This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems.For this purpose,a complex ship piping system is designed to operate in firefighting and bilge services thr...This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems.For this purpose,a complex ship piping system is designed to operate in firefighting and bilge services through jet pumps.The system is solved as pressure-dependent model by the piping system analysis software EPANET and by a mathematical approach involving a piping network model.This results in a functional system that guarantees the recommendable ranges of hydraulic state variables(flow and pressure)and compliance with the rules of ship classification societies.Through this research,the suitability and viability of pressure-dependent models in the simulation of a ship piping system are proven.展开更多
Since the roll damping of ships has significant effects of viscosity, it is difficult to calculate it theoretically. Therefore, experimental results or some prediction methods are used to get the roll damping in desig...Since the roll damping of ships has significant effects of viscosity, it is difficult to calculate it theoretically. Therefore, experimental results or some prediction methods are used to get the roll damping in design stage of ships. Among some prediction methods, Ikeda＇s one is widely used in many ship motion computer programs. Using the method, the roll damping of various ship hulls with various bilge keels can be calculated to investigate its characteristics. To calculate the roll damping of each ship, detailed data of the ship are needed to input. Therefore, a simpler prediction method is expected in primary design stage. Such a simple method must be useful to validate the results obtained by a computer code to predict it on the basis of Ikeda＇s method, too. On the basis of the predicted roll damping by Ikeda＇s method for various ships, a very simple prediction formula of the roll damping of ships is deduced in the present paper. Ship hull forms are systematically changed by changing length, beam, draft, mid-ship sectional coefficient and prismatic coefficient. It is found, however, that this simple formula can not be used for ships that have high position of the center of gravity. A modified method to improve accuracy for such ships is proposed.展开更多
Ships generate large amounts of wastewater including oily bilge water, blackwater and greywater. Traditionally they are treated separately with high energy consumption. In this study we demonstrate the feasibility tha...Ships generate large amounts of wastewater including oily bilge water, blackwater and greywater. Traditionally they are treated separately with high energy consumption. In this study we demonstrate the feasibility that these waste streams can be treated using an integrated electrocoagulation cell (ECC) and microbial fuel cell (MFC) process, which not only synergized the contaminants removal but also accomplished energy neutrality by directly powering EC with MFC electricity. Results showed that MFC stack powered ECC removed 93% of oily organics, which is comparable to the performance of an external DC voltage powered ECC. In the meantime, more than 80% of COD was removed from MFCs when fed with either acetate or municipal wastewater. Moreover, the ECC electrode area and distance showed notable effects on current generation and contaminants removal, and further studies should focus on operation optimization to enhance treatment efficiency.展开更多
According to the linear wave resistance theory, a comparison among the ship resistance for the high speed round bilge ships, the deep “Vee” vessels, the wave-piercing catamarans, and the high speed trimarans was giv...According to the linear wave resistance theory, a comparison among the ship resistance for the high speed round bilge ships, the deep “Vee” vessels, the wave-piercing catamarans, and the high speed trimarans was given by using the high-speed round-bilge ship as a benchmark. And the optimal speed range of each ship form was also suggested by using the analysis of the research results.展开更多
文摘This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems.For this purpose,a complex ship piping system is designed to operate in firefighting and bilge services through jet pumps.The system is solved as pressure-dependent model by the piping system analysis software EPANET and by a mathematical approach involving a piping network model.This results in a functional system that guarantees the recommendable ranges of hydraulic state variables(flow and pressure)and compliance with the rules of ship classification societies.Through this research,the suitability and viability of pressure-dependent models in the simulation of a ship piping system are proven.
文摘Since the roll damping of ships has significant effects of viscosity, it is difficult to calculate it theoretically. Therefore, experimental results or some prediction methods are used to get the roll damping in design stage of ships. Among some prediction methods, Ikeda＇s one is widely used in many ship motion computer programs. Using the method, the roll damping of various ship hulls with various bilge keels can be calculated to investigate its characteristics. To calculate the roll damping of each ship, detailed data of the ship are needed to input. Therefore, a simpler prediction method is expected in primary design stage. Such a simple method must be useful to validate the results obtained by a computer code to predict it on the basis of Ikeda＇s method, too. On the basis of the predicted roll damping by Ikeda＇s method for various ships, a very simple prediction formula of the roll damping of ships is deduced in the present paper. Ship hull forms are systematically changed by changing length, beam, draft, mid-ship sectional coefficient and prismatic coefficient. It is found, however, that this simple formula can not be used for ships that have high position of the center of gravity. A modified method to improve accuracy for such ships is proposed.
文摘Ships generate large amounts of wastewater including oily bilge water, blackwater and greywater. Traditionally they are treated separately with high energy consumption. In this study we demonstrate the feasibility that these waste streams can be treated using an integrated electrocoagulation cell (ECC) and microbial fuel cell (MFC) process, which not only synergized the contaminants removal but also accomplished energy neutrality by directly powering EC with MFC electricity. Results showed that MFC stack powered ECC removed 93% of oily organics, which is comparable to the performance of an external DC voltage powered ECC. In the meantime, more than 80% of COD was removed from MFCs when fed with either acetate or municipal wastewater. Moreover, the ECC electrode area and distance showed notable effects on current generation and contaminants removal, and further studies should focus on operation optimization to enhance treatment efficiency.
文摘According to the linear wave resistance theory, a comparison among the ship resistance for the high speed round bilge ships, the deep “Vee” vessels, the wave-piercing catamarans, and the high speed trimarans was given by using the high-speed round-bilge ship as a benchmark. And the optimal speed range of each ship form was also suggested by using the analysis of the research results.
