We propose an algorithm of data compression for the purpose of effective output of multi-dimensional numerical simulation data with a huge number of mesh cells during simulation runs, supposed to use the compressed data including necessary and sufficient information in visualization or analyses after the simulations. This algorithm consists of classification or quantization of single or double precision real data at each mesh point and subsequent compression by using conventional compression algorithm. In the previous paper, we described detailed method of data compression, obtained the compression efficiency for several typical simulations and showed that this method gave good results for those simulations. However, our method was limited to the variables which have positive or negative definite sign such as density. In this paper, we extend this algorithm to all variables which have any signs such as velocity variables. We show that our proposed compression algorithm can attain as high compression efficiencies for the magnetic fields as our previous method. Furthermore we develop another version of our proposed algorithm in which is adopted for the second stage compression method as the next step. We perform test calculations of the compression efficiencies calculated by using this method for the same models as those in the previous paper and show that this compression method is also very useful as well as the previous one.

An effective method for the user account management of the educational computer system is proposed. This method automates the update and the deletion of a user account by using their own application. Transferring a part of the control authority to student's belonging department enables to correspond in the class quickly, and some problems in operation are solved. The details of this method is described in this paper.

A WWW based course registration system has been developed using 3 layered client and server architecture. The system is developed only on free software, has equivalent functionality as the current expensive registration system, and significantly outperforms it even on very cheap server hardware. Software architecture of the prototype system and ideas to improve performance are discussed. Benchmark software has also been developed to evaluate server performance under heavy load by simulating many clients' access, which can be configured and run by only one person.

Accompanied by drastic advance of the recent technology of computer systems and communication networks,services and systems of computer centers of Japanese national universities have been changed. Here, the annual reports of the computer centers in '94- '99 are surveyed to show the changes of organization, services, and computers they provide. The statistical result shows that internet service and computer-network maintenance become one of the important services of computer centers after the computer networks were introduced in '94-'96. Also, personal computers as educational environment are increasing, whereas processing service for entrance examination and students' registration and record has decreased. Concerning research computers, main-frame computers have been replaced by vector processors and parallel computers.