Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studi...Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.展开更多
基于一般的决策和规划流程,提出了一个面向兵棋推演的快速决策框架(Rapid Military Decision Framework, RMDF),该框架针对异构实体模型,通过分层的网格环境对复杂推演环境简化建模,将推演实体的作用效果,简化为地面、海上和空中三个网...基于一般的决策和规划流程,提出了一个面向兵棋推演的快速决策框架(Rapid Military Decision Framework, RMDF),该框架针对异构实体模型,通过分层的网格环境对复杂推演环境简化建模,将推演实体的作用效果,简化为地面、海上和空中三个网格环境层次上的作用效果,并以热图的形式在网格环境中显示,通过推演实体的核心参数来确定其性能模型和行为模型,并基于一致性包算法实现任务分配,生成备选行动策略,通过快速仿真实现推演策略的迭代优化,能够在推演之前或推演期间提供行动方案的快速评估,可以有效地辅助兵棋推演指挥人员进行复杂态势下的兵棋推演。展开更多
In this paper, we present a distributed consensus-based algorithm to solve the social welfare maximization problem. This is one of typical problems of distributed energy management in smart grid. In this problem, we c...In this paper, we present a distributed consensus-based algorithm to solve the social welfare maximization problem. This is one of typical problems of distributed energy management in smart grid. In this problem, we consider not only the generator and demand, but also the transmission losses which make the feasibility set of the formulated problem a non-convex set. In solving this issue, we find a noticeable result that the primal problem has the same solution with a new convex optimization problem by getting the utmost out of the implied term in practice. Considering the general communication topology among generators and demands, we first design a finite step algorithm to make each generator and demand know the information of parameters of others.Then, we design a distributed algorithm and also prove the optimality and convergence of the proposed algorithm. Finally, the convergence and optimality are examined through extensive simulations.展开更多
基金supported by National Key Laboratory of Bubble Physics and Natural Circulation of China(Grant No. 51482040105CB0103)
文摘Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.
文摘基于一般的决策和规划流程,提出了一个面向兵棋推演的快速决策框架(Rapid Military Decision Framework, RMDF),该框架针对异构实体模型,通过分层的网格环境对复杂推演环境简化建模,将推演实体的作用效果,简化为地面、海上和空中三个网格环境层次上的作用效果,并以热图的形式在网格环境中显示,通过推演实体的核心参数来确定其性能模型和行为模型,并基于一致性包算法实现任务分配,生成备选行动策略,通过快速仿真实现推演策略的迭代优化,能够在推演之前或推演期间提供行动方案的快速评估,可以有效地辅助兵棋推演指挥人员进行复杂态势下的兵棋推演。
基金supported by the Science and Technology Project of State Grid Zhejiang Electric Power Co.Ltd.(Grant No.5211JY17000P)the Fundamental Research Funds for the Central Universities(Grant No.2242019K40111)+1 种基金the National Natural Science Foundation of China(Grant No.61673107)the Jiangsu Provincial Key Laboratory of Networked Collective Intelligence(Grant No.BM2017002)
文摘In this paper, we present a distributed consensus-based algorithm to solve the social welfare maximization problem. This is one of typical problems of distributed energy management in smart grid. In this problem, we consider not only the generator and demand, but also the transmission losses which make the feasibility set of the formulated problem a non-convex set. In solving this issue, we find a noticeable result that the primal problem has the same solution with a new convex optimization problem by getting the utmost out of the implied term in practice. Considering the general communication topology among generators and demands, we first design a finite step algorithm to make each generator and demand know the information of parameters of others.Then, we design a distributed algorithm and also prove the optimality and convergence of the proposed algorithm. Finally, the convergence and optimality are examined through extensive simulations.
