级数的

Along with the rapid development of Internet technology and exponential progressional increase of network resource, the tempo of search engine decides the using rate of Internet resource to a large extent, and the problems in existing search engines make the academia ceaselessly do some research in every kind of search theory and technique.

随着互联网的高速发展和网络资源的指数级数增长，搜索引擎的发展水平在一定程度上决定着互联网资源的利用率，但现有搜索引擎存在的问题，促使学术界不断进行各种搜索理论和技术的研究。P2P全文搜索引擎作为一种全新的搜索方式，日益受到学术界的关注，各种改进的搜索算法被相继提出，并应用于实践。

In this dissertation, many works have been done on the basis of the summarization of the merits of all kinds of meshless methods after a large number of relevant references are read and studied. The basic ideas, principles of meshless methods and their development in the recent years are introduced synoptically. Applications of Element-free Galerkin method in elastic foundation plate are studied deeply and some useful conclusions are obtained as follows:(1) Comparisons between numerical solutions and analytical solutions for several different styles of weight functions, including Gaussian weight function, spline weight function and singular weight function etc, are performed. The results show that Gaussian weight function is the best one.(2) Ranges of relevant parameters for Gaussian weight function are given.(3) Influences of nodal distribution schemes and the number of Gaussian integrated dots on computational results are discussed.

在本文中，作者在认真阅读和研究所搜集到的大量参考文献、综合各种无网格法优点的基础上，首先，对无网格法的基本思想、基本原理、发展现状作了概括性的介绍；其次，对无单元Galerkin法在弹性地基板计算中的应用进行了较为深入的探讨：(1)分别对高斯型、样条型、奇异型等不同形式的权函数进行比较分析，数值计算结果与级数解析解的比较表明，高斯型权函数效果较好：(2)对高斯型权函数进行参数研究，得到地基板计算中相关参数的选取范围；(3)对不同节点分布方案和不同高斯积分对计算结果的影响等作了有益的讨论。

We proposed a set of tabulate shim coils to improve the imaging field homogeneity for permanent magnet. By studying the magnetic spherical harmonics and its Taylor expansion, the proposal of designing lower-order radial coils was derived including x, y, xz, xz~2, x~2-y~2 etc. In addition, a novel composite design was presented for the axial coils. By controlling the shim currents of axial coils, different axial magnetic fields can be obtained. This method simplified the design process of axial coils, and made the axial correcting magnetic field more precise.

本文针对永磁体的组成结构提出了一种平板式匀场线圈设计方法，通过研究成像磁场的球谐函数以及通电圆弧在自由空间产生磁场的泰勒展开级数，导出了x、y、xz、xz~2、x~2-y~2等低阶径向线圈的设计方法，同时针对轴向线圈提出了一种新的混合式设计方案，能够通过控制线圈中的电流组合实现对不同轴向磁场分量的获取，简化了轴向线圈的设计过程，提高了校正磁场的准确性。

Secondly, method of Taylor series is used to approximate the slow manifold and the O approximation of the slow manifold is given; slow dynamics such as saddle node bifurcation which has been proven to be the same as that for the full system is analyzed; at the same time, fast dynamics including bifurcation conditions and domain of attractor of the stable equilibrium are also analyzed; the attracting region which consists of the stable manifold of the unstable equilibrium and stable equilibrium is given; we found that when the inner flux decay increases, the domain of attractor is enlarged.

首先，给出了电力系统SMIB模型的时间尺度分解，得到标准的奇异摄动模型；其次，利用幂级数方法，给出了慢流形的O近似M〓，分析了在慢流形M〓上的慢动态，得到了慢子系统的鞍结分支值，并证明此分支值与原系统的鞍结分支值相同；分析了快子系统的平衡点和全局分支的存在条件，给出由不稳定平衡点的稳定流形与稳定平衡点形成的吸引域；并研究内部电压对稳定域的影响，发现稳定域随内部电压增加而扩大；最后给出整个系统的稳定平衡点的近似吸引域。

A grating function and a groove function are introduced to determine the structure of a concave grating. Basic ideas for the design of a flat-field concave grating with three stigmatic points are proposed. As a proof of the usefulness of these design approaches, image conditions of the grating with three stigmatic points are developed which concise with other published results and they are more general than those obtained from holographic gratings.

采用与分析三维光栅相类似的级数展开法给出了二维集成凹面光栅的球差、彗差的计算方法，计算中用光栅函数和槽面函数来描述具有任意形状和任意变化周期的光栅，提出了一种具有三个无像差点的平面场型凹面光栅的设计方法，利用该方法推导了三点无像差光栅的成像条件，与文献中用其它方法获得的结果相一致，该结果与全息光栅的成像条件相比，更具一般性。

So, in this paper, a circular cavity witha large radius is used to replace the straight boundary of thehalf space, then the half space problem can be changed tothe scattering problem of two circular cavities to the steadyincident P-wave . Having the aid of the mature cylinderfunction theory, the general solutions of the wave functionscan be given, and an infinite linear algebraic equations ofthe unknown coefficients in the wave functions can be gottenwith the boundary conditions and the Fourier complex seriesexpansion technology, the infinite linear algebraic equationscan be approximately solved by the finite trunction withsatisfying some definite precision, at the basis of thissolution of the equation, the variations and the lay-outs ofthe DSCF at the circular cavity boundary vs. the differentincident angles, the different embedded depths of thecircular cavity as well as the different dimensionless wavenumber of the incident P-wave.

为此，本文采用一个半径很大的圆孔来代替半空间的直边界，将该半空间问题转化为一无限大空间中两个圆孔对稳态P波的共同散射问题，借助于成熟的柱函数理论，通过写出问题波函数的一般形式解，利用问题的边界条件，并采用复数傅立叶级数展开技术将其化为一个仅包含问题波函数中未知系数的一无穷线性代数方程组，在满足一定计算精度的前提下，通过有限项截断进行近似求解，进而讨论了圆孔边界处的动应力集中系数随不同入射角、不同的圆孔掩埋深度、入射波的不同无量纲波数以及介质的泊松比变化和分布情况。

In this paper, the sorting of wear, the mechanics of wear particle formed and the characteristics of wear particles are introduced, and morphology characteristics parameter of wear particle are determined, which is particle brim digital feature. Based on image characters, after pre-process, section and extracting of contour parameter of wear particle using image process technique, four shape character parameters are extracted by fourier series expansion. After analyzing fundamental principle and shortcomings of neural network, current BP algorithm is improved in output optimization, network linearization implication optimization and adding momentum, and then astringe speed of BP algorithm.

本文介绍了磨损的分类以及磨粒的生成机理、磨粒的形态特征，应用摩擦学系统分析的观点，确定磨粒边缘数字特征为磨粒的识别特征参数；根据磨粒图像的特征，利用计算机图像处理技术对磨粒图像进行预处理、分割、轮廓参数的提取，采用傅立叶级数展开式提取磨粒四个形状特征参数：圆形度、散射度、凹度、细长度；针对 BP(Back-Propagation)神经网络收敛速度慢的特点，对现行的 BP 算法进行改进，并通过实验验证改进后的网络收敛速度快；研究设计了磨粒图像采集系统；利用 BP 算法建立磨损磨粒自动识别算法模型 AWPRM(Auto Wear Particle Recognition Model)。

Finally, the wave equation of the electromagnetic field of this kind damper isderived from the Maxwells equation. The magnetic flux density at the boundary isassumed to be harmonic, so the analytical result of the wave equation is solved. When therotor rotates, eddy currents flowing inside the conducting material field are caused. Thetangential force acting on the rotor because of the action between eddy currents andmagnetic field is produced. The tangential force causes a retardation torque, which leadsto the increase of power and heating effects.

最后，应用Ahrens的电磁轴承简化模型，从Maxwell方程出发推导了应用于本文所述的被动式电磁阻尼器的波动方程，并用傅立叶级数把矩形磁场展开的谐变磁场作为磁场的边界条件，通过求解波动方程得到磁场的解析解，从而计算了阻尼器对转子的电磁力和由涡流引起的切向力产生的阻尼器附加功耗。

Two GFRF system model identify algorithms based respectively on Signal Flow Graph/Driving Point Impedance and EDA simulation are proposed. In order to solve the problem of fault diagnosis that the inner structure and parameters of the Object under Test cannot be able to determine, a new fault diagnosis method based on the phase space reconstruction and GFRF general formula is investigated. This method builds up a bridge between the chaos theory and Volterra series analysis, which does not strongly depend on the topological structure and the testing data length, is sensitive to the fault property, traces monotonously the change of system fault, and possesses some significant predominance compared with conventional fault diagnosis methods of analog circuits.

提出了基于信号流图/驱动点阻抗法的GFRF算法和基于EDA仿真和非线性频谱响应特性分析的系统模型辨识算法，为解决工程实践中不能确知被测对象内部结构和参数时的故障诊断问题，研究了基于相空间重构和GFRF简化算法的复杂电子系统故障诊断方法，该方法建立了混沌理论与Volterra级数分析法之间的桥梁，它对被测对象的拓扑结构依赖性不强，对被测系统的故障性质的敏感，可以单调地跟踪系统故障的变化，这种基于混沌特性分析的故障诊断方法与其它的模拟电路的故障诊断方法相比较具有显著的优势。

As same as the above-mentioned reason, because theconditions at the inside straight boundary of the binarycomposite material can not be easily satisfied, here, anelastic circular inclusion with large radius is used to replacethe upper half space of the binary composite material, so the〓mary binary composite mater ial problem can be changed〓the scattering problem of a circular elastic inclusion andto the scattering problem of a circular eastic inclusion and〓circular cavity in an infinite space to the steady incident〓wave.

与前面两个问题的理由一样，同样，由于问题中双质复合材料的内部直边界上的边界条件不易解析满足，为此，本文采用了一个半径很大的弹性实夹杂来代替问题中双质复合材料的上半空间部分，而将原来的双质复合材料问题转化成了无限大空间中一圆形弹性夹杂和一圆孔对稳态P波的共同散射问题，根据该问题的特点写出了弹性夹杂内外波场中波函数的一般形式解，利用该问题中夹杂和圆孔处的位移和应力的连续条件，并采用复数傅立叶级数展开技术将其化为一个仅包含问题波函数中未知系数的无穷线性代数方程组，在满足一定计算精度的前提下，通过有限项截断进行近似求解，进而讨论了双质复合材料中圆孔边界处的动应力集中系数随不同入射角、圆孔的不同位置、以及入射波的不同无量纲波数的变化和分布情况。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。