In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and lea...In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and leader-follower strategy(IAPF-LF). Firstly, the proposed fixed-time control can achieve the desired multi-AUV formation within a fixed settling time in any initial system state. Secondly, an event-triggered communication strategy is developed to govern the communication among AUVs, and the communication energy consumption can be decremented. The time-varying formation obstacle avoidance control algorithm based on IAPF-LF is designed to avoid static and dynamic obstacles, the desired formation is maintained in the presence of external disturbances, and there is no Zeno behavior under the fixed-time event-triggered consensus control strategy.The stability of the system is proved by the Lyapunov function and inequality scaling. Finally, simulation examples and water pool experiments are reported to verify the performance of the proposed theoretical algorithms.展开更多
Coping strategies adopted to deal with psychological health issues could have influences on the general health, productivity and task performance of the employee. This study sought to investigate the coping strategies...Coping strategies adopted to deal with psychological health issues could have influences on the general health, productivity and task performance of the employee. This study sought to investigate the coping strategies adopted by construction employees to deal with the causes and effects of occupational psychological disorders such as burnout and workaholism. To achieve this aim, the methods of focus group discussions were first employed. A total of 16 semi-structured focus group discussions were held in Ghana, with 90 construction employees. The focus group study revealed 25 coping strategies adopted as efforts to mitigate the causes and 22 coping strategies adopted as responses to moderate the effects of occupational psychological disorders. A quantitative study involving 150 construction professionals and 150 construction trade workers were also conducted in Ghana to investigate the coping strategies that were highly adopted by the two construction working groups. The findings from the study revealed that the construction professionals adopted delegating complicated tasks and seeking medical attention as the most common coping strategies to manage the causes and effects respectively. The construction trade workers were also revealed to adopt withdrawing from work duties or changing jobs and taking in more caffeinated drinks as the most common coping strategies to manage the causes and effects respectively. Exploratory factor analysis was employed, and the findings were put into the main constructs. The causes focused coping strategies were categorized under avoidance, alteration, adaptation, and acceptance. The effects focused coping strategies were also categorized under healthy and unhealthy coping strategies. This study recommends appropriate coping strategies and interventions in the construction industry such as education of construction personnel on the consequences of various coping strategies.展开更多
Consensus theory and noncooperative game theory respectively deal with cooperative and noncooperative interactions among multiple players/agents. They provide a natural framework for road pricing design, since each mo...Consensus theory and noncooperative game theory respectively deal with cooperative and noncooperative interactions among multiple players/agents. They provide a natural framework for road pricing design, since each motorist may myopically optimize his or her own utility as a function of road price and collectively communicate with his or her friends and neighbors on traffic situation at the same time. This paper considers the road pricing design by using game theory and consensus theory. For the case where a system supervisor broadcasts information on the overall system to each agent, we present a variant of standard fictitious play called average strategy fictitious play(ASFP) for large-scale repeated congestion games.Only a weighted running average of all other players actions is assumed to be available to each player. The ASFP reduces the burden of both information gathering and information processing for each player. Compared to the joint strategy fictitious play(JSFP) studied in the literature, the updating process of utility functions for each player is avoided. We prove that there exists at least one pure strategy Nash equilibrium for the congestion game under investigation, and the players actions generated by the ASFP with inertia(players reluctance to change their previous actions) converge to a Nash equilibrium almost surely. For the case without broadcasting, a consensus protocol is introduced for individual agents to estimate the percentage of players choosing each resource, and the convergence property of players action profile is still ensured. The results are applied to road pricing design to achieve socially local optimal trip timing. Simulation results are provided based on the real traffic data for the Singapore case study.展开更多
This study investigates how the events of deception attacks are distributed during the fusion of multi-sensor nonlinear systems.First,a deception attack with limited energy(DALE)is introduced under the framework of di...This study investigates how the events of deception attacks are distributed during the fusion of multi-sensor nonlinear systems.First,a deception attack with limited energy(DALE)is introduced under the framework of distributed extended Kalman consensus filtering(DEKCF).Next,a hypothesis testing-based mechanism to detect the abnormal data generated by DALE,in the presence of the error term caused by the linearization of the nonlinear system,is established.Once the DALE is detected,a new rectification strategy can be triggered to recalibrate the abnormal data,restoring it to its normal state.Then,an attack-resilient DEKCF(AR-DEKCF)algorithm is proposed,and its fusion estimation errors are demonstrated to satisfy the mean square exponential boundedness performance,under appropriate conditions.Finally,the effectiveness of the AR-DEKCF algorithm is confirmed through simulations involving multi-unmanned aerial vehicle(multi-UAV)tracking problems.展开更多
针对新能源出力的强随机性、间歇性影响配电网功率平衡问题,提出了一种融合多步贪婪策略改进的深度双Q网络(double deep Q network,DDQN)算法和一致性算法的双层功率分配策略,该方法在源荷波动情况下可自适应调整配电网各机组出力,保证...针对新能源出力的强随机性、间歇性影响配电网功率平衡问题,提出了一种融合多步贪婪策略改进的深度双Q网络(double deep Q network,DDQN)算法和一致性算法的双层功率分配策略,该方法在源荷波动情况下可自适应调整配电网各机组出力,保证功率调节的快速性和经济性。首先,基于“资源集群”的划分提出了分层分布式功率分配框架,将智能配电网功率分配问题分解为协调调度层和自治层功率优化分配模型进行求解。然后,协调调度层采用多步贪婪策略改进的DDQN算法来实现“资源集群”间的功率分配,自治层提出以成本微增量为一致性状态变量的功率动态分配方法。最后,典型智能配电网算例仿真结果表明,所提的双层功率分配策略能够在新能源波动情况下解决功率的优化分配问题;与多种方法相比,所提方法具有较快的收敛速度和较低的调节成本。展开更多
基金supported in part by the National Natural Science Foundation of China (62033009)the Creative Activity Plan for Science and Technology Commission of Shanghai (20510712300,21DZ2293500)the Supported by Science Foundation of Donghai Laboratory。
文摘In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and leader-follower strategy(IAPF-LF). Firstly, the proposed fixed-time control can achieve the desired multi-AUV formation within a fixed settling time in any initial system state. Secondly, an event-triggered communication strategy is developed to govern the communication among AUVs, and the communication energy consumption can be decremented. The time-varying formation obstacle avoidance control algorithm based on IAPF-LF is designed to avoid static and dynamic obstacles, the desired formation is maintained in the presence of external disturbances, and there is no Zeno behavior under the fixed-time event-triggered consensus control strategy.The stability of the system is proved by the Lyapunov function and inequality scaling. Finally, simulation examples and water pool experiments are reported to verify the performance of the proposed theoretical algorithms.
文摘Coping strategies adopted to deal with psychological health issues could have influences on the general health, productivity and task performance of the employee. This study sought to investigate the coping strategies adopted by construction employees to deal with the causes and effects of occupational psychological disorders such as burnout and workaholism. To achieve this aim, the methods of focus group discussions were first employed. A total of 16 semi-structured focus group discussions were held in Ghana, with 90 construction employees. The focus group study revealed 25 coping strategies adopted as efforts to mitigate the causes and 22 coping strategies adopted as responses to moderate the effects of occupational psychological disorders. A quantitative study involving 150 construction professionals and 150 construction trade workers were also conducted in Ghana to investigate the coping strategies that were highly adopted by the two construction working groups. The findings from the study revealed that the construction professionals adopted delegating complicated tasks and seeking medical attention as the most common coping strategies to manage the causes and effects respectively. The construction trade workers were also revealed to adopt withdrawing from work duties or changing jobs and taking in more caffeinated drinks as the most common coping strategies to manage the causes and effects respectively. Exploratory factor analysis was employed, and the findings were put into the main constructs. The causes focused coping strategies were categorized under avoidance, alteration, adaptation, and acceptance. The effects focused coping strategies were also categorized under healthy and unhealthy coping strategies. This study recommends appropriate coping strategies and interventions in the construction industry such as education of construction personnel on the consequences of various coping strategies.
文摘Consensus theory and noncooperative game theory respectively deal with cooperative and noncooperative interactions among multiple players/agents. They provide a natural framework for road pricing design, since each motorist may myopically optimize his or her own utility as a function of road price and collectively communicate with his or her friends and neighbors on traffic situation at the same time. This paper considers the road pricing design by using game theory and consensus theory. For the case where a system supervisor broadcasts information on the overall system to each agent, we present a variant of standard fictitious play called average strategy fictitious play(ASFP) for large-scale repeated congestion games.Only a weighted running average of all other players actions is assumed to be available to each player. The ASFP reduces the burden of both information gathering and information processing for each player. Compared to the joint strategy fictitious play(JSFP) studied in the literature, the updating process of utility functions for each player is avoided. We prove that there exists at least one pure strategy Nash equilibrium for the congestion game under investigation, and the players actions generated by the ASFP with inertia(players reluctance to change their previous actions) converge to a Nash equilibrium almost surely. For the case without broadcasting, a consensus protocol is introduced for individual agents to estimate the percentage of players choosing each resource, and the convergence property of players action profile is still ensured. The results are applied to road pricing design to achieve socially local optimal trip timing. Simulation results are provided based on the real traffic data for the Singapore case study.
基金supported by the National Natural Science Foundation of China(Nos.62103283 and 12371308)。
文摘This study investigates how the events of deception attacks are distributed during the fusion of multi-sensor nonlinear systems.First,a deception attack with limited energy(DALE)is introduced under the framework of distributed extended Kalman consensus filtering(DEKCF).Next,a hypothesis testing-based mechanism to detect the abnormal data generated by DALE,in the presence of the error term caused by the linearization of the nonlinear system,is established.Once the DALE is detected,a new rectification strategy can be triggered to recalibrate the abnormal data,restoring it to its normal state.Then,an attack-resilient DEKCF(AR-DEKCF)algorithm is proposed,and its fusion estimation errors are demonstrated to satisfy the mean square exponential boundedness performance,under appropriate conditions.Finally,the effectiveness of the AR-DEKCF algorithm is confirmed through simulations involving multi-unmanned aerial vehicle(multi-UAV)tracking problems.
文摘针对新能源出力的强随机性、间歇性影响配电网功率平衡问题,提出了一种融合多步贪婪策略改进的深度双Q网络(double deep Q network,DDQN)算法和一致性算法的双层功率分配策略,该方法在源荷波动情况下可自适应调整配电网各机组出力,保证功率调节的快速性和经济性。首先,基于“资源集群”的划分提出了分层分布式功率分配框架,将智能配电网功率分配问题分解为协调调度层和自治层功率优化分配模型进行求解。然后,协调调度层采用多步贪婪策略改进的DDQN算法来实现“资源集群”间的功率分配,自治层提出以成本微增量为一致性状态变量的功率动态分配方法。最后,典型智能配电网算例仿真结果表明,所提的双层功率分配策略能够在新能源波动情况下解决功率的优化分配问题;与多种方法相比,所提方法具有较快的收敛速度和较低的调节成本。
