No abstract

Aiming at the contact strength reliability of variable hyperbolic circular arc gear, a reliability analysis method for contact strength of variable hyperbolic circular arc gear based on Kriging model and advanced first-order and second-moment algorithm is proposed. Kriging model was used to establish the limit state equation of the contact stress reliability analysis of variable hyperbolic circular arc gear, and the advanced first-order second-moment method was used to analyze the contact stress reliability of variable hyperbolic circular arc gear based on the limit state equation of the contact stress. In order to verify the effectiveness of the proposed algorithm, a Markov Chain Monte Carlo reliability analysis method based on Important Sampling was proposed. Markov Chain and Important Sampling were exploited to improve the accuracy of contact reliability analysis based on Monte Carlo method for variable hyperbolic circular arc gear. The comparison between the analysis results of Markov Chain Monte Carlo with Important Sampling method and first order second moment shows that it is feasible to analyze the reliability of variable hyperbolic circular arc gear by first-order second-moment method.

Carbon-based materials were prepared to catalyze the V3+/V2+ couple of vanadium redox flow battery using chitosan as the preliminary material and FeCl3 as activating agent. Graphite microcrystals were the main structures of the obtained catalyst (CTS-Fe-900) activated by FeCl3, and they contained a large number of curled and overlapped carbon nanosheets. Compared with CTS-D-900 (without FeCl3 as an activating agent), CTS-Fe-900 exhibits a better structure, higher graphitization degree, stronger current response, and smaller charge transfer resistance. The charge/discharge measurements indicates that the performances of the cell are improved by using the CTS-Fe-900-modified negative electrode in terms of increased discharge capacity and energy efficiency. Compared with pristine cell, the capacity retention for the CTS-Fe-900 modified cell maintains 82.2% at 50 mA cm−2 after 50 cycles, increased by 5.2%, and the corresponding energy efficiency reaches 81.3%, enhanced by 5.1%. This work reveals that CTS-Fe-900 catalyst can improve the comprehensive energy storage performance. The excellent electrocatalytic properties are mainly attribute to the effect of the FeCl3 template and the increase in the degree of graphitization.

Water electrolysis is of vital importance to store renewable energy and the development of efficient, inexpensive and stable electrocatalysts for oxygen evolution reaction (OER) is essential, which requires much more understanding of the structural and the element classification. Here, a series of [Formula: see text]Fex[Formula: see text][Formula: see text] perovskites have been assessed as potential noble-metal-free OER electrocatalysts prepared by sol–gel method. Moreover, the functional role of Cu and Fe amount on the B-site of perovskites for OER electrocatalytic performance was evaluated. [Formula: see text][Formula: see text][Formula: see text] materials exhibited the highest intrinsic activities in 0.1[Formula: see text]M KOH for OER with an onset potential of 1.56[Formula: see text]V, a Tafel slope of 76[Formula: see text]mV[Formula: see text][Formula: see text], slightly lower than that of benchmark perovskite-type electrocatalyst [Formula: see text][Formula: see text]C[Formula: see text][Formula: see text]O3 (BSCF). The above results demonstrate that Cu element in the B-site of perovskites had little effect on the OER performance, and [Formula: see text][Formula: see text][Formula: see text] is a potential alternative electrocatalyst for OER application.

No abstract