The mobile laser-point cloud measurement system has been widely used in urban highprecision mapping. In some urban spaces with many high-rise buildings and indoor spaces, high-precision point cloud data cannot be directly obtained due to weak or no global navigation satellite system (GNSS) signals. We propose a space-constrained mobile vehicle-mounted laser scanning data acquisition plan that can effectively utilize the advantages of ground 3D laser scanning and mobile vehicle-mounted laser scanning. In addition, the plan adopts multi-source point cloud data fusion technology to obtain high-precision complete point cloud data both indoors and outdoors. The validity and reliability of the plan are verified by data acquisition experiments, which provide a useful reference for future high-precision mapping.

Delay fracture is an environmental embrittlement occurring when materials, environment and stress interact with each other and also a form of hydrogen induced material deterioration. It is a leading factor inhibiting the further improvement of strength of steel and iron material. Hence this study analyzed the improved low-carbon Mn-B type ultra-high strength steel plate (1500 MPa) which were processed by conventional heat treatment and heating forming technique and explored the effects of tempering temperature and heating forming technique on the performance of hydrogen induced delay fracture, which provides a reference for the actual application of such kind of steel plate. KEY WORDS: Hydrogen induced delay fracture; Environmental management technology.