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In the Global Navigation Satellite System (GNSS) community, the Quasi-Zenith Satellite System (QZSS) is an augmentation system for users in the Asia-Pacific region. However, the characteristics and performance of four QZSS satellite clocks in a long-term scale are unknown at present. However, it is crucial to the positioning, navigation and timing (PNT) services of users, especially in Asia-Pacific region. In this study, the characteristics and performance variation of four QZSS satellite clocks, which including the phase, frequency, frequency drift, fitting residuals, frequency accuracy, periodic terms, frequency stability and short-term clock prediction, are revealed in detail for the first time based on the precise satellite clock offset products of nearly 1000 days. The important contributions are as follows: (1) It is detected that the times of phase and frequency jump are 2.25 and 1.5 for every QZSS satellite clock in one year. The magnitude of the frequency drift is about 10−18. The periodic oscillation of frequency drift of J01 and J02 satellite clocks is found. The clock offset model precision of QZSS is 0.33 ns. (2) The two main periods of QZSS satellite clock are 24 and 12 hours, which is the influence of the satellite orbit; (3) The frequency stability of 100, 1000 and 10,000 s are 1.98 × 10−13, 6.59 × 10−14 and 5.39 × 10−14 for QZSS satellite clock, respectively. The visible “bump” is found at about 400 s for J02 and J03 satellite clocks. The short-term clock prediction accuracy of is 0.12 ns. This study provides a reference for the state monitoring and performance variation of the QZSS satellite clock.

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In today's world, mining is faced with many evolving requirements and challenges that come to a head in the handling of the plant tailings. Many of which are directly related to the use and conservation of water. Water availability is reducing as the world's demand for it expands. This is particularly true in arid climates like that of Inner Mongolia China. Water supply for the Baotou Steel mine and the livelihood of the nearby communities is supported by a 130 km long pipeline (the longest in China) which draws from the Yellow River. Conservation of this precious resource was one of the main drivers for the use of P&TT technology management of the plant tailings. The water recovery at the iron mine is successfully and consistently achieving above 95%. Recovery of the water at the paste thickeners eliminates or greatly reduces the existence of any free standing water in the tailings deposition unlike within slurry ponds where free water pools on the surface and large volumes are lost to evaporation and allows fluidization during slurry pond dam failures. This paper presents some case studies of China P&TT installations in arid and wet climates.

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