Control Behaviour of Motorcycle Riders

The control behaviour of motorcycle riders is studied by means of a simulation model for the ridermotorcycle system, which stresses the control actions of the riders. The rider model describes the major steering torque control as well as the rider's own body control actions. This simulation model is applied to a single lane change maneuver and the results of this simulation are compared with the experiments in order to examine its validity.     

An outline of R/V Kairei and recent activity of the multichannel seismic reflection survey system (MCS) and ROV Kaiko

The deep-sea research vessel Kairei was built in 1996 to carry out general deep-sea research, and is now active throughout the world. Kairei is the mother ship for the remotely operated vehicle (ROV) Kaiko, which is also equipped with deep-sea research systems. The role of the Kairei is to conduct detailed research on the tectonics of subduction zones and the sea bed in the deep ocean. A multichannel seismic reflection survey system (MCS) was developed in 1997 to investigate the focal mechanism of the huge earthquakes that occurr in subduction zones around Japan. In 1999, a new system was introduced into the MCS system. It took almost a year to improve the new towing assembly for the air gun array. Kaiko is currently the only ROV that can reach a depth of over 10 000 m. The system's ability was proved in various operating conditions, and Kaiko has continued to make new scientific discoveries. The Kairei's deep-sea observation system has become very powerful and stable. These systems will pursue the challenge to understand the unknown global deep-sea frontier. Received: February 5, 2001 / Accepted: April 26, 2001     

Distribution of drifting seaweeds in eastern East China Sea

In offshore waters with relatively low primary production, drifting seaweeds composed of Sargassum species form an identical ecosystem such as an oasis in desert. Commercially important pelagic fishes such as jack mackerel (Trachurus japonicus) and yellow tail (Seriola quinqueradiata) spawn in East China Sea pass their juvenile period accompanying drifting seaweeds. Therefore drifting seaweeds are very important not only in offshore ecosystem but also fishery resources. However the distribution of drifting seaweeds in East China Sea has scarcely known. Then we conducted two research cruises of R/V Hakuho–Maru in May 2002 and in March 2004. During the cruises, drifting seaweeds were visually observed from the bridge and sampled with a towing net. The observation revealed that the drifting seaweeds were distributed along the front between the Kuroshio Current and coastal waters and mainly composed of one seaweed species, Sargassum horneri (Turner) C. Agardh from spring to early summer. There are no reports on geographical distribution of this species in the coasts south of southern Kyushu Island in Japan. Kuroshio Current flows northeastward there. Buoys with GPS attached to drifting seaweeds released off Zhejiang Province, China, in March 2005 to track their transport. Their positions monitored by ORBCOM satellite showed that they were transported to the area in East China Sea, where the drifting seaweeds were observed during the cruises, in 2 months. These facts suggest that S. horneri detached from Chinese coast in March or months earlier than March could be transported to fringe area of continental shelf and waters influenced by Kuroshio Current from March to May. Therefore the Sargassum forests, especially S. horneri, along the Chinese coast play a very important role in the ecosystem of the East China Sea as a source of drifting seaweeds.