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Existence for V T-harmonic maps from compact manifolds with boundary

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Science China Mathematics 2022年第11期65卷 2371-2378页

作者： Xiangzhi Cao Qun Chen School of Information Engineering Nanjing Xiaozhuang UniversityNanjing 211171China School of Mathematics and Statistics Wuhan UniversityWuhan 430072China

We consider a kind of generalized harmonic maps,namely,the V T-harmonic maps.We prove an existence theorem for the Dirichlet problem of V T-harmonic maps from compact manifolds with boundary.

关键词： Dirichlet problem existence harmonic map

A refined representation method of the particle size distribution curve based on grading entropy

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Particuology 2024年第5期88卷 302-311页

作者： Xing Li Qun Chen Zhaozhao Liu cheng Zhou chen Wang chen chen State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China

The particle size distribution(PSD)curve is an important expression of the basic properties of the soil.The characteristic parameters such as median particle size D 50,effective particle size D 10,and some combinations of characteristic parameters can only represent some points of the PSD curve,failing to represent all information of the PSD curve.In this paper,a fraction characteristic parameter F that could reflect the fraction size variation of the PSD curve was introduced based on grading entropy.And a new presentation method of the A-B-F three parameters was proposed for a refined representation of the PSD curve.It was found that the newly constructed model not only better represents the differences in the width of PSD curves but also has a higher sensitivity than the A-B two-parameter model proposed by Lőrincz.For PSD curves with similar distributions,the new presentation method has a higher degree of discrimination than that of the D 50-C u-C c three-parameter or the four-parameter combination G c proposed by Arshad.Finally,the application of this new method in describing the spatial nonuniformity distribution of depositions and predicting the soil hydraulic conductivity was discussed.The research results can provide a reference for the refined representation of PSD curves.

关键词： Grading entropy Particle size distribution curve Refined representation

Cause analysis of expressway traffic accidents based on accident statistics of Hunan provincial expressway in 2012-2018

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Transportation Safety and Environment 2024年第1期6卷 83-92页

作者： Xinyu Liu Shengjun Huang Qun Chen Business school Foshan UniversityFoshan 528225GuangdongChina School of Traffic and Transportation Engineering Central South UniversityChangsha 410075HunanChina Hunan Provincial Expressway Traffic Police Station Law Enforcement DepartmentChangsha 410007HunanChina

Based on the 2012–2018 accident statistics on the Hunan Provincial Expressway in China,this paper analyses the proportion to which various factors contribute to accidents,as well as the trends over time.From 2012 to 2018,the total number of general procedure handling accidents(i.***.major accidents)increased first and then decreased,while the number of accidents and deaths per 1000 kilometres decreased year by year.The total number of simple procedure handling accidents(i.***.minor accidents)increased year by year,but the number of accidents per 1000 kilometres remained relatively stable.Speeding,fatigued driving,improper driving operation,failure to maintain a safe distance from the preceding vehicle and pedestrians entering the expressway are the main causes of general procedure handling accidents.Failure to maintain a safe distance from the preceding vehicle as required and improper driving operation accounted for approximately 2/3 of the simple procedure handling accidents.In view of the accidents caused by these factors,how to use law enforcement,education,science and technology and facilities construction to further reduce the occurrence of expressway traffic accidents is discussed.

关键词： expressway traffic accident cause analysis

Bus passengers’anger scale and expression in anger-provoking situations

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Transportation Safety and Environment 2023年第1期5卷 18-30页

作者： Zhili Yuan Qun Chen Shi Ye School of Traffic and Transportation Engineering Central South UniversityChangsha 410075HunanChina.

This paper investigates the scale and expression of passengers’anger arising from disputes between drivers and passengers,and between passengers,by surveying a sample of 757 undergraduate students.The bus passengers’anger scale and expression inventory(BPASX),a newly-designed questionnaire battery,is used to analyse the anger levels and resulting behaviour expression of passengers in 6-item anger-provoking situations.The analysis shows that a positive correlation exists between the frequency or duration of bus rides and anger levels/external anger expression,while self-adaptive expression is only correlated with frequency.Gender differs only in the violent external expression,where males display a greater preference.Meanwhile,the correlations of anger levels between anger-provoking situations are significantly positive.Moreover,anger expression patterns gradually shift from self-adaptation to external expression as anger levels grow in general,but the variation rules of expression frequency are different.Overall,this study provides a newly effective tool to explore characteristics of the anger expression of bus passengers in different anger-provoking scenarios and demonstrates its variation features when anger levels change.

关键词： anger bus passengers expression bus passengers’anger and expression inventory(BPASX)

f-Harmonic Maps Within Bounded Distance from Quasi-isometric Maps

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Communications in Mathematics and Statistics 2023年第4期11卷 815-825页

作者： Qun Chen Kaipeng Li Hongbing Qiu School of Mathematics and Statistics Wuhan UniversityWuhan 430072People’s Republic of China Hubei Key Laboratory of Computational Science Wuhan UniversityWuhan 430072People’s Republic of China

In this article,we prove that a quasi-isometric map between rank one symmetric spaces is within bounded distance from an f-harmonic map.

关键词： F-harmonic map Quasi-isometric map Rank one symmetric spaces

Very long wave infrared quantum dot photodetector up to 18μm

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Light(Science & Applications) 2024年第4期13卷 772-782页

作者： Xiaomeng Xue qun Hao Menglu chen School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China. Westlake Institute for Optoelectronics FuyangHangzhou 311421China. Physics Department Changchun University of Science and TechnologyChangchun 130022China

Colloidal quantum dots(CQDs)are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared wavelengths.People may question about the upper limit on the CQD wavelength region.To date,although the CQD absorption already reaches terahertz,the practical photodetection wavelength is limited within mid-wave infrared.To figure out challenges on CQD photoresponse in longer wavelength,would reveal the ultimate property on these nanomaterials.What’s more,it motivates interest in bottom-up infrared photodetection with less than 10%cost compared with epitaxial growth semiconductor bulk.In this work,developing a re-growth method and ionic doping modification,we demonstrate photodetection up to 18μm wavelength on HgTe CQD.At liquid nitrogen temperature,the responsivity reaches 0.3 A/W and 0.13 A/W,with specific detectivity 6.6×108 Jones and 2.3×109 Jones for 18μm and 10μm CQD photoconductors,respectively.This work is a step toward answering the general question on the CQD photodetection wavelength limitation.

关键词： quantum wave ultraviolet

Data-driven decision-making model for determining the number of volunteers required in typhoon disasters

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Journal of Safety Science and Resilience 2023年第3期4卷 229-240页

作者： Sheng-Qun Chen Jie Bai School of Information Engineering Fujian Business UniversityFuzhou 350506China School of computer and information Fujian agriculture and Forestry UniversityFuzhou 350002China

Volunteer teams provide valuable support after large-scale disasters.However,excessive volunteer participation poses challenges for formal operations.Therefore,an appropriate decision-making method is required to quickly determine the number of volunteers required after a disaster.This study proposes a data-driven decision-making(D^(3)M)method for typhoon disaster volunteerism that can effectively predict the number of volunteers required.Disaster data from actual cases were gathered,analyzed,and preprocessed to prepare the model.Feature selection,D^(3)M model training and optimization,and model validation were performed to fine-tune the volunteer participant predictions.Using data from an actual typhoon in the Philippines,the rationality and efficacy of the method were verified through a comparative analysis of the experimental results.The proposed method learns from disaster-event data to quickly predict the number of volunteers needed,such that it not only reasonably allocates volunteers to assist professional teams in rescue but also avoids secondary problems caused by an overwhelming response.

关键词： Data-driven decision-making Optimization Rescue Typhoon

Automatic Web-based relational data imputation

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Frontiers of Computer Science 2018年第6期12卷 1125-1139页

作者： Hailong LIU Zhanhuai LI Qun Chen Zhaoqiang chen School of Computer Science and Technology Northwestern Polytechnical UniversityXi'an 710072China

Data incompleteness is one of the most important data quality problems in enterprise information systems. Most existing data imputing techniques just deduce approximate values for the incomplete attributes by means of some specific data quality rules or some mathematical methods. Unfortunately, approximation may be far away from the truth. Furthermore, when observed data is inadequate, they will not work well. The World Wide Web (WWW) has become the most important and the most widely used information source. Several current works have proven that using Web data can augment the quality of databases. In this paper, we propose a Web-based relational data imputing framework, which tries to automatically retrieve real values from the WWW for the incomplete attributes. In the paper, we try to take full advantage of relations among different kinds of objects based on the idea that the same kind of things must have the same kind of relations with their relatives in a specific world. Our proposed techniques consist of two automatic query formulation algorithms and one graph-based candidates extraction model. Several evaluations are proposed on two high-quality real datasets and one poor-quality real dataset to prove the effectiveness of our approaches.

关键词： data incompleteness imputation World Wide Web query formulation candidate selection semantic relation

On the Error Estimate of the Harmonic B_z Algorithm in MREIT from Noisy Magnetic Flux Field

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数学年刊：B辑英文版 2014年第3期35卷 319-336页

作者： Qun Chen Jijun LIU College of Mathematics and Statistics Nanjing University of Information Science and Technology Corresponding author. Department of Mathematics Southeast University

Magnetic resonance electrical impedance tomography(MREIT, for short) is a new medical imaging technique developed recently to visualize the cross-section conductivity of biologic tissues. A new MREIT image reconstruction method called harmonic Bz algorithm was proposed in 2002 with the measurement of Bz that is a single component of an induced magnetic flux density subject to an injection current. The key idea is to solve a nonlinear integral equation by some iteration process. This paper deals with the convergence analysis as well as the error estimate for noisy input data Bz, which is the practical situation for MREIT. By analyzing the iteration process containing the Laplacian operation on the input magnetic field rigorously, the authors give the error estimate for the iterative solution in terms of the noisy level δ and the regularizing scheme for determiningΔBz approximately from the noisy input data. The regularizing scheme for computing the Laplacian from noisy input data is proposed with error analysis. Our results provide both the theoretical basis and the implementable scheme for evaluating the reconstruction accuracy using harmonic Bz algorithm with practical measurement data containing noise.

关键词：误差估计磁通密度算法谐波非线性积分方程输入数据感应磁场迭代过程