To solve higher-order elliptic gear manufacturing problems, this paper researches the pitch curves of higher-order elliptic gear and its transmission features, and creates the judgment method whether hobbing process can be applied. The four-axle three-linkage hobbing model for spur gear and the four-axle four-linkage hobbing model for helical gear are built by using tools (inclined) rack based on four-axle linkage strategy. This work provided the theory foundation for the manufacturing modular of higher-order elliptic gear in CNC System.

To solve higher-order elliptic gear manufacturing problems, this paper builds the model of hobbing process based on higher-order elliptic gear equation, and researches the graphic simulation technology of hobbing process by using tools (inclined) rack. Four higher-order elliptic spur gears and helical gears with different parameters are simulated by Matlab, to verify the processing model built and the condition of hobbing process can be applied. This work provided the theory foundation for the manufacturing modular of higher-order elliptic gear in CNC System and the reference for its manufacture.

To solve the defect of being not extended for curves in some CAD software, the trend extrapolation principle was imported and the intelligent extension technology for curves was discussed in this paper. The methods of identifying and choosing the trend extrapolation model are provided. Three mathematical models including polynomial curve extension, Gompertz curve extension and exponential curve extension were built, which can be adopted according to the feature points in curves reasonably. This paper has solved the common and core problems, which can be applied to CAD software upgrade or re-development.

To achieve the concise interpolation for spatial curves, the strategy of cross-octant interpolation was researched based on open-architecture CNC system. The sub-modules of the interpolation module for complete software type CNC system or NC embedded PC type system were designed. Take cylinder spiral-line and spatial line for instance, some studies that include principles and techniques of affine transformation, automatic cross-octant, and calling basic sub-modules of interpolation were carried out. The interpolation module for open-architecture CNC system can be divided into some sub-modules to develop. Thus, the balance between the openness and the real-time of the system are achieved. Some strategies and principles in this paper can be also applied to other spatial curves.

To solve the problem that hydropower stations equipped with propeller turbine are not able to work under small flow conditions in dry seasons, after analyzing the influencing factors, a rebuilding scheme for decreasing capacity to increase efficiency is proposed. The distribution of velocity circulation at the inlet and the outlet is researched in this paper. Some key technologies in computer-aided hydraulic design, including unfolded aerofoil converted to cylindrical surface and intelligent extension for curves, are solved. The proposed version is feasible and the composed CAD software is reliable and accurate.