This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from ...This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.展开更多
A promoter\|signal peptide probe vector of lactic acid bacteria,designated pZLB based on pMG36e has been constructed.The vector contained a reporterd gene encoding for β lactamase,which lacked a promoter and a functi...A promoter\|signal peptide probe vector of lactic acid bacteria,designated pZLB based on pMG36e has been constructed.The vector contained a reporterd gene encoding for β lactamase,which lacked a promoter and a functional signal sequence.Sau3A restriction fragments (80-400bp) from L.lactis ATCC 7962 total DNA were cloned into Bam HI site of pZLB.A lot of different size framents were selected.These fragments promoted transcription and secretion of β lactamase in L.lac tis. Sequence analysis revealed that inserted fragment in pZLBe7 contained typical promoter,SD sequence and atypical signal sequence.展开更多
文摘This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.
文摘A promoter\|signal peptide probe vector of lactic acid bacteria,designated pZLB based on pMG36e has been constructed.The vector contained a reporterd gene encoding for β lactamase,which lacked a promoter and a functional signal sequence.Sau3A restriction fragments (80-400bp) from L.lactis ATCC 7962 total DNA were cloned into Bam HI site of pZLB.A lot of different size framents were selected.These fragments promoted transcription and secretion of β lactamase in L.lac tis. Sequence analysis revealed that inserted fragment in pZLBe7 contained typical promoter,SD sequence and atypical signal sequence.
