Marine Ecosystems Research Department - jamstec japan agency ...

Japan Marine Science and Technology Center
Marine Technology Department
hydride at low pressure. Figure shows the general layout
of AUV after the modification. After fiscal , we
plan to conduct sea trials with a target cruising distance
of km.
(4) Ocean energy utilization technologies
From Fiscal
As general awareness about global environmental
problems continues to rise, the use of clean inexhaustible
natural energy is again taken interest. In this
R&D project, we are focusing on wave energy in
coastal waters as natural energy from the ocean, and
have been carrying out R&D on the "Mighty Whale"
offshore floating wave power device since fiscal .
The Mighty Whale system efficiently absorbs wave
energy for effective use in coastal regions, and creates
calm waters behind the devices, enabling those areas to
be used for fishery and other marine activities. At the
end of March we completed an open sea test of a
Mighty Whale prototype (length m, width m) in
the mouth of Gokasho Bay, Nansei-cho, Watarai-gun
in Mie Prefecture. Following the completion of the
test, in June and July the floatation section was
removed from the test area and dismantled. In parallel
with the removing works, we carried out free oscillation
tests under actual sea conditions to confirm
motion characteristics of the prototype, and various
tests on structural material and component equipment
to check for durability through the test period. Along
with these works and tests, we are also analyzing and
organizing the test data gathered to date, and have
begun compiling the test results into a database.
The free oscillation test is aimed at accurately determining
the natural period including the mooring system
necessary for understanding the motion characteristics
of moored floats; there have been very few free oscillation
tests in the actual sea of large-scale moored floating
bodies such as "Mighty Whale". As shown in Figure ,
for the test we forcibly dragged the moored Mighty
Whale using a tugboat, then released it and took a timeseries
measurement of the float position. We then
(Rear)
Movement distance;
About 10m; About 10m
converted the measured positional data to movement
with six degrees of freedom around the float center of
gravity, and calculated the natural period and damping
coefficient from the time-series data.
For the future, we are planning to integrate the results
of the sea test and various other incidental tests and build
a design system for the floating wave power device.
2. Research Project ; Category 2
(1) Technologies for AUV operation in ice ocean
areas
From Fiscal
The polar region is significantly affected by global
warming, and this research looks into the measurement
technologies needed when gathering CTD, ice
thickness, and CO data in this region by AUV.
This fiscal year we continued development of the
program necessary for autonomous operation. We also
carried out a sea trial to confirm the performance of
the vehicle.
3. Personal Research
(1) Electromagnetic pulse subsurface exploration
systems
From Fiscal
180m
Tugboat (4,000 ps class)
(Front)
Seafloor (-40m)
Fig. 8 Conceptual diagram of the free oscillation test
Plate subduction and fault structures can be examined
by transmitting a strong electromagnetic pulse
into the earth's interior and measuring the reflected
echo. It also has the potential for discovering water
reservoirs and buried objects. The advantages of using
electromagnetic pulse in exploration is that it generates
more information than the conventional sound
wave or magnetic field methods used in subsurface
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