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Physical modeling of long-term dynamic characteristics of the subgrade for medium-low-speed maglevs

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Railway Engineering Science 2023年第3期31卷 293-308页

作者： Minqi Dong Wubin Wang Chengjin Wang Zhichao Huang zhaofeng ding Zhixing Deng Qian Su School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China National Engineering Research Center of Geological Disaster Prevention Technology in Land Transportation Southwest Jiaotong UniversityChengdu 611756China China Railway Maglev Transportation Investment Construction China Railway Construction Corporation LimitedWuhan 430000China

To investigate the dynamic characteristics and long-term dynamic stability of the new subgrade structure of medium-low-speed(MLS)maglevs,cyclic vibration tests were performed under natural and rainfall conditions,and the dynamic response of the subgrade structure was *** dynamic response attenuation characteristics along the depth direction of the subgrade were compared,and the distribution characteristics of the dynamic stress on the surface of the subgrade along the longitudinal direction of the line were *** critical dynamic stress and cumulative deformation were used as indicators to evaluate the long-term dynamic stability of the *** show that water has a certain effect on the dynamic characteristics of the subgrade,and the dynamic stress and acceleration increase with the water *** the dowel steel structure set between the rail-bearing beams,stress concentration at the end of the loaded beam can be prevented,and the diffusion distance of the dynamic stress along the longitudinal direction *** dynamic stress measured in the subgrade bed range is less than 1/5 of the critical dynamic *** postconstruction settlement of the subgrade after similarity ratio conversion is 3.94 mm and 7.72 mm under natural and rainfall conditions,respectively,and both values are less than the 30 mm limit,indicating that the MLS maglev subgrade structure has good long-term dynamic stability.

关键词： Medium-low-speed maglev Subgrade Dynamic characteristics Long-term dynamic stability Model test

Muon Spin Relaxation Study of Frustrated Tm_(3)Sb_(3)Mg_(2)O_(14)with Kagomé Lattice

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Chinese Physics Letters 2022年第10期39卷 45-49页

作者： Yanxing Yang Kaiwen Chen zhaofeng ding Adrian D.Hillier Lei Shu State Key Laboratory of Surface Physics Department of PhysicsFudan UniversityShanghai 200438China ISIS Facility STFC Rutherford Appleton LaboratoryChiltonDidcotOxfordshireOX110QXUnited Kingdom Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China Shanghai Research Center for Quantum Sciences Shanghai 201315China

The structure and magnetic properties of rare-earth ions Tm^(3+)Kagomé lattice Tm_(3)Sb_(3)Mg_(2)O_(14)are studied by x-ray diffraction,magnetic susceptibility and muon spin relaxation(𝜇SR)*** existence of a small amount of Tm/Mg site-mixing disorder is *** magnetic susceptibility measurement shows that Tm^(3+)magnetic moments are antiferromagnetically correlated with a negative Curie-Weiss temperature of−26.3 *** long-range magnetic order nor spin-glass transition is observed by DC and AC magnetic susceptibility,and confirmed by μSR experiment down to 0.1 ***,the emergence of short-range magnetic order is indicated by the zero-field μSR experiments,and the absence of spin dynamics at low temperatures is evidenced by the longitudinal-field μSR *** with the results of Tm_(3)Sb_(3)Zn_(2)O_(14),another Tm-based Kagomé lattice with much more site-mixing disorder,the gapless spin liquid like behaviors in Tm_(3)Sb_(3)Zn_(2)O_(14)can be induced by disorder *** with perfect geometrical frustration are in urgent demand to establish whether QSL exists in this kind of materials with rare-earth Kagomé lattice.

关键词： technique effect susceptibility

Electronic structure of LaIrIn5and f-electron character in its related Ce-115 compounds

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Science China(Physics,Mechanics & Astronomy) 2020年第11期63卷 90-97页

作者： Rui Zhou XueBing Luo zhaofeng ding Lei Shu XingYu Ji ZiHao Zhu YaoBo Huang DaWei Shen ZhengTai Liu ZhongHao Liu Yun Zhang QiuYun Chen Science and Technology on Surface Physics and Chemistry Laboratory Mianyang 621908China Department of Engineering Physics Tsinghua UniversityBeijing 100084China State Key Laboratory of Surface Physics and Department of Physics Fudan UniversityShanghai 200433China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China Center of Excellence in Superconducting Electronics State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China

LaIrIn5 is a reference compound of the heavy-fermion superconductor *** lack of f electrons in LaIrIn5 indicates that there should not be any f electron participating in the construction of its Fermi *** the electronic structure comparison between LaIrIn5 and LaIrIn5 provides a good platform to study the properties of f *** angle-resolved photoemission spectroscopy(ARPES)measurements and density functional theory(DFT)calculations are performed to study the electronic structures of LaIrIn5 and *** find the valence band structures of the two materials are similar to each other,except for the absence of f bands in *** analyzing the Fermi crossings of the three conduction bands of the two materials quantitatively,we find the volumes of the electron pocketsαandβaround the M′point become larger from LaIrIn5 to LaIrIn5,while the hole pocketγaround theΓ′point becomes *** with the calculation results,we confirm that this is mainly originated from the f-electron contribution,while the lattice-constant difference between LaIrIn5 and LaIrIn5 only has a finite *** also give a summary of the f-electron character in its related Ce-115 heavy fermion *** results may be essential for the complete microscopic understanding of the 115 compounds and the related heavy-fermion systems.

关键词： ARPES DFT heavy fermion LaIrIn5

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气体扩散层亲疏水特性对流体分布的预测

同济大学学报（自然科学版） 2023年第8期51卷 1288-1295页

作者：高源丁兆丰同济大学汽车学院上海201804

采用伪势两相格子玻尔兹曼方法(LBM)研究了非增湿条件下碳纸和碳布气体扩散层(GDL)的流体流动状态。通过随机方法和X射线扫描法构建了气体扩散层样本。为确保模型中表面张力和接触角计算的准确性,采用玻璃微珠模型进行验证,随后通过调... 详细信息

采用伪势两相格子玻尔兹曼方法(LBM)研究了非增湿条件下碳纸和碳布气体扩散层(GDL)的流体流动状态。通过随机方法和X射线扫描法构建了气体扩散层样本。为确保模型中表面张力和接触角计算的准确性,采用玻璃微珠模型进行验证,随后通过调整气体扩散层的亲疏水特性,分析流体在气体扩散层中流动的实时状态,得到了亲疏水特性对孔隙结构内水饱和度的影响规律。结果表明:疏水性气体扩散层中的水分布与亲水性气体扩散层中的水分布明显不同,较大的疏水性更有利于气体扩散层内水的排出;疏水性更强的气体扩散层显著提高了液态水进入气体扩散层的入口压力,导致催化剂层(CL)更容易受到水渗透的影响。

关键词：质子交换膜燃料电池(PEMFC) 碳纸碳布气体扩散层(GDL) 流动传输疏水性和亲水性

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中低速磁浮低置结构路基基床关键技术研究

铁道标准设计 2020年第8期64卷 11-15页

作者：丁兆锋中铁磁浮交通投资建设有限公司武汉430060

为了确定基床合理的技术参数,完善其技术标准,对时速200 km及以下的中低速磁浮低置结构路基基床关键技术进行理论分析研究,采用布什理论明确动荷载影响深度,采用动变形、临界动应变控制指标明确不同基床填料所需的最小变形模量,据此进... 详细信息

为了确定基床合理的技术参数,完善其技术标准,对时速200 km及以下的中低速磁浮低置结构路基基床关键技术进行理论分析研究,采用布什理论明确动荷载影响深度,采用动变形、临界动应变控制指标明确不同基床填料所需的最小变形模量,据此进一步明确了基床结构、厚度、填料及其压实标准,并与现有技术标准进行对比。研究结论如下:(1)低置结构路基基床厚度可取为1.5 m,按两层结构设计,基床表层厚为0.3 m,基床底层厚为1.2 m;(2)基床表层采用级配碎石或A组填料填筑,压实系数不宜小于0.95,地基系数K30不小于150 MPa/m;基床底层采用A、B组填料或改良土填筑,压实系数不小于0.93, A、B组填料地基系数K30不小于130 MPa/m,改良土填料地基系数K30不小于100 MPa/m;(3)本文研究成果与现行应用成果相比,基床结构尺寸、压实标准等进行了合理减小或降低,其设计结果更为合理,也较为经济。

关键词：中低速磁浮低置结构路基基床动荷载影响深度基床填料变形模量压实标准

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竖向荷载作用下桩板结构仿真分析

路基工程 2006年第6期 84-86页

作者：马斌丁兆锋苏谦西南交通大学土木工程学院四川成都610031

桩板结构是一种新型路基基础工程。通过对桩板结构的三维有限元仿真分析,得出桩及承台板在上承结构无碴轨道和列车荷载作用下的应力分布及变形特性,为桩板结构的设计提供理论参考。

关键词：无碴轨道桩板结构有限元仿真分析

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陇东黄土层大体积混凝土施工技术

施工技术 2010年第S2期39卷 138-143页

作者：丁照峰中国石油庆阳石化公司甘肃庆阳745115

结合工程实践,从混凝土配合比设计、施工措施、原材料控制等方面探讨了大体积混凝土的施工工艺,以保证大体积混凝土的工程质量。

关键词：大体积混凝土配合比设计温度控制质量控制评定

基于改进Vision Transformer的行人再识别算法研究

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信息技术与信息化 2023年第8期 164-167页

作者：丁肇丰福州大学福建福州350108

随着Transformer在视觉任务中的迅速发展,它的自注意力机制能够提取不同图像块之间的信息进而提升行人再识别精度,从而来缓解卷积神经网络(convolutional neural networks,CNN)长距离依赖问题。此外,由于CNN下采样后细节信息的丢失问题... 详细信息

随着Transformer在视觉任务中的迅速发展,它的自注意力机制能够提取不同图像块之间的信息进而提升行人再识别精度,从而来缓解卷积神经网络(convolutional neural networks,CNN)长距离依赖问题。此外,由于CNN下采样后细节信息的丢失问题,视觉Transformer因为不会对图像进行下采样,所以可以保留细节的特征。根据上述问题,本文研究了一种改进视觉Transformer的行人再识别方法,并提出一种随机打乱patch模块,即通过重新组合成多个特征来进行特征重排,并且加入视角辅助embedding来提高网络模型的学习鲁棒性特征。实验结果表明,该方法在Market-1501和DukeMTMC-reID两个行人再识别数据集上的准确性优于基于视觉Transformer行人再识别方法基线,其mAP比原始视觉Transformer分别提升1.8%和1.5%。

关键词：行人再识别深度学习 Transformer 图像处理

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郑西客运专线桩板结构室内动态模型试验技术

路基工程 2008年第1期 38-40页

作者：丁兆锋苏谦崔维秀西南交通大学土木工程学院四川成都610031

以郑西客运专线桩板结构室内动态模型试验为例,对室内模型试验的模型设计、模型制作、试验的加荷设计与量测设计以及试验步骤进行了探讨,并对试验中的关键技术做了总结,为类似科研试验提供参考。

关键词：桩板结构动态模型试验试验技术