In this paper,after analysing and comparing currently often used security methods such as user identification,access control,software protection and data enciphering,a leveled security model are designed which according to the particular characteristics of MIS to presentively protect directories,program files and database files. In addition,We present some new ideas on ways to secure application system by me ans of passwords,multi-user access management,ways to solve the problem of data collision and deadlock under mult i- user environment and leveled use of database files.
This paper discusses necessity of development of general document database system.It describes basie design thinking,definition of database and its main components.Finally,it details the retrieval function of the system.
In this artical,there is a description that equivalency exists between the indicated content of weighted query expression and that of logical query expression in computer information retrieval,which is or the basis of compairing ,weighted search with logical search and constructing concept of minus weighted valve. And a simple approch to the valid determination of weighted valve is pointed out. Besides,there embarks upon available methods based on sequeutial or reversed-index document query.
The question of solving minimal covers of query lossless join about any normal form has been researched. The algorithims of the verify of query lossless join, the solution of minimal covers of query lossless join based on divided relations and the algorithim of the verify,have been introduced and confirmed.
The paper describes mathematical expression of documentation Languages, discusses mainly mathematical expression of terms Concrete content includes:(1)recall rate,precision rate,omission factor,noise factor,rational reject rate and discrete factor ,(2)Boolean retrieval;(3)related evaluation;(4 )bibliographic information structure,(5)index table structure;(6)coordination indexing;(7)weighted function etc. It has research importance and practical valueto the guantitative analysis for the documentation and information as well as communication and transmission of information, especially to the information retrieval services.
This paper describes the networking CD—ROM technology,then introduces two softwares about networking CD-ROM Opti-Net and SCSI Express.
This article introduce how to search online databases by using of Internet,and tell us the principle,methods,costs of the using Internet ,the methods of connection and Internet information resources.
The paper describes in detail database directory based natwork information resource control mechanisms ,and analyses in particular the multiple database dictionary model and Internet-based Archie and WAIS systems.
This paper introduced a connected installation and application of Internet in Centre of Labour Information & Documentation, than it described an using of E-mail,FTP and Gopher in day today work, at las t it pointed out some weakness in its application.
This paper summarizse the content of the International Seminar on Chinese Document Database,including significance,present situation,networking and sharing,standardization and authority file,advanced technology application,developing and services, countermeasures and suggestion of building Chinese document database.
The library model is an attempt to research the quantitative approach in library management.With the help of LM-1,we can know the dynamic states of the fundamental functions of the library every month,and foretell the changes in the library within two years.
The paper discusses the present condition of the building of MARC database in China, existing problems and their solutions, and the future of development, including the quality of bibliographic data, the normalization of the database,the data coverage,as well as the personal qualities and the investment for building the database.