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虫害检测算法的构建是耦合“地-天”特征的过程,是实现其遥感监测的重要保障。以福建省三明市、将乐县、沙县、南平市延平区等4个县(区、市)为试验区,收集182组马尾松毛虫害样本数据,随机划分为训练集与验证集,设置5次重复试验及1次指标筛除试验。结合马尾松毛虫危害下的寄主表征,获取松林叶面积指数LAI、叶面积指数标准误SEL、归一化差值植被指数NDVI、缨帽变换湿度轴WET及影像绿光波段B2、红光波段B3、近红外波段B4等7个地面与遥感特征指标,建立其危害等级的Fisher判别分析与随机森林模型,从检测精度、Kappa系数、ROC曲线等角度综合比较两种算法的检测效果,并给予配对t检验。结果表明:7个指标均具备虫害响应能力,SEL和NDVI相对较弱;Fisher判别分析6次试验的虫害平均检测精度为73.26%,Kappa系数为0.631 9,而RF法则分别为79.30%,0.715 1,显著优于前者(p<0.05);RF法对无危害、轻度危害、中度危害3个虫害等级的检测精度、Kappa系数、AUC均显著高于Fisher判别分析(p<0.05),对于重度危害等级,Fisher判别分析则占优。总体而言,RF法对马尾松毛虫害的检测效果优于Fisher判别分析,但Fisher判别分析对重度危害等级有更高准确性且模型明确、易于推广,可综合应用两种算法开展虫害监测工作。该成果为马尾松毛虫害及其他森林病虫害的有效检测提供技术参考,奠定其遥感监测的基础。 相似文献
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我们提供了基态和多极(偶极和三极)光束在非局域程度呈垒型分布的非均匀非局域介质中传输的动力学演化行为。在非局域垒的影响下,基态光束会发生周期性振荡,其振荡周期和振荡程度可以由非局域垒的系统参数进行调控。然而,多极光束在非局域垒的影响下会分裂成相应数目的基态光束,分裂形成的各基态光束在传播过程中发生周期性碰撞;通过调控系统参数,其碰撞周期和振荡程度可以被有效控制。 相似文献
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Higher-order nonlinear Schr\"{o}dinger equation with the Hirota
constraint conditions is considered, and an analytic solution, which
can describe the modulational instability process, is presented.
Based on the solution, a new pulse train without continuous wave (CW)
background is generated in quadratures and the propagation of the
pulse train is discussed in detail by simulating numerically. The
results show that, unlike the propagation of the picosecond pulse
train, under the effects of the higher-order terms, the pulse train
cannot propagate along the fibre when the energy is very high;
however, for some medium energy the pulse train can stably propagate.
We also investigate the stability of the pulse train against
violation of the Hirota conditions, and the results show that the
pulse train can still propagate stably when the Hirota conditions are
broken. 相似文献
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Controllable soliton propagation based on phase-front curvature in asymmetrical nonlocal media 下载免费PDF全文
The influence of phase-front curvature on the dynamical behavior of the fundamental mode soliton during its transmission in asymmetrical nonlocal media is studied in detail and the phase-front curvature can be imposed on the fundamental mode soliton by reshaping or phase imprinting technologies. By changing the phase-front curvature or its imposed position,controllable soliton propagation in asymmetrical nonlocal media can be achieved. 相似文献
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HPLC法同时测定淫羊藿中朝藿定A、B、C与淫羊藿苷的含量 总被引:8,自引:0,他引:8
建立了同时测定淫羊藿中朝藿定A、B、C与淫羊藿苷含量的高效液相色谱方法。淫羊藿样品经超声波提取,以50%(φ)乙醇溶液为溶剂,在温度50℃、料液比1∶60条件下超声波提取30 m in,共提取2次。色谱条件:ZORBAX SB-C8色谱柱(5μm,4.6×250 mm);流动相A为乙腈,B为1%乙酸溶液;梯度洗脱;紫外检测波长为270 nm。上述4种类黄酮的标准曲线在6.6~33.0 mg/L(朝藿定A、淫羊藿苷)或6.6~55.0mg/L(朝藿定B、C)范围内呈良好的线性关系(r>0.99);加标回收率在97%~102%之间;相对标准偏差小于2%(n=5)。测得不同产地心叶淫羊藿叶片中4种类黄酮的质量分数差异较大;朝藿定A广泛分布于淫羊藿属中。本方法在淫羊藿药材质量控制中具有一定的参考价值。 相似文献