查询词典 difference boundary value problem

Using the method of blow up lower and upper solutions, the existence and boundary behavior of positive boundary blow up solutions for some elliptic systems of competitive type with singular weight functions are obtained, here the singular weight functions are permitted to be bounded in some parts of the boundary, and to go to infinity or even oscillate in other parts.

利用爆破上、下解方法，本文建立了带奇异权函数的竞争型椭圆方程组正的边界爆破解的存在性和边界行为，这里奇异权函数可以在边界的某一部分有界，而在其他的部分趋于无穷或者震荡。

The modal tests of PCB and PCB assembly (free boundary condition and fixed boundary condition) were carried out. The equivalent elastic modulus and damping parameters of PCB can be gained, and the fixed boundary condition of finite element model was also determined. These will help to the following work.Second, drop impact tests of three different heights were carried out. Strains and acceleration responses of PCB were measured. Failed BGA packages of different test conditions were dyeing, and cross section analysis of failed solder joints was conducted.

针对JEDEC标准试件的局限性，提出了设计便于统计学研究焊点可靠性的试验试件的构想，利用有限元模态分析方法确定并验证了用圆形PCB组件替代JEDEC标准试件的可行性；通过一系列模态试验和有限元模态分析，确定了圆形PCB组件的相关试验参数，这不仅为跌落碰撞下PCB组件有限元模拟确定了较为合理准确的有限元模型，而且为正确地评价跌落碰撞下PCB组件的可靠性问题奠定了基础。2。

The modal tests of PCB and PCB assembly (free boundary condition and fixed boundary condition) were carried out. The equivalent elastic modulus and damping parameters of PCB can be gained, and the fixed boundary condition of finite element model was also determined. These will help to the following work. Second, drop impact tests of three different heights were carried out. Strains and acceleration responses of PCB were measured. Failed BGA packages of different test conditions were dyeing, and cross section analysis of failed solder joints was conducted. It was found in our drop tests that the root cause of lead-free solder joints under drop impact was the combined effect of mechanical shock and PCB bending vibration.

针对JEDEC标准试件的局限性，提出了设计便于统计学研究焊点可靠性的试验试件的构想，利用有限元模态分析方法确定并验证了用圆形PCB组件替代JEDEC标准试件的可行性；通过一系列模态试验和有限元模态分析，确定了圆形PCB组件的相关试验参数，这不仅为跌落碰撞下PCB组件有限元模拟确定了较为合理准确的有限元模型，而且为正确地评价跌落碰撞下PCB组件的可靠性问题奠定了基础。

As the application of the intermediate models is concerned, the works applying the intermediate models to investigate the topographic boundary layer, frontogenesis and low-level frontal structures, and the boundary layer jet are summarized in this article. It is mainly focused on the dynamic characteristics of the Ekman layer and its effect on the low-level structure and circulation of the weather systems illustrated by the models. It is shown that the intermediate boundary-layer models have great potential in illustrating the low level structures of the weather and climate systems as they are coupled with the free atmospheric models.

对于这些Ekman边界层近似理论模型的进一步应用问题，主要回顾和总结了利用上述模型探讨地形边界层结构、大气锋生过程、低层锋面结构和环流以及边界层日变化、低空急流形成等动力学问题的研究，并对这些研究所揭示的Ekman层动力学特征及其对自由大气低层运动的影响进行了分析，结果表明，这些Ekman边界层近似模型可以较好地揭示大气边界层动力学特征，在大气边界层动力学及其与自由大气相互作用的研究上具有重要价值。

In order to develop this local property,this paper presents a method,which uses Fourier Series to approximate the boundary shapes of the shafts with periodic boundary of cross section,and uses the conformal mapping in Theory of Function of a Complex Variable to make the complicated boundary shapes of the shafts map a unit circle.Thus elastic theory can analyze...

本文提出一种方法，其实质是：采用富里埃级数来逼近横截面呈周期性变化边界的轴类零件的边界形状；并应用复变函数论中保角映射原理，将零件复杂的边界形状映像成单位圆，从而使弹性理论可以分析和计算复杂边界轴类零件的应力场；再通过留数的求解实现保角映射的反变换。

O the system should be put into an expending system to be dealt with, which includes the original system, the environment system and the band boundary. There are various complex interactive relationships between the original system and the environment system in an expending system; therefore the band boundary becomes a gradational boundary.

AR系统理论借用了生物系统中的许多重要概念，比如感知、反应、捕获、游离等来研究这类复杂系统的演化问题，认为开放系统的复杂性主要是由系统与环境之间的相互作用关系产生的，而这种相互作用关系最集中地体现在系统边界上，因此必须把系统、环境以及边界三者一起放到一个更广泛的全系统中进行处理。

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。

There are multiple choices for the normalized boundary equation. Based on a chosen normalized boundary equation, a new normalized boundary equation can be established such that the irregularity of the kernel of integral equations is overcome.

边界方程有多种选择，在选定一种边界方程的基础上，可以通过建立一个新的边界方程来表示问题的边界，以克服积分核的奇异性。

Based on the additional information such as displacements or stresses provided at several internal or boundary points in the structure,combined with stochastic boundary element method and optimization technique,the basic model of the prediction of the structural reliability by inverse analysis of boundary element method is presented in this p.

本文利用随机边界元法与非线性优化技术相结合，根据弹性体内或边界上的位移、应力等附加信息，建立了结构可靠性预测的边界元逆分析法的基本模型，算例证明了该理论的有效

An artificial boundary is introduced, and an exact boundary condition by the natural boundary reduction is obtained.

引入一条人工边界，通过自然边界归化获得人工边界上精确的人工边界条件。

Many will continue to choose to live in duality and in conflict.

许多人将继续选择活在二元对立性和冲突中。

I find that students of the University of Physical Education all wear sportswear at first sight.

我发现：体育大学的学生乍一看，都是穿运动衣，大家都一样