基于小波和深度小波自编码器的轴承故障诊断

针对滚动轴承故障严重程度与复合故障难以准确识别的问题，提出了一个基于提升双树复小波包（Lifting Dual-Tree Complex Wavelet Packet，LDTCWP）和深度小波自编码器（Deep Wavelet Auto-Encoder，DWAE）的轴承故障诊断方法。首先，使用迁移学习扩展目标数据量；其次，对轴承振动数据进行3层提升双数复小波包分解，分别计算各子频带信号的样本熵、排列熵和能量矩，作为初始特征向量；最后，将初始特征向量输入DWAE，进行二次特征提取并实现故障诊断。实验结果表明，该方法能有效地对滚动轴承进行多种故障类型和多种故障程度的识别，与传统机器学习方法相比，在目标数据较少的情况下也具有较强的泛化能力、特征提取能力和识别能力

Visual analytics towards big data

可视分析是大数据分析的重要方法。大数据可视分析旨在利用计算机自动化分析能力的同时，充分挖掘人对于可视化信息的认知能力优势，将人、机的各自强项进行有机融合，借助人机交互式分析方法和交互技术，辅助人们更为直观和高效地洞悉大数据背后的信息、知识与智慧。主要从可视分析领域所强调的认知、可视化、人机交互的综合视角出发，分析了支持大数据可视分析的基础理论，包括支持分析过程的认知理论、信息可视化理论、人机交互与用户界面理论。在此基础上，讨论了面向大数据主流应用的信息可视化技术--面向文本、网络(图)、时空、多维的可视化技术。同时探讨了支持可视分析的人机交互技术，包括支持可视分析过程的界面隐喻与交互组件、多尺度/多焦点/多侧面交互技术、面向 Post-WIMP 的自然交互技术。最后，指出了大数据可视分析领域面临的瓶颈问题与技术挑战。 Visual analytics is an important method used in big data analysis. The aim of big data visual analytics is to take advantage of human’s cognitive abilities in visualizing information while utilizing computer’s capability in automatic analysis. By combining the advantages of both human and computers, along with interactive analysis methods and interaction techniques, big data visual analytics can help people to understand the information, knowledge and wisdom behind big data directly and effectively. This article emphasizes on the cognition, visualization and human computer interaction. It first analyzes the basic theories, including cognition theory, information theory, interaction theory and user interface theory. Based on the analysis, the paper discusses the information visualization techniques used in mainstream applications of big data, such as text visualization techniques, network visualization techniques, spatio-temporal visualization techniques and multi-dimensional visualization techniques. In addition, it reviews the interaction techniques supporting visual analytics, including interface metaphors and interaction components, multi-scale/multi-focus/multi-facet interaction techniques, and natural interaction techniques faced on Post-WIMP. Finally, it discusses the bottleneck problems and technical challenges of big data visual analytics.Visual analytics is an important method used in big data analysis. The aim of big data visual analytics is to take advantage of human's cognitive abilities in visualizing information while utilizing computer's capability in automatic analysis. By combining the advantages of both human and computers, along with interactive analysis methods and interaction techniques, big data visual analytics can help people to understand the information, knowledge and wisdom behind big data directly and effectively. This article emphasizes on the cognition, visualization and human computer interaction. It first analyzes the basic theories, including cognition theory, information theory, interaction theory and user interface theory. Based on the analysis, the paper discusses the information visualization techniques used in mainstream applications of big data, such as text visualization techniques, network visualization techniques, spatio-temporal visualization techniques and multi-dimensional visualization techniques. In addition, it reviews the interaction techniques supporting visual analytics, including interface metaphors and interaction components, multi-scale/multi-focus/multi-facet interaction techniques, and natural interaction techniques faced on Post-WIMP. Finally, it discusses the bottleneck problems and technical challenges of big data visual analytics

Human-Computer Interaction Based on Semantic Focus+Context for Information Visualization

大数据成为继云计算和物联网之后,国际学术界和产业界所共同瞩目的又一个研究热点.信息可视化是辅助用户洞悉大数据背后隐藏的知识和规律的重要方法和有力 工具.如何在图形用户界面中对大规模信息以符合认知规律的方式进行可视化,并且使得计算机能够智能化的理解用户意图以配合其进行高效的人机交互,是信息可 视化面临的挑战之一.文中提出一种面向信息可视化的语义Focus+Context人机交互技术.首先,在基于空间距离的经典Focus+Context 数学模型基础上对其进行语义建模和扩展,建立了面向信息空间和可视化表征空间的语义距离模型以及语义关注度模型,定义了交互中的焦点对象与语义上下文.其 次,在此基础上建立了语义Fcous + Conext用户界面模型,给出了界面抽象元素和实体元素以及映射关系的形式化描述,同时建立了Focus+Context交互循环机制.最后,给出了应 用于经典Focus+Context及鱼眼数学模型的描述,表明文中提出方法具有很好的兼容性描述能力;同时,给出了面向文件系统主题聚集的语义Focu s+Context应用,给出了基于主题语义关注度与嵌套圆鱼眼视图的动态可视化实例,应用实例表明文中提出技术能够有效支持用户在信息可视化界面中对大 规模信息进行智能化的可视化和交互探索.Big data has become another revolutionary technology following the booming of cloud computing and internet of things. Information visualization is regarded as an essential approach and powerful tool for users to get insight from big data. However, great challenges still exist in information visualization and smart interaction in small interfaces according to cognitive law. This paper proposes a semantic Focus+Context interaction technology for information visualization in user interface. Firstly, a semantic distance model and a semantic Degree -Of-Interest (DOI) model towards information space and visual representation space are presented. And based on the models, semantic context related to a focus is defined. Secondly, the paper proposes a semantic Focus + Context based user interface model, defining both abstract and entity elements as well as the mappings in this kind of user interface. Finally, the proposed technology is applied to semantic theme clustering for exploration of large scale file systems. Application examples show that the proposed technology can effectively support large scale information visualization in small interface and intelligent interaction for semantic exploration of complex data

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies