Designing electrodes in a highly ordered structure simultaneously with
appropriate orientation, outstanding mechanical robustness, and high electrical
conductivity to achieve excellent electrochemical performance remains a daunting
challenge. Inspired by the phenomenon in nature that leaves significantly increase
exposed tree surface area to absorb carbon dioxide (like ions) from the environments
(like electrolyte) for photosynthesis, we report a design of micro-conduits in a
bioinspired leaves-on-branchlet structure consisting of carbon nanotube arrays
serving as branchlets and graphene petals as leaves for such electrodes. The
hierarchical all-carbon micro-conduit electrodes with hollow channels exhibit high
areal capacitance of 2.35 F cm−2
(~500 F g−1 based on active material mass), high rate
capability and outstanding cyclic stability (capacitance retention of ~95% over
10,000 cycles). Furthermore, Nernst–Planck–Poisson calculations elucidate the
underlying mechanism of charge transfer and storage governed by sharp graphene petal
edges, and thus provides insights into their outstanding electrochemical
performance.
Based on analyzing the problem of the screen with circular, linear, and elliptical trajectory, the spatial Lissajous trajectory has been put forward. The article analyzes the dynamic theory of the spatial Lissajous trajectory screen, and the virtual simulation with discrete-element method is applied to study the solid migration rules. A discrete-element model is developed based on the JKR contact model which takes into considerations viscous forces of contacting particles. Two important factors, migration velocity and filter ratio, are selected to describe the working performance of the vibrating screen. The research results show that the spatial Lissajous vibrating screen has approximate solid migration velocity like the linear vibrating screen, but the filter rate of spatial Lissajous trajectory is the highest. Therefore, the spatial Lissajous trajectory vibrating screen can reduce the phenomenon of screening blockage, and the advantage will be more evident in the case of high drilling fluid viscosity, high mesh number, and serious screen blockage.
In order to study fretting wear damage law of planetary frame axle hole, the distribution of normal stress and relative sliding velocity at axle hole was obtained by finite element software, and a method of extracting fretting wear characteristic parameter data was put forward and verified. According to the modified model of fretting wear depth calculation, the wear depth of each step at axle hole was calculated, and the influence of interference on wear depth was analyzed. The results show that the stress distribution obtained by this method corresponds to the values of each node in the Workbench stress nephogram at that time and has the same distribution rule, which shows that the method is correct. The stress concentration near the inner part of the axle hole of the planetary frame is obvious. Along the circumferential and axial direction of the shaft hole, the relative slip velocity of both ends is larger, and the relative slip velocity of the middle part is smaller. Average wear in both axial and circumferential directions increases with the increase in interference, while wear in the axial direction plays a dominant role in the whole meshing process.
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