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FY-4A/GIIRS资料云上温度廓线反演研究

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激光与光电子学进展 2021年第17期58卷 117-125页

作者：黄鹏宇郭强韩昌佩张春明杨天杭黄硕中国科学院上海技术物理研究所红外探测与成像技术重点实验室上海200083 中国科学院大学北京100081 国家卫星气象中心北京100049

云污染容易造成星基红外高光谱观测精度下降,导致大量观测信息损失。针对有云情况下的干涉式大气垂直探测仪(FY-4A/GIIRS)的观测数据,提出一种云上温度廓线反演方法。利用辐射传输模型分别开展晴空和有云情况下的观测亮温模拟实验,统计... 详细信息

云污染容易造成星基红外高光谱观测精度下降,导致大量观测信息损失。针对有云情况下的干涉式大气垂直探测仪(FY-4A/GIIRS)的观测数据,提出一种云上温度廓线反演方法。利用辐射传输模型分别开展晴空和有云情况下的观测亮温模拟实验,统计分析不同通道的模拟亮温变化特征,根据云顶气压确定通道优选方案,通过神经网络算法实现云上的温度廓线反演,温度廓线反演的精度评估采用ERA5再分析数据作为参照标准。实验结果表明均方根误差(RMSE)整体优于1.5 K,反演的温度廓线具有较高的精度,有效地提高了FY-4A/GIIRS在云污染情况下的观测资料使用率。

关键词：大气光学风云四号气象卫星干涉式大气垂直探测仪云污染温度廓线大气遥感

A new skeleton based flying bird detection method for low-altitude air traffic management

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Chinese Journal of Aeronautics 2018年第11期31卷 2149-2164页

作者： tianhang WU Xiaoyan LUO Qunyu XU School of Electronic and Information Engineering Beihang University Image Processing Center School of AstronauticsBeihang University Department of Civil and Environmental Engineering University of Illinois

In low-altitude air traffic management, non-cooperation targets are the greatest threat to security of low-flying aircraft. Among various aviation fatalities, flying bird is the main factor with the highest risk and directs economic losses amounted to nearly 10 billion US dollars each ***, Flying Bird Detection(FBD) has attracted considerable attention in low-altitude air traffic management. In this paper, we propose a skeleton based FBD method via describing bird motion information with a set of key poses. To overcome the variability of birds, the skeleton feature is selected as a relatively fixed and common characteristic for the pose appearance of flying bird. Based on the geometric topology among some key parts of bird body, a set of key poses can be described by some extracted skeleton features, which are used to represent the bird motion information. Aimed at robustly handling with the pose variations, multiple pose-specific classifiers are individually trained to learn the representative poses of the flying bird. At the detection stage,the flying bird skeleton features are combined with extracted key-pose sets to perform the flying bird classification task from each image. Afterwards, the key-frame pose-change set and the consistency of the classification results from sequent images are employed to validate the final detection *** on flying bird datasets demonstrate the effectiveness and efficiency of the proposed method.

关键词： Bird-aircraft collisions Flight security Flying bird detection Low-Altitude Air Traffic Management(LAATM) Simplified skeleton descriptor

A fast and automatic full-potential finite volume solver on Cartesian grids for unconventional configurations

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Chinese Journal of Aeronautics 2017年第3期30卷 951-963页

作者： Fanxi LYU tianhang XIAO Xiongqing YU College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

To meet the requirements of fast and automatic computation of subsonic and transonic aerodynamics in aircraft conceptual design,a novel finite volume solver for full potential flows on adaptive Cartesian grids is developed in this *** grids with geometric adaptation are firstly generated automatically with boundary cells processed by cell-cutting and cell-merging *** nonlinear full potential equation is discretized by a finite volume scheme on these Cartesian grids and iteratively solved in an implicit fashion with a generalized minimum residual（GMRES） *** computation,solution-based mesh adaptation is also applied so as to capture flow features more *** improved ghost-cell method is proposed to implement the non-penetration wall boundary condition where the velocity-potential of a ghost cell is modified by an analytic method *** to the characteristics of the Cartesian grids,the Kutta condition is applied by specially computing the gradients on Kutta-faces without directly assigning the potential jump to cells adjacent wake faces,which can significantly improve the solution converging *** feasibility and accuracy of the proposed method are validated by several typical cases of sub/transonic flows around an ONERA M6 wing,a DLR-F4 wing-body,and an unconventional figuration of a blended wing body（BWB）.The validation cases demonstrate a fast convergence with fully automatic grid treatment and computation,and the results suggest its capacity in application for aircraft conceptual design.

关键词： Cartesian grids CUT-cell Finite volume method Full potential equation Grid adaptation Kutta condition Non-penetration condition

Flight trajectory optimization of sun-tracking solar aircraft under the constraint of mission region

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Chinese Journal of Aeronautics 2021年第11期34卷 140-153页

作者： Mingjian WU Zhiwei SHI tianhang XIAO Haisong ANG School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The optimal yawing angle of sun-tracking solar aircraft is tightly related to the solar azimuth angle,which results in a large arc flight path to dynamically track the sun ***,the limited detection range of payload usually requires solar aircraft to loiter over areas of interest for persistent surveillance *** large arc sun-tracking flight may cause the target area on the ground to be outside the maximum coverage area of *** present study therefore develops an optimal flight control approach for planning the flight path of sun-tracking solar aircraft within a mission *** proposed method enables sun-tracking solar aircraft to maintain the optimal yawing angle most of the time during daylight flight,except when the aircraft reverses its direction by turning *** a circular region with a mission radius of 50km,the optimal flight trajectory and controls of an example K-shaped sun-tracking solar aircraft are investigated *** demonstrate the effectiveness of the proposed approach to optimize the flight path of the sun-tracking aircraft under the given circular region while maximizing the battery input ***,the effects of varying the mission radius on energy performance are explored *** has been proved that both net energy and energy balance remain nearly constant as the radius constraint varies,which enables the solar aircraft to achieve perpetual flight at almost the same latitude as the large arc *** method and results presented in this paper can provide reference for the persistent operation of sun-tracking solar aircraft within specific mission areas.

关键词： Energy performance Mission region Optimal yawing angle Perpetual operation Sun-tracking solar aircraft Trajectory optimization

Flight mechanism and design of biomimetic micro air vehicles

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Science China(Technological Sciences) 2009年第12期52卷 3722-3728页

作者： ANG HaiSong XIAO tianhang DUAN WenBo Research Center of Micro Air Vehicle Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper summaries the investigations on natural flyers and development of bio-mimetic micro air vehicles(MAVs)at NUAA,China,where the authors have led a group to conduct research for a decade. The investigations include the studies of low Reynolds number aerodynamics,unsteady computational fluid dynamics and flight control for the fixed-wing MAVs,the bird-like MAVs,the dragonfly-like MAVs and the bee-like MAVs.

关键词： biomimetics micro air vehicles aerodynamics configuration design

Facile interfacial synthesis of gold micronails with adjustable length and roughness and their superior SERS properties for the detection of p-aminothiophenol Author links open overlay panel

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Particuology 2024年第8期91卷 333-340页

作者： Hang Li Kaisheng Yao tianhang Liu Weiwei Lu School of Chemistry and Chemical Engineering Henan University of Science and TechnozlogyLuoyang471023China School of Physics and Engineering Henan University of Science and TechnologyLuoyang471023China

Au hierarchical architectures with special morphology and structures are strongly desired in varied ***,a simple synthesis method was developed for the one-step preparation of Au micronails(MNs)at the planar liquid-liquid interface under mild *** well-defined Au MNs were grown and constructed at CHCl_(3)-H_(2)O interface at room temperature using aniline in CHCl_(3)as reducing agent and HAuCl_(4)in H_(2)O as precursor and no surfactant or seed is *** intriguing Au MNs with rough surface consist of big heads and thin rods,just like iron nails in ***,through simple changing the reagent concentrations,the length and surface roughness of Au MNs can be adjusted *** effects of a series of factors on the morphology and structure of the products are studied in *** p-aminothiophenol as a molecular probe,the as-obtained Au MNs all exhibit dramatically improved surface enhanced Raman scattering sensitivity and high reproducibility,the enhancement factor and limit of detection of Au MNs are 5.4×10^(5)and 1.0×10^(-10),respectively.

关键词： Au micronails Liquid-liquid interface synthesis Surface enhanced Raman scattering P-aminothiophenol

Multi-objective optimal design for AC filters in high voltage direct current system based on improved multi-objective evolutionary algorithm based on decomposition

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High Voltage 2023年第3期8卷 492-503页

作者： Fan Shi Honghua Wang tianhang Lu Jiawei Huang Chengliang Wang College of Energy and Electrical Engineering Hohai UniversityNanjingJiangsuChina Jiangsu Frontier Electric Technology Co. LtdNanjingJiangsuChina

A triple-objective optimal design method for AC filters in high voltage direct current(HVDC)system based on an improved multi-objective evolutionary algorithm based on decomposition(MOEA/D)is proposed.A triple-objective optimisation mathematical model including total harmonic distortion(THD)on AC side voltage,investment cost of AC filters and telephone harmonic form factor(THFF)is *** improved MOEA/D is proposed to realise the triple-objective optimal design for AC filters more *** improved MOEA/D adds a particular mutation operator,which can not only to prevent MOEA/D from getting stuck at local optimum but also accelerate the convergence to the optimum solution while the algorithm approaches the neighbourhood of the optimum solution.A three-dimensional fuzzy evaluation system is designed to select the optimum solution of the triple-objective optimisation.A case of±500 kV HVDC system is *** the±500 kV HVDC system as the prototype system,a dynamic simulation experimental platform of the rectification system of the direct current transmission system with AC filters is designed and established based on the similarity *** the simulation and experimental results verify that the proposed method have excellent performance.

关键词： MOEA/D system optimal

Impact of exterior electron emission on the self-sustaining margin of hollow cathode discharge

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Plasma Science and Technology 2020年第9期22卷 2-11页

作者： tianhang MENG Zhongxi NING Daren YU Harbin Institute of Technology Harbin 150001.People's Republic of China

Hollow cathode researches used to focus on the inner cavity or downstream plume,however,rarely on the gap between the throttling orifice plate and the keeper plate(T-K gap),which was found to impact the self-sustaining margin of hollow cathode discharge in this *** the lower margin,the main power deposition and electron emission and ionization regions would migrate from inner cavity and downstream plume to the T-K gap,in which case,the source and destination of each m A current therein matter for the self-sustaining *** the metal surfaces in the T-K gap with emissive materials proved effective in lowering the lower margin by supplementing auxiliary thermionic emission,compensating electron loss on cold absorbing walls and suppressing discharge *** doing so,the lower margin of a 4 A hollow cathode was lowered from 1 to 0.1-0.2 A,enabling it to couple with low power Hall thruster without extra keeper current.

关键词： hollow cathode self-sustained discharge secondary electron emission ionization oscillations thermionic emission

Aerodynamic characteristics of co-flow jet wing with simple high-lift devices

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Chinese Journal of Aeronautics 2022年第10期35卷 67-83页

作者： Zhenhao ZHU tianhang XIAO Haolin ZHI Shuanghou DENG Yujin LU College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Numerical investigations are conducted to explore the aerodynamic characteristics of three-dimensional Co-Flow Jet(CFJ) wing with simple high-lift devices during low-speed takeoff and landing. Effects of three crucial parameters of CFJ wing, i.e., angle of attack, jet momentum and swept angle, are comprehensively examined. Additionally, the aerodynamic characteristics of two CFJ configurations, i.e., using open and discrete slots for injection, are compared. The results show that applying CFJ technique to a wing with simple high-lift device is able to generate more lift,reduce drag and enlarge stall margin with lower energy expenditure due to the super-circulation effect. Increasing the jet intensity can reduce the drag significantly, which is mainly contributed by the reaction jet force. The Oswald efficiency factor is, in some circumstances, larger than one,which indicates the potential of CFJ in reducing induced drag. Compared with clean wing configuration, using CFJ technique allows the aerodynamic force variation less sensitive to the swept angle, and such phenomenon is better observed for small swept angle region. Eventually, it is interesting to know that the discrete slotted CFJ configuration demonstrates a promising enhancement in aerodynamic performance in terms of high lift, low drag and efficiency.

关键词： Active flow control Co-flow jet Continuous injection Discrete injection slot Simple high-lift device