第一篇：房地產建筑中英文翻譯文章

Architectural aesthetics Description: good architecture is breathtaking beauty.We can compare the strict designed by calculation from the ancient Greek temple of ancient Rome, medieval church or ancient temples, but was unable to predict that Tadao Ando's “light of the Church”, he is born, find the peacefulness.After the priest of the Forum should be sacred for wall, human thinking should be in the wall, but on solidification, Ando has boldly fashionable in the wall of a perpendicular to the horizontal opening of the intersect, forming a “cross” light, the God of light into the room.This means that the gods of light of many people's hearts.Keywords: architectural aesthetics, geographical, natural environment Our physical environment, some content to let long galleries, there are things you as minor and fleeting.Sometimes, it has not been tested by underline things but has an excellent quality, because they are in the environment and the role of one of them in the history of a people cannot be underestimated.The building is the mental and the physical form of a fantasy world, is a people want to constantly improve the world.Even in urban space or building a reality, people can be aware of when building the content, the content determines the atmosphere is not visible.At the same time, building with — the walls between the consciousness of history--also pregnant with significant changes in the future.Good architecture is breathtaking beauty.We can compare the strict designed by calculation from the ancient Greek temple of ancient Rome, medieval church or ancient temples, but was unable to predict that Tadao Ando's “light of the Church”, he is born, find the peacefulness.After the priest of the Forum should be sacred for wall, human thinking should be in the wall, but on solidification, Ando has boldly fashionable in the wall of a perpendicular to the horizontal opening of the intersect, forming a “cross” light, the God of light into the room.This means that the gods of light of many people's hearts.Architectural beauty lies in its natural environment, and rooted in obedience to the natural environment.A variety of architectural form, and varied architectural styles suitable for different natural and scenic forest terrain dissolving into one, creating a variety of architectural culture his beautiful language.Different different natural environment, as man and nature, to the summary of the building, to the plants.Hop, hop, suitable for the various geographical areas at the request of the natural environment, and nature.In the South-East Asia and South Asian countries, in China's Hainan Island and Taiwan island, located at the lush, tropical climate, people use Coconut Grove palm leaf up to adapt to the tropical rainforest left, the wooden floor, ventilation, light and cool and simple, built in the building;the tropical rain forest in the province, in China's Western Alpine region, people use stone barrier wall, according to the Hill jiushi built stone building, Typhoon snow insulation against the cold, built a plateau mountain building.As China's Sichuan and other minorities in Tibet Qinghai in Western China, according to the Hill jiushi built to all kinds of mountain building group.The loess plateau in China, mobei Gobi, rainfall climates, they leverage mountain slope dig to build houses, built of Adobe buildings.Dunhuang Pinakothek construction buried into the hillside, semi-open entrance, hillside retaining wall obtained, Adobe-style architectural characteristics very obvious.In the Eastern United States, Australia, in the South of China, with abundant rainfall, mild climate, people with wood and tile mountains jiushi, local conditions and cover up the shade hood, ventilation, humid area in the building.Visible in the different regions of the building has its own beautiful language.Architectural beauty lies in its rich sound, garden buildings is highly representative of a case.Although he continuously to borrow, King, box sites, and many other visual techniques demonstrated at such as art as the conception, however, only to Visual impact, he was not to be so awesome.In addition to the traditional Chinese garden itself of cultural tradition, philosophy, his heart also lies in the human sensory perception of others.The Phoenix huang class flute, whistle “flowing water when his sound;the bamboo homes Kim Bong, Lotus flowers smell” performance taste;“Poly boxing ring shaped Hill, as the bucket water pool” and reflects his scale, not to mention the claustrophobic to solitude, ascending to the expression of emotion in a lifetime “.The beauty of Chinese architecture: all inclusive-vapour and whirling, wind dance secluded huang, fragrant as years years-heze, by xiangyuan Yi Ching;pool-view heart, tingxie pleasant and so on and so on.It is this otoacoustic eye color, full moon flower, Garden perception of imagery, reflecting his poetically.Architectural beauty is a multi axis coordinate system.In different historical periods, different regional culture, ethnic background are not all the same.Ancient Chinese aesthetic standard who are unified, as was the mobilization of centralization, almost all the buildings means the creation of a common complete form of art.As a result, China's architecture reflects the orthodox Confucian thought, and ambitious;Chinese gardens with the Taoist, strongly imitate nature, extreme freedom and changeable.While ancient Greek philosophy and the arts all knowledge, in pursuit of eternal perfect, so in the spirit of the level of their pursuit of spiritual perfection, nature they are pursuing a lasting image of beauty, to some extent, their beauty is $ 1.1840, Engels in his earlier book, seven Filippo's hometown ”, discusses the classical architecture style of Zhongshan key new features: the Greek architects are brightly coloured, Moore of architecture(of North Africa, southern Europe of Islamic architecture)makes people feel hesitant, Gothic sacred happy;Greek architectural style phase anything, Moore-building style like the stars of the evening, Gothic architecture style like the Golden Dawn.“In short, different architectural expression of beauty are quite different.Architectural beauty lies in its arbitrary and should display fine, although it's almost done by people from the natural and artistic creation.Whether it is a tile, is a variation of, or is incomplete, dangerous, contemporary architectural design of the non-harmony ”consciousness is striking a trend.For example, postmodern architecture will tile formally introduced architecture creation, Isozaki of Tsukuba Center is a typical example.He will appear in the history and contemporary of intensity, Roman, Michelangelo, Moore, years and so many people of fragments from the original context in-out, converted and tile, make up a new system crashing, Vilas Palace of the expensive's maid were “in the Group Portrait, which stimulate the thinking of.The remains of ancient construction, the ruins of war, waste that some artists and architects feel torn beauty or form.For example, an earlier use of torn law-abiding architects Haworth to cause Shihlin jewellery design, he will even granite brick facades tore a large gap, causing a crash, make light projecting from the mysterious.While the deconstruction architects also exaggerated attitude stressed that the composition of dangerous to pose, its taste is represented as instability, weightlessness, sliding, overturning, falling, and so on a non-equilibrium of dangerous composition.Beauty is changing, the tragedy of the ancients, fair, sublime, noble, naive, and so far not able to cover a wide variety of today's emerging aesthetic form.Contemporary architecture in the area of ”non-harmony“ complexity, it widens the architectural modeling and aesthetic space so that the architectural beauty and meaning of ”harmonious“ become more abundant.Architectural beauty lies in the fact that it is reasonable to interleave.The evolution of the building, in a sense is emotional and the rational development of the Union.The relationship between emotion and reason, from had clashed, gradually developed into the amalgamation of the stage.In the field of architecture, emotional and rational boundaries are obscure.The emergence of light to dark, as emotion to rational, reasonable negative Chahar confirmed the existence of reason, and the building is with a certain function, a function of matter.At this level, the building contains natural rational components.When crossing the modern industrial civilization dating back to ancient times, we will surprises, this one's mind old emotional factors.Built on a thick massive form, there is a spirit of flexibility and intangible.In accurate and detailed scale in a fine expression of emotion, ”happy and bright mood, … a bright, sunny day...“(Engels).Back to the contemporary, the construction sector, multicultural coexistence styles;the rise and fall of modernism, postmodernism has just put on the stage of history, it was ”crazy“ heedless of the annihilation of deconstruction.”Wrong,“ ”symbiosis“ ”metaphor“ ”symbol“ a ”high tech“...seems to be in one night, the building became the best media passed emotion.Therefore, in the knowledge of contemporary architecture trends and future architecture, architectural beauty of emotional understanding and is one of the contemplative basis points.Architectural beauty lies in the science and technology on the art and architecture of the 20th century art and architecture development, most dramatic beneficial to past era。

Advances in technology make it possible to dream of architect.The role of art and nature and man, society, so that the full of life, from emotionally experience of nature and life of rhyme and poetic.At this time of the construction sector evolved ”reverse form of aesthetics“ aesthetic ”high tech“ ”ecological aesthetics“ and ”to maintain development of aesthetics“ as the representative of the emerging architectural aesthetic system.The inverse form of aesthetics ”intentional violation of the law in the form of aesthetics.Classical aesthetic pursuit in harmony, and he advocated conflict broken by expanding and American antithesis of conflict, warfare requirements, funny, humor, and other ways and means to improve the performance of buildings.“Aesthetic” stressed the high tech application, stressing the cultural expression of emotion, focusing on building flexibility and diversity, local and historical culture, such as Jean Nouvel * Design Center for the Arab world.The ecological aesthetics “ecology of full, stable, harmonious aesthetic standards, the pursuit of natural beauty and man-made beauty, Norman Foster's design in Wales * gardens, will naturally into them create artificial climate, this is not possible in the past.In support of science and technology, could hardly have been able to break through the nature and structure of the constraint.The sustainable development of natural aesthetics ”, ecology, society as a complete system, people and nature of interdependence and mutual harmony, as aesthetic ideals, chasing meet human needs, and create a good environment.The network era buildings form already appeared-e building.The magic of the computer network is now like a storm swept across the world, its biggest huge impact changing our every aspect of life.Science and technology of every advancement affect to the building and the development of the city, just as the invention of the cinema also means cinema such as architecture.Winston * Churchill that widespread warning said “we bring up the building, the building makes us”.E architectural beauty lies in its performance of the network age art architectural space, architect, or at least is the art of a special form, building with building language authoring, artistic expression to the outside world a thought or a explains a significance.The architectural language in the creative process in writing these meanings.While the network age of a main interpretation of the expression of every thought.E building is the author of a creative passion, artistic, aesthetic taste, social experience, the internal state of mind and to describe the depth of understanding of the object.The e-age, and paper are no longer the only vector of architecture, as history and bamboo from Oracle to ask, and development to paper and printing.Computer architecture expression, in fact already started showing up, is different from the previously static drawings, it displays the information of the expression, and broadband Internet use media real-time interactive publication makes the comprehensive development of the architectural design.All in all, a cultural background of the building, the accumulation of a rich cultural connotations of the building, either the environment it reflected the cultural heritage of the human spirit, but also with their own interpretation to the concept of beauty, building rich language and of endless aftertaste.http://www.tmdps.cn / http:// www.tmdps.cn

建筑美學淺談

簡介：好的建筑是令人窒息的美麗。我們幾乎可以比較嚴格的由計算而設計出古希臘古羅馬的神廟，中世紀的教堂或是古代的寺廟，但卻無法預測到安藤忠雄的“光的教堂”，他的誕生著實令人為之一振。在牧師的講壇后應該是神圣的永恒不變的墻體，人類的思維應該在這面墻體上凝固，可是，安藤卻大膽地在墻上流出了一個垂直于水平的相交的開口，形成了一個“光的十字”，把神的光芒引到人間。這種光的神靈意味更強烈的震撼著人的心靈。

關鍵字：建筑美學,地域,自然環境

我們所處的物質環境中,有些內容讓人長久無法忘懷，有些東西則如過眼云煙轉瞬即逝。有時，沒有經過刻意雕琢過的東西卻擁有著精良的品質，因為他們在環境中所扮演的角色令人折服，他們在歷史中上演的一幕令人不能小覷。建筑是精神和幻想世界的物化形式，是一個人們想不斷完善的世界。即使是在城市空間或建筑成為現實后，人們依然可以察覺到當初建筑所要表達的內容，這種內容決定了不可見的氣氛的情緒。同時，建筑標志著過去——墻壁之間可自覺的歷史——也孕育著將來顯著的變化。

好的建筑是令人窒息的美麗。我們幾乎可以比較嚴格的由計算而設計出古希臘古羅馬的神廟，中世紀的教堂或是古代的寺廟，但卻無法預測到安藤忠雄的“光的教堂”，他的誕生著實令人為之一振。在牧師的講壇后應該是神圣的永恒不變的墻體，人類的思維應該在這面墻體上凝固，可是，安藤卻大膽地在墻上流出了一個垂直于水平的相交的開口，形成了一個“光的十字”，把神的光芒引到人間。這種光的神靈意味更強烈的震撼著人的心靈。

建筑之美在于其根植于自然環境，又服從于自然環境。多樣的建筑形式，各異的建筑風格適宜于不同的自然環境，與風景林木地形溶為一體，形成了各種建筑文化自己的美的語言。

不同的地域，不同的自然環境，作為人與自然總結的建筑，向植物一樣落地生根。合天時，合地利，適宜于各種地區自然環境的要求，與大自然融為一體。

在東南亞和南亞各國，在中國的海南島和臺灣島，椰林茂密，氣候炎熱，人們用椰樹林棕櫚葉蓋起了適應熱帶雨林的茅草房，小木樓，通風輕盈涼爽簡潔，建起了熱帶雨林建筑；在中亞西亞，在中國的西部高寒地區，人們用石塊壘砌，依山就勢蓋起了石板建筑，避風擋雪保溫御寒，筑成了高原山地建筑。如中國的西藏青海四川等少數民族在中國西部，依山就勢建起可各式各樣的山地建筑群。在中國的黃土高原，漠北戈壁，雨量稀少，氣候干燥，人們利用山邊土坡挖地筑房，建起了具有鮮明特色的生土建筑。甘肅敦煌藝術陳列館把建筑埋入山坡下，半開敞式入口，山坡擋墻甬道，生土式建筑特征十分明顯。在美國的東部，在澳大利亞，在中國的南方，雨量充沛，氣候溫和，人們用木材磚瓦依山就勢，因地制宜，蓋起了遮陽避雨，通風透氣，造型別致的濕熱地區建筑。可見，不同地區的建筑有著自己美的語言。

建筑之美在于其詩情畫意，中國古典園林的建筑就是卓有代表的一例。盡管他不間斷地以借景，對景，框景等諸多視覺手法向人們展示著如畫般的意境,然而僅以視覺沖擊，他還無以有如此撼人的魅力。除了中國古典園林自身所蘊含的文化底蘊，哲學思想外，他的深意還在于調動了人的其他感官知覺。“鳳篁類長笛，流水當鳴笛”表現其聲；“竹院金風細，荷塘花氣香”表現其味；“聚拳石為山，環斗水為池”又體現了他的尺度，更不用說“幽閉以獨處，登高以暢懷”表達的情緒了。中國建筑之美包羅萬象：竹影婆娑，風舞幽篁，菏香苒苒，香遠益清；池景賞心，亭榭宜人等等等等。正是這耳聲目色，月圓花好，造就了中國古典園林的知覺意象，體現了他的詩情畫意。

建筑之美是一個多軸的坐標系。在不同的歷史時期，不同地域文化，不同民族背景下都不盡相同。中國古代人們心中的美學標準則是統一的，正如當時的中央集權，幾乎動員了全部當時的建筑手段共同創造出完整的藝術形式。因此，中國的建筑體現了儒家思想，正統而有氣魄;中國園林蘊含著道家思想，極力效法自然，極度自由，變化多端。而古希臘在哲學與藝術等等的一切知識，都是在追求永恒的完美，所以在精神層次上他們追求靈性的完美，在自然界中他們則追求一種永恒的形象美，在某種程度上，他們的美是一元的。

1840年，恩格斯在他的早期著作《七個菲利特的故鄉》一文中，論述了古典建筑中山重點新風格的美學特征：“希臘式的建筑師人感到明快，摩爾時的建筑（指北非，南歐的伊斯蘭建筑）使人覺得猶豫，哥特式建筑神圣的令人心醉神迷；希臘式的建筑風格相艷陽天，摩爾式的建筑風格像星光閃爍的黃昏，哥特式建筑的風格像朝霞。”總之，不同的建筑有著不同美的表達。

建筑之美在于其隨意之處竟顯精致，雖由人做宛自天成的藝術創作。無論是拼貼，是變異，抑或是殘缺，奇險，當代建筑設計中的“非和諧”意識引人注目的一種傾向。

例如，后現代主義建筑將拼貼正式引入建筑創作中,磯崎新的筑波中心是典型事例。他將歷史上和當代的烈度，羅曼諾，米開朗基羅，穆爾，霍來因等很多人的片斷從原來的文脈中撕拉出來，進行了轉換和拼貼，構成了一個相互撞擊的新系統，猶如維拉斯貴茲的《宮廷的侍女們》中的群體肖像，從而激起人們的思索。古代建筑的遺跡，戰爭廢墟，廢棄物使一些藝術家和建筑師感受到殘缺的美感或造型上的力度。比如較早運用殘缺守法的建筑師霍來因，在士林珠寶店的設計中，他將平整的花崗巖砌成的外立面撕開了一個大缺口，造成一種撞擊感，使得光線從種神秘的投射出來。而解構主義建筑師同樣以夸張的姿態強調構圖的奇險于動勢的感覺，其審美意趣表現為失穩，失重，滑動，翻傾，墜落等等非平衡的奇險構圖。

美是發展變化的，古人提出的悲劇，秀雅，崇高，尊貴，樸素等遠不能涵蓋當今出現的各種各樣的審美形態。當代建筑領域的“非和諧”具有復雜性，它開拓了建筑造型與審美的空間，使建筑之美與“和諧”的含義變得更為豐富。

建筑之美在于其是情理交織的。建筑的演進，在某種意義上是情感與理性的交織發展過程。情感與理性的關系，從曾經相互抵觸，逐漸發展到相互融合的階段。

建筑學領域中,情感與理性的界限正變的模糊。光之于黑暗的出現，正如情感之于理性，對理性的否定恰確認了理性的存在，而建筑物正是憑借了一定的功能，成為了使用功能的物質承擔者。在這個層面上，建筑包含與生俱來的理性成分。

當越過現代工業文明追溯到遠古，我們會驚喜的發現，這種人的心靈情感因素早已有之。建筑在厚重巨大的形態下，蘊藏了心靈的柔性與無形的時間。在精確細致的比例尺度中營造著細膩的情感，“表達了愉快與明朗的情緒，??燦爛，陽光照耀的白晝??”（恩格斯語）。回到當代，建筑界多元共存，風格多變；現代主義潮起潮落，后現代主義剛在歷史舞臺上上演，又被“瘋狂”的解構狂嘯湮沒。“錯時”“共生”“隱喻”“象征”“高技”??.似乎在一夜之間,建筑成了傳遞情感的最佳媒介。因此，在認識當代建筑思潮以及對未來建筑時，建筑之美的情理解和則是思辨的基點之一。

建筑之美在于科學技術對藝術和建筑創作的影響，這是20世紀藝術和建筑發展中，最鮮明的有益于以往時代的特征。

技術的進步使得建筑師的夢想成為可能。藝術的作用表現與人與自然，社會的關系，使生活的爆滿，從感性上體驗自然和人生的韻律和詩意。這時候的建筑界逐漸形成了“反形式美學”“高技美學”“生態美學”和“可維持發展的美學”為代表的新興建筑美學體系。

“反形式美學”有意違反了形式美學的規律。古典美學追求和諧統一，而他提倡沖突破碎，通過拓展美的對立面要求采用沖突，對抗，滑稽，幽默等方式與手法來提高建筑的表現力。“高技美學”強調高技術的應用，講究文化情感的表述，注重建筑靈活性和多樣性，努力表現地方性與歷史文化的內涵，如讓*努維爾設計的阿拉伯世界研究中心。“生態美學”以自然生態的完整，穩定，和諧為審美標準，追求自然美與人工美的完美結合，諾曼*福斯特設計的威爾士國家植物園，將自然納入其中營造人工氣候，這在過去是不可能想象的。在科技的支持下，簡直已經能夠突破自然，結構的約束。“可持續發展美學”把自然，生態，社會作為一個完整的系統，將人與自然的相互依賴和相互和諧，作為審美理想，追求著滿足人類生存需要，又創造良好的生態環境美學價值。

網絡時代的建筑形式已經出場——e建筑。神奇的計算機網絡現在像一場風暴席卷著全球，正以其無法估量的巨大沖擊力改變著我們生活的每一個方面。科技的每一次進步都或多或少影響到建筑和城市的發展，就像電影的發明同時也就意味著電影院這類的建筑產生一樣。

溫斯頓*丘吉爾那就廣為傳播的警句說“我們造就建筑，建筑也造就我們”。e建筑之美在于它表現網絡時代的建筑空間，建筑師藝術，或者至少是藝術的一種特殊形式，建筑時采用建筑的語言創作，凡是藝術都要向外界表達一種思想或說明一種意義。建筑語言在創作過程中書寫了這些意義。而網絡時代的一件主詮釋了每一個思想的表達。e建筑凝聚了作者的創作激情，藝術修養，審美趣味，社會閱歷，內在心境和對描繪對象深度的理解。

e時代，紙不再只是建筑的唯一載體，正像歷史上從甲骨文到竹簡問，又發展到紙和印刷術一樣。計算機建筑表達，事實上已經開始顯示出強大的說服力，不同于一張張靜止的圖紙，它顯示了信息的動態表達，并在寬帶互聯網上利用媒體實時交互式發布，使得建筑設計全面發展。

總之，孕育著一個文化背景的建筑，積淀著豐富的文化內涵的建筑，既可以折射出所處環境的文化傳統，人文精神，同時也以其自身詮釋著美的概念，建筑豐富的語言中裹著的是讓人無盡的回味。

第二篇：建筑證書中英文翻譯

建筑證書的中英文翻譯

Certificate of Real Estate Ownership（房地產權證）

The Certificate granted by the government stating the ownership title of the property built on a certain piece of land, location, construction area, etc.The years of property ownership is equal to the years of land use right.New Certificate is a combination of both the land use right information and real estate ownership information.由政府部門頒發的關于某土地上所建建筑權屬、地理位置、建筑面積等的證書。房屋所有權年限等于土地使用年限。新的房地產權證包括土地使用權信息和房地產權信息。

Construction Completion Inspection Certificate（建設工程竣工驗收備案證書）

A certificate issued by Construction Project Quality Supervision to approve the inspection for the quality of construction after completion.建設工程完工時，對工程質量進行驗收檢查，合格后由建設質量監督總站頒發建設工程竣工驗收備案證書。

Construction Permit（施工許可證）

A permit for the construction company to commence construction on a piece of land issued by Construction Management Bureau.由建設工程管理局頒發的對于建筑單位可以開始在土地上建設的施工許可。

Engineering Planning Permit（建筑工程規劃許可證）

A permit issued by City Planning Management Bureau for the construction planning which confirms its legitimacy to protect the lawful rights and interests of an entity or individual.It includes time schedule, details in construction area, approved layout, structure, etc.由城市規劃管理局頒發的有關建設工程符合城市規劃要求的法律憑證，用以確認有關建設活動的合法地位，保證有關建設單位和個人的合法權益，內容包括施工進度表、建筑地區詳情、批準規劃和工程結構等。

Land Usage Planning Permit（建設用地規劃許可證）

A permit issued by City Planning Management Bureau which confirms its legitimacy for the land usage planning.由城市規劃管理局頒發的用以確認建設項目位置和范圍符合城市規劃的法律憑證。

State-owned Land Use Right Certificate（國有土地使用產權證）

A certification issued by Administrative Bureaus of Houses and Land Resources certifying that the certificate holder legally has the right to use a piece of State owned land as approved by the governmental authorities.由房屋土地資源管理局頒發的表明土地使用者依法享有國有土地使用權的證明。

第三篇：中英文翻譯

Fundamentals This chapter describes the fundamentals of today’s wireless communications.First a detailed description of the radio channel and its modeling are presented, followed by the introduction of the principle of OFDM multi-carrier transmission.In addition, a general overview of the spread spectrum technique, especially DS-CDMA, is given and examples of potential applications for OFDM and DS-CDMA are analyzed.This introduction is essential for a better understanding of the idea behind the combination of OFDM with the spread spectrum technique, which is briefly introduced in the last part of this chapter.1.1 Radio Channel Characteristics Understanding the characteristics of the communications medium is crucial for the appropriate selection of transmission system architecture, dimensioning of its components, and optimizing system parameters, especially since mobile radio channels are considered to be the most difficult channels, since they suffer from many imperfections like multipath fading, interference, Doppler shift, and shadowing.The choice of system components is totally different if, for instance, multipath propagation with long echoes dominates the radio propagation.Therefore, an accurate channel model describing the behavior of radio wave propagation in different environments such as mobile/fixed and indoor/outdoor is needed.This may allow one, through simulations, to estimate and validate the performance of a given transmission scheme in its several design phases.1.1.1 Understanding Radio Channels In mobile radio channels(see Figure 1-1), the transmitted signal suffers from different effects, which are characterized as follows: Multipath propagation occurs as a consequence of reflections, scattering, and diffraction of the transmitted electromagnetic wave at natural and man-made objects.Thus, at the receiver antenna, a multitude of waves arrives from many different directions with different delays, attenuations, and phases.The superposition of these waves results in amplitude and phase variations of the composite received signal.Doppler spread is caused by moving objects in the mobile radio channel.Changes in the phases and amplitudes of the arriving waves occur which lead to time-variant multipath propagation.Even small movements on the order of the wavelength may result in a totally different wave superposition.The varying signal strength due to time-variant multipath propagation is referred to as fast fading.Shadowing is caused by obstruction of the transmitted waves by, e.g., hills, buildings, walls, and trees, which results in more or less strong attenuation of the signal strength.Compared to fast fading, longer distances have to be covered to significantly change the shadowing constellation.The varying signal strength due to shadowing is called slow fading and can be described by a log-normal distribution [36].Path loss indicates how the mean signal power decays with distance between transmitter and receiver.In free space, the mean signal power decreases with the square of the distance between base station(BS)and terminal station(TS).In a mobile radio channel, where often no line of sight(LOS)path exists, signal power decreases with a power higher than two and is typically in the order of three to five.Variations of the received power due to shadowing and path loss can be efficiently counteracted by power control.In the following, the mobile radio channel is described with respect to its fast fading characteristic.1.1.2 Channel Modeling The mobile radio channel can be characterized by the time-variant channel impulse response h(τ , t)or by the time-variant channel transfer function H(f, t), which is the Fourier transform of h(τ , t).The channel impulse response represents the response of the channel at time t due to an impulse applied at time t ? τ.The mobile radio channel is assumed to be a wide-sense stationary random process, i.e., the channel has a fading statistic that remains constant over short periods of time or small spatial distances.In environments with multipath propagation, the channel impulse response is composed of a large number of scattered impulses received over Np different paths，Where

and ap, fD,p, ?p, and τp are the amplitude, the Doppler frequency, the phase, and the propagation delay, respectively, associated with path p, p = 0,..., Np ? 1.The assigned channel transfer function is

The delays are measured relative to the first detectable path at the receiver.The Doppler Frequency

depends on the velocity v of the terminal station, the speed of light c, the carrier frequency fc, and the angle of incidence αp of a wave assigned to path p.A channel impulse response with corresponding channel transfer function is illustrated in Figure 1-2.The delay power density spectrum ρ(τ)that characterizes the frequency selectivity of the mobile radio channel gives the average power of the channel output as a function of the delay τ.The mean delay τ , the root mean square(RMS)delay spread τRMS and the maximum delay τmax are characteristic parameters of the delay power density spectrum.The mean delay is

Where

Figure 1-2 Time-variant channel impulse response and channel transfer function with frequency-selective fading is the power of path p.The RMS delay spread is defined as Similarly, the Doppler power density spectrum S(fD)can be defined that characterizes the time variance of the mobile radio channel and gives the average power of the channel output as a function of the Doppler frequency fD.The frequency dispersive properties of multipath channels are most commonly quantified by the maximum occurring Doppler frequency fDmax and the Doppler spread fDspread.The Doppler spread is the bandwidth of the Doppler power density spectrum and can take on values up to two times |fDmax|, i.e.，1.1.3Channel Fade Statistics The statistics of the fading process characterize the channel and are of importance for channel model parameter specifications.A simple and often used approach is obtained from the assumption that there is a large number of scatterers in the channel that contribute to the signal at the receiver side.The application of the central limit theorem leads to a complex-valued Gaussian process for the channel impulse response.In the absence of line of sight(LOS)or a dominant component, the process is zero-mean.The magnitude of the corresponding channel transfer function

is a random variable, for brevity denoted by a, with a Rayleigh distribution given by

Where

is the average power.The phase is uniformly distributed in the interval [0, 2π].In the case that the multipath channel contains a LOS or dominant component in addition to the randomly moving scatterers, the channel impulse response can no longer be modeled as zero-mean.Under the assumption of a complex-valued Gaussian process for the channel impulse response, the magnitude a of the channel transfer function has a Rice distribution given by

The Rice factor KRice is determined by the ratio of the power of the dominant path to thepower of the scattered paths.I0 is the zero-order modified Bessel function of first kind.The phase is uniformly distributed in the interval [0, 2π].1.1.4Inter-Symbol(ISI)and Inter-Channel Interference(ICI)The delay spread can cause inter-symbol interference(ISI)when adjacent data symbols overlap and interfere with each other due to different delays on different propagation paths.The number of interfering symbols in a single-carrier modulated system is given by

For high data rate applications with very short symbol duration Td < τmax, the effect of ISI and, with that, the receiver complexity can increase significantly.The effect of ISI can be counteracted by different measures such as time or frequency domain equalization.In spread spectrum systems, rake receivers with several arms are used to reduce the effect of ISI by exploiting the multipath diversity such that individual arms are adapted to different propagation paths.If the duration of the transmitted symbol is significantly larger than the maximum delay Td τmax, the channel produces a negligible amount of ISI.This effect is exploited with multi-carrier transmission where the duration per transmitted symbol increases with the number of sub-carriers Nc and, hence, the amount of ISI decreases.The number of interfering symbols in a multi-carrier modulated system is given by

Residual ISI can be eliminated by the use of a guard interval(see Section 1.2).The maximum Doppler spread in mobile radio applications using single-carrier modulation is typically much less than the distance between adjacent channels, such that the effect of interference on adjacent channels due to Doppler spread is not a problem for single-carrier modulated systems.For multi-carrier modulated systems, the sub-channel spacing Fs can become quite small, such that Doppler effects can cause significant ICI.As long as all sub-carriers are affected by a common Doppler shift fD, this Doppler shift can be compensated for in the receiver and ICI can be avoided.However, if Doppler spread in the order of several percent of the sub-carrier spacing occurs, ICI may degrade the system performance significantly.To avoid performance degradations due to ICI or more complex receivers with ICI equalization, the sub-carrier spacing Fs should be chosen as

such that the effects due to Doppler spread can be neglected(see Chapter 4).This approach corresponds with the philosophy of OFDM described in Section 1.2 and is followed in current OFDM-based wireless standards.Nevertheless, if a multi-carrier system design is chosen such that the Doppler spread is in the order of the sub-carrier spacing or higher, a rake receiver in the frequency domain can be used [22].With the frequency domain rake receiver each branch of the rake resolves a different Doppler frequency.1.1.5Examples of Discrete Multipath Channel Models Various discrete multipath channel models for indoor and outdoor cellular systems with different cell sizes have been specified.These channel models define the statistics of the 5 discrete propagation paths.An overview of widely used discrete multipath channel models is given in the following.COST 207 [8]: The COST 207 channel models specify four outdoor macro cell propagation scenarios by continuous, exponentially decreasing delay power density spectra.Implementations of these power density spectra by discrete taps are given by using up to 12 taps.Examples for settings with 6 taps are listed in Table 1-1.In this table for several propagation environments the corresponding path delay and power profiles are given.Hilly terrain causes the longest echoes.The classical Doppler spectrum with uniformly distributed angles of arrival of the paths can be used for all taps for simplicity.Optionally, different Doppler spectra are defined for the individual taps in [8].The COST 207 channel models are based on channel measurements with a bandwidth of 8–10 MHz in the 900-MHz band used for 2G systems such as GSM.COST 231 [9] and COST 259 [10]: These COST actions which are the continuation of COST 207 extend the channel characterization to DCS 1800, DECT, HIPERLAN and UMTS channels, taking into account macro, micro, and pico cell scenarios.Channel models with spatial resolution have been defined in COST 259.The spatial component is introduced by the definition of several clusters with local scatterers, which are located in a circle around the base station.Three types of channel models are defined.The macro cell type has cell sizes from 500 m up to 5000 m and a carrier frequency of 900 MHz or 1.8 GHz.The micro cell type is defined for cell sizes of about 300 m and a carrier frequency of 1.2 GHz or 5 GHz.The pico cell type represents an indoor channel model with cell sizes smaller than 100 m in industrial buildings and in the order of 10 m in an office.The carrier frequency is 2.5 GHz or 24 GHz.COST 273: The COST 273 action additionally takes multi-antenna channel models into account, which are not covered by the previous COST actions.CODIT [7]: These channel models define typical outdoor and indoor propagation scenarios for macro, micro, and pico cells.The fading characteristics of the various propagation environments are specified by the parameters of the Nakagami-m distribution.Every environment is defined in terms of a number of scatterers which can take on values up to 20.Some channel models consider also the angular distribution of the scatterers.They have been developed for the investigation of 3G system proposals.Macro cell channel type models have been developed for carrier frequencies around 900 MHz with 7 MHz bandwidth.The micro and pico cell channel type models have been developed for carrier frequencies between 1.8 GHz and 2 GHz.The bandwidths of the measurements are in the range of 10–100 MHz for macro cells and around 100 MHz for pico cells.JTC [28]: The JTC channel models define indoor and outdoor scenarios by specifying 3 to 10 discrete taps per scenario.The channel models are designed to be applicable for wideband digital mobile radio systems anticipated as candidates for the PCS(Personal Communications Systems)common air interface at carrier frequencies of about 2 GHz.UMTS/UTRA [18][44]: Test propagation scenarios have been defined for UMTS and UTRA system proposals which are developed for frequencies around 2 GHz.The modeling of the multipath propagation corresponds to that used by the COST 207 channel models.HIPERLAN/2 [33]: Five typical indoor propagation scenarios for wireless LANs in the 5 GHz frequency band have been defined.Each scenario is described by 18discrete taps of the delay power density spectrum.The time variance of the channel(Doppler spread)is modeled by a classical Jake’s spectrum with a maximum terminal speed of 3 m/h.Further channel models exist which are, for instance, given in [16].1.1.6Multi-Carrier Channel Modeling Multi-carrier systems can either be simulated in the time domain or, more computationally efficient, in the frequency domain.Preconditions for the frequency domain implementation are the absence of ISI and ICI, the frequency nonselective fading per sub-carrier, and the time-invariance during one OFDM symbol.A proper system design approximately fulfills these preconditions.The discrete channel transfer function adapted to multi-carrier signals results in

where the continuous channel transfer function H(f, t)is sampled in time at OFDM symbol rate s and in frequency at sub-carrier spacing Fs.The duration

s is the total OFDM symbol duration including the guard interval.Finally, a symbol transmitted onsub-channel n of the OFDM symbol i is multiplied by the resulting fading amplitude an,i and rotated by a random phase ?n,i.The advantage of the frequency domain channel model is that the IFFT and FFT operation for OFDM and inverse OFDM can be avoided and the fading operation results in one complex-valued multiplication per sub-carrier.The discrete multipath channel models introduced in Section 1.1.5 can directly be applied to(1.16).A further simplification of the channel modeling for multi-carrier systems is given by using the so-called uncorrelated fading channel models.1.1.6.1Uncorrelated Fading Channel Models for Multi-Carrier Systems These channel models are based on the assumption that the fading on adjacent data symbols after inverse OFDM and de-interleaving can be considered as uncorrelated [29].This assumption holds when, e.g., a frequency and time interleaver with sufficient interleaving depth is applied.The fading amplitude an,i is chosen from a distribution p(a)according to the considered cell type and the random phase ?n,I is uniformly distributed in the interval [0,2π].The resulting complex-valued channel fading coefficient is thus generated independently for each sub-carrier and OFDM symbol.For a propagation scenario in a macro cell without LOS, the fading amplitude an,i is generated by a Rayleigh distribution and the channel model is referred to as an uncorrelated Rayleigh fading channel.For smaller cells where often a dominant propagation component occurs, the fading amplitude is chosen from a Rice distribution.The advantages of the uncorrelated fading channel models for multi-carrier systems are their simple implementation in the frequency domain and the simple reproducibility of the simulation results.1.1.7Diversity The coherence bandwidth of a mobile radio channel is the bandwidth over which the signal propagation characteristics are correlated and it can be approximated by

The channel is frequency-selective if the signal bandwidth B is larger than the coherence bandwidth.On the other hand, if B is smaller than , the channel is frequency nonselective or flat.The coherence bandwidth of the channel is of importance for evaluating the performance of spreading and frequency interleaving techniques that try to exploit the inherent frequency diversity Df of the mobile radio channel.In the case of multi-carrier transmission, frequency diversity is exploited if the separation of sub-carriers transmitting the same information exceeds the coherence bandwidth.The maximum achievable frequency diversity Df is given by the ratio between the signal bandwidth B and the coherence bandwidth，The coherence time of the channel is the duration over which the channel characteristics can be considered as time-invariant and can be approximated by

If the duration of the transmitted symbol is larger than the coherence time, the channel is time-selective.On the other hand, if the symbol duration is smaller than , the channel is time nonselective during one symbol duration.The coherence time of the channel is of importance for evaluating the performance of coding and interleaving techniques that try to exploit the inherent time diversity DO of the mobile radio channel.Time diversity can be exploited if the separation between time slots carrying the same information exceeds the coherence time.A number of Ns successive time slots create a time frame of duration Tfr.The maximum time diversity Dt achievable in one time frame is given by the ratio between the duration of a time frame and the coherence time, A system exploiting frequency and time diversity can achieve the overall diversity

The system design should allow one to optimally exploit the available diversity DO.For instance, in systems with multi-carrier transmission the same information should be transmitted on different sub-carriers and in different time slots, achieving uncorrelated faded replicas of the information in both dimensions.Uncoded multi-carrier systems with flat fading per sub-channel and time-invariance during one symbol cannot exploit diversity and have a poor performance in time and frequency selective fading channels.Additional methods have to be applied to exploit diversity.One approach is the use of data spreading where each data symbol is spread by a spreading code of length L.This, in combination with interleaving, can achieve performance results which are given for

by the closed-form solution for the BER for diversity reception in Rayleigh fading channels according to [40]

Whererepresents the combinatory function，and σ2 is the variance of the noise.As soon as the interleaving is not perfect or the diversity offered by the channel is smaller than the spreading code length L, or MCCDMA with multiple access interference is applied,(1.22)is a lower bound.For L = 1, the performance of an OFDM system without forward error correction(FEC)is obtained, 9

which cannot exploit any diversity.The BER according to(1.22)of an OFDM(OFDMA, MC-TDMA)system and a multi-carrier spread spectrum(MC-SS)system with different spreading code lengths L is shown in Figure 1-3.No other diversity techniques are applied.QPSK modulation is used for symbol mapping.The mobile radio channel is modeled as uncorrelated Rayleigh fading channel(see Section 1.1.6).As these curves show, for large values of L, the performance of MC-SS systems approaches that of an AWGN channel.Another form of achieving diversity in OFDM systems is channel coding by FEC, where the information of each data bit is spread over several code bits.Additional to the diversity gain in fading channels, a coding gain can be obtained due to the selection of appropriate coding and decoding algorithms.中文翻譯 1基本原理

這章描述今日的基本面的無線通信。第一一個的詳細說明無線電頻道，它的模型被介紹，跟隨附近的的介紹的原則的參考正交頻分復用多載波傳輸。此外，一個一般概觀的擴頻技術，尤其ds-cdma，被給，潛力的例子申請參考正交頻分復用，DS對1。分配的通道傳輸功能是

有關的延誤測量相對于第一個在接收器檢測到的路徑。多普勒頻率

取決于終端站，光速c，載波頻率fc的速度和發病路徑分配給速度v波αp角度頁具有相應通道傳輸信道沖激響應函數圖1-2所示。

延遲功率密度譜ρ（τ）為特征的頻率選擇性移動無線電頻道給出了作為通道的輸出功能延遲τ平均功率。平均延遲τ，均方根（RMS）的時延擴展τRMS和最大延遲τmax都是延遲功率密度譜特征參數。平均時延特性參數為

有

圖1-2時變信道沖激響應和通道傳遞函數頻率選擇性衰落是權力頁的路徑均方根時延擴展的定義為 同樣，多普勒頻譜的功率密度（FD）的特點可以定義

在移動時變無線信道，并給出了作為一種金融衍生工具功能的多普勒頻率通道輸出的平均功率。多徑信道頻率分散性能是最常見的量化發生的多普勒頻率和多普勒fDmax蔓延fDspread最大。多普勒擴散是功率密度的多普勒頻譜帶寬，可價值觀需要兩年時間| fDmax|，即

1.1.3頻道淡出統計

在衰落過程中的統計特征和重要的渠道是信道模型參數規格。一個簡單而經常使用的方法是從假設有一個通道中的散射，有助于在大量接收端的信號。該中心極限定理的應用導致了復雜的值的高斯信道沖激響應過程。在對視線（LOS）或線的主要組成部分的情況下，這個過程是零的意思。相應的通道傳遞函數幅度

是一個隨機變量，通過給定一個簡短表示由瑞利分布，有

是的平均功率。相均勻分布在區間[0，2π]。

在案件的多通道包含洛杉磯的或主要組件除了隨機移動散射，通道脈沖響應可以不再被建模為均值為零。根據信道脈沖響應的假設一個復雜的值高斯過程，其大小通道的傳遞函數A的水稻分布給出

賴斯因素KRice是由占主導地位的路徑權力的威力比分散的路徑。I0是零階貝塞爾函數的第一階段是一致kind.The在區間[0，2π]分發。

1.1.4符號間（ISI）和通道間干擾（ICI）

延遲的蔓延引起的符號間干擾（ISI）當相鄰的數據符號上的重疊與互相不同的傳播路徑，由于不同的延遲干涉。符號的干擾在單載波調制系統的號碼是給予

對于高數據符號持續時間很短運輸署<蟿MAX時，ISI的影響，這樣一來，速率應用，接收機的復雜性大大增加。對干擾影響，可以抵消，如時間或頻域均衡不同的措施。在擴頻系統，與幾個臂Rake接收機用于減少通過利用多徑分集等，個別武器適應不同的傳播路徑的干擾影響。

如果發送符號的持續時間明顯高于大的最大延遲運輸署蟿最大，渠道產生ISI的微不足道。這種效果是利用多載波傳輸的地方，每發送符號的增加與子載波數控數目，因此，ISI的金額減少的持續時間。符號的干擾多載波調制系統的號碼是給予

可以消除符號間干擾由一個保護間隔（見1.2節）的使用。

最大多普勒在移動無線應用傳播使用單載波調制通常比相鄰通道，這樣，干擾對由于多普勒傳播相鄰通道的作用不是一個單載波調制系統的問題距離。對于多載波調制系統，子通道間距FS可以變得非常小，這樣可以造成嚴重的多普勒效應ICI的。只要所有子載波只要是一個共同的多普勒頻移金融衍生工具的影響，這可以補償多普勒頻移在接收器和ICI是可以避免的。但是，如果在對多普勒子載波間隔為幾個百分點的蔓延情況，卜內門可能會降低系統的性能顯著。為了避免性能降級或因與ICI卜內門更復雜的接收機均衡，子載波間隔財政司司長應定為

這樣說，由于多普勒效應可以忽略不擴散（見第4章）。這種方法對應于OFDM的1.2節中所述，是目前基于OFDM的無線標準遵循的理念。

不過，如果多載波系統的設計選擇了這樣的多普勒展寬在子載波間隔或更高，秩序是在頻率RAKE接收機域名可以使用[22]。隨著頻域RAKE接收機每個支部耙解決了不同的多普勒頻率。

1.1.5多徑信道模型的離散的例子

各類離散多與不同的細胞大小的室內和室外蜂窩系統的信道模型已經被指定。這些通道模型定義的離散傳播路徑的統計信息。一種廣泛使用的離散多徑信道模型概述于下。造價207[8]：成本207信道模型指定連續四個室外宏蜂窩傳播方案，指數下降延遲功率密度譜。這些頻道功率密度的離散譜的實現都是通過使用多達12個頻道。與6頻道設置的示例列于表1-1。在這種傳播環境的幾個表中的相應路徑延遲和電源配置給出。丘陵地形導致最長相呼應。

經典的多普勒頻譜與均勻分布的到達角路徑可以用于簡化所有的頻道。或者，不同的多普勒譜定義在[8]個人頻道。207信道的成本模型是基于一個8-10兆赫的2G，如GSM系統中使用的900兆赫頻段信道帶寬的測量。造價231[9]和造價259[10]：這些費用是行動的延續成本207擴展通道特性到DCS1800的DECT，HIPERLAN和UMTS的渠道，同時考慮到宏觀，微觀和微微小區的情況為例。空間分辨率與已定義的通道模型在造價259。空間部分是介紹了與當地散射，這是在基站周圍設幾組圓的定義。三種類型的通道模型定義。宏細胞類型具有高達500?5000米，載波頻率為900兆赫或1.8 GHz的單元尺寸。微細胞類型被定義為細胞體積約300米，1.2 GHz或5 GHz載波頻率。細胞類型代表的Pico與細胞體積小于100工業建筑物和辦公室中的10 m階米室內信道模型。載波頻率為2.5 GHz或24千兆赫。造價273：成本273行動另外考慮到多天線信道模型，這是不是由先前的費用的行為包括在內。

CODIT [7]：這些通道模型定義的宏，微，微微蜂窩和室外和室內傳播的典型案例。各種傳播環境的衰落特性是指定的在NakagamiSS）的不同擴頻碼L是長度，如圖1-3所示的系統。沒有其他的分集技術被應用。QPSK調制用于符號映射。移動無線信道建模為不相關瑞利衰落信道（見1.1.6）。由于這些曲線顯示，辦法，AWGN信道的一對L時，對MC-SS系統性能有很大價值。

另一種實現形式的OFDM系統的多樣性是由前向糾錯信道編碼，在這里，每個數據位的信息分散在幾個代碼位。附加在衰落信道分集增益，編碼增益一個可因適當的編碼和解碼算法的選擇。

第四篇：中英文翻譯

蓄電池 battery 充電 converter 轉換器 charger

開關電器 Switch electric 按鈕開關 Button to switch 電源電器 Power electric 插頭插座 Plug sockets

第五篇：中英文翻譯

特種加工工藝

介紹

傳統加工如車削、銑削和磨削等，是利用機械能將金屬從工件上剪切掉，以加工成孔或去除余料。特種加工是指這樣一組加工工藝，它們通過各種涉及機械能、熱能、電能、化學能或及其組合形式的技術，而不使用傳統加工所必需的尖銳刀具來去除工件表面的多余材料。

傳統加工如車削、鉆削、刨削、銑削和磨削，都難以加工特別硬的或脆性材料。采用傳統方法加工這類材料就意味著對時間和能量要求有所增加，從而導致成本增加。在某些情況下，傳統加工可能行不通。由于在加工過程中會產生殘余應力，傳統加工方法還會造成刀具磨損，損壞產品質量。基于以下各種特殊理由，特種加工工藝或稱為先進制造工藝，可以應用于采用傳統加工方法不可行，不令人滿意或者不經濟的場合：

1.對于傳統加工難以夾緊的非常硬的脆性材料； 2.當工件柔性很大或很薄時； 3.當零件的形狀過于復雜時；

4.要求加工出的零件沒有毛刺或殘余應力。

傳統加工可以定義為利用機械（運動）能的加工方法，而特種加工利用其他形式的能量，主要有如下三種形式： 1.熱能； 2.化學能； 3.電能。

為了滿足額外的加工條件的要求，已經開發出了幾類特種加工工藝。恰當地使用這些加工工藝可以獲得很多優于傳統加工工藝的好處。常見的特種加工工藝描述如下。

電火花加工

電火花加工是使用最為廣泛的特種加工工藝之一。相比于利用不同刀具進行金屬切削和磨削的常規加工，電火花加工更為吸引人之處在于它利用工件和電極間的一系列重復產生的（脈沖）離散電火花所產生的熱電作用，從工件表面通過電腐蝕去除掉多余的材料。

傳統加工工藝依靠硬質刀具或磨料去除較軟的材料，而特種加工工藝如電火花加工，則是利用電火花或熱能來電蝕除余料，以獲得所需的零件形狀。因此，材料的硬度不再是電火花加工中的關鍵因素。

電火花加工是利用存儲在電容器組中的電能（一般為50V/10A量級）在工具電極（陰極）和工件電極（陽極）之間的微小間隙間進行放電來去除材料的。如圖6.1所示，在EDM操作初始，在工具電極和工件電極間施以高電壓。這個高電壓可以在工具電極和工件電極窄縫間的絕緣電介質中產生電場。這就會使懸浮在電介質中的導電粒子聚集在電場最強處。當工具電極和工件電極之間的勢能差足夠大時，電介質被擊穿，從而在電介質流體中會產生瞬時電火花，將少量材料從工件表面蝕除掉。每次電火花所蝕除掉的材料量通常在10-5～10-6mm3范圍內。電極之間的間隙只有千分之幾英寸，通過伺服機構驅動和控制工具電極的進給使該值保持常量。化學加工

化學加工是眾所周知的特種加工工藝之一，它將工件浸入化學溶液通過腐蝕溶解作用將多余材料從工件上去除掉。該工藝是最古老的特種加工工藝，主要用于凹腔和輪廓加工，以及從具有高的比剛度的零件表面去除余料。化學加工廣泛用于為多種工業應用（如微機電系統和半導體行業）制造微型零件。

化學加工將工件浸入到化學試劑或蝕刻劑中，位于工件選區的材料通過發生在金屬溶蝕或化學溶解過程中的電化學微電池作用被去除掉。而被稱為保護層的特殊涂層所保護下的區域中的材料則不會被去除。不過，這種受控的化學溶解過程同時也會蝕除掉所以暴露在表面的材料，盡管去除的滲透率只有0.0025～0.1 mm/min。該工藝采用如下幾種形式：凹坑加工、輪廓加工和整體金屬去除的化學銑，在薄板上進行蝕刻的化學造型，在微電子領域中利用光敏抗蝕劑完成蝕刻的光化學加工(PCM)，采用弱化學試劑進行拋光或去毛刺的電化學拋光，以及利用單一化學活性噴射的化學噴射加工等。如圖6.2a所示的化學加工示意圖，由于蝕刻劑沿垂直和水平方向開始蝕除材料，鉆蝕（又稱為淘蝕）量進一步加大，如圖6.2b所示的保護體邊緣下面的區域。在化學造型中最典型的公差范圍可保持在材料厚度的±10%左右。為了提高生產率，在化學加工前，毛坯件材料應采用其他工藝方法（如機械加工）進行預成形加工。濕度和溫度也會導致工件尺寸發生改變。通過改變蝕刻劑和控制工件加工環境，這種尺寸改變可以減小到最小。

電化學加工

電化學金屬去除方法是一種最有用的特種加工方法。盡管利用電解作用作為金屬加工手段是近代的事，但其基本原理是法拉第定律。利用陽極溶解，電化學加工可以去除具有導電性質工件的材料，而無須機械能和熱能。這個加工過程一般用于在高強度材料上加工復雜形腔和形狀，特別是在航空工業中如渦輪機葉片、噴氣發動機零件和噴嘴，以及在汽車業（發動機鑄件和齒輪）和醫療衛生業中。最近，還將電化學加工應用于電子工業的微加工中。

圖6.3所示的是一個去除金屬的電化學加工過程，其基本原理與電鍍原理正好相反。在電化學加工過程中，從陽極（工件）上蝕除下的粒子移向陰極（加工工具）。金屬的去除由一個合適形狀的工具電極來完成，最終加工出來的零件具有給定的形狀、尺寸和表面光潔度。在電化學加工過程中，工具電極的形狀逐漸被轉移或復制到工件上。型腔的形狀正好是與工具相匹配的陰模的形狀。為了獲得電化學過程形狀復制的高精度和高的材料去除率，需要采用高的電流密度（范圍為10～100 A/cm2)和低電壓（范圍為8～30V）。通過將工具電極向去除工件表面材料的方向進給，加工間隙要維持在0.1 mm范圍內，而進給率一般為0.1～20 mm/min左右。泵壓后的電解液以高達5～50 m/s的速度通過間隙，將溶解后的材料、氣體和熱量帶走。因此，當被蝕除的材料還沒來得及附著到工具電極上時，就被電解液帶走了。

作為一種非機械式金屬去除加工方法，ECM可以以高切削量加工任何導電材料，而無須考慮材料的機械性能。特別是在電化學加工中，材料去除率與被加工件的硬度、韌性及其他特性無關。對于利用機械方法難于加工的材料，電化學加工可以保證將該材料加工出復雜形狀的零件，這就不需要制造出硬度高于工件的刀具，而且也不會造成刀具磨損。由于工具和工件間沒有接觸，電化學加工是加工薄壁、易變形零件及表面容易破裂的脆性材料的首選。激光束加工

LASER是英文Light Amplification by Stimulated Emission of Radiation 各單詞頭一個字母所組成的縮寫詞。雖然激光在某些場合可用來作為放大器，但它的主要用途是光激射振蕩器，或者是作為將電能轉換為具有高度準直性光束的換能器。由激光發射出的光能具有不同于其他光源的特點：光譜純度好、方向性好及具有高的聚焦功率密度。

激光加工就是利用激光和和靶材間的相互作用去除材料。簡而言之，這些加工工藝包括激光打孔、激光切割、激光焊接、激光刻槽和激光刻劃等。

激光加工（圖6.4）可以實現局部的非接觸加工，而且對加工件幾乎沒有作用力。這種加工工藝去除材料的量很小，可以說是“逐個原子”地去除材料。由于這個原因，激光切削所產生的切口非常窄。激光打孔深度可以控制到每個激光脈沖不超過一微米，且可以根據加工要求很靈活地留下非常淺的永久性標記。采用這種方法可以節省材料，這對于貴重材料或微加工中的精密結構而言非常重要。可以精確控制材料去除率使得激光加工成為微制造和微電子技術中非常重要的加工方法。厚度小于20 mm的板材的激光切割加工速度快、柔性好、質量高。另外，通過套孔加工還可有效實現大孔及復雜輪廓的加工。

激光加工中的熱影響區相對較窄，其重鑄層只有幾微米。基于此，激光加工的變形可以不予考慮。激光加工適用于任何可以很好地吸收激光輻射的材料，而傳統加工工藝必須針對不同硬度和耐磨性的材料選擇合適的刀具。采用傳統加工方法，非常難以加工硬脆材料如陶瓷等，而激光加工是解決此類問題的最好選擇。

激光切割的邊緣光滑且潔凈，無須進一步處理。激光打孔可以加工用其他方法難以加工的高深徑比的孔。激光加工可以加工出高質量的小盲孔、槽、表面微造型和表面印痕。激光技術正處于高速發展期，激光加工也如此。激光加工不會掛渣，沒有毛邊，可以精確控制幾何精度。隨著激光技術的快速發展，激光加工的質量正在穩步提高。

超聲加工

超聲加工為日益增長的對脆性材料如單晶體、玻璃、多晶陶瓷材料的加工需求及不斷提高的工件復雜形狀和輪廓加工提供了解決手段。這種加工過程不產生熱量、無化學反應，加工出的零件在微結構、化學和物理特性方面都不發生變化，可以獲得無應力加工表面。因此，超聲加工被廣泛應用于傳統加工難以切削的硬脆材料。在超聲加工中，實際切削由液體中的懸浮磨粒或者旋轉的電鍍金剛石工具來完成。超聲加工的變型有靜止（傳統）超聲加工和旋轉超聲加工。

傳統的超聲加工是利用作為小振幅振動的工具與工件之間不斷循環的含有磨粒的漿料的磨蝕作用去除材料的。成形工具本身并不磨蝕工件，是受激振動的工具通過激勵漿料液流中的磨料不斷緩和而均勻地磨損工件，從而在工件表面留下與工具相對應的精確形狀。音極工具振動的均勻性使超聲加工只能完成小型零件的加工，特別是直徑小于100 mm 的零件。

超聲加工系統包括音極組件、超聲發生器、磨料供給系統及操作人員的控制。音極是暴露在超聲波振動中的一小塊金屬或工具，它將振動能傳給某個元件，從而激勵漿料中的磨粒。超聲加工系統的示意圖如圖6.5所示。音極/工具組件由換能器、變幅桿和音極組成。換能器將電脈沖轉換成垂直沖程，垂直沖程再傳給變幅桿進行放大或壓抑。調節后的沖程再傳給音極/工具組件。此時，工具表面的振動幅值為20～50μm。工具的振幅通常與所使用的磨粒直徑大致相等。

磨料供給系統將由水和磨粒組成的漿料送至切削區，磨粒通常為碳化硅或碳化硼。另外，除了提供磨粒進行切削外，漿料還可對音極進行冷卻，并將切削區的磨粒和切屑帶走。

Nontraditional Machining Processes Introduction

Traditional or conventional machining, such as turning, milling, and grinding etc., uses mechanical energy to shear metal against another substance to create holes or remove material.Nontraditional machining processes are defined as a group of processes that remove excess material by various techniques involving mechanical, thermal, electrical or chemical energy or combinations of these energies but do not use a sharp cutting tool as it is used in traditional manufacturing processes.Extremely hard and brittle materials are difficult to be machined by traditional machining processes.Using traditional methods to machine such materials means increased demand for time and energy and therefore increases in costs;in some cases traditional machining may not be feasible.Traditional machining also results in tool wear and loss of quality in the product owing to induced residual stresses during machining.Nontraditional machining processes, also called unconventional machining process or advanced manufacturing processes, are employed where traditional machining processes are not feasible, satisfactory or economical due to special reasons as outlined below: 1.Very hard fragile materials difficult to clamp for traditional machining;2.When the workpiece is too flexible or slender;3.When the shape of the part is too complex;4.Parts without producing burrs or inducing residual stresses.Traditional machining can be defined as a process using mechanical(motion)energy.Non-traditional machining utilizes other forms of energy;the three main forms of energy used in non-traditional machining processes are as follows: 1.Thermal energy;2.Chemical energy;3.Electrical energy.Several types of nontraditional machining processes have been developed to meet extra required machining conditions.When these processes are employed properly, they offer many advantages over traditional machining processes.The common nontraditional machining processes are described in the following section.Electrical Discharge Machining(EDM)

Electrical discharge machining(EDM)sometimes is colloquially referred to as spark machining, spark eroding, burning, die sinking or wire erosion.It is one of the most widely used non-traditional machining processes.The main attraction of EDM over traditional machining processes such as metal cutting using different tools and grinding is that this technique utilizes thermoelectric process to erode undesired materials from the workpiece by a series of rapidly recurring discrete electrical sparks between workpiece and electrode.The traditional machining processes rely on harder tool or abrasive material to remove softer material whereas nontraditional machining processes such as EDM uses electrical spark or thermal energy to erode unwanted material in order to create desired shapes.So, the hardness of the material is no longer a dominating factor for EDM process.EDM removes material by discharging an electrical current, normally stored in a capacitor bank, across a small gap between the tool(cathode)and the workpiece(anode)typically in the order of 50 volts/10amps.As shown in Fig.6.1, at the beginning of EDM operation, a high voltage is applied across the narrow gap between the electrode and the workpiece.This high voltage induces an electric field in the insulating dielectric that is present in narrow gap between electrode and workpiece.This causes conducting particles suspended in the dielectric to concentrate at the points of strongest electrical field.When the potential difference between the electrode and the workpiece is sufficiently high, the dielectric breaks down and a transient spark discharges through the dielectric fluid, removing small amount of material from the workpiece surface.The volume of the material removed per spark discharge is typically in the range of 10-5 to 10-6 mm3.The gap is only a few thousandths of an inch, which is maintained at a constant value by the servomechanism that actuates and controls the tool feed.Chemical Machining(CM)

Chemical machining(CM)is a well known non-traditional machining process in which metal is removed from a workpiece by immersing it into a chemical solution.The process is the oldest of the nontraditional processes and has been used to produce pockets and contours and to remove materials from parts having a high strength-to-weight ratio.Moreover, the chemical machining method is widely used to produce micro-components for various industrial applications such as microelectromechanical systems(MEMS)and semiconductor industries.In CM material is removed from selected areas of workpiece by immersing it in a chemical reagents or etchants, such as acids and alkaline solutions.Material is removed by microscopic electrochemical cell action which occurs in corrosion or chemical dissolution of a metal.Special coatings called maskants protect areas from which the metal is not to be removed.This controlled chemical dissolution will simultaneously etch all exposed surfaces even though the penetration rates of the material removed may be only 0.0025-0.1mm/min.The basic process takes many forms: chemical milling of pockets, contours, overall metal removal, chemical blanking for etching through thin sheets;photochemical machining(pcm)for etching by using of photosensitive resists in microelectronics;chemical or electrochemical polishing where weak chemical reagents are used(sometimes with remote electric assist)for polishing or deburring and chemical jet machining where a single chemically active jet is used.A schematic of chemical machining process is shown in Fig.6.2a.Because the etchant attacks the material in both vertical and horizontal directions, undercuts may develop(as shown by the areas under the edges of the maskant in Fig.6.2b).Typically, tolerances of ±10% of the material thickness can be maintained in chemical blanking.In order to improve the production rate, the bulk of the workpiece should be shaped by other processes(such as by machining)prior to chemical machining.Dimensional variations can occur because of size changes in workpiece due to humidity and temperature.This variation can be minimized by properly selecting etchants and controlling the environment in the part generation and the production area in the plant.Electrochemical Machining(ECM)

Electrochemical metal removal is one of the more useful nontraditional machining processes.Although the application of electrolytic machining as a metal-working tool is relatively new, the basic principles are based on Faraday laws.Thus, electrochemical machining can be used to remove electrically conductive workpiece material through anodic dissolution.No mechanical or thermal energy is involved.This process is generally used to machine complex cavities and shapes in high-strength materials, particularly in the aerospace industry for the mass production of turbine blades, jet-engine parts, and nozzles, as well as in the automotive(engines castings and gears)and medical industries.More recent applications of ECM include micromachining for the electronics industry.Electrochemical machining(ECM), shown in Fig.6.3, is a metal-removal process based on the principle of reverse electroplating.In this process, particles travel from the anodic material(workpiece)toward the cathodic material(machining tool).Metal removal is effected by a suitably shaped tool electrode, and the parts thus produced have the specified shape, dimensions, and surface finish.ECM forming is carried out so that the shape of the tool electrode is transferred onto, or duplicated in, the workpiece.The cavity produced is the female mating image of the tool shape.For high accuracy in shape duplication and high rates of metal removal, the process is operated at very high current densities of the order 10-100 A/cm2,at relative low voltage usually from 8 to 30 V, while maintaining a very narrow machining gap(of the order of 0.1 mm)by feeding the tool electrode with a feed rate from 0.1 to 20 mm/min.Dissolved material, gas, and heat are removed from the narrow machining gap by the flow of electrolyte pumped through the gap at a high velocity(5-50 m/s), so the current of electrolyte fluid carries away the deplated material before it has a chance to reach the machining tool.Being a non-mechanical metal removal process, ECM is capable of machining any electrically conductive material with high stock removal rates regardless of their mechanical properties.In particular, removal rate in ECM is independent of the hardness, toughness and other properties of the material being machined.The use of ECM is most warranted in the manufacturing of complex-shaped parts from materials that lend themselves poorly to machining by other, above all mechanical methods.There is no need to use a tool made of a harder material than the workpiece, and there is practically no tool wear.Since there is no contact between the tool and the work, ECM is the machining method of choice in the case of thin-walled, easily deformable components and also brittle materials likely to develop cracks in the surface layer.Laser Beam Machining(LBM)

LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.Although the laser is used as a light amplifier in some applications, its principal use is as an optical oscillator or transducer for converting electrical energy into a highly collimated beam of optical radiation.The light energy emitted by the laser has several characteristics which distinguish it from other light sources: spectral purity, directivity and high focused power density.Laser machining is the material removal process accomplished through laser and target material interactions.Generally speaking, these processes include laser drilling, laser cutting, laser welding, and laser grooving, marking or scribing.Laser machining(Fig.6.4)is localized, non-contact machining and is almost reacting-force free.This process can remove material in very small amount and is said to remove material “atom by atom”.For this reason, the kerf in laser cutting is usually very narrow , the depth of laser drilling can be controlled to less than one micron per laser pulse and shallow permanent marks can be made with great flexibility.In this way material can be saved, which may be important for precious materials or for delicate structures in micro-fabrications.The ability of accurate control of material removal makes laser machining an important process in micro-fabrication and micro-electronics.Also laser cutting of sheet material with thickness less than 20mm can be fast, flexible and of high quality, and large holes or any complex contours can be efficiently made through trepanning.Heat Affected Zone(HAZ)in laser machining is relatively narrow and the re-solidified layer is of micron dimensions.For this reason, the distortion in laser machining is negligible.LBM can be applied to any material that can properly absorb the laser irradiation.It is difficult to machine hard materials or brittle materials such as ceramics using traditional methods, laser is a good choice for solving such difficulties.Laser cutting edges can be made smooth and clean, no further treatment is necessary.High aspect ratio holes with diameters impossible for other methods can be drilled using lasers.Small blind holes, grooves, surface texturing and marking can be achieved with high quality using LBM.Laser technology is in rapid progressing, so do laser machining processes.Dross adhesion and edge burr can be avoided, geometry precision can be accurately controlled.The machining quality is in constant progress with the rapid progress in laser technology.Ultrasonic Machining(USM)

Ultrasonic machining offers a solution to the expanding need for machining brittle materials such as single crystals, glasses and polycrystalline ceramics, and for increasing complex operations to provide intricate shapes and workpiece profiles.This machining process is non-thermal, non-chemical, creates no change in the microstructure, chemical or physical properties of the workpiece and offers virtually stress-free machined surfaces.It is therefore used extensively in machining hard and brittle materials that are difficult to cut by other traditional methods.The actual cutting is performed either by abrasive particles suspended in a fluid, or by a rotating diamond-plate tool.These variants are known respectively as stationary(conventional)ultrasonic machining and rotary ultrasonic machining(RUM).Conventional ultrasonic machining(USM)accomplishes the removal of material by the abrading action of a grit-loaded slurry, circulating between the workpiece and a tool that is vibrated with small amplitude.The form tool itself does not abrade the workpiece;the vibrating tool excites the abrasive grains in the flushing fluid, causing them to gently and uniformly wear away the material, leaving a precise reverse from of the tool shape.The uniformity of the sonotrode-tool vibration limits the process to forming small shapes typically under 100 mm in diameter.The USM system includes the Sonotrode-tool assembly, the generator, the grit system and the operator controls.The sonotrode is a piece of metal or tool that is exposed to ultrasonic vibration, and then gives this vibratory energy in an element to excite the abrasive grains in the slurry.A schematic representation of the USM set-up is shown in Fig.6.5.The sonotrode-tool assembly consists of a transducer, a booster and a sonotrode.The transducer converts the electrical pulses into vertical stroke.This vertical stroke is transferred to the booster, which may amplify or suppress the stroke amount.The modified stroke is then relayed to the sonotrode-tool assembly.The amplitude along the face of the tool typically falls in a 20 to 50 μm range.The vibration amplitude is usually equal to the diameter of the abrasive grit used.The grit system supplies a slurry of water and abrasive grit, usually silicon or boron carbide, to the cutting area.In addition to providing abrasive particles to the cut, the slurry also cools the sonotrode and removes particles and debris from the cutting area.