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The distribution of vanadium (V) in aerosols is commonly used to track ship exhaust emissions, yet the atmospheric abundance of V has been greatly reduced due to the implementation of a clean fuel policy. Recent research mainly discussed the chemical compositions of ship-related particles during specific events, yet few studies focus on the long-term changes of V in the atmosphere. In this study, a single-particle aerosol mass spectrometer was used to measure V-containing particles from 2020 to 2021 in Huangpu Port in Guangzhou, China. The long-term trend of the particle counts of V-containing particles declined annually, but the relative abundance of V-containing particles in the total single particles increased in summer due to the influence of ship emissions. Positive matrix factorization revealed that in June and July 2020, 35.7% of the V-containing particles were from ship emissions, followed by dust and industrial emissions. Furthermore, more than 80% of the V-containing particles were found mixing with sulfate and 60% of the V-containing particles were found mixing with nitrate, suggesting that the majority of the V-containing particles were secondary particles processed during the transport of ship emissions to urban areas. Compared with the small changes in the relative abundance of sulfate in the V-containing particles, the relative abundance of nitrate exhibited clear seasonal variations, with a high abundance in winter. This may have been due to the increased production of nitrate from high concentrations of precursors and a suitable chemical environment. For the first time, the long-term trends of V-containing particles in two years are investigated to demonstrate changes in their mixing states and sources after the clean fuel policy, and to suggest the cautious application of V as an indicator of ship emissions. [ABSTRACT FROM AUTHOR]

Based on the continuous strain data recorded in Xinjiang since 1985, we discuss the mechanisms of Tianshan’s uplift and Tarim basin’s clockwise rotation. The results indicate; 1) The principal – compression directions in Tianshan are nearly NS, and their intersection angles with regional structures and mountains are nearly perpendicular, which is in accordance with Tianshan’s uplift and crustal shortening. 2) The principal compressions around Tarim basin tend to facilitate the regional faults’ left-lateral strike-slip movements and the basin’s clockwise rotation. These phenomena of uplift/shortening and rotation are fundamentally the results of India plate’s northward push on Euro-Asia plate, and the associated Pamir arc’s rapid northward movement and regional blocks’ interaction.

This note deals with the robust Hurwitz stability of a class of linear systems with uncertain commensurate time delays, which is formulated as the robust Hurwitz stability of a nonpolytopic family of quasi-polynomials, a NP-hard problem from the viewpoint of computational complexity. On the basis of the "Edge Theorem" and Sylvester resultant elimination, a necessary and sufficient condition is developed for the robust stability of the whole family, and it yields an effective testing procedure. An illustrative example is given to show the effectiveness of the method. Index Terms--Nonpolytope, quasi-polynomial, resultant elimination, robust stability, time delay.