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The dust generated during tunnel construction poses serious health risks to workers, as it not only causes respiratory obstruction but also leads to pneumoconiosis and respiratory failure after prolonged exposure. However, most existing studies focus on specific construction stages or particular particle sizes and often assume an ideal airflow, neglecting the complex flow fields, vortex effects, and dust composition variations at different stages in tunnel and mine construction. This study systematically analyzes the spatiotemporal distribution characteristics of dust at various stages of tunnel construction and proposes targeted prevention and control strategies. On the basis of measured data from three construction stages—the working face, initial support, and secondary lining stages—and SPSS 27 statistical analysis, a dynamic analysis was conducted on the concentration and distribution patterns of total suspended particulates (TSPs) and particulate matter of different sizes (PM10, PM4, PM2.5, and PM1). The results show that coarse particles dominate during the working face stage, whereas fine particles gradually accumulate during the initial support and secondary lining stages. Finally, this work establishes a dust concentration–excavation time/tunnel depth equation and proposes targeted dust control measures. These findings offer important practical value for enhancing construction safety and air quality. [ABSTRACT FROM AUTHOR]

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]

Dust comprises particles usually present in the atmosphere. The deposition of dust on the surface of the solar panel seriously affects the light transmittance, resulting in lower pow-er generation efficiency and shortening the service life of the solar panel. Therefore, it is important to understand the dust distribution on the surface of solar panels and discuss the influence of dust on the power generation efficiency of solar panels for the efficient prevention of dust deposition on the panel. In this study, to analyze the dust distribution on the surface of the solar panel, the discrete element method was used to establish the contact mechanics model between dust particles and the solar panel. The number of dust particles on the surface of solar panels was calculated at different solar panel inclination angles, wind speeds, and wind directions. The wind speed of 1 and 3 m/s did not affect the dust deposition significantly but the speed over 5 m/s reduced the dust particles from the surface of the solar panel. The inclination angle of 23° influenced dust deposition on the surface of the solar panel. Wind direction did not show a significant effect on dust deposition. The longer the deposition time, the more particles remained on the surface due to the increased force between the particles and the surface of the solar panel. The results from calculation and measurement from transmittance were similar with a different rate of 3.41%. Thus, the result of the proposed calculation in this study provides a basis for de-signing the solar power generation plant and decision-making on the maintenance of the solar panel. [ABSTRACT FROM AUTHOR]

In this paper, we present solution of Einstein field equations which admit dust distribution and negative energy massless scalar field as a source with cosmological term (Λ) in the frame work of Bianchi type II space-time. The models satisfy conservation equation and creation field increases with time satisfying the result as investigated by Hoyle and Narlikar [A new theory of gravitation, Proc. Roy. Soc. A 282 (1964) 191]. The deceleration parameter (q) for the model (22) shows a transition from decelerating to accelerating regime with creation. A comparison with other cosmological models shows a transition from decelerating to accelerating regime with and without creation is mentioned. The present model is free from singularity, particle horizon and provides a natural explanation for inflationary scenario and isotropization. These features make the creation field cosmological models theoretically superior to the Big Bang models. Creation field and Einstein field equation are derived using principle of least action and the Lagrangian formulation of variable cosmological term is derived as mentioned by Moffat [Lagrangian formulation of a solution to the cosmological constant problem (1996), arXiv:astro-ph/9608202v1]. The current creation rate with other physical consequences is also discussed. For illustrative purposes, evolutionary behaviors of some cosmological parameters are shown graphically. In the figures, the cosmic time t is given in gravitational units assuming the velocity of light c = 1. This t = c T and T = t c . Therefore, by multiplying cosmic time t by (light years)−1, we obtain the coordinate time in years. [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]

Residents in arid regions of northwest China, where dust storms are more common, are continually exposed to air pollution particularly fine particles of PM2.5 and PM10, causing health hazards to residents. Urban greening species have a strong dust retention capacity which is also available in arid conditions and should be chosen to reduce the impact of air pollution on people and the urban environment. In this paper, three common tree species in four different functional areas: Transportation area (TA), Residential area (RA), Industrial area (IA), and Clean area (CA) of Aksu City were selected to measure their foliar dust to select the matching trees for appropriate sites. The dust particle size distribution for PM2.5 and PM10 was analyzed to explore the particle size difference between foliar dust and natural landing dust. The largest particle size was recorded in IA (168.56 µm), while the smallest was found in CA (43.25 µm). Furthermore, Salix babylonica (S. babylonica) absorbed the highest PM2.5 and PM10, 0.15% and 1.39% respectively; while Ulmus densa (U. densa) absorbed the least PM2.5 and PM10, 0.08% and 0.37%. Platanus acerifolia (P. acerifolia) foliar dust particle density was the highest, and has stable dust retention capacity, while, S. babylonica foliar dust particulate density is the lowest under the same conditions (height/location, pollution exposition, weather). Our findings concluded that the average values of dust diameters in the four areas differed significantly. It is concluded that P. acerifolia is the best performer in removing dust in different functional urban areas and S. babylonica was more suitable for CA because of having the capacity to remove fine particle matter. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the dust load in St. Petersburg based on the measurements of dust levels in different areas of the city using a CEM DT-9880 portable dust particle counter. A uniform one-character bottom up zoning was performed to determine the parameters, and the dependencies of dust distribution on various factors were identified using the "Ecolog" software package. The zoning was based on more than 2.5 thousand measurements of dust levels. An effective and rational solution to the problem of increased aerotechnogenic load in different areas of the city through the use of modern te chnologies of hydro-dedusting of city roads with a dust-binding solution based on surfactants was proposed for increasing the adhesion ability of the solution to the standard roadbed. [ABSTRACT FROM AUTHOR]

At present, the fact that the airflow of the air duct outlet in fully mechanized heading face cannot be adjusted and cannot meet the practical requirement of ventilation dust suppression may lead to the steep rise of safety hazard and pollution risk. While by adjusting the angle, caliber, and the distance from the air duct outlet to the heading face, the dust distribution can be optimized and the dust suppression efficiency can be effectively improved. The acquisition method of regulation rules under different sizes of the roadways, the angles, calibers, and distance from the air duct outlet to the heading face is investigated by using the rough set theory, finite element flow field numerical simulation and underground test verification. Then, the decision information system, the discernibility matrix algorithm for attribute reduction and the heuristic value reduction algorithm for rule acquisition are established, and the regulation rules of the outlet parameters are obtained and expressed. The dust concentration analysis after adjusting shows that the area of the dust concentration is significantly reduced and the dust reduction rate at drivers can be increased by 48% compared with the original field, which provides theoretical basis for the optimal dust distribution and dust sup pression. [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]