质点

40In this chapter we develop the implications of momentum conservation in the motion of a collection of particles.

本章将揭示群质点运动时动量守恒的含义。

In this paper,the boundary singular kernel method in Reproducing Kernel Paicle Method has been applied to impose the essential boundary conditions in EFGM by revising the MLS shape function.The stress field and the displacement field are analysed by linear elastic theory.The contour integral method is used to calculate the J-integral,then the stress intensity factors of mixed-mode crack is acquired.The correctness and the validity of the method are validated.

本文将再生核质点方法中的边界奇异权方法引入EFGM中，通过对MLS形函数进行修正实现了本质边界条件在节点处的精确施加；运用线弹性断裂理论分析裂纹板的应力应变场，采用围线积分法计算J积分，给出了复合型裂纹板的应力强度因子的无网格伽辽金方法。

, the motion of a particle is referred to by a rectangular coordinate system.

在图6-1中，质点的运动是用直角坐标系来描述的。

The inertia force and coriolis force are calculated to draw deviation for opposite balance, fall and plane motions close to the earth, based on the particle motion differential equation to no-inertial frame of reference.

在质点对非惯性参考系的运动微分方程的基础上，计算惯性离心力和科里奥利力对地球表面附近物体的相对平衡，落体运动和平面运动引起的偏差。

By the natural and harmonious relationship between differential forms and differential equations and between differential forms and vector analysis, we discuss the properties, which are covariant under the transformation of coordinates in the framework of differential forms, of particle motion in a central force field .

通过微分形式与微分方程和向量分析之间存在的自然而协调的关系，在微分形式框架下讨论了质点在有心力场中运动的特性并得出在坐标变换下其均是协变的

The succession of points occupied by the particle will trace out a curve in space.

质点连续经过的点描绘出一条空间曲线。

It discusses the definite methods of cutting-pattern lines in the paper and also solves the problems to expansion of the membrane curved surface on the basis of modeling analysis. The paper combines two kinds of methods: the plane cutting method and the expansion method based on spring-mass system, to realize the cutting pattern analysis of the pneumatic membrane structure.

本文在造型分析的基础上对裁剪线的确定方法进行讨论，并对膜曲面的展开进行了分析，结合两种方法——平面切割法和基于弹簧质点系统的展开方法，完成了充气膜结构的裁剪分析。

This paper discusses the mechanism of the propagation of elastic surface wave,presented a method that use the tip of atomic force microscopy and beam deflexion method to on line detect the nanometer vibration of the particle in the surface wave.

本文探讨了表面弹性波传播的机制，提出了一种利用原子力显微镜微探针与光束偏转法检测纳米振动的新方法，并利用这种方法对表面波质点的纳米振动进行了实时检测。

In the context of signal processing it is often referred to as the unit impulse function. Note that the Dirac delta is not strictly a function. While for many purposes it can be manipulated as such, formally it can be defined as a distribution that is also a measure .

在物理上，通常用于代表脉冲函数，或者呈点分布的物理量，例如质点、点电荷等；另外，delta函数常用于表示对物理量在某点的抽样，这一点不仅在数学物理方法这样的理论学科中常用，在实际的工程通信中也很常用，这时delta函数被用作采样函数。

This paper measured the constitutive relation of soil in the condition of the low stain-rate by Split Hopkinson Press Bar technology. It offers the reference for study in high stain-rate in the future. And simulated the explosion between soil and concrete by finite element dynamic analysis software LS-DYNA3D. Finished the numerical simulation for power of exploding between soil and concrete in different position of detonator and different scale model. Set out the curves of displacement, velocity, acceleration and pressure of different position. Obtained the destructibility of concrete target in different explosion condition. It offers data reference for theory studying and engineering designing.

本文首先利用分离式Hopkinson压杆实验技术测定了土在低应变率下的本构关系，为以后进行较高应变率下的研究提供了参考；后面着重利用三维显式非线性有限元动力分析软件LS-DYNA3D对土壤混凝土介质中的爆炸进行了数值模拟，采用土壤混凝土分层介质模型，完成了不同装药位置、不同缩比模型的混凝土模型中爆炸威力的数值模拟，测定了不同情况下的压力曲线及典型位置的质点位移、速度、加速度和压力，得出了混凝土靶在各种不同爆炸条件下的破坏情况，为理论研究和工程设计提供了数据参考。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。