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Improving flight performance of UAVs by ice shape modulation

Chinese Journal of Aeronautics 2024年第8期37卷 49-62页

作者： Jiajun ZHANG Xuecheng LIU Hua LIANG Like XIE Biao WEI Haohua ZONG Yun WU Yinghong Li national key lab of Aerospace Power System and Plasma Technology Air Force Engineering UniversityXi’an 710038China Institute of Aero-Engine School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China

aircraft icing poses a great threat to flight *** response to the characteristics of high-power consumption,large volume,and heavy weight of traditional anti-/de-icing technologies,the concept of ice shape modulation is proposed,which is called ice tolerant ***,the flight performance of Unmanned Aerial Vehicle(UAV)was compared in three states:no ice,full ice,and modulated ice through flight *** was found that ice shape modulation has a significant improvement effect on the aerodynamic performance of aircraft under icing *** the three modulated ice shape conditions in this experiment,the lift coefficient of the UAV under different ice shape modulation conditions increased by 18%–33%,and the stalling angle was delayed by 3°-5°.Subsequently,the pressure distribution,streamlines in the flow field,and detached vortex distribution of the UAV model in these three states were obtained through numerical simulation,to study the mechanism of ice shape modulation on the aerodynamic performance of *** simulation found that the reason for the improvement of the wings effect after ice shape modulation is that the modulated area forms a leading-edge protrusion structure similar to a vortex *** structure prolongs the mixed flow region on the wings surface and reduces the trend of flow separation,which plays a role in increasing lift and reducing drag for UAVs under icing ***,a reverse reachable set that can be used for unexpected state recovery is used as the definition of flight safety boundaries,and an aircraft dynamics model is established to obtain flight safety boundaries for different *** has found that the flight safety boundary of the UAV in a no ice state is greater than that in a modulated ice state,and the safety boundary in a modulated ice state is greater than that in a full ice *** with the full ice state,the flight safety boundary after modulation has expanded by 27.0%.The sch

关键词： Ice shape modulation Aerodynamic performance Reachable set Flight safety UAV

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Heat Transfer Characteristics of a Microchannel Heat Sink with Highly-Dense Micro-Jet Arrays

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Journal of Thermal Science 2024年第3期33卷 1148-1160页

作者： ZHANG Yu CHEN Xiaoyan MIAO Lin CHEN Liang HOU Yu State key laboratory of Multiphase flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Beijing Aerospace Technology Institute Beijing100083China

This paper proposed a new structure of highly-dense micro-jet arrays for hybrid jet-impingement/microchannel heat sinks(~120 jet per cm^(2) with jet width of 0.35 mm).Parametric study is performed to investigate the influence of structure and flow parameters on the convective heat transfer of water jet cooling in confined *** simulation results show that the optimal jet width,jet spacing and impingement distance are around 0.2 mm,0.2 mm and 0.3 mm,respectively,which can achieve a low thermal resistance as well as a relatively low pressure *** analysis of the heat transfer pathways shows that the micro-fin jet structures can extend the impinging heat transfer area and conduct a considerable proportion of heat,which can reach up to 38.9%with the Reynolds number ranging from 797.1 to *** heat transfer characteristics in the heat sink will shift from impingement dominated heat transfer to the channel-convection dominated heat transfer as the jet impingement distance increases.A correlation is proposed to predict the average Nusselt number on the stagnation area for the heat sink with different structure parameters,and the deviations of predictions from the numerical results are less than 10%.

关键词： hybrid heat sink impingement microchannel thermal management high heat flux

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A study on basic research priorities and development suggestions for the digital transformation of air traffic management

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Aerospace traffic and Safety 2024年第1期1卷 1-9页

作者： Zhijie Chen Yongwen Zhu Fan Pu Wen Tian State key laboratory of air traffic management System Nanjing 211106China College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China

air traffic is exhibiting the characteristics of high density,high volume,and unmanned *** ensure smooth,efficient,safe,and reliable operations,it is necessary to promote the digital transformation of air traffic management(ATM)with digitalization,autonomy,and collaboration as its typical *** article,based on the background of current and foreseeable future ATM needs,deeply analyzes the challenges and opportunities faced by traditional *** explores and proposes to further investigate the commonalities,characteristics,and evolution of air traffic,the interaction mechanism of"human-machine-environment"in air traffic,the integrated design of airborne avionics and ATM systems,the comprehensive integration of ATM based on vulnerability analysis,airspace classification management,air traffic flow management,key technologies of"perception-collision avoidance",wake vortex monitoring and interval reduction,unmanned aerial vehicle management,and the expansion of ATM capabilities in the"high frontier".The research suggests strengthening top-level planning,building an open,mutually beneficial,and win-win digital ATM ecological framework based on multi-party collaboration,coordinating the research and application of new digital ATM technologies,accelerating the occupation of the new track of low-altitude economy,and enhancing ATM capabilities driven by the digital transformation of ATM.

关键词： air traffic management(ATM)system Digital transformation airspace resource management Digital ATM service

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Molecular compositions and sources of organic aerosols at a rural site on the Guanzhong Plain,Northwest China:The importance of biomass burning

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Particuology 2024年第6期89卷 44-56页

作者： Yali Liu Minxia Shen Haijiao Liu Wenting Dai Weining Qi Yifan Zhang Lu Li Yue Cao Xin Wang Xiao Guo Yingkun Jiang Jianjun Li State key laboratory of Loess and Quaternary Geology Key Lab of Aerosol Chemistry and PhysicsInstitute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China Xi'an Institute for Innovative Earth Environment Research Xi'an 710061China national Observation and Research Station of Regional Ecological Environment Change and Comprehensive management in the Guanzhong Plain ShaanxiChina

The concentration of PM_(2.5)has considerably reduced in recent years,but remains relatively high in *** particular,the increasing contribution of organic compounds to PM_(2.5)generates popular pressure for further reductions,resulting in an urgent need to study organic aerosol(OA).To investigate the molecular composition and source contribution of OA in the rural area of the Guanzhong Plain,Northwest China,PM_(2.5)samples were collected during 3–23 August 2016 and 5–20 January 2017 and studied for more than 100 organic tracer *** mean concentration of total measured organic compounds is 662±296 ng/m^(3)in summer and 3258±1925 ng/m^(3)in *** is the most abundant single compound found throughout the sampling period,which is a crucial tracer for biomass burning emissions,preliminary suggesting that biomass burning is an essential source of *** summer,organic compounds such as lipid compounds,sugar compounds,and polycyclic aromatic hydrocarbons(PAHs),more come from higher plants,wood burning,vehicle exhausts,plastic waste,and other direct emission *** PAHs(OPAHs),nitrophenols,and phthalic acids more come from the atmosphere through the oxidation reaction of aromatic precursors,especially photochemical ***,in winter,most of the increases in concentrations of organic compounds are attributed to biomass *** analysis of a haze event(14–19 January 2017)during the winter sampling period shows that the increases in the concentration of organic compounds are unaccompanied by strong secondary formation under lower relative humidity(49.1%±13.5%).The main reason for the growth of OA in this haze event is the accumulation of primary OA(POA).The source apportionment by the positive matrix factorization(PMF)model shows that biomass burning(37.1%)is the primary source of OA in the rural regions of the Guanzhong Plain,especially in winter(40.6%).The contribution of secondary formation decreases from 26.0%in summer t

关键词： Organic aerosol Molecular composition Seasonal variation Source apportionment Guanzhong Plain

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airfoil friction drag reduction based on grid-type and super-dense array plasma actuators

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Plasma Science and Technology 2024年第2期26卷 94-103页

作者：方子淇宗豪华吴云梁华苏志 School of Aerospace Engineering Xi'an Jiaotong UniversityXi'an 710049People's Republic of China School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049People's Republic of China national key lab of Aerospace Power System and Plasma Technology Air Force Engineering UniversityXi'an 710038People's Republic of China

To improve the cruise flight performance of aircraft, two new configurations of plasma actuators(grid-type and super-dense array) were investigated to reduce the turbulent skin friction drag of a low-speed airfoil. The induced jet characteristics of the two actuators in quiescent air were diagnosed with high-speed particle image velocimetry(PIV), and their drag reduction efficiencies were examined under different operating conditions in a wind tunnel. The results showed that the grid-type plasma actuator was capable of producing a wall-normal jet array(peak magnitude: 1.07 m/s) similar to that generated in a micro-blowing technique, while the superdense array plasma actuator created a wavy wall-parallel jet(magnitude: 0.94 m/s) due to the discrete spanwise electrostatic forces. Under a comparable electrical power consumption level,the super-dense array plasma actuator array significantly outperformed the grid-type configuration,reducing the total airfoil friction drag by approximately 22% at a free-stream velocity of 20 m/*** magnitude of drag reduction was proportional to the dimensionless jet velocity ratio(r), and a threshold r = 0.014 existed under which little impact on airfoil drag could be discerned.

关键词： plasma actuator flow control drag reduction airfoil

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Understanding Simulated Causes of Damaging Surface Winds in a Derecho-Producing Mesoscale Convective System near the East China Coast Based on Convection-Permitting Simulations

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Advances in Atmospheric Sciences 2024年第11期41卷 2112-2130页

作者： Liping LUO Ming XUE Xin XU Lijuan LI Qiang ZHANG Ziqi FAN College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China State key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China key laboratory of Mesoscale Severe Weather/Ministry of Education and School of Atmospheric Sciences Nanjing UniversityNanjing 210023China Center for Analysis and Prediction of Storms and School of Meteorology University of OklahomaNormanOklahoma 73072USA Civil Aviation North China air traffic management Bureau Meteorological Center Beijing 100621China

A mesoscale convective system(MCS) occurred over the East China coastal provinces and the East China Sea on 30April 2021, producing damaging surface winds near the coastal city Nantong with observed speeds reaching 45 m s^(–1). A simulation using the Weather Research and Forecasting model with a 1.5-km grid spacing generally reproduces the development and subsequent organization of this convective system into an MCS, with an eastward protruding bow segment over the sea. In the simulation, an east-west-oriented high wind swath is generated behind the gust front of the MCS. Descending dry rear-to-front inflows behind the bow and trailing gust front are found to feed the downdrafts in the main precipitation regions. The inflows help to establish spreading cold outflows and enhance the downdrafts through evaporative cooling. Meanwhile, front-to-rear inflows from the south are present, associated with severely rearward-tilted updrafts initially forming over the gust front. Such inflows descend behind(north of) the gust front, significantly enhancing downdrafts and near-surface winds within the cold pool. Consistently, calculated trajectories show that these parcels that contribute to the derecho originate primarily from the region ahead(south) of the east-west-oriented gust front, and dry southwesterly flows in the low-to-middle levels contribute to strong downdrafts within the MCS. Moreover, momentum budget analyses reveal that a large westward-directed horizontal pressure gradient force within the simulated cold pool produced rapid flow acceleration towards Nantong. The analyses enrich the understanding of damaging wind characteristics over coastal East China and will prove helpful to operational forecasters.

关键词： damaging surface winds convection-permitting simulations mesoscale convective system gust front cold pool

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DGS1 improves rice disease resistance by elevating pathogenassociated molecular pattern-triggered immunity

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aBIOTECH 2024年第1期5卷 46-51页

作者： Yu Wang Chuan Zheng You-liang Peng Qian Chen MOA key lab of Pest Monitoring and Green management and Frontiers Science Center for Molecular Design Breeding China Agricultural UniversityBeijing 100193China

Rice yield and disease resistance are two crucial factors in determining the suitability of a gene for agricultural *** grain size1(DGS1),encoding an RING-type E3 ligase,has been found to have a positive effect on rice yield by regulating rice grain number and 1000-grain ***,the role of DGS1 in rice blast resistance is still *** this study,we report that DGS1 enhances disease resistance by improving PTI responses,including stronger ROS burst and MAPK activation,and also increased expression of defense-related ***,DGS1 works in conjunction with ubiquitin conjugating enzyme OsUBC45 as an E2-E3 pair to facilitate the ubiquitin-dependent degradation of OsGSK3 and OsPIP2;1,thereby influencing rice yield and immunity,***,the DGS1-OsUBC45 module has the potential in facilitating rice agricultural breeding.

关键词： Rice blast PTI ERAD E2-E3 pair Ubiquitination

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Preferential Formation of Ethylene via Electrocatalytic CO_(2) Reduction on Mesoporous Cu_(2)O Nanoparticles:Synergistic Effects of Pore Structure Confinement and Surface Amine

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Chinese Journal of Chemistry 2024年第16期42卷 1846-1852页

作者： Haifeng Zhang Dun Li Zhifang Chen Yingying Wang Haoyu Sun Feng Liu Maochang Liu Yiqun Zheng Hongwen Huang School of Chemistry Chemical Engineering and MaterialsJining UniversityQufuShandong 273155China College of Materials Science and Engineering Hunan UniversityChangshaHunan 410082China Health management Department Shandong Vocational College of Light IndustryZiboShandong 255300China International Research Center for Renewable Energy national key laboratory of Multiphase flow in Power Engineering Xi'an Jiotong UniversityXi'anShaanxi 710049China

We present a facile synthetic strategy to create mesoporous Cu_(2)O nanocrystals with tunable pore structures and surface functional groups of amine derivatives for efficient and preferable electrochemical conversion of CO_(2) into *** structural characteristics of theseCu_(2)O nanocrystals can be manipulated using a set of amine derivatives,such as pyridine,4,4'-bipyridine,and hexamethylenetetramine,during the oxidative etching process of Cu nanocrystals by bubbling gaseous oxygen in N,N-dimethylformamide *** amine derivatives not only serve as surface functional groups but also significantly affect the resulting pore *** synergistic effect of pore structure confinement and surface amine functionalization leads to the superb Faradaic efficiency(FE)of 51.9% for C_(2)H_(4),respectively,together with the C_(2)H_(4) partial current density of -209.4 mA·cm^(-2) at -0.8 V *** hydrogen electrode(RHE).The relatively high selectivity towards C_(2)H_(4) was investigated using DFT simulations,where 4,4'-bipyridine functionalized Cu_(2)O seemed to favor the C_(2)H_(4) formation with the low free energy of the *** study provides a feasible strategy to manipulate the pore structure and surface functionalization of mesoporous Cu_(2)O nanocrystals by regulating the oxidative etching process,which sheds light on the rational preparation of high-performance CO_(2)RR electrocatalysts.

关键词： Amines Ethylene Cuprous oxide CO_(2)reduction Mesoporous materials

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Resilience assessment and optimization method of city road network in the post-earthquake emergency period

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 765-779页

作者： Wang Haoran Xiao Jia Li Shuang Zhai Changhai key lab of Structures Dynamic Behavior and Control of the Ministry of Education Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information TechnologyHarbin Institute of TechnologyHarbin 150090China

The post-earthquake emergency period,which is a sensitive time segment just after an event,mainly focuses on saving life and restoring social *** improve the seismic resilience of city road networks,a resilience evaluation method used in the post-earthquake emergency period is *** road seismic damage index of a city road network can consider the influence of roads,bridges and buildings along the roads,*** road capacity after an earthquake.A function index for a city road network is developed,which reflects the connectivity,redundancy,traffic demand and traffic function of the *** optimization model for improving the road repair order in the post-earthquake emergency period is also developed according to the resilience evaluation,to enable decision support for city emergency management and achieve the best seismic resilience of the city road *** optimization model is applied to a city road network and the results illustrate the feasibility of the resilience evaluation and optimization method for a city road network in the post-earthquake emergency period.

关键词： city road network post-earthquake emergency period traffic demand resilience evaluation optimization model

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Modeling the dynamic impacts of maritime network blockage on global supply chains

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The Innovation 2024年第4期5卷 103-109,102页

作者： Shen Qu Yunlei She Qi Zhou Jasper Verschuur Lu-Tao Zhao Huan Liu Ming Xu Yi-Ming Wei Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing 100081China School of management Beijing Institute of TechnologyBeijing 100081China Beijing key lab of Energy Economics and Environmental management Beijing 100081China Oxford Programme for Sustainable Infrastructure Systems(OPSIS) Environmental Change InstituteUniversity of OxfordOX12JD OxfordUK State key Joint laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China State Environmental Protection key laboratory of Sources and Control of air Pollution Complex Beijing 100084China School of Environment Tsinghua UniversityBeijing 100084China

Recent phenomena such as pandemics,geopolitical tensions,and climate change-induced extreme weather events have caused transportation network interruptions,revealing vulnerabilities in the global supply chain.A salient example is the March 2021 Suez Canal blockage,which delayed 432 vessels carrying cargo valued at$92.7 billion,triggering widespread supply chain *** ability to model the spatiotemporal ramifications of such incidents remains *** fill this gap,we develop an agent-based complex network model integrated with frequently updated maritime *** Suez Canal blockage is taken as a case *** results indicate that the effects of such blockages go beyond the directly affected countries and *** Suez Canal blockage led to global losses of about$136.9($127.5–$147.3)billion,with India suffering 75%of these *** losses show a nonlinear relationship with the duration of blockage and exhibit intricate trends post *** proposed model can be applied to diverse blockage scenarios,potentially acting as an earlyalert system for the ensuing supply chain ***,high-resolution daily data post blockage offer valuable insights that can help nations and industries enhance their resilience against similar future events.

关键词： chains valued extreme

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