A SYMMETRIC crying facies(ACF)is characterized by facial asymmetry only when crying.It may present as an exclusive symptom,or be concomitant with other congenital malformations and even some fatal birth defects.Clinic...A SYMMETRIC crying facies(ACF)is characterized by facial asymmetry only when crying.It may present as an exclusive symptom,or be concomitant with other congenital malformations and even some fatal birth defects.Clinically,ACF is featured by drooping of the intact corner of the mouth during crying,while the face appears symmetric展开更多
In the 90 years since its inception,radio astronomy has become the setting of almost all major astronomical discoveries and a hothouse for Nobel Prizes in Physics.As a result,countries all over the world have actively...In the 90 years since its inception,radio astronomy has become the setting of almost all major astronomical discoveries and a hothouse for Nobel Prizes in Physics.As a result,countries all over the world have actively explored new engineering concepts to build large-aperture radio telescopes.Limited by their self-weight and wind load,100 m radio telescopes are regarded as the maximum limit of traditional radio telescopes.This perspective allowed the Arecibo 305 m telescope—built by Cornell University in the United States in 1963—to dominate the field for more than half a century.During this period,scholars have been exploring how to further expand their horizons in order to make a breakthrough in the problem of the universe.展开更多
The Five-hundred-meter Aperture Spherical radio Telescope(FAST) is the largest and most sensitive single-dish radio telescope in the world and has made many important scientific achievements in a few years. Given the ...The Five-hundred-meter Aperture Spherical radio Telescope(FAST) is the largest and most sensitive single-dish radio telescope in the world and has made many important scientific achievements in a few years. Given the enormous scientific research potential of the Milky Way center, it is necessary to enhance the observation zenith angle as close to the Milky Way center as possible. In this regard, a new mechanism for the feed cabin is proposed with cables and sliders, which is lighter in weight and larger in the workspace. This paper will introduce this new feed cabin and the whole feed support system and establish their mechanical models to optimize the relevant control parameters, making FAST achieve an observation zenith angle of at least 50°with satisfying the required constraints. It indicates that the new mechanism designed by the FAST team can be used for the FAST upgrade and the future FAST array project.展开更多
文摘A SYMMETRIC crying facies(ACF)is characterized by facial asymmetry only when crying.It may present as an exclusive symptom,or be concomitant with other congenital malformations and even some fatal birth defects.Clinically,ACF is featured by drooping of the intact corner of the mouth during crying,while the face appears symmetric
基金financially supported by the National Natural Science Foundation of China(12225303,12003047,11973062,12273069,and 11973005)the National Key Research and Development Program of China(2019YFB1312705,2022YFA1602900,and 2018YFE0202900)+1 种基金the Youth Innovation Promotion Association CASthe Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CAS。
文摘In the 90 years since its inception,radio astronomy has become the setting of almost all major astronomical discoveries and a hothouse for Nobel Prizes in Physics.As a result,countries all over the world have actively explored new engineering concepts to build large-aperture radio telescopes.Limited by their self-weight and wind load,100 m radio telescopes are regarded as the maximum limit of traditional radio telescopes.This perspective allowed the Arecibo 305 m telescope—built by Cornell University in the United States in 1963—to dominate the field for more than half a century.During this period,scholars have been exploring how to further expand their horizons in order to make a breakthrough in the problem of the universe.
基金supported by the National Natural Science Foundation of China(Grant No.11973062)the Youth Innovation Promotion Association CAS(Grant No.Y2021025)+1 种基金the Cultivation Project for FAST Scientific Payoff and Research Achievement of Center for Astronomical Mega-Science,CASOpen Project Program of the Key Laboratory of FAST,National Astronomical Observatories,Chinese Academy of Sciences。
文摘The Five-hundred-meter Aperture Spherical radio Telescope(FAST) is the largest and most sensitive single-dish radio telescope in the world and has made many important scientific achievements in a few years. Given the enormous scientific research potential of the Milky Way center, it is necessary to enhance the observation zenith angle as close to the Milky Way center as possible. In this regard, a new mechanism for the feed cabin is proposed with cables and sliders, which is lighter in weight and larger in the workspace. This paper will introduce this new feed cabin and the whole feed support system and establish their mechanical models to optimize the relevant control parameters, making FAST achieve an observation zenith angle of at least 50°with satisfying the required constraints. It indicates that the new mechanism designed by the FAST team can be used for the FAST upgrade and the future FAST array project.
