第一节 桌椅设计概述 第二节 坐姿生理解剖基础 第三节 座椅的功能尺寸 第四节 坐垫与靠垫 第五节 办公桌的功能尺寸

Lecture D32: Damped Free Vibration Spring-Dashpot-Mass System k Spring Force Fs =-kx, k>0 Dashpot Fd =-cx, c>0 Newton's Second Law (mx =EF) mx +cx+kx (Define)Natural Frequency wn=k/m,and

Lecture D33: Forced Vibration Fosinwt m Spring Force Fs =-kx, k>0 Dashpot Fd =-ci, c>0 Forcing Fext Fo sin wt Newton's Second Law (mix =CF) mx+cx+kx= Fo sin wt =k/m,=c/(2mwn)

Surface quality is another aspect of machining accuracy. It consists of the surface finish and the physic mechanical state of the surface layer. It affects the proper functioning and service life of the parts Surface Finish Machining accuracy is expressed quantitatively in machining error. Surface finish is expressed quantitatively in surface roughness. The surface roughness on a machined workpiece surface is caused primarily by the geometrical factors(cutting tool geometry and cutting

不确定性分析 一、项目投资决策中收益与风险的权衡 收益 风险 投资 目标 二、主要的不确定性分析方法 盈亏平衡分析:确定盈利与亏损的临界点 一敏感性分析:分析不确定因素可能导致的后果 一概率分析:对项目风险作直观的定量判断

When the only force acting on a particle is always directed to- wards a fixed point, the motion is called central force motion. This type of motion is particularly relevant when studying the orbital movement of planets and satellites. The laws which gov- ern this motion were first postulated by Kepler and deduced from observation. In this lecture, we will see that these laws are a con- sequence of Newton's second law. An understanding of central

In this lecture, we consider the problem of a body in which the mass of the body changes during the motion, that is, m is a function of t, i.e. m(t). Although there are many cases for which this particular model is applicable, one of obvious importance to us are rockets. We shall see that a significant fraction of the mass of a rocket is the fuel, which is expelled during flight at a high velocity and thus, provides the propulsive force for the rocket

In this lecture, we will consider how to transfer from one orbit, or trajectory, to another. One of the assumptions that we shall make is that the velocity changes of the spacecraft, due to the propulsive effects, occur instantaneously. Although it obviously takes some time for the spacecraft to accelerate to the velocity of the new orbit, this assumption is reasonable when the burn time of the rocket is much smaller than the period of the orbit. In such cases, the Av required to do the maneuver is simply the difference between the

第一节 夹具的基本概念 第二节 工件的定位原理 第三节 定位方式与定位元件的选择 第四节 定位误差 第五节 工件的夹紧 第六节 各类机床夹具特点

– 1、掌握设备有形、无形损耗的类型及其对设备价值的影响； – 2、掌握设备折旧的含义、折旧方法与计算； – 3、掌握设备经济寿命概念及其计算； – 4、掌握存在新设备的设备更新原则及方法； – 5、掌握存在税收影响的设备租赁与购买比较决策