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Joint Subcarrier and Power Allocation for Multi-UAV Systems

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China Communications 2019年第1期16卷 47-56页

作者： xin Guan Yang Huang Qingjiang shi College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space(NUAA) Ministry of Industry and Information Technology School of Software Engineering Tongji University

This paper investigates subcarrier and power allocation in a multi-UAV OFDM *** study considers a practical scenario,where certain subcarriers are unavailable for dynamic subcarrier allocation,on account of pre-allocation for burst *** first propose a novel iterative algorithm to jointly optimize subcarrier and power allocation,so as to maximize the sum rate of the uplink transmission in the multiUAV OFDM *** key idea behind our solution is converting the nontrivial allocation problem into a weighted mean square error(MSE) *** this means,the allocation problem can be solved by the alternating optimization ***,aiming at a lower-complexity solution,we propose a heuristic allocation scheme,where subcarrier allocation and transmit power allocation are separately *** the heuristic scheme,closedform solution can be obtained for power *** results demonstrate that in the presence of stretched subcarrier resource,the proposed iterative joint optimization algorithm can significantly outperform the heuristic scheme,offering a higher sum rate.

关键词： Multi-UAV OFDM subcarrier allocation power allocation alternating optimization weighted MSE

Extremal P_(8)-Free/P_(9)-Free Planar Graphs

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Journal of the Operations Research Society of China 2023年第3期11卷 451-457页

作者： Yong-xin Lan Yong-Tang shi School of Science Hebei University of TechnologyTianjin300401China Center for Combinatorics and LPMC Nankai UniversityTianjin300071China

An H-free graph is a graph not containing the given graph H as a *** is well known that the Turán number ex(n,H)is the maximum number of edges in an H-free graph on n *** on this definition,we define ex_(P)(n,H)to restrict the graph classes to planar graphs,that is,ex_(P)(n,H)=max{|E(G)|:G∈G,where G is a family of all H-free planar graphs on n ***,we have ex_(P)(n,H)=3n−6 if the graph H is not a planar *** study is initiated by Dowden(J Graph Theory 83:213–230,2016),who obtained some results when H is considered as C_(4)or C_(5).In this paper,we determine the values of ex_(P)(n,Pk)with k∈{8,9},where Pk is a path with k vertices.

关键词： Turán number Extremal graph Planar graph

Do large-scale farmers use more pesticides? Empirical evidence from rice farmers in five Chinese provinces

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Journal of Integrative Agriculture 2020年第2期19卷 590-599页

作者： QIN shi-le LU xin-ye Institute of Agricultural Economics and Development Chinese Academy of Agricultural Sciences

It is of great theoretical and practical significance to understand the rules of the differences in pesticide use behaviors between large-scale and small-scale farmers,so as to regulate the behavior of farmers differently and improve the quality and safety of *** overall pesticide use behavior of large-scale farmers was characterized by large doses and high application frequency,while that of small-scale farmers was characterized by small doses and low application *** econometric test showed that(i)the proportion of staple food ration has a significant negative impact on the single dose exceeding the standard and pesticide application frequency of small-scale farmers,and the increase of the proportion of staple food ration will reduce the demand among small-scale farmers for pesticides;(ii)yield effect has a greater impact on the frequency of pesticide application by large-scale farmers,and the large yield effect will increase the frequency of pesticide application among large-scale ***,in pesticide use behaviors,large-scale farmers should reduce pesticide quantity and increase efficiency,while small-scale farmers improve the level of plant protection.

关键词： pesticide use behavior rice farmers scale management

Crystallization Behavior and Magnetic Properties of(Fe0.6Co0.4)86Hf7B6Cu1 Alloy

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材料热处理学报 2004年第5期25卷 201-203页

作者： LIANGXiu-bing FERENCJ. KULIKT. XUBin-shi FacultyofMaterialsScienceandEngineering WarsawUniversityofTechnologyWarsawPoland／NationalKeyLaboratoryforRemanufacturingtheAcademyofArmoredForcesEngineeringBeijingChina FacultyofMaterialsScienceandEngineering WarsawUniversityofTechnologyWarsawPoland NationalKeyLaboratoryforRemanufacturing theAcademyofArmoredForcesEngineeringBeijingChina

***.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution for Fe can enhance the curie temperature of amorphous alloy (Tc = 630 °C) and improve the magnetization of nanocrystalline alloy at high temperature ( = 1.56T at 550 °C). After annealing amorphous precursor at 550 °C for 1 hour, the optimum nanocrystalline alloy can be obtained which shows the local minimum coercivity ( = 16 A/m). The coercivity increases with the increase of annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization. Furthermore, additions of Hf and B elements reduce the melting temperature of the alloy studied comparing with the Fe-Co binary alloy.

关键词：纳米结晶软磁性材料结晶过程等温退火矫顽磁性 (Fe0.6Co0.4)86Hf7B6Cu1合金

On d-row(Column) Antimagic Matrices and Subset Partitions

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Acta Mathematicae Applicatae Sinica 2021年第1期37卷 192-200页

作者： Zhi-he LIANG shi-xin LIANG School of Mathematical Science Hebei Normal UniversityShijiazhuang 050024China ABB Electric Transmission Systems Co.LTD Beijing 100020China

An m×k matrix is said to be a d-row(column)antimagic matrix if its row-sums(column-sums)form an arithmetic progression with a difference *** goal of this paper is to obtain the existence theorems and construction methods of some d-row(column)antimagic *** these results we give the necessary and sufficient condition for the existence of an(m,d)-partition of[1,mk].

关键词： matrix d-row(column)antimagic matrix subset partition

A New Boundary of the Mapping Class Group

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Acta Mathematica Sinica,English Series 2023年第5期39卷 885-903页

作者： Li xin LIU Yao Zhong shi School of Mathematics Sun Yat-sen UniversityGuangzhou 510275P.R.China

Based on the action of the mapping class group on the space of measured foliations,we construct a new boundary of the mapping class group and study the structure of this *** an application,for any point in Teichmüller space,we consider the orbit of this point under the action of the mapping class group and describe the closure of this orbit in the Thurston compactification and the Gardiner-Masur compactification of Teichmüller *** also construct some new points in the Gardiner-Masur boundary of Teichmüller space.

关键词： Mapping class group measured foliation Teichmiller space

Changes in ecological stoichiometry and nutrient resorption in Castanopsis hystrix plantations along an urbanization gradient in the lower subtropics

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Journal of Forestry Research 2021年第6期32卷 2323-2331页

作者： Feifan Li bing Sun Zhaowan shi Nancai Pei Research Institute of Tropical Forestry Chinese Academy of ForestryGuangzhou510520People’s Republic of China

The stoichiometry of carbon,nitrogen and phosphorous in plants can reflect the interactions between plants and their *** interplay between plant nutrients,climatic factors,and soil properties and the underlying regulatory mechanisms are pillars of ecology but remain *** this study of plant C-N-P stoichiometry and nutrient resorption in Castanopsis hystrix groves in three cities(Guangzhou,Zhongshan,and Lechang)that represent an urban-rural gradient in Guangdong Province,South China,we explored potential relationships among NO_(2) concentrations,diameter at breast height(DBH),and resident human *** annual temperature,mean annual precipitation,insolation duration per year,and the human resident population differed significantly among the three *** C-N-P was always highest in suburban Lechang,and the concentration of NO_(2) was highest in urban Guanghzou(55.33±0.67μg m^(-3))and positively correlated with the resident population and leaf N:*** findings suggest that C-N-P stoichiometry of *** was better explained by NO_(2)than by soil C-N-P stoichiometry and that nutrient resorption was better explained by leaf nutrients and DBH than by NO_(2) and soil *** study supports the hypothesis that rapid urbanization influences NO_(2) concentrations and microclimate,which may jointly change the stoichiometry of plant nutrients in the forest ecosystems.

关键词： Ecological stoichiometry Nutrient cycling Plant-environment interaction Subtropical forest Urban–rural gradient

Novel Fault Diagnosis Scheme for HVDC System via ESO

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高电压技术 2007年第11期33卷 88-93页

作者： YAN bing-yong TIAN Zuo-hua shi Song-jiao Department of Automation Shanghai Jiao Tong University Shanghai 200240 China

A novel fault detection and identification(FDI)scheme for HVDC(High Voltage Direct Current Transmission)system was *** was based on the unique active disturbance rejection concept,where the HVDC system faults were estimated using an extended states observer(ESO).Firstly,the mathematical model of HVDC system was constructed,where the system states and disturbance were treated as an extended *** augment HVDC system was established by using the extended state in rectify side and converter side,***,a fault diagnosis filter was established to diagnose the HVDC system faults via the ESO *** evolution of the extended state in the augment HVDC system can reflect the actual system faults and disturbances,which can be used for the fault diagnosis purpose.A novel feature of this approach is that it can simultaneously detect and identify the shape and magnitude of the HVDC faults and ***,different kinds of HVDC faults were simulated to illustrate the feasibility and effectiveness of the proposed ESO based FDI *** with the neural network based or support vector machine based FDI approach,the ESO based FDI scheme can reduce the fault detection time dramatically and track the actual system fault ***'s more important,it needs not do complex online calculations and the training of neural network so that it can be applied into practice.

关键词：高压直流输电系统故障检验与识别故障诊断分支状态观测器

Origin of modern humans in East Asia:clues from the Y chromosome

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Frontiers in Biology 2009年第3期4卷 241-247页

作者： Hong shi bing SU State Key Laboratory of Genetic Resources and Evolution Kunming Institute of Zoology and Kunming Primate Research CentreChinese Academy of SciencesKunming 650223China

East Asia is one of the most important regions for studying modern human origin and evolution.A lot of efforts have been made to detect the genetic diversity and to reconstruct the evolutionary history of East Asians,especially using Y chromosome genetic data,in recent *** Y chromosome data supports the African origin of modern humans in East Asia and the later migration to East Asia through the southern tropic coastline route,and then the northward migration occurred,leading to peopling of the main *** genetic data of the Y chromosome reflects a clear prehistoric evolution and migration course of East *** well,the Y chromosome data of East Asians provides clues to elucidate modern human origins and evolution in the neighboring regions,***,Oceania and the Pacific Islands.

关键词： Y chromosome East Asia modern human origin prehistoric migration