According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total c...According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.展开更多
It is essential to measure the stitch length of weft knitted fabric in a static environment for economy and improving productivity. The image inputted was dealt with the digital image processing techniques： the paper...It is essential to measure the stitch length of weft knitted fabric in a static environment for economy and improving productivity. The image inputted was dealt with the digital image processing techniques： the paper carried out the transformation of grey scale; then removed impurities with filtering; the characteristic of the stitch structure was abstracted by using the Fourier transform technique. To obtain the stitch length more accurately, we should establish ageometric medal of the stitch lined on the digital image processing, which provides a way to transform the stitch length in the two-dimenslon space into a three-dimension space. This study provides a new methed for measuring the stitch length without damaging the fabric.展开更多
针对直升机飞行动力学建模参数优化问题,提出了一种基于粒子群的线性变参数模型预测控制(Linear parameter variable and model predictive control,LPV-MPC)优化设计,通过优化建模参数,提高直升机飞行动力学建模精度。基于经过滤波加...针对直升机飞行动力学建模参数优化问题,提出了一种基于粒子群的线性变参数模型预测控制(Linear parameter variable and model predictive control,LPV-MPC)优化设计,通过优化建模参数,提高直升机飞行动力学建模精度。基于经过滤波加权的前飞速度和横向速度对操纵量、姿态角、气动导数和操纵导数进行三维插值,对气动力进行实时计算,完成了UH-60直升机的LPV-MPC系统建模。采用粒子群优化算法,针对前飞速度插值间隔、横向速度插值间隔和滤波常数等三个建模参数进行优化。利用UH-60直升机非线性模型生成一系列用于优化的线性状态空间模型,对直升机纵向通道、横向通道同时给定激励进行仿真试验。仿真结果表明:在一定范围内任意选取的优化参数,经过粒子群寻优后,建立的LPV-MPV模型精度更高。展开更多
基金The National High Technology Research and Development Program of China(863 Program)(No.2005AA420240)the Key Science and Technology Program of Jiangsu Province (No.BE2005014)
文摘According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.
文摘It is essential to measure the stitch length of weft knitted fabric in a static environment for economy and improving productivity. The image inputted was dealt with the digital image processing techniques： the paper carried out the transformation of grey scale; then removed impurities with filtering; the characteristic of the stitch structure was abstracted by using the Fourier transform technique. To obtain the stitch length more accurately, we should establish ageometric medal of the stitch lined on the digital image processing, which provides a way to transform the stitch length in the two-dimenslon space into a three-dimension space. This study provides a new methed for measuring the stitch length without damaging the fabric.
文摘针对直升机飞行动力学建模参数优化问题,提出了一种基于粒子群的线性变参数模型预测控制(Linear parameter variable and model predictive control,LPV-MPC)优化设计,通过优化建模参数,提高直升机飞行动力学建模精度。基于经过滤波加权的前飞速度和横向速度对操纵量、姿态角、气动导数和操纵导数进行三维插值,对气动力进行实时计算,完成了UH-60直升机的LPV-MPC系统建模。采用粒子群优化算法,针对前飞速度插值间隔、横向速度插值间隔和滤波常数等三个建模参数进行优化。利用UH-60直升机非线性模型生成一系列用于优化的线性状态空间模型,对直升机纵向通道、横向通道同时给定激励进行仿真试验。仿真结果表明:在一定范围内任意选取的优化参数,经过粒子群寻优后,建立的LPV-MPV模型精度更高。
