【正文】 n Cylindrical Shells due to Internal PressureThe classic equation for determining stress in a thin cylindrical shell subjected to pressure isobtained from of forces perpendicular to plane ABCD gives:PL ．2r =2σqLtorσqq=PrtWhereP=pressure,L=length of cylinder ,σThe strain εε=is defined as_2prr2prr=hoop stress ,r=radius, t=thicknessq2p(r+W)2prrr=qorεq=WrAlsoεdWdrThe radial deflection of a cylindrical shell subjected to internal pressure is obtained by substituting the quantity into Eq.().Hence for thin cylindersW=PrEt2Where W= radial deflection, E= modulus of elasticityEquations()and()give accurate results when r rt decreases,however , a more accurate expression is needed because the stress distribution through the thickness is not is then made to the “thick shell” theory first developed by derived equations are based on the forces and stresses shown in theory assumes that all shearing stresses are zero due to symmetry and a plane that is normal to the longitudinal axes before pressure is applied remains plane other words ,?1 is constant at any cross sectionA relationship between σrand σqcan be obtained by taking a freebody diagram ofring dr as shown in forces in the vertical direction and neglecting higherorde terms ,we then haveσ—σr=dσdrrqA second relationship is written asσ σr=q=E（1+μ）（12μ）E[εq(1μ)+μ（εr+ε）]σ1=（1+μ）（12μ）E[εr(1μ)+μ（ε(1μ)+μ（εq+ε+ε）]）]（1+μ）（12μ）[ε1qrSubstituting Eqs.()and()into the first two expressions ofEq.()and substituting the result into Eq.()results in:dwdr+1dwrdr—wr=0A solution of this equation isW=Ar+BrWhere A and B are constants of integration and are determined by first substituting Eq.()into the first one ofEq.()and applying the boundary conditionsσr= —piatr=riatσr= —poatr=roExpression()then bees: w= — μrε1+1Er(rOri)［r2(1μ2μ)（PiriPOrO）+rirO(1+μ)（PiPO）］2222Once w is obtained, the values of σand expressed for thick cylinders asPiriPOri+(PiPO)（rOriqare determined from Eqs.(),and ,(),and()rirOσq=r)σr= —POriPiri+(PiPO)（rOririrOr)whpressureσr=radial stressσq=hoop stressPi=internal pressurePO=externalri=inside radiusrO=outside radiusr=radius at any pointThe longitudinal stress in a thick cylinder is obtained by substituting Eqs.(),(),and()into the last expression of Eqs.()to giveσ1=Eε+2μ(PiriPOrO）r2OriThis equation indicates that σ1 is constant throughout a cross section because εis constantand r does not appear in the second the expressionσ1 can be obtained from statics Asσ1=PiriPOrOr2OriWith σ1 known, Eq.()for the deflection of a cylinder can be expressed asw=r(PiriPOrO)(12μ)+(PiPO)rirO(1+μ)Er(rOri)閱讀材料4圓柱殼體的應(yīng)力源于內(nèi)部壓力。累積力通過正交于平面ABCD給出：PL ．2r =2σqLtorσqq=Prt說明： P=壓力，L=圓柱體的長度，σ正應(yīng)變εε=由下面式子決定：_2prr=環(huán)繞切應(yīng)力，r=半徑，t=殼體的壁厚q2p(r+W)2prrrq并且：ε=2prrdWdrorεq=Wr圓柱狀殼體的半徑偏差源于內(nèi)部壓力。隨著r的減少，然而，一個更精確的表述是非常必要的，因為厚度的壓力分配并不是均衡的。該理論假定所有的剪切力都為0是由于對稱性和一個正常縱軸的平面，在施壓前仍然是平面壓力。σr和σq的關(guān)系可以通過一個環(huán)dr的自由體示意圖獲得。其為： σ1=Eε+2μ(PiriPOrO）r2O2ri這個表達式說明了σ1是一個橫截面的常數(shù)因為ε的表達式可以由靜態(tài)值表示:σ1=PiriPOrOr2O2是常數(shù)和r不會在第二項出現(xiàn)。The lower heating value is defined here as the higher heating value(HHV)minus the energy necessary to evaporate the water that is created by the bustion of the hydrogen in the fuel and minus the energy needed to evaporate the moisture that was already part of the fuel before value熱值Evaporate [?39。p?ret]……蒸發(fā)；使……脫水；使……消失，揮發(fā)；消失，失蹤Combustion [k?m39。m??st??] ；濕度；潮濕；降雨量低熱值在這里定義為高熱值減去使水分蒸發(fā)所需要的能量，這些能量包括使燃料中的氫燃燒產(chǎn)生的水分蒸發(fā)所必需的能量和使燃料燃燒前所含有的水分蒸發(fā)所需要的能量。biomass [‘ba??(?)m230。sifi39。In developing countries like Ghana where solid waste disposal is increasingly an environmental burden with its attendant health hazards, the idea of converting the organic fraction of municipal solid waste into energy for the national grid is a wele proposition towards reducing volumes of domestic waste to be disposed of or —；burden—；attendant—隨員、伴隨的；hazard—；convert—；organic fraction—有機部分；municipal—市政的；the national grid—國家電網(wǎng)；proposition—提議volumes of—大量的；在像加納這樣的發(fā)展中國家中，因為伴隨著健康危害，固體垃圾處理正日益成為環(huán)境負擔(dān)，而把城市生活垃圾轉(zhuǎn)換成電能并輸送到國家電網(wǎng)中的想法，對于減少將被處理或填埋的大量的生活垃圾來說，是一個不錯的提議。Thus, a bined cycle plant can be designed that uses the hot flue gases produced from organic waste bustion to generate steam and gasify liquid methane in stages to turn a steam turbine and a gas turbine respectively , and the flue gases, cooled down, can be used to predry the organic waste in a cycle for use as fuel to increase the efficiency of the —；turbine—渦輪機；因此，一個聯(lián)合循環(huán)電廠可以被設(shè)計成這樣：使用有機垃圾燃燒產(chǎn)生的熱煙氣分步地去生產(chǎn)蒸汽去轉(zhuǎn)動蒸汽輪機和氣化液態(tài)甲烷去轉(zhuǎn)動燃氣輪機，然后被冷卻下來的煙氣可作為燃料循環(huán)地用于預(yù)熱有機垃圾以提高電廠的效率。王局長：Hydrogen production from biomass can contribute not only to largescale development and utilization of renewable energy, improve energy structure and reduce pollution as well as to meet people39。Biomass gasification in supercritical water(SCW超臨界水)is a promising technology for Hydrogen production from biomass, which is based on the special physical and chemical properties of water near the critical point.第三篇：過程裝備與控制工程專業(yè)專業(yè)英語翻譯9Reading Material 9Heat Treatment of SteelTypes of Heat Treating OperationsFive operations are detailed in this lesson as the basis of heat of theseOperations RelievingWhen a metal Is heated，expansion occurs which is more or less proportional to the temperature cooling a metal,the reverse reaction takes is, a contraction is observed．When a steel bar or plate is heated at one point more than at another，as in welding or during forging，Internal stresses are set up．During heating, expansion of the heated area cannot take place unhindered，and it tends to deform．On cooling，contraction is prevented from taking place by the unyielding cold metal surrounding the heated area．The forces attempting to contract the metal are not