Equivalent staggered-grid(ESG) as a new family of schemes has been utilized in seismic modeling,imaging,and inversion.Traditionally,the Taylor series expansion is often applied to calculate finite-difference(FD) coeff...Equivalent staggered-grid(ESG) as a new family of schemes has been utilized in seismic modeling,imaging,and inversion.Traditionally,the Taylor series expansion is often applied to calculate finite-difference(FD) coefficients on spatial derivatives,but the simulation results suffer serious numerical dispersion on a large frequency zone.We develop an optimized equivalent staggered-grid(OESG) FD method that can simultaneously suppress temporal and spatial dispersion for solving the second-order system of the 3 D elastic wave equation.On the one hand,we consider the coupling relations between wave speeds and spatial derivatives in the elastic wave equation and give three sets of FD coefficients with respect to the P-wave,S-wave,and converted-wave(C-wave) terms.On the other hand,a novel plane wave solution for the 3 D elastic wave equation is derived from the matrix decomposition method to construct the time-space dispersion relations.FD coefficients of the OESG method can be acquired by solving the new dispersion equations based on the Newton iteration method.Finally,we construct a new objective function to analyze P-wave,S-wave,and C-wave dispersion concerning frequencies.The dispersion analyses show that the presented method produces less modeling errors than the traditional ESG method.The synthetic examples demonstrate the effectiveness and superiority of the presented method.展开更多
将智能优化算法与数值迭代方法有机组合,构造一种并联机构位置正解求解的通用算法——混合人工蜂群和Newton迭代(Hybrid artificial bee colony and Newton iteration,HABC-Newton)算法。将差分进化(Differential evolution,DE)算法融...将智能优化算法与数值迭代方法有机组合,构造一种并联机构位置正解求解的通用算法——混合人工蜂群和Newton迭代(Hybrid artificial bee colony and Newton iteration,HABC-Newton)算法。将差分进化(Differential evolution,DE)算法融入人工蜂群(Artificial bee colony,ABC)算法,形成一种能快速收敛到问题近优解的混合人工蜂群(Hybrid ABC,HABC)算法,再以该近优解为初值,应用Newton-Шамарский迭代法求出高精度位置正解。以4自由度4-SPS-CU并联机构正运动学分析为例,阐述基于HABC-Newton算法的并联机构正运动学分析方法。为了验证算法的有效性和普适性,给出4-SPS-CU、3-RRR两种耦合并联机构位置正解的数值算例。结果表明,HABC-Newton算法能以较少计算开销求得并联机构的全部高精度位置正解。还比较了HABC-Newton、ABC、DE和粒子群算法求并联机构位置正解的性能,数值实验显示,HABC-Newton算法的精度、稳健性和计算效率高于对比算法。展开更多
在利用泰劳级数展开并忽略高次项将相关非线性问题简化为线性问题的数学处理方法基础上,采用牛顿迭代法的相关原理,提出了1套适合冷连轧机快速负荷设定的带材中间厚度计算模型。其应用到宝钢冷轧薄板厂1 220 mm 5机架冷连轧机上取得了...在利用泰劳级数展开并忽略高次项将相关非线性问题简化为线性问题的数学处理方法基础上,采用牛顿迭代法的相关原理,提出了1套适合冷连轧机快速负荷设定的带材中间厚度计算模型。其应用到宝钢冷轧薄板厂1 220 mm 5机架冷连轧机上取得了良好的使用效果,创造出较大的经济效益。展开更多
文摘Equivalent staggered-grid(ESG) as a new family of schemes has been utilized in seismic modeling,imaging,and inversion.Traditionally,the Taylor series expansion is often applied to calculate finite-difference(FD) coefficients on spatial derivatives,but the simulation results suffer serious numerical dispersion on a large frequency zone.We develop an optimized equivalent staggered-grid(OESG) FD method that can simultaneously suppress temporal and spatial dispersion for solving the second-order system of the 3 D elastic wave equation.On the one hand,we consider the coupling relations between wave speeds and spatial derivatives in the elastic wave equation and give three sets of FD coefficients with respect to the P-wave,S-wave,and converted-wave(C-wave) terms.On the other hand,a novel plane wave solution for the 3 D elastic wave equation is derived from the matrix decomposition method to construct the time-space dispersion relations.FD coefficients of the OESG method can be acquired by solving the new dispersion equations based on the Newton iteration method.Finally,we construct a new objective function to analyze P-wave,S-wave,and C-wave dispersion concerning frequencies.The dispersion analyses show that the presented method produces less modeling errors than the traditional ESG method.The synthetic examples demonstrate the effectiveness and superiority of the presented method.
