Papers by Author: Yang Wang

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Authors: Xiao Dong Yang, Yang Wang, P. Yang
Abstract: In this paper, a teeth correction 3-D data modeling technology based on the basis of optical measurement is proposed. Using structured light measurement, the STL data of the teeth plaster model are obtained. Based on STL data, the topological relationship model of vertices and planes is constructed. The data of single tooth is separated with separation algorithm, and using matrix transform, geometrical transformation of teeth model is realized. Then, after establishing frame curves, the 3-D solid modeling of corrected tooth socket is constructed. At last, using the SLA technology, the colophony model of the remedying device is produced.
Authors: Shu Dong Xiu, Shi Jun Ji, Yang Wang
Abstract: A fast algebraic grid generation algorithm is proposed and a improved Kamaugh map data structure for the new algorithm is designed in the paper. The new created vertex inside of the region is based on algebraic operation of the corner vertices and the middle vertices of boundary broken lines on the region and the program data structure is a improved Kamaugh map data structure, so the algorithm has the merit of simple algebraic formula, quickly executing speed and powerful technology for the four-sided region enclosed by four broken lines, the algorithm is realized on the four-sided region and B-spline surface on the complex surface. The algorithm is extensively applicable for shape modeling in computer aided geometric design, industrial prototype design and reverse engineering.
Authors: Peng Xin Liu, Yang Wang
Abstract: Conventional engineering parts usually composed by algebraic surfaces are important investigation objects of reverse engineering. In this paper a step segmentation method for algebraic models is proposed. The mesh normals and curvedness of every vertex are estimated as a shape descriptor. In the first segmentation fourteen directions are chosen initially, and a k-means algorithm according to the normal vectors is used, then the surface is divided to form patches by a region-growing scheme, as well as some sharp edges or flat areas are detected. In order to identify algebraic surface, curvedness of a patch is set as the criterion by which the surface merged into near constant curvedness region. Especially a novel mean shift algorithm is adopted in this method, that a powerful technique for clustering in image process, and is extended to normal filtering while preserving the features to increase robustness of the method. Experimental evaluations using scan data or noise data demonstrate the efficiency of the proposed method.
Authors: Han Ming Lv, Shu Dong Xiu, Yang Wang
Abstract: A heuristic approach was presented to automatically partition a triangle meshes into a coarse quadrangular segmentation. The triangle mesh was firstly partitioned into a polygonal segmentation which will further be split into triangular and quadrangular patches. At last, the quadrangular segmentation was obtained by eliminating triangular patches according to their topological relations. The final segmentation consisted of pure-quadrangular patches with appropriate sizes according to the model’s geometric characteristics, and the features of input model were well captured. Experimental results showed that the algorithm was efficient and effective.
Authors: Li Jun Yang, Yang Wang
Abstract: Laser forming of metal sheet is a forming technology of sheet without a die that the sheet is deformed by internal thermal stress induced by partially irradiation of a laser beam. In this paper, the bending behavior of common stainless steel 1Cr18Ni9 sheet is studied after being irradiated by straight line with a Nd:YAG pulsed laser beam. The aim of the investigation is to find out the relationship of the physical behaviors of heat affected zone (HAZ) with the pulse parameters of the laser. Through the analysis of the fundamental theory of pulsed laser affected, this paper shows the affected characteristics of metal sheet with pulsed laser forming. The results show that the microstructure of HAZ of pulsed laser scanned is layered, and the micro-hardness is improved than that in matrix. The microstructures show that the deformed grain structure is inhomogeneous, that caused the grain sizes and grain orientations in HAZ to become different. By qualitative analysis of experimental result, the conclusion obtained may provide basis for theoretical investigation and possible industrial application of laser forming process in the future.
Authors: Bing Hui Liu, Li Jun Yang, J. Tang, Yang Wang, Ju Long Yuan
Abstract: In recent years, optical manipulators based on forces exerted by enhanced evanescent field close to near-field optical probes have provided the access to nonintrusive manipulation of nanometric particles. However, the manipulation capability is restricted to the intensity enhancement of the probe tip due to low emitting efficiency. Here a near-field optical trapping scheme using the combination of an optical fiber probe and an AFM metallic probe is developed theoretically. Calculations are made to analyze the field distributions including tip interaction and the trapping forces in the near-field region by applying a direct calculation of Maxwell stress tensor using three-dimensional FDTD. The results show that the scheme is able to trap particle at the nanoscale with lower laser intensity than that required by conventional near-field optical tweezers.
Authors: Bing Hui Liu, Li Jun Yan, Yang Wang
Abstract: New forms of trapping force are proposed for the design of near-field optical tweezers. Without the limitation of dipole approximation, the trapping force acting on a nano-particle located in near-field region can be solved by direct calculation of Maxwell stress tensor using 3D FDTD method. The new forms are used to design near-field optical trapping with a metal-coated fiber probe. Calculations show that the fiber probe can trap a nano-particle with tens of nanometres diameter to different positions with different distance from the probe tip. In order to achieve higher trapping capability, the feasibility of near-field trapping near the optical fiber probe after adding the AFM metallic probe is shown by analyzing trapping forces along three axis directions. The correctness of new forms is demonstrated by numerical results.
Authors: Hui Liu, Jun Yan Liu, Yang Wang, Hui Juan Li
Abstract: Lock-in thermography (LT), that is active infrared testing technology, mainly includes optical lock-in thermography (OLT) and ultrasound lock-in thermography (ULT). LT can be used to detect unbonds between honeycomb core and face sheet of sandwich structures. However, modulation frequency is an important influencing factor. In this paper, the principles of LT are represented, in experimental detections of simulated unbonds in honeycomb sandwich structures with Al-face sheet and CFRP-face sheet using OLT and ULT, detectability of OLT and ULT is compared and analyzed, effect of modulation frequency is researched and the optimal frequencies are obtained.
Authors: Sheng Dong Gao, Yang Wang, Yan Wu, Wen Bin Li
Abstract: The generation of uniform droplets in the size of hundred microns was described in this paper. An experimental device capable of producing uniform droplet has been developed. For the purpose of adjusting the signal generator for both continuous droplets spray and drop-on-demand, the piezoelectric driving signal was set up with a PC and software of Labview. With the signal generation system, Flexible signal adjustment appears to be more suitable than simple signal generator to generate uniform droplets.
Authors: Li Jun Yang, Jian Lei Cui, Yang Wang, Shou Wu Guo, Hui Xie, Li Ning Sun
Abstract: Dip-pen nanolithography (DPN), based on atomic force microscope (AFM) system, is an effective method for nanoscale science and engineering, and the potential applications of DPN will be shown in the field of nanomechanics, nanomaterials, nanobiotechnology, nanomedicine. And the novel combined-dynamic mode DPN (CDDPN), rather than mostly used contact mode DPN or tapping mode DPN, becomes the important tool for the fabrication of nanodots with the direct-writing method of depositing the ink onto the hard silicon surface at the predetermined position, which is presented in the corresponding experiments. In addition, the size of nanodots gradually decreases in the diameter with the increase of the number of nanodots in the case of AFM tip dipping in ink once. However, the size in height does not monotonically reduce as the reduction of the ink, which is affected by the interaction among the relative humidity, AFM tip, substrate material, surface roughness, etc. For the better nanolithography quality of the nanodot, the nanolithography process, under the optimized process parameters, is accomplished once without the intermediate scan imaging process as much as possible.
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