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The primary purpose of maritime delimitation is to ensure the maximum internal waters area obtained. In order to grantee the maximum internal waters area obtained with the selected base point, the idea and method of optimal selection of the territorial sea base points with the convex hull (minimum convex hull) construction technology is proposed. The ideal base points are selected by constructing convex hull for all alternative base points, which makes it possible to realize the automatic selection of base points under the principle of the maximum internal waters area.

The method for calculation of geodetic problem on earth ellipsoid surface is the basic premise for the realization of high-precision marine delimitation technology. Based on the analysis of the construction principle of the existing solution of geodetic problem method, the algorithm for direct geodetic problem solution(DGPS) based on nested coefficient method and Bessel’s inverse geodetic problem solution(IGPS), which are suitable for various distance solutions, are optimized. Then, the experimental verification scheme of the solution of geodetic problem is designed. Finally, the crossing and reducing accuracy of different calculation examples are verified by different geodetic problem solution methods, and the experiment shows that: the verified accuracy of point-position plotting, distance calculation and azimuth calculation meet the requirements of the indexes of high-precision marine delimitation.

This paper presents the experimental and numerical results of the effect process parameters on ovality in cross wedge rolling (CWR) for hollow engine valve without mandrel. Numerical simulation model for ovality was established by means of the rigid-plastic finite element modeling (FEM) method for hollow engine valve. The experiments and numerical analyses suggest that the following parameters represent the best conditions for CWR of hollow engine valve: 30°-34° for the forming angle( α ), 5°-7° for the stretching angle( β ), 0.2-0.3mm for the mold void width( L ), and 65%-70% for the area reduction( Ψ ).