包络速度

In this paper, the plane double enveloping worm has been researched. The motion equations have been built of it. The states of motions and victories and forces of the worm engaging point were been analysis.

本文以平面二次包络环面蜗杆传动为主要研究对象，建立了平面二次包络环面蜗杆传动的运动学分析模型，分析了平面二次包络环面蜗杆传动啮合点的运动状态、啮合点各方向的速度、各方向上啮合力的分力。

By using the CFD software FLUENT, the inner-flow field of centrifugal fans with ruled-surface impeller versus with enveloping surface impeller has been simulated. The static pressure distribution, the dynamic pressure distribution, the total pressure distribution, the turbulent intensity and the speed vector of the two kinds of centrifugal fans are then analyzed and compared. From the calculating results, we found that the pressure distribution, the speed vector and other parameters of the two kinds of centrifugal fans are basically same. This implies that the tool-path generating arithmetic for the machining of the impeller can meet the aerodynamic requirements of the centrifugal fan. Furthermore the method can provide proof for designing department to establish sound manufacturing tolerance for impeller.

最后采用CFD软件FLUENT，利用标准k-ε湍流模型，采用分离隐式求解器，分别对直纹面叶轮离心通风机和包络面叶轮离心通风机整体风机内部三维流场和单个通道流场进行了数值模拟计算，在计算结果的后处理中，对相同坐标值处的静压力、动压力、湍流强度和速度矢量等参数进行了分析与比较，结果表明：在相同的计算参数条件下所得到直纹面叶轮离心通风机和包络面叶轮离心通风机内部流场差别不大，从而揭示所采用的叶轮数控加工的刀位规划方法的规划误差对流体机械动力性能的影响不大，这也为设计部门制定合理的叶轮加工公差提供了依据。

In order to overcome the influence of return pulse motion,an improved extracting method is provided.

为克服速度造成的包络走动影响，本文提出了一种改进的目标抽取算法。

How to calculate the intersection point between line and CSV is a core problem in NC machining process simulation techniques. This paper presents a noval intersection algrithm by decomposing the CSV into several simple surfaces and the intersection point is found by solving the scalar equation.

论文中针对数控加工几何仿真中存在的几个难点问题，提出了以下的处理方法： 1利用包络理论计算多轴加工中刀具运动所形成的刀具扫描体，算法精确，简单，计算量小，运算速度快。

The results of numerical analysis show that the elastic modular and the poisson ratio have no effect on two-dimensional bearing capacity, but can affect the ultimate bearing capacity of three-dimensional foundations and control the convergence and precision of finite element calculation; the earth pressure coefficient controls the geostatic stress of foundation, sequentially affects the ultimate bearing capacity of foundations and the convergence of numerical calculation. When calculating the ultimate bearing capacity of undrained saturated foundation, the complete formulation exists shear locking, and reduce formulation exists hourglassing, so the hybrid formulation is suitable to imitate the geomaterial. When the soil obeys nonrelevent flow rule, the yielding function is different from potential function, and the elastic-plastic matrix of soil is asymmetric, so the unsymmetry numerical solver and appropriate finite element mesh is required.

研究结果表明，土体弹性模量和泊松比对二维基础极限承载力没有影响，但是影响着三维矩形基础的极限承载力，控制着ABAQUS数值算法的计算精度与收敛速度；地基土压力系数控制着地基土体中的地应力平衡，从而影响着二维条形基础和三维矩形基础的极限承载力和地基破坏包络面；对于不排水饱和软黏土地基，常规的完全积分单元会造成剪力自锁现象，而减缩积分单元则存在过于柔化的现象，故采用杂交单元来模拟较合适；当土体服从非关联流动法则时，屈服函数与塑性势函数之间存在差异，从而导致土体弹塑性矩阵呈现非对称性，在有限元计算中必须采用非对称数值解法，并且合理地划分单元才能对极限承载力进行准确求解。

The dissociation constants and the reaction rate constants of inclusion complexes formed between α、β—cyclodextrin and several naphthyl esters (α—naphthyl acetate,β—naphthyl acetate,β—naphthyl caproate) were obtained by kinetics of hydrolyses of naphthyl esters.

通过几种脂肪酸萘酯(乙酸-α-萘酯、乙酸-β-萘酯、己酸-β-萘酯)的环糊精催化水解研究得到了它们同环糊精所形成的包接络合物的分解平衡常数和反应速度常数，进而提出了它们同环糊精所形成的包接络合物的结构模型。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。