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Hada A.,Telecommunications and Networking Laboratory | Tsuchiya R.,Telecommunications and Networking Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2012

This paper studies effective algorithms for designing wireless sensor networks to be used for health monitoring of railway structures. The first step reviewed optimization problems arising in railway system and highlighted the importance of maximizing the network lifetime in a poor communication environment and minimizing the total cost of the wireless sensor network in a general communication environment. Basic ideas for a life span algorithm for the network lifetime maximization problem and a Lagrangian heuristic algorithm for the total cost minimization problem are introduced in this paper. Finally these algorithms were verified with randomly generated data for the former problem and data acquired from a real WSN used for railway structural health monitoring for the latter problem. Source

Takeuchi K.,Telecommunications and Networking Laboratory | Nakamura K.,Telecommunications and Networking Laboratory | Kawasaki K.,Telecommunications and Networking Laboratory | Yamaguchi D.,Telecommunications and Networking Laboratory | Kawamura Y.,Telecommunications and Networking Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2013

High speed data transmission systems using metallic telecommunication lines such as xDSL (Digital Subscriber Line) are being introduced into railway systems as a substitute to analog systems where adoption of optical carrier is not cost effective and to supplement optical carrier systems between a station with optical terminal equipment, and a station without optical terminal equipment. Research carried out so far has produced a method for assessing the suitability of coupling high speed data transmission systems for railways with normalstate telecommunication lines. This study proposes an improved evaluation method, which considers the influence of the line disturbances on the electrical characteristics of telecommunication lines, and delay time and jitter when transmission systems are connected in tandem. Source

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