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A survey of safety separation management and collision avoidance approaches of civil UAS operating in integration national airspace system

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Chinese Journal of Aeronautics 2020年第11期33卷 2851-2863页

作者： Xiangmin guan Renli LYU Hongxia SHI Jun chen Department of General Aviation Civil Aviation Management Institute of ChinaBeijing 100102China General Aviation Institute of Zhejiang JianDe Hangzhou 311600China School of Engineering and Materials Science Queen Mary University of LondonLondon E14NSUnited Kingdom

Recent years have witnessed a booming of the industry of civil Unmanned Aircraft System(UAS).As an emerging industry,the UAS industry has been attracting great attention from governments of all countries and the aviation *** are highly digitalized,informationized,and intelligent;therefore,their integration into the national airspace system has become an important trend in the development of civil ***,the complexity of UAS operation poses great challenges to the traditional aviation regulatory system and technical *** to prevent collisions between UASs and between UAS and manned aircraft to achieve safe and efficient operation in the integrated operating airspace has become a common challenge for industry and academia around the *** recent years,the international community has carried out a great amount of work and experiments in the air traffic management of UAS and some of the key *** paper attempts to make a review of the UAS separation management and key technologies in collision avoidance in the integrated airspace,mainly focusing on the current situation of UAS Traffic Management(UTM),safety separation standards,detection system,collision risk prediction,collision avoidance,safety risk assessment,etc.,as well as an analysis of the bottlenecks that the current researches encountered and their development trends,so as to provide some insights and references for further research in this ***,this paper makes a further summary of some of the research highlights and challenges.

关键词： Air transportation Collision avoidance Safety Separation control Unmanned aircraft system

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Non-FDG PET imaging of brain tumors

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Nuclear Science and Techniques 2007年第3期18卷 154-158页

作者： HUANG Zemin guan Yihui zuo Chuantao ZHANG Zhengwei XUE Fangping LIN Xiangtong PET Center Huashan Hospital Fudan University Shanghai 200235 China

Due to relatively high uptake of glucose in the brain cortex, the use of FDG PET imaging is greatly limited in brain tumor imaging, especially for low-grade gliomas and some metastatic tumours. More and more tracers with higher specificity were developed lately for brain tumor imaging. There are 3 main types of non-FDG PET tracers: amino acid tracers, choline tracers and nucleic acid tracers. These tracers are now widely applied in many aspects of brain tumor imaging. This article summarized the general use of non-FDG PET in different aspects of brain tumor imaging.

关键词：脑肿瘤正电子发射成像大脑皮层放射疗法

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Transaction or Membership?Impact on On-Demand Delivery Service Platforms'Profits,Consumer Surplus,and Labor Welfare

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Journal of Systems Science and Systems Engineering 2022年第5期31卷 563-593页

作者： Danna chen Yongwu Zhou Xinxin guan Xiaogang Lin School of Business Administration South China University of TechnologyGuangzhou 510640P.R.China School of Management Guangdong University of TechnologyGuangzhou 510520P.R.China

In recent years,two pricing policies are commonly adopted by on-demand delivery service platforms(e.g,Meituan PaoTui and Costco)that provide delivery services to heterogeneous customers via self-scheduling *** called"transaction-based"pricing policy(TBPP)allows the platforms to determine a per-service wage paid to providers and a price charged to customers for each *** other one called"membership-based"pricing policy(MBPP)also allows the platforms to announce a wage paid to providers but charge customers a membership fee for using an unlimited number of the services in a certain period(e.g.,one month).This paper considers an on-demand delivery service platform with self-scheduling providers and two classes of customers(i.e.,regular and frequent customers).We aim to analyze and compare the platform's profits and welfare performances generated by the two pricing *** the number of regular customers and their preference for TBPP equal the number of frequent customers and their preference for MBPP,respectively,we show that compared with the MBPP,employing the TBPP is beneficial for the platform but is detrimental for customers and ***,adopting the MBPP(TBPP)can simultaneously benefit the platform,customers and providers if frequent customers'preference for MBPP is higher(lower)than regular customers'preference for TBPP or the number of frequent customers is larger(less)than regular customers.

关键词： On-demand delivery service platforms pricing policies profit consumer surplus labor welfare

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A preliminary analysis and discussion of the condominium building collapse in surfside,Florida,US,June 24,2021

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Frontiers of Structural and Civil Engineering 2021年第5期15卷 1097-1110页

作者： Xinzheng LU Hong guan Hailin SUN Yi LI Zhe ZHENG Yifan FEI Zhi YANG Lingxiao zuo Key Laboratory of Civil Engineering Safety and Durability of Ministry of Education Tsinghua UniversityBeijing 100084China School of Engineering and Built Environment Griffith University Gold Coast CampusQueensland 4222Australia China Architecture Design&Research Group Co. LtdBeijing 100044China Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit Beijing University of TechnologyBeijing 100124China

On June 24,2021,a 40-year-old reinforced concrete flat plate structure building in Miami suffered a sudden partial *** study analyzed the overall performance and key components of the collapsed building based on the building design codes(ACI-318 and GB 50010).Punching shear and post-punching performances of typical slabcolumn joints are also studied through the refined finite element *** collapse process was simulated and visualized using a physics *** way of these analyses,weak design points of the collapsed building are *** differences between the reinforcement detailing of the collapsed building and the requirements of the current Chinese code are discussed,together with a comparison of the punching shear and post-punching *** simulated collapse procedure and debris distribution are compared with the actual collapse scenes.

关键词： progressive collapse flat plate simulation punching

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Retrieval of Snow Depth on Sea Ice in the Arctic Using the FengYun-3B Microwave Radiation Imager

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Journal of Ocean University of China 2019年第3期18卷 580-588页

作者： LI Lele chen Haihua guan Lei College of Information Science and Engineering Ocean University of China

Snow on sea ice is a sensitive indicator of climate change because it plays an important role regulating surface and near surface air temperatures. Given its high albedo and low thermal conductivity, snow cover is considered a key reason for amplified warming in polar regions. This study focuses on retrieving snow depth on sea ice from brightness temperatures recorded by the Microwave Radiation Imager(MWRI) on board the FengYun(FY)-3 B satellite. After cross calibration with the Advanced Microwave Scanning Radiometer-EOS(AMSR-E) Level 2 A data from January 1 to May 31, 2011, MWRI brightness temperatures were used to calculate sea ice concentrations based on the Arctic Radiation and Turbulence Interaction Study Sea Ice(ASI) algorithm. Snow depths were derived according to the proportional relationship between snow depth and surface scattering at 18.7 and 36.5 GHz. To eliminate the influence of uncertainties in snow grain sizes and sporadic weather effects, seven-day averaged snow depths were calculated. These results were compared with snow depths from two external data sets, the IceBridge ICDIS4 and AMSR-E Level 3 Sea Ice products. The bias and standard deviation of the differences between the MWRI snow depth and IceBridge data were respectively 1.6 and 3.2 cm for a total of 52 comparisons. Differences between MWRI snow depths and AMSR-E Level 3 products showed biases ranging between-1.01 and-0.58 cm, standard deviations from 3.63 to 4.23 cm, and correlation coefficients from 0.61 to 0.79 for the different months.

关键词： MWRI AMSRE brightness temperature snow depth inter-sensor calibration sea ice concentration

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Leave or Stay?Antecedents of High-level Talent Migration in the Pearl River Delta Megalopolis of China:from a Perspective of Regional Differentials in Housing Prices

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Chinese Geographical Science 2023年第6期33卷 1068-1081页

作者： SHEN chen WANG Yang zuo Jian Raufdeen RAMEEZDEEN School of Civil Engineering Wuhan UniversityWuhan430072China School of Architecture&Built Environment University of AdelaideAdelaide5005Australia School of Natural and Built Environments University of South AustraliaAdelaide5001Australia

Rapid urbanization and population growth have triggered an increase in urban housing demand and rising housing prices,which can influence the migration intention of high-level *** work within the literature has focused more on the migration of the general ***,antecedents of migration intention and the impact of housing prices on the migration of high-level talents remain ***,based on the push-pull theory,this study investigates the influencing factors of talent migration intention and explores the role of housing *** study reveals a complex mechanism underlying migration decisions by using logistic regression models and survey data of high-level talents in the Pearl River Delta(PRD)megalopolis of *** results indicate that:1)in high house-price regions,social integration is the primary push factor,and the main factors for retaining talents are the expectation of future work and intimate family relationships;2)in medium house-price regions,the main factors that attract talents are the current salary level and close family ties;3)in low house-price regions,living convenience is a determining factor in retaining *** study provides a new perspective for talent mobility research and offers valuable inputs for retaining and attracting talents in different economic development *** are of great significance for formulating talent introduction policies and forming a new pattern of rational spatial docking and effective allocation of human resources.

关键词： destination choice migration intention high-level talents house-price pressure push-pull theory the Pearl River Delta megalopolis of China

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Reactive Power Multi-objective Optimization for Multi-terminal AC/DC Interconnected Power Systems Under Wind Power Fluctuation

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CSEE Journal of Power and Energy Systems 2020年第3期6卷 630-637页

作者： Qian Hui Yun Teng Hao zuo Zhe chen Shenyang University of Technology Shenyang 110870China Aalborg University Aalborg 9220Denmark

In view of the reactive power coordination difficulties caused by reactive power strong coupling,the provincial power grids in the interconnected system are formed by the multi-AC/DC *** power channels are under the conditions of large-scale long-distance transmission of wind power and other forms of renewable power *** AC-DC hybrid power flow equation of the interconnected system,including the AC-DC tie lines,is presented in this paper,along with the robust dynamic evolutionary optimization of the reactive power system in interconnected systems under fluctuating and uncertain wind power ***,the rapid collaborative optimization of reactive power flow and the exchange of reactive power between tie lines between provincial power grids are *** analysis was made by taking four interconnected large-scale provincial power grids of Eastern Mongolia,Jilin,Liaoning and Shandong as an *** simulation results demonstrate the effectiveness and superiority of the proposed reactive power dynamic multi-objective optimization method for interconnected power grids.

关键词： Multi-objective robust evolution multi terminal AC/DC interconnection reactive power optimization wind power transmission

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A Proactive Selection Method for Dynamic Access Points Grouping in User-centric UDN

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China Communications 2021年第4期18卷 153-165页

作者： Bo Hu Fangxia zuo Chuan’anWang Shanzhi chen State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China Department of Computer Science Anhui Science and Technology UniversityAnhui 233100China State Key Laboratory of Wireless Mobile Communications China Academy of Telecommunication TechnologyBeijing 100191China

Network densification is a promising solution to fulfill network capacity requirement and transmission rate for beyond 5G and 6G wireless ***-dense network(UDN)integrates heterogeneous network resources and coordinates technologies on quality of service controlling,to provide users with flexible ***,dense deployment reduces coverage radius of the cell,resulting in an increase on handover frequency,which makes a serious impact on service *** this paper,we propose a proactive selection method for dynamic access points grouping(DAPGing)in accordance with“user-centric”philosophy,which selects target Access Points(AP)and reduces handover times to ensure communication *** method includes two criteria:1)the user’s sojourn time,which is determined by analyzing the AP coverage area;2)neighbor relationship between APs,which is determined by coverage area and signal strength characteristics between neighboring ***,candidate APs become the proactive selected ones to update the AP *** geometry is used to build system model and performance metrics are analyzed,including AP group coverage probability and average update *** analysis shows that the proposed proactive selection method brings similar coverage probability to traditional handover method,while average update frequency is reduced more than 20%selection criteria.

关键词： proactive selection user-centric ultradense network stochastic geometry model

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Carbon Isotope from Shallow Marine System in North China:Implications for Stratigraphical Correlation and Sea-Level Changes in Cambrian

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Journal of Earth Science 2023年第6期34卷 1777-1792页

作者： Jingxun zuo Xuejian Zhu Yonglin chen Wenjian Zhai Henan Institute of Geological Survey Zhengzhou 450001China Nanjing Institute of Geology and Paleontology Chinese Academy of SciencesNanjing 210008China

Cambrian System at the Shatan Section in northern Henan,North China,consists of sedimentary successions of tidal flat and shallow-water carbonate platform *** of carbon isotope(δ^(13)C_(carb))from this section reveals five positive δ^(13)C_(carb)(P_(st-1)-P_(st-5))and five negative δ^(13)C_(carb) excursions(N_(st-1)-N_(st-5)).In the positive excursions,δ^(13)C_(carb) rises to 0.88‰,1.05‰,2.04‰,1.00‰ and 2.97‰,respectively,while in the negative excursions δ^(13)C_(carb) drops to -8.00‰,-3.50‰,-1.00‰,-0.33‰ and around -2.00‰,*** the basis of chronostratigraphy of Cambrian,the most remarkable carbon isotope excursions can be correlated regionally and *** addition,one second-order and ten third-order sequences have been recognized at this *** third-order sequences and chemostratigraphy indicates that carbonates from the basal part of the transgression system tract(TST)and the upper part of the high-water system(LHST)generally have lighter δ^(13)C_(carb) values,whereas massive carbonates with microbialite from the lower part of the high-water system tract(EHST)usually have heavier δ^(13)C_(carb) *** association of δ^(13)C_(carb) values with sea-level fluctuations suggests that the positive carbon isotope excursions or high δ^(13)C_(carb) values may have been caused by an increase in the marine primary productivity in response to maximum seawater flooding during the transgression.

关键词： carbon isotope sedimentary rocks sea-level change shallow-water Cambrian System stratigraphy North China

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A Surrogate Model for a CAES Radial Inflow Turbine with Test Data-Based MLP Neural Network Algorithm

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Journal of Thermal Science 2023年第6期32卷 2081-2092页

作者： WANG Xing ZHU Yangli LI Wen zuo Zhitao chen Haisheng National Energy Large Scale Physical Energy Storage Technologies R&D Center(Bijie) Bijie551712China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing101408China

It is usually to conduct a full-scale three-dimensional flow analysis for a radial turbine to find a way to increase the efficiency of a Compressed Air Energy Storage(CAES)***,long solving time and huge consumption of computing resources become a major obstacle to the ***,in present study,a surrogate model with test data-based multi-layer perceptron(MLP)Neural Network is proposed to overcome the *** of complex flow field solving process,it provides reliable turbine aerodynamic performance and flow field distribution characteristics in a short solution time by“learning the measurement results”.The validation results illustrated that the predicted maximum relative errors of isentropic efficiency,corrected mass flow rate and corrected power are only 0.03%,0.22%and 0.26%*** predicted flow distribution parameters in chamber,shroud cavity and outlet region of rotor are also basically consistent with the experimental *** the chamber,it can be found that a pressure stagnation point is observed at circumferential angle of 270°when total pressure ratio is *** the shroud cavity,obvious pressure variation is found near outlet of shroud cavity which although labyrinth seals *** outlet of rotor,obvious variations of velocity and pressure are found in the 0.0–0.4 and 0.6–0.8 of blade *** the same time,obvious variations of velocity and pressure are found in the 0.0–0.4 and 0.6–0.8 of blade height and this is because the influence of upper passage vortex,lower passage vortex and end wall secondary *** present study can provide further reference for the dynamic performance evaluation of CAES radial inflow turbine.

关键词： CAES surrogate model radial inflow turbine MLP neural network

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