A compliant metamorphic mechanism attributes to a new type of metamorphic mechanisms evolved from rigid metamorphic mechanisms. The structural characteristics and representations of a compliant metamorphic mechanism a...A compliant metamorphic mechanism attributes to a new type of metamorphic mechanisms evolved from rigid metamorphic mechanisms. The structural characteristics and representations of a compliant metamorphic mechanism are different from its rigid counterparts, so does the structural synthesis method. In order to carry out its structural synthesis, a constraint graph representation for topological structure of compliant metamorphic mechanisms is introduced, which can not only represent the structure of a compliant metamorphic mechanism, but also describe the characteristics of its links and kinematic pairs. An adjacency matrix representation of the link relationships in a compliant metamorphic mechanism is presented according to the constraint graph. Then, a method for structural synthesis of compliant metamorphic mechanisms is proposed based on the adjacency matrix operations. The operation rules and the operation procedures of adjacency matrices are described through synthesis of the initial configurations composed of s＋1 links from an s-link mechanism （the final configuration）. The method is demonstrated by synthesizing all the possible four-link compliant metamorphic mechanisms that can transform into a three-link mechanism through combining two of its links. Sixty-five adjacency matrices are obtained in the synthesis, each of which corresponds to a compliant metamorphic mechanism having four links. Therefore, the effectiveness of the method is validated by a specific compliant metamorphic mechanism corresponding to one of the sixty-five adjacency matrices. The structural synthesis method is put into practice as a fully compliant metamorphic hand is presented based on the synthesis results. The synthesis method has the advantages of simple operation rules, clear geometric meanings, ease of programming with matrix operation, and provides an effective method for structural synthesis of compliant metamorphic mechanisms and can be used in the design of new compliant metamorphic mechanisms.展开更多
Brassica napus cultivars have little or no primary dormancy;however,they are prone to sec on dary dorma ncy in ducti on.Secondary dormant seeds can produce volunteer plants,which can result in genetic contamination,re...Brassica napus cultivars have little or no primary dormancy;however,they are prone to sec on dary dorma ncy in ducti on.Secondary dormant seeds can produce volunteer plants,which can result in genetic contamination,reduced quality and biosafety issues.However,informati on regarding the molecular mecha nism un derlyi ng sec on dary dormancy is limited.The MOTHER OF FT AND TFL1(MFT)gene,which is evolutionarily conserved in the plant kingdom,acts in a complex gene network in the seed dormancy or germination processes.In this study,we identified four B.napus genes that share high homology with AtMFT,named as BnaMFT.Analyses of c/s-acting elements showed that BnaMFT promoters contain multiple seed-specific regulatory elements,and various stress-and hormone-responsive elements.Further experiments validated that BnaMFTs were specifically expressed during seed maturation and in the dry seed,with peaks at 35-42 days after pollination.BnaMFTs were not sufficient for primary dormancy;however,they were significantly enhanced by secondary dormancy induction with PEG6000 treatment.Moreover,BnaMFTtranscripts were elevated by treatment with abscisic acid(ABA),which is known to be accumulated duri ng sec on dary dorma ncy.These results collectively suggest that increased BnaMFT tra nscription levels are associated with sec on dary dorma ncy inducti on in an ABA-depe ndent mariner in B.napus.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51075039, Grant No. 50805110,Grant No. 50705010)Beijing Municipal Natural Science Foundation of China (Grant No. 3082014)the Fundamental Research Funds for the Central Universities of China (Grant No. 2009CZ08, Grant No. JY10000904010)
文摘A compliant metamorphic mechanism attributes to a new type of metamorphic mechanisms evolved from rigid metamorphic mechanisms. The structural characteristics and representations of a compliant metamorphic mechanism are different from its rigid counterparts, so does the structural synthesis method. In order to carry out its structural synthesis, a constraint graph representation for topological structure of compliant metamorphic mechanisms is introduced, which can not only represent the structure of a compliant metamorphic mechanism, but also describe the characteristics of its links and kinematic pairs. An adjacency matrix representation of the link relationships in a compliant metamorphic mechanism is presented according to the constraint graph. Then, a method for structural synthesis of compliant metamorphic mechanisms is proposed based on the adjacency matrix operations. The operation rules and the operation procedures of adjacency matrices are described through synthesis of the initial configurations composed of s＋1 links from an s-link mechanism （the final configuration）. The method is demonstrated by synthesizing all the possible four-link compliant metamorphic mechanisms that can transform into a three-link mechanism through combining two of its links. Sixty-five adjacency matrices are obtained in the synthesis, each of which corresponds to a compliant metamorphic mechanism having four links. Therefore, the effectiveness of the method is validated by a specific compliant metamorphic mechanism corresponding to one of the sixty-five adjacency matrices. The structural synthesis method is put into practice as a fully compliant metamorphic hand is presented based on the synthesis results. The synthesis method has the advantages of simple operation rules, clear geometric meanings, ease of programming with matrix operation, and provides an effective method for structural synthesis of compliant metamorphic mechanisms and can be used in the design of new compliant metamorphic mechanisms.
基金This work was funded by the National Natural Science Foundation of China(31470572 and 31701514)and the Qing Lan Project of Jiangsu Province,China(2016).
文摘Brassica napus cultivars have little or no primary dormancy;however,they are prone to sec on dary dorma ncy in ducti on.Secondary dormant seeds can produce volunteer plants,which can result in genetic contamination,reduced quality and biosafety issues.However,informati on regarding the molecular mecha nism un derlyi ng sec on dary dormancy is limited.The MOTHER OF FT AND TFL1(MFT)gene,which is evolutionarily conserved in the plant kingdom,acts in a complex gene network in the seed dormancy or germination processes.In this study,we identified four B.napus genes that share high homology with AtMFT,named as BnaMFT.Analyses of c/s-acting elements showed that BnaMFT promoters contain multiple seed-specific regulatory elements,and various stress-and hormone-responsive elements.Further experiments validated that BnaMFTs were specifically expressed during seed maturation and in the dry seed,with peaks at 35-42 days after pollination.BnaMFTs were not sufficient for primary dormancy;however,they were significantly enhanced by secondary dormancy induction with PEG6000 treatment.Moreover,BnaMFTtranscripts were elevated by treatment with abscisic acid(ABA),which is known to be accumulated duri ng sec on dary dorma ncy.These results collectively suggest that increased BnaMFT tra nscription levels are associated with sec on dary dorma ncy inducti on in an ABA-depe ndent mariner in B.napus.
