第一篇:中英對照
行政主體在對行政相對人作出不利行政決定時,是否必須說明理由,二戰之后伴隨民主法治的發展,經歷從無到有的過程。法國、德國、美國、日本及我國臺灣地區和澳門地區的行政程序法都有相關規定,說明理由已成為行政程序中一項重要的制度。行政主體在作出影響對人權利義務的行政行為時,向相對人說明作出該行為的事實根據、法律根據及進行自由裁量時所考慮的公共利益、社會習慣、政策考量等因素。這一方面有利于規范行政主體依法行使行政權,保障行政合法性和合理性,降低行政恣意和專斷的風險;另一方面,將作出行政決定所依據的事實、法律根據及裁量因素告知行政相對人,可以增強相對人對行政決定的理解和認同。此外,如果相對人對行政決定不服,可根據行政決定的依據和理由尋求法律救濟,保障其合法權益。本文以行政程序中的說明理由制度為視角,以我國工商系統推行的說理式行政處罰決定的相關案例,總結我國工商系統說明式行政處罰決定書的特點和問題,并在此基礎之上提出完善建議,以期將說理式行政決定書推廣適用到行政處罰、行政強制等執法領域,增強行政決定的合理性和正當性,更有效地規范行政權力,保障公民合法權益。
Whether the administrative subject has to give the reasons why making negative administrative decision on administrative counterpart, which appears accompany with the development of democracy and the rule of law.The administrative procedure law in France, Germany, the United States, Japan, Taiwan and Macao of china has relative regulations, and giving the reasons has become an important system in administrative procedure system.When the administrative subject takes administrative actions that will impact the rights and obligations of the administrative counterpart, it should explain to the administrative counterpart the fact and foundation and the law, on which it take the action, also it should explain the public interests, social habits, policy considerations and other factors that it has to take into account when make discretions.on one hand, this is conductive to standardize the administrative subject to execute administrative power according to the law, and guarantee the administrative legality and rationality, reduce administrative arbitrariness and abuse of administrative power;on the other hand, to inform the administrative decision basis of facts, law and discretion factors to the administrative counterpart could enhance the understanding and recognition of the decisions for the administrative counterpart.Besides, if the administrative counterpart doesn’t accept the decisions, could according to the foundations and reasons of the administrative decisions seek for legal redress to protect his/her legal interests.This report base on the reasons explanation system to summarize the characteristics and existing problems of the persuasive administrative penalties notifications in our country’s industrial and commercial systems, and make suggestions on how to improve it, in order to make the administrative decision be applicable to administrative penalty, administrative compulsory enforcement and other executive fields, to enhance the rationality and legitimacy of the administrative decision, effectively regulate the use of the administrative power, protect the legal rights and interests of the citizens.本文分為五部分:
The report has five parts:
引言部分簡單介紹我國學界關于行政程序中說明理由制度的研究概況,說明當前關于說明理由制度研究重心和熱點問題。
The brief introduce the general situation of the study of the reasons explanation system in administrative procedure of our law circles, and illustrates the focus and hot issues in current study of the reasons explanation system.第一部分為全文概述,簡要介紹選題依據和來源,從憲政角度分析行政決定的說理性理論基
礎,并從行政機關、行政相對人和受理爭議機關復審三方面分析行政決定說理性的價值所在。第二部分著重研究我國工商系統推行的說理式行政處罰決定書案例,總結工商系統說理式行政處罰決定書的特點及存在的問題。
The first part is the general overview of the report, give a brief introduction to the basis and resource of the selection of the topic, analyze the rationality theory foundation of the administrative decision from the constitutional perspective, and analyze the value of the administrative decision rationality from the administrative organ, the administrative counterpart and the request of the controversy dispute acceptance organ.Part two focuses on the study of the cases on the persuasive administrative penalty notification pushed by our country’s industrial and commercial system, and summarize the characteristics and existing problems of the persuasive administrative penalties notifications in our country’s industrial and commercial systems.第三部分對我國目前關于行政決定說理性的立法規范進行分析,指出當前我國相關立法存在的缺陷和問題。
The third part analyzes the current legal regulations in our country on the rationality of the administrative decisions, and point out the existing defects and problems in our country’s relative laws.
第二篇:清明上河圖中英對照
Riverside Scene at Qingming Festival 清明上河圖
“Riverside Scene at Qingming 清明上河圖是北宋畫家張擇端(960-1127)創作的Festival” is a panoramic(全景的)全景圖.是張擇端唯一現在的杰作,現作為國寶被北painting by Zhang Zeduan(張擇端), 京故宮博物院收藏。an artist in the Northern Song
這幅手卷畫528.7厘米長、24.8厘米寬。它展Dynasty(北宋)(960-1127).It is the
描繪了在清明時節北宋京only existing masterpiece 杰作from 現了當時城鄉的經濟活動,Zhang, and has been collected by 城汴京(當今河南開封市)各個階層的生活場景。這the Palace Museum in Beijing as a 是對當時京城以及當地居民生活情況進行研究的重national treasure(國家寶藏).要參考資料。
The hand scroll painting手卷畫is capture:vt.俘獲;奪得;n.捕獲;戰利品,俘虜 528.7 cm long and 24.8 cm wide.It 詞義辨析:arrest,seize,catch,capture,trap這組provides a window展現to the period's
詞都有“抓住,捕捉”的意思,其區別是:arresteconomic activities in urban and rural areas, and captures描繪the daily life 指根據法律或命令進行逮捕并予以監禁或拘留。of people of all ranks in the capital seize側重指以突然、有力地動作迅速抓住或捉住。city of Bianjing(today's Kaifeng, catch普通用詞,指捉住跑動或隱藏中的人或動物,Henan Province)during Qingming 一般指活捉。capture指通過武力或計謀等,戰勝抵Festival in the Northern Song 抗而捉住敵人或動物。trap多指誘捕。本文中captureDynasty.It is an important historical 是“捕捉、捕獲”的意思,捕捉到某一個畫面。如果reference material for the study of the 對應到某幅畫,可以翻譯為“描繪”。providesawindowcity then as well as the life its
譯為“為??提供了窗口”,根據文中大意,可以靈residents rich and poor.The painting is composed of活譯為“展現”。
這幅畫有三部分組成:農村的春景、汴河上繁華由……組成 three parts: spring in the
清明上河圖也因為畫中各rural area, busy Bianhe River ports, 場景以及繁榮的城市街道。and prosperous繁榮的city streets.種自然元素、建筑、船艇以及小橋、集市、店鋪還有The painting is also known for its 人物、風景等在空間上精確合理的布局而聞名于世。geometrically accurate images of 清明上河圖中有550余人,但是他們各著不同服飾,variety natural elements and
表情各異,身體姿勢也是變化萬千。它是中國繪畫中architectures, boats and bridges, market place and stores, people and 最享有盛名的著作,被稱作 “中國的蒙娜麗莎”。scenery.Over 550 people in different Composevt組成,構成;創作(文學、音樂、繪畫等作clothes服飾, expressions表情 and 品);整理,整頓詞義辨析:invent,compose,make, postures姿勢 are shown in the create,design,produce這組詞都有“創造”的意思,painting.It is often considered to be 其區別是:invent主要用于科技領域,指通過思考、the most renowned work among all 研究或實驗制造出新的前所未有、極為有用的東西。the Chinese paintings, and it has compose多指音樂或詩歌、畫的創作。make最普通用been called “China's Mona Lisa.”
詞,指任何東西的創作或制造。create側重創造出來的東西以前并不存在,或者指獨具特色的創作。design主要指在藝術或技術領域的創作設計,強調構思多于實際制造。produce指產品的生產,或作品創作的完成。geometrically 意思是“幾何學上的”geometrically accurate images表面譯為“幾何上精確的圖片”,根據文中的意境,應該是“各個元素
在空間上合理而準確的布局”。
第三篇:ArcGIS中英對照
ArcGIS 9 ArcToolbox 中英文對照表
3D Analyst Tools
Conversion
TIN 三角計算 TIN 域值 TIN 多邊形標志 TIN 節點 TIN 邊 TIN 到柵格 柵格轉 TIN Functional Surface 三維分析工具
轉換
表面功能
插值形狀 表面體積 表面點 表面長度 視線
Raster Interpolation
柵格修補
克里金 地形到柵格 曲線擬合
用文件地形到柵格 自然鄰域 趨勢
距離權重倒數 Raster Math
柵格計算
乘
減
加
取整
浮點
除
Raster Reclass 柵格重分類
切片
查找
用 ASCII 文件重分
類
用表重分類
重分類 Raster Surface 坡向 坡度 填/挖 山影 曲率
柵格表面
等高線 等高線列表 觀察點 視域 TIN Creation
創建 TIN 編輯 TIN TIN Surface
TIN 創建
Analysis Tool:
TIN 表面
TIN 坡度
TIN 方位
TIN 等高線
多邊形插值成多個面
分析工具
提取
剪切
選擇
拆分 Extract
Clip
Select Split Table Select Overlay
Erase Identity
Intersect
表選擇 疊加分析
擦除
查看
相交
對稱差 聯合更新
鄰域分析
緩沖區 多環緩沖區 臨近
點距離 統計表
頻度
總結統計
繪圖工具
掩模工具
Cul-De-Sac 掩模 要素輪廓線掩模 相交圖層掩模
轉換工具
從刪格到...刪格到 ASCII Symmetrical Difference
Union Update Proximity
Buffer Multiple Ring Buffer Near
Point Distance Statistics
Frequency
Summary Statistics
Cartography Tool:
Masking Tools
Cul-De-Sac Masks Feature Outline Masks Intersecting Layers Masks
Conversion Tool:
From Raster
Raster to ASCII
Raster to Float Raster to Point
刪格到浮點 刪格到點 刪格到面 刪格到線 到 CAD
添加 CAD 字段
創建 CAD 擴展實體數據 導出到 CAD 設置 CAD 別名
到 Coverage
要素類到 Coverage 到 dBASE
表到 dBASE
要素類到要素類 要素類到 Geodatabase 導入 CAD 注記
導入 Coverage 注記 從 CAD 導入
柵格到 Geodatabase 表到 Geodatabase 表到表
到柵格
ASCII 到柵格 DEM 到柵格 要素到柵格 浮點到柵格 柵格到其他格式 到 Shapefile Raster to Polygon
Raster to Polyline
To CAD
Add CAD Fields Create CAD XData Export to CAD
Set CAD Alias
To Coverage
Feature Class To Coverage To dBASE
Table to dBASE [multiple] To GeodatabaSE Feature Class To Feature Class Feature Class to Geodatabase [multiple] Import CAD Annotation Import Coverage Annotation Import from CAD Raster To Geodatabase[multiple]
Table to Geodatabase[multiple] Table To Table To Raster
ASCII to Raster DEM to Raster
Feature to Raster
Float to Raster Raster To Other Format
To Shapefile
Coverage Tool: Analysis
Feature Class To Shapefile 要素類到 Shapefile Coverage 工具
分析
提取
剪切
選擇
拆分 Extract Clip
Select Split Overlay Erase Identity
Intersect
疊加
擦除
判別
相交
聯合更新
鄰近 Union Update Proximity
Buffer Near
Point Distance Point Node Thiessen
Conversion
From Coverage
緩沖
近鄰
點距離 點到結點 泰森近似多邊形
轉換
從 Coverage
到 DLG
到 Interchange 文件 到 S57 到 SETS 到 VPF 取消生成 到 Coverage
高級 Tiger 轉換
基本 Tiger 轉換 Export To DLG
Export To Interchange File Export To S57
Export To SETS Export To VPF
Ungenerate To Coverage Advanced Tiger Conversion Basic Tiger Conversion
Generate
Import From DLG Import From Interchange File
生成從 DLG 導入
從 Interchange 文件導入 從 S57 導入 從 SETS 導入 從 VPF 導入
數據管理 集合
追加
要素合成線 Coverage 到區域
線 Coverage 到路徑 Import From S57 Import From SETS Imort From VPF
Data Management
Aggregate
Append Composite Features
Line Coverage To Region
Line Coverage To Route
Polygon Coverage To Region Region To Polygon Coverage
多邊形 Coverage 到區域 區域到多邊形 Coverage 聚集多邊形
分解雙線到中心線
融合消除
查找沖突 簡化建筑物 簡化線或多邊形
刪除索引
索引項
添加項 刪除項 Generalization Aggregate Polygons
一般
Collapse Dual Lines To Centerline Dissolve
Eliminate
Find Conflicts Simplify Building
Simplify Line Or Polygon Indexes Drop Index Index Item
索引
項 Items Add Item
Drop Item
Joins Join Info Tables Projections Define Projection
Project Transform
連接
投影
連接 Info 表 定義投影 投影
變換
添加 XY 坐標 重新計數節點 更新 ID
容差
構建
Clean 創建標注 VPF 圖塊拓撲 Tables Add XY Coordinates
表
Renumber Nodes Update IDs Tolerances Tolerance
容差 拓撲 Topology
Build Clean Create Labels
VPF Tile Topology
Workspace Management
工作空間管理
創建 Coverage
緊湊 Create Coverage
Data Management Tools 數據管理工具
Database
數據庫
Compact Compress
Disconnected Editing
Check In
Check In From Delta Check Out
壓縮
分離編輯
檢入
從增量中檢入 檢出
值域
導出增量
添加編碼值到值域 賦值值域到字段 創建值域
從值域中刪除編碼值 刪除值域 值域到表 從字段刪除值域 為范圍值域設置值 表到值域
要素類
追加注記要素類
計算缺省容限值 Export To Delta Domains
Add Coded Value To Domain Assign Domain To Field
Create Domain
Delete Coded Value From Domain Delete Domain
Domain To Table Remove Domain From Field Set Value For Range Domain Table To Domain Feature class
Append Annotation Feature Classes Calculate Default Cluster Tolerance Calculate Default Spatial Grid Index 計算缺省空間格網索引
Integrate
整合
Update Annotation Feature Class
創建要素類
Features
要素
Add XY Coordinates
更新標記要素類 創建要素類
添加 XY 坐標
檢查幾何形狀 復制要素
刪除要素 要素封裝到多邊形 Check Geometry Copy Features
Delete Features Feature Envelope to Polygon
Feature To Line Feature To Point Feature To Polygon
Feature Vertices To Points Multipart To Singlepart
Polygon To Line Repair Geometry Split Line At Vertices
Fields
Add Field
Assign Default To Field
Calculate Field Delete Field General
Copy
Delete Rename Select Data 追加
Generalization Dissolve
Eliminate
Simplify Line
Smooth Line Indexes
Add Attribute Index Add Spatial Index
Remove Attribute Index Remove Spatial Index Joins
Add Join
Remove Join Layers and Table Views
Make Query Table Make Raster Catalog Layer Make Raster Layer
要素到線 要素到點 要素到多邊形 要素定點到點 多部分到單部分 多邊形到線 修改集合形狀
在定點拆分線
字段
添加字段 設置缺省到字段 計算字段 刪除字段 一般
復制
刪除
重命名 選擇數據
追加
一般
融合消除
簡化線平滑線 索引
添加屬性索引 添加空間索引 刪除屬性索引 刪除空間索引 連接
添加連接 刪除連接
圖層和表的查看
制作查詢表 制作柵格目錄圖層 制作柵格圖層
Make XY Event Layer Save To Layer File
Select Layer By Attribute Select Layer By Location
制作 XY 事件圖層 保存成圖層文件 通過屬性選擇 通過位置選擇 制作表視圖 制作要素圖層 制作表視圖 制作要素圖層
Projections and Transformations 投影和轉換
Feature Batch Project
Project 創建空間參考 Raster Flip
Mirror Project Raster Rescale Rotate Shift War
Define Projection
Raster
Batch Build Pyramids Batch Calculate Statistics Build Pyramids
Calculate Statistics Clip
Composite Bands Copy Raster Copy Raster Catalog Items Create Raster Catalog Delete Raster Catalog Items Mosaic To New Raster Resample
創建柵格數據集
鑲嵌
Relationship Classes
Create Relationship Class Table To Relationship Class Subtypes
Add Subtype Remove Subtype
Set Default Subtype Set Subtype Field
Table
要素
批量投影
投影
創建空間參考
柵格
翻轉
鏡像
投影柵格
重建比例
旋轉
偏移
翹曲
定義投影 柵格
批量建立金字塔
批量計算統計表 建立金字塔 計算統計表 剪切
組合波段 復制柵格 復制柵格目錄項 創建柵格目錄 刪除柵格目錄項
鑲嵌到新的柵格
重采樣
創建柵格數據集
鑲嵌
關系類
創建關系類
表到關系類 子類型
添加子類型
刪除子類型
設置缺省子類型
設置子類型字段
表
Analyze Change Privileges
Copy Rows
分析
改變權限 復制行 刪除行 獲得數目 關聯表 創建表
拓撲
添加要素類型到拓撲 添加規則到拓撲 創建拓撲
從拓撲刪除要素類 從拓撲中刪除規則 設置簇容限值
版本
教驗拓撲
改變版本 創建版本 刪除版本 提交版本 協調版本 注冊版本
工作空間
取消注冊
創建 ArcInfo 工作空間 創建要素數據集 創建文件夾
創建個人 Geodatabase
地理編碼工具
自動生成地理編碼索引 創建地址定位器
取消自動生成地理編碼索引 刪除地址定位器 地理編碼地址 重建地理編碼索引 標準化地址 Delete Rows Get Count
Pivot Table 創建表
Topology
Add Feature Class To Topology Add Rule To Topology Create Topology Remove Feature Class From Topology Remove Rule From Topology Set Cluster Tolerance Validate Topology
Versions
Alter Version
Create Version Delete Version Post Version Reconcile Version
Register As Versioned Unregister As Versioned
Workspace
Create ArcInfo Workspace Create Feature Dataset
Create Folder
Create Personal GDB Geocoding Tools
Automate Geocoding Indexes Create Address Locator
Deautomate Geocoding Indexes Delete Address Locator
Geocode Addresses
Rebuild Geocoding Indexes Standardize Addresses
Geostatistical Analyst Tools
Geostatistical Layer To Grid
地理統計分析工具
導出地理統計圖層到 Grid
線性參考工具
校準路徑 創建路徑 融合路徑事件
Linear Referencing Tools
Calibrate Routes Create Routes
Dissolve Route Events
Locate Features Along Routes
沿路徑定位要素 制作路徑事件圖層 Make Route Event Layer
Overlay Route Events Transform Route Events
Spatial Analyst Tools
Conditional
拾取 條件 設空 Density
核密度 點密度 線密度
Distance
代價分配 代價回聯 代價距離 代價路徑 歐幾里德分配 歐幾里德方向 歐幾里德距離 走廊 路徑距離 路徑距離分配 路徑距離回聯 Extraction
提取值到點 根據屬性提取 用圓提取 用多邊形提取 用掩模提取 用點提取 用矩形提取 采樣 Generalization 區塊組合 多數過濾 收縮 消蝕 細化 聚合 膨脹 邊界清理
疊加路徑事件 轉換路徑事件
空間分析工具
條件
密度
距離
提取
一般
Groundwater
粒子跟蹤 達西流 達西速率 透水層 Hydrology
下陷點 填充 捕捉匯流點 河流分級 河流到要素 河流連接 流向 流域 流程 盆地 累積流量
Interpolation
克里金 地形到柵格 曲線擬合
用文件地形到柵格自然鄰域 趨勢
距離權重倒數 Local
像素統計 分級 合成 大于頻率 小于頻率 普及度 最低位置 最高位置 等于頻率 Map Algebra
單輸出地圖代數 多輸出地圖代數 Math
Bitwise 位與
位右移 位否
位異或
地下水
水文
添補
本地
地圖代數
數學計算
為運算
左位移
按位或 Logical 不等于
為空
大于
大于等于 小于
小于等于
測試
等于
組合與
組合異或
組合或 邏輯與 邏輯否
邏輯異或
邏輯或 Trigonometric
ATan2 余弦
雙曲余弦 雙曲正切 雙曲正弦 反余弦 反雙曲余弦 反雙曲正切 反雙曲正弦 反正切 反正弦 正切
正弦的對數 10 的指數 2 的對數 2 的指數 上取整 下取整 乘
減
加
取整 否
平方
邏輯運算
三角函數
平方根 指數 整除 浮點
絕對值
自然對數
自然指數
除
Multivariate
多元多變量
Isocluster
主成分
創建特征
最大似然性分類
波段組統計
類概率
系統樹圖功能
編輯署名函數
Neighborhood
鄰域
塊統計
點統計
焦點流
焦點統計
線統計
過濾
Overlay
疊加
加權疊加
Raster Creation 柵格創建
創建常量柵格
創建正態柵格
創建隨機柵格
Reclass
重分類
切片
查找
用 ASCII 文件重分
類
用表重分類
重分類 Surface
坡向 坡度 填/挖 山影 曲率 等高線 等高線列表
表面
觀察點 視域 Zonal
區域幾何 區域幾何到表 區域填充 區域統計
區域統計到表
面積制表
Spatial Statistics Tools
Analyzing Patterns
區域
空間統計工具
分析模型
平均鄰近鄰居 空間自相關 群體和群外要素分析
帶渲染群體和群外要素分析 熱點分析 帶渲染熱點分析 測量地理分布
中心要素 定向分布平均線方向平均中心
實用工具
標準間隔距離
計算面積 收集事件 帶渲染收集事件 計算渲染
導出要素表到 Ascii 文本 Average Nearest Neighbor High/Low Clustering[Getis-Ord General G]高/低聚類
Spatial Autocorrelation [Morans I] Mapping Clusters
Cluster and Outlier Analysis
繪制群體
Cluster/Outlier Analysis with Rendering Hot Spot Analysis [Getis-Ord Gi*] Hot Spot Analysis with Rendering
Measuring Geographic Distributions
Central Feature Directional Distribution Linear Directional Mean
Mean Center Standard Distance
Utilities
Calculate Areas Collect Events
Collect Events with Rendering Count Rendering Export Feature Attribute to Ascii Z Score Renderine
第四篇:自我介紹中英對照
大家好,我叫xx,中山大學工商管理本科,09年7月份畢業。我想從三個方面介紹自己:
1)學生工作方面。在學院擔任XX,班級擔任XXX,學校擔任XXXX,負責了學校學院和班級的多項活動。憑借著優異的工作,我獲得了XXXX學生干部獎學金。
2)學術競賽方面。參加挑戰杯獲得XXX,花旗論壇獲得XXX等。
3)社會實踐方面。我曾經在XXX公司實習,而實習的經歷讓我明白了公司對人才的要求,也讓我自己不斷提高自我要求。
接下來就是靠對公司的認識,結合自己的某些事例,拉近自己和公司的距離。最后一句一般都是,相信通過自己在貴公司的學習,一定可以成為XXXX!
My name is xx, a postgraduate student from Tianjin University, and will get my master degree in March 2007.I'd like to summarize myself from 3 aspects:
First, I'm an excellent learner.In my sophomore year, I passed the entrance examination to the Excellent Student Program in Tianjin University and
was recommended as the postgraduate student with special courses, and then I joined the IBM Center in Tianjin University.After finishing my undergradua te courses, my GPA was 3.8 out of 4.5.Second, I'm an excellent problem-solver.During the
last 4 years, I have finished 5 projects, including the Hydraulic Engineering Project Management
System, and so on.And I took part in the Mathematical Contest in Modeling in 2003 and won the second prize in Tianjin region.Last, I'm an excellent team player.I've been serving as the monitor for 6 years and team leader for 2 years.And besides taking more responsibiliti
es, I also placed great emphasis on teamwork, in order to meet the team's go l.
第五篇:中英對照:光纖通信
光纖通信
光纖常被電話公司用于傳遞電話、互聯網,或是有線電視的信號,有時候利用一條光纖就可以同時傳遞上述的所有信號。與傳統的銅線相比,光纖的信號衰減(attenuation)與遭受干擾[來源請求](interference)的情形都改善很多,特別是長距離以及大量傳輸的使用場合中,光纖的優勢更為明顯。然而,在城市之間利用光纖的通信基礎建設(infrastructure)通常施工難度以及材料成本難以控制,完工后的系統維運復雜度與成本也居高不下。因此,早期光纖通信系統多半應用在長途的通信需求中,這樣才能讓光纖的優勢徹底發揮,并且抑制住不斷增加的成本。
從2000年光通信(optical communication)市場崩潰后,光纖通信的成本也不斷下探,目前已經和銅纜為骨干的通信系統不相上下。
對于光纖通信產業而言,1990年光放大器(optical amplifier)正式進入商業市場的應用后,很多超長距離的光纖通信才得以真正實現,例如越洋的海底電纜。到了2002年時,越洋海底電纜的總長已經超過25萬公里,每秒能攜帶的數據量超過2.56Tb,而且根據電信業者的統計,這些數據從2002年后仍然不斷的大幅成長中。
光纖通信的歷史
自古以來,人類對于長距離通信的需求就不曾稍減。隨著時間的前進,從烽火到電報,再到1940年第一條同軸電纜(coaxial cable)正式服役,這些通信系統的復雜度與精細度也不斷的進步。但是這些通信方式各有其極限,使用電氣信號傳遞信息雖然快速,但是傳輸距離會因為電氣信號容易衰減而需要大量的中繼器(repeater);微波(microwave)通信雖然可以使用空氣做介質,可是也會受到載波頻率(carrier frequency)的限制。到了二十世紀中葉,人們才了解使用光來傳遞信息,能帶來很多過去所沒有的顯著好處。
然而,當時并沒有同調性高的發光源(coherent light source),也沒有適合作為傳遞光信號的介質,也所以光通信一直只是概念。直到1960年代,激光(laser)的發明才解決了第一項難題。1970年代康寧公司(Corning Glass Works)發展出高品質低衰減的光纖則是解決了第二項問題,此時信號在光纖中傳遞的衰減量第一次低于光纖通信之父高錕所提出的每公里衰減20分貝
(20dB/km)關卡,證明了光纖作為通信介質的可能性。與此同時使用砷化鎵(GaAs)作為材料的半導體激光(semiconductor laser)也被發明出來,并且憑借著體積小的優勢而大量運用于光纖通信系統中。1976年,第一條速率為44.7Mbit/s的光纖通信系統在美國亞特蘭大的地下管道中誕生。
經過了五年的研發期,第一個商用的光纖通信系統在1980年問市。這個人類史上第一個光纖通信系統使用波長800納米(nanometer)的砷化鎵激光作為光源,傳輸的速率(data rate)達到45Mb/s(bits per second),每10公里需要一個中繼器增強信號。
第二代的商用光纖通信系統也在1980年代初期就發展出來,使用波長1300納米的磷砷化鎵銦(InGaAsp)激光。早期的光纖通信系統雖然受到色散(dispersion)的問題而影響了信號品質,但是1981年單模光纖(single-mode fiber)的發明克服了這個問題。到了1987年時,一個商用光纖通信系統的傳輸速率已經高達1.7Gb/s,比第一個光纖通信系統的速率快了將近四十倍之譜。同時傳輸的功率與信號衰減的問題也有顯著改善,間隔50公里才需要一個中繼器增強信號。1980年代末,EDFA的誕生,堪稱光通信歷史上的一個里程碑似的事件,它使光纖通信可直接進行光中繼,使長距離高速傳輸成為可能,并促使了DWDM的誕生。
第三代的光纖通信系統改用波長1550納米的激光做光源,而且信號的衰減已經低至每公里0.2分貝(0.2dB/km)。之前使用磷砷化鎵銦激光的光纖通信系統常常遭遇到脈波延散(pulse spreading)問題,而科學家則設計出色散遷移光纖(dispersion-shifted fiber)來解決這些問題,這種光纖在傳遞1550納米的光波時,色散幾乎為零,因其可將激光光的光譜限制在單一縱模(longitudinal mode)。這些技術上的突破使得第三代光纖通信系統的傳輸速率達到2.5Gb/s,而且中繼器的間隔可達到100公里遠。
第四代光纖通信系統引進了光放大器(optical amplifier),進一步減少中繼器的需求。另外,波分復用(wavelength-division multiplexing, WDM)技術則大幅增加傳輸速率。這兩項技術的發展讓光纖通信系統的容量以每六個月增加一倍的方式大幅躍進,到了2001年時已經到達10Tb/s的驚人速率,足足是80年代光纖通信系統的200倍之多。近年來,傳輸速率已經進一步增加到14Tb/s,每隔160公里才需要一個中繼器。
第五代光纖通信系統發展的重心在于擴展波分復用器的波長操作范圍。傳統的波長范圍,也就是一般俗稱的“C band”約是1530納米至1570納米之間,新一帶的無水光纖(dry fiber)低損耗的波段則延伸到1300納米至1650納米間。另外一個發展中的技術是引進光孤子(optical soliton)的概念,利用光纖的非線性效應,讓脈波能夠抵抗色散而維持原本的波形。
1990年至2000年間,光纖通信產業受到互聯網泡沫的影響而大幅成長。此外一些新興的網絡應用,如隨選視頻(video on demand)使得互聯網帶寬的成長甚至超過摩爾定律(Moore’s Law)所預期集成電路芯片中晶體管增加的速率。而自互聯網泡沫破滅至2006年為止,光纖通信產業通過企業整并壯大規模,以及委外生產的方式降低成本來延續生命。
現在的發展前沿就是全光網絡了,使光通信完全的代替電信號通訊系統,當然,這還有很長的路要走。
fiber-optic communications
Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals.Due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications.However, infrastructure development within cities was relatively difficult and time-consuming, and fiber-optic systems were complex and expensive to install and operate.Due to these difficulties, fiber-optic communication systems have primarily been installed in long-distance applications, where they can be used to their full transmission capacity, offsetting the increased cost.Since 2000, the prices for fiber-optic communications have dropped considerably.The price for rolling out fiber to the home has currently become more cost-effective than that of rolling out a copper based network.Prices have dropped to $850 per subscriber in the US and lower in countries like The Netherlands, where digging costs are low.Since 1990, when optical-amplification systems became commercially available, the telecommunications industry has laid a vast network of intercity and transoceanic fiber communication lines.By 2002, an intercontinental network of 250,000 km of submarine communications cablewith a capacity of 2.56 Tb/s was completed, and although specific network capacities are privileged information, telecommunications investment reports indicate that network capacity has increased dramatically since 2004.History
In 1966 Charles K.Kao and George hockom proposed optical fibers at STC Laboratories(STL)at Harlow, England, when they showed that the losses of 1000 dB/km in existing glass(compared to 5-10 db/km in coaxial cable)was due to contaminants, which could potentially be removed.Optical fiber was successfully developed in 1970 by Corning Glass Works, with attenuation low enough for communication purposes(about 20dB/km), and at the same time GaAs semiconductor lasers were developed that were compact and therefore suitable for transmitting light through fiber optic cables for long distances.After a period of research starting from 1975, the first commercial fiber-optic communications system was developed, which operated at a wavelength around 0.8 μm and used GaAs semiconductor lasers.This first-generation system operated at a bit rate of 45 Mbps with repeater spacing of up to 10 km.Soon on 22 April, 1977, General Telephone and Electronics sent the first live telephone traffic through fiber optics at a 6 Mbit/s throughput in Long Beach, California.The second generation of fiber-optic communication was developed for commercial use in the early 1980s, operated at 1.3 μm, and used InGaAsP semiconductor lasers.Although these systems were initially limited by dispersion, in 1981 the single-mode fiber was revealed to greatly improve system performance.By 1987, these systems were operating at bit rates of up to 1.7 Gb/s with repeater spacing up to 50 km.The first transatlantic telephone cable to use optical fiber was TAT-8, based on Desurvire optimized laser amplification technology.It went into operation in 1988.Third-generation fiber-optic systems operated at 1.55 μm and had losses of about 0.2 dB/km.They achieved this despite earlier difficulties with pulse-spreading at that wavelength using conventional InGaAsP semiconductor lasers.Scientists overcame this difficulty by using dispersion-shifted fibers designed to have minimal dispersion at
1.55 μm or by limiting the laser spectrum to a single longitudinal mode.These developments eventually allowed third-generation systems to operate commercially at 2.5 Gbit/s with repeater spacing in excess of
km.The fourth generation of fiber-optic communication systems used optical amplification to reduce the need for repeaters and wavelength-division multiplexing to increase data capacity.These two improvements caused a revolution that resulted in the doubling of system capacity every 6 months starting in 1992 until a bit rate of 10 Tb/s was reached by 2001.Recently, bit-rates of up to 14 Tbit/s have been reached over a single 160 km line using optical amplifiers.The focus of development for the fifth generation of fiber-optic communications is on extending the wavelength range over which a WDM system can operate.The conventional wavelength window, known as the C band, covers the wavelength range 1.53-1.57 μm, and the new dry fiber has a low-loss window promising an extension of that range to 1.30-1.65 μm.Other developments include the concept of “optical solitons, “ pulses that preserve their shape by counteracting the effects of dispersion with the nonlinear effectsof the fiber by using pulses of a specific shape.In the late 1990s through 2000, industry promoters, and research companies such as KMI and RHK predicted vast increases in demand for communications bandwidth due to increased use of the Internet, and commercialization of various bandwidth-intensive consumer services, such as video on demand.Internet protocoldata traffic was increasing exponentially, at a faster rate than integrated circuit complexity had increased under Moore’s Law.From the bust of the dot-com bubble through 2006, however, the main trend in the industry has been consolidation of firms and offshoring of manufacturing to reduce costs.Recently, companies such as Verizon and AT&T have taken advantage of fiber-optic communications to deliver a variety of high-throughput data and broadband services to consumers’ homes.