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A geographical and operational deep graph convolutional approach for flight delay prediction

Chinese Journal of Aeronautics 2023年第3期36卷 357-367页

作者： Kaiquan CAI Yue LI Yongwen ZHU Quan FANG Yang YANG wenbo du School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Key Laboratory of National Airspace Technology Beijing 100085China National Lab of Pattern Recognition Institute of AutomationChinese Academy of SciencesBeijing 100190China Research Institute for Frontier Science Beihang UniversityBeijing 100191China

Flight delay prediction has attracted great interest in civil aviation community due to its significant role in airline planning,flight scheduling,airport operation,and passenger *** delay is affected by numerous factors and irregularly propagates in air transportation networks owing to flight connectivity,which brings critical challenges to accurate flight delay *** recent years,Graph Convolutional Networks(GCNs)have become popular in flight delay prediction due to the advantage in extracting complicated ***,most of the existing GCN-based methods have failed to effectively capture the spatial-temporal information in flight delay *** this paper,a Geographical and Operational Graph Convolutional Network(GOGCN)is proposed for multi-airport flight delay *** GOGCN is a GCN-based spatial-temporal model that improves node feature representation ability with geographical and operational spatial-temporal interactions in a ***,an operational aggregator is designed to extract global operational information based on the graph structure,while a geographical aggregator is developed to capture the similar nature among spatially close *** experiments on a real-world dataset demonstrate that the proposed approach outperforms the state-of-the-art methods with a satisfying accuracy improvement.

关键词： Flight delay prediction Flight operation pattern Geographical interactive information Graph neural network Spatial-temporal information

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静压群桩挤土效应对邻近既有码头桩基影响数值分析

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中国海洋大学学报（自然科学版） 2024年第9期54卷 141-147页

作者：杜文博谢伟王滨倪卫达沈侃敏高广运中国电建集团华东勘测设计研究院有限公司浙江杭州310030 中国海洋大学工程学院山东青岛266100 中国海洋大学环境科学与工程学院山东青岛266100 同济大学土木工程学院上海200092

为研究软土地区静压群桩对周边建构筑物的不利影响,本文以浙江某近海光伏发电项目为背景,利用圆孔扩张法模拟沉桩挤土效应,基于硬化土(Hardening soil,HS)本构模型,建立了桩-土、桩-桩相互作用三维有限元模型,据此分析并探讨了沉桩顺序... 详细信息

为研究软土地区静压群桩对周边建构筑物的不利影响,本文以浙江某近海光伏发电项目为背景,利用圆孔扩张法模拟沉桩挤土效应,基于硬化土(Hardening soil,HS)本构模型,建立了桩-土、桩-桩相互作用三维有限元模型,据此分析并探讨了沉桩顺序及遮栏效应对邻近既有桩基础的影响。结果表明,当不考虑沉桩顺序及遮拦效应时,既有桩基础最大变形为6.09 mm,桩基均处于弹性状态;当考虑沉桩顺序及遮栏效应后,群桩左侧土体位移有所减小。既有桩变形和内力均易受沉桩顺序和沉桩相对位置关系因素的影响,工程设计和施工应对沉桩顺序给予足够重视,对于本项目建议以沉桩顺序为逐排压桩顺序。

关键词：静压沉桩圆孔扩张法硬化土模型沉桩顺序遮拦效应

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UAV navigation in high dynamic environments:A deep reinforcement learning approach

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Chinese Journal of Aeronautics 2021年第2期34卷 479-489页

作者： Tong GUO Nan JIANG Biyue LI Xi ZHU Ya WANG wenbo du School of Electronic and Information Engineering Beihang UniversityBejing 100083China Key Laboratory of Advanced Technology of Near Space Information System(Beihang University) Ministry of Industry and Information Technology of ChinaBeijing 100083China Research Institute of Frontier Science Beihang UniversityBeijing 100083China College of Software Beihang UniversityBeijing 100083China State Key Laboratory of Software Development Environment Beihang UniversityBeijing 100083China

Unmanned Aerial Vehicle(UAV) navigation is aimed at guiding a UAV to the desired destinations along a collision-free and efficient path without human interventions, and it plays a crucial role in autonomous missions in harsh environments. The recently emerging Deep Reinforcement Learning(DRL) methods have shown promise for addressing the UAV navigation problem,but most of these methods cannot converge due to the massive amounts of interactive data when a UAV is navigating in high dynamic environments, where there are numerous obstacles moving *** this work, we propose an improved DRL-based method to tackle these fundamental *** be specific, we develop a distributed DRL framework to decompose the UAV navigation task into two simpler sub-tasks, each of which is solved through the designed Long Short-Term Memory(LSTM) based DRL network by using only part of the interactive data. Furthermore, a clipped DRL loss function is proposed to closely stack the two sub-solutions into one integral for the UAV navigation problem. Extensive simulation results are provided to corroborate the superiority of the proposed method in terms of the convergence and effectiveness compared with those of the state-of-the-art DRL methods.

关键词： Autonomous vehicles Deep learning Motion planning Navigation Reinforcement learning Unmanned Aerial Vehicle(UAV)

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Icosahedral quasicrystalline phase in an as-cast Mg-Zn-Er alloy

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Rare Metals 2009年第3期28卷 297-301页

作者： LI Jianhui du wenbo LI Shubo WANG Zhaohui School of Materials Science and Engineering Beijing University of Technology Beijing 100124 China

The microstructure of an as-cast Mg-Zn-Er alloy was investigated through scanning electron microscopy （SEM） and transmission electron microscopy （TEM） equipped with energy dispersive spectroscopy （EDS）. The results indicate that two different second phases, one with eutectoid-lamellar morphology and the other with granular shape, distribute in the α-Mg matrix. The coexistence of the face-centered icosahedral quasicrystalline phase （I-phase） and W-phase with the face-centered cubic structure is found in the as-cast alloy. The coexistence of I-phase and W-phase in the Mg-Zn-Er alloy is because the W-phase is the primary phase and the I-phase forms by peritectic reaction during solidification.

关键词： magnesium alloy microstructure quasicrystal erbium

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Precipitate Characteristics and Mechanical Performance of Cast Mg–6RE–1Zn–xCa–0.3Zr(x=0 and 0.4 wt%) Alloys

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Acta Metallurgica Sinica(English Letters) 2022年第4期35卷 596-608页

作者： Zijian Yu Xi Xu Baotian du Kang Shi Ke Liu Shubo Li Xiuzhu Han Tao Xiao wenbo du College of Materials Science and Engineering Beijing University of TechnologyBeijing 100124China Beijing Institute of Spacecraft System Engineering Beijing 100094China

In this study,the Mg–4Y–1Gd–1Nd–xCa–1Zn–0.3Zr(x=0 and 0.4 wt%)cast alloys with low rare earth concentration were prepared in different routes of heat treatments,and their microstructures and mechanical properties were *** Mg–4Y–1Gd–1Nd–1Zn–0.4Ca–0.3Zr cast alloy with ultimate tensile strength(UTS)of 264±7.8 MPa,tensile yield strength(TYS)of 153±1.2 MPa and elongation to failure(EL)of 17.2±1.2% was successfully developed by appropriate heat *** improved mechanical performance was attributed to the combined strengthening effects of fine grains,Mg24RE5,β′,β_(1),γ′and LPSO *** the heat treatment process,cooling method of T4 treatment affected the microstructure,which consequently determined the mechanical properties air cooling,rather than water cooling,gave rise to the formation of γ′phase in the alloy without Ca ***,Ca addition facilitated the formation of γ′phase,and the γ′phase precipitated in the alloy after T4 treatment either by water cooling or by air cooling,but the air cooling increased the number density of γ′phase in comparison to the water *** the γ′phase strengthened the studied alloys,the formation of γ′phase inhibited the precipitatition of β′and β_(1) phases in the following T6 treatment,and consequently reduced the strengthening effect ofβ′andβ_(1) *** results showed that the mechanical performance of the studied alloys was largely determined by the precipitation of γ′phase,which was regulated by the Ca addition and the cooling method of T4 treatment.

关键词： Magnesium alloy Microstructure Mechanical properties Rare earth Heat treatment

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Development and characteristics of a low rare-earth containing magnesium alloy with high strength-ductility synergy

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Journal of Magnesium and Alloys 2023年第5期11卷 1629-1642页

作者： Zijian Yu Xi Xu Kang Shi Baotian du Xiuzhu Han Tao Xiao Shubo Li Ke Liu wenbo du Faculty of Materials and Manufacturing Beijing University of Technology100 PenLe YuanChaoyang DistrictBeijing 100124China Beijing Institute of Spacecraft System Engineering Beijing 100094China

In this study,we successfully developed a low RE containing Mg-3Y-2Gd-1Nd-0.5Zr(wt%)alloy with high strength-ductility synergy by combined processes of hot extrusion,hot rolling and *** alloy exhibits an excellent strength-ductility balance(UTS of 345±2.0 MPa,TYS of 301±5.0 MPa and EL of 9.2±1.9%),which is better than that of many Mg-RE wrought alloys with higher RE concentration and even comparable to that of 6061 Al wrought alloy.A long-range chain-like structure consisting ofβphase,βH phase,βM phase and zig-zag atomic columns is observed for the first time in the studied *** combined process of hot extrusion and hot rolling boosts the formation of deformed grains and low angle grain boundaries,and makes the deformed grains dominate in the alloy *** this circumstance,the following ageing generates a novel heterogeneous structure comprising the long-range chain-like structure with broad interparticle spacing and the spacious precipitate-free zones in the deformed grains,which plays a key role in the concurrent strengthening and toughening of the *** present study demonstrates that the deformed grains with long-range chain-like structures and precipitate-free zones is desirable microstructure for the low RE containing Mg alloys to achieve high strength-ductility synergy.

关键词： Magnesium alloy Microstructure Mechanical properties Rare earth

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Predictability of real temporal networks

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National Science Review 2020年第5期7卷 929-937页

作者： Disheng Tang wenbo du Louis Shekhtman Yijie Wang Shlomo Havlin Xianbin Cao Gang Yan School of Electronic and Information Engineering Beihang University Shanghai Institute of Intelligence Science and Technology Tongji University Network Science Institute Northeastern University Department of Physics Bar Ilan University CAS Center for Excellence in Brain Science and Intelligence Technology Chinese Academy of Sciences National Engineering Laboratory of Big Data Application Technologies of Comprehensive Transportation School of Physics Science and Engineering Tongji University

Links in most real networks often change over time. Such temporality of links encodes the ordering and causality of interactions between nodes and has a profound effect on network dynamics and *** evidence has shown that the temporal nature of links in many real-world networks is not ***, it is challenging to predict temporal link patterns while considering the entanglement between topological and temporal link patterns. Here, we propose an entropy-rate-based framework, based on combined topological–temporal regularities, for quantifying the predictability of any temporal network. We apply our framework on various model networks, demonstrating that it indeed captures the intrinsic topological–temporal regularities whereas previous methods considered only temporal aspects. We also apply our framework on 18 real networks of different types and determine their predictability. Interestingly,we find that, for most real temporal networks, despite the greater complexity of predictability brought by the increase in dimension, the combined topological–temporal predictability is higher than the temporal predictability. Our results demonstrate the necessity for incorporating both temporal and topological aspects of networks in order to improve predictions of dynamical processes.

关键词： temporal network predictability network entropy predictive algorithm

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The effect of heat treatment on microstructure of the melt-spun Mg-7Y-4Gd-5Zn-0.4Zr alloy

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Journal of Magnesium and Alloys 2016年第2期4卷 99-103页

作者： Ke Liu wenbo du Shubo Li Zhaohui Wang College of Materials Science and Engineering Beijing University of TechnologyBeijing 100124China

The microstructure evolution of the melt-spun Mg–7Y–4Gd–5Zn–0.4Zr alloy during annealing treatment has been investigated by using X-ray diffraction(XRD),optical microscope(OM),differential scanning calorimetry(DSC)and transmission electron microscope(TEM).The results indicated that two kinds of primary grains were contained in the melt-spun *** was the supersaturated magnesium matrix,and the other was the 18R-LPSO *** 18R-LPSO phase transformed into the 14H-LPSO phase during annealing treatment at 300 ℃ for 0.5 *** new precipitate of the 14H-LPSO phase was found at 300 ℃ for 5 *** of linear precipitates formed as well as some precipitate with quadrangular morphology in matrix at 500 ℃ for 0.5 *** melt-spun alloy displayed the highest hardness of 103 NHV after annealing treatment at 300 ℃ for 5 h.

关键词： Mg-RE alloy Melt-spun Microstructure LPSO phase

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A review on magnesium alloys for application of degradable fracturing tools

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Journal of Magnesium and Alloys 2022年第10期10卷 2649-2672页

作者： Jian Sun wenbo du Junjian Fu Ke Liu Shubo Li Zhaohui Wang Hongxing Liang Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China

The vulnerable corrosion resistance of Mg alloys is regarded as one of the main disadvantages restricting their application,while it can be used as an extraordinary specialty in some particular fields,such as petroleum exploitation and *** recent years,many Mg alloys with high corrosion rate and high strength have been developed for fracturing temporary plugging tools in the oil *** review briefly introduces the performance requirements of the degradable fracturing tools classified into mechanical and corrosion *** progress on corrosion behavior of degradable Mg-Al,Mg-Zn,Mg-RE alloys and Mg matrix composites is then summarized and ***,the factors influencing the degradation rate of Mg alloys are analyzed and divided into secondary phase,texture,dislocation,grain size and surface *** the summary,it can be found that addition of Ni or Cu to the degradable Mg alloys is a common and effective method to enhance the degradation rate due to increasing the amount of secondary phases and deteriorating the corrosion product *** the as-extruded degradable Mg alloys,grain size,texture and dislocation are the key factors affecting the corrosion rate under different processing *** expect this review is helpful for those who are working on developing Mg-based functional materials with superior degradation rate.

关键词： Review Mg alloys Degradable fracturing tools Corrosion rate Secondary phase

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Heterogeneous pigeon-inspired optimization

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Science China(Information Sciences) 2019年第7期62卷 64-72页

作者： Hao WANG Zhuxi ZHANG Zhen DAI Jun CHEN Xi ZHU wenbo du Xianbin CAO School of Electronic and Information Engineering Frontier Institute of Science and Technology InnovationBeihang University School of Engineering and Materials Science Queen Mary University of London

Pigeon-inspired optimization(PIO) is a swarm intelligence optimizer inspired by the homing behavior of pigeons. PIO consists of two optimization stages which employ the map and compass operator,and the landmark operator, respectively. In canonical PIO, these two operators treat every bird equally,which deviates from the fact that birds usually act heterogenous roles in nature. In this paper, we propose a new variant of PIO algorithm considering bird heterogeneity — HPIO. Both of the two operators are improved through dividing the birds into hub and non-hub roles. By dividing the birds into two groups, these two groups of birds are respectively assigned with different functions of "exploitation" and "exploration", so that they can closely interact with each other to locate the best promising solution. Extensive experimental studies illustrate that the bird heterogeneity produced by our algorithm can benefit the information exchange between birds so that the proposed PIO variant significantly outperforms the canonical PIO.

关键词： heuristic optimization pigeon-inspired optimization particle heterogeneity network-based topology scale-free network selective-informed learning

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