The development of subsea all-electric Christmas trees is an area of focus in the offshore oil industry worldwide.The main difficulties are associated with the development and control strategies for subsea all-electri...The development of subsea all-electric Christmas trees is an area of focus in the offshore oil industry worldwide.The main difficulties are associated with the development and control strategies for subsea all-electric actuators,which are the most criti-cal components of subsea Christmas trees.A single-motor-level fuzzy PID control with an integrated working condition detection mod-ule and a three-motor redundant-level deviation strategy with coupled joint synchronous control were proposed in this paper to real-ize the real time determination of algorithm parameters according to the working conditions,solve the rapid redistribution problems,and maintain the fast speed of the servo motor of the subsea all-electric tree valve actuator.A synchronous control electrical system was built,tested,and verified through simulation analysis.Test results show that the two redundant servo motors can still control the all-electric valve actuator and provide good synchronization control capabilities despite the failure of one servo motor,and the verti-cal and horizontal vibration values of the system are within reasonable ranges.The synchronous control strategy can be applied to the synchronous control problem of subsea all-electric production systems,which is of considerable importance for the development of subsea all-electric production systems.展开更多
Geographically replicating objects across multiple data centers improves the performance and reliability of cloud storage systems.Maintaining consistent replicas comes with high synchronization costs,as it faces more ...Geographically replicating objects across multiple data centers improves the performance and reliability of cloud storage systems.Maintaining consistent replicas comes with high synchronization costs,as it faces more expensive WAN transport prices and increased latency.Periodic replication is the widely used technique to reduce the synchronization costs.Periodic replication strategies in existing cloud storage systems are too static to handle traffic changes,which indicates that they are inflexible in the face of unforeseen loads,resulting in additional synchronization cost.We propose quantitative analysis models to quantify consistency and synchronization cost for periodically replicated systems,and derive the optimal synchronization period to achieve the best tradeoff between consistency and synchronization cost.Based on this,we propose a dynamic periodic synchronization method,Sync-Opt,which allows systems to set the optimal synchronization period according to the variable load in clouds to minimize the synchronization cost.Simulation results demonstrate the effectiveness of our models.Compared with the policies widely used in modern cloud storage systems,the Sync-Opt strategy significantly reduces the synchronization cost.展开更多
Cooperative spatial exploration in initially unknown surroundings is a common embodied task in various applications and requires satisfactory coordination among the agents.Unlike many other research questions,there is...Cooperative spatial exploration in initially unknown surroundings is a common embodied task in various applications and requires satisfactory coordination among the agents.Unlike many other research questions,there is a lack of simulation platforms for the cooperative exploration problem to perform and statistically evaluate different methods before they are deployed in practical scenarios.To this end,this paper designs a simulation framework to run different models,which features efficient event scheduling and data sharing.On top of such a framework,we propose and implement two different cooperative exploration strategies,i.e.,the synchronous and asynchronous ones.While the coordination in the former approach is conducted after gathering the perceptive information from all agents in each round,the latter enables an ad-hoc coordination.Accordingly,they exploit different principles for assigning target points for the agents.Extensive experiments on different types of environments and settings not only validate the scheduling efficiency of our simulation engine,but also demonstrate the respective advantages of the two strategies on different metrics.展开更多
基金support of the Shandong Provincial Natural Science Foundation(No.ZR2021QE059)the National Natural Science Foundation of China(No.51974169)the Key R&D Program of Shandong Province(No.2019GGX101020).
文摘The development of subsea all-electric Christmas trees is an area of focus in the offshore oil industry worldwide.The main difficulties are associated with the development and control strategies for subsea all-electric actuators,which are the most criti-cal components of subsea Christmas trees.A single-motor-level fuzzy PID control with an integrated working condition detection mod-ule and a three-motor redundant-level deviation strategy with coupled joint synchronous control were proposed in this paper to real-ize the real time determination of algorithm parameters according to the working conditions,solve the rapid redistribution problems,and maintain the fast speed of the servo motor of the subsea all-electric tree valve actuator.A synchronous control electrical system was built,tested,and verified through simulation analysis.Test results show that the two redundant servo motors can still control the all-electric valve actuator and provide good synchronization control capabilities despite the failure of one servo motor,and the verti-cal and horizontal vibration values of the system are within reasonable ranges.The synchronous control strategy can be applied to the synchronous control problem of subsea all-electric production systems,which is of considerable importance for the development of subsea all-electric production systems.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.62272026 and 62104014)the fund of the State Key Laboratory of Software Development Environment(No.SKLSDE-2022ZX-07)the Iluvatar CoreX semiconductor Co.,Ltd.
文摘Geographically replicating objects across multiple data centers improves the performance and reliability of cloud storage systems.Maintaining consistent replicas comes with high synchronization costs,as it faces more expensive WAN transport prices and increased latency.Periodic replication is the widely used technique to reduce the synchronization costs.Periodic replication strategies in existing cloud storage systems are too static to handle traffic changes,which indicates that they are inflexible in the face of unforeseen loads,resulting in additional synchronization cost.We propose quantitative analysis models to quantify consistency and synchronization cost for periodically replicated systems,and derive the optimal synchronization period to achieve the best tradeoff between consistency and synchronization cost.Based on this,we propose a dynamic periodic synchronization method,Sync-Opt,which allows systems to set the optimal synchronization period according to the variable load in clouds to minimize the synchronization cost.Simulation results demonstrate the effectiveness of our models.Compared with the policies widely used in modern cloud storage systems,the Sync-Opt strategy significantly reduces the synchronization cost.
基金This work was supported in part by the National Natural Science Foundation of China(Nos.61273300,62103428,62103425,and 62306329)the Natural Science Fund of Hunan Province(No.2023JJ40676).
文摘Cooperative spatial exploration in initially unknown surroundings is a common embodied task in various applications and requires satisfactory coordination among the agents.Unlike many other research questions,there is a lack of simulation platforms for the cooperative exploration problem to perform and statistically evaluate different methods before they are deployed in practical scenarios.To this end,this paper designs a simulation framework to run different models,which features efficient event scheduling and data sharing.On top of such a framework,we propose and implement two different cooperative exploration strategies,i.e.,the synchronous and asynchronous ones.While the coordination in the former approach is conducted after gathering the perceptive information from all agents in each round,the latter enables an ad-hoc coordination.Accordingly,they exploit different principles for assigning target points for the agents.Extensive experiments on different types of environments and settings not only validate the scheduling efficiency of our simulation engine,but also demonstrate the respective advantages of the two strategies on different metrics.
