自动化专业英语PartⅤ-Ⅵ 课文原文内容

Part Ⅴ

Sensors and Transmitters

In a feedback control system, the elements of a process-control systemare defined interms of separate functional parts of the system . The four basic components of controlsystems are thesensors, transmitter , controller , and final control elements . Thesecomponents per form the three basic operations of every control system: measurementdecision, and action.

Sensors and transmitters perform the measurements operation of control system. Thesensor produces a phenomenon, mechanical, or the like related to the process variable that itmeasures. The function of transmitter in turn is to convert the signal from sensor to the formrequired by the final control device. The signal, therefor e, is related to the process variable.

Two analog standards are in common u se as a means of representing the range ofvariables in control systems. For electrical systems we use a range of electric current carriedin wires , and for pneumatic systems we use a range of gas pressure carried in pipes . Thesesignals are used primarily to transmitvariable information over some distance, such as to andfrom the control room and the plant .Fig .5 . 9 shows a diagram of a process- controlinstallation where current is used to transmit measurement data about the controlled variableto the control room, and gas pressure in pipes is used to transmit a feedback signal to a valve

to change flow as the controlling variable .

Fig .5 .9 Electrical current and pneumatic pressures are the most common means of information transmitter in the industrial environment

Current signal The most common current transmission signal is 4 to 20 mA . Thu s , in

the preceding temperature example, 20℃might be represented by 4 mA, and 120℃by 20 mA, with all temperatures in between represented by a proportional current . The gain is

略

That is , we can say that the gain of sensor/ transmitter is ratio of the span of the output to

the span of input .

Current is used instead of voltage because the system is then les s dependent on load . Voltage is not used for transmission because of its susceptibility to changes of resistance in

the line .

Pneumatic signals The most common standard for pneumatic signal transmitter is 3 to

15 psi . In this case, when a sensor measures some variable in a range it is converted into a proportionalpressure of gas in a pipe . The gas is usually dry air .The pipe may be many hundreds of meters long , but as long as there is no leak in the system the pressure will be propagated down the pipe . This English system standard is still widely used in the U .S ., despite the move to the SI system of units . The equivalent SI range that will eventually be adopted is 20 to 100 kPa.

The two cases presented show that the gain of the sensor/ transmitter is constant over its completeoperating range . For most sensor/ transmitter this is the case; however , there are some in stances , such as a differential pressure sensor used to measure flow, when this is not the case . A differential pressure sensor measures the differential pressure ,h, across an

orifice . This differential pressure is related to the square of the volumetric flow rate F . That

is F2 ah .

The equation that describes the output signal form an electronicdifferential pressure transmitter when used to measure volumetric flow with a range of 0～F maxgpm is

M F = 4 + 16 F2/ ( F max )2

Where MF = output signal in mA

F = Volumetric flow

From this equation the gain of the transmitter is obtained as follows:

K′r = d MF/ d F = 216 F/ ( F max )2

with a nominal gain

K′T = 16/ F max

This expression shows that the gain is not constant but rather a function of flow . T he greater the flow is , the greater the gain . So the actual gain varies from zero to twice the nominal gain .

This fact results in a nonlinearly in flow control system . Nowadays most manufactures

offer differential pressure transmitters with built-in square root extractor s yielding a line r transmitter .

The dynamic response of most sensor/ transmitter s is much faster than the process . Consequently , their time constants and dead time can often beconsidered negligible and

thus , their transfer function is given by a pure gain . However , when the dynamics must be considered , it is usual practice to represent the transfer function of the instrument by a first-orderor second-order system:

G( s) = K / ( T s + 1)

or G( s) = K / ( T2 s + 2 Tξs + 1)

WORDS AND TERMS

3 .1 Numerical Control

Numerical control is a system that uses predetermined instructions to control a sequenceof manufacturing operations. The instructions are coded numerical values stored on sometype of input medium, such as punched paper tape , magnetic tape, or a common memory for program storage . The instructions specify such things as position ,direction , velocity , and cutting speed . A partprogram contains all the instructions required to produce a desired

part . A machine program contains all the instruction s required to accomplish a desired process . Numerical control machines per form operations such as boring , drilling , grinding , milling , punching , routing , sawing , turning , winding ( wire ) , flame cutting , knitting

( garments ) , riveting , bending , welding , and wire processing .

Numerical control ( NC) has been refer red to as flexible automation because of the

relative ease of changing the program compared with changing cams , jigs , and templates .

The same machine may be used to produce any number of different parts by using different programs . The numerical control process is most justified when a number of different parts

are to be produced on a particular machine: it is seldom used to produce a single par t continually on the same machine . Numerical control is ideal when a part or process is defined mathematically . With the increasing u se of computer- aided design (CAD) , more and more processes and products are being defined mathematically . Drawings as we k now them have become unnecessary ―a part that is completely defined mathematically can be manufactured

by computer-controlled machines . A closed-loop numerical control machine is shown in Fig .

5 .13 .

The NC process begins with a specification ( engineering drawing or mathematical

definition ) that completely defines the desired par t or process . A programmer uses the specification to determine the sequence of operations necessary to produce the par t or carry out the process . The programmer also specifies the tools to be used , the cutting speeds , and the feed rates . The programmer uses a special programming language to prepare a symbolic program . APT ( Automatically Programmed Tools ) is one language used for this purpose . A computer converts the symbolic program into the part program or the machine program . In the past , the pa r t or machine program was stored on paper or magnetic t ape . The numerical control machine operator fed the tape into the machine and monitored the operation . If a change was necessary , a new tape had to be made . Now, it is possible to store the program

in a common database with provision for on-demand distribution to the numerical control machine . Graphicterminals at the matching center allow operators to review programs and make changes if necessary .

The x position controller moves the work piece horizontally in the direction indicated by

the + x a r row . The position controller moves the milling machine head horizontally in the direction indicated by the + yarrow . The z position controller moves the cutting tool vertically as indicated by the + z arrow . The following actions are involved in changing the x-axis position .( 1 ) The control unit reads an instruction in the program that specifies a

+ 0 .004-inch ( in .) change in the x position . ( 2 ) The control unit send s a pulse to the machine actuator . (3 ) The machine actuator rotates the lead screw and advances the x- axis position + 0 .001 in . (4 ) the position sensor measures the + 0 .001-in . measured motion and sends another pulse . Steps ( 1 ) through ( 5 ) are repeated until the measured motion equals the desired + 0 .004 in .

Computerized numerical control ( CNC ) was developed to utilize the storage and

processing capabilities of a digital computer . CNC uses a dedicated computer to accept the input of instructions and to perform the control functions required to produce the part . However , CNC was not designed to provide the information exchange demanded by the recent t r end toward computer-integrated manufacturing (CIM) . The idea of CIM is to“get the right information- to the right person- at the right time- to make the right decision .”“I t link s all aspects of the business-f rom quotation and order entry through engineering , process planning , financial reporting , manufacturing , and shipping-in an efficient chain of production .”

Direct numerical control ( DNC ) was developed to facilitate computer-integrated manufacturing . DNC is a system in which a n umber of numerical control machines are connected to a central computer for real- time access to a common database of part programs and machine programs . General Electric used a central computer connected to DNC machines through a communication s network in the automation of its steam turbine-generator operation s (STGO) .“A typical turbine-genera tor consists of more than 100 , 000 parts , some

of which are manufactured in thousands of different configurations to meet the specific needs of each custom-designed unit . Through the CIM system, customers can specify a needed par t and receive replacement components that suit the original configuration of more than 4 , 000 operating STGO installations . In some cases , the small-parts shop can now manufacture and ship some emergency parts the same day the order is received .”

4 .1 Relay Controllers

An industrial control system typically involves electric motors , solenoids , heaters or

cooler , and other equipment that is operated from the ac power line . Thus , when a control system specifies that a“conveyor motor be turned on ,”it may mean starting a 50-HP motor . This is not done by a simple toggle switch .Instead , one would logically assume that a small switch may be used to energize a relay with contact ratings that can handle the heavy load , such as that shown in Fig .5 .16 . In this way , the relay became the primary control element

of discrete-state control systems .

When an entire control system is implemented u sing relays , the system is called a relay sequencer . A relay sequencer consists of a combination of many relays , including special

time-delay types , wired up to implement the specified sequence of events . Inputs are switches and push buttons that energize relay , and outputs are closed contacts that can turn lights on or off , start motor s , energize solenoids , and so on .

The wiring of a relay control system can be described by traditional schematic diagrams ,

such as those shown in Fig .5 .16 . Such diagrams are cumbersome , however , when many relays , each with many contacts , are used in a system . Simplified diagrams have been gradually adopted by the industry over the years . As an example of such simplification , a relay’s contacts need not be placed directly over the coil symbol , but can go anywhere in the circuit diagram with a number to associate them with a particular coil . These simplifications resulted in the ladder diagram in use today .

Ladder Diagrams

The ladder diagram is a symbolic and schematic way of representing both the system hardware and the process controller . It is called a ladder diagram because the various circuit devices connected in parallel across the ac line form something that looks like a ladder , with each parallel connection a“rung”on the ladder

In the construction of a ladder diagram , it is understood that each rung of the ladder is composed of a number of conditions or input states and a single command output . The nature of the input states determines whether the output is to be energized or not energized . T he following example illustrates many features of a ladder diagram construction and its application to control problems .

Example: The elevator shown in Fig .5 .17 employs a platform to move objects up and

down . The global objective is that when the UP button is pushed , the platform carries

something to the up position , and when the DOWN but ton is pushed , the plat form carries something to the down position .

The following hardware specifications defined the equipment used in the elevator :

Output elements:

M1 = Motor to drive the platform up

M2 = Motor to drive the platform down

Input elements:

LS1 = NC limit switch to indicate UP position

LS2 = NC limit switch to indicate DOWN position

ST ART = NO push button for START

STOP = NO push button for STOP

UP = NO push button for UP command

DOWN = No pus h but ton for DOWN command

The following narrative description indicates the required sequence of events for theelevator system .

1 .When the START but ton is pushed , the platform is driven to the down position .

2 .When the STOP button is pushed , the platform is halted at whatever position it

occupies at that time .

3 .When the UP button is pushed , the platform, if it is not in downward motion , is

driven to the up position .

4 .When the DOWN but ton is pushed , the platform, if it is not in upward motion , is

driven to the down position .

Prepare a ladderdiagram to implement this control function .

Solution

Let us prepare a solution by breaking the requirements into individual tasks . For

example, the firsttask is to move the platform to the down position when the START

but ton is pushed .

This task can be done by using the START but ton to latch a relay , whose contacts also energize M2 ( the down motor ) . The relay is released , stopping M2 , when the LS2 limit

switch open s . Pushing START energizes CR1 if L S2 is not open ( platform not down ) .CR1

is latched by the contacts across the START button . Another set of CR1 contacts starts M2

to drive the platform down . When L S2 opens , indicating the full down position has been reached ,CR1 is released , unlatched , and M2 stops . These two rungs will operate only when

the START button is pushed .

For the STOP sequence , let us assume a relay CR3 is the master control for the rest of

the system . Because STOP is a NO switch , we cannot use it to release CR3 . Instead , we use STOP to energize another relay ,CR2 , and use the NC contacts of that relay to release CR3 .

This is shown in Fig .5 .18 . You can see that when START is pushed ,CR3 in rung 4 is

energized by the latching of the CR1 contact and the NC contact of CR2 . When STOP is

pushed ,CR2 in rung 3 is energized , which causes the NC contact in rung 4 to open and

release CR3 .

Finally , we come to the sequences for up and down motion of the platform . In each

case, a relay is latched to energize a motor if CR3 is energized , the appropriate button has

been pushed , the limit has not been reached , and the other direction is not energized . T he entire ladder diagram is shown in Fig .5 .17 . A NC relay connection is used to ensure that the

up motor is not turned on if the down motor is on , and vice versa . Also , it was necessary to add a contact to rung 2 to be sure M2 could not star t if there was up motion and some joke r pushed the START button .

Part Ⅵ

1.1Transmission of Electrical Energy

Electrical energy is carried by conductors such as overhead transmission lines and underground cable . Although these conductors appear very ordinary , they possess

important electrical proper ties that greatly affect the transmission of electrical energy . In this section , we study these proper ties for several types of transmission lines: high volt age , low-voltage, high-power , aerial lines , and underground lines .

Principal components of a power distribution system

In order to provide electrical energy to consumers in usable form, a transmission and distribution system must satisfy some basic requirements . Thu s the system must

1 .Provide, at all times , the power that consumers need

2 .Maintain a stable, nominal voltage that does not vary by more than±10%

3 .Maintain a stable frequency that does not vary by more than±0 .1 Hz

4 .Supply energy at an acceptable price

5 .Meet standards of safety

6 .Respect environmental standards .

Fig .6 .1 shows an elementary diagram of a transmission and distribution system .I t

consists of two genera ting station s G1 and G2 , a few substations , an inter connecting substation and several commercial , residential , and industrial loads . The energy is carried

over lines designated extra-high voltage ( EH V ) , high volt age ( H V ) , medium voltage

(MV) , and low voltage ( LV ) . This voltage classification is made according to a scale of standardized voltage .

Transmission substations ( Fig .6 .1 ) serve to change the line voltage by mean s of step-up

and step-down transformers and to regulator it by means of static vary compensators , synchronous condensers , or transformers with variable taps .

Distribution substations change the medium voltage to low voltage by means of step-down transformers , which may have automatic tap-changing capabilities to regulate the low

voltage . The low voltage ranges from 120/ 240V single phase to 600V, 3-phase . I t serves to power private residences , commercial and institutional establishments , and small industry .

Interconnecting substations serve to tie different power systems together , to enable

power exchanges between them, and to increase the stability of the overall network .

These sub stations also contain circuit breakers , fuses , and lightning arresters , to

protect expensive apparatus , and to provide for quick isolation of faulted lines from the system . In addition , control apparatus , power measuring devices , disconnect switches , capacitors , inductors , and other devices may be part of a substation .

Electrical power utilities divide their power distribution systems into two major categories:

1 .Transmission systems in which the line voltage is roughly between 115kVand 800kV .

2 .Distribution systems in which the voltagegenerally lies between 120V and 69kV .

Distribution systems , in turn , are divided into medium-voltage distribution systems ( 2 .4kV to 69 kV ) and low-voltage distribution systems (120V to 600V) .

Type of power lines

The design of a power line depends upon the following:

1 .The amount of active power it has to transmit

2 .The distance over which the power must be carried

3 .The cost of the power line

4. Esthetic considerations , urban congestion , ease of installation , and expected

load growth

We distinguish four types of power lines ,according to their voltage class:

1 .Low- voltage ( L V) lines provide power to buildings , factories , and houses to drive motors , electric stoves , lamps , heater s , and air conditioners . The lines are insulated conductors , usually made of aluminum, often extending from a local pole-mounted distribution transformer to the service entrance of the consumer . The lines may be overhead or underground , and the transformer behaves like a miniature substation .

2 .Medium- voltage ( MV) lines tie the load centers to one of the many substation s of the utility company . The voltage is usually between 2 .4kV and 69kV . Such medium-voltage radial distribution systems are preferred in the larger cities . In radial systems the transmission lines spread out like fingers from one or more substation s to feed power to various load centers , such as high- rise buildings , shopping centers , and colleges .

3 .High-voltage ( H V) lines connect the main substations to the generating stations .

T he lines are composed of aerial wire or underground cable operating at voltages below 230kV . In this category we also find lines that transmit energy between two power systems , to increase the stability of the network .

4 .Extra-high- voltage ( E H V) lines are used when gene rating stations are very far from

the load centers . We put these lines in a separate class because of their special electrical

properties . Such lines operate a t volt ages up to 800kV and may be as long as 1, 000 km .

Components of a HV transmission line

A transmission line is composed of conductors , insulators , and supporting structures . Conductors . Conductors for high-volt age lines are always bare . Stranded copper conductors , or steel-reinforced aluminum cable ( ACSR ) are used . ACSR conductor s are usually prefer red because they result in a lighter and more economical line . Conductor s have to be spliced when a line is very long . Special care must be taken so that the joints have low resistance and great mechanical strength .

Insulators . Insulators serve to support and anchor the conductors and to insulate them

from ground . Insulators areusually made of porcelain , but glass and other synthetic insulating materials are also used .

Supporting structures . The supporting structure must keep the conductors at a safe

height from the ground and at an adequate distance from each other . For voltages below

70 kV, we can use single wooden poles equipped with cross-arms , but for higher voltages , twopoles are used to create an H-frame, the wood is treated with creosote or special metallic salts to prevent it from rot ting . For very high-voltage lines, we always use steel towers made of galvanized angle-iron pieces that are bolted together .

The spacing between conductors must be sufficient to prevent arc-over under gusty wind conditions . The spacing has to be increased as the distance between towers and as the line voltages become higher .

Construction of a line

Once we know the conductor size, the height of the poles , and the distance between the poles ( span ) , we can direct our attention to stringing the conductor s . A wire supported between two points ( Fig . 6 .2 ) does not remain horizontal , but loops down at the middle . The vertical distance between the straight line joining the points of support and the lowest point of the conductor is called sag . The tighter the wire, the smaller the sag will be .

Before under taking the actual construction of a line it is important to calculate the permissible sag and the corresponding mechanical pull . Among other things , the summer to winter temperature range must be taken into account because the length of the conductor varies with the temperature . Thus , if the line is strung in the winter , the sag must not be

too great , otherwise the wire will stretch even more during the summer heat , with the result that the clearance to ground may no longer be safe . On the other hand , if the line is installed in the summer , the sag must not be too small otherwise the wire , contracting in winter , may become so dangerously tight as to snap . Wind and sleet add even more to the tractive force, whichmay also cause the wire to break .

2 .1 Grounding and Ground-Fault Protection

T he importance of proper grounding for elect rical systems in buildings is often

under estimated . Unde r normal conditions , an elect rical system can continue to ope rate satisfactorily ( that is , deliver power to the utilization equipment ) even without prope r grounding . It is not until an abnormal condition has occur red , and after eithe r someone has been injured, equipment has been damaged , or a fir e has been star ted , that it is realized that imprope r or faulty grounding was the r eason . T her efore, a good understanding of the functions of grounding is essential for the proper design , in stallation , and maintenance of an electrical system . In most cases , the con nection is made by direct metallic contact with

earth . The large mass of the ear th then serves as a zero potential r eferencepoint .

T he study of grounding must begin by identifying the differ ent aspects of grounding:

system grounding , equipment grounding lightning protection grounding , and static

electricity grounding . Fig .6 .4 shows the basic difference between system grounding and equipmentgrounding .System grounding is the intentional elect rical connection to ground of one of the cur r ent- car rying conductors of the elect ricalsystem . Equipment grounding is the connection to ground of all the nonelectrical conductive materials that enclose or ar e adjacent to the energized conductor s . T he electrical code r equires that all equipment must be prope rly grounded , except in very ra re special cases . However , the application of system grounding is not so universal . Certain types of systems , such as the 120/ 240 volt , single-phase, threewire and the 208Y/ 120 volt , three-phase, four-wire syst ems used to supply lighting have

always been grounded . On the other hand , the 480 and 600 volt , three-phase syst ems used

to supply loads such as motor s have until recently us ually been operated ungrounded .

①System grounding . The intentional connection to grounding of one of the current-carrying conductions

of the system .

②Equipment grounding . The connection to grounding of all the nonelectrical conductive ma terials that

enclose or ar e adjacent to the energized conductors .

T he primary purpose for grounding an electrical system is one of safety, that is , to limit

the potential to ground that otherwise could occur f rom accidental contact with highervoltage syst ems or f rom t ransientovervoltages . However ,ther e ar e other important benefits associa ted with grounded sy stems , as follows :

1 .Se rvice r eliability is improved: The transient over voltage condition s tha t a re possible

with ungrounded systems cannot occur . With the elimination of this overvolt age stressing of the ins ulation , fewer ground faults should occur ove r the operating life of grounded sy stems .

2 .Much simpler to locate the first ground fault : With proper coordination , the

overcur rent device ( circuit breake r or fuse ) near est to the fault operates to disconnect the faultedcircuit , thu s leaving the balance of the system operating .

3 .Ground-fault protection can be easily added: Arcing ground faults can be difficult to

detect and therefore require special attention .

4 .Provides two voltage levels on the same system: Single-phase loads such as lighting can be connected across the line- to-neutral voltage (120 volts on a 208Y/ 120 volt system) . Three-phase loads such as motors can then be connected across the line- to-line voltages (208 volts) .

As is the case with most arrangements ,ther e a re some drawbacks to the use of

grounded systems , as follows :

1 .T he fir st ground fault r esults in the immediate s hutdown of par t of the system .

2 .T he re can be very high ground- fault cur rents on bolt ed-type faults . These large

cur rents must flow over the equipment grounding circuit .

Protective relay

T he protective relay is defined as a device that causes an abrupt change in an elect rical

control circuit when the measured quantity to which it responds changes in a prescribed manner .T he elect ricalcontrol circuit is usually the t rip circuit of a circuit breaker , and the measured quantity is the powe r circuit cur rent and/ or voltage as r epresented by the instrument t ransformer s .

Protective r elays can be divided into two fundament al types elect romechanical relays and solid-state r elays . Elect romechanical r elays have been the standard for many year s and , in spite of the development of the newer solid-state units , ar e still widely used because of their proven r eliability . Solid- st ate units , since they have no moving par ts , have gr eater accuracy andfaste r reset times than elect romagnetic relays . However , solid-state relays have the drawback that they can initiat e false tripping of the circuit breaker s becau se they may imprope rly react to spurious t ransient voltage spikes . These transientvoltages , which may only last for a few microseconds , can be the r esult of disruption on the power system, such

as the switching of a powe r circuit . A solid-star e relay must have a filtering system that

blocks any chance of these transient conditions f rom t riggering any of its detection circuits . Electromagnetic relays , on the othe r hand , are inherently immune to t ransient disturbances . Solid-state r elays can offer the same operating cha racteristicsand , in fact , usually use the same type of hou sing and t erminalar r angements , so they ar e virtually inter changeable with electromagnetic units .

《土木工程专业英语》段兵延第二版全书文章翻译精编版

第一课 土木工程学土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。 土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。他们也建造私有设施，比如飞机场，铁路，管线，摩天大楼，以及其他设计用作工业，商业和住宅途径的大型结构。此外，土木工程师还规划设计及建造完整的城市和乡镇，并且最近一直在规划设计容纳设施齐全的社区的空间平台。 土木一词来源于拉丁文词“公民”。在1782年，英国人John Smeaton为了把他的非军事工程工作区别于当时占优势地位的军事工程师的工作而采用的名词。自从那时起，土木工程学被用于提及从事公共设施建设的工程师，尽管其包含的领域更为广阔。 领域。因为包含范围太广，土木工程学又被细分为大量的技术专业。不同类型的工程需要多种不同土木工程专业技术。一个项目开始的时候，土木工程师要对场地进行测绘，定位有用的布置，如地下水水位，下水道，和电力线。岩土工程专家则进行土力学试验以确定土壤能否承受工程荷载。环境工程专家研究工程对当地的影响，包括对空气和地下水的可能污染，对当地动植物生活的影响，以及如何让工程设计满足政府针对环境保护的需要。交通工程专家确定必需的不同种类设施以减轻由整个工程造成的对当地公路和其他交通网络的负担。同时，结构工程专家利用初步数据对工程作详细规划，设计和说明。从项目开始到结束，对这些土木工程专家的工作进行监督和调配的则是施工管理专家。根据其他专家所提供的信息，施工管理专家计算材料和人工的数量和花费，所有工作的进度表，订购工作所需要的材料和设备，雇佣承包商和分包商，还要做些额外的监督工作以确保工程能按时按质完成。 贯穿任何给定项目，土木工程师都需要大量使用计算机。计算机用于设计工程中使用的多数元件（即计算机辅助设计，或者CAD）并对其进行管理。计算机成为了现代土木工程师的必备品，因为它使得工程师能有效地掌控所需的大量数据从而确定建造一项工程的最佳方法。 结构工程学。在这一专业领域，土木工程师规划设计各种类型的结构，包括桥梁，大坝，发电厂，设备支撑，海面上的特殊结构，美国太空计划，发射塔，庞大的天文和无线电望远镜，以及许多其他种类的项目。结构工程师应用计算机确定一个结构必须承受的力：自重，风荷载和飓风荷载，建筑材料温度变化引起的胀缩，以及地震荷载。他们也需确定不同种材料如钢筋，混凝土，塑料，石头，沥青，砖，铝或其他建筑材料等的复合作用。 水利工程学。土木工程师在这一领域主要处理水的物理控制方面的种种问题。他们的项目用于帮助预防洪水灾害，提供城市用水和灌溉用水，管理控制河流和水流物，维护河滩及其他滨水设施。此外，他们设计和维护海港，运河与水闸，建造大型水利大坝与小型坝，以及各种类型的围堰，帮助设计海上结构并且确定结构的位置对航行影响。 岩土工程学。专业于这个领域的土木工程师对支撑结构并影响结构行为的土壤和岩石的特性进行分析。他们计算建筑和其他结构由于自重压力可能引起的沉降，并采取措施使之减少到最小。他们也需计算并确定如何加强斜坡和填充物的稳定性以及如何保护结构免受地震和地下水的影响。 环境工程学。在这一工程学分支中，土木工程师设计，建造并监视系统以提供安全的饮用水，同时预防和控制地表和地下水资源供给的污染。他们也设计，建造并监视工程以控制甚至消除对土地和空气的污染。他们建造供水和废水处理厂，设计空气净化器和其他设备以最小化甚至消除由工业加工、焚化及其他产烟生产活动引起的空气污染。他们也采用建造特殊倾倒地点或使用有毒有害物中和剂的措施来控制有毒有害废弃物。此外，工程师还对垃圾掩埋进行设计和管理以预防其对周围环境造成污染。

土木工程专业英语全部

Lesson 1 Compression Members New Words 1. achieve achievement 2. eccentricity center, 中心; ec centric 偏心的；ec centricity 偏心，偏心距 3. inevitable evitable 可避免的avoidable; in evitable 不可避免的unavoidable 4. truss 桁架triangular truss, roof truss, truss bridge 5. bracing brace 支柱，支撑；bracing, 支撑，撑杆 6. slender 细长，苗条；stout; slenderness 7. buckle 压曲，屈曲；buckling load 8. stocky stout 9. convincingly convince, convincing, convincingly 10. stub 树桩，短而粗的东西；stub column 短柱 11. curvature 曲率；curve, curvature 12. detractor detract draw or take away; divert; belittle，贬低，诽谤； 13. convince 14. argument dispute, debate, quarrel, reason, 论据（理由） 15. crookedness crook 钩状物，v弯曲，crooked 弯曲的 16. provision 规定，条款 Phrases and Expressions 1. compression member 2. bending moment shear force, axial force 3. call upon (on) 要求，请求，需要 4. critical buckling load 临界屈曲荷载critical 关键的，临界的 5. cross-sectional area 6. radius of gyration 回转半径gyration 7. slenderness ratio 长细比 8. tangent modulus 切线模量 9. stub column 短柱 10. trial-and-error approach 试算法 11. empirical formula 经验公式empirical 经验的 12. residual stress 残余应力residual 13. hot-rolled shape 热轧型钢hot-rolled bar 14. lower bound 下限upper bound 上限 16. effective length 计算长度 Definition （定义） Compression members are those structural elements that are subjected only to axial compressive forces: that is, the loads are applied along a longitudinal axis through the centroid of the member cross section, and

自动化专业英语常用词汇

自动化专业英语常用词汇 acceleration transducer 加速度传感器 accumulated error 累积误差 AC-DC-AC frequency converter交-直-交变频器 AC (alternating current) electric drive 交流电子传动 active attitude stabilization 主动姿态稳定 adjoint operator 伴随算子 admissible error 容许误差 amplifying element 放大环节 analog-digital conversion 模数转换 operational amplifiers运算放大器 aperiodic decomposition 非周期分解 approximate reasoning 近似推理 a priori estimate 先验估计 articulated robot 关节型机器人 asymptotic stability 渐进稳定性 attained pose drift 实际位姿漂移 attitude acquisition 姿态捕获 AOCS (attitude and orbit control system) 姿态轨道控制系统attitude angular velocity 姿态角速度 attitude disturbance 姿态扰动 automatic manual station 自动-手动操作器 automaton 自动机 base coordinate system 基座坐标系 bellows pressure gauge 波纹管压力表 gauge测量仪器

土木工程专业英语正文课文翻译

第一课土木工程学 土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。 土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。他们也建造私有设施，比如飞机场，铁路，管线，摩天大楼，以及其他设计用作工业，商业和住宅途径的大型结构。此外，土木工程师还规划设计及建造完整的城市和乡镇，并且最近一直在规划设计容纳设施齐全的社区的空间平台。 土木一词来源于拉丁文词“公民”。在1782年，英国人John Smeaton为了把他的非军事工程工作区别于当时占优势地位的军事工程师的工作而采用的名词。自从那时起，土木工程学被用于提及从事公共设施建设的工程师，尽管其包含的领域更为广阔。 领域。因为包含范围太广，土木工程学又被细分为大量的技术专业。不同类型的工程需要多种不同土木工程专业技术。一个项目开始的时候，土木工程师要对场地进行测绘，定位有用的布置，如地下水水位，下水道，和电力线。岩土工程专家则进行土力学试验以确定土壤能否承受工程荷载。环境工程专家研究工程对当地的影响，包括对空气和地下水的可能污染，对当地动植物生活的影响，以及如何让工程设计满足政府针对环境保护的需要。交通工程专家确定必需的不同种类设施以减轻由整个工程造成的对当地公路和其他交通网络的负担。同时，结构工程专家利用初步数据对工程作详细规划，设计和说明。从项目开始到结束，对这些土木工程专家的工作进行监督和调配的则是施工管理专家。根据其他专家所提供的信息，施工管理专家计算材料和人工的数量和花费，所有工作的进度表，订购工作所需要的材料和设备，雇佣承包商和分包商，还要做些额外的监督工作以确保工程能按时按质完成。 贯穿任何给定项目，土木工程师都需要大量使用计算机。计算机用于设计工程中使用的多数元件（即计算机辅助设计，或者CAD）并对其进行管理。计算机成为了现代土木工程师的必备品，因为它使得工程师能有效地掌控所需的大量数据从而确定建造一项工程的最佳方法。 结构工程学。在这一专业领域，土木工程师规划设计各种类型的结构，包括桥梁，大坝，发电厂，设备支撑，海面上的特殊结构，美国太空计划，发射塔，庞大的天文和无线电望远镜，以及许多其他种类的项目。结构工程师应用计算机确定一个结构必须承受的力：自重，风荷载和飓风荷载，建筑材料温度变化引起的胀缩，以及地震荷载。他们也需确定不同种材料如钢筋，混凝土，塑料，石头，沥青，砖，铝或其他建筑材料等的复合作用。 水利工程学。土木工程师在这一领域主要处理水的物理控制方面的种种问题。他们的项目用于帮助预防洪水灾害，提供城市用水和灌溉用水，管理控制河流和水流物，维护河滩及其他滨水设施。此外，他们设计和维护海港，运河与水闸，建造大型水利大坝与小型坝，以及各种类型的围堰，帮助设计海上结构并且确定结构的位置对航行影响。 岩土工程学。专业于这个领域的土木工程师对支撑结构并影响结构行为的土壤和岩石的特性进行分析。他们计算建筑和其他结构由于自重压力可能引起的沉降，并采取措施使之减少到最小。他们也需计算并确定如何加强斜坡和填充物的稳定性以及如何保护结构免受地震和地下水的影响。 环境工程学。在这一工程学分支中，土木工程师设计，建造并监视系统以提供安全的饮用水，同时预防和控制地表和地下水资源供给的污染。他们也设计，建造并监视工程以控制甚至消除对土地和空气的污染。

土木工程专业英语词汇(整理版)

第一部分必须掌握，第二部分尽量掌握 第一部分： 1 Finite Element Method 有限单元法 2 专业英语Specialty English 3 水利工程Hydraulic Engineering 4 土木工程Civil Engineering 5 地下工程Underground Engineering 6 岩土工程Geotechnical Engineering 7 道路工程Road (Highway) Engineering 8 桥梁工程Bridge Engineering 9 隧道工程Tunnel Engineering 10 工程力学Engineering Mechanics 11 交通工程Traffic Engineering 12 港口工程Port Engineering 13 安全性safety 17木结构timber structure 18 砌体结构masonry structure 19 混凝土结构concrete structure 20 钢结构steelstructure 21 钢-混凝土复合结构steel and concrete composite structure 22 素混凝土plain concrete 23 钢筋混凝土reinforced concrete 24 钢筋rebar 25 预应力混凝土pre-stressed concrete 26 静定结构statically determinate structure 27 超静定结构statically indeterminate structure 28 桁架结构truss structure 29 空间网架结构spatial grid structure 30 近海工程offshore engineering 31 静力学statics 32运动学kinematics 33 动力学dynamics 34 简支梁simply supported beam 35 固定支座fixed bearing 36弹性力学elasticity 37 塑性力学plasticity 38 弹塑性力学elaso-plasticity 39 断裂力学fracture Mechanics 40 土力学soil mechanics 41 水力学hydraulics 42 流体力学fluid mechanics 43 固体力学solid mechanics 44 集中力concentrated force 45 压力pressure 46 静水压力hydrostatic pressure 47 均布压力uniform pressure 48 体力body force 49 重力gravity 50 线荷载line load 51 弯矩bending moment 52 torque 扭矩53 应力stress 54 应变stain 55 正应力normal stress 56 剪应力shearing stress 57 主应力principal stress 58 变形deformation 59 内力internal force 60 偏移量挠度deflection 61 settlement 沉降 62 屈曲失稳buckle 63 轴力axial force 64 允许应力allowable stress 65 疲劳分析fatigue analysis 66 梁beam 67 壳shell 68 板plate 69 桥bridge 70 桩pile 71 主动土压力active earth pressure 72 被动土压力passive earth pressure 73 承载力load-bearing capacity 74 水位water Height 75 位移displacement 76 结构力学structural mechanics 77 材料力学material mechanics 78 经纬仪altometer 79 水准仪level 80 学科discipline 81 子学科sub-discipline 82 期刊journal ,periodical 83文献literature 84 ISSN International Standard Serial Number 国际标准刊号 85 ISBN International Standard Book Number 国际标准书号 86 卷volume 87 期number 88 专着monograph 89 会议论文集Proceeding 90 学位论文thesis, dissertation 91 专利patent 92 档案档案室archive 93 国际学术会议conference 94 导师advisor 95 学位论文答辩defense of thesis 96 博士研究生doctorate student 97 研究生postgraduate 98 EI Engineering Index 工程索引 99 SCI Science Citation Index 科学引文索引 100ISTP Index to Science and Technology Proceedings 科学技术会议论文集索引 101 题目title 102 摘要abstract 103 全文full-text 104 参考文献reference 105 联络单位、所属单位affiliation 106 主题词Subject 107 关键字keyword 108 ASCE American Society of Civil Engineers 美国土木工程师协会 109 FHWA Federal Highway Administration 联邦公路总署

土木工程专业英语课文原文及对照翻译

土木工程专业英语课文原 文及对照翻译 Newly compiled on November 23, 2020

Civil Engineering Civil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities. 土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。 Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities. 土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。他们也建造私有设施，比如飞机场，铁路，管线，摩天大楼，以及其他设计用作工业，商业和住宅途径的大型结构。此外，土木工程师还规划设计及建造完整的城市和乡镇，并且最近一直在规划设计容纳设施齐全的社区的空间平台。 The word civil derives from the Latin for citizen. In 1782, Englishman John Smeaton used the term to differentiate his nonmilitary engineering work from that of the military engineers who predominated at the time. Since then, the term civil engineering has often been used to refer to engineers who build public facilities, although the field is much broader 土木一词来源于拉丁文词“公民”。在1782年，英国人John Smeaton为了把他的非军事工程工作区别于当时占优势地位的军事工程师的工作而采用的名词。自从那时起，土木工程学被用于提及从事公共设施建设的工程师，尽管其包含的领域更为广阔。 Scope. Because it is so broad, civil engineering is subdivided into a number of technical specialties. Depending on the type of project, the skills of many kinds of civil engineer specialists may be needed. When a project begins, the site is surveyed and mapped by civil engineers who locate utility placement—water, sewer, and power lines. Geotechnical specialists perform soil experiments to determine if the earth can bear the weight of the project. Environmental specialists study the project’s impact on the local area: the potential for air and

土木工程专业英语

non-destructive test 非破损检验 non-load—bearingwall 非承重墙 non—uniform cross—section beam 变截面粱 non—uniformly distributed strain coefficient of longitudinal tensile reinforcement 纵向受拉钢筋应变不均匀系数 normal concrete 普通混凝土 normal section 正截面 notch and tooth joint 齿连接 number of sampling 抽样数量 O obligue section 斜截面 oblique—angle fillet weld 斜角角焊缝 one—way reinforced(or prestressed)concrete slab “单向板” open web roof truss 空腹屋架， ordinary concrete 普通混凝土(28) ordinary steel bar 普通钢筋(29) orthogonal fillet weld 直角角焊缝(61) outstanding width of flange 翼缘板外伸宽度(57) outstanding width of stiffener 加劲肋外伸宽度(57) over-all stability reduction coefficient of steel beam·钢梁整体稳定系数(58) overlap 焊瘤(62) overturning or slip resistance analysis 抗倾覆、滑移验算(10) P padding plate 垫板(52) partial penetrated butt weld 不焊透对接焊缝(61) partition 非承重墙(7) penetrated butt weld 透焊对接焊缝(60) percentage of reinforcement 配筋率(34) perforated brick 多孔砖(43) pilastered wall 带壁柱墙(42) pit·凹坑(62) pith 髓心(?o) plain concrete structure 素混凝土结构(24) plane hypothesis 平截面假定(32) plane structure 平面结构(11) plane trussed lattice grids 平面桁架系网架(5) plank 板材(65) plastic adaption coefficient of cross—section 截面塑性发展系数(58) plastic design of steel structure 钢结构塑性设计(56) plastic hinge·塑性铰(13) plastlcity coefficient of reinforced concrete member in tensile zone 受拉区混凝土塑性影响系数

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