我们所以在 New Science一栏中郑重推出此文,除了儿童的身高问题不能小视之外,另一重要原因是针对目前各类广告对儿童身高的误导宣传。此类广告给人的印象是,似乎服用了他们的产品,儿童的身高就会迅速“达标”.而且儿童身高未能“达标...我们所以在 New Science一栏中郑重推出此文,除了儿童的身高问题不能小视之外,另一重要原因是针对目前各类广告对儿童身高的误导宣传。此类广告给人的印象是,似乎服用了他们的产品,儿童的身高就会迅速“达标”.而且儿童身高未能“达标”的原因就是因为缺乏“钙”的摄入量！读罢此文,令我们走出误区,如梦初醒。本文对儿童发育迟缓,身高不足的问题条分缕析,严密科学。诚然.钙是 important hone-building chemical,但是文章提醒读者;Vitamin D helps thebody to use calcium…But the vitamin must be changed,first by the liver andthen by the kidneys,before it can do this.由此可窥见“钙”被人体吸收的两个重要的先决条件。 文中的第 13条注释词为 cyproheptadine(赛庚啶).此药在我国被认定是用于治疗气喘、止痒等,而本文所述的此药的功能不知是否已被我国药界认识。 最后、本文提及了儿童身高的重要参数,似可参考:Generally,a child growsfive centimeters or more each year、Parents should talk to a doctor if a child’syearly growth falls below five centimeters.】展开更多
The clear differences between the atmosphere of Mars and the Earth coupled with the lack of a domestic research basis were significant challenges for the aerodynamic prediction and verification of Tianwen-1.In additio...The clear differences between the atmosphere of Mars and the Earth coupled with the lack of a domestic research basis were significant challenges for the aerodynamic prediction and verification of Tianwen-1.In addition,the Mars entry,descent,and landing(EDL)mission led to specific requirements for the accuracy of the aerodynamic deceleration performance,stability,aerothermal heating,and various complex aerodynamic coupling problems of the entry module.This study analyzes the key and difficult aerodynamic and aerothermodynamic problems related to the Mars EDL process.Then,the study process and results of the design and optimization of the entry module configuration are presented along with the calculations and experiments used to obtain the aerodynamic and aerothermodynamic characteristics in the Martian atmosphere.In addition,the simulation and verification of the low-frequency free oscillation characteristics under a large separation flow are described,and some special aerodynamic coupling problems such as the aeroelastic buffeting response of the trim tab are discussed.Finally,the atmospheric parameters and aerodynamic characteristics obtained from the flight data of the Tianwen-1 entry module are compared with the design data.The data obtained from the aerodynamic design,analysis,and verification of the Tianwen-1 entry module all meet the engineering requirements.In particular,the flight data results for the atmospheric parameters,trim angles of attack,and trim axial forces are within the envelopes of the prediction deviation zones.展开更多
文摘我们所以在 New Science一栏中郑重推出此文,除了儿童的身高问题不能小视之外,另一重要原因是针对目前各类广告对儿童身高的误导宣传。此类广告给人的印象是,似乎服用了他们的产品,儿童的身高就会迅速“达标”.而且儿童身高未能“达标”的原因就是因为缺乏“钙”的摄入量！读罢此文,令我们走出误区,如梦初醒。本文对儿童发育迟缓,身高不足的问题条分缕析,严密科学。诚然.钙是 important hone-building chemical,但是文章提醒读者;Vitamin D helps thebody to use calcium…But the vitamin must be changed,first by the liver andthen by the kidneys,before it can do this.由此可窥见“钙”被人体吸收的两个重要的先决条件。 文中的第 13条注释词为 cyproheptadine(赛庚啶).此药在我国被认定是用于治疗气喘、止痒等,而本文所述的此药的功能不知是否已被我国药界认识。 最后、本文提及了儿童身高的重要参数,似可参考:Generally,a child growsfive centimeters or more each year、Parents should talk to a doctor if a child’syearly growth falls below five centimeters.】
基金This research comes from the Tianwen-1 Mars exploration mission.The authors gratefully acknowledge the contributions of the entire Tianwen-1 design team.
文摘The clear differences between the atmosphere of Mars and the Earth coupled with the lack of a domestic research basis were significant challenges for the aerodynamic prediction and verification of Tianwen-1.In addition,the Mars entry,descent,and landing(EDL)mission led to specific requirements for the accuracy of the aerodynamic deceleration performance,stability,aerothermal heating,and various complex aerodynamic coupling problems of the entry module.This study analyzes the key and difficult aerodynamic and aerothermodynamic problems related to the Mars EDL process.Then,the study process and results of the design and optimization of the entry module configuration are presented along with the calculations and experiments used to obtain the aerodynamic and aerothermodynamic characteristics in the Martian atmosphere.In addition,the simulation and verification of the low-frequency free oscillation characteristics under a large separation flow are described,and some special aerodynamic coupling problems such as the aeroelastic buffeting response of the trim tab are discussed.Finally,the atmospheric parameters and aerodynamic characteristics obtained from the flight data of the Tianwen-1 entry module are compared with the design data.The data obtained from the aerodynamic design,analysis,and verification of the Tianwen-1 entry module all meet the engineering requirements.In particular,the flight data results for the atmospheric parameters,trim angles of attack,and trim axial forces are within the envelopes of the prediction deviation zones.
