为提高工业机器人整体性能,减小其静动态性能误差,提出一种综合考虑工业机器人连杆和关节柔性的拓扑优化方法。将机器人动力学与拓扑优化相结合,以变密度法(Solid isotropic material with penalization,SIMP)为基础,通过线性加权和法...为提高工业机器人整体性能,减小其静动态性能误差,提出一种综合考虑工业机器人连杆和关节柔性的拓扑优化方法。将机器人动力学与拓扑优化相结合,以变密度法(Solid isotropic material with penalization,SIMP)为基础,通过线性加权和法建立工业机器人大臂的多目标拓扑优化函数模型,基于柔性多体动力学理论,利用有限元软件和多体动力学软件建立含关节、连杆柔性的机器人刚柔耦合动力学仿真模型,获得机器人在极限工况下大臂载荷谱,最后,利用层次分析法确定优化目标函数中各子目标的权重系数,并对函数进行求解。优化结果显示,优化后机器人大臂刚度和固有频率都得到提高,并且质量下降18.71%。通过虚拟样机技术重构机器人模型,并对其整体进行分析,结果表明,最大负载作用下,机器人最大变形量从0.208 mm降至0.188 mm,静态变形量误差减小9.62%;动态定位误差从0.777 mm降至0.687 mm,定位精度提高11.58%。上述拓扑优化方法为提升工业机器人整体静动态性能提供了有效的理论参考。展开更多
人类活动与全新世环境变化的耦合过程与机理已成为地球科学领域的研究热点。湖泊沉积物储存了丰富的环境信息,已成为反演过去气候变化的良好材料。目前古环境代用指标指示人类活动的研究多通过单一湖泊进行讨论,缺乏一定的整体区域研究...人类活动与全新世环境变化的耦合过程与机理已成为地球科学领域的研究热点。湖泊沉积物储存了丰富的环境信息,已成为反演过去气候变化的良好材料。目前古环境代用指标指示人类活动的研究多通过单一湖泊进行讨论,缺乏一定的整体区域研究,且通过古环境代用指标辨识该区域人类活动的研究相对较少,指示人类活动的古环境代用指标具有不确定性。本文分析了祁连山周边内流河流域14个终端湖泊的岩性、年代和古环境代用指标数据,重建了该区域全新世以来的气候变化,探索了全新世以来气候变化与人类活动的耦合关系。初步结果如下:全新世以来祁连山及周边地区终端湖泊中有机质多为水生和陆生植物混合来源;祁连山地区早中全新世气候温暖湿润,晚全新世以来气候干旱化明显;古环境代用指标变化与沉积相变化密切相关,不同沉积相对应的代用指标指示意义差异较大,2.0 cal ka BP以来湖泊沉积相的变化开始受到人类活动影响,距今200 a左右开始,人类活动对区域环境变化起主导作用。展开更多
Three crosses,Hawaii7981×PI128216,Hawaii7981×LA1589,and PI128216×LA1589,were made to develop F_2 populations for testing allelism among three genes Xv3,Rx4,and Rx_(LA1589) conferring resistance to bacte...Three crosses,Hawaii7981×PI128216,Hawaii7981×LA1589,and PI128216×LA1589,were made to develop F_2 populations for testing allelism among three genes Xv3,Rx4,and Rx_(LA1589) conferring resistance to bacterial spot caused by Xanthomonas perforans race T3 in tomato. Each population consisted of 535–1 655 individuals. An infiltration method was used to inoculate the leaves of the parental and F_2 plants as well as the susceptible control OH88119 for detecting hypersensitive resistance(HR). The results showed that all the tomato plants except OH88119 had HR to race T3,indicating that Xv3,Rx4,and Rx_(LA1589) were allelic genes. Genomic DNA fragments of the Rx4 alleles from Hawaii7981,PI128216,and LA1589 were amplified using gene-specific primers and sequenced. No sequence variation was observed in the coding region of Rx4 in the three resistant lines. Based on the published map positions of these loci as well as the allelic tests and sequence data obtained in this study,we speculated that Xv3,Rx4,and Rx_(LA1589) were the same gene. The results will provide useful information for understanding the mechanism of resistance to race T3 and developing resistant tomato varieties.展开更多
文摘为提高工业机器人整体性能,减小其静动态性能误差,提出一种综合考虑工业机器人连杆和关节柔性的拓扑优化方法。将机器人动力学与拓扑优化相结合,以变密度法(Solid isotropic material with penalization,SIMP)为基础,通过线性加权和法建立工业机器人大臂的多目标拓扑优化函数模型,基于柔性多体动力学理论,利用有限元软件和多体动力学软件建立含关节、连杆柔性的机器人刚柔耦合动力学仿真模型,获得机器人在极限工况下大臂载荷谱,最后,利用层次分析法确定优化目标函数中各子目标的权重系数,并对函数进行求解。优化结果显示,优化后机器人大臂刚度和固有频率都得到提高,并且质量下降18.71%。通过虚拟样机技术重构机器人模型,并对其整体进行分析,结果表明,最大负载作用下,机器人最大变形量从0.208 mm降至0.188 mm,静态变形量误差减小9.62%;动态定位误差从0.777 mm降至0.687 mm,定位精度提高11.58%。上述拓扑优化方法为提升工业机器人整体静动态性能提供了有效的理论参考。
文摘人类活动与全新世环境变化的耦合过程与机理已成为地球科学领域的研究热点。湖泊沉积物储存了丰富的环境信息,已成为反演过去气候变化的良好材料。目前古环境代用指标指示人类活动的研究多通过单一湖泊进行讨论,缺乏一定的整体区域研究,且通过古环境代用指标辨识该区域人类活动的研究相对较少,指示人类活动的古环境代用指标具有不确定性。本文分析了祁连山周边内流河流域14个终端湖泊的岩性、年代和古环境代用指标数据,重建了该区域全新世以来的气候变化,探索了全新世以来气候变化与人类活动的耦合关系。初步结果如下:全新世以来祁连山及周边地区终端湖泊中有机质多为水生和陆生植物混合来源;祁连山地区早中全新世气候温暖湿润,晚全新世以来气候干旱化明显;古环境代用指标变化与沉积相变化密切相关,不同沉积相对应的代用指标指示意义差异较大,2.0 cal ka BP以来湖泊沉积相的变化开始受到人类活动影响,距今200 a左右开始,人类活动对区域环境变化起主导作用。
基金supported by the National Natural Science Foundation of China(Grant No.31372073)Beijing Modern Agro-industry Technology Research System(Grant No.GCTDZJ2014033001)
文摘Three crosses,Hawaii7981×PI128216,Hawaii7981×LA1589,and PI128216×LA1589,were made to develop F_2 populations for testing allelism among three genes Xv3,Rx4,and Rx_(LA1589) conferring resistance to bacterial spot caused by Xanthomonas perforans race T3 in tomato. Each population consisted of 535–1 655 individuals. An infiltration method was used to inoculate the leaves of the parental and F_2 plants as well as the susceptible control OH88119 for detecting hypersensitive resistance(HR). The results showed that all the tomato plants except OH88119 had HR to race T3,indicating that Xv3,Rx4,and Rx_(LA1589) were allelic genes. Genomic DNA fragments of the Rx4 alleles from Hawaii7981,PI128216,and LA1589 were amplified using gene-specific primers and sequenced. No sequence variation was observed in the coding region of Rx4 in the three resistant lines. Based on the published map positions of these loci as well as the allelic tests and sequence data obtained in this study,we speculated that Xv3,Rx4,and Rx_(LA1589) were the same gene. The results will provide useful information for understanding the mechanism of resistance to race T3 and developing resistant tomato varieties.
