Medical 3D image reconstruction is an important image processing step in medical image analysis. How to speed up the speed while improving the accuracy in 3D reconstruction is an important issue. To solve this problem, this paper proposes a 3D reconstruction method based on image feature point matching. By improving SIFT, the initial matching of feature points is realized by using the neighborhood voting method, and then the initial matching points are optimized by the improved RANSAC algorithm, and a new SFM reconstruction method is obtained. The experimental results show that the feature matching rate of this algorithm on Fountain data is 95.42% and the matching speed is 4.751 s. It can be seen that this algorithm can shorten the reconstruction time and obtain sparse point clouds with more reasonable distribution and better reconstruction effect.

Abstract. Aluminum metal matrix composites (Al-MMCs) with Al 2 O 3 particulates as reinforcement fabricated by the power metallurgy (PM) methods have gained much attention due to their unique characteristics of the wide range of Al 2 O 3 particles addition, easy-operating process and effectiveness. The improved PM techniques, such as the high energy ball milling, powder extruder and high pressure torsion were applied to further strengthening the properties or/and diminishing the agglomeration of strength particles. The formation of liquid phase assisted densi¿cation of compacts to promote the sintering of composites. Complex design of Al 2 O 3 particles with other particles was another efficient method to tailor the properties of Al-MMCs.

Five kinds of heating treatment processing were chosen according to the experiment result of differential scanning calorimeter to prepare SiO 2 -Al 2 O 3 -MgO-K 2 O-F glass ceramics samples. The effects of heat treatment processing on the crystallization of these samples were explored by X-ray diffraction and scanning electron microscopy techniques. The results indicate that phase separations can occur in the bulk regions of the glass sample when holding at 670 ℃ for 3 h. The phase separation can accelerate the precipitation of the crystallization phase: when the temperature directly rises to 950 ℃ after the phase separation, there are mainly interlocked plate-shapes mica phases; If holding at 860 ℃ for 3 h fi rst after the phase separation, the star-shape cordierite phases form; Thereby, elevating temperature to 950 ℃ and holding for 1 h will bring plate-shapes mica phases growing at inter-phases of the star-shape cordierite and fi nally the homogeneously distributed micacordierite composites form. However, if heating at 950 ℃ directly without holding at 670 ℃, there is a small quantity of phase separation appearing at 670 ℃ and a little crystallization phases precipitating at last.

Abstract. Aluminum metal matrix composites (Al-MMCs) with Al 2 O 3 particulates as reinforcement fabricated by the power metallurgy (PM) techniques have gained much attention due to their unique characteristics, which combine the roles of the process method, Al 2 O 3 particles and aluminum matrix. The contents and sizes, locations and dispersion of Al 2 O 3 particles on the matrix affect the mechanical behaviors and ultimate properties of the composites, which depend on microstructure of the final composites, usually including porosity, the grain size of composites and the dispersion of Al 2 O 3 particle in the matrix. The agglomeration and segregation of the particles deteriorate the mechanical properties of composites.