The possibility of using 209Bi as a new threshold detector to measurc high-energy neutrons was investigated for the first time. At the same time the experiment measured successfully the emitted neutron fiuence rate, e...The possibility of using 209Bi as a new threshold detector to measurc high-energy neutrons was investigated for the first time. At the same time the experiment measured successfully the emitted neutron fiuence rate, energy spectrum and dose equivalent rate distributions in the heavy ion target area using a detector complex including 209Bi, 115In, 27A1, 19F and 12C samples.展开更多
Spectrum sensing is the first step of cognitive radio （CR）. In this area, previous researches mostly consider distributed local nodes which are under identical channel conditions, hence uniform and fixed detection t...Spectrum sensing is the first step of cognitive radio （CR）. In this area, previous researches mostly consider distributed local nodes which are under identical channel conditions, hence uniform and fixed detection threshold is set with energy detector. However, the distributions of nodes in real environments are not quite the same. In this paper, the optimal threshold to minimize the total detection error over add＇itive white Gaussion noise （AWGN） channel is derived firstly. Then the dynamic threshold scheme is proposed to reduce the average total detection error. Simulations have shown that, with this scheme, sensing performance is improved.展开更多
主要研究设备异常度的检测问题。在无故障样本的情况下,如何快速检测设备异常度已经成为状态检测的重要问题。为此,提出一种用于设备异常和异常度检测的信息匹配检测方法——可变阈值信息检测器(Variable threshold information detecto...主要研究设备异常度的检测问题。在无故障样本的情况下,如何快速检测设备异常度已经成为状态检测的重要问题。为此,提出一种用于设备异常和异常度检测的信息匹配检测方法——可变阈值信息检测器(Variable threshold information detector,VTI-detector),在分析分散增量理论并提出数据分布相亲有限信息密度概念的基础上,计算了每个正常训练样本对自己样本(正常样本)的匹配阈值,建立了带有匹配阈值信息的矩阵,即确立VTI-detector。最后利用确立的VTI-detector,结合相亲有限信息密度的概念,提出了设备异常度的计算公式。以UCI数据库中的Iris数据集为例,将所提出的异常检测方法与其他三种常用的异常检测方法进行对比,显示VTI-detector具有比其他方法更好的检测性能。利用异常度公式在线计算轴承正常和各种故障状态的异常度,并以异常度曲线的形式进行显示,结果表明故障异常度检测效果明显,具有较好的应用前景。展开更多
基金Supported by the National Natural Science Foundation of China(19875070)
文摘The possibility of using 209Bi as a new threshold detector to measurc high-energy neutrons was investigated for the first time. At the same time the experiment measured successfully the emitted neutron fiuence rate, energy spectrum and dose equivalent rate distributions in the heavy ion target area using a detector complex including 209Bi, 115In, 27A1, 19F and 12C samples.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municiplity (Grant No.08DZ2231100)the National Natural Science Foundation of China (Grant No.60872021)
文摘Spectrum sensing is the first step of cognitive radio （CR）. In this area, previous researches mostly consider distributed local nodes which are under identical channel conditions, hence uniform and fixed detection threshold is set with energy detector. However, the distributions of nodes in real environments are not quite the same. In this paper, the optimal threshold to minimize the total detection error over add＇itive white Gaussion noise （AWGN） channel is derived firstly. Then the dynamic threshold scheme is proposed to reduce the average total detection error. Simulations have shown that, with this scheme, sensing performance is improved.
文摘主要研究设备异常度的检测问题。在无故障样本的情况下,如何快速检测设备异常度已经成为状态检测的重要问题。为此,提出一种用于设备异常和异常度检测的信息匹配检测方法——可变阈值信息检测器(Variable threshold information detector,VTI-detector),在分析分散增量理论并提出数据分布相亲有限信息密度概念的基础上,计算了每个正常训练样本对自己样本(正常样本)的匹配阈值,建立了带有匹配阈值信息的矩阵,即确立VTI-detector。最后利用确立的VTI-detector,结合相亲有限信息密度的概念,提出了设备异常度的计算公式。以UCI数据库中的Iris数据集为例,将所提出的异常检测方法与其他三种常用的异常检测方法进行对比,显示VTI-detector具有比其他方法更好的检测性能。利用异常度公式在线计算轴承正常和各种故障状态的异常度,并以异常度曲线的形式进行显示,结果表明故障异常度检测效果明显,具有较好的应用前景。
