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Weighted local polynomial estimations of a non-parametric function with censoring indicators missing at random and their applications

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Frontiers of Mathematics in China 2022年第1期17卷 117-139页

作者： jiangfeng wang Yangcheng ZHOU Ju TANG School of Statistics and Mathematics Zhejiang Gongshang UniversityHangzhou 310018China Collaborative Innovation Center of Statistical Data Engineering Technology&ApplicationZhejiang Gongshang UniversityHangzhou 310018China

In this paper,we consider the weighted local polynomial calibration estimation and imputation estimation of a non-parametric function when the data are right censored and the censoring indicators are missing at random,and establish the asymptotic normality of these *** their applications,we derive the weighted local linear calibration estimators and imputation estimations of the conditional distribution function,the conditional density function and the conditional quantile function,and investigate the asymptotic normality of these ***,the simulation studies are conducted to illustrate the finite sample performance of the estimators.

关键词： Local polynomial estimation asymptotic normality non-parametric function censoring indicator missing at random

A hybrid lattice Boltzmann flux solver for integrated hypersonic fluid-thermal-structural analysis

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Chinese Journal of Aeronautics 2020年第9期33卷 2295-2312页

作者： Jiawei LI jiangfeng wang Liming YANG Chang SHU College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mechanical Engineering National University of SingaporeSingapore 119260Singapore

In this paper,a hybrid Lattice Boltzmann Flux Solver(LBFS)with an improved switch function is proposed for simulation of integrated hypersonic fluid-thermal-structural *** the solver,the macroscopic Navier–Stokes equations and structural heat transfer equation are discretized by the finite volume method,and the numerical fluxes at the cell interface are reconstructed by the local solution of the Boltzmann *** compute the numerical fluxes,two equilibrium distribution functions are *** is the D1Q4 discrete velocity model for calculating the inviscid flux across the cell interface of Navier–Stokes equations,and the other is the D2Q4 model for evaluating the flux of structural energy *** this work,a new dual thermal resistance model is proposed to calculate the thermal properties at the fluid–solid *** accuracy and stability of the present hybrid solver are validated by simulating several numerical examples,including the fluid-thermal-structural problem of cylindrical leading *** results show that the present solver can accurately predict the thermal properties of hypersonic fluid-thermalstructural problems and has the great potential for solving fluid-thermal-structural problems of long-endurance high-speed vehicles.

关键词： Finite volume method Fluid-structural-thermal Hybrid lattice Boltzmann flux solver Hypersonic Improved switch function

Modeling and simulation of intersection quasi-moving block speed guidance based on connected vehicles

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Journal of Intelligent and Connected Vehicles 2020年第2期3卷 67-78页

作者： Qing Xu jiangfeng wang Botong wang Xuedong Yan State Key Laboratory of Automotive Safety and Energy School of Vehicle and MobilityTsinghua UniversityBeijingChina Department of Traffic Engineer Beijing Jiaotong UniversityBeijingChina Department of ICV Testing and Research CATARC Automotive Test Center(Tianjin)Co.LtdTianJinChina

Purpose–This study aims to propose a speed guidance model of the CV environment to alleviate trafﬁc congestion at intersections and improve trafﬁc efﬁ*** introducing the theory of moving block section for high-speed train control,a speed guidance model based on the quasi-moving block speed guidance(QMBSG)is proposed to direct platoon including human-driven vehicles and connected vehicles(CV)through the intersection ***/methodology/approach–In this model,the green time of the intersection is divided into multiple block intervals according to the minimal safety *** vehicles can pass through the intersection by following the block interval using the QMBSG *** block interval is assigned dynamically according to the traveling relation of HV and CV,when entering the communication range of the *** validate the comprehensive guidance effect of the proposed model,a general evaluation function(GEF)is *** to CVs without speed guidance,the simulation results show that the GEF of QMBSG model has an obvious ***–Compared to CVs without speed guidance,the simulation results show that the GEF of QMBSG model has an obvious ***,compared to the single intersection speed guidance model,the GEF value of the QMBSG model improves over 17.1%.To further explore the guidance effect,the impact of sensitivity factors of the CVs’environment,such as intersection environment,communication range and penetration rate(PR)is *** the PR reaches 75.0%,the GEF value will change suddenly and the model guidance effect will be signiﬁcantly *** paper also analyzes the impact of the length of block interval under different PR and trafﬁc *** is found that the proposed model has a better guidance effect when the length of the block section is 2 s,which facilitates trafﬁc congestion alleviation of the intersection in ***/value–Based on the aforementioned discussion,the

关键词： Simulation analysis Block interval Connected vehicle Quasi-moving block Speed guidance

Impact of connected and autonomous vehicles on traffic safety of mixed traffic flow:from the perspective of connectivity and spatial distribution

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Transportation Safety and Environment 2022年第3期4卷 88-97页

作者： Jiakuan Dong jiangfeng wang Dongyu Luo Key Laboratory of Transport Industry of Big Data Application Technologies for Comprehensive Transport of Ministry of Transport Beijing Jiaotong UniversityBeijing 100044China.

Equipped with high driving automation and advanced communication technologies, connected and autonomous vehicles (CAV) areexpected to possess a shorter reaction time and a wider vision,which are promising to improve traffic safety and efficiency. However,little attention has been paid to the effect of connectivity and spatial distribution on the safety performance of mixed traffic flow. Inthis paper, we attempt to investigate the impact of CAV on traffic safety considering these factors. To this end, a car-following modelfor CAV is proposed first. Then, the cooperative driving strategy for CAVs is designed. Precisely, the feedback gains of the informationare adjusted in real-time and are designed based on the derived stability criterion of the mixed traffic flow. Microscopic simulations ofmixed traffic flow in traffic oscillation are designed and conducted to explore how the distribution and connectivity of CAV affect thesafety performance ofmixed traffic flow. Simulation results show that increasing the penetration rate of CAV is promising to shift thesafety performance ofmixed traffic flow. In addition, the safety performance of mixed traffic flow is related to the spatial distributionand communication range of CAV. Besides, increasing communication range does not inevitably improve the safety performance ofmixed traffic flow when the penetration rate of CAV is low. Moreover, it is also found from the spatial–temporal trajectory of themixedtraffic flow that introducing CAV can mitigate the propagation of the stop-and-go wave and increase the throughput.

关键词： Mixed traffic traffic safety connected and autonomous vehicle connectivity spatial distribution

Design of multi-vehicle ad hoc experiment system based on VANets

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Science China(Technological Sciences) 2011年第4期54卷 1011-1016页

作者： wang jiangfeng YAN XueDong SHAO ChunFu WEI LiYing MOE Key Laboratory for Transportation Complex Systems Theory and Technology Beijing Jiaotong UniversityBeijing 100044China

Vehicular ad hoc networks(VANets) experiment system is ***,characteristics and research fields of VANets are introduced *** to the characteristics of VANets,key modules that multi-vehicle ad hoc experiment system needs are designed,and each module's function and practice requirement is *** reliability of experiment system is tested primarily using three experiment scenes of multi-vehicle ad hoc network,car following and wireless *** experiment result shows that multi-vehicle ad hoc experiment system has the capability of the correlated experiment of VANets.

关键词： VANets multi-vehicle ad hoc car following experiment system

Effects of Chemical Reactions in the Hypersonic Reacting Flow around Blunt Bodies

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 71-79页

作者： ZHAO Faming wang jiangfeng FAN Xiaofeng YANG Tianpeng College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

The effects of chemical reactions in the hypersonic reacting flow are investigated using an integrated algorithm considering simultaneously two different reaction mechanisms,i.e.,including the high temperature air nonequilibrium chemical reactions and the H_2-air combustion reactions. The program is validated by the air non-equilibrium flow at Mach number of 25.9 with the RAM C-II configuration and the shock-induced combustion flow at Mach number of 4.512 6 around a sphere,respectively. Furthermore,the mixed reacting flow with the Mach number of 10.0 with an opposing jet of hydrogen is numerically analyzed. The results show that the program is reliable,and the effects of chemical reactions engender in the decrease of peak temperature along characteristic lines,as well as on the surface. The production of water is augmented in the region with high ratio of oxygen to hydrogen and weakened in the area with low ratio of oxygen to hydrogen by the air chemical non-equilibrium effects.

关键词： hypersonic air chemical non-equilibrium combustion effects of chemical reaction

基于iTransformer的高速公路通行费精准预测模型

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山东科学 2025年第1期38卷 120-128页

作者：王恒昆谷金宋之凡王江锋山东省交通科学研究院山东济南250002 山东省交通规划设计院集团有限公司山东济南250002 北京交通大学交通运输学院北京100044

高速公路通行费受到节假日、突发事件等复杂因素影响,传统预测方法在处理这些问题时,往往无法充分考虑多维因素之间的复杂交互作用,导致预测精度难以达到理想水平。大型语言模型利用自注意力机制能够实现对复杂时空数据的拟合,并具有更... 详细信息

高速公路通行费受到节假日、突发事件等复杂因素影响,传统预测方法在处理这些问题时,往往无法充分考虑多维因素之间的复杂交互作用,导致预测精度难以达到理想水平。大型语言模型利用自注意力机制能够实现对复杂时空数据的拟合,并具有更强的特征学习能力,可有效解决高速公路通行费的精准预测问题。利用此特性提出了一种基于iTransformer的高速公路通行费精准预测模型,该预测模型将时间信息作为独立维度嵌入输入序列中,并倒置了自注意力机制与前馈网络的职责,使得预测模型能够更准确地捕捉时间序列的动态特征和多变量之间的相关性。实例分析结果显示,所提出的预测模型在普通场景下较SARIMA模型和LSTM模型平均预测精度分别提高23.47%和17.84%。特殊场景下具有更优预测效果,分别提升70.92%和45.64%。针对所提出预测模型进行敏感性分析,模型对前馈网络层数和编码器堆叠层数较为敏感,对注意力头数变化不敏感。该研究为解决复杂交通环境下的通行费预测问题提供了新的方法论支持,对提高高速公路通行费预测精度具有重要意义。

关键词：大语言模型预测模型自注意力机制通行费

Geochemical characteristics of Bikou volcanic group and Sr-Nd-Pb isotopic composition: Evidence for breakup event in the north margin of Yangtze plate, Jining era

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Science China Earth Sciences 2007年第z2期50卷 339-350页

作者： LI YongFei LAI ShaoCong QIN jiangfeng LIU Xin wang Juan State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China

The geodynamic setting of the Bikou volcanic group is a critical question to trace the Precambrain tectonic framework and evolution for the Yangtze plate. This study has suggested that the Bikou volcanic group is composed of several residual oceanic crust units: MORB (mid-ocean ridge basalt), Alk-OIB (alkaline ocean island basalt) and Th-OIB (tholeiitic ocean island basalt) as well as subduction-related volcanic rocks. According to field observation, those distinct rocks occurred collectively in form of tectonic contact, implying that the Bikou volcanic group was an ophiolitic mélange. Coupled with geochronological data, a perished oceanic basin at the northern margin of the Yangtze block during Neoproterozoic was tested by this ophiolitic mélange. Meanwhile, the isogeochemical data suggest that the ocean occurred in the Southern Hemisphere identical to Indian, South Atlantic and South Pacific oceans in terms of their Dupal anomalies, and the original source of the rocks could be probably mixing by EMⅠand EMⅡ component caused by dehydration melting of subducting oceanic crust during subduction process. On the basis of geochemical characteristics of the studied rocks, the Bikou volcanic group could imply that a partial breakup event occurred in the northern margin of Yangtze plate during the Neoproterozoic era.

关键词： Bikou volcanic group, ophiolitic mélange, geochemistry, Dupal anomaly, Neoproterozoic, Yangtze plate

Evaluating damage in optical elements using an amplified spontaneous emission beam

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High Power Laser Science and Engineering 2015年第4期3卷 25-30页

作者： Qiong Zhou jiangfeng wang Yajing Guo Dean Liu Jianqiang Zhu National Laboratory on High Power Laser and Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences University of Chinese Academy of Science

A method to evaluate damage in optical elements with the near field of an amplified spontaneous emission(ASE) beam has been developed. Local peak intensities are generally distributed randomly in the near field of a laser beam. The partial coherence of the ASE source results in a very smooth beam profile. The coherence time of ASE is much less than the pulse width. Small-scale intensity modulations can be smoothed out rapidly within the time of a pulse *** the experiments, ASE is generated from a multifunctional high-performance Nd:glass system, with a pulse duration of 3 ns, a spectral width(full width at half maximum, FWHM) of 1 nm and an adjustable energy range from 1 to 10 *** damage thresholds of samples induced by ASE are two to three times higher than those induced by a laser with the same size of test spot. Furthermore, the ASE beam has great potential for the detection of defects over a large area and the conditioning of optical elements.

关键词： amplified spontaneous emission damage threshold test partially coherence uniform intensity distribution