共查询到18条相似文献,搜索用时 624 毫秒
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区间Wang-Said型广义Ball曲线的降阶 总被引:1,自引:1,他引:0
定义了区间Wang-Said型广义Ball曲线(WSGB曲线),它可作为误差控制和产品检验的有效工具;采用3种方法讨论了其降阶逼近问题,即扰动法、利用Chebyshev多项式导出的最佳一致逼近算法和插值端点的最佳一致逼近方法;给出了各种处理方法的显式误差表示.最后结合数值实例分析了3种方法的优劣. 相似文献
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Wang-Said型广义Ball曲线的降阶 总被引:1,自引:1,他引:1
主要讨论 WSGB 曲线的两种不同的降阶算法,分别为扰动法和最佳一致逼近法,给出了两种方法所得降阶曲线与原曲线的逼近误差与相对逼近误差,并通过实例对两种降阶算法进行了比较. 相似文献
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分析在电场力驱动下微共振器的非线性动力学特性.取前3阶模态,利用非线性Galerkin方法得到单自由度的降阶模型.用多尺度法计算降阶模型的动态响应,并得出了稳态响应的幅频特性曲线,与利用传统Galerkin方法直接取1阶模态所得的结果比较.以数值积分法求解3自由度模型得到的微共振器动力学响应为参考标准,验证了非线性Galerkin方法与传统Galerkin方法相比具有较高的精度. 相似文献
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Wang Ball曲线作为一种广义Ball曲线已经在参数曲线求值、升降阶计算中显示出极其有效的作用 .为了在几何设计中更好地发挥其作用 ,应当用简单的方法求出Bernstein基到Wang Ball基的转换矩阵 .该文借助于一个多项式的展开算法 ,给出了这个转换矩阵 ,即给出了B啨zier曲线到Wang Ball曲线的转换公式 ,并应用它简捷地推导出n次Wang Ball曲线的中点离散公式 . 相似文献
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《Computers & Mathematics with Applications》2005,49(2-3):321-329
In this paper, a new generalized Ball basis, normalized totally positive (NTP) basis given by Delgado and Peña, is investigated. The conversion formulae between the basis and the Bernstein basis are derived. We also prove that these formulae not only are valuable for studying the geometric properties, such as subdivision, of the curves and surfaces constructed by this generalized Ball basis, but also can improve the computational speed of the Bézier curves and surfaces. After the Bézier surface (curve) is converted into the generalized Ball surface (curve), the time complexity for evaluation can be reduced from cubic to quadratic, of the degree of the surface (curve). However, the intrinsic property, such as shape-preserving property, is not changed. So, the generalized Ball surface and curve have a great future in application of geometric design. 相似文献
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构造了带形状参数的2m+1次Ball基及Ball曲线.它具有和Ball基及曲线同样的性质.通过3次带参数的Ball曲线生成圆形和花瓶的实例说明在不变动控制点的情况下,通过调整形状参数λ值可根据需要达到控制曲线形状的目的. 相似文献
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为压缩几何信息的数据量,将区间曲线分解成中心曲线和误差曲线的形式,从而得到能够包含2条相邻有理Bézier曲线的区间近似合并曲线.该算法利用摄动误差最小化,通过求解一个线性方程组得到作为中心曲线的近似合并曲线;再利用中间结果直接得到区间宽度相等的误差曲线,或者通过二次规划得到逼近效果更佳但是等区间宽度不等的误差曲线;如果令端点处的区间宽度为0,还能得到端点插值的区间近似合并曲线;最后通过实例验证了文中算法的有效性. 相似文献
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本文构造的带形状参数的2m+2次Ball基及Ball曲线具有和Ball基及曲线同样的性质,它可以通过调节形状参数A值根据需要控制曲线形状,避免了通过改变控制点的位置来调整曲线的形状,而且参数值越大,曲线越光滑。最后,通过由带参数Ball曲线生成圆形和花瓶的实例说明本文方法是可行的。 相似文献
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A class of linear interval programming problems and its application to portfolio selection 总被引:5,自引:0,他引:5
This paper discusses a class of linear programming problems with interval coefficients in both the objective functions and constraints. The noninferior solutions to such problems are defined based on two order relations between intervals, and can be found by solving a parametric linear programming problem. Considering the uncertain returns of assets in capital markets as intervals, we propose a model for portfolio selection based on the semiabsolute deviation measure of risk, which can be transformed to a linear interval programming model studied in the paper. The method is illustrated by solving a simplified portfolio selection problem. 相似文献
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Existing interval constraint logic programming languages, such as BNR Prolog, work under the framework of interval narrowing and are deficient in solving systems of linear constraints over real numbers, which constitute an important class of problems in engineering and other applications. In this paper, we suggest to separate linear equality constraint solving from inequality and non-linear constraint solving. The implementation of an efficient interval linear constraint solver, which is based on the preconditioned interval Gauss-Seidel method, is proposed. We show how the solver can be adapted to incremental execution and incorporated into a constraint logic programming language already equipped with a non-linear solver based on interval narrowing. The two solvers share common interval variables, interact and cooperate in a round-robin fashion during computation, resulting in an efficient interval constraint arithmetic language CIAL. The CIAL prototypes, based on CLP(R), are constructed and compared favorably against several major interval constraint logic programming languages. 相似文献