Tohoku University has been constructing the academic information-exchange network TAINS (Tohoku University Academic/All-round/Advanced Information Network System) to link its widely spread campuses and to meet several demands for an intrauniversity network. TAINS, the first network based on OSI, became operational in April 1988. The primary function of TAINS is to connect all the geographically dispersed locations of the university via a high-speed digital network in order to facilitate an easy and efficient interconnection among the various computers, terminals and other scientific equipment. TAINS is constructed as a large-scale local area network of hierarchical structure. In the hierarchical network of TAINS, a backbone network, consisting of two 100 Mbps optical fiber rings, interconnects several small-scale IEEE802.3 networks, each of which span a building or a part of a building. This paper describes the background, the basic design concept and the constitution of TAINS. In TAINS, the inhouse network protocol is OSI-based, and the ring network protocol is based on FDDI. The use of these communication protocols are reviewed and the protocol matching adopted for TAINS is described. Finally, a method for estimating the stable operation of a 2-layer hierarchical network using traffic analysis is given.

In this paper, an adaptive method for active control of vibration intensity in the frequency domain is proposed. In this method, vibration intensity is observed with the 4-sensor method, and the coefficients of an adaptive FIR filter for the active control is renewed with the Block Filtered-X LMS algorithm in the frequency domain. An experiment with the proposed method is performed on a simple model. As a result, the proposed method gives larger attenuation of vibration intensity than the conventional method in the high frequency region. The overall attenuation in vibration intensity in that frequency region is 14.1 dB with the proposed method, while it is 7.0 dB with the conventional method. In the lower frequency region, the reduction in vibration intensity by the proposed method is roughly equivalent to that obtained by the conventional method. An improvement may also be achieved there by setting the intervals between error sensors properly.