共查询到20条相似文献,搜索用时 78 毫秒
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多项式拟合铁磁材料的磁滞回线曲线 总被引:2,自引:0,他引:2
确定铁磁材料的磁滞回线的绘制属于最小二乘法问题,并确定用分段三次多项式来拟合.给出三次多项式拟合,以及在求解过程中解法方程的方法,并给出了具体算法. 相似文献
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求解二维三温辐射扩散方程组的一种代数两层迭代方法 总被引:2,自引:2,他引:0
在二维三温辐射扩散方程离散代数方程组的求解中,由于光子、电子和离子温度之间存在耦合关系,而且三个温度在同种介质中有不同的扩散性质,使得经典的代数多重网格(AMG)方法难以直接应用.基于特殊粗化策略,在粗网格层解除了这种耦合关系,得到一种代数两层网格方法,而粗网格方程由经典AMG方法求解.将这一算法具体应用于JFNK(Jacobian自由的Newton-Krylov)框架中预处理方程的求解,并基于该框架求解二维三温辐射扩散方程组.数值结果显示了算法的可扩展性和健壮性. 相似文献
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针对认知无线电网络中基于图着色模型的频谱分配问题,基于其非确定性多项式特性,以最大化网络收益总和为目标,提出了一种基于拟态物理学优化的求解算法. 在拟态物理学优化算法中,将频谱分配问题的解映射为一个具有质量的微粒,通过建立微粒的质量与其适应值之间的关系,并利用万有引力定律定义微粒间的虚拟作用力的大小,使整个群体向更好的方向运动,实现群体寻优. 给出了频谱分配问题的具体求解过程,并根据分配问题的二进制编码特点,改进了微粒的位置更新方程. 仿真实验表明:本文算法能更好地实现网络收益最大化.
关键词:
拟态物理学优化
认知无线电网络
频谱分配
网络收益 相似文献
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针对二维泊松方程在实际应用过程中几种常用方法存在计算量大、易发散、局部收敛等不足,提出了一种改进算法.该算法基于并行超松弛迭代法,采用遗传算法对松弛因子进行全局寻优,解决了超松弛迭代法求解泊松方程时最佳松弛因子难以确定的问题.构建了多目标适应度函数,优化了遗传算子参数,分析了算法的计算量、计算时间与误差精度,与传统方法进行了对比研究.结果表明:松弛因子对泊松方程求解的速度与精度影响显著;改进算法能减少迭代次数,节省计算时间,加快方程的求解;算法适合于求解计算量较大、精度要求较高的时域有限差分方程,而且精度要求越高,算法的性能越好,节省的时间也越多. 相似文献
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针对薄板弯曲大变形问题, 运用变分原理, 建立了薄板弯曲大变形问题的高阶非线性偏微分方程. 运用有限差分法和动态设计变量优化算法原理, 以离散坐标点的上未知挠度为设计变量, 以离散坐标点的差分方程组构建目标函数, 提出了薄板弯曲大变形挠度求解的动态设计变量优化算法, 编制了相应的优化求解程序. 分析了具有固定边界、均布载荷下的矩形薄板挠度的典型算例. 通过与有限元的结果对比, 表明了本文求解算法的有效性和精确性, 提供了直接求解实际工程问题的基础. 相似文献
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作为对泰勒展开公式的新认识,本文由泰勒展开公式出发,系统地导出了常用特殊函数的倍乘公式与加法公式.得到了大约50个公式,绝大多数在现有的几本主要工具书中都未能检得. 相似文献
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R-C系统外遮光罩挡光环的程序化设计及锥状内遮光罩的改进 总被引:2,自引:1,他引:1
基于几何作图法推导出R-C系统外遮光罩内挡光环顶点的坐标公式,利用C语言编程实现程序化设计挡光环.在中心遮光比确定的情况下,推导出内遮光罩的顶点坐标公式,并将通常使用的主镜一级锥状遮光罩改进为二级锥状遮光罩,以高速摄影系统的R-C型折反式主物镜为例,对其主镜和次镜内遮光罩进行设计,并给出设计结果.当轴角为70°,遮光罩为二级和一级时,到达像面的杂散光照度分别为1.082 3×10-12 W/m2和1.661 4×10-10 W/m2,相差二个数量级,证明改进的二级遮光罩优于一级遮光罩,能有效抑制杂散光.最后,设计了主、次镜间镜筒内壁上等高挡光环,进一步抑制了R-C系统的杂散光. 相似文献
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Correlation functions of the two-dimensional Ising model on the periodic lattice can be expressed in terms of form factors—matrix
elements of the spin operator in the basis of common eigenstates of the transfer matrix and translation operator. Free-fermion
structure of the model implies that any multiparticle form factor is given by the pfaffian of a matrix constructed from the
two-particle ones. Crossed two-particle form factors can be obtained by inverting a block of the matrix of linear transformation
induced on fermions by the spin conjugation. We show that the corresponding matrix is of elliptic Cauchy type and use this
observation to solve the inversion problem explicitly. Non-crossed two-particle form factors are then obtained using theta
functional interpolation formulas. This gives a new simple proof of the factorized formulas for periodic Ising form factors,
conjectured by A. Bugrij and one of the authors. 相似文献
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特殊函数的数值计算综述 总被引:1,自引:0,他引:1
本文首先介绍了在科技工作中常遇到的各类特殊函数,以计算Bessel函数和椭圆积分为例,讨论了在计算大多数特殊函数中所遇到的有关算法的一些共性问题。如采用小宗量级数展开式,大宗量渐近式,多项式近似,递推法,迭代法计算等。最后还讨论了计算某些特殊函数的零点及其它有关数值计算问题。 相似文献
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O. Costa De Beauregard 《International Journal of Theoretical Physics》1973,7(2):129-143
Four generalisations of results appearing in a previous paper, referred to as I, are here produced. (1) Formulas for the field strengths of the evanescent wave generated inside a vacuum sandwiched between two identical refracting media propagating symmetrical incident plane waves; the classical exponential damping factor being then replaced by hyperbolic cosines or sines (according to the field components), an extremely close approximation to a plane tachyon wave is thus obtained; (2) Compact formulas for the case where the evanescent wave is generated by a superposition of plane incident waves with propagation vectors k parallel to a common incidence plane; (3) Compact formulas for the other typical case where the dispersion on k is parallel to the reflecting plane; (4) Formulas for refraction and total reflection of a photon with a non-zero rest mass.We take the opportunity of this paper to review briefly various articles that had escaped us, where a transverse energy flux inside Fresnel's evanescent wave was discussed, and also some recent papers dealing with quantisation of the evanescent wave or related topics. 相似文献
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The Capacity of a Quantum Channel for Simultaneous Transmission of Classical and Quantum Information
An expression is derived characterizing the set of admissible rate pairs for simultaneous transmission of classical and quantum information over a given quantum channel, generalizing both the classical and quantum capacities of the channel. Although our formula involves regularization, i.e. taking a limit over many copies of the channel, it reduces to a single-letter expression in the case of generalized dephasing channels. Analogous formulas are conjectured for the simultaneous public-private capacity of a quantum channel and for the simultaneously 1-way distillable common randomness and entanglement of a bipartite quantum state. 相似文献
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The aim of this work is to fill the gap between three-dimensional embedding formulas for problems of diffraction by cones
and the modified Smyshlyaev formulas. The three-dimensional embedding formulas express the diffraction effect in the form
of iterated integrals over spatial variables. The modified Smyshlyaev formulas express it in the form of a single contour
integral with respect to the parameter ν of separation of variables. This situation resembles the theorem of convolution for
the Fourier transform: repeated convolutions are expressed by a single integral with respect to frequency. In [1], where the
modified Smyshlyaev formulas were introduced for the first time, these formulas were hypothesized and then proved. No regular
method for deriving them has been proposed. The extension of the analogy with the Fourier transform to the case of conical
problems of diffraction enables one to construct a technique for transformation of contour integrals that can be used for
deriving the modified Smyshlyaev formulas directly from the three-dimensional embedding formulas. This extension is performed
by introducing an integral transform similar to the Kontorovich-Lebedev transform, for which analogs of the theorem of convolution
and the Plancherel formulas can be successfully proved. 相似文献
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运用MATLAB软件,采用数值计算的方法,得出单摆运动周期的两个新的近似公式.同时,对原有文献报道的运用解析方法推导出的近似公式进行比较和修正. 相似文献