Diamond films were prepared at different grid bias and substrate bias in hot filament chemical vapor deposition (HFCVD) system. The Raman and SEM results show that grain size decreases and non-diamond impurities incre...Diamond films were prepared at different grid bias and substrate bias in hot filament chemical vapor deposition (HFCVD) system. The Raman and SEM results show that grain size decreases and non-diamond impurities increase for applying grid and substrate bias currents. The defects and impurities in the film increase with the decrease of grain size, which causes the decrease of hardness and elastic modulus of diamond films. The fracture toughness of film increases because of the grain size effects by applying bias. The grid bias and substrate bias make the friction coefficient smaller because of the smaller grain size and lubricating effect of graphite in the film. But the excessively high substrate bias current will lead to the dramatic decrease of mechanical properties of CVD diamond as a lot of non-diamond impurities appear in the film.展开更多
Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room tem...Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.展开更多
Although the uniformity of diamond discrete global grid is essential for calculations and searches,geometric deformations increase with the level of divisions.The Good child Criteria provides a basis for evaluating th...Although the uniformity of diamond discrete global grid is essential for calculations and searches,geometric deformations increase with the level of divisions.The Good child Criteria provides a basis for evaluating the quality of the global grid.However,some indicators in the criteria are redundant and contradictory,and the existing indicator system has limitations.Directly using the indicator system may render the evaluation of the diamond grid unreliable.In this study,we summarized the evaluation indicators for grid quality basedon the Good child Criteria,calculated the correlations between these indicators using different diamond grid systems,and constructed reliable evaluation systems based on similarities and differences.The selected grid systems are classified into two groups:non-equal-area and equal-area grids.Their quality evaluation systems are composed of Size-Shape-Topology Factor and Geometry-Topology Factor,respectively.The proposed quality evaluation systems utilize a minimal number of indicators selected from each factor to provide a comprehensive description of the diamondgrid’s characteristics.This approach simplifies the complexity of the evaluations while improving their reliability and credibility.展开更多
为了从格网剖分结构上解决分块LOD(Level Of Details)模型中复杂的块内、块间裂缝问题,避免目前裂缝消除方法的缺陷,该文提出一种基于多分辨率半边结构的分块LOD模型无缝表达方法。首先,引入多分辨率组合映射理论,给出基于多分辨率半边...为了从格网剖分结构上解决分块LOD(Level Of Details)模型中复杂的块内、块间裂缝问题,避免目前裂缝消除方法的缺陷,该文提出一种基于多分辨率半边结构的分块LOD模型无缝表达方法。首先,引入多分辨率组合映射理论,给出基于多分辨率半边的菱形块多尺度表达的基本方法,包括菱形块剖分方法和编码方法;在此基础上,提出块内、块间格网无缝表达机制,设计并实现了基于菱形块的全球地形动态LOD管理机制;最后,应用C语言和DirectX工具,开发了相应的可视化实验系统。实验表明:该方法从格网剖分结构上解决了全球地形分块LOD模型中的块内、块间裂缝问题;与传统方法相比,其不需要限制相邻格网的剖分层差,简化效率更高,且无地形失真。展开更多
为了表现海浪的真实感和实时性仿真,本文以Pierson-Moskowitz模型为基础,采用波的波长和波速建立了海浪波高的初始状态值.通过FBM(Fractal Brown Motion)的菱形网格方式计算海浪曲面片上每个网格点的波高,把每个点画出;再以菱形网格模...为了表现海浪的真实感和实时性仿真,本文以Pierson-Moskowitz模型为基础,采用波的波长和波速建立了海浪波高的初始状态值.通过FBM(Fractal Brown Motion)的菱形网格方式计算海浪曲面片上每个网格点的波高,把每个点画出;再以菱形网格模拟海浪形状,将海浪点的波高描述为随时间和空间变化的多个正弦波叠加近似地表现海浪的运动效果;利用光照模型给海浪添加明暗凹凸效果,增加海浪的真实感;将真实世界中某一海浪的图像作为纹理源,贴到每个网格上,提高仿真的逼真度和运行速度,达到实时仿真的效果.利用Java和JOGL编程模拟,逼真地生成了海浪在不同风向、不同等级情况下的场景.实验表明文中所述方法得当,技术可行.展开更多
基金Project(0802025B) supported by Jiangsu Provincial Postdoctoral Science Foundation, ChinaProject(BK2008382) supported by Natural Science Foundation of Jiangsu Province, China
文摘Diamond films were prepared at different grid bias and substrate bias in hot filament chemical vapor deposition (HFCVD) system. The Raman and SEM results show that grain size decreases and non-diamond impurities increase for applying grid and substrate bias currents. The defects and impurities in the film increase with the decrease of grain size, which causes the decrease of hardness and elastic modulus of diamond films. The fracture toughness of film increases because of the grain size effects by applying bias. The grid bias and substrate bias make the friction coefficient smaller because of the smaller grain size and lubricating effect of graphite in the film. But the excessively high substrate bias current will lead to the dramatic decrease of mechanical properties of CVD diamond as a lot of non-diamond impurities appear in the film.
基金supported by NCRC(National Core Research Center)program of the Ministry of Education,Science and Technology(2010-0008-277)"Development of next generation multi-functional machining systems for eco/bio components" project of ministry of knowledge economy
文摘Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.
基金funded by the Yunnan Provincial Education Department Scientific Research Fund Project[grant number 2023J0717]the Applied Basic Research Foundation of Yunnan Province[grant number 2019FB067].
文摘Although the uniformity of diamond discrete global grid is essential for calculations and searches,geometric deformations increase with the level of divisions.The Good child Criteria provides a basis for evaluating the quality of the global grid.However,some indicators in the criteria are redundant and contradictory,and the existing indicator system has limitations.Directly using the indicator system may render the evaluation of the diamond grid unreliable.In this study,we summarized the evaluation indicators for grid quality basedon the Good child Criteria,calculated the correlations between these indicators using different diamond grid systems,and constructed reliable evaluation systems based on similarities and differences.The selected grid systems are classified into two groups:non-equal-area and equal-area grids.Their quality evaluation systems are composed of Size-Shape-Topology Factor and Geometry-Topology Factor,respectively.The proposed quality evaluation systems utilize a minimal number of indicators selected from each factor to provide a comprehensive description of the diamondgrid’s characteristics.This approach simplifies the complexity of the evaluations while improving their reliability and credibility.
文摘为了从格网剖分结构上解决分块LOD(Level Of Details)模型中复杂的块内、块间裂缝问题,避免目前裂缝消除方法的缺陷,该文提出一种基于多分辨率半边结构的分块LOD模型无缝表达方法。首先,引入多分辨率组合映射理论,给出基于多分辨率半边的菱形块多尺度表达的基本方法,包括菱形块剖分方法和编码方法;在此基础上,提出块内、块间格网无缝表达机制,设计并实现了基于菱形块的全球地形动态LOD管理机制;最后,应用C语言和DirectX工具,开发了相应的可视化实验系统。实验表明:该方法从格网剖分结构上解决了全球地形分块LOD模型中的块内、块间裂缝问题;与传统方法相比,其不需要限制相邻格网的剖分层差,简化效率更高,且无地形失真。
文摘为了表现海浪的真实感和实时性仿真,本文以Pierson-Moskowitz模型为基础,采用波的波长和波速建立了海浪波高的初始状态值.通过FBM(Fractal Brown Motion)的菱形网格方式计算海浪曲面片上每个网格点的波高,把每个点画出;再以菱形网格模拟海浪形状,将海浪点的波高描述为随时间和空间变化的多个正弦波叠加近似地表现海浪的运动效果;利用光照模型给海浪添加明暗凹凸效果,增加海浪的真实感;将真实世界中某一海浪的图像作为纹理源,贴到每个网格上,提高仿真的逼真度和运行速度,达到实时仿真的效果.利用Java和JOGL编程模拟,逼真地生成了海浪在不同风向、不同等级情况下的场景.实验表明文中所述方法得当,技术可行.
