Recent Advances in Space-Deployable Structures in China

Deployable space structure technology is an approach used in building spacecraft,especially when realizing deployment and folding functions.Once in orbit,the structures are released from the fairing,deployed,and positioned.With the development of communication,remote-sensing,and navigation satellites,space-deployable structures have become cutting-edge research topics in space science and technology.This paper summarizes the current research status and development trend of spacedeployable structures in China,including large space mesh antennas,space solar arrays,and deployable structures and mechanisms for deep-space exploration.Critical technologies of space-deployable structures are addressed from the perspectives of deployable mechanisms,cable-membrane form-finding,dynamic analysis,reliable environmental adaptability analysis,and validation.Finally,future technology developments and trends are elucidated in the fields of mesh antennas,solar arrays,deployable mechanisms,and on-orbit adjustment,assembly,and construction.

The Growth Path of Agricultural Labor Productivity in Major Grain Producing Areas

The growth of agricultural labor productivity in major grain producing areas arises from the increase in production factors or improvement of efficiency,and is related to the sustainability of agricultural economic growth and national food security. We study the growth path of agricultural labor productivity in 13 major grain producing areas of China,and the analysis results show that from the relative endowments of land and labor in major grain producing areas,the growth rate of the output value per unit of labor is higher than that of the productivity per unit of land; in essence,this growth path of increasing the output value relying on increasing the production factor inputs is the reduction of labor,and the reduction of agricultural labor has a great elasticity of impact on the total value of agricultural production. In the case of stable future number of agricultural labor in China,the growth of agricultural labor productivity will be impossible to rely more on the increase in agricultural production factor inputs,and the growth path of agricultural economy still has to rely on the improvement of land productivity and take the efficiency-based path.