森林优化特征选择算法的增强与扩展

特征选择作为一种重要的数据预处理方法,不但能解决维数灾难问题,还能提高算法的泛化能力.各种各样的方法已被应用于解决特征选择问题,其中,基于演化计算的特征选择算法近年来获得了更多的关注并取得了一些成功.近期研究结果表明,森林优化特征选择算法具有更好的分类性能及维度缩减能力.然而,初始化阶段的随机性、全局播种阶段的人为参数设定,影响了该算法的准确率和维度缩减能力;同时,算法本身存在着高维数据处理能力不足的本质缺陷.从信息增益率的角度给出了一种初始化策略,在全局播种阶段,借用模拟退火控温函数的思想自动生成参数,并结合维度缩减率给出了适应度函数;同时,针对形成的优质森林采取贪心算法,形成一种特征选择算法EFSFOA(enhanced feature selection using forest optimization algorithm).此外,在面对高维数据的处理时,采用集成特征选择的方案形成了一个适用于EFSFOA的集成特征选择框架,使其能够有效处理高维数据特征选择问题.通过设计对比实验,验证了EFSFOA与FSFOA相比在分类准确率和维度缩减率上均有明显的提高,高维数据处理能力更是提高到了100 000维.将EFSFOA与近年来提出的比较高效的基于演化计算的特征选择方法进行对比,EFSFOA仍具有很强的竞争力.

Image segmentation method for coal particle size distribution analysis

Particle size distribution is extremely important in the coal preparation industry.It is traditionally analysed by a manual screening method,which is relatively time-consuming and cannot immediately guide production.In this paper,an image segmentation method for images of coal particles is proposed.It employs the watershed algorithm,k-nearest neighbour algorithm,and convex shell method to achieve preliminary segmentation,merge small pieces with large pieces,and split adhered particles,respectively.Comparing the automated segmentation using this method with manual segmentation,it is found that the results are comparable.The size distributions obtained by the automated and manual segmentation methods are nearly identical,and the standard deviation is less than 3%,indicating good reliability.This automated image segmentation method provides a new approach for rapidly analysing the size distribution of coal particles with size fractions defined according to consumer requirements.