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Joint Analysis of Recurrent Event Data with a Dependent Terminal Event

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Journal of Systems Science & Complexity 2017年第6期30卷 1443-1458页

作者： YE peng DAI Jiajia ZHU jun School of Statistics University of International Business and Economics School of Mathematics and Statistics Guizhou University Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences

Recurrent event data frequently occur in many longitudinal studies, and the observation on recurrent events could be stopped by a terminal event such as death. This paper considers joint modeling and analysis of recurrent event and terminal event data through a common subject-specific frailty, in which the proportional intensity model is used for modeling the recurrent event process and the additive hazards model is used for modeling the terminal event time. Estimating equation approaches are developed for parameter estimation and asymptotic properties of the resulting estimators are established. In addition, some procedures are presented for model checking. The finite sample behavior of the proposed estimators is evaluated through simulation studies, and an application to a heart failure study is provided.

关键词： Additive hazards model estimating equation frailty recurrent events terminal event

Modeling of flow and debris ejection in blasting erosion arc machining in end milling mode

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Advances in Manufacturing 2020年第4期8卷 508-518页

作者： Ji-peng Chen Lin Gu wan-Sheng Zhao Mario Guagliano School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037People's Republic of China Department of Mechanical Engineering Polytechnic University of MilanPiazza Leonardo da Vinci32MilanItaly State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240People's Republic of China

Blasting erosion arc machining(BEAM)is a typical arc discharge machining technology that was developed around 2012 to improve the machinability of difficult-to-cut *** milling BEAM has been successfully developed and preliminarily applied in ***,owing to the high complexity of the flow field and the difficulty of observing debris in the discharge gap,studies of the flow and debris in end milling BEAM are *** this study,fluid dynamics simulations and particle tracking are used to investigate the flow characteristics and debris ejection processes in end milling ***,the end milling BEAM m o d e is *** the numerical modeling parameters,geometric models,and simulation methods are presented in ***,the flow distribution and debris ejection are described,analyzed,and *** velocity and pressure distributions of the axial feed and radial feed are observed;the rotation speed and milling depth are found to have almost no effect on the flow velocity ***,debris is ejected more rapidly in the radial feed than in the axial *** particle kinetic energy tends to increase with increasing milling depth,and smaller particles are more easily expelled from the flushing *** study attempts to reveal the flow field properties and debris ejection mechanism of end milling BEAM,which will be helpful in gaining a better understanding of BEAM.

关键词： Modeling Flow Debris ejection Blasting erosion arc machining(BEAM) End milling

A Facile Strategy for Intrinsic Low-Dk and Low-Df Polyimides Enabled by Spirobifluorene Groups

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Chinese Journal of Polymer Science 2023年第2期41卷 288-296页

作者： wan-Yi Tan Ling-Feng Jian Wei-peng Chen Yong-Wen Zhang Xiao-Chuang Lu wan-jun Huang Ji-Sheng Zhang Jing-Wu Wu jun-Li Feng Yi-Dong Liu Ting-Ting Cui Yong-Gang Min Guangdong University of Technology(GDUT) Guangzhou510006China Huimai Materials Technology(Guangdong)Co. Ltd.Foshan528200China Shenzhen Customs Industrial Product Inspection Technology Center Shenzhen518026China

Modified polyimides(MPIs)show great potential towards 5G communication applications,due to its excellent thermal stability,mechanical property and chemical stability as compared to most of *** fluoride groups or porous structure is favorable to ultra-low dielectric constant(D_(k))and dielectric loss(D_(f)).However,the cost of the fluorinated MPIs is high and their synthetic processes are complicated,and porous MPIs suffer poor mechanical ***,increasing the fraction of free volume is a very effective way to lower D_(k)through introducing more ultra-low-D_(k)air ***,most of this kind of MPIs lag far behind the fluorinated MPIs and the porous MPIs in terms of ultra-low D_(f),hindering the application of MPIs in high-speed communication ***,it is highly desirable to develop intrinsic ultra-low-D_(k)/D_(f)MPIs at high frequency with less fluoric groups and nonporous ***,we introduce a facile and effective strategy to lower D_(k)and D_(f)through introducing rigid and large sterically hindered aromatic groups into *** the one hand,their large steric hindrance effect leads to low D_(k)by increasing intrinsic free *** the other hand,the resulting highly stiff polymer chain and strong intermolecular interaction are favorable to reduce D_(f)by inhibiting dipole *** on this strategy,the spirobifluorene groups are *** as-prepared MPIs show excellent dielectric performance with low D_(k)of 2.74–2.76 and low D_(f)of 0.00599 at 10 GHz,to some extent,exceeding the multiple fluorinated MPI with D_(k)/D_(f)of 2.67/0.00663 at 10 GHz.

关键词： Polyimide High speed communication Low dielectric constant Low dielectric loss

Recent advances in the synthesis and fabrication methods of high-entropy alloy nanoparticles

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Journal of Materials Science & Technology 2024年第11期178卷 226-246页

作者： Wenqiang wan Kaiming Liang pengyu Zhu peng He Shuye Zhang State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Chongqing Research Institute Harbin Institute of TechnologyChongqing 401135China

High-entropy alloy nanoparticles(HEA NPs)containing four or more elements possess several advantages over traditional alloy nanoparticles(NPs),such as higher strength,greater thermal stability,enhanced ox-idation resistance,stronger catalytic activity,and greater flexibility in adjusting element composition and composition ***,the development of HEA NPs has been limited by preparation difficulties caused by the challenge of achieving complete miscibility between multiple-component elements and the unique high-entropy *** this review,we provide a comprehensive summary of recent break-throughs in synthesizing and fabricating HEA *** describe the experimental procedures and princi-ples of various synthesis methods,including furnace pyrolysis,carbothermal shock(CTS)method,pulse laser,solvothermal method,microwave heating,hydrogen spillover-driven,sputtering deposition,anneal-ing on mesoporous materials,arc discharge methods and using liquid ***,we delve into recent improvements made to some of these methods or novel NPs synthesized using ***,we review the current applications of HEA NPs and provide insights into potential applications of this rapidly emerging research field.

关键词： High-entropy alloy nanoparticles Synthesis methods Application

Self-adaptive Processing and Forecasting Algorithm for Univariate Linear Time Series

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Chinese Journal of Electronics 2017年第6期26卷 1147-1153页

作者： LIU Shufen GU Songyuan peng jun College of Computer Science and Technology Jilin University

As the Box-Jenkins method could not grasp the non-stationary characteristics of time series exactly, nor identify the optimal forecasting model order quickly and precisely, a self-adaptive processing and forecasting algorithm for univariate linear time series is proposed. A self-adaptive series characteristic test framework which employs varieties of statistic tests is constructed to solve the problem of inaccurate identification and inadequate processing for non-stationary characteristics of time series. To achieve favorable forecasts, an optimal forecasting model building algorithm combined with model filter and candidate model pool is proposed, in which a univariate linear time series forecasting model is built. Experimental data demonstrates that the proposed algorithm outperforms the comparative method in all forecasting performance statistics.

关键词： Time series Self-adaptivity Unit root Autoregressive moving average(ARMA)

Estimation of the accumulation rates and health risks of heavy metals in residential soils of three metropolitan cities in China

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Journal of Environmental Sciences 2022年第5期34卷 149-161页

作者： Chi peng Kai Zhang Meie wang Xinxing wan Weiping Chen Institute of Environmental Engineering School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083China State key laboratory of urban and regional ecology Research center for eco-environmental sciencesChinese academy of sciencesBeijing 100085China Third Xiangya Hospital Central South UniversityChangsha 410013China

Heavy metal concentrations in urban soils are likely to increase over time because of contin-uous urbanization and heavy metal *** estimate the accumulation rates of heavy metals in urban soils,we collected soil samples from residential areas with different build-ing ages in the metropolitan cities of Shanghai,Shenzhen,and Beijing,*** metal concentrations in the soils varied among the cities and were primarily affected by soil parent material and the intensity of anthropogenic *** analyses revealed that the accumulation rates of Cd and Cu in the soils ranged from 0.0034 to 0.0039 mg/(kg·year)and 0.343 to 0.391 mg/(kg·year),respectively,and were similar across the three cities,while ac-cumulation rates of Zn and Pb in Shanghai were higher than those in Shenzhen and *** higher accumulation rates of Zn and Pb in Shanghai can be explained by differences in city history and industrial structures among the *** soils with high health risks posed by the heavy metals were mostly collected from old towns of Shanghai because of high Pb content in the *** recent urbanization resulted in elevated concen-trations of Cd,Cu,Zn,and Pb in the residential soils,the effect on the total health risks of residents exposed to the soils was negligible.

关键词： Urbanization Urban soil Health risk assessment Building age Regression model Source analysis

In-situ nanoscale insights into the evolution of solid electrolyte interphase shells:revealing interfacial degradation in lithium metal batteries

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Science China Chemistry 2021年第5期64卷 734-738页

作者： Yang Shi Gui-Xian Liu Jing wan Rui Wen Li-jun wan Key Laboratory of Molecular Nanostructure and Nanotechnology Beijing National Laboratory for Molecular SciencesCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of the Chinese Academy of Sciences Beijing 100049China

The solid electrolyte interphase(SEI)has caught considerable attention as a pivotal factor affecting lithium(Li)metal battery ***,the understanding of the interfacial evolution and properties of the on-site formed SEI shells on Li deposits during cycling is still at a preliminary ***,we provide a straightforward visualized evidence of SEI shells’evolution during Li deposition/stripping to reveal anode degradation via in-situ atomic force microscopy(AFM).Nucleation and growth of quasi-spherical Li particles are observed on a Cu substrate,followed by Li stripping and collapse of SEI *** the subsequent cycling,new Li deposits tend to nucleate at pristine sites with fresh SEI shells forming on *** previously collapsed SEI shells accumulate to increase interface impedance,eventually leading to capacity *** the electrochemical processes and interfacial degradation at the nanoscale will enrich fundamental comprehension and further guide improvement strategies of Li metal anodes.

关键词： solid electrolyte interphase shell lithium deposition and stripping interfacial degradation lithium metal battery

ICE optimization strategies of hard carbon anode for sodium-ion batteries:from the perspective of material synthesis

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Materials Futures 2024年第3期3卷 28-53页

作者： Huanbin Zheng jun Zeng Xuanhong wan Xin Song Chenxi peng Jiarui wang Luyi Sun Hui wang Min Zhu jun Liu School of Materials Science and Engineering Guangdong Provincial Key Laboratory of Advanced Energy Storage MaterialsSouth China University of TechnologyGuangzhou 510641People’s Republic of China

With the continuous exploration of researchers in the field of sodium-ion batteries,the performance of these batteries has been greatly improved,and they have a wide range of application prospects in large-scale energy storage,traffic power and other *** carbon is the most important anode material for sodium-ion *** it has the advantages of low cost,stable structure and performance,it still has the problems of low initial Coulombic efficiency(ICE)and poor rate performance in *** order to solve the problem of low ICE of hard carbon anode in sodium-ion batteries,in recent years the literature about hard carbon anode in sodium-ion batteries has been comprehensively *** on the microstructure of hard carbon material,the causes of low ICE of hard carbon are *** the same time,from the point of view of material structure design and regulation,the current optimization strategies of hard carbon anode ICE are summarized,including the following aspects:optimization and improvement of the carbonization process,precursor screening and design,surface coating strategy,micro-pore structure control,catalytic carbonization *** hope that this review will provide reference for further optimization of hard carbon properties and its large-scale application in sodium-ion batteries.

关键词： sodium-ion batteries anode materials hard carbon initial Coulombic efficiency

One-step electrodeposition synthesis of bisphosphonate loaded magnesium implant:A strategy to modulate drug release for osteoporotic fracture healing

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Journal of Materials Science & Technology 2021年第19期78卷 92-99页

作者： peng wan Weidan wang Lizhen Zheng Ling Qin Ke Yang School of Materials Science and Engineering Dongguan University of TechnologyDongguan523808China Li Ka Shing Institute of Health Sciences Department of Orthopaedics and TraumatologyThe Chinese University of Hong KongHong KongChina Department of Orthopaedics Affiliated Zhongshan Hospital of Dalian UniversityDalian116001China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

Osteoporotic fracture with increase of aging population became an urgent orthopedic *** were widely recommended as effective clinical treatment *** of biodegradable Mg-based implants and merits of bisphosphonates was suggested for osteoporotic fracture *** the mild and sustained drug release,a novel one-step electrodeposition synthesis of drug loaded coating was proposed in this *** comparison to conventional soaking method,encapsulated zoledronate coating by one-step electrodeposition method could modulate drug release in first diffusion-controlled and later degradation-controlled *** in vitro cell response to zoledronate loaded coating showed enhanced proliferation and osteogenic differentiation of osteoblasts and no significant inhibition on osteoclasts,which could improve bone-forming and decrease bone resorption due to osteoporosis.

关键词： Bisphosphonate Magnesium Coating Electrodeposition Osteoporosis