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快速成型制造技术（英文要点·大三大四）
核心内容
Basic concepts:
In this course, we mainly learned the principles,characteristics and applications of several rapid prototyping manufacturing(RPM) .
Explanation of concepts:
RPM is with the help of the computer,laser,precision transmission, digital control ans some other modern technology, combine the CAD and CAM, according the 3D model in computer, can build the product model or sample in a short period of time, without the traditional machining machine tool and die technology.
AD: 1, free forming, without the use of tools or molds;
2, the manufacturing process is fast, form CAD to entities in general as
long as a few hours to teens hours, shorten the product design and
development cycle.
3, add type and digital drive molding method;
4, technology highly integrated, using CAD, CAM,new materials and so on;
5, economic benefits, a large number of cost savings;
6, a wide range of applications, suitable for new product development,
single or small batch production, complex shape parts production ,mold
design and manufacturing and other fields.
Stereolithography apparatus(SLA 光敏液相固化):
034290 The fluid bath is full of light cured resin(光敏树脂), the laser device radiates UV laser scanning the surface of the resin point by point, makes the thin layer of resin in the scanned area solid, and become a thin layer of the workpiece. When one layer is finished, the work platform go down for a distance of a layer. Then the drawing strickle(刮板) moves on the surface and make it smooth. Then repeat the process, until the workpiece is finished. Pick it out, wash it clean, then put it under the UV laser to solid it again. Then the workpiece is already.
AD: 1,high degree of automation of the molding process;
2,high dimensional accuracy, can reach 0.1mm;
3,excellent surface quality, although there may be some arris between
Layers, but the top of the surface can be like the glass;
4,can make the structure very complex and make the size relatively fine;
5,the hollow structure of the die casting can be directly produced;
6, the prototype can replaced the plastic parts in a certain degree.
DIS:1,with the physics and chemical changes in the molding process, the
manufacture is easy to band, need support;
2,the performance of the cured liquid resin is not as good as the commonly
Used industrial plastic, it is more brittle;
3,the cost of operating and maintenance is high;
4,can choose very few materials, mainly are light-sensitivity liquid resin;
5,liquid resin has a certain toxicity and odor, and need to keep avoid the
light;
6,need twice curing.
Laminated object manufacturing(LOM,叠层实体快速成型):
09525There are melt adhesive on one side of the paper, the press roller press the paper and heat it, make the paper stick on the work platform. Then the laser device emits laser to meshing the area which is not the contour of the wokpiece of present layer. Then the work platform went down for a distance of the thickness of the paper. Then the paper roller rolling, take the paper without the cut part away, and bring the new paper on the work platform. Repeat the step until the workpiece is finished. Then pick the workpiece out, wipe off the part with grid, the remain part is the workpiece.
AD: 1, the raw material price is very low, the prototype production cost is low;
2,the size of parts can be very large;
3,no need curing treatment after the manufacturing;
4,no need to design and manufacture the support structure;
5,the waste is easy to peel off(剥落);
6,the workpiece can withstand up to 200℃,and it has high hardness and
Good mechanical properties, can be processed directly;
7,the prototype precision is high.
DIS:when the thickness of the workpiece is very large, the forming process
costs a very long time, the efficiency is low. And the model can’t meet
water.
Selective laser sintering(SLS,选择性激光烧结):
The process is similar to the SLA, but the raw material is power. The powder makes the surface of the powder smooth and heat the surface of the powder to a temperature close melting. Then the laser device emits laser to melt the powder in the area of workpiece counter, then the work platform go down for a distance of a layer. Repeat the process until the workpiece is finished. Finally pick out the workpiece and wipe out the powder.
AD: 1, can choose many materials, metals and non-metallic materials are all
fine;
2, can produce the complex-shape prototype directly;
3,high precision, generally can achieve the 0.05~2.5mm, according the
difference of the powder;
4,no need to support structure, the workpiece is supported by the powder;
5,the material utilization rate is high, the powder which is not used can be
used again;
DIS:1, rough surface, because the raw material is powder, so the surface is like
powder;
2,the sintering process has peculiar smell;
3,sometime need complex auxiliary process, because some materials will
burn when meet high temperature, the work platform need to be
protected with flame retardant gas(阻燃气体);
Fused deposition modeling(FDM,熔融沉积快速成形):
We heat the material wire in the guide sleeve to melt, then squeeze it through the spray nozzle with micro nozzle. The temperature of the melt material is a little higher than the curing temperature. And the temperature of the top layer of the workpiece is a little lower than the curing temperature. So when the melt material comes out of the spray nozzle and meets the cured part, it will cure with the cured part. When one layer is finished, the work platform go down, and repeat.
AD: 1, the manufacturing principle and operation of the whole system is simple,
the maintenance cost is low, and the system is safe;
2, can use non-toxic materials, equipment system can be run in the office
environment;
3, with wax molding parts prototypes, can be directly used for investment
casting(消失模铸造);
4, the part can be shaped to any degree of complexity;
5, there are no chemical changes of the raw material in the molding
process, the distortion of parts is small;
6, the utilization rate of raw material is high, and the material life is long;
7, the support can be removed easily, no need for chemical cleaning, easy
separation;
8, can make colorful prototype directly.
DIS: 1, there are obvious stripes on the surface;
2,the strength of the vertical direction of the extension is weak;
3,have to design and manufacture the support structure;
4,have to scan the entire section of the layer, need long time;
5,the raw materials are expensive.
参考：来源：大三大四专业课资料（英文.docx｜专业：机械工程｜课程：快速成型制造技术
物理学
核心内容
· 光学 (Optics)
· 光的波粒二象性 (Wave-particle duality of light)
· 波动性 (Wave nature)
· 光的干涉 (Interference of Light)：两个或两个以上光波相互重叠时，出现稳定强弱分布的现象。
· 光的衍射 (Diffraction of Light)：光在传播过程中遇到障碍物或小孔时，偏离直线传播路径而绕到障碍物后面传播的现象。
· 粒子性 (Particle nature)
· 光电效应 (Photoelectric effect)：光照射到金属上，引起物质的电性质发生变化。
· 力学 (Mechanics)
· 牛顿三大定律 (Newton's three laws)
1. 惯性定律 (Law of Inertia)：任何物体都保持静止或匀速直线运动状态，直到受到其它物体的作用力迫使它改变这种状态为止。
2. 加速度定律 (Law of Acceleration)：物体受到合外力作用会产生加速度；加速度方向与合外力方向相同，加速度大小正比于合外力大小、与物体的惯性质量成反比。
3. 作用力与反作用力定律 (Law of Action and Reaction)：两个物体之间的作用力和反作用力在同一条直线上，大小相等，方向相反。
· 热力学 (Thermodynamics)
1. 热力学第一定律 (First Law of Thermodynamics，能量守恒定律)：一个热力学系统的内能增量等于外界向它传递的热量与外界对它所做的功的和。
2. 热力学第二定律 (Second Law of Thermodynamics)：克劳修斯表述 (Clausius statement)——热量可以自发地从温度高的物体传递到较冷的物体，但不可能自发地从温度低的物体传递到温度高的物体。
3. 热力学第三定律 (Third Law of Thermodynamics)：绝对零度 (absolute zero) 时，所有纯物质的完美晶体的熵值 (entropy) 为零。
参考：来源：物理学.png｜专业：生物科学｜课程：物理学
可靠性设计（英文要点·大三大四）
核心内容
Basic concepts:
In this course, I learned about what is reliability and some surface features of reliability, and fault tree analysis and how to use minimum cut set method(最小割集法) to get the rate of the top rate.
Explanation of concepts:
Reliability is an important quality index of the product, which includes the normal service ability of the product. Compared with the traditional safety factor design criterion, the reliability design criterion(可靠性设计规范) is more effective to ensure the safety of the product.
Reliability(R(t)可靠性):
Reliability is the product quality index(system or port) has the time attribute, defined as the product under prescribed conditions within the prescribed time, the ability of completing the function. Degree of reliability is defined as the rate of the product under prescribed conditions within the prescribed time to complete the functions.
Failure rate(λ(t)失效率):
Failure rate means the product work until the moment t and has not failed. And the rate of the product fails in unit time after the moment t.
According to the experiments, we get a curve of failure rate, it has 3 parts.
Initial failure(早期失效): caused by the product defects.
Random failure(偶然失效): caused by the operation mistake or the service mistake.
Loss failure(损耗失效): caused by aging, fatigue, wear and tear.
Maintainability(M(t)维修性):
Degree of maintainability means products after a failure, the rate of completing the repair under specified condition and time.
Mean time to repair: the average time that repair the products.
Repair rate(μ(t)): the rate of completing the repair after a special moment.
Fault tree analysis(故障树分析):
09525X are parts/components of system
G are mid situation event
T is top event
Lowest layer:
G3=x4+x5 G4=x6+x2+x4 G3=x3x4
Low layer:
G1=G3x3G4 G2=x2+G3
Top layer:
T=G1+x1+G2
Then we take the G1, G2, G3, G4 in to the T, we can get:
T=G1+x1+G2
=G3x3G4+x2+G5+x1
=x3x4+x2+x1+x3x5x2
So the minimum cut set is {x1},{x2},{x3,x4},{x3,x5,x2}
So the probability of the T working normal is
P(T)=P(x1)+P(x2)+P(x3x4)+P(x3x5x2)
参考：来源：大三大四专业课资料（英文.docx｜专业：机械工程｜课程：可靠性设计
物理学实验
核心内容
· 课程：物理学实验（生物科学专业）
· 核心实验一：用双缝干涉测量光的波长
· 实验原理
· 光的双缝干涉（double-slit interference）：单缝出射的一束光经双缝形成一对相干光（coherent light），两束光叠加产生干涉现象。
· 波长计算公式：Δx = Lλ/d
· Δx：相邻两条亮（暗）纹间的距离
· L：双缝到屏的距离
· d：双缝间距
· λ：单色光的波长
· 实验步骤
· 安装双缝干涉仪。
· 单缝到双缝间的距离取 5~10 cm。
· 依次放置滤光片、单缝、双缝。
· 调整装置，使单缝与双缝互相平行，双缝与灯丝平行。
· 测量 n 条亮条纹的间距 a。
· 观察条纹：移动测量头，使分划板中心刻线与某条亮纹对齐。
· 代入公式求出波长 λ。
· 核心实验二：验证机械能守恒定律
· 实验目的：验证机械能守恒定律（law of conservation of mechanical energy）。
· 实验原理
· 物体自由下落时只有重力做功，重力势能与动能相互转化，机械能守恒。
· 重物下落 h 时，通过计算对比重力势能减少量与动能增加量，在误差范围内验证机械能是否守恒。
· 实验步骤
· 将打点计时器（ticker-tape timer）安装在铁架台上，用导线把打点计时器与学生电源连接好。
· 纸带一端固定在重锤上，另一端穿过计时器限位孔，用手竖直提起纸带使重锤停靠在打点计时器附近。
· 接通电源，松开纸带，让重锤自由下落。
· 重做几次，得到 3~5 条打好的纸带。
· 在纸带上取“0”点，关注第一、二两点。
· 用刻度尺测出各计数点到“0”点的距离：h₁、h₂、h₃…
· 计算各点对应的瞬时速度 vᵢ，公式：vᵢ = (hᵢ₊₁ − hᵢ₋₁) / 2T
· hᵢ₊₁、hᵢ₋₁：与第 i 点相邻两计数点到“0”点的距离
· T：相邻两计数点间的时间间隔
· 计算各点对应的重力势能减少量 mgh 与动能增加量 ½mv²，进行对比（mghₙ 与 ½mvₙ²）。
参考：来源：物理学实验.png｜专业：生物科学｜课程：物理学实验
毕业实习（英文要点·大三大四）
核心内容
Basic concepts:
We paid a visit to some factories, mainly are the Hefei Changyuan hydraulic product company, and the MIMA forklift company.
Explanation of concepts:
As for the Hefei Changyuan hydraulic product company, we mainly visited its workshop, its production line is the flexible production line, many kinds of products are manufactured, most of them are hydraulic motors, hydraulic pumps, hydraulic valves and hydraulic cylinders. It is not a only-assembly factory, but a company can research and develop new products. And there are some advanced equipment in the factory of this company, i find a heat energy burring machine(热能去毛刺机) which is rare in China.
As for the MIMA forklift company, it manufactures forklift. But its forklift is different with the Heli forklift. The Heli forklift uses diesel oil as the fuel, but the MIMA forklift uses electricity, which is more benefit for the environment. And we see some special types of forklift, such as a 30-meter-lift-high forklift, and a large tonnage forklift. The 30-meter-lift-high forklift has a very big bob-weight to keep it balance when it lift things high. As for the large tonnage forklift, it uses solid tyre(实心胎) to afford its weight. And this company is working on developing the AGV(automated guided vehicle). The little car can work along the line on the ground, and it can avoid run into blocks which are putting in its way.
参考：来源：大三大四专业课资料（英文.docx｜专业：机械工程｜课程：毕业实习
测试技术基础（英文要点·复习资料）
核心内容
Sensors
1. Foil Strain Gauge
It is a device used to measure strain on an object.As the object is deformed, the foil is deformed,
causing its electrical resistance to change.
The sensibility can be given as
E
L
dL
R
dR
k
e
+
+
=
=
)
2
1(
/
/
the sensitive coefficient consist 2 parts, the 1st part is caused by Poisson Effect, while the 2nd part
is relative to the change of resistivity caused by strain.
The change of resistance is very small, usually measured using a Wheatstone bridge.
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by
balancing two legs of a bridge circuit. For example, the quarter wheatstone bridge have one leg
which is the unknown conponent.
and the balacnce conditions for the bridge is ...
so when the object is deformed, the resistance is changed, the galwanometer will not be zero,
with the number showed on it, we can know the unkown part.
Application: strain/ vibration/ torque measurement
2. angle/line displacement sensor
capacitance
d
S
C
=
dielectric constant/section area/the displacement of capavitive boards
circle turn
application: micro-displacement, such as the adjustment of electron microscope
also the capacitance sensor can be used to measure the air quality/ the water level
3. Piezoelectric sensor
some material will generate piezoelectricity/electricity when the material is compressed, that is
piezoelectric effect
measure changes in pressure, acceleration, temperature, strain by converting them to an
electrical charge
application: in many large shopping malls, the escalators will have a piezoelectric or pressure
sensor. when there are people on the elevator, it will run in normal speed; but when there are no
one on it, the speed will be relative low to save energy.
4. cross corelation function
the maximum value of this funtion is at the time difference, which show the lag time between
the two signal.
detect fracture site of a pipeline, we can install two sensors, there have different displacement
from the fracture site, so the signal from the break site to the two sensor will need different time,
and the time defference can be given by the cross corelation function, and by using the time we
can calculate the certain position of the break position. repair
signal processing and its application
1. two kinds of signal: analog signal is countinuous and most in the natural, digital signal is
discrete and for the machine. process information
so when we want to using the analog signal, we should convert it into digital, by
sampling/dicretization(function to sequence), finalization(infinite sequenc to finite)
in sampling, we should avoid frequency aliasing, that means when the digital signal change back
to analog, the useful information contained in the signal should be complete. so the smapling
frequency should more than double maximum frequency for the useful frequency band.
2. Fourier Series and Fourier Transform
the fourier Series normally represent the periodic signal as the sum of simple sine waves and
then we can make frequency-domain analysis.
There are two forms of fourier Series, one is the Trigonimetric function, the other one is the
complex exponential form. the converting between this two forms is using the Euler’s formula.
3. Fast Fourier transform
when we use sofeware programm to process the discrete signal, to reduce the amount of
calculation, we will use FFT to convert analog to digital.
1st the point N should be a power of 2;
2nd by using fft, we can convert the signal from time-domain to frequency-domain.
3rd the fft break up the N point transform into two transform of n/2(n/secends)
when the N is big enough, fft will reduce the number of computations needed for N points from
to 2Nlog2N.
with fft, we can achieve the real-time signal processing, which is really importent for industrial system.
in the experiment cource, we use the fft function in matlab to process signal.
4. filter
4: high pass/ low pass/ band pass/band stop
the design of Butterworth filter
normally, we use the function to determine the order of filter, the wc is cutoff frequency, which is -3db
frequency; the wp .and then we use a fomular to check the coeffient of the filter.
also we use maltab test the filter we design in the experiment course.
(convolution)
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：测试技术基础
机电一体化系统设计（英文要点·复习资料）
核心内容
1. sensor: sensor to position, according the displacement
Ultrasonic sensor measure the displacement by using ultrasonic waves, the sensor send the
waves and recive the wave reflected back from target. it can use the time and the sound speed to
calculate the displacement.
2. actuator: stepper motor, ball screw guide rail, manipulator/ robot arm(steering gear),
3. controller
python for the GUI(Graphical user interface): area, software programs, send the information
of coordinate value to matlab, analyse the changing trend of the value to know which number
that user has writed. send the to the microcontroller named STM32, the microcontroller will
control the actuaor move, to go into more detail, manipulator will catch the corresponding
number of objects as the user write on the screen to the certain area.
integrated design technology for mechatronics system
Rapid Application Development framework, it looks like a letter “V”.
the design of mechatronics system involves the knowledge of machinery, information, electricity
in this course, we are devided into 2 groups, each one have 15 people. and we design a
Electrohydraulic pump and a EHA, from the parameter calculation, structure design, modeling to
analysis and simulation, and we finished thesis and give a presentation to show our design.
the electrohydraulic pump is the conbination of motor and hydraulich pump, in a single shell, so
that it can spare space, but we should consider the friction and heat dissipation with the
hydraulic oil in the schell. and I was resonsible to the simulation of vibration of structure by using
soildworks to measure the natural frequency to avoid resonance. how change the structure
the EHA is an Electro-Hydrostatic Actuator, which is rapidly applied in the field of aviation, in
many modern plane, more than 50% actuator is the EHA.
I was responsible for the simulation of hydraulic system by using the software amesim, I set the
section area of the hydraulic cylinder, the rotational speed, displacement and other paremeters
of the pump, then I give the system a position feedback to improve the stability.
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：机电一体化系统设计
机电传动控制（英文要点·复习资料）
核心内容
motor
1. difference between Synchronous moter and Induction motor:
Synchronous motors and induction motors are the most widely used types of AC motor. In a
synchronous electric motor, the rotation of the shaft is synchronized with the frequency of the
supply current. An Induction Motor is an AC electric motor in which the electric current in the
rotor is produced by electromagnetic induction from the magnetic field of the stator winding.
·Synchronous moter: runs at a constant speed; It is not self-starting; External DC source is
necessary to provide excitation.
·induction motor: cheaper; construction is simple; It does not require any complex circuit for
starting; Speed control is difficult; Efficiency drops at low loads; Poor starting torque
2. difference between AC and Dc moter:
AC. motors are powered from alternating current (A.C.) while D.C. motors are powered from
direct current (D.C.), such as batteries, D.C. power supplies or an AC-to-DC power converter, DC
motor have high torque and easy to control of speed and torque.
3. the Basic structure of DC motor
·Stator(still): Main pole, Steel Core(increse the effect of magnetic fields) and Excitation Winding.
some have Brush
·Rotor(rotation): Armature core, amature Winding
the Stator generate magnetic field, and the rotor have torque to rotation.
4. Start-up mode
Mechanical characteristics of DC motor
we learned start-up mode, which have 3 types. the easiest one is direct start-up, but the current
is too large, so it’s normally not allowed.
the second mode is to add a series resistor in the aemature circuit, normally for small motor.
the ideal no-load speed is n0, the line slop is β.
third mode is to reduce the armature voltage when motor starts up, the energy loss is small and
it is suitable for large motor. n0, β, Is
the process is smooth, because the voltage can be continuously regulated.
speed regulation method and stop mode
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：机电传动控制
控制工程（英文要点·复习资料）
核心内容
this cource is about principle of automatic control
1. open loop and closed loop control
feedback:
positive--fish pool, rotten, the living environment/ a small disturbance to the system will lead to
an incredibal consequence.
negative-- in human’s body, when we are hungry, the blood sugar will decline, the brain tell us to
eat, and after eating, the blood sugar will increase, our body will secrete hormones to balance
the blood sugar. so the system will keep at a stable value.
block diagram: input, output, disturbance, the equivalent transformation for the diagram
2. time domain anslysis
the system is stable or not is an important character for the system in time domain. normally we
will use Routh Criterion : characteristic equation coefficient and the number in the first line of
the Routh formular are positive, the system will be stable.
the unit step response of first-order system
closed-loop transfer function of second order system
3. Laplace transform and tansfer function
the laplace transfer function is like this, but we almost not use the function to transform. we
didn’t learn the related methematic courses before, so we just remeber some commonly used
formula, like impulse function/ step / ramp/ exponential
transfer function is a representaion in terms of the relation between the input and output of a
linear time-invariant system with zero initial conditions.
4. nyquist diagram and bode diagram (frequency domain)
nyquist diagram: use jw to replace s in transfer function. Nyquist stability criterion: when w
change from 0 to ∞, the number of encirclements of point at (-1,j0) is N, Counterclockwise is
positive, the number of poles in the right half plane is p, when z=p-2n equal to 0, system is stable.
z is the number of positive real root of characteristic equation.
bode diagram:
5. PID control/ controller
PID stands for Proportional, Integral, Derivative.
PID control provides a continuous variation of output within a control loop feedback mechanism
to accurately control the process, removing oscillation and increasing efficiency.
proportional control is used to minimize the oscillation characteristic of on/off control
PID control is used for a variety of process variables such as; Temperature, Flow and Pressure.
the relation between input and output of PID controller is
u(t)=kp[e(t)+1/TI∫e(t)dt+TD*de(t)/dt] from 0 to t
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：控制工程
机电传动控制（英文要点·复习资料·motor driving and robots）
核心内容
1. stepper motors and servo motors, AC/DC
the motor can be used in robot, its wheels, legs, tracks, arms, fingers
·In a continuous DC motor, application of power causes the shaft to rotate continually. The shaft
stops only when the power is removed.
·In a stepping motor, applying power causes the shaft to rotate a few degrees, then stop.
Continuous rotation of the shaft requires that the power be pulsed to the motor. they are also
the easiest to use. open loop control, cheap
·the servo motor in typical cases combines a continuous DC motor with a “feedback loop” to
ensure accurate positioning. There are many, many types of servo motors; a common form is the
kind used in radio-controlled cars and planes.
2. motor driving in robot
3. thesis
design of a robot, focus on the application and motor choosing. my thesis is about the Unmanned
Aerial Vehicle(UAV), normally it’s endurance time is short, about half hour, to make it can work
for a long time, I design a system with a car carring battery for the UAV. I design the structure and
the control flow chart, also I chose DC motor for the plane and car, because they are easy to
control and cheap.
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：机电传动控制
机器人技术基础（英文要点·复习资料）
核心内容
1. definition of robot
A robot is a machine—especially one programmable by a computer— capable of carrying out a
complex series of actions automatically. Robots can be guided by an external control device or
the control may be embedded within. Robots may be constructed in a human form, but most
robots are machines designed to perform a task with other forms like a car or just an arm.
2. types of robots, such as and the techniques in robots
·industrial robots: are widely used in automobile manufacturing, machinery processing, such as
welding robot and many kinds of robotic arm for assembly.
·service robot: home service robot can do some housework. Many of them have human forms,
which make them looked more humanized.
·medical robot: Da Vinci surgical robot can help doctor have a remote, precise operation. Some
can provide health-care service.
3. the attitude control of manipulator by using Matrix transformation. it consists of joints and
links, joints provide relative motion, the types of joints include linear and rotary, each joint
provides a degree of freedom.
Rotate α around the x axis， Ф y; ϴ z
Kinematic analysis, normally a rotaion consists of several basic rotation, so we have basic
rotation matrixs.
1st we have translation transformation so we got the position, then rotation transformation to
get the attitude.
4. how to achieve the function
·sensor: testing technology
·actuator: machine design and drive system
·controller: control system, the principle of micro-controller
·software programme: based on C language
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：机器人技术基础
工程热力学（英文要点·复习资料）
核心内容
focus more on the basic theory
1. Zeroth law
if two system are each in thermal equilibrium with a third, they are also in thermal equilibrium
with each other. based this law, we can measure the temperature.
2. First law
the internal energy of an isolated system is constant. energy can be transformed but cannot be
created or destoryed. so without input energy machine won’t produce work.
3. Second law
the conversion of heat into useful work without and side effect is impossible. it describes the
direction of the heat transfer.
4. Carnot cycle
T1=T2=Thigh T3=T4=Tlow
Isebtropic process: there is no heat exchange between the system and the surroundings
Idothermal process: the heat and volume is changed, while the tempurature remains the same.
S-entropy: a measure of the unavailable energy in a closed thermodynamic system that is also
usually considered to be a measure of the system's disorder.
·Carnot heat engine
Process
Change
in
Internal Energy
Work
Interaction
Heat
Interaction
Process
1-2
CV(T2-T1)
CV(T1-T2)
0
absorb heat; volume expand
doing
work
on
the
surroundings
Process
2-3
0
RTB ln(V3/V2)
RTB ln(V3/V2)
no heat change between
system and surrondings
adiabatic expansion,
decrese temperature
Process
3-4
CV(T4-T3)
CV(T3-T4)
0
surroundings do work on the
system, heat to be released
temperature ramain
Process
4-1
0
RTAln(V1/V4)
RTA ln(V1/V4)
No heat exchange occurs
Adiabatic compression
raise temperature
·heat pump
engineering thermodynamics and heat transfer
how to calculate and solve the actual problem
1. thermal conduction
the transfer of heat by movement of microscopic particles within a bodt or objects in touch. heat
spontaneously flows from a hotter to a colder body.(without external influence)
Example: the wall of a house
formula
2. thermal convection
the transfer of heat from one place to another by the movement of fluids, usually liquids and
gases.
Example: electrical fan in summer
3. thermal radiation
process by which energy, in the form of electromagnetic radiation, is emitted by a heated surface
in all directions.
thermal radiation does not require an intervening medium to carry it.
all matter with a temperature greater then absolute 0 emits thermal radiation.
· black body: absorbs all the radiation and radiates. a ball with a small hole can be considered as
a black body.
Example: The heating of the Earth by the Sun is an example of transfer of energy by radiation.
Heating in winter
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：工程热力学
液压与气压传动（英文要点·复习资料）
核心内容
Mainly about hydraulic transmission, but at first we learned a little about hydromechanics
1. Hydrostatics
The pressure at all points in the same horizontal plane is the same.
2. Hydrodynamics
·The continuity equation Q=Av=constant
·Bernoulli equatoin
Bernouli principle: an increase in the speed of a fluid occurs with a decrease in pressure or in the
fluid’s potential energy.
It is valid only for incompressible flow.
·the momentum equation
According to the Newton’s second low, any change in momentum of fluid will be due to the
action of external forces acting on the fluid.
)
(
1
1
2
2
v
v
Q
F
−
=
β is correction factor of momentum, for laminar flow is 1.33, for turbulent flow is 1.
Q=vA
3. Laminar and turbulent flow
Reynolds number: the ratio of inertial force to viscous forces.
Turbulent flow: occurs at high Reynolds numbers and is dominated by inertial forces, which tend
to produce flow instabilities.
Laminar flow: occurs at low Reynolds numbers and is dominated by viscous forces. The character
of laminar flow is smooth, constant fluid motion.
4. head loss
It is usually measured in metres head of the fluid
·Overall head loss in a pipe is affected by a number of factors which include the viscosity of the
fluid, the size of the internal pipe diameter, the internal roughness of the inner surface of the
pipe, the change in elevation between the ends of the pipe and the length of the pipe along
which the fluid travels.
Normally we use this formula to calculate head loss in a circular tube for laminar flow:
where:
hf = head loss (m)
f = friction factor
L = length of pipe work (m)
d = inner diameter of pipe work (m)
v = velocity of fluid (m/s)
g = acceleration due to gravity (m/s²)
For laminar flow
·Local head loss
g
v
hj
2
2
=
the local loss coefficient, is related to Reynolds number and the local pipe shape.
5. Structure & working principle of hydraulic system
A typical hydraulic system is consist of hydraulic pump, cylinder/motor, many valves and other
auxiliary element for example, tank, piping, and pressure gage.
Hydraulic pump is a mechanical source of power the converts mechanical power into hydraulic
energy.
Hydraulic cylinder is a hydraulic actuator that is used to give a external work.
Hydraulic valves include flow control valves, pressure control valves, direction control valves
and so on, which are control components in a hydraulic system.
·pump
·cylinder
·Pilot operated check valve/ forward flow valve
·reversing valve
·pressure unloading valve & pressure reducing valve
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：液压与气压传动
电工技术与电子技术基础（英文要点·复习资料）
核心内容
Analog circuit and basic of circuit analysis & digital circuit
1. Semiconductor device/ P-N junction/ Diodes
The application of diodes:
·a rectifier circuit to reserve the direction of the current.
·zener diodes are used as voltage-regulator diode. When the voltage is higer than the zener
voltage, the current will go through the diode to keep the voltage nearly constant but do not
damage the diode.
2. Transistor
Use two junctions betweeen two semiconductor types, n-type & p-type.
Consist of emitter, collector and base.
The characteristic diagram of transistor
·Commen-collector amplifier
The input and output signals are in the same phase, the gain is approximately 1, it means the
output changes in the same way with the input. So it is also called emitter follower. But the
power gain is much greater than 1, so it can significantly amplify the power of the circuit.
1
)
1(
+
+
=
=
L
E
E
i
o
i
R
R
R
I
I
A
And the input resistance is relative high and the output resistance
is really small(so when the load change, the change of output voltage will be very small).
i
B
B
i
R
R
R
R
//
//
2
1
=
It can be used as Buffer and isolation circuit.
3. Circuit analysis
kirchhoff’s current law and voltage law
KCL: at any junction in an circuit, the sum of currents flowing into that node is equal to the sum
of currents flowing out of that node.
KVL: the directed sum of the electrical potential differences/voltage around any closed network is
zero.
4. Logical relationships
5. Karnaugh map method --- K-map
reduced method of a Karnaugh map
6. Sequential logic circuit
As for sequential logic circuit, they should have the parts for memories of the former state. The
flip-flop has two steady states and can be used to store state information.
·RS flip-flop
R=1, set. S=1, reset.
·edge JK trigger
7. Decoder
3 to 8-line decoder
It takes 3 binary inputs and activates one of the eight outputs.
When the enable port is low, then input is invalid and all output is 0.
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：电工技术与电子技术基础
微机原理及应用（英文要点·复习资料）
核心内容
1. Basic concept
Bit - a sigal binary digit, a “0” or a “1”
Byte - an eight- bit word
Word - 2 bytes
2. Von Neumann Architecture
The signal bus can only access one of the two classes of memory at a time.
Programm memory and data memory are in the same memory.
3. The representation of machine number
It’s mainly related to binary, hexadecimal and decimal.
The computer machine number has 3 methods to represent a binary signed number: true
code(-127,127), ones’ complement, two’s complement.
If we want to subtract 1 from 8, we can use two’s complement to computing, that is much easy.
When the highest bit of ture code is “1”, it means the number is negative.
The ones’ complement of positive number is itself, but for negative number, it inverts all bits
except signal bit.
The two’s complement of positive number is still itself, but for negative number, it plus 1.
Two’s complement to ture code: inverting and plus 1.
4. Software architecture of the 8086 micro-processor
·bus interface unit
Provides a full 16 bit data bus and 20 bit address bus. It is responsible for performing all external
bus operation.
·execution unit
Arithmetic logic unit + registers
Flag registers mark the state of the micro-processor / general purpose registers save the data
information.
·instruction system
Machine language: the only language that CPU can directly execute, written in machine code.
Assembly language
·Interrupt
An interrupt is a signal from a device attached to a computer or from a program within the
computer that requires the operating system to stop and figure out what to do next.
参考：来源：aps复习资料.rar / up自己一点点整理的复习资料.pdf｜专业：机械工程｜课程：微机原理及应用