In lecture D2 we introduced the position velocity and acceleration vectors and referred them to a fixed cartesian coordinate system. While it is clear that the choice of coordinate system does not affect the final answer, we shall see that, in practical problems, the choice of a specific system may simplify the calculations considerably. In previous lectures, all the vectors at all points in the trajectory were expressed in the

In this lecture we will look at some other common systems of coordinates. We will present polar coordinates in two dimensions and cylindrical and spherical coordinates in three dimensions. We shall see that these systems are particularly useful for certain classes of problems Like in the case of intrinsic coordinates presented in the previous lecture, the reference frame changes from point to point. However, for the coordinate systems to be presented below, the reference frame depends only on the position of the particle. This is in contrast with the intrinsic coordinates, where the reference frame is a function of the position, as well as the path

is a vector equation that relates the magnitude and direction of the force vector, to the magnitude and direction of the acceleration vector. In the previous lecture we derived expressions for the acceleration vector expressed in cartesian coordinates. This expressions can now be used in Newton's second law, to produce the equations of motion expressed in cartesian coordinates

一、荒漠化检测的概念及目的 荒漠化监测是人类对全球或某一地区 干旱、半干旱及湿润干旱区因气候变动 人类活动及其他因素引发的土地退化现 象,采取某些技术手段就人类所关心的 可以反映土地退化现象的某些指标进行 定期、不定期观测并以某种媒介形式 进行公布的活动

We will start by studying the motion of a particle. We think of particle as a body which has mass, but has negligible dimensions. Treating bodies as particles is, of course, an idealization which involves an approximation. This approximation may be perfectly acceptable in some situations and not adequate in some other cases. For instance, if we want to study the motion of planets it is common to consider each planet as a particle

In this course we will study Classical Mechanics. Particle motion in Classical Mechanics is governed by Newton's laws and is sometimes referred to as Newtonian Mechanics. These laws are empirical in that they combine observations from nature and some intuitive concepts. Newton's laws of motion are not self evident. For instance, in Aristotelian mechanics before Newton, force was thought to be required in order

实验步骤 (1)确定罐上发酵培养基的配制、灭菌及 接种方式对发酵的影响。 (2)查资料确定你选定的发酵产品在发酵 过程中的主要影响因素,如还原糖的量、 pH的波动,并将其转换为可以调整的物质 如需要添加葡萄糖调节还原糖的量,通过 添加氨水或尿素来调节pH及氨的供给

实验步骤 (1)确定罐上发酵培养基的配制、灭菌及接种方式对发酵的影响。 (2)查资料确定你选定的发酵产品在发酵过程中的主要影响因素,如还原糖的量、pH的波动,并将其转换为可以调整的物质如需要添加葡萄糖调节还原糖的量,通过添加氨水或尿素来调节pH及氨的供给

目标:选定任一你感兴趣的发酵产品,如 ,A, 抗生素,淀粉酶,确定该菌种的筛选模型、 采样方式,稀释倍数和方法,确定特定产 物微生物的筛选方案及影响因素

• 4.1 概述 • 4.2 物料衡算的基本理论 • 4.3 物料衡算举例 • 4.3.1 物理过程的物料衡算 • 4.3.2 化学过程的物料衡算 • 1.反应转化率、选择性及收率 • (1)限制反应物 • (2)过量反应物 • (3)过量百分数 • (4)转化率x • (5)选择性