检索结果-南通市图书馆

A Study of 10 Rotating Radio Transients Using Parkes Radio Telescope

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第4期24卷 114-123页

作者： Xinhui Ren Jingbo Wang Wenming yan jintao Xie Shuangqiang Wang Yirong Wen Yong Xia Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Institute of Optoelectronic Technology Lishui UniversityLishui 323000China Xinjiang Key Laboratory of Radio Astrophysics Urumqi 830011China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China

Rotating Radio Transients(RRATs)are a relatively new subclass of pulsars that emit detectable radio bursts *** analyzed 10 RRATs observed using the Parkes telescope,with eight of these observed via the ultra-wide-bandwidth low-frequency(UWL)*** measured the burst rate and produced integrated profiles spanning multiple frequency bands for three *** also conducted a spectral analysis on both integrated pulses and individual pulses of three *** of their integrated pulses follow a simple power law,consistent with the known range of pulsar spectral *** average spectral indices of single pulses are-0.9,-1.2,and-1.0 respectively,which are within the known range of pulsar spectral ***,we find that the spreads of single-pulse spectral indices for these RRATs(ranging from-3.5 to+0.5)are narrower compared to what has been observed in other ***,the average spectral index and scatter of single pulses are both relatively *** the remaining five RRATs observed at the UWL receiver,we also provide the upper limits on fluence and flux *** addition,we obtain the timing solution of PSR *** analysis shows that PSRs J1919+1745,J1709-43,and J1649-4653 are potentially nulling pulsars or weak pulsars with sparse strong pulses.

关键词： (stars:)pulsars:general stars:neutron stars:individual(PSRs J1919+1745.1909+0641,0628+0909)

Self-powered stimuli responsive material for dual stimulation of heat and guest molecules

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第2期35卷 590-593页

作者： jintao Men Ke Xu Taiting Sha Lei He yan Xu Jie Mu Tijian Yin Qiong Ye Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics and School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189China

Stimuli-responsive smart materials exhibit reverse chemical/physical changes in response to external stimuli and research on stimuli-responsive smart materials with self-powered properties is still uncultivated ***,we report perovskite crystalline self-powered multiple stimuli-responsive materials triggered by chemical and thermal stimuli.[HMEP]PbI_(3)·(H_(2)O)(1;HMEP is a hydroxytris(1-methylethyl)phosphorus cation)crystallizes in a chiral space group P 21 at 293 K and has the piezoelectric reaction(d_(33)=10 pC/N and output voltage=1 V)of self-powered modes,this value is larger than the value of 3 pC/N for the classical piezoelectric material *** materials can generate energy due to mechanical deformation,and using thermal heating to lose water,[HMEP]PbI_(3)(2)can be obtained.2 crystallizes in the non-centrosymmetric space group,undergoes two reversible phase transitions at 243/255 K and 315/348 K,and shows second harmonic generation ***,2 can return to the hydrated form 1 after absorbing *** work will lay the foundation for self-powered stimuli-responsive compounds and contribute to the construction of novel organic-inorganic hybrid materials with second harmonic generation switching.

关键词： Self-powered Dual stimulation reactive Phase transition SHG switch Organic-inorganic hybrid perovskite

Hierarchical Federated Learning: Architecture, Challenges, and Its Implementation in Vehicular Networks

在线全文

学校读者我要写书评

暂无评论

ZTE Communications 2023年第1期21卷 38-45页

作者： yan jintao CHEN Tan XIE Bowen SUN Yuxuan ZHOU Sheng NIU Zhisheng Tsinghua University Beijing 100084China Beijing Jiaotong University Beijing 100044China

Federated learning(FL)is a distributed machine learning(ML)framework where several clients cooperatively train an ML model by exchanging the model parameters without directly sharing their local *** FL,the limited number of participants for model aggregation and communication latency are two major *** federated learning(HFL),with a cloud-edge-client hierarchy,can leverage the large coverage of cloud servers and the low transmission latency of edge *** are growing research interests in implementing FL in vehicular networks due to the requirements of timely ML training for intelligent ***,the limited number of participants in vehicular networks and vehicle mobility degrade the performance of FL *** this context,HFL,which stands out for lower latency,wider coverage and more participants,is promising in vehicular *** this paper,we begin with the background and motivation of HFL and the feasibility of implementing HFL in vehicular ***,the architecture of HFL is ***,we clarify new issues in HFL and review several existing ***,we introduce some typical use cases in vehicular networks as well as our initial efforts on implementing HFL in vehicular ***,we conclude with future research directions.

关键词： hierarchical federated learning vehicular network mobility convergence analysis

Large eddy simulation study of 3D wind field in a complex mountainous area under different boundary conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第7期25卷 541-556页

作者： yan LI Lei yan Xuhui HE School of Civil Engineering Central South UniversityChangsha410075China National Engineering Research Center for High-speed Railway Construction Changsha410075China Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structures Changsha410075China

Large eddy simulations generally are used to predict 3D wind field characteristics in complex mountainous *** simulation boundary conditions,such as the height and length of the computational domain or the characteristics of inflow turbulence,can significantly impact the quality of *** this study,we examined these boundary conditions within the context of the mountainous terrain around a long-span cable-stayed bridge using a wind tunnel *** sizes of computational domains and turbulent incoming wind velocities were used in large eddy *** results show that when the height of the computational domain is five times greater than the height of the terrain model,there is minimal influence from the top wall on the wind field characteristics in this complex mountainous *** the length of the wake region of the computational domain has negligible effects on the wind *** in the inlet boundary reduces the length of the wake region on a leeward hill with a low slope,but has less impact on the mean wind velocity of steep hills.

关键词： Large eddy simulation(LES) Spectral representation method Recycling method High mountainous canyon Wind characteristics Atmospheric boundary layer Computational domain

Towards Data-Driving Multi-View Evaluation Framework for Scratch

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2024年第2期29卷 517-528页

作者： Xiaolin Chai yan Sun yan Gao Department of Computer Science Beijing University of Posts and TelecommunicationBeijing 100876China Intellectual Property Institute Shandong Polytechnic CollegeJining 272067China

As one of the most popular visual programming languages,Scratch has a lot of evaluation around *** evaluation can help programmers understand their projects *** the same time,it can also provide a reference for them to browse other projects in the online *** of the existing evaluations on Scratch are carried from three perspectives:Computational Thinking(CT)ability,visual presentation aesthetics,and code *** them,the assessment of CT and code quality is mainly carried out from the program script,while the evaluation of visual aesthetics is analyzed from the perspective of image sequences generated by project *** single-view evaluation focuses on the performance of a program in a certain aspect and is *** this paper,we propose a multi-view evaluation framework to integrate various evaluations using different *** quantitatively analyze the assessment of different views driven by *** with overall evaluations that represent human opinions,we analyze their differences and *** experiments,we determine the weights of different integration policies,the proposed multi-view evaluation method can generate evaluation results similar to human opinions.

关键词： Scratch Computational Thinking(CT) visual aesthetic static analysis integration policy machine learning

Forward to the Special Topic on“Solving Differential Equations with Deep Learning”

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第2期37卷 389-390页

作者： yan Zhenya Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China

The concept of artificial intelligence(AI)was first presented at the Dartmouth SummerResearch Project on AI hosted by McCarthy and Minsky in *** that,the developmentof AI has experienced ups and downs due to some limited conditions including intelligentcomputing techniques,computer and hardware and software^([1,2]).In particular,with the rapidof deep artificial neural networks,machine learning(ML)and deep learning(DL)techniques^([3,4])have been applied in many fields of science and engineering,including machine translation,image recognition,genomics,scientific computing and atmospheric science,etc^([5]).

关键词： has artificial hardware

在线全文

学校读者我要写书评

暂无评论

播期和播深对冬小麦越冬前生长性状的影响

农业机械学报 2022年第2期53卷 327-335页

作者：闫锦涛冯利平李扬陈先冠余卫东中国农业大学资源与环境学院北京100193 中国气象局河南省农业气象保障与应用技术重点开放实验室郑州450003

为评价播期和播深对冬小麦越冬前生长性状的影响,以农大211冬小麦为试验材料,于2015—2017年在中国农业大学北京上庄实验站进行了4个播期水平(9月23日、10月3日、10月13日和10月23日)、3个播深水平(2、4、6 cm)的随机区组大田试验,探究... 详细信息

为评价播期和播深对冬小麦越冬前生长性状的影响,以农大211冬小麦为试验材料,于2015—2017年在中国农业大学北京上庄实验站进行了4个播期水平(9月23日、10月3日、10月13日和10月23日)、3个播深水平(2、4、6 cm)的随机区组大田试验,探究不同栽培措施对越冬前冬小麦各生长指标(单株叶面积、主茎叶龄、分蘖数、地上部干物质量、分蘖节入土深度、地中茎长度和株高)的影响。并于2016年和2018年开展梯度播种试验,设置不同播期(2016年9月23日、10月3日、10月13日和2018年10月23日、11月3日),对分蘖节入土深度进行定量化模拟。结果表明:随着播期推迟,单株叶面积、主茎叶龄、分蘖数和地上部干物质量均显著减少(P<0.05),地中茎长度和株高随着播种深度的增加逐渐增加。播期、播深、播期与播深的交互效应均对冬小麦分蘖节入土深度有显著影响,冬小麦分蘖节入土深度与越冬前积温为负相关的线性关系,随着播期推迟分蘖节入土深度逐渐增加,冬小麦分蘖节入土深度和播深呈对数曲线规律。依据梯度播种试验数据进行分蘖节入土深度的模拟,建立了分蘖节入土深度与越冬前有效积温和播种深度的定量关系。研究结果对于评价冬小麦地上地下部性状、制定防冻保苗措施具有重要意义。

关键词：冬小麦播期播深生长性状分蘖节入土深度抗寒性

维普期刊数据库博看期刊

Electromagnetic characteristic analysis and design of a linear motor used for ultra-high-speed EMS maglev train

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第6期67卷 1957-1973页

作者： GAO Han SHI TingNa GAO XinMai LEI yanXiao yan Dong GUO Liyan yan yan College of Electrical Engineering Zhejiang UniversityHangzhou310027China Zhejiang University Advanced Electrical Equipment Innovation Center Hangzhou311107China State Key Laboratory of High-speed Maglev Transportation Technology Qingdao266100China CRRC Qingdao Sifang Co.Ltd. Qingdao266111China

The operating speed of the commercial electromagnetic suspension(EMS)maglev train has been over 430 km/h,making it the fastest means of land *** the increasing demands of people traveling,it is necessary to further improve the operating speed of maglev *** to examine whether the existing EMS system can meet the requirements of ultra-highspeed operation(more than 600 km/h),the electromagnetic characteristics of an EMS linear motor under the operating speed of 600–1000 km/h fed by a square-wave voltage supply is investigated in this ***,an electromagnetic field model of the EMS system under the square-wave voltage supply is established to investigate its electromagnetic performance,e.g.,the characteristics of phase current,the magnetic flux density,and the electromagnetic ***,the relationship between the harmonic components of the air-gap magnetic flux density and electromagnetic force is investigated using the two-dimensional fast Fourier transform(2D-FFT)to reveal the mechanism of electromagnetic force ***,to address the issues of excessive armature current density and significant electromagnetic force ripple,the linear motor is re-designed by enlarging the stator slot area and reshaping the mover's main magnetic ***,the Taguchi method is used to further improve the electromagnetic characteristics of the linear electric ***,the effectiveness of the proposed optimal design is validated by the finite-element analysis(FEA)based co-simulation.

关键词： ultra-high-speed maglev transportation electromagnetic suspension(EMS) linear motor electromagnetic force ripple suppression

Research on Modeling and Parameter Identification of Comprehensive Load Model of Distribution Network in Industrial Park

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第1期33卷 264-273页

作者： Tingling WANG Xiaohe yan School of Electric Engineering North China University of Water Resources and Electric Power Wenzhou Polytechnic

With the rapid development of industrial parks, its load model research has become a hot spot. In order to study the load of power system in industrial park, based on the characteristics of the industrial park load, a comprehensive load admittance static model with full voltage range adaptability is considered, and a comprehensive load model of distribution network of the industrial park is established. A complete parameter identification of the model is carried out through chaos particle swarm optimization. The simulation results show that the model can effectively describe the load characteristics of the distribution network in industrial parks.

关键词： Chaos Adaptation models Analytical models Parameter estimation Induction motors Simulation Distribution networks