Five-hundred-meter Aperture Spherical radio Telescope( FAST) is the largest sensitive single dish radio telescope in the world,in which the control and measurement of the feed is one crucial section of the FAST contro...Five-hundred-meter Aperture Spherical radio Telescope( FAST) is the largest sensitive single dish radio telescope in the world,in which the control and measurement of the feed is one crucial section of the FAST control system. Trilateration is presented to obtain three-dimensional coordinate for tracking feed focus cabin. Every three total stations chase prism movement to be attached on feed focus cabin and the prism position is determined from the measured distances based on the principle of trilateration. Therefore,feed position is determined from three prisms on the focus cabin. This study is to assess the accuracy and reliability of trilateration calculation on tracking focus cabin of FAST. Different arrangement of total stations on trilateration is theoretically studied. Through experiment,the proposed method shows that the accuracy is better than that of the polar coordinate measurement. The average root mean square error is lower than 0. 6 mm,which is found to have high accuracy and reliability.展开更多
Background:Findings from prior research into the effect of feeding methods on infant sleep are inconsistent.The objectives of this study were to examine infants'sleep patterns by feeding methods and sleep arrangem...Background:Findings from prior research into the effect of feeding methods on infant sleep are inconsistent.The objectives of this study were to examine infants'sleep patterns by feeding methods and sleep arrangement from birth to eight months old.Methods:This longitudinal cohort study enrolled 524 pregnant women at 34-41 weeks of gestation and their infants after delivery in 2006 and followed up until eight months postpartum.The study subjects were recruited from nine women and children hospitals in nine cities in China(Beijing,Chongqing,Wuhan,Changsha,Nanning,Xiamen,Xi'an,Jinan,and Hailin).Participating infants were followed up weekly during the first month and monthly from the second to the eighth month after birth.Twenty-four hour sleep diaries recording infants'sleeping and feeding methods were administered based on caregiver's self-report.Multivariable mixed growth curve models were fi tted to estimate the effects of feeding methods and sleep arrangement on infants'sleep patterns over time,controlling for maternal and paternal age,maternal and paternal education level,household income,supplementation of complementary food,and infant birth weight and length.Results:Exclusively formula fed infants had the greatest sleep percentage/24 h,followed by exclusively breast milk fed infants and partially breast milk fed infants(P<0.01).Night waking followed a similar pattern.However,the differences in sleep percentage and night waking frequency between exclusively formula and exclusively breast milk fed infants weakened over time as infants developed.In addition,compared to infants with bed-sharing sleep arrangement,those with room sharing sleep arrangement had greater daytime and 24-hour infant sleep percentage,whereas those with sleeping alone sleep arrangement had greater nighttime sleep percentage.Conclusions:Our data based on caregiver's selfreport suggested that partial breastfeeding and bedsharing may be associated with less sleep in infants.Health care professionals need to work with parents of newborns to develop coping strategies that will help prevent early weaning of breastfeeding.展开更多
基金Supported by the National Natural Science Foundation of China(No.11273001,11373001,11703046)
文摘Five-hundred-meter Aperture Spherical radio Telescope( FAST) is the largest sensitive single dish radio telescope in the world,in which the control and measurement of the feed is one crucial section of the FAST control system. Trilateration is presented to obtain three-dimensional coordinate for tracking feed focus cabin. Every three total stations chase prism movement to be attached on feed focus cabin and the prism position is determined from the measured distances based on the principle of trilateration. Therefore,feed position is determined from three prisms on the focus cabin. This study is to assess the accuracy and reliability of trilateration calculation on tracking focus cabin of FAST. Different arrangement of total stations on trilateration is theoretically studied. Through experiment,the proposed method shows that the accuracy is better than that of the polar coordinate measurement. The average root mean square error is lower than 0. 6 mm,which is found to have high accuracy and reliability.
基金supported by grants from maternal and children health hospitals of Xi'an,Wuhan,Changsha,Chongqing,Nanning,Beijing,Xiamen,Jinan and Hailin。
文摘Background:Findings from prior research into the effect of feeding methods on infant sleep are inconsistent.The objectives of this study were to examine infants'sleep patterns by feeding methods and sleep arrangement from birth to eight months old.Methods:This longitudinal cohort study enrolled 524 pregnant women at 34-41 weeks of gestation and their infants after delivery in 2006 and followed up until eight months postpartum.The study subjects were recruited from nine women and children hospitals in nine cities in China(Beijing,Chongqing,Wuhan,Changsha,Nanning,Xiamen,Xi'an,Jinan,and Hailin).Participating infants were followed up weekly during the first month and monthly from the second to the eighth month after birth.Twenty-four hour sleep diaries recording infants'sleeping and feeding methods were administered based on caregiver's self-report.Multivariable mixed growth curve models were fi tted to estimate the effects of feeding methods and sleep arrangement on infants'sleep patterns over time,controlling for maternal and paternal age,maternal and paternal education level,household income,supplementation of complementary food,and infant birth weight and length.Results:Exclusively formula fed infants had the greatest sleep percentage/24 h,followed by exclusively breast milk fed infants and partially breast milk fed infants(P<0.01).Night waking followed a similar pattern.However,the differences in sleep percentage and night waking frequency between exclusively formula and exclusively breast milk fed infants weakened over time as infants developed.In addition,compared to infants with bed-sharing sleep arrangement,those with room sharing sleep arrangement had greater daytime and 24-hour infant sleep percentage,whereas those with sleeping alone sleep arrangement had greater nighttime sleep percentage.Conclusions:Our data based on caregiver's selfreport suggested that partial breastfeeding and bedsharing may be associated with less sleep in infants.Health care professionals need to work with parents of newborns to develop coping strategies that will help prevent early weaning of breastfeeding.
