Laboratory experiments were conducted for falling U-chain,but explicit analytic form of the general equations of motion was not presented.Several modeling methods were developed for fish robots,however they just focus...Laboratory experiments were conducted for falling U-chain,but explicit analytic form of the general equations of motion was not presented.Several modeling methods were developed for fish robots,however they just focused on the whole fish’s locomotion which does little favor to understand the detailed swimming behavior of fish.Udwadia-Kalaba theory is used to model these two multi-body systems and obtain explicit analytic equations of motion.For falling U-chain,the mass matrix is non-singular.Second-order constraints are used to get the constraint force and equations of motion and the numerical simulation is conducted.Simulation results show that the chain tip falls faster than the freely falling body.For fish robot,two-joint Carangiform fish robot is focused on.Quasi-steady wing theory is used to approximately calculate fluid lift force acting on the caudal fin.Based on the obtained explicit analytic equations of motion(the mass matrix is singular),propulsive characteristics of each part of the fish robot are obtained.Through these two cases of U chain and fish robot,how to use Udwadia-Kalaba equation to obtain the dynamical model is shown and the modeling methodology for multi-body systems is presented.It is also shown that Udwadia-Kalaba theory is applicable to systems whether or not their mass matrices are singular.In the whole process of applying Udwadia-Kalaba equation,Lagrangian multipliers and quasi-coordinates are not used.Udwadia-Kalaba theory is creatively applied to dynamical modeling of falling U-chain and fish robot problems and explicit analytic equations of motion are obtained.展开更多
目的 观察雷公藤甲素对血管内皮细胞迁移活性及尿激酶型纤溶酶原激活物(u- PA )表达的影响,探讨雷公藤甲素抑制血管生成的机制。方法 体外培养人脐静脉内皮细胞,传至第三代,接种于琼脂凝胶立体细胞培养系统后,加入不同质量浓度的雷公...目的 观察雷公藤甲素对血管内皮细胞迁移活性及尿激酶型纤溶酶原激活物(u- PA )表达的影响,探讨雷公藤甲素抑制血管生成的机制。方法 体外培养人脐静脉内皮细胞,传至第三代,接种于琼脂凝胶立体细胞培养系统后,加入不同质量浓度的雷公藤甲素(0 ,5 ,10 ,2 0 ,30μg/ L ) ,培养4 8h,观察内皮细胞的迁移活性;荧光定量RT- PCR检测u- PA m RNA的表达;免疫组织化学染色检测内皮细胞u- PA蛋白表达量。结果 雷公藤甲素可明显抑制内皮细胞的迁移活性,使细胞游走距离缩短;可减少内皮细胞u- PA m RNA和蛋白的表达。结论 雷公藤甲素可能通过基因水平干扰内皮细胞u- PA m RNA的表达,抑制u- PA蛋白的表达,从而有效地抑制血管内皮细胞迁移,这可能是雷公藤甲素抑制血管生成的主要机制之一。展开更多
文摘Laboratory experiments were conducted for falling U-chain,but explicit analytic form of the general equations of motion was not presented.Several modeling methods were developed for fish robots,however they just focused on the whole fish’s locomotion which does little favor to understand the detailed swimming behavior of fish.Udwadia-Kalaba theory is used to model these two multi-body systems and obtain explicit analytic equations of motion.For falling U-chain,the mass matrix is non-singular.Second-order constraints are used to get the constraint force and equations of motion and the numerical simulation is conducted.Simulation results show that the chain tip falls faster than the freely falling body.For fish robot,two-joint Carangiform fish robot is focused on.Quasi-steady wing theory is used to approximately calculate fluid lift force acting on the caudal fin.Based on the obtained explicit analytic equations of motion(the mass matrix is singular),propulsive characteristics of each part of the fish robot are obtained.Through these two cases of U chain and fish robot,how to use Udwadia-Kalaba equation to obtain the dynamical model is shown and the modeling methodology for multi-body systems is presented.It is also shown that Udwadia-Kalaba theory is applicable to systems whether or not their mass matrices are singular.In the whole process of applying Udwadia-Kalaba equation,Lagrangian multipliers and quasi-coordinates are not used.Udwadia-Kalaba theory is creatively applied to dynamical modeling of falling U-chain and fish robot problems and explicit analytic equations of motion are obtained.
文摘目的 观察雷公藤甲素对血管内皮细胞迁移活性及尿激酶型纤溶酶原激活物(u- PA )表达的影响,探讨雷公藤甲素抑制血管生成的机制。方法 体外培养人脐静脉内皮细胞,传至第三代,接种于琼脂凝胶立体细胞培养系统后,加入不同质量浓度的雷公藤甲素(0 ,5 ,10 ,2 0 ,30μg/ L ) ,培养4 8h,观察内皮细胞的迁移活性;荧光定量RT- PCR检测u- PA m RNA的表达;免疫组织化学染色检测内皮细胞u- PA蛋白表达量。结果 雷公藤甲素可明显抑制内皮细胞的迁移活性,使细胞游走距离缩短;可减少内皮细胞u- PA m RNA和蛋白的表达。结论 雷公藤甲素可能通过基因水平干扰内皮细胞u- PA m RNA的表达,抑制u- PA蛋白的表达,从而有效地抑制血管内皮细胞迁移,这可能是雷公藤甲素抑制血管生成的主要机制之一。
