Papers by Author: Yue Hua Wan

Abstract: An appropriate shape designing of a snowboard course (currently known as a "halfpipe") is the precondition to achieve higher scores in a competition. We divided the whole process into four procedures: Air, Transition Processes and Pump, Twist Techniques. Elliptical transition of a halfpipe was put forward instead of the traditional circular one to optimize the shape, by simplifying this problem into some dynamical partial differential equations. We proved three theorems and used numerical methods to calculate the optimal value. The optimal shape we designed is mainly based on the initial velocity and combines all the known targets into two calculable physical variables. Simulation with common parameters from FIS indicates that our results accord with the practice and gives us the optimal shape of the snowboard courses for various levels of competition with different initial velocities. Plenty of sensitivity analysis shows that our designing is robust.

Abstract: Geographic profiling uses locations of series crimes to detect the most probable residence of the offender. However, because of shortage of other information, the method doesn't perform well. To Solve this problem, the concept of geographic profiling was extended and a concept of human geographic profiling (HGP) was put forward to take offender’s bias, victims’ characteristics, and geographical circumstances into account. The physical geographic profiling (PGP) was obtained by combining an improved “spatial mean” method and an improved criminal geographic targeting (CGT) model by using a precisely deduced "Combination Function". Afterwards, HGP and PCG were combined by the same function. The resultant product was a three-dimentional probability map. Simulation result indicated high accuracy rates among which the lowest is 66% under an ideal situation. The introduction of HGP and deduction of combination function are discussed originally and are of great importance in this paper.

Abstract: The polishing robot can serve the polishing work and realize the fully automation for obtaining much higher polishing efficiency and well-proportioned surface quality which attracts many researchers’ attention. In this reviews, the research status of the polishing robot are summarized. Twenty-eight articles which published these years about the polishing robot are introduced in brief. The robot system for complex surfaces polishing, automation of polishing process for a cavity surface, intelligently automated polishing abrasive polishing, the CAD/CAM-based position/force controller for a mold polishing robot and so on are reviewed. More research on an effective gasbag polishing technique based on the novel spinning-inflated-gasbag polishing tool, which can obtain well-proportioned quality surface and high polishing efficiency is a potential one. Investigations of the polishing robot will be helpful for the readers understand the robotic polishing.

Abstract: Saw-tooth chip has great effect on the dynamic cutting forces, cutting temperature waviness, PCBN tool life and surface integrity during precision hard part machining. The forming and finish process of saw-tooth chip could be observed through different high frequencies of dynamic cutting forces by wavelet analysis. According to the cutting speed, feed rate, sampling frequency and time, the characteristic parameters of saw-tooth chip type and shear instability could be calculated based on the saw-tooth chip forming frequency formula supported by M.C.Shaw theory. The forming frequency of saw-tooth chip was far smaller than high frequency of cutting forces under the normal cutting parameters during precision hard part machining process, and will be moved similar equal to each other under the high cutting speed. Experimental results and analysis show that the basic characteristics of saw-tooth chip could be calculated through dynamic cutting forces wavelet analysis.

Abstract: Surface integrity of Sapphire wafer is the frontier technology to grow high quality AlN/GaN films for high brightness light-emitting diode. Surface damage measurement methods for single crystal sapphire were introduced firstly. Classical types of surface deformation induced by abrasive machining, such as lattice deformation, strain, scratch, crack versus abrasive grits and chemical reaction were compared. With the development of modern grinding technology, depth of the damaged surface layer decreases from 10μm to 2μm or much less. Both crack, lattice deformation, twinning and strain were detected along the ground surface, only dislocation and strain were appeared for polished sapphire surface. Usually, depth of the damaged layer was less than 300nm using mechanical polishing process. Chemical mechanical polishing achieved the lowest depth of the damaged surface and best surface roughness, scratch depth was used to descript the damaged depth, which is about 1 nm, and so called no damage to the layer remains during chemical mechanical polishing process.

Abstract: In this paper, a novel spinning-inflated-ballonet polishing tool for curved surface of mould is proposed. The head of the tool is a spherical spinning-inflated-ballonet whose inner air pressure can be controlled on-line and the head surface is covered with a suitable polishing cloth. The head can be rotated in high speed driven by an electromotor or high pressure airflow and its rotating speed can be adjusted. The flexibility of the head, the polishing force in radial direction and the contact area between the head surface and the curved surface of the work-piece can be controlled by adjusting the feeding deepness and ballonet pressure of the tool. The structure and the polishing mechanism of the novel polishing tool are introduced. The application of robot polishing system based on the novel polishing tool also is discussed. Finally the polishing control strategy of curved surface is researched.

Abstract: In the field of the mold-curved free surface polishing, how to control the removing depth of the polishing surface exactly is one of the important problems to be solved. In this paper, a mould automatic polishing system that is developed on Motoman-NL20 robot is used to make theoretical analysis and experimental research on the removing depth of the polishing surface based on a novel Spinning-Inflated-ballonet Polishing tool for curved surface of mould. Firstly, FEM (finite element analysis) software is used to emulate three kinds of situation in the process of polishing, then the model of surface removing depth of SBCT polishing is established. At last, through the analysis and comparison, the result of emulation and experiment has a remarkable consistency which accords with the model established by formal theory. This indicates the correctness of the model.