A reflectance spectra-based approach to mapping salt fields using PCA-fused Landsat TM data

In this paper a method based on in situ measured reflectance spectra was developed for accurately mapping salt fields in the Taibei Salt Farm in Lianyungang City of East China. After radiometric correction and geometric rectification, six multispectral ETM+ bands were fused with the panchromatic band via principal components analysis (PCA). The fused data were used to map salt fields in the farm. Salt fields were mapped 91.95% correctly in comparison with ground statistics from raw multispectral bands. This accuracy level rose to 96.4% with the use of the panchromatic band (15 m resolution). However, PCA-fused data produced the highest accuracy of 98.8%. At the zone level, coarse resolution data resulted in an accuracy of 98.93% for crystallization ponds, but only 82.68% for condensation ponds. Use of the panchromatic band alone improved the accuracy for condensation ponds but decreased the accuracy for crystallization and evaporation ponds. Results derived from PCA-fused data are highly consistent with the ground statistics at a discrepancy between 0.35% for evaporation zone and 1.80% for condensation zone. It is concluded that a fine spectral resolution is important to separation of ponds of a varying salt content while a fine spatial resolution is important to their mapped area. Ponds of a lower salt content can be mapped more accurately from fused data than from raw spectral bands.     

航空备件共享与租赁的经济意义

航空备件共享与租赁可削减航空公司的库存费用。持续降低成本的压力及越来越多的航空公司对非核心业务外包做法的认可正激发起人们对此项商业活动的兴趣。     

Haze removal for UAV reconnaissance images using layered scattering model

During the unmanned aerial vehicles(UAV) reconnaissance missions in the middle-low troposphere, the reconnaissance images are blurred and degraded due to the scattering process of aerosol under fog, haze and other weather conditions, which reduce the image contrast and color fidelity. Considering the characteristics of UAV itself, this paper proposes a new algorithm for dehazing UAV reconnaissance images based on layered scattering model. The algorithm starts with the atmosphere scattering model, using the imaging distance, squint angle and other metadata acquired by the UAV. Based on the original model, a layered scattering model for dehazing is proposed. Considering the relationship between wave-length and extinction coefficient, the airlight intensity and extinction coefficient are calculated in the model. Finally, the restored images are obtained. In addition, a classification method based on Bayesian classification is used for classification of haze concentration of the image, avoiding the trouble of manual working. Then we evaluate the haze removal results according to both the subjective and objective criteria. The experimental results show that compared with the origin image, the comprehensive index of the image restored by our method increases by 282.84%, which proves that our method can obtain excellent dehazing effect.     

仓容与资金约束下多项物品联合订购近优策略的确定

本文讨论在存在仑容与资金约束的条件下,如何确定多项物品联合订购的近优库存控制策略。根据本文所建立的决策模型开发了计算机软件,并给出了例题求解结果。     

基于支持向量机和线性判别分析的维数约减方法及其应用

目前已提出的一些基于支持向量机的维数约减方法,但其投影矩阵的获得仅考虑支持向量机的类间间隔,而忽略了数据中的类内信息。本文首次提出了一种基于支持向量机和线性判别分析的维数约减方法,称之为DRSL。DRSL实现了类问和类内信息的有效组合,能有效拟合数据中类间和类内结构,使得所获投影矩阵能够提高后续分类器的推广能力。实验验证了该方法的有效性。     

基于神经网络模型的层次诊断方法及应用

对神经网络和故障诊断的层次分解模型进行了研究,把神经网络技术和层次分解模型相结合,利用神经网络来实现分层诊断。以卫星能源系统为背景,建立了该系统故障模拟试验台的层次分解模型,在此基础上构造了合适的分层神经网络,通过分层神经网络诊断系统故障,给出的两个实例说明了这种方法的有效性。     

基于三站点库存组织的备件转运策略分析

基于三站点库存组织研究了备件转运策略对于系统期望延期交货量（EBO）的影响。首先,依据三站点库存组织中备件和故障件的消耗与补给过程以及库存控制策略,给出了考虑保障站点供应优先级的手边现货、应得备件数和延期交货量之间的状态方程。其次,通过定义站点延期交货量与应得备件数之间的比例系数,将原非线性方程组转化成线性方程组,然后借助线性方程组解的判定法则对方程组解的唯一性进行判定,并结合不动点原理构造柯西列逼近原方程的解。最后,在算例分析中借助MATLAB对2种转运策略（按固定概率转运和按优先级约束转运）下系统EBO的数值大小进行对比。结果表明:按优先级约束进行备件转运能够在大部分情况下提高备件利用率同时降低系统EBO。此外,通过分析还可以发现,不同备件转运策略对系统EBO作用效果的显著性主要由转运策略的可行作用空间大小决定,而作用空间的可行变化范围主要由备件需求由本地满足的概率、库存配置方案以及需求率和维修速率决定。      

基于FRFT域特征差异的压制干扰检测与分类算法

针对干信比未知情况下有源压制干扰分类识别结果可信度较低的问题, 提出了一种基于FRFT域特征差异的压制干扰检测与分类算法。首先, 通过FRFT域峰值阶次的序贯判决算法, 进行压制干扰的存在性检测, 以保证压制干扰分类识别在较高的干信比条件下进行; 然后, 在此基础上, 分别提取回波信号在FRFT域的极值阶次标准差和峰值阶次标准差作为分类识别特征量, 同时, 为避免硬判决造成的分类错误, 采用模糊判决的方法得到基于不同特征参数的分类识别结果; 最后, 按一定准则将2种分类识别结果进行融合, 以进一步提高分类识别正确率。仿真结果表明, 与现有压制干扰分类识别算法相比, 该算法较好地解决了分类识别结果可信度较低的问题, 同时具有较高的分类识别正确率。      

SAM在CMODIS数据信息提取中的应用

中国首次上天的中等分辨率成像光谱仪 (CMODIS)数据具有 34谱段 ,包含了从可见光、近红外、短波红外至热红外波段非常丰富的波谱信息。但是CMODIS波段间相关性很高 ,而且数据量很大 ,若用传统的基于数理统计的分类方法 (如监督和非监督分类方法 )提取信息会有一定的困难。光谱角度制图法(SAM)是通过计算 1个测试光谱 (像元光谱 )与 1个参考光谱之间的“角度”来确定它们两者之间的相似性 ,从而达到分类目的。这一方法更符合高光谱数据的特点。文章对 2 0 0 2年 5月 2 2日取得的前 2 0个波段的CMODIS数数据分别采用监督分类方法和光谱角度制图 (SAM)法提取信息。试验结果表明采用SAM得到了比监督分类方法更好的分类效果和更多的信息。     

基于非线性神经网络的高清晰高光谱遥感图像分类器设计与应用

对于高光谱和空间分辨率的遥感图像而言，它具有较为复杂的地物判读特性，应用常规的监督或非监督分类方法难以达到理想的结果。为此设计了一种非线性BP网络分类器，它将纹理结构特征与地物光谱特征相结合．针对上海市某地区的卫星遥感图像．在ENVI／IDL平台上与K-means的非监督分类和最小距离的监督分类方法进行了分类的对比应用。试验结果表明．该分法较好地考虑了图像的光谱特征，能有效地提高类别辨识的精度。