To study simultaneous location of different kinds of facilities,a new model of flow interception problem with multi-type of flows is proposed,with the consideration of multi-purpose flows and the influence of faciliti...To study simultaneous location of different kinds of facilities,a new model of flow interception problem with multi-type of flows is proposed,with the consideration of multi-purpose flows and the influence of facilities on each other.To be more practical,the objective is to maximize the benefits from flow-by customers instead of maximizing flows in the past.Since this problem is NP-hard and there is no optimal solution for large network,greedy and improved greedy heuristic algorithms are proposed.A computational example is presented to show that the optimal location decisions are proved to be strongly dependent on the influence coefficients and average profits by one customer and different types of facilities are almost co-located.Finally the results of sensitivity analysis are reported.展开更多
To study location problems with congestion demand,a bi-objective model based on flow intercep-tion problem is proposed.The model is formulated from the view of M/M/m queuing systems.Service quantity and quality are si...To study location problems with congestion demand,a bi-objective model based on flow intercep-tion problem is proposed.The model is formulated from the view of M/M/m queuing systems.Service quantity and quality are simultaneously considered as objectives,with constraint on total cost.Service quality includes deviation distance from preplanned trips and customers'waiting time.Service quantity is the number of intercep-tion customers.A multi-objective evolutionary algorithm combined with greedy heuristic is proposed.Finally a computational experiment is given,and the algorithm is proved to be efficient.展开更多
Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dyna...Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.展开更多
This paper presents the logic relationship between rural settlement reconstruction and soil conservation in the Upper Yangtze River. Firstly, by introducing the concepts of ＂flow＂ and ＂intercepted flow＂, we probe ...This paper presents the logic relationship between rural settlement reconstruction and soil conservation in the Upper Yangtze River. Firstly, by introducing the concepts of ＂flow＂ and ＂intercepted flow＂, we probe into the dynamic mechanism on interaction between ecological and environmental system, and then point out that the ＂intercepting sites＂ are physical conditions for establishment of human settlements in mountains. Secondly, by using ecological theories, ＂flow＂, ＂source＂, and ＂sink＂, material cycle and energy flow in mountains have been discussed. Thirdly, according to dissipative structure theory and thermodynamic laws, a hypothesis has been proposed that ＂entropy flow＂ is a dynamic force for settlement evolution. Finally, it is argued that a project for soil conservation is set to control and utilize flows so rural settlements can be supported and farmers＇ life improved.展开更多
基金supported by the National Natural Science Foundation of China(70601011,70871044)Trans-Century Traning Program Foundation for the Talents by the State Education Commission(NECT-06-0653).
文摘To study simultaneous location of different kinds of facilities,a new model of flow interception problem with multi-type of flows is proposed,with the consideration of multi-purpose flows and the influence of facilities on each other.To be more practical,the objective is to maximize the benefits from flow-by customers instead of maximizing flows in the past.Since this problem is NP-hard and there is no optimal solution for large network,greedy and improved greedy heuristic algorithms are proposed.A computational example is presented to show that the optimal location decisions are proved to be strongly dependent on the influence coefficients and average profits by one customer and different types of facilities are almost co-located.Finally the results of sensitivity analysis are reported.
基金supported by the National Natural Science Foundation of China(70601011,70871044)Trans-Century Training Program Foundation for the Talents by the State Education Commission(NCET-06-0653)
文摘To study location problems with congestion demand,a bi-objective model based on flow intercep-tion problem is proposed.The model is formulated from the view of M/M/m queuing systems.Service quantity and quality are simultaneously considered as objectives,with constraint on total cost.Service quality includes deviation distance from preplanned trips and customers'waiting time.Service quantity is the number of intercep-tion customers.A multi-objective evolutionary algorithm combined with greedy heuristic is proposed.Finally a computational experiment is given,and the algorithm is proved to be efficient.
基金supported by the National Natural Science Foundation of China (51639007)the Youth Science and Technology Fund of Sichuan Province (2016JQ0011)the Science and Technology Fund of Chengdu Water Authority (14H1055).
文摘Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.
基金the Key Social Research Project of Education Ministry (04JZD0010)
文摘This paper presents the logic relationship between rural settlement reconstruction and soil conservation in the Upper Yangtze River. Firstly, by introducing the concepts of ＂flow＂ and ＂intercepted flow＂, we probe into the dynamic mechanism on interaction between ecological and environmental system, and then point out that the ＂intercepting sites＂ are physical conditions for establishment of human settlements in mountains. Secondly, by using ecological theories, ＂flow＂, ＂source＂, and ＂sink＂, material cycle and energy flow in mountains have been discussed. Thirdly, according to dissipative structure theory and thermodynamic laws, a hypothesis has been proposed that ＂entropy flow＂ is a dynamic force for settlement evolution. Finally, it is argued that a project for soil conservation is set to control and utilize flows so rural settlements can be supported and farmers＇ life improved.
