According to the unique problem of sample data in ash prediction model based on near infrared spectroscopy. an optimization method was proposed. Principal component analysis method is used for eliminating abnormal samples in coal sample set and extracting feature information of coal spectrum. A double-level clustering method is presented which integrates self-organize map neural netwo... https://www.roneverhart.com/Tasoliesi-Hackman-RTL-6-levyinen-15kW/