Open-circuit Fault Diagnosis of Traction Inverter Based on Compressed Sensing Theory

This study proposes a new method of fault diagnosis based on the least squares support vector machine with gradient information(G-LS-SVM)to solve the insulated-gate bipolar transistor(IGBT)open-circuit failure problem of the traction inverter in a catenary power supply system.First,a simulation model based on traction inverter topology is built,and various voltage fault signal waveforms are simulated based on the IGBT inverter open-circuit fault classification.Second,compressive sensing theory is used to sparsely represent the voltage fault signal and make it a fault signal.The new method has a high degree of sparseness and builds an overcomplete dictionary model containing the feature vectors of voltage fault signals based on a double sparse dictionary model to match the sparse signal characteristics.Finally,the space vector transform is used to represent the three-phase voltage scalar in the traction inverter as a composite quantity to reduce the redundancy of the fault signals and data-processing capabilities.A G-LS-SVM fault diagnosis model is then built to diagnose and identify the voltage fault signal feature vector in an overcomplete dictionary.The simulation results show that the accuracy of this method for various types of IGBT tube fault diagnosis is over 98.92%.Moreover,the G-LS-SVM model is robust and not affected by Gaussian white noise.

Black Phosphorus Nanosheets Enhance Photophosphorylation by Positive Feedback

We construct a natural-artificial hybrid architecture containing black phosphorus nanosheets(BPNS)to enhance photosynthesis of chloroplast in a positive-feedback manner.In this architecture,oxygen yielded by photosynthesis during water splitting by photosystemⅡpromotes the photoreaction of BPNS to produce proton and inorganic phosphate(Pi).Further,transmembrane proton gradient is increased to drive ATP synthase to synthesize ATP.Meanwhile,additional photogenerated electrons produced by BPNS are transferred to the photosynthesis process.As a consequence,photosynthesis performed by chloroplast is improved.Quantitatively,photophosphorylation efficacy of the hybrid system is increased by 1.89 times in the case of Pi deficiency.This work offers a new path to enhance solar-to-chemical energy conversion,holding promise in boosting natural photosynthesis.

Enhanced Bioenergy Transformation by Metal-Free Electrozyme-Based Mitochondrion Nanoarchitectonics

Herein,we couple a synthetic electrozyme in a supramolecule-assembled nanoarchitecture to achieve enhanced bioenergy transformation by mimicking mitochondrial oxidative phosphorylation.Different from the natural counterpart,the metal-free electrozyme is a semiconducting polymer deposited on an electrode.The wellmatched electrocatalytic property of the electrozyme permits oxidization of reduced nicotinamide adenine dinucleotide(NADH)to release protons under a much lower electric potential.As a consequence,the generated proton gradient drives rotary catalysis of adenosine 5′-triphosphate(ATP)synthase reconstituted in a lipid membrane to produce ATP.Remarkably,electrochemical bioenergy conversion of NADH to ATP is accomplished with much higher efficiency in such a bio-like system compared with the natural mitochondria.This work integrates synthetic and natural catalytic chemistry to facilitate enhanced bioenergy transformation,thereby greatly improving prospects in ATP-fueled bioapplications.