Simultaneous perturbation stochastic approximation （SPSA） belongs to the class of gradient-free optimization methods that extract gradient information from successive objective function evaluation. This paper descri...Simultaneous perturbation stochastic approximation （SPSA） belongs to the class of gradient-free optimization methods that extract gradient information from successive objective function evaluation. This paper describes an improved SPSA algorithm, which entails fuzzy adaptive gain sequences, gradient smoothing, and a step rejection procedure to enhance convergence and stability. The proposed fuzzy adaptive simultaneous perturbation approximation （FASPA） algorithm is particularly well suited to problems involving a large number of parameters such as those encountered in nonlinear system identification using neural networks （NNs）. Accordingly, a multilayer perceptron （MLP） network with popular training algorithms was used to predicate the system response. We found that an MLP trained by FASPSA had the desired accuracy that was comparable to results obtained by traditional system identification algorithms. Simulation results for typical nonlinear systems demonstrate that the proposed NN architecture trained with FASPSA yields improved system identification as measured by reduced time of convergence and a smaller identification error.展开更多
无线监测网络中多电台监测节点通过捕捉和分析无线用户的通信数据,可以达到监测网络行为、诊断网络故障和管理网络资源的目的,而为多电台监测节点优化选择工作信道、最大化捕获数据量、获得最佳网络监测质量(quality of monitoring,QoM...无线监测网络中多电台监测节点通过捕捉和分析无线用户的通信数据,可以达到监测网络行为、诊断网络故障和管理网络资源的目的,而为多电台监测节点优化选择工作信道、最大化捕获数据量、获得最佳网络监测质量(quality of monitoring,QoM)是一个关键问题。文章研究了一种基于同步微扰随机近似(SPSA)的信道选择算法。该算法在迭代过程中以随机扰动策略得到目标函数的近似梯度,引导搜索过程逐步逼近最优解;适合于复杂的多维优化问题求解,收敛速度快、复杂度低。实验结果表明,该算法可以实现无线监测网络中多电台监测节点的信道优化选择,并且性能优良。展开更多
首先回顾了地震概率安全评价(Seismic Probability Safety Assessment,SPSA)方法的发展历史及应用现状;然后基于SPSA的要素,研究了SPSA方法中需要解决的主要问题,重点是地震易损性分析,并根据SPSA的任务描述SPSA流程,主要探讨电厂走访...首先回顾了地震概率安全评价(Seismic Probability Safety Assessment,SPSA)方法的发展历史及应用现状;然后基于SPSA的要素,研究了SPSA方法中需要解决的主要问题,重点是地震易损性分析,并根据SPSA的任务描述SPSA流程,主要探讨电厂走访和继电器评价的方法;最后结合我国概率安全评价(Probability Safety Assessment,PSA)的研究进展、SPSA的基础等实际状况,提出适合我国的SPSA实施路线的建议,以保障核电站地震情况下的安全。展开更多
文摘Simultaneous perturbation stochastic approximation （SPSA） belongs to the class of gradient-free optimization methods that extract gradient information from successive objective function evaluation. This paper describes an improved SPSA algorithm, which entails fuzzy adaptive gain sequences, gradient smoothing, and a step rejection procedure to enhance convergence and stability. The proposed fuzzy adaptive simultaneous perturbation approximation （FASPA） algorithm is particularly well suited to problems involving a large number of parameters such as those encountered in nonlinear system identification using neural networks （NNs）. Accordingly, a multilayer perceptron （MLP） network with popular training algorithms was used to predicate the system response. We found that an MLP trained by FASPSA had the desired accuracy that was comparable to results obtained by traditional system identification algorithms. Simulation results for typical nonlinear systems demonstrate that the proposed NN architecture trained with FASPSA yields improved system identification as measured by reduced time of convergence and a smaller identification error.
文摘无线监测网络中多电台监测节点通过捕捉和分析无线用户的通信数据,可以达到监测网络行为、诊断网络故障和管理网络资源的目的,而为多电台监测节点优化选择工作信道、最大化捕获数据量、获得最佳网络监测质量(quality of monitoring,QoM)是一个关键问题。文章研究了一种基于同步微扰随机近似(SPSA)的信道选择算法。该算法在迭代过程中以随机扰动策略得到目标函数的近似梯度,引导搜索过程逐步逼近最优解;适合于复杂的多维优化问题求解,收敛速度快、复杂度低。实验结果表明,该算法可以实现无线监测网络中多电台监测节点的信道优化选择,并且性能优良。
