由于相位敏感光时域反射仪(Φ-OTDR,Phase-sensitive Optical Time Domain Reflectometer)光纤预警系统高灵敏度的特性,使其对于环境中的声波及瞬时高频噪声也异常敏感,如何提高信噪比,使有用信号在众多噪声中显现出来,实现精确定位,成...由于相位敏感光时域反射仪(Φ-OTDR,Phase-sensitive Optical Time Domain Reflectometer)光纤预警系统高灵敏度的特性,使其对于环境中的声波及瞬时高频噪声也异常敏感,如何提高信噪比,使有用信号在众多噪声中显现出来,实现精确定位,成为该领域研究的关键问题。分析了Φ-OTDR分布式光纤系统的工作原理,介绍了分离平均与差分、滑动平均与差分以及小波阈值去噪三种常用的定位算法。利用连续小波变换分析了挖掘信号的功率谱分布随距离传播的变化规律,并提出了一种利用小波高频分量进行定位的算法方案。实验证明小波高频分量定位算法具有更高的定位精度,信噪比为9.6033dB。展开更多
Surveying and early detection of invasive weeds are essential for strategic management and monitoring. Accordingly, a weed mapping was conducted during July 2011, against native （Orobanche ramosa, Cuscuta spp., Sorgh...Surveying and early detection of invasive weeds are essential for strategic management and monitoring. Accordingly, a weed mapping was conducted during July 2011, against native （Orobanche ramosa, Cuscuta spp., Sorghum halepense and Xanthium strumarium） and non native （Abutilon theophrasti, Datura stramonium, Solanum elaeagnifolium and Verbesina encelioide） weeds of Lebanon. A global positioning system （Garmin 2006） was used for precise waypoint, elevation, navigation and distance. The result of interviewing and interacting with the residents in 95 villages distributed between the Beq＇aa and the North governorates of Lebanon, along with the observations made on the route, yielded the first detection of Abutilon theophrasti in both governorates. Solanum elaeagnifolium and Verbesina encelioide were not found in the agro-ecosystems of either governorates. This is the first report of the introduction ofAbutilon theophrasti in Lebanon and the establishment of a baseline data on weeds of Lebanon. The adoption of an integrated weed management program with a quarantine and control techniques and methods is needed to manage the spreading of weeds and to lessen their ability to adapt to a constantly changing system which uses several control practices.展开更多
文摘由于相位敏感光时域反射仪(Φ-OTDR,Phase-sensitive Optical Time Domain Reflectometer)光纤预警系统高灵敏度的特性,使其对于环境中的声波及瞬时高频噪声也异常敏感,如何提高信噪比,使有用信号在众多噪声中显现出来,实现精确定位,成为该领域研究的关键问题。分析了Φ-OTDR分布式光纤系统的工作原理,介绍了分离平均与差分、滑动平均与差分以及小波阈值去噪三种常用的定位算法。利用连续小波变换分析了挖掘信号的功率谱分布随距离传播的变化规律,并提出了一种利用小波高频分量进行定位的算法方案。实验证明小波高频分量定位算法具有更高的定位精度,信噪比为9.6033dB。
文摘Surveying and early detection of invasive weeds are essential for strategic management and monitoring. Accordingly, a weed mapping was conducted during July 2011, against native （Orobanche ramosa, Cuscuta spp., Sorghum halepense and Xanthium strumarium） and non native （Abutilon theophrasti, Datura stramonium, Solanum elaeagnifolium and Verbesina encelioide） weeds of Lebanon. A global positioning system （Garmin 2006） was used for precise waypoint, elevation, navigation and distance. The result of interviewing and interacting with the residents in 95 villages distributed between the Beq＇aa and the North governorates of Lebanon, along with the observations made on the route, yielded the first detection of Abutilon theophrasti in both governorates. Solanum elaeagnifolium and Verbesina encelioide were not found in the agro-ecosystems of either governorates. This is the first report of the introduction ofAbutilon theophrasti in Lebanon and the establishment of a baseline data on weeds of Lebanon. The adoption of an integrated weed management program with a quarantine and control techniques and methods is needed to manage the spreading of weeds and to lessen their ability to adapt to a constantly changing system which uses several control practices.
