电离层总电子含量(Total Electron Content,TEC)精确预报对提高卫星导航定位精度具有重要意义.为此,提出一种联合鲸鱼优化算法(Whale Optimization Algorithm,WOA)与长短期记忆神经网络模型(Long-Short Term Memory Networks,LSTM)的TE...电离层总电子含量(Total Electron Content,TEC)精确预报对提高卫星导航定位精度具有重要意义.为此,提出一种联合鲸鱼优化算法(Whale Optimization Algorithm,WOA)与长短期记忆神经网络模型(Long-Short Term Memory Networks,LSTM)的TEC短期预报模型;该模型通过LSTM模型训练得到WOA算法的最佳适应度,并利用优化的WOA算法得到LSTM模型最优参数.最后,结合欧洲定轨中心(Center for Orbit Determination in Europe,CODE)提供的TEC格网点数据对所提模型进行验证;试验结果表明:地磁平静状态下,组合模型的平均相关系数ρ较LSTM模型在低、中、高纬度分别提升了2.8%、6.2%和14.8%;地磁活跃状态下组合模型的平均相关系数ρ在低、中、高纬度地区较LSTM模型分别提升了6.6%、9.2%与7.9%.且模型预报效果与地磁活跃状态、季节、太阳活跃水平等有关,在不同地磁活跃状态、季节与不同太阳活动水平情况下,组合模型预报效果均优于单一LSTM模型,为电离层TEC预报模型的实际应用提供了参考.展开更多
The uncertain nature of mapping user tasks to Virtual Machines(VMs) causes system failure or execution delay in Cloud Computing.To maximize cloud resource throughput and decrease user response time,load balancing is n...The uncertain nature of mapping user tasks to Virtual Machines(VMs) causes system failure or execution delay in Cloud Computing.To maximize cloud resource throughput and decrease user response time,load balancing is needed.Possible load balancing is needed to overcome user task execution delay and system failure.Most swarm intelligent dynamic load balancing solutions that used hybrid metaheuristic algorithms failed to balance exploitation and exploration.Most load balancing methods were insufficient to handle the growing uncertainty in job distribution to VMs.Thus,the Hybrid Spotted Hyena and Whale Optimization Algorithm-based Dynamic Load Balancing Mechanism(HSHWOA) partitions traffic among numerous VMs or servers to guarantee user chores are completed quickly.This load balancing approach improved performance by considering average network latency,dependability,and throughput.This hybridization of SHOA and WOA aims to improve the trade-off between exploration and exploitation,assign jobs to VMs with more solution diversity,and prevent the solution from reaching a local optimality.Pysim-based experimental verification and testing for the proposed HSHWOA showed a 12.38% improvement in minimized makespan,16.21% increase in mean throughput,and 14.84% increase in network stability compared to baseline load balancing strategies like Fractional Improved Whale Social Optimization Based VM Migration Strategy FIWSOA,HDWOA,and Binary Bird Swap.展开更多
文摘电离层总电子含量(Total Electron Content,TEC)精确预报对提高卫星导航定位精度具有重要意义.为此,提出一种联合鲸鱼优化算法(Whale Optimization Algorithm,WOA)与长短期记忆神经网络模型(Long-Short Term Memory Networks,LSTM)的TEC短期预报模型;该模型通过LSTM模型训练得到WOA算法的最佳适应度,并利用优化的WOA算法得到LSTM模型最优参数.最后,结合欧洲定轨中心(Center for Orbit Determination in Europe,CODE)提供的TEC格网点数据对所提模型进行验证;试验结果表明:地磁平静状态下,组合模型的平均相关系数ρ较LSTM模型在低、中、高纬度分别提升了2.8%、6.2%和14.8%;地磁活跃状态下组合模型的平均相关系数ρ在低、中、高纬度地区较LSTM模型分别提升了6.6%、9.2%与7.9%.且模型预报效果与地磁活跃状态、季节、太阳活跃水平等有关,在不同地磁活跃状态、季节与不同太阳活动水平情况下,组合模型预报效果均优于单一LSTM模型,为电离层TEC预报模型的实际应用提供了参考.
文摘The uncertain nature of mapping user tasks to Virtual Machines(VMs) causes system failure or execution delay in Cloud Computing.To maximize cloud resource throughput and decrease user response time,load balancing is needed.Possible load balancing is needed to overcome user task execution delay and system failure.Most swarm intelligent dynamic load balancing solutions that used hybrid metaheuristic algorithms failed to balance exploitation and exploration.Most load balancing methods were insufficient to handle the growing uncertainty in job distribution to VMs.Thus,the Hybrid Spotted Hyena and Whale Optimization Algorithm-based Dynamic Load Balancing Mechanism(HSHWOA) partitions traffic among numerous VMs or servers to guarantee user chores are completed quickly.This load balancing approach improved performance by considering average network latency,dependability,and throughput.This hybridization of SHOA and WOA aims to improve the trade-off between exploration and exploitation,assign jobs to VMs with more solution diversity,and prevent the solution from reaching a local optimality.Pysim-based experimental verification and testing for the proposed HSHWOA showed a 12.38% improvement in minimized makespan,16.21% increase in mean throughput,and 14.84% increase in network stability compared to baseline load balancing strategies like Fractional Improved Whale Social Optimization Based VM Migration Strategy FIWSOA,HDWOA,and Binary Bird Swap.
