A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste...A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit （LEO） satellite IP networks. The CCST algorithm includes the dynamic approximate center （DAC） core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation, the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization. Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay ofw-CCST algorithm is lower than that of the CCST algorithm.展开更多
堆芯应急排盐系统作为熔盐堆特有的安全系统,具有排盐和余热排出功能,为熔盐堆提供了一种紧急停堆方式。为定量化分析堆芯应急排盐系统的可靠性,以美国橡树岭实验室的熔盐实验堆(Molten Salt Reactor Experiment,MSRE)为研究对象,使用...堆芯应急排盐系统作为熔盐堆特有的安全系统,具有排盐和余热排出功能,为熔盐堆提供了一种紧急停堆方式。为定量化分析堆芯应急排盐系统的可靠性,以美国橡树岭实验室的熔盐实验堆(Molten Salt Reactor Experiment,MSRE)为研究对象,使用概率安全分析软件RiskSpectrum建立和计算MSRE堆芯应急排盐系统故障树,得到系统失效概率为5.62×10^(-4),并进行最小割集分析和重要度分析,识别出影响系统失效的关键因素是外套管泄漏失效、控制冷冻阀冷却气的电磁阀共因失效和气动阀共因失效。通过套管换热元件中减少使用焊缝连接,以及采用不同类型部件控制冷冻阀冷却气,可明显降低系统失效概率。分析结果为液态熔盐堆应急排盐系统工程应用研究提供参考。展开更多
区分配电网中发生的单相接地故障类型,能够有针对性地制定故障检修策略,提升故障处置效率。配电自动化设备作为配电网故障快速辨识与处理的重要载体,对故障分类的原理及效果差异性较大,准确率无法满足电力系统工作需求,为此提出一种基...区分配电网中发生的单相接地故障类型,能够有针对性地制定故障检修策略,提升故障处置效率。配电自动化设备作为配电网故障快速辨识与处理的重要载体,对故障分类的原理及效果差异性较大,准确率无法满足电力系统工作需求,为此提出一种基于分类回归树与多核残差网络(classfication and regression tree and multi-core ResNet, CART-MRN)的树状结构故障类型识别方法。首先,建立树状故障分类结构,利用Fourier变换、经验模态分解(empirical mode decompsition, EMD)分解等方法提取故障点电压电流的多域故障特征;其次,结合特征分析与信息增益建立适应不同小电流接地系统的融合算法模型,并引入粒子群算法优化网络超参数;最后,通过现场录波数据验证与对比实验,证明该方法能快速、有效地完成单相接地故障分类识别,且更具有适应性。展开更多
基金National Natural Science Foundation of China （60532030, 10577005, 60625102） Innovation Foundation of Aerospace Science and Technology of China
文摘A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit （LEO） satellite IP networks. The CCST algorithm includes the dynamic approximate center （DAC） core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation, the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization. Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay ofw-CCST algorithm is lower than that of the CCST algorithm.
文摘堆芯应急排盐系统作为熔盐堆特有的安全系统,具有排盐和余热排出功能,为熔盐堆提供了一种紧急停堆方式。为定量化分析堆芯应急排盐系统的可靠性,以美国橡树岭实验室的熔盐实验堆(Molten Salt Reactor Experiment,MSRE)为研究对象,使用概率安全分析软件RiskSpectrum建立和计算MSRE堆芯应急排盐系统故障树,得到系统失效概率为5.62×10^(-4),并进行最小割集分析和重要度分析,识别出影响系统失效的关键因素是外套管泄漏失效、控制冷冻阀冷却气的电磁阀共因失效和气动阀共因失效。通过套管换热元件中减少使用焊缝连接,以及采用不同类型部件控制冷冻阀冷却气,可明显降低系统失效概率。分析结果为液态熔盐堆应急排盐系统工程应用研究提供参考。
文摘区分配电网中发生的单相接地故障类型,能够有针对性地制定故障检修策略,提升故障处置效率。配电自动化设备作为配电网故障快速辨识与处理的重要载体,对故障分类的原理及效果差异性较大,准确率无法满足电力系统工作需求,为此提出一种基于分类回归树与多核残差网络(classfication and regression tree and multi-core ResNet, CART-MRN)的树状结构故障类型识别方法。首先,建立树状故障分类结构,利用Fourier变换、经验模态分解(empirical mode decompsition, EMD)分解等方法提取故障点电压电流的多域故障特征;其次,结合特征分析与信息增益建立适应不同小电流接地系统的融合算法模型,并引入粒子群算法优化网络超参数;最后,通过现场录波数据验证与对比实验,证明该方法能快速、有效地完成单相接地故障分类识别,且更具有适应性。
