Intersections of two offset parametric surfaces based on topology analysis

INTRODUCTIONTheOSSI(OffsetSurface/SurfaceIntersection)problemisasub-problemofgeneralSSI.AlthoughtheOSSIproblemcanberesolvedbyapplyinggeneralSSIalgorithm,itiscomputationallyexpensiveandexhaustive.Inrecentdecades,effortshavebeenfocusedoncomputingSSIexactly,efficiently,androbustlyinageneralsetting(Abdel-MalekandYeh,1997;Changetal.,1994;BurkeandSabharwal,1996;Mullenheim,1991).Thesetechniquescanbeclassifiedmainlyintofivecategories:algebraic,latticeevaluation,marching(tracing)method,…     

Surface reconstruction by offset surface filtering

The problem of computing a piecewise linear approximation to a surface from its sample has been a focus of research in geometry modeling and graphics due to its widespread applications in computer aided design. In this paper, we give a new algorithm, to be called offset surface filtering (OSF) algorithm, which computes a piecewise-linear approximation of a smooth surface from a finite set of cloud points. The algorithm has two main stages. First, the surface normal on every point is estimated by the least squares best fitting plane method. Second, we construct a restricted Delaunay triangulation, which is a tubular neighborhood of the surface defined by two offset surfaces. The algorithm is simple and robust. We describe an implementation of it and show example outputs.     

Surface reconstruction by offset surface filtering

The problem of computing a piecewise linear approximation to a surface from its sample has been a focus of research in geometry modeling and graphics due to its widespread applications in computer aided design. In this paper, we give a new algorithm, to be called offset surface filtering （OSF） algorithm, which computes a piecewise-linear approximation of a smooth surface from a finite set of cloud points. The algorithm has two main stages. First, the surface normal on every point is estimated by the least squares best fitting plane method. Second, we construct a restricted Delaunay triangulation, which is a tubular neighborhood of the surface defined by two offset surfaces. The algorithm is simple and robust. We describe an implementation of it and show example outputs.     

CJK6032A数控车床的对刀及刀偏值的输入

数控机床的对刀是操作数控机床的基本内容,也是最难以掌握的。本文以华中Ⅰ型CJK6032A教学型数控车床为例,介绍了数控车床的对刀原理和方法。该原理同样适用于数控铣床及加工中心。     

利用Coons曲面构造曲面上的G1插值曲线

利用双三次Coons曲面, 给出了一种对隐式或参数曲面上任意点序列及切方向给定时的G1连续插值方法.首先构造G1连续的组合Coons曲面, 其次求该组合曲面片与已知曲面的交线. 插值曲线是组合Coons曲面片与给定曲面的交线. 由于引入了若干控制参数, 可对曲线进行交互修改使得其最终的形状更好地满足我们的要求. 实验证明该方法简单可行, 适用于计算机辅助设计、计算机图形学等领域.     

Sensitivity analysis for generalized parametric implicit quasi-variational inequalities

1IntroductionandpreliminariesaRecently,Noor[1],Agarwal,ChoandHuang[2]studiedthesensitivityofthesolutionsforsomevariationalinequalitiesonaparameterinHibertspaces.Inthispaper,theauthorstudiesaclassofgeneralizedparametricimplicitquasivariationalinequalities,provesanewexistencetheoremofthesolutionsandanalyzesthesensitivityofsolutions.LetHbearealHilbertspacewithanorm||?||andaninnerproduct??,??.LetKbeanonemptyclosedconvexsubsetofH,PKtheprojectionofHontoKandManopensubsetofHinwhichtheparameterλ…     

基于共轭展成法的直齿锥齿轮三维参数化建模

基于共轭展成法啮合原理和微分几何的理论,推导出了平面产形轮和被加工锥齿轮的齿廓方程,利用Pro-E中参数化建模的方法,在直角坐标系Cartesian中编制齿廓曲线方程,最终生成了整体模型.通过建模的过程证明了建立数学模型的正确性,也进一步拓宽了在应用软件方面建立精确锥齿轮三维模型的途径.     

Analysis on spectral gain characteristics of PPMgLN based quasi-phase-matching optical parametric amplification

A deep understanding of the spectral gain characteristics of optical parametric oscillators （OPOs） and optical parametric amplifiers （OPAs） is important for a highly efficient optical parametric conversion. We numerically calculated the spectral gain characteristics of a quasi-phase-matching （QPM） parametric conversion process using the periodically poled 6% （mol/mol） MgO doped LiNbO3 （PPMgLN） as the nonlinear crystal. In the simulation we utilized the approach of a transformative matrix of the periodically poled nonlinear medium, which results from the small-signal approximation of three-wave mixed nonlinear equations. Numerical simulation results show that： （1） The full width at half maximum （FWHM） of the spectral gain of the parametric process becomes wider with the increase of parametric wavelength and reaches the maximum at degeneration; （2） The gain coefficient decreases gradually with the increase of parametric wavelength; （3） The spectral gain bandwidth decreases correspondingly with the increase of the nonlinear material length; （4） There exists an optimal parametric wavelength band, which is most suitable for the high gain parametric conversion when pumped by a laser source with a wide wavelength band, such as the high power fiber laser.     

广义非线性含参混合拟变分包含组的灵敏性分析

在Hilbert空间中,借助预解算子技巧,讨论了一类新的广义非线性含参混合拟变分包含组,证明了解的存在性,并对解做了灵敏性分析,所得结果推广和统一了文献中的一些结果。     

Research on ultrasonic detection of complex surfaces

INTRODUCTION Parts of complex surfaces have found wide ap-plications today in airplane,ship,automobile industry,medical science,etc.How to detect the internal de-fects of parts of complex surfaces efficiently and ac-curately is an important issue.Due to its special ad-vantages of high sensitivity,good detection,strong penetration ability,and harmlessness to human body,ultrasonic detection has become a most important method of Nondestructive Test(NDT).However,at present in China,to detec…     

基于改进的DTW算法的仿真与分析

传统的DTW算法着重于时间规整和间距测量的概念，对数据的可靠性没有进行有效的分析，且对连续词的识别效果不明显。基于松弛起始点和分段思想的改进DTW算法，可以改善明阿算法的缺陷。通过对语音样本0．9在MATLAB6．5上的仿真实现与分析表明，采用改进后的DTW算法具有良好的语音识别效果。     

基于一种新的曲率分析算法对散乱数据点云分块

给出了数据分块系统性方案, 即从仅含有三维坐标的散乱的点云中自动提取几何曲面特性. 首先基于局部基面参数化估算散乱数据点云的局部表面曲率分析是其方案的关键性技术. 再采用由高斯曲率和平均曲率的记号得到的8种曲面类型, 就形成初始数据分块. 通过区域增长法可以使粗略数据分块进一步被提取, 得到更小的噪声影响及更精确的区域划分. 其方案得到了实例验证, 具有较强的可操作性和实用性. 基于新曲率算法的分块方案使数据分块技术能够直接运用于散乱数据点云.     

基于交通仿真的拓宽交叉口服务通行能力研究

采用延误分析法研究路口拓宽后信号交叉口的服务通行能力，利用交通仿真软件VISSIM对拓宽交叉口进行交通流微观仿真，从而得到拓宽车道的延误曲线，建立了基于交通仿真的拓宽交叉口延误-流量模型．依据该模型提出了拓宽左转车道的基本服务通行能力的建议值，并给出了各修正系数以及实用服务通行能力的确定方法．     

基于AutoLisp齿轮参数化绘图命令的二次开发

对机械设计中常用的齿轮参数化绘图系统的Lisp二次开发进行了分析,给出了整体功能设计的开发步骤,涵盖了齿轮绘图命令用户界面的自定义方法,基于AutoLisp圆柱齿轮、圆锥齿轮和蜗轮蜗杆参数化绘图命令的设计思路和基本尺寸参数输入方式几个方面;给出了基于DCL语言的单个齿轮零件图和齿轮啮合图的对话框参数输入界面的设计和基于AutoLisp参数化绘图命令二次开发的程序设计方法及关键程序段,并给出具体的应用实例。     

基于CATIA的扭角测量仪的参数化设计与仿真

介绍了应用于WB-100B型扭转试验机的扭角测量仪设计,重点讨论了扭角测量仪的夹紧原理,利用CATIA设计软件对扭角测量仪进行参数化设计并进行了运动仿真优化设计。     

基于拓扑和尺寸优化的汽车C型梁结构轻量化设计

以商用车空气悬架C型梁为研究对象,采用材料替换并结合拓扑和尺寸优化的方法进行轻量化设计。基于变密度法,以结构刚度最大化为目标进行拓扑优化,获得结构初始构型。在拓扑优化结果的基础上,综合考虑3种工况,以板件厚度为设计变量,各工况下的应力和变形为约束条件,质量最小化为目标,进一步进行尺寸优化。优化结果表明,设计方案满足结构刚强度要求,降低了结构的质量,达到了轻量化的效果。     

重庆旅游产业新增长点打造:基于乡村旅游的分析

在旅游业蓬勃发展和社会主义新农村建设的背景下,乡村旅游面临着大好的发展机遇。通过问卷调查的方式分析了重庆乡村旅游的市场潜力和存在的问题。对将乡村旅游打造为重庆旅游产业新的增长点进行了理论分析并提出了对策建议。     

钢管混凝土组拼管拱面外屈曲参数分析

以福鼎山前大桥空间有限元模型为基础,分析了影响钢管混凝土组拼管拱面外屈曲的主要参数,包括横撑布置形式、横撑刚度、拱脚约束情况、截面含钢率和混凝土弹性模量.有限元分析结果表明,横撑布置形式、横撑刚度和截面含钢率对钢管混凝土组拼管拱面外屈曲影响很大,但混凝土强度等级和拱脚约束对其影响很小.     

副词研究平议

副词相对于动词，形容词具有语法和语义上的从属性，按照副词的形式定义，并主要结合现代汉语的实际情况，语用中副词以外其他词类成员进入副词位置和某些词词单位离开副词位置前移的现象，分别可以从词类交叉理论和词类过渡理论获得解释。     

Surface morphologies of aluminum films on silicone oil surfaces

The surface morphology and growth mechanism of an aluminum film system deposited on silicone oil surfaces by a vapor depositing method was investigated by scanning electron microscopy. It was found that the perpendicular fluctuation of the film's bottom surface was more remarkable than that of the film's top surface. Near the joint between the film on the silicone oil substrate and the film on the silicon wafer surface on which the silicone oil substrate rested, was a naturally formed anomalous wedge-shaped wrinkly structure with slopes of 10⁻⁴–10⁻⁵ rad, whose growth mechanism could be interpreted under the assumption of the thermal expansion behavior of the liquid substrates. Project supported by NSFC (No. 19874016) and the Special Fund of Zhejiang Provincial Natural Science Foundation for Young Scientists (Grant No. 1997RC9603).