ROVs are often used to underwater observation and research mission. However, the operation of conventional ROVs under disturbances such as wave and current conditions are often problem. If the target object is moving by disturbances, the operation will not be able to continue. Therefore, we are aiming at realization of smart and secure in situ operations onboard. Especially, objective of our project is maintenance examination for swinging mooring facility of GPS buoys by our developed underwater vehicle. The buoys were deployed for survey hydrographic phenomena. Our key methods for semi-autonomous underwater vehicle are optical navigation and smart operational interface. In particular, our objective is that we realize grasping of the degree of soundness of the chain part as remaining amount of chain by the underwater vehicle with image measurement system in situ through the optical navigation function assists the vehicle operation under disturbances. In this paper, mimic mission of maintenance examination for the mooring facility and a performance trial of target tracking with optical navigation under wave condition in large tank were described. The tests were carried out by using developed tank test model with image measurement system and optical navigation function. In addition, primary required performances of a practical trial model of mooring facility inspection machine were specified by the above described tests, current measurements, and other field data. Consequently, key components of the practical trial model of mooring facility inspection machine were shown.
The NAKHODKA oil spill in 1997 caused extensive damage to the Japanese coast of Japan Sea. and the amount of damage was 36 billion yen. This paper shows an oil skimmer in emergency. Japanese coast is very long but the oil recovery vessels are not distributed enough to response quickly. We supposed that the crane barges will be useful for oil recovery because they are distributed all prefectures which have coastline and ports. Therefore, the Bucket Oil Skimmer with Rake was developed. The skimmer is operated by the labors employed by the company of the cranebarge operator. It is transported by truck to the port near the coast where we have to recover oil.The crane barge prepares to recover oil at the quay. The system should be easy to operate. Therefore we designed that the skimmer can recover the oil which shows its viscosity range from C heavy fuel to emulsified high viscous oil. Operational image is similar to the grab bucket that is often used for oil recovery in emergency. These concepts help to recover the oil without special technical knowledge. However, the grab bucket recovers so much water with oil. so we must prepare enormous capacity of storage. The skimmer we developed canseparate the high density oily phase from recovered oily water by its drain device.We tested the skimmer in the large basin under waves, and made a field simulation at SAKAI Port. We appreciate the skimmer that its oil recovery rate will be 5. 9 t/h. and oil recovery efficiency will be 70%from 1/4 scale model test. It shows that its capacity is as same as the Grab Bucket, and the oil density in recovered fluid will be two times higher. From the field test, we appreciate the skimmerwill be able to be operated simply without special knowledge about oilspill response products.
Mutsu Bay is semi-enclosed coastal water body composed of Iwo bays. The west bay connected to Tsugaru Straight is strongly influenced by Tsugaru Warm Current and high-saline, warm, whereas the east bay is low-saline, cold. The abrupt rises of the bottom water temperature and its vertical reversal was observed at the automatic marine monitoring buoys under a condition of the atmospheric disturbance approaching in the bay during March 6-8th. 200.1 This study reproduced the abrupt vertical reversal of the water temperature and examined the oceanic response to the atmospheric disturbance using the threedimensional mulli level model. The typical northwestern wind in winter drove the surface eastward currents along the northern and southern coasts, which transported the high-saline, warm water from the west bay to the east bay. The westward bottom current flowed into the west bay. compensating the surface current. When the atmospheric disturbance approached the bay. the northeastern wind drove the westward currents transporting the surface water from the east bay to the west bay along the northern and southern coasts. The westward currents were compensated by the downwelling in the southern coast of the east bay and the bottom eastward current transporting the high-saline, warm water from the west bay to the cast bay. Thus, the flow pattern during the atmospheric disturbance was contrast tQ the typical pattern in winter. The surface high-saline, warm water was advected by the downwelling to the bottom layer. The bollom temperature increases higher than the surface, which causes the vertical reversal. Since the salinity of the transported bottom warm water is relatively high, the density of the warm water is hardly different from that of the low-saline, cold water distributed at the bollom in the east bay before the atmospheric disturbance approaching. After the atmospheric disturbance, the structures of the flow and temperature required approximately four days and more than a week, respectively, to returns lo the typical patterns in winter.
Although a lot of studies of ocean carbon cycle had focused on phytoplankton in euphotic zone, ecosystem under euphotic zone should also be paid attention to understand the carbon cycle in the ocean, because average depth of ocean reach 3800 m. However conventional models focused on euphotic zone have considerably underestimated zooplankton biomass in deep sea. We carried out sensitivity analysis on Ivlev constant relating in feeding limitation and migration effect using new ocean carbon cycle model with more plankton functional groups than conventional one. Sensitivity analysis on zooplankton parameters shows a possibility that underestimation of zooplankton biomass is due to feeding limitation of zooplankton. it is suggested that large size zooplankton has the smaller feeding limitation than the small size one. Additionally zooplankton daily migration shows possibility that play an important role that link surface to deep sea in carbon cycle.