AUTOMATIC TRANSMISSION
The modern automatic transmission is by far，the most complicated mechanical component in today’s automobile。It is a type of transmission that sifts itself。A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine。
There are two basic types of automatic transmission based on whether the vehicle is rear wheel drive or front wheel drive。On a rear wheel drive car，the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position。A drive shaft connects the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels。Power flow on this system is simple and straight forward going from the engine，through the torque converter，then trough the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear transmission。
On a front wheel drive car，the transmission is usually combined with the final drive to form what is called a transaxle。The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car。Front axles are connected directly to the transaxle and provide power to front wheels。In this example，power floes from the engine，through the torque converter to a larger chain that sends the power through a 180 degree turn to the transmission that is along side the engine。From there，the power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles。
There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular。A much less popular rear and is connected by a drive shaft to the torque converter which is still mounted on the engine。This system is found on the new Corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling。Another rear drive system mounts everything，the engine，transmission and final drive in the rear。This rear engine arrangement is popular on the Porsche。
The modern automatic transmission consists of many components and systems that designed to work together in a symphony of planetary gear sets，the hydraulic system, seals and gaskets，the torque converter，the governor and the modulator or throttle cable and computer controls that has evolved over the years into what many mechanical inclined individuals consider to be an art from。Here try to used simple，generic explanation where possible to describe these systems。
1）Planetary gear sets
Automatic transmission contain many gears in various combinations。In a manual transmission，gears slide along shafts as you move the shift lever from one position to another，engaging various sizes gears as required in order to provide the correct gear ratio。In an automatic transmission，how ever，the gears are never physically moved and are always engaged to the same gears。This is accomplished through the
use of planetary gear sets。
The basic planetary gear set consists of a sun gear，a ring and two or more planet gears，all remaining in constant mesh。The planet gears are connected to each other through a common carrier which allows the gears to spin on shafts called “pinions”which are attached to the carrier。
One example of a way that this system can be used is by connecting the ring gear to the input shaft coming from the engine，connecting the planet carrier to the output shaft，and locking the sun gear so that it can’t move。In this scenario，when we turn the ring gear，the planets will “walk”along the sun gear ( which is held stationary ) causing the planet carrier to turn the output shaft in the same direction as the input shaft but at a slower speed causing gear reduction ( similar to a car in first gear )。
If we unlock the sun gear and lock any two elements together，this will cause all three elements to turn at the same speed so that to output shaft will turn at the same rate of speed as the input shaft。This is like a car that is third or high gear。Another way we can use a planetary gear set is by locking the planet carrier from moving，then applying power to the ring gear which will cause the sun gear to turn in opposite direction giving us reverse gear。
The illustration in Figure shows how the simple system described above would look in an actual transmission。The input shaft is connected to the ring gear，the output shaft is connected to the planet carrier which is also connected to a “Multi-disk” clutch pack。The sun gear is connected to drum which is also connected to the other half of the clutch pack。Surrounding the outside of the drum is a band that can be tightened around the drum when required to prevent the drum with the attached sun gear from turning。
The clutch pack is used，in this instance，to lock the planet carrier with the sun gear forcing both to turn at the same speed。If both the clutch pack and the band were released，the system would be in neutral。Turning the input shaft would turn the planet gears against the sun gear，but since noting is holding the sun gear，it will just spin free and have no effect on the output shaft。To place the unit in first gear，the band is applied to hold the sun gear from moving。To shift from first to high gear，the band is released and the clutch is applied causing the output shaft to turn at the same speed as the input shaft。
Many more combinations are possible using two or more planetary sets connected in various way to provide the different forward speeds and reverse that are found in modern automatic transmission。
2）Clutch pack
A clutch pack consists of alternating disks that fit inside a clutch drum。Half of the disks are steel and have splines that fit into groves on the inside of the drum。The other half have a friction material bonded to their surface and have splines on the inside edge that fit groves on the outer surface of the adjoining hub。There is a piston inside the drum that is activated by oil pressure at the appropriate time to squeeze the clutch pack together so that the two components become locked and turn as one。
3）One-way Clutch
A one-way clutch ( also known as a “sprag” clutch ) is a device that will allow a component such as ring gear to turn freely in one direction but not in the other。This effect is just like that bicycle，where the pedals will turn the wheel when pedaling forward，but will spin free when pedaling backward。
A common place where a one-way clutch is used is in first gear when the shifter is in the drive position。When you begin to accelerate from a stop，the transmission starts out in first gear。But have you ever noticed what happens if you release the gas while it is still in first gear ? The vehicle continues to coast as if you were in neutral。Now，shift into Low gear instead of Drive。When you let go of the gas in this case，you will feel the engine slow you down just like a standard shift car。The reason for this is that in Drive，one-way clutch is used whereas in Low，a clutch pack or a band is used。
4）Torque Converter
On automatic transmission，the torque converter takes the place of the clutch found on standard shift vehicles。It is there to allow the engine to continue running when the vehicle comes to a stop。The principle behind a torque converter is like taking a fan that is plugged into the wall and blowing air into another fan which is unplugged。If you grab the blade on the unplugged fan，you are able to hold it from turning but as soon as you let go，it will begin to speed up until it comes close to speed of the powered fan。The difference with a torque converter is that instead of using air it used oil or transmission fluid，to be more precise。
A torque converter is a lager doughnut shaped device that is mounted between the engine and the transmission。It consists of three internal elements that work together to transmit power to the transmission。The three elements of the torque converter are the pump，the Turbine，and the Stator。The pump is mounted directly to the torque housing which in turn is bolted directly to the engine’s crankshaft and turns at engine speed。The turbine is inside the housing and is connected directly to the input shaft of the transmission providing power to move the vehicle。The stator is mounted to a one-way clutch so that it can spin freely in one direction but not in the other。Each of the three elements has fins mounted in them to precisely direct the flow of oil through the converter。
With the engine running，transmission fluid is pulled into the pump section and is pushed outward by centrifugal force until it reaches the turbine section which stars it running。The fluid continues in a circular motion back towards the center of the turbine where it enters the stator。If the turbine is moving considerably slower than the pump，the fluid will make contact with the front of the stator fins which push the stator into the one way clutch and prevent it from turning。With the stator stopped，the fluid is directed by the stator fins to re-enter the pump at a “help”angle providing a torque increase。As the speed of the turbine catches up with the pump，the fluid starts hitting the stator blades on the back-side causing the stator to turn in the same direction as the pump and turbine。As the speed increase，all three elements begin to turn at approximately the same speed。Sine the ‘80s，in order to improve fuel economy，torque converters have been equipped with a lockup clutch which locks the turbine to the pump as the vehicle reaches approximately 40-50 mph。This lockup is controlled by computer and usually won’t engage unless the
transmission is in 3rd or 4th gear。
5）Hydraulic System
The hydraulic system is a complex maze of passage and tubes that sends that sends transmission fluid and under pressure to all parts of the transmission and torque converter and。Transmission fluid serves a number of purpose including : shift control ,general lubrication and transmission cooling。Unlike the engine ,which uses oil primary for lubrication ,every aspect of a transmission ‘s function is dependant on a constant supply of fluid is send pressure。In order to keep the transmission at normal operating temperature，a portion of the fluid is send to through one of two steel tubes to a special chamber that is submerged in anti-freeze in the radiator。Fluid passing through this chamber is cooled and then returned to the transmission through the other steel tube。A typical transmission has an avenge of ten quarts of fluid between the transmission，torque converter，and cooler tank，In fact，most of the components of a transmission are constantly submerged in fluid including the clutch packs and bands。The friction surfaces on these parts are designed to operate properly only when they are submerged in oil。
6）Oil Pump
The transmission oil pump ( not to confused with the pump element inside the torque converter ) is responsible for producing all the oil pressure that is required in the transmission。The oil pump is mounted to front of the transmission case and is directly connected to a flange on the engine crankshaft，the pump will produce pressure whenever the engine is running as there is a sufficient amount of transmission fluid available。The oil enters the pump through a filter that is located at bottom of the transmission oil pan and travels up a pickup tube directly to the oil pump。The oil is then sent，under pressure to the pressure regulator，the valve body and the rest of the components，as required。
7）Valve Body
The valve body is the control center of the automatic transmission。It contains a maze of channels and passages that direct hydraulic fluid to the numerous valves which when activate the appropriate clutch pack of band servo to smoothly shift to the appropriate gear for each driving situation。Each of the many valves in the valve body has a specific purpose and is named for that function。For example the 2-3 shift valve activates the 2nd gear up-shift or the 3-2 shift timing valve which determines when a downshift should occur。
The most important valve and the one that you have direct control over is the manual valve。The manual valve is directly connected to the gear shift handle and covers and uncovers various passages depending on what position the gear shift is paced in。When you place the gear shift in Drive，for instance，the manual valve directs fluid to the clutch pack ( s ) that activates 1st gear。It also sets up to monitor vehicle speed and throttle position so that it can determine the optimal time and the force for the 1-2 shift。On computer controlled transmission，you will also have electrical solenoids that are mounted in the valve body to direct fluid to the appropriate clutch packs or bands under computer control to more precisely control shift points。
8）Seals and Gaskets
An automatic transmission has many seals and gaskets to control the flow of hydraulic fluid and to keep it from leaking out。There are two main external seals : the front seal and the rear seal。The front seal seals the point where the torque converter mounts to the transmission case。This seal allows fluid to freely move from the converter to the transmission but keeps the fluid from leaking out。The rear seal keeps fluid from leaking past the output shaft。
A seal is usually made of rubber ( similar to the rubber in a windshield wiper blade ) and is used to keep oil from leaking past a moving part such as a spinning shaft。In some cases，the rubber is assisted by a spring that holds he rubber in close contact with the spinning shaft。
A gasket is a type of seal used to seal two stationary parts that are fasted together。Some common gasket materials are : paper，cork，rubber，silicone and soft metal。
Aside from the main seals，there are also a number of other seals and gasket that vary from transmission to transmission。A common example is the rubber O-ring that seals the shaft for the shift control lever。This is the shaft that you move when you manipulate the gear shifter。Another example that is common to most transmission is the oil pan gasket。In fact，seals are required anywhere that a device needs to pass through the transmission case with each one being a potential source for leaks。
9）Computer Controls
The computer uses sensors on the engine and transmission to detect such things as throttle position，vehicle speed，engine speed，engine load，stop light switch position，etc。to control exact shift points as well as how soft or firm the shift should be。Some computerized transmission even learn your driving style and constantly adapt to it so that every shift is timed precisely when you would need it。
Because of computer controls，sports models are coming out with the ability to take manual control of the transmission as through it were a stick shift lever through a special gate，then tapping it in one direction or the other in order to up-shift at will。The computer monitors this activity to make sure that the driver dose not select a gear that could over speed the engine and damage it。
Another advantage to these “ smart” transmission is that they have a self diagnostic mode which can detect a problem early on and warn you with an indicator light on the dash。A technician can then plug test equipment in and retrieve a list of trouble codes that will help pinpoint where the problem is。
自动变速器
对于现代的汽车，自动变速器是一个复杂的组件，这种传递动力的方式，是液力变矩期充当离合器来连接发动机和变速器。
两个基本类型的自动变速器基于该车辆是否是前驱动或后驱动。对发动机前置后驱动的汽车，变速器通常安装在发动机后底盘中心与油门配合。变速器输出轴连接到后桥，把发动机的动力传递到后轮，动力传输系统是直线的，从发动机，通过液力变矩器、变速器、传动轴、最后直接到到达车轮。
对于发动机前置前轮驱动的汽车，变速器通常和差速器装在一起。对于前驱动的汽车，变速器安装在发动机一侧，前车轴直接连接到差速器上，把动力传递给前轮。在这个布置中，动力来自于发动机，通过液力变矩器、变速器输出的动力通过了一个180度大转弯，经过变速器沿发动机侧边通过传动轴输出到前轮。
还有其它的一些布置，发动机前置前驱动，发动机横向布置，装设一个分动器可以实现四轮驱动。但这种形式目前是最常用的：发动机中置后驱动，可以使重量均匀的分布在前、后轮之间，改善了操作性能；发动机后置后驱动，发动机、变速器、驱动轮都在后方，这种后置式的发动机的安排，是最满意的。
现代的自动变速器包括了许多组件和系统的协同工作，有行星齿轮组、液压系统、密封件和垫圈、变矩器、调节器、节气门拉线、计算机控制这些都是多年来由机械式演变过来的。这用简单、通用的解释，描述一下这些系统。
1）行星齿轮组
自动变速器箱体内有很多齿轮，有各种不同的组合，在一个变速箱内，齿轮的滑动沿轴线从一个位置到另一个位置，对各种大小齿轮的要求，有正确的传动
比。在一个自动变速箱，至始至终，不是齿轮的机械移动来达到这一点的，通过行星齿轮组来完成。
基本的行星齿轮组成由一个太阳轮、一个齿圈、并且有两个或两个以上的行星齿轮，全部齿轮都是常啮合。行星齿轮的相互联系通过一个共同的载体，使齿轮相互啮合在一起。一个传递方式，这个系统可以从发动机的输出连接到齿圈作为主动件，连接行星轮作为从动件，并锁定太阳轮，使起不能转动。在这情况下，当我们把齿圈、行星齿轮，沿太阳轮转动，主动件与从动件就同向转动，从动件的转速慢，齿轮减速就类似汽车的一挡。
如果解开太阳轮和锁定其它两个元素，这就会使这三个要素以同样的速度转动，齿轮的传动就类似于汽车是第三或高挡位。另一个方式是，把行星架锁定，使太阳轮作为主动轮，齿圈作为从动件，这时它们的转动方向就相反，就类似以汽车的到挡。
上面所说的，在实际的传动过程是如何控制。齿圈为输入轴，行星架为输出轴，都是通过盘式离合器控制。太阳轮一个单向离合器，一个制动器，当制动器作用时，太阳轮只能从一个方向转动。
在这情况下，离合器的使用，锁定行星架与太阳轮迫使它们以相同的转速转动。如果它们的离合器和制动器都被释放，该系统在自由状态。变速器的行星齿轮组太阳轮是自由的，比输出动力。在一挡位，制动器制动太阳轮跟随转动，从第一挡到高挡制动器释放和离合器使用到输入轴，它们以同一个速度转动。
使用两个或两个以上的行星齿轮组以各种方式连接，可提供不同的前进速度和扭矩，普遍的使用以现代的自动变速器。
2）片式离合器
片式离合器主要由若干交替排列的离合器盘和离合器片组成。每片离合器盘上有伸出的突线，勾住离合器鼓，以输入轴连接。离合器片内的键槽与离合器壳互相啮合，离合器壳与中间轴键槽连接，中间轴又与后行星排内齿圈用键槽连接。因此，离合器盘和离合器片分别与输入轴和湖行星排内齿圈连接。操作离合器的活塞安装以离合器鼓上，离合器鼓亦称做为活塞缸。
3）单向离合器
单向离合器是一种只可以使元件在一个方向转动，如把齿圈自由在一贯方向，而
不能反向转动，这种作用就象是，自行车踏板转动时，可以带动车轮转动，当车轮转动或向另一个方向转动是自由的
一个单向离合器用于一挡时，在驱动方向是，当从停止开始加速，在第一个齿轮输出动力，如果继续加速，不在一挡位？汽车继续加速，他就是一个方向自由的。此时，单向离合器不在输出动力，当车速慢下来时，转速慢，它就可以起作用。这一个现象由于，在提供力的时候它才起作用，在高速时，是自由的。
4）液力变矩器
对于自动变速器，液力变矩器取代离合器装于车上。它的作用是：当车停下来，发动机还可以继续运转。传递扭矩的原理，比如，把一个风扇吹向另一个，另一个不用插电也能跟它一起转动，如果你压住扇片，它就不会转动，但你一放手，它就开始加速，直到速度接近动力风扇。它们两者的差异就是：变矩器不是利用空气，而是利用油液，以使他的传递更加准确。
液力变矩器是一个较大的盆壮装置，安装在发动机与变速器之间。它包含三个部件，协同工作，为变速器提供动力，液力变矩器的三要素是：泵论、涡轮、导轮，泵论是通过螺栓直接安装在发动机的曲轴上，转速与发动机的相同，涡轮连接到变速器的输入轴上，为汽车提供动力，导轮上装有一个单向离合器，使他只可以在一个方向转动，而在另一方被固定，每一个要素之间通过液流传递扭矩。
发动机启动后，输入轴开始旋转，带动泵轮旋转，因旋转产生的离心力使泵轮叶片间的液流沿叶片从外缘向外甩出；接着又由于泵轮和涡轮转速差引起泵轮叶片外缘与涡轮叶片外缘产生了压力差，液流从液压高的泵轮叶片外缘流进涡轮叶片外缘，同时，泵轮的旋转也使得其叶片带动液流随工作轮旋转，这一旋转就使液流流进涡轮时方向改变，从而冲击涡轮叶片推动涡轮绕泵轮同一方向旋转。从涡轮流出的液流进入固定不动的导轮，经导轮叶片改变方向后回流至泵轮。如果涡轮的速度大大低于泵轮转素时，导轮仍锁住不动。导轮停止，液流通过导轮时重新进入泵轮，促使泵轮旋转起到扭矩增大的作用。由于泵轮和导轮的转速增加，液流开始改变方向流向泵轮叶片背面，也可以产生增矩的作用。由于车速的提高，这三要素句以相同的转速旋转，为了提高燃油经济性，在液力变矩器上装了一个锁止离合器，车速达到40—50英里的时候，锁止离合器就把三要素连为一体，这种控制是计算机控制。
5）液压系统
液压系统是一个复杂的迷宫壮通道，液流压力控制变速器扭矩的输出，。液流有若干用途，包括：换挡控制、润滑、冷却。不象发动机，它只用来润滑，每一个流动，是依赖于不断提供的液体压力。为了使油液在一个正常的温度工作，部分液流从散热器中流过以便散热。液体通过此通道被冷却，然后返回到传输通道。液里变矩器和散热器，是用来给液流散热的。事实上大部分的摩擦表面都淹没在油液中，比如：离合器盘、离合器片，也能正常的工作。
6）油泵
油泵主要是负责提供油液传输过程中的压力，油泵安装在前面的泵轮上，并且以发动机的曲轴相连，当发动机转动时，带动油泵运转，产生压力，提供足够的油。油进入油泵时通过一个空气滤清器，安装在油底壳的底部。压力调节器、调压阀、压力修正阀调节后送到各个管路。
7）阀体
阀体是自动变速器的控制中心。它包含一个迷宫壮的通道输送液压油，在每一个工况下控制离合器和其它伺服机构，顺利的控制齿轮传动情况。
最重要的阀门一个直接控制的手动阀。手动阀是直接连接到齿轮变速箱里面的，根据它所在位置打开或关闭各种通道，控制换挡节奏。用齿轮变速传动来举例说明，监控车辆的速度和油门的位置，以便它能确定最佳的换挡时间，。计算机的控制，通过电磁阀控制油压压力，控制离合器或制动器，以更精确的控制换挡点。
8）密封垫和垫圈
一个自动变速器有许多的密封件和垫圈，以控制流动的液压油，使它不外泄。主要有两个外部密封垫：前油封和后油封。前油封安装到变速器的变矩器，这使得油底壳到变矩器的油液能自由流动，而不外泄。后密封垫使游液不泄漏到输出轴。
密封垫通常用橡胶（类似汽车挡风玻璃雨刮器叶片），它是用来保持不泄漏到其它部分，如旋转轴。在有的情况下，用一个弹簧和橡胶在一起，如用在花键轴。
垫圈是一种用来密封两个固定部分，使其连接在一起。一些常见的衬垫材料
是：硬纸、软木、橡胶、有机硅和软金属。
除了主要的密封垫，也有一些其它的密封垫和垫片，因使用条件而定，有的从轴到轴的连接。一个常见的例子是橡胶O型密封圈用来密封换的挡轴。就是说，你所操作的边速杠在转动时，另一个例子是大部分常见的油底壳垫片，事实上，密封垫是随时进行更换，防止油不泄漏。
9）计算机控制
计算机控制是利用传感器对发动机和变速器提取数据，因为节气门位置、汽车行驶速度、发动机转速、发动机负荷等是变数。利用这些数据可以精确控制换挡点，以便换挡平顺。一些电脑数据，能了解行驶条件，并不断的适应行驶条件的变化，使汽车稳定的行驶。
由于计算机的控制，通过一个特殊的元素代替了手动控制，在每一个工况都是安全的。计算机的控制，确保发动机转速不至于过高而使发动机损坏。
另一个好处是，这些精确的数据输入系统，有一个自诊断系统，以便能使我们及时的发现问题，当有问题时，故障指示灯就闪烁。维修人员就可以根据检测设备检测出的故障码，很快的找到问题所在部位。
Unit 1 Chemical Industry 化学工业 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin‘s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939). 1．化学工业的起源 尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。可以认为它起源于工业革命其间，大约在1800年，并发展成为为其它工业部门提供化学原料的产业。比如制肥皂所用的碱，棉布生产所用的漂白粉，玻璃制造业所用的硅及Na2CO3. 我们会注意到所有这些都是无机物。有机化学工业的开始是在十九世纪六十年代以William Henry Perkin 发现第一种合成染料—苯胺紫并加以开发利用为标志的。20世纪初，德国花费大量资金用于实用化学方面的重点研究，到1914年，德国的化学工业在世界化学产品市场上占有75%的份额。这要归因于新染料的发现以及硫酸的接触法生产和氨的哈伯生产工艺的发展。而后者需要较大的技术突破使得化学反应第一次可以在非常高的压力条件下进行。这方面所取得的成绩对德国很有帮助。特别是由于1914年第一次世界大仗的爆发，对以氮为基础的化合物的需求飞速增长。这种深刻的改变一直持续到战后（1918-1939）。 date bake to/from: 回溯到 dated: 过时的，陈旧的 stand sb. in good stead: 对。。。很有帮助
外文翻译 英文原文 Belt Conveying Systems Development of driving system Among the methods of material conveying employed，belt conveyors play a very important part in the reliable carrying of material over long distances at competitive cost．Conveyor systems have become larger and more complex and drive systems have also been going through a process of evolution and will continue to do so．Nowadays，bigger belts require more power and have brought the need for larger individual drives as well as multiple drives such as 3 drives of 750 kW for one belt(this is the case for the conveyor drives in Chengzhuang Mine)．The ability to control drive acceleration torque is critical to belt conveyors’performance．An efficient drive system should be able to provide smooth，soft starts while maintaining belt tensions within the specified safe limits．For load sharing on multiple drives．torque and speed control are also important considerations in the drive system’s design. Due to the advances in conveyor drive control technology，at present many more reliable．Cost-effective and performance-driven conveyor drive systems covering a wide range of power are available for customers’ choices[1]. 1 Analysis on conveyor drive technologies 1．1 Direct drives Full-voltage starters．With a full-voltage starter design，the conveyor head shaft is direct-coupled to the motor through the gear drive．Direct full-voltage starters are adequate for relatively low-power, simple-profile conveyors．With direct fu11-voltage starters．no control is provided for various conveyor loads and．depending on the ratio between fu11-and no-1oad power requirements，empty starting times can be three or four times faster than full load．The maintenance-free starting system is simple，low-cost and very reliable．However, they cannot control starting torque and maximum stall torque；therefore．they are
Circuit breaker 断路器 Compressed air circuit breaker is a mechanical switch equipm ent, can be i 空气压缩断路器是一种机械开关设备，能够在n normal and special conditions breaking current (such as sho rt circuit cur 正常和特殊情况下开断电流（比如说短路电流）。 rent). For example, air circuit breaker, oil circuit breaker, interf erence circ 例如空气断路器、油断路器，干扰电路的导体uit conductor for the application of the safety and reliability o f the circuit 干扰电路的导体因该安全可靠的应用于其中， breaker, current in arc from is usually divided into the followin g grades: a 电流断路器按灭弧远离通常被分为如下等级：ir switch circuit breaker, oil circuit breaker, less oil circuit break er, compr 空气开关断路器、油断路器、少油断路器、压缩空essed air circuit breaker, a degaussing of isolating switch, six s ulfur hexaf
外文原文 Mechanical Design Abstract: A machine is a combination of mechanisms and other components which transforms, transmits. Examples are engines, turbines, vehicles, hoists, printing presses, washing machines, and movie cameras. Many of the principles and methods of design that apply to machines also apply to manufactured articles that are not true machines. The term "mechanical design" is used in a broader sense than "machine design" to include their design. the motion and structural aspects and the provisions for retention and enclosure are considerations in mechanical design. Applications occur in the field of mechanical engineering, and in other engineering fields as well, all of which require mechanical devices, such as switches, cams, valves, vessels, and mixers. Keywords: Mechanical Design mechanisms Design Process The Design Process Designing starts with a need real.Existing apparatus may need improvements in durability, efficiency, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts. When the general shape and a few dimensions of the several components become
丹宁改性絮凝剂处理城市污水 J.Beltrán-heredia，J.ánche z-Martin 埃斯特雷马杜拉大学化学工程系和物理化学系,德埃娃儿，S / N 06071，巴达霍斯，西班牙 摘要 一种新的以丹宁为主要成分的混凝剂和絮凝剂已经过测试用以处理城市污水。TANFLOC 证实了其在浊度的去除上的高效性（接近100%，取决于剂量），并且近50%的BOD5和COD 被去除，表明TANFLOC是合适的凝集剂，效力可与明矾相媲美。混凝絮凝剂过程不依赖于温度，发现最佳搅拌速度和时间为40转/每分钟和30分钟。多酚含量不显著增加，30%的阴离子表面活性剂被去除。沉淀过程似乎是一种絮凝分离，所以污泥体积指数和它随絮凝剂剂量的改变可以确定。证明TANFLOC是相当有效的可用于污水处理的混凝絮凝剂。 关键词: 基于丹宁的絮凝剂城市污水絮凝天然混凝剂 1．简介 人类活动是废物的来源。特别是在城市定居点，来自家庭和工业的废水可能是危险有害的产品[ 1 ]，需要适当的处理，以避免对环境[ 2 ]和健康的影响[ 3,4 ]。2006年12月4日联合国大会通过决议宣布2008为国际卫生年。无效的卫生基础设施促使每年220万人死于腹泻，主要在3岁以下儿童，600万人因沙眼失明，两亿人感染血吸虫病，只是为了给出一些数据[ 5 ]。显然，他们中的大多数都是在发展中国家，所以谈及城市污水，必须研究适当的技术来拓宽可能的处理技术种类。 在这个意义上，许多类型的水处理被使用。他们之间的分歧在于经济和技术特点上。了摆脱危险的污染[ 6 ]，一些令人关注的论文已经发表的关于城市污水处理的几种天然的替代方法，包括绿色过滤器、化学初步分离、紫外消毒[ 7 ]和多级程序[ 8 ]。 几个以前的文件指出了城市污水管理[9,10]的重要性。这种类型的废物已成为社会研究的目标，因为它涉及到几个方面，都与社会结构和社会组织[11 ]相关。根据这一维度，必须认识到废水管理作为发展中国家的一种社会变化的因素，事关污水处理和生产之间的平衡，是非常重要的，一方面，人类要发展，另一方面，显而易见。 对水处理其它程序的研究一直是这和其他文件的范围。几年来，研究者关注的是发展中国家间的合作，他们正在致力于水处理的替代过程，主要考虑可持续发展，社会承受能力和可行性等理念。在这个意义上，自然混凝絮凝剂这一广为传播，易于操作的资源即使是非专业人员也不难操作。有一些例子，如辣木[ 14 ]和仙人掌榕[ 15 ]。丹宁可能是一个新的混凝剂和絮凝剂。 一些开拓者已经研究了丹宁水处理能力。 ?zacar和sengil [ 16 ]：从瓦罗NIA获得的丹宁，从土耳其的autoctonous树的果壳中获得丹宁，并用于他们的–污水混凝絮凝过程。他们表明，丹宁有很好的效果，结合Al2（SO4）3可进一步提高污泥去除率。 詹和赵[ 17 ]试着用丹宁为主要成分的凝胶作为吸收剂除去水中的铝，丹宁凝胶改进了金属去除过程，一定意义上也可参照Nakano等人的[ 18 ]，Kim 和Nakano[ 19 ]。 ?zacar和sengil [ 20 ]加强以前的文章给出了关于三卤甲烷的形成和其他不良化合物特殊的数据，以及处理后的水质安全。他们始终使用丹宁与Al2（SO4）3的组合。 帕尔马等人将丹宁从辐射松的树皮为原位提取，用于重金属去除中聚合固体。树皮本
Manufacturing Engineering and Technology—Machining Serope kalpakjian；Steven R.Schmid 机械工业出版社2004年3月第1版 20.9 MACHINABILITY The machinability of a material usually defined in terms of four factors: 1、Surface finish and integrity of the machined part; 2、Tool life obtained; 3、Force and power requirements; 4、Chip control. Thus, good machinability good surface finish and integrity, long tool life, and low force And power requirements. As for chip control, long and thin (stringy) cured chips, if not broken up, can severely interfere with the cutting operation by becoming entangled in the cutting zone. Because of the complex nature of cutting operations, it is difficult to establish relationships that quantitatively define the machinability of a material. In manufacturing plants, tool life and surface roughness are generally considered to be the most important factors in machinability. Although not used much any more, approximate machinability ratings are available in the example below. 20.9.1 Machinability Of Steels Because steels are among the most important engineering materials (as noted in Chapter 5), their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels. Resulfurized and Rephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase particles), which act as stress raisers in the primary shear zone. As a result, the chips produced break up easily and are small; this improves machinability. The size, shape, distribution, and concentration of these inclusions significantly influence machinability. Elements such as tellurium and selenium, which are both chemically similar to sulfur, act as inclusion modifiers in
毕业设计（论文） 外文文献翻译 文献、资料中文题目：供配电系统 文献、资料英文题目：POWER SUPPLY AND DISTRIBUTION SYSTEM 文献、资料来源： 文献、资料发表（出版）日期： 院（部）： 专业： 班级： 姓名： 学号： 指导教师： 翻译日期： 2017.02.14
POWER SUPPLY AND DISTRIBUTION SYSTEM ABSTRACT The basic function of the electric power system is to transport the electric power towards customers. The l0kV electric distribution net is a key point that connects the power supply with the electricity using on the industry, business and daily-life. For the electric power, allcostumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable.To improve the reliability of the power supply network, we must increase the investment cost of the network construction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic,between the investment and the loss by calculating the investment on power net and the loss brought from power-off. KEYWARDS：power supply and distribution,power distribution reliability，reactive compensation,load distribution
哲学Philosophy 马克思主义哲学Philosophy of Marxism 中国哲学Chinese Philosophy 外国哲学Foreign Philosophies 逻辑学Logic 伦理学Ethics 美学Aesthetics 宗教学Science of Religion 科学技术哲学Philosophy of Science and Technology 经济学Economics 理论经济学Theoretical Economics 政治经济学Political Economy 经济思想史History of Economic Thought 经济史History of Economic 西方经济学Western Economics 世界经济World Economics 人口、资源与环境经济学Population, Resources and Environmental Economics 应用经济学Applied Economics 国民经济学National Economics 区域经济学Regional Economics 财政学（含税收学）Public Finance (including Taxation) 金融学（含保险学）Finance (including Insurance) 产业经济学Industrial Economics 国际贸易学International Trade 劳动经济学Labor Economics 统计学Statistics 数量经济学Quantitative Economics 中文学科、专业名称英文学科、专业名称 国防经济学National Defense Economics 法学Law 法学Science of Law 法学理论Jurisprudence 法律史Legal History 宪法学与行政法学Constitutional Law and Administrative Law 刑法学Criminal Jurisprudence 民商法学(含劳动法学、社会保障法学) Civil Law and Commercial Law (including Science of Labour Law and Science of Social Security Law ) 诉讼法学Science of Procedure Laws
1. Introduction America is one of the countries that speak English. Because of the special North American culture, developing history and the social environment, American English has formed its certain unique forms and the meaning. Then it turned into American English that has the special features of the United States. American English which sometimes also called United English or U.S English is the form of the English language that used widely in the United States .As the rapid development of American economy, and its steady position and strong power in the world, American English has become more and more widely used. As in 2005, more than two-thirds of English native speakers use various forms of American English. The philologists of the United States had divided the English of the United States into four major types: “America n creating”; “Old words given the new meaning”; “Words that eliminated by English”;“The phonetic foreign phrases and the languages that are not from the English immigrates”[1]. Compared to the other languages, American English is much simple on word spelling, usage and grammar, and it is one of the reasons that American English is so popular in the world. The thesis analyzes the differences between American English and British English. With the main part, it deals with the development of American English, its peculiarities compared to that of British English, its causes and tendency. 2. Analyses the Differences As we English learners, when we learning English in our junior or senior school, we already came across some words that have different spellings, different pronunciations or different expressions, which can be represented by following contrasted words: spellings in "color" vs. "colour"; pronunciations in "sec-re-ta-ry" vs. "sec-re-try";
机械专业英语词汇中英文对照翻译一览表 陶瓷ceramics 合成纤维synthetic fibre 电化学腐蚀electrochemical corrosion 车架automotive chassis 悬架suspension 转向器redirector 变速器speed changer 板料冲压sheet metal parts 孔加工spot facing machining 车间workshop 工程技术人员engineer 气动夹紧pneuma lock 数学模型mathematical model 画法几何descriptive geometry 机械制图Mechanical drawing 投影projection 视图view 剖视图profile chart 标准件standard component 零件图part drawing 装配图assembly drawing
尺寸标注size marking 技术要求technical requirements 刚度rigidity 内力internal force 位移displacement 截面section 疲劳极限fatigue limit 断裂fracture 塑性变形plastic distortion 脆性材料brittleness material 刚度准则rigidity criterion 垫圈washer 垫片spacer 直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear 直齿锥齿轮straight bevel gear 运动简图kinematic sketch 齿轮齿条pinion and rack 蜗杆蜗轮worm and worm gear 虚约束passive constraint 曲柄crank 摇杆racker
毕业设计(论文)外文资料翻译 学院：电气信息学院 专业：电气工程及其自动化 姓名：郭骥翔 学号： 081001227 外文出处： Adaptive torque control of variable speed wind turbines 附件： 1.外文资料翻译译文；2.外文原文。 指导教师评语： 签名： 年月日(用外文写)
附件1：外文资料翻译译文 多种风力涡轮机的适应性转矩控制 4.5 使用SymDyn进行仿真 所有先前所描述的模拟是使用SimInt来演示的，其中，如前所述，包括唯一的转子角速度自由度，与复杂的仿真工具比，如SymDyn和FAST，他能够更快的运行。然而，为了确认目的，与其他更流行的仿真工具比较SimInt在适应运行上的增益是很有价值的。适应性的增加并不是期望它能够同等的适应每一个仿真工具，因为每个仿真工具都有其独到的涡轮机模型。但是如果每个涡轮机的造型都相同，如同本例，那么在SimInt 和SymDyn中则有着基本相似的适应性增益(CART)。在数据4-10中，这种相似性被明显的显示出来。 SimInt和SymDyn仿真工具都是由零时刻开始，而且大多数参数初值都相同，如M，角速度等。然而，尽管这两个涡轮机模型都设立了最佳转矩控制M*，但是CP表面却有着不同程度的峰值。因此为了使初始过程大致相同，初始Pfavg值应有相同的最大比例，而不是相同的绝对值。在显示标准化M值4-10的上图中，显示了合理的类似数据。但在30到60小时后，仿真工具的适应性增益开始出现分歧。但在此之后，他们再次互相接近，在从模拟开始100小时到模拟结束这段时间，他们保持基本重合。从下图中也可以清楚的观察出，每个仿真工具都在调整他们的增益M，并采集最大输出功率。 尽管SimInt仿真速度差不多是SymDyn仿真速度的五倍，在图4-10中所显示的SymDyn 数据是唯一一个可以验证适应性增益法则的模拟工具。在这个展示了两个模拟工具合理
Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.
机械工业出版社2004年3月第1版 20.9 MACHINABILITY The machinability of a material usually defined in terms of four factors: 1、Surface finish and integrity of the machined part; 2、Tool life obtained; 3、Force and power requirements; 4、Chip control. Thus, good machinability good surface finish and integrity, long tool life, and low force And power requirements. As for chip control, long and thin (stringy) cured chips, if not broken up, can severely interfere with the cutting operation by becoming entangled in the cutting zone. Because of the complex nature of cutting operations, it is difficult to establish relationships that quantitatively define the machinability of a material. In manufacturing plants, tool life and surface roughness are generally considered to be the most important factors in machinability. Although not used much any more, approximate machinability ratings are available in the example below. 20.9.1 Machinability Of Steels Because steels are among the most important engineering materials (as noted in Chapter 5), their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels. Resulfurized and Rephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase particles), which act as stress raisers in the primary shear zone. As a result, the chips produced break up easily and are small; this improves machinability. The size, shape, distribution, and concentration of these inclusions significantly influence machinability. Elements such as tellurium and selenium, which are both chemically similar to sulfur, act as inclusion modifiers in resulfurized steels. Phosphorus in steels has two major effects. It strengthens the ferrite, causing