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APS出来好几天出来，今天才得空写篇经验帖，感谢ABCDV上各位前辈的帮助。
复习时间磨磨蹭蹭一周（抵不住微博诱惑）
笔试 一题PID，一题仪表精度&准确度分析
面试刚开始问问为什么去德国啊，去那个城市学什么啊，家里准备多少钱啊，木有自我介绍然后进入正题，问了4门，其中两门分数最低，两门最高，全是大三的。选修课也问到了，所以复习面还是要广些。
你认为重要的他不一定会考，最尴尬就是问你偏的选修课，而你恰好酱油（我就遇到了。。。），不过问的科目都是与专业有关的。
*下面附上英文词汇*
The course mainly introduce the principle/theory of ** and its application in real life.
电路，模电，数电Circuit Theory/Analog/Digital Circuit
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow.
Transistors(base/emit/collect)
MOS(metal oxide semiconductor)
PN-Junction(Diodes With Unidirectional Conductivity)
V-I特性 V-I characteristic
放大系数 magnification coefficient
Analogue electronics are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two different levels.
Digital Circuit: binary encoding is used: the more positive value represents a binary '1' and a value near the ground potential, 0 V represents a binary '0'.
Logic gates (AND, OR, NOT)
CMOS vs TTL-power dissipation
各种电子器件
Current/Voltage source, Inductance, electrode, electric charge, resistance, Diode, amplifier, semiconductor, electric field, trigger, square/sine wave, power, saturation region, frequency, rectification, amplitude, filter, gate circuit, feedback, cut-off, AC(alternating current), ADDC, Channel, Truth table, Karnaugh map,
KCL (all the currents at a node must add to 0)
KVL(the voltage around a closed loop of wires is 0)
Thevenin/Norton theorem
微机原理Principle of Microcomputer(Intel MCS-51)
Decimal, Binary, C#, ASM(Assemble Language)
Microcomputer structure: RAM(Random access memory)，ROM(read only memory),BUS(AB,DB,CB),I/O(parallel/serial interface, Peripherals(AD/DA converter, switch), interrupt logic, timer, etc.
传感器原理Sensor: A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. A thermocouple converts temperature to an output voltage which can be read by a voltmeter.
结构Structure of measurement systems
1. Sensing element
Thermocouple where millivolt e.m.f. depends on temperature
Strain gauge where resistance depends on mechanical strain
2. Signal conditioning element
Amplifier which amplifies millivolts to volts
Deflection Bridge which converts an impedance change into a voltage change
3. Signal processing element
(ADC) which converts a voltage into a digital form for input to a computer
4. Data presentation element
Static Characteristic:
Rang, Linearity, Sensitivity, Resolution/Discrimination, Zero drift
Dynamic Characteristic:
Time constant, Damping ratio
传感器类型：
Resistive/Capacitive/Inductive/Piezoelectric/Thermocouple/Thermistor/Optical Sensor
Parameter:
Displacement/Velocity/Temperature/Pressure/Humidity/Level/Mass/
Flow rate------Current/Voltage----ADC----LED
检测仪表：
Accuracy class, relative err,
压力计pressure gage(resistive/inductive/capacitive)
差压式液位计differential pressure type level gauge(buoyancy/capacitance)
节流式流量计Throttle flow meter(buyance/turbine)
热电偶温度计thermocouple thermometer
虚拟仪器 virtual instrumentVirtual instrumentation is the use of customizable software and modular measurement hardware to create user-defined measurement systems, called virtual instruments.
Labview (Graphical programming)
采集卡采集数据Data acquisition(data capture card)
用户面板 create user interface
编译 compile
虚拟仪器与传统仪器的比较
Traditional hardware instrumentation systems are made up of pre-defined hardware components, such as digital multimeters and oscilloscopes that are completely specific to their stimulus, analysis, or measurement function. Because of their hard-coded function, these systems are more limited in their versatility than virtual instrumentation systems. The primary difference between hardware instrumentation and virtual instrumentation is that software is used to replace a large amount of hardware. The software enables complex and expensive hardware to be replaced by already purchased computer hardware.
现场总线Fieldbus
Fieldbus is an industrial network system for real-time distributed control. It is a way to connect instruments in a manufacturing plant.
A complex automated industrial system — such as manufacturing assembly line — usually needs an organized hierarchy of controller systems to function. In this hierarchy there is usually a Human Machine Interface (HMI) at the top, where an operator can monitor or operate the system. This is typically linked to a middle layer of programmable logic controllers (PLC) via a communications system (e.g. Ethernet). At the bottom of the control chain is the fieldbus that links the PLCs to the components that actually do the work, such as sensors, actuators, switches, valves and contactors.
几种现场总线
Foundation Fieldbus/Profibus/Lon work
Structure: Operation Station/Ethernet/Fieldbus/Instruments
集散系统 Distributed Control System
A distributed control system (DCS) refers to a control system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system. The entire system of controllers is connected by networks for communication and monitoring.
组成：分散过程控制装置，操作管理装置， 通信系统
也就是：Distributed control device/operation management device/communication system
DCS控制系统的而一个例子——设定值闭环压力控制
DCSs are connected to sensors and actuators and use setpoint control to control the flow of material through the plant. The most common example is a setpoint control loopconsisting of a pressure sensor, controller, and control valve. Pressure or flow measurements are transmitted to the controller, usually through the aid of a signal conditioning input/output (I/O) device.
组态configuration
控制功能块
Central to the DCS model was the inclusion of control function blocks，which can realize the execution of PID algorithms.
PLC(programmable logic controller)
PLC的特点PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements which connect PLC to actuators and sensors, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact.
一直扫描A PLC program is generally executed repeatedly as long as the controlled system is running.
扫描机理The status of physical input points is copied to an area of memory accessible to the processor, sometimes called the "I/O Image Table". The program is then run from its first instruction rung down to the last rung.
Communication
PLCs have built in communications ports, usually 9-pin RS-232. Other options include various fieldbuses such as FF or Profibus.
Programming
PLC programs are typically written in a special application on a personal computer, then downloaded by a direct-connection cable or over a network to the PLC. The program is stored in the PLC either in RAM or some other non-volatile flash memory.
PLCs can be programmed using standards-based programming languages, usually Sequential Function Charts and Ladder Charts. |
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发表于 2011-12-16 15:55:30
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发表于 2012-2-3 22:46:59
