检索结果-南通市图书馆

基于分形理论的SWCC边界曲线滞后效应模型研究

在线全文

学校读者我要写书评

暂无评论

岩土力学 2019年第10期40卷 3805-3812页

作者：杨明辉陈贺陈可湖南大学土木工程学院

微观土颗粒及孔隙分布的非均匀性及由此引起的瓶颈效应是造成非饱和土土-水特征曲线(SWCC)滞后效应的主要原因。引入分形理论,考虑非饱和土孔径及渗流路径的微观分形特性,提出了一个用于描述水在非饱和土中渗流的毛细管模型。模型中将... 详细信息

微观土颗粒及孔隙分布的非均匀性及由此引起的瓶颈效应是造成非饱和土土-水特征曲线(SWCC)滞后效应的主要原因。引入分形理论,考虑非饱和土孔径及渗流路径的微观分形特性,提出了一个用于描述水在非饱和土中渗流的毛细管模型。模型中将非饱和土孔隙简化为一系列具有不同孔径大小的毛细弯管,其孔径大小及弯曲程度假定服从分形规律。在此基础上,推导得了非饱和土的吸湿与脱湿过程的饱和度S_e^-水头高度h来描述土-水特征曲线滞后效应的特征方程以及饱和度S_e^-相对水力传导系数Kr特征方程。与室内观测结果及已有研究的对比表明,该模型相比以往方法,可更好地模拟非饱和土土-水特征曲线的滞后效应。对非饱和土吸湿与脱湿过程滞后效应的本质进行了对比分析,揭示了滞后效应产生的根本原因在于土体中流通孔隙大小的非均匀性。

关键词：非饱和土滞后效应细观毛细模型分形理论

The abundance,distribution,and enrichment mechanism of harmful trace elements in coals from Guizhou,Southwestern China

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第5期43卷 889-903页

作者： hui Hou Wei Cheng Ruidong yang Yan Zhang College of Mining Guizhou UniversityGuiyangChina National and Local Joint Laboratory of Engineering for Effective Utilization of RegionalMineral Resources from Karst Areas GuiyangChina Guizhou Key Laboratory of Comprehensive Utilization of Non-Metallic Mineral Resources GuiyangChina College of Resource and Environment Engineering Guizhou UniversityGuiyangChina

Coal seams can enrich a variety of harmful trace elements under specific geological *** spatial distribution of harmful trace elements in coal is extremely uneven,and the distribution characteristics of each element content are *** harmful elements released in the process of coal mining and utilization will cause serious harm to the environment and the human *** is of great resource significance to study the geochemistry of coal that affects the enrichment and distribution characteristics of harmful trace *** on the domestic and foreign literature on coal geochemistry in Guizhou published by previous investigators,this study counted 1097 sample data from 23 major coal-producing counties in Guizhou Province,systematically summarized the relevant research results of harmful trace elements in the coal of Guizhou,and revealed the overall distribution and enrichment characteristics of harmful trace elements in the coal of *** results show that the average contents of Cd,Pb,Se,Cu,Mo,U,V,As,Hg,and Cr in coal of Guizhou are higher than those in Chinese coal and world coal.A variety of harmful trace elements in the coal of Guizhou have high background values,especially in Liupanshui,Xingyi and Qianbei *** enrichment of various harmful trace elements in the Late Permian coal in Guizhou is mainly related to the combined action of various geological and geochemical *** supply of terrigenous debris and sedimentary environment may be the basic background of the enrichment of harmful elements in western Guizhou,while low-temperature hydrothermal activity and volcanic ash deposition may be the main reasons for the enrichment of harmful elements in southwestern Guizhou.

关键词： Harmful trace elements Distribution characteristics Enrichment law Geological and geochemical features Guizhou

Resource Allocation for Space-Air-Ground Integrated Networks:A Comprehensive Review

在线全文

学校读者我要写书评

暂无评论

Journal of Communications and Information Networks 2024年第1期9卷 1-23页

作者： hui Liang Zhiqing yang Guobin Zhang Hanxu Hou School of Electrical Engineering and Intelligentization Dongguan University of TechnologyDongguan 523808China Peng Cheng Laboratory Shenzhen 518055China School of Electronics and Information Engineering Shenzhen UniversityShenzhen 518061China School of Electrical Engineering and Intelligentization Dongguan University of TechonologyDongguan 523808China School of Information and Communication Engineering Guangzhou Maritime UniversityGuangzhou 510725China

The space-air-ground integrated networks (SAGIN) has emerged as a critical paradigm to address the growing demands for global connectivity and enhanced communication services. This paper gives a thorough review of the strategies and methodologies for resource allocation within SAGIN, focusing on the challenges and solutions within its complex structure. With the advent of technologies such as 6G, the dynamics of resource optimization have become increasingly complex, necessitating innovative approaches for efficient management. We examine the application of mathematical optimization, game theory, artificial intelligence (AI), and dynamic optimization techniques in SAGIN,offering insights into their effectiveness in ensuring optimal resource distribution, minimizing delays, and maximizing network throughput and stability. The survey highlights the significant advances in AI-based methods,particularly deep learning and reinforcement learning, in tackling the inherent challenges of SAGIN resource allocation. Through a critical review of existing literature, this paper categorizes various resource allocation strategies, identifies current research gaps, and discusses potential future directions. Our findings highlight the crucial role of integrated and intelligent resource allocation mechanisms in realizing the full potential of SAGIN for next-generation communication networks.

关键词： space-air-ground integrated networks resource allocation 6G optimization theory game theory artificial intelligence

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

基于剪切位移法的刚性桩复合地基沉降计算

上海交通大学学报 2007年第6期41卷 965-969页

作者：赵明华张玲杨明辉湖南大学岩土工程研究所长沙410082

在对刚性桩复合地基的工作机理及受荷过程中刚性桩与桩间土的受力特性进行分析探讨的基础上,引入Mylonakis & Gazetas模型模拟桩与桩及桩与土之间的相互作用,充分考虑桩侧土体的非线性特性,假定桩侧土剪应力与剪应变的弹塑性关系,应用... 详细信息

在对刚性桩复合地基的工作机理及受荷过程中刚性桩与桩间土的受力特性进行分析探讨的基础上,引入Mylonakis & Gazetas模型模拟桩与桩及桩与土之间的相互作用,充分考虑桩侧土体的非线性特性,假定桩侧土剪应力与剪应变的弹塑性关系,应用剪切位移法分别导出弹性阶段及弹塑性阶段的桩顶荷载与桩顶位移的显式关系式.在此基础上,考虑垫层作用的影响,提出一种能综合考虑桩-土-垫层体系共同作用的刚性桩复合地基沉降计算方法.结合某模型试验实测结果对文中理论计算进行了验证,其结果表明该计算方法是可行的.

关键词：刚性桩复合地基沉降计算剪切位移法

在线全文

学校读者我要写书评

暂无评论

基于剪切位移法的长短桩复合地基沉降计算

岩土工程学报 2005年第9期27卷 994-998页

作者：赵明华张玲杨明辉湖南大学岩土工程研究所湖南长沙410082

在深入探讨长短桩复合地基作用机理基础上,针对长短桩复合地基的桩–土–承台整体相互作用特点,通过一定的简化假定,建立出长短桩复合地基的沉降计算模型;然后以剪切位移法为基础,引入Mylonakis&Gazetas桩—桩、桩—土相互作用模型,导... 详细信息

在深入探讨长短桩复合地基作用机理基础上,针对长短桩复合地基的桩–土–承台整体相互作用特点,通过一定的简化假定,建立出长短桩复合地基的沉降计算模型;然后以剪切位移法为基础,引入Mylonakis&Gazetas桩—桩、桩—土相互作用模型,导出长短桩复合地基计算时的桩—桩、桩—土以及土—土相互作用柔度系数;在此基础上,考虑垫层作用的影响,提出一种综合考虑桩—土—垫层体系共同作用的长短桩复合地基沉降计算方法,并编制出相应的计算程序。最后利用该法对某工程实例进行了计算分析,结果表明,基于本文方法获得的沉降预测值与实测值吻合较好。

关键词：长短桩复合地基剪切位移法沉降 Mylonakis&Gazetas模型

在线全文

学校读者我要写书评

暂无评论

高定位精度的毫米波全息图像三维目标检测

红外与毫米波学报 2021年第6期40卷 870-877页

作者：李怀乾杨明辉吴亮中国科学院上海微系统与信息技术研究所中国科学院太赫兹固态技术重点实验室上海200050 中国科学院大学材料与光电研究中心北京100049

投影角度不同导致目标的形状及尺寸变化限制了基于主动式毫米波(AMMW)全息图像投影视图的隐匿物品二维检测方法对小目标检测性能的提升,为此,提出了基于点云的隐匿物品三维检测方法。通过阈值化处理将AMMW全息图像转换为点云输入经空洞... 详细信息

投影角度不同导致目标的形状及尺寸变化限制了基于主动式毫米波(AMMW)全息图像投影视图的隐匿物品二维检测方法对小目标检测性能的提升,为此,提出了基于点云的隐匿物品三维检测方法。通过阈值化处理将AMMW全息图像转换为点云输入经空洞卷积及多分支结构改进的SECOND三维目标检测器,提取对目标的三维几何理解及其多尺度上下文信息以提高对小目标的检测能力。实验结果表明,较基于投影的二维检测方法,该方法平均召回率(AR)提升了3.33%,有效提升了定位精度;在交并比(IOU)阈值为0.5时的检出率提升了8.75%,虚警率降低了1.78%,平均精度(AP)提升了7.11%,不同IOU阈值下的平均AP提升了4.30%,有效提升了检测精度;检测速度为17.3 FPS,达实时水平。

关键词：信息科学与系统科学三维目标检测空洞卷积小目标主动式毫米波全息图像

在线全文

学校读者我要写书评

暂无评论

云南“一带一路”粮食物流节点体系研究

粮油食品科技 2019年第2期27卷 73-78页

作者：杨蕙铭李辉曹阳云南省粮油科学研究院国家粮食和物资储备局科学研究院

粮食安全不仅取决于粮食供给和需求的简单平衡,粮食物流节点体系的建立直接影响粮食安全的实现。运用SWOT分析方法对云南"一带一路"粮食物流节点体系进行了分析,同时提出了政策措施和建议。

关键词：粮食安全一带一路粮食物流体系建设

CrN supported by carbon nanosheets as efficient catalysts toward oxygen reduction reaction and Zn-air batteries

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第10期43卷 4973-4981页

作者： Ya-Ting Zhang Fan Zhang Zhe Lu Jun-ming Luo Su-yang Feng Qi Wang hui Chen Hao-ming Wu Zheng-Pei Miao Bin Chi Neng Yu Cheng-Hang You Jing Li Xin-Long Tian School of Chemistry and Chemical Engineering School of Marine Science and EngineeringHainan Provincial Key Lab of Fine ChemistryHainan University State Power Investment Group Hainan Electric Power Co.Ltd. Key Laboratory of Fuel Cell Technology of Guangdong Province Shenzhen Automotive Research Institute Beijing Institute of Technology State Key Laboratory of Nuclear Resources and Environment East China University of Technology

Exploring non-precious efficient oxygen reduction reaction （ORR） catalysts is of great significance to fuel cells and Zn-air batteries （ZABs）.CrN is a theoretically promising ORR catalyst,but its potential needs to be unlocked by proper supports that provide high conductivity and high exposure of active *** this work,we introduce a novel synthesis of carbon nanosheets-supported CrN nanoparticles （CrN/C） by annealing the mixture of CrCl3,1,10-phenanthroline and melamine via a two-step *** prepared CrN/C materials show good ORR activity and stability in acidic and alkaline *** optimal CrN/C material has an ORR half-wave potential of 0.73 and 0.72 V （*** hydrogen electrode） in acidic and alkaline media,*** it retains 82% and 78% of ORR current density in acidic and alkaline media after durability tests,***,the optimal CrN/C material-based self-breathing ZABs deliver a maximum power density of 168 mW·cm-2,which is one of the highest among transition metal nitrides-based ZABs It is found that the ORR activity of CrN/C materials is highly related to the Cr–N valence *** work highlights the good potential of CrN as robust ORR catalyst and verifies its promising application in ZABs.

关键词： Carbon nanosheets CrN Fuel cells Oxygen reduction reaction Zn-air batteries

Super-high bed sintering for iron ores: inhomogeneous phenomena and its mechanism during mineralizing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第8期31卷 1850-1860页

作者： hui-bo Liu Liang-ping Xu Xi-duan yang Zhong-lin Dong Qiang Zhong Guang-hui Li School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina

The inhomogeneous sinter properties in super-high bed sintering have been reported in our previous *** inves-tigate the reasons for the inhomogeneous phenomena,detailed sampling and analysis of mixed material bed and sintered bed in super-high bed sintering plant were *** results indicated that the higher porosity and thinner dendrite of silico-ferrite of calcium and aluminum in the upper layer as well as dense structure and higher secondary hematite content in the lower layer led to the heterogeneities of mechanical strength and reduction properties exceeding 20%and 10%,*** the bed top downward,the basicity of mixed material decreased from 2.13 to 1.68 because the average particle size increased from 2.65 to 4.56 *** and fuels gathered in finer particles(-3 mm)of mixed material,and the-3 mm particles of mixed material generated more liquid phase than+3 mm *** heat input of super-high sintering bed was inhomogeneous due to the heat accumulation effect and unreasonable fuel *** inhomo-geneous sintering heat condition in sintering bed resulted in the different quantities and properties of liquid *** inhomogeneous quantities and properties of liquid phase that were influenced by inhomogeneous distribution of chemical composition,particle size,and heat input led to inhomogeneous mineralizing *** mineralizing condition is the key for homogeneous super-high bed sintering.

关键词： Iron ore Super-high bed sintering Mineralization Material segregation Heat accumulation