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After the completion of the Three Gorges Dam, it increases the risk of inducing an earthquake. We use the GRACE Gravity Field Model to analyze the relationship between the operation of the Three Gorges Reservoir and the change of gravity field in western Sichuan. The research results indicate that the reservoir water level and the western Sichuan gravitational field are positively correlated. In the early stage of rising water level, the change of gravity field is not apparent, and the change of gravity field gradually increases with time. Therefore, the change of reservoir water level affects the gravity field in western Sichuan. The dynamic changes of the gravity field can reflect the Earth’s material change and deformation process and are closely related to earthquakes. Consequently, the Three Gorges Dam will indirectly affect the seismicity in western Sichuan by affecting the gravity field. The research provides valuable information for studying regional reservoir earthquake disasters and supports related policy decisions.

In this study, earthquakes with magnitudes above 3.0 on the Richter scale in southwest China from 1900 to 2013 are taken as research objects. The spatio-temporal migration characteristics of seismic activity in the area of concern are studied by using geostatistics method to explore the rules of seismic activity. From the perspective of geostatistics and based on z-value, eight major seismic zones in southwest China were studied zone-wise by using the geostatistics tool ArcGIS and the seismic analysis tool ZMAP to explore the spatial and temporal migration characteristics of earthquakes. It was found that each seismic zone had its own quiet period with relatively inactive seismic activity. Simultaneously, through the study of the time-varying characteristics of the seismic belt, it was found that the time-varying regularity of the seismic frequency of the fault belt with the same or related geological structure background is roughly consistent. In conclusion, the seismic activity in southwest China will still be active in the future.

Combined with the background of the rapid development of e-commerce platform, this paper constructs a twoechelon e-commerce supply chain game model dominated by e-commerce platform and followed by a manufacturer. This paper considers the pricing of products, service level and promotion level under centralized decision and decentralized decision, analyzes the influence of commission rate on optimal decision and supply chain members'profit, and designs "promotion cost allocation coordination" strategy. The results show that: When the commission rate is low, the optimal decision under centralized decision is higher than that under decentralized decision; when the commission rate is high, the result is opposite. Under decentralized decision, the supply chain profit is always lower than that under centralized decision, and the strategy of "promotion cost allocation coordination"can achieve Pareto improvement of both sides'profits. Under decentralized and centralized decision-making, the manufacturer's product price and e-commerce platform service level increase with the promotion efficiency. Finally, a numerical example is given to verify the validity of the conclusion. [ABSTRACT FROM AUTHOR]

We present a theoretical and experimental study of a single-beam spin-exchange relaxation-free magnetometer in 87 Rb vapor cells under different nitrogen gas pressures. The spin relaxation rate is a key component to limit the magnetic sensitivity, and the zero-field resonance method was used to measure the spin relaxation rates of different alkali metal cells. Simultaneously, in a single-beam spin-exchange-relaxation-free (SERF) magnetometer, we demonstrated that the fundamental magnetic field sensitivity was also limited by the pumping light intensity. Based on our theoretical analysis and experimental results, we determined the optimal pumping light intensity and optimal gas pressure. We experimentally demonstrated that the magnetic field sensitivity was 8.89 fT/Hz in the single-beam configuration, with an active measurement volume of 3 × 3 × 3~mm 3 .