查询词典 boundary element method

The examples given have proved the advantage of the Boundary Element Method. In the analysis of the fracture mechanics using Boundary Element Method, the calculation model of one-quarter singular element has been established, and has been proved its validity.

把边界元法应用于线弹性结构断裂分析中，建立了裂尖奇异区分析的四分之一奇异元计算模型，算例表明，用四分之一奇异元分析断裂力学问题是一种有效的逼近裂尖场的数值方法。

Boundary element method is a kind of numerical algorithm on boundary; it is based on the boundary integral equation and employs the element discretization technique.

边界元属于边界型的数值方法，它是以边界积分方程为数学基础，同时采用了有限元法的单元离散技术。

The coordinate transformation and numerical integration was executed on the discretized tetrahedral elements based on which the 3-D MT vector-finite element method was implemented. A whole computation framework for 3-D vector-finite element method with unstructured mesh was given. Based on this some typical models were tested which has demonstrated that our algorithm could distinctively avoid problems caused by the fake solution and both the accuracy and efficiency were enhanced which made our algorithm has a bright future for further application.3. According to theory of Sobolev vector space and the discretization of Helmholtz space, the error estimate which was suitable for 3-D MT vector-finite element modeling was deduced by which the procedure of adaptive technique was guaranteed.4. Based on the fully unstructured tetrahedralization and optical strategy, the 3-D magnetotelluric h-adaptive vector-finite element method was presented through combining the error estimate. With this work, the accuracy and creditableness for 3-D MT complicatedly modeling was guaranteed.5. The 3-D magnetotelluric h-adaptive vector-finite element algorithm with unstructured mesh was implemented.

针对非结构化的四面体单元，采用坐标变换和数值积分方法，实现了MT三维矢量有限单元分析，建立起基于非结构化网格的三维MT矢量有限元计算流程，并对典型模型和国际标准电磁模型进行了数值模拟，结果对比和分析表明，基于非结构化网格的三维MT矢量有限元不仅消除了节点型有限元的伪解，而且具有很高的计算精度和速度，有广阔的应用前景。3、根据Sobolev函数的向量空间和Hemlholtz空间的分解，推导出基于残差的三维大地电磁矢量有限元后验误差估计公式，为三维大地电磁自适应矢量有限元数值模拟的实现奠定了基础。4、在完全非结构化四面体单元剖分及优化基础上，结合三维大地电磁矢量有限元后验误差估计公式，提出了基于非结构化网格的三维大地电磁h-型自适应矢量有限元计算策略，保证了对复杂大地电磁模型数值计算的精度和可靠性。5、实现了基于非结构化网格的三维大地电磁h-型自适应矢量有限元计算流程，对典型模型和国际标准电磁模型进行了数值模拟。

With an example, the paper uses finite element program ANSYS to establish three calculating model of the steel-concrete composite open-web floor: the combination finite element method of spatial beam elements and shell elements, the finite element method of shell elements and the combination finite element method of shell elements and entity element.

结合一算例，利用ANSYS有限元软件，建立了组合空腹楼盖的三种计算模型：空间梁单元与壳单元的混合元模型、空间壳单元模型、壳单元和块体单元模型三种理论计算方法，对这三种计算模型作分析对比，得到了静荷载作用下该类结构的内力分布规律及其他一些有价值的结论。

Main points of the thesis are as follows:(1) The main function models and information relations between these models in the CAPP system in the integrated CAD/CAM project are explained, a new process plan design method is mentioned based on analyses of process plan design. This method is based on the process plan prototype, and develops the prototype little by little until the perfect process plan is completed, the prospect of this method is discussed;(2) The feature abstracting rules and methods are studied, a feature coding system is developed based on GT, all the defined feature models are described by the mathematical methods;(3) The integrated method of CAD/CAPP based on features is mentioned, this method defines a feature exchanging model, and develops an interface software to exchange design data into technology data base, this technology data base includes the design and technology information of the parts;(4) The process plan reasoning method based on features is created, this method uses Mycin algorithm to solve the reasoning of the feature process plan. A process plan making system is developed. In this system part process plan is made by the semi-intelligent method, this method uses the feature reasoning, feature process chain searching and man-computer talking together;(5) The main structure of the HOPE system is introduced, a shaft drawing and its process plan made by this system are shown, the data process problem in process drawing making is also discussed;(6) A new method of describing process rule is introduced, this method uses IfThen rules and neural nets weight values together to describe process rules, the BP algorithm is adopted in this method;(7) The optimal machining sequence problem of the process steps on the same fixturing is discussed, optimal algorithms SA is applied to solve this problem, the result shows that this method is more efficient than the traditional method;(8) All jobs in the thesis are summarized. In order to carry out the research in the future, some rational proposals are given.

全文论述的内容主要有下列几个方面：(1)较为系统地阐述了CAD／CAM一体化工程项目中CAPP系统的主要功能模块及其信息流程，在分析工艺设计过程的基础上，提出了基于特征原型的渐进式工艺设计方法，并探讨了该方法的应用前景；(2)研究了零件特征提取的原则和方法，在成组技术的基础上，开发了一套基于特征的分类编码系统，并在提取零件特征的基础上，定义了零件特征的数据模型，开发了基于轴类零件特征的参数化设计系统；(3)研究了基于特征的CAD／CAPP集成的方法，通过定义零件特征数据模型的存储结构，开发了将设计数据转换到工艺数据库中的接口程序，为后续的CAPP系统提供必要的零件形状和工艺信息；(4)研究了基于特征的工艺推理方法，将Mycin算法应用到工艺决策中，开发了基于特征的工艺推理及工艺方案生成系统，在系统中综合运用特征推理、特征加工工艺链查询及人机对话相结合的半智能化方法确定零件加工工艺；(5)介绍了整个HOPE系统的总体结构，通过运行HOPE系统绘出了一轴类零件的零件图，并生成了该零件的加工工艺方案，初步探讨了基于特征的工序图生成技术中数据处理问题；(6)研究了工艺设计过程中知识如何有效表示的问题，提出了将显式的IF-THEN规则表示与隐式神经网络权值表示相结合的工艺知识表示方法，并利用BP算法进行了工艺知识表示的初步研究；(7)研究了工艺设计过程中同一安装下工步优化排序问题，利用神经网络中基于模拟退火的理论来解决该工步优化排序问题，实践证明该方法较传统的算法具有更高的效率；(8)总结了本文所进行的研究工作，为今后进一步开展工作提出了较为合理的建议。

It is different from the finite element method which uses the calculus of variation to construct the element-based approximate equilibrium equation. It does consider the equilibriums of forces on the inter-element boundary, which are neglected in the finite element method through the weak formulation.

这种方法跟有限元素法不同，因为有限元素法是采用变分法建立各个元素的近似平衡方程式，这种方法也考虑元素与元素相连接的边界上的力平衡条件，而在有限元素法的推导过程中我们忽略了这种条件。

Boundary polynomial point interpolation mesh-free method and boundary radial point interpolation mesh-free method were presented, based on polynomial basis and radial basis respectively for transient eddy current analysis, and their interpolation shape functions satisfy the Kronecker delta function and the essential boundary conditions can be directly imposed on the boundary nodes. An example on analyzing transient eddy current of a square metal column was set to prove the validity of the proposed methods, and a comparison on accuracy between BPPIM and BRPIM was analyzed as well.

运用多项式点插值法和径向基点插值法构造形函数，推导了适合于工程电磁场瞬态涡流问题的多项式基点插值边界无单元方法和径向基点播值边界无单元方法，这两种方法的空间插值形函数满足Kronecker delta条件，从而强加边界条件可以直接施加在边界点上，以金属长方柱的瞬态涡流分析作为数值算例，证实了两种方法的正确性和有效性，并对两种基类的点插值法进行了精度分析和比较。

First mostly contraposing hull deck structure it goes along FEA analysis, discuss the different influence degree of calculational results between the different simplifications of the mathematical model, thereinto mostly analyse five different simplifications of the deck model; Second contraposing hold section and hull deck structure it goes along FEA analysis together, discuss the different influence degree of calculational results between the different elements style, gridding number and gridding density, thereinto mostly analyse the difference between adopting 8 node shell element and 4 node shell element, nondense gridding and thick gridding, and numerous gridding number and few gridding number, In the end mostly contraposing hold section structure it goes along FEA analysis, discuss the different influence degree of calculational results between the different boundary conditions, thereinto mostly analyse the difference between adopting CCS boundary conditions and LR boundary conditions.

首先主要针对船体甲板结构进行分析研究，讨论结构简化不同对有限元计算结果的影响程度，其中主要研究分析了五种不同甲板结构简化模型；紧接着针对舱段与甲板结构一起进行分析研究，讨论单元类型，网格数量与密度的不同对有限元计算结果的影响程度，其中主要研究分析了分别采用8节点板壳单元与4节点板壳单元的不同，以及分别采用疏的网格与密的网格，多的网格数量与少的网格数量的计算结果的差异。最后主要针对舱段模型进行分析研究，讨论不同的边界条件对有限元计算结果的影响程度，其中主要研究分析了分别采用CCS舱段边界条件与LR舱段边界条件进行有限元计算而带来的结果上的差异。本文第二部分为港工建筑物中的大直径薄壁圆筒结构的有限元比较分析。在研究大圆筒的有限元比较分析中，主要讨论用不同的网格密度与数量来划分网格引起的差异。其中用了网格密，数量多与网格疏，数量少两种模型进行大圆筒结构的有限元分析对比

Based on the prior information obtained by qualitative inversion, the two stages inversion method was put forward. That is, the first stage is that distinguishing the high-quality element and non- high-quality element, and determining the initial iteration value of element sound velocity reasonably. The second stage is that treating differentially the constraint weights of the high-quality element and non- high-quality element, and then quantitatively inversing the final sound velocity distribution. The results of two concrete specimens indicate that the two stages inversion method can inhibit artifacts effectively and has better defect identification effect than normal one stage inversion.

在获取定性反演先验信息的基础上，提出了两阶段反演的方法：第一阶段，区分优质像元和非优质像元，合理确定像元声速的迭代初值；第二阶段，区别对待优质像元和非优质像元的约束权重，定量反演最终的速度分布。2个混凝土试件的模型试验表明，两阶段反演能有效抑制伪像，具有比常规的一阶段反演更好的缺陷识别效果。

FENG Kang, YU De-hao and some other scholars of our country are the first ones to create the natural boundary element method, and they have successfully studied the natural boundary reduction method for the boundary value problems of harmonic equation and biharmonic equation.

我国学者冯康、余德浩等首创自然边界元法，并已成功地研究了调和方程及双调和方程边值问题的自然边界归化方法。

I hope that this success is just the first in a long series.

我希望这只是成功的开始。

Three dimensional stresses on the interface of tire and soil, tire deflection and soil sinkage are measured.

测试轮胎——沙土界面上的三向应力、轮胎变形和沙土沉陷；建立考虑剪切应力对沙土承载特性产生影响的车轮牵引性能预测模型；分析车轮作用下土壤的纵向稳定性。