M. Ibbotson - Professional english in use engineering (794233), страница 28
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This is the power of theengine measured at the engine's output shaft. The word 'brake' comes from the techniqueused to measure engine power in the past. In power tests, a brake was applied to the outputshaft to resist the torque of the engine. The amount of braking force required to do this wasmeasured.Degrees FahrenheitThe following calculations can be used to convert degrees Fahrenheit (°F) to degrees Celsius0( C), and vice versa:°C = (°F - 32)°F = (°CXX5/99/5) + 32Professional English in Use EngineeringI 03III 04Chemical elementsElementSymbolElementSymbolactiniumAcfermiumFmaluminium (BrE) I aluminum (ArnE)AIfluorineFamencmmAmfranciumFrantimonySbgadoliniumGdargonArgalliumGaarserucAsgermamumGeastatineAtgoldAubariumBahafniumHfberkeliumBkhassiumHsberylliumBeheliumHebismuthBiholmiumHobohriumBhhydrogenHboronBindiumInbromineBriodineIcadmiumCdiridiumIrcaesium (BrE) I cesium (ArnE)CstrODFecalciumCakryptonKrcaliforniumCflanthanumLacarbonclawrenciumLrcenumCeleadPhchlorineCllithiumLichromiumCrlutetiumLucobaltComagnesiumMgcopperCumanganeseMncuriumCmmeitneriumMtdarmstadtiumDsmendeleviumMddubniumDbmercuryHgdysprosiumDymolybdenumMoeinsteiniumEsneodymiumNderbiumErneonNeeuropiumEuneptuniumNpProfessional English in Use EngineeringElementSymbolElementSymbolnickelNisulphur (BrE) I sulfur (ArnE)sniobiumNbtantalumTanitrogenNtechnetiumTcnobeliumNotelluriumTeosmmmOsterbiumTboxygen0thalliumTlpalladiumPdthoriumThphosphoruspthuliumTmplatinumPttinSnplutoniumPutitaniumTipoloniumPotungstenwpotassiumKurantumpraseodymiumPrvanadiumuvpromethiumPmxenonXeprotactiniumPaytterbiumYbradiumRayttriumyradonRnzincZnrheniumRezirconiumZrrhodiumRhroentgeniumRgrubidiumRbrutheniumRurutherfordiumRfsamanumSmscandiumScseaborgiumSgseleniumSesiliconSisilverAgsodiumNastrontiumSrProfessional English in Use EngineeringlOSStructural elements and types of loadCommon structural elementsThe table below lists the structural elements commonly found in large structures, in:•the substructure- elements situated below ground level (below the ground)•the superstructure - elements situated above ground level.ElementDescriptionfoundationan element in the ground, usually made of concrete, which transmits loadsfrom a structure to the soil or rocks in the ground below itpad foundationa square foundation - usually supports a columnstrip foundationa long, narrow foundation- usually supports a wallraft foundationa large rectangular foundation which covers the entire area of the buildingthat it supports - effectively a thick slab which acts as a foundationpilea vertical column of concrete below the ground which provides a strongfoundation- may be cast in-situ by pouring concrete into a hole that hasbeen bored (drilled), or may be precast and driven (hammered) into thegroundpile capa block of concrete, at ground level, built directly on top of a pile or pilecluster (several piles close together) to provide a flat foundation- for acolumn, for exampleground beama concrete beam at ground level which connects two pile caps- pilefoundations often consist of a network of ground beams connecting anumber of pile capsbasementone or more floors of a building situated below ground level, surroundedby wallsretaining walla wall which supports earth behind it, allowing the ground behind it to beat a higher level than the ground in front of it - the wall retains the earth(holds it back)columna vertical structural element with a relatively small cross-section - in largestructures, often consists of reinforced concrete, a steel Universal Column(UC), or an encased UC- that is, a UC encased in (surrounded by)concretebeama horizontal structural element with a relatively small cross-section - inlarge structures, often consists of reinforced concrete or a steel UniversalBeam (UB) -frequently spans between two columnsslaban area of concrete generally with a constant thickness, most often afloor slab (a slab for a floor)- called a suspended slab if it spans betweensupporting beams, including ground beamsdama wall which holds back water behind it- for example, across a valley todam a river and create a reservoir (a manmade lake)Note: See Unit 16 for more on in-situ concrete and precast concrete.I 06Professional English in Use EngineeringStructural sectionsuniversal beam (UB)an !-section with a depth greater than its widthuniversal column (UC)an !-section whose outside dimensions are roughly squarerolled steel joist (RSJ)a term sometimes used to refer to !-sections generallyrolled steel channel (RSC)a C-sectionrolled steel angle (RSA)an L-sectionIII[LTstructural teeaT-sectioncircular hollow section (CHS)a circular tuberectangular hollow section (RHS)a square or rectangular tube0DTypes of loadType of loadDescriptionExamplesdead loada load that never changes, such asthe self-weight of a structure (itsown weight)the weight of the concrete fromwhich a bridge is builtlive loada load whose magnitude can bedifferent at different times - usuallyimposed on (put on) a machine orstructure by something that is notpart of the machine or structurecargo carried by a truck - differentweights of cargo may be carried ondifferent tripsstatic loada load that remains still (does notmove)the dead load of a building, or aLive Load which remains still, suchas snow lying on a roofdynamic loada moving load, such as one whichproduces a sudden shock but lastsfor only a brief moment (an impulse)aircraft wheels hitting the runwayon landingpoint loada load which is concentrated - thatis, one which acts on a small areathe end of a set screw pressing ona shaft (see Unit 27)uniformlydistributed load(UDL)a load which is spread evenly over areasonably large areathe weight of water acting on thebottom of a swimming poolProfessional English in Use Engineering107B MomentsThe diagrams show how the load supported or lifted can be increased by moving the effortfurther from the fulcrum .
In both diagrams, the clockwise moment - the force turning thelever in the same direction as the hands of a clock - is equal to the anticlockwise moment.The levers are therefore in equilibrium (see Unit 32). In order to lift the load, the clockwiseturning moment would need to be increased slightly.Lever 1load200 Neffort100 Nllj1mleverfulcrum2mClockwise moment: 100 N x 2 m = 200 NmAnticlockwise moment: 200 N x 1 m = 200 NmLever 2load400 Neffort100 Nll4mClockwise moment: 100 N x 4 m = 400 NmAnticlockwise moment: 400 N x 1 m = 400 Nm108Professional English in Use EngineeringVapour, cooling and thermal inertiaGas and vapourA gas can also be called a vapour- for example, water vapour.
The definition of a vapour isa gas which is below its critical temperature. This means the gas can be condensed by puttingit under pressure. Above the critical temperature (374 ac in the case of water), the gas can nolonger be condensed by pressure.SteamWater vapour is often called steam. When it is extremely hot- such as in electricitygenerating turbines - it is called superheated steam.Cooling and thermal inertiaRadiators are widely used in cooling systems - for example, in vehicle engines. Liquid called coolant- is pumped around the hot engine to absorb heat, and travels through aradiator positioned at the front of the vehicle.
As the vehicle moves, air flows over theradiator. The airflow cools the radiator and the coolant inside it. Without a cooling system,the engine would overheat. However, this would not happen immediately after starting theengine, due to thermal inertia- the fact that it takes time to change the temperature of aheavy mass of material (such as an engine), either when it is heated or cooled. An object witha high level of thermal inertia can be described as a heat sink.A radiator for an engine cooling systemProfessional English in Use Engineering109rmJ The electromagnetic spectrumThe diagram below shows the types of wave in the electromagnetic spectrum.red_ _ _o_range700 n~ -----wavelengthvisible lightgreenyellow--- -- - ..................--- --- -frequency in Hz10 41061081010------ --101 2microwavesradio wavesnm110TV waves= nanometresProfessional English in Use Engineeringviolet500nm600nm............
_blue''1014'''''''''''''''''1016ultravioletinfrared'''''' 400nm1018gamma raysx-raysPipe and hose fittings and valvesPipe and hose fittingsa ninety-degree elbowa crossa plug: fits inside theend of a pipe to close ita forty fivedegree elbowa uniona cap: fits over theoutside of the endof a pipe to close ita teea flange: allows largerpipes to be bolted together,end to enda reducer: allows twopipes of different diametersto be connectedValvesThe flow of liquid through pipes and hoses can be controlled by valves. According to theirtype, these devices can:•be fully opened to allow a flow, or fully closed to shut off (stop) the flow•be partly opened/closed to regulate the flow rate (control the volume of flow)•direct the flow, by allowing it to go along one pipe or another at a junction•provide an inlet, allowing liquid or gas to enter a pipe or tank, or an outlet, allowingliquid or gas to exit•act as a safety valve in a pressure vessel, allowing gas to escape if a dangerously highpressure is reached, to prevent an explosion•act as a check valve (or non-return valve), allowing liquid or gas to flow in only onedirection.Professional English in Use EngineeringIllSiphonic actionHydrostatic pressure allows liquids to be siphoned.
The principle of siphonic action can beshown using a hose - called a siphon in this situation - to make liquid flow upwards fromits surface level, over the side of a tank and then downwards. The hose must first be primed- that is, completely filled with water. The top end of the hose must then be immersed in theliquid (put below the surface).
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