英文资料翻译(原文)Friction (1)

Friction , Lubrication of Bearing and How to

Extend Bearing Life

Abstract：This article is about the types, harm of bearing friction and the modes of friction reduction. Among all the modes, perhaps the lubrication is one of the most effectively mode, it also has many kinds of forms, functions and types. Nature works hard to destroy bearings, but their chances of survival can be improved by following a few simple guidelines. Extreme neglect in a bearing leads to overheating and possibly seizure or, at worst, an explosion. But even a failed bearing leaves clues as to what went wrong. After a little detective work, action can be taken to avoid a repeat performance.

Keywords: bearings friction lubrication failures life

Part 1:Friction , Lubrication of Bearing

In many of the problem thus far , the student has been asked to disregard or neglect friction . Actually , friction is present to some degree whenever two parts are in contact and move on each other. The term friction refers to the resistance of two or more parts to movement.

Friction is harmful or valuable depending upon where it occurs. friction is necessary for fastening devices such as screws and rivets which depend upon friction to hold the fastener and the parts together. Belt drivers, brakes, and tires are additional applications where friction is necessary.

The friction of moving parts in a machine is harmful because it reduces the mechanical advantage of the device. The heat produced by friction is lost energy because no work takes place. Also , greater power is required to overcome the increased friction. Heat is destructive in that it causes expansion. Expansion may cause a bearing or sliding surface to fit tighter. If a great enough pressure builds up because made from low temperature materials may melt.

There are three types of friction which must be overcome in moving parts:

(1)starting, (2)sliding, and(3)rolling. Starting friction is the friction between two solids that tend to resist movement. When two parts are at a state of rest, the surface irregularities of both parts tend to interlock and form a wedging action. To produce

motion in these parts, the wedge-shaped peaks and valleys of the stationary surfaces must be made to slide out and over each other. The rougher the two surfaces, the greater is starting friction resulting from their movement .

Since there is usually no fixed pattern between the peaks and valleys of two mating parts, the irregularities do not interlock once the parts are in motion but slide over each other. The friction of the two surfaces is known as sliding friction. As shown in figure ,starting friction is always greater than sliding friction .

Rolling friction occurs when roller devces are subjected to tremendous stress which cause the parts to change shape or deform. Under these conditions, the material in front of a roller tends to pile up and forces the object to roll slightly uphill. This changing of shape , known as deformation, causes a movement of molecules. As a result ,heat is produced from the added energy required to keep the parts turning and overcome friction.

The friction caused by the wedging action of surface irregularities can be overcome partly by the precision machining of the surfaces. However, even these smooth surfaces may require the use of a substance between them to reduce the friction still more. This substance is usually a lubricant which provides a fine, thin oil film. The film keeps the surfaces apart and prevents the cohesive forces of the surfaces from coming in close contact and producing heat .

Another way to reduce friction is to use different materials for the bearing surfaces and rotating parts. This explains why bronze bearings, soft alloys, and copper and tin iolite bearings are used with both soft and hardened steel shaft. The iolite bearing is porous. Thus, when the bearing is dipped in oil, capillary action carries the oil through the spaces of the bearing. This type of bearing carries its own lubricant to the points where the pressures are the greatest.

Moving parts are lubricated to reduce friction, wear, and heat. The most commonly used lubricants are oils, greases, and graphite compounds. Each lubricant serves a different purpose. The conditions under which two moving surfaces are to work determine the type of lubricant to be used and the system selected for distributing the lubricant.

On slow moving parts with a minimum of pressure, an oil groove is usually sufficient to distribute the required quantity of lubricant to the surfaces moving on each other .

A second common method of lubrication is the splash system in which parts moving in a reservoir of lubricant pick up sufficient oil which is then distributed to all moving parts during each cycle. This system is used in the crankcase of lawn-mower engines to lubricate the crankshaft, connecting rod ,and parts of the piston.

A lubrication system commonly used in industrial plants is the pressure system. In this system, a pump on a machine carries the lubricant to all of the bearing surfaces at a constant rate and quantity.

There are numerous other systems of lubrication and a considerable number of lubricants available for any given set of operating conditions. Modern industry pays greater attention to the use of the proper lubricants than at previous time because of the increased speeds, pressures, and operating demands placed on equipment and devices.

Although one of the main purposes of lubrication is reduce friction, any substance-liquid , solid , or gaseous-capable of controlling friction and wear between sliding surfaces can be classed as a lubricant.

Varieties of lubrication

Unlubricated sliding. Metals that have been carefully treated to remove all foreign materials seize and weld to one another when slid together. In the absence of such a high degree of cleanliness, adsorbed gases, water vapor ,oxides, and contaminants reduce frictio9n and the tendency to seize but usually result in severe wear; this is called “unlubricated ”or dry sliding.

Fluid-film lubrication. Interposing a fluid film that completely separates the sliding surfaces results in fluid-film lubrication. The fluid may be introduced intentionally as the oil in the main bearing of an automobile, or unintentionally, as in the case of water between a smooth tuber tire and a wet pavement. Although the fluid is usually a liquid such as oil, water, and a wide range of other materials, it may also

be a gas. The gas most commonly employed is air.

Boundary lubrication. A condition that lies between unlubricated sliding and fluid-film lubrication is referred to as boundary lubrication, also defined as that condition of lubrication in which the friction between surfaces is determined by the properties of the surfaces and properties of the lubricant other than viscosity. Boundary lubrication encompasses a significant portion of lubrication phenomena and commonly occurs during the starting and stopping off machines.

Solid lubrication. Solid such as graphite and molybdenum disulfide are widely used when normal lubricants do not possess sufficient resistance to load or temperature extremes. But lubricants need not take only such familiar forms as fats, powders, and gases; even some metals commonly serve as sliding surfaces in some sophisticated machines.

Function of lubricants

Although a lubricant primarily controls friction and ordinarily does perform numerous other functions, which vary with the application and usually are interrelated .

Friction control. The amount and character of the lubricant made available to sliding surfaces have a profound effect upon the friction that is encountered. For example, disregarding such related factors as heat and wear but considering friction alone between the same surfaces with on lubricant. Under fluid-film conditions, friction is encountered. In a great range of viscosities and thus can satisfy a broad spectrum of functional requirements. Under boundary lubrication conditions , the effect of viscosity on friction becomes less significant than the chemical nature of the lubricant.

Wear control. wear occurs on lubricated surfaces by abrasion, corrosion ,and solid-to-solid contact wear by providing a film that increases the distance between the sliding surfaces ,thereby lessening the damage by abrasive contaminants and surface

asperities.

Temperature control. Lubricants assist in controlling corrosion of the surfaces themselves is twofold. When machinery is idle, the lubricant acts as a preservative. When machinery is in use, the lubricant controls corrosion by coating lubricated parts with a protective film that may contain additives to neutralize corrosive materials. The ability of a lubricant to control corrosion is directly relatly to the thickness of the lubricant film remaining on the metal surfaces and the chermical composition of the lubricant.

Other functions

Lubrication are frequently used for purposes other than the reduction of friction. Some of these applications are described below.

Power transmission. Lubricants are widely employed as hydraulic fluids in fluid transmission devices.

Insulation. In specialized applications such as transformers and switchgear , lubricants with high dielectric constants acts as electrical insulators. For maximum insulating properties, a lubricant must be kept free of contaminants and water.

Shock dampening. Lubricants act as shock-dampening fluids in energy transferring devices such as shock absorbers and around machine parts such as gears that are subjected to high intermittent loads.

Sealing. Lubricating grease frequently performs the special function of forming a seal to retain lubricants or to exclude contaminants.

The object of lubrication is to reduce friction ,wear , and heating of machine pars which move relative to each other. A lubricant is any substance which, when inserted between the moving surfaces, accomplishes these purposes. Most lubricants are liquids(such as mineral oil, silicone fluids, and water),but they may be solid for use in dry bearings, greases for use in rolling element bearing, or gases(such as air) for use in

gas bearings. The physical and chemical interaction between the lubricant and lubricating surfaces must be understood in order to provide the machine elements with satisfactory life.

The understanding of boundary lubrication is normally attributed to hardy and doubleday , who found the extrememly thin films adhering to surfaces were often sufficient to assist relative sliding. They concluded that under such circumstances the chemical composition of fluid is impor tant, and they introduced the term “boundary lubrication”. Boundary lubrication is at the opposite end of the spectrum from hydrodynamic lubrication.

Five distinct of forms of lubrication that may be defined :(a) hydrodynamic; (b)hydrostatic;(c)elastohydrodynamic (d)boundary; (e)solid film.

Hydrodynamic lubrication means that the load-carrying surfaces of the bearing are separated by a relatively thick film of lubricant, so as to prevent metal contact, and that the stability thus obtained can be explained by the laws of the lubricant under pressure ,though it may be; but it does require the existence of an adequate supply at all times. The film pressure is created by the moving surfaces itself pulling the lubricant under pressure, though it maybe. The film pressure is created by the moving surface to creat the pressure necessary to separate the surfaces against the load on the bearing . hydrodynamic lubrication is also called full film ,or fluid lubrication .

Hydrostatic lubrication is obtained by introducing the lubricant ,which is sometime air or water ,into the load-bearing area at a pressure high enough to separate the surface with a relatively thick film of lubricant. So ,unlike hydrodynanmic lubrication, motion of one surface relative to another is not required .

Elasohydrodynamic lubrication is the phenomenon that occurs when a lubricant is introduced between surfaces which are in rolling contact, such as mating gears or rolling bearings. The mathematical explanation requires the hertzian theory of contact stress and fluid mechanics.

When bearing must be operated at exetreme temperatures, a solid film lubricant

such as graphite or molybdenum disulfide must be use used because the ordinary mineral oils are not satisfactory. Must research is currently being carried out in an effort, too, to find composite bearing materials with low wear rates as well as small frictional coefficients.

In a journal bearing, a shaft rotates or oscillates within the bearing , and the relative motion is sliding . in an antifriction bearing, the main relative motion is rolling . a follower may either roll or slide on the cam. Gear teeth mate with each other by a combination of rolling and sliding . pistions slide within their cylinders. All these applications require lubrication to reduce friction ,wear, and heating.

The field of application for journal bearing s is immense. The crankshaft and connecting rod bearings of an automotive engine must poerate for thousands of miles at high temperatures and under varying load conditions . the journal bearings used in the steam turbines of power generating station is said to have reliabilities approaching 100 percent. At the other extreme there are thousands of applications in which the loads are light and the service relatively unimportant. a simple ,easily installed bearing is required ,suing little or no lubrication. In such cases an antifriction bearing might be a poor answer because because of the cost, the close ,the radial space required ,or the increased inertial effects. Recent metallurgy developments in bearing materials , combined with increased knowledge of the lubrication process, now make it possible to design journal bearings with satisfactory lives and very good reliabilities.

Part 2: How to Extend Bearing Life

Bearings fail for a number of reasons，but the most common are misapplication，contamination，improper lubricant，shipping or handling damage，and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrong．

However，while a postmortem yields good information，it is better to avoid the process altogether by specifying the bearing correctly in The first place．To do this，it is

useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing.

Equally critical is a study of requirements for noise, torque, and run out, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job.

1 Why bearings fail

About 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environment．Fortunately, a bearing failure caused by environment or handling contamination is preventable，and a simple visual examination can easily identify the cause．

Conducting a postmortem il1ustrates what to look for on a failed or failing bearing．Then，understanding the mechanism behind the failure, such as brandling or fatigue, helps eliminate the source of the problem.

Brandling is one type of bearing failure easily avoided by proper handing and assembly. It is characterized by indentations in the bearing raceway caused by shock loading－such as when a bearing is dropped-or incorrect assembly. Brandling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)．It may also be caused by improper assembly, Which places a load across the races．Raceway dents also produce noise，vibration，and increased torque.

A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turning．This problem is called false brandling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brandling acts like an abrasive, further contaminating the bearing. Unlike brandling, false brandling is often indicated by a reddish color from fretting corrosion in the lubricant.

False brandling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required

to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brandling during transit.

Seizures can be caused by a lack of internal clearance, improper lubrication, or excessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color，usually to blue-black or straw colored．Friction also causes stress in the retainer，which can break and hasten bearing failure．Premature material fatigue is caused by a high load or excessive preload．When these conditions are unavoidable，bearing life should be carefully calculated so that a maintenance scheme can be worked out．

Another solution for fighting premature fatigue is changing material．When standard bearing materials，such as 440C or SAE 52100，do not guarantee sufficient life，specialty materials can be recommended. In addition，when the problem is traced back to excessive loading，a higher capacity bearing or different configuration may be used．Creep is less common than premature fatigue．In bearings．it is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaft．Creep can be expensive because it causes damage to other components in addition to the bearing．0ther more likely creep indicators are scratches，scuff marks，or discoloration to shaft and bore．To prevent creep damage，the bearing housing and shaft fittings should be visually checked．

Misalignment is related to creep in that it is mounting related．If races are misaligned or cocked．The balls track in a noncircumferencial path．The problem is incorrect mounting or tolerancing，or insufficient squareness of the bearing mounting site．Misalignment of more than 1/4·can cause an early failure．

Contaminated lubricant is often more difficult to detect than misalignment or creep．Contamination shows as premature wear．Solid contaminants become an abrasive in the lubricant．In addition。insufficient lubrication between ball and retainer wears and weakens the retainer．In this situation，lubrication is critical if the retainer is a fully machined type．Ribbon or crown retainers，in contrast，allow lubricants to more easily reach all surfaces．

Rust is a form of moisture contamination and often indicates the wrong material for the application．If the material checks out for the job，the easiest way to prevent rust is to keep bearings in their packaging，until just before installation．

2 Avoiding failures

The best way to handle bearing failures is to avoid them．This can be done in the selection process by recognizing critical performance characteristics．These include noise，starting and running torque，stiffness，nonrepetitive runout，and radial and axial play．In some applications, these items are so critical that specifying an ABEC level alone is not sufficient．

Torque requirements are determined by the lubricant，retainer，raceway quality(roundness cross curvature and surface finish)，and whether seals or shields are used．Lubricant viscosity must be selected carefully because inappropriate lubricant，especially in miniature bearings，causes excessive torque．Also，different lubricants have varying noise characteristics that should be matched to the application. For example，greases produce more noise than oil．

Nonrepetitive runout(NRR)occurs during rotation as a random eccentricity between the inner and outer races，much like a cam action．NRR can be caused by retainer tolerance or eccentricities of the raceways and balls．Unlike repetitive runout, no compensation can be made for NRR.

NRR is reflected in the cost of the bearing．It is common in the industry to provide different bearing types and grades for specific applications．For example，a bearing with an NRR of less than 0.3um is used when minimal runout is needed，such as in disk—drive spindle motors．Similarly，machine—tool spindles tolerate only minimal deflections to maintain precision cuts．Consequently, bearings are manufactured with low NRR just for machine-tool applications．

Contamination is unavoidable in many industrial products，and shields and seals are commonly used to protect bearings from dust and dirt．However，a perfect bearing seal is

not possible because of the movement between inner and outer races．Consequently，lubrication migration and contamination are always problems．

Once a bearing is contaminated, its lubricant deteriorates and operation becomes noisier．If it overheats，the bearing can seize．At the very least，contamination causes wear as it works between balls and the raceway，becoming imbedded in the races and acting as an abrasive between metal surfaces．Fending off dirt with seals and shields illustrates some methods for controlling contamination．Noise is as an indicator of bearing quality．Various noise grades have been developed to classify bearing performance capabilities．Noise analysis is done with an Anderonmeter, which is used for quality control in bearing production and also when failed bearings are returned for analysis. A transducer is attached to the outer ring and the inner race is turned at 1,800rpm on an air spindle. Noise is measured in andirons, which represent ball displacement in μm/rad.

With experience, inspectors can identify the smallest flaw from their sound. Dust, for example, makes an irregular crackling. Ball scratches make a consistent popping and are the most difficult to identify. Inner-race damage is normally a constant high-pitched noise, while a damaged outer race makes an intermittent sound as it rotates.

Bearing defects are further identified by their frequencies. Generally, defects are separated into low, medium, and high wavelengths. Defects are also referenced to the number of irregularities per revolution.

Low-band noise is the effect of long-wavelength irregularities that occur about 1.6 to 10 times per revolution. These are caused by a variety of inconsistencies, such as pockets in the race. Detectable pockets are manufacturing flaws and result when the race is mounted too tightly in multiplejaw chucks.

Medium-hand noise is characterized by irregularities that occur 10 to 60 times per revolution. It is caused by vibration in the grinding operation that produces balls and raceways. High-hand irregularities occur at 60 to 300 times per revolution and indicate closely spaced chatter marks or widely spaced, rough irregularities.

Classifying bearings by their noise characteristics allows users to specify a noise grade in addition to the ABEC standards used by most manufacturers. ABEC defines physical tolerances such as bore, outer diameter, and runout. As the ABEC class number

increase (from 3 to 9), tolerances are tightened. ABEC class, however, does not specify other bearing characteristics such as raceway quality, finish, or noise. Hence, a noise classification helps improve on the industry standard.

Reference

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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.sodocs.net/doc/a016063607.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

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Exploring Filipino School Counselors’ Beliefs about Learning Allan B. I. Bernardo [Abstract] School reform efforts that focus on student learning require school counselors to take on important new roles as advocates of student learning and achievement.But how do school counselors understand the process of learning? In this study, we explore the learning beliefs of 115 Filipino school counselors who indicated their degree of agreementwith 42 statements about the process of learning and the factors thatinfluence this process.A principal components analysis of the responses to the 42 statements suggested three factors:(F1)social-cognitive constructivist beliefs, (F2) teacher-curriculum-centered behaviorist beliefs,and (F3) individual difference factors.The preliminary results are briefly discussed in terms of issues related to how Filipino school counselors’ conceptions of learning may guide their strategies for promoting student learning and achievement. [Key words]beliefs about learning, conceptions of learning, school counselors, student learning, Philippines School reform efforts in different parts of the world have focusedon students’learning. In particular,most school improvement programsnow aim to ensure that students acquire the high-level knowledge and skills that help them to thrive in today’s highly competitive globaleconomy (e.g., Lee & Williams, 2006). I n this regard, school reform programs draw from various contemporary theories and research on learning (e.g.,Bransford,Brown, & Cocking, 1999; Lambert & McCombs, 1998).The basic idea is that all school improvement efforts should be directed at ensuring students achieve high levels of learning or attainment of well-defined curricular objectives and standards.For example, textbooks (Chien & Young, 2007), computers and educational technology (Gravoso, 2002; Haertnel & Means, 2003;Technology in Schools Task Force, 2003), and educational assessment systems (Black & Wiliam2004; Cheung & Ng, 2007; Clark, 2001; Stiggins, 2005) are being reconsidered as regards how they can effectively provide scaffolds and resources for advancing student learning. Likewise,the allocation and management of a school’s financial resources are assessed in terms ofwhether these are effectively mobilized and utilized towards improving student learning (Bolam, 2006; Chung & Hung, 2006; Retna, 2007). In this regard, some advocates have also called for an examination of the role of school counselors in these reform efforts (Herr, 2002). Inthe United States, House and Hayes (2002) challenged school counselors to take proactive leadership roles in advocating for the success of all

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文献翻译英文原文

https://www.sodocs.net/doc/a016063607.html,/finance/company/consumer.html Consumer finance company The consumer finance division of the SG group of France has become highly active within India. They plan to offer finance for vehicles and two-wheelers to consumers, aiming to provide close to Rs. 400 billion in India in the next few years of its operations. The SG group is also dealing in stock broking, asset management, investment banking, private banking, information technology and business processing. SG group has ventured into the rapidly growing consumer credit market in India, and have plans to construct a headquarters at Kolkata. The AIG Group has been approved by the RBI to set up a non-banking finance company (NBFC). AIG seeks to introduce its consumer finance and asset management businesses in India. AIG Capital India plans to emphasize credit cards, mortgage financing, consumer durable financing and personal loans. Leading Indian and international concerns like the HSBC, Deutsche Bank, Goldman Sachs, Barclays and HDFC Bank are also waiting to be approved by the Reserve Bank of India to initiate similar operations. AIG is presently involved in insurance and financial services in more than one hundred countries. The affiliates of the AIG Group also provide retirement and asset management services all over the world. Many international companies have been looking at NBFC business because of the growing consumer finance market. Unlike foreign banks, there are no strictures on branch openings for the NBFCs. GE Consumer Finance is a section of General Electric. It is responsible for looking after the retail finance operations. GE Consumer Finance also governs the GE Capital Asia. Outside the United States, GE Consumer Finance performs its operations under the GE Money brand. GE Consumer Finance currently offers financial services in more than fifty countries. The company deals in credit cards, personal finance, mortgages and automobile solutions. It has a client base of more than 118 million customers throughout the world

英文翻译(原文)

GRA VITY RETAINING?WALL 1. INTRODUCTION Retaining walls are structures used to provide stability for earth or other material where conditions disallow the mass to assume its natural slope, and are commonly used to hold back or support soilbanks,coal or ore piles, and water. Retaining walls are classified, based on the method of achieving stability, into six principal types (Fig.1). The gravity-wall depends upon its weight, as the name implies, for stability. The cantilever wall is a reinforced-concrete wall that utilizes cantilever action to retain the mass behind the wall from assuming a natural slope. Stability of this wall is partially achieved from the weight of soil on the heel portion of the base slab. A counterfort retaining wall is similar to a cantilever retaining wall, except that it is used where the cantilever is long or for very high pressures behind wall and has counterforts, which tie the wall and base together, built at intervals along the wall to reduce the bending moments and sheers. As indicated in Fig.1c, the counterfort is behind the wall and subjected to tensile forces. A buttressed retaining wall is similar to a counterfort wall, except that the bracing is in front of the wall and is in compression instead of tension. Two other types of walls not considered further are crib walls, which are built-up members of pieces of precast concrete, metal, or timber and are supported by anchor pieces embedded in the soil for stability, and semigravity walls, which are walls intermediate between a true gravity and a cantilever wall. (a)(b)(e)

中文和英文简历和专业英语材料翻译

韶关学院 期末考核报告 科目：专业英语 学生姓名： 学号： 同组人： 院系： 专业班级： 考核时间：2012年10月9日—2012年11月1 日评阅教师： 评分：

第1章英文阅读材料翻译 (1) 第2章中文摘要翻译英文 (3) 第3章中文简历和英文简历 (4) 第4章课程学习体会和建议 (6) 参考文献 (7)

第1章英文阅读材料翻译 Mechanization and Automation Processes of mechanization have been developing and becoming more complex ever since the beginning of the Industrial Revolution at the end of the 18th century. The current developments of automatic processes are, however, different from the old ones. The “automation” of the 20th century is distinct from the mechanization of the 18th and 19th centuries inasmuch as mechanization was applied to individual operations, wherea s “automation” is concerned with the operation and control of a complete producing unit. And in many, though not all, instances the element of control is so great that whereas mechanization displaces muscle, “automation”displaces brain as well. The distinction between the mechanization of the past and what is happening now is, however, not a sharp one. At one extreme we have the electronic computer with its quite remarkable capacity for discrimination and control, while at the other end of the scale are “ transfer machines” , as they are now called, which may be as simple as a conveyor belt to another. An automatic mechanism is one which has a capacity for self-regulation; that is, it can regulate or control the system or process without the need for constant human attention or adjustment. Now people often talk about “feedback” as begin an essential factor of the new industrial techniques, upon which is base an automatic self-regulating system and by virtue of which any deviation in the system from desired condition can be detected, measured, reported and corrected. when “feedback” is applied to the process by which a large digital computer runs at the immense speed through a long series of sums, constantly rejecting the answers until it finds one to fit a complex set of facts which have been put to it, it is perhaps different in degree from what we have previously been accustomed to machines. But “feedback”, as such, is a familiar mechanical conception. The old-fashioned steam engine was fitted with a centrifugal governor, two balls on levers spinning round and round an upright shaft. If the steam pressure rose and the engine started to go too fast, the increased speed of the spinning governor caused it to rise up the vertical rod and shut down a valve. This cut off some of the steam and thus the engine brought itself back to its proper speed. The mechanization, which was introduced with the Industrial Revolution, because it was limited to individual processes, required the employment of human labor to control each machine as well as to load and unload materials and transfer them from one place to another. Only in a few instances were processes automatically linked together and was production organized as a continuous flow. In general, however, although modern industry has been highly mechanized ever since the 1920s, the mechanized parts have not as a rule been linked together. Electric-light bulbs, bottles and the components of innumerable mass-produced

科普版英语六年级下册课文及翻译 (直接打印版)

Lesson 1 I’m not feeling well. Let’s talk （M=Mom, T= Tom） M: What,'s the matter, Tom T: I'm not feeling well, Mom M: Do you have a cold T: Yes, I think so. Could you give me some water, please M: Here you are. T: Thank you, Mom. M: Tom, you must go and see a doctor. T: OK, Mom. M: It's cold outside. You must wear your coat. T: OK, Mom. Could you pass me my coat,please M: Here you are. T: Thank you, Mom M: Tell me your teacher's number. I'll call him and tell him you are sick. T: OK. Here it is. 译文 (M=妈妈,T=汤姆) 妈妈:怎么了,汤姆 汤姆:我感觉不舒服,妈妈。 妈妈:你感冒了吗 汤姆:是的,我想是这样的。您能给我一些水吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:汤姆,你必须去看医生. 汤姆:好的,妈妈。 妈妈:外面很冷。你必须穿你的外套。 汤姆:好的,妈妈。您能把我的外套递给我吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:告诉我你老师的电话号码。我将给他打电话告诉他你生病了。

英文翻译与英文原文.陈--

翻译文献：INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL （对组合机床滑台动态性能的调查报告） 文献作者：Peter Dransfield, 出处：Peter Dransfield, Hydraulic Control System-Design and Analysis of TheirDynamics, Springer-Verlag, 1981 翻译页数：p139—144 英文译文： 对组合机床滑台动态性能的调查报告 【摘要】这一张纸处理调查利用有束缚力的曲线图和状态空间分析法对组合机床滑台的滑动影响和运动平稳性问题进行分析与研究，从而建立了滑台的液压驱动系统一自调背压调速系统的动态数学模型。通过计算机数字仿真系统，分析了滑台产生滑动影响和运动不平稳的原因及主要影响因素。从那些中可以得出那样的结论，如果能合理地设计液压缸和自调背压调压阀的结构尺寸. 本文中所使用的符号如下： s1-流源，即调速阀出口流量； S el—滑台滑动摩擦力 R一滑台等效粘性摩擦系数： I1—滑台与油缸的质量 12—自调背压阀阀心质量 C1、c2—油缸无杆腔及有杆腔的液容； C2—自调背压阀弹簧柔度； R1, R2自调背压阀阻尼孔液阻， R9—自调背压阀阀口液阻 S e2—自调背压阀弹簧的初始预紧力； I4, I5—管路的等效液感 C5、C6—管路的等效液容： R5, R7-管路的等效液阻； V3, V4—油缸无杆腔及有杆腔内容积； P3, P4—油缸无杆腔及有杆腔的压力 F—滑台承受负载， V—滑台运动速度。本文采用功率键合图和状态空间分折法建立系统的运动数学模型，滑台的动态特性可以能得到显著改善。

英语翻译学习资料(含中英文解释)

例1.Winners do not dedicate their lives to a concept of what they imagine they should be, rather, they are themselves and as such do not use their energy putting on a performance, maintaining pretence and manipulating（操纵） others . They are aware that there is a difference between being loved and acting loving, between being stupid and acting stupid, between being knowledgeable and acting knowledgeable. Winners do not need to hide behind a mask. 1.dedicate to 把时间，精力用于 2.pretence 虚伪，虚假 6 ．1 斤斤于字比句次，措辞生硬 例2.Solitude is an excellent laboratory in which to observe the extent to which manners and habits are conditioned by others. My table manners are atrocious( 丑恶)—in this respect I've slipped back hundreds of years in fact, I have no manners whatsoever（完全，全然）. If I feel like it, I eat with my fingers, or out of a can, or standing up —in other words, whichever is easiest. 孤独是很好的实验室，正好适合观察一个人的举止和习惯在多大程度上受人制约。如今我吃东西的举止十分粗野；这方面一放松就倒退了几百年，实在是一点礼貌也没有。我高兴就用手抓来吃，（eat out of a can）开个罐头端着吃，站着吃；反正怎么省事就怎么吃。 3.Whatsoever 完全，全然 1.Be conditioned by 受……制约 2.Atrocious 丑恶 6 ．2 结构松散，表达过于口语化 例3．有一次，在拥挤的车厢门口，我听见一位男乘客客客气气地问他前面的一位女乘客：“您下车吗？”女乘客没理他。“您下车吗？”他又问了一遍。女乘客还是没理他。他耐不住了，放大声问：“下车吗？”，那女乘客依然没反应。“你是聋子，还是哑巴？”他急了，捅了一下那女乘客，也引起了车厢里的人都往这里看。女乘客这时也急了，瞪起一双眼睛，回手给了男乘客一拳。（庄绎传，英汉翻译教程，1999 ：练习 3 ） 译文1：Once at the crowded door of the bus, I heard a man passenger asked politely a woman passenger before him: “Are you getting off?” The woman made no

英语翻译专业必翻经典文章英文原文参考译文

文档简介 一，英语翻译经典文章之英文原稿二，中文翻译：这篇英语文章的最好翻译版本！不是俺说的，是俺老师说哒！！ 英文原稿Brian It seems my only request (“please, let me sleep”) is not clear enough, so I made this simple table that can help you when you’re in doubt. Especially during the night

中文翻译小子： 我只想好好地睡觉，你不明白吗？！所以，我做了这个简表。当你不知道怎么办时，特 别是在晚上的时候，你可以看看它。 具体情况行动指南 1，我正在睡觉禁止进入 2，你不确定我是否睡觉，你想搞清楚管你“鸟”事；禁止进入 3，你嗑了药，想奔向我的床你他妈的滚远点 4，你在youtube上看了一个超赞的视频，禁止进入；在脸书上把链接发给我想让我看看 5，就算第三次世界大战开始了管我屁事，他妈的别进来 6，你和你的基友们想和我“玩玩”抱歉，直男一枚。不要碰我的任何东西，门都别碰 7，你想整理我的房间我谢谢你了！我自己会打扫 8，普京宣布同性婚姻合法化终于等到“它”！还好你没放弃！还是不要来我房里！ 9，我不在家进我房间，想都别想 10，白天，我在家。你敲了门，我说“请进” 你可以进来了 福利放送！！

如果你已经看到了这里，那么说明你应该是英文爱好者哦。 下面有一些非常实用，我精心整理的英文资料，你一定用得到！快去看看吧！ 一，最常用英语翻译政治文体句型总结大全完美版 二，英文合同翻译最常用句型总结专业版 三，英语毕业论文提纲模板优秀完整详细无敌版

英文翻译原文

南京师范大学泰州学院 英文翻译原文 年级： 2011级学号：12110330 姓名：申佳佳 系部：信息工程学院 专业：通信工程 题目：基于C51的数字测速仪设计与仿真 指导教师：焦蓬蓬 2015 年 4 月 5 日

Linux - Operating system of cybertimes Though for a lot of people , regard Linux as the main operating system to make u p huge work station group, finish special effects of " Titanic " make , already can be re garded as and show talent fully. But for Linux, this only numerous news one of. Rece ntly, the manufacturers concerned have announced that support the news of Linux to i ncrease day by day, users' enthusiasm to Linux runs high unprecedentedly too. Then, Linux only have operating system not free more than on earth on 7 year this piece wh at glamour, get the favors of such numerous important software and hardware manufa cturers as the masses of users and Orac le , Informix , HP , Sybase , Corel , Intel , Net scape , Dell ,etc. , OK? 1.The background of Linux and characteristic Linux is a kind of " free (Free ) software ": What is called free, mean users can o btain the procedure and source code freely , and can use them freely , including revise or copy etc.. It is a result of cybertimes, numerous technical staff finish its research a nd development together through Inte rnet, countless user is it test and except fault , c an add user expansion function that oneself make conveniently to participate in. As th e most outstanding one in free software, Linux has characteristic o f the following: (1)Totally follow POSLX standard, expand the network operating system of sup porting all AT&T and BSD Unix characteristic. Because of inheritting Unix outstandi ng design philosophy , and there are clean , stalwart , high-efficient and steady kernels , their all key codes are finished by Li nus Torvalds and other outstanding programmer s, without any Unix code of AT&T or Berkeley, so Linu x is not Unix, but Linux and Unix are totally compatible. (2)Real many tasks, multi-user's system, the built-in n etwork supports, can be with such seamless links as NetWare , Windows NT , OS/2 , Unix ,etc.. Network in various kinds of Unix it tests to be fastest in comparing and ass ess efficiency. Support such many kinds of files systems as FAT16 , FAT32 , NTFS , E x t2FS , ISO9600 ,etc. at the same time .