Engineering)经典双语详解讲义__图文
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Engineering Economy 工程经济学讲义
Revisit Your Decisions
Improved decision making results from an adaptive process; to the extent practicable, the initial projected outcomes of the selected alternative should be subsequently compared with actual results achieved.
Make Uncertainty Explicit
Uncertainty is inherent in projecting (or estimating) the future outcomes of the alternatives and should be recognized in their analysis and comparison.
CHAPTER 1
INTRODUCTION TO ENGINEERING ECONOMY
Introduction to Engineering Economy
Title 1 Introduction
Title 2 Origins of engineering economy
Title 3 Principles of engineering economy
Resource
Land
Labor
Capital
All gifts of nature, such as: water, air, minerals, sunshine, plant and tree growth, as well as the land itself which is applied to the production process
电工学原理及应用(Electrical Engineering)经典双语详解讲义
Alternating Current
On the other hand, a current that varies with time, reversing direction periodically, is called alternating current, abbreviated as AC.
3Ω
4Ω 2Ω 3Ω a 6Ω
10V
Congsidering current I， N=4,B=6,L=7
N=3,B=5,L=6
1.4 Kirchhoff’s current LAW (KCL)
The net(净，总的) current a node is zero.
Ｉ= 0
entering
• Electrical Engineering Subdivisions
• • • • • • • • Communication systems Computer systems Control systems Electromagnetics Electronics Photonics Power systems Signal processing
P1 P2 P3 P4 P5 90 20 120 90 80 0
功率平衡！电路中所有元件的功率之和为 0 ！ 常用作对分析结果的检验准则。
•About Kirchhoff
古斯塔夫· 罗伯特· 基尔霍夫(Gustav Robert Kirchhoff )
——/wiki/Gustav_Kirchhoff
Box3
P3 U 3 I 3 60V ( 2)A 120W<0
U1 1
U2 2 U5
电工学原理及应用(Electrical Engineering)经典双语详解讲义 (5)
U d
U Ii
f
(1 A F)ri
2) 并联负反馈 使电路的输入电阻降低
ii
id
+
ui if
ri
–
ri f
1
ri A0 F
无负反馈时：
ri
ui id
+
有负反馈时：
–
rif
ui ii
ui id i f
1
1 AF
ri
6.对输出电阻的影响
1) 电压负反馈使电路的输出电阻降低
rof
1
ro A0 F
uo 电压负反馈具有稳定输出电压的作用
2. 并联电压负反馈
if RF
i1
+ ui –
R1 R2
id
– +
－
++
RL
uo –
设输入电压 ui 为正， 差值电流 id = i1 – if if 削弱了净输入电流(差 值电流) ——负反馈
反馈电流
if
uo Rf
取自输出电压——电压反馈
反馈信号与输入信号在输入端以电流的形式比
反之若比较的结果使净输入信号增大，因而输 出信号也增大，称为正反馈(positive feedback) 。
17.1.2 负反馈与正反馈的判别方法 反馈类型的判别步骤
1) 找出反馈网络（一般是电阻、电容) 2) 采用瞬时极性法判别正负反馈 3) 判别是交流或直流反馈？ 4) 是负反馈！判断是何种类型的负反馈？
电压负反馈具有稳定输出电压的作用，
即有恒压输出特性，故输出电阻降低。
2) 电流负反馈使电路的输出电阻提高
rof (1 A0F )ro
电流负反馈具有稳定输出电流的作用，
电工学原理及应用(Electrical Engineering)经典双语详解讲义
N
–
+
内电场被加 强，少子的漂 移加强，由于 少子数量很少， 形成很小的反 向电流。
PN 结加反向电压时，PN结变宽，反向电流较小， 反向电阻较大，PN结处于截止状态。 温度越高少子的数目越多，反向电流将随温度增加。
•二极管的符号与结构Fra bibliotekuDD 外形 iD 国标符号 D 美标符号
根据PN结构造面的特点，二极管分为点接触型、面接触 型、键型、合金型、扩散型、台面型、平面型、合金扩散型、 外延型、肖特基型等。
I D2
D1承受反向电压为－6 V
3
4mA
Ex.8.8 Assume ideal diodes, find the diode states for the circuits shown in Fig. 10.17.
D1 is on;
D2 is off;
D3 is off;D4 is on.
Electrical Engineering and Electronics II
Chapter 8 Diodes
4 Course Hours
Chapter 8 Diode
8.1 Basic Diode Concepts 8.2 Load-line analysis of diode circuits 8.3 Zener-diode voltage-regulator circuits 8.4 Ideal-diode model 8.5 Piecewise-linear diode models 8.6 Rectifier circuits 8.7 Wave-shaping Circuits 8.8 Linear Small-signal Equivalent Circuits
《工程制图》(双语)讲义-Note2
Parallel Projection
Orthographic Projection
Oblique Projection
Characteristics of Projection
The size of projection is independent of the relative distance of the object and the plane. So the measurement character is good. Engineering drawings adopt orthographic projection mostly.
Projection Plane C1 Z1
X Z
C
O
Projection Plane
Z1
A
Y
C1 B1
X 1 A 1 O1 Z C O XA BY
B1
Y1
B
A
X1 1
O1
Y1
O1A1 = p OA
O1B1 = q OB
O1C1 = r OC
Parallel Rules
Oblique Projection
If the cube is placed so that its front and rear faces are parallel to the projection plane and the parallel projectors make a oblique angle with the projection plane, then the projection is a general oblique projection.
★ If two lines parallel each other, the axonometric projections of two lines parallel each other. ★ The ratios of the length of two paralleling lines is equal to the ratios of the length of axonometric projections of two lines.
电工学原理及应用(Electrical_Engineering)经典双语详解讲义_(1)
Power systems convert energy to and from electrical form. Signal processing is concerned with information-bearing
electrical signals.
• Why Study Electrical Engineering?
•
• • • • •
Control systems
and magnetic fields.
gather information with sensors and use electrical energy to control a physical process.
Electromagnetics is the study and application of electric Electronics is the study and application of materials, devices
Alternating Current
On the other hand, a current that varies with time, reversing direction periodically, is called alternating current, abbreviated as AC.
q(t ) i (t )dt q(t0 )
t0
t
Example 1.1 Determining Current Given Charge
q(t )( C )
2
0
Suppose that charge versus time is given by
q( t ) 0
电工学原理及应用(Electrical Engineering)经典双语详解讲义 (2)
The Summary of Series/Parallel Equivalents
Although they are very important concepts, series/parallel equivalents and the current/voltage division principles are not sufficient to solve all circuits. Series/Parallel Equivalents are useful to solve simple circuits (is composed of single source and multiple resistances can be reduced by series/parallel equivalents ) Complex circuits are typically composed of multiple sources or multiple resistances can not be reduced by series/parallel equivalents.
R1 v i2 itotal R2 R1 R2
•Application of the Current-Division and Voltage-Division Principle
Example 2.4 Find the values of is and i3.
i3 is * R2 / ( R2 R3 ) 1.25 / 3 0.417 A
•Homework
P2.2 P2.7 P2.10
2.4 Branch current analysis
•The first and most straightforward complex network analysis technique is called the Branch Current Method. •Let the branch currents be unknowns, write equations describing their relationships to each other through Kirchhoff's and Ohm's Laws. •Give rules to write b independent equations to find currents of b branches. •For the network with b branches and n nodes, use KCL to write n-1 current equations and use KVL to write b(n-1) independent voltage equations.
《工程制图》(双语)讲义-Note1
Lesson 1 Basic Drafting
1 2 3 4
Drawing Equipment Drafting Standard Geometric Construction Dimension
Drawing Equipment
SKETCHES and DRAWINGS
SKETCHES and MODELS
ASSEMBLY DRAWINGS
Refinement of the model
Projection
Object Projection
First Angle Projection and Third Angle Projection
V
V
First angle projection
Third angle projection
OTHER APPLICATION
Image Process
OTHER APPLICATION
Game, Film and Cartoon
SUMMARY
The graphic language is the universal language used by every engineering team designing and developing products throughout the world. Every technical drawing is based on standard that prescribe what each symbol, line, and arc means. We need to train our ability of spatial imagining, learn how to transform 3D object to 2D projections and 2D projections to 3D object. For train your ability of spatial imagining, you must do exercises yourself.