Dynamic switching of transmission modes hydroacoustic communication MAC protocols.

In recent years, the hydroacoustic communication MAC (Medium Access Control) protocol has attracted wide attention. Hydroacoustic communication networks suffer from issues such as long propagation delays and rapid dynamic changes in network load, which prevent the maximization of network performance through the use of a single transmission mode. In this paper, we propose a Dynamic Switching Transmission MAC protocol called the DSTM-MAC protocol.

Influence of Recirculation Flow on the Dispersion Pattern of Blasting Dust in Deep Open-Pit Mines.

The recirculation within a deep open-pit mine is a significant factor contributing to the deterioration of the atmospheric environment. However, the underlying mechanisms of how recirculation influences the dispersion pattern of dust clouds within the deep open-pit mine have not been clearly elucidated. In this research, the dispersion patterns of blast dust clouds were investigated in a deep open-pit mine located in northern China.

Influence of vehicle and pavement characteristics on dust resuspension from soil pavement of open-pit mine.

It is essential to explore the distribution characteristics of dust concentration distribution near the surface of soil pavement in open-pit mines to develop effective dust control measures. Therefore, in this study, the dust resuspension process of soil pavement was analyzed by building the dust resuspension experimental system of open-pit mine, and the change rules of dust concentration under different factors were investigated. The results showed that under the action of wheel rolling, the dust moved around the wheel along the vertical direction, and the diffusion trajectory in the horizontal direction was approximately parabolic.

Simulation Experiment Research of Mine Roadway Simulating Test Device with Adjustable Wind Velocity and Temperature and Humidity.

The design and development process of wind velocity sensors for mining has been a challenging task due to the complexity of a large number of field tests. To resolve this problem, this study aimed to provide a comprehensive test device for the design and development of high-precision wind velocities sensor for mining. Through a combination of experiments and computational fluid dynamics (CFD), a device that can simulate the mine roadway environment was developed.

Formulation and Performance Characterization of Polymeric Dust Suppressants for Stockpiles.

With an aim at the dust problem of open dust sources in construction sites, open stockyards, mines, docks, and other areas, a polymer chemical dust inhibitor was developed in this study that is suitable for stockyards through theoretical analysis and laboratory tests. Through a single-factor experiment and an orthogonal experiment, the viscosity value of dust suppressant and the hardness value of the crust taken as evaluation indexes, the optimal formula of dust suppressant for a pile was finally obtained after an analysis of range and variance: the optimum formulation of the dust suppressant for stockpiles was finally obtained by: 0.6%A + 0.

Modeling of Permeability Coefficient Calculations Based on the Mesostructure Parameters of Tailings.

The permeability coefficient of tailings in tailings ponds, which can affect the release and migration of heavy metals in tailings, also affects the stability of dams by affecting the variation of the height of the saturation line. In this paper, tailings at different levels in a tailings pond were taken as research objects to measure the particle size and permeability coefficient of the tailings. At the same time, CT scanning technology and three-dimensional reconstruction were used to establish the three-dimensional model of the tailings, and the permeability coefficient of the tailings was analyzed from a mesostructural point of view.

Progress in Piezoelectric Nanogenerators Based on PVDF Composite Films.

In recent years, great progress has been made in the field of energy harvesting to satisfy increasing needs for portable, sustainable, and renewable energy. Among piezoelectric materials, poly(vinylidene fluoride) (PVDF) and its copolymers are the most promising materials for piezoelectric nanogenerators (PENGs) due to their unique electroactivity, high flexibility, good machinability, and long-term stability. So far, PVDF-based PENGs have made remarkable progress.

Research on the Influencing Factors and Prediction Model of Impact Airflow in the Process of Unloading of an Ore Pass Based on a Coupled Computational Fluid Dynamics and Discrete Element Method.

In this paper, a coupled computational fluid dynamics and discrete element method (CFD-DEM) is used to numerically simulate the energy transfer of the ore falling process and the change law of impact airflow velocity under different influencing factors. The results are as follows: the total drag force is an important factor that determines the impact airflow velocity. The greater the total drag force, the greater the impact airflow velocity.

Mesoscopic Seepage Simulation and Analysis of Unclassified Tailings Pores Based on 3D Reconstruction Technology.

Taking the unclassified tailings as the research object, the three-dimensional (3D) pore model was established using computed tomography (CT) scanning technology, image processing, and the 3D reconstruction method. The model was imported into Flac3D software for mesoscopic seepage simulation and analysis. Combined with the laboratory seepage experiment, the influence of tailings' mesoscopic parameters on permeability was explored.

Distribution Law of the Temperature Inversion Layer in a Deep Open-Pit Mine.

Using the methods of field experiment, numerical simulation, and theoretical analysis, a deep concave open-pit mine (DCOM) geometric model is established. Ansys Fluent software is used to simulate the change in the temperature field at night in the DCOM over time and analyze the probability of the spatial distribution of the temperature inversion layer. The results show that the location inside the stope close to the southwest edge is more likely to present temperature inversion, and the location close to the northeast edge is the least likely to have temperature inversion, and the height range where temperature inversion is likely to occur is 100-0 m.

Polarization-Sensitive Light Sensors Based on a Bulk Perovskite MAPbBr Single Crystal.

Organic-inorganic halide perovskites have attracted much attention thanks to their excellent optoelectronic performances. Here, a bulk CHNHPbBr (MAPbBr) single crystal (SC) was fabricated, whose temperature and light polarization dependence was investigated by measuring photoluminescence. The presence of obvious band tail states was unveiled when the applied temperature was reduced from room temperature to 78 K.

Key Factor Analysis and Model Establishment of Blasting Dust Diffusion in a Deep, Sunken Open-Pit Mine.

Blasting dust is the main source of atmospheric pollution in deep, sunken open-pit mines (DSOMs), which affects seriously the normal work and production in the mines. Here, the influencing factors and a diffusion model with regard to blasting dust diffusion were investigated and proposed in a representative mine. Dimensional analysis and multiple nonlinear regression analysis were applied to establish a mathematical model of the blasting dust diffusion.

Temporal-Spatial Distribution of Vehicle Transportation Pavement Dust Migration in an Open-Pit Mine.

To investigate the dust source of the most polluted equipment in the open-pit mine, this paper studied the temporal-spatial distribution laws of dust migration in the vehicle transportation pavements in the open-pit mine via theoretical analysis and a field test. The results show that the dust concentration of the same horizontal distance from the pavement centerline remains roughly stable, which proves that the dust above the pavements is a continuous line source. In the horizontal direction, the maximum dust and baseline concentration reached heights of 1-3 and 20 m away from the wheels, respectively, while they are obtained at heights of 0.

Preparation of a Composite Calcium Silicate Board with Carbide Slag and Coal-Based Solid Waste Activated by Different Alkali Activators.

Overall performance of composite calcium silicate boards (CCSBs) was investigated to further promote their application. The alkali activators were used to fully hydrate the calcium and silicon raw materials, which further improved the comprehensive performance of the CCSBs made of four pure industrial solid wastes. Within the range of dosage in this study, single doping of different proportions of the alkali activator improved the flexural strength of the CCSB.