[1] In this study gravitational circulation and its response to the variation in river discharge have been investigated in the Seto Inland Sea, Japan. Monthly hydrographic surveys have been conducted from 2002 to 2006 in Hiuchi-Nada, a basin located between two straits. Horizontal salinity gradients along the channel varied as the 9/10 power of the river discharge into one end of the basin. Significant volume fluxes which were proportional to the horizontal salinity gradients were found. The relationship between river discharge (R m 3 s À1 ) and the volume flux (Q m 3 s À1 ) was represented as Q = 13.9R 0.88 . When river discharge increased, vertical density gradients were intensified and then along-channel horizontal density gradients were gradually enhanced due to vertical mixing at the western strait. These gradients drove gravitational circulations along the channel. The gravitational circulations were not uniform across the channel and accompanied by horizontal circulations. In the northern part of the basin, low-salinity water at the eastern end of the basin was directed toward the west and high-salinity water was directed toward the east. The eastward flows arising from the intrusion of relatively heavy water at the western strait extended from the bottom to the surface. In the southern part, low-salinity water was directed toward the west. The westward flows arising from the intrusion of relatively light water at the eastern strait concentrated in the middle layer and formed a plume-like structure, accompanied by the eastward flow under the plume. These situations were responsible for the development of the bulk exchange flux.
The seawater exchange is closely related to the spreading of pollutant and the water quality in coastal seas. The Seto Inland Sea is a semi-enclosed coastal sea which has a series of broad basins and narrow straits, and the along-channel outflows from the strait located at the center of the channel toward east and west may play an important role in seawater exchange. In this study, flows along the boundary between Bisan Seto which is located at the center of the Seto Inland Sea and the adjacent basin called Harima Nada were measured using a ship-mounted Acoustic Doppler Current Profiler and residual flows were obtained by removing tidal currents. The survey results showed significant volume flux of the along-channel outflows from Bisan Seto toward Harima Nada. A numerical model based on Princeton Ocean Model was also used in order to analyze the driving forces of the along-channel outflow. The outflow was well reproduced using the model which was driven by tide and horizontal density gradient between the strait and basin, suggesting that these possibly induce the seawater exchange in the Seto Inland Sea.
The purpose of this study is a design of an automatic peering system with a Controllable Pitch Propeller (CPP) in the case of the stormy weather. A velocity response of CPP has a delay time. Especially, this study verifies the ship's propelling force against the CPP angle and detects the delay time by analyzing the data of the propelling force. The CPP angle is controlled by Generalized Minimum Variance Control (GMVC). This study arranges the GMVC for the automatic mooring system. The proposed GMVC has wind and a tidal effect's terms. The wind effect's term is considered by the ship's drift with the wind. The predicted wind velocity is calculated by the AR model of wind change. The AR model of wind is used for the GMVC of the peering system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.