毕业设计(论文)外文翻译(原文)

1、毕业设计（论文）外文翻译（原文）new application of databaserelational databases have been in use for over two decades. a large portion of the applications of relational databases have been in the commercial world, supporting such tasks as transaction processing for banks and stock exchanges, sales and reservations

2、for a variety of businesses, and inventory and payroll for almost of all companies we study several new applications, which have become increasingly important in recent years.first decision-support systemas the online availability of data has grown, businesses have begun to exploit the available dat

3、a to make better decisions about increase sales we can extract much information for decision support by using simple sql queries recently however, people have felt the need for better decision support based on data analysis and data mining, or knowledge discovery, using data from a variety of source

4、sdatabase applications can be broadly classified into transaction processing and decision support. transaction-processing systems are widely used today, and companies have accumulated a vast amount of information generated by these systems.the term data mining refers loosely to finding relevant info

5、rmation, or "discovering knowledge/5 from a large volume of data like knowledge discovery in artificial intelligence, data mining attempts to discover statistical rules and patterns automatically from data. however, data mining differs from machine learning in that it deals with large volumes o

6、f data, stored primarily on disk.knowledge discovered from a database can be represented by a set of rules we can discover rules from database using one of two models:in the first model, the user is involved directly in the process of knowledge discovery.in the second model, the system is responsibl

7、e for automatically discovering knowledge from the database, by detecting patterns and correlations in the data.work on automatic discovery of mles has been influenced strongly by work in the artificial-intelligence community on machine learning. the main differences lie in the volume of data handle

8、d in databases, and in the need to access disk. specialized data-mining algorithms have been developed to handle large volumes of disk-resident data efficientlythe manner in which rules are discovered depends on the class of data-mining application we illustrate rule discovery using two application

9、classes: classification and associations.second- spatial and geographic databasesspatial databases store information related to spatial locations, and provide support for efficient querying and indexing based on spatial locations. two types of spatial databases arc particularly important:design data

10、bases, or computer-aided-design (cad) databases, are spatial databases used to store design information about how objectssuch as buildings, cars or aircraft一are constructed. other important examples of computer-aided-design databases are integrated-circuit and electronic-device layouts.geographic da

11、tabases are spatial databases used to store geographic information, such as maps. geographic databases are often called geographic information systems.geographic data are spatial in nature, but differ from design data in certain ways. maps and satellite images are typical examples of geographic data

12、 maps may provide not only location information -such as boundaries, rivers and roadsbut also much more detailed information associated with locations, such as elevation, soil type, land usage, and annual rainfall.geographic data can be categorized into two types: raster data (such data consist a bi

13、t maps or pixel maps, in two or more dimensions.), vector data (vector data are constructed from basic geographic objects). map data are often represented in vector formatthird. multimedia databasesrecently, there has been much interest in databases that store multimedia data, such as images, audio,

14、 and video. today multimedia data typically are stored outside the database, in files systems. when the number of multimedia objects is relatively small, features provided by databases are usually not important. database functionality becomes important when the number of multimedia objects stored is

15、 large issues such as transactional updates, querying facilities, and indexing then become important. multimedia objects often have descriptive attributes, such as those indicating when they were created, who created them, and to what category they belong one approach to building a database for such

16、 multimedia objects is to use database for storing the descriptive attributes, and for keeping track of the files in which the multimedia objects are stored.however, storing multimedia outside the database makes it harder to provide database functionality, such as indexing on the basis of actual mul

17、timedia data content. it can also lead to inconsistencies, such a file that is noted in the database, but whose contents are missing, or vice versa. it is therefore desirable to store the data themselves in the databaseforth. mobility and personal databaseslarge-scale commercial databases have tradi

18、tionally been stored in central computing facilities. in the case of distributed database applications, there has usually been strong central database and network administration. two technology trends have combined to create applications in which this assumption of central control and administration

19、 is not entirely correct:1 .the increasingly widespread use of personal computers, and, more important, of laptop or "notebook computers2. thc development of a relatively low-cost wireless digital communication infrastructure, base on wireless local-area networks, cellular digital packet networ

20、ks, and other technologies.wireless computing creates a situation where machines no longer have fixed locations and network addresses. this complicates query processing, since it becomes difficult to determine the optimal location at which to materialize the result of a query in some cases, the loca

21、tion of the user is a parameter of the query a example is a traveler's information system that provides data on hotels, roadside services, and the like to motorists. queries about services that are ahead on the current route must be processed based on knowledge of the user's location, direct

22、ion of motion, and speedenergy (battery power) is a scarce resource for mobile computers. this limitation influences many aspects of system design. among the more interesting consequences of the need for energy efficiency is the use of scheduled data broadcasts to reduce the need for mobile system t

23、o transmit queries. increasingly amounts of data may reside on machines administered by users, rather than by database administrators furthermore, these machines may, at times, be disconnected from the network.summarydecision-support systems arc gaining importance, as companies realize the value of

24、the on-line data collected by their on-line transaction-processing systems. proposed extensions to sql, such as the cube operation, help to support generation of summary data. data mining seeks to discover knowledge automatically, in the form of statistical rules and patterns from large databases. d

25、ata visualization systems help humans to discover such knowledge visually.spatial databases are finding increasing use today to store computer-aided design data as well as geographic data. design data are stored primarily as vector data; geographic data consist of a combination of vector and raster

26、datamultimedia databases are growing in importance issues such as similarity-based retrieval and delivery of data at guaranteed rates arc topics of current research.mobile computing systems have become common, leading to interest in database systems that can run on such systems. query processing in

27、such systems may involve lookups on server database毕业设计（论文）外文翻译（译文）数据库的新应用我们使用关系数据库已经有20多年了，关系数据库应用屮有很人一部分都用于商业领域支 持诸如银行和证券交易所的事务处理、各种业务的销伟和预约，以及几乎所有公司都需要的财产 目录和工资单管理。下面我们要研究几个新的应用，近年来它们变得越来越重要。1、决策支持系统由于越来越多的数据可联机获得，企业已开始利用这些可获得的数据来对a己的行动做出更 好的决策，比如进什么货，以及如何最好的吸引顾客以提高销伟额。我们可以通过使用简单的sql 查询语句提供大量用于决策

28、支持的信息。但是，人们最近感到需要使用多种数据源的数据，以便 在数据分析和数据挖掘（或知识发现）的基础上，更好的來做决策支持。数据库应用从广义上可分为事务处理和决策支持两类。事务处理系统现在正被广泛使用，并 且公司已经积累了大量由这类系统产生的信息。数据挖掘这个概念广义上讲是指从人最数据中发现有关信息，或“发现知识”。与人t智能 屮的知识发现类似，数据挖掘试图白动从数据屮发现统计规则和模式。但是，数据挖掘和机器学 习的不同在于它处理的是大量数据，它们主要存储在磁盘上。从数据库中发现的知识可以用一个规则集表示。我们用如下两个模型之一从数据库中发现规 则：在第一个模型中，用户直接参与知识发现的过程

29、在第二个模型屮，系统通过检测数据的模式和相互关系，白动从数据库屮发现知识。有关自动发现规则的研究很大程度上是受人工智能领域在知识学习方血研究的影响。其主要 的区别在于数据库中处理的数据量，以及是否需要访问磁盘。已经有一些貝体的数据挖掘算法用 于高效地处理放在磁盘上的大量数据。规则发现的方式依赖于数据挖掘应用的类型。我们用两类应用阐述规则发现：分类和关联。2、空间和地理数据库空间数据库存储有关空间位置的信息，并且对高效查询和基于空间位置的索引提供支持。有 两种空间数据库特别重要：设计数据库或计算机辅助设计（cad）数据库是用于存储设计信息的空间数据库，这些 信息主要是关于物体（如建筑、汽车或是飞

30、机）是如何构造的。另一个计算机辅助设计 数据库的重要例子是整合电路和电子设备设计图。地理数据库是用于存储地理信息（如地图）的空间数据库。地理数据库常称为地理信息 系统。地理数据本质上是空间的，但与设计数据相比在儿个方面有所不同。地图和卫星图像是地理 数据的典型例子。地图不仅可提供位置信息，如边界、河流和道路，而且还可以提供许多和位置 相关的详细信息，如海拔、十-壤类型、土地使用和年降用量。地理数据可以分为两类：光栅数据 （这种数据由二维或更高维的位图或像素图组成）、矢最数据（由基木几何对象构成）。地图数据 常以矢量形式表示。3、多媒体数据库最近，冇关多媒体数据（如图像、声咅和视频）的数据库的研究很热门。现在多媒体数据通 常存储在数据库以外的文件系统中。当多媒体对彖的数冃相对较少时，数据库提供的特点往往不 那么重要。但是当存储的多媒体对彖数冃较多时，数据库的功能就变得重要起來。总z,事务更 新