Nowadays, robots generally have a variety of capabilities, which often form a coalition replacing human to work in dangerous environment, such as rescue, exploration, etc. In these operating conditions, the energy sup...Nowadays, robots generally have a variety of capabilities, which often form a coalition replacing human to work in dangerous environment, such as rescue, exploration, etc. In these operating conditions, the energy supply of robots usually cannot be guaranteed. If the energy resources of some robots are consumed too fast, the number of the future tasks of the coalition will be affected. This paper will develop a novel task allocation method based on Gini coefficient to make full use of limited energy resources of multi-robot system to maximize the number of tasks. At the same time, considering resources consumption,we incorporate the market-based allocation mechanism into our Gini coefficient-based method and propose a hybrid method,which can flexibly optimize the task completion number and the resource consumption according to the application contexts.Experiments show that the multi-robot system with limited energy resources can accomplish more tasks by the proposed Gini coefficient-based method, and the hybrid method can be dynamically adaptive to changes of the work environment and realize the dual optimization goals.展开更多
The settling of particles in fluid flows is a common occurrence in various industrial processes. Investigating the interactions between particles and fluid during settling holds significant importance. This article pr...The settling of particles in fluid flows is a common occurrence in various industrial processes. Investigating the interactions between particles and fluid during settling holds significant importance. This article presents a numerical study of the settling process involving two parallel particles in upward flow, employing the immersed boundary method (IBM). The simulation data were validated using experimental results for single spherical particle settlement, two parallel spherical particles settlement, and the settlement of two series of spherical particles. A comparative analysis was conducted between particle settling in upward flow and static fluid. The study explores the impact of different upward velocities and initial particle spacing on particle settling. Results indicate that the wake generated by the two parallel particles in upward flow forms a distinct boundary with the surrounding fluid. As the upward velocity increases, this boundary becomes increasingly observable. In comparison to settling in static flow, the repulsive effect between two parallel particles in upward flow is stronger, and the settling velocity of particles is smaller. Furthermore, the study reveals that the repulsion between two particles diminishes rapidly with an increase in the initial spacing, but the final settling velocity of particles remains nearly constant.展开更多
Numerous gas-liquid-solid flows exist in chemical engineering and metallurgical processes. Numerical modeling is an important topic that can be used to improve the design and investigate the operating conditions of th...Numerous gas-liquid-solid flows exist in chemical engineering and metallurgical processes. Numerical modeling is an important topic that can be used to improve the design and investigate the operating conditions of these processes. The complicated interphase interaction within such three-phase systems, which include free surfaces and discrete phases, poses challenges in the existing methods. We imple- mented a volume-of-fluid （VOF） and discrete-element-method （DEM） combined solver, which should be useful for modeling the gas-liquid-solid systems, within the OpenFOAM framework. The Du Plessis and Masliyah drag force, added mass force, and capillary force were considered for fluid-particle coupling. The VOF-DEM solver was tested in three different cases, namely, particles in pure gas, particle collision in water, and gas-liquid-solid three-phase dam break. The results were validated against previous experi- ments and good agreement was obtained between the simulations and the experiments, which indicates the accuracy and suitability of this VOF-DEM solver for gas-liquid-solid systems.展开更多
基金supported by the National High Technology Research and Development Program of China(863 Program)(2015AA015403)the National Natural Science Foundation of China(61404069,61401185)the Project of Education Department of Liaoning Province(LJYL052)
文摘Nowadays, robots generally have a variety of capabilities, which often form a coalition replacing human to work in dangerous environment, such as rescue, exploration, etc. In these operating conditions, the energy supply of robots usually cannot be guaranteed. If the energy resources of some robots are consumed too fast, the number of the future tasks of the coalition will be affected. This paper will develop a novel task allocation method based on Gini coefficient to make full use of limited energy resources of multi-robot system to maximize the number of tasks. At the same time, considering resources consumption,we incorporate the market-based allocation mechanism into our Gini coefficient-based method and propose a hybrid method,which can flexibly optimize the task completion number and the resource consumption according to the application contexts.Experiments show that the multi-robot system with limited energy resources can accomplish more tasks by the proposed Gini coefficient-based method, and the hybrid method can be dynamically adaptive to changes of the work environment and realize the dual optimization goals.
基金supported by the National Natural Science Foundation of China(grant No.52222601).
文摘The settling of particles in fluid flows is a common occurrence in various industrial processes. Investigating the interactions between particles and fluid during settling holds significant importance. This article presents a numerical study of the settling process involving two parallel particles in upward flow, employing the immersed boundary method (IBM). The simulation data were validated using experimental results for single spherical particle settlement, two parallel spherical particles settlement, and the settlement of two series of spherical particles. A comparative analysis was conducted between particle settling in upward flow and static fluid. The study explores the impact of different upward velocities and initial particle spacing on particle settling. Results indicate that the wake generated by the two parallel particles in upward flow forms a distinct boundary with the surrounding fluid. As the upward velocity increases, this boundary becomes increasingly observable. In comparison to settling in static flow, the repulsive effect between two parallel particles in upward flow is stronger, and the settling velocity of particles is smaller. Furthermore, the study reveals that the repulsion between two particles diminishes rapidly with an increase in the initial spacing, but the final settling velocity of particles remains nearly constant.
文摘Numerous gas-liquid-solid flows exist in chemical engineering and metallurgical processes. Numerical modeling is an important topic that can be used to improve the design and investigate the operating conditions of these processes. The complicated interphase interaction within such three-phase systems, which include free surfaces and discrete phases, poses challenges in the existing methods. We imple- mented a volume-of-fluid （VOF） and discrete-element-method （DEM） combined solver, which should be useful for modeling the gas-liquid-solid systems, within the OpenFOAM framework. The Du Plessis and Masliyah drag force, added mass force, and capillary force were considered for fluid-particle coupling. The VOF-DEM solver was tested in three different cases, namely, particles in pure gas, particle collision in water, and gas-liquid-solid three-phase dam break. The results were validated against previous experi- ments and good agreement was obtained between the simulations and the experiments, which indicates the accuracy and suitability of this VOF-DEM solver for gas-liquid-solid systems.
