In this article, the state-of-the-art of oversea data communication and China s data communication network are summarized. Also the structure and mode of China s national information service network are analysed and elaborated.

The intellegence-aided book classification tool is a software system used for aiding the book classification work. This software adopts some techniques of the expert system and is implemented on PC 286 and 386. The classification characteristics such as subject headings of the document are used as the initial value for the production system. Some relative classification codes are obtained through the indexed classification knowledge and the classification code set is then clipped according to the classification code from the least classification code set.

An integrated library automation system-SIOCL system is reported. Eight noteworthy problems on the design of ILAS are discussed in detail based on the experience from design of SIOCL system. They are the choice of the type of computer and applied software. the relationship between ILAS and network system, the retrieval efficiency of the system, the relations of ILAS with bibliographic retrieval of secondary literatures, the enhanced circulation control in ILAS, data structure and data sources in ILAS etc.

For the purpose of exploring an effective auxiliary decision method for library automation, the Analytic Hierarchy Process (AHP) is used to optimize the scheme in which an integrated library system can be selected or recommended. The AHP model combined with the evaluation criteria for the integrated library system is Proposed and a quantitative analysis is made for demonstration.

The article describes the meaning of contrast and contrast coefficient, analyses the factors influencing contrast in photograph reproducing, and introduces some ways how to control the contrast of photograph reproduction.