Experimental rig

<p>Experimental rig</p

A rolling element bearing fault diagnostic system based on multifractal dimension algorithm and adaptive gray relation algorithm

<p>A rolling element bearing fault diagnostic system based on multifractal dimension algorithm and adaptive gray relation algorithm</p

Traditional single fractal dimension (i.e., box-counting dimension) of a random chosen sample from bearing normal condition and different fault conditions with fault size 7mils

<p>Traditional single fractal dimension (i.e., box-counting dimension) of a random chosen sample from bearing normal condition and different fault conditions with fault size 7mils</p

Generalized multifractal dimensions of a random chosen sample from bearing inner race fault condition with different levels of severity

<p>Generalized multifractal dimensions of a random chosen sample from bearing inner race fault condition with different levels of severity</p

Description of experimental data set

<p>Description of experimental data set</p

Generalized multifractal dimensions of a random chosen sample from bearing normal condition and different fault conditions with fault size 7mils

<p>Generalized multifractal dimensions of a random chosen sample from bearing normal condition and different fault conditions with fault size 7mils</p

Bearing inner race fault conditions with different levels of severity.

<p>Bearing inner race fault conditions with different levels of severity.</p

Traditional single fractal dimension (i.e., box-counting dimension) of a random chosen sample from bearing inner race fault condition with different levels of severity

<p>Traditional single fractal dimension (i.e., box-counting dimension) of a random chosen sample from bearing inner race fault condition with different levels of severity</p

Bearing normal condition and various fault conditions with fault size 7mils

<p>Bearing normal condition and various fault conditions with fault size 7mils</p

Dual Regulation of Charge Separation and the Oxygen Reduction Pathway by Encapsulating Phosphotungstic Acid into the Cationic Covalent Organic Framework for Efficient Photocatalytic Hydrogen Peroxide Production

Previous research on covalent organic framework (COF)-based photocatalytic H2O2 synthesis from oxygen reduction focuses more on charge carrier separation but less on the electron utilization efficiency of O2. Herein, we put forward a facile approach to simultaneously promote charge separation and tailor the oxygen reduction pathway by introducing phosphotungstic acid (PTA) into the cationic COF skeleton. Experiments verified that PTA, as an electron transport medium, establishes a fast electron transfer channel from the COF semiconductor conductor band to the substrate O2; meanwhile, the reaction path is optimized by its catalytic cycle for preferable dioxygen capture and reduction in oxygen reduction reaction (ORR) kinetics. The existence of PTA promotes the rate and tendency of converting O2 into •O2– intermediates, which is conducive to boosting the photocatalytic activity and selectivity toward the sequential two-step single-electron ORR. As expected, compared to the pristine TTB-EB, the optimal PTA0.5@TTB-EB achieves a 2.2-fold improvement of visible-light-driven photocatalytic performance with a H2O2 production rate of 897.94 μmol·L–1·h–1 in pure water without using any sacrificial agents. In addition, owing to the robust electrostatic interaction and the confinement effect of porous TTB-EB channels, the PTA@TTB-EB composite possessed favorable stability