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By using the theorem on cone expansion and compression and a fixed point theorem on cone,this paper is concerned with the existence of positive solutions for some boundary value problem of singular nonliear semipositive second-order three-point boundary value problem,which improve many known results.

运用锥拉伸与压缩不动点定理研究非线性奇异半正二阶三点边值问题正解的存在性，推广了一些已知的结果。

Primary atrial tumor has obvious characteristic on RT-3DE: All the atrial tumor display the same size of stereoimages as the tumor themselves. There is a clear boundary between the stereoimage of the myxoma and the atrial wall and there exists a short pedicle connecting the atrial myxoma to the atrial wall or the interatrial septum. The body of the atrial myxoma moves to and fro through the atrium and the atrioventricular valve with the contraction and relaxation of the heart with a fixative pedicle. Atrial myxoma leads to relative atrioventricular valve incompetence during systolic phase and relative atrioventricular valve stenosis during diastolic phase, but doesn't result in pathological changes of atrioventricular valve which restore to normal after exsection of the atrial myxoma. Malignant atrial tumor closely and extensively contact with atrial wall without obvious boundary, pedicle and movement with the contraction and relaxation of the heart.

所有心房肿瘤RT-3DE均实时显示与肿瘤大小相同的立体形态图像；心房黏液瘤立体形态图像与心房壁界限明显，都通过一短蒂与房间隔或心房壁相连，瘤体以蒂为固定点随心脏收缩、舒张在心房与房室瓣口之间往返运动；心房黏液瘤收缩期瘤体导致房室瓣相对关闭不全，舒张期瘤体导致房室瓣相对狭窄，但瘤体不引起房室瓣器质性病变，瘤体摘除后房室瓣功能即恢复正常；恶性心房肺瘤立体形态图像与心房壁关系密切，界限不明显，接触范围广泛，无蒂，瘤体不随心脏收缩、舒张运动。

Exterior problem ; boundary integral equations; equivalent boundary integral equations

外边值问题；边界积分方程；等价边界积分方程

Anisotropic problem;elliptic artificial boundary;exterior problem;natural boundary reduction;DDM.

各向异性问题；椭圆人工边界；外问题；自然边界归化；区域分解

Potential theory is used to transfer the exterior boundary value problem into the boundary integral equation of the first kind. A iterated Tikhonov regularization and a modified Tikhonov regularization are presented to solve the integral equation.

利用位势理论将外边值问题转化为第一类边界积分方程，再分别利用迭代的Tikhonov正则化方法和改进的Tikhonov正则化方法求解积分方程。

We investigate the natural boundary element method for the boundary value problem of Helmholtz equation in an exterior elliptic domain.

本文研究椭圆外区域上Helmholtz方程边值问题的自然边界元法。

In this paper,we investigate the natural boundary element method for the boundary value problem of Helmholtz equation in an exterior elliptic domain.

本文研究椭圆外区域上Helmholtz方程边值问题的自然边界元法。

In this paper, natural boundary reduction and natural boundary method for an anisotropic problem in an exterior elliptic domain is investigated.

研究一类各向异性抛物外问题的自然边界归化及其自然边界元方法。

When the boundary condition described above applied, we found that there's almost no influence on pattern styles, however, influence on pattern distribution.This study can simulate concentric eyespot and wave stripe along the boundary of wing in Nymphalidae, besides, we can also simulate smaller and non-regular wave pattern which distributes over the wing.

本研究最后结合以L系统字串重建的翅脉与涂林系统，配合不同系数并将重建之翅脉作为边界条件进行蝴蝶斑纹形成研究，发现边界条件对我们所使用的四种涂林系统所产生的斑纹型态没有显著影响，但对斑纹分布则是会有一定程度的影响。

In the analysis, firstly, the flux boundary condition is used to simulate the frictional heat resource between wheel and rail. The non-steady heat transfer between the contacting surfaces of the wheel/rail, heat-convection and radiation between the wheel/rail and the ambient were all taken into consideration. Therefore, a heat coupling model of the wheel/rail in rolling/sliding is put forward to calculate the frictional temperature rise in the wheel and rail. Secondly, after the temperature distribution of wheel/rail, due to friction, is calculated, substitute the thermal load with equivalent fictitious body force and boundary distributed force loaded on the nodes of the corresponding elements. The wheel-load is applied to the center of the wheel.

首先，用热流边界条件模拟轮轨接触界面的摩擦热源，考虑轮轨间的非稳态热传导、轮轨自由表面与环境的热对流、热辐射的影响，建立轮轨滚动接触热耦合有限元计算模型，分析计算轮轨滚、滑工况下的摩擦温升；其次，以求得的轮轨温度场结果作为求解轮轨应力场的已知条件，轮载以集中力形式直接加载于轮心处，将摩擦温升引起的热载荷等效为假想体力和热边界面力，施加于相应的单元节点上，建立了轮轨热—机械载荷耦合作用的热弹性平面应力模型，分析热—机械载荷作用下的轮轨应力场。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。