排序方式: 共有64条查询结果,搜索用时 15 毫秒
1.
非线性规划的拟下降方法:概念,模型及应用 总被引:7,自引:0,他引:7
§1.引言 考虑一般非线性规划问题: (P)min{f(x)|x∈S},其中S?R~n为一非空闭集,f:R~n→R~1。 求解(P)的下降算法的基本思想是:在当前点x_k∈S处,(若x_k不是某种期望的 相似文献
2.
可行方向法的统一探讨:二阶段算法模型 总被引:1,自引:0,他引:1
1 引言可行方向法是非线性规划中一类思想简单数值效果好的基本方法。特别是对线性约束问题,这类方法一直受人欢迎。但由于非线性约束带来的困难,这一领域内的工作近年来并不多见。文[1]曾统一和推广了国内外文献中常见的投影梯度和既约梯度法。本文首先提出一个二阶段算法模型用来解不等式约束问题,大范围地统一和推广了现有的可行方向法。然后,对于一般非线性规划问题,本文利用仅含等式约束的Lagrange函数作为搜索函数,直接应用上述模型的结果给出相应的模型,大大推广和简化了[2]中方法。具体选 相似文献
3.
极大熵方法与非单调曲线搜索可行方向法 总被引:5,自引:0,他引:5
1.引言逼近方法是解决复杂的最优问题的有效方法之一.目前,已有许多研究工作【‘一句.己有的工作主要是从理论上讨论逼近问题和原问题的最优解之间的关系.另一方面,寻求具体而有效的逼近方法不仅具有理论意义,而且更具有实用价值.近年来出现的求解非线性规划(minimaxfbi题)的极大滴方法I‘-‘]就是一种具体而有效的逼近方法.[1-3]中的有关结果可以用于这种方法.[7]则从另一途径给出了强凸规划的极大嫡方法的收敛性质.已有的极大滴方法的收敛性结果均是在最优解意义下得到的.由于一般情况下只能求得优化问题的Kuhn-T… 相似文献
4.
5.
Lattice Bhatnagar-Gross-Krook Simulations of Hydromagnetic Double-Diffusive Convection in a Rectangular Enclosure with Opposing Temperature and Concentration Gradients 下载免费PDF全文
The temperature-concentration lattice Bhatnagar-Gross-Krook (TCLBGK) model with a robust boundary scheme is developed for two-dimensional hydromagnetic double-diffusive convective flow of a binary gas mixture in a rectangular enclosure, in which the upper and lower walls are insulated, while the left and right walls are constant temperature and constant concentration, and a uniform magnetic field is applied in the x-direction. In the model the velocity, temperature and concentration fields are solved by three independent LBGK equations, which are combined into a coupled equation for the whole system. In our simulations, we take the Prandtl number Pr = 1.0, the Lewis number Le = 2.0, the thermal Rayleigh number RaT = 10^5, and the aspect ratio A = 2 for the enclosure. The numerical results are found to be in good agreement with those of previous studies. 相似文献
6.
7.
本文提出了二类新的摄动可行方向法,发展和完善了这类方法.新方法形式简单而且不必用Polak程序.适当选择算法中有关参数可减少计算量,还可加快算法的收敛速度. 相似文献
8.
9.
Simulating high Reynolds number flow in two-dimensional lid-driven cavity by multi-relaxation-time lattice Boltzmann method 总被引:3,自引:0,他引:3 下载免费PDF全文
By coupling the non-equilibrium extrapolation scheme for boundary condition with the
multi-relaxation-time lattice Boltzmann method, this paper finds that the stability
of the multi-relaxation-time model can be improved greatly, especially on
simulating high Reynolds number (Re) flow. As a discovery, the super-stability
analysed by Lallemand and Luo is verified and the complex structure of the cavity
flow is also exhibited in our numerical simulation when Re is high enough. To the
best knowledge of the authors, the maximum of Re which has been investigated by
direct numerical simulation is only around 50,000 in the literature; however,
this paper can readily extend the maximum to 1000,000 with the above combination. 相似文献
10.
格子Boltzmann方法中的曲边界处理 总被引:4,自引:2,他引:2
研究了格子Boltzmann方法中实现曲边界条件的3种格式,对它们的精度和稳定性进行了分析和比较.通过二维Poiseuille流和等边三角域上空腔流的模拟,讨论了这3种格式的数值精度和稳定性. 相似文献