Low frequency infrasonic waves are emitted during the formation and movement of debris flows, which are detectable in a radius of several kilometers, thereby to serve as the precondition for their remote monitoring.Ho...Low frequency infrasonic waves are emitted during the formation and movement of debris flows, which are detectable in a radius of several kilometers, thereby to serve as the precondition for their remote monitoring.However, false message often arises from the simple mechanics of alarms under the ambient noise interference.To improve the accuracy of infrasound monitoring for early-warning against debris flows, it is necessary to analyze the monitor information to identify in them the infrasonic signals characteristic of debris flows.Therefore, a large amount of debris flow infrasound and ambient noises have been collected from different sources for analysis to sum up their frequency spectra, sound pressures, waveforms, time duration and other correlated characteristics so as to specify the key characteristic parameters for different sound sources in completing the development of the recognition system of debris flow infrasonic signals for identifying their possible existence in the monitor signals.The recognition performance of the system has been verified by simulating tests and long-term in-situ monitoring of debris flows in Jiangjia Gully,Dongchuan, China to be of high accuracy and applicability.The recognition system can provide the local government and residents with accurate precautionary information about debris flows in preparation for disaster mitigation and minimizing the loss of life and property.展开更多
GNSS民用信号因其公开性和脆弱性易受外界欺骗干扰.作为欺骗干扰检测的有效方法,信号质量监测(signal quality monitoring,SQM)技术通过检测接收机跟踪环路早码、即时码、晚码(early late phase,ELP)的相关结果,与无欺骗时的相关特性对...GNSS民用信号因其公开性和脆弱性易受外界欺骗干扰.作为欺骗干扰检测的有效方法,信号质量监测(signal quality monitoring,SQM)技术通过检测接收机跟踪环路早码、即时码、晚码(early late phase,ELP)的相关结果,与无欺骗时的相关特性对比,判断是否存在欺骗干扰.常规SQM算法仅利用ELP三个信息,检测性能受限,为此提出多相关器联合功率(SQM detection of power combined Multi-correlator groups,SPCM)算法.以ELP之间多个等间隔相关器输出功率的加权为检测量,且取相关时刻与即时码时间差的反比为加权系数;进一步分析检测量的概率分布特性,并基于Neyman-Pearson理论确定最佳检测阈值,通过比较检测量与检测阈值的大小,判断是否存在欺骗干扰.基于美国德克萨斯大学奥斯汀分校公开的场景四数据集进行试验,结果表明:与Ratio和ELP等典型SQM算法相比,在不同虚警率条件下,所提出SPCM算法兼具高检测概率和快速预警响应时间性能.展开更多
局部放电检测已成为电缆绝缘在线检测技术的重要内容之一,由于局部放电信号微弱,且易受现场噪声干扰,因此如何准确识别并提取局放信号成为在线监测系统研究的重点和难点。本文通过运用联合抗干扰技术对局放信号进行处理,有效消除干扰并...局部放电检测已成为电缆绝缘在线检测技术的重要内容之一,由于局部放电信号微弱,且易受现场噪声干扰,因此如何准确识别并提取局放信号成为在线监测系统研究的重点和难点。本文通过运用联合抗干扰技术对局放信号进行处理,有效消除干扰并保留原始信号的必要形状特征;采用多相态谱图聚类分析法,从多相态谱图中提取放电特性,为局放在线监测提供判断依据和有效分析手段。经某水电厂330 k V电缆线路局部放电在线监测系统现场应用证明该技术具有较好的实用性和推广性。展开更多
基金supported by the National Science and Technology Support Program(2011BAK12B00)the International Cooperation Project of the Department of Science and Technology of Sichuan Province(2009HH0005)the Project of the Department of Science and Technology of Sichuan Province(2015JY0235)
文摘Low frequency infrasonic waves are emitted during the formation and movement of debris flows, which are detectable in a radius of several kilometers, thereby to serve as the precondition for their remote monitoring.However, false message often arises from the simple mechanics of alarms under the ambient noise interference.To improve the accuracy of infrasound monitoring for early-warning against debris flows, it is necessary to analyze the monitor information to identify in them the infrasonic signals characteristic of debris flows.Therefore, a large amount of debris flow infrasound and ambient noises have been collected from different sources for analysis to sum up their frequency spectra, sound pressures, waveforms, time duration and other correlated characteristics so as to specify the key characteristic parameters for different sound sources in completing the development of the recognition system of debris flow infrasonic signals for identifying their possible existence in the monitor signals.The recognition performance of the system has been verified by simulating tests and long-term in-situ monitoring of debris flows in Jiangjia Gully,Dongchuan, China to be of high accuracy and applicability.The recognition system can provide the local government and residents with accurate precautionary information about debris flows in preparation for disaster mitigation and minimizing the loss of life and property.
文摘GNSS民用信号因其公开性和脆弱性易受外界欺骗干扰.作为欺骗干扰检测的有效方法,信号质量监测(signal quality monitoring,SQM)技术通过检测接收机跟踪环路早码、即时码、晚码(early late phase,ELP)的相关结果,与无欺骗时的相关特性对比,判断是否存在欺骗干扰.常规SQM算法仅利用ELP三个信息,检测性能受限,为此提出多相关器联合功率(SQM detection of power combined Multi-correlator groups,SPCM)算法.以ELP之间多个等间隔相关器输出功率的加权为检测量,且取相关时刻与即时码时间差的反比为加权系数;进一步分析检测量的概率分布特性,并基于Neyman-Pearson理论确定最佳检测阈值,通过比较检测量与检测阈值的大小,判断是否存在欺骗干扰.基于美国德克萨斯大学奥斯汀分校公开的场景四数据集进行试验,结果表明:与Ratio和ELP等典型SQM算法相比,在不同虚警率条件下,所提出SPCM算法兼具高检测概率和快速预警响应时间性能.
文摘局部放电检测已成为电缆绝缘在线检测技术的重要内容之一,由于局部放电信号微弱,且易受现场噪声干扰,因此如何准确识别并提取局放信号成为在线监测系统研究的重点和难点。本文通过运用联合抗干扰技术对局放信号进行处理,有效消除干扰并保留原始信号的必要形状特征;采用多相态谱图聚类分析法,从多相态谱图中提取放电特性,为局放在线监测提供判断依据和有效分析手段。经某水电厂330 k V电缆线路局部放电在线监测系统现场应用证明该技术具有较好的实用性和推广性。
