第一篇：局域網(wǎng)外文翻譯(一)

外 文 翻 譯

論文題目 ： 姓學班年專學名 ： 號 ： 級 ： 級 ： 業(yè) ： 院 ：

大型企業(yè)網(wǎng)絡(luò)的設(shè)計與規(guī)劃

賈龍飛 201120210230 1122102班 2011級 網(wǎng)絡(luò)工程 軟件學院 王志波（講師）二〇一五 年 四 月 指導教師 ： 完成時間 ：

目錄

1.COMPUTER NETWORKS............................................3 DATE COMMUNICATIONS..........................................3 2.ARCHITECTURE OF COMPUTER NETWORKS............................4 1.The OSI Reference Model....................................4 2.The TCP/IP Reference Model.................................4 3.WIDE AREA NETWORK............................................5 1.CIRCUIT SWITCHED NETWORKS..................................5 2．LEASED LINE NETWORKS......................................6 3.PACKET SWITCHING NETWORKS..................................6 4.LOCAL AREA NETWORK...........................................7 1.Topology...................................................7 2.Transmission media.........................................7 3.Medium access control methods.............................7 1.計算機網(wǎng)絡(luò)...................................................9 數(shù)據(jù)通信.....................................................9 2.計算機網(wǎng)絡(luò)的體系結(jié)構(gòu).........................................9 1.OSI參考模型..............................................10 2.TCP/IP參考模型...........................................10 3.廣域網(wǎng)......................................................10 1.電路交換網(wǎng)................................................11 2.專線網(wǎng)....................................................11 3.分組交換網(wǎng)................................................11 4.局域網(wǎng)......................................................12 1.拓撲結(jié)構(gòu)..................................................12 2.傳輸媒體..................................................12 3.媒體訪問控制方法..........................................12

1.COMPUTER NETWORKS DATE COMMUNICATIONS The end equipment which either generates the digital information for transmission or uses the received digital data can be computer ,printers ,keyboards, CRTs, and so on.This equipment generally manipulates digital information internally in word units—all the bits that make up a word in a particular piece of equipment are transferred in parallel.Digital data, when transmitted, are in serial form.Parallel transmission of an 8-bit word require eight pairs of transmission lines—not at all cost-effective.Data terminal(DTE)is a general phrase encompassing all of the circuitry necessary to perform parallel-to-serial and serial-to-parallel conversions for transmission and reception respectively and for data link management.The UART(Universal Asynchronous Receiver/Transmitter)

and

USART

(Universal Asynchronous/Asynchronous Receiver/Transmitter)are the devices that perform the parallel-to-serial and serial-to-parallel conversions.The primary DTE includes a line control unit(LCU or LinCo)which controls the flow of information in a multipoint data link system.A station controller(STACO)is the corresponding that belonged to the subscriber in a data link system.Between the DTEs, starting with the modems, was communications equipment owned and maintained by Telco property.Data communications equipment(DCE)accepts the serial data stream from the DTE and converts it to some form of analog signal suitable for transmission on voice-grade lined.At the receive end, the DCE performs the reverse function of converting the received analog signal to a serial digital data stream.The simplest form of DCE is a modem(modulator/demodulator)or data set.At the transmit end, the modem can be considered a form of digital-to-analog converter, while at the receive end, it can considered a form of analog-to-digital converter.The most common of modulation by modems are frequency shift keying(FSK), phase shift keying(PSK), and quadrature amplitude modulation(QAM).This is a typically data transmission mode using the analog telephone lines.If you transmit data by digital channel(sometimes it is called “Digital T-carrier”), a pulse Code Modulation(PCM)equipment must be used.A microwave transmission system can also be used for the data communication.Finally, you can use the satellite communication system for data transmission.If the cables and signal levels used to interconnect the DTE and DCE were left unregulated, the variations generated would probably be proportional to the number of manufacturers.Electronics industries Association(EIA),an organization of manufactures with establishing the DTE and modem.This is a 25-pincable whose pins have designated functions and specified signal levels.The RS-232C is anticipated to be replaced by an update standard.2.ARCHITECTURE OF COMPUTER NETWORKS Computer network is a complex consisting of two or more conned computing units, it is used for the purpose of data communication and resource resource sharing.Design of a network and its logical structure should comply with a set of design principles, including the organization of functions and the description of data formats and procedure.This is the network architecture and so called as a set of layers and protocols, because the architecture is a layer-based.In the next two sections we will discuss two important network architectures, the OSI reference model and the TCP/IP reference model.1.The OSI Reference Model The OSI model is shown in Fig.14-2(minus the physical medium).This model is based on a proposal developed by the International Standards Organizations(OSI)as the first step toward international standardization of the protocols used in the various layers.The model is called the ISO OSI(Open System Interconnection)Reference Model because it deals with connecting open systems--that is, systems that are open for communication with other systems, We will usually just call it the OSI model for short.The OSI model has seven has seven layers.Note that the OSI model itself is not a network architecture because it does not specify the exact services and protocols to be used in each layer.It just tells what each layer should do.However , However, ISO has also produced standards for all the layers, although these are not part of the reference model itself.Each one has been published as a separate international standard.2.The TCP/IP Reference Model

The TCP/IP reference model is an early transport protocol which was designed by the US Department of Defence(DOD)around in 1978.It is often claimed that it gave rise the OSI “connectionless” mode of operation.TCP/IP is still used

extensively and is called as a industrial standard of internet work in fact, TCP/IP has two parts: TCP and IP.TCP means it is on the transport layer and IP means it is on the network layer separately.1.There are two end-to-end protocols in the transport layer, one of which is TCP(Transmission Control Protocol), another is UDP(User Datagram Protocol).TCP is a connection-oriented protocol that allows a byte stream originating on one machine to be delivered without error on any other machine in the internet.UDP is an unreliable, connectionless protocol for application that do not want TCP’s sequencing of flows control flow control and wish to provide their own.2.The network layer defines an official packet format and protocol called IP(Internet protocol).The job of the network layer is to deliver IP packets where they are supposed to go.The TCP/IP Reference Model is shown in Fig.14.3.On top of the transport layer is the application layer, It contains all the higher-level protocols.The early ones included virtual terminal(TELNET), file transfer(FTP), electronic mail(SMTP)and domain name service(DNS).3.WIDE AREA NETWORK A wide area network, or WAN, spans a large geographical area, often a country or continent.It contains a collection of machines intended for running user(i.e., application)programs.We will follow traditional usage and call these machines hosts.By a communication subnet, or just subnet for short.The job of the subnet is to carry messages from host to host, just as the telephone system carries words from speaker to listener.By separating the pure communication aspects of the network(the subnet)from the application aspects(the hosts), the complete network design is greatly simplified.Relation between hosts and the subnet is shown in Fig.14-4.One of many methods that can be used to categorize wide area networks is with respect to the flow of information on a transmission facility.If we use this method to categorize wide area networks, we can group them into three basic types: circuit switched, leased line and packet switched.1.CIRCUIT SWITCHED NETWORKS The most popular type of network and the one almost all readers use on a daily basis is a circuit switched network.The public switched telephone network, however，is not limited to the telephone company, By purchasing appropriate switching equipment, any organization can construct their own internal circuit switched network and, if desired, provide one or more interfaces to the public switched network to allow voice and data transmission to flow between the public network and their private internal network

2．LEASED LINE NETWORKS This is a dedicated network connected by leased lines.Leased line is a communications line reserved for the exclusive use of a leasing customer without inter-exchange switching arrangements.Leased or private lines are dedicated to the user.This advantage is that the terminal or computer is a always physically connected to the line.Very short response times are met with service.3.PACKET SWITCHING NETWORKS A packet network is constructed through the use of equipment that assembles and disassembles packets, equipment that routes packet, and transmission facilities used to route packets from the originator to the destination device.Some types of data terminal equipment(DTE)can create their own packets, while other types of DTE require the conversion of their protocol into packets through the use of a packet assembler / disassemble(PAD).Packets are routed through the network by packet switches.Packet switches examine the destination of packets as they flow through the network and transfer the packets onto trunks interconnecting switches based upon the packet destination destination and network activity.Many older pubic networks follow a standard called X.25.It was developed during 1970s by CCITT to provide an interface between public packet-switched network and their customers.CCITT Recommendation X.25 controls the access from a packet mode DTE, such as a terminal device or computer system capable of forming packets, to the DCE at a packet mode.CCITT Recommendation X.28 controls the interface between non-packet mode devices that cannot interface between the PAD and the host computer.CCITT Recommendation X.3 specifies the parameter settings on the PAD and X.75 specifies the interface between packet network.4.LOCAL AREA NETWORK Local area data network , normally referred to simply as local area network or LANs, are used to interconnect distributed communities of computer-based DTEs located within a building or localized group of building.For example, a LAN may be used to interconnect workstations distributed around offices within a single building or a group of buildings such as a university campus.Alternatively, it may be complex.Since all the equipment is located within a single establishment, however, LANs are normally installed and maintained by the organization.Hence they are also referred to as private data networks.The main difference between a communication path established using a LAN and a connection made through a public data network is that a LAN normally offers much higher date transmission rates because of the relatively short physical separations involved.In the context of the ISO Reference Model for OSI, however, this difference manifests itself only at the lower network dependent layers.In many instances the higher protocol layers in the reference model are the same for both types of network.Before describing the structure and operation of the different types of LAN, it is perhaps helpful to first identify some of the selection issues that must be considered.It should be stressed that this is only a summary;there are also many possible links between the tips of the branches associated with the figure.1.Topology Most wide area networks, such as the PSTN, use a mesh(sometimes referred to as a network)topology.With LANs, however, the limited physical separation of the subscriber DTEs allows simpler topologies to be used.The four topologies in common use are star, bus ,ring and hub.The most widespread topology for LANs designed to function as data communication subnetworks for the interconnection of local computer-based equipment is the hub topology, which is a variation a variation of the bus and ring.Sometimes it is called hub/tree topology.2.Transmission media Twisted pair, coaxial cable and optical fiber are the three main type of transmission medium used for LANs.3.Medium access control methods

Two techniques have been adopted for use of the medium access control in the LANs.They are carrier-sense-multiple-access with collision detection(CSMA/CD), for bus network topologies, and control token, for use with either bus or ring networks.CSMA/CD is used to control multiple-access networks.Each on the network “l(fā)istens” before attempting to send a message, waiting for the “traffic” to clear.If two stations try to sent their messages at exactly the same time, a “collision” is detected, and both stations are required to “step back” and try later.Control token is another way of controlling access to a shared transmission medium that is by the use of a control(permission)token.This token is passed form one DTE to another according to a defined set of rules understood and adhered to by all DTEs connected to the medium.ADTE may only transmit a frame when it is in possession of the token and, after it has transmitted the frame, it passed the token on to allow another DTE to access the transmission medium.1．計算機網(wǎng)絡(luò)

數(shù)據(jù)通信

端設(shè)備可以是計算機、打印機、鍵盤、CRT等，它們可以產(chǎn)生要發(fā)送的數(shù)字信息，也可使用所接收的數(shù)字數(shù)據(jù)。這種設(shè)備通常在內(nèi)部以字為單位處理數(shù)字信息——在一個實際設(shè)備中構(gòu)成一個字的所有位是并行傳遞的。數(shù)字數(shù)據(jù)在發(fā)送一個8對傳輸線，這是不經(jīng)濟的。那些在發(fā)送、接收數(shù)據(jù)分別完成并-串和串-并轉(zhuǎn)換并進行數(shù)據(jù)鏈路管理的所有電路，一般稱為數(shù)據(jù)終端設(shè)備（DTE）。UART（通用異步接收/發(fā)送器）和USART（通用同步/異步接收/發(fā)送器）是實現(xiàn)并-串和串-并轉(zhuǎn)換的設(shè)備。主DTE包括控制多點數(shù)據(jù)鏈路系統(tǒng)中信息流的線路控制部件（LCU或LinCo）。從設(shè)備一方的相應(yīng)設(shè)備是工作站控制器（STACO）。如果DTE有與LCU相關(guān)的軟件，則稱為前端處理機（FEP）。同時，DTE也是數(shù)據(jù)鏈路系統(tǒng)中屬于用戶的最后一個設(shè)備。在兩個DTE之間，先是調(diào)制解調(diào)器，接著是屬于并有電話公司維護的通信設(shè)備。最近的調(diào)整結(jié)果是調(diào)制解調(diào)器已不屬于電話公司獨家管理的設(shè)備了。

數(shù)據(jù)通信設(shè)備（DCE）從DTE接收串行數(shù)據(jù)流，并將其轉(zhuǎn)化成適合在話音線路上發(fā)送的某種模擬信號形式。在接收端，DCE完成相反的功能，把接收到的模擬信號轉(zhuǎn)換成串行數(shù)字數(shù)據(jù)流。最簡單的DCE是調(diào)制解調(diào)器或數(shù)傳機。在發(fā)送端，調(diào)制解調(diào)器可以視為一種數(shù)/模轉(zhuǎn)換器，而在接收端則可視為一種模/數(shù)轉(zhuǎn)換器。調(diào)制解調(diào)器最常用的幾種調(diào)制方式是移頻鍵控（FSK）、移相鍵控（PSK）和正交調(diào)幅（QAM）。這是一種典型的使用模擬電話線路傳輸數(shù)據(jù)的方式。如果使用數(shù)字通信（有時稱為T-載波）傳輸數(shù)據(jù)，則必須使用脈碼調(diào)制（PCM）設(shè)備。也可以用微波傳輸系統(tǒng)進行的數(shù)據(jù)通信，當然還可以用衛(wèi)星通信系統(tǒng)去傳輸數(shù)據(jù)。

如果鏈接DTE和DCE的電纜和信號電平都是未調(diào)整的，則所產(chǎn)生的偏差就是可能與生產(chǎn)廠家的數(shù)量成正比。電子工業(yè)協(xié)會（EIA）（由關(guān)心建立行業(yè)標準的廠家組成的組織）同意將RS-232C作為DTE和調(diào)制解調(diào)器間的標準接口。它是一個25針電纜，每一針都規(guī)定了功能及信號電平，預計RS-232C將被修訂的標準所取代。

2．計算機網(wǎng)絡(luò)的體系結(jié)構(gòu)

計算機網(wǎng)絡(luò)是由兩個或多個計算機設(shè)備互連而成的一種復合系統(tǒng)，用于數(shù)據(jù)通信和資源共享。網(wǎng)絡(luò)設(shè)計及邏輯結(jié)構(gòu)應(yīng)該遵循一套設(shè)計原則，包括功能的組織與數(shù)據(jù)格式和過程的描述，這就是網(wǎng)絡(luò)的體系結(jié)構(gòu)。由于這種體系結(jié)構(gòu)是分層次 的，故又稱為一組層次和協(xié)議。

下面兩節(jié)將討論兩個重要的網(wǎng)絡(luò)體系結(jié)構(gòu)，即OSI參考模型和TCP/IP參考模型。

1．OSI參考模型

OSI模型如圖14-2所示（物理介質(zhì)未畫出）。這一模型是基于國際標準化組織（ISO）提出的一個建議，作為用于各層次的國際標準協(xié)議的第一步。該模型也稱為ISO開放系統(tǒng)互連參考模型，因為它涉及開放系統(tǒng)的互連，即于其他系統(tǒng)的通信是開放的，通常簡稱為OSI模型。

OSI模型有7層。應(yīng)該注意的是，OSI模型本身并不是一種網(wǎng)絡(luò)體系結(jié)構(gòu)，因為它不具體規(guī)定每一層所使用的確切的服務(wù)和協(xié)議。它只是說明每一層應(yīng)該做什么。然而，ISO還是對各層制定出了標準，盡管這些標準不是參考模型本身的一部分。每一層都作為一個單獨的國際標準來頒布。

2．TCP/IP參考模型

TCP/IP參考模型是美國國防部大約于1978年設(shè)計的一種早期的運輸協(xié)議。該協(xié)議通常被視為OSI無連接工作方式的源頭。TCP/IP仍在廣泛的使用，并且被稱為互聯(lián)網(wǎng)事實上的行業(yè)標準。

TCP/IP有兩部分：TCP和IP。TCP表明是處于運輸層，IP意為是網(wǎng)絡(luò)層。（1）運輸層有兩個端到端協(xié)議，其中之一是傳輸協(xié)議（TCP），另一個是用戶數(shù)據(jù)報協(xié)議（UDP）。TCP是一種面向連接的協(xié)議，它可以在互聯(lián)網(wǎng)上無差錯地將字節(jié)流從一臺機器發(fā)送出去。UDP是一種不可靠的無連接協(xié)議，用于不希望那種TCP流控制序列，而希望只提供自身功能的場合。

（2）網(wǎng)絡(luò)層定義了正式的分組格式及稱為互聯(lián)網(wǎng)協(xié)議的IP。該網(wǎng)絡(luò)層的任務(wù)是將IP分組發(fā)送到指定的地方。

圖14-3所示為TCP/IP參考模型。在運輸層上面是應(yīng)用層。應(yīng)用層包括所有高層協(xié)議。早期的協(xié)議包括虛擬終IELNET、文件傳送協(xié)議FTP、電子郵件（SMTP）和域名服務(wù)DNS。

3．廣域網(wǎng)

廣域網(wǎng)跨越地域很大，通常是一個國家或一個大陸。這種網(wǎng)絡(luò)中匯集了運行各種用戶程序（即應(yīng)用程序）的計算機。本文還是沿用傳統(tǒng)的稱呼把它們叫做主

機，在一些文獻里有時也稱其為端系統(tǒng)。這些主機是通過通信子網(wǎng)（有時簡稱子網(wǎng)）連接起來的。子網(wǎng)的任務(wù)是把報文從一個主機傳送到另一個主機，就像電話系統(tǒng)把話音從講話人傳到收聽者一樣。把網(wǎng)絡(luò)（子網(wǎng)）的純通信任務(wù)與主機的應(yīng)用任務(wù)分開以后，整個網(wǎng)絡(luò)的設(shè)計工作就得到很大的簡化。圖14-4展示了主機與通信子網(wǎng)之間的關(guān)系。

廣域網(wǎng)的分類方法很多，其中一種方法是按傳輸設(shè)備中的信息流分類。如果使用這種方法，可將廣域網(wǎng)分成3種基本類型：電路交換、專線和分組交換。

1．電路交換網(wǎng)

電路交換網(wǎng)是最常用的并且是幾乎所有用戶都要用的網(wǎng)絡(luò)類型。然而，公用電話交換網(wǎng)不限于電話公司。任何單位只要購買了合適的交換設(shè)備，就可以建立自己的內(nèi)部電路交換網(wǎng)，而且如果需要，還可配置一至多個與公用交換網(wǎng)互連的接口，在公用網(wǎng)和他們的專用內(nèi)部網(wǎng)之間話音和數(shù)據(jù)傳輸。

2．專線網(wǎng)

這是一種通過租用線連接的專用網(wǎng)。租用線是由租用客戶專用的一條通信線，不須進行交換機間的交換。租用或私人線路是用戶專用的。專線的優(yōu)點是終端或計算機一直連在租用線上，服務(wù)的響應(yīng)時間極短。

3．分組交換網(wǎng)

分組網(wǎng)絡(luò)是用分組裝拆設(shè)備、分組路由的設(shè)備，以及將分組從源傳到目的地的設(shè)備構(gòu)成的。某些類型的數(shù)據(jù)終端設(shè)備DTE可以生成他們自己的分組，而其他一些DTE則要使用分組裝拆器（PAD）把其協(xié)議轉(zhuǎn)化成分組。分組通過分組交換機在網(wǎng)上傳遞。當分組在網(wǎng)上傳輸時，分組交換機檢查分組的目的地址，并且根據(jù)該分組的目的地址和網(wǎng)絡(luò)的實際運行情況把分組傳向互連交換機的中繼結(jié)點。

早期網(wǎng)絡(luò)的許多公用網(wǎng)一般都遵循X。25標準，該標準是20世紀70年代由CCITT開發(fā)的，旨在為公用分組交換網(wǎng)與用戶之間提供一個接口。

CCITT X。25建議管理從一個分組型DTE，例如從一個具有分組功能的終端設(shè)備或計算機系統(tǒng)，去訪問一個分組結(jié)點DCE。CCITT X。28建議的管理沒有分組功能的非分組設(shè)備與PAD之間的接口。CCITT X。29建議定義的是PAD與主機之間的接口。CCITT X。3建議規(guī)定了PAD上的參數(shù)設(shè)定，X。75則規(guī)定了分組網(wǎng)之間的接口。

4．局域網(wǎng)

局域數(shù)據(jù)網(wǎng)一般簡稱為局域網(wǎng)，用于在一幢樓內(nèi)或局限在樓群范圍內(nèi)把分散的基于計算機數(shù)據(jù)終端設(shè)備互連在一起。例如，一個局域網(wǎng)可以把一幢樓里或像大學校園內(nèi)各個樓里的各個辦公室的工作站連在一起。另外，局域網(wǎng)也可以把分布在工廠或醫(yī)院建筑群中的計算機設(shè)備連在一起。由于所有這些設(shè)備都是一個單位的，因此局域網(wǎng)一般也由這些單位負責安裝和維護。于是這類局域網(wǎng)也叫做專用數(shù)據(jù)網(wǎng)。

用局域網(wǎng)方式建立的通信線路和通過公用數(shù)據(jù)網(wǎng)連接的線路兩者的主要區(qū)別在于：因為局域網(wǎng)連接的設(shè)備之間相對來說距離較近，因而數(shù)據(jù)傳輸速率高的多。但是在ISO的OSI參考模型中，這兩種網(wǎng)絡(luò)是沒有區(qū)別的。

在敘述幾種不同類型的局域網(wǎng)的結(jié)構(gòu)和工作之前先認識一下必須考慮的有關(guān)問題可能是很有幫助的。應(yīng)該強調(diào)的是，這僅僅是一個概括，因為各分支之間還可能有很多鏈路。

1．拓撲結(jié)構(gòu)

大多數(shù)廣域網(wǎng)，如公共電話交換網(wǎng)（PSTN）就使用網(wǎng)狀（有時稱為網(wǎng)絡(luò)）拓撲結(jié)構(gòu)。而局域網(wǎng)，由于用戶數(shù)據(jù)終端設(shè)備相距很近，可采用簡單的拓撲結(jié)構(gòu)。常用的有星形、總線、環(huán)形和集線器等4種拓撲結(jié)構(gòu)。

應(yīng)用最廣的、用于本地計算機設(shè)備互連以進行數(shù)據(jù)通信的局域網(wǎng)拓撲結(jié)構(gòu)是集線器拓撲結(jié)構(gòu)。這種拓撲結(jié)構(gòu)是總線和環(huán)形拓撲結(jié)構(gòu)的變種。有時也稱為集線器/樹形拓撲結(jié)構(gòu)。

2．傳輸媒體

雙絞線、同軸電纜和光纖是局域網(wǎng)采用的3種主要傳輸媒體。

3．媒體訪問控制方法

局域網(wǎng)中采用了兩種媒體訪問控制技術(shù)。他們是用于總線網(wǎng)絡(luò)拓撲結(jié)構(gòu)的帶沖突檢測的載波偵聽多路存取（CSMA/CD）和既可用于總線又可用于環(huán)形網(wǎng)絡(luò)的令牌控制技術(shù)。

CSMA/CD用來控制多路存取網(wǎng)絡(luò)。網(wǎng)絡(luò)上的每個站點在試圖發(fā)送信息前先“偵聽”，等待通路空閑。如果兩個站點在同一時刻要發(fā)送信息，將會檢測到?jīng)_突，這

兩個站點必須各自“后退”一步，以后再重試。

令牌控制是另一種用令牌去控制訪問共享傳輸媒體的方法。該令牌按所有連入媒體的DTE都知道并遵守的一套確定的規(guī)則從一個DTE傳向另一個DTE。當某一DTE掌握這一令牌時，它才能傳送一幀數(shù)據(jù)，而在傳送完該幀之后，要將令牌釋放，以便其他DTE訪問該傳輸媒體。

第二篇：外文翻譯

當今時代是一個自動化時代，交通燈控制等很多行業(yè)的設(shè)備都與計算機密切相關(guān)。因此，一個好的交通燈控制系統(tǒng)，將給道路擁擠，違章控制等方面給予技術(shù)革新。隨著大規(guī)模集成電路及計算機技術(shù)的迅速發(fā)展，以及人工智能在控制技術(shù)方面的廣泛運用，智能設(shè)備有了很大的發(fā)展，是現(xiàn)代科技發(fā)展的主流方向。本文介紹了一個智能交通的系統(tǒng)的設(shè)計。該智能交通燈控制系統(tǒng)可以實現(xiàn)的功能有：對某市區(qū)的四個主要交通路口進行控制：個路口有固定的工作周期，并且在道路擁擠時中控制中心能改變其周期：對路口違章的機動車能夠即時拍照，并提取車牌號。在世界范圍內(nèi)，一個以微電子技術(shù)，計算機和通信技術(shù)為先導的，一信息技術(shù)和信息產(chǎn)業(yè)為中心的信息革命方興未艾。而計算機技術(shù)怎樣 與實際應(yīng)用更有效的結(jié)合并有效的發(fā)揮其作用是科學界最熱門的話題，也是當今計算機應(yīng)用中空前活躍的領(lǐng)域。本文主要從單片機的應(yīng)用上來實現(xiàn)十字路口交通燈智能化的管理，用以控制過往車輛的正常運作。

研究交通的目的是為了優(yōu)化運輸，人流以及貨流。由于道路使用者的不斷增加，現(xiàn)有資源和基礎(chǔ)設(shè)施有限，智能交通控制將成為一個非常重要的課題。但是，智能交通控制的應(yīng)用還存在局限性。例如避免交通擁堵被認為是對環(huán)境和經(jīng)濟都有利的，但改善交通流也可能導致需求增加。交通仿真有幾個不同的模型。在研究中，我們著重于微觀模型，該模型能模仿單獨車輛的行為，從而模仿動態(tài)的車輛組。

由于低效率的交通控制，汽車在城市交通中都經(jīng)歷過長時間的行進。采用先進的傳感器和智能優(yōu)化算法來優(yōu)化交通燈控制系統(tǒng)，將會是非常有益的。優(yōu)化交通燈開關(guān)，增加道路容量和流量，可以防止交通堵塞，交通信號燈控制是一個復雜的優(yōu)化問題和幾種智能算法的融合，如模糊邏輯，進化算法，和聚類算法已經(jīng)在使用，試圖解決這一問題，本文提出一種基于多代理聚類算法控制交通信號燈。

在我們的方法中，聚類算法與道路使用者的價值函數(shù)是用來確定每個交通燈的最優(yōu)決策的，這項決定是基于所有道路使用者站在交通路口累積投票，通過估計每輛車的好處(或收益)來確定綠燈時間增益值與總時間是有差異的，它希望在它往返的時候等待，如果燈是紅色，或者燈是綠色。等待，直到車輛到達目的地，通過有聚類算法的基礎(chǔ)設(shè)施，最后經(jīng)過監(jiān)測車的監(jiān)測。

我們對自己的聚類算法模型和其它使用綠燈模擬器的系統(tǒng)做了比較。綠燈模擬器是一個交通模擬器，監(jiān)控交通流量統(tǒng)計，如平均等待時間，并測試不同的交通燈控制器。結(jié)果表明，在擁擠的交通條件下，聚類控制器性能優(yōu)于其它所有測試的非自適應(yīng)控制器，我們也測試理論上的平均等待時間，用以選擇車輛通過市區(qū)的道路，并表明，道路使用者采用合作學習的方法可避免交通瓶頸。

本文安排如下：第2部分敘述如何建立交通模型，預測交通情況和控制交通。第3部分是就相關(guān)問題得出結(jié)論。第4部分說明了現(xiàn)在正在進一步研究的事實，并介紹了我們的新思想。

The times is a automation times nowadays,traffic light waits for much the industey equipment to go hand in hand with the computer under the control of.Therefore,a good traffic light controls system,will give road aspect such as being crowded,controlling against rules to give a technical improvement.With the fact that the large-scale integrated circuit and the computer art promptness develop,as well as artificial intelligence broad in the field of control technique applies,intelligence equipment has had very big development,the main current being that modern science and technology develops direction.The main body of a book is designed having introduccd a intelligence traffic light systematically.The function being intelligence traffic light navar’s turn to be able to come true has：The crossing carries out supervisory control on four main traffic of some downtown area;Every crossing has the fixed duty period,charges centrefor being able to change it’s period and in depending on a road when being crowded;The motro vehicle breaking rules and regulations to the crossing is able to take a photo immediately,abstracts and the vehicle shop sign.Within world range ,one uses the microelectronics technology,the computer and the technology communicating by letter are a guide’s,centering on IT and IT industry information revolution is in the ascendant.But,how,computer art applies more effective union and there is an effect’s brought it’s effect into play with reality is the most popular topic of scientific community,is also that computer applications is hit by the unparalleled active field nowadays.The main body of a book is applied up mainly from slicing machine’s only realizing intellectualized administration of crossroads traffic light,use operation in controlling the vehicular traffic regularity.Transportation research has the goal to optimize transportation flow of people and goods.As the number of road users constantly increases, and resources provided by current infras-tructures are limited, intelligent control of traffic will become a very important issue in thefuture.However, some limitations to the usage of intelligent tra?c control exist.Avoidingtraffic jams for example is thought to be beneficial to both environment and economy, butimproved traffic-flow may also lead to an increase in demand [Levinson, 2003].There are several models for traffic simulation.In our research we focus on microscopicmodels that model the behavior of individual vehicles, and thereby can simulate dynam-ics of groups of vehicles.Research has shown that such models yield realistic behavior[Nagel and Schreckenberg, 1992, Wahle and Schreckenberg, 2001].Cars in urban traffic can experience long travel times due to inefficient traffic light con-trol.Optimal control of traffic lights using sophisticated sensors and intelligent optimizationalgorithms might therefore bevery beneficial.Optimization of traffic light switching increasesroad capacity and traffic flow, and can prevent tra?c congestions.Traffic light control is acomplex optimization problem and several intelligent algorithms, such as fuzzy logic, evo-lutionary algorithms, and reinforcement learning(RL)have already been used in attemptsto solve it.In this paper we describe a model-based, multi-agent reinforcement learningalgorithm for controlling traffic lights.In our approach, reinforcement learning [Sutton and Barto, 1998, Kaelbling et al., 1996]with road-user-based value functions [Wiering, 2000] is used to determine optimal decisionsfor each traffic light.The decision is based on a cumulative vote of all road users standingfor a traffic junction, where each car votes using its estimated advantage(or gain)of settingits light to green.The gain-value is the difference between the total time it expects to waitduring the rest of its trip if the light for which it is currently standing is red, and if it is green.The waiting time until cars arrive at their destination is estimated by monitoring cars flowingthrough the infrastructure and using reinforcement learning(RL)algorithms.We compare the performance of our model-based RL method to that of other controllersusing the Green Light District simulator(GLD).GLD is a traffic simulator that allows usto design arbitrary infrastructures and traffic patterns, monitor traffic flow statistics such asaverage waiting times, and test different traffic light controllers.The experimental resultsshow that in crowded traffic, the RL controllers outperform all other tested non-adaptivecontrollers.We also test the use of the learned average waiting times for choosing routes of cars through the city(co-learning), and show that by using co-learning road users can avoidbottlenecks.

第三篇：外文翻譯

設(shè)計一個位于十字路口的智能交通燈控制系統(tǒng)

摘要：本文模型使用模糊本體的交通燈控制域，并把它應(yīng)用到控制孤立十字路口。本文最重要的目的之一是提出一個獨立的可重復使用的交通燈控制模塊。通過這種方式，增加軟件的獨立性和為其他的軟件開發(fā)活動如測試和維護，提供了便利。專家對本體論進行手動的開發(fā)和評估。此外，交通數(shù)據(jù)提取和分類路口使用的人工神經(jīng)網(wǎng)絡(luò)的圖像處理算法。根據(jù)預定義的XML架構(gòu)，這種信息轉(zhuǎn)化為XML實例映射到適合使用模糊推理引擎的模糊規(guī)則的模糊本體。把本系統(tǒng)的性能與其他類似的系統(tǒng)性能進行比較。比較結(jié)果顯示：在所有的交通條件下，在每個周期中，對每輛車它有低得多的平均延遲時間與其他的控制系統(tǒng)相比。

關(guān)鍵詞:模糊本體,智能代理,智能交通系統(tǒng)(ITS),交通信號燈控制(TLC),孤立的十字路口,圖像處理,人工神經(jīng)網(wǎng)絡(luò)

1.引言

作為城市交通增加的結(jié)果,道路網(wǎng)絡(luò)的能力有限和發(fā)展交通工具和方法的技術(shù)方面，許多實體，關(guān)系，情況和規(guī)則已經(jīng)進入交通燈控制域和轉(zhuǎn)化成為一個知識領(lǐng)域。這個領(lǐng)域的建模知識幫助交通代理和應(yīng)用有效地管理關(guān)于實時條件下的交通。全面知識建模領(lǐng)域的一個最合適的方法是使用本體概念。“本體論是一個正式的、明確的一個共享的概念化的規(guī)范。以前的模型是基本的本體建設(shè)的基礎(chǔ)，為下列建立一個共享的語義豐富的知識域。除了本體作為概念化的形式主義的重要性，它有可能超過所代表的數(shù)據(jù)。這種能力將提高有關(guān)性能的決定和其他非智能系統(tǒng)的功能特點。在近年來，本體論上的研究正成為一個新的熱點話題在不同的活動，如人工智能，知識管理，語義網(wǎng)絡(luò)，電子商務(wù)和幾個其他應(yīng)用領(lǐng)域。這些領(lǐng)域之一是智能交通系統(tǒng)。一些努力已制成這個通過展示和使用本體檢測交通領(lǐng)域擁塞，管理非城市道路氣象事件，駕駛阿德?！骼锵到y(tǒng)，共享和整合一個智能交通系統(tǒng)。本文的目的是介紹一個紅綠燈有效控制孤立交叉口這方面的知識重用的控制本體。這種新的辦法適用于智能代理使用知識決策模糊。該系統(tǒng)采用的圖像來自安裝了監(jiān)控攝像機拍攝的路口。這些圖像處理利用圖像處理算法和神經(jīng)網(wǎng)絡(luò)的方法，然后發(fā)送到一個智能代理。第2節(jié)中，我們將簡要地解釋了在這項工作中運用的技術(shù)包括seman-TIC網(wǎng)絡(luò)技術(shù)，智能代理技術(shù)和交通的回地面光控制方法。在第3節(jié)，新的系統(tǒng)架構(gòu)是基于分層語義網(wǎng)絡(luò)架構(gòu)。第4節(jié)介紹交通燈控制的模糊本體的建設(shè)。第五節(jié)從路口提取的圖像信息解釋。在第6節(jié)，智能系統(tǒng)的運作被完整描述，最后在第7節(jié)對所提出的方法進行評估，對結(jié)論進行闡述。

2.背景

本節(jié)說明在這項工作中的應(yīng)用技術(shù)包括語義網(wǎng)絡(luò)技術(shù)，特別本體和模糊本體。此外，國家的交通燈控制的藝術(shù)方法是簡要介紹。2.1.語義網(wǎng)絡(luò)技術(shù)

語義網(wǎng)絡(luò)被定義為當前Wed的延伸，這些網(wǎng)站的信息都給出明確的含義;使電腦與人更好的合作。有幾層語義Web的建議源自伯納斯滯后階段。在此類別中的所有規(guī)則如表1所示。圖.4顯示輸出模式的示意圖。本次評選有助于智能系統(tǒng)，以確定下一步的階段測序。

另一種模糊的規(guī)則類別涉及估計優(yōu)化周期時間。這些規(guī)則的模糊變量是天氣條件，時間，每天平均車輛擁堵情況。出于這個原因，60個模糊規(guī)則被定義了。從氣象研究所取得氣象條件。日期和時間也是在交通專家的知識的基礎(chǔ)上以模糊變量形式預先定義的。圖5顯示日期，時間和周期時間的隸屬函數(shù)。當天的參數(shù)是在日歷基礎(chǔ)上基于假期和正常的一天與周期時間量的關(guān)系預定義的。例如，假期期間的周期時間是較平日少。因此，平日的隸屬度比假期多。

例如一個階段選型的模糊規(guī)則如下所述：“如果一個路口的類型是四的方式，平均車輛擁堵低，平均行人擁堵是中等，然后相類型是簡單的兩階段”。此外，為周期時間估計的模糊規(guī)則表示如下：“如果天氣條件是晴天，時間是早晨，天是正常的，平均車輛擁堵是低，則周期時間短”。在此類別中的所有規(guī)則都列在附錄A。

在此步驟結(jié)束時，應(yīng)該對交通燈邏輯控制的項目的有效性進行評估。此功能是使用專家的意見。評價過程的主要目的是顯示發(fā)展的本體和其相關(guān)的軟件環(huán)境的用處。雖然所有的信息，尤其是交通燈控制規(guī)則已提取國際標準和科學交通文學，專家的知識優(yōu)勢是他們最后的正確性驗證標準。所有模糊規(guī)則，包括優(yōu)化周期時間和相位類型的規(guī)則，在這個過程中，準備以調(diào)查問卷形式和展現(xiàn)給一些專家包括從德黑蘭警察局交通上校和兩名來自德黑蘭的交通組織工程師。由于德爾菲專家的意見，約有84％的淘汰型規(guī)則和優(yōu)化周期時間的87％被接受。此外，所有交通邏輯控制的元素包括概念，關(guān)系，屬性和公理都被這些專家進行了評估和驗證。我們評估邏輯交通控制是基于理論知識的。在這個過程中進行了兩項活動，包括檢查的要求和能力的問題，并在目標應(yīng)用環(huán)境測試本體。由于邏輯交通控制已建成的基礎(chǔ)上，如指定要求優(yōu)化循環(huán)時間，逐步淘汰型，交通的移動和優(yōu)化綠燈時間，每個階段的序列中，第一項活動是最好的結(jié)果。邏輯交通控制滿足所有的交通燈控制的需求，并能回答的能力問題?？冃гu估機制，可以支持這種說法。在部分實驗結(jié)果我們驗證了這一過程。

第四篇：外文翻譯

中原工學院畢業(yè)設(shè)計（論文）譯文

超聲測距系統(tǒng)設(shè)計

原文出處：傳感器文摘 布拉福德：1993年第13頁

摘要：超聲測距系統(tǒng)技校在工業(yè)場車輛導航水聲工程等領(lǐng)域都具有了廣泛的應(yīng)用價值，目前已應(yīng)用于物理測量，機器人自動導航以及空氣中與水下的目標探測、識別定位等場合，因此，深入研究超聲的探測理論和方法具有重要的實踐意義，為了進一步提高測量的精確度，滿足工程人員對測量精度測距量程和測距儀使用的要求，本文研制了一套基于單片機的使拱式超聲測距系統(tǒng)。關(guān)鍵詞：超聲波 測距儀 單片機

1、前言

隨著科技的發(fā)展，人們生活水平的提高，城市發(fā)展建設(shè)加快，城市給排水系統(tǒng)也有較大發(fā)展，其狀況不斷改善，但是，由于歷史原因合成時間性的許多不可預見因素，城市給排水系統(tǒng)，特別是排水系統(tǒng)往往落后于城市建設(shè)，因此，經(jīng)常出現(xiàn)開挖已經(jīng)建設(shè)好的建筑設(shè)施來改造排水系統(tǒng)的現(xiàn)象。城市污水給人們帶來的困擾，因此箱的排污疏通對大城市給排水系統(tǒng)污水理，人們生活舒適顯得非常重要。而設(shè)計研制箱涵排水疏通移動機器人的自動控制系統(tǒng)，保證機器人在箱涵中自由排污疏通，是箱涵排水系統(tǒng)疏通機器人的設(shè)計研制的核心部分，控制系統(tǒng)核心部分就是超聲波測儀的研制。因此，設(shè)計好的超聲波測距儀就顯得非常重要了。

1.1課題背景

隨著經(jīng)濟的發(fā)展與汽車科學技術(shù)的進步，公路交通呈現(xiàn)出行駛高速化、車流密集化和駕駛員非職業(yè)化的趨勢。同時，隨著汽車工業(yè)的飛速發(fā)展，汽車的產(chǎn)量和保有量都在急劇增加。但公路發(fā)展、交通管理卻相對落后，導致了交通事故與日劇增，城市里尤其突出。智能交通系統(tǒng)ITS是目前世界上交通運輸科學技術(shù)的前沿技術(shù)，它在充分發(fā)揮現(xiàn)有基礎(chǔ)設(shè)施的潛力，提高運輸效率，保障交通安全，緩解交通賭塞，改善城市環(huán)境等方面的卓越效能，已得到各國政府的廣泛關(guān)注。中國政府也高度重視智能交通系統(tǒng)的研究開發(fā)與推廣應(yīng)用。汽車防撞系統(tǒng)作為ITS 發(fā)展的一個基礎(chǔ)，它的成功與否對整個系統(tǒng)有著很大的作用。從傳統(tǒng)上說，汽車的安全可以分為兩個主要研究方向:一是主動式安全技術(shù)，即防止事故的發(fā)生，該種方式是目前汽車安全研究的最終目的;二是被動式安全技術(shù)，即事故發(fā)生后的乘員保護。目前汽車安全領(lǐng)域被動安全研究較多，主要從安全氣囊、ABS(防抱死系統(tǒng))和懸架等方面著手，以保證駕乘人員的安全。從經(jīng)濟性和安全性兩方面來說，中原工學院畢業(yè)設(shè)計（論文）譯文

這些被動安全措施是在事故發(fā)生時刻對車輛和人員進行保護，有很大的局限性，因而車輛的主動安全研究尤為重要，引出了本文研究的基于單片機的超聲波測距系統(tǒng)。這個系統(tǒng)是一種可向司機預先發(fā)出視聽語音信號的探測裝置。它安裝在汽車上，能探測企圖接近車身的行人、車輛或周圍障礙物;能向司機及乘員提前發(fā)出即將發(fā)生撞車危險的信號，促使司機采取應(yīng)急措施來應(yīng)付特殊險情，避免損失。

1.2 課題設(shè)計的意義

隨著現(xiàn)代社會工業(yè)化程的發(fā)展，汽車這一交通工具正為越來越多的人所用，但是隨之而來的問題也顯而易見，那就是隨著車輛的增多，交通事故的頻繁發(fā)生，由此導致的人員傷亡和財產(chǎn)損失數(shù)目驚人。對于公路交通事故的分析表明，80%以上的車禍事由于駕駛員反應(yīng)不及所引起的，超過65%的車輛相撞屬于追尾相撞，其余則屬于側(cè)面相撞。奔馳汽車公司對各類交通事故的研究表明：若駕駛員能夠提早1S 意識到有事故危險并采取相應(yīng)的正確措施，則絕大多數(shù)的交通事故都可以避免。因此，大力研究開發(fā)如汽車防撞裝置等主動式汽車輔助安全裝置，減少駕駛員的負擔和判斷錯誤，對于提高交通安全將起到重要的作用。顯然，此類產(chǎn)品的研究開發(fā)具有極大的實現(xiàn)意義和廣闊的應(yīng)用前景。

1.3超聲波測距在汽車上應(yīng)用的介紹

超聲波倒車測距儀(俗稱電子眼)是汽車倒車防撞安全輔助裝置，能以聲音或者更為直觀的數(shù)字形式動態(tài)顯示周圍障礙物的情況。其較早的產(chǎn)品是用蜂鳴器報警，蜂鳴聲越急，表示車輛離障礙物越近。后繼的產(chǎn)品可以顯示車后障礙物離車體的距離。其大多數(shù)產(chǎn)品探測范圍在0.4～1.5m，有的產(chǎn)品能達到0.35～2.5m，并有距離顯示、聲響報警、區(qū)域警示和方位指示，有些產(chǎn)品還具備開機自檢功能。目前市場上還出現(xiàn)了具有語音報警功能的產(chǎn)品。這些產(chǎn)品存在的主要問題是測量盲區(qū)大，報警滯后，未考慮汽車制動時的慣性因素，使駕駛者制動滯后，抗干擾能力不強，誤報也較多。汽車防撞雷達之所以能實現(xiàn)防撞報警功能，主要有超聲波這把無形尺子, 它測量最近障礙物的距離, 并告訴給車主。其實超聲測距原理簡單: 它發(fā)射超聲波并接收反射回波, 通過單片機計數(shù)器獲得兩者時間差t, 利用公式S=Ct/2計算距離, 其中S為汽車與障礙物之間的距離, C為聲波在介質(zhì)中的傳播速度。

本文介紹的超聲測距系統(tǒng)共有2只超聲波換能器(俗稱探頭),分別布置在汽車的后左、后右2個位置上。能檢測前進和倒車方向障礙物距離, 通過后視鏡內(nèi)置的

中原工學院畢業(yè)設(shè)計（論文）譯文

顯示單元顯示距離和方位, 發(fā)出一定的聲響, 起到提示和警戒的作用。系統(tǒng)采用一片STC89C52單片機對兩路超聲波信號進行循環(huán)采集。超聲波是指頻率高于20HHZ的機械波。為了以超聲波作為檢測手段，必須產(chǎn)生超生波和接收超聲波。完成這種功能的裝置就是超聲波傳感器，習慣上稱為超聲波換能器或超聲波探頭。超聲波傳感器有發(fā)送器和接收器，但一個超聲波傳感器也可具有發(fā)送和接收聲波的雙重作用。超聲波傳感器是利用壓電效應(yīng)的原理將電能和超聲波相互轉(zhuǎn)化，即在發(fā)射超聲波的時候，將電能轉(zhuǎn)換，發(fā)射超聲波；而在收到回波的時候，則將超聲振動轉(zhuǎn)換成電信號。超聲波測距的原理一般采用渡越時間法。首先測出超聲波從發(fā)射到遇到障礙物返回所經(jīng)歷的時間，再乘以超聲波的速度就得到二倍的聲源與障礙物之間的距離。測量距離的方法有很多種，短距離的可以用尺，遠距離的有激光測距等，超聲波測距適用于高精度的中長距離測量。因為超聲波在標準空氣中的傳播速度為331.45米/秒，由單片機負責計時，單片機使用12.0M晶振，所以此系統(tǒng)的測量精度理論上可以達到毫米級。由于超聲波指向性強，能量消耗緩慢，在介質(zhì)中傳播距離遠，因而超聲波可以用于距離的測量。利用超聲波檢測距離，設(shè)計比較方便，計算處理也較簡單，并且在測量精度方面也能達到要求。超聲波發(fā)生器可以分為兩類：一類是用電氣方式產(chǎn)生超聲波，一類是用機械方式產(chǎn)生超聲波。本設(shè)計屬于近距離測量，可以采用常用的壓電式超聲波換能器來實現(xiàn)觸發(fā)單元。

利用超聲波測距的工作，就可以根據(jù)測量發(fā)射波與反射波之間的時間間隔，從而達到測量距離的作用。其主要有三種測距方法：

（1）相位檢測法，相位檢測法雖然精度高，但檢測范圍有限；

（2）聲波幅值檢測法，聲波幅值檢測法易受反射波的影響；

（3）渡越時間檢測法，渡越時間檢測法的工作方式簡單，直觀，在硬件控制和軟件設(shè)計上都非常容易實現(xiàn)。其原理為：檢測從發(fā)射傳感器發(fā)射超聲波，經(jīng)氣體介質(zhì)傳播到接收傳感器的時間，這個時間就是渡越時間。本設(shè)計的超聲波測距就是使用了渡越時間檢測法。在移動車輛中應(yīng)用的超聲波傳感器，是利用超聲波在空氣中的定向傳播和固體反射特性（縱波），通過接收自身發(fā)射的超聲波反射信號，根據(jù)超聲波發(fā)出及回波接收的時間差和傳播速度，計算傳播距離，從而得到障礙物到車輛的距離。

中原工學院畢業(yè)設(shè)計（論文）譯文 超聲波測距原理

2.1 壓電式超聲波發(fā)生器原理

壓電式超聲波發(fā)生器實際上是利用壓電晶體的諧振來工作的。超聲波發(fā)生器內(nèi)部結(jié)構(gòu)，它有兩個壓電晶片和一個共振板。當它的兩極外加脈沖信號，其頻率等于壓電晶片的固有振蕩頻率時，壓電晶片將會發(fā)生共振，并帶動共振板振動，便產(chǎn)生超聲波。反之，如果兩極板間未加電壓，當共振板接收到超聲波時，將壓迫壓電晶片做振動，將機械能轉(zhuǎn)換為電信號，這是它就成為超聲波接收器了。

測量脈沖到達時間的傳統(tǒng)方法是以擁有固定參數(shù)的接收信號開端為基礎(chǔ)的。這個信號恰恰選于噪音水平之上，然而脈沖到達時間被定義為脈沖信號剛好超過界限的第一時刻。一個物體的脈沖強度很大程度上取決于這個物體的自然屬性尺寸還有它與傳感器的距離。進一步說，從脈沖起始點到剛好超過界限之間的時間段隨著脈沖的強度而改變。結(jié)果，一種錯誤便出現(xiàn)了——兩個擁有不同強度的脈沖在不同時間超過界限卻在同一時刻到達。強度較強的脈沖會比強度較弱的脈沖超過界限的時間早點，因此我們會認為強度較強的脈沖屬于較近的物體。

2.2 超聲波測距原理

超聲波發(fā)射器向某一方向發(fā)射超聲波，在發(fā)射時刻的同時開始計時，超聲波在空氣中傳播，途中碰到障礙物就立即返回來，超聲波接收器收到反射波就立即停止計時。超聲波在空氣中的傳播速度為340m/s，根據(jù)計時器記錄的時間t，就可以計算出發(fā)射點距離障礙物的距離(s)，即：s=340t/2

中原工學院畢業(yè)設(shè)計（論文）譯文

3、超聲波測距系統(tǒng)的電路設(shè)計

系統(tǒng)的特點是利用單片機控制超聲波的發(fā)射和超聲波自發(fā)射至接受往返時間的計時，單片機選用C51，經(jīng)濟易用，且片內(nèi)有4K的ROM，便于編程。電路的原理如圖1所示。

圖1 電路原理圖

中原工學院畢業(yè)設(shè)計（論文）譯文

3.1 40kHz脈沖的產(chǎn)生與超聲波發(fā)射

測距系統(tǒng)中的超聲波傳感器采用UCM40的壓電陶瓷，它的工作電壓是40kHz的脈沖信號，這由單片機執(zhí)行下面的程序來產(chǎn)生。puzel：mov 14h，#12h

here： cp1.0；

nop；

nop；

nop；

djnz 14h，here；

Ret

前方測距電路的輸出端接單片機P1.0端口，單片機執(zhí)行上面的程序后，在P1.0端口輸出一個40khz的脈沖信號，經(jīng)過三極管T放大，驅(qū)動超聲波發(fā)射頭UCM40T，發(fā)出40khz的脈沖超聲波，且持續(xù)發(fā)射200ms。右側(cè)合作側(cè)測距電路的輸入端分別接P1.1和P1.2端口，工作原理和前方測距電路相同。

超聲波發(fā)射持續(xù)200ms 輸出40kHz方波

3.2 超聲波的接收與處理

接收頭采用與發(fā)射頭配對的UCM40R，將超聲波調(diào)制脈沖變?yōu)殡妷盒盘?，?jīng)運算放大器ic1a和ic1b兩級放大后加至IC2,。IC2是帶有鎖定環(huán)的音頻譯碼集成塊LM567，內(nèi)部壓控振蕩器的中心頻率f0=1/1.1R8C3，電容C4決定其帶寬。調(diào)節(jié)R8在發(fā)射的載頻上，則LM567輸入信號大于25mv，輸出端8腳由5由高電平躍變?yōu)榈碗娖剑鳛橹袛嗾埱笮盘?，送至單片機處理。

前方測距電路的輸出端接至單片機INT0端口，中斷優(yōu)先級最高，左、右測距電路的輸出通過與門IC3A的輸出接單片機的INT1端口，同時單片機P1.3和P1.4接到IC3A的輸入端，中斷源的識別由程序查詢來處理，中斷優(yōu)先級為先右后左。部分源程序如下： receive1：push psw

push acc

clr ex1；關(guān)中斷源1

jnb p1.1，right;P1.1引腳為0，轉(zhuǎn)至右側(cè)距電路中斷服務(wù)程序

jnb p1.2,left;P1.2 引腳為0，轉(zhuǎn)至左測距中斷電路服務(wù)程序 returne：SETB EX1；

開外部中斷1

pop acc

中原工學院畢業(yè)設(shè)計（論文）譯文

pop psw

reti right：

...；

右測距電路中斷服務(wù)程序入口

ajmp return

left：

...；

左測距電路中斷服務(wù)程序入口

ajmp return

3.3 計算超聲波傳播時間

在啟動發(fā)射電路的同時啟動單片機內(nèi)部的定時器T0，利用定時器的計數(shù)功能，記錄超聲波發(fā)射的時間和受到反射波的時間。當收到超聲波反射波時，接受電路輸出端產(chǎn)生一個負跳變，在INT0或INT1端產(chǎn)生一個中斷請求信號，單片機響應(yīng)外部中斷請求，執(zhí)行外部中斷服務(wù)子程序，讀取時間差，計算距離。其部分源程序如下：

RECEIVEO: PUSH PSW

PUSH ACC CLR EX0;

關(guān)外部中斷0 讀取時間值

MOV R7,TH0;MOV R6,TL0 CLR C MOV A,R6 SUBB A,#0BBH;MOV 31H,A;MOV A,R7 SUBB A,#3CH MOV 30H,A SETB EX0;POP ACC

POP PSW

RETI 對于一個平坦的目標，測量距離包括兩個階段：粗糙的測量和精細的測量。第一步：脈沖的傳送產(chǎn)生一種簡單的超聲波

第二步：根據(jù)公式改變回波放大器的獲得量直到回撥被檢測到。第三步：檢測兩種回波的振幅與過零時間。

計算時間值 存儲結(jié)果

開外部中斷0

中原工學院畢業(yè)設(shè)計（論文）譯文

第四步：設(shè)置回波放大器的所得規(guī)格輸出，假定是3v。通過脈沖的周期設(shè)置下一個脈沖。根據(jù)第二部的數(shù)據(jù)設(shè)定時間窗。

第五步：發(fā)射兩竄脈沖產(chǎn)生干擾波。測量過零時間與回波振幅。如果逆向發(fā)生在回波中，決定要不通過在低氣壓插入振幅。

第六步：通過公式計算距離y。

中原工學院畢業(yè)設(shè)計（論文）譯文

4、超聲波測距系統(tǒng)的軟件設(shè)計

軟件分為倆部分，主程序和中斷服務(wù)程序。主程序完成初始化工作、各路超聲波發(fā)射和接收順序的控制。定時中斷服務(wù)子程序完成三方向超聲波的輪流發(fā)射，外部中斷服務(wù)子程序主要完成時間值的讀取、距離計算、結(jié)果的輸出等工作。

中原工學院畢業(yè)設(shè)計（論文）譯文

5、結(jié)論

對所要求測量范圍30cm-200cm內(nèi)的平面物體做了多次測量發(fā)現(xiàn)，其最大誤差為1.5cm，且重復性好。可見基于單片機設(shè)計的超聲波測距系統(tǒng)具有硬件結(jié)構(gòu)簡單、工作可靠、測量誤差小等特點。因此，它不僅可用于移動機器人，還可以用在其他檢測系統(tǒng)中。

思考：至于為什么不用接收管做放大電路，因為放大倍數(shù)搞不好，集成放大電路，還帶自動電平增益控制，放大倍數(shù)為76db，中心頻率是38k到40k，剛好是超聲波傳感器的諧振頻率。

中原工學院畢業(yè)設(shè)計（論文）譯文

參考文獻

1.Fox，J.D.，Khuri-Yakub，B.T.and Kino，G.S.，“High Frequency Acoustic Wave Measurement in Air”，in Proceedings of IEEE 1983 Ultrasonic Symposium，October 31-2 November，1983，Atlanta，GA，pp.581-4.2.Martin Abreu，J.M.，Ceres,R.And Freire,T.,“Ultrasonic Ranging: Envelope Analysis Gives Improved Accuracy”,Sensor Review, Vol.12 No.1,1992,pp.17-21.3.Parrilla， M., Anaya,J.J and Fritsch C.,‖Digital Signal Processing Techniques for High Accuracy Ultrasonic Range Measurement:,IEEE Transactions: Instrumentation and Measurement.Vol.40 No.4, August 1991,pp.750-63.4.Canali, C., Cicco, G.D., Mortem, B., Prudenziati, M., and Taron, A., ―A Temperature Compensated Ultrasonic Sensor Operating in Air for Distance and Proxinmity Measurement‖, IEEE Trasaction on Industry Electronics, Vol, IE-29 No.4,1982, pp.336-41.5.Martin, J.M., Ceres, R., Calderon, L and Freire, T., ‖Ultrasonic Ranging Gets Themal Correction‖, Sensor Review, Vol, 9 No.3, 1989,pp.153-5.中原工學院畢業(yè)設(shè)計（論文）譯文

Ultrasonic ranging system design Publication title: Sensor Review.Bradford:1993.Vol.13 ABSTRACT: Ultrasonic ranging technology has wide using worth in many field, such as the industrial locale, vehicle navigation and sonar engineering.Now it has been used in level measurement, self-guided autonomous vehicles, fieldwork robots automotive navigation, air and underwater target detection, identification ,location and so on.So there is an important practicing meaning to learn the ranging theory and ways deeply.To improve the precision of the ultrasonic ranging system in hand, satisfy the request of the engineering personal for the precision,the bound and the usage, a portable ultrasonic ranging system based on the single chip processor was developed.Keywords: Ultrasound r, Ranging System, Single Chip Processor

1.Introductive With the development of science and technology, the improvement of people’s standard of living, speeding up the development and construction of the city.Urban drainage system have greatly developed their situation is constantly improving.However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system.In particular drainage system often lags behind urban construction.Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon.It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system.Confort is very important to people’s lives.Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core.Control System is the core component of the development of ultrasonic range finder.Therefore, it is very important to design a good ultrasonic range finder.1.1 subject background

With the development of economy and car scientific and technological progress, highway traffic presents driving fast pace, traffic dense is changed and the driver not professional trend.At the same time, along with the rapid development of auto industry, automobile yield and quantities are increased dramatically.But road development，中原工學院畢業(yè)設(shè)計（論文）譯文

transportation management is relatively backward, leading to a large number of traffic accidents in some cities, especially prominent.Intelligent transportation system in the world, ITS transportation science and technology of advanced technology, ITS exerting existing infrastructure of potential, enhance the transport efficiency, safeguard traffic safety and ease traffic wager plug, improving urban environment aspects of outstanding performance, has received the governments of widespread concern.The Chinese government is also highly intelligent transportation system of the development and popularization applications.The automotive anti-collision system as ITS development of a base, ITS success to the whole system has a very significant role.Traditionally, auto safety said can be divided into two main research direction: first,it is active safety technology, including the prevention of accidents, the way is now automotive safety research ultimate purpose;second, it is passive safety technique, namely the occupant protection after the accident.Now automotive safety field passive safety more research, mainly from the airbag, ABS(antilock brakes)and suspension from the aspects such as to ensure safety of personnel rides.From the economic and safety two ways, these passive safety measures is the accident of vehicle and personnel moments protection, with great limitations, thus vehicle active safety research is particularly important, leads to a of this study is based on single chip ultrasonic ranging system.This system is a kind of can advance to the driver issued audio-visual speech signal detection devices.It is installed in cars that can detect trying to approach the body of a car pedestrians and vehicles or around obstacles, Can send to the driver and crew imminent danger ahead of the signal, prompting a crash drivers take emergency measures to cope with special danger, avoid the loss.1.2 question design significance

Along with the development of modern society industrialization process, car this traffic tools are used for more and more people, but any problem has obvious that along with the increase in vehicles, traffic accident, which led to the frequent occurrence of casualties and property losses number astonishing.For highway traffic accident analysis showed that more than 80% of the accident due to the driver reaction inferior things, caused more than 65% of vehicle collision, the rest belongs to tracing cauda collided belongs to the side collision.Mercedes-benz Automobile Company for all kinds of traffic accident research shows that: if the driver can early 1S are aware

中原工學院畢業(yè)設(shè)計（論文）譯文

that a accident risk and take the appropriate corrective measures, the overwhelming majority of traffic accidents can be avoided.Therefore, vigorously research and development as the automotive anti-collision device etc active car auxiliary safe device, reduce the burden and misjudgments drivers to improve the traffic safety will play an important role.Obviously, this kind of product research and development has great realize meaning and broad application prospects.1.3 Ultrasonic ranging in automotive applications introduced

Ultrasonic back-draft rangefinder(known as electron optics)automotive anti-collision reversing device, can safe adjunct to sound or more intuitive digital form the dynamic display of around obstacles.Its earlier products is to use buzzer alarm, hum more anxious, and says vehicles from obstructions closer.Subsequent product can display the car from the body after the obstacles distance.Most of its products detection range in 0.4 ~ 1.5 m, some product can achieve 0.35 ~ 2.5 m, and have distance display, sound alarm, area-warning and azimuth instructions, some products also has the boot self-checking function.Still appeared on the market at present with voice alarm function of products.These products are the main problem is big, alarm measuring blind area lags behind, without considering the automobile braking inertial factors and make drivers brake lag, the anti-interference ability is not strong, misstatement or more.The automotive anti-collision radar is able to realize impact-proof alarm functions, basically have ultrasonic this intangible ruler, it recently obstacles distance measurement, and told to the owner.Actually ultrasonic range-finding principle simple: it emit ultrasonic echo, and receive reflected by microcontroller counter obtain both lag using formula S = t, Ct / 2 calculating distances, including S for cars and obstacles, C for the distance between the sound wave propagation in the medium speed.This paper introduces the ultrasonic ranging system only have 2 ultrasonic transducer(known as probe)respectively, decorate in cars left and right after after 2 position.Capable of detecting forward and reverse direction obstacle distance, the rearview mirror built-in display element display distance and direction, issued must be sound, plays the role of hints and alert.System USES a STC89C52 SCM two way ultrasonic signal cyclicly acquisition.Ultrasonic refers to the 20HHZ wave frequency is over.In order to use the ultrasonic detection means, must generate as ultrasonic wave and receiving damnation.Complete the functions of the device is called the

中原工學院畢業(yè)設(shè)計（論文）譯文

ultrasonic sensor, habit, ultrasonic transducer or ultrasonic probe.Ultrasonic sensors have both transmitters and receivers, but a ultrasonic sensors can also has the sending and receiving the sound waves of the dual role.Ultrasonic sensors is using the principle of piezoelectric effect and ultrasonic energy conversion, be in namely emit ultrasonic, energy conversion, launch ultrasonic, And in the stockades, received echo ultrasonic vibration into electrical signal.Ultrasonic ranging principle generally USES the time method for the crossing.First measured ultrasonic from the launch to meet obstacles returns experience of time, again multiply ultrasonic speed of get twice the distance between the sound source and obstacles.Measuring distance a variety of ways, short can use ruler, long-range laser displacement etc, are suitable for high accuracy of ultrasonic ranging in long distance measurement.Because of ultrasound in standard air of propagation speed 331.45 meters per second, by single-chip microcomputer is responsible for timing, SCM use 12.0 M crystals, so the system of measurement precision theory can achieve mm level.Because of ultrasonic directivity strong, energy consumption is slow, in a medium transmission distance, thus ultrasonic can be used for distance measurement.Using ultrasonic detection distance, the design is more convenient, computing procese also relatively simple, and the measurement precision can also meet the requirements.Ultrasonic generator can be divided into two kinds: one kind is to use electrical means producing ultrasonic, one kind is with mechanical approach to producing ultrasonic.This design belongs to nearly distance measurement, can use commonly used the piezoelectric ultrasonic transducer to achieve trigger unit.Using ultrasonic ranging work, can according to measuring launch reflection wave wave and the time interval between the measured distance, so as to achieve the effect.It mainly have three ranging methods:

(1)phase assay, phase assays high precision, but detection though limited range，(2)sound amplitude assay, acoustic amplitude assay vulnerable reflection wave influence;

(3)ferrying more time assay, crossing the time assay way of working is simple, intuitive, in hardware control and software design are very easy to implement.Its principle is: from the launch emit ultrasonic detection sensor, the gas medium spread to receive sensor of time, this time is crossing the more time.This design is the use of ultrasonic ranging the crossing the time assay.In the mobile vehicles of the application 15

中原工學院畢業(yè)設(shè)計（論文）譯文

of ultrasonic sensor is the use of ultrasound in air of directional spread and solid reflective characteristics(p-wave)and by receiving their launch ultrasonic reflecting signal, according to the ultrasonic issued and echo receiving the Windows and propagation speed, calculate transmission distance, thus obtains the obstacles to vehicle distance.中原工學院畢業(yè)設(shè)計（論文）譯文

2.A principle of ultrasonic distance measurement

2.1 the principle of piezoelectric ultrasonic generator

Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work.Ultrasonic generator, the internal structure as shown, it has two piezoelectric chip and a resonance plate.When it’s two plus pulse signal, the frequency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promote the development of plate vibration resonance, ultrasound is generated.Conversely, if the two are not inter-electrode voltage, when the board received ultrasonic resonance, it will be for vibration suppression, then it becomes the ultrasonic receiver.The traditional way to determine the moment of the echo’s arrival is based on thresholding the received signal with a fixed reference.The threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the echo signal surpasses that threshold.The intensity of an echo reflecting from an object strongly depends on the object’s nature, size and distance from the sensor.Further, the time interval from the echo’s starting point to the moment when it surpasses the threshold changes with the different intensities arriving exactly at the same tome will surpass the threshold at different moments.The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer object.2.2 The principle of ultrasonic distance measurement Ultrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the same time, the spread of ultrasound in the air, obstracles on his way to return immediately, the ultrasonic reflected wave wave received by the reveiver immediately stop the clock.Ultrasonic in the air as the propagation velocity of 340m/s, according to the timer records the time t, we can calculate the distance between the launch distance barrier(s), that is:s=340t/2

中原工學院畢業(yè)設(shè)計（論文）譯文

3.Ultrasonic Ranging System for the Second Circuit Design

System is characterized by single-chip microcomputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, single-chip selection of 8751,economic-to –use, and the chip has 4K of ROM, to facilitate programming.Circuit schematic diagram shown in Figure 1.Figure 1 circuit principle diagram

中原工學院畢業(yè)設(shè)計（論文）譯文

3.1 40 kHz ultrasonic pulse generated with the launch

Ranging system using the ultrasonic sensor of piezoelectric sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the single-chip implementation of the following procedures to generate.Puzel:mov 14h,# 12h;ultrasonic firing continued 200ms here:cpl pl.0;output 40 kHz square wave

nop;

nop;nop;djnz 14h, here;ret Ranging in front of single-chip termination circuit P1.0 input port, single chip implementation of the above procedure, the P1.0 port in a 40kHz pulze output signal, after amplification transistor T, the drive to launch the first ultrasonic UCM40T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms.Ranging the right and the left side of the circuit, respectively, then input port P1.1 and P1.2, the working principle and circuit in front of the same location.3.2 Reception and processing of ultrasonic

Used to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the op-amp amplification IC1A and after polarization IC1B to IC2.IC2 is locked loop with audio decoder chip LM567, internal voltage-controlled oscillator center frequency of f0=1/1.1R8C3, capacitor C4 determine their target bandwidth.R8-conditioning in the launch of the carrier frequency on the LM567 input signal is greater than 25Mv, the output from the high jump 8 feet into a low-level, as interrupt request signals to the single-chip processing.Ranging in front of single-chip termination circuit port INT0 interrupt the highest priority, right or left location of the output circuit with output gete IC3A access INT1 port single-chip, while single-chip P1.3 and P1.4 received input IC3A, interrupted by the process to identify the source code is as follows: receivel:

push psw

push ace

中原工學院畢業(yè)設(shè)計（論文）譯文

cir ex1: related external interrupt 1

jnb p1.1, right;P1.1 pin to 0, ranging from right to interrupt service rountine circuit

jnb p1.2, left;P1.2 pin to 0, to the left ranging circuit

interrupt service routine return:SETB EX1;open external interrupt 1

pop

acc pop

psw reti right:…;right location entrance circuit interrupt service rountine

Ajmp Return left:…;left Ranging entrance circuit interrupt service rountine

Ajmp Return

3.3 The calculation of ultrasonic propagation time

When you start firing at the same time start the single-chip circuitry within the timer T0, the use of timer counting function records the time and the launch of ultrasonic reflected wave received time when you receive the ultrasonic reflected wave, the receiver circuit outputs a negative jump in the end of INT0 or INT1 interrupt request generates a signal, single-chip microcomputer in response to external interrupt request, the implementation of the external interrupt service subroutine, read the time difference, calculating the distance.Some of its source is as follows: RECEIVE0: PUSH PSW PUSH ACC CLR EX0;related external interrupt 0 MOV R7, TH0;read the time value MOV R6, TL0 CLR C MOV A, R6 SUBB A,#0BBH;calculate the tome difference MOV 31H, A;storage results MOV A, R7 SUBB A,#3CH

中原工學院畢業(yè)設(shè)計（論文）譯文

MOV 30H,A SETB EX0;open external interrupt 0 POP ACC POP PAW RETI For a flat target, a distance measurement consists of two phases: a coarse measurement and, a fine measurement: Step 1: Transmission of one pulse train to produce a simple ultrasonic

Wave.Step 2: Changing the gain of both echo amplifiers according to equation，until the echo is detected.Step 3:detection of te amplitudes anf zero-crossing times of both echoes.Step 4:setting the gains of both echo amplifiers to normalize the output at, say 3 volts.Setting the period of the next pulses according to the: period of echoes.Setting the time window according to the data of step 2.Step 5:sending two pulse trains to produce an interfered wave.Testing the zero-crossing in the echo,detemine to otherwise calculate to by interpolation using the amplitudes near the trough.Derive t sub ml and t sub m2.Step6: Calculation of the distance y using equation.中原工學院畢業(yè)設(shè)計（論文）譯文

4.The ultrasonic ranging system software design

Software is divided into two parts, the main program and interrupt service routine.Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving control.Tnterrupt service routines from time to complete three of the rotation direction of ultrasonic launch, the main external interrupt service subroutine to resd the value of completion time, distance calculation, the results of the output and so on.中原工學院畢業(yè)設(shè)計（論文）譯文

5.Conclusions

Required measuring range of 30cm~200cm objects inside the plane to do a number of measurements found that the maximum error is 0.5cm, and good reproducibility.Single-chip design can be seen on the ultrasonic ranging system has a hardware structure is simple, reliable, small features such as measurement error.Therefore, it can be used not only for mobile robot can be used in other detection systems.Thoughts: As for why the receiver do not have the transistor amplifier circuit, because the magnification well, integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency is 38k to 40k, is exactly resonant ultrasonic sensors frequency.中原工學院畢業(yè)設(shè)計（論文）譯文

REFERENCES 1.Fox,J.D.,Khuri-Yakub, B.T.and Kino, G.S., ‖High Frequency Acoustic Wave Measurement in Air‖, in Proceedings of IEEE 1983 Ultrasonic Symposium, October 31-2 November, 1983, Atlanta, GA, pp.581-4.2.Martin Abreu,J.M.,Ceres,R.and Freire, T.,‖Ultrasonic Ranging: Envelope Analysis Gives Improved Accuracy‖, Sensor Review, Vol.12No.1,1992, pp.17-21.3.Parrilla， M., Anaya,J.J and Fritsch C.,‖Digital Signal Processing Techniques for High Accuracy Ultrasonic Range Measurement:,IEEE Transactions: Instrumentation and Measurement.Vol.40 No.4, August 1991,pp.750-63.4.Canali, C., Cicco, G.D., Mortem, B., Prudenziati, M., and Taron, A., ―A Temperature Compensated Ultrasonic Sensor Operating in Air for Distance and Proxinmity Measurement‖, IEEE Trasaction on Industry Electronics, Vol, IE-29 No.4,1982, pp.336-41.5.Martin, J.M., Ceres, R., Calderon, L and Freire, T., ‖Ultrasonic Ranging Gets Themal Correction‖, Sensor Review, Vol, 9 No.3, 1989,pp.153-5.24

第五篇：外文翻譯

Low Voltage Flyback DC-DC Converter For

Power Supply Applications Hangzhou Liu1, John Elmes2, Kejiu Zhang1, Thomas X.Wu1, Issa Batarseh1

Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, FL 32816, USA Advanced Power Electronics Corporation, Orlando, FL 32826, USA Abstract ：In this paper, we design a low voltage DC-DC converter with a flyback transformer.The converter will be used as a biased power supply to drive IGBTs.The flyback transformer using planar EI-core is designed and simulated using ANSYS PExprt software.Besides, anLT3574 IC chip from Linear Technology has been chosen for converter control.Finally, the converter modeling and simulation are presented and PCB layout is designed.Keywords：Flyback, anLT3574IC, PCB

I.INTRODUCTION The goal of this project is to develop and build a prototype of a high-efficiency, high-temperature isolated DC-DC converter to be used as a biased power supply for driving a complementary IGBT pair.It is important that the converter can deliver the required power at an ambient temperature of up to 100℃;therefore it has to be efficient so that its components do not exceed their maximum temperature ratings.The final converter will be completely sealed and potted in a metal case.The input voltage range for this converter is from 9V to 36V.The output sides have two terminals, one is﹢16V and the other one is﹣6V.In order to get the desired performance, anLT3574 IC chip from Linear Technology is used.The key to this design is the flyback transformer.The transformer using planar EI-core is designed and simulated using ANSYS PExprt software.Finally, the PCB layout of the converter will be presented.II.KEY DESIGN OUTLINE For this flyback topology, the output voltage can be determined by both the transformer turns ratio and the flyback loop resistor pairs.Therefore, at the initial design stage, we can choose a convenient turn’s ratio for the transformer, and modify it later on if necessary to make sure the output performance is desirable and the transformer will not saturate [1].The relationship between transformers turns ratio and duty cycle can be found as

Where n is the transformer turns ratio, D is the duty cycle, VO` is the sum of the output voltage plus the rectifier drop voltage, VIN is the input voltage of the transformer.The value of feedback resistor can be calculated as

Where RREF is the reference resistor, whose value is typically 6.04k?;α is a constant of 0.986;VBG is the internal band gap reference voltage, 1.23V;and VTC is normally 0.55V [1].With a specific IC chosen, the converter circuit can be designed based on a demo circuit and some parameters may need to be modified if necessary to optimize the performance.Furthermore, in LT Spice, a large number of simulations need to be done with different conditions such as load resistor values and input voltage levels.It is important to make sure that the output voltage can be regulated well with all these different conditions.The most critical part of the design is the flyback transformer.With high switching frequency, the AC resistance can only be estimated based on some traditional methods such as Dowell’s curve rule [2].In order to get more accurate values of AC resistance values;we propose to use finite element electromagnetic software ANSYS PExprt to do the design [3].At the initial design stage, key parameters such as the worst-case input voltage, frequency, material, inductance values will be decided.After that, these data will be imported to the software, from which an optimized solution will be generated.III.CONVERTER SIMULATION RESULTS We choose LT3574 chip in this design.From the simulation results in Figure 1 and Table 1, it clearly shows that the output voltages which are﹢16V and-6V respectively can be regulated pretty well with the input voltage range from 9V to 36V.The voltage tolerance ranges are from ﹢15V to ﹢19V and-12V toDC converter for low voltage power supply application has been designed.The modeling and simulation results are presented.Based on the design specifications, a suitable IC from Linear Technology is chosen.A large amount of circuit simulations with different conditions such as load resistor values and input voltage levels are presented to get the desirable output voltage and current performance.The transformer has been designed including electrical, mechanical and thermal properties.With all the specific components decided, the PCB layout of the converter has been designed as well.REFERENCE

[1] Linear Technology Application Notes , Datasheet of Isolated Flyback Converter Without an Opto-Coupler, http://cds.linear.com/docs /Datasheet/3574f.pdf.[2] P.L.Dowell, “Effect of eddy currents in transformer windings” Proceedings of the IEE, NO.8 PP.1387-1394, Aug 1966.[3] S.Xiao, “Planar Magnetics Design for Low-Voltage DC-DC Converters” MS, 2004.[4] ANSYS Application Notes, PEmag Getting Started: A Transformer Design Example, http://004km.cn/download/ EDA/Maxwell9/planarGS0601.pdf.[5] K.Zhang;T.X.Wu;H.Hu;Z.Qian;F.Chen.;K.Rustom;N.Kutkut;J.Shen;I.Batarseh;“Analysis and design of distributed transformers for solar power conversion” 2011 IEEE Applied Power Electronics Conference and Exposition(APEC), v l., no., pp.1692-1697, 6-11 March 2011.[6] Zhang.;T.X.Wu.;N.Kutkut;J.Shen;D.Woodburn;L.Chow;W.Wu;H.Mustain;I.Batarseh;,“Modeling and design optimization of planar power transformer for aerospace applic ation,” Proceedings of the IEEE 2009 National, Aerospace & Electronics Conference(NAECON), vol., no., pp.116-120, 21-23 July 2009.[7] Ferroxcube Application Notes, Design of Planar Power Transformer,