检索结果-南通市图书馆

Age of Information Based User Scheduling and Data Assignment in Multi-User Mobile Edge Computing Networks:An Online Algorithm

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第5期21卷 153-165页

作者： Ge Yiyang Xiong Ke Dong Rui lu yang Fan Pingyi Qu Gang School of Computer and Information Technology Beijing Jiaotong UniversityBeijing 100044China Engineering Research Center of Network Management Technology for High Speed Railway of Ministry of Education Beijing 100044China Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications Beijing 100044China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China Department of Electrical and Computer Engineering College ParkMarylandUSA

This paper investigates the age of information(AoI)-based multi-user mobile edge computing(MEC)network with partial offloading mode.The weighted sum AoI(WSA)is first analyzed and derived,and then a WSA minimization problem is formulated by jointly optimizing the user scheduling and data assignment.Due to the non-analytic expression of the WSA w.***.t.the optimization variables and the unknowability of future network information,the problem cannot be solved with known solution methods.Therefore,an online Joint Partial Offloading and User Scheduling Optimization(JPOUSO)algorithm is proposed by transforming the original problem into a single-slot data assignment subproblem and a single-slot user scheduling sub-problem and solving the two sub-problems separately.We analyze the computational complexity of the presented JPO-USO algorithm,which is of O(N),with N being the number of users.Simulation results show that the proposed JPO-USO algorithm is able to achieve better AoI performance compared with various baseline methods.It is shown that both the user’s data assignment and the user’s AoI should be jointly taken into account to decrease the system WSA when scheduling users.

关键词： age of information(aoi) mobile edge computing(mec) user scheduling

A Deep Learning Approach for Forecasting Thunderstorm Gusts in the Beijing–Tianjin–Hebei Region

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第7期41卷 1342-1363页

作者： Yunqing LIU lu yang Mingxuan CHEN Linye SONG Lei HAN Jingfeng XU Faculty of Information Science and Engineering Ocean University of ChinaQingdao 266100China Institute of Urban Meteorology China Meteorological AdministrationBeijing 100089China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044China

Thunderstorm gusts are a common form of severe convective weather in the warm season in North China,and it is of great importance to correctly forecast them.At present,the forecasting of thunderstorm gusts is mainly based on traditional subjective methods,which fails to achieve high-resolution and high-frequency gridded forecasts based on multiple observation sources.In this paper,we propose a deep learning method called Thunderstorm Gusts TransU-net(TGTransUnet)to forecast thunderstorm gusts in North China based on multi-source gridded product data from the Institute of Urban Meteorology(IUM)with a lead time of 1 to 6 h.To determine the specific range of thunderstorm gusts,we combine three meteorological variables:radar reflectivity factor,lightning location,and 1-h maximum instantaneous wind speed from automatic weather stations(AWSs),and obtain a reasonable ground truth of thunderstorm gusts.Then,we transform the forecasting problem into an image-to-image problem in deep learning under the TG-TransUnet architecture,which is based on convolutional neural networks and a transformer.The analysis and forecast data of the enriched multi-source gridded comprehensive forecasting system for the period 2021–23 are then used as training,validation,and testing datasets.Finally,the performance of TG-TransUnet is compared with other methods.The results show that TG-TransUnet has the best prediction results at 1–6 h.The IUM is currently using this model to support the forecasting of thunderstorm gusts in North China.

关键词： thunderstorm gusts deep learning weather forecasting convolutional neural network transformer

Noise attenuation of frequency-modulated multi-rotor using sound field reproduction

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第11期36卷 185-203页

作者： Xice XU yang lu Mengxue SHAO Jiaxin lu National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors.To reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this study.First,the fast prediction method is used to estimate the global noise of the multirotor with different configurations online.Meanwhile,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation.Then,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited.Next,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain characteristics.Finally,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results.The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB.Moreover,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control.

关键词： Acoustic modal analysis Frequency-modulated multirotor Noise attenuation Optimal filter design Sound reproduction

High-Volume Mineral Admixtures Cement: The Effects of Particle Size Distribution

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 102-108页

作者：黄启珉 WANG Kun lu Jiping YU Jianping SHENG Zhenhua 杨露 State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Fujian Jinniu Cement Co. LtdSanming 353300China

The effects of high-volume slag-fly ash cement with different particle sizes on hydration degree,microstructure and mechanical properties were systematically studied,by means of laser particle size(DLS),X-ray diffraction (XRD),comprehensive thermal analysis (TG-DTA),scanning electron microscopy(SEM) and mechanical properties tests.The results show that suitable particle size distribution of cementitious material has significantly promoting effects on hydration reaction rate and mechanical properties.Compared with slag without further grinding,the slag after ball milling for 4 h has an obvious improvement in reactivity,which also provides a faster hydration rate and higher compressive strength for the cementitious material.When the slag milled for 1 and 4 h is mixed at a mass ratio of 2:1 (i e,slag with D_(50) of 7.4μm and average size of 9.9μm,and slag with D_(50) value of 2.6μm and average size of 5.3μm),and a certain amount of fly ash is added in,the most obvious improvement of compressive strength of cement is achieved.

关键词： ultrafine slag microstructure compressive strength particle size

Structural,^(40)Ar/^(39)Ar Geochronological and Rheological Feature Analysis of the Guoxuepu Shear Zone:Indications for the Jitang Metamorphic Complex in the Northern Lancangjiang Zone

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第1期98卷 32-49页

作者： FENG Yipeng WANG Genhou WANG Shulai LI Dian WANG Huan lu yang LIU Han ZHANG Peilie Beijing Institute of Geology for Mineral Resources Co. Ltd.Beijing 100012China School of Earth Sciences and Resources China University of Geosciences(Beijing)Beijing 100083China College of Earth Sciences Chengdu University of TechnologyChengdu 610059China Rock Analysis Laboratory Regional Geology Survey Institute of Hebei ProvinceLangfangHebei 065099China Chengdu Center China Geology SurveyChengdu 610081China

The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone.Through structural-lithological mapping,structural analysis and laboratory testing,the composition of the Jitang metamorphic complex was determined.The macro-and microstructural analyses of the ductile detachment shear zone(Guoxuepu ductile shear zone,2–4 km wide)between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top-to-the-southeast.The presence of various deformation features and quartz C-axis electron backscatter diffraction(EBSD)fabric analysis suggests multiple deformation events occurring at different temperatures.The average stress is 25.68 MPa,with the strain rates(έ)ranging from 9.77×10^(−14)s^(−1)to 6.52×10^(−16)s^(−1).The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern.The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88,implying that the shear zone is dominated by simple shear.The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar-39Ar age of 60.09±0.38 Ma.It is suggested that,coeval with the initial Indo–Eurasian collision,the development of strike-slip faults led to a weak and unstable crust,upwelling of lower crust magma,then induced the detachment of the Jitang metamorphic complex in the Eocene.

关键词： ^(40)Ar/^(39)Ar dating strain pattern vorticity EBSD Guoxuepu shear zone Jitang metamorphic complex

Early diagnostic value of carotid artery ultrasound parameters combined with epicardial adipose layer thickness in coronary heart disease

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2024年第17期12卷 3004-3011页

作者： Min Xu Zhao-yang lu Department of Ultrasound Suzhou Ninth People's HospitalSuzhou 215200Jiangsu ProvinceChina

BACKGROUND Coronary heart disease is associated with coronary atherosclerosis indicated by carotid intima-media thickness(CIMT)thickening and altered vascular elasticity.The epicardial adipose layer can secrete proinflammatory factors that promote the formation of coronary atherosclerosis.Thus,the epicardial fat layer thickness(EAT)may also predict coronary heart disease.AIM To determine the role of common carotid artery ultrasound parameters and EAT in the early diagnosis of coronary artery disease.METHODS Based on coronary angiography,patients with newly suspected coronary heart disease were divided into case(n=107)and control(n=41)groups.The carotid ultrasound parameters,including vascular stiffness(β),elastic coefficient(EP),pulse wave conduction velocity(PWV-β),CIMT,and EAT were compared between the case and control groups and among patients with different lesion numbers in the case group.Pearson correlation was used to evaluate the early diagnostic value of EAT,common carotid artery elasticity,and CIMT for coronary heart disease.RESULTS EP,β,PWV-β,CIMT,and EAT were significantly higher in the case group compared with the levels in the control group(all PluSION EAT correlated well with changes in carotid artery elasticity and CIMT in patients with coronary heart disease.The combination of EAT,carotid artery elasticity,and CIMT facilitates the early diagnosis of coronary heart disease.

关键词： Carotid artery Ultrasound Epicardial adipose layer thickness Coronary heart disease Early diagnosis

Simultaneous enhancement of strength and ductility via microband formation and nanotwinning in an L1_(2)-strengthened alloy

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

Fundamental Research 2024年第1期4卷 147-157页

作者： lu yang Dingshan Liang Zhuo Cheng Ranxi Duan Chuanxin Zhong Junhua luan Zengbao Jiao Fuzeng Ren Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

Metallic alloys with high strength and large ductility are required for extreme structural applications.However,the achievement of ultrahigh strength often results in a substantially decreased ductility.Here,we report a strategy to achieve the strength-ductility synergy by tailoring the alloy composition to control the local stacking fault energy(SFE)of the face-centered-cubic(fcc)matrix in an L1_(2)-strengthened superlattice alloy.As a proof of concept,based on the thermodynamic calculations,we developed a non-equiatomic CoCrNi_(2)(Al_(0.2)Nb_(0.2))alloy using phase separation to create a near-equiatomic low SFE disordered CoCrNi medium-entropy alloy matrix with in situ formed high-content coherent Ni_(3)(Al,Nb)-type ordered nanoprecipitates(∼12 nm).The alloy achieves a high tensile strength up to 1.6 GPa and a uniform ductility of 33%.The low SFE of the fcc matrix promotes the formation of nanotwins and parallel microbands during plastic deformation which could remarkably enhance the strain hardening capacity.This work provides a strategy for developing ultrahigh-strength alloys with large uniform ductility.

关键词： L1_(2)-strengthened superlattice alloy Stacking fault energy Nanotwins Microbands Strain hardening

WC Grain Growth Behavior During Selective Laser Melting of WC-Co Cemented Carbides

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

Acta Metallurgica Sinica(English Letters) 2023年第6期36卷 949-961页

作者： Jinyang Liu Jian Chen yang lu Xin Deng Shanghua Wu Zhongliang lu School of Electromechanical Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510635China Guangdong Master Group Co LtdYunfu 527400China School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049China Guangdong Xi’an Jiaotong University Academy Foshan 528300China Guangdong Industrial Training Center Guangdong Normal University of TechnologyGuangzhouChina

Scanning strategy is a critical parameter for selective laser melting(SLM)processing of metals,alloys as well as metalceramic composites,while related research has rarely been reported yet,especially for additive manufacturing of WC–Co cemented carbides.In this study,three scanning strategies,i.e.,stripe,checkerboard,and spiral scanning,were used for additive manufacturing of WC-32Co cemented carbides.Checkerboard scanning leads to the highest relative density of 96%.Stripe scanning results in the largest average WC grain size followed by checkerboard and spiral scanning.SLM-processed carbides demonstrate agglomeration of WC grains mixed with isolated Co pools and pores.The WC grain growth mechanisms of SLM-processed cemented carbides include mosaic agglomeration growth and incomplete and uneven step growth regardless of scanning strategies.

关键词： Cemented carbides Selective laser melting Scanning strategy Grain Microstructure

An MPI+OpenACC-Based PRM Scalar Advection Scheme in the GRAPES Model over a Cluster with Multiple CPUs and GPUs

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 2022年第1期27卷 164-173页

作者： Huadong Xiao yang lu Jianqiang Huang Wei Xue the Institute of Geodesy and Geophysics Chinese Academy of SciencesWuhan 430074China the University of Chinese Academy of Sciences Beijing 100049China the National Meteorological Information Center Beijing 100081China the Department of Computer Science and Technology Tsinghua UniversityBeijing 100084China the Department of Computer Technology and Application Qinghai UniversityXining 810016China

A moisture advection scheme is an essential module of a numerical weather/climate model representing the horizontal transport of water vapor.The Piecewise Rational Method(PRM) scalar advection scheme in the Global/Regional Assimilation and Prediction System(GRAPES) solves the moisture flux advection equation based on PRM.Computation of the scalar advection involves boundary exchange,and computation of higher bandwidth requirements is complicated and time-consuming in GRAPES.Recently,Graphics Processing Units(GPUs) have been widely used to solve scientific and engineering computing problems owing to advancements in GPU hardware and related programming models such as CUDA/OpenCL and Open Accelerator(OpenACC).Herein,we present an accelerated PRM scalar advection scheme with Message Passing Interface(MPI) and OpenACC to fully exploit GPUs’ power over a cluster with multiple Central Processing Units(CPUs) and GPUs,together with optimization of various parameters such as minimizing data transfer,memory coalescing,exposing more parallelism,and overlapping computation with data transfers.Results show that about 3.5 times speedup is obtained for the entire model running at medium resolution with double precision when comparing the scheme’s elapsed time on a node with two GPUs(NVIDIA P100) and two 16-core CPUs(Intel Gold 6142).Further,results obtained from experiments of a higher resolution model with multiple GPUs show excellent scalability.

关键词： Graphics Processing Unit(GPU)computing Open Accelerator(OpenACC) Message Passing Interface(MPI) Global/Regional Assimilation and Prediction System(GRAPES) Piecewise Rational Method(PRM)scalar advection scheme