Zhangzhen Sun¹, Tianhe Xu^1,*, Fan Gao¹, Chunhua Jiang¹, Guochang Xu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.119, No.2, pp. 263-280, 2019, DOI:10.32604/cmes.2019.04425

Abstract Abnormal effects in GPS broadcast ephemerides can have a significant effect on real-time navigation and positioning solutions that use the orbit and clock error data provided by GPS broadcast ephemerides. This paper describes three types of non-integer-hour navigation data in GPS broadcast ephemeris data. Compared with GPST integer hour data, we find that there are two types of data blocks for non-integer-hour navigation containing gross errors with different levels of precision, which is reflected in the user range accuracy (URA) of the broadcast ephemeris. These gross errors can cause large deviations when using the GPS broadcast ephemeris for orbit calculation… More >

Manyu Jin¹, Tao Wang¹, Zexuan Ji^1,*, Xiaobo Shen²

CMC-Computers, Materials & Continua, Vol.56, No.3, pp. 501-515, 2018, DOI: 10.3970/cmc.2018.02371

Abstract Perceptual image quality assessment (IQA) is one of the most indispensable yet challenging problems in image processing and computer vision. It is quite necessary to develop automatic and efficient approaches that can accurately predict perceptual image quality consistently with human subjective evaluation. To further improve the prediction accuracy for the distortion of color images, in this paper, we propose a novel effective and efficient IQA model, called perceptual gradient similarity deviation (PGSD). Based on the gradient magnitude similarity, we proposed a gradient direction selection method to automatically determine the pixel-wise perceptual gradient. The luminance and chrominance channels are both took… More >