检索结果-南通市图书馆

Effective thermal conductivity estimation using a convolutional neural network and its application in topology optimization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and AI 2024年第1期15卷 236-247页

作者： Andre Adam Huazhen Fang xianglin Li Department of Mechanical Engineering University of Kansas1530 W 15th St.Lawrence66045KSUSA Department of Mechanical Engineering and Materials Science Washington University in St.LouisOne Brookings DriveSt.Louis63130MOUSA

Topology optimization of heterogeneous structures can find significant use in a wide range of applications,and its fabrication has been made possible by recent advances in additive ***,the optimization procedure is computationally expensive,as each structural update requires the re-evaluation of the *** computational time is the major limiting factor in large-scale and complex structural *** this study,a convolutional neural network(CNN)model for predicting effective thermal conductivity inspired by the VGG networks is *** using 130,000 unique binary images,the model achieves high predictive ***,it shows a mean absolute percent error(MAPE)of 0.35%in testing when the thermal conductivity of the solid is ten times larger than the fluid,and when the thermal conductivities assigned are that of aluminum and water,the MAPE is 2.35%.The prediction time is 15 ms for a single image with 128×128 pixels,which is 3 to 5 orders of magnitude faster than a finite volume *** employed in topology optimization,the CNN retains a MAPE between 0.67%and 11.8%for different *** CNN model correctly predicts trends in effective thermal conductivity and improves the structure to close proximity of a theoretical maximum in all cases.

关键词： Machine learning Effective thermal conductivity Convolutional neural network VGG Numerical heat transfer Topology optimization

Distributed Matching Theory-Based Task Re-Allocating for Heterogeneous Multi-UAV Edge Computing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Communications 2024年第1期21卷 260-278页

作者： Yangang Wang xianglin Wei Hai Wang Yongyang Hu Kuang Zhao Jianhua Fan College of Communications Engineering Army Engineering University of PLANanjing 210007China The Sixty-Third Research Institute National University of Defense TechnologyNanjing 210007China

Many efforts have been devoted to efficient task scheduling in Multi-Unmanned Aerial Vehicle(UAV)edge ***,the heterogeneity of UAV computation resource,and the task re-allocating between UAVs have not been fully considered ***,most existing works neglect the fact that a task can only be executed on the UAV equipped with its desired service function(SF).In this backdrop,this paper formulates the task scheduling problem as a multi-objective task scheduling problem,which aims at maximizing the task execution success ratio while minimizing the average weighted sum of all tasks’completion time and energy *** three coupled goals in a realtime manner with the dynamic arrival of tasks hinders us from adopting existing methods,like machine learning-based solutions that require a long training time and tremendous pre-knowledge about the task arrival process,or heuristic-based ones that usually incur a long decision-making *** tackle this problem in a distributed manner,we establish a matching theory framework,in which three conflicting goals are treated as the preferences of tasks,SFs and ***,a Distributed Matching Theory-based Re-allocating(DiMaToRe)algorithm is put *** formally proved that a stable matching can be achieved by our *** simulation results show that Di Ma To Re algorithm outperforms benchmark algorithms under diverse parameter settings and has good robustness.

关键词： edge computing heterogeneity matching theory service function unmanned aerial vehicle

Quantifying the agreement and accuracy characteristics of four satellite-based LULC products for cropland classification in China

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2024年第1期23卷 283-297页

作者： Jie Xue xianglin Zhang Songchao Chen Bifeng Hu Nan Wang Zhou Shi Department of Land Management Zhejiang UniversityHangzhou 310058China Institute of Applied Remote Sensing and Information Technology College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China Department of Land Resource Management School of Public Finance and Public AdministrationJiangxi University of Finance and EconomicsNanchang 330013China Key Laboratory of Data Science in Finance and Economics Jiangxi University of Finance and EconomicsNanchang 330013China Key Laboratory of Spectroscopy Sensing Ministry of Agriculture and Rural AffairsHangzhou 310058China

Various land use and land cover(LULC)products have been produced over the past decade with the development of remote sensing *** the differences in LULC classification schemes,there is a lack of research on assessing the accuracy of their application to croplands in a unified ***,this study evaluated the spatial and area accuracies of cropland classification for four commonly used global LULC products(i.e.,MCD12Q1V6,GlobCover2009,FROM-GLC and GlobeLand30)based on the harmonised FAO criterion,and quantified the relationships between four factors(i.e.,slope,elevation,field size and crop system)and cropland classification *** validation results indicated that MCD12Q1 and GlobeLand30 performed well in cropland classification regarding spatial consistency,with overall accuracies of 94.90 and 93.52%,*** FROMGLC showed the worst performance,with an overall accuracy of 83.17%.Overlaying the cropland generated by the four global LULC products,we found the proportions of complete agreement and disagreement were 15.51 and 44.72% for the cropland classification,*** consistency was mainly observed in the Northeast China Plain,the Huang-Huai-Hai Plain and the northern part of the Middle-lower Yangtze Plain,*** contrast,low consistency was detected primarily on the eastern edge of the northern and semiarid region,the Yunnan-Guizhou Plateau and southern *** size was the most important factor for mapping *** area accuracy,compared with China Statistical Yearbook data at the provincial scale,the accuracies of different products in descending order were:GlobeLand30,FROM-GLC,MCD12Q1,and *** cropland classification schemes mainly caused large area deviations among the four products,and they also resulted in the different ranks of spatial accuracy and area accuracy among the four *** results can provide valuable suggestions for selecting cropland products at the national or provinc

关键词： global LULC products cropland mapping accuracy evaluation food security China

Blast damage zone strength reduction method for deep cavern excavation and its application

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第2期18卷 236-251页

作者： Tianzhi YAO Zuguo MO Li QIAN Yunpeng GAO Jianhai ZHANG xianglin XING Enlong LIU Ru ZHANG State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resources and HydropowerSichuan UniversityChengdu 610065China Power China Chengdu Engineering Corporation Limited Chengdu 610072China

The drill and blast(D&B)method is widely used to excavate underground spaces,but explosions generally cause damage to the ***,no blast simulation method can provide computational accuracy and *** this paper,a blast equivalent simulation method called the blast damage zone strength reduction(BDZSR)method is *** method first calculates the range of the blast-induced damage zone(BDZ)by formulae,then reduces the strength and deformation parameters of the rock within the BDZ ahead of excavation,and finally calculates the excavation damage zone(EDZ)for the D&B method by numerical *** method combines stress wave attenuation,rock damage criteria and stress path variation to derive the BDZ depth calculation *** formulae consider the initial geo-stress,and the reliability is verified by numerical *** calculation of BDZ depth with these formulae allows the corresponding numerical simulation to avoid the time-consuming dynamic calculation process,thus greatly enhancing the calculation *** method was applied to the excavation in Jinping Class II hydropower station to verify its *** results show that the BDZSR method can be applied to blast simulation of underground caverns and provide a new way to study blast-induced damage.

关键词： attenuation of stress wave deep-buried underground building drill and blast in situ stress

A macro-mesoscopic constitutive model for porous and cracked rock under true triaxial conditions

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 Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3080-3098页

作者： Li Qian Zuguo Mo Jianhai Zhang xianglin Xing Ru Zhang Tianzhi Yao Yunpeng Gao State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resources and HydropowerSichuan UniversityChengdu610065China Power China Chengdu Engineering Corporation Limited Chengdu610072China

The complex mechanical and damage mechanisms of rocks are intricately tied to their diverse mineral compositions and the formation of pores and cracks under external *** rock tests reveal a complex interplay between the closure of porous defects and the propagation of induced cracks,presenting challenges in accurately representing their mechanical properties,especially under true triaxial stress *** paper proposes a conceptualization of rock at the mesoscopic level as a two-phase composite,consisting of a bonded medium matrix and frictional medium *** bonded medium is characterized as a mesoscopic elastic material,encompassing various minerals surrounding porous *** mechanical properties are determined using the mixed multi-inclusion *** of the bonded medium into the frictional medium occurs through crack extension,with its elastoplastic properties defined by the DruckerePrager yield criterion,accounting for hardening,softening,and *** and Eshelby’s equivalent inclusion methods are applied to the bonded and frictional media,*** macroscopic mechanical properties of the rock are derived from these mesoscopic ***,a True Triaxial Macro-Mesoscopic(TTMM)constitutive model is *** model effectively captures the competitive effect and accurately describes the stress-deformation characteristics of *** the TTMM model,the strains resulting from porous defect closure and induced crack extension are differentiated,enabling quantitative determination of the associated damage evolution.

关键词： Micromechanics Macroemesoscopic Homogenization Constitutive model Competitive effect

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中低速磁浮车辆与U型梁耦合振动响应

同济大学学报（自然科学版） 2021年第12期49卷 1678-1687页

作者：梁潇向湘林彭也也赵春发湖南磁浮技术研究中心有限公司湖南长沙410021 西南交通大学牵引动力国家重点实验室四川成都610031

为了评估中低速磁浮列车在U型梁上的走行性能,建立了考虑比例‒积分‒微分(PID)反馈控制的磁浮列车动力学模型,以及轨排和梁高1.7 m、跨度25 m的U型轨道梁有限元模型。利用开发的磁浮交通分布式协同仿真平台,计算了20~100 km·h^(-1)速度... 详细信息

为了评估中低速磁浮列车在U型梁上的走行性能,建立了考虑比例‒积分‒微分(PID)反馈控制的磁浮列车动力学模型,以及轨排和梁高1.7 m、跨度25 m的U型轨道梁有限元模型。利用开发的磁浮交通分布式协同仿真平台,计算了20~100 km·h^(-1)速度下磁浮车‒轨‒桥系统的动力学响应。结果表明:U型梁跨中挠度、电磁铁悬浮间隙变化量、车体和U型梁梁体的竖向加速度随车速提高变化不大,U型梁跨中挠度不超过3.00 mm,跨中F型导轨最大竖向位移约3.81 mm,悬浮间隙波动量小于1.00 mm,车体质心最大竖向加速度为0.13 m·s^(-2);梁端和跨中接缝处轨排的竖向加速度随车速提高先减小后增大,最大加速度达到5.0g。中低速磁浮列车在U型轨道梁上能够稳定悬浮和安全平稳运行。

关键词：磁浮列车 U型梁轨道悬浮控制动力相互作用数值仿真

Modeling Reynolds stress anisotropy invariants via machine learning

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2024年第6期40卷 50-63页

作者： xianglin Shan Xuxiang Sun Wenbo Cao Weiwei Zhang Zhenhua Xia School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China Department of Engineering Mechanics Zhejiang UniversityHangzhou310027China

The presentation and modeling of turbulence anisotropy are crucial for studying large-scale turbulence structures and constructing turbulence ***,accurately capturing anisotropic Reynolds stresses often relies on expensive direct numerical simulations(DNS).Recently,a hot topic in data-driven turbulence modeling is how to acquire accurate Reynolds stresses by the Reynolds-averaged Navier-Stokes(RANS)simulation and a limited amount of data from *** existing studies use mean flow characteristics as the input features of machine learning models to predict high-fidelity Reynolds stresses,but these approaches still lack robust generalization *** this paper,a deep neural network(DNN)is employed to build a model,mapping from tensor invariants of RANS mean flow features to the anisotropy invariants of high-fidelity Reynolds *** the aspects of tensor analysis and input-output feature design,we try to enhance the generalization of the model while preserving invariance.A functional framework of Reynolds stress anisotropy invariants is derived *** irreducible invariants are then constructed from a tensor group,serving as alternative input features for ***,we propose a feature selection method based on the Fourier transform of periodic *** results demonstrate that the data-driven model achieves a high level of accuracy in predicting turbulence anisotropy of flows over periodic hills and converging-diverging ***,the well-trained model exhibits strong generalization capabilities concerning various shapes and higher Reynolds *** approach can also provide valuable insights for feature selection and data generation for data-driven turbulence models.

关键词： Reynolds stress Anisotropy invariant Tensor analysis Machine learning

Overview of Torque Ripple Minimization Methods for Permanent Magnet Synchronous Motors Based on Harmonic Injection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electrical Engineering 2024年第2期10卷 16-29页

作者： Peng Yi Wenzhi Zheng xianglin Li College of Electrical Engineering Qingdao UniversityQingdao 266071China

Permanent magnet synchronous motors(PMSMs)are widely used because of their high power/torque density and high efficiency,particularly in applications with strict requirements for arrangement space or weight,such as in the electric vehicle(EV)and aerospace ***,the PMSM torque ripple problem has received increasing interest because PMSM drive requirements continuously *** applications with complex transmission and a wide speed range,torque ripple can easily cause system resonance,which deteriorates the driving *** research status and latest progress in the minimization of PMSM torque ripple based on harmonic injection are ***,the causes of PMSM torque ripple are ***,the research status of the PMSM analytical model is introduced,and multiple current harmonic control and optimization methods are described in ***,future development trends in this field are analyzed.

关键词： Permanent magnet synchronous motor torque ripple minimization harmonic injection

Improving model performance in mapping cropland soil organic matter using time-series remote sensing data

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 Integrative Agriculture 2024年第8期23卷 2820-2841页

作者： xianglin Zhang Jie Xue Songchao Chen Zhiqing Zhuo Zheng Wang Xueyao Chen Yi Xiao Zhou Shi Institute of Applied Remote Sensing and Information Technology College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China Department of Land Management Zhejiang UniversityHangzhou 310058China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China Institute of Digital Agriculture Zhejiang Academy of Agricultural SciencesHangzhou 310021China Key Laboratory of Spectroscopy Sensing Ministry of Agriculture and Rural AffairsHangzhou 310058China

Faced with increasing global soil degradation,spatially explicit data on cropland soil organic matter(SOM)provides crucial data for soil carbon pool accounting,cropland quality assessment and the formulation of effective management *** a spatial information prediction technique,digital soil mapping(DSM)has been widely used to spatially map soil information at different ***,the accuracy of digital SOM maps for cropland is typically lower than for other land cover types due to the inherent difficulty in precisely quantifying human *** overcome this limitation,this study systematically assessed a framework of“information extractionfeature selection-model averaging”for improving model performance in mapping cropland SOM using 462 cropland soil samples collected in Guangzhou,China in *** results showed that using the framework of dynamic information extraction,feature selection and model averaging could efficiently improve the accuracy of the final predictions(R^(2):0.48 to 0.53)without having obviously negative impacts on *** the dynamic information of the environment was an efficient way to generate covariates that are linearly and nonlinearly related to SOM,which improved the R^(2)of random forest from 0.44 to 0.48 and the R^(2)of extreme gradient boosting from 0.37to *** recursive feature selection(FRFS)is recommended when there are relatively few environmental covariates(500).The Granger-Ramanathan model averaging approach could improve the prediction accuracy and average *** the structures of initial prediction models are similar,increasing in the number of averaging models did not have significantly positive effects on the final *** the advantages of these selected strategies over information extraction,feature selection and model averaging have a great potential for high-accuracy soil mapping

关键词： cropland soil organic matter digital soil mapping machine learning feature selection model averaging