凹角

In this paper the natural boundary reduction for some elliptic boundary value problems with concave angle domains and its natural boundary element methods are investigated.

本文研究凹角型区域椭圆边值问题的自然边界归化及其边界元法。

Part II, the artificial boundary condition and its numerical methods based on natural boundary reduction for a hyperbolic initial boundary value problem in an infinite domain with a concave angle is investigated.

第二部分，研究一类具有凹角的无界外区域的双曲型初边值问题基于自然边界归化的人工边界条件及其数值方法。

A polygon with one or more ''.

有一个或多个凹角的多边形。

Whose content is pursued including using the AutoCAD software to draw out a part , is pursue the parametric choice carrying out analysis , blank choice , electricity to the part, the machine tool choice workpiece dress gripping and rectifying CAXA line cutting programming , the part treating and so on, reaches the scheme knowing well that a part processes process from blank to finished product's, and processes the problem should pay attention to in process and solving thereby

本次毕业设计的内容是电火花线切割样件加工，主要是对零件凹角和尖角进行电火花线切割加工，其内容包括使用AutoCAD软件绘制出零件图、对零件图进行分析、毛坯的选择、电参数的选择、电极丝的选择、机床的选择、工件的选择、工件的安装及校正、CAXA线切割编程、零件的加工等，从而达到熟悉一个零件从毛坯到成品的加工过程，以及在加工过程中应注意的问题及解决方案。

Whose content is pursuedincluding using the AutoCAD software to draw out a part , is pursuethe parametric choice carrying out analysis , blank choice ,electricity to the part, the machine tool choice workpiece dressgripping and rectifying CAXA line cutting programming , the parttreating and so on, reaches the scheme knowing well that a partprocesses process from blank to finished product's, and processesthe problem should pay attention to in process and solvingthereby

摘要本次毕业设计的内容是电火花线切割样件加工，主要是对零件凹角和尖角进行电火花线切割加工，其内容包括使用AutoCAD软件绘制出零件图、对零件图进行分析、毛坯的选择、电参数的选择、电极丝的选择、机床的选择、工件的选择、工件的安装及校正、CAXA线切割编程、零件的加工等，从而达到熟悉一个零件从毛坯到成品的加工过程，以及在加工过程中应注意的问题及解决方案。

A polygon with one or more reentrant angles.

有一个或多个凹角的多边形。

In the experience Salt、Sb and thulium can change primary Si and eutectic Si through changing the morphology, but the effect of modification is very defferent.

其中钠盐的变质效果强，锑次之，稀土变质效果最差；变质剂对Si相的变质主要是通过孪晶凹角沟槽机制进行的。

Salt is the best. Sb is better than thulium. The modification of modifying elements addition on Si takes effects through TPRE mechanics.

变质通过"毒化"孪晶凹角而抑制Si相在择优方向上的各向异性生长，迫使Si相产生多重孪晶并沿其它方向进行各向同性生长，长成等轴状。

The results show that the undissolved silicon particles in the melt become the cores of primary silicon precipitated in solidification and there is a close relationship between the shape of primary silicon and undissolved silicon particles. The growth of silicon follows not only the twin plane re-entrant edge mechanism, but also layer mechanism as well. Meanwhile, the shape of primary silicon also relies on kinetic surroundings, such as the transmitting of solute. At higher overheating temperature, the shape of primary silicon becomes the star-shape and tree-shape.

结果表明：重熔过程中熔体中未溶解的硅相粒子，在凝固过程中可成为初生硅生长核心，并且未熔颗粒与初生硅形状之间存在明显对应关系；初生硅的生长机制不是惟一的，既可以以孪晶凹角机制生长，还可以以层状机制生长，初生硅最终形状还要取决于溶质传输等动力学环境；随着熔体过热温度的升高，凝固组织中初生硅形状由多边形向星形及树枝状转变。

Beginning with these angles of the niche, the wall extended along the Rue Polonceau as far as a house which bore the number 49, and along the Rue Droit-Mur, where the fragment was much shorter, as far as the gloomy building which we have mentioned and whose gable it intersected, thus forming another retreating angle in the street.

和这斜壁两角相连的墙，在波隆梭街方面，一直延伸到第四十九号房屋，而在直壁街一面？？这面短多了？？直抵先头提到过的那所黑暗楼房的山尖，并和山尖构成一个新凹角。

I will endeavour to find you some assistance.

我尽力帮你找人帮忙。

At first I only know bruck is the idol of American younglings, afterwards I returned back to Taiwan ,even in Beijing last year ,I saw her poster everywhere, I was so surprised at her charm.

起初我只晓得布鲁克雷德丝是美国少男少女崇拜的偶像，后来回台湾，甚至去年在北京，居然也四处看见她的海报，才惊讶她的魅力之大。