对称面

This is obviously influenced by the base level up and down changings, pore space variation and sediment alimentation. Through analysing the relationship between the course of base level up and down cycles of high resolution sequence strata and the reservoir physical behavior, six heterogeneity models of diff...

通过高分辨率层序地层的短期基准面升、降旋回过程与储集物性关系的分析，建立了6种不同沉积微相的非均质性模式，探讨了向上变深、向上变浅的非对称型和向上变深后复变浅的对称型短期基准面旋回层序对储层非均质性特征的控制作用

Therefore, the moist potential vorticity analysis associated with the mesoscale convective system was researched in the paper, so as to reveal the moist potential characteristics of mesoscale convective system in typhoon circulation. The results showed that, during the generation stage, convective instability characterized by MPV1 was a favorable condition for forming MCS, while the vorticity which was caused by the slantwise isentropic surface and the vertical shear of the horizontal wind characterized by MPV2 was an inspiring mechanism. The specific process was that, the atmosphere exhibited the feature of strong convective instability at the low level of convection areas and the southeast areas, which included plenty of erratic energy. The slantwise ascended the stream transfer the erratic energy to northwest, where the stratification stability was small. As decreased, the cyclonic vorticity increased. On the other hand, the vorticity caused by the slantwise isentropic surface and the vertical shear of the horizontal wind inspired the release of convective instability and as a result that the MCS formed. During the development stage, the cyclonic vorticity increased quickly with the persistent decreasing of . Meanwhile, the inclination of isentropic linewas bigger than the absolute momentum line at middle level, which exhibited the feature of conditional symmetric instability , then the conditional symmetric instability was forced to release by the vorticity resulted from the slantwise isentropic surface and the vertical shear of horizontal wind, and the MCS developed.

结果表明，在对流形成阶段，MPV1即对流不稳定为MCS的形成提供背景不稳定条件，由MPV2即湿等熵面的倾斜和水平风的垂直切变而引起的涡旋发展作为强迫机制：MCS形成的区域及东南区域中低层是强对流不稳定层，蕴含丰富的不稳定能量，倾斜上升运动把对流不稳定区具有强不稳定能量的暖湿空气向西北中层的中性层结区输送，由于的减小，气旋性涡度增强，有利于形成对流，另一方面，由于湿等熵面倾斜和低空急流加强而引起的涡旋发展作为一种强迫机制激发对流不稳定能量得到释放，从而形成对流；在对流系统地发展阶段，由于低层的对流不稳定性进一步减弱，进一步减小，气旋性涡度进一步增强，有利于MCS的增强，中层等θe 线的倾斜度比绝对动量M 等值线的倾斜度大，对应有条件对称不稳定区域，满足条件对称不稳定条件，在湿等熵面倾斜和台风低空急流作用下引起的涡旋发展强迫对称不稳定能量释放，从而使得对流得以维持和加强。

For example, Keyfitz made the classification of the bifurcations in one state variable, without symmetry up to codimension 7; Golubitsky and Schaeffer obtained the classification of the bifurcation problems in one state variable with Z_2 symmetry, in one parameter up to codimension 3; Golubitsky and Roberts studied the classification of degenerate Hopf bifurcation in two state variables with dihedron D_4 symmetry, in one parameter up to topological codimension 2; Melbourne obtained the classification of bifurcations in three state variables with octahedral symmetry, in one parameter, up to

需要指出的是以上研究均没有考虑分歧参数的对称性，Futer，Sitta和Stewart的工作虽然考虑了分歧参数的对称性，但仅限于分歧参数与状态变量具有相同的对称性，他们得到了状态变量与分歧参数均关于二面体群D_4对称，拓扑余维数不大于1的分歧问题的分类。高守平和李养成则讨论状态变量和分歧参数均具有对称性且对称性可以不同的分歧问题，并给出了状态(来源：A770707BC论文网www.abclunwen.com)变量关于二面体群D_4对称，分歧参数关于S~1对称，拓扑余维不超过1的分歧问题的分类。本文第一章讨论两个状态变量关于二面体群D_3对称，两个分歧参数关于O(2)对称的分歧问题，给出了该类分歧问题在非退化条件q(0)≠0下所有情形的分类与相应的识别条来源：AdadaBC论文网www.abclunwen.com

Thus LES is proved to be suitable to simulate the flow and temperature fields of large scale vortices with complex geometric boundaries. LES cooperated with the second order full extension ETG finite element method is applied to simulate the forced convection heat transfer around two square cylinders arranged side by side. While the boundary conditions are symmetrical, the time history and power spectrums of drag coefficient, lift coefficient, averaged Nusselt number at the wall, and the streamwise velocity and temperature on the symmetrical points are calculated. The results show that the power spectrums are all almost symmetrical.

应用大涡模拟与二阶全展开ETG有限元离散格式相结合的方法对间距比为1.5的条件下横掠并列双方柱强制对流换热问题进行了数值模拟，通过边界条件对称时，对并列双方柱对称点上的速度和温度以及方柱的阻力系数、升力系数和壁面平均Nu数进行的时域分析和频域分析，得到了在对称边界条件下并列双方柱对称点上的速度和温度以及方柱的阻力系数、升力系数和壁面平均Nu数的功率谱均基本对称的结论。

The medium term and the long term cycles of datum plane are made of symmetry structures by the two half cycles of rising and falling, and the short term cycle of datum plane are divided into two basic types of symmetry and non symmetry.

中、长期基准面旋回由上升、下降2个半旋回构成对称型结构，短期基准面旋回分为对称型和非对称型结构。

Based on a comprehensive study of drilling and log data, sequences of short-term base-level cycle of turbidite fan in Yanchang Formation of Triassic in Longdong area are divided into three basic structure types: up - deepening non - symmetry, up -shallowing non ?symmetry and symmetry ones according to recognition sign of the interface of the short - term base - level cycle.

以高分辨率层序地层学理论和技术方法为指导，以钻井、测井资料的综合研究为基础，运用短期基准面旋回界面的识别标志将陇东地区三叠系延长组浊积扇短期基准面旋回层序划分为向上"变深"非对称型、向上"变浅"非对称型和对称型3种基本结构类型。

This paper analyzes the cause of distortion of octahedron complexes and tetrahedron complexes and states the general methods to judge the distortion .

分析了八面体配合物和四面体配合物畸变的原因，给出了判断八面体配合物和四面体配合物畸变的一般方法：配合物是否发生畸变要看中心离子电子云是否对称分布，若对称分布，就具有规则的八面体或四面体构型，否则，将会发生变形。

Based on a comprehensive study of drilling and log data, sequences of short-term base-level cycle of turbidite fan in Yanchang Formation of Triassic in Longdong area are divided into three basic structure types: up - deepening non - symmetry, up -shallowing non ?symmetry and symmetry ones according to recognition sign of the interface of the short - term base - level cycle.

以高分辨率层序地层学理论和技术方法为指导，以钻井、测井资料的综合研究为基础，运用短期基准面旋回界面的识别标志将陇东地区三叠系延长组浊积扇短期基准面旋回层序划分为向上&变深&非对称型、向上&变浅&非对称型和对称型3种基本结构类型。

Identical autopilots are used to control the pitch and yaw motions if the missile has two planes of symmetry.

如果导弹有两个对称面，则使用相同的自动驾驶仪控制俯仰和偏航运动。

There are three forms of symmetry in virus capsids: icosahedral , helical and complex forms.

壳粒排列的方式使病毒的结构呈几何对称，病毒衣壳有三种对称形式：二十面体立体对称、螺旋对称、复合对称，螺旋结构呈杆状，而二十面体由对称的亚单位组成近似的球状，非对称的衣壳是较复杂的形式，往往与细菌病毒有关。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷