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《中国高新技术企业评价》2017,(9)
犁体曲面设计是农机具中较复杂的曲面设计,犁性能好坏直接影响着农业生产。文章以翻土型犁体为例,根据水平元线法形成犁体曲面的原理,计算出犁体曲面的各要素参数的数学模型。在CATIA环境中绘制犁体曲面的构架,利用网格曲面命令生成曲面。根据犁体曲面的正视图修剪该曲面得到犁体曲面的外形轮廓。然后生成实体,对其曲面进行数控加工仿真。 相似文献
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本文以曲面多轴高速加工技术为研究对象,在三轴曲面加工基础上考虑多轴曲面和高速切削的特点和现实要求,对曲面高速加工过程进行动态分析,为曲面多轴高速加工技术的优化提供参考,以提高加工工件的表面质量。 相似文献
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在Mastercam X中复杂网格曲面的创建是三维曲面造型中的一大难点,本文从网格曲面的概念、构建步骤及实际操作过程中的相关注意点等方面,探讨了几种典型网格曲面的构建方法. 相似文献
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曲面重构是逆向工程中CAD建模中的重要组成部分,三维曲面的重构方法决定了获得的曲面精度与光滑性,直接决定了逆向工程的效果,文章针对逆向工程中的关键技术三维曲面的重构方法进行了分析与讨论. 相似文献
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《中国高新技术企业评价》2016,(29)
在运用边界元方法计算开域场中的电场时,为提高传统一阶边界元法的精度问题,提出NURBS曲面四边形边界元法。此方法是对计算模型进行二阶四边形剖分,采用剖分信息构造出NURBS曲面参数方程,然后用面积比值法定义曲面上顶点的形状函数,曲面四边形的四个顶点作为求解点,计算NURBS曲面四边形单元上的积分值。 相似文献
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本文以UG8.5软件为设计基础,讲述了在该软件中如何运用软件进行复杂曲面的建模方法,以某发动机叶片为例,对该叶片曲面造型中的某些问题进行分析,并应用UG软件的曲面造型功能,使叶片的设计开发变得精确,进一步增强了复杂曲面叶片的设计效率和精度。 相似文献
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James G. MacKinnon 《Journal of Applied Econometrics》1996,11(6):601-618
This paper employs response surface regressions based on simulation experiments to calculate distribution functions for some well-known unit root and cointegration test statistics. The principal contributions of the paper are a set of data files that contain estimated response surface coefficients and a computer program for utilizing them. This program, which is freely available via the Internet, can easily be used to calculate both asymptotic and finite-sample critical values and P-values for any of the tests. Graphs of some of the tabulated distribution functions are provided. An empirical example deals with interest rates and inflation rates in Canada. 相似文献
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This paper employs response surface regressions based on simulation experiments to calculate asymptotic distribution functions for the Johansen-type likelihood ratio tests for cointegration. These are carried out in the context of the models recently proposed by Pesaran, Shin, and Smith ( 1997 ) that allow for the possibility of exogenous variables integrated of order one. The paper calculates critical values that are very much more accurate than those available previously. The principal contributions of the paper are a set of data files that contain estimated asymptotic quantiles obtained from response surface estimation and a computer program for utilizing them. This program, which is freely available via the Internet, can be used to calculate both asymptotic critical values and P-values. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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介绍土坝软基段的基础处理,采取以砂井排水固结法、表层淤泥清除的处理方案,并分析土坝施工过程中裂缝发生的原因以及处理方法。 相似文献
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为解决混凝土浇筑过程中出现泌水、离析,混凝土实体表面出现麻面、气孔、水纹等质量问题,在混凝土浇筑过程中运用系统控制理论,精心组织,合理布置施工方案。 相似文献
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金属表面等离子体激元所具有的近场增强、表面受限、短波长等特性为亚波长尺度的金属结构中光场局域化提供了可能性。利用它可以实现纳米级别、亚波长尺度内的高质量滤波。本文建立在表面等离子体理论的基础上,设计出一种方形腔结构,编写程序利用matlab和时域有限差分法模拟,并通过改变结构的宽度、高度和耦合长度等参数,分析光波通过该金属结构后的透射性质,结合振幅分布,总结了其在滤波器中的应用。 相似文献
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文章结合上海闵浦大桥国产环氧沥青钢桥面铺装项目,从处在繁华闹市位置的一个工程实例出发,对国产环氧沥青混凝土铺装施工组织及关键技术控制进行了全面探讨,并对国产环氧沥青混凝土的施工应用进行了经验总结。 相似文献
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What sociological attributes characterize the form of an enduring social organization that empowers individually rational self‐interested actors to provide themselves with a common property or collective goods resource? To address this question, two common property/collective goods organizations for water management—located in the Arkansas River Basin of Colorado—were compared. The method was to assess attributes of each organization against those of conceptual benchmarks that reflect a tradition of common property resource and collective goods organizational research. The organizations were the Arkansas River Water Bank Pilot Program and the Lower Arkansas Valley Water Management Association. The Arkansas River Water Bank Pilot Program lacked the characteristics that theorists advancing the conceptual benchmarks have hypothesized as important to success. The pilot program also failed to generate local interest. The program was decommissioned in 2005 after the pilot trial period concluded. The Lower Arkansas Water Management Association possessed the attributes. It was considered a success as defined by member support for the organization and the capacity of that organization to re‐time flows on the Arkansas River. This program has been operating a water market in the lower Arkansas River Basin for over 30 years and continues to successfully move groundwater and surface water around the landscape. Implications for policy and theory are addressed. 相似文献
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在单螺杆式水利机械中,定子与转子是其中的关键性部件。在进行设计时,需要对螺杆转子刀具加工条件进行深入的分析,充分的考虑到工件与刀具的形状、尺寸与刚度,对这些因素进行综合分析,以此为基础来确定好相关的刀具设计方案,本文主要分析内螺旋曲面数控镗削加工原理及工艺方法。 相似文献