幂指数

The simulation results of the cylinder-block model were given in the article, consistent with that of Middlemen"s. It was shown that the block part could improve the uniformity of the flow distribution. The analysis of the flow field of some materials with different power-law factor in the die designed by Mckelvey was close to that of Mckelvey"s. It was shown that the flow distribution was uniform in the die that can producesheets with 1200mm in width. During the analysis the flow channel was divided into several parts to get the details about the fluid flow in each area. A conclusion was drawn after analyzing the influence of the die pressure on the flow distribution, that the higher pressure is good for the output and bad for the uniformity of the distribution. Simulation of the die applying the cylindrical main runner showed the fact that when the cylinder replaced the cone the change of uniformity was trivial. The uniformity of the non-block flow channel was so poor that the block in the proper position of the die channel was necessary. The project of the die for the wider sheet was put forth, and the analysis of the fluid flow in the die was shown.

本文模拟了圆柱管缝隙流模型的三维流动场，得到了与Middlemen结论一致的流动均匀性，并通过模拟直观地展示了采用阻尼块可以改善挤出均匀性的现象；分析了多种幂率指数的流体在Mckelvey等人设计的流道模型中的流动分布，得到了与Mckelvey的分析结果接近的压力降和流量偏差；本文建立了1200mm幅宽机头流道的三维有限元模型，并逐个分析各个区域和多个截面的流动分布状况，由此揭示了1200mm幅宽L-型机头流道内的流北京化工大学硕士学位论文动分布基本均匀，并在分析了机头压力对于挤出流动分布的影响后得出结论：较高的机头压力可以获得较大的产量，但是不利于物料均匀分布；模拟了采用圆柱管主流道时机头流道内的流动分布，得出结论：主流道由圆锥管改为圆柱管时对流动均匀性影响不大，通过设置适当的阻尼仍然可以达到挤出平衡；模拟了两端进料式圆柱管无阻尼流道的流动均匀性后得到结论：两端进料式无阻尼结构的流动均匀性较差，宽机头中仍然有必要设置阻尼块；确定宽幅机头流道的基本方案，并设计了一种宽幅防水卷材挤出机头流道的结构，通过流动模拟表明该种结构的流动均匀性较好；考察了宽幅机头对于不同厚度片材的挤出适应性，得到结论：当生产不同厚度的片材时，阻尼块高度需要调整。

The database consists of nodimensional data of load carring capacities, maximum pressures and their positions, flow factors, and power loss factors by solving full 2D Reynolds equation including oil feed features of 360°, 180°partial groove, and single oil hole, corresponding to a series of power law index, length/diameter, groove width/length, hole diameter/length, hole diameter/bearing diameter, eccentricity, angle between the attitude angle line and centre line of oil groove/hole, rotary, squezze, and oil feed pressure factors.

数据库中的数据通过求解全二维Reynolds方程和热平衡方程获得。数据库由对应于360°全油槽，180°半油槽和单孔的三类轴承的一系列的幂率指数，宽径比、槽宽／轴瓦宽、油孔直径／轴瓦宽、油孔直径／轴承直径、偏心率、偏位线与油槽中心线之间的夹角、挤压因子、旋转因子、进油压力因子的一系列的轴承无量纲的特性参数组成：油膜承载力、最大油膜压力及位置、流量系数和消耗功系数。

The results showed that soil wind erosion was the near-surface wind-sand activity. The sediment particle saltates mainly in 7.5-43.5 cm. Wind sediment amount decreased along height, which correlate well with power function, exponent function and logarithm function. The sediment particle composition was influenced strongly by wind erosion intensity and topsoil characteristics. However, the regularity of sediment composition was distinct in a definite paticle size in different heights. Wind erosion amount increases with wind speed exponentially, which was influenced by times that the wind does.

结果表明：阴山北麓农牧交错带土壤风蚀是一种近地表的风沙运动，风蚀物跃移颗粒体主要集中在7.5～43.5 cm高度，风蚀物含量沿高度呈一递减函数，对幂函数、指数函数和对数函数均具有较好的相关性；风蚀物颗粒组成与风蚀强度和地表状况关系密切；风蚀物颗粒组成以某一粒径范围、某一高度为界随高度的变化而表现出明显的规律性；风蚀量沿高度的变化与风力作用时间有关，风蚀量随风速的增大呈指数增加。

The structure functions D of flux variations caused by refractive scintillations are calculated.

对折射闪烁引起的流量变化的结构函数D的计算表明，结构函数的幂律部份的指数P（D依赖于上述两个成份的相对散射强度，即在连续介质散射为主的情况下；而在薄屏散射为主的情况下；若两个成份的散射可相比较时，1＜P＜2。

He also invented the notation which uses superscripts to show the powers or exponents, for example the 2 used in x2 to indicate squaring.

他也发明了用于标注幂或指数的符号，比如把2用在x2上表示平方。

Plunder melds and run with this jewel!

掠夺melds和运行与此宝石！

My dream is to be a crazy growing tree and extend at the edge between the city and the forest.

此刻，也许正是在通往天国的路上，我体验着这白色的晕旋。