Melt index is the most important indicator of quality in the production process of polypropylene. Because of the constraints of process equipment and technical, the melt index is difficult to measure online. If we directly measure the melt index of the polypropylene product samples, that will result the measurement delay, melt index can not be controlled effectively online. Because the melt index is difficult to measure online, model of melt index prediction based on stacked neural networks was esta...