The nitrogen-doped striations in axial-cut slice along \ direction of the as-grown crystal show that the convex growth front at the initial growth stage changes gradually into nearly flat growth front at the subsequent growth stages.

Regarding water resources as one of the elements of production,the efficient production frontier is built based on the DEA relative efficiency evaluation with C_2GS_2 model of output oriented.

Regarding water resources as one of the elements of production,the efficient production frontier is built based on the DEA relative efficiency evaluation with C~2GS~2 model and C~2R model of output oriented.

Regarding water resources as one of the elements of production,the efficient production frontier is built based on the DEA relative efficiency evaluation with C2GS2 model of output oriented.

A control rule for information of arbitrary boundaries in the goaf is made and regional mesh density function is based on the subdivision precision of known air leakage boundaries, then Delaunay triangular units are generated automatically by mesh subdivision technology of advancing front generation method.

Study on generation and development of production frontier theory;

Single-side support vector regression model for parametric production frontier analysis;

The approaches to evaluating DEA efficient DMUs(Decision Making Units) based on production frontier are studied.