本文围绕智能工厂中关键性任务的边缘计算开展研究.考虑边缘计算中由于信道的不确定性及计算资源受限可能出现的高时延风险,首先通过使用条件风险价值(Conditional Value at Risk,CVaR)完成时延分布尾部信息的刻画,通过利用CVaR的凸性...本文围绕智能工厂中关键性任务的边缘计算开展研究.考虑边缘计算中由于信道的不确定性及计算资源受限可能出现的高时延风险,首先通过使用条件风险价值(Conditional Value at Risk,CVaR)完成时延分布尾部信息的刻画,通过利用CVaR的凸性和平移等价性,给出了时延CVaR的上界.进一步,通过对边缘服务器的选择与计算资源分配,完成了机器设备处理计算任务的平均时延与CVaR上界的联合优化.通过仿真实验,验证了算法模型对高时延分布刻画的有效性.从仿真结果可知,所提策略不仅提高了计算的可靠性,同时降低了时延的高风险值.展开更多
In recent years,multiple-load automatic guided vehicle(AGV)is increasingly used in the logistics transportation fields,owing to the advantages of smaller fleet size and fewer occurrences of traffic congestion.However,...In recent years,multiple-load automatic guided vehicle(AGV)is increasingly used in the logistics transportation fields,owing to the advantages of smaller fleet size and fewer occurrences of traffic congestion.However,one main challenge lies in the deadlock-avoidance for the dispatching process of a multiple-load AGV system.To prevent the system from falling into a deadlock,a strategy of keeping the number of jobs in the system(NJIS)at a low level is adopted in most existing literatures.It is noteworthy that a low-level NJIS will make the processing machine easier to be starved,thereby reducing the system efficiency unavoidably.The motivation of the paper is to develop a deadlock-avoidance dispatching method for a multiple-load AGV system operating at a high NJIS level.Firstly,the deadlock-avoidance dispatching method is devised by incorporating a deadlock-avoidance strategy into a dispatching procedure that contains four sub-problems.In this strategy,critical tasks are recognized according to the status of workstation buffers,and then temporarily forbidden to avoid potential deadlocks.Secondly,three multiattribute dispatching rules are designed for system efficiency,where both the traveling distance and the buffer status are taken into account.Finally,a simulation system is developed to evaluate the performance of the proposed deadlock-avoidance strategy and dispatching rules at different NJIS levels.The experimental results demonstrate that our deadlock-avoidance dispatching method can improve the system efficiency at a high NJIS level and the adaptability to various system settings,while still avoiding potential deadlocks.展开更多
文摘本文围绕智能工厂中关键性任务的边缘计算开展研究.考虑边缘计算中由于信道的不确定性及计算资源受限可能出现的高时延风险,首先通过使用条件风险价值(Conditional Value at Risk,CVaR)完成时延分布尾部信息的刻画,通过利用CVaR的凸性和平移等价性,给出了时延CVaR的上界.进一步,通过对边缘服务器的选择与计算资源分配,完成了机器设备处理计算任务的平均时延与CVaR上界的联合优化.通过仿真实验,验证了算法模型对高时延分布刻画的有效性.从仿真结果可知,所提策略不仅提高了计算的可靠性,同时降低了时延的高风险值.
基金supported by the National Natural Science Foundation of China(Nos.52005427,61973154)the National Defense Basic Scientific Research Program of China(No.JCKY2018605C004)+1 种基金the Natural Science Research Project of Jiangsu Higher Education Institutions(Nos.19KJB510013,18KJA460009)the Foundation of Graduate Innovation Center in Nanjing University of Aeronautics and Astronautics(No.KFJJ20190516)。
文摘In recent years,multiple-load automatic guided vehicle(AGV)is increasingly used in the logistics transportation fields,owing to the advantages of smaller fleet size and fewer occurrences of traffic congestion.However,one main challenge lies in the deadlock-avoidance for the dispatching process of a multiple-load AGV system.To prevent the system from falling into a deadlock,a strategy of keeping the number of jobs in the system(NJIS)at a low level is adopted in most existing literatures.It is noteworthy that a low-level NJIS will make the processing machine easier to be starved,thereby reducing the system efficiency unavoidably.The motivation of the paper is to develop a deadlock-avoidance dispatching method for a multiple-load AGV system operating at a high NJIS level.Firstly,the deadlock-avoidance dispatching method is devised by incorporating a deadlock-avoidance strategy into a dispatching procedure that contains four sub-problems.In this strategy,critical tasks are recognized according to the status of workstation buffers,and then temporarily forbidden to avoid potential deadlocks.Secondly,three multiattribute dispatching rules are designed for system efficiency,where both the traveling distance and the buffer status are taken into account.Finally,a simulation system is developed to evaluate the performance of the proposed deadlock-avoidance strategy and dispatching rules at different NJIS levels.The experimental results demonstrate that our deadlock-avoidance dispatching method can improve the system efficiency at a high NJIS level and the adaptability to various system settings,while still avoiding potential deadlocks.
