Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Marine Technology Department
exploration to date.
This fiscal year, as well as formulating the concept,
we designed and produced for trial a high-powered
pulse transmitter and a highly sensitive search coil
antenna for the receiver. We also confirmed the underwater
characteristics of the sensitive receiving search
coil antenna. And we began developing the simulation
code using FDTD (Finite Difference Time Domain).
(2) High-performance (low specific gravity, high
strength) buoyancy material
From Fiscal
To improve the maneuverability and increase the
payload of manned submersibles and ROVs, these
vessels must be made smaller and lighter. The greater
the operating depth, the greater the weight of the pressure
vessel, so buoyancy material must have a low
specific gravity and high strength.
In this research, we make hollow spheres from engineering
ceramics with a high specific compressive
strength, and examining technological issues when they
are used as buoyancy material. Ceramics have a higher
compressive strength and are more corrosion-resistant
than titanium alloy and other metal material, so they are
highly suited to use under harsh environments, however,
the brittleness of ceramics has been a major barrier to
their more extensive use as structural material.
This fiscal year, we made hollow spheres with a
compression strength of more than MPa using
alumina, a kind of engineering ceramics. We also
designed a device for measuring sphericity for small
spheres, and measured the local curvature radius of the
sphere surface. Through this, we carried out a quantitative
assessment of irregularity, and examined its
relationship with compression strength.
4. Cooperative Research
(1) Dynamic behavior of flexible pipe
From Fiscal
Continuing on from last year, this fiscal year we
examined and developed theoretical analysis methods
for behavior of linear structures including riser pipes to
clarify dynamic behavior, and surveyed current flexible
pipe technology. We carried out behavior measuring
tests using test models of long linear structures
under deepwater conditions in the deep-sea simulation
tank at the National Maritime Research Institute
(NMRI), JAMSTEC's joint research partner. In the
experiment, we produced and used a Teflon line and
synthetic rubber model of the intake pipe for the airlift
pump on "Mighty Whale" offshore floating wave
power device. We measured three dimensional displacement
of each of the many measurement points set
along the long linear structure model using an image
measurement device. From the experiment we gained
important data on the behavioral characteristics of long
linear structures, and these data will be invaluable in
developing behavior analysis methods.
(2) Hydrothermal plume observation technology
From Fiscal
Observing hydrothermal plumes spouting out from
the seafloor is important for understanding the dynamics
of the earth's interior and global material circulation.
This research is mainly aimed at developing
plume chemical observation methods required for the
efficient exploration of hydrothermal plume source
and for gaining a temporal and spatial understanding
of changes in hydrothermal plumes, and in-situ observation
to confirm their effectiveness. From the results
of tests carried out last fiscal year, we determined the
dimensions of the ion-sensitive membrane and packaging
methods for ISFET specifications, and produced
a prototype. From examinations on its basic characteristics
under high hydrostatic pressure, we found out
that it is affected by pressure. We are currently checking
for causes, but one factor is that there is a problem
with the connection of semiconductor element. We
completed the design and partial production of the
SPR optical sensor test equipment. Regarding sea test
of ISFET sensor, we fitted a pH sensors, CTD, suspension
meter, and water sampler to HYPER-DOL-
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