Algorithm for cavity flow in a new-born goaf and experimental verification

Prevention and control measures of spontaneous combustion of coal and gas accumulation in a goaf require an accurate description of its gas flow state.However,the commonly used fluid dynamics in porous media is not suitable for the new-born goaf with fracture cavity combination,multi-scale,and large blocks.In this study,we propose a cavity flow algorithm to accurately describe the gas flow state in the new-born goaf.The genetic algorithm(GA)is used to randomly generate the binary matrix of a goaf caving shape.The difference between the gas flow state calculated by the lattice Boltzmann method(LBM)and the measured data at the boundary or internal measuring points of the real goaf is taken as the GA fitness value,and the real goaf caving shape and the gas flow state are quickly addressed by GA.The experimental model of new-born goaf is established,and the laser Doppler anemometry(LDA)experiment is carried out.The results show that the Jaccard similarity coefficient between the reconstructed caving shape and the real caving shape is 0.7473,the mean square error between the calculated wind speed and the LDA-measured value is 0.0244,and the R2 coefficient is 0.8986,which verify the feasibility of the algorithm.

Atomic Layer Coated Al_(2)O_(3) on Nitrogen Doped Vertical Graphene Nanosheets for High Performance Sodium Ion Batteries

Heteroatom doped graphene materials are considered as promising anode for high-performance sodium-ion batteries(SIBs).Defective and porous structure especially with large specific surface area is generally considered as a feasible strategy to boost reaction kinetics;however,the unwanted side reaction at the anode hinders the practical application of SIBs.In this work,a precisely controlled Al_(2)O_(3)coated nitrogen doped vertical graphene nanosheets(NVG)anode material has been proposed,which exhibits excellent sodium storage capacity and cycling stability.The ultrathin Al_(2)O_(3)coating on the NVG is considered to help construct an advantageous interface between electrode and electrolyte,both alleviating the electrolyte decomposition and enhancing sodium adsorption ability.As a result,the optimal Al_(2)O_(3)coated NVG materials delivers a high reversible capacity(835.0 mAh g^(-1))and superior cycling stability(retention of 92.3%after 5000 cycles).This work demonstrates a new way to design graphene-based anode materials for highperformance sodium-ion batteries.

Hydrophilic modification of poly(aryl sulfone) membrane materials toward highly-efficient environmental remediation

Poly(aryl sulfone)as a typical membrane material has been widely used due to excellent mechanical,chemical and thermal stability.However,the inherent hydrophobicity of poly(aryl sulfone)based membranes bears with the fouling issue during applications,which makes the membrane tending to adsorb contaminants on the surface so as to result in decreased separation performance and lifetime.In this critical review,we give a comprehensive overview on characterizations of hydrophilic membrane and diverse hydrophilic modification approaches of poly(aryl sulfone)membranes,predominantly including bulky,blending and surface modification technology.The discussions on the different modification methods have been provided in-depth.Besides,focusing on modification methods and performance of modified membranes,the related mechanisms for the performance enhancement are discussed too.At last,the perspectives are provided to guide the future directions to develop novel technology to manipulate the hydrophilicity of poly(aryl sulfone)membranes toward diverse practical and multifunctional applications.

Compact long-working-distance laser-diode-based photoacoustic microscopy with a reflective objective

Photoacoustic microscopy(PAM) has quickly developed into a noninvasive biomedical imaging technique to achieve detection, diagnosis, and monitoring.Compared with Q-switched neodymium-doped yttrium aluminum garnet or optical parametric oscillator lasers, a low-cost and small-size laser diode(LD) used as an alternative light source is conducive to achieving the miniaturization and integration for preclinical transformation.However, the LD’s low peak output power needs the high numerical aperture objective to attain tight focus, which limits the working distance(WD) of the system in only2–3 mm, resulting in not achieving the backward coaxial confocal mode.Here, we present a compact visible LD-based PAM system with a reflective objective to achieve a 22 mm long WD and a 10 μm lateral resolution.Different depth subcutaneous microvascular networks in label-free mouse ears have successfully reappeared in vivo with a signal-to-noise ratio up to14 d B by a confocal alignment.It will be a promising tool to develop into a handy tool for subcutaneous blood vessel imaging.

Effect of geometric parameters at open turbine combined structure on flow field distribution of dry granulation for Si_(3)N_(4) powder

To improve the uniformity of the flow field and the poor axial velocity in the chamber of Si3N4 dry granulation, the influence of geometric parameters at open turbinecombined structure on the flow field distribution is studied. The Euler–Euler gas-solidtwo-phase flow model is established and the physical model of dry granulation chamberunder the combined structure is simplified. Under the same radial structure, the volumedistribution and velocity field of Si3N4 particles in the granulation chamber with a different number and angle of the axial structure at the open turbine are analyzed by theCFD method. The influence of the axial structure at the open turbine on the flow fielddistribution of Si3N4 particles under different geometric parameters is compared. Theresults show that the axial structure of the open turbine in the granulation chamber isthe most uniform when the number of blades is 6 and the inclination angle is 45◦, andthe circulating flow of the upper and lower parts of Si3N4 powder is strong.