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We developed 6,000 m class cylindrical pressure-tight housings using ceramic cylinders and metal caps. The housings have a simple structure, comprising ceramic cylinders, aluminum alloy caps, and couplings between the ceramic cylinders. They are considerably lighter than metal housings. We applied nonlinear finite element analysis (FEA) to evaluate the stress distribution. Results show no stress exceeding...
For long-term monitoring, the authors are developing a prototype underwater vehicle that can sleep on the seafloor or sleep while drifting underwater. Using these functions, it can carry out long-term monitoring of ocean environments while remaining in a designated area. Recent landing-sleep and drifting-sleep experiments yielded good results. Results of these experiments reported herein demonstrate...
We are now developing a prototype underwater glider for long-term virtual mooring. It can land on the seafloor and remain inactive (sleep) there for a predetermined time to extend its monitoring period. If the seafloor is too deep, then it can sleep while drifting underwater. If it drifts because of the sea current, it will glide back to the designated area and remain there for more than one year...
We have developed a new system for real-time observation of tsunamis and crustal deformation using a seafloor pressure sensor, an array of seafloor transponders and a Precise Point Positioning (PPP ) system on a buoy. The seafloor pressure sensor and the PPP system detect tsunamis, and the pressure sensor and the transponder array measure crustal deformation. The system is designed to be capable of...
We propose a simple design method of a ceramic pressure-tight housing having an extended length of cylinder and metal caps. Ceramics have higher compressive strength and lower specific gravity than typical metals. Moreover, they are free from erosion by seawater. For that reason, we can produce light pressure-tight ceramic housings that have good durability for deep-water applications. The proposed...
We developed a new ocean bottom seismometer (OBS) that can be deployed to the ocean floor to 9,000 m depth. We conducted the first observations using the device. Conducting seismic observations in waters deeper than 6,000 m had been difficult because the maximum applicable depth of conventional ocean bottom seismometers is 6,000 m. The Japan Trench, where the Great East Japan Earthquake occurred,...
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