phosphorus(P-doped Rh SACCo_(3)O_(4)/NF),possessing an appropriate electronic structure and high conductivity for electrocatalytic *** the introduction of P atom in the lattice,the electrocatalyst demonstrates outstanding alkaline oxygen evolution reaction(OER)activity with 50 mA·cm^(−2) under overpotential of 268 mV,6 times higher than that of Ir/C/*** interestingly,the P-doped Rh SAC-Co_(3)O_(4)/NF can get 50 mA·cm^(−2) at only 1.77 V for overall water *** electrical conductivity studies and density functional theory(DFT)calculations reveal that the high conductivity at grain boundary improves the charge transfer efficiency of the Rh catalytic ***,other noble-metal(Ir,Pd,and Ru)doped Co_(3)O_(4) nanosheets arrays are prepared to exhibit the general efficacy of the phosphorus doping strategy.

关键词： overall water splitting electrical conductivity single atom electrocatalyst phosphor doping strategy

Loading CuO on the surface of MgO with low-coordination basic O^(2-)sites for effective enhanced CO_(2) capture and photothermal synergistic catalytic reduction of CO_(2) to ethanol

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Chinese Journal of Chemical Engineering 2023年第9期61卷 58-67页

作者： Ting Li Hongxia Guo Xiao Wang Huan Wang Li Liu wenquan.cui Xiaoran Sun Yinghua Liang College of Chemical Engineering Hebei Key Laboratory for Environment Photocatalytic and Electrocatalytic MaterialsNorth China University of Science and TechnologyTangshan 063210China

The higher capacity of CO_(2)adsorption on the surface of magnesium oxide(MgO)with low-coordination O^(2-)sites would effectively enhance the catalytic reduction of CO_(2).Herein,a series of copper oxide(CuO)and MgO composites with different mass ratios have been prepared by hydrothermal method and used for photothermal synergistic catalytic reduction of CO_(2)to *** catalyst with CuO mass ratio of 1.6% shows the best yield(15.17μmol·g^(-1)·h^(-1))under 3 h Xenon lamp *** improved performance is attributable to the loose nano-sheet structure,uniform dispersion of active sites,the increased specific surface area,medium-strength basicity,the high separation efficiency of electrons and holes,and the formation of Mg-O-Cu *** synthesized CuO and MgO composites with loose nano-sheet structure facilitate the diffusion of reactants CO_(2),so an excellent CO_(2)adsorption performance can be ***,the introduction of CuO in the form of bivalence provides higher specific surface area and porosity,thus obtaining more active *** importantly,the Mg-O-Cu species make the donation of electrons from MgO to CO_(2)easier,resulting in the breaking of the old Mg-O bond and the formation of C-O bond,thus promoting the adsorption and conversion of CO_(2)to ethanol.

关键词： CO_(2)reduction Photothermal catalysis Ethanol MgO CuO

Construction of a Cu@hollow TS-1 nanoreactor based on a hierarchical full-spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

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Carbon Energy 2024年第2期6卷 25-36页

作者： Sixian Zhu Qiao Zhao Hongxia Guo Li Liu Xiao Wang Xiwei Qi Xianguang Meng wenquan.cui Hebei Key Laboratory for Environment Photocatalytic and Electrocatalytic Materials College of Chemical EngineeringNorth China University of Science and TechnologyTangshanChina School of Materials Science and Engineering National Institute for Advanced MaterialsTKL of Metal and Molecule-Based Material ChemistryNankai UniversityTianjinChina Hebei Iron and Steel Laboratory TangshanChina

The artificial photosynthesis technology has been recognized as a promising solution for CO_(2) *** catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and ***,strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently ***,a hierarchical full-spectrum solar light utilization strategy is *** on this strategy,a Cu@hollow titanium silicalite-1 zeolite(TS-1)nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high-efficiency photothermal catalytic artificial *** space-time yield of alcohol products over the optimal catalyst reached 64.4μmol g−1 h−1,with the selectivity of CH3CH2OH of 69.5%.This rationally designed hierarchical utilization strategy for solar light can be summarized as follows:(1)high-energy ultraviolet light is utilized to drive the initial and difficult CO_(2) activation step on the TS-1 shell;(2)visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps;and(3)low-energy near-infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier *** work provides some scientific and experimental bases for research on novel,highly efficient photothermal catalysts for artificial photosynthesis.

关键词： artificial photosynthesis full spectrum nanoreactors photothermal catalysis