A spread spectrum steganalysis algorithm based on discontinuity detection

A novel audio steganalysis method is proposed.. the audio signal is denoised with wavelet transform. Then, a part of noise signal with different length is intercepted circularly and is used to calculate the cross correlation sequence with the rest of the noise signal. With the wavelet discontinuity detection technique, the feature is extracted from the cross correlation sequence for steganalysis and find out the steg audio. The detection rate is determined by the embedding strength of the secret message other than the embedding capacity. Experimental results show that the more embedding intensity of PN sequence is, the higher the detection rate will be. The detection rate of the algorithm is above 80% when the strength of the PN sequence is about 0.002, which demonstrates that the proposed algorithm has good detection performance.     

The spatial distribution estimation of Interference temperature based on kriging method in cognitive radio

In order to resolve the problems of the traditional interference temperature estimation methods, such as unclear spatial characteristics, inaccurate estimation of spatial distribution, and the insufficient use of spectrum resources, this paper proposes an estimation method which utilizes the interference temperature sample values obtained by wireless sensors distribute in space to estimate the interference temperature in the total area. This method makes use of the geo-statistical interpolation method of Kriging to calculate the interference temperature data and obtain the 3-dimensional distribution of the interference temperature in the area. Kriging interpolation method is based on the variogram and structure analysis theory, makes optimal estimation of the variables in area. Simulation results demonstrate that the proposed method can estimate the spatial distribution of interference temperature in the interested area more accurately and the spatial spectrum utilization is improved.     

A cooperative localization algorithm for wireless sensor networks

Aiming at the shortcomings of the existing RSS(received signal strength) based localization algorithm for wireless sensor networks (WSN), a cooperative localization algorithm (CLA) is proposed. A reference anchor node is introduced to tolerant some minor error including the node position error. Dixon detection method is applied to remove abnormal RSS values, while the standard deviation threshold of RSS and learning model are introduced to reduce the RSS ranging error and effectively improve the precision. Simulation experiments are performed to evaluate the performance of the proposed algorithm. The results demonstrate that the localization accuracy is improved effectively, while the stability and robustness are better.     

日光诱导叶绿素荧光遥感探测的研究进展

对陆地植被的生物物理参数和生物化学参数进行反演,对夫琅禾费暗线中的叶绿素荧光信号进行提取是植被高光谱遥感的三项基本任务。鉴于叶绿素荧光与光合作用存在密切的联系,叶绿素荧光参数和稳态荧光光谱特征在植物健康状况的评价,环境胁迫因子的早期检测应用中表现出很大潜力,围绕叶绿素荧光遥感的研究快速发展起来。本文结合国内外最新的研究进展对稳态荧光的光谱特征及其产生机理;日光诱导叶绿素荧光信号的检测方法;遥感探测器的类型及工作原理;叶绿素荧光的建模与仿真现状进行了综述;也对叶绿素荧光在非生物胁迫子早期检测、植物病害监测与病情评估领域中的应用进行了综述;对叶绿素荧光遥感研究工作的重点作了展望。