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Fast and slow earthquakes are predominantly generated along faults constituting active plate boundaries. Characterized by repeated devastating earthquakes and frequent slow slip events and tremors, the Alaska megathrust presents a chance to understand the complicated dynamics of a subduction system changing from steep to shallow dips associated with enigmatically abundant fast and slow seismic events. Based on three-dimensional thermal modeling, we find that the downgoing metamorphosed oceanic crust containing bound water releases a large amount of fluid and causes the recurrence of fast and slow earthquakes by elevated pore fluid pressure and hydrofracturing. The seismogenic interface and the slow slip events (SSEs) identified beneath the Upper Cook Inlet coincide well with the slab metamorphic dehydration regions. The observed slow earthquakes with quasi-stable fault slips preferentially occur, accompanied by high dehydration and temperature downdip along the transition zone.

As the main drive components of the automobile transmission, the performance of gear shaft plays an important role on transmission performance. Aiming at the existing problems of the traditional strength check method of gear shaft, the objective of this study is to take a five-speed transmission as an example, to accomplish the strength analysis of gear shaft of the automobile transmission based on the MASTA software. Furthermore, the simulation modeling of the transmission is built completely to simulate the actual load conditions and complete the process of analysis for the gear shaft. Analytical results show that all gear shafts can fully meet the strength requirements, in addition to the input shaft which has any further improvements. Hence, it is indicated that a new design concept is put forward, that is, using specialized software MASTA for transmission modeling and simulation analysis can heavily improve the design level of the gear shaft, provide the theoretic basis to analyze the dynamic characteristics of gear shaft as well. Finally, it can provide references for the development and application of gear shaft of the automobile transmission.