It is illustrated that migration can make diffraction wave convergent and the diffraction from air can be recognized effectively with migration method by changing the migration velocity,which can provide the foundation for interpretation,thus improving precision of interpretation of GPR profiles.

In the light of the popularization and utilization of the HDPE hollow-wall twined pipes materials,this paper expounds the construction techniques and quality guaranteeing measures of the HDPE hollow-wall twined pipes from the excavation of the foundation ditch,the installation and connection of the pipelines,and the backfill of the pipelines,etc.

This paper discusses internal air launch scheme of a launch vehicle and mainly calculates the position and gesture of a rocket-parachute system before it is blasted off,and analysis its best launching time and gesture,and the effect of all parameters by the result of simulation.

This paper discusses internally air launch scheme of launch vehicle.

Based on the analysis of air launching spacecraft scheme of every country, this paper discusses several items of key technologies of air launching spacecraft, and analyzes the technology of plane vehicle seperation mostly.