第一篇：通信專業(yè)專業(yè)英語翻譯

專業(yè)英語

英文出處：PROCEEDINGS OF THE IEEE, VOL.60, NO.7, JULY 1972

譯文

可視化環(huán)境中的圖像處理簡介

圖像的質(zhì)量在整個圖像處理領域正在受到越來越多的關注。在某種程度上不斷增長的認識是基于復雜的數(shù)學方法，這種方法往往是為了突出精度的需要。在圖像的讀入和輸出數(shù)字形式的標準的缺乏方面，這里也有一個在不斷進步的認識，可以偏向的理解為處理的表面效率以及在不同的設施中對獲得的結(jié)果進行不確定的比較。更大的認識和要求是部分的受挫做出的響應，因為解決主觀失真的措施很難找到。這個困難的一部分是源于物理和主觀的結(jié)果的必然不同。這個觀點在這里的提出是源于我們對圖像結(jié)構(gòu)之間關系的重新評估1）數(shù)量的表示法的問題2)圖像處理的預期效果和不想要的失真3）基于觀察者的圖像處理的相互作用。

他們提供了一個框架，讓我們用來考慮和執(zhí)行我們的任務。通過加進我們自己對處理圖像的理解，以及在物理上和視覺上圖像處理時問題方面的理解，這些關于圖像質(zhì)量觀點的闡明，加強了我們對它的理解能力。我們提供了這些是希望他們可以被應用在其他領域。

在討論的過程中，人們注意到圖像處理服從乘法疊加性而不是加法疊加性，在操作上和結(jié)構(gòu)上都有令人關注的相同之處，用來實現(xiàn)一部分人類早期的視覺。基于這些相似觀點的提出，我們假設了一個視覺模型，這個實驗的結(jié)果在理論上能夠為其增加一些支持，并且提供了模型描述的基準。這個實驗性的視覺模型提供了特殊的作用，能夠大概的預測視覺處理的特性。

在近幾年，大量定量的工作被不同領域的工程師和科學家們所完成，以此來支持人類的視覺模型，這項工作中的很多部分在這里并沒有被明確的指出。我們嘗試引用參考文獻和教材，這樣可以更好的收集到這些文獻中少數(shù)引用到它們的地方，并且能夠提供一個統(tǒng)一的解釋。

2圖像的表示

在傳播，存儲和處理這些信息上的一個關鍵問題是如何表示。選擇如何表示重要的因素是傳輸，存儲和處理的問題，它們可以被它大大的影響。

如果一個理想的物理圖像是作為一個信息載體來考慮，那么它自身的性質(zhì)就已經(jīng)選擇了一種表示方法，在這里它選擇了光能的形式。此外，如果從字面上理解一個光學圖像，我們將繼續(xù)通過創(chuàng)建一個與之相對的信號來加強光能的代表性。這種表示確實是一種非常自然的表示方法，事實上它已經(jīng)被證明了，它經(jīng)常被應用于電視和圖像處理方面。

說來也奇怪，用光強度來分析在圖像技術上是一個相對較新的方法。攝影方面的處理，現(xiàn)在已經(jīng)過去了一個世紀，但是并沒有應用到它。隨著有關電的圖像處理方法的出現(xiàn)，它才受到重視。為了闡明這一點，想象一個黑白透明度的影像來描繪光學的圖像。為了看到這個模型，我們必須用一些強度io來一致的闡述透明度。以某種方法觀察光強度ix,y的傳輸模式。光能的傳輸取決于在膠狀乳劑中非晶體的體積濃度。因此，這些濃度代表著圖像的存儲形式，這些濃度被表示成cx,y,z。物理的情況在圖1中被描述.為了推導出重現(xiàn)圖像的ix,y和cx,y,z之間的關系，我們必須考慮光在介質(zhì)中的透射性。該物理情況在公式（9）中被給出。

di??kCx,y,zi（9）在這里i是光在任意一點傳輸介質(zhì)中的強dz

度，k是一個常數(shù)，代表非晶體銹銀在單位濃度上的衰減能力。整合公式（9）便得到標準的公式（10）。?iIx,ydiz??k?tCx,y,zdz（10）0i0

這里Zt代表溶劑的厚度。由于公式（10）積分在可靠性上代表著透明度獨立的每個單元銹銀的總流量，以及他在Z平面上是如何分布的。公式（10）也可以寫成公式（11）.ln(Ix,y0)??kdx,y（11）公式（11）的解決方法得出了

公式（12）Ix,y?i0e?kd（12）由公式（11）可以看出，在透x,y

明度的攝影情況下，圖像的物理表示法實際就是dx,y，這個表示法與重現(xiàn)的圖像的強度的對數(shù)成比例關系。轉(zhuǎn)而，公式（12）揭示了物理表示法dx,y在它轉(zhuǎn)換成光強度時取冪。此外，如果ix,y是一個原始圖像強度準確可靠的復制值，這些銹

銀被用來形成的dx,y一定通過處理被儲存在乳劑中，通過對數(shù)轉(zhuǎn)換成光能。這種

情況在圖2中對對數(shù)和指數(shù)的轉(zhuǎn)換進行了總結(jié)，用來機械化的形成攝影圖像，并且得到了證明。出現(xiàn)在公式（11）和公式（12）中的變量i0和 k為了計算方便

被省略了，它們只是質(zhì)量常數(shù)。

在攝影技術上公式（12）的關系是容易理解的，但是經(jīng)常被表達成公式（13）的形式log(i0Ix,y)?Dx,y（13）這里Dx,y叫做強度，與成dx,y比例，直接

敘述這個常用對數(shù)，在某種意義上與分貝的定義相似。由于dx,y和Dx,y都與一

般的強度概念有關，所以叫這個對數(shù)表示為強度是合理的。如上所述，除了兩個可選擇的參量所有的表示式是相同的。通過理解公式（11）和公式（12）得出公式(14)和（15）:

I?

x,y??log(Ix,y)（14）Ix,y?exp()（15）Ix,y

在這里帶點的變量代表密度，不帶點的變量代表強度。除了一個比例因素和一個附加的變量，這里所有的密度值代表的意思相同。

Image Processing in the Context of a Visual Model.INTRODUCTION

Image quality is becoming an increasing concern throughout the field of image processing.The growing awareness is due in part to the availability of sophisticated digital methods which tend to highlight the need for precision.Also there is a eveloping

realization that the lack of standards for reading images into and writing images out of digital form can bias the apparent effectivenesosf a process and can make uncertain the comparison of results obtained at different installations.Greater awareness and the desire to respond to it are partially frustrated, because subjective distortion measures which work well are difficult to find.Partof the difficulty stems from the fact that

physical and subjective distortions are necessarily different.The ideas presented here spring from our reevaluation of the relationship between

the structure of images and 1)the problem of quantitative representation, 2)the effect of desired processing and/or unwanted distortion, and 3)the interaction of images with the human observer.They provide a framework in which we think about and perform our image processing tasks.By adding to our understanding of what is to be measured when dealing with images and by strengthening the bridge between the objective(physical)and the subjective(visual)aspects of many image processing issues, these ideas have clarified the meaning of image quality and thus have ‘enhanced our ability to obtain it.[Ye offer them with the hope that they may aid othersw ealsl.In the course of the discussion it is noted that image processors which obey

superposition multiplicatively instead of additively, bear an interesting resemblance both operationally and structurally to early portionosf the human visual system.Based on this resemblance a visual model is hypothesized, and the results of an experiment which lends some support to and providesa calibration for the model are described.This tentative visual model is offered only for its special ability to predict approximate visual processing characteristics.In recent years there has beena large amount of quantitative work done by engineers and scientists from many fields in support of a model for human vision.While many of these works are not referenced explicitly here, we have attempted to reference papers and texts which doa good job of collecting these references in a small number of places while providing a unifying interpretation

.THER EPRESENTATION oF IMAGES

A key question in the transmission, storage, or processing of any information is

that of representation.The reason that the choice of representation is important is that the problems of transmission, storage, and processing can be substantially effected by it.If an ideal physical image is considered as a carrier of information, it follows that nature has already chosen a representation..It takes the form of light energy.Furthermore, if one takes nature literally when sensing an optical image, one will continue that representation by creating a ignal proportional to the intensity of that light energy.Indeed this representation seems likea very natural one, and in fact as already indicated, it is commonluys ed in television and digital image processing.Strangely enough representation by light intensity analogy is a relatively new practice in image technology.The process of photography, now over a century old, does not use it.It has only been with the advent of electrical imaging methods that it harse ceived attention.In order to clarify' this point, imagine a black and white photographic transparency which portrays some optical image.In order to see the reproduction one must illuminate the transparency uniformly with some intensity io and somehow view

the transmitted pattern of light intensity I.The quantities of light which are transmitted are determined by the volume concentrations of amorphous silver suspended in a gelatinous emulsion.Thus it is these concentrations which represent the image in its stored form.Let these concentrations be expressed as.Physically the situation is as depicted in Fig1..In order to derive the relationship between the reproduced image I and C we must consider the transmission of light through materials.The physics of the situation is given in(9)

di??kCx,y,zi(9)dz

where i is the intensity of the light at any point in the transmitting material and K is a constant representing the attenuating ability of a unit concentration of amorphous silver.Integration of(9)according to standard methods yields(10)

?iIx,ydiz??k?tCx,y,zdz(10)0i0

where st represents the thickness of the emulsion.Since the integral in the right-hand side of(10)represents the total quantity of silver per unit area of the transparency independent of how that silver is distributed in the z dimension(10)can be rewritten as in(11)ln(Ix,y)??kd0

x,yx,y(11)A solution of(11)for I，, yields(12)Ix,y?i0e?kd(12)

From(11)it can be seen that in the case of a photographic transparency, the physical representation of the image is actually d which is proportional to the logarithm of the reproduced intensity image.In turn(12)reveals that the physical representation d is exponentiated during its conversion to light intensity.Further, it follows that if Iu is a faithful reproduction of the original intensity image from which the transparency was made, then the quantities of silver used to form the representation d，, must have beendeposited in the emulsion by a process which was logarithmically sensitive to light energy.This situation is summarized in Fig.2 where the logarithmic and exponential transformations which mechanize the formation of a photographic image are placed in evidence.The variables io and R which appear in(11)and(12)have been omitted for convenience since they are only scaling constants.' The relationship of(12)is well known in photography but is usually presented ian somewhat altered form as in(1 3).log(i0Ix,y)?Dx,y(13)

Here the quantity Dx,ycalled densitydx,y, is proportional to but related directly

to the common logarithm in a manner similar t o t h a t used in the definition of the decibel.Because Dx,yanddx,y are both related to the popular notion of density it is

reasonable to call any logarithmic representation of an image a density representation.As indicated above, all such representations are the same except for the choice of the

two constant parameters.Taking this into account(1 1)and(12)may be generalizedto(14)and(15)I?

x,y??logI(x,y)(14)Ix,y?exp()(15)Ix,y

where the hatted variables represent density and the unhatted variables represent intensity.All density representations arethe same except for a scale factor and an additive constant.

第二篇：專業(yè)英語翻譯

Freeways,especially those built to Interstate standardsare the safest of the various classes of highways.高速公路,尤其是那些按照州際公路標準建造的是各種公路里面最安全的.While control of access, which limits vehicle conflicts(車輛沖突), isa primary factor in relatively low accident, injury,and fatality rates(事故,死亡率), other design features, such as wide medians and shoulders roadsides clear of obstructions, and the extensive use of protective barriers(護欄), are key factors as well.出入口控制減少車輛沖突，是獲得較低的交通事故率和傷亡率的一個主 要因素。另外，其他的設計特性，如較寬的中央分隔帶和較寬的路肩、路邊無障礙物、大量采用防護欄等也是關鍵要素。

The higher design speeds(設計速度)used for freeways result in long sight distances(視距)due to long radiushorizontal curves and long vertical curves, and otherdesirable design features that create a safe drivingenvironment.高速公路采用較高的設計速度導致的長視距是由于大半徑水平曲線和長的豎曲線，以及其他創(chuàng)造安全的駕駛環(huán)境的適宜的設計特性.Although most of the nation’s freeways enjoy this

relatively high level of design and safety, there are many opportunities for further enhancements.盡管全國絕大部分高速公路最喜歡這樣的設計和安全性比較高的水平，但還是有很多地方需要進一步增強。

Safety improvements on freeways can also result in substantial savings in life and property(生命和財產(chǎn))because freeways carry 25 percent of the nation’s total traffic.高速公路安全方面的改善，還會節(jié)約大量的生命財產(chǎn)資源，因為高速公路流量占了全國的總流量的25﹪。

Selecting the design speed for a freeway is an important safety element because most geometric criteria(準則，標準)related to or depend on it.選擇高速公路的設計速度是一件重要的安全因素因為大部分的幾何設計標準都是與它相關或者取決于它

In general, 110 kilometers per hour(km/h)should be the design speed for the mainline of a freeway , but it may need to be lower in areas of severe terrain or heavy development.一般來說，110千米每小時應該作為高速公路主干道的設計速度，但是在崎嶇的地區(qū)或者施工難度大的地區(qū)可能需要降低。

For reconstruction, rehabilitation, and resurfacing(3R)

projects, the design speed should not be less than the original design speed or the current legal speed limit of that highway section.對于重建，恢復鋪新路面工程，設計速度不應該低于平時設計速度或者那塊交通干線區(qū)域的目前規(guī)定的速度限制。Design speeds for interchange ramps（立交匝道）depend on the type of ramp selected, for example , loop，diamond, or direct, and the low-volume（低交通量）, running speed（行駛速度）of the intersecting highway.立交匝道的設計速度取決于砸到的選擇類型，例如，環(huán)形、菱形、直線型以及低交通量，相交交通干線的運行速度。Usually, the design speed is established by the most restrictive element of the ramp, typically, the sharpest curve（小半徑曲線）.通常，這個設計速度被匝道的最限制的范圍，典型的是小半徑曲線。

Whatever design speed is selected, adequate transitions（轉(zhuǎn)變、過渡）from the freeway proper and at the ramp terminal（末端、末尾）or merge point（合流點）should be developed.無論選擇多大的設計速度，都應該發(fā)展來自高速公路本身的和在匝道末尾或者合流點的合適的過渡。

Safe and efficient traffic operations depend on adequate lane

and shoulder widths as outlined in A Police on Geometric Design of Highways and Streets.安全及高效的交通運作取決于按照《道路的幾何尺寸的規(guī)定》設計的適當?shù)男熊嚲€和路肩寬度。

The need to accommodate more traffic within existing or limited additional right-of-way on high-volume urban freeway has led some agencies to increase capacity by exchange full-lane or shoulder widths for additional travel lanes with reduced widths.在高交通量的城市高速公路上，在已有的或者額外有限的公路用地條件下，容納更多的交通的需求，導致許多機構(gòu)通過減小車道寬度或者路肩寬度來騰出額外的車道來提高通行能力。

Any proposed use of less-than-full-standard cross-section must be analyzed carefully on a site-by-site basis.Experience indicates that 3.3-m lane can operate safely if there are no other less-than-standard features;however, combined with shoulder-width reductions, substandard sight distance, and other features, 3.3-m lanes may not provide the same safe operation.任何少于全標準道路橫截面的提議都必須建立在充分論證的基礎上。經(jīng)驗表明，不考慮其他低于標準的因素，3.3

米得行車道寬足夠保證安全。但是結(jié)合路肩寬度的減少，視距不足及其他因素，3.3米得行車道寬不能提供足夠的安全度。Converting shoulder to travel lanes for additional capacity through a short bottleneck section has been shown to significantly reduce congestion-related accidents on some projects.Removing shoulders for several kilometers, however, has not had the same result.在某些項目中，在短程的瓶頸路段為了額外的通行能力，將路肩轉(zhuǎn)變成行車道能顯著減少由道路擁擠導致的交通事故。然而減少幾公里長的路肩寬度，得不到同樣的的結(jié)果。

Pavement marking, such as lane lines, edge lines, channelizing lines at interchanges and ramps, and word symbol markings, provide important information to the drivers.路面標記，像在立體交道和斜坡處的車道線，邊緣線，通道線以及文字和符號標記，為駕駛員提供重要信息

Pavement markings define separate lanes of traffic traveling in the same direction, inform drivers of lane restrictions, and convey certain regulation and warnings that would not otherwise be clearly understand.路面標記定義了單獨的車道交通朝同一方向行駛，告訴駕駛員該車道限速，以及傳達某些規(guī)則和警告，否則，它們不會被駕駛員清楚的明白。

Pavement markings are particularly important at night and during inclement weather, and,therefore, must be retroreflective.While well-maintained painted pavement markings are acceptable, thicker, long-life markings ,such as thermoplastic or performed tapes ,may perform better in wet weather and heavy traffic.同時保養(yǎng)好的涂有油漆的路面標志是可以采用的，厚的，長壽命的標記，像熱塑性塑料或預成行的條帶，可以在潮濕的空氣和交通繁忙時表現(xiàn)得更出色。

Some studies have been made regarding the benefits of wider edge line markings(150 to 200 mm versus the standard 100 mm width).The wider markings may particularly benefit older drivers.一些研究已經(jīng)取得了有關更寬邊緣線方面的好處（150到200毫米相對于100毫米的標準寬度）。更寬的標記對老司機尤為有利。

第三篇：專業(yè)英語翻譯

樁筏基礎的簡化設計方法

摘要：在筏板基礎本身并不能滿足設計要求情況下，可通過在筏板下增加樁來提高其承載力。合理的布置一定量的樁，可以提高樁筏基礎的承載力和減少總沉降和差異沉降。本文分析了簡化計算方法的過程，對樁筏基礎的初步設計提供了有用的依據(jù)。它包括兩個階段：

1.樁筏基礎整體性能的評價；

2.單柱荷載作用下的性能評價。

第四篇：專業(yè)英語翻譯

8.Structural Steel Behaviour

土木0704喬薈07231104

靜載下的力學性能 最重要的機械結(jié)構(gòu)鋼性能的靜負荷是表示在理想化的拉伸應力應變Fig.8.1所示圖。最初的剛才有一個線性的應力應變曲線的斜率是楊氏彈性模量。鋼的彈性，同時保持在這個線性范圍，完全恢復。該線彈性特性的限制，通常近似屈服應力約200000MPA，以及相應的范圍內(nèi)。超過這個限制塑性鋼的流動沒有任何壓力，直到應變硬化應變的增加就達到了。這通常是塑料的范圍相當大，以及對鋼鐵延性非常重視。

屈服應力或許是結(jié)構(gòu)鋼的最重要的強度特性，它隨著鋼材化學 不同發(fā)生顯著的變化，最重要的成分是碳和錳，兩者都會引起屈服應力的提高。屈服應力隨著熱處理方法和壓制過程的工作量而變化，在同樣的條件下壓制次數(shù)多的薄板的屈服應力高于較厚的鋼板。硬化也可以提高屈服應力，拉伸的速率影響屈服應力，高拉伸速率會提高前期屈服應力，也可以提高下屈服應力Fy.在試驗中用到的用來確定特殊鋼種屈服應力的拉伸速率比實際結(jié)構(gòu)中經(jīng)常遇到的幾乎不變的速率要明顯提高很多。根據(jù)設計目的，各個不同的鋼級別要確定一個最小屈服應力，在澳大利亞和英格蘭，是根據(jù)化學組成和熱處理方法來分級的，而且各個級別的屈服應力隨壓制面最大厚度的增加而減小，另一方面，美國的慣例是在個級別內(nèi)區(qū)分化學組成和熱處理方法。所應用的屈服應力不隨厚度而變化。每種鋼材的最小屈服應力是根據(jù)一系列的標準拉伸試驗的結(jié)果確定的。由于成分組成，熱處理方法，壓制次數(shù)，板厚和試驗速率的小的變化，在這些試驗結(jié)果中有種顯著的分布，這種分布近似服從正態(tài)分布曲線。因此，某種鋼材用在設計中的最小屈服應力通常是一個特征值，其在任何標準拉伸試驗中會超過某個概率，因而一個獨立的試驗結(jié)果很可能明顯高于我們引用的屈服應力。當然，這種區(qū)別會更明顯的如果試驗不再橫截面最后的位置進行的話。通常認為，單向拉伸所確定的屈服應力對單向壓縮也正確。

重復荷載下的疲勞破壞

結(jié)構(gòu)鋼經(jīng)過多次的循環(huán)交變荷載后可能在低水平拉應力條件下發(fā)生破

壞。由重復荷載導致的局部損傷會引起這種高周疲勞破壞，它導致了微小裂縫的形成，疲勞裂縫的程度隨著后來的重復荷載而逐漸增大，直到最終有效橫截面積小以至發(fā)生突然破壞，高周疲勞只是當在結(jié)構(gòu)物設計基準期可能出現(xiàn)大量的荷載循環(huán)時的一種設計的考慮。這通常是橋梁，起重機，和支撐機械的結(jié)構(gòu)物的問題，而且風和波浪荷載也可能引起疲勞問題。顯著影響疲勞強度的因素有荷載循環(huán)次數(shù)，荷載循環(huán)中的應力幅以及局部應力集中的大小。

通常，節(jié)點應當布置得使應力集中減少到最小，以使通過節(jié)點的‘應力流，盡可能平滑。

焊接細節(jié)也應考慮到這一決定，和不必要的'壓力聚集者，應避免。它也將有利于限制，如可行，接頭的地點，如在接近中性軸點，低應力區(qū)。

沖擊荷載下的脆性破壞 結(jié)構(gòu)鋼不總表現(xiàn)出可塑的特性，在一些情況下可能發(fā)生突然破壞，即使名義拉應力很低。脆性破壞由局部高應力區(qū)域的微小裂縫的存在或形成而引發(fā)。一旦開始，裂紋就會穩(wěn)定增長因為外力會提供撕裂鋼材所需的能量。更嚴重的是快速不穩(wěn)定傳播的裂縫，因為儲存在鋼材中的固有的彈性應變能被釋放并用來使鋼材破壞。只要有足夠的應變內(nèi)能，這種裂縫是自擴展的并且將延伸至被擴展路徑中的延性元件破裂。這種延性元件具有足夠的變形能力吸收釋放的內(nèi)能。由于鋼材的延性，在三向約束條件下，結(jié)構(gòu)對脆性破壞的抵抗由局部應力集中的大小確定。高集中應力促進裂縫開展，所以由不良的幾何形狀和荷載布置引起的應力集中都很危險，而且材料的裂紋和缺陷也非常重要。不僅會增加局部應力而且有可能成為裂紋擴展區(qū)。結(jié)構(gòu)鋼的延性取決于鋼材的組成，熱處理方法和鋼材的厚度，并且隨溫度和應變率的變化而變化。像發(fā)生在更厚或者更大顆粒元素的鋼材中南，三向的幾何約束也會促進脆性，這是因為有更高的局部應力，因為在開裂過程中的更大的能量釋放和裂縫傳播的減緩。

脆性破壞的危險可以由選擇適合溫度下延性的鋼材類型來降低，或者通

過由減小應力集中和幾何約束的觀點來設計節(jié)點。裝配技術應該盡量避免引進潛在的危險裂縫或缺陷。重要結(jié)構(gòu)物的設計細節(jié)需要受目的在于探測嚴重缺陷的檢查程序的影響。當然，設計者還必須適當考慮特種鋼，制造技術，檢測和修正程序的額外費用。

9.Earth Pressures

重力式傳播的穩(wěn)定條件

設計必須考慮的不是最終或使用極限狀態(tài)，計算表明，必須有足夠的經(jīng)費是對發(fā)生不良極限狀態(tài)有關一個特定類型的墻體了。?在擋土墻的失效模式的數(shù)目可能對于檢查外部穩(wěn)定，重力墻被視為剛體（即沒有內(nèi)部收益或扭曲）。在某些類型的結(jié)構(gòu)檢驗中，還需要有內(nèi)部的穩(wěn)定，例如鋼筋混凝土墻，加固土墻。

上述給出的安全系數(shù)的運用是設計的傳統(tǒng)方法，在1994年推薦的極限狀態(tài)方法要求對強度代表值運用一個調(diào)節(jié)系數(shù)來獲得設計值，例如，如果墻體位移量要求不超過0.5%的墻高，不排水強度下應用的M之應該小于1.5，承載能力計算時M應該在2到3之間，有效應力參數(shù)M應該小于1.2。結(jié)構(gòu)內(nèi)力和彎矩應該由設計土壓力和水壓力確定。為方便起見，重力墻壁取決于他們對外部的穩(wěn)定和極限狀態(tài)下自身的重量基本上應審查：力量作用在擋土墻中的垂直和水平分量計算。為了方便垂直力量包括墻壁的垂直載荷的重量和任何它可能攜帶，隨土壤以上的L形和T形墻踵重量在一起。也可能是地球的壓力造成的垂直分量的支持時，面對的不垂直，地面是傾斜的或在墻上摩擦是包括在內(nèi)。?

擋土墻的土壓力

主動土壓力對能夠阻止土體塌落、滑移和蠕變?yōu)樽匀黄胶鉅顟B(tài)的任何擋土結(jié)構(gòu)施加水平向和豎直向荷載分量，這些結(jié)構(gòu)在土壓力的作用下會發(fā)生稍微的屈服。當擋土結(jié)構(gòu)擠壓墻后土體時，產(chǎn)生被動土壓力。靜止土壓力是土

體施加給不屈服豎直擋土表面的水平壓力。靜止土壓力表示介于主動和被動兩種極限狀態(tài)之間的情況。

每一種土壓力都取決于土壤的物理特性以及土壤和結(jié)構(gòu)的相對剛性。土最重要的性質(zhì)看來是密度、砂土的內(nèi)摩擦角、黏性土的黏聚力和超固結(jié)比。就任意土體材料來說，作用在常見擋土墻上的主動土壓力水平分量可由針對墻背豎直、墻后填土面基本水平的一般土壓力楔體理論很好地給出。

假定該墻體采用通常的施工方法進行回填，并且能夠產(chǎn)生一小的轉(zhuǎn)動（轉(zhuǎn)動大小為0.001倍的墻體高度）引發(fā)回填土的內(nèi)摩擦。該轉(zhuǎn)角等價于土壓力作用下20英尺墻體的上表面向外移動1/4英寸。

一般土壓力楔體理論的公式（考慮了沿擋土墻墻面的摩擦）也可以用來計算墻體和填土面傾斜等其它所有情況下的水平分力。然而，和試驗結(jié)果相比則表明計算結(jié)果對負超載情況有點偏小，對正超載情況有點偏大，但是相差不超過10%。如果考慮進關于實際坡度的條件的不確定性，將擋土墻簡化為墻背垂直填土面水平的情況進行計算，也是足夠精確的。

在所有情況下，側(cè)向壓力的豎直分量會使土壓力合力與墻背的法線形成一個等于墻面摩擦角的角度。然而，該角度在任何情況下都不能超過墻后填土的內(nèi)摩擦角。

有些土由于缺少排水及他們自身的性質(zhì)，在任何情況下都可能變?yōu)榱黧w（不管形成的流體材料是大面積的還是僅僅靠墻的一條窄層）；這些土的壓力和與其具有同樣密度的流體的靜水壓力相等。

浸沒土的壓力可由式(9.1)給出，只不過式中采用的材料容重會由于水的浮力和浸沒條件下的內(nèi)摩擦系數(shù)而降低；除此之外，也必須包括完全的靜水壓力。對于粒狀材料來說，水下的浸沒對內(nèi)摩擦系數(shù)和墻面摩擦系數(shù)的影響非常小。

第五篇：專業(yè)英語翻譯

1)Electricity can be measured in amount and quality.電可以用數(shù)量和質(zhì)量來度量。

2)Instrument transformers are installed on the high-voltage equipment.互感器安裝在高壓設備上。

3)Electric power is generated in power generating stations or plants.電能是在發(fā)電站或發(fā)電廠產(chǎn)生的。

4)The meters are calibrated and the scale is designed to read the value of the desired unit.這些儀表可以被校準并且設計了不同的量程，以便讀出期望的數(shù)值。

5)Electrical energy can be stored in two metal plates separated by an insulation medium.Such a device is called a capacitor, and its ability to store electrical energy is termed capacitance.It is measured in Farads.電能可以儲存在被一絕緣介質(zhì)隔開的兩塊金屬板中，這樣的裝置被稱為電容器，它儲存電能的能力就被稱為電容。電容的測量單位是法拉。1)The signal should be filtered before it is amplified.The signal should be filtered before being amplified.放大信號前，應先對其進行濾波。

2)An object becomes hot.It is placed in the sun.Once being placed in the sun, an object becomes hot.物體放置在太陽下會變熱。

3)We must do various experiments before a new electronic product is designed.Before designing a new electronic product we must do various experiments.在設計一個新的電子產(chǎn)品之前，我們必須做各種實驗。

4)Changing resistance is a method for controlling the flow of the current.改變電阻是控制電流的一種方法。

5)Conducting electricity means the flow of electrons through an object.傳導電流意味著電子在物體內(nèi)的流動。

1)The power supply, which is shown in block-diagram in Fig.1, is a single-phase switch-mode inverter.The power supply shown in block-diagram in Fig.1 is a single-phase switch-mode inverter.圖1中用框圖表示的電源是一個單相開關逆變器。

2)A three-phase circuit, as it was pointed out above, is merely a combination of three single-phase circuits.A three-phase circuit, as pointed out above, is merely a combination of three single-phase circuits.正如上面所指出的那樣，三相電路只不過是三個單相電路的組合。

3)The transistor, which is working with correctly polarities, can work as an amplifier.The transistor working with correctly polarities can work as an amplifier.工作于正確電源極性下的晶體管，作用就像放大器。

1）The capacity of individual generators is larger and larger so that the increasing demand of electric power is satisfied.The capacity of individual generators is larger and larger to satisfy the increasing demand of electric power.單臺發(fā)電機的容量越來越大，目的就是滿足不斷增長的用電需求。2)What does a fuse do? It protects a circuit.The function of a fuse is to protect a circuit.保險的作用就是保護電路。1)If it is possible, the open-loop control approach should be used in this system.If possible, the open-loop control approach should be used in this system.可能的話，這個系統(tǒng)應該使用開環(huán)控制方法。

2)As illustrated in Fig.1, there is a feedback element in the closed-loop system.As in Fig.1, there is a feedback element in the closed-loop system.就像圖1所示的那樣，這個閉環(huán)系統(tǒng)中有一個反饋元件。

3)The device includes an instrument transformation and a relay system which has two circuits in it.The device includes an instrument transformation and a

relay system with two circuits in it.這個裝置包括一個互感器和一個有兩個電路的繼電器系統(tǒng)。

1)It has been mentioned above that the electrons in a metal

are able to move freely through the metal, that their motion constitutes an electric current in the metal and that they play an important part in conduction of heat.前面已經(jīng)提到：金屬中電子能自由地通過金屬，電子的移動在金屬中形成了電流，電子在熱傳導中起著重要的作用。

2)The reluctance motor operates synchronously at a speed which is determined by the supply frequency and the number of poles for which the stator is wound.磁阻電動機以某一速率同步運轉(zhuǎn)，該速率是由電源頻率和定子繞制的級數(shù)決定的。

3)The testing of a cross-field generator will be described in this section with chief reference to the tests that are normally taken on every machine before it leaves the makers works.交磁發(fā)電機的試驗將在本節(jié)中敘述，它主要涉及每臺電機在離開制造廠前應進行的試驗。1)All radiant energies have wavelike characteristics, which are analogous to those of waves moving through water.All radiant energies have wavelike characteristics analogous to those of waves moving through water.所有的輻射能都具有波的特性，與水中移動的波的特征相似。

2)The instruments present include some digital ones which are relative to DSPs.The instruments present include some digital ones relative to DSPs.到場的儀器中還有一些與DSP有關的數(shù)字儀器。

1.As the system expands and higher voltage levels become necessary for transmission, the older transmission lines are often relegated to subtransmission function.隨著系統(tǒng)的擴大和更高的電壓等級為輸電所必需，舊的輸電線路往往被移交給中壓輸電功能。

1.Roughly, the capability of lines of the same length varies at a rate somewhat greater than the square of the voltage.粗略的講，長度相同的線路的容量，以比電壓的平方略大的比率變化。

2.No definite capability can be specified for a line of a given voltage, however, because capability is dependent on the thermal limits of the conductor, allowable voltage drop, reliability, and requirements for maintaining synchronism between the machines of the system, which is known as stability.然而，無法為給定電壓等級的線路指定確切的容量，這是因為容量取決于導線的發(fā)熱極限、允許的電壓降落、可靠性和維持系統(tǒng)中的發(fā)電機同步的要求（這被認為是穩(wěn)定性）。

1.Capacitance exists between the conductors and is the charge on the conductors per unit of potential difference between them.電容存在于導體之間，等于導體上的電荷（電量）與導體間的電勢差之比。或：電容存在于導體之間，等于導體之間單位電壓對應的電量。“A per unit of B” 表示 “單位B上的A” 或者“A/B”。

2.Balance of the three phases can be restored by exchanging the positions of the conductors at regular intervals along the line so that each conductor occupies the original position of every other conductor over an equal distance, as shown in Fig.3.1.如圖3.1所示，沿線路方向每隔一定間隔就交換導線位置，使每根導線都能占據(jù)具有相同輸電距離的其他各導線的初始位置，以重建三相平衡。

Electrical energy can be stored in two metal plates separated by an insulating medium.Such a device is called capacitor or condenser.Its ability to store electrical energy is capacitance.It is measured in farads 電能可儲存在由一絕緣介質(zhì)隔開的兩塊金屬極板內(nèi)。這樣的裝置稱之為電容器，其儲存電能的能力稱為電容。電容的測量單位是法拉。

1.Small industrial customers are supplied by primary feeders at this voltage level from the primary system, which also supplies the distribution transformers providing secondary voltages over single-phase three-wire circuits for residential and commercial customers at 120 V/240 V.小型工業(yè)用戶由一次系統(tǒng)中此電壓等級的一次饋線供電。一次系統(tǒng)也給經(jīng)過單相三線電路為居民用電和商業(yè)用戶提供120V/240V二次電壓的配電變壓器供電。

2.As illustrated in Fig.6.1, the aggregated load represented at a transmission substation(bus A)usually includes, in addition to the connected load devices, the effects of substation step-down transformers…

如圖6.1所示，在輸電變電站（母線A）所給出的集合負荷，除了所連接的負荷設備以外，通常還包括變電站降壓變壓器的影響……。

1.Roughly, loads are devices those consume electric energy or electric power consumed by customers mainly in distribution system.粗略的講，負荷是主要在配電網(wǎng)中消耗電能的設備或者由用戶消耗的功率。

2.The loads absorb electric energy from the power system and converts it into energy of other forms, which may be heat energy to heat water or to melt irons, or mechanical energy to drive a machine, etc.負荷從電力系統(tǒng)中吸收電能，并將其轉(zhuǎn)換為其他形式的能量，可能是燒水或溶化鋼鐵的熱能，或者是驅(qū)動機器的機械能等。

3.This kind of loads, especially those consume energy calculated by standard coals more over 10 thousands of tons per year, has a name of high energy consuming loads.這種負荷，尤其是那些年耗能萬噸標準煤以上的負荷，被稱為高耗能負荷。

1.The synchronous machine as an AC generator driven by a

turbine is the device which converts mechanical energy to electrical energy, in powers ranging up to 1500MW.作為由渦輪機驅(qū)動的交流發(fā)電機，同步電機是將機械能轉(zhuǎn)化為電能的設備，其功率范圍高達1500MW。

1.Hydropower plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riverbank habitats.水電廠會導致水中的氧氣溶解度降低——（這是）一個對岸邊生存環(huán)境有害的問題。

2.For instance, in the United States, water power accounts for less than 20% of the total and that percentage will drop because most of the available sources of water power have been developed.例如，在美國，水電在全部電力中所占的比例不到20%，并且，因為大多數(shù)可用的水電資源已被開發(fā)，該百分數(shù)還會下降。

1.Most stations have ratings between 200 MW and 1500 MW so as to attain the high efficiency and economy of a large installation.大多數(shù)電站的額定值在200MW到1500MW之間，以實現(xiàn)大站的高效經(jīng)濟（運行）。

2.Thermal stations are usually located near a river or lake because large quantities of cooling water are needed to condense the steam as it exhausts from the turbines.熱電廠通常位于河流或湖泊附近，這是因為需要大量的冷卻水在蒸汽從汽輪機排出時將其冷凝。

1.Nuclear plants fueled by uranium account for a continually increasing share of the load, but their construction is slow and uncertain because of the difficulty of raising capital to meet the sharply rising cost of construction, constantly increasing safety requirements which cause redesign, public opposition to the operation of the plants, and delays in licensing.Flowing through a circuit, the current will lose part of it energy.當電流流過電路時，要損耗掉一部分能量。（現(xiàn)在分詞短語作狀語）

Doing experiment is of great help to us.做實驗對我們的學習是很有幫助的。（動名詞作主語）By changing the resistance，we can change the current.通過改變電阻，我們就能改變電流。（動名詞作介賓）Mechanization is using machines instead of hand labor.機械化就是用機器來代替手工勞動。（動名詞作表語）

When an electric current flow through a wire it meets some opposition.當電流流過導線時，它會遇到某種阻力。（狀語從句）

Before one studies a system, it is necessary to define and discuss some important terms.在我們學習系統(tǒng)之前，必須定義并討論一些重要的術語。（狀語從句）It is possible that we use a computer to solve these complicated problem.我們可以用計算機來解這些復雜的題目。（表語從句）

You should determine which of the following functions is analytic.你應當確定下列函數(shù)中哪一個是解析式。（賓語從句）The fact is that radio waves travel as fast as light does.事實是無線電波的傳播速度與光速一樣快。（表語從句）The places where small computers can be used appear endless.可以使用小型計算機的場合似乎是無止境的。（定語從句）The instrument that we often use is very good in quality.我們經(jīng)常使用的那臺儀器質(zhì)量很好。（定語從句）

The places where small computers can be used appear endless.可以使用小型計算機的場合似乎是無止境的。（定語從句）The instrument that we often use is very good in quality.我們經(jīng)常使用的那臺儀器質(zhì)量很好。（定語從句）

Now we can determine where the slope is zero.現(xiàn)在我們可以求出何處斜率為零。（賓語從句）This is how a computer works.這就是計算機的工作原理。（賓語從句）Electrons always move toward where the potential is higher.電子總是朝向電位較高的地方移動。（介賓從句）

The fact that everything around us is matter is known to all.我們周圍的一切東西均是物質(zhì)這一事實是大家都知道的。（同位語從句）Section 2 Exercise 3

Section 3 Exercise3 必須強調(diào)的是線性電阻器是一個理想的電路元件；它是物理元件的數(shù)學模型。我們可以很容易地買到或制造電阻器，但很快我們發(fā)現(xiàn)這種物理元件只有當電流、電壓或者功率處于特定范圍時其電壓——電流之比才是恒定的，并且這個比值也取決于溫度以及其它環(huán)境因素。我們通常應當把線性電阻器僅僅稱為電阻器。只有當需要強調(diào)元件性質(zhì)的時候才使用更長的形式稱呼它。

而對于任何非線性電阻器我們應當始終這么稱呼它，非線性電阻器不應當必然地被視為不需要的元件。

Section 4 Exercise 3 如果一個電路有兩個或多個獨立源，求出具體變量值（電流或電壓）的一種方法是使用節(jié)點分析法或網(wǎng)孔分析法。另一種方法是求出每個獨立源對變量的作用然后把它們進行疊加。而這種方法被稱為疊加法。疊加法原理表明線性電路某個元件兩端的電壓（或流過元件的電流）等于每個獨立源單獨作用時該元件兩端的電壓（或流過元件的電流）的代數(shù)和。Section 5 Exercise 3 相電壓與相電流之比等于電路的阻抗，符號為字母Z，阻抗是一個具有量綱為歐姆的復數(shù)量。阻抗不是一個相量，因此不能通過把它乘以

并取其實部把它轉(zhuǎn)換成時域形式。但是，我們把電感器看作是通過其電感量L表現(xiàn)為時域形式而通過其阻抗

表現(xiàn)為頻域形式，電容在時域里為電容量C而在頻域里為

，阻抗是某種程度上的頻域變量而非時域變量。

Section 6 Exercise 3