This paper presents the possibilities of job optimization in waterway with multiple locks and canals, in order to increase the system productivity. Safe navigation in such complex waterway system is very demanding. So...This paper presents the possibilities of job optimization in waterway with multiple locks and canals, in order to increase the system productivity. Safe navigation in such complex waterway system is very demanding. Some of the problems that need to be solved are： How to control traffic in a way that vessels move in opposite directions; How to resolve possible conflicts in case that more vessels try to acquire particular lock at the same time; How to avoid possible deadlocks; How to ensure the vessel passage in the shortest possible time？ It is necessary to apply adequate control policy to avoid deadlocks and blocks the vessels＇ moving only in the case of dangerous situation. The motion of vessels can be described as the set of discrete events and states. Herein we propose deadlock avoidance algorithm for complex waterway system with multiple key resources and we use multiple re-entrant flowlines class of Petri net （MRF^PN）. The solution represents deadlock prevention supervisor in a sense that vessels are stopped only in a case of immediate dangerous situation in dense traffic. The goal of this paper is to find optimal, conflict and deadlock free job schedule in CWS. In this sense, the authors developed the algorithm which integrates MRF^PN with a genetic algorithm. The algorithm deals with multi-constrained scheduling problem with shared resources. The final goals are minimization the total travel time of vessels through the waterway system.展开更多
According to the measured data after impoundment and operation of the Three Gorges Reservoir,the reservoir sediment deposition and downstream river channel scouring are described briefly and compared with the research...According to the measured data after impoundment and operation of the Three Gorges Reservoir,the reservoir sediment deposition and downstream river channel scouring are described briefly and compared with the research results achieved in the demonstration stage.It is indicated through analysis that the reservoir sediment deposition and downstream river channel scouring during 8-year impoundment and operation are still within the original forecast,so the original forecasting results are feasible.The further observation and comparison should be conducted because the comparison between the observed data and the original forecast is not so sufficient in time and the prototype observation and related research work should be strengthened in the future.展开更多
Wood debris is an important component of mountain streams. It causes serious damage and renders difficulty of water resource management in Taiwan. In this study, the quantity of wood debris and variation of migratory ...Wood debris is an important component of mountain streams. It causes serious damage and renders difficulty of water resource management in Taiwan. In this study, the quantity of wood debris and variation of migratory wood debris during flood events were examined. The downstream of Gaoshan Creek and Qijiawan Creek, located at Central Taiwan, was selected as the study area. The distribution and dynamic of wood debris in a high gradient headwater catchment were quantified using field surveys. A formula of critical depth for wood debris entrainment was used to evaluate the wood debris migration during three flooding events. In the study area, wood abundance and unit volume increased downstream, and wood density decreased downstream within a channel network. The channel morphology, riparian vegetation, and wood debris characteristics were found to influence the wood storage. As a result, the wood debris has an irregular accumulative distribution in the steep stream, and it migrates easily in the stream because of a high flow discharge. Strong relationships between the channel width and wood debris variables are discovered. Moreover, wood debris has a tendency to accumulate at sites with low stream power and wood debris dams, topographical notches, and unique geological structures. Our findings assist in the understanding of the effects of channel characteristics on distributions of wood debris in steep stream systems.展开更多
文摘This paper presents the possibilities of job optimization in waterway with multiple locks and canals, in order to increase the system productivity. Safe navigation in such complex waterway system is very demanding. Some of the problems that need to be solved are： How to control traffic in a way that vessels move in opposite directions; How to resolve possible conflicts in case that more vessels try to acquire particular lock at the same time; How to avoid possible deadlocks; How to ensure the vessel passage in the shortest possible time？ It is necessary to apply adequate control policy to avoid deadlocks and blocks the vessels＇ moving only in the case of dangerous situation. The motion of vessels can be described as the set of discrete events and states. Herein we propose deadlock avoidance algorithm for complex waterway system with multiple key resources and we use multiple re-entrant flowlines class of Petri net （MRF^PN）. The solution represents deadlock prevention supervisor in a sense that vessels are stopped only in a case of immediate dangerous situation in dense traffic. The goal of this paper is to find optimal, conflict and deadlock free job schedule in CWS. In this sense, the authors developed the algorithm which integrates MRF^PN with a genetic algorithm. The algorithm deals with multi-constrained scheduling problem with shared resources. The final goals are minimization the total travel time of vessels through the waterway system.
基金support from the Technology Pillar Program during the"Eleventh Five-year Plan"Period (No.2006BAB05B02No.2006BAB05B03) are acknowledged
文摘According to the measured data after impoundment and operation of the Three Gorges Reservoir,the reservoir sediment deposition and downstream river channel scouring are described briefly and compared with the research results achieved in the demonstration stage.It is indicated through analysis that the reservoir sediment deposition and downstream river channel scouring during 8-year impoundment and operation are still within the original forecast,so the original forecasting results are feasible.The further observation and comparison should be conducted because the comparison between the observed data and the original forecast is not so sufficient in time and the prototype observation and related research work should be strengthened in the future.
基金the Taiwan Science Council for financially supporting this research under Contract No.NSC96-2625-Z005-001-MY3
文摘Wood debris is an important component of mountain streams. It causes serious damage and renders difficulty of water resource management in Taiwan. In this study, the quantity of wood debris and variation of migratory wood debris during flood events were examined. The downstream of Gaoshan Creek and Qijiawan Creek, located at Central Taiwan, was selected as the study area. The distribution and dynamic of wood debris in a high gradient headwater catchment were quantified using field surveys. A formula of critical depth for wood debris entrainment was used to evaluate the wood debris migration during three flooding events. In the study area, wood abundance and unit volume increased downstream, and wood density decreased downstream within a channel network. The channel morphology, riparian vegetation, and wood debris characteristics were found to influence the wood storage. As a result, the wood debris has an irregular accumulative distribution in the steep stream, and it migrates easily in the stream because of a high flow discharge. Strong relationships between the channel width and wood debris variables are discovered. Moreover, wood debris has a tendency to accumulate at sites with low stream power and wood debris dams, topographical notches, and unique geological structures. Our findings assist in the understanding of the effects of channel characteristics on distributions of wood debris in steep stream systems.
