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Geometry and tectonic deformation of the seismogenic structure for the 8 August 2017 M_S 7.0 Jiuzhaigou earthquake sequence,northern Sichuan, China 被引量:22
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作者 Feng Long GuiXi Yi +2 位作者 SiWei Wang YuPing Qi Min Zhao 《Earth and Planetary Physics》 CSCD 2019年第3期253-267,共15页
To reveal the geometry of the seismogenic structure of the Aug. 8, 2017 M_S 7.0 Jiuzhaigou earthquake in northern Sichuan,data from the regional seismic network from the time of the main event to Oct. 31, 2017 were us... To reveal the geometry of the seismogenic structure of the Aug. 8, 2017 M_S 7.0 Jiuzhaigou earthquake in northern Sichuan,data from the regional seismic network from the time of the main event to Oct. 31, 2017 were used to relocate the earthquake sequence by the tomoDD program, and the focal mechanism solutions and centroid depths of the M_L ≥ 3.5 events in the sequence were determined using the CAP waveform inversion method. Further, the segmental tectonic deformation characteristics of the seismogenic faults were analyzed preliminarily by using strain rosettes and areal strains(As). The results indicate:(1) The relocated M_S 7.0 Jiuzhaigou earthquake sequence displays a narrow ~ 38 km long NNW-SSE-trending zone between the NW-striking Tazang Fault and the nearly NSstriking Minjiang Fault, two branches of the East Kunlun Fault Zone. The spatial distribution of the sequence is narrow and deep for the southern segment, and relatively wide and shallow for the northern segment. The initial rupture depth of the mainshock is 12.5 km, the dominant depth range of the aftershock sequence is between 0 and 10 km with an average depth of 6.7 km. The mainshock epicenter is located in the middle of the aftershock region, showing a bilateral rupture behavior. The centroid depths of 32 M_L ≥ 3.5 events range from 3 to 12 km with a mean of about 7.3 km, consistent with the predominant focal depth of the whole sequence.(2) The geometric structure of the seismogenic fault on the southern section of the aftershock area(south of the mainshock) is relatively simple, with overall strike of ~150° and dip angle ~75°, but the dip angle and dip-orientation exhibit some variation along the segment. The seismogenic structure on the northern segment is more complicated; several faults, including the Minjiang Fault, may be responsible for the aftershock activities. The overall strike of this section is ~159° and dip angle is ~59°, illustrating a certain clockwise rotation and a smaller dip angle than the southern segment. The differences between the two segments demonstrate variation of the geometric structure along the seismogenic faults.(3) The focal mechanism solutions of 32 M_L ≥ 3.5 events in the earthquake sequence have obvious segmental characteristics. Strike-slip earthquakes are dominant on the southern segment, while 50% of events on the northern segment are thrusting and oblique thrusting earthquakes, revealing significant differences in the kinematic features of the seismogenic faults between the two segments.(4) The strain rosettes for the mainshock and the entire sequence of 31 M_L ≥ 3.5 aftershocks correspond to strike-slip type with NWW-SEE compressional white lobes and NNE-SSW extensional black lobes of nearly similar size. The strain rosette and As value of the entire sequence of 22 M_L ≥ 3.5 events on the southern segment are the same as those of the M_S 7.0 mainshock,indicating that the tectonic deformation here is strike-slip. However, the strain rosette of the entire sequence of 10 M_L ≥ 3.5 events on the northern segment show prominent white compressional lobes and small black extensional lobes, and the related As value is up to 0.52,indicating that the tectonic deformation of this segment is oblique thrusting with a certain strike-slip component. Differences between the two segments all reveal distinctly obvious segmental characteristics of the tectonic deformation of the seismogenic faults for the Jiuzhaigou earthquake sequence. 展开更多
关键词 MS 7.0 Jiuzhaigou earthquake sequence RELOCATION focal mechanism SEISMOGENIC structure geometry tectonic deformation
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Influence of external constraint and rolling geometry on deformation banding of copper single crystals with {123}<634> orientation
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作者 YanpingZeng JianxinDongt +3 位作者 MaicangZhang XishanXie WeiminMao ZhenshengLi 《Journal of University of Science and Technology Beijing》 CSCD 2003年第3期55-61,共7页
In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation... In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation behaviour of copper single crystals with{123}<634> orientation was investigated by embedding them into metal frames of different strengths.The metal frames were made of aluminum and mild steel, respectively. The results show that thedeformation banding degree of the crystal increases with the strength of metal frame and shearstrain. For the crystals rolled under lower (gamma)g ((gamma)g is the ratio of the geometricalredundant shear strain to the normal rolling strain), the deformation is homogeneous. For thecrystals rolled under higher (gamma)g, the deformation is extremely inhomogeneous. The deformationis more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. TheS-orientation is more stable in the crystals rolled under lower (gamma)g than that rolled underhigher (gamma)g. 展开更多
关键词 external constraint rolling geometry deformation banding copper singlecrystal
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Gravity changes and surface deformations due to faults with different geometry
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作者 白志明 王椿镛 申重阳 《Acta Seismologica Sinica(English Edition)》 CSCD 1999年第6期690-698,728,共10页
Based on the formulae of the gravity changes and surface deformations raised by the dislocation of a point source,the gravity changes and deformations caused by the dislocations of fault with arbitrary geometry are co... Based on the formulae of the gravity changes and surface deformations raised by the dislocation of a point source,the gravity changes and deformations caused by the dislocations of fault with arbitrary geometry are computed by using numerical method. The results show that both of the dislocation and the geometry of the fault plane are the basic elements that determine the gravity and deformation effects. Gravity changes, vertical deformations and apparent vertical deformations induced by the dislocation are alike in their characteristic patterns. The similarities and differences of these patterns provide us a probability in acquiring the gravity and deformation anomalies due to faulting from the observed data. Thus the geometric and kinematic features of the earthquake-generating faults can be appropriately distinguished and evaluated. 展开更多
关键词 numerical method fault dislocations arbitrary geometry gravity changes and deformations
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Constrained geometry analysis to resolve 3-D deformations from three ground-based radars
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作者 DENG Yunkai ZHU Jiaxin +2 位作者 TIAN Weiming HU Cheng YANG Wenyu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第6期1263-1269,共7页
When multiple ground-based radars(GB-rads)are utilized together to resolve three-dimensional(3-D)deformations,the resolving accuracy is related with the measurement geometry constructed by these radars.This paper focu... When multiple ground-based radars(GB-rads)are utilized together to resolve three-dimensional(3-D)deformations,the resolving accuracy is related with the measurement geometry constructed by these radars.This paper focuses on constrained geometry analysis to resolve 3-D deformations from three GB-rads.The geometric dilution of precision(GDOP)is utilized to evaluate 3-D deformation accuracy of a single target,and its theoretical equation is derived by building a simplified 3-D coordinate system.Then for a 3-D scene,its optimal accuracy problem is converted into determining the minimum value of an objective function with a boundary constraint.The genetic algorithm is utilized to solve this constrained optimization problem.Numerical simulations are made to validate the correctness of the theoretical analysis results. 展开更多
关键词 three-dimensional(3-D)deformation ground-based radar(GB-rad) constrained geometry geometric dilution of precision(GDOP) accuracy evaluation
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高速铁路桥梁结构变形与轨面几何形态的空间映射模型研究
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作者 冯青松 陈谣 +3 位作者 李秋义 孙魁 杨舟 张凌 《铁道学报》 EI CAS CSCD 北大核心 2024年第8期132-141,共10页
高速铁路桥梁附加变形会导致轨面几何形态的变化,加剧列车和轨道-桥梁结构之间的动态相互作用,影响桥上行车安全性。以32 m简支梁桥-CRTSⅡ型板式无砟轨道结构为研究对象,将箱梁看作耦合板结构,选取改进傅里叶级数作为结构的试函数,通... 高速铁路桥梁附加变形会导致轨面几何形态的变化,加剧列车和轨道-桥梁结构之间的动态相互作用,影响桥上行车安全性。以32 m简支梁桥-CRTSⅡ型板式无砟轨道结构为研究对象,将箱梁看作耦合板结构,选取改进傅里叶级数作为结构的试函数,通过输入梁体的附加变形值,基于势能驻值原理求解轨道各结构层的垂、横向变形函数,建立桥梁结构变形与轨面几何形态的空间映射模型。研究考虑底板脱空情况下桥梁典型横、竖向组合变形下轨面几何形态的变形规律。研究表明:空间映射模型与有限元模型得到的钢轨变形曲线吻合较好。映射模型经过少量的迭代便可以求出底板脱空的位置、幅值与面积。钢轨在梁体横、竖向组合变形下存在耦合变形效应,梁体横向转角幅值对钢轨垂向变形影响较大,并会导致左右两块底板脱空区域的范围与幅值发生相反变化趋势,进而使底板上方两侧钢轨“上翘”处以及“下凹”处最大变形值发生改变。桥墩垂向沉降值基本不会影响其钢轨横向变形。 展开更多
关键词 高速铁路 桥梁附加变形 轨面几何形态 势能驻值原理 空间映射模型
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外包钢壳混凝土拱形桥塔节段拼装几何姿态预测研究 被引量:1
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作者 桂水荣 李勇康 +1 位作者 尹樟勇 杨龙贵 《世界桥梁》 北大核心 2024年第2期66-73,共8页
赣州市集结大桥主桥为外包钢壳混凝土拱形桥塔斜拉桥,为确保钢混组合拱形桥塔节段拼装精准合龙,采用MIDAS Civil软件建立拱形桥塔空间几何模型,分析外包钢壳和混凝土湿重对桥塔变形的影响,采用切线初始位移法对桥塔施工阶段位移进行预测... 赣州市集结大桥主桥为外包钢壳混凝土拱形桥塔斜拉桥,为确保钢混组合拱形桥塔节段拼装精准合龙,采用MIDAS Civil软件建立拱形桥塔空间几何模型,分析外包钢壳和混凝土湿重对桥塔变形的影响,采用切线初始位移法对桥塔施工阶段位移进行预测,通过求解制造线形对桥塔待拼装节段进行预偏修正,并与实测数据进行对比。结果表明:外包钢壳能显著减小桥塔变形;施工阶段桥塔变形主要由混凝土湿重引起,临时支撑能有效减小混凝土浇筑产生的横向变形。基于切线初始位移法的几何姿态预测方法能有效预测桥塔拼装全过程几何姿态,实测成桥阶段桥塔各节段最大偏位为6 mm,小于施工控制要求,具有较高的实施精度,可保证成桥状态下桥塔几何姿态的准确性。 展开更多
关键词 斜拉桥 外包钢壳混凝土拱形桥塔 几何姿态预测 切线初始位移法 混凝土湿重 变形影响 线形控制 有限元法
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车辆循环动载下高速铁路路基累积变形预测研究
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作者 李正 徐磊 +4 位作者 王卫东 杜香刚 余志武 刘鹏飞 曾志平 《铁道科学与工程学报》 EI CAS CSCD 北大核心 2024年第4期1445-1456,共12页
高速铁路路基在车辆荷载反复作用下不可避免地产生累积变形,影响铁路轨道-路基结构服役性能和车辆运行品质。为探明高铁路基在循环车辆动载下的累积变形空间分布特性和长期发展规律,建立车致路基累积变形预测模型,其主要由2个子模块组成... 高速铁路路基在车辆荷载反复作用下不可避免地产生累积变形,影响铁路轨道-路基结构服役性能和车辆运行品质。为探明高铁路基在循环车辆动载下的累积变形空间分布特性和长期发展规律,建立车致路基累积变形预测模型,其主要由2个子模块组成:1)基于多体动力学和有限单元法建立的高速铁路车辆-轨道-路基耦合时变动力学模型;2)基于建立的车辆-轨道-路基动力相互作用模型,引入路基累积变形预测模型,利用循环跳跃的方式预测不同车辆荷载累积次数下路基的累积变形及其空间分布规律。2个模块的交互方面,在每次循环跳跃后,将路基累积变形空间映射至轨道,形成轨面附加几何不平顺,并同步更新迭代系统动力矩阵,建立了车致路基累积变形与系统动力响应之间的关联关系。研究结果表明:本文提出的计算模型可较好地揭示路基土体累积变形在循环车辆动载下的演化规律;采用循环跳跃的方法可更为真实准确地预测路基的累积变形,其计算的路基累积变形最大值为2.6069 mm,而未采用循环跳跃方法计算出的累积变形最大值则为1.7 mm,低估了34.8%。路基累积变形在前期发展较快,后期由于土体被不断夯实,累积变形的演化呈现减缓趋势,累积变形速率从1次加载0.035 mm减小到1次加载小于10^(-6)mm;在路基具有初始不均匀变形的区域内,路基累积变形的幅值大于路基没有初始不均匀变形的区域;路基的累积变形对系统的垂向动力响应的影响显著,动力响应表现为增大的趋势;对于系统的横向振动,累积变形的影响较小。本文提出的方法和研究结果可为高速铁路路基不均匀累积变形控制和预测提供技术支撑。 展开更多
关键词 铁道工程 车辆-轨道-路基动力相互作用 路基累积变形 空间几何映射 时变动力系统
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基于DEFORM的7075铝合金切削过程仿真研究 被引量:3
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作者 朱昱 王成 +2 位作者 朱杨杨 倪红军 沈伟平 《工具技术》 2019年第1期70-74,共5页
以7075铝合金为例,利用DEFORM仿真软件中的车削模块,建立铝合金切削有限元模型,对仿真结果进行分析,得到切削过程中切削力变化、工件应力及刀具表面切削温度分布等相关试验数据。通过切削力的测量试验验证仿真结果的有效性,结果表明仿... 以7075铝合金为例,利用DEFORM仿真软件中的车削模块,建立铝合金切削有限元模型,对仿真结果进行分析,得到切削过程中切削力变化、工件应力及刀具表面切削温度分布等相关试验数据。通过切削力的测量试验验证仿真结果的有效性,结果表明仿真值与测量值的变化趋势一致,证明了仿真后处理结果的有效性。在此基础上研究刀具几何形状对切削过程的影响,该方法为生产实践中确定切削7075铝合金的刀具几何形状提供了新途径。 展开更多
关键词 7075铝合金 deform 刀具几何形状
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空间任意汇交杆系的变形协调几何方程组及其组合学释义
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作者 陈彦 陈丰 邵红才 《扬州职业大学学报》 2024年第1期27-30,共4页
将平面汇交杆系的变形协调问题拓展到空间任意汇交杆系的情形,运用微分解析法,通过对空间任意4根汇交杆的求解,直观地得到了空间任意n根汇交杆系变形协调几何方程组的一般形式,解决了空间汇交杆系的超静定问题。结论中所有下标的顺序符... 将平面汇交杆系的变形协调问题拓展到空间任意汇交杆系的情形,运用微分解析法,通过对空间任意4根汇交杆的求解,直观地得到了空间任意n根汇交杆系变形协调几何方程组的一般形式,解决了空间汇交杆系的超静定问题。结论中所有下标的顺序符合组合学中字典序数排列,因此可以用计算机编程去求解超静定空间汇交杆系的变形协调方程。 展开更多
关键词 空间任意汇交杆系 微分解析法 变形协调几何方程组 超静定 字典序数排列
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考虑地下通道的盾构隧道下穿轨道群施工影响
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作者 杨琳杰 郜亮亮 +2 位作者 汤劲松 陈之宁 朱正国 《甘肃科学学报》 2024年第5期9-15,共7页
为了研究盾构隧道下穿铁路客站轨道群时,轨道下穿施工对铁路轨道几何形位的影响和地下通道的存在有何种作用,采用数值模拟的方法对盾构隧道下穿铁路旅客地下通道和客站轨道进行研究,确定轨道变形的主要分析指标,探讨了地下通道存在的作... 为了研究盾构隧道下穿铁路客站轨道群时,轨道下穿施工对铁路轨道几何形位的影响和地下通道的存在有何种作用,采用数值模拟的方法对盾构隧道下穿铁路旅客地下通道和客站轨道进行研究,确定轨道变形的主要分析指标,探讨了地下通道存在的作用,并结合呼和浩特市轨道交通2号线的现场监测数据进行对比分析。结果表明:盾构隧道下穿铁路轨道对铁路轨道几何形位影响最大的是轨道沉降,其次为轨道高低不平顺和水平不平顺;盾构隧道正交或斜交下穿铁路时,地下通道的存在会减小轨道的变形;盾构隧道正交下穿铁路轨道时,盾构隧道轴线应距地下通道中心线3倍以上隧道直径;近距离穿过地下通道,可斜交通过,但应做好防止地下通道沉降过大的防护工作。 展开更多
关键词 盾构隧道 地下通道 轨道几何形位 轨道变形 下穿施工
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地下水作用致隧道底鼓和双块式无砟轨道变形规律研究
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作者 张彩亮 刘秀波 +2 位作者 柯在田 张玉芳 马帅 《铁道建筑》 北大核心 2024年第6期1-8,共8页
水压作用会导致隧道底鼓变形,变形传递至轨道会引起轨道几何状态不良。本文从轨道几何形位变化角度出发,对水压力作用导致隧道底鼓时引发的轨道几何状态劣化问题展开深入研究,提出了水压力的近似计算方法;基于荷载-结构法建立了隧道内... 水压作用会导致隧道底鼓变形,变形传递至轨道会引起轨道几何状态不良。本文从轨道几何形位变化角度出发,对水压力作用导致隧道底鼓时引发的轨道几何状态劣化问题展开深入研究,提出了水压力的近似计算方法;基于荷载-结构法建立了隧道内双块式无砟轨道数值计算模型,分析了不同找平层水压作用下轨道的几何不平顺特征和变化规律。结果表明:隧道底鼓-无砟轨道几何不平顺现象是道床板与找平层接触状态变化、沿线路纵向与隧道横断面内的横向变形叠加作用的结果;水压作用除引起轨道高低几何状态劣化外,还可导致轨道轨向、水平变化及扭曲变形;受承压水头和水压分布长度影响,水压引起的内外轨的高低、轨向以及轨道水平变化曲线具有各自形态特征,而并非单一抛物线或正弦线。通过数值模拟,验证了隧底找平层底鼓变形的接触状态非线性力学行为,揭示了底鼓变形下轨道线路三角坑的形成机理。 展开更多
关键词 高速铁路 隧道 数值模拟 底鼓变形 双块式无砟轨道 水压作用 轨道几何状态
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基于DG/K方法的成形铣刀设计模型 被引量:1
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作者 顾慧卿 王西彬 刘志兵 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2014年第1期101-105,112,共6页
对广泛应用于曲面加工的成形铣刀设计困难的问题,基于DG?K方法,应用刀具展成面T和待加工曲面P在刀触点K的微小邻域内的一致率、曲面的包络和逆包络原理,以加工一个非共轴零件的特征曲面的成形铣刀设计为实例,建立了系统性的成形铣刀设... 对广泛应用于曲面加工的成形铣刀设计困难的问题,基于DG?K方法,应用刀具展成面T和待加工曲面P在刀触点K的微小邻域内的一致率、曲面的包络和逆包络原理,以加工一个非共轴零件的特征曲面的成形铣刀设计为实例,建立了系统性的成形铣刀设计模型,包括待加工曲面P的数学模型、成形铣刀廓形的设计模型、螺旋刃口曲线数学模型以及实得沟槽曲面数学模型;并利用所建立的模型绘制铣刀螺旋刃口曲线和螺旋沟槽面的可视化图形,以验证该模型的正确性和可用性,为成形铣刀的设计提供一种理论方法和依据. 展开更多
关键词 微分几何 运动学 一致率 成形铣刀 包络 逆包络
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Precise point positioning and its application in mining deformation monitoring 被引量:4
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作者 XU Chang-hui1, 2, WANG Jin-ling2, GAO Jing-xiang1, WANG Jian1, HU Hong1 1. School of Environment and Spatial Information, China University of Mining and Technology, Xuzhou 22116, China 2. School of Surveying and Spatial Information Systems, University of New South Wales, Sydney 2052, Australia 《中国有色金属学会会刊:英文版》 CSCD 2011年第S3期499-505,共7页
Precise point positioning (PPP)-based deformation monitoring scheme is presented for the use in mining deformation monitoring. Within the solutions of daily observation, outliers are detected and removed to avoid any ... Precise point positioning (PPP)-based deformation monitoring scheme is presented for the use in mining deformation monitoring. Within the solutions of daily observation, outliers are detected and removed to avoid any potential misinterpretation of the results and then the deformation can be extracted by the coordinate differences between the two consecutive solutions. Meanwhile, because of the special location of a rover station in mining areas, the satellite geometry may be insufficient for a reasonable PPP solution, and the multipath impact an also be significant. Therefore, it is necessary to predict the satellite geometry before any daily observation. To evaluate the ability of extracting the deformation using the PPP-based method, various quality measures were introduced. The results of three datasets of the same station show that the precision of deformation monitored by PPP can reach up to cm level and even mm level. 展开更多
关键词 PRECISE point POSITIONING deformATION monitoring OUTLIER identification geometry MULTIPATH
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Computational implementation of a GIS developed tool for prediction of dynamic ground movement and deformation due to underground extraction sequence 被引量:3
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作者 Yue Cai Yujing Jiang +1 位作者 Baoguo Liu Ibrahim Djamaluddin 《International Journal of Coal Science & Technology》 EI 2016年第4期379-398,共20页
In the last century, there has been a significant development in the evaluation of methods to predict ground movement due to underground extraction. Some remarkable developments in three-dimensional computational meth... In the last century, there has been a significant development in the evaluation of methods to predict ground movement due to underground extraction. Some remarkable developments in three-dimensional computational methods have been supported in civil engineering, subsidence engineering and mining engineering practice. However, ground movement problem due to mining extraction sequence is effectively four dimensional (4D). A rational prediction is getting more and more important for long-term underground mining planning. Hence, computer-based analytical methods that realistically simulate spatially distributed time-dependent ground movement process are needed for the reliable long-term underground mining planning to minimize the surface environmental damages. In this research, a new computational system is developed to simulate four-dimensional (4D) ground movement by combining a stochastic medium theory, Knothe time-delay model and geographic information system (GIS) technology. All the calculations are implemented by a computational program, in which the components of GIS are used to fulfill the spatial-temporal analysis model. In this paper a tight coupling strategy based on component object model of GIS technology is used to overcome the problems of complex three-dimensional extraction model and spatial data integration. Moreover, the implementation of computational of the interfaces of the developed tool is described. The GIS based developed tool is validated by two study cases. The developed computational tool and models are achieved within the GIS system so the effective and efficient calculation methodology can be obtained, so the simulation problems of 4D ground movement due to underground mining extraction sequence can be solved by implementation of the developed tool in GIS. 展开更多
关键词 Computational model Geographical information system - Component object model - Complex mining geometry Ground deformation Surface subsidence
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Image Reconstruction from Fan-Beam Projections without Back-Projection Weight in a 2-D Dynamic CT: Compensation of Time-Dependent Rotational, Uniform Scaling and Translational Deformations 被引量:1
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作者 A. V. Narasimhadhan Aman Sharma Dipen Mistry 《Open Journal of Medical Imaging》 2013年第4期136-143,共8页
In a dynamic CT, the acquired projections are corrupted due to strong dynamic nature of the object, for example: lungs, heart etc. In this paper, we present fan-beam reconstruction algorithm without position-dependent... In a dynamic CT, the acquired projections are corrupted due to strong dynamic nature of the object, for example: lungs, heart etc. In this paper, we present fan-beam reconstruction algorithm without position-dependent backprojection weight which compensates for the time-dependent translational, uniform scaling and rotational deformations occurring in the object of interest during the data acquisition process. We shall also compare the computational cost of the proposed reconstruction algorithm with the existing one which has position-dependent weight. To accomplish the objective listed above, we first formulate admissibility conditions on deformations that is required to exactly reconstruct the object from acquired sequential deformed projections and then derive the reconstruction algorithm to compensate the above listed deformations satisfying the admissibility conditions. For this, 2-D time-dependent deformation model is incorporated in the fan-beam FBP reconstruction algorithm with no backprojection weight, assuming the motion parameters being known. Finally the proposed reconstruction algorithm is evaluated with the motion corrupted projection data simulated on the computer. 展开更多
关键词 Fan-Beam Reconstruction Algorithm Hilbert Filter Virtual Acquisition geometry Equiangular Detector geometry ROTATIONAL UNIFORM SCALING and Translational deformation Position Dependent BACK-PROJECTION Weight
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Cosserat Dynamic Modeling and Simulation of Mobile Cable on Satellite
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作者 Ziquan Wang Jinzhu Li +4 位作者 Weinan Chen Xuefeng Gao You Lü Leijie Shen Haojie Chen 《Journal of Beijing Institute of Technology》 EI CAS 2023年第6期740-753,共14页
Mainly for the problems that the configuration of the mobile cable on the satellite is very easy to change,the motion trajectory and dynamic characteristics of the cable can not be accu-rately predicted,which affects ... Mainly for the problems that the configuration of the mobile cable on the satellite is very easy to change,the motion trajectory and dynamic characteristics of the cable can not be accu-rately predicted,which affects the laying quality seriously,the dynamic modeling and simulation of mobile cable on the satellite are carried out.On the basis of referring to the previous papers,the existing mathematical model is improved.The equations of the base vector of the cable section principal axis coordinate system with respect to the arc coordinate s,the distribution force of cable balance equation,the matrix expression of the base vector after the rotation motion transformation in the section principal axis coordinate system,the angular velocity of cable,the section elastic strain and velocity calculation equations are given,and the Cosserat dynamic modeling of the mobile cable is established.Finally,the dynamic simulation model of the mobile cable assembly of the kinematic mechanism is established,and the changes of the force and torque on the cable con-straint end are obtained,which provides a reference for the dynamic modeling and simulation of the mobile cable on satellite. 展开更多
关键词 flexible cable large deformation curve geometry Cosserat modeling computer simulation
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Assessment of the ballistic response of honeycomb sandwich structures subjected to offset and normal impact
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作者 Nikhil Khaire Gaurav Tiwari +1 位作者 Vivek Patel M.A.Iqbal 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第10期56-73,共18页
In the present study,experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb cores.The high velocity impact tests were carried out using a compressed air gu... In the present study,experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb cores.The high velocity impact tests were carried out using a compressed air gun.A sharp conical nosed projectile was impacted normally and with some offset distance(20 mm and 40 mm).The deformation,failure mode and energy dissipation characteristics were obtained for both kinds of loading.Moreover,the explicit solver was run in Abaqus to create the finite element model.The numerically obtained test results were compared with the experimental to check the accuracy of the modelling.The numerical result was further employed to obtain strain energy dissipation in each element by externally running user-defined code in Abaqus.Furthermore,the influence of inscribe circle diameter and cell wall and face sheet thickness on the energy dissipation,deformation and failure mode was examined.The result found that ballistic resistance and deformation were higher against offset impact compared to the normal impact loading.Sandwich panel impacted at 40 mm offset distance required 3 m/s and 1.9 m/s more velocity than 0 and 20 mm offset distance.Also,increasing the face sheet and wall thickness had a positive impact on the ballistic resistance in terms of a higher ballistic limit and energy absorption.However,inscribe circle diameter had a negative influence on the ballistic resistance.Also,the geometrical parameters of the sandwich structure had a significant influence on the energy dissipation in the different deformation directions.The energy dissipation in plastic work was highest for circumferential direction,regardless of impact condition followed by tangential,radial and axial directions. 展开更多
关键词 Honeycomb sandwich structure Offset impact Energy dissipation characteristic deformation and failure mode geometry effect
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微变形平面的设计解码——瑞士设计师组合莫格&德格罗的木构加建住宅建构分析
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作者 夏珩 全巧琳 郭杰宏 《建筑师》 CSSCI 2023年第6期70-78,共9页
揭示“变形”平面是对空间场所特质的回应,“微弱”变形程度的掌控则是对夸张形式的精心抵抗。本文基于文献资料,使用图解、口述采访的方式挖掘隐藏的设计密码,回答案例中新建体量与现有住宅的错动布局、极微弱变形的菱形平面、在室内... 揭示“变形”平面是对空间场所特质的回应,“微弱”变形程度的掌控则是对夸张形式的精心抵抗。本文基于文献资料,使用图解、口述采访的方式挖掘隐藏的设计密码,回答案例中新建体量与现有住宅的错动布局、极微弱变形的菱形平面、在室内外极大视觉反差的窗户等一系列相关设计问题,呈现各个层次的设计逻辑。展示瑞士设计师组合莫格&德格罗的设计水准,提倡一种异于“照片建筑”的设计价值观。 展开更多
关键词 体量 微变形 空间 几何 内凹窗 木结构
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Spectral Element Discretization of the Stokes Equations in Deformed Axisymmetric Geometries
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作者 Zakaria Belhachmi Andreas Karageorghis 《Advances in Applied Mathematics and Mechanics》 SCIE 2011年第4期448-469,共22页
In this paper,we study the numerical solution of the Stokes system in deformed axisymmetric geometries.In the azimuthal direction the discretization is carried out by using truncated Fourier series,thus reducing the d... In this paper,we study the numerical solution of the Stokes system in deformed axisymmetric geometries.In the azimuthal direction the discretization is carried out by using truncated Fourier series,thus reducing the dimension of the problem.The resulting two-dimensional problems are discretized using the spectral element method which is based on the variational formulation in primitive variables.The meridian domain is subdivided into elements,in each of which the solution is approximated by truncated polynomial series.The results of numerical experiments for several geometries are presented. 展开更多
关键词 Spectral element method Stokes equations variational formulation deformed geometries Fourier expansion
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大别山超高压变质带面理化榴辉岩中变形石榴石的几何学和运动学特征及其大地构造意义 被引量:21
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作者 徐树桐 刘贻灿 +3 位作者 苏文 吴维平 江来利 王汝成 《岩石学报》 SCIE EI CAS CSCD 北大核心 1999年第3期321-337,共17页
大别山东部双河附近面理化榴辉岩中, 所有榴辉岩相矿物包括石榴石、绿辉石乃至金红石都受到强烈拉伸。用透射电镜可以观察到石榴石晶体中塑性变形的显微构造, 包括自由位错、位错环、位错壁和位错网。拉伸石榴石的应变轴比表现为 X... 大别山东部双河附近面理化榴辉岩中, 所有榴辉岩相矿物包括石榴石、绿辉石乃至金红石都受到强烈拉伸。用透射电镜可以观察到石榴石晶体中塑性变形的显微构造, 包括自由位错、位错环、位错壁和位错网。拉伸石榴石的应变轴比表现为 X> Y> Z。运动学标志如石榴石的不对称碎斑和旋转的金红石颗粒, 表明有旋转应变的作用。石榴石和金红石的福林系数分别为118 和098。所有这些都表明石榴石是在接近于平面应变的条件下形成。由于石榴石颗粒在应变前后体积未变,因此也是在简单剪切作用条件下形成的。根据石榴石韧性变形要求的温度条件, 此种变形应在榴辉岩相条件下发生, 代表一次向南的逆冲作用, 经过展开后, 逆冲的方向为南西。根据石榴石的流变律, 其韧性变形的最低温度估计约为 800℃。石榴石中普遍有一组透入性破劈理, 它产生于面理化榴辉石折返后的角闪岩相早期, 形成于石榴石韧性变形之后。破劈理及其中反S形破劈理的运动指向表明有向北的滑动, 发生在主簿源复背斜形成之前; 主簿源复背斜使面理化榴辉岩的产状由倾向北改变为倾向南。根据面理化榴辉岩及其围岩的同位素年龄, 估算出面理化榴辉岩在200~190 Ma 期间的平均垂直折返速率为9m m /a。此外, 展开更多
关键词 榴辉岩 变形石榴石 几何学 运动学 大地构造意义
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