1.无源逆变电路和有源逆变电路有何不同? 2.换流方式有哪几种?各有什么特点? 3什么是电压型逆变电路?什么是电流型逆变电路?二者各有何特点?

生态学是研究有机体与其环境相互作用的科学。 “环境”是物理环境（温度、可利用水等）和生物 环境（对有机体的、来自其他有机体的任何影响） 的结合体

8.1 Differential equations of equilibrium 平衡微分方程 Plane problems平面问题的平衡方程 do ox+oty/oy+X-0 Otxy/ox+oo oy+Y=0(2.2.2) Spatial problems空间问题的平衡方程

Polar coordinates极坐标 The position of a point P in polar coordinates is defined by the radial coordinate r and the angular coordinateθ. 一点P的极坐标用径向坐标r和角坐标θ表示 P(r,0) displacements:位移:urue strains:应变:

Review: Inverse method逆解法 Select satisfying the compatibility equation 设定中,并满足相容方程V4φ=0(2.12.11) find the stress components by由下式求出应力分量 Txy--02d/ (2.12.10) find the surface force components by 由下式对给定坐标的物体求出面力分量

Section 12.1 Introduction and Assumptions 引言和假定 a plate is a body bounded by two closely spaced parallel planes and one or more prismatical surfaces normal to the planes

2.1 Plane stress and plane strain 平面应力问题与平面应变问题 2.2 Differential equations of equilibrium 平衡微分方程 2.3 Stress at a point. Principal stresses 一点的应力，主应力 2.4 Geometrical equations. Rigid-body displacements 一几何方程，刚体位移 Shear stress trajectories in a cantilever beam 悬臂梁的剪应力轨迹线 2.6 Physical equations. 物理方程 2.7 Boundary conditions 边界条件 2.8 Saint-venant`s principle-1 圣维南原理 2.9 solution of plane problem in terms of displacements 按位移求解平面问题 2.10 solution of plane problem in terms of stresses 按应力求解 2.11 Case of constant body forces 常体力情况 2.12 Airy`s stress function. Inverse method and semi-inverse method 艾瑞应力函数，逆解法，半 逆解法

1.1 Contents of Theory of Elasticity 1.1弹性力学的内容 ·NAME Theory of elasticity is often called elasticity for short. It is the branch of solid mechanics. 弹性力学的理论简称为弹性理论或弹性力学. 它是固体力学的一个分枝

QUIZI There is a 1-in-17 chance of drawing two successive hearts in this manner. The varieties of nonferrous(有色的) metals are nearly four times what they were. There are races(种,属) between animals large and small. Leprosy does not affect most animals the way it does humans

1·高频化的意义是什么?为什么提高开关频率可以减小滤波器的体积和重量?为什么提高开关频率可以减小变压器的体积和重量? 2.软开关电路可以分为哪几类?其典型拓扑分别是什么样的?各有什么特点?