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Distributed velocity-free formation tracking control for clustered UAVs under virtual leader-follower framework

Science China(Technological Sciences) 2024年第5期67卷 1538-1552页

作者： ZHANG ZhaoYu duan HaiBin School of Automation Science and Electrical Engineering Beihang UniversityBeijing100083China

The collective formation control problem of a cluster of rotorcraft unmanned aerial vehicles(UAVs)is investigated in this *** consensus tracking towards formation centroid with following UAVs forming a predefined configuration around the leader is considered as the *** prior studies,the information of the central reference trajectory,which is deemed as a virtual leader in the leader-follower topology,is not directly accessible for partial nodes through the communication ***,a novel distributed formation tracking control scheme is ***,a decentralized saturation observer is employed to estimate the reference acceleration signal of the virtual *** the absence of linear velocity measurement,two sliding manifolds are proposed by introducing the relative discrepancy terms of position and *** a smooth saturation operator in the form of a sigmoid function is applied to generate the command force ***,under the dilemma of constrained capabilities of the airborne sensors equipped on the rotorcrafts,the angular velocity is difficult to *** cascaded auxiliary attitude error systems are established on each rotorcraft system to synthesize the rotating torque with no need to require the angular velocity *** to the strong coupling and nonlinearity of the rotorcraft UAV system,the command angular velocity and the derivatives of command input are hard to *** a continuous nonlinear differentiator is proposed to work with the difficulties in deriving the explicit expression of system ***,a detailed stability analysis is conducted progressively on the angular control loop,reference trajectory observer loop,and the position control loop.A simulation scheme for a cluster of four rotorcraft UAVs tracking sinusoidal trajectory are presented and the formation control results are proven advantageous in comparison with the control protocol in previous literature.

关键词： distributed formation control unmanned rotorcraft clusters velocity-free tracking nonlinear differentiator

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Non-genetic risk factors of Parkinson’s disease: A large meta-analysis and systematic review

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中华医学杂志(英文版) 2024年第15期137卷 1873-1875页

作者： Yin Kangfu Su Weiming Gu Xiaojing Jiang zheng duan Qingqing Cao Bei Chi Liyi Chen Yongping Department of Neurology West China Hospital Sichuan University Chengdu Sichuan China Department of Mental Health Center West China Hospital Sichuan University Chengdu Sichuan China Department of Neurology First Affiliated Hospital of Air Force Military Medical University Xi’an Shaanxi China

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Progress of the bolometer diagnostic system on EAST

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Plasma Science and Technology 2024年第9期26卷 125-132页

作者： Wen WEN Yanmin duan Shanshan PAN Yan chao Songtao MAO Jing QIAN Lingyi MENG Panjun TANG Shiyao LIN Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People’s Republic of China University of Science and Technology of China Hefei 230026People’s Republic of China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060People’s Republic of China

Measurements of the total radiated power and its spatial distribution are crucial for fusion *** the experimental advanced superconducting tokamak(EAST),both the metal foil resistive bolometer and the absolute extreme ultraviolet(AXUV)photodiodes have been used to quantify the radiated *** article introduces the latest improvement of the bolometer diagnostic system on *** also details the successful design and installation of new divertor AXUV cameras,which are dedicated to the investigation of divertor *** shielding components of the bolometer detector have been refined,and the article provides a detailed exposition of the double shielding structures that have been verified as effective in microwave ***,the changes in the radiated power distribution in the divertor region during the plasma detachment process are measured using the divertor AXUV ***,the radiated power measured by the AXUV detector and metal foil resistive bolometer are compared,and different detector performances are presented.

关键词： radiated power bolometer diagnostic microwave shielding plasma detachment sensitivity degradation

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Drogue detection for autonomous aerial refueling via hybrid pigeon-inspired optimized color opponent and saliency aggregation

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Chinese Journal of Aeronautics 2024年第5期37卷 27-38页

作者： Tongyan WU Haibin duan Yanming FAN State Key Laboratory of Virtual Reality Technology and Systems School of Automation Science and Electrical EngineeringBeihang UniversityBeijing 100083China Virtual Reality Fundamental Research Laboratory Department of Mathematics and TheoriesPeng Cheng LaboratoryShenzhen 518000China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

Drogue detection is one of the challenging tasks in autonomous aerial refueling due to the requirement for accuracy and *** detection based on image intrinsic cues can achieve fast detection,but with poor *** studies reveal that optimization-based methods provide accurate and quick solutions for saliency *** paper presents a hybrid pigeon-inspired optimization method,the optimized color opponent,that aims to adjust the weight of color opponent channels to detect the drogue *** can optimize the weights in the selected aerial refueling scene offline,and the results are applied for drogue detection in the scene.A novel algorithm aggregated by the optimized color opponent and robust background detection is presented to provide better precision and *** results on benchmark datasets and aerial refueling images show that the proposed method successfully extracts the saliency region or drogue and exhibits superior performance against the other saliency detection methods with intrinsic *** algorithm designed in this paper is competent for the drogue detection task of autonomous aerial refueling.

关键词： Autonomous aerial refueling Drones Hybrid pigeon-inspired optimization Color opponent Saliency detection Saliency aggregation

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A Deep-Learning and Transfer-Learning Hybrid Aerosol Retrieval Algorithm for FY4-AGRI:Development and Verification over Asia

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Engineering 2024年第7期38卷 164-174页

作者： Disong Fu Hongrong Shi Christian AGueymard Dazhi Yang Yu zheng Huizheng Che Xuehua Fan Xinlei Han Lin Gao Jianchun Bian Minzheng duan Xiangao Xia Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 10029China Key Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Solar Consulting Services ColebrookNH 03576USA School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150006China State Key Laboratory of Severe Weather&Key Laboratory of Atmospheric Chemistry Institute of Atmospheric Composition and Environmental MeteorologyChinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081China National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing100085China Key Laboratory of Compound and Chained Natural Hazards Dynamics Ministry of Emergency Management of ChinaBeijing 100085China h National Satellite Meteorological Center China Meteorological AdministrationBeijing 100081China University of Chinese Academy of Sciences Beijing 100049China

The Advanced Geosynchronous Radiation Imager(AGRI)is a mission-critical instrument for the Fengyun series of *** acquires full-disk images every 15 min and views East Asia every 5 min through 14 spectral bands,enabling the detection of highly variable aerosol optical depth(AOD).Quantitative retrieval of AOD has hitherto been challenging,especially over *** this study,an AOD retrieval algorithm is proposed that combines deep learning and transfer *** algorithm uses core concepts from both the Dark Target(DT)and Deep Blue(DB)algorithms to select features for the machinelearning(ML)algorithm,allowing for AOD retrieval at 550 nm over both dark and bright *** algorithm consists of two steps:①A baseline deep neural network(DNN)with skip connections is developed using 10 min Advanced Himawari Imager(AHI)AODs as the target variable,and②sunphotometer AODs from 89 ground-based stations are used to fine-tune the DNN ***-of-station validation shows that the retrieved AOD attains high accuracy,characterized by a coefficient of determination(R2)of 0.70,a mean bias error(MBE)of 0.03,and a percentage of data within the expected error(EE)of 70.7%.A sensitivity study reveals that the top-of-atmosphere reflectance at 650 and 470 nm,as well as the surface reflectance at 650 nm,are the two largest sources of uncertainty impacting the *** a case study of monitoring an extreme aerosol event,the AGRI AOD is found to be able to capture the detailed temporal evolution of the *** work demonstrates the superiority of the transfer-learning technique in satellite AOD retrievals and the applicability of the retrieved AGRI AOD in monitoring extreme pollution events.

关键词： Aerosol optical depth Retrieval algorithm Deep learning Transfer learning Advanced Geosynchronous Radiation Imager

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Evaluation of the injection and plugging ability of a novel epoxy resin in cement cracks

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Petroleum Science 2024年第2期21卷 1211-1220页

作者： Guang-Yao Leng Wei Yan Hai-Mu Ye Er-Dong Yao Ji-Bin duan zheng-Xian Xu Ke-Pei Li Jing-Ru Zhang Zhong Li State Key Laboratory of Petroleum Resource&Prospecting China University of Petroleum(Beijing)Beijing102249China CNPC Liaohe Oilfield Gas Storage Co.LTD Panjin124000LiaoningChina CNOOC Research Institute Co. Ltd.Beijing100028China

Sustained casing pressure(SCP)is a crucial issue in the oil and gas production *** resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable *** injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation *** study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid *** investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing *** flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in *** results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,*** mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor *** epoxy resin containing 30%curing agent exhibited optimal mechanical *** a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy *** brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and *** tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,*** a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow ***,the injection pressure of cement surged dramatically to 2.61 MPa within 5 *** breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's perme

关键词： Sustained casing pressure Epoxy resin sealant Curing agent Viscosity reducer Mechanical properties Crack sealing

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Atomically dispersed Fe sites on hierarchically porous carbon nanoplates for oxygen reduction reaction

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Journal of Energy Chemistry 2024年第3期90卷 7-15,I0002页

作者： Ruixue zheng Qinglei Meng Hao Zhang Teng Li Di Yang Li Zhang Xiaolong Jia Changpeng Liu Jianbing Zhu Xiaozheng duan Meiling Xiao Wei Xing State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026AnhuiChina Laboratory of Advanced Power Sources Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials&DevicesJiangsu Key Laboratory of Advanced Negative Carbon TechnologiesSoochow UniversitySuzhou 215123JiangsuChina State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina

Developing cost-effective,robust and stable non-precious metal catalysts for oxygen reduction reaction(ORR) is of paramount importance for electrochemical energy conversion devices such as fuel cells and metal-air *** Fe-N-C single atom catalysts(SACs) have been hailed as the most promising candidate due to the optimal binding strength of ORR intermediates on the Fe-N_(4) sites,they suffer from serious mass transport limitations as microporous templates/substrates,i.e.,zeolitic imidazolate frameworks(ZIFs),are usually employed to host the active *** by this challenge,we herein develop a hydrogen-bonded organic framework(HOF)-assisted pyrolysis strategy to construct hierarchical micro/mesoporous carbon nanoplates for the deposition of atomically dispersed Fe-N_(4) *** a design is accomplished by employing HOF nanoplates assembled from 2-aminoterephthalic acid(NH_(2)-BDC) and p-phenylenediamine(PDA) as both soft templates and C,N *** from the structural merits inherited from HOF templates,the optimized catalyst(denoted as Fe-N-C SAC-950) displays outstanding ORR activity with a high half-wave potential of 0.895 V(*** hydrogen electrode(RHE)) and a small overpotential of 356 mV at 10 mA cm^(-2) for the oxygen evolution reaction(OER).More excitingly,its application potential is further verified by delivering superb rechargeability and cycling stability with a nearly unfading charge-discharge gap of 0.72 V after 160 *** dynamics(MD) simulations reveal that micro/mesoporous structure is conducive to the rapid mass transfer of O_(2),thus enhancing the ORR *** situ Raman results further indicate that the conversion of O_(2) to~*O_(2)-the rate-determining step(RDS) for Fe-N-C *** work will provide a versatile strategy to construct single atom catalysts with desirable catalytic properties.

关键词： Fe single atom catalysts Oxygen reduction reaction Mesoporous structure Active sites Zinc-air battery

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Design Optimization and Operating Performance of S-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand Scenarios

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Journal of Thermal Science 2024年第1期33卷 190-206页

作者： YANG Jingze YANG Zhen duan Yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce *** the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand *** addition,the cycle design condition will directly affect the off-design *** this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced *** show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient *** average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient *** multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature *** the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance

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Nanoindentation behavior and creep-induced cracking of long-term crept austenitic steel at 650℃

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Journal of Iron and Steel Research International 2024年第2期31卷 464-474页

作者： Zhen Zhang Yu-hang duan Shuai Wang Jin-shan Chen An-zhe Wang Xiang-yang Mao Yuan-ji Shi Jie Zhang Ming Liu zheng-fei Hu School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing211167JiangsuChina Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Nanjing211167JiangsuChina Jiangsu Wind Power Engineering Technology Center Nanjing210023JiangsuChina Nanjing Vocational University of Industry Technology Nanjing210023JiangsuChina Baoshan Iron&Steel Co. Ltd.Shanghai201900China Fujian Provincial Key Laboratory of Terahertz Functional Devices and Intelligent Sensing School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou350116FujianChina School of Materials Science and Engineering Tongji UniversityShanghai201804China

The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered *** corresponding microstructure was characterized by scanning electron microscopy and transmission electron *** show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the *** M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the *** nanoindentation hardness in grains varies with orientation of the stress *** orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.

关键词： Austenitic steel Creep Nanoindentation Grain orientation Creep-induced cracking

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Exclusive Hypothesis Testing for Cox's Proportional Hazards Model

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Journal of Systems Science & Complexity 2024年第5期37卷 2157-2172页

作者： WU Qiang TONG Xingwei duan Xiaogang School of Statistics Beijing Normal University

Exclusive hypothesis testing is a new and special class of hypothesis testing. This kind of testing can be applied in survival analysis to understand the association between genomics information and clinical information about the survival time. Besides, it is well known that Cox's proportional hazards model is the most commonly used model for regression analysis of failure time. In this paper,the authors consider doing the exclusive hypothesis testing for Cox's proportional hazards model with right-censored data. The authors propose the comprehensive test statistics to make decision, and show that the corresponding decision rule can control the asymptotic Type Ⅰ errors and have good powers in theory. The numerical studies indicate that the proposed approach works well for practical situations and it is applied to a set of real data arising from Rotterdam Breast Cancer Data study that motivated this study.

关键词： Comprehensive test statistics Cox’s proportional hazards model exclusive hypothesis testing right-censored data Type I error

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