Particle Size Ratio Research Articles

Prediction of particle mixing in rotary drums by a DEM data-driven PSO-SVR model

Particle mixing in rotary drums is of significant industrial importance, but very complex. Detailed simulation can be achieved using the discrete element method (DEM), but the computational time cost is enormous. Therefore, we combined machine learning with DEM simulations and established a DEM data-driven particle swarm optimization and support vector regression (PSO-SVR) model to predict mixing time and mixing degree at steady mixing state for binary sphere mixtures in horizontal rotary drums with four independent variables: revolution frequency, particle density ratio, particle size ratio, and drum length. After hyperparameter tuning by PSO on a validation set of 25 simulations, the SVR model was trained on 81 DEM simulations. Testing on another 25 simulations yielded excellent results with R2 = 0.95 for mixing time and R2 = 0.90 for mixing degree. These results indicate that the PSO-SVR model is suitable for rapid predictions of particle mixing in rotary drums and other particle processing equipment.

Research on the construction and verification of evaluation model for borehole collapse in gas extraction

To improve the precision prevention of gas extraction borehole deformation and collapse, it is an important prerequisite to achieve precise monitoring of boreholes. This work is based on distributed optical fiber monitoring and Brillouin Optical Time Domain Analysis Technique (BOTDA). We carried out simulation and validation experiments of borehole plugging with different particle size ratios, constructed a mathematical model for calculating the plugging rate (denoted by ω) of boreholes, and put forward a new methodology for accurate monitoring and evaluation of gas extraction boreholes. The experimental results show that there is a linear relationship between the strain of optical fiber (denoted by ε), the accumulation mass of the simulated coal samples (denoted by m), and the deformation collapse of the borehole. And a mathematical model for calculating the plugging rate of boreholes with more universality has been built by introducing the ratio, volumetric, and strain correction coefficients (denoted by φ, β, and γ). Based on the verification experiment, it was found that the change in the actual and theoretical plugging rates is consistent. With the increase in the ratio of medium coal (2.0–5.0 cm), the plugging rate error decreases first and then increases. The maximum errors are −18.36 % and 19.04 %, but the plugging rate results are still within the middle boundaries of the collapsed boreholes (29.31 % to 75.07 %) and have a neglected effect on the stage classification. Inevitable errors in model construction and actual accumulation errors are two important factors contributing to errors in mathematical models. Taking ω as 0 %, 27.71+40.05·rord.-2%, 74.50+14.13·rord.-2%, and ε limit value 143.77·φ·γ με as the critical value to distinguish the primary, middle, and late periods of borehole collapse. In this work, a new technology of borehole monitoring and evaluation with plugging rate and strain critical value as evaluation indexes is proposed, which can provide a reference for accurate monitoring of drainage boreholes and gas prevention.

Effect of Coal Particle Breakage on Gas Desorption Rate during Coal and Gas Outburst

The gas contained in coal plays a crucial role in triggering coal and gas outbursts. During an outburst, a large quantity of gas originally absorbed by coal is released from pulverized coal. The role this part of the gas plays in the process of coal and gas outbursts has not been clearly elucidated yet. Therefore, investigating the changes in gas desorption rate from coal particles of different sizes could provide some meaningful insights into the outburst process and improve our understanding of the outburst mechanism. First, combining the diffusivity of coal of different particle sizes and the distribution function of broken coal, we present a gas desorption model for fragmented gas-bearing coal that can quantify gas desorption from coal particles within a certain range of size. Second, the gas desorption rate ratio is defined as the ratio of the gas desorption rate from coal being crushed to that from coal before breaking. The desorption rate ratio is mainly determined by the desorption index (γ) and the granularity distribution index (α). Within the limit range of coal particle sizes, the ratio of effective diffusion coefficient for coal particles with different sizes is directly proportional to the reciprocal of the ratio of particle sizes. Under uniform particle size conditions before and after fragmentation, the gas desorption rate ratio is the square root of the reciprocal of the effective diffusion coefficient. The gas desorption model quantitatively elucidates the accelerated desorption of adsorbed gas in coal during the continuous fragmentation process of coal during an outburst.

Co-assembly of cellulose nanocrystals and gold nanorods: insights from molecular dynamics modelling.

A coarse-grained molecular dynamics model is developed to explore the co-assembly of cellulose nanocrystals (CNCs) and gold nanorods (AuNRs) under sedimentation conditions with varying volumetric concentration and particle-size ratios. Simulations and statistical analysis reveal a noticable preferential attachment of AuNRs on the surface of CNC clusters as the solid fraction of AuNRs was increased when the volumetric fraction of the AuNRs was low. Density-driven self-assembly under sedimentation forces is primarily driven by the AuNRs. This shift in the dominant mechanism from CNCs to AuNRs reveals the limits of multi-particle interactions and formation of ordered structures in binary particle systems. The fundamental insights provided in this work into the self-assembly process in complex particle systems are valuable for the design and control of the physical conditions to achieve desired ordered structures.

Investigation on the effect of particle size ratio on liquefaction resistance of sand-fines mixtures using DEM

Investigation on the effect of particle size ratio on liquefaction resistance of sand-fines mixtures using DEM

Experimental Study on the Migration and Clogging of Fine Particles in Coarse-Grained Soil with Seepage

The migration and clogging of fine particles in the pores of coarse-grained soil with seepage is of great significance to reduce the leakage of soil at the dam base and lower the permeability of soil. Therefore, the homemade infiltration test device was used to test the infiltration and clogging of soil samples with different particle size ratios D15/d85 (D15 represents the particle size corresponding to the cumulative percentage content of soil particles smaller than a certain particle size in the coarse particles which is 15%, and d85 represents the particle size corresponding to the cumulative percentage content of soil particles smaller than a certain particle size in the fine particles group which is 85%). The factors affecting the deposition of fine particles in coarse-grained soil and the characteristics of fine particle migration and penetration were analyzed. The clogging of coarse-grained soil, hydraulic gradient and pore changes characteristics before and after clogging were studied. The results show that: 1) The main factor affecting the retention of fine particles in coarse-grained soil is the particle size ratio, and the retention rules conforms to the Peak-Gauss function relationship. The penetration law of fine particles satisfies the Logistic function relationship, which can directly predict the internal clogging of coarse-grained soil. 2) The particle size ratio is the main factor affecting the blockage in each mode, followed by the influence of the water head, When the particle size ratio is less than 13.10, the clogging ratio decreases with the increase of particle size ratio, and the hydraulic gradient increases with the increase of particle size ratio. When is greater than 13.10, the clogging ratio increases with the increase of particle size ratio, and the hydraulic gradient decreases with the increase of particle size ratio. 3) The degree of clogging in coarsegrained soil is closely related to the change in porosityand and can be judged according to the change of porosity in coarse-grained soil. The research results deepen the understanding of fine particle migration on the rules of coarse-grained soil clogging and can provide a theoretical basis for related engineering applications.

Numerical Simulation Analysis and Research of Large Scale Garden Construction Waste Mounding Hill Landscaping

Along with the rapid development of international metropolis, China's urbanization is developing faster and faster. In the process of China's urbanization development, mountain mounding with construction waste is one of the most direct, effective and economical means to deal with construction waste, not only that, but also, one of the important methods for ecological restoration project of landscape gardening, this method has several advantages such as green construction, green low carbon, energy saving and carbon reduction, etc. It also improves the utilization rate of resources, has high economic and environmental benefits, and also has high High research value and social significance.Since there are differences in the mechanical properties of the original soil and the mounded hill materials in the process of construction waste mounding, as well as, differences in the soil quality in different regions, it is necessary to study the stability of the hill. In this paper, the following research results are obtained through actual case studies of typical landscape projects: first, geomechanical tests are conducted on the raw soil and construction waste mound hill materials to obtain the particle size ratios, maximum dry density and optimum moisture content, and compression modulus of specific mixes, and the triaxial shear test proves that each stress-strain curve basically conforms to the Duncan-Zhang hyperbolic relationship assumption before the peak occurs.Finally, numerical simulations were carried out for different working conditions in combination with the three-dimensional calculation model, and the calculation and analysis of the Bishop consolidation theory were used to obtain the settlement displacement, horizontal displacement development and pore pressure dissipation process of the calculation model. The landslide stability of the slope is calculated and the minimum safety coefficient under normal conditions and the minimum safety coefficient under seismic conditions are both calculated by Swedish method and Bishop method respectively, both of which meet the requirements and determine the technical feasibility and reasonableness of the scheme. In the conclusion part of this paper, the problems and handling measures in the construction process are summarized to provide valuable experience for similar projects.

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.

Effect of Particle Size Ratio on Microstructure and Active Material Utilization in Argyrodyte All-Solid-State Composite Cathodes

Among next-generation batteries, all-solid-state batteries (ASSB) promise increased energy densities, fast charging properties, and higher safety compared to traditional liquid-based systems. To achieve the demanded high energy densities high mass loadings of the composite cathodes are necessary. These consist of active material (AM), solid electrolyte (SE), and conductive additive as well as binder. Volume changes of intercalation AM and insufficient ionic percolation at low SE contents lead to an increased interfacial resistance and capacity loss. In order to promote cathode AM utilization the particle size ratio of the AM and the SE within the composite cathode needs to be optimized.Theoretical calculations have shown that for high AM utilization at high AM loadings particle size ratio is a crucial parameter [1, 2]. Experimentally, the influence of particle size ratio has so far only been studied at laboratory scale. However, scalable process routes have not considered this important aspect. In this work, we present a solvent-based process route for the preparation of sulfide-based solid-state composite cathodes with NCM622 as AM, starting from the adjustment of the particle size of a commercially available Li6PS5Cl SE by planetary ball mill. Further process steps include the dispersion of SE with AM and conductive additive and doctor blade coating of cathode films. We analyzed the composite cathodes with regard to their internal resistance as well as their microstructure and conducted electrochemical tests in lab-scale test cells. Optimization of the particle size ratio results in an increase of AM utilization by a factor of 5 as well as an enhanced AM-SE-particle contact area and lower porosity.

Ni agglomeration and performance degradation of solid oxide fuel cell: A model-based quantitative study and microstructure optimization

Nickel agglomeration poses a noteworthy impediment to the commercialization of SOFCs. A comprehensive coupled degradation model is established, encompassing a Ni-particle coarsening model, microstructural parameters, effective mesoscopic parameters, and various transport processes (mass/momentum/heat/charge/multi-species transports), and chemical/electrochemical reactions. The initial anode microstructural parameters are optimized by the comprehensive model and response surface method (RSM). Single-factor analysis shows that within the initial Ni-particle diameter (dNi(t=0)) range of 0.6–0.9 μm, a particle size ratio (R) of 1.0–1.5 between YSZ-particle and Ni-particle, and a solid-phase volume fraction of Ni-particle (ψNi) ranging from 0.35 to 0.55, SOFC demonstrates high power density and a reduced degradation rate. Using the single-factor results, RSM is employed for -anode microstructure optimization, specifying: dNi(t=0) = 0.7 μm, R = 1.0, and ψNi = 0.49. Correspondingly, the average power density at 0.6 V (PD‾0.6V) reaches 2828.5 W/m2, with a degradation rate (Vde) off 0.441 %/1000 h. In comparison to original microstructure parameters (dNi(t=0) = 0.6 μm, R = 1.0, ψNi = 0.4), the optimal SOFC exhibits a remarkable enhancement in electrical performance and durability, with an 11.9 % increase in PD‾0.6V and a 69 % reduction in Vde. The integration of the comprehensive model and RSM presents a promising strategy for predicting performance, refining operation condition, and optimizing electrode microstructure for long-term operating SOFC.

A novel semi‐resolved CFD‐DEM method with two‐grid mapping: Methodology and verification

AbstractThe semi‐resolved Computational Fluid Dynamics coupled with the Discrete Element Method (CFD‐DEM) method has emerged as approach to modeling particle‐fluid interactions in granular materials with high particle size ratios. However, challenges arise from conflicting requirements regarding the CFD grid size, which must adequately resolve fluid flow in the pore space while maintaining a physically meaningful porosity field. This study addresses these challenges by introducing a two‐grid mapping approach. Initially, the porosity field associated with fine particles is estimated using a coarse CFD grid, which is then mapped to a dynamically refined grid. To ensure conservation of total solid volume, a volume compensation procedure is implemented. The proposed method has been rigorously verified using benchmark cases, showing its high computational efficiency and accurate handling of complex porosity calculations near the surface of coarse particles. Moreover, the previously unreported impact of the empirical drag correlation on fluid‐particle force calculations for both coarse and fine particles has been revealed.

Method of spectral response to stochastic processes for measuring the nonreciprocal effective interactions.

The theoretical background of the nonperturbative method of spectral response to stochastic processes (SRSP) for measuring the nonreciprocal interparticle effective interactions in strongly coupled underdamped systems is described. Analytical expressions for vibrational spectral density of confined Brownian particles with a nonreciprocal effective interaction are presented. The changes in the vibrational spectral density with varying different parameters of the system (nonreciprocity, viscosity, ratios of particle sizes, and intensities of random processes acting on each particle) are discussed using the example of a pair of nonidentical particles in a harmonic trap. The SRSP method is compared to three other nonperturbative methods. The SRSP method demonstrates an undeniable advantage when processing particle trajectories with errors in particle tracking.

Research on an epoxy resin magnetoelastic abrasive: Application in tool edge preparation

Magnetoelastic abrasive grains have low elastic modulus and magnetism, which can create magnetic brushes in magnetic fields. When magnetoelastic abrasive particles come into contact with a workpiece, they can cause deformation, which increases the effective contact surface area and improves machining quality and efficiency. A method for preparing epoxy resin magnetoelastic abrasives was proposed first. The magnetic particle micromorphology was detected through scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Secondly, based on the theory of particle-filled composite materials and mechanics, the representative volume element (RVE) model was developed using the finite element software ABAQUS. The size ratio of iron and silicon carbide filler particles, particle shape, and arrangement of stress and strain were found to further improve the magnetoelastic abrasive preparation process. To investigate the effect of time, abrasive size, tool speed, disc speed, and disc spacing on the flank face value, rake face value, and shape factor, double disc magnetic preparation was subjected to magnetoelastic abrasive. Compared to traditional drag finishing methods, the magnetoelastic abrasive demonstrated high efficiency and quality. Exploring the application of magnetoelastic abrasives, new technology and methods of edge preparation, and promoting progress in magnetic efficient processing and magnetic optical finishing technology is of great theoretical and practical value.

Kinetic modeling of phenolic compounds extraction from nutshells: influence of particle size, temperature and solvent ratio

This paper studies the effects of particle size, temperature and ethanol–water solvent ratio on the extraction of total phenolic compounds (TPC) from peanut, coconut, and macadamia nutshells. Using an I-optimal design, the maximum TPC extraction obtained from the shells ranged from 63.5 ± 1.6 to 76.2 ± 3.1 mg gallic acid equivalent (GAE) per 100 g dry weight (dw) of nutshell. Next, a response surface model (RSM) was developed to describe the relationship between the process parameters and the extracted TPC concentration, in order to predict the optimal extraction conditions. For all of the examined biomasses, the optimal conditions for extraction were predicted at a particle size of 1 mm, temperature of 75 °C and ethanol/water mixture of 54, 53 and 65% ethanol, for peanut, coconut and macadamia nutshells respectively. Particle size seems to be the most important parameter, while temperature appears to be of lesser importance. Besides, the extraction kinetics were assessed by fitting kinetic models on the experimental data. The combined second-order diffusional model provided the best goodness of fit. This model revealed that, at the boundary layer, the effect of washing mechanism of extraction is more important than extraction due to diffusion kinetics. This study provides an understanding of the mass transfer mechanism involved in the TPC extraction process from nutshells, which yields valuable insights that could facilitate the industrial biorefinery of nutshells.Graphical

Parametric modelling of clogging behavior of porous pavements with time

With the aim of facilitating easier development of guidelines for the stakeholders using porous pavements, a simple parametric mathematical model is developed for the prediction of clogging behavior, i.e., time-dependent decaying hydraulic conductivity of porous pavement dependent on two different input parameters in addition to time. Based on earlier experimental results, trends of diminishing hydraulic conductivities with time under different void ratios and particle sizes were established. It is found that for a particular particle size, the effect of void ratio on time-dependent hydraulic conductivity can be expressed with a combined linear and exponential functions. Again, for a particular void ratio, the effect of particle size on time-dependent hydraulic conductivity can be expressed with an exponential function. The particle size dependent equation was further extended to include the effect of void ratio through multiplying a linear function having void content as independent variable. Developed equation predicted results were compared with the original experimental measurements. It is found that all the three models are capable to well-predict experimental measurements with RMSE values equal or higher than 0.98. The void content dependent equation is capable to predict results having standard errors as, Root Mean Squared Error (RMSE) = 0.04, Mean Absolute Error (MAE) = 0.03 and Relative Absolute Error (RAE) = 0.09, whereas the same error statistics of the particle size dependent equation are 0.04, 0.02 and 0.08 respectively. Error statistics of the combined (particle size and void ratio) equation are, RMSE = 0.1, MAE = 0.07 and RAE = 0.22. Such modelling technique would be useful for the prediction of potential clogging in the porous pavement for any combination of input parameters.

Effects of shock stress and microstructure on shock response of Al-Hf reactive materials

Reactive materials are functional structural materials that balance structural strength and reactivity, and their shock response is greatly influenced by the characteristics of reactive components. This article aims at understanding the shock compression and reaction of Al-Hf reactive materials with two values of the Al-Hf particle size ratio α (1 µm:10 µm and 10 µm:10 µm), which were prepared through hot pressing with a compactness (the ratio of density to theoretical maximum density) greater than 96.46%. The free surface velocity of the materials was measured in the impact velocity range of 279–865 m/s. The Hugoniot elastic limit (HEL), spall strength, and Hugoniot relationships under shock stresses of 1.83–14.46 GPa were analyzed on the basis of the microstructure and phase change. Continuous Al phase was formed in the sample with α = 0.1, while more Hf–Hf contact and crushed Hf appeared in the sample with α = 1. The velocity profiles presented clear signs of the linear growth to the HEL, the slow increase to the peak, and the subsequent pullback, indicating the transition from elastic to plastic and spall behavior. The HEL fluctuated significantly with increasing shock stress, while the spall strength first increased and then decreased. The sample with a continuous Al phase exhibited a lower HEL (0.52–0.97 GPa) and higher spall strength (0.31–0.46 GPa). The microstructure had a significant effect on the shock induced chemical reaction of the materials. Shock velocity was linearly related to particle velocity for the α = 0.1 sample, while a notable quadratic growth was observed for the α = 1 sample owing to self-reactions under the lower shock stress (5.32 GPa). The intermetallic Hf4Al3 observed in the recovered product by X-ray diffraction further verified the phenomenon.

Al/Hf ratio-dependent mechanisms of microstructure and mechanical property of nearly fully dense Al–Hf reactive material

This study proposed three types of Al–Hf reactive materials with particle size ratios (α), which were almost completely dense (porosity of <5.40%) owing to their preparation using hot-pressing technology. Microstructure characteristics and phase composition were analyzed, and the influence of particle size ratios on dynamic mechanical behavior and damage mechanism were investigated. The prepared sample with α = 0.1 exhibited continuous wrapping of the Hf phase by the Al phase. Hf–Hf contact (continuous Hf phase) within the sample gradually increased with increasing α, and a small amount of fine Hf appeared for the sample with α = 1. The reactive materials exhibited clear strain-rate sensitivity, with flow stress σ0.05 and failure strain εf increasing approximately linearly with increasing strain rate ε˙. It is found that the plastic deformation of the material increased with increasing strain rate. As α increased from 0.1 to 1, the flow stress gradually increased. Impact failure of the material was dominated by ductile fracture with a large Al phase plastic deformation band for lower α, while brittle fracture with crushed Hf particles occurred at higher α. Finally, a constitutive model based on BP neural network was proposed to describe the stress-strain relationships of the materials, with an average relative error of 2.22%.

Influence of impact medium particle size on mechanical deposition layer formation process based on discrete element method

Based on the discrete element method, this study has simulated the movement of materials in the plated barrel using EDEM software to investigate the effect of the impact medium with different particle sizes on the mechanical deposition plating. The simulation analyzed the interaction between five impact mediums with different particle sizes (2, 3, 4, 5, and 6 mm) and the base body while determining the particle size ratio of the impact medium. The rationality of the particle size ratio was verified by the simulation analysis of the interreaction of two groups of mixed particle size impact medium and the base body. The samples of mechanically deposited zinc coating were prepared. The average thickness, relative density, and average deviation of the coating were measured. The results show that When the particle size is 2 and 3 mm, the effective collision frequency of the materials is higher. When it is 3, 4, and 5 mm, the kinetic energy of collision between materials fluctuates evenly. When it is 4 and 5 mm, the collision contact force of the materials changes regularly. Consequently, the obtained particle size ratio (second group) is 2 mm 23%; 3 mm 23%; 4 mm 23%; 5 mm 27%; and 6 mm 4%. Compared with mixed impact media with 20% of each of the five particle sizes (first group), in the second group of assorted particle size simulation test, the collision frequency between materials is high. The contact force changes more regularly between materials. The average thickness, relative density, and average deviation of the mechanically deposited galvanized layer are consistent with the simulation results of the two groups of mixed particle sizes. The average thickness and relative density of the galvanized layer in the second group are higher, the average deviation is smaller, and the compactness and uniformity are the best.

Технология использования чернового концентрата в качестве минералов-носителей

Технология использования чернового концентрата в качестве минералов-носителей

Preparation of bimodal-diamond/SiC composite with high thermal conductivity

The excellent thermal properties of diamond/SiC composites are mainly attributed to the addition of diamond particles. In order to further increase the diamond content, a novel preparation method was used to regulate the distribution of bimodal diamond particles. Moreover, in order to achieve better performance, the effects of particle size ratios on the properties were studied. The results show that with the increase of small diamond particle size, the bimodal diamond packing will change from unmixing mechanism to mixing mechanism, and the critical ratio (small/large) of entrance for 400 µm diamond particles is between 0.37 and 0.5. When the particle size ratio is 0.25, the thermal conductivity reaches the maximum, reaching 812.27 W/mK (break through 800 W/mK for the first time). In addition, the influence of particle size ratio on coefficient of thermal expansion is also discussed.