Fog that refers to the concentration of ice or water droplets in the near surface air is an important short-time meteorological phenomenon. As the measure of visibility of air …
针对视频版权的保护,提出了一种基于改进的JND模型的视频水印算法。此算法首先选取二值图像作为图像水印,利用Logistic混沌映射对图像进行加密;然后对载体视频进行关键帧提取,将提取的帧进行4层小波分解,结合分形理论对小波系数进行D树和R树的存储,并根据人类视觉系统(HVS)提出改进的JND模型,进而将处理后的水印信息按照三个方向自适应的嵌入到D树和R树中。 …
The Arctic near-surface air temperatures are increasing more than twice as fast as the global average–a feature known as Arctic amplification (AA). A modified AA index is …
In a stratified water column, the nitracline is a layer where the nitrate concentration increases below the nutrient-depleted upper layer, exhibiting a strong vertical gradient in …
针对视频版权的保护,提出一种基于Chebyshev混沌神经网络的视频水印算法。首先选取二值图像作为图像水印,利用Chebyshev混沌神经网络对图像进行加密;然后对宿主视频进行分帧处理,通过Henon映射产生混沌序列提取关键帧,同时提取关键帧亮度分量的低频系数,将处理后的图像水印自适应地嵌入小波变换后亮度分量的低频系数中。实验结果表明,该算法具有较好的不可见 …
针对数字图像版权的保护,本文提出了一种小波域内基于分形理论的零水印算法。首先对载体图像进行Haar小波变换,接着对小波低频系数进行分形编码,通过分形匹配获得图像的重要特征信息;然后建立特征信息与图像水印之间的关系,进行水印的双重嵌入;由于算法没有对图像进行任何修改就完成了水印的嵌入,很好地解决水印鲁棒性与不可见性之间的矛盾。仿真实验结果表明,算法对常见的图像 …
Because fog is a high-impact weather phenomenon, there has been increased demand for its accurate prediction. Both surface data and wind profiler data possess great potential for …
The ensemble Kalman filter (EnKF) performs well because that the covariance of background error is varying along time. It provides a dynamic estimate of background error and …
