Papers by Author: W.H. Liao

Abstract: The principle of Hartmann-Shack wavefront sensor decided that the distance between micro-lens array and the CCD is the essence of reconstruction algorithm. Because of lacking way to measure the parameter and the existing of assembly error, it will obviously cause error by using the micro-lens focus instead of actual parameter. After analyzing the Zernike polynomial for describing wavrfront aberration, a new Self-reference method is given in this paper to calibrate the parameter. The method is based on the truth that the primary aberration of point light source is defocusing amount. Through this way, the requirement of sensor assembly-precision is reduced, and the detection accuracy of Hartmann-Shack sensor is also improved in the meanwhile. Satisfying results has been achieved under the normal experimental condition using the method given in this paper.

Abstract: With the honeycomb sandwich structure widely used in aerospace, the research of its mechanical properties becomes especially important. All of the finite element analysis software have no corresponding cell library, so before the analysis, the honeycomb sandwich panels should be equivalent processed. The paper by taking the floor of a microsatellite as the research object, used the equivalent plate theory and sandwich plate theory for equivalent processing, then adopted the finite element software to analyze the mechanical properties of the floor under two alternative condition. By compared with analytical solution, the equivalent results were reasonable, and the two methods were basically identical. Meanwhile, the equivalent results provided the reliable basis for the satellite structure optimum design and mechanical test.

Abstract: An efficient mesh model repair method is proposed in this paper, which can repair the holes with boundary continuity. It is mainly composed of the following steps: Firstly, the hole boundary is triangulated to generate the initial surface patch, of which the edges are distributed along the boundary averagely similar to an curtain covering at a window. Secondly, the initial surface patch is refined, and the interior edges are relaxed while refining to get a Delaunay-like refinement surface patch, which approximates the density of the surrounding mesh. Finally, the refinement surface patch is reshaped based on the minimization of the surface energy solved by the order discrete Euler-Lagrange equation in order to realize the continuity repair. The proposed method is proved to be efficient and robust by experiments of different kinds of boundary conditions.

Abstract: An enhanced product representation model was introduced, and it was specified with the sets of property, the sets of the multiplicity of modules, and the sets of relationships among them. A multi-case base corresponding complex product decomposition was established. Cases were defined and edited on customization template, which improved efficiency of developing multi-case base. For an example, a design tool for diesel engine development based on multi-case base was developed, and diesel engine product development could be more rapidly.

Abstract: Feature-based programming is one of tendency of NC programming technology, and it is also an important portion for CAD/CAPP/CAM integration in the manufacturing enterprises. Because of selecting geometry repeatedly, random programming and bad integration during programming for the aircraft NC parts, the technology of rapid programming based on features is put forward in this paper. On the basis of features, the technology of feature recognition for aircraft NC parts and the algorithm of tool path generation based on features are integrated by taking XML as data transfer standard. With this method, the programming for aircraft NC parts can be realized quickly in the condition of CAD/CAPP/CAM integration. The system developed has been well applied to the programming for aircraft NC parts in an aircraft corporation.

Abstract: Few existing systems can support the reuse of conceptual design knowledge due to the lack of satisfying modeling technologies. In the present study, we investigated the ontology-based modeling technologies and apply them to develop a framework of conceptual design knowledge management. The practicability and validity of our framework were then examined in a Construction Machinery Design Knowledge Management System.