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Efficient Estimation of Longitudinal Data Additive Varying Coefficient Regression Models

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Acta Mathematicae Applicatae Sinica 2017年第2期33卷 529-550页

作者： Shu liu School of Statistics and Information Shanghai University of International Business and Economics Shanghai 201620 China School of Statistics and Management Shanghai University of Finance and Economics Shanghai 200433 China

we consider a longitudinal data additive varying coefficient regression model, in which the coef- ficients of some factors （covariates） are additive functions of other factors, so that the interactions between different factors can be taken into account effectively. by considering within-subject correlation among repeated measurements over time and additive structure, we propose a feasible weighted two-stage local quasi-likelihood estimation. In the first stage, we construct initial estimators of the additive component functions by b-spline se- ries approximation. with the initial estimators, we transform the additive varying coefficients regression model into a varying coefficients regression model and further apply the local weighted quasi-likelihood method to estimate the varying coefficient functions in the second stage. The resulting second stage estimators are com- putationally expedient and intuitively appealing. They also have the advantages of higher asymptotic efficiency than those neglecting the correlation structure, and an oracle property in the sense that the asymptotic property of each additive component is the same as if the other components were known with certainty. Simulation studies are conducted to demonstrate finite sample behaviors of the proposed estimators, and a real data example is given to illustrate the usefulness of the proposed methodology.

关键词： additive vary-coefficient model longitudinal data modified Cholesky decomposition withinsubject correlation

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Mg-Li ALLOY wITH Ca ADDITION

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 355-361页

作者： H.b. Li G. C. Yao Z.Q. Guo Y.H. liu H.J. Yu H.b. Ji School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China

Mg-9wt%Li-2wt%Zn alloy was prepared and studied in this article. The addition of Ca to the alloy from 0.1wt% to 1wt% can refine the α-Mg and the best effect of refinement occurs when Ca content is 0.4wt%-0.5wt%. The billets can be rolled to thin sheets at room temperature, from which it is obvious that the addition of Ca improves alloys ormalin. while it decreases with the excess addition of Ca. The results also show that the ultimate tensile strength （UTS） and yield strength （YS） of the alloy with lwt% Ca may rise by 28% and 25%, respectively, however, the elongation decreases. It is clarified that the adsorption of proper Ca on the grain boundaries refines α-Mg and improves the tensile properties, but the presence of excess Ca and stable Ca2Mg6Zn3phase worsens the elongation.

关键词： calcium Mg-Li-Zn alloy cold rolling microstructure tensile property

STUDY OF THE ATOMIZED FLOw IN HYDRAULIC ENGINEERING

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Journal of Hydrodynamics 1999年第2期11卷 77-83页

作者： liu, Shihe wuhan Univ of Hydraulic and Electric Engineering Wuhan China

Atomized flow widely exists in hydraulic engineering. A mathematical model was suggested for the atomized flow by the overflow flip bucket. The following problems have been considered: the hydraulic characteristics of atomized jet; the quantity of the atomized water; and the lateral diffusion of the atomized flow. by comparing the calculating results by the model with that of the prototype observation of wujiangdu hydropower station, it is found that the model has fairly good predictive ability.

关键词： Atomization Hydraulic structures Jets Mathematical models Multiphase flow Numerical analysis

Asymptotic Normality of LS Estimate in Simple Linear EV Regression Model

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Chinese Annals of Mathematics,Series b 2006年第6期27卷 675-682页

作者： Jixue liu School of Mathematical Sciences Peking University Beijing 100871 China

Though EV model is theoretically more appropriate for applications in which measurement errors exist, people are still more inclined to use the ordinary regression models and the traditional LS method owing to the difficulties of statistical inference and computation. So it is meaningful to study the performance of LS estimate in EV model. In this article we obtain general conditions guaranteeing the asymptotic normality of the estimates of regression coefficients in the linear EV model. It is noticeable that the result is in some way different from the corresponding result in the ordinary regression model.

关键词： EV model LS estimate Asymptotic normality

Piezo1-targeted aerosol inhalation nanoparticles for acute lung injury

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Journal of Materials Science & Technology 2023年第10期141卷 21-31页

作者： Xinxin liu Xuwei Ling Jiachen He Xingzhi liu Lin wang Huiling liu Chang liu Yi wang Xiao Lin Chunhua Ling Qin Shi Department of Respiratory Medicine the First Affiliated Hospital of Soochow UniversitySuzhou 215031China Department of Respiratory and Critical Care Medicine The First Affiliated Hospital of Gannan Medical University/Gannan Branch of National Clinical Research Center for GeriatricsGanzhou 341000China Department of Orthopedics the First Affiliated Hospital of Soochow UniversityOrthopedic Institute of Soochow UniversitySuzhou 215031China School of Nano-Tech and Nano-bionics University of Science and Technology of ChinaSuzhou 215123China University of Science and Technology of China Hefei 230026China National Clinical Research Center for Hematologic Diseases the First Affiliated Hospital of Soochow UniversitySuzhouJiangsu 215031China

Inhaled drug-containing nanocarriers have been well applied as an important strategy in pulmonary *** lung injury(ALI)is characterized by abnormal lung tension and complex pathogenesis,with high mortality because of the limitations of targeted ***,in the present study,we first identified that the mechanosensitive ion channel Piezo1 participated in the ALI-associated processes induced by lipopolysaccharide(LPS)in vitro and in ***,chitosan-stabilized bovine serum albu-min nanoparticles(NCs)emulsified with the Piezo1 inhibitor GsMTx4(NC-GsMTx4)were generated and exhibited excellent biocompatibility and biological *** aerosol inhalation,NC-GsMTx4 im-proved lung injury and inhibited cell apoptosis in LPS-stressed ALI mice and alleviated pulmonary fibrosis during the later stage of ***,GsMTx4 could regulate inflammation and apoptosis in lung epithelial cells via NF-κb and ERK1/2 *** summary,our findings provide new insights into the pathological mechanisms of Piezo1 in ALI progression,and nebulized inhalation of NC-GsMTx4 offers a prospective platform for targeting Piezo1 to treat ALI efficiently and conveniently.

关键词： Acute lung injury Piezo1 Nanoparticle carrier NF-κb ERK1/2 GsMTx4

Microstructure and Tribological Properties of Fe-Cr-b-Si-based Alloy Coating on the Surface of Scraper Conveyor Middle Trough NM450

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Journal of wuhan University of Technology(Materials Science) 2020年第5期35卷 967-972页

作者： LI Junxia ZHANG Hongyu ZHANG Hongbin YANG Xiaobing ZHANG wei liu Libo College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China Shandong Province Key Laboratory of Mine Mechanical Engineering Shandong University of Science and TechnologyQingdao 266590China JMC Heavy Duty Vehicle Co. LtdTaiyuan 030024China

This paper aims to develop a surface modification process to improve the surface properties of the middle *** coatings were prepared by plasma cladding with Fe-Cr-b-Si-based alloy powders (Ig 6 and Ig7).The organizational structure and micro-hardness of the coatings were analyzed by laboratory *** friction and wear tests were performed to investigate the friction-wear properties of middle *** coatings have higher hardness and good friction-wear properties than the *** hardness and friction wear properties of the coating with Ig7 powder are better than those with Ig6 *** experimental results show that the surface properties of the middle trough are improved by Fe-Cr-b-Si-based alloy coating,which can improve the middle trough service *** plasma cladding can be widely used in the surface-modification of middle trough to reduce the waste of resources.

关键词： plasma cladding coating NM450 substrate alloy powders friction/wear micro-structure

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冻融循环下低液限盐渍化粉土力学特性研究

地下空间与工程学报 2024年第4期20卷 1223-1235页

作者：包卫星秦川李伟刘亚伦陈锐长安大学公路学院西安710064

为了研究冻融作用对低液限盐渍化粉土强度的影响,对不同初始含水率低液限盐渍化粉土进行冻融循环试验后,开展不固结不排水(UU)剪切和扫描电镜(SEM)试验,从宏微观角度揭示低液限盐渍化粉土强度的劣化机理。结果表明:未冻融时,含水率的改... 详细信息

为了研究冻融作用对低液限盐渍化粉土强度的影响,对不同初始含水率低液限盐渍化粉土进行冻融循环试验后,开展不固结不排水(UU)剪切和扫描电镜(SEM)试验,从宏微观角度揭示低液限盐渍化粉土强度的劣化机理。结果表明:未冻融时,含水率的改变不会引起低液限盐渍化粉土应力-应变曲线形态发生变化,均表现为软化型;在冻融作用下,含水率小于14%时试件的曲线形态不会发生改变,呈现软化型,高含水率的试件其应力-应变曲线形态会向着硬化性转变;通过分析冻融和含水率与破坏强度的关系,发现低液限盐渍化粉土破坏强度随含水率的提高呈现线性衰减,破坏强度随冻融循环次数的增加呈现指数型衰减,前3次冻融过程中破坏强度的衰减速率和幅度最大,随后趋于稳定;随着围压的增大,试件的应力-应变曲线会由软化型向硬化型过渡;在微观结构方面,冻融作用会改变土颗粒之间的接触形式,造成孔隙和裂隙的发育,冻融过程中微观结构的变异规律和宏观力学指标的劣化具有一致性。结合土体损伤力学,构建了冻融作用下的低液限盐渍化粉土黏聚力损伤劣化模型,冻融过程中的劣化度符合双曲线关系,最终劣化度A_(c)与含水率呈指数型关系,劣化速率b_(c)与含水率呈线性关系。

关键词：低液限盐渍化粉土冻融循环力学性质劣化模型微观结构

Effect of Heat Treatment Time on Dy–Cu Alloy Diffusion Process in Dy-Containing Commercial Nd–Fe–b Sintered Magnets

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 496-502页

作者： H.Y.liu G.wang Y.Hong D.C.Zeng School of Materials Science and Engineering South China University of Technology

In this paper, the grain boundary diffusion process（GbDP） using a Dy70Cu30（at.%） alloy as the diffusion source was performed in a commercial sintered Nd–Fe–b magnet, and the effect of heat treatment time on the microstructure and magnetic properties of the magnet was investigated in detail. For the processed magnets heat-treated at 860℃, as heat treatment time increased, the coercivity and the depth of（Nd,Dy）2Fe14b core–shell structure increased first and then decreased. However, when the heat treatment time was more than 2 h, the diffusion path of Dy from the Dy-rich shell phase into the Nd2Fe14b grains was revealed, and a nearly homogeneous（Nd,Dy）2Fe14b phase was formed, which brought on the decrease in both the depth of visible core–shell structure and the coercivity of Nd–Fe–b magnet.

关键词： Sintered Nd-Fe-b magnets Grain boundary diffusion Heat treatment time Coercivity Micromagnetic simulation

双模板剂调控SAPO-34对1-丁烯催化裂解的影响

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工业催化 2024年第2期32卷 34-41页

作者：杨哲旭柳娜西安科技大学化学与化工学院陕西西安710054 自然资源部煤炭资源勘查与综合利用重点实验室陕西西安710054

利用水热合成法,通过调控模板剂吗啡啉和四乙基氢氧化铵物质的量比[n(MOR)∶n(TEAOH)]合成出不同SAPO-34分子筛。采用XRD、SEM、NH_(3)-TPD等测试方法对合成样品进行表征,并考察其在1-丁烯催化裂解制丙烯反应中的催化性能。结果表明,双... 详细信息

利用水热合成法,通过调控模板剂吗啡啉和四乙基氢氧化铵物质的量比[n(MOR)∶n(TEAOH)]合成出不同SAPO-34分子筛。采用XRD、SEM、NH_(3)-TPD等测试方法对合成样品进行表征,并考察其在1-丁烯催化裂解制丙烯反应中的催化性能。结果表明,双模板剂相比单模板剂制得的SAPO-34分子筛具有不同的酸性和颗粒尺寸,适宜的[n(MOR)∶n(TEAOH)]可以协同SAPO-34分子筛有更弱的酸强度和b酸酸位,从而抑制裂解过程中氢转移反应的发生。当n(MOR)∶n(TEAOH)=2.0∶0.5时可以最大程度的提升丙烯产率和选择性,在1-丁烯催化裂解制丙烯中具有最高的丙烯产率和丙烯选择性,分别为37.03%和45.78%,可以有效应用于1-丁烯催化裂解反应。

关键词：催化剂工程催化裂解丙烯 1-丁烯 SAPO-34 吗啡啉四乙基氢氧化铵