Description and reconstruction of typical structured light beams with vector spherical wave functions.

It is well known that the generalized Lorenz-Mie theory (GLMT) is a rigorous analytical method for dealing with the interaction between light beams and spherical particles, which involves the description and reconstruction of the light beams with vector spherical wave functions (VSWFs). In this paper, a detailed study on the description and reconstruction of the typical structured light beams with VSWFs is reported. We first systematically derive the so-called beam shape coefficients (BSCs) of typical structured light beams, including the fundamental Gaussian beam, Hermite-Gaussian beam, Laguerre-Gaussian beam, Bessel beam, and Airy beam, with the aid of the angular spectrum decomposition method. Then based on the derived BSCs, we reconstruct these structured light beams using VSWFs and compare the results of the reconstructed beams with those of the original beams. Our results will be useful in the study of the interaction of typical structured light beams with spherical particles in the framework of GLMT.

Reflection and refraction of higher-order Hermite-Gaussian beams: a vector wave analysis.

Hermite-Gaussian beams, as a typical kind of higher-order mode laser beams, have attracted intensive attention because of their interesting properties and potential applications. In this paper, a full vector wave analysis of the higher-order Hermite-Gaussian beams upon reflection and refraction is reported. The explicit analytical expressions for the electric and magnetic field components of the reflected and refracted Hermite-Gaussian beams are derived with the aid of angular spectrum representation and vector potential in the Lorenz gauge. Based on the derived analytical expressions, local field distributions of higher-order Hermite-Gaussian beams reflection and refraction at a plane interface between air and BK7 glass are displayed and analyzed.

Experimental and numerical evaluation of the dust suppression efficiency of an innovative vortex pneumatic fog screen dust control device.

To effectively control the dust generated by coal mining operations, a new type of cyclonic pneumatic mist curtain dust control device was developed. Using CFD software, numerical simulations were conducted on the internal airflow velocity field, the exit velocity of the cyclonic pneumatic mist curtain, and the mist droplet particle field of the curtain. Experiments were carried out to measure the spray coverage, droplet size, and the dust control performance of the model device. The results indicate that when the water pump supply pressure is 8 MPa, the fan supply wind speed is 12 m/s, and the nozzle installation angle is 75 degrees, the cyclonic pneumatic mist curtain dust control device model operates under optimal conditions. The effective coverage of the cyclonic mist curtain is 380 × 3300 mm, fully suppressing dust generation on one side of the curtain. An optimal dust removal distance of about 90 cm was determined. After installing the cyclonic pneumatic mist curtain dust control device, the average dust reduction efficiency for respirable dust reached 91.07%, and the overall dust reduction efficiency achieved 93.34%.

Research on the mechanism of coal wall fragmentation and dust production characteristics in the perspective of differentiated discrete elements.

In order to efficiently and accurately control coal dust pollution in coal mining faces, this study addresses the insufficient research on the dust generation mechanism during cutting. Firstly, a similar experimental platform for simulating coal wall cutting with a drum cutter was used to investigate the changes in coal wall fragmentation and dust generation at drum speeds of 35 r/min, 50 r/min, 65 r/min, and 80 r/min. The experimental results revealed that the degree of coal wall fragmentation and dust generation increased with the increase in rotational speed, leading to a wider range of particle size distribution and an increase in the generation of fine dust particles. A 1:1 scale discrete element simulation of coal wall cutting with a drum cutter was conducted based on the experiments. The results indicated that, under the four rotational speeds, the cracks generated during coal wall fracture were predominantly tensile cracks, accounting for over 76% of the total crack count. The total number of cracks increased from 10,600 to 11,200, the number of free single particles increased from 2555 to 2728, and the fragmentation volume increased from 0.021607 to 0.023024 m3. The range and degree of coal wall fragmentation increased with the increase in drum speed.

Study on the dust migration law and a spray dust suppression scheme in transportation roadway.

To solve the problem of excessive dust concentration in the belt transportation roadway of the mine. Numerical simulations were used to study the dust migration in the belt transportation roadway under 1.5 m/s ventilation conditions. The simulation results show the process of dust ejection from the inflow chute to contamination of the whole belt transportation roadway, and the spatial distribution of dust velocity. A comprehensive dust reduction scheme of "central suppression and bilateral splitting" was designed according to the dust distribution, with simultaneous control of the infeed chute and the roadway. In practical application, pneumatic spraying greatly reduces the amount of dust in the guide chute. The misting screen has a significant effect on dust collection and segregation. The solution effectively controls the dust in the space of 20 m on both sides of the transfer point, and the dust removal efficiency reaches more than 90%.

Numerical simulation of the fine kinetics of dust reduction using high-speed aerosols.

A numerical model of single-particle fog-dust collision coupling in a high-speed airflow based on three-phase flow theory. The effect of the fog-to-dust particle size ratio, relative velocity between the fog and dust particles, collision angle and contact angle at the wetting humidity function of dust particles is investigated. Different particle size ratios are determined for achieving the optimal wetting humidity for the interaction of high-velocity aerosols with dust particles of different sizes, for differ, that is, kPM2.5 = 2:1, kPM10 = 3.5:1 and kPM20 = 1.5:1. The optimal humidity increases with the relative velocity U between the fog and dust particles in the high-speed airflow. The larger the collision angle is, the lower the wetting rate is.The smaller the contact angle between the solid and liquid is, the better droplet wetting on dust is. The fine kinetic mechanism of single-particle fog-dust collision-coupling in a high-speed airflow is elucidated in this study.

Study on coal dust diffusion law and new pneumatic spiral spray dedusting technology at transfer point of mine cross roadway.

In order to solve the problem of coal dust pollution at the transfer point, a three-dimensional numerical model of wind flow-coal dust at the loading point of underground rubber run was established by computational fluid dynamics (CFD) discrete particle model and finite element method and k-ε turbulence model, and the coal dust diffusion pollution phenomenon caused by the coal flow transfer under the intersection of wind flow in the cross tunnel was studied. Based on the simulation results of wind flow velocity contour, pressure contour and isochronous flow vector distribution, the influence mechanism of wind flow and coal dust characteristics on the distribution of wind flow and coal dust diffusion in the roadway is analysed, and a dust control and reduction system and treatment scheme with new pneumatic screw spray technology as the core is proposed to suppress coal dust pollution at the reloading point. The results of the study show that the wind flow distribution is mainly influenced by the intersection of tape traction and cross-roadway wind flow, showing a complex multi-layer distribution along the roadway and in the normal direction; the diffusion of coal dust of different particle sizes is influenced by the roadway wind flow, and coal dust with particle sizes in the range of 10µm~20µm is more easily diffused, and the dust with particle sizes in the range of 20µm~45µm is mainly collected and suspended near the vortex wind flow at the cross-roadway. The coal dust in the range of 20 µm~45 µm is more likely to gather in the vortex; the treatment system effectively controls the coal dust inside the dust cover, and the spiral-shaped transported droplet particle group formed by the pneumatic spiral spray combines with it efficiently, which verifies the dust control and reduction effect of the pneumatic spiral spray system at the transfer point, and the dust removal efficiency reaches 89.35%~93.06%, which provides relevant theoretical support for the treatment of dust pollution at the coal transfer point in underground coal mines It provides the theoretical support and means to control dust pollution at underground coal transfer points.