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Semiparametric Quantile Modelling of Hierarchical Data

Acta Mathematica Sinica,English Series 2009年第4期25卷 597-616页

作者： Mao Zai TIAN man Lai TANG ping Shing CHAN School of Statistics Renmin University of China Beijing 100872 P. R. China Center for Applied Statistics Renmin University of China Beijing 100872 P. R. China Department of Mathematics Hong Kong Baptist University Kowloon Hong Kong Department of Statistics The Chinese University of Hong Kong Shatin N.T. Hong Kong

The classic hierarchical linear model formulation provides a considerable flexibility for modelling the random effects structure and a powerful tool for analyzing nested data that arise in various areas such as biology, economics and education. However, it assumes the within-group errors to be independently and identically distributed （i.i.d.） and models at all levels to be linear. Most importantly, traditional hierarchical models （just like other ordinary mean regression methods） cannot characterize the entire conditional distribution of a dependent variable given a set of covariates and fail to yield robust estimators. In this article, we relax the aforementioned and normality assumptions, and develop a so-called Hierarchical Semiparametric Quantile Regression Models in which the within-group errors could be heteroscedastic and models at some levels are allowed to be nonparametric. We present the ideas with a 2-level model. The level-1 model is specified as a nonparametric model whereas level-2 model is set as a parametric model. Under the proposed semiparametric setting the vector of partial derivatives of the nonparametric function in level-1 becomes the response variable vector in level 2. The proposed method allows us to model the fixed effects in the innermost level （i.e., level 2） as a function of the covariates instead of a constant effect. We outline some mild regularity conditions required for convergence and asymptotic normality for our estimators. We illustrate our methodology with a real hierarchical data set from a laboratory study and some simulation studies.

关键词： hierarchical models quantile regression robustness

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Coordinating EV Charging via Blockchain

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Journal of Modern Power Systems and Clean Energy 2020年第3期8卷 573-581页

作者： Jian ping Zheng Yan Sijie Chen Liangzhong Yao Minhui qian Department of Electrical Engineering School of Electronics Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghaiChina School of Electrical Engineering and Automation Wuhan UniversityWuhanChina China Electric Power Research Institute BeijingChina

The increasing electric vehicle(EV) penetration in a distribution network triggers the need for EV charging coordination. This paper firstly proposes a hierarchical EV charging coordination model and an algorithm based on Lagrangian relaxation. A barrier to the implementation of the coordination algorithm is that there usually does not exist a reliable coordinator of charging stations. This paper shows that an unreliable coordinator may collude with some charging stations and behave dishonestly by disobeying the coordination algorithm. Thus, the collusion coalition can gain more profits while lowering the profits of others and the total social welfare. To provide reliable coordination of charging stations, a novel blockchain-based coordination platform via Ethereum is established, including a coordination structure and a smart contract. A mathematical analysis is given to show that the proposed platform can mitigate the collusion behaviors in the coordination. Simulation results show the consequence of collusion and how blockchain can prevent the collusion.

关键词： Electric vehicle(EV)charging coordination collusion blockchain smart contract

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Suspension Polymerization of Methyl Methacrylate Stabilized Solely by Palygorskite Nano Fibers

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Chinese Journal of Polymer Science 2014年第2期32卷 123-123,124-129页

作者：黎白钰 Yin-ping Wang Xiao-bin Niu Zai-man Liu The School of Chemical & Biological Engineering Lanzhou Jiaotong University

A kind of fibrous clay, palygorskite （PAL）, was used as the sole stabilizer in suspension polymerization without the using of any other stabilizer usually used, especially polymeric stabilizers. In order to improve the compatibility with the organic monomer, PAL nano fibers were organically modified with silane coupling agent methacryloxypropyltrimethoxysilane （MPS）. Transmission electron microscopy （TEM） and Fourier-transform infrared （FTIR） spectroscopy results show that the hydrolyzed MPS was attached onto PAL surface through Si--O--Si bonds formation without morphology change of PAL. At a loading amount of PAL to monomer as low as 0.36 wt%, effective stabilization could be achieved. After suspension polymerization, spherical poly（methyl methacrylate）（PMMA） particles were obtained. Scanning electron microscopy （SEM） analysis on both the outer surface and the inner cracked surface of the spherical PMMA particles indicates that the PAL particles reside on the surface of the PMMA spheres. The densely stacked PAL together with attached silane coupling agent stabilized the droplets throughout the suspension polymerization.

关键词： Palygorskite Attapulgite Clay Poly(methyl methacrylate) Suspension polymerization.

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DNA storage: research landscape and future prospects

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National Science Review 2020年第6期7卷 1092-1107页

作者： Yiming Dong Fajia Sun Zhi ping Qi Ouyang Long qian Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences Peking University Academician Workstation of BGI Synthetic Genomics BGI-Shenzhen The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics School of Physics Peking University

The global demand for data storage is currently outpacing the world’s storage capabilities. DNA, the carrier of natural genetic information, offers a stable, resource-and energy-efficient and sustainable data storage solution. In this review, we summarize the fundamental theory, research history, and technical challenges of DNA storage. From a quantitative perspective, we evaluate the prospect of DNA, and organic polymers in general, as a novel class of data storage medium.

关键词： DNA storage information compilation sequencing

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Light-Activated Virtual Sensor Array with Machine Learning for Non-Invasive Diagnosis of Coronary Heart Disease

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Nano-Micro Letters 2024年第12期16卷 427-448页

作者： Jiawang Hu Hao qian Sanyang Han ping Zhang Yuan Lu Department of Chemical Engineering Tsinghua UniversityBeijing 100084People’s Republic of China Key Laboratory of Industrial Biocatalysis Ministry of EducationTsinghua UniversityBeijing 100084People’s Republic of China Department of Cardiology Xuanwu HospitalCapital Medical UniversityBeijing 100053People’s Republic of China Department of Cardiology Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing 102218People’s Republic of China Institute of Biopharmaceutical and Health Engineering Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055People’s Republic of China

Early non-invasive diagnosis of coronary heart disease(CHD)is ***,it is challenging to achieve accurate CHD diagnosis via detecting *** this work,heterostructured complexes of black phosphorus(BP)and two-dimensional carbide and nitride(MXene)with high gas sensitivity and photo responsiveness were formulated using a self-assembly strategy.A light-activated virtual sensor array(LAVSA)based on BP/Ti_(3)C_(2)Tx was prepared under photomodulation and further assembled into an instant gas sensing platform(IGSP).In addition,a machine learning(ML)algorithm was introduced to help the IGSP detect and recognize the signals of breath samples to diagnose *** to the synergistic effect of BP and Ti_(3)C_(2)Tx as well as photo excitation,the synthesized heterostructured complexes exhibited higher performance than pristine Ti_(3)C_(2)Tx,with a response value 26%higher than that of pristine Ti_(3)C_(2)*** addition,with the help of a pattern recognition algorithm,LAVSA successfully detected and identified 15 odor molecules affiliated with alcohols,ketones,aldehydes,esters,and ***,with the assistance of ML,the IGSP achieved 69.2%accuracy in detecting the breath odor of 45 volunteers from healthy people and CHD *** conclusion,an immediate,low-cost,and accurate prototype was designed and fabricated for the noninvasive diagnosis of CHD,which provided a generalized solution for diagnosing other diseases and other more complex application scenarios.

关键词： Black phosphorus/MXene heterostructures Light-activated virtual sensor array Diagnosis of coronary heart disease Machine learning

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Ensemble projections of climate and streamflow in a typical basin of semi-arid steppes in Mongolian Plateau of 2021-2100

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Advances in Climate Change Research 2024年第2期15卷 230-243页

作者： Hang PAN Jian-ping TANG Liang CHENG man-Chun LI Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology Nanjing UniversityNanjing 210023China School of Geography and Ocean Science Nanjing UniversityNanjing 210023China Key Laboratory of Mesoscale Severe Weather/Ministry of Education Nanjing UniversityNanjing 210023China School of Atmospheric Sciences Nanjing UniversityNanjing 210023China

The Kherlen River is the main water source for Hulun Lake,the largest lake in northern *** to reduced inflow from the Kherlen River,Hulun Lake experienced rapid shrinkage at the beginning of the 21st century,posing a serious threat to the ecological security of northern ***,there is still a significant lack of projections regarding future climate change and its hydrological response in the Kherlen River *** study analyzed the projected climate and streamflow changes in the Kherlen River basin,a vital yet vulnerable international semi-arid steppes type basin.A combination of multi-model ensemble projection techniques,and the soil and water assessment tool(SWAT)model was employed to examine the spatio-temporal changes in precipitation,temperature,streamflow,and the associated uncertainties in the *** temperature(an increase of 1.84-6.42℃)and the precipitation(an increase of 15.0-46.0 mm)of Kherlen River basin are projected to increase by 2100,leading to a rise in streamflow(1.08-4.78 m^(3) s^(-1)).The upstream of the Kherlen River exhibits remarkable increasing trends in precipitation,which has a dominant influence on streamflow of Kherlen *** increases in streamflow are observed in April,August,September,and October compared to the reference period(1971-2000).These findings suggest a partial alleviation of water scarcity in the Kherlen River,but also an increased likelihood of hydrological extreme *** projected temperature increase in the Kherlen River basin exhibits the smallest uncertainty,while more pronounced uncertainties are found in precipitation and *** spread among the results of CMIP6 models is greater than that of CMIP5 models,with lower signal-to-noise ratio(SNR)values for temperature,precipitation,and streamflow.

关键词： Climate change Flow projection Uncertainty SWAT Mongolian Plateau

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Numerical simulation of water entry problems considering air effect using a multiphase Riemann-SPH model

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Advances in Aerodynamics 2021年第1期3卷 244-259页

作者： Zi-Fei Meng Fu-Ren Ming ping-ping Wang A-man Zhang College of Shipbuilding Engineering Harbin Engineering UniversityHarbinChina

The water entry is a classic fluid-structure interaction problem in ocean *** prediction of impact loads on structure during the water entry is critical to some engineering *** this paper,a multiphase Riemann-SPH model is developed to investigate water entry *** this model,a special treatment,a cut-off value for the particle density,is arranged to avoid the occurrence of negative pressure.A remarkable advantage of the present multiphase SPH model is that the real speed of sound in air can be allowed when simulating water-air *** the present work,considering the air effect,several typical water entry problems are studied,and the evolution of multiphase interface,the motion characteristic of structure and complex fluid-structure interactions during the water entry are *** with the experimental data,the present multiphase SPH model can obtain satisfactory results,and it can be considered as a reliable tool in reproducing some fluid-structure interaction problems.

关键词： Water entry Multiphase flow Fluid-structure interaction SPH Air effect

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Evaluation of Tensile and Fatigue Properties of Metals Using Small Specimens

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Acta Metallurgica Sinica(English Letters) 2023年第1期36卷 147-157页

作者： Wen‑Ke Yang Zhu‑man Song Xue‑Mei Luo Guang‑ping Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

Small specimens are increasingly being used in getting mechanical properties directly when there are limited materials to facilitate standard specimens,which play a great role in the rapid measurement of mechanical properties and residual life assessment of in-service reactor *** tensile and fatigue properties of the small specimens are investigated extensively,theoretical models for describing the mechanical properties of small specimens need to be ***,we conduct a systematic investigation of tensile and fatigue properties of pure Cu specimens with thicknesses ranging from 3 to 0.2 *** results show that the decrease in uniform elongation of the 0.2 mm-thick specimens is mainly due to the efects of grain boundary and free surface on the strain hardening rate.A modifed theoretical model correlated with the ratio of the surface grain layer thickness to the grain size is proposed to predict variation in yield strength of the small specimens more ***,the mechanism for the diference in fatigue life between the 0.2 mm-thick specimen and other thicker specimens is *** Basquin equation-based model is presented as a potential way to evaluate the fatigue life of metals using small specimens.

关键词： Size efect Small specimen Tensile property Fatigue life

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Molecular Hydrodynamics of the Moving Contact Line in Two-Phase Immiscible Flows

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Communications in Computational Physics 2006年第1期1卷 1-52页

作者： Tiezheng qian Xiao-ping Wang ping Sheng Department of Mathematics The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina Department of Physics The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

The no-slip boundary condition,i.e.,zero fluid velocity relative to the solid at the fluid-solid interface,has been very successful in describing many macroscopic flows.A problem of principle arises when the no-slip boundary condition is used to model the hydrodynamics of immiscible-fluid displacement in the vicinity of the moving contact line,where the interface separating two immiscible fluids intersects the solid *** ago it was already known that the moving contact line is incompatible with the no-slip boundary condition,since the latter would imply infinite dissipation due to a non-integrable singularity in the stress near the contact *** this paper we first present an introductory review of the *** then present a detailed review of our recent results on the contact-line motion in immiscible two-phase flow,from molecular dynamics(MD)simulations to continuum hydrodynamics *** extensive MD studies and detailed analysis,we have uncovered the slip boundary condition governing the moving contact line,denoted the generalized Navier boundary *** have used this discovery to formulate a continuum hydrodynamic model whose predictions are in remarkable quantitative agreement with the MD simulation results down to the molecular *** results serve to affirm the validity of the generalized Navier boundary condition,as well as to open up the possibility of continuum hydrodynamic calculations of immiscible flows that are physically meaningful at the molecular level.

关键词： Moving contact line slip boundary condition molecular dynamics continuum hydrodynamics

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The Chang’E-1 orbiter plays a distinctive role in China’s first successful selenodetic lunar mission

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Science China(Physics,Mechanics & Astronomy) 2011年第12期54卷 2130-2144页

作者： ping JinSong SU XiaoLi HUANG qian YAN JianGuo National Astronomical Observatory Chinese Academy of Sciences Beijing 100012 China Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China State Key Laboratory of lnformation Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430070 China

The first Chinese lunar orbiter Chang'E-1 is a successful mission with many fruitful results obtained in various disciplines. The scientific data acquired by the Chang'E-1 payloads can benefit studies of the lunar origin and evolution, as well as other relevant research areas, after careful validation of the data. Among the new results, the Chang'E-1 selenodetic products are continually uncovering characteristics of the lunar surface, undersurface and inner structure. Successful lunar orbiters such as the Clementine, Lunar Prospector, KAGUYA/SELENE, Chang'E-1, Lunar Reconnaissance Orbiter and GRAIL have been revealing, with increasing clarity, global selenodetic characteristics with state-of-the-art fine resolution and high precision. In particular, the Chang'E-1 plays an important distinctive role in selenodetic exploration through enhancing lunar topography and gravity models. The gravity model has been successfully improved with a factor of two after applying the Chang'E-1 long-wavelength tracking data. Using the new models, some medium-scale lunar surface characteristics such as basins and volcanoes have been identified. Furthermore, the old mascon basins of Bouguer, gravity anomaly and craters have been discovered with the Chang'E-1 selenodetic data.

关键词： Chang’E-1 lunar orbiter lunar science selenodesy topography gravity

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