查询词典 numerical algorithm

In order to speed up the convergence speed, the each one step of the Landwber iteration is discomposed into the matrix computation and solution and a quick iteration scheme is given for the matrix computation. The relevant accelerated algorithm is given too. Numerical example proves that the accelerated algorithm can quicken convergence speed, reduce the calculation burden, and overcome the obstacle of application of Landweber method of iterated regularization.

为了加快Landweber迭代收敛速度，将每一步Landweber迭代分解为矩阵计算和求解，对矩阵计算部分设计了一种快速迭代格式，并给出了相应的加速算法，通过数值实验验证了这种算法能够大大加快收敛速度，有效的减少计算量，解决了Landweber迭代正则化方法在实际应用中的障碍。

The reconstruction problem is ill-posed, so two optimal criterions, the least module and the smoothness criterion base on Tikhonov regularization technique, are introduced into reconstruction algorithm. Many regularization parameters choice strategies are investigated, and the TPA(Two—Parameter Algorithm) strategy which is based on the Morozov discrepancy principles, is implemented in two regularization reconstruction algorithms.Numerical experiment results show that the nonnegative and smoothness constraint condition can overcome the difficulty of iteration semiconvergent, preconditioned technique can improve convergence rate and reconstruction accuracy, smoothness regularization criterion can meliorate ill-posed problem of reconstruction and enhance iteration stability, and the TPA is an effective strategy of regularization parameters choice.

数值试验表明：在共轭梯度法中引入非负约束和光滑约束改善了迭代的"半收敛"性，非负约束保证了解的非负性，光滑约束抑制了重建解的振荡现象，约束算法的重建精度与无约束算法相比大幅度提高；在约束共轭梯度重建算法中引入预优技术，可以加快算法的收敛速度，提高迭代的稳定性和重建精度；引入光滑准则的正则化技术可以有效改善图像重建问题的不适定性，加快迭代的收敛速度，提高迭代的稳定性和图像重建质量，计算正则参数的TPA算法在闪光照相图像重建中是有效的。

The algorithm is proved to be convergent theoretically and implemented for numerical calculation.Thirdly, two kind problems of multi-unit system maintenance based on the discrete-state deterioration model are analyzed:To achieve the optimization aim of series system consist of two types of units with different failure mode, an opportunistic policy is presented to combine the corrective and condition-based maintenance. The optimal model based on this policy is built and an iteration algorithm based on sequential decision is proposed according to the characteristic of discrete-state deterioration model.

第三、在部件优化分析的基础上，针对基于离散状态劣化模型的多部件系统视情维修决策中的两类典型问题，提出了相应的机会维修策略和优化分析方法：(1)针对串联系统由分别采用视情维修和事后维修的两类部件组成的情况，提出了一类事后维修与视情维修相结合的机会策略，建立了相应的多部件系统维修优化模型，并根据离散状态劣化模型的特点，提出了一类基于序贯决策的求解方法。

In the Uzawa algorithm, we use the HX preconditioner for the primal variable. The numerical results indicate that the new algorithm has good parallelization scalability and the iteration counts are independent of the mesh size and the jump range as for the floating subdo mains and interior cross-points.

数值实验结果表明，不论是对光滑系数还是对有无浮动子区域及有无内交叉点的跳系数情形，我们所设计的并行算法HX-Uzawa-p的迭代次数都基本不依赖于网格规模及系数跳幅，且具有很好的并行可扩展性。

We also introduce a control function, prove the global convergence, and prove the local superlinear convergence under some conditions. Then we propose another new algorithm by using an existed approximation functions, which has the same characters as the first algorithms does. Finally, the result of the numerical experiments indicates the efficiency of the first algorithm. The paper contains four parts.

本文还引入了新的控制函数，并证明了算法具有全局收敛性和在一定的条件下具有局部超线性收敛性；然后，在第一个算法的基础上，本文利用已有的光滑逼近函数提出了另外一个新的算法，通过适当参数选取，证明了新的算法具有与第一个算法同样良好的收敛性质；最后，通过数值计算说明了算法的高效性。

The multiresolution time-domain algorithm based on the scaling function of the Daubechies wavelet is introduced, and the perfectly matched layer absorbing boundary condition for the algorithm is deduced. In order to overcome the difficulties due to the nonlocalized property of the MRTD basis functions, the pure scattered-field formulation is adopted. The method presented is applied to the scattering analysis of multiple conducting objects, and the numerical results are compared with those by the traditional finite-difference time-domain method. It is shown that the computational resource is reduced drastically without sacrificing much accuracy.

对基于Daubechies小波尺度函数的时域多分辨分析算法进行了详细论述，推导了MRTD算法的完全匹配层吸收边界条件，为克服传统MRTD方法中基函数存在着非局部性的缺点，在源的加入上采用了纯散射场方法；并应用该算法对多目标的电磁散射特性进行了分析，数值结果表明，MRTD算法与传统的时域有限差分法结果相吻合，大大节约了计算资源。

In this paper, some basic CFD problems are studied, including ENO/WENO schemes, CFD systematic analysis, object-oriented programming method and zone divided parallel algorithm. These methods enriched and advanced the CFD algorithms, and then these algorithms were applied in numerical applications of the scarfed reversal nozzle and the open cavity. This promotes the speed of the CFD algorithm combine with the project applications.

本文通过对ENO／WENO格式、CFD计算系统分析、面向对象的程序设计方法以及分区并行计算等一些基本问题的研究，进一步丰富和发展了CFD的分析方法，并将所研究的CFD技术应用于斜切反喷管和空腔流动的计算分析中，推动了CFD技术进步同工程应用的紧密结合。

The reconstruction problem is ill-posed, so two optimal criterions, the least module and the smoothness criterion base on Tikhonov regularization technique, are introduced into reconstruction algorithm. Many regularization parameters choice strategies are investigated, and the TPA(Two—Parameter Algorithm) strategy which is based on the Morozov discrepancy principles, is implemented in two regularization reconstruction algorithms.Numerical experiment results show that the nonnegative and smoothness constraint condition can overcome the difficulty of iteration semiconvergent, preconditioned technique can improve convergence rate and reconstruction accuracy, smoothness regularization criterion can meliorate ill-posed problem of reconstruction and enhance iteration stability, and the TPA is an effective strategy of regularization parameters choice.

数值试验表明：在共轭梯度法中引入非负约束和光滑约束改善了迭代的&半收敛&性，非负约束保证了解的非负性，光滑约束抑制了重建解的振荡现象，约束算法的重建精度与无约束算法相比大幅度提高；在约束共轭梯度重建算法中引入预优技术，可以加快算法的收敛速度，提高迭代的稳定性和重建精度；引入光滑准则的正则化技术可以有效改善图像重建问题的不适定性，加快迭代的收敛速度，提高迭代的稳定性和图像重建质量，计算正则参数的TPA算法在闪光照相图像重建中是有效的。

Meanwhile,based on the analysis result,in this paper it gives a solution of global-mesh parallelization algorithm,and has proved by numerical testing that this algorithm really meliorates the DSMC method in computation efficiency a lot.

同时根据分析结果提出了全局网格并行化解决方案，通过数值验证了该并行策略对于DSMC方法在计算效率上确实有显著的提升。

Thus, we can apply the very algorithm to make their numerical analysis much quickly and precisely. We will take the following two devices, the multiple branch rectangular waveguide directional coupler and the H-plane T-junction duplexer, as examples, systematically analyze and discuss the "Network segment and de-segment algorithm" presented and GA application in the computer aided design of complex microwave structures.

本论文将以矩形波导分支电桥耦合器和H面T型接头双工器的优化设计为例，比较系统地分析讨论将&多模网络分解—重组算法&和遗传算法应用于微波电路器件CAD的理论、算法和计算技术问题，并给出主要的器件性能特性曲线，以全面报告我们研究工作的心得体会和研究成果。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。