查询词典 numerical analysis

Chapter 8: We discuss the acceleration of multigrid by Krylov subspace approaches, and recognize the reason for slow convergence of algebraic multigrid methods is that error reduction is significantly less efficient for some very specific error components which may cause a few eigenvalues of the algebraic multigrid iteration matrix to be considerably closer to 1 than all the rest. However, the eigenvectors belonging to the few isolated eigenvalues can be expected to be typically captured after only a few conjugate gradient iterations, which accelerate algebraic multigrid algorithms. Theoretical analysis and numerical results of some practical problems show the iterant recombination accelerates algebraic multigrid convergence.

第八章：先介绍用Krylov子空间迭代法加速一般多重网格方法收敛的基本框架，然后紧紧抓住引起代数多重网格方法收敛减慢的根本原因往往是误差减小对几个特别的误差分量不明显，这导致代数多重网格方法的迭代矩阵的几个特征值接近于1，而共轭梯度方法则能比较典型地捕捉属于孤立特征值的特征向量，从而推导出有效的共轭梯度加速算法和程序实现，不仅从一些具体的实际应用例子的数值结果去验证迭代复合加速收敛的效果，而且还从理论上分析了预处理共轭梯度法加速代数多重网格法收敛的机理。

Based on the analysis of kinetical process of CH4 -air oxidation, a numerical modeling of the species concentrations and temperature for CH4 jet diffusion combustion is made using a four-step reduced mechanism and two semi-detailed chemical kinetical reaction mechanismsW mechanism and Y mechansim.

在分析甲烷-空气氧化反应动力学过程的基础上，采用四步简化机理和两种半详细的化学反应动力学机理-W机理和Y机理，对甲烷射流扩散燃烧的组分浓度和温度进行了数值模拟，计算结果与实验结果进行了对比分析。

In order to make Maca be introduced to China, the basicproblems related to introduction and planting such as morphology classification, regionlayout, tissue culture and allelopathy were carried out. And the results were as follows:(1) The numerical Taxonomy of Maca and fifteen plants of Lepidium in China wasinvestigated by cluster analysis and the results showed that the method of numericaltaxonomy could be applied for Lepidium and its results were basically consistent with thatof morphology taxonomy and molecular marker such as Pi intron, ITS and cpDNA.

本文围绕玛咖在中国引种栽培的基础性和关键性问题，进行了形态学分类、区域规划、组织快繁以及克生现象等的研究，取得以下成果：(1)采用聚类分析，对 15 种中国独行菜属植物以及玛咖进行数量学分类，结论与经典形态学分类以及用 Pi 内含子序列、ITS 序列和 cpDNA 序列进行分类的结果基本吻合，玛咖与家独行菜、碱独行菜的亲缘关系最近，相似系数分别为 0.839、0.722。

The high frequency combustion instability in liquid rocket engine LRE is analyti cally studied by usin g CFD methods.The comprehensive model and governing equations for numerical simu lation of high frequency combustion instability are presented.The PISO and MacCo rmack algorithms are compared in this study.Both methods can successfully handle combustion instability analysis.

应用CFD方法对液体火箭发动机中的高频燃烧不稳定性进行了分析研究，建立了液体火箭发动机不稳定燃烧数值模拟的综合模型和控制方程，比较了PISO和Ma cCormack两种算法，得出了两种算法均能成功应用于不稳定燃烧分析的结论。

Diversity and phylogeny of rhizobia isolated from root nodules of Sesbania cannabina in Jinshajiang arid river valley;2. To study the diversity and phylogeny of rhizobia from Sesbania cannabina in JinShaJiang arid river vally in Sichuan,48 rhizobia was isolated,nodulated,and studied by numerical taxonomy,BOXAIR-PCR,16S rDNA PCR-RFLP,sequences analysis of 16S rDNA and GSⅡ.

从金沙江干热河谷区田菁根瘤中分离得到48株根瘤菌，在对其进行回接实验后，采用数值分类、BOXAIR-PCR、16S rDNAPCR-RFLP、16S rDNA和GSⅡ序列分析方法对这些菌株进行研究，以揭示在金沙江干热河谷区这一特殊地理环境下田菁根瘤菌的多样性和系统发育地位。

Fourth, it conducts the formula deduction, analysis and numerical calculations of the noncollinear quasi-phase matching gains and the output parametric spectrum, which leads to the conclusions that under the same circumstances, the gains of noncollinear interaction will be much less than those of the collinear interaction, and consequently the noncollinear interaction possesses the larger acceptance bandwidths than that of the collinear interaction.

对非共线准相位匹配的增益和输出参量光的允许波长进行了公式推导、分析和计算，得到了允许信号光波长的精确公式和关系曲线。

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。

By utilizing the theory of numerical processing, digital frequency spectrum analysis and multi-rate digital signal processing, this paper focuses the research on mechanism of the testing error, the compensation of testing error in the field of sampling technology, nonsynchronous sampling, nonuniformly sampling, and puts forward some new analyzing, compensation and realization methods.

本论文通过运用数值处理、数字频谱分析和多抽样率信号处理的有关理论和原理，对采样技术、采样的非同步方式和采样的多通道方式中的测试原理、测试误差产生机理、测试误差补偿及其应用技术等主要环节进行了深入的研究，提出了一些新的分析与处理方法，建立了有关测试误差分析与补偿的预估理论和实现方法。

The bifurcation and chaos behavior of impact and rubbing fault rotor system caused by the parameters of nonlinear rigidity, rotor rotating speed, eccentric mass is analyzed, in the numerical value analysis method. The bifurcation diagrams, maximum Lyapunov exponent diagrams, Poincaré maps, phase plane portraits, trajectories of journal center, time-history curve, amplitude spectra diagrams of the rotor motion are used. The convert and evolution course of periodical response, quasi-periodical response, double-periodical bifurcation, chaos of the system response is analyzed.(3). It is deduced that the general differential equation of bending-torsional-pendular coupling vibration about rotor with the gyroscopic moment. On the basis of this equation, the general differential equations of coupled bending, torsional and pendular nonlinear vibration about rotor with unbalance character and rubbing character are deduced.

2建立了具有非线性刚度的转子系统在非稳态非线性油膜力作用下的径向碰摩动力学微分方程，并应用含高阶余项的非线性动力方程的线性化数值法研究了此类系统响应的复杂动力学行为，利用转子响应的分岔图、最大Lyapunov指数曲线、Poincaré截面映射、时域波形、相轨线、轴心轨迹、幅值谱等图形分析了系统响应的周期运动、拟周期运动、倍周期分岔、混沌等运动形式的转化与演变过程，重点研究了非线性刚度、转子转速、偏心质量等系统参数对碰摩故障转子系统的分岔和混沌行为的影响。

This method can make sure the structure radiant sound status in total noise and the detail phonate part quickly and correctly.(3) Study on the control mechanism of structure noise radiated from rotary machines, we build a common model of rotary machine structure noise analysis relied on the general characters of rotary machines. Based on this model, we analyzed various influence factors to structure radiant noise using the union of revolution and numerical calculation method. We found that the joint stiffness between the rotor and the frame is the most sensitive parameter of structure radiant noise by calculating and analyzing.

根据本文对于旋转机械结构噪声控制技术的研究结果和惯性振动筛工作的特殊要求，对有关参数的选择进行了讨论，并通过试验为降低惯性振动筛噪声找到了两个新的方法：即，在轴间相对运动要求不高的情况下，可以在激振器与筛体之间安装一组减振器，通过适当选取减振器参数，既可以使机体在工作频率附近获得稳定振幅，保证振动筛正常工作，又可以使机体的高频响应减小，降噪效果显著；反之，如果轴间相对运动精度要求(来源：1aABC论文网www.abclunwen.com)较高，可以采用空心滚动体轴承，在保证滚动体强度的条件下也可以获得较好的降噪效果。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。