查询词典 calculus of finite differences

It is found by solving the self-consistency equa tion that, at zero chemical potential and finite temperature the chiral phase transition is of second order, while both at finite temperature and density and at zero temperature finite density this transition is of first order.

通过求解序参量所满足的自洽方程，其结果表明：在零化学势有限温度情况下，有二级手征相变发生；对于有限温度和密度以及零温有限密度两种情况，手征相变为一级，并且其转变温度或密度与费米子所处的初始相有关，即从破缺相到正常相的转变温度或密度不同于从正常相到破缺相的转变温度或密度。

This paper is based on the former research taking the No.1 Tong-Lv Bridge as an example; the large universal finite element program Midas/Civil is adopted, a three-dimensional finite element model is established. The static performance, the comparative analysis of influence surfaces, the experimental study and the analysis of a local finite element model of the new style three-span continuous through type bow-string arch bridge is made. With these studies, this paper is aimed at revealing the performance of this kind of construction.

本文在前人研究的基础上，以通吕一号桥为背景，采用空间有限元法对结构形式新颖的三跨连续下承式系杆拱桥的静力性能、影响面比较分析、实桥荷载试验、局部节点分析等进行研究，旨在深入理解该结构形式桥梁的力学性能，为今后相同结构体系桥梁的结构分析提供可以参考的建议。

A finite element analysis on the new method is presented in this paper. Based on the finite element analysis, tension tests of 18 steel bars in different diameters and holes are carried out. The results of tests, which are according with that of finite element analysis, validate the new method to determine real stresses of steel bars by drilling/enlarging small holes. Furthermore, some suggestions in using of the new method are given.

本文针对该新方法进行了有限元分析，并在此基础上进行了18种不同钢筋直径和不同孔径的带孔短钢筋拉伸试验，试验结果与相应有限元计算结果一致，验证了钻／扩孔确定钢筋实际应力的新方法，并提出了若干工程适用建议。

In studies of interaction among pile, platform that above it and surrounding soil, this paper employ the concept of plate element to simulate the loading character of platform, and employ the concept of solid element to simulate the character of pile and soil, using the finite element method after understanding the geometry properties of pile, soil and the platform. Analyzing the loading properties of the three entities above and their deformation, this paper also employ a special element, Penalty Element. The introduction of penalty element of this kind has served to guarantee the join harmony of displacement between solid element and plate element, thereby effectively resolving the join problem between platforms, pile that support it and surrounding soil.Considering significant property difference between pile material and its surrounding soil, there may be much shear stress on their contact interface produced under vertical load, thus causing displacement or fission. Therefore it is necessary to adopt one special constitutive law of this kind of contact interface, which can reflect its feature of loading and deformation thoroughly. On the basis of the deformation feature and constitutive laws of some contact interface obtained by Zhang Dongji and people concerned through some single-shear experiments on contact interface between structure and soil, this paper employ one pile-soil three-dimensional constant thickness contact interface model to simulate the " slide" taken place on the interface between pile and its surrounding soil. With this kind model, this paper has also created one finite element model, which can be applied to perform finite element calculation and analyze the pile-loading feature, and deduced its element stiffness matrix.

在承台-桩-土共同作用中，考虑桩与承台的几何特性，采用有限元方法，用实体单元模拟桩土，用板单元模拟承台，更具体地分析桩和承台的受力特性和变形，而且还采用罚单元—既实体单元与板单元之间连接必须满足变形协调条件，来有效地解决了承台与桩土的连接问题，且在桩土共同作用中，由于桩体结构的材料性能与周围土层性质相差较大，在竖向荷载下有可能在其接触面上产生较大的剪应力从而导致错动或开裂，因此，为了充分反映桩土接触面上的受力及变形特征，应采用一种桩土接触面特有的本构关系，即利用张冬霁等人关于结构与土体接触面单剪试验所得到的接触面变形特征及其本构关系，引入桩-土三维等厚度接触单元来模拟桩与桩侧土之间的&滑移&，在此基础上建立可用于桩基承载性状分析的有限元计算单元模型，并推导出了各单元的刚度矩阵。

In the finite element analysis, by adding individual beam elements to model the connector between top joints and chords in finite element model, based on the experimental model, the factors affecting the shape forming process of dome, such as the bending stiffness of duckbilled connector and the size of top joints, can be taken into account; A whole and continuous analysis method is put forward for solving the question of applying the member forces produced in the shape forming process to the finite element models of load analysis.

有限元分析中，采用节点增设独立梁单元的方法，研究了鸭嘴半刚性连接和上弦节点域大小对穹顶成形过程的影响；提出了统一连续的分析方法，很好的解决了成形初应力向穹顶承载力有限元分析模型中的施加问题。

Magnetotelluric field finite difference migration tomography Found on the researches of Zhdanov etc. in MT finite difference migration tomography, we analyze and summarize both fruits and limitation of foregone peoples' achievements. So more precise finite difference extrapolation equation can be deduced, and it can be easily applied into the migration tomography. New equation reserved the derivative terms of wave number both at vertical and horizontal direction, so that more exquisite geoelectric diversification can still be accommodated, that is the very requirement of practical data interpolation.

大地电磁有限差分偏移成像技术：在Zhdanov等人建立的有限差分偏移成像研究的基础上，总结分析了前人在 MT成像技术方面的研究成果和存在问题；推导更精确的有限差分波场延拓方程，采用改进的有限差分法进行大地电磁场偏移成像，差分延拓方程保留波数对水平方向和垂直方向的一阶导数项而提高求解精度，可适应电性纵横方向变化剧烈的地电构造，使成像分辨率得到增强。

This paper reviews and summarizes the progress in this field as follows: the mathematical model and the difficulty of the analytical solutions is introduced; discusses the latest progress of the numerical solutions is discussed; the finite difference method, the Godunov method, the Boltzmann method, and the KFVS method of one-dimensional dam-break problem are introduced; the TVD method, the discontinuous finite element method, the finite volume method and characteristic method of two-dimensional dam-break problem are discussed; the applicability, the advantage and the disadvantage of each method are analyzed; and the progress in the numerical calculations of flow of fluid with free surface are presented.

回顾和总结了国内外对溃坝水流演进问题的研究进展：介绍了溃坝水流的数学模型及解析解法存在的困难，进而讨论了数值解法的最新进展；论述了求解溃坝水流一维问题的有限差分法、近似黎曼解的Godunov格式法、Boltzmann法、KFVS法和二维问题的TVD格式法、间断有限元法、有限体积法、特征线法，并分析了各种方法的适用范围和优缺点，及讨论了限制函数的使用；介绍了利用自由水面追踪方法计算溃坝水流的研究进展，并根据目前存在的不足和实际工程的需要，提出了进一步研究的方向和发展趋势。

Based on Wilson\'s lemma on evenly distributed differences, elementary number theory and fundamental theory of finite field, the finite field construction for strict optimal OOCs is proposed and the basic idea of this construction is investigated. The main steps and flow chart of assistance design by computer are obtained.

3基于Wilson均匀分布差引理、初等数论及有限域的基本理论，提出一种严格最佳光正交码的有限域构造法，对该构造法的基本设计思想进行深入的理论分析，得到该构造法计算机辅助设计的主要步骤及流程。

Finite element method is based on the actual ship models, a true reflection of the real ship distribution of the specific structure. This paper also uses empirical formula to calculate the inherent frequency of the catamaran; contrast them in the process of modeling the structural stiffness, and quality of the different treatments, as well as natural frequency calculated from the results of differences analyze the different and the reason between the finite method and the empirical formula method which used to calculate the inherent frequency of catamarans in the vibration analysis.

有限元方法是根据实际船型，较真实的反映了实船结构的具体分布特征；本文还采用经验公式对该船的固有频率进行了计算，对比它们在建模过程中对结构刚度、质量的不同处理，以及计算所得固有频率结果的差异，分析了在双体船振动特性分析中有限元法与经验公式法的结果略有差距及其原因。

In the surveys, some very closely spaced survey lines displayed remarkable differences in crustal structure. To find the reasons for the differences and to analyze the reliability of crustal structure, ocean bottom seismometer data from the west and east sides of the Dongsha Islands were reprocessed and inverted with tomography technique. The routine processing and inversion procedures include clock correction, position correction, finite-difference ray-tracing-based tomography, checkerboard test and comparison of the inverted crustal model with initial models. As a key step, we analyzed the lateral velocity resolution and smoothed out the short wavelength velocity variation which maybe most probably artifacts in the final velocity models.

在一些相隔很近的测线上，探测的深部地壳结构却相差较大，为了分析这些探测结果中差异的原因和地壳结构变化的可靠性，本文以东沙东侧海域测线和东沙西侧海域测线为例，对采集的海底地震仪记录进行了时间、位置校正和初至波走时拾取，利用有限差分地震走时层析成像进行了走时反演，获得所在剖面的地壳速度结构，并分析了模型的横向分辨率，剔除模型中短波长的横向速度变化。

You can snipe the second and third union leaders from this position.

您可以鹬第二和第三工会领袖从这一立场出发。

Aiming at the currently shortage of XML streams quality detecting, this paper proposes a new forecasting method of XML streams quality by least squares support vector machines, which is used the method of XML keys' vector matrix as windows, and vector product wavelet transform to multilevel decompose and refactor the XML streams series, that can fulfill real-time checking demand of XML quality, and ensure constraint, consist- ency and integrality. For even more adapting net load, it proposes a control strategy by weight and adaptive adjustment to ensure XML streams quality.

针对当前XML数据流质量检测存在的不足，提出构建XML键的矢量矩阵作为窗口，利用矢量积小波变换多级分解与重构XML数据流，再结合最小二乘支持向量机对XML数据流质量进行预测的一种方法，满足XML数据流质量重构时实时检测的要求，保证XML数据的约束性、一致性与完整性；为了更好的适应网络负载，采取加权与自适应窗口调整等调度策略充分保证XML数据流的质量检测。