数据库毕业设计---外文翻译
毕业论文(设计)外文文献翻译及原文
金融体制、融资约束与投资——来自OECD的实证分析R．SemenovDepartment of Economics，University of Nijmegen，Nijmegen（荷兰内梅亨大学，经济学院）这篇论文考查了OECD的11个国家中现金流量对企业投资的影响.我们发现不同国家之间投资对企业内部可获取资金的敏感性具有显著差异,并且银企之间具有明显的紧密关系的国家的敏感性比银企之间具有公平关系的国家的低.同时，我们发现融资约束与整体金融发展指标不存在关系.我们的结论与资本市场信息和激励问题对企业投资具有重要作用这种观点一致，并且紧密的银企关系会减少这些问题从而增加企业获取外部融资的渠道。
一、引言各个国家的企业在显著不同的金融体制下运行。
金融发展水平的差别(例如，相对GDP的信用额度和相对GDP的相应股票市场的资本化程度），在所有者和管理者关系、企业和债权人的模式中，企业控制的市场活动水平可以很好地被记录.在完美资本市场,对于具有正的净现值投资机会的企业将一直获得资金。
然而，经济理论表明市场摩擦，诸如信息不对称和激励问题会使获得外部资本更加昂贵，并且具有盈利投资机会的企业不一定能够获取所需资本.这表明融资要素，例如内部产生资金数量、新债务和权益的可得性，共同决定了企业的投资决策.现今已经有大量考查外部资金可得性对投资决策的影响的实证资料（可参考，例如Fazzari（1998）、 Hoshi(1991)、 Chapman（1996）、Samuel(1998））.大多数研究结果表明金融变量例如现金流量有助于解释企业的投资水平。
这项研究结果解释表明企业投资受限于外部资金的可得性。
很多模型强调运行正常的金融中介和金融市场有助于改善信息不对称和交易成本，减缓不对称问题,从而促使储蓄资金投着长期和高回报的项目,并且提高资源的有效配置（参看Levine（1997)的评论文章）。
因而我们预期用于更加发达的金融体制的国家的企业将更容易获得外部融资.几位学者已经指出建立企业和金融中介机构可进一步缓解金融市场摩擦。
毕业设计外文翻译_英文版
A Design and Implementation of Active NetworkSocket ProgrammingK.L. Eddie Law, Roy LeungThe Edward S. Rogers Sr. Department of Electrical and Computer EngineeringUniversity of TorontoToronto, Canadaeddie@, roy.leung@utoronto.caAbstract—The concept of programmable nodes and active networks introduces programmability into communication networks. Code and data can be sent and modified on their ways to destinations. Recently, various research groups have designed and implemented their own design platforms. Each design has its own benefits and drawbacks. Moreover, there exists an interoperability problem among platforms. As a result, we introduce a concept that is similar to the network socket programming. We intentionally establish a set of simple interfaces for programming active applications. This set of interfaces, known as Active Network Socket Programming (ANSP), will be working on top of all other execution environments in future. Therefore, the ANSP offers a concept that is similar to “write once, run everywhere.” It is an open programming model that active applications can work on all execution environments. It solves the heterogeneity within active networks. This is especially useful when active applications need to access all regions within a heterogeneous network to deploy special service at critical points or to monitor the performance of the entire networks. Instead of introducing a new platform, our approach provides a thin, transparent layer on top of existing environments that can be easily installed for all active applications.Keywords-active networks; application programming interface; active network socket programming;I. I NTRODUCTIONIn 1990, Clark and Tennenhouse [1] proposed a design framework for introducing new network protocols for the Internet. Since the publication of that position paper, active network design framework [2, 3, 10] has slowly taken shape in the late 1990s. The active network paradigm allows program code and data to be delivered simultaneously on the Internet. Moreover, they may get executed and modified on their ways to their destinations. At the moment, there is a global active network backbone, the ABone, for experiments on active networks. Apart from the immaturity of the executing platform, the primary hindrance on the deployment of active networks on the Internet is more on the commercially related issues. For example, a vendor may hesitate to allow network routers to run some unknown programs that may affect their expected routing performance. As a result, alternatives were proposed to allow active network concept to operate on the Internet, such as the application layer active networking (ALAN) project [4] from the European research community. In the ALAN project, there are active server systems located at different places in the networks and active applications are allowed to run in these servers at the application layer. Another potential approach from the network service provider is to offer active network service as the premium service class in the networks. This service class should provide the best Quality of Service (QoS), and allow the access of computing facility in routers. With this approach, the network service providers can create a new source of income.The research in active networks has been progressing steadily. Since active networks introduce programmability on the Internet, appropriate executing platforms for the active applications to execute should be established. These operating platforms are known as execution environments (EEs) and a few of them have been created, e.g., the Active Signaling Protocol (ASP) [12] and the Active Network Transport System (ANTS) [11]. Hence, different active applications can be implemented to test the active networking concept.With these EEs, some experiments have been carried out to examine the active network concept, for example, the mobile networks [5], web proxies [6], and multicast routers [7]. Active networks introduce a lot of program flexibility and extensibility in networks. Several research groups have proposed various designs of execution environments to offer network computation within routers. Their performance and potential benefits to existing infrastructure are being evaluated [8, 9]. Unfortunately, they seldom concern the interoperability problems when the active networks consist of multiple execution environments. For example, there are three EEs in ABone. Active applications written for one particular EE cannot be operated on other platforms. This introduces another problem of resources partitioning for different EEs to operate. Moreover, there are always some critical network applications that need to run under all network routers, such as collecting information and deploying service at critical points to monitor the networks.In this paper, a framework known as Active Network Socket Programming (ANSP) model is proposed to work with all EEs. It offers the following primary objectives.• One single programming interface is introduced for writing active applications.• Since ANSP offers the programming interface, the design of EE can be made independent of the ANSP.This enables a transparency in developing andenhancing future execution environments.• ANSP addresses the interoperability issues among different execution environments.• Through the design of ANSP, the pros and cons of different EEs will be gained. This may help design abetter EE with improved performance in future.The primary objective of the ANSP is to enable all active applications that are written in ANSP can operate in the ABone testbed . While the proposed ANSP framework is essential in unifying the network environments, we believe that the availability of different environments is beneficial in the development of a better execution environment in future. ANSP is not intended to replace all existing environments, but to enable the studies of new network services which are orthogonal to the designs of execution environments. Therefore, ANSP is designed to be a thin and transparent layer on top of all execution environments. Currently, its deployment relies on automatic code loading with the underlying environments. As a result, the deployment of ANSP at a router is optional and does not require any change to the execution environments.II. D ESIGN I SSUES ON ANSPThe ANSP unifies existing programming interfaces among all EEs. Conceptually, the design of ANSP is similar to the middleware design that offers proper translation mechanisms to different EEs. The provisioning of a unified interface is only one part of the whole ANSP platform. There are many other issues that need to be considered. Apart from translating a set of programming interfaces to other executable calls in different EEs, there are other design issues that should be covered, e.g., • a unified thread library handles thread operations regardless of the thread libraries used in the EEs;• a global soft-store allows information sharing among capsules that may execute over different environmentsat a given router;• a unified addressing scheme used across different environments; more importantly, a routing informationexchange mechanism should be designed across EEs toobtain a global view of the unified networks;• a programming model that should be independent to any programming languages in active networks;• and finally, a translation mechanism to hide the heterogeneity of capsule header structures.A. Heterogeneity in programming modelEach execution environment provides various abstractions for its services and resources in the form of program calls. The model consists of a set of well-defined components, each of them has its own programming interfaces. For the abstractions, capsule-based programming model [10] is the most popular design in active networks. It is used in ANTS [11] and ASP [12], and they are being supported in ABone. Although they are developed based on the same capsule model, their respective components and interfaces are different. Therefore, programs written in one EE cannot run in anther EE. The conceptual views of the programming models in ANTS and ASP are shown in Figure 1.There are three distinct components in ANTS: application, capsule, and execution environment. There exist user interfaces for the active applications at only the source and destination routers. Then the users can specify their customized actions to the networks. According to the program function, the applications send one or more capsules to carry out the operations. Both applications and capsules operate on top of an execution environment that exports an interface to its internal programming resources. Capsule executes its program at each router it has visited. When it arrives at its destination, the application at destination may either reply it with another capsule or presents this arrival event to the user. One drawback with ANTS is that it only allows “bootstrap” application.Figure 1. Programming Models in ASP and ANTS.In contrast, ASP does not limit its users to run “bootstrap” applications. Its program interfaces are different from ANTS, but there are also has three components in ASP: application client, environment, and AAContext. The application client can run on active or non-active host. It can start an active application by simply sending a request message to the EE. The client presents information to users and allows its users to trigger actions at a nearby active router. AAContext is the core of the network service and its specification is divided into two parts. One part specifies its actions at its source and destination routers. Its role is similar to that of the application in ANTS, except that it does not provide a direct interface with the user. The other part defines its actions when it runs inside the active networks and it is similar to the functional behaviors of a capsule in ANTS.In order to deal with the heterogeneity of these two models, ANSP needs to introduce a new set of programming interfaces and map its interfaces and execution model to those within the routers’ EEs.B. Unified Thread LibraryEach execution environment must ensure the isolation of instance executions, so they do not affect each other or accessThe authors appreciate the Nortel Institute for Telecommunications (NIT) at the University of Toronto to allow them to access the computing facilitiesothers’ information. There are various ways to enforce the access control. One simple way is to have one virtual machine for one instance of active applications. This relies on the security design in the virtual machines to isolate services. ANTS is one example that is using this method. Nevertheless, the use of multiple virtual machines requires relatively large amount of resources and may be inefficient in some cases. Therefore, certain environments, such as ASP, allow network services to run within a virtual machine but restrict the use of their services to a limited set of libraries in their packages. For instance, ASP provides its thread library to enforce access control. Because of the differences in these types of thread mechanism, ANSP devises a new thread library to allow uniform accesses to different thread mechanisms.C. Soft-StoreSoft-store allows capsule to insert and retrieve information at a router, thus allowing more than one capsules to exchange information within a network. However, problem arises when a network service can execute under different environments within a router. The problem occurs especially when a network service inserts its soft-store information in one environment and retrieves its data at a later time in another environment at the same router. Due to the fact that execution environments are not allowed to exchange information, the network service cannot retrieve its previous data. Therefore, our ANSP framework needs to take into account of this problem and provides soft-store mechanism that allows universal access of its data at each router.D. Global View of a Unified NetworkWhen an active application is written with ANSP, it can execute on different environment seamlessly. The previously smaller and partitioned networks based on different EEs can now be merging into one large active network. It is then necessary to advise the network topology across the networks. However, different execution environments have different addressing schemes and proprietary routing protocols. In order to merge these partitions together, ANSP must provide a new unified addressing scheme. This new scheme should be interpretable by any environments through appropriate translations with the ANSP. Upon defining the new addressing scheme, a new routing protocol should be designed to operate among environments to exchange topology information. This allows each environment in a network to have a complete view of its network topology.E. Language-Independent ModelExecution environment can be programmed in any programming language. One of the most commonly used languages is Java [13] due to its dynamic code loading capability. In fact, both ANTS and ASP are developed in Java. Nevertheless, the active network architecture shown in Figure 2 does not restrict the use of additional environments that are developed in other languages. For instance, the active network daemon, anted, in Abone provides a workspace to execute multiple execution environments within a router. PLAN, for example, is implemented in Ocaml that will be deployable on ABone in future. Although the current active network is designed to deploy multiple environments that can be in any programming languages, there lacks the tool to allow active applications to run seamlessly upon these environments. Hence, one of the issues that ANSP needs to address is to design a programming model that can work with different programming languages. Although our current prototype only considers ANTS and ASP in its design, PLAN will be the next target to address the programming language issue and to improve the design of ANSP.Figure 2. ANSP Framework Model.F. Heterogeneity of Capsule Header StructureThe structures of the capsule headers are different in different EEs. They carries capsule-related information, for example, the capsule types, sources and destinations. This information is important when certain decision needs to be made within its target environment. A unified model should allow its program code to be executed on different environments. However, the capsule header prevents different environments to interpret its information successfully. Therefore, ANSP should carry out appropriate translation to the header information before the target environment receives this capsule.III. ANSP P ROGRAMMING M ODELWe have outlined the design issues encountered with the ANSP. In the following, the design of the programming model in ANSP will be discussed. This proposed framework provides a set of unified programming interfaces that allows active applications to work on all execution environments. The framework is shown in Figure 2. It is composed of two layers integrated within the active network architecture. These two layers can operate independently without the other layer. The upper layer provides a unified programming model to active applications. The lower layer provides appropriate translation procedure to the ANSP applications when it is processed by different environments. This service is necessary because each environment has its own header definition.The ANSP framework provides a set of programming calls which are abstractions of ANSP services and resources. A capsule-based model is used for ANSP, and it is currently extended to map to other capsule-based models used in ANTSand ASP. The mapping possibility to other models remains as our future works. Hence, the mapping technique in ANSP allows any ANSP applications to access the same programming resources in different environments through a single set of interfaces. The mapping has to be done in a consistent and transparent manner. Therefore, the ANSP appears as an execution environment that provides a complete set of functionalities to active applications. While in fact, it is an overlay structure that makes use of the services provided from the underlying environments. In the following, the high-level functional descriptions of the ANSP model are described. Then, the implementations will be discussed. The ANSP programming model is based upon the interactions between four components: application client , application stub , capsule , and active service base.Figure 3. Information Flow with the ANSP.•Application Client : In a typical scenario, an active application requires some means to present information to its users, e.g., the state of the networks. A graphical user interface (GUI) is designed to operate with the application client if the ANSP runs on a non-active host.•Application Stub : When an application starts, it activates the application client to create a new instance of application stub at its near-by active node. There are two responsibilities for the application stub. One of them is to receive users’ instructions from the application client. Another one is to receive incoming capsules from networks and to perform appropriate actions. Typically, there are two types of actions, thatare, to reply or relay in capsules through the networks, or to notify the users regarding the incoming capsule. •Capsule : An active application may contain several capsule types. Each of them carries program code (also referred to as forwarding routine). Since the application defines a protocol to specify the interactions among capsules as well as the application stubs. Every capsule executes its forwarding routine at each router it visits along the path between the source and destination.•Active Service Base : An active service base is designed to export routers’ environments’ services and execute program calls from application stubs and capsules from different EEs. The base is loaded automatically at each router whenever a capsule arrives.The interactions among components within ANSP are shown in Figure 3. The designs of some key components in the ANSP will be discussed in the following subsections. A. Capsule (ANSPCapsule)ANSPXdr decode () ANSPXdr encode () int length ()Boolean execute ()New types of capsule are created by extending the abstract class ANSPCapsule . New extensions are required to define their own forwarding routines as well as their serialization procedures. These methods are indicated below:The execution of a capsule in ANSP is listed below. It is similar to the process in ANTS.1. A capsule is in serial binary representation before it issent to the network. When an active router receives a byte sequence, it invokes decode() to convert the sequence into a capsule. 2. The router invokes the forwarding routine of thecapsule, execute(). 3. When the capsule has finished its job and forwardsitself to its next hop by calling send(), this call implicitly invokes encode() to convert the capsule into a new serial byte representation. length() isused inside the call of encode() to determine the length of the resulting byte sequence. ANSP provides a XDR library called ANSPXdr to ease the jobs of encoding and decoding.B. Active Service Base (ANSPBase)In an active node, the Active Service Base provides a unified interface to export the available resources in EEs for the rest of the ANSP components. The services may include thread management, node query, and soft-store operation, as shown in Table 1.TABLE I. ACTIVE SERVICE BASE FUNCTION CALLSFunction Definition Descriptionboolean send (Capsule, Address) Transmit a capsule towards its destination using the routing table of theunderlying environment.ANSPAddress getLocalHost () Return address of the local host as an ANSPAddress structure. This isuseful when a capsule wants to check its current location.boolean isLocal (ANSPAddress) Return true if its input argument matches the local host’s address andreturn false otherwise.createThread () Create a new thread that is a class ofANSPThreadInterface (discussed later in Section VIA “Unified Thread Abstraction”).putSStore (key, Object) Object getSStore (key) removeSStore (key)The soft-store operations are provided by putSStore(), getSSTore(), and removeSStore(), and they put, retrieve, and remove data respectively. forName (PathName) Supported in ANSP to retrieve a classobject corresponding to the given path name in its argument. This code retrieval may rely on the code loading mechanism in the environment whennecessary.C. Application Client (ANSPClient)boolean start (args[])boolean start (args[],runningEEs) boolean start (args[],startClient)boolean start (args[],startClient, runningEE)Application Client is an interface between users and the nearby active source router. It does the following responsibilities.1. Code registration: It may be necessary to specify thelocation and name of the application code in some execution environments, e.g., ANTS. 2. Application initialization: It includes selecting anexecution environment to execute the application among those are available at the source router. Each active application can create an application client instance by extending the abstract class, ANSPClient . The extension inherits a method, start(), to automatically handle both the registration and initialization processes. All overloaded versions of start() accept a list of arguments, args , that are passed to the application stub during its initialization. An optional argument called runningEEs allows an application client to select a particular set of environment variables, specified by a list of standardized numerical environment ID, the ANEP ID, to perform code registration. If this argument is not specified, the default setting can only include ANTS and ASP. D. Application Stub (ANSPApplication)receive (ANSPCapsule)Application stubs reside at the source and destination routers to initialize the ANSP application after the application clients complete the initialization and registration processes. It is responsible for receiving and serving capsules from the networks as well as actions requested from the clients. A new instance is created by extending the application client abstract class, ANSPApplication . This extension includes the definition of a handling routine called receive(), which is invoked when a stub receives a new capsule.IV. ANSP E XAMPLE : T RACE -R OUTEA testbed has been created to verify the design correctnessof ANSP in heterogeneous environments. There are three types of router setting on this testbed:1. Router that contains ANTS and a ANSP daemonrunning on behalf of ASP; 2. Router that contains ASP and a ANSP daemon thatruns on behalf of ANTS; 3. Router that contains both ASP and ANTS.The prototype is written in Java [11] with a traceroute testing program. The program records the execution environments of all intermediate routers that it has visited between the source and destination. It also measures the RTT between them. Figure 4 shows the GUI from the application client, and it finds three execution environments along the path: ASP, ANTS, and ASP. The execution sequence of the traceroute program is shown in Figure 5.Figure 4. The GUI for the TRACEROUTE Program.The TraceCapsule program code is created byextending the ANSPCapsule abstract class. When execute() starts, it checks the Boolean value of returning to determine if it is returning from the destination. It is set to true if TraceCapsule is traveling back to the source router; otherwise it is false . When traveling towards the destination, TraceCapsule keeps track of the environments and addresses of the routers it has visited in two arrays, path and trace , respectively. When it arrives at a new router, it calls addHop() to append the router address and its environment to these two arrays. When it finally arrives at the destination, it sets returning to false and forwards itself back to the source by calling send().When it returns to source, it invokes deliverToApp() to deliver itself to the application stub that has been running at the source. TraceCapsule carries information in its data field through the networks by executing encode() and decode(), which encapsulates and de-capsulates its data using External Data Representation (XDR) respectively. The syntax of ANSP XDR follows the syntax of XDR library from ANTS. length() in TraceCapsule returns the data length, or it can be calculated by using the primitive types in the XDRlibrary.Figure 5. Flow of the TRACEROUTE Capsules.V. C ONCLUSIONSIn this paper, we present a new unified layered architecture for active networks. The new model is known as Active Network Socket Programming (ANSP). It allows each active application to be written once and run on multiple environments in active networks. Our experiments successfully verify the design of ANSP architecture, and it has been successfully deployed to work harmoniously with ANTS and ASP without making any changes to their architectures. In fact, the unified programming interface layer is light-weighted and can be dynamically deployable upon request.R EFERENCES[1] D.D. Clark, D.L. Tennenhouse, “Architectural Considerations for a NewGeneration of Protocols,” in Proc. ACM Sigcomm’90, pp.200-208, 1990. [2] D. Tennenhouse, J. M. Smith, W. D. Sicoskie, D. J. Wetherall, and G. J.Minden, “A survey of active network research,” IEEE Communications Magazine , pp. 80-86, Jan 1997.[3] D. Wetherall, U. Legedza, and J. Guttag, “Introducing new internetservices: Why and how,” IEEE Network Magazine, July/August 1998. [4] M. Fry, A. Ghosh, “Application Layer Active Networking,” in ComputerNetworks , Vol.31, No.7, pp.655-667, 1999.[5] K. W. Chin, “An Investigation into The Application of Active Networksto Mobile Computing Environments”, Curtin University of Technology, March 2000.[6] S. Bhattacharjee, K. L. Calvert, and E. W. Zegura, “Self OrganizingWide-Area Network Caches”, Proc. IEEE INFOCOM ’98, San Francisco, CA, 29 March-2 April 1998.[7] L. H. Leman, S. J. Garland, and D. L. Tennenhouse, “Active ReliableMulticast”, Proc. IEEE INFOCOM ’98, San Francisco, CA, 29 March-2 April 1998.[8] D. Descasper, G. Parulkar, B. Plattner, “A Scalable, High PerformanceActive Network Node”, In IEEE Network, January/February 1999.[9] E. L. Nygren, S. J. Garland, and M. F. Kaashoek, “PAN: a high-performance active network node supporting multiple mobile code system”, In the Proceedings of the 2nd IEEE Conference on Open Architectures and Network Programming (OpenArch ’99), March 1999. [10] D. L. Tennenhouse, and D. J. Wetherall. “Towards an Active NetworkArchitecture”, In Proceeding of Multimedia Computing and Networking , January 1996.[11] D. J. Wetherall, J. V. Guttag, D. L. Tennenhouse, “ANTS: A toolkit forBuilding and Dynamically Deploying Network Protocols”, Open Architectures and Network Programming, 1998 IEEE , 1998 , Page(s): 117 –129.[12] B. Braden, A. Cerpa, T. Faber, B. Lindell, G. Phillips, and J. Kann.“Introduction to the ASP Execution Environment”: /active-signal/ARP/index.html .[13] “The java language: A white paper,” Tech. Rep., Sun Microsystems,1998.。
毕业设计论文外文文献翻译
毕业设计(论文）外文文献翻译院系：财务与会计学院年级专业：201＊级财务管理姓名:学号：132148*＊*附件: 财务风险管理【Abstract】Although financial risk has increased significantly in recent years risk and risk management are not contemporary issues。
The result of increasingly global markets is that risk may originate with events thousands of miles away that have nothing to do with the domestic market。
Information is available instantaneously which means that change and subsequent market reactions occur very quickly。
The economic climate and markets can be affected very quickly by changes in exchange rates interest rates and commodity prices。
Counterparties can rapidly become problematic。
As a result it is important to ensure financial risks are identified and managed appropriately. Preparation is a key component of risk management。
【Key Words】Financial risk，Risk management，YieldsI. Financial risks arising1.1What Is Risk1.1.1The concept of riskRisk provides the basis for opportunity. The terms risk and exposure have subtle differences in their meaning. Risk refers to the probability of loss while exposure is the possibility of loss although they are often used interchangeably。
本科毕业设计外文文献翻译
（Sheaｒ waｌl ｓt ｒuctural desigｎ ofh ｉgh-ｌev ｅl fr ａmeworkＷｕ Jiche ｎgＡbstract ： In t ｈis pape ｒ the basic c ｏｎcepts of ｍａn ｐow ｅr ｆｒom th ｅ ｆra ｍｅ sh ｅａr w ａｌl str ｕc ｔｕｒｅ, analy ｓis of the ｓtruct ｕr ａｌ des ｉgn ｏf th ｅ c ｏnt ｅnt ｏｆ t ｈe fr ａme she ａr wall, in ｃｌudi ｎg the ｓeism ｉc wa ｌl she ａr spa本科毕业设计外文文献翻译学校代码： 10128学 号：题 目：Shear wall structural design of high-level framework 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程专业（建筑工程方向） 班 级：土木08-（5）班 指导教师： (副教授)ｎratiｏdesign, ａnd a concrｅtｅｓtruｃtuｒe in thｅmｏst co ｍmonｌy useｄframe shear walｌstｒｕcturｅtｈｅdesign of p ｏiｎｔs to note.Keyworｄs: cｏncrｅｔｅ; fｒaｍｅshｅａｒwall sｔｒucｔｕre；hiｇh－risｅbuildｉｎｇsThe wall is aｍoｄern high－rｉｓe buiｌdiｎgs is an iｍpo ｒｔant buiｌdinｇconｔｅnt, the ｓize of thｅfraｍe sheａr wall must comｐly with buildｉng reguｌａtｉons. The pｒｉnｃipｌe is ｔhat the largeｒsｉzｅbｕt the thｉｃknessｍuｓt ｂｅsmaller gｅoｍetric featｕrｅｓshoｕlｄｂe ｐｒeｓented ｔo the pｌatｅ,ｔｈe forｃe is close to cylｉndrｉcal.Ｔhe waｌl sｈｅar wa ｌl strｕｃｔure ｉs a flaｔcomｐonent. Itｓeｘposure to tｈe force aｌoｎg ｔhe ｐlane leｖｅl of theｒole ofｓｈear and momｅｎt, must also take ｉｎtｏａccounｔthe veｒｔical preｓsure.Opeｒate unｄer thｅcomｂiｎed actｉｏn oｆbenｄing momeｎts and axial force aｎｄsheａr forcｅbｙthe caｎtilｅｖｅr deep beａm uｎder ｔｈe acｔion of the force leveｌｔo lｏo ｋinto ｔｈe bottom mouｎted on ｔhe basｉs of. Sheaｒｗaｌl ｉｓdiｖidｅｄinｔo a whole walｌand ｔheａssoｃiated ｓｈeａr wall in thｅactual project,a wholｅwａlｌfor ｅxａmpl ｅ, suｃh as ｇenｅraｌhｏusiｎｇｃonstｒuction in tｈe gablｅｏr fish bｏne strｕcture ｆｉlｍwａｌls ａnd small opｅningｓwall.Cｏupled Sｈeａr ｗalls are ｃonnｅcted bｙｔhｅcｏupｌing ｂeam shｅａr wall.Buｔｂecause tｈeｇｅnerａlｃｏupling beaｍstｉｆfness is less thaｎｔhe wall stiｆfnｅsｓof the lｉmbs，ｓｏ. Wａlｌliｍb aｌonｅis obviｏus.The ｃｅntral beam of tｈeｉnflｅｃtion pｏｉnｔtｏpay aｔtenｔiｏｎto tｈeｗaｌl pressｕre thａn the limiｔs of the lｉmb axis. Will forｍa shortｗiｄe beａms，widｅcolｕmn wａll liｍｂｓhear wａll ｏpｅnings toｏlarge ｃomｐonｅnt aｔbothｅn ｄs ｗith jｕst the domain of vａｒiabｌe crosｓ－ｓecｔｉon ro ｄin ｔhe intｅrｎａｌforcｅｓｕnder tｈｅaｃtioｎof maｎy Ｗalｌlｉmb iｎflｅcｔion point Ｔhｅｒeｆoｒe, ｔhe cａｌcula ｔions ａｎd consｔruction sｈouldAccordinｇtｏappｒoxiｍａｔe tｈe framｅstｒucｔure to ｃonsideｒ.Tｈe desｉｇｎof ｓhｅａr walls ｓhoulｄbe based on the cｈａractｅrisｔics ｏf ａvａｒｉｅty oｆwall itseｌｆ,ａnd dｉfferｅnｔmeｃhanical ch ａrａcteｒisｔｉcｓand requireｍents,wall oｆthｅinternａｌforceｄistrｉbutｉon and failurｅmoｄｅs ｏf sｐecific and cｏmprehensive ｃonｓideration of the design rｅinｆorcemｅnt aｎd stｒuctural measｕres. Ｆrame sｈear wall ｓｔrｕctuｒe deｓiｇn is to cｏｎsider the ｓtructｕre of the oｖerall ａnａｌysis for ｂoｔh dｉrecｔｉｏｎsｏｆthｅhｏrｉzontal and vｅrtiｃalｅfｆects. Oｂtain thｅinternal force ｉs reｑuirｅd in ａccｏrdancｅｗｉｔｈtｈe bias or paｒtｉal ｐull normal sｅcｔｉon forｃｅｃaｌculatiｏn.The waｌl strｕcture oｆtheｆｒame sｈear ｗall ｓｔructural dｅsign of ｔhe coｎtent frame hｉgh-rise buildings, in ｔhe actual ｐrｏjeｃｔiｎｔhｅuse of thｅｍoｓt seisｍic ｗａlls have suffiｃient quantitｉeｓto meｅt ｔheｌｉmitsｏf the lａyer displacement, the loｃation iｓｒelａtiｖely flexiblｅ. Seiｓmic wａll for cｏntinuous layout，ｆulｌ-length ｔhroｕgh．Should bｅdesigned to avoid the waｌl mutaｔioｎs ｉn limb ｌｅｎgth and alignment is noｔuｐａnd down the ｈolｅ. The samｅtｉme．Tｈe inｓide of ｔhe hole marginｓcｏlｕｍｎshｏｕld not ｂｅｌｅssｔhan３00mm ｉｎordｅｒtｏguaraｎteｅtheｌengtｈof the colｕｍn ａs the edgｅof tｈe coｍponent and constｒａiｎt eｄgｅcｏｍponeｎts．Thｅbi-direc ｔiｏnal laｔerａl forｃe ｒesiｓting strucｔurａl fｏrm of verticａl aｎｄhorｉzontaｌwalｌcoｎnected.Eａｃh ｏｔhｅr as ｔhe ａffiｎiｔｙof the shｅar wall. Ｆor ｏnｅ, two seismic frａme sｈe ａr ｗalｌｓ,ｅｖen beam highｒatio ｓhould noｔgreateｒthan 5 aｎd a height of nｏt less thaｎ400mm.Midline colｕmnａnd beａmｓ,wall ｍｉdline shouｌdｎoｔbe greaｔer tha ｎthe ｃoｌｕmｎwidｔｈof1/4，ｉn ordｅr ｔｏreｄuce thｅtoｒsional eｆfect of the sｅiｓmｉｃacｔion ｏnｔｈｅｃolｕmn．Oｔhｅrwｉsｅcan be taken tｏstrengthｅn theｓtirruprａｔｉo iｎｔhe cｏlｕmn tｏmake ｕp.If thｅshear wａｌl sheａｒsｐａn ｔhａnｔhe ｂig twｏ. Ｅveｎthe beａｍcro ｓs-heｉｇht ratiｏgreateｒthan 2.5, ｔhen tｈe design presｓｕｒe ｏf thｅｃｕt shoulｄnoｔmａkｅａｂig 0.2. Howevｅｒ, ｉf the sheａｒwallｓheａr sｐａｎｒatiｏof ｌess than two couｐlinｇｂeａms sｐan of ｌeｓs than ２．5, then the shear coｍｐres ｓiｏn rａｔiｏis noｔgreaｔer thａn 0.15. Thｅｏther haｎｄ，ｔhe bｏttom oｆthe fraｍe ｓhｅar walｌstructure ｔo enhａnce tｈｅdｅsign sｈould ｎoｔbe leｓs thaｎ２０0mmａnd noｔlesｓthaｎstorey 1/１6，othｅｒｐaｒtｓｓhｏulｄnot be lｅss than 160mm ａnd ｎｏt ｌｅss thaｎｓtoｒey １/20. Arounｄthe wall of the frame ｓhｅar ｗall strucｔure sｈｏulｄbe set ｔo the beａm or dark bｅamａnd the sｉｄe columｎｔｏform a borｄｅr. Ｈoｒizｏntａl ｄｉｓtrｉbuｔioｎoｆsｈear waｌls cａn from the sheａr effect，tｈｉs design wｈen ｂuilｄｉng higｈｅr longeｒor fｒaｍｅｓtructｕre reinfoｒcｅment shｏuld be aｐprｏpｒiatelｙincｒeａｓed, ｅspｅcｉａlｌy in the sｅnｓitivｅｐarts of the beam pｏsition ｏr teｍperaｔuｒe, stiffnｅsｓchａnge is besｔappｒopriatｅly increased, ｔｈeｎcｏnsidｅration sｈoulｄbe ｇｉveｎｔo the wａlｌvertｉcaｌreiｎforｃemeｎt,becaｕse ｉt is mａinly fｒom the bｅnding efｆecｔ, aｎｄtake in ｓome ｍｕlti-ｓtorｅｙshｅａｒｗａll structuｒereinforcｅｄreｉnｆorceｍent rate -likｅlｅsｓconｓtｒained edgｅｏｆｔhｅcomｐonent or components reinforｃemeｎt of thｅedge ｃomｐｏnent.Referｅnces: [1 sad Hａyaｓhi,He Yaming. Ｏn the shorｔshｅar ｗall ｈigh-riｓe bｕilｄinｇｄesign ［J]．Kｅｙｕaｎ, 2008, (O2).高层框架剪力墙结构设计吴继成摘要: 本文从框架剪力墙结构设计的基本概念人手, 分析了框架剪力墙的构造设计内容, 包括抗震墙、剪跨比等的设计, 并出混凝土结构中最常用的框架剪力墙结构设计的注意要点。
毕业设计外文资料翻译sc-pdf
毕业设计外文资料翻译题目甲醇氧化生产甲醛的银催化剂改性学院化学化工学院专业化学工程与工艺班级0803学生许继盟学号20080207167指导教师倪献智二〇一二年三月十五日Catalysts Today, 1996, (28): 239-244.甲醇氧化生产甲醛的银催化剂的改性A.N.Pestryakov摘 要 银催化剂的性能可用Zr ，La ， Rb ，C s 的氧化物改性，改性后的银催化剂的物化性能和催化性能已在甲醇的选择性氧化工艺中研究过，甲醇氧化制甲醛工艺中，质量分数为1%-10%的改性添加物会改变载体银的有效电荷及氧化还原性能、金属分散度和其表面扩散、催化剂表面酸度及结焦程度。
当银催化性能改变时，改性物主要影响催化剂活性位（++δn Ag Ag）。
关键词 银催化剂；甲醇氧化为甲醛 1 简介甲醇选择性氧化生产甲醛工艺中使用大量的载体银催化剂[1-3]。
采用不同的非有机添加物对银催化剂进行改性是提高其性能的最有前景的方法之一。
在银催化剂发现之后，人们致力于对其进行改进，以达到提高其催化活性和寿命，降低银使用量和扩展其工艺操作条件的目的。
广泛使用载体以减少银使用量及防止银在“严酷”条件（600-700 ℃）下烧结也是改性方法之一。
但是载体的堆积有限，不同改性化合物的少量添加（质量分数0.1-10%）可以使银可变的催化性能产生较大差异。
在科技和专利文献中提到过很多不同的添加物，它们能改善并激发银的催化性能[3-14]。
在这其中，研究人员提到改性作用的不同机理：银上金属的电子功能和电子密度改变[7-9]，O 2吸附的差异[3,10]，催化剂表面酸度[11]，催化剂表面的机械堵塞[12]，添加物的固有催化性质[13,14]。
然而，所有这些仅描述了催化剂改性的几个分散的方面，并没有涉及添加物对银催化剂改性影响的差异。
也没有考虑改性物对银催化剂活性位电子状态的影响。
在本文中，我们研究了改性物对银的性能影响的几个方面[15-18]，目的是在甲醇氧化制甲醛工艺中对稀有和稀土金属氧化物反应及银催化剂的电子属性、物化属性和催化属性进行综合研究。
毕业设计论文 外文文献翻译
毕业设计（论文）外文参考文献翻译计算机科学与信息工程系系（院）2008 届题目企业即时通Instant Messaging for Enterprises课题类型技术开发课题来源自选学生姓名许帅专业班级 04计算机科学与技术指导老师王占中职称工程师完成日期：2008年4 月 6 日目录I NSTANT M ESSAGING FOR E NTERPRISE (1)1. Tips (1)2. Introduction (1)3. First things first (2)4.The While-Accept loop (4)5. Per-Thread class (6)6. The Client class (7)企业即时通 (9)1.提示 (9)2.简介 (9)3.首先第一件事 (10)4.监听循环 (11)5.单线程类 (13)6.用户端类 (14)Instant Messaging for Enterprise1. TipsIf Java is, in fact, yet another computer programming language, you may question why it is so important and why it is being promoted as a revolutionary step in computer programming. The answer isn’t immediately obvious if you’re coming from a tr aditional programming perspective. Although Java is very useful for solving traditional standalone programming problems, it is also important because it will solve programming problems on the World Wide Web. What is the Web?The Web can seem a bit of a mys tery at first, with all this talk of “surfing,”“presence,” and “home pages.” It’s helpful to step back and see what it really is, but to do this you must understand client/server systems, another aspect of computing that is full of confusing issues. The primary idea of a client/server system is that you have a central repository of information，some kind of data, often in a database。
毕业设计(论文)外文资料翻译(学生用)
毕业设计外文资料翻译学院：信息科学与工程学院专业：软件工程姓名： XXXXX学号： XXXXXXXXX外文出处： Think In Java (用外文写)附件： 1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文网络编程历史上的网络编程都倾向于困难、复杂，而且极易出错。
程序员必须掌握与网络有关的大量细节，有时甚至要对硬件有深刻的认识。
一般地，我们需要理解连网协议中不同的“层”（Layer）。
而且对于每个连网库，一般都包含了数量众多的函数，分别涉及信息块的连接、打包和拆包；这些块的来回运输；以及握手等等。
这是一项令人痛苦的工作。
但是，连网本身的概念并不是很难。
我们想获得位于其他地方某台机器上的信息，并把它们移到这儿；或者相反。
这与读写文件非常相似，只是文件存在于远程机器上，而且远程机器有权决定如何处理我们请求或者发送的数据。
Java最出色的一个地方就是它的“无痛苦连网”概念。
有关连网的基层细节已被尽可能地提取出去，并隐藏在JVM以及Java的本机安装系统里进行控制。
我们使用的编程模型是一个文件的模型；事实上，网络连接（一个“套接字”）已被封装到系统对象里，所以可象对其他数据流那样采用同样的方法调用。
除此以外，在我们处理另一个连网问题——同时控制多个网络连接——的时候，Java内建的多线程机制也是十分方便的。
本章将用一系列易懂的例子解释Java的连网支持。
15.1 机器的标识当然，为了分辨来自别处的一台机器，以及为了保证自己连接的是希望的那台机器，必须有一种机制能独一无二地标识出网络内的每台机器。
早期网络只解决了如何在本地网络环境中为机器提供唯一的名字。
但Java面向的是整个因特网，这要求用一种机制对来自世界各地的机器进行标识。
为达到这个目的，我们采用了IP（互联网地址）的概念。
IP以两种形式存在着：(1) 大家最熟悉的DNS（域名服务）形式。
我自己的域名是。
所以假定我在自己的域内有一台名为Opus的计算机，它的域名就可以是。
数据库毕业设计外文翻译--数据库管理系统的介绍
Database Management Systems( 3th Edition ),Wiley ,2004, 5-12A introduction to Database Management SystemRaghu RamakrishnanA database (sometimes spelled data base) is also called an electronic database , referring to any collection of data, or information, that is specially organized for rapid search and retrieval by a computer. Databases are structured to facilitate the storage, retrieval , modification, and deletion of data in conjunction with various data-processing operations .Databases can be stored on magnetic disk or tape, optical disk, or some other secondary storage device.A database consists of a file or a set of files. The information in these files may be broken down into records, each of which consists of one or more fields. Fields are the basic units of data storage , and each field typically contains information pertaining to one aspect or attribute of the entity described by the database . Using keywords and various sorting commands, users can rapidly search , rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregate of data.Complex data relationships and linkages may be found in all but the simplest databases .The system software package that handles the difficult tasks associated with creating ,accessing, and maintaining database records is called a database management system(DBMS).The programs in a DBMS package establish an interface between the database itself and the users of the database.. (These users may be applications programmers, managers and others with information needs, and various OS programs.)A DBMS can organize, process, and present selected data elements form the database. This capability enables decision makers to search, probe, and query database contents in order to extract answers to nonrecurring and unplanned questions that aren’t available in regular reports. These questions might initially be vague and/or poorly defined ,but people can “browse” through the database until they have the needed information. In short, the DBMS will “manage”the stored data items and assemble the needed items from the common database in response to the queries ofthose who aren’t programmers.A database management system (DBMS) is composed of three major parts:(1)a storage subsystem that stores and retrieves data in files;(2) a modeling and manipulation subsystem that provides the means with which to organize the data and to add , delete, maintain, and update the data;(3)and an interface between the DBMS and its users. Several major trends are emerging that enhance the value and usefulness of database management systems;Managers: who require more up-to-data information to make effective decision Customers: who demand increasingly sophisticated information services and more current information about the status of their orders, invoices, and accounts.Users: who find that they can develop custom applications with database systems in a fraction of the time it takes to use traditional programming languages.Organizations : that discover information has a strategic value; they utilize their database systems to gain an edge over their competitors.The Database ModelA data model describes a way to structure and manipulate the data in a database. The structural part of the model specifies how data should be represented(such as tree, tables, and so on ).The manipulative part of the model specifies the operation with which to add, delete, display, maintain, print, search, select, sort and update the data. Hierarchical ModelThe first database management systems used a hierarchical model-that is-they arranged records into a tree structure. Some records are root records and all others have unique parent records. The structure of the tree is designed to reflect the order in which the data will be used that is ,the record at the root of a tree will be accessed first, then records one level below the root ,and so on.The hierarchical model was developed because hierarchical relationships are commonly found in business applications. As you have known, an organization char often describes a hierarchical relationship: top management is at the highest level, middle management at lower levels, and operational employees at the lowest levels. Note that within a strict hierarchy, each level of management may have manyemployees or levels of employees beneath it, but each employee has only one manager. Hierarchical data are characterized by this one-to-many relationship among data.In the hierarchical approach, each relationship must be explicitly defined when the database is created. Each record in a hierarchical database can contain only one key field and only one relationship is allowed between any two fields. This can create a problem because data do not always conform to such a strict hierarchy.Relational ModelA major breakthrough in database research occurred in 1970 when E. F. Codd proposed a fundamentally different approach to database management called relational model ,which uses a table as its data structure.The relational database is the most widely used database structure. Data is organized into related tables. Each table is made up of rows called and columns called fields. Each record contains fields of data about some specific item. For example, in a table containing information on employees, a record would contain fields of data such as a person’s last name ,first name ,and street address.Structured query language(SQL)is a query language for manipulating data in a relational database .It is nonprocedural or declarative, in which the user need only specify an English-like description that specifies the operation and the described record or combination of records. A query optimizer translates the description into a procedure to perform the database manipulation.Network ModelThe network model creates relationships among data through a linked-list structure in which subordinate records can be linked to more than one parent record. This approach combines records with links, which are called pointers. The pointers are addresses that indicate the location of a record. With the network approach, a subordinate record can be linked to a key record and at the same time itself be a key record linked to other sets of subordinate records. The network mode historically has had a performance advantage over other database models. Today , such performance characteristics are only important in high-volume ,high-speed transaction processing such as automatic teller machine networks or airline reservation system.Both hierarchical and network databases are application specific. If a new application is developed ,maintaining the consistency of databases in different applications can be very difficult. For example, suppose a new pension application is developed .The data are the same, but a new database must be created.Object ModelThe newest approach to database management uses an object model , in which records are represented by entities called objects that can both store data and provide methods or procedures to perform specific tasks.The query language used for the object model is the same object-oriented programming language used to develop the database application .This can create problems because there is no simple , uniform query language such as SQL . The object model is relatively new, and only a few examples of object-oriented database exist. It has attracted attention because developers who choose an object-oriented programming language want a database based on an object-oriented model. Distributed DatabaseSimilarly , a distributed database is one in which different parts of the database reside on physically separated computers . One goal of distributed databases is the access of information without regard to where the data might be stored. Keeping in mind that once the users and their data are separated , the communication and networking concepts come into play .Distributed databases require software that resides partially in the larger computer. This software bridges the gap between personal and large computers and resolves the problems of incompatible data formats. Ideally, it would make the mainframe databases appear to be large libraries of information, with most of the processing accomplished on the personal computer.A drawback to some distributed systems is that they are often based on what is called a mainframe-entire model , in which the larger host computer is seen as the master and the terminal or personal computer is seen as a slave. There are some advantages to this approach . With databases under centralized control , many of the problems of data integrity that we mentioned earlier are solved . But today’s personal computers, departmental computers, and distributed processing require computers andtheir applications to communicate with each other on a more equal or peer-to-peer basis. In a database, the client/server model provides the framework for distributing databases.One way to take advantage of many connected computers running database applications is to distribute the application into cooperating parts that are independent of one anther. A client is an end user or computer program that requests resources across a network. A server is a computer running software that fulfills those requests across a network . When the resources are data in a database ,the client/server model provides the framework for distributing database.A file serve is software that provides access to files across a network. A dedicated file server is a single computer dedicated to being a file server. This is useful ,for example ,if the files are large and require fast access .In such cases, a minicomputer or mainframe would be used as a file server. A distributed file server spreads the files around on individual computers instead of placing them on one dedicated computer.Advantages of the latter server include the ability to store and retrieve files on other computers and the elimination of duplicate files on each computer. A major disadvantage , however, is that individual read/write requests are being moved across the network and problems can arise when updating files. Suppose a user requests a record from a file and changes it while another user requests the same record and changes it too. The solution to this problems called record locking, which means that the first request makes others requests wait until the first request is satisfied . Other users may be able to read the record, but they will not be able to change it .A database server is software that services requests to a database across a network. For example, suppose a user types in a query for data on his or her personal computer . If the application is designed with the client/server model in mind ,the query language part on the personal computer simple sends the query across the network to the database server and requests to be notified when the data are found.Examples of distributed database systems can be found in the engineering world. Sun’s Network Filing System(NFS),for example, is used in computer-aidedengineering applications to distribute data among the hard disks in a network of Sun workstation.Distributing databases is an evolutionary step because it is logical that data should exist at the location where they are being used . Departmental computers within a large corporation ,for example, should have data reside locally , yet those data should be accessible by authorized corporate management when they want to consolidate departmental data . DBMS software will protect the security and integrity of the database , and the distributed database will appear to its users as no different from the non-distributed database .Database Management Systems( 3th Edition ),Wiley ,2004, 5-12数据库管理系统的介绍Raghu Ramakrishnan数据库（database,有时拼作data base）又称为电子数据库，是专门组织起来的一组数据或信息，其目的是为了便于计算机快速查询及检索。
大学毕业设计关于数据库外文翻译2篇
原文：Structure of the Relational database—《Database System Concepts》Part1: Relational Databases The relational model is the basis for any relational database management system (RDBMS).A relational model has three core components: a collection of obj ects or relations, operators that act on the objects or relations, and data integrity methods. In other words, it has a place to store the data, a way to create and retrieve the data, and a way to make sure that the data is logically consistent.A relational database uses relations, or two-dimensional tables, to store the information needed to support a business. Let's go over the basic components of a traditional relational database system and look at how a relational database is designed. Once you have a solid understanding of what rows, columns, tables, and relationships are, you'll be well on your way to leveraging the power of a relational database.Tables, Row, and ColumnsA table in a relational database, alternatively known as a relation, is a two-dimensional structure used to hold related information. A database consists of one or more related tables.Note: Don't confuse a relation with relationships. A relation is essentially a table, and a relationship is a way to correlate, join, or associate two tables.A row in a table is a collection or instance of one thing, such as one employee or one line item on an invoice. A column contains all the information of a single type, and the piece of data at the intersection of a row and a column, a field, is the smallest piece of information that can be retrieved with the database's query language. For example, a table with information about employees might have a column calledLAST_NAME that contains all of the employees' last names. Data is retrieved from a table by filtering on both the row and the column.Primary Keys, Datatypes, and Foreign KeysThe examples throughout this article will focus on the hypothetical work of Scott Smith, database developer and entrepreneur. He just started a new widget company and wants to implement a few of the basic business functions using the relational database to manage his Human Resources (HR) department.Relation: A two-dimensional structure used to hold related information, also known as a table.Note: Most of Scott's employees were hired away from one of his previous employers, some of whom have over 20 years of experience in the field. As a hiring incentive, Scott has agreed to keep the new employees' original hire date in the new database.Row:A group of one or more data elements in a database table that describes a person, place, or thing.Column:The component of a database table that contains all of the data of the same name and type across all rows.You'll learn about database design in the following sections, but let's assume for the moment that the majority of the database design is completed and some tables need to be implemented. Scott creates the EMP table to hold the basic employee information, and it looks something like this:Notice that some fields in the Commission (COMM) and Manager (MGR) columns do not contain a value; they are blank. A relational database can enforce the rule that fields in a column may or may not be empty. In this case, it makes sense for an employee who is not in the Sales department to have a blank Commission field. It also makes sense for the president of the company to have a blank Manager field, since that employee doesn't report to anyone.Field:The smallest piece of information that can be retrieved by the database query language. A field is found at the intersection of a row and a column in a database table.On the other hand, none of the fields in the Employee Number (EMPNO) column are blank. The company always wants to assign an employee number to an employee, and that number must be different for each employee. One of the features of a relational database is that it can ensure that a value is entered into this column and that it is unique. Th e EMPNO column, in this case, is the primary key of the table.Primary Key:A column (or columns) in a table that makes the row in the table distinguishable from every other row in the same table.Notice the different datatypes that are stored in the EMP ta ble: numeric values, character or alphabetic values, and date values.As you might suspect, the DEPTNO column contains the department number for the employee. But how do you know what department name is associated with what number? Scott created the DEPT table to hold the descriptions for the department codes in the EMP table.The DEPTNO column in the EMP table contains the same values as the DEPTNO column in the DEPT table. In this case, the DEPTNO column in the EMP table is considered a foreign key to the same column in the DEPT table.A foreign key enforces the concept of referential integrity in a relational database. The concept of referential integrity not only prevents an invalid department number from being inserted into the EMP table, but it also prevents a row in the DEPT table from being deleted if there are employees still assigned to that department.Foreign Key:A column (or columns) in a table that draws its values from a primary or unique key column in another table. A foreign key assists in ensuring the data integrity of a table. Referential Integrity A method employed by a relational database system that enforces one-to-many relationships between tables.Data ModelingBefore Scott created the actual tables in the database, he went through a design process known as data modeling. In this process, the developer conceptualizes and documents all the tables for the database. One of the common methods for mod eling a database is called ERA, which stands for entities, relationships, and attributes. The database designer uses an application that can maintain entities, their attributes, and their relationships. In general, an entity corresponds to a table in the database, and the attributes of the entity correspond to columns of the table.Data Modeling:A process of defining the entities, attributes, and relationships between the entities in preparation for creating the physical database.The data-modeling process involves defining the entities, defining the relationships between those entities, and then defining the attributes for each of the entities. Once a cycle is complete, it is repeated as many times as necessary to ensure that the designer is capturing what is important enough to go into the database. Let's take a closer look at each step in the data-modeling process.Defining the EntitiesFirst, the designer identifies all of the entities within the scope of the database application.The entities are the pers ons, places, or things that are important to the organization and need to be tracked in the database. Entities will most likely translate neatly to database tables. For example, for the first version of Scott's widget company database, he identifies four entities: employees, departments, salary grades, and bonuses. These will become the EMP, DEPT, SALGRADE, and BONUS tables.Defining the Relationships Between EntitiesOnce the entities are defined, the designer can proceed with defining how each of the entities is related. Often, the designer will pair each entity with every other entity and ask, "Is there a relationship between these two entities?" Some relationships are obvious; some are not.In the widget company database, there is most likely a relations hip between EMP and DEPT, but depending on the business rules, it is unlikely that the DEPT and SALGRADE entities are related. If the business rules were to restrict certain salary grades to certain departments, there would most likely be a new entity that defines the relationship between salary grades and departments. This entity wouldbe known as an associative or intersection table and would contain the valid combinations of salary grades and departments.Associative Table:A database table that stores th e valid combinations of rows from two other tables and usually enforces a business rule. An associative table resolves a many-to-many relationship.In general, there are three types of relationships in a relational database:One-to-many The most common type of relationship is one-to-many. This means that for each occurrence in a given entity, the parent entity, there may be one or more occurrences in a second entity, the child entity, to which it is related. For example, in the widget company database, the DEPT entity is a parent entity, and for each department, there could be one or more employees associated with that department. The relationship between DEPT and EMP is one-to-many.One-to-one In a one-to-one relationship, a row in a table is related to only one or none of the rows in a second table. This relationship type is often used for subtyping. For example, an EMPLOYEE table may hold the information common to all employees, while the FULLTIME, PARTTIME, and CONTRACTOR tables hold information unique to full-time employees, part-time employees, and contractors, respectively. These entities would be considered subtypes of an EMPLOYEE and maintain a one-to-one relationship with the EMPLOYEE table. These relationships are not as common as one-to-many relationships, because if one entity has an occurrence for a corresponding row in another entity, in most cases, the attributes from both entities should be in a single entity.Many-to-many In a many-to-many relationship, one row of a table may be related to man y rows of another table, and vice versa. Usually, when this relationship is implemented in the database, a third entity isdefined as an intersection table to contain the associations between the two entities in the relationship. For example, in a database used for school class enrollment, the STUDENT table has a many-to-many relationship with the CLASS table—one student may take one or more classes, and a given class may have one or more students. The intersection table STUDENT_CLASS would contain the comb inations of STUDENT and CLASS to track which students are in which classes.Once the designer has defined the entity relationships, the next step is to assign the attributes to each entity. This is physically implemented using columns, as shown here for th e SALGRADE table as derived from the salary grade entity.After the entities, relationships, and attributes have been defined, the designer may iterate the data modeling many more times. When reviewing relationships, new entities may be discovered. For exa mple, when discussing the widget inventory table and its relationship to a customer order, the need for a shipping restrictions table may arise.Once the design process is complete, the physical database tables may be created. Logical database design sessions should not involve physical implementation issues, but once the design has gone through an iteration or two, it's the DBA's job to bring the designers "down to earth." As a result, the design may need to be revisited to balance the ideal database implementation versus the realities of budgets andschedules.译文：关系数据库的结构—《数据库系统结构》第一章：关系数据库关系模型是任何关系数据库管理系统（RDBMS）的基础。
数据库毕业设计外文翻译--图像系统简介
附录1 外文原文COLOR SYSTEM OVERVIEWIn the age of office automation and electronic imaging, office documents are being processed, transported, and displayed in a variety of ways. The scope of document processing is enormous; it encompasses page layout, document length, collation, simplex/duplex, color, image quality, finishing, and binding. If the office system is networked, then another dimension of network-related issues-protocol, file format, page description language, compression/decompression, job management, error handling, user interface, and device driver-has to be addressed. Digital color-imaging systems process electronic information from various sources; images may come from a local-area network, a remote-sensing device, different color workstations, or a local scanner. After processing, a document is usually compressed and transmitted to several places via a computer network for viewing, editing, or printing. Moreover, the trend in the industry is moving toward an open environment. This means that various devices such as scanners, computers, workstations, modems, and printers from multiple vendors are assembled into one system. Implementations should be based on public-domain technology rather than proprietary standards. This will allow vendors equal access to the market for system components and give users the widest choice in selecting components. It is a vastly large task to enable the communication of all system components regardless of differences in the operating system, file format, page description language, and information content. Ideally, the exchange should not cause information loss or alteration. A closer look at a document may reveal that it consists of different types of images, primarily text, graphs, and pictorial images. These all have different image characteristics and representations such as ASCII (American Standard Code for Information Interchange) for text, vector for graphs, and raster for pictorial images. Each type of image and its associated attributes like the font, font size, halftone, gray level, resolution, and color have to be dealt with differently. In such a complex environment, there is no doubt that many compatibility problems occur when an image is acquired, transmitted, displayed, and rendered. ?With the fast development of Internet technology, large volumes of data in the form of electronic documents from the Web. For the purposes of data integration and data exchange, more and moreexisting sources, such as relational databases, support public XML export, and increasing amount of public and private data is described in a semi-structured way. A number of issues need to be addressed when we integrate data from different sources, including heterogeneous and duplicate data, multiple divisions and partners, and changes.? Data heterogeneity results from the use of different information management systems to store data and each system has its own data structure and access methods. Relational database management systems benefit from the universal acceptance of Structured Query Language (SQL) as the primary means of getting answers whilst document and email repositories are generally accessed using text search engines with varying interfaces and capabilities. Because these systems were not designed with interoperability in mind, each must generally be accessed using source-specific applications or application programming interfaces (APIs).? Another difficulty in data integration is data duplication-different systems represent the same piece of data in different ways. For example, customers may be identified by name in one database, but by account number in a second repository, may identify the same customer by email address. Frequently a required piece of information is derived from multiple data points. Data integration is further complicated when customers do business with multiple divisions within a large company, or with other partners. Similarly, answering questions about the state of a company's supply chain requires access to vendor and distributor information sources. Doing business electronically across the firewall gives rise to security and data ownership issues. Finally, data integration has to deal with different types of changes; change in business requirements and strategies, in IT systems, mergers and acquisitions, and new product launches. This demands that a data integration solution be sufficiently flexible and adaptable.One possible solution for the data integration problems mentioned above is to provide an XML Web services break down the barriers between different computing platforms, development environments and communications networks, allowing organizations to work together electronically without the expense and delay of agreeing on semantics, schema, interfaces, and other application integration. XML provides the flexibility for handling data with differing structures. As XML is becoming the principal medium for data exchange over the Web and for information integration in general,increasing amounts of public and private data are described in XML. XML data is usually defined in a tree or graph based, self-describing object instance model (Boncz and Kersten, 1999). However, semi-structured data is incompatible with the flat structure of relational database tables, and so the growth of XML data requires new and complex query optimization techniques.Creating XML files with a text editor would be a lot easier if you didn't have to close all those HTML tags. First you have to add the XML declaration and the root opening and closing HTML tags. Next, you start adding element opening and closing tags one at a time. Of course, once you have the initial sequence completed you can just copy and paste to repeat the required elements. After doing this hundreds of times you'll be looking for a faster way to create XML files.Some XML editors will automatically add the closing tag after you have finished typing the opening tag but, you still have to type the brackets around the opening tag. I kept thinking this process should be easier. So, I came up with a solution that allows you to create XML files without using HTML tags.This console application will create an XML file based on user input. Just enter the file name, how many element fields you want, and the name of each field. Optionally, you can include a data type separated by a comma after the field name. You can just enter the field name because the data type is not required. The structure of the XML file that is created will be compatible with the .NET Dataset and can be easily added to a database.In addition to creating the XML file, an XSL file and HTML file are also created. The HTML file uses client side JavaScript to transform the XML file using the XSL file. This provides an easy way to view the new XML file by displaying it in a table layout.The download includes both the source code and the already compiled application. You can start using the executable right away or customize it to meet your needs. All you will need is the .NET Framework and a text editor, like Notepad, to build this application.Improving ASP Performance with Data CachingOne of the nicest features of is the ability to cache page content. This can be used to substantially reduce load on a website's database - which is an obvious attraction if the site uses Microsoft's Access to store data rather than SQL Server. Unfortunately there is no built in cachingsystem in classic ASP, but it is easy to build one by using the Application object to store data.When to use ASP Caching. Caching is most useful for data that changes - but not too often. For example an e-commerce store could display a list of popular products, or an information site could display a list of press releases.Don't forget that it is also possible to build functionality into the admin part of the site so that the cache would be flushed if new content is added to the database. That way the website administrator would not have to wait until the cache timed out in order for new content to appear on the website. Remember that data stored in Application variables is visible by all the users of the website。
毕 业 设 计(英文翻译)
附录G：英文翻译参考（要求学生完成与论文有关的外文资料中文字数5000字左右的英译汉，旨在培养学生利用外文资料开展研究工作的能力，为所选课题提供前沿参考资料。
）毕业设计（英文翻译）题目系别：专业：班级：学生姓名：学号：指导教师：一位从事质量管理的人约瑟夫·朱兰出生于圣诞夜,1904 在罗马尼亚的喀尔巴阡山脉山中。
他青年时期的村庄中贫穷、迷信和反犹太主义甚是猖獗。
1912年朱兰家搬到了明尼阿波尼斯州，虽然充满了危险，但是它却让一个男孩充满信心和希望。
从如此多了一个在质量观念的世界最好改革者之一。
在他90年的生活中，朱兰一直是一个精力充沛的思想者倡导者，推动着传统的质量思想向前走。
因为九岁就被雇用,朱兰表示在他的生活工作上永不停止。
记者:技术方面如何讲质量?朱兰:技术有不同方面:一、当然是精密。
物的对精密的需求像电子学、化学…我们看来它们似乎需要放大来说,和重要的原子尘的有关于质量。
要做到高精密具有相当大的挑战，而且我们已经遇见非常大的挑战。
另外的一个方面是可信度－没有失败。
当我们举例来说建立一个系统，同类空中交通管制的时候,我们不想要它失败。
我们必须把可信度建入系统。
因为我们投入很大的资金并依赖这些系统，系统非常复杂，这是逐渐增加的。
除此之外,有对公司的失败费用。
如果事物在领域中意外失败,可以说，它影响民众。
但是如果他们失败在内部,然后它影响公司的费用,而且已经试着发现这些费用在哪里和该如何免除他们。
因此那些是相当大的因素:精密、可信度和费用。
还有其它的,当然，但是我认为这些是主要的一些。
记者:据说是质量有在美国变成一种产业的可能?朱兰:资讯科技当然有。
已经有大的变化。
在世纪中初期当质量的一个想法到一个检验部门的时候，这有了分开的工作，东西被做坏之后。
检验是相当易错的程序,实际上。
而且无论如何，资讯科技在那天中相当花时间，直到某事已经被认为是否资讯科技是正确的。
应该强调计划，如此它不被错误首先订定。
外文翻译----高级数据库应用
信息与计算科学毕业设计Advanced Database ApplicationsThe 1990s have seen significant changes in the computer industry. In database systems, we have seen the widespread acceptance of RDBMSs for traditional business applications, such as order processing, inventory control, banking, and airline reservations. However, existing RDBMSs have proven inadequate for applications whose needs are quite different from those of traditional business database applications. These applications include:■computer-aided design (CAD);■computer-aided manufacturing (CAM);■computer-aided software engineering (CASE);■office information systems (OIS) and multimedia systems;■digital publishing;■eographic information systems (GIS);■interactive and dynamic Web sites.Computer-aided design (CAD)A CAD database stores data relating to mechanical and electrical design covering, for example, buildings, aircraft, and integrated circuit chips. Designs of this type have some common characteristics:■Design data is characterized by a large number of types, each with a small number of instances.Conventional databases are typically the opposite. For example, the DreamHome database consists of only a dozen or so relations, although relations such as PropertyForRent, Client, and Viewing may contain thousands of tuples.■Designs may be very large, perhaps consisting of millions of parts, often with many interdependent subsystem designs.■The design is not static but evolves through time. When a design change occurs, its implications must be propagated through all design representations. The dynamic nature of design may mean that some actions cannot be foreseen at the beginning.■Updates are fat-reaching because of topological or functional relationships, tolerances, and so on. One change is likely to affect a large number of design objects.■Often, many design alternatives are being considered for each component, and the correct version for each part must be maintained. This involves some form of version control and1configuration management.■There may be hundreds of staff involved with the design, and they may work in parallel on multiple versions of a large design. Even so, the end-product must be consistent and coordinated. This is sometimes referred to as cooperative engineering.Computer-aided manufacturing （CAM）A CAM database stores similar data to a CAD system, in addition to addition to data relating to discrete production (such as cars on an assembly line) and continuous production (such as chemical synthesis). For example, in chemical manufacturing there will be applications that monitor information about the state of the system, such as reactor Bessel temperatures, flow rates, and yields. There will also be applications that control various physical processes, such as opening valves, applying more heat to reactor vessels, and increasing the flow of cooling systems. These applications are often organized in a hierarchy, with a top-level application monitoring the entire factory and lower=level applications monitoring individual manufacturing processes. These applications must respond in real time and be capable of adjusting processes to maintain optimum performance within tight tolerances. The applications use a combination of standard algorithms and custom rules to respond to different conditions. Operators may modify these rules occasionally to optimize performance based on complex historical data that the system has to maintain. In this example, the system has to maintain large volumes of data that is hierarchical in nature and maintain complex relationships between the data. It must also be able to rapidly navigate the data to review and respond to changes.Computer-aided software engineering (CASE)A CASE database stores data relating to stages of the software development lifecycle: planning, requirements collection and analysis, design, implementation, testing, maintenance, and documentation. As with CAD, designs may be extremely large, and cooperative engineering is the norm. For example, software configuration management tools allow concurrent sharing of project design, code, and documentation. They also track the dependencies between these components and assist with change management. Project management tools facilitate the coordination of various project management activities, such as the scheduling of potentially highly complex interdependent tasks, cost estimation, and progress monitoring.Network management systemsNetwork management systems coordinate the delivery of communication services across a2信息与计算科学毕业设计computer network. These systems perform such tasks as network path management, problem management, and network planning. As with the chemical manufacturing example we discussed earlier, these systems also handle complex data and require real-time performance and continuous operation. For examples, a telephone call might involve a chain of network switching devices that route a message from sender to receiver, such as:Node⇔Link⇔Node⇔Link⇔Node⇔Link⇔NodeWhere each Node represents a port on a network device and each Link represents a slice of bandwidth reserved for that connection. However, a node may participate in several different connections and any database that is created has to manage a complex graph of relationships. To route connections, diagnose problems, and balance loadings, the network management systems have to be capable of moving through this complex graph in real time.Office information systems (OIS) and multimedia systemsAn OIS database stores data relating to the computer control of information in a business, including electronic mail, documents, invoices, and so on. To provide better support for this area, we need to handle a wider range of data types other than names, addresses, dates, and money. Modern systems now handle free-form text, photographs, diagrams, and audio and video sequences. For example, a multimedia document may handle text, photographs, spreadsheets, and voice commentary. The documents may have a specific structure imposed on them, perhaps described using a mark-up language such as SGML (Standardized Generalized Markup Language), HTML (HyperText Markup Language), or XML (eXtended Markup Language), as we discuss in Chapter 29.Documents may be shared among many users using systems such as electronic mail and bulletin-boards based on Internet technology. Again ,such applications need to store data that has a much richer structure than tuples consisting of numbers and text strings. There is also an increasing need to capture handwritten notes using electronic devices. Although many notes can be transcribed into AS CⅡtext using handwriting analysis techniques, most such data cannot. In addition to words, handwritten data can include sketches, diagrams and so on.In the DreamHome case study, we may find the following requirements for handling multimedia.■Image data A client may query an image data base of properties for rent. Some queries may simply use a textual description to identify images of desirable properties. In other cases it may3be useful for the client to query using graphical images of features that may be found in desirable properties (such as bay windows, internal cornicing, or roof gardens).■Video data A client may query a video database of properties for rent. Some queries may simply use a textual description to identify the video images of desirable properties. In other cases it may be useful for the client to query using video features of the desired properties (such as views of the sea or surrounding hills).■Audio data A client may query an audio database that describes the features of properties for rent. Some queries may simply use a textual description to identify the desired property. In other cases it may be useful for the client to use audio features of the desired properties (such as the noise level from nearby traffic).■Handwritten data A member of staff may create notes while carrying out inspections of properties for rent. At a later data, he or she may wish to query such data to find all notes made about a flat in Novar Drive with dry rot.Digital publishingThe publishing industry is likely to undergo profound changes in business practices over the next decade. It is becoming possible to store books, journals, papers, and articles electronically and deliver them over high-speed networks to consumers. As with office information systems, digital publishing is being extended to handle multimedia documents consisting of text, audio, image, and video data and animation. In some cases, the amount of information available to be put online is enormous, in the order of petabytes (1015 bytes), which would make them the largest databases that a DBMA has ever had to manage.Geographic information systems (GIS)A GIS database stores various types of spatial and temporal information, such as that used in land management and underwater exploration. Much of the data in these systems is derived from survey and satellite photographs, and tends to be very large. Searches may involve identifying features based, for example, on shape, color, or texture, using advanced pattern-recognition techniques.For example, EOS (Earth Observing System) is a collection of satellites launched by NASA in the 1990s to gather information that will support sci8entists concerned with long-term trends regarding the earth’s atmosphere, oceans, and land. It is anticipated that these satellites will return over one-third of a petabyte of information per year. This data will be integrated with other data4信息与计算科学毕业设计sources and will be stored in EOSDIS (EOS Data and Information System). EOSDIS will supply the information needs of both scientists and non-scientists. For example, schoolchildren will be able to access EOSDIS to see a simulation of world weather patterns. The immense size of this database and the need to support thousands of users with very heavy volumes of information requests will provide many challenges for DBMSs.Interactive and dynamic Web sites■Consider a Web site that has an online catalog for selling clothes. The Web site maintains a set of preferences for previous visitors to the site and allows a visitor to:■browse through thumbnail images of the items in the catalog and select one to obtain a full-size image with supporting details;■search for items that match a user-defined set of criteria;■obtain a 3D rendering of any item of clothing based on a customized specification (for example, color, size, fabric);■modify the rendering to account for movement, illumination, backdrop, occasion, and so on;■select accessories to go with the outfit, from items presented in a sidebar;■select a voiceover commentary giving additional details of the item;■view a running total of the bill, with appropriate discounts;■conclude the purchase through a secure online transaction.The requirements for this type of application are not that different from some of the above advanced applications: there is a need to handle multimedia content (text, audio, image, video data, and animation) and to interactively modify the display based on user preferences and user selections. As well as handling complex data, the site also has the added complexity o9f providing 3D rendering. It is argued that in such a situation the database is not just presenting information to the visitor but is actively engaged in selling, dynamically providing customized information and atmosphere to the visitor (King, 1997).As we discuss in Chapters 28 and 29, the Web now provides a relatively new paradigm for data management, and languages such as XML hold significant promise, particularly for the e-Commerce market. The Forrester Research Group is predicting that business-to-business transactions will rise by 99% annually and is expected to reach US$1.3 trillion by 2003. in addition, e-Commerce is expected to account for US$3.2 trillion in worldwide corporate revenue by 2003 and potentially represent 5% of sales in the global economy. As the use of the Internet5increases and the technology becomes more sophisticated, then we will see Web sites and business-to-business transactions handle much more complex and interrelated data.Other advanced database applications include:■Scientific and medical applications, which may store complex data representing systems such as molecular models for synthetic chemical compounds and genetic material.■Expert systems, which may store knowledge and rule bases for artificial intelligence (AI) applications.■Other applications with complex and interrelated objects and procedural data.原文摘自2004年出版的Database Systems A Practical Approach to Design Implementation and Management第580页6信息与计算科学毕业设计高级数据库应用20世纪90年代，计算机工业发生了巨大变化。
数据库毕业设计外文翻译--正确选择数据采集系统
中英文翻译Selecting the Right Data Acquisition SystemEngineers often must monitor a handful of signals over extended periods of time, and then graph and analyze the resulting data. The need to monitor, record and analyze data arises in a wide range of applications, including the design-verification stage of product development, environmental chamber monitoring, component inspection, benchtop testing and process trouble-shooting.This application note describes the various methods and devices you can use to acquire, record and analyze data, from the simple pen-and-paper method to using today's sophisticated data acquisition systems. It discusses the advantages and disadvantages of each method and provides a list of questions that will guide you in selecting the approach that best suits your needs.IntroductionIn geotechnical engineering, we sometime encounter some difficulties such as monitoring instruments distributed in a large area, dangerous environment of working site that cause some difficulty for easy access. In this case, operators may adopt remote control, by which a large amount of measured data will be transmitted to a observation room where the data are to be collected, stored and processed.The automatic data acquisition control system is able to complete the tasks as regular automatic data monitoring, acquisition and store, featuring high automation, large data store capacity and reliable performance.The system is composed of acquisition control system and display system, with the following features:1. No. of Channels: 32 ( can be increased or decreased according to user's real needs.)2. Scanning duration: decided by user, fastest 32 points/second3. Store capacity: 20G( may be increased or decreased)4. Display: (a) Table of parameter (b) History tendency (c) Column graphics.5. Function: real time monitoring control, warning6. Overall dimension: 50cm×50cm×72cmData acquisition systems, as the name implies, are products and/or processes used to collect information to document or analyze some phenomenon. In the simplest form, a technician logging the temperature of an oven on a piece of paper is performing data acquisition. As technology has progressed, this type of process has been simplified and made more accurate, versatile, and reliable through electronic equipment. Equipment ranges from simple recorders to sophisticated computer systems. Data acquisition products serve as a focal point in a system, tying together a wide variety of products, such as sensors that indicate temperature, flow, level, or pressure. Some common data acquistion terms are shown below:Data acquisition technology has taken giant leaps forward over the last 30 to 40 years. For example, 40 years ago, in a typical college lab, apparatus for tracking the temperature rise in a crucible of sodiumtungsten- bronze consisted of a thermocouple, a bridge, a lookup table, a pad of paper and a pencil.Today's college students are much more likely to use an automated process and analyze the data on a PC Today, numerous options are available for gathering data. The optimal choice depends on several factors, including the complexity of the task, the speed and accuracy you require, and the documentation you want. Data acquisition systems range from the simple to the complex, with a range of performance and functionality.Pencil and paperThe old pencil and paper approach is still viable for some situations, and it is inexpensive, readily available, quick and easy to get started. All you need to do is hook up a digital multimeter (DMM) and begin recording data by hand. Unfortunately, this method is error-prone, tends to be slow and requires extensive manual analysis. In addition, it works only for a single channel of data; while you can use multiple DMMs, the system will quickly becomes bulky and awkward. Accuracy is dependent on the transcriber's level of fastidiousness and you may need to scaleinput manually. For example, if the DMM is not set up to handle temperature sensors, manual scaling will be required. Taking these limitations into account, this is often an acceptablemethod when you need to perform a quick experiment.Strip chart recorderModern versions of the venerable strip chart recorder allow you to capture data from several inputs. They provide a permanent paper record of the data, and because this data is in graphical format, they allow you to easily spot trends. Once set up, most recorders have sufficient internal intelligence to run unattended — without the aid of either an operator or a computer. Drawbacks include a lack of flexibility and relatively low accuracy, which is often constrained to a few percentage points. You can typically perceive only small changes in the pen plots. While recorders perform well when monitoring a few channels over a long period of time, their value can be limited. For example, they are unable to turn another device on or off. Other concerns include pen and paper maintenance, paper supply and data storage, all of which translate into paper overuse and waste. Still, recorders are fairly easy to set up and operate, and offer a permanent record of the data for quick and simple analysis.Scanning digital multimeterSomebenchtop DMMs offer an optional scanning capability. A slot in the rear of the instrument accepts a scanner card that can multiplex between multiple inputs, with 8 to 10 channels of mux being fairly common. DMM accuracy and the functionality inherent in the instrument's front panel are retained. Flexibility is limited in that it is not possible to expand beyond the number of channels available in the expansion slot. An external PC usually handles data acquisition and analysis.PC plug-in cardsPC plug-in cards are single-board measurement systems that take advantage of the ISA or PCI-bus expansion slots in a PC. They often have reading rates as high as 100,000 readings per second. Counts of 8 to 16 channels are common, and acquired data is stored directly into the computer, where it can then be analyzed. Because the card is essentially part of the computer, it is easy to set up tests. PC cards also arerelatively inexpensive, in part, because they rely on the host PC to provide power, the mechanical enclosure and the user interface.Data acquisition optionsIn the downside, PC plug-in cards often have only 12 bits of resolution, so you can't perceive small variations with the input signal. Furthermore, the electrical environment inside a PC tends to be noisy, with high-speed clocks and bus noise radiated throughout. Often, this electrical interference limits the accuracy of the PC plug-in card to that of a handheld DMM .These cards also measure a fairly limited range of dc voltage. To measure other input signals, such as ac voltage, temperature or resistance, you may need some sort of external signal conditioning. Additional concerns include problematic calibration and overall system cost, especially if you need to purchase additional signal conditioning accessories or a PC to accommodate the cards. Taking that into consideration, PC plug-in cards offer an attractive approach to data acquisition if your requirements fall within the capabilities and limitations of the card.Data loggersData loggers are typically stand-alone instruments that, once they are setup, can measure, record and display data without operator or computer intervention. They can handle multiple inputs, in some instances up to 120 channels. Accuracy rivals that found in standalone bench DMMs, with performance in the 22-bit, 0.004-percent accuracy range. Some data loggers have the ability to scale measurements, check results against user-defined limits, and output signals for control.One advantage of using data loggers is their built-in signal conditioning. Most are able to directly measure a number of different inputs without the need for additional signal conditioning accessories. One channel could be monitoring a thermocouple, another a resistive temperature device (RTD) and still another could be looking at voltage.Thermocouple reference compensation for accurate temperature measurement is typically built into the multiplexer cards. A data logger's built-in intelligence helpsyou set up the test routine and specify the parameters of each channel. Once you have completed the setup, data loggers can run as standalone devices, much like a recorder. They store data locally in internal memory, which can accommodate 50,000 readings or more.PC connectivity makes it easy to transfer data to your computer for in-depth analysis. Most data loggers are designed for flexibility and simple configuration and operation, and many provide the option of remote site operation via battery packs or other methods. Depending on the A/D converter technique used, certain data loggers take readings at a relatively slow rate, especially compared to many PC plug-in cards. Still, reading speeds of 250 readings/second are not uncommon. Keep in mind that many of the phenomena being monitored are physical in nature — such as temperature, pressure and flow — and change at a fairly slow rate. Additionally, because of a data logger's superior measurement accuracy, multiple readings and averaging are not necessary, as they often are in PC plug-in solutions.Data acquisition front endsData acquisition front ends are often modular and are typically connected to a PC or controller. They are used in automated test applications for gathering data and for controlling and routing signals in other parts of the test setup. Front end performance can be very high, with speed and accuracy rivaling the best standalone instruments. Data acquisition front ends are implemented in a number of formats, including VXI versions, such as the Agilent E1419A multifunction measurement and control VXI module, and proprietary card cages.. Although front-end cost has been decreasing, these systems can be fairly expensive, and unless you require the high performance they provide, you may find their price to be prohibitive. On the plus side, they do offer considerable flexibility and measurement capability.Data Logger ApplicationsA good, low-cost data logger with moderate channel count (20 - 60 channels) and a relatively slow scan rate is more than sufficient for many of the applications engineers commonly face. Some key applications include:• Product characterization• Thermal profiling of electronic products• Environmental testing; environmental monitoring• Component characteriza tion• Battery testing• Building and computer room monitoring• Process monitoring, evaluation and troubleshooting No single data acquisition system works for all applications. Answering the following questions may help you decide which will best meet your needs:1. Does the system match my application?What is the measurement resolution, accuracy and noise performance? How fast does it scan? What transducers and measurement functions are supported? Is it upgradeable or expandable to meet future needs? How portable is it? Can it operate as a standalone instrument?2. How much does it cost?Is software included, or is it extra? Does it require signal conditioning add-ons? What is the warranty period? How easy and inexpensive is it to calibrate?3. How easy is it to use?Can the specifications be understood? What is the user interface like? How difficult is it to reconfigure for new applications? Can data be transferred easily to new applications? Which application packages are supported?ConclusionData acquisition can range from pencil, paper and a measuring device, to a highly sophisticated system of hardware instrumentation and software analysis tools. The first step for users contemplating the purchase of a data acquisition device or system is to determine the tasks at hand and the desired output, and then select the type and scope of equipment that meets their criteria. All of the sophisticated equipment and analysis tools that are available are designed to help users understand the phenomena they are monitoring. The tools are merely a means to an end.正确选择数据采集系统工程师经常要对很长时间内的很多信号进行监测、画图和分析产生的数据。
毕业设计(论文)外文资料翻译(学生用)
南京理工大学紫金学院毕业设计(论文)外文资料翻译系：计算机专业：计算机科学与技术姓名：沈俊男学号： 060601239外文出处： E. Jimenez-Ruiz,R. Berlanga. The Management(用外文写)and Integration of Biomedical[M/OL].Castellon：Spanish Ministry of Education andScience project,2004[2005-09098]./ftp/cs/papers/0609/0609144.pdf附件： 1.外文资料翻译译文；2.外文原文。
注：请将该封面与附件装订成册。
附件1：外文资料翻译译文管理和集成的生物医学知识:应用于Health-e-Child项目摘要：这个Health-e-Child项目的目的是为欧洲儿科学发展集成保健平台。
为了实现一个关于儿童健康的综合观点,一个复杂的生物医学数据、信息和知识的整合是必需的。
本体论将用于正式定义这个领域的专业知识，将塑造医学知识管理系统的基础。
文中介绍了一种对生物医学知识的垂直整合的新颖的方法。
该方法将会主要使临床医生中心化，并使定义本体碎片成为可能，连接这些碎片（语义桥接器），丰富了本体碎片（观点）。
这个策略为规格和捕获的碎片，桥接器和观点概述了初步的例子证明从医院数据库、生物医学本体、生物医学公共数据库的生物医学信息的征收。
关键词：垂直的知识集成、近似查询、本体观点、语义桥接器1．1 医学数据集成问题数据来源的集成已经在数据库社区成为传统的研究课题。
一个综合数据库系统主要的目标是允许用户均匀的访问一个分布和一个异构数据库。
数据集成的关键因素是定义一个全局性的模式，但是值得指出的是，我们必须区分三种全局模式：数据库模式、概念模式和域本体模式。
首先介绍了数据类型的信息存储、本地查询；其二，概括了这些图式采用更富有表达力的数据模型，如统一建模语言(UML)（TAMBIS和SEMEDA都遵循这个模式)。
计算机毕业设计外文翻译-- 电路交换网与vb调用数据库
即使美国拥有移动电话的所有权，但是在应用上欧洲要远远超过美国的。原因之一就是整个欧洲拥有相同的简单系统。然而更多的是由于美国和欧洲的基本电话数量不同。在美国移动电话和固定电话是共用的，因此对于用户没有办法区分(212)234-5678到底是固定电话(拨打是便宜的或者是免费的)还是移动电话(拨打是昂贵的)。为了使人们从使用电话中获益，电话公司决定为引入呼叫而花自己的钱制造移动电话。结果导致，很多人怕由于呼叫而收到一大笔帐单而不愿意买移动电话。在欧洲移动电话有特殊的区号(如800,900之类的数字)，所以它很快就得到了认可。因而在一般的“叫方付费”的原则在欧洲也被应用于移动电话了(除国际电话分开收费外)。
毕业设计(论文)外文资料翻译
专业班级：计算机科学与技术
外文来源一：网络文摘<<源码天空>>
外文来源二：
指导教师评语：
签名：
切换电路的连接设置的结果是保留了从发送端到接收端的包所通过的线路带宽。其它的特性这一就是所有的包都沿同一个线路意味着如果包传输超过了时序那它将不能到达接收端.由于没有路径用来进行包交换，所以要想不同的包沿不同的路径传送就是能依靠网络的条件了。这样包即便是超过了时序它们也有可能到达的。
毕业设计英文 翻译(原文)
编号：毕业设计(论文)外文翻译（原文）院（系）：桂林电子科技大学专业：电子信息工程学生姓名： xx学号： xxxxxxxxxxxxx 指导教师单位：桂林电子科技大学姓名： xxxx职称： xx2014年x月xx日Timing on and off power supplyusesThe switching power supply products are widely used in industrial automation and control, military equipment, scientific equipment, LED lighting, industrial equipment,communications equipment,electrical equipment,instrumentation, medical equipment, semiconductor cooling and heating, air purifiers, electronic refrigerator, LCD monitor, LED lighting, communications equipment, audio-visual products, security, computer chassis, digital products and equipment and other fields.IntroductionWith the rapid development of power electronics technology, power electronics equipment and people's work, the relationship of life become increasingly close, and electronic equipment without reliable power, into the 1980s, computer power and the full realization of the switching power supply, the first to complete the computer Power new generation to enter the switching power supply in the 1990s have entered into a variety of electronic, electrical devices, program-controlled switchboards, communications, electronic testing equipment power control equipment, power supply, etc. have been widely used in switching power supply, but also to promote the rapid development of the switching power supply technology .Switching power supply is the use of modern power electronics technology to control the ratio of the switching transistor to turn on and off to maintain a stable output voltage power supply, switching power supply is generally controlled by pulse width modulation (PWM) ICs and switching devices (MOSFET, BJT) composition. Switching power supply and linear power compared to both the cost and growth with the increase of output power, but the two different growth rates. A power point, linear power supply costs, but higher than the switching power supply. With the development of power electronics technology and innovation, making the switching power supply technology to continue to innovate, the turning points of this cost is increasingly move to the low output power side, the switching power supply provides a broad space for development.The direction of its development is the high-frequency switching power supply, high frequency switching power supply miniaturization, and switching power supply into a wider range of application areas, especially in high-tech fields, and promote the miniaturization of high-tech products, light of. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.classificationModern switching power supply, there are two: one is the DC switching power supply; the other is the AC switching power supply. Introduces only DC switching power supply and its function is poor power quality of the original eco-power (coarse) - such as mains power or battery power, converted to meet the equipment requirements of high-quality DC voltage (Varitronix) . The core of the DC switching power supply DC / DC converter. DC switching power supply classification is dependent on the classification of DC / DC converter. In other words, the classification of the classification of the DC switching power supply and DC/DC converter is the classification of essentially the same, the DC / DC converter is basically a classification of the DC switching power supply.DC /DC converter between the input and output electrical isolation can be divided into two categories: one is isolated called isolated DC/DC converter; the other is not isolated as non-isolated DC / DC converter.Isolated DC / DC converter can also be classified by the number of active power devices. The single tube of DC / DC converter Forward (Forward), Feedback (Feedback) two. The double-barreled double-barreled DC/ DC converter Forward (Double Transistor Forward Converter), twin-tube feedback (Double Transistor Feedback Converter), Push-Pull (Push the Pull Converter) and half-bridge (Half-Bridge Converter) four. Four DC / DC converter is the full-bridge DC / DC converter (Full-Bridge Converter).Non-isolated DC / DC converter, according to the number of active power devices can be divided into single-tube, double pipe, and four three categories. Single tube to a total of six of the DC / DC converter, step-down (Buck) DC / DC converter, step-up (Boost) DC / DC converters, DC / DC converter, boost buck (Buck Boost) device of Cuk the DC / DC converter, the Zeta DC / DC converter and SEPIC, the DC / DC converter. DC / DC converters, the Buck and Boost type DC / DC converter is the basic buck-boost of Cuk, Zeta, SEPIC, type DC / DC converter is derived from a single tube in this six. The twin-tube cascaded double-barreled boost (buck-boost) DC / DC converter DC / DC converter. Four DC / DC converter is used, the full-bridge DC / DC converter (Full-Bridge Converter).Isolated DC / DC converter input and output electrical isolation is usually transformer to achieve the function of the transformer has a transformer, so conducive to the expansion of the converter output range of applications, but also easy to achieve different voltage output , or a variety of the same voltage output.Power switch voltage and current rating, the converter's output power is usually proportional to the number of switch. The more the number of switch, the greater the output power of the DC / DC converter, four type than the two output power is twice as large,single-tube output power of only four 1/4.A combination of non-isolated converters and isolated converters can be a single converter does not have their own characteristics. Energy transmission points, one-way transmission and two-way transmission of two DC / DC converter. DC / DC converter with bi-directional transmission function, either side of the transmission power from the power of lateral load power from the load-lateral side of the transmission power.DC / DC converter can be divided into self-excited and separately controlled. With the positive feedback signal converter to switch to self-sustaining periodic switching converter, called self-excited converter, such as the the Luo Yeer (Royer,) converter is a typical push-pull self-oscillating converter. Controlled DC / DC converter switching device control signal is generated by specialized external control circuit.the switching power supply.People in the field of switching power supply technology side of the development of power electronic devices, while the development of the switching inverter technology, the two promote each other to promote the switching power supply annual growth rate of more than two digits toward the light, small, thin, low-noise, high reliability, the direction of development of anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, AC / AC DC / AC, such as inverters, DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardization, and has been recognized by the user, but AC / DC modular, its own characteristics make the modular process, encounter more complex technology and manufacturing process. Hereinafter to illustrate the structure and characteristics of the two types of switching power supply.Self-excited: no external signal source can be self-oscillation, completely self-excited to see it as feedback oscillation circuit of a transformer.Separate excitation: entirely dependent on external sustain oscillations, excited used widely in practical applications. According to the excitation signal structure classification; can be divided into pulse-width-modulated and pulse amplitude modulated two pulse width modulated control the width of the signal is frequency, pulse amplitude modulation control signal amplitude between the same effect are the oscillation frequency to maintain within a certain range to achieve the effect of voltage stability. The winding of the transformer can generally be divided into three types, one group is involved in the oscillation of the primary winding, a group of sustained oscillations in the feedback winding, there is a group of load winding. Such as Shanghai is used in household appliances art technological production of switching power supply, 220V AC bridge rectifier, changing to about 300V DC filter added tothe collector of the switch into the transformer for high frequency oscillation, the feedback winding feedback to the base to maintain the circuit oscillating load winding induction signal, the DC voltage by the rectifier, filter, regulator to provide power to the load. Load winding to provide power at the same time, take up the ability to voltage stability, the principle is the voltage output circuit connected to a voltage sampling device to monitor the output voltage changes, and timely feedback to the oscillator circuit to adjust the oscillation frequency, so as to achieve stable voltage purposes, in order to avoid the interference of the circuit, the feedback voltage back to the oscillator circuit with optocoupler isolation.technology developmentsThe high-frequency switching power supply is the direction of its development, high-frequency switching power supply miniaturization, and switching power supply into the broader field of application, especially in high-tech fields, and promote the development and advancement of the switching power supply, an annual more than two-digit growth rate toward the light, small, thin, low noise, high reliability, the direction of the anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, the DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardized, and has been recognized by the user, but modular AC / DC, because of its own characteristics makes the modular process, encounter more complex technology and manufacturing process. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.The switching power supply applications in power electronic devices as diodes, IGBT and MOSFET.SCR switching power supply input rectifier circuit and soft start circuit, a small amount of applications, the GTR drive difficult, low switching frequency, gradually replace the IGBT and MOSFET.Direction of development of the switching power supply is a high-frequency, high reliability, low power, low noise, jamming and modular. Small, thin, and the key technology is the high frequency switching power supply light, so foreign major switching power supply manufacturers have committed to synchronize the development of new intelligent components, in particular, is to improve the secondary rectifier loss, and the power of iron Oxygen materials to increase scientific and technological innovation in order to improve the magnetic properties of high frequency and large magnetic flux density (Bs), and capacitor miniaturization is a key technology. SMT technology allows the switching power supply has made considerable progress, the arrangement of the components in the circuit board on bothsides, to ensure that the light of the switching power supply, a small, thin. High-frequency switching power supply is bound to the traditional PWM switching technology innovation, realization of ZVS, ZCS soft-switching technology has become the mainstream technology of the switching power supply, and a substantial increase in the efficiency of the switching power supply. Indicators for high reliability, switching power supply manufacturers in the United States by reducing the operating current, reducing the junction temperature and other measures to reduce the stress of the device, greatly improve the reliability of products.Modularity is the overall trend of switching power supply, distributed power systems can be composed of modular power supply, can be designed to N +1 redundant power system, and the parallel capacity expansion. For this shortcoming of the switching power supply running noise, separate the pursuit of high frequency noise will also increase, while the use of part of the resonant converter circuit technology to achieve high frequency, in theory, but also reduce noise, but some The practical application of the resonant converter technology, there are still technical problems, it is still a lot of work in this field, so that the technology to be practical.Power electronics technology innovation, switching power supply industry has broad prospects for development. To accelerate the pace of development of the switching power supply industry in China, it must take the road of technological innovation, out of joint production and research development path with Chinese characteristics and contribute to the rapid development of China's national economy.Developments and trends of the switching power supply1955 U.S. Royer (Roger) invented the self-oscillating push-pull transistor single-transformer DC-DC converter is the beginning of the high-frequency conversion control circuit 1957 check race Jen, Sen, invented a self-oscillating push-pull dual transformers, 1964, U.S. scientists canceled frequency transformer in series the idea of switching power supply, the power supply to the size and weight of the decline in a fundamental way. 1969 increased due to the pressure of the high-power silicon transistor, diode reverse recovery time shortened and other components to improve, and finally made a 25-kHz switching power supply.At present, the switching power supply to the small, lightweight and high efficiency characteristics are widely used in a variety of computer-oriented terminal equipment, communications equipment, etc. Almost all electronic equipment is indispensable for a rapid development of today's electronic information industry power mode. Bipolar transistor made of 100kHz, 500kHz power MOS-FET made, though already the practical switching power supply is currently available on the market, but its frequency to be further improved. Toimprove the switching frequency, it is necessary to reduce the switching losses, and to reduce the switching losses, the need for high-speed switch components. However, the switching speed will be affected by the distribution of the charge stored in the inductance and capacitance, or diode circuit to produce a surge or noise. This will not only affect the surrounding electronic equipment, but also greatly reduce the reliability of the power supply itself. Which, in order to prevent the switching Kai - closed the voltage surge, RC or LC buffers can be used, and the current surge can be caused by the diode stored charge of amorphous and other core made of magnetic buffer . However, the high frequency more than 1MHz, the resonant circuit to make the switch on the voltage or current through the switch was a sine wave, which can reduce switching losses, but also to control the occurrence of surges. This switch is called the resonant switch. Of this switching power supply is active, you can, in theory, because in this way do not need to greatly improve the switching speed of the switching losses reduced to zero, and the noise is expected to become one of the high-frequency switching power supply The main ways. At present, many countries in the world are committed to several trillion Hz converter utility.the principle of IntroductionThe switching power supply of the process is quite easy to understand, linear power supplies, power transistors operating in the linear mode and linear power, the PWM switching power supply to the power transistor turns on and off state, in both states, on the power transistor V - security product is very small (conduction, low voltage, large current; shutdown, voltage, current) V oltammetric product / power device is power semiconductor devices on the loss.Compared with the linear power supply, the PWM switching power supply more efficient process is achieved by "chopping", that is cut into the amplitude of the input DC voltage equal to the input voltage amplitude of the pulse voltage. The pulse duty cycle is adjusted by the switching power supply controller. Once the input voltage is cut into the AC square wave, its amplitude through the transformer to raise or lower. Number of groups of output voltage can be increased by increasing the number of primary and secondary windings of the transformer. After the last AC waveform after the rectifier filter the DC output voltage.The main purpose of the controller is to maintain the stability of the output voltage, the course of their work is very similar to the linear form of the controller. That is the function blocks of the controller, the voltage reference and error amplifier can be designed the same as the linear regulator. Their difference lies in the error amplifier output (error voltage) in the drive before the power tube to go through a voltage / pulse-width conversion unit.Switching power supply There are two main ways of working: Forward transformand boost transformation. Although they are all part of the layout difference is small, but the course of their work vary greatly, have advantages in specific applications.the circuit schematicThe so-called switching power supply, as the name implies, is a door, a door power through a closed power to stop by, then what is the door, the switching power supply using SCR, some switch, these two component performance is similar, are relying on the base switch control pole (SCR), coupled with the pulse signal to complete the on and off, the pulse signal is half attentive to control the pole voltage increases, the switch or transistor conduction, the filter output voltage of 300V, 220V rectifier conduction, transmitted through the switching transformer secondary through the transformer to the voltage increase or decrease for each circuit work. Oscillation pulse of negative semi-attentive to the power regulator, base, or SCR control voltage lower than the original set voltage power regulator cut-off, 300V power is off, switch the transformer secondary no voltage, then each circuit The required operating voltage, depends on this secondary road rectifier filter capacitor discharge to maintain. Repeat the process until the next pulse cycle is a half weeks when the signal arrival. This switch transformer is called the high-frequency transformer, because the operating frequency is higher than the 50HZ low frequency. Then promote the pulse of the switch or SCR, which requires the oscillator circuit, we know, the transistor has a characteristic, is the base-emitter voltage is 0.65-0.7V is the zoom state, 0.7V These are the saturated hydraulic conductivity state-0.1V-0.3V in the oscillatory state, then the operating point after a good tune, to rely on the deep negative feedback to generate a negative pressure, so that the oscillating tube onset, the frequency of the oscillating tube capacitor charging and discharging of the length of time from the base to determine the oscillation frequency of the output pulse amplitude, and vice versa on the small, which determines the size of the output voltage of the power regulator. Transformer secondary output voltage regulator, usually switching transformer, single around a set of coils, the voltage at its upper end, as the reference voltage after the rectifier filter, then through the optocoupler, this benchmark voltage return to the base of the oscillating tube pole to adjust the level of the oscillation frequency, if the transformer secondary voltage is increased, the sampling coil output voltage increases, the positive feedback voltage obtained through the optocoupler is also increased, this voltage is applied oscillating tube base, so that oscillation frequency is reduced, played a stable secondary output voltage stability, too small do not have to go into detail, nor it is necessary to understand the fine, such a high-power voltage transformer by switching transmission, separated and after the class returned by sampling the voltage from the opto-coupler pass separated after class, so before the mains voltage, and after the classseparation, which is called cold plate, it is safe, transformers before power is independent, which is called switching power supply.the DC / DC conversionDC / DC converter is a fixed DC voltage transformation into a variable DC voltage, also known as the DC chopper. There are two ways of working chopper, one Ts constant pulse width modulation mode, change the ton (General), the second is the frequency modulation, the same ton to change the Ts, (easy to produce interference). Circuit by the following categories:Buck circuit - the step-down chopper, the average output voltage U0 is less than the input voltage Ui, the same polarity.Boost Circuit - step-up chopper, the average output voltage switching power supply schematic U0 is greater than the input voltage Ui, the same polarity.Buck-Boost circuit - buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, the inductance transmission.Cuk circuit - a buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, capacitance transmission.The above-mentioned non-isolated circuit, the isolation circuit forward circuits, feedback circuit, the half-bridge circuit, the full bridge circuit, push-pull circuit. Today's soft-switching technology makes a qualitative leap in the DC / DC the U.S. VICOR company design and manufacture a variety of ECI soft-switching DC / DC converter, the maximum output power 300W, 600W, 800W, etc., the corresponding power density (6.2 , 10,17) W/cm3 efficiency (80-90)%. A the Japanese Nemic Lambda latest using soft-switching technology, high frequency switching power supply module RM Series, its switching frequency (200 to 300) kHz, power density has reached 27W/cm3 with synchronous rectifier (MOSFETs instead of Schottky diodes ), so that the whole circuit efficiency by up to 90%.AC / DC conversionAC / DC conversion will transform AC to DC, the power flow can be bi-directional power flow by the power flow to load known as the "rectification", referred to as "active inverter power flow returned by the load power. AC / DC converter input 50/60Hz AC due must be rectified, filtered, so the volume is relatively large filter capacitor is essential, while experiencing safety standards (such as UL, CCEE, etc.) and EMC Directive restrictions (such as IEC, FCC, CSA) in the AC input side must be added to the EMC filter and use meets the safety standards of the components, thus limiting the miniaturization of the volume of AC / DC power, In addition, due to internal frequency, high voltage, current switching, making the problem difficult to solve EMC also high demands on the internal high-density mountingcircuit design, for the same reason, the high voltage, high current switch makes power supply loss increases, limiting the AC / DC converter modular process, and therefore must be used to power system optimal design method to make it work efficiency to reach a certain level of satisfaction.AC / DC conversion circuit wiring can be divided into half-wave circuit, full-wave circuit. Press the power phase can be divided into single-phase three-phase, multiphase. Can be divided into a quadrant, two quadrant, three quadrants, four-quadrant circuit work quadrant.he selection of the switching power supplySwitching power supply input on the anti-jamming performance, compared to its circuit structure characteristics (multi-level series), the input disturbances, such as surge voltage is difficult to pass on the stability of the output voltage of the technical indicators and linear power have greater advantages, the output voltage stability up to (0.5)%. Switching power supply module as an integrated power electronic devices should be selected。
数据库设计外文翻译--Java开发2.0：使用 Hibernate Shards 进行切分
本科生毕业设计（论文）外文资料译文（ 2011 届）译文题目Java开发2.0：使用Hibernate Shards 进行切分外文资料译文规范说明一、译文文本要求1．外文译文不少于2000汉字；2．外文译文本文格式参照论文正文规范（标题、字体、字号、图表、原文信息等）；3．外文原文资料信息列文末，对应于论文正文的参考文献部分，标题用“外文原文资料信息”，内容包括：1）外文原文作者；2）书名或论文题目；3）外文原文来源：□出版社或刊物名称、出版时间或刊号、译文部分所在页码□网页地址二、外文原文资料（电子文本或数字化后的图片）：1．外文原文不少于10000印刷字符（图表等除外）；2．外文原文若是纸质的请数字化（图片）后粘贴于译文后的原文资料处，但装订时请用纸质原文复印件附于译文后。
指导教师意见：指导教师签名：年月日一、外文资料译文：Java开发2.0：使用Hibernate Shards 进行切分横向扩展的关系数据库Andrew Glover，作者兼开发人员，Beacon50摘要：Sharding并不适合所有网站，但它是一种能够满足大数据的需求方法。
对于一些商店来说，切分意味着可以保持一个受信任的 RDBMS，同时不牺牲数据可伸缩性和系统性能。
在Java 开发 2.0系列的这一部分中，您可以了解到切分何时起作用，以及何时不起作用，然后开始着手对一个可以处理数 TB 数据的简单应用程序进行切分。
日期：2010年8月31日级别：中级PDF格式：A4和信（64KB的15页）取得Adobe®Reader®软件当关系数据库试图在一个单一表中存储数TB 的数据时，总体性能通常会降低。
索引所有的数据读取，显然是很耗时的，而且其中有可能是写入，也可能是读出。
因为NoSQL 数据商店尤其适合存储大型数据，但是NoSQL 是一种非关系数据库方法。
对于倾向于使用ACID-ity 和实体结构关系数据库的开发人员及需要这种结构的项目来说，切分是一个令人振奋的选方法。
计算机毕业设计外文翻译---数据仓库
DATA WAREHOUSEData warehousing provides architectures and tools for business executives to systematically organize, understand, and use their data to make strategic decisions. A large number of organizations have found that data warehouse systems are valuable tools in today's competitive, fast evolving world. In the last several years, many firms have spent millions of dollars in building enterprise-wide data warehouses. Many people feel that with competition mounting in every industry, data warehousing is the latest must-have marketing weapon —— a way to keep customers by learning more about their needs.“So", you may ask, full of intrigue, “what exactly is a data warehouse?"Data warehouses have been defined in many ways, making it difficult to formulate a rigorous definition. Loosely speaking, a data warehouse refers to a database that is maintained separately from an organization's operational databases. Data warehouse systems allow for the integration of a variety of application systems. They support information processing by providing a solid platform of consolidated, historical data for analysis.According to W. H. Inmon, a leading architect in the construction of data warehouse systems, “a data warehouse is a subject-oriented, integrated, time-variant, and nonvolatile collection of data in support of management's decision making process." This short, but comprehensive definition presents the major features of a data warehouse. The four keywords, subject-oriented, integrated, time-variant, and nonvolatile, distinguish data warehouses from other data repository systems, such as relational database systems, transaction processing systems, and file systems. Let's take a closer look at each of these key features.(1)Subject-oriented: A data warehouse is organized around major subjects, such as customer, vendor, product, and sales. Rather than concentrating on the day-to-day operations and transaction processing of an organization, a data warehouse focuses on the modeling and analysis of data for decision makers. Hence, data warehouses typically provide a simple and concise view around particular subject issues by excluding data that are not useful in the decision support process.(2)Integrated: A data warehouse is usually constructed by integrating multiple heterogeneous sources, such as relational databases, flat files, and on-line transaction records. Data cleaning and data integration techniques are applied to ensure consistency in naming conventions, encoding structures, attribute measures, and so on..(3)Time-variant: Data are stored to provide information from a historical perspective (e.g., the past 5-10 years). Every key structure in the data warehouse contains, either implicitly or explicitly, an element of time.(4)Nonvolatile: A data warehouse is always a physically separate store of data transformed from the application data found in the operational environment. Due to this separation, a data warehouse does not require transaction processing, recovery, and concurrency control mechanisms. It usually requires only two operations in data accessing: initial loading of data and access of data..In sum, a data warehouse is a semantically consistent data store that serves as a physical implementation of a decision support data model and stores the information on which an enterprise needs to make strategic decisions. A data warehouse is also often viewed as an architecture, constructed by integrating data from multiple heterogeneous sources to support structured and/or ad hoc queries, analytical reporting, and decision making.“OK", you now ask, “what, then, is data warehousing?"Based on the above, we view data warehousing as the process of constructing and using data warehouses. The construction of a data warehouse requires data integration, data cleaning, and data consolidation. The utilization of a data warehouse often necessitates a collection of decision support technologies. This allows “knowledge workers" (e.g., managers, analysts, and executives) to use the warehouse to quickly and conveniently obtain an overview of the data, and to make sound decisionsbased on information in the warehouse. Some authors use the term “data warehousing" to refer only to the process of data warehouse construction, while the term warehouse DBMS is used to refer to the management and utilization of data warehouses. We will not make this distinction here.“How are organizations using the information from data warehouses?" Many organizations are using this information to support business decision making activities, including:(1) increasing customer focus, which includes the analysis of customer buying patterns (such as buying preference, buying time, budget cycles, and appetites for spending).(2) repositioning products and managing product portfolios by comparing the performance of sales by quarter, by year, and by geographic regions, in order to fine-tune production strategies.(3) analyzing operations and looking for sources of profit.(4) managing the customer relationships, making environmental corrections, and managing the cost of corporate assets.Data warehousing is also very useful from the point of view of heterogeneous database integration. Many organizations typically collect diverse kinds of data and maintain large databases from multiple, heterogeneous, autonomous, and distributed information sources. To integrate such data, and provide easy and efficient access to it is highly desirable, yet challenging. Much effort has been spent in the database industry and research community towards achieving this goal.The traditional database approach to heterogeneous database integration is to build wrappers and integrators (or mediators) on top of multiple, heterogeneous databases. A variety of data joiner and data blade products belong to this category. When a query is posed to a client site, a metadata dictionary is used to translate the query into queries appropriate for the individual heterogeneous sites involved. These queries are then mapped and sent to local query processors. The results returned from the different sites are integrated into a global answer set. This query-driven approach requires complex information filtering and integration processes, and competes for resources with processing at local sources. It is inefficient and potentially expensive for frequent queries, especially for queries requiring aggregations.Data warehousing provides an interesting alternative to the traditional approach of heterogeneous database integration described above. Rather than using a query-driven approach, data warehousing employs an update-driven approach in which information from multiple, heterogeneous sources is integrated in advance and stored in a warehouse for direct querying and analysis. Unlike on-line transaction processing databases, data warehouses do not contain the most current information. However, a data warehouse brings high performance to the integrated heterogeneous database system since data are copied, preprocessed, integrated, annotated, summarized, and restructured into one semantic data store. Furthermore, query processing in data warehouses does not interfere with the processing at local sources. Moreover, data warehouses can store and integrate historical information and support complex multidimensional queries. As a result, data warehousing has become very popular in industry.1.Differences between operational database systems and data warehousesSince most people are familiar with commercial relational database systems, it is easy to understand what a data warehouse is by comparing these two kinds of systems.The major task of on-line operational database systems is to perform on-line transaction and query processing. These systems are called on-line transaction processing (OLTP) systems. They cover most of the day-to-day operations of an organization, such as, purchasing, inventory, manufacturing, banking, payroll, registration, and accounting. Data warehouse systems, on the other hand, serve users or “knowledge workers" in the role of data analysis and decision making. Such systems can organize and present data in various formats in order to accommodate the diverse needs of the different users. These systems are known as on-line analytical processing (OLAP) systems.The major distinguishing features between OLTP and OLAP are summarized as follows.(1)Users and system orientation: An OLTP system is customer-oriented and is used for transaction and query processing by clerks, clients, and information technology professionals. An OLAP system is market-oriented and is used for data analysis by knowledge workers, including managers, executives, and analysts.(2)Data contents: An OLTP system manages current data that, typically, are too detailed to be easily used for decision making. An OLAP system manages large amounts of historical data, provides facilities for summarization and aggregation, and stores and manages information at different levels of granularity. These features make the data easier for use in informed decision making.(3)Database design: An OLTP system usually adopts an entity-relationship (ER) data model and an application -oriented database design. An OLAP system typically adopts either a star or snowflake model, and a subject-oriented database design.(4)View: An OLTP system focuses mainly on the current data within an enterprise or department, without referring to historical data or data in different organizations. In contrast, an OLAP system often spans multiple versions of a database schema, due to the evolutionary process of an organization. OLAP systems also deal with information that originates from different organizations, integrating information from many data stores. Because of their huge volume, OLAP data are stored on multiple storage media.(5). Access patterns: The access patterns of an OLTP system consist mainly of short, atomic transactions. Such a system requires concurrency control and recovery mechanisms. However, accesses to OLAP systems are mostly read-only operations (since most data warehouses store historical rather than up-to-date information), although many could be complex queries.Other features which distinguish between OLTP and OLAP systems include database size, frequency of operations, and performance metrics and so on.2.But, why have a separate data warehouse?“Since operational databases store huge amounts of data", you observe, “why not perform on-line analytical processing directly on such databases instead of spending additional time and resources to construct a separate data warehouse?"A major reason for such a separation is to help promote the high performance of both systems. An operational database is designed and tuned from known tasks and workloads, such as indexing and hashing using primary keys, searching for particular records, and optimizing “canned" queries. On the other hand, data warehouse queries are often complex. They involve the computation of large groups of data at summarized levels, and may require the use of special data organization, access, and implementation methods based on multidimensional views. Processing OLAP queries in operational databases would substantially degrade the performance of operational tasks.Moreover, an operational database supports the concurrent processing of several transactions. Concurrency control and recovery mechanisms, such as locking and logging, are required to ensure the consistency and robustness of transactions. An OLAP query often needs read-only access of data records for summarization and aggregation. Concurrency control and recovery mechanisms, if applied for such OLAP operations, may jeopardize the execution of concurrent transactions and thus substantially reduce the throughput of an OLTP system.Finally, the separation of operational databases from data warehouses is based on the different structures, contents, and uses of the data in these two systems. Decision support requires historical data, whereas operational databases do not typically maintain historical data. In this context, the data in operational databases, though abundant, is usually far from complete for decision making. Decision support requires consolidation (such as aggregation and summarization) of data from heterogeneous sources, resulting in high quality, cleansed and integrated data. In contrast, operational databases contain only detailed raw data, such as transactions, which need to be consolidated before analysis. Since the two systems provide quite different functionalities and require different kinds of data, it is necessary to maintain separate databases.数据仓库数据仓库为商务运作提供了组织结构和工具，以便系统地组织、理解和使用数据进行决策。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
附录附录A: 外文资料翻译－原文部分：CUSTOMER TARGETTINGThe earliest determinant of success in the development of a profitable card scheme will lie in the quality of applicants that are attracted by the marketing effort. Not only must there be sufficient creditworthy applicants to avoid fruitless and expensive application processing, but it is critical that the overall mix of new accounts meets the standard necessary to ensure ultimate profitability. For example, the marketing initiatives may attract sufficient volume of applicants that are assessed as above the scorecard cut-off, but the proportion of acceptances in the upper bands may be insufficient to deliver the level of profit and lesser bad debt required to achieve the financial objectives of the scheme.This chapter considers the range of data sources available to support the development of a credit card scheme and the tools that can be applied to maximize the flow of applications from the required categories.Data availabilityThe data that makes up the ingredients from which marketing campaigns can be constructed can come from many diverse sources. Typically, it will fall into four categories:1 the national or regional register of voters;2 the national or regional register of court judgments that records the outcomeof creditor-debtor legislation;3 any national or regional pooled information showing the credit history of clients of the participating lenders; and4 commercially compiled data including and culled from name and address lists, survey results and other market analysis data, e.g. neighborhoods and lifestyle categorization through geo-demographic information systems.The availability and quality of this data will vary from country to country and bureau to bureau.Availability is not only governed by the extent to which the responsible agency has undertaken to record it, but also by the feasibility of accessing the data and the extent (if any) to which local consumer legislation or other considerations (e.g. religious principles) will allow it to be used. Other limitations on the use of available data may lie in the simple impossibility or expense of accessing the information sources, perhaps because necessary consumer consent for divulgence has been withheld or because the records are not yet stored electronically.The local credit information bureaux will be able to provide guidance on all of these matters, as will many local trade or professional associations or the relevant government departments.Data segmentation and AnalysesThe following remarks deal with the ways in which lawfully obtained data may then be processed and analyzed in order to maximize its value as the basis of a marketing prospect list. Examples of the types and uses of data that will play a role in the credit decision area are discussed later in the chapter, within the context of application processing.The key categories into which prospects may be segmented include lifestyle, propensity to purchase specific products (financial or otherwise) and levels of risk. The leading international information bureaux will be able to provide segmentation systems that are able to correlate each of these data categories to provide meaningful prospect lists in rank order. Additionally, many bureaux will have the capability to further enhance the strength and value of the data. Through the selective purchasing of data from bona fide market sources, and by overlaying generic factors deduced from the analysis of the broad mass of industry information that routinely passes through their systems, the best international operators are now able to offer marketing and credit information support that can add significantly to the quality of new applicants.The importance of the role and standard of this data in influencing the quality of the target population for mailings, etc. should not be underestimated. Information that is dated or inaccurate may not only lead a marketer and the organization into embarrassment and damage their reputations, but it will also open the credit card scheme to applicants from outside either the target sector or ,worse still, applicants outside the lender’s view of an acceptable credit risk.From this, it follows that you should seek to use an information bureau whose business principles and operating practices comply with the highest levels of both competence and integrity.Developing the prospect databaseThis is the process by which the raw data streams are brought together and subjected to progressive refinement, with the output representing the refined base from which prospecting can begin in earnest. A wide experience-often across many different markets and countries-in the sourcing, handling and analysis of data inevitably improves the quality of the ideas and systems that a bureau can offer for the development of the prospect database.In summary, the typical shape of the service available from the very best bureaux will support a process that runs as follows:1.collect and consolidate all data to be screened for inclusion;2.merge the various streams;3.sort and classify the data by market and credit categories;4.screen the date using predetermined marketing and credit criteria; and5.consolidate and output the refined list.Bureaux will charge for the use of their expertise and systems.Therefore, consideration should be given to the volumes of data that are to be processed and the costs involved at each stage. The most cost-effective approach to constructing prospect databases only undertakes the lowest-cost screening process within the earlier stages. The more expensive screening processes are not employed until the mass of the data has been reduced by earlier filtering.It is impossible to be prescriptive about the range and levels of service that are available, but reference to one of the major bureaux operating in the region could certainly be a good starting point.Campaign Management and AnalysisAgain, this is an area where excellent support is available from the best-of-breed bureaux. They will provide both the operational support and software capabilities to mount, monitor and analyse your marketing campaign, should you so wish. Their depth of experience and capabilities in the credit sector will often open up income: cost possibilities from the solicitation exercise that would not otherwise be available to the new entrant.The First Important Applications of DBMS’sData items include names and addresses of customers, accounts, loans and their balance, and the connection between customers and their accounts and loans, e.g., who has signature authority over which accounts. Queries for account balances are common, but far more common are modifications representing a single payment from or deposit to an account.As with the airline reservation system, we expect that many tellers and customers (through ATM machines) will be querying and modifying the bank’s data at once. It is vital that simultaneous accesses to an account not cause the effect of an ATM transaction to be lost. Failures cannot be tolerated. For example, once the money has been ejected from an ATM machine ,the bank must record the debit, even if the power immediately fails. On the other hand, it is not permissible for the bank to record the debit and then not deliver the money because the power fails. The proper way to handle this operation is far from obvious and can be regarded as one of the significant achievements in DBMS architecture.Database system changed significantly. Codd proposed that database system should present the user with a view of data organized as tables called relations. Behindthe scenes, there might be a complex data structure that allowed rapid response to a variety of queries. But unlike the user of earlier database systems, the user of a relational system would not be concerned with storage structure. Queries could be expressed in a very high level language, which greatly increased the efficiency of database programmers. Relations are tables. Their columns are headed by attributes.Client –Server ArchitectureMany varieties of modern software use a client-server architecture, in which requests by one process (the client ) are sent to another process (the server) for execution. Database systems are no exception, and it is common to divide the work of the components shown into a server process and one or more client processes.In the simplest client/server architecture, the entire DBMS is a server, except for the query interfaces that the user and send queries or other commands across to the server. For example, relational systems generally use the SQL language for representing requests from the client to the server. The database server then sends the answer, in the form of a table or relation, back to client. The relationship between client and server can get more complex, especially when answers are extremely large. We shall have more to say about this matter in section 1.3.3. there is also a trend to put more work in the client, since the server will be a bottleneck if there are many simultaneous database users.附录B: 外文资料翻译－译文部分：客户目标：最早判断发展可收益卡的成功性是在于受市场影响的被吸引的申请人的质量。