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合成粗聚丙烯纤维与水泥砂浆界面黏结力学性能

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复合材料学报 2023年第4期40卷 2427-2440页

作者：李长辉陈雪芳张献民王慧颖中国民航大学交通科学与工程学院天津300300

纤维嵌入水泥基材料中的界面黏结力学性能对纤维增强混凝土材料的力学性能起着重要作用。单纤维拉拔试验可以较好地模拟纤维与水泥基体材料界面间的受力条件,因此考虑3种纤维直径(0.2 mm、0.6 mm、0.8 mm)、3种纤维埋置长度(10 mm、20 m... 详细信息

纤维嵌入水泥基材料中的界面黏结力学性能对纤维增强混凝土材料的力学性能起着重要作用。单纤维拉拔试验可以较好地模拟纤维与水泥基体材料界面间的受力条件,因此考虑3种纤维直径(0.2 mm、0.6 mm、0.8 mm)、3种纤维埋置长度(10 mm、20 mm、30 mm)和3种纤维表面性状(压痕型、波浪型、光圆型)与3种水泥砂浆基体水胶比(0.66、0.51、0.41)影响因素,进行了单根粗聚丙烯纤维从水泥砂浆基体中的拔出试验,使用SEM观测了纤维被拔出后的形貌特征,通过ABAQUS有限元建立了纤维拔出过程的数值模型,以研究单根纤维与水泥基界面间的剪切应力。同时将试验结果和模拟结果进行了数值拟合,得到了各因素对界面黏结力学性能的影响规律:(1)水泥砂浆的最佳水胶比为0.41~0.49;(2)合成粗聚丙烯纤维埋置长度最佳为8~10 mm,最佳纤维直径在0.26~0.39 mm范围;(3)纤维表面性状为压痕型时,纤维在水泥基材料中的利用率较大,并且与水泥砂浆的界面黏结性能良好。

关键词：粗聚丙烯纤维单纤维拉拔试验界面黏结性能 ABAQUS有限元数值模拟

SPANNING TREE METHOD OF IDENTIFYING ISOMORPHISM AND TOPOLOGICAL SYMMETRY TO PLANAR KINEMATIC CHAIN WITH MULTIPLE JOINT

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Chinese Journal of Mechanical Engineering 2001年第1期14卷 27-31页

作者： Song Li Yang Jian Department of Mechanical Engingeering,Xiangtan University zhang xianmin Cao Weiqing Shantou University Xi’an University of Technology 湘潭大学机械工程学院湖南湘潭汕头大学广东西安理工大学陕西

The spanning tree method of identifying isomorphism and topological symmetry to planar kinematic chain with multiple joint is presented. Directly using the kinematic chain’s structural graph in the mechanism motion sketch or its inversion,the connected relations of components and joints can be presented through the spanning tree constructed by Depth First traversal the graph and the distribution of back edge. Then, whether two graph isomorphism and components’topological symmertry can be identified through comparing the structural characteristic of spanning tree and the distribution characteristic of back edge. The study shows that the method is effective, directly perceptible, simple and convenient, and easily dealt with by computer.

关键词： Structural graph of kinematic chain Multiple joint Isomorphism Topological symmetry Spanning tree

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机场跑道水泥混凝土道面板尺寸分析

北京航空航天大学学报 2022年第4期48卷 551-559页

作者：张献民李梦晓陈宇李长辉徐博庆中国民航大学交通科学与工程学院天津300300

中国机场通常采用板宽不超过5 m的水泥混凝土道面板,国际上已有机场采用板宽6 m以上的水泥混凝土道面板。相比大尺寸水泥混凝土道面板,小尺寸道面板容易产生病害。为了研究道面板尺寸对道面性能的影响,基于弹性层状理论体系建立道面结... 详细信息

中国机场通常采用板宽不超过5 m的水泥混凝土道面板,国际上已有机场采用板宽6 m以上的水泥混凝土道面板。相比大尺寸水泥混凝土道面板,小尺寸道面板容易产生病害。为了研究道面板尺寸对道面性能的影响,基于弹性层状理论体系建立道面结构有限元模型,通过改变水泥混凝土道面板平面尺寸,研究了考虑温度梯度时飞机荷载作用下道面板内的应力变化。通过某机场实例分析了温度梯度和飞机荷载共同作用下道面板平面尺寸对道面使用寿命的影响,结果表明:道面板内应力受温度梯度影响较大,常见机型荷载作用下,夏季道面板内拉应力25%以上是由温度梯度荷载造成;不同尺寸道面板在相同荷载作用下,道面产生的损伤量不同,设计过程中加入道面板温度应力计算,选择合适的道面板尺寸,可以显著提高水泥混凝土道面的预期使用寿命。

关键词：道面板尺寸温度梯度临界荷载累积损伤疲劳寿命

Topological and Shape Optimization of Flexure Hinges for Designing Compliant Mechanisms Using the Level Set Method

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Chinese Journal of Mechanical Engineering 2019年第1期32卷 42-53页

作者： Benliang Zhu xianmin zhang Min Liu Qi Chen Hai Li Guangdong Provincial Key Laboratory of Precision Equipment and Manufacturing Technology South China University of Technology East China Jiaotong University

A flexure hinge is a major component in designing compliant mechanisms that o ers unique possibilities in a wide range of application fields in which high positioning accuracy is required. Although various flexure hinges with di erent configurations have been successively proposed, they are often designed based on designers' experiences and inspirations. This study presents a systematic method for topological optimization of flexure hinges by using the level set method. Optimization formulations are developed by considering the functional requirements and geometrical constraints of flexure hinges. The functional requirements are first constructed by maximizing the compliance in the desired direction while minimizing the compliances in the other directions. The weighting sum method is used to construct an objective function in which a self-adjust method is used to set the weighting factors. A constraint on the symmetry of the obtained configuration is developed. Several numerical examples are presented to demonstrate the validity of the proposed method. The obtained results reveal that the design of a flexure hinge starting from the topology level can yield more choices for compliant mechanism design and obtain better designs that achieve higher performance.

关键词： Topology optimization Compliant mechanisms Flexure hinges Level set method

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工业机器人能耗预测研究

中国机械工程 2022年第22期33卷 2727-2732,2740页

作者：庹军波彭秋媛张贤明李聪波重庆工商大学废油资源化技术与装备教育部工程研究中心重庆400067 重庆工商大学机械工程学院重庆400067 重庆大学机械传动国家重点实验室重庆400044

针对工业机器人传统能耗预测方法存在的模型复杂、操作繁琐、测量成本高等问题,从机器人末端动作模式和运动轨迹角度出发,提出了一种基于元动作的工业机器人能耗预测方法。首先分析工业机器人静态和动态运行时的元动作和能耗特点,建立... 详细信息

针对工业机器人传统能耗预测方法存在的模型复杂、操作繁琐、测量成本高等问题,从机器人末端动作模式和运动轨迹角度出发,提出了一种基于元动作的工业机器人能耗预测方法。首先分析工业机器人静态和动态运行时的元动作和能耗特点,建立轴移动、轴转动等动态元动作的能耗描述函数及静态元动作的能耗描述函数;然后基于所建元动作库对目标过程进行元动作分解,并构建各元动作的能耗计算模型;最后结合各元动作能耗描述函数和能耗计算模型,实现工业机器人目标过程的能耗预测。应用所提方法,只需事先测试元动作功率并构建能耗描述函数,就能通过分解目标过程实现能耗预测,具有较广阔的应用前景。

关键词：工业机器人能耗预测运动轨迹元动作

Forecasting supernova observations with the CSST: I. Photometric samples

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Science China(Physics,Mechanics & Astronomy) 2024年

作者： Chengqi Liu Youhua Xu xianmin Meng Xin zhang Shi-Yu Li Yuming Fu Xiaofeng Wang Shufei Liu Zun Luo Guanghuan Wang Hu Zhan Department of Astronomy School of Physics Peking University Kavli Institute for Astronomy and Astrophysics Peking University Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of Sciences Beijing Planetarium Beijing Academy of Science and Technology Leiden Observatory Leiden University Kapteyn Astronomical Institute University of Groningen Physics Department Tsinghua University School of Astronomy and Space Science University of Chinese Academy of Sciences

The China Space Station Telescope (CSST, also known as Xuntian) is a serviceable two-meter-aperture wide-field telescope operating in the same orbit as the China Space Station. The CSST plans to survey a sky area of 17,500 deg2of the medium-to-high Galactic latitude to a depth of 25-26 AB mag in at least 6 photometric bands over 255-1,000 nm. Within such a large sky area,slitless spectra will also be taken over the same wavelength range as the imaging survey. Even though the CSST survey is not dedicated to time-domain studies, it would still detect a large number of transients, such as supernovae (SNe). In this paper, we simulate photometric SN observations based on a strawman survey plan using the Sncosmo package. During its 10-year survey,the CSST is expected to observe about 5 million SNe of various types. With quality cuts, we obtain a “gold” sample that comprises roughly 7,400 SNe Ia, 2,200 SNe Ibc, and 6,500 SNe II candidates with correctly classified percentages reaching 91%,63%, and 93%(formally defined as classification precision), respectively. The same survey can also trigger alerts for the detection of about 15,500 SNe Ia (precision 61%) and 2,100 SNe II (precision 49%) candidates at least two days before the light ***, the near-ultraviolet observations of the CSST will be able to catch hundreds of shock-cooling events serendipitously every year. These results demonstrate that the CSST can make a potentially significant contribution to SN studies.

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A novel CGBoost deep learning algorithm for coseismic landslide susceptibility prediction

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Geoscience Frontiers 2024年第2期15卷 349-365页

作者： Qiyuan Yang xianmin Wang Jing Yin Aiheng Du Aomei zhang Lizhe Wang Haixiang Guo Dongdong Li Hubei Subsurface Multi-scale Imaging Key Laboratory School of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China Key Laboratory of Geological and Evaluation of Ministry of Education China University of GeosciencesWuhan 430074China Laboratory of Natural Disaster Risk Prevention and Emergency Management School of Economics and ManagementChina University of GeosciencesWuhan 430074China College of Electronic Science and Engineering National University of Defense TechnologyChangsha 410073China

The accurate prediction of landslide susceptibility shortly after a violent earthquake is quite vital to the emergency rescue in the 72-h‘‘golden window”.However,the limited quantity of interpreted landslides shortly after a massive earthquake makes landslide susceptibility prediction become a *** address this gap,this work suggests an integrated method of Crossing Graph attention network and xgBoost(CGBoost).This method contains three branches,which extract the interrelations among pixels within a slope unit,the interrelations among various slope units,and the relevance between influencing factors and landslide probability,respectively,and obtain rich and discriminative features by an adaptive fusion ***,the difficulty of susceptibility modeling under a small number of coseismic landslides can be *** a basic module of CGBoost,the proposed Crossing graph attention network(Crossgat)could characterize the spatial heterogeneity within and among slope units to reduce the false alarm in the susceptibility ***,the rainfall dynamic factors are utilized as prediction indices to improve the susceptibility performance,and the prediction index set is established by terrain,geology,human activity,environment,meteorology,and earthquake *** is applied to predict landslide susceptibility in the Gorkha meizoseismal area.3.43%of coseismic landslides are randomly selected,of which 70%are used for training,and the others for *** the testing set,the values of Overall Accuracy,Precision,Recall,F1-score,and Kappa coefficient of CGBoost attain 0.9800,0.9577,0.9999,0.9784,and 0.9598,*** by all the coseismic landslides,CGBoost outperforms the current major landslide susceptibility assessment *** suggested CGBoost can be also applied to landslide susceptibility prediction in new earthquakes in the future.

关键词： Coseismic landslide Landslide susceptibility prediction Graph neural network Deep learning

基于透射型超表面的模态可重构太赫兹涡旋波束生成

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雷达学报（中英文） 2022年第4期11卷 728-735页

作者：周晶仪郑史烈余显斌回晓楠章献民浙江大学信息与电子工程学院杭州310027

太赫兹技术与轨道角动量(OAM)技术相结合在高速无线通信领域具有巨大潜力。理论上不同模态的OAM之间具备严格正交性,若能将OAM技术应用到太赫兹通信系统中,必能极大提升系统的通信容量。因此,如何产生高质量的THz-OAM波束,并给予它灵活... 详细信息

太赫兹技术与轨道角动量(OAM)技术相结合在高速无线通信领域具有巨大潜力。理论上不同模态的OAM之间具备严格正交性,若能将OAM技术应用到太赫兹通信系统中,必能极大提升系统的通信容量。因此,如何产生高质量的THz-OAM波束,并给予它灵活的动态控制成为研究者们的一大研究热点。该文设计了一种双层透射型超表面,使用3D打印作为加工方式,成本低、加工难度小。超表面单元结构采用高度可变的介质单元,随着单元高度不断发生改变,透射相位覆盖0°~360°,且透射率保持在88%以上。采用WR-10标准波导喇叭天线进行馈电,在100 GHz工作频率下,通过改变双层超表面之间的相对旋转角度,产生了不同模态的OAM波束。仿真结果表明,该文设计的超表面天线能够实现$l=1,2,3$的OAM波束,二维幅相结果符合对应模态的特征,$l=1,2,3$时,OAM波束的模态纯度分别为85.4%,84.9%,83.4%。通过太赫兹扫场测试平台测试了天线在90 GHz,100 GHz,110 GHz频点下的电场分布。结果表明:在20 GHz带宽内,产生的OAM波束质量较好,证明该文设计的超表面天线在高频工作具有一定的工作带宽,有望应用于高频OAM通信。

关键词：太赫兹涡旋波束模态可重构超表面透射型

34km传感长度的布里渊光时域反射计的设计与实现

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仪器仪表学报 2005年第11期26卷 1155-1158页

作者：宋牟平章献民浙江大学信息与电子工程学系杭州310027

布里渊分布式光纤传感器是目前最具应用前景的分布式光纤传感技术之一,其关键是如何检测布里渊散射光信号,布里渊光时域反射计是其中较好的检测方式。针对布里渊散射光信号特点,应用光相干技术来检测布里渊散射光信号。具体采用微波电... 详细信息

布里渊分布式光纤传感器是目前最具应用前景的分布式光纤传感技术之一,其关键是如何检测布里渊散射光信号,布里渊光时域反射计是其中较好的检测方式。针对布里渊散射光信号特点,应用光相干技术来检测布里渊散射光信号。具体采用微波电光调制产生频率可调的参考光,和散射光进行相干检测,根据散射光频移特性,应用电信号处理技术取出布里渊散射光电信号,并采用偏振控制技术来抑制相干检测的偏振相干性,再经过数字信号累加和平均处理,最后得到分布式传感信号。采用光相干检测设计方案实现了布里渊时域反射计分布式光纤传感器,并进行了34km光纤的分布式应变传感实验。

关键词：分布式光纤传感布里渊散射光相干检测传感长度