We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase ...We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase shift and contrast of the interference fringe are experimentally investigated. The results show that the contrast of the interference fringe is well held when the platform is rotated, and the phase shift of the interference fringe is linearly proportional to the rotation rate of the platform. The long-term stability, which is evaluated by the overlapped Allan deviation, is 8.5 × 10^-6 rad/s over the integrating time of 1000s.展开更多
In order to fabricate a large-aperture continuous phase plate(CPP) using atmospheric pressure plasma processing(APPP) with high efficiency and precision, the position dwell mode and velocity mode were proposed and...In order to fabricate a large-aperture continuous phase plate(CPP) using atmospheric pressure plasma processing(APPP) with high efficiency and precision, the position dwell mode and velocity mode were proposed and the iterative calculation method was developed for the non-constant removal rate. Two 320 mm × 320 mm × 2 mm CPPs were fabricated with two processing modes. The experiment results show that the velocity mode is capable of significantly reducing the processing time and shape error. The total processing time is decreased from 13.2 h to 9.3 h, and the surface shape error is decreased from 0.158λ to 0.119λ(λ = 632.8 nm)(root mean square).展开更多
Background:Sustainable land management is considered as one of the useful approaches to combat the threat of various forms of land degradation in Ethiopia.Despite this,there is scant information regarding households’...Background:Sustainable land management is considered as one of the useful approaches to combat the threat of various forms of land degradation in Ethiopia.Despite this,there is scant information regarding households’decision towards the implementation of sustainable land management practices.This paper,therefore,looks into the determinants for the continued use and choice of the sustainable land management practices by smallholder farmers and its productivity effect in three randomly chosen districts in Tigrai region,Ethiopia.The study uses data from household survey and key informant interviews.The paper employs a binary logit to analyze the determinants for the decision of continued use of sustainable land management practices,and a multivariate probit to analyze the simultaneous adoption decision of sustainable land management practices using cross sectional data collected from 230 randomly selected households.The impact of sustainable land management practices was also evaluated using propensity score matching.Results:Farming techniques,wealth status,agro-ecological variations,and plot level characteristics were found to be associated with the implementation decision of sustainable land management practices by rural households.Besides,institutional supports and access to basic infrastructures influenced the overall continued use of sustainable land management practices and the preference of households toward these practices.The study also finds that the value of crop production of sustainable land management users was on average 77–100%higher than that of nonusers.Conclusions:The results of the current study confirm that the implementation of various sustainable land management practices are influenced by farming technologies deployed by rural households,agro-ecological variations,plot characteristics,and institutional supports.The findings also affirm that most of the sustainable land management practices are complementary to one another,and implementing two or more sustainable land management practices on a given plot is highly associated with higher value of crop production.Such complementarity highlights that the productivity effect of a given sustainable land management practice is enhanced by the use of the other ones.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11227083 and 91536221
文摘We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase shift and contrast of the interference fringe are experimentally investigated. The results show that the contrast of the interference fringe is well held when the platform is rotated, and the phase shift of the interference fringe is linearly proportional to the rotation rate of the platform. The long-term stability, which is evaluated by the overlapped Allan deviation, is 8.5 × 10^-6 rad/s over the integrating time of 1000s.
基金supported by the National Natural Science Foundation of China(No.51175123)the National Science and Technology Major Project(No.2013ZX04006011-205)
文摘In order to fabricate a large-aperture continuous phase plate(CPP) using atmospheric pressure plasma processing(APPP) with high efficiency and precision, the position dwell mode and velocity mode were proposed and the iterative calculation method was developed for the non-constant removal rate. Two 320 mm × 320 mm × 2 mm CPPs were fabricated with two processing modes. The experiment results show that the velocity mode is capable of significantly reducing the processing time and shape error. The total processing time is decreased from 13.2 h to 9.3 h, and the surface shape error is decreased from 0.158λ to 0.119λ(λ = 632.8 nm)(root mean square).
文摘Background:Sustainable land management is considered as one of the useful approaches to combat the threat of various forms of land degradation in Ethiopia.Despite this,there is scant information regarding households’decision towards the implementation of sustainable land management practices.This paper,therefore,looks into the determinants for the continued use and choice of the sustainable land management practices by smallholder farmers and its productivity effect in three randomly chosen districts in Tigrai region,Ethiopia.The study uses data from household survey and key informant interviews.The paper employs a binary logit to analyze the determinants for the decision of continued use of sustainable land management practices,and a multivariate probit to analyze the simultaneous adoption decision of sustainable land management practices using cross sectional data collected from 230 randomly selected households.The impact of sustainable land management practices was also evaluated using propensity score matching.Results:Farming techniques,wealth status,agro-ecological variations,and plot level characteristics were found to be associated with the implementation decision of sustainable land management practices by rural households.Besides,institutional supports and access to basic infrastructures influenced the overall continued use of sustainable land management practices and the preference of households toward these practices.The study also finds that the value of crop production of sustainable land management users was on average 77–100%higher than that of nonusers.Conclusions:The results of the current study confirm that the implementation of various sustainable land management practices are influenced by farming technologies deployed by rural households,agro-ecological variations,plot characteristics,and institutional supports.The findings also affirm that most of the sustainable land management practices are complementary to one another,and implementing two or more sustainable land management practices on a given plot is highly associated with higher value of crop production.Such complementarity highlights that the productivity effect of a given sustainable land management practice is enhanced by the use of the other ones.