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Fourier Descriptors with Different Shape Signatures:a Comparative Study for Shape Based Retrieval of Kinematic Constraints 被引量:1
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作者 WU Jun GE Qiaode Jeffrey +1 位作者 GAO Feng SU Haijun 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2011年第5期723-730,共8页
Fourier Descriptors(FD) has been widely used in image analysis and computer vision for shape recognition as they can be made independent of translation,rotation,as well as scaling.They have also been used for develo... Fourier Descriptors(FD) has been widely used in image analysis and computer vision for shape recognition as they can be made independent of translation,rotation,as well as scaling.They have also been used for developing methods for the analysis and synthesis of four-bar linkages for path generation.This paper focuses on a comparative study of Fourier descriptors derived from various shape signatures of planar closed curves.This includes representations based on Cartesian coordinates,centroid distance,cumulative angle,and curvature.The comparison is conducted not only using commonly used criteria for shape representation and identification but also in the context of shape based retrieval of kinematic constraints for task centered mechanism design.Examples are provided to seek to extract geometric constraints such as circle,circular arc,ellipse and line-segment from a given motion. 展开更多
关键词 Fourier descriptors kinematic constraints shape recognition and retrieval
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石墨烯增强功能梯度多孔梁材料不确定性对热机械过屈曲行为的影响
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作者 Fahed Mohd Mohammad Talha 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2023年第4期21-43,共23页
本文旨在研究石墨烯片增强功能梯度多孔梁材料不确定性对在热环境下的过屈曲行为的影响.通过采用随机有限元方法,已经完成了全面的确定性和随机性研究.考虑了温度依赖性(TD)和温度无关性(TID)的材料特性.使用Halpin-Tsai微力学模型估计... 本文旨在研究石墨烯片增强功能梯度多孔梁材料不确定性对在热环境下的过屈曲行为的影响.通过采用随机有限元方法,已经完成了全面的确定性和随机性研究.考虑了温度依赖性(TD)和温度无关性(TID)的材料特性.使用Halpin-Tsai微力学模型估计了杨氏模量等均质化有效材料性质,通过Voigt混合法则估计了密度和热膨胀系数.假设均质化的材料特性沿厚度方向以功能渐变的方式变化.所开发的公式基于高阶剪切变形理论,结合冯-卡门型几何非线性进行过屈曲分析.开发C^(0)有限元模型求解非线性控制方程组,使用直接迭代过程进行数值求解.所开发方法的收敛和验证研究也通过独立的蒙特卡罗模拟进行,以确保方法的准确性.分别讨论了材料设计参数如孔隙率含量、纳米填料量和材料特性(即杨氏模量、金属基体密度和纳米填料)的低变异性(随机性)等材料不确定性对FGGPLRC多孔梁热机械过屈曲行为的影响.结果表明,材料性能的不确定性会显著影响FG-GPLRC多孔梁的过屈曲响应. 展开更多
关键词 杨氏模量 功能梯度 蒙特卡罗模拟 纳米填料 温度依赖性 热膨胀系数 材料特性 直接迭代
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