共查询到20条相似文献,搜索用时 62 毫秒
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基于点位移约束的NURBS曲面变形研究 总被引:1,自引:0,他引:1
NURBS曲面变形涉及控制网格、控制点、权因子或一些物理参数等复杂计算,变形不够直观.应用Cao En曲面模型和合成函数对NURBS曲面提出一种新的变形方法,将变形后的曲面表示成NURBS原始曲面和位移函数的合成曲面.曲面变形与控制网格无关,关键点位置可随意选取,直接通过点的位移约束得到可控制的变形结果.实验证明该方法计算简单,变形操作简便直观,适用于曲面的交互设计. 相似文献
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一类弱非线性振动方程的变分迭代算法 总被引:1,自引:0,他引:1
本文提出了一种求解非线性方程的迭代算法,这种方法是先给方程一个带待定函数的试函数作为初始近似解,然后用拉氏乘子法构造一个迭代公式,而拉氏乘子可用变分的概念最佳确定。应用这种方法不会出现长期项,其结果比传统的摄动方法要好得多。 相似文献
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本文给出了相邻Bézier曲面片G~1拼接时的边界自由度个数,即多少个独立的条件可以唯一确定出两块相邻Bézier曲面片是G~1拼接的。应用该结果可以解决Bézier曲面插值时的次数和形状函数的选择,还可用来分析曲面在公共边界上的局部性质。 相似文献
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Samia Riaz Muhammad Waqas Anwar Irfan Riaz Hyun-Woo Kim Yunyoung Nam Muhammad Attique Khan 《计算机、材料和连续体(英文)》2022,70(1):1-14
The captured outdoor images and videos may appear blurred due to haze, fog, and bad weather conditions. Water droplets or dust particles in the atmosphere cause the light to scatter, resulting in very limited scene discernibility and deterioration in the quality of the image captured. Currently, image dehazing has gained much popularity because of its usability in a wide variety of applications. Various algorithms have been proposed to solve this ill-posed problem. These algorithms provide quite promising results in some cases, but they include undesirable artifacts and noise in haze patches in adverse cases. Some of these techniques take unrealistic processing time for high image resolution. In this paper, to achieve real-time halo-free dehazing, fast and effective single image dehazing we propose a simple but effective image restoration technique using multiple patches. It will improve the shortcomings of DCP and improve its speed and efficiency for high-resolution images. A coarse transmission map is estimated by using the minimum of different size patches. Then a cascaded fast guided filter is used to refine the transmission map. We introduce an efficient scaling technique for transmission map estimation, which gives an advantage of very low-performance degradation for a high-resolution image. For performance evaluation, quantitative, qualitative and computational time comparisons have been performed, which provide quiet faithful results in speed, quality, and reliability of handling bright surfaces. 相似文献
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分析了直线度数据评定处理的常用方法,依据相关的数学模型,通过在EXCEL环境下的编程,对直线度数据进行自动计算处理和输出结果,实现直线度测量数据的自动计算处理。通过实例验证,该方法是一种有效的提高测量效率、减小人工计算误差、降低测量软件成本的方法。 相似文献
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首次提出“过原点切线法”,这是一种利用缓冲系数-最大应力(c-σ_m)曲线进行缓冲包装设计的新方法。该法简便实用,用该法设计出的缓冲垫体积最小,因而最经济。文中对“过原点切线法”理论进行了详细的推导。 相似文献
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The design of a strictly modular and flexible system for structural optimization is discussed. OPTIMA 2.0 uses advanced design oriented concepts and is provided for linear and nonlinear structural behaviour. For shape optimal design it is attempted to utilize the simple and efficient Lagrangian interpolation schemes and to restrict spline interpolation to the movable boundaries. A simple interpolation scheme for sizing variables allows the simultaneous handling of sizing and shaping. Some approximation models for the explicit approximation of implicit constraint functions are discussed and evaluated. The realm of this models is extended by introducing an exponential hybrid scheme. Applications are presented in shape optimal design. Objectives are minimum weight as well as minimum stress. Some special aspects of the minimum stress problem are discussed. 相似文献
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为研究锆金属粉尘云燃烧的基础特性参数,从而为其安全性能提供依据,采用哈特曼管试验系统和最低着火温度测定系统分别对锆金属粉尘云的最小点火能(MIE)和最低着火温度(MIT)开展试验研究。分别研究了锆金属粉尘云质量浓度、点火延迟时间和喷粉压力对MIE的影响,以及粉尘云质量浓度对MIT的影响。结果得出:中位径为33.49 μm的锆金属粉尘云的MIE在1~3 mJ之间;在50~500 g/m3质量浓度范围下,随着质量浓度增大,MIE先减小后增大,在质量浓度为400 g/m3时达到最小;点火延迟时间从10 ms增至180 ms,MIE先减小后增大,在60 ms时达到最小;喷粉压力从0.4 MPa增至1.0 MPa,MIE先减小后增大,在0.6~0.8 MPa间达到最小。该粒度锆金属粉尘云的MIT为210 ℃左右,在一定浓度范围下,MIT随粉尘浓度的增加而减小。 相似文献
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为了能够对爆破后形成的露天边坡稳定性进行合理的分析评价,结合大小鱼山岛露天爆破边坡失稳的情况,采用事故树分析方法,建立了工程爆破现场露天边坡失稳事故树模型。计算出事故树的最小割集96个,最小径集3个以及基本事件的结构重要度系数,并得到基本事件结构重要度排序,找出了导致边坡失稳的主要原因是边坡监测和边坡支护。然后根据基本事件结构重要度的排序,制定合理有序的预防措施。事故树分析方法可以全面阐述露天矿边坡失稳的各种因素和逻辑关系,并通过对结构重要性分析,提出合理预防措施,为爆破露天边坡的安全管理提供参考依据。 相似文献
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根据直线度误差定义,提出了一种新的寻找最小包容平行线的方法——相切旋转减小法,并给出了其理论依据;对于实测误差曲线,提出了精确求解直线度误差的方法和步骤。 相似文献
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Inverse maximum capacity problems 总被引:3,自引:0,他引:3
Let be a finite set, be a family of subsets of and be a capacity vector for all elements of . For each , define the capacity of as the minimum capacity occurring in . The problem which we discuss in this paper is how to change the vector as little as possible so that a given has the maximum capacity. This model contains inverse maximum capacity spanning tree problem, inverse maximum capacity path
problem and etc. as its special cases. We transform the problem into the minimum weight cut set problem and show that this
problem can be solved efficiently if an efficient algorithm for finding minimum weight cut set of is available.
Received: 19 July 1996 / Accepted: 12 November 1997 相似文献