An Onboard Air Conveyer Oil Skimmer
A high power air conveyer oil skimming system and implementation on a real oil recovery vessel are presented. Port and Airport Research Institute (PARI) has succeeded in development of a new type of onboard oil recovery system. Development of the project has been in cooperation with the Shikoku Regional Bureau, Ministry of Land Infrastructure and Transport Japan (MLIT). The system employs a high-power vacuum blower for sucking liquid in gas-liquid multiphase form. Its applicability to an onboard oil recovery system has been experimentally investigated. The experiments have shown that the method can respond to the wide range of viscosity of the spilled oil and works well even in wavy sea condition. These results have been applied to the oil skimming system mounted on ISHIZUCH - an oil recovery vessel owned and operated by MLIT recently refitted by Mitsui Engineering & Shipbuilding Co., LTD
Game-theoretic cooperative coverage using autonomous vehicles
This paper presents a game-theoretic method for cooperative coverage of a priori unknown environments using a team of autonomous vehicles. These autonomous vehicles are required to cooperatively scan the search area without human supervision as autonomous entities. However, due to the lack of a priori knowledge of the exact obstacle locations, the trajectories of autonomous vehicles cannot be computed offline and need to be adapted as the environment is discovered in situ. In this regard, the cooperative coverage method is based upon the concept of multi-resolution navigation that consists of local navigation and global navigation. The main advantages of this algorithm are: i) the local navigation enables real-time locally optimal decisions with a reduced computational complexity by avoiding unnecessary global computations, and ii) the global navigation offers a wider view of the area seeking for unexplored regions. This algorithm prevents the autonomous vehicles from getting trapped into local minima, which is commonly encountered in potential field based algorithms. The neighboring agents among the team of autonomous vehicles exchange the most up-to-date environment information for collaborations. Given sufficient operation time, the team of autonomous vehicles are capable of achieving complete coverage in their own regions. However, in order to further improve cleaning efficiency and reduce operation time, the vehicles that finish early should participate in assisting others that are in need of help. In this sense, a cooperative game is designed to be played among involved agents for optimal task reallocation. This paper considers the cooperative oil spill cleaning application; however the concepts can be applied to general class of coverage problems. The efficacy of the algorithm is validated using autonomous vehicles equipped with lasers in an obstacle-rich environment on the high-fidelity Player/Stage simulator.
STUDY ON VACUUM SUCTION ONBOARD OIL RECOVERY SYSTEM
A vacuum suction oil skimming system is investigated. Several types of suction inlets are experimentally studied with small-sized models. Their suction performances are measured in terms of liquid suction rates, oil and water fraction, pressure gradient and liquid hold-up in a vertical suction pipe in various simulated conditions. In the experiments, W/O emulsified heavy oil, whose viscosity is about 300,000mPa•Es, is used. The results show that the vacuum suction is a potentially suitable measure for skimming spilled oil from sea surface since it has even better