共查询到20条相似文献,搜索用时 93 毫秒
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在工业设计和反求工程中,曲线是形状设计和数据拟合的重要对象。曲线的光顺性对最终产品的外观质量有着直接影响。文章利用文献[1]构造出带有参数调配函数的模型,用其生成三次C-Bézier曲线。在能量法的基础上,研究了控制参数α对这种新曲线形态的影响,通过调整α和控制顶点使得曲线的能量最小,得到最优的光顺逼近曲线。通过最小二乘法和非线性泛函的极小值优化计算,对平面数据点进行光顺逼近,达到光顺的目的。该算法既可以对曲线进行全局光顺又可以进行局部光顺。最后给出了由数据拟合的C-Bézier曲线光顺的实例。 相似文献
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Bézier曲线是计算机辅助几何设计中的一类重要曲线,以三次三角Bézier曲线为例,对三角Bézier曲线的性质进行了分析,并由此推出三次三角Bézier曲线比三次Bézier曲线更光滑.然后,由连续函数f在给定区间[a,b]上的分割⊿:a=t0<t1<…<tn-1<tn=b和函数值f(ti),导出了三次三角Bézier曲线插值算法,并对插值的整体误差和节点区间[ti,ti 1]内的误差进行了分析估计;最后给出的应用实例验证了上述结论. 相似文献
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采用割线段击逼近计算机输出的非线性曲线.文中分析了用割线段厦用弦线段逼近间的关系。自变量h和曲线及割(弦)线间距离d之间的关系。它指出在同样精度下弦线段数与割线段数之比是√2,当自变量步长h变成ah(a<1)时,割线与曲线的距离d将变成a^2d.文中给出了不含任何迭代的步长函数h(x)的计算公式。 相似文献
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给出了一组带有3个形状参数的双曲Bézier基函数,并相应定义了H-Bézier曲线.通过参数变化可以很方便地调控曲线的形状,随着参数的增大曲线能够很好地逼近控制多边形.另外,曲线可以精确表示直线段、双曲线及悬链线.最后给出了曲线在C1连续下的拼接及在实物造型中的应用. 相似文献
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针对CE-Bézier曲面造型中复杂曲面难以用单一曲面来表示的问题,通过分析CE-Bézier曲线的唯一性,提出了一种新的CE-Bézier曲面的光滑拼接技术。首先,在分析第1类CE-Bézier曲线基函数及其端点性质的基础上,对第1类CE-Bézier曲线的唯一性进行了研究,得出了对于同一条第1类CE-Bézier曲线可以有很多组不相同的控制顶点和形状参数与之对应的结论;其次,利用该结论进一步给出了两相邻第1类CE-Bézier曲面片间G1光滑拼接的一般几何条件,并通过合理地选取形状参数,进一步简化了该曲面的G1拼接条件;最后,给出了第1类CE-Bézier曲面光滑拼接的几何造型实例。实例结果表明,该方法简单、直观、易实现,有效地增强了CE-Bézier方法表达复杂曲线曲面的能力,可广泛地应用于工程复杂曲面的造型系统中。 相似文献
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关于Szász-Durrmeyer-Bézier算子的点态逼近 总被引:1,自引:0,他引:1
Bézier型算子是一些著名算子的推广,已有研究成果主要是对有界变差函数的逼近,而对于应用光滑模研究其中心逼近定理的结果很少.本文利用一阶Ditzian-Totik模得到了Szász-Durrmeyer-Bézier算子点态逼近的正、逆定理及等价定理这一完美的逼近结果. 相似文献
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关于分形图象逼近中的迭代模糊集系统IFZS 总被引:1,自引:1,他引:0
分形的黑白图象和彩色图象之逼近函数可以看作一个模糊集,因此对迭代模糊集系统IFZS的研究是极有必要的。本文对IFZS的重要成分图象函数u和灰度映射φ作了深入的分析。 相似文献
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考虑到具体的博弈、利益团体投票或决策过程中,Vague集的表示往往受到决策者历史知识、感性判断等因素的限制,本文借助于模糊逻辑非门算子,对经典Vague集中隶属度与非隶属度之间的关系进行了改进,提出了广义Vague集的概念。利用三角模和三角余模,建立了模糊近似空间中广义Vague集的粗糙近似,定义和讨论了模糊近似空间中广义Vague集的粗糙度度量方法。最后给出了算例。 相似文献
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Abstract This paper presents an explicit derivation of the all‐pass Routh approximants to e‐s. It then shows that the stable all‐pass Routh approximants to e‐s are exactly the same as the all‐pass Padé approximants. As a result, the derivation provides an alternative way of proving that the all‐pass Padé approximants to e‐s are always asymptotically stable. 相似文献
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Ioana Veronica Ciuchi Cristina Stefania Olariu Liliana Mitoseriu 《Materials Science and Engineering: B》2013,178(19):1296-1302
Measurements by impedance spectroscopy and Bruggeman effective medium approximation model were employed in order to determine the mineral volume fraction of dry bone. This approach assumes that two or more phases are present into the composite: the matrix (environment) and the other ones are inclusion phases. A fragment of femur diaphysis dense bone from a young pig was investigated in its dehydrated state. Measuring the dielectric properties of bone and its main components (hydroxyapatite and collagen) and using the Bruggeman approach, the mineral volume filling factor was determined. The computed volume fraction of the mineral volume fraction was confirmed by a histogram test analysis based on the SEM microstructures. In spite of its simplicity, the method provides a good approximation for the bone mineral volume fraction. The method which uses impedance spectroscopy and EMA modeling can be further developed by considering the conductive components of the bone tissue as a non-invasive in situ impedance technique for bone composition evaluation and monitoring. 相似文献
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László Biró 《Journal of Modern Optics》2019,66(2):119-129
We present a benchmark study by comparing time-dependent electronic state populations calculated in the rotating wave approximation (RWA) to those obtained in numerical exact simulations without the application of the RWA. A wide range of laser intensities and energies are considered in order to explore the limits of the RWA. Our model system consists of a single electron confined to a finite potential well of atomic size so that there are five bound electronic states. The presented numerical study is carried out in the dipole approximation considering either two or all the five electronic states of the system. 相似文献
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K.W.Yu 《材料科学技术学报》1993,9(2):145-147
We build the perturbation expansion method for nonlinear composite media and extend the EMA fornonlinear effective conductivity. Using the solutions of boundary-value problems of a cylindrical in-clusion, we derive formulae for nonlinear effective conductivity. 相似文献
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This paper presents a method of finite-dimensional Markov process (FDMP) approximation for stochastic dynamical systems with time delay and numerical solutions of probability density functions of the systems. Solutions of probability density functions of time-delayed systems are rare in the literature. The FDMP method preserves the standard state space format of the system, and allows us to apply all the existing methods and theories for analysis and control of stochastic dynamical systems and to compute the probability density functions efficiently. The solutions of the FPK equation for a linear time-delayed stochastic system are presented. The effects of different spectral differentiation schemes for the FDMP method on the probability density functions are compared. 相似文献
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We use an unrestricted self-consistent Hartree-Fock approach to calculate the nature of doping states in the three-band Hubbard model. It turns out that for physically relevant parameter values one hole is localized within a small spin-polarized region where five Cu spins are aligned in the same direction. The spin polarization and binding energy between these spinpolaronic states are investigated as a function of different parameters including a Holstein-type electron-phonon coupling on the Cu sites. At higher doping concentration we observe the occurrence of afmon states where the holes are localized in a ring-shaped area. Inside this ring the antiferromagnetic order parameter has inverse sign with respect to the residual antifer-romagnetically ordered plane. 相似文献
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利用有限维空间的逼近性质,本文研究了由一类Fourier系数确定的乘子函数类Fq(α)(0
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