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The special linear shape of spiral tunnel changes the air flow structure during tunnel construction and changes the diffuse and distribution of blasting dust. Mastering the blasting dust distribution and diffuse mechanisms can provide theoretical basis for ventilation layout and dust removal measures during spiral tunnel construction. To study the influence of spiral shape on dust diffusion and concentration distribution after tunnel blasting, a similar scale model of 1:20 and full-scale numerical model of spiral tunnel during construction were established. The similarity criterion and the similarity ratio of each physical quantity are derived from the dust motion equation. The dust distribution and diffuse characteristics in the spiral tunnel under different dust release quantity and release velocity were studied by model experiment. The dust distribution and diffuse characteristics in spiral tunnel with different curvature radius were studied by numerical simulation. The dust distribution model is refined based on the research results. The dust distribution model divides the tunnel into heavily polluted area and slightly polluted area, and the influence characteristics of the curvature radius on the dust export area are found. The layout of ventilation systems can be optimized according to the volume of heavily polluted areas. The heavily polluted area should be as small as possible; the dust in the heavily polluted area should be discharged to the slightly polluted area in an orderly manner to avoid the accumulation of dust. Dust removal measures can also be arranged according to the dust export location to improve dust removal efficiency. [ABSTRACT FROM AUTHOR]

To obtain the adaptability range of the single-filter cartridge dust collector, a numerical analysis of the key component (filter cartridge) that affects the filter performance of the dust collector is carried out. The study found that the filtration air velocity gradually decreases from the top A to the bottom C of the filter cartridge surface. During the filtration process, along the surface of the filter cartridge from C to A, the pressure first drops and then rises. At C, the negative pressure is the largest, with an average of about 525 Pa. The ineffective filtration area of section A of the upper part of the filter cartridge accounts for 2/5 of the filtration area, and the concentration of the first layer of dust is y = (0.01 ± a) + 0.02 × (0.08 ± b)x exponentially decreasing. The critical particle size range that the filter cartridge can filter dust is M≥1.87 μm, and the best dust removal range of the dust collector is N≥4.625 μm. An agreement between experiment and simulating results proves the validity of simulation model and reliability of the experimental data. Enterprises can choose a reasonable dust removal method based on the research results to optimize the adaptability of the working environment and the dust collector. It also provides a theoretical basis for researchers to solve the problems in the filtration and cleaning process. [ABSTRACT FROM AUTHOR]

Field equations in a modified theory of gravitation proposed by Harko et al. (Phys. Rev. D 84: 024020, ) are obtained with the aid of a spatially homogeneous and anisotropic LRS Bianchi type-II metric. Cosmological models corresponding to stiff fluid, disordered radiation, dust and false vacuum are obtained. Some physical and kinematical properties of each of the models are also studied. [ABSTRACT FROM AUTHOR]

Axially symmetric cosmological models are obtained in a scalar tensor theory proposed by Sen (Z. Phys. 149:311, ) based on Lyra manifold with time dependent β in the presence of string source, perfect fluid distribution, dust distribution and thick domain walls. Some physical and geometrical properties of these models are discussed. [ABSTRACT FROM AUTHOR]