英文文献及其翻译

步进电机的知识

什么是步进电机：

步进电机是一种把电脉冲转化为角位移的执行机构。通俗的说：当驱动程序收到一个步进脉冲信号，将驱动步进电机轴旋转一个固定的角度（步进角）。您可以通过控制脉冲个数来控制角位移，从而达到准确定位的目的;同时，你可以通过控制脉冲频率来控制电机的旋转速度和加速度，实现速度控制的目的。

步进电机的种类：

步进电机分为三种：永磁式（PM），反应式（VR）和混合式（HR）永磁式步进电机一般为两相，转矩和体积较小，步进角一步7.5度或15度;反应式一般有三相可以实现大转矩输出，步进角一般是1.5度，但噪声和振动大。在欧洲和美洲80个国家已被淘汰;混合式步进是混合了永磁式和反应的优势。它由两相和五相：一般两相的步距角是1.8度，而的五相步距角为0.72度。是使用最广泛的的步进电机。

步进电机允许的最高表面温度

步进电机温度过高首先会的磁性材料退磁，导致转矩降低甚至失步，电机表面温度允许的最大值取决于的磁性材料退磁点;一般来说，磁性材料退磁点在摄氏130度以上有些材料甚至高达摄氏200度高，所以步进电机表面温度在摄氏80-90度是正常的。

步进电机精度为多少？是否累积

一般步进电机的精度为步进角的3-5%，且不累积

如何确定步进电机驱动器直流电源

A.电压确定

混合式步进电机驱动器的电源电压范围较广（比如IM483的供电电压12?48VDC），电源电压通常根据电机的转速和响应要求来选择。如果要求较快的运行速度较高的响应速度就选用较高的电压，但注意电源电压的峰值不能超过驱动器的最大输入电压，否则可能会损坏驱动器。

B.电流确定

电源电流一般根据输出相电流I来确定。如果采用线性电源，电源电流一般可取I的1.1?1.3倍;如果采用开关电源，电源电流一般可取I的1.5?2.0倍。

步进电机的主要特性

在步进电机关机时要确保没有脉冲信号，当电机运行时

如果加入适当的脉冲信号，它会转过一定的角度（称为步距角是）。转速与脉冲频率成正比。

2龙式步进电机步距角7.5度，旋转360度，需要48个脉冲来完成。

3步进电机具有快速启动和停止的优良特性。

4只要改变脉冲，可以很容易地改变电机轴旋转的方向。

因此，目前的打印机，绘图仪，机器人设备以步进电机作为动力核心。

步进电机控制的例子

我们以四相单极步进电机为例：

四个相绕组引出四个相和两个公共线（连接到正极）。一相接地。会被激发，。我们使用四相八拍控制，即第1阶段第2阶段交替反过来，会提高分辨率。步距角0.9°，可以转移到控制电机励磁是为了转移如下：

如果电机反转的要求，传输的激励信号可以逆转的。2控制方案

控制系统框图如下

该方案采用AT89S51的主要控制装置。它是与AT89C51兼容，但也增加了SPI接口和看门狗模块，这不仅使调试变得更容易，也更稳定。单片机程序主要用于现场信号的采集和通过步进电机的运转来计算的方向和速度信息。然后将信息发送到CPLD。

CPLD使用EPM7128SLC84-15，ALTERA公司的MAX7000系列可编程逻辑器件EPM7128。具有高阻抗，电可擦除等特点，可用单位数为2500单位，工作电压+5 V CPLD接收脉冲后转换为相应的控制信号输出到步进电机驱动器，从微控制器发送的信息。输入后把控制信号发送到驱动电机绕组，以达到有效控制电机的目的。 2.1为电机驱动器的硬件结构

电机驱动器通过下面的电路来实现：

R1?R8的电阻值为320Ω。R9-R12的电阻值为2.2KΩ。Q1?Q4作为达林顿401A，Q5-Q8为S8550。J1，J2和步进电机连接到六个接口。

步进电机优点和缺点

优势

1。电机的旋转角度与脉冲数成正比;

2。当电机停转为最大转矩（当绕组励磁时）;

3。由于每一步准确度为百分之三到五，而且误差不会累积到下一步，因而具有更好定位精度和重复定位精度;

4。优良的启动和制动特性_;

5。没有电刷，可靠性高，电机的寿命只是取决于电机轴承;

6。电机_仅由输入脉冲数决定，可用于开环控制，这使得电机和控制结构确定相对简单

系统成本

7。只是负载直接连接到电机轴也可以极其缓慢旋转

8。速度与的脉冲频率成正比，因此，有相对较宽的调速范围

缺点

1。如果没有适当的控制，容易共振;

2。高速操作难度较大

3。难以获得大转矩

4。没有体积小，重量轻，能耗低，效率高等方面优势

5。过载时会破坏同步性，工作时会发出时较大的振动和噪音

步进电机驱动要求

（1）为了满足速度迅速上升或下降的要求，波形应当尽可能接近矩形

以释放回路电流流，绕组两端的反电动势，加速电流衰减

（2）具有较高功率和效率

步进电机驱动器，把输入的脉冲信号转化为角位移，每当控制系统发出一个脉冲信号，步进电机驱动就旋转一个步距角，步进电机的速度与的脉冲信号频率成正比，因此，通过控制脉冲信号频率，就可以精确控制电机转速步进脉冲数决定准确连接为电机步进电机驱动器有很多，我们应该根据功率采取的合理的方式选择驱动器

最新的技术发展

国内和国际上对于驱动技术的研究十分活跃，高性能子驱动电路可以细分成几千部分甚至任意细分，现在已经能够做到通过复杂的计算统一步距角，大大提高了步进电机的脉冲分辨率，减少或消除振动，噪声和转矩波动，步进电机有了更多“类伺服”功能

实际作用：步距角细分驱动器出现之前，用户需要选择不同的相来获取不同的步进电机步距角，以满足自己的要求，如果使用细分驱动器，用户可以通过更改驱动器号段，来改变实际的步距角，相数对实际步距角的作用几乎可以忽略不计

AT89C51的介绍

描述

AT89C51是一个拥有4K字节FLASH编程功能和可擦除只读储存器的低功耗，高性能CMOS8位微机（PEROM）。该设备是采用Atmel的高密度非易失性内存技术并与工业标准的的MCS-51指令集和引脚兼容。芯片上的Flash允许程序存储器通过系统或由传统的非易失性存储器编程重新编程。通过把一个多功能8位CPU与一个单一的芯片上的Flash相结合的，Atmel的AT89C51是一个功能强大微型计算机为许多嵌入式控制程序提供了高度灵活和成本效益的解决方案。

功能特点

AT89C51具有以下功能：4K字节的Flash，128字节RAM，32 I / O口，两个16位定时器/计数器，一个五向量2级中断机构，一个全双工串行口，芯片振荡器和时钟电路。此外，AT89C51支持频率为0的静态逻辑运算，并支持两种节电模式。空闲模式时CPU停止工作，同时允许RAM，定时器/计数器，串口和中断系统继续运作。掉电模式保存RAM的内容，但冻结振荡器，禁用所有其他芯片功能，直到硬件复位。

引脚描述

VCC：电源电压

GND：地

端口0：

端口0是一个8位漏极开路双向I / O端口。作为一个输出端口，每个引脚可以驱动8个TTL 输入端。当1写入端口0引脚，引脚可作为高阻输入端.端口0也可以设定成地址/数据在访问外部程序和数据存储器时的总线。在这种模式下，口0内部上拉.电阻口0 在Flash编程期间也可以收到代码字节，输出程序改变的代码字节。程序改变期间还要外部上拉电阻

端口1

端口1是一个具有内部上拉电阻的8位双向I / O端口端口1输出缓冲器可以驱动四个TTL 输入.当1被写入端口1它们被内部上拉电阻上拉为高电平并可以用作输入口。作为输入口时，由于内部上拉电阻的作用，引脚被外部信号拉低时输出一个电流，flash编程和校验时端口1也会接收到低地址信号。

端口2

端口2是一个具有内部上拉电阻的8位双向I / O端口。端口2输出缓冲器可以驱动四个TTL 输入。当1S写入端口2引脚他们被内部上拉电阻拉到高电平，并可以用作输入口。作为输入口时，由于内部上拉电阻的做用，端口2引脚被外部信号拉至低电平时，将输出电流，端口2在访问使用16位地址的外部数据存储器时发出的高位地址字节。在此应用中，它采用强大的内部上拉电阻，发光1S。在访问使用8位地址的外部数据存储器时，端口2也会收到一些高八位地址信号或者控制信号。

端口3

端口3是一个具有内部上拉电阻的8位双向I / O端口。端口3输出缓冲器可以驱动四个TTL 输入。当1S被写入端口3的引脚，他们被内部上拉电阻拉到高电平，并可以用作输入

口。作为输入口时，由于内部上拉电阻的做用，端口2引脚被外部信号拉至低电平时，将输出电流。端口3还为A T89C51提供各种特殊功能，如下：

RST

复位输入引脚。震荡器运行时，两个运行周期的高电平将使设备复位。

ALE / PROG

在访问外部存储器时地址锁存使能输出脉冲锁存的低八位地址。该引脚也是程序在Flash 编程时的PROG。正常运行时ALE以恒定的速率发出振荡频率的1/6的脉冲信号，可用作外部时钟或定时。但是请注意，，在每次访问外部数据存储器都有一个ALE脉冲跳过。。

如果需要，可以通过把0 SFR置位为8EH来禁用ALE。此时，ALE仅执行MOVX或MOVC 指令。如果单片机在执行外部的工作，应将ALE设置为禁用。

PSEN

程序储存允许输出是外部程序存储器的读选通信号，当A T89C51由外部程序存储器读取指令时，每个机器周期两次PSEN 有效，即输出两个脉冲。在此期间，当访问外部数据存储器时，这两次有效的PSEN 信号不出现。

EA/ VPP

外部访问允许。EA必须绑到GND才能使设备开始在0000H到FFFFH位取代码。但是请注意，如果锁存位1被编程，EA将锁存位置上复位。若EA为高电平则单片机执行内部程序。在Flash编程时，也可以使用使用12V编程电压

VCC

XTAL1：震荡器反相放大器及内部时钟发生器的输入端。

XTAL2：震荡器反相放大器的输出端。

时钟振荡器的特性

时钟振荡器是可以设置为内部振荡器的反相放大器XTAL1和XTAL2分别为其出入端和输出端，如图1所示。石英晶体或陶瓷谐振器都可以作为其材料。如图2所示要想通过外部时钟来驱动它，XTAL1工作时XTAL2应悬空。对外部时钟信号的占空比没有特殊要求，因为外部时钟信号是通过一个2分频触发器后作为内部时钟信号的，但最小高电平持续时间和最大的低电平持续时间应该符合要求。

内部振荡电路外部振荡电路

闲散模式

在闲散模式下，CPU停止工作，而所有其他元件依然处于工作状态。该模式是通过软件控制的。这种模式下，片上RAM和所有特殊功能寄存器的内部数据不变。该模式可以由任何可用的终止指令或者硬件重置来终止当由硬件复位来终止闲散工作模式时，中央处理器CPU 通常是从激活空闲模式那条指令的下一条开始继续执行程序的，要完成内部复位操作，硬件复位脉冲要保持两个机器周期有效，在这种情况下，内部禁止中央处理器CPU访问片内RAM，而允许访问其他端口，这是为了避免可能对端口产生的意外写入：激活空闲模式的指令后面的一条指令不应是一条对端口或外部存储器的写入指令。

掉电模式

在掉电模式下，振荡器停止运行，断电指令是最后一条要执行的指令。片上RAM和特殊功能寄存器保持原值，直到掉电模式终止。终止掉电唯一的方式是硬件复位。复位将重置SFR，但不改变RAM的内容。复位不能被激活，直到VCC恢复到其正常水平，以确保有足够长的时间使振荡器重新启动并稳定。。

Knowledge of The Stepper Motor

What is a stepper motor：

Stepper motor is a kind of electrical pulses into angular displacement of the implementing agency.Popular little lesson: When the driver receives a step pulse signal, it will drive a stepper motor to set the direction of rotation at a fixed angle (and the step angle). You can control the number of pulses to control the angular displacement, so as to achieve accurate positioning purposes; the same time you can control the pulse frequency to control the motor rotation speed and acceleration, to achieve speed control purposes.

What kinds of stepper motor sub-：

In three stepper motors: permanent magnet (PM), reactive (VR) and hybrid (HB) permanent magnet stepper usually two-phase, torque, and smaller, step angle of 7.5 degrees or the general 15 degrees; reaction step is generally three-phase, can achieve high torque output, step angle of 1.5 degrees is generally, but the noise and vibration are large. 80 countries in Europe and America have been eliminated; hybrid stepper is a mix of permanent magnet and reactive advantages. It consists of two phases and the five-phase: two-phase step angle of 1.8 degrees while the general five-phase step angle of 0.72 degrees generally. The most widely used Stepper Motor.

What is to keep the torque (HOLDING TORQUE)

How much precision stepper motor? Whether the cumulative：

The general accuracy of the stepper motor step angle of 3-5%, and not cumulative.

Stepper motor to allow the minimum amount of surface temperature

Stepper motor to allow the minimum amount of surface temperature：

Stepper motor causes the motor temperature is too high the first magnetic demagnetization, resulting in loss of torque down even further, so the motor surface temperature should be the maximum allowed depending on the motor demagnetization of magnetic material points; Generally speaking, the magnetic demagnetization points are above 130 degrees Celsius, and some even as high as 200 degrees Celsius, so the stepper motor surface temperature of 80-90 degrees Celsius is normal. How to determine the stepper motor driver DC power supply：

A. Determination of the voltage

Hybrid stepping motor driver power supply voltage is generally a wide range (such as the IM483 supply voltage of 12 ~ 48VDC), the supply voltage is usually based on the work of the motor speed and response to the request to choose. If the motor operating speed higher or faster response to the request, then the voltage value is high, but note that the ripple voltage can not exceed the maximum input voltage of the drive, or it may damage the drive.

B. Determination of Current

Power supply current is generally based on the output phase current drive I to determine. If a linear power supply, power supply current is generally preferable 1.1 to 1.3 times the I; if we adopt the switching power supply, power supply current is generally preferable to I, 1.5 to 2.0 times.

The main characteristics of stepping motor：

A stepper motor drive can be added operate pulse drive signal must be no pulse when the stepper motor at rest, such as

If adding the appropriate pulse signal, it will to a certain angle (called the step angle) rotation. Rotation speed and pulse frequency is proportional to.

2 Dragon step angle stepper motor version is 7.5 degrees, 360 degrees around, takes 48 pulses to complete.

3 stepper motor has instant start and rapid cessation of superior characteristics.

Change the pulse of the order of 4, you can easily change the direction of rotation.

Therefore, the current printers, plotters, robotics, and so devices are the core of the stepper motor as the driving force.

Stepper motor control example

We use four-phase unipolar stepper motor as an example. The structure shown in Figure 1: Four four-phase winding leads (as opposed to phase A1 A2 B1 phase phase B2) and two public lines (to the power of positive). The windings of one phase to the power of the ground. So that the windings will be inspired. We use four-phase eight-beat control, ie, 1 phase 2 phase alternating turn, would enhance resolution. 0.9 ° per step can be transferred to control the motor excitation is transferred in order as follows:

If the requirements of motor reversal, the transmission excitation signal can be reversed. 2 control scheme

Control system block diagram is as follows

The program uses AT89S51 as the main control device. It is compatible with the AT89C51, but also increased the SPI interface and the watchdog module, which not only makes the debugging process becomes easy and also more stable. The microcontroller in the program mainly for field signal acquisition and operation of the stepper motor to calculate the direction and speed information. Then sent to the CPLD.

CPLD with EPM7128SLC84-15, EPM7128 programmable logic device of large-scale, for the ALTERA company's MAX7000 family. High impedance, electrically erasable and other characteristics, can be used for the 2500 unit, the working voltage of +5 V. CPLD receives information sent from the microcontroller after converted to the corresponding control signal output to the stepper motor drive. Put the control signal drives the motor windings after the input, to achieve effective control of the motor. 2.1 The hardware structure of the motor drive

Motor drive using the following circuit:

R1-R8 in which the resistance value of 320Ω. R9-R12 resistance value 2.2KΩ. Q1-Q4 as Darlington D401A, Q5-Q8 for the S8550. J1, J2 and the stepper motor connected to the six-lead。Advantages and disadvantages of stepper motor

Advantages

1. The motor rotation angle is proportional to the number of pulses;

2. When the motor stopped with a maximum torque (when the winding excitation time);

3. Since the accuracy of each step in the three per cent to five per cent, and the error will not accumulate to the next step and thus has better positional accuracy and repeatability of movement;

4. Excellent response from the stop and reverse;

5. In the absence of brush, high reliability, it just depends on the life of the motor bearing life;

6. Motor response only determined by the number of input pulses, which can be used open loop control, which makes the motor and control structure can be relatively simple

System cost

7. Just load directly connected to the motor shaft can also be extremely slow synchronous rotation.

8. Speed is proportional to the pulse frequency, and thus a relatively wide speed range. Shortcomings

1. If not properly controlled prone to resonance;

2. Difficult operation to a higher speed.

3. Difficult to obtain high torque

4. There is no advantage in terms of volume weight, low energy efficiency.

5. Over load will destroy the synchronization, the work will be issued when high-speed vibration and noise.

Stepper motor drive requirements

(1) to provide fast rise and fall of current speed, the current waveform as close as possible rectangle. For the period ended with the release of the loop current flow, to reduce the winding ends of the back electromotive force, to accelerate the current decay.

(2) rhyme with higher power and efficiency.

Stepper motor driver, which is the control pulse signal emitted into the angular displacement of the stepper motor, or: the control system sends a pulse signal each through the stepper motor drive to rotate a step angle. That is the stepper motor speed is proportional to the frequency and pulse signals. Therefore, the frequency control pulse signal, to be precise motor speed control; control the number of step pulses to connect the motor accurately. Stepper motor drive there are many, we should take a reasonable choice of power requirements of the drive, the following were introduced various types of typical drive.

The latest technological developments

Domestic and international research on the sub-drive technology is very active, high-performance sub-driver circuit can be broken down into thousands or even any subdivision. Now able to do complicated calculations to make after the breakdown of uniform step angle, which greatly improves the resolution of stepper motor pulses, reduce or eliminate the vibration, noise and torque ripple, the stepper motor is more "class server" feature.

The actual role of step angle: in the absence of sub-drive, the user select a different number of phases depends mainly on the stepper motor to meet their own requirements on the step angle，If you use the sub-drive, the user can change the drive number of segments, can dramatically change the actual step angle stepper motor 'phases' of change in the role of the actual step angle is almost negligible. Introduction of AT89C51

Description

The A T89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications.

Function characteristic

The A T89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.

Pin Description

VCC：Supply voltage.

GND：Ground.

Port 0：

Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as highimpedance inputs.Port 0 may also be configured to be the multiplexed loworder address/data bus during accesses to external program and data memory. In this mode P0 has internal pullups.Port 0 also receives the code bytes during Flash programming,and outputs the code bytes during programverification. External pullups are required during programverification.

Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pullups.The Port 1 output buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups.Port 1 also receives the low-order address bytes during Flash programming and verification.

Port 2

Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers can sink/source four TTL inputs.When 1s are written to Port 2 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled low will source current, because of the internal pullups.Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses. In this application, it uses strong internal pullupswhen emitting 1s. During accesses to external data memory that use 8-bit addresses, Port 2 emits the contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.

Port 3

Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port 3 output buffers can sink/source four TTL inputs.When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups.Port 3 also serves the functions of various special features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and verification.

RST

Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.

ALE/PROG

Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external Data Memory.

If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode. PSEN

Program Store Enable is the read strobe to external program memory.When the AT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.

EA/VPP

External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset.EA should be strapped to VCC for internal program executions.This pin also receives the 12-volt programming enable voltage(VPP) during Flash programming, for parts that require12-volt VPP.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively,of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1.Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2.There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.

Figure 1. Oscillator Connections Figure 2. External Clock Drive Configuration

Idle Mode

In idle mode, the CPU puts itself to sleep while all the onchip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset.It should be noted that when idle is terminated by a hard ware reset, the device normally resumes program execution,from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory.

Power-down Mode

In the power-down mode, the oscillator is stopped, and the instruction that invokes power-down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power-down mode is terminated. The only exit from power-down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.

英文文献翻译

中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。

外文翻译 - 英文

The smart grid Smart grid is the grid intelligent (electric power), also known as the "grid" 2.0, it is based on the integration, high-speed bidirectional communication network, on the basis of through the use of advanced sensor and measuring technology, advanced equipme nt technology, the advanced control method, and the application of advanced technology of decision support system, realize the power grid reliability, security, economic, efficient, environmental friendly and use the security target, its main features include self-healing, incentives and include user, against attacks, provide meet user requirements of power quality in the 21st century, allow all sorts of different power generation in the form of access, start the electric power market and asset optimizatio n run efficiently. The U.S. department of energy (doe) "the Grid of 2030" : a fully automated power transmission network, able to monitor and control each user and power Grid nodes, guarantee from power plants to end users among all the nodes in the whole process of transmission and distribution of information and energy bi-directional flow. China iot alliance between colleges: smart grid is made up of many parts, can be divided into:intelligent substation, intelligent power distribution network, intelli gent watt-hourmeter,intelligent interactive terminals, intelligent scheduling, smart appliances, intelligent building electricity, smart city power grid, smart power generation system, the new type of energy storage system.Now a part of it to do a simple i ntroduction. European technology BBS: an integration of all users connected to the power grid all the behavior of the power transmission network, to provide sustained and effective economic and security of power. Chinese academy of sciences, institute of electrical: smart grid is including all kinds of power generation equipment, power transmission and distribution network, power equipment and storage equipment, on the basis of the physical power grid will be modern advanced sensor measurement technology, network technology, communication

关于力的外文文献翻译、中英文翻译、外文翻译

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计算机网络-外文文献-外文翻译-英文文献-新技术的计算机网络

New technique of the computer network Abstract The 21 century is an ages of the information economy, being the computer network technique of representative techniques this ages, will be at very fast speed develop soon in continuously creatively, and will go deep into the people's work, life and study. Therefore, control this technique and then seem to be more to deliver the importance. Now I mainly introduce the new technique of a few networks in actuality live of application. keywords Internet Network System Digital Certificates Grid Storage 1. Foreword Internet turns 36, still a work in progress Thirty-six years after computer scientists at UCLA linked two bulky computers using a 15-foot gray cable, testing a new way for exchanging data over networks, what would ultimately become the Internet remains a work in progress. University researchers are experimenting with ways to increase its capacity and speed. Programmers are trying to imbue Web pages with intelligence. And work is underway to re-engineer the network to reduce Spam (junk mail) and security troubles. All the while threats loom: Critics warn that commercial, legal and political pressures could hinder the types of innovations that made the Internet what it is today. Stephen Crocker and Vinton Cerf were among the graduate students who joined UCLA professor Len Klein rock in an engineering lab on Sept. 2, 1969, as bits of meaningless test data flowed silently between the two computers. By January, three other "nodes" joined the fledgling network.

外文翻译computerprogram英文.doc

Computer Program 1 Introduction Computer Program, set of instructions that directs a computer to perform someprocessing function or combination of functions. For the instructions to be carried out, a computer must execute a program, that is, the computer reads the program, and then follow the steps encoded in the program in a precise order until completion. A program can be executed many different times, with each execution yielding a potentially different result depending upon the options and data that the user gives the computer. Programs fall into two major classes: application programs and operating systems. An application program is one that carries out somefunction directly for a user, such as word processing or game-playing. An operating system is a program that manages the computer and the various resources and devices connected to it, such as RAM,hard drives, monitors, keyboards, printers, and modems,so that they maybe used by other programs. Examples of operating systems are DOS, Windows 95, OS\2, and UNIX. 2 Program Development Software designers create new programs by using special applications programs, often called utility programs or development programs. A programmer uses another type of program called a text editor to write the new program in a special notation called a programming language. With the text editor, the programmer creates a text file, which is an ordered list of instructions, also called the program source file. The individual instructions that make up the program source file are called source code. At this point, a special applications program translates the source code into machine language, or object code— a format that the operating system

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(文档含英文原文和中文翻译) 中英文翻译 平面设计 任何时期平面设计可以参照一些艺术和专业学科侧重于视觉传达和介绍。采用多种方式相结合，创造和符号，图像和语句创建一个代表性的想法和信息。平面设计师可以使用印刷，视觉艺术和排版技术产生的最终结果。平面设计常常提到的进程，其中沟通是创造和产品设计。 共同使用的平面设计包括杂志，广告，产品包装和网页设计。例如，可能包括产品包装的标志或其他艺术作品，举办文字和纯粹的设计元素，如形状和颜色统一件。组成的一个最重要的特点，尤其是平面设计在使用前现有材料或不同的元素。 平面设计涵盖了人类历史上诸多领域，在此漫长的历史和在相对最近爆炸视觉传达中的第20和21世纪，人们有时是模糊的区别和重叠的广告艺术，平面设计和美术。毕竟，他们有着许多相同的内容，理论，原则，做法和语言，有时同样的客人或客户。广告艺术的最终目标是出售的商品和服务。在平面

设计，“其实质是使以信息，形成以思想，言论和感觉的经验”。 在唐朝（ 618-906 ）之间的第4和第7世纪的木块被切断打印纺织品和后重现佛典。阿藏印在868是已知最早的印刷书籍。 在19世纪后期欧洲，尤其是在英国，平面设计开始以独立的运动从美术中分离出来。蒙德里安称为父亲的图形设计。他是一个很好的艺术家，但是他在现代广告中利用现代电网系统在广告、印刷和网络布局网格。 于1849年，在大不列颠亨利科尔成为的主要力量之一在设计教育界，该国政府通告设计在杂志设计和制造的重要性。他组织了大型的展览作为庆祝现代工业技术和维多利亚式的设计。 从1892年至1896年威廉?莫里斯凯尔姆斯科特出版社出版的书籍的一些最重要的平面设计产品和工艺美术运动，并提出了一个非常赚钱的商机就是出版伟大文本论的图书并以高价出售给富人。莫里斯证明了市场的存在使平面设计在他们自己拥有的权利，并帮助开拓者从生产和美术分离设计。这历史相对论是，然而，重要的，因为它为第一次重大的反应对于十九世纪的陈旧的平面设计。莫里斯的工作，以及与其他私营新闻运动，直接影响新艺术风格和间接负责20世纪初非专业性平面设计的事态发展。 谁创造了最初的“平面设计”似乎存在争议。这被归因于英国的设计师和大学教授Richard Guyatt，但另一消息来源于20世纪初美国图书设计师William Addison Dwiggins。 伦敦地铁的标志设计是爱德华约翰斯顿于1916年设计的一个经典的现代而且使用了系统字体设计。 在20世纪20年代，苏联的建构主义应用于“智能生产”在不同领域的生产。个性化的运动艺术在俄罗斯大革命是没有价值的，从而走向以创造物体的功利为目的。他们设计的建筑、剧院集、海报、面料、服装、家具、徽标、菜单等。 Jan Tschichold 在他的1928年书中编纂了新的现代印刷原则，他后来否认他在这本书的法西斯主义哲学主张，但它仍然是非常有影响力。 Tschichold ，包豪斯印刷专家如赫伯特拜耳和拉斯洛莫霍伊一纳吉，和El Lissitzky 是平面设计之父都被我们今天所知。 他们首创的生产技术和文体设备，主要用于整个二十世纪。随后的几年看到平面设计在现代风格获得广泛的接受和应用。第二次世界大战结束后，美国经济的建立更需要平面设计，主要是广告和包装等。移居国外的德国包豪斯设计学院于1937年到芝加哥带来了“大规模生产”极简到美国;引发野火的“现代”建筑和设计。值得注意的名称世纪中叶现代设计包括阿德里安Frutiger ，设计师和Frutiger字体大学;保兰德，从20世纪30年代后期，直到他去世于1996年，采取的原则和适用包豪斯他们受欢迎的广告和标志设计，帮助创造一个独特的办法，美国的欧洲简约而成为一个主要的先驱。平面设计称为企业形象;约瑟夫米勒，罗克曼，设计的海报严重尚未获取1950年代和1960年代时代典型。 从道路标志到技术图表，从备忘录到参考手册，增强了平面设计的知识转让。可读性增强了文字的视觉效果。 设计还可以通过理念或有效的视觉传播帮助销售产品。将它应用到产品和公司识别系统的要素像标志、颜色和文字。连同这些被定义为品牌。品牌已日益成为重要的提供的服务范围，许多平面设计师，企业形象和条件往往是同时交替使用。

10kV小区供配电英文文献及中文翻译

在广州甚至广东的住宅小区电气设计中,一般都会涉及到小区的高低压供配电系统的设计.如10kV高压配电系统图,低压配电系统图等等图纸一大堆.然而在真正实施过程中,供电部门(尤其是供电公司指定的所谓电力设计小公司)根本将这些图纸作为一回事,按其电脑里原有的电子档图纸将数据稍作改动以及断路器按其所好换个厂家名称便美其名曰设计(可笑不?),拿出来的图纸根本无法满足电气设计的设计意图,致使严重存在以下问题:(也不知道是职业道德问题还是根本一窍不通) 1.跟原设计的电气系统货不对板,存在与低压开关柜后出线回路严重冲突,对实际施工造成严重阻碍,经常要求设计单位改动原有电气系统图才能满足它的要求(垄断的没话说). 2.对消防负荷和非消防负荷的供电(主要在高层建筑里)应严格分回路(从母线段)都不清楚,将消防负荷和非消防负荷按一个回路出线(尤其是将电梯和消防电梯,地下室的动力合在一起等等,有的甚至将楼顶消防风机和梯间照明合在一个回路,以一个表计量). 3.系统接地保护接地型式由原设计的TN-S系统竟曲解成"TN-S-C-S"系统(室内的还需要做TN-C,好玩吧?),严格的按照所谓的"三相四线制"再做重复接地来实施,导致后续施工中存在重复浪费资源以及安全隐患等等问题.. ............................(违反建筑电气设计规范等等问题实在不好意思一一例举,给那帮人留点混饭吃的面子算了) 总之吧,在通过图纸审查后的电气设计图纸在这帮人的眼里根本不知何物,经常是完工后的高低压供配电系统已是面目全非了,能有百分之五十的保留已经是谢天谢地了. 所以.我觉得:住宅建筑电气设计,让供电部门走!大不了留点位置,让他供几个必需回路的电,爱怎么折腾让他自个怎么折腾去.. Guangzhou, Guangdong, even in the electrical design of residential quarters, generally involving high-low cell power supply system design. 10kV power distribution systems, such as maps, drawings, etc. low-voltage distribution system map a lot. But in the real implementation of the process, the power sector (especially the so-called power supply design company appointed a small company) did these drawings for one thing, according to computer drawings of the original electronic file data to make a little change, and circuit breakers by their the name of another manufacturer will be sounding good design (ridiculously?), drawing out the design simply can not meet the electrical design intent, resulting in a serious following problems: (do not know or not know nothing about ethical issues) 1. With the original design of the electrical system not meeting board, the existence and low voltage switchgear circuit after qualifying serious conflicts seriously hinder the actual construction, often require changes to the original design unit plans to meet its electrical system requirements (monopoly impress ). 2. On the fire load and fire load of non-supply (mainly in high-rise building in) should be strictly sub-loop (from the bus segment) are not clear, the fire load and fire load of non-qualifying press of a circuit (especially the elevator and fire elevator, basement, etc.

变电站_外文翻译_外文文献_英文文献_变电站的综合概述

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英文文献及中文翻译

毕业设计说明书 英文文献及中文翻译 学院：专 2011年6月 电子与计算机科学技术软件工程

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英文论文及中文翻译

International Journal of Minerals, Metallurgy and Materials Volume 17, Number 4, August 2010, Page 500 DOI: 10.1007/s12613-010-0348-y Corresponding author: Zhuan Li E-mail: li_zhuan@https://www.wendangku.net/doc/153277831.html, ? University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2010 Preparation and properties of C/C-SiC brake composites fabricated by warm compacted-in situ reaction Zhuan Li, Peng Xiao, and Xiang Xiong State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China (Received: 12 August 2009; revised: 28 August 2009; accepted: 2 September 2009) Abstract: Carbon fibre reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) were fabricated by the warm compacted-in situ reaction. The microstructure, mechanical properties, tribological properties, and wear mechanism of C/C-SiC composites at different brake speeds were investigated. The results indicate that the composites are composed of 58wt% C, 37wt% SiC, and 5wt% Si. The density and open porosity are 2.0 g·cm–3 and 10%, respectively. The C/C-SiC brake composites exhibit good mechanical properties. The flexural strength can reach up to 160 MPa, and the impact strength can reach 2.5 kJ·m–2. The C/C-SiC brake composites show excellent tribological performances. The friction coefficient is between 0.57 and 0.67 at the brake speeds from 8 to 24 m·s?1. The brake is stable, and the wear rate is less than 2.02×10?6 cm3·J?1. These results show that the C/C-SiC brake composites are the promising candidates for advanced brake and clutch systems. Keywords: C/C-SiC; ceramic matrix composites; tribological properties; microstructure [This work was financially supported by the National High-Tech Research and Development Program of China (No.2006AA03Z560) and the Graduate Degree Thesis Innovation Foundation of Central South University (No.2008yb019).] 温压-原位反应法制备C / C-SiC刹车复合材料的工艺和性能 李专，肖鹏，熊翔 粉末冶金国家重点实验室，中南大学，湖南长沙410083，中国（收稿日期：2009年8月12日修订：2009年8月28日;接受日期：2009年9月2日） 摘要：采用温压?原位反应法制备炭纤维增强炭和碳化硅双基体(C/C-SiC)复合材