第十二章 计算机

∙Data (340)o Facts or observations about people, places, things, and events.o Types of data▪Numbers, letters, and symbols recorded by keyboards.▪Audio captured, interpreted, and saved using microphones and voicerecognition systems▪Music captured from the Internet, from MIDI devices, and from other sources.▪Photographs captured by digital cameras, and edited by image editing software.▪Video captured by digital video cameras, TV tuner cards, and WebCams.o Physical view focuses on the actual format and location of the datao Logical view, focuses on the meaning and content of the data.∙Data Organization (340)o Character- the most basic logical data element.o Field - group of related characters.o Record - a collection of related fields.o File- a collection of related records.o Database- an integrated collection of logically related records or objects.o Key Field (341)▪Each record in a database has at least one distinctive field▪This field uniquely identifies the record.▪Key fields in different files can be used to integrate the data in a database.o Batch vs. Real-time processing▪Batch∙Data is collected over several hours, days, or even weeks, thenprocessed all at once▪Real-time∙Also known as online processing∙Occurs when data is processed at the same time the transactionoccurs.∙Database (343)o Many organizations have multiple files on the same subject or person.o Data spread around in different files is not as useful.o Need for databases▪Sharing- information from one department can be readily shared with others.▪Security - Users are given passwords or access only to the kind ofinformation they need.▪Less data redundancy - having access to one file, there are fewer files.Thus, storage is reduced.▪Data integrity - a change made to a file by one department will be seen by other departments. Accuracy is improved.o Database Management (344)▪Allows users to create, modify, and gain access to a database, specialsoftware is required.▪The DBMS engine provides a bridge between the logical view of the data and the physical view of the data.▪The data definition subsystem defines the logical structure of the database by using a data dictionary.▪The data manipulation subsystem provides tools for maintaining andanalyzing data.▪The application generation subsystem provides tools to create data entry forms and specialized programming languages that interface or work withcommon and widely used programming languages.▪The data administration subsystem helps to manage the overall database, including maintaining security, providing disaster recovery support, andmonitoring the overall performance of database operations.DBMS Structure (346)o DBMS programs are designed to work with data that is logically structured or arranged in a particular way.o Hierarchical database▪Fields or records are structured in nodes.▪Each entry has one parent node,▪ A parent may have several child nodes - a one-to-many relationship.▪To find a particular field you have to start at the top with a parent and trace down the tree to a child.▪If one parent node is deleted, so are all the subordinate child nodes.o Network database (347)▪Each child node may have more than one parent node.▪ A many-to-many relationship.▪Additional connections—called pointers—between parent nodes andchild nodes.▪ A node may be reached through more than one path.o Relational database▪There are no access paths down a hierarchy.▪The data elements are stored in different tables, each of which consists of rows and columns.▪Related tables must have a common data item (key field).▪Information stored on one table can be linked with information stored on another▪Entries can be easily added, deleted, and modified.o Multidimensional database (348)▪ A variation and an extension of the relational data model▪Extend this two-dimensional data model to include additional or multiple dimensions sometimes called a hyper cube.▪Each side of the cube is considered a dimension of the data.▪Conceptualization - Multidimensional databases and hyper cubesprovide users with an intuitive model in which complex data andrelationships can be conceptualized.▪Processing speed - Analyzing and querying a large multidimensional database is much faster.o Object-oriented database (349)▪More flexible, store data as well as instructions to manipulate the data, and are able to handle unstructured data such as photographs, audio, andvideo.∙Objects are items that contain both data and instructions tomanipulate the data.∙Classes are similar objects grouped together.∙Entities are a person, place, thing, or event that is to be described.∙Attributes are the description of entities. They are similar tofields.∙Methods are descriptions of how the data is to be manipulated.∙Types of Databases (350)o Individual - a collection of integrated files primarily used by just one person.o Company (shared) - stored on a mainframe and managed by a database administrator.▪Common operational database - contains data describing the day-to-day operations of the organization▪Common user database - contains selected information both from the common operational database and from outside private (proprietary)databases.o Distributed (351) - located in a place or places other than where users are located.o Proprietary –▪Generally an enormous database that an organization develops to cover particular subjects.▪Offers access to this database to the public or selected outside individuals for a fee.▪Some important proprietary databases:∙CSi: Offers consumer and business services, including electronicmail.∙Dialog Information Services: Offers business information, as wellas technical and scientific information.∙Dow Jones Interactive Publishing: Provides world news andinformation on business, investments, and stocks.∙LexisNexis: Offers news and information on legal, public records,and business issues.o Web - similar to the other types of databases, but it is available over the Web.∙Database Uses and Issues (352)o Strategic uses▪Business directories - provide addresses, financial and marketinginformation, products, and trade and brand names.▪Demographic data - county and city statistics, current estimates onpopulation and income, employment statistics, and census data.▪Business statistical information - financial information on publiclytraded companies, market potential of certain retail stores, and otherbusiness data and information.▪Text databases - provide articles from business publications, pressreleases, reviews on companies and products.▪Web databases - cover a wide range of topics; Web search sites likeYahoo! maintain extensive databases of available Web sites.o Security (353)▪Personal and private information about people stored in databases may be used for the wrong purposes.▪Unauthorized users gaining access to a database∙Careers in IT (353)o Database administrators - use database management software to determine the most eff icient ways to organize and access a company’s data.o Typically responsible for maintaining database security and backing up the system.o Normally require a bachelor’s degree in computer science and technical experience.o possible too Transfer skills learned in one industry to a new career in database administration.o Annual salary of $44,000 to $81,000.∙ A Look to the Future (354)o Accessing information from many databases using one interface.o Xperanto is designed to make both structured (relational databases) and unstructured data (word processing or spreadsheet files, for example) searchablein a database.o Could be used to examine audio transcripts of phone calls.o ano Organization can access to all of its files, on all computers, and in all locations through a database.o Relies heavily on XML.∙Data (340)o Emphasize how databases have changed significantly in the last decade or so due to the type of data that is being captured.o Types of data▪Numbers, letters, and symbols recorded by keyboards.▪Audio captured, interpreted, and saved using microphones and voicerecognition systems▪Music captured from the Internet, from MIDI devices, and from othersources.▪Photographs captured by digital cameras, and edited by image editingsoftware.▪Video captured by digital video cameras, TV tuner cards, and WebCams. ∙Data Organization (340)o Emphasize the different elements of a database and why a key field is an important aspect of it. You can use examples of a registrar’s database and how itcan be used to keep track of studentso Batch vs. Real-time processing - You can use Expanding Your Knowledge exercise #1 has a lab or assignment to help explore and research the differencebetween types of processing.∙Database (343)o You can emphasize the different needs for databases and the need for information by organizations.o Need for databases▪Sharing- information from one department can be readily shared with others.▪Security - Users are given passwords or access only to the kind ofinformation they need.▪Less data redundancy - having access to one file, there are fewer files.Thus, storage is reduced.▪Data integrity - a change made to a file by one department will be seen by other departments. Accuracy is improved.o Database Management (344)▪You can have the students discuss the different aspects of databases and relate it to large amount of information. You use a small DBMS, such asAccess, to help illustrate different points.∙DBMS Structure (346)o You can briefly discuss, at most, the hierarchical and network databases, since that are not used much, if at all, anymore.o You can emphasize the relational database concept and you can use Access to help with this illustration by setting up a database with a couple of tables.o Emphasize the differences of multidimensional and object-oriented databases and where they can be used.∙Types of Databases (350)o You can utilize the Applying Technology exercises; Free Database Software, Internet Movie Database, and Online databases; as well as, Expanding YourKnowledge exercise, DVD Direct Databases, to help illustrate the different typesof databases that are available today.o You can use these exercises in conjunction with a lab to have the students explore the different possibilities available for data repositories.Database Uses and Issues (352)o Strategic uses▪You can combine the strategic uses when discussing the types ofdatabases.▪You can expound on the exercise to have the student include different types of strategic uses for the different types of databases discussed.o Security (353)▪You can emphasize the different security issues and use the WritingAbout Technology exercise, Database Security, to promote discussions onthe issues.Key TermsCrossword Puzzle Answers:Open Ended Questions:1.Describe the five logical data groups or categories.a.Numbers, letters, and symbolsb.Audioc.Musicd.Photographse.Video2.What is the difference betw een batch processing and real-time processing?a.Batchi.Data is collected over several hours, days, or even weeks, then processedall at onceb.Real-timei.Also known as online processingii.Occurs when data is processed at the same time the transaction occurs..3.Identify and define the five parts of DBMS programs.a.Allows users to create, modify, and gain access to a database, special software isrequired.b.Provides a bridge between the logical view of the data and the physical view ofthe data.c.The data definition subsystem defines the logical structure of the database byusing a data dictionary.d.The data manipulation subsystem provides tools for maintaining and analyzingdata.e.Provides tools to create data entry forms and specialized programming languagesthat interface or work with common and widely used programming languages4.What are the five types of databases? Why does more than one kind of database exist?a.Hierarchical databasework databasec.Relational databased.Multidimensional databasee.Object-oriented databasef.More than one exists because they are designed to work with data that is logicallystructured or arranged in a particular way, and they define rules and standards forall the data in a database.5.What are some of the benefits and limitations of databases? Why is security a concern?Sharing- information from one department can be readily shared with others.Security - Users are given passwords or access only to the kind of informationthey need.Less data redundancy - having access to one file, there are fewer files. Thus,storage is reduced.Data integrity - a change made to a file by one department will be seen byother departments. Accuracy is improved.Security is an issue because personal and private information about people stored in databases may be used for the wrong purposes, and unauthorized users can gain access to a database.1.Writing About Technology exercise #1 Personal Information has the students explore theethical issues of personal information databases and how it relates to personal privacyissues.Web Tools1.Applying Technology exercise #2 Internet Movie Database explores the uses andtechnologies used with this type of database.2.Applying Technology exercise #3 Online Databases has the students research fivedifferent online database and critique each site according to relevancy of data found.3.Expanding Your Knowledge exercise #1 DVD Direct Databases has the student research,diagram, and compare using real-time and batch processing with a DVD direct database. Software Tools1.Applying Technology exercise #1 Free Database Software has the students explore thefree database software, MySql, and how it could be employed in an IT environment.2.Expanding Your Knowledge exercise #2 SQL explores the features and functions of SQLand how it can be used as in a IT solution.Writing Skills1.Writing About Technology exercise #2 Database Security explores the different type ofsecurity issues that a database administrator faces.。

大学计算机基础(科学版)电子教案第一章：计算机概述1.1 计算机的发展史1.2 计算机的分类与特点1.3 计算机硬件系统1.4 计算机软件系统第二章：操作系统2.1 操作系统概述2.2 Windows操作系统2.3 Linux操作系统2.4 操作系统的基本操作第三章：计算机网络3.1 计算机网络概述3.2 网络协议与网络结构3.3 Internet的基本应用3.4 网络安全与防护第四章：程序设计基础4.1 程序设计概述4.2 算法与数据结构4.3 常见编程语言及其特点4.4 编程实践第五章：数据库系统5.1 数据库概述5.2 关系型数据库5.3 SQL语言5.4 数据库应用实例第六章：计算机组成原理6.1 计算机体系结构6.2 中央处理器（CPU）6.3 存储器层次结构6.4 输入输出系统第七章：计算机图形学7.1 计算机图形学概述7.2 图形表示与变换7.3 图形绘制算法7.4 计算机动画与虚拟现实第八章：算法设计与分析8.1 算法概述8.2 算法设计方法8.3 算法分析与评价8.4 常用算法及其实现第九章：软件工程9.1 软件工程概述9.2 软件开发过程与管理9.3 软件设计与测试9.4 软件项目管理第十章：计算机应用领域10.1 计算机在科学研究中的应用10.2 计算机在工程设计中的应用10.3 计算机在医学领域的应用10.4 计算机在教育与娱乐领域的应用第十一章：计算机编程语言11.1 编程语言概述11.2 高级编程语言的特点与分类11.3 面向对象编程11.4 编程语言的选择与使用第十二章：软件工具与开发环境12.1 软件工具的分类与作用12.2 集成开发环境（IDE）12.3 版本控制系统12.4 软件开发辅助工具的使用第十三章：数据库管理系统13.1 数据库管理系统概述13.2 关系型数据库的创建与管理13.3 数据库查询语言SQL13.4 数据库设计与管理第十四章：大数据与数据挖掘14.1 大数据概述14.2 数据挖掘技术14.3 常用大数据处理工具与技术14.4 大数据应用案例分析第十五章：网络安全与信息安全15.1 网络安全概述15.2 计算机病毒与恶意软件15.3 数据加密与安全协议15.4 信息安全策略与实践重点和难点解析本教案涵盖了计算机科学的基础知识，重点和难点如下：第一章至第五章主要介绍了计算机的基本概念、操作系统、计算机网络、程序设计基础和数据库系统。

计算机及其网络保密管理规定计算机及其网络保密管理规定为了保护计算机和网络安全，维护国家利益和公共利益，加强对计算机及其网络的保密管理，依据《中华人民共和国保密法》和《中华人民共和国计算机信息系统安全保护条例》等相关法律法规，制定本规定。

第一章总则第一条为了规范计算机及其网络保密管理，维护国家信息安全和社会稳定，本规定适用于计算机及其网络保密管理工作。

第二条计算机及其网络保密管理应遵循“安全第一，预防为主，综合治理”的原则，坚持防范和解决问题相结合，全面加强计算机及其网络保密管理。

第三条计算机及其网络保密管理是指依法制定、实施和监督保护计算机及其网络安全，保障信息的机密性、完整性和可用性的措施和活动。

第四条计算机及其网络是指通过计算机及其网络进行信息处理、存储、传输、交换和使用的技术和装备。

第五条本规定所称计算机及其网络保密是指依法对计算机及其网络的信息进行保密。

第六条计算机及其网络保密管理部门应当履行保密职责，依法开展计算机及其网络保密管理工作，保障国家机密、商业秘密、个人隐私和其他重要信息的安全。

第二章计算机及其网络保密工作机制第七条计算机及其网络保密工作应当按照属地管理、分级保密、责任制等原则，建立健全计算机及其网络保密工作机制。

第八条计算机及其网络保密责任制是指各级保密责任人应当对保密工作负总责、分管责任、实施责任、考核责任，做到属地负责、部门负责、个人负责。

第九条各级保密机构应当建立健全计算机及其网络保密工作体系，制定计算机及其网络保密管理制度和规程，推动保密工作的开展，协调解决计算机及其网络保密工作中的问题。

第十条计算机及其网络保密工作应当与信息化建设同步推进，发挥科技和人才优势，加强信息安全防护和应急响应工作，做到安全运营、实时监控、快速响应。

第十一条实施计算机及其网络保密工作，应当遵守法律法规和保密制度，严格执行保密审批和管理程序，切实防范计算机病毒、木马、黑客和网络攻击等安全威胁。

计算机控制系统(期末复习资料)⏹ 第一章 绪论1、计算机控制系统的组成：由计算机（工业控制计算机）和工业对象（被控对象）组成。

2、计算机控制过程的3个步骤：实时数据采集；实时决策；实时控制。

3、过程输入输出通道：计算机和被控对象（或生产过程）之间设置的信息传递和转换的连接通道。

4、采样过程：在计算机控制系统中，信号是以脉冲序列或数字序列的方式传递的，把连续信号变成数字序列的过程；采样开关：实现采样的装置。

5、控制系统的稳态控制精度由A/D 、D/A 转换器的分辨率决定。

6、计算机控制系统是利用离散的信号进行控制运算。

7、香农采样定理：一个连续时间信号f(t)，设其频带宽度是有限的，其最高频率为ωmax(或fmax)，如果在等间隔点上对该信号f(t)进行连续采样，为了使采样后的离散信号f *(t)能包含原信号f(t)的全部信息量。

则采样角频率只有满足下面的关系：ωs ≥2ωmax8、采样保持器：将数字信号序列恢复成连续信号的装置。

9、零阶保持器所得到的信号是阶梯信号，它只能近似地恢复连续信号。

⏹ 第二章 Z 变换及Z 传递函数1、计算机控制系统属于闭环离散控制系统，它的输出量与输入量之间的关系可用差分方程来描述。

2、部分分式法3、常用信号的Z 变换单位脉冲信号： 单位阶跃信号： 单位速度信号： 指数信号：正弦信号： 4、常用Z 变换表5、连续系统是用微分方程描述的，离散系统是用差分方程描述的，差分方程是离散系统时域分析的基础，而计算机系统的本质是离散系统。

6、Z 传递函数：在零初始条件下离散系统的输出与输入序列的Z 变换之比。

)()(t t f δ=)(1)(t t f =tt f =)(at e t f -=)(t t f ωsin )(=7、Z 传递函数的物理可实现性：k 时刻的输出y(k)不依赖于k 时刻之后的输入，只取决于k 时刻及k 时刻之前的输入和k 时刻之前 的输出。

故G(z)是物理可实现的。