BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
@booklet{EasyChair:1831,
author = {Peng He and Ge Chen and Kai Deng and Ping Yao and Li Fu},
title = {Improve Image Classication by Convolutional Network on Cambricon},
howpublished = {EasyChair Preprint 1831},
year = {EasyChair, 2019}}