Compact Density Research Articles

Effect of Aloe binder on green properties of dry pressed copper compact: a comparative study

ABSTRACT The present study used Aloe (0–4 wt%) as a binder for dry compaction of copper metal powder. The properties of copper compacts were investigated as a function of compaction pressure (130 MPa, 140 MPa, 150 MPa) and moisture content. The maximum compact density of samples was achieved using 3.5 wt% of Aloe binder at 150 MPa compaction pressure. The maximum achievable green and sintered density of the copper samples was 68.04% and 88.25%, respectively. The corresponding samples exhibited a 4.5-fold and 2.1-fold increase in their green and sintered flexural strength. Copper compacts with the optimal amount of Aloe binder were sufficient for green machining. The density and strength of green compacts were affected by plasticising effect of binder due to functional groups such as hydroxyl (−OH), carbonyl (C=O), and ester groups present in Aloe gel. Samples with the optimal amount of Aloe binder show minimum porosity with negligible residue, as validated by the SEM and thermal analysis. The examined results were compared with the green properties of dry-pressed copper compacts using 0–4 w % polyvinyl acetate binder. Copper has been selected due to its excellent electrical and thermal conductivity and corrosion resistance, making it valuable for electronics, heat exchangers, manufacturing components, etc.

Research on simulation of a bullet skimming the ground by the finite element method

It is greatly complicated to research the process of bullets penetrating into the ground due to the diversity and heterogeneity of ground physical characteristics. The empirical formulas have been developed for scenarios involving deep penetration of bullets into the ground so far; however, equivalent calculations for bullets skimming the ground scenarios remain absent. This paper has established a finite element method (FEM) simulation model for deep penetration and validated it against empirical data. Leveraging this validated model, simulations have been extended to examine the bullets skimming the ground behavior of bullets. The results have delineated the impact angles at which bullets skimming the ground occur for soil with average compaction density. This methodology can be adapted to various soil types to construct a comprehensive set of parameters for bullets skimming the ground angles, thereby optimizing artillery performance.

Effect of Compact Density of MoO2 Powders on Densification Kinetics and Grain Growth During Sintering Processes

Effect of Compact Density of MoO2 Powders on Densification Kinetics and Grain Growth During Sintering Processes

Novel vibratory compaction quality indices developed from particle migration and distribution characteristics for unbound aggregate materials

Unbound aggregate materials (UAM) with large air voids are increasingly used to construct pavement base and subbase layers as part of the initiative to create sponge cities and improve drainage performance. However, the motion of particles and the spatial distribution of kinetic energy during the particle rearrangement process induced by vibratory loading remain unclear. This study presents the results of laboratory vibratory plate compaction tests conducted on UAM specimens under various combinations of vibratory parameters and different levels of Gravel to Sand ratio (G/S). SmartRock (SR) sensors were placed within the specimens to monitor particle motion in real-time while kinematic energy and its spatial distribution were analyzed from the acceleration time-history signals collected by the SR sensors. Based on high-precision industrial X-ray computed tomography (XCT) and 3D reconstruction technology, this study analyzed the motion and migration rules of the UAM particles. A new compaction index was proposed based on particle motion and kinematic energy to evaluate the compaction quality of the specimens.The findings of this study reveal that vibratory compaction can be divided into two distinct stages. During the first stage, coarse particles primarily move vertically while energy dissipation occurs mainly through compression of air voids but does not form a dense skeleton structure. In the second stage, coarse particles translate horizontally while rotating vertically, resulting in a tendency of the particles to lie flat with their long axes oriented horizontally. During this stage, most of the energy is used to fill air voids, leading to the formation of a densely packed skeleton structure. Kinematic energy indices and particle movement in the middle of the specimen can be used to evaluate the compaction stage and quality. Additionally, the lateral particle motion in the specimen transitions from continuous ascent to gradual descent to almost no kinematic energy, indicating a relatively dense state of compaction. Reducing the void ratio and increasing the contact area between particles in these size ranges of 4.75-9.5mm and 2.36-4.75mm can significantly increase the compaction density and improve the stability and deformation resistance of the subgrade bed.The results of this study provide valuable insights into the mechanisms of vibratory compaction and can be used to optimize compaction methods and improve pavement performance.

Effect of Bentonite Properties on Corrosion Behavior of Carbon Steel

Geological disposal is being considered as a disposal method for liquid waste resulting from nuclear power generation. In geological disposal, liquid waste and glass materials are melted together and solidified in an overpack (metal container), and a buffer material is compacted between the overpack and the bedrock. Carbon steel is as a candidate for overpack material and bentonite as a buffer materialin Japan. Overpack materials are required to be safe and reliable over a very long period, and their corrosion behavior and long-term corrosion resistance have been investigated before. However, most of these researches have been conducted in environments where oxygen is fully consumed, and the corrosion behavior and resistance during transient periods have not been fully clarified. In this study, the effects of bentonite properties on the corrosion behavior of carbon steel in compacted bentonite were investigated by electrochemical methods in order to clarify the corrosion behavior of carbon steel during the transient period. An iron wire grinded with sandpapers was used as the sample. The amount of bentonite was weighed to achieve the specified compacted density, and firstly approximately one-half of the amount was filled into a titanium compacted vessel. The iron wire was then set on the bentonite and the remaining bentonite was filled into the vessel using a hydraulic press. The properties of the bentonite were adjusted from 0.9 Mg/m3 to 1.8 Mg/m3 with the compaction density when packed. The titanium vessel was then immersed in a 0.1 mol/L NaCl solution and depressurized at room temperature. The solution was supplied to the cell through a filter on the side of the cell. Polarization and electrochemical impedance measurements were performed in a three-electrode system under open air. The test solution was 0.1 mol/L NaCl solution, a saturated KCl/Ag/AgCl electrode (SSE) was used as the reference electrode, and a platinum wire as the counter electrode. Polarization measurements were conducted by polarizing in the anodic and cathodic directions from the immersion potential at a scanning rate of 0.5 mV/sec. The polarization measurements of an iron wire were also performed in the same solution for comparison. Electrochemical impedance was measured at 24 and 48 hours after immersing the titanium vessel in the test solution. Polarization curve of iron wire in bentonite with a compressibility density of 1.5 Mg/m3 were compared with that in the solution. A clear diffusion-limiting current of oxygen was observed in the polarization curve of iron wire in the solution, whereas it was unclear for iron wire in bentonite. This result is attributed to the influence of water reduction reaction in a cathodic region. On the other hand, in the anodic region, the anodic current of iron in bentonite was about two orders of magnitude lower than that in the solution. This indicates that electrochemical measurements are possible in bentonite as well as in solution, but the influence of compacted bentonite is not small. Electrochemical impedance characteristic of the iron wire in bentonite with a compressive density of 1.6 Mg/m3 showed one time constant after 25 hours of immersion and two time constants after 48 hours, respectively.The diameter of the capacitive semicircles decreased with immersion time. The titanium vessel immersed for 48 hours was opened and the surface of the iron wire was visually observed. As a result, corrosion products were observed. These results suggest that the test solution penetrated into the compacted bentonite after at least 25 hours, and that corrosion progressed to form corrosion products on the electrode surface by 48 hours. Curve fitting was performed on the obtained impedance spectra, assuming the two equivalent circuits. As a result, it was confirmed that the polarization resistance at the electrode surface decreases with time.

Effect of Size Distribution of Solid Electrolyte on Tortuosity of Ionic Conductivity

Solid state batteries (SSBs) are expected to be the next-generation of batteries due to their high energy density and safety. To emphasize the battery performance of SSBs, it is crucial to analyze and design the electrode structure. The powder compression process is one of the most important processes for determining the battery structure. Powder compression is a molding method used to transform powders into solid and high-density compacts. The powder properties and compression conditions influence the packing structure and density of compacts. In this study, we elucidated the effect of the size distribution of a sulfide solid electrolyte on the ionic conductivity of pellets. The particle size distributions of lithium phosphorus sulfur chloride (LPSCl), a solid electrolyte with high plastic deformability, were prepared to evaluate its effect on the relative density and electrochemical properties. The average particle size of LPSCl was reduced through the milling process, and the resulting compacts were evaluated by impedance measurement after mixing raw and milled LPSCl with different mass fractions. The ionic conductivity of the compacts was found to be improved with the broadening of the particle size distribution of the solid electrolyte. Furthermore, the effect of the particle size distribution of the solid electrolyte on the electrode structure was also investigated numerically. The numerical simulations were performed in consideration of the actual particle size distribution to evaluate the void fraction and tortuosity of the electrodes. A discrete element method (DEM) can simulate the powder behavior by calculating the motion of individual particles based on Newton’s second law. Edinburgh elasto-plastic adhesive (EEPA) model, which can consider particle plasticity and cohesiveness, was applied as the contact force model. Particle plasticity parameter λ p was calibrated based on force-displacement curves obtained by nanoindentation tests. The compression process was calculated assuming an infinite flat plate. Although the calculated relative densities agreed with the experimental trend, the values differed from the experimental values owing to the disregard of particle shape. In addition, tortuosity was evaluated by the shortest path algorithm using the powder bed obtained from the numerical analyses. An effective tortuosity was calculated by weighting the contributions of the conductive paths by its number of particles. The effective tortuosity also increased due to the higher number of particles generated during the LPSCl milling process. The combination of DEM analysis and the shortest path algorithm, taking into account grain boundary resistance, demonstrated that is was possible to correlate the electrode structure of the SSB with its electrochemical performance.

Mechanical Milling - Induced Microstructure Changes in Argyrodite Lpscl Solid-State Electrolyte Critically Affect Electrochemical Stability

In the early stages of sulfide solid-state electrolyte (SSE) research, sulfides like Li6PS5Cl (LPSCl) were primarily synthesized in laboratories using fine precursors such as Li2S, LiCl, and P2S5, employing meticulous synthetic procedures involving milling and sintering. This approach resulted in grams of as-synthesized SSE materials with a uniform particle size distribution and well-controlled morphology. Consequently, large-scale synthesis methods for LPSCl SSE have been developed, leading to the availability of commercial LPSCl SSE. Nonetheless, compared to lab-scale synthesis, commercial production of LPSCl SSE often yields a wide range of particle sizes and particle distributions. In-depth understanding is needed regarding how microstructural features such as the average particle size and distribution, and pore size and distribution, affect the compressed SSE's electrochemical performance.In this presentation, we investigate mechanical milling – induced microstructure changes of LPSCl SSE and their influence on electrochemical performance. Planetary mechanical milling in wet media (m-xylene) is employed to alter commercial LPSCl powder. Quantitative stereology demonstrates how extended milling progressively refines grain and pore size/distribution, increases compact density, and geometrically smoothens the SSE-Li interface. Microstructure, in turn, profoundly influences electrochemical behavior. It is shown that an optimized SSE microstructure enables state-of-the-art electrochemical performance without the need for any artificial SEI layers or other secondary modifications. Combined cryogenic focused ion beam (cryo-FIB) and X-ray photoelectron spectroscopy (XPS) demonstrate that milled microstructures promote uniform early-stage electrodeposition on foil collectors and stabilize solid electrolyte interphase (SEI) reactivity. For the first time, short-circuiting Li metal dendrite is directly identified, employing 1.5 mm diameter "mini" symmetrical cell and cryo-FIB. Site-specific analysis highlights that the lithium metal dendrite has the following features: a) a sheet-like morphology with branching sections; b) traverses the compact intergranularly, moving around large grains rather than through them; c) fills the interparticle voids and reacts with the contacting SSE to form reduction decomposition products, i.e. the dendrite is surrounded by an SEI. Figure 1

Multiple strategies from apparatus to synthetic process toward high-performance spherical manganese hexacyanoferrate for sodium-ion batteries

Traditional cubic Prussian blue analogs with limited processability and low density are not suitable for the fabrication of high energy density sodium-ion batteries. Here, we present a novel reactor called the dual-vortexed coprecipitation chamber (DVCC) and a corresponding click reaction as well as electrostatic adsorption mechanism for producing high-density, size-controllable, spherical and low-deficiency manganese-based Prussian blue analogs. The DVCC takes advantage of the two dual vortexes evolve from its side walls to regulate and control the surface functional groups of PBAs primary cubes, thereby facilitating the formation of spherical particles. Through the optimized controlled crystallization precipitation technique, we are able to precisely regulate the nucleation, crystallization and spherical agglomeration process. In comparison to cubic crystals, our unique spherical particles exhibited superior performance with a controllable size distribution of 0 ∼ 40 μm, compacted density of 1.60 g cm−3, an initial capacity of 132.5mAh/g and notably retention rates of 99.5 % for coin cell and 86.7 % for pouch cell respectively after 500 cycles at 1C rate. Benefit by the low H2O content (less than 300 ppm) in the electrodes, the pouch cell avoided gas expansion and also demonstrated excellent fast discharge capability with a retention of 78.7 % at a maximum rate of 40C compared to 1C rate.

Deep learning-based inversion of soil and rock compaction density utilizing Falling Weight Deflectometer (FWD) and Surface Waves

Methods relying on a single dynamic parameter to estimate the material density for the compaction quality testing of earth-rock dams and roadbed projects, present certain limitations in terms of applicability, testing accuracy, and work efficiency. The theory of elastic wave propagation reveals that the compaction density of the medium results from the combined interaction of multiple material properties. This study proposes a method that utilizes the transient surface wave method and a vehicle-mounted Falling Weight Deflectometer (FWD) to jointly enhance the accuracy of soil and rock material compaction detection. The transient surface wave method is employed to extract surface wave velocity and compressional wave velocity. The analysis of the FWD signal involves extracting dynamic parameters closely related to material density, including stiffness coefficients, central frequencies, and stiffness impedances, from time-domain, frequency-domain, and mechanical impedance analyses. A fully connected deep neural network is introduced to intelligently estimate the compaction density. The deep learning model is optimized by selecting the optimal activation function and optimization algorithm, as well as additional tuning. Extensive testing shows that deep learning model produce results closely approximating the true compaction density values. The average relative errors for the wet density and the dry density are 2.9% and 2.85%, respectively, meeting the quality control requirements for density testing. The proposed approach enables rapid detection and control of the compaction quality of soil and rock materials, providing a new method for the in-situ rapid detection of compaction quality.

Strain-induced modulations in nonlinear optical rectification of core/shell quantum dots within an MEH-PPV polymer matrix under electric field: a 3D finite-element modeling study

This research aims to explore how the MEH-PPV polymer matrix and the strength of the applied field (EF) affect an electron confined within strained CdSe/ZnSe spherical core/shell quantum dots (CSQDs). By solving the Schrödinger equation using the element method (FEM) and effective mass approximation we calculated eigenenergy values and their corresponding wavefunctions. Through a compact density matrix approach, we examined how the MEH-PPV polymer matrix, QDs size and electric field intensity impact nonlinear rectification (NOR), in both unstrained systems. By considering factors such as the surrounding polymer matrix and size confinement we analysed computed coefficients related to EF intensity, peak locations and shifts. Our key findings suggest that understanding NOR in relation to parameters and surrounding materials can provide insights, for improving future optoelectronic and photonic devices.

Short-Range promotion and long-range inhibition mechanism of sulfur release in high-sulfur petroleum coke for fast-charging graphite anodes

High-sulfur petroleum coke is considered a promising raw material for artificial graphite anode materials due to its low cost, abundant supply, and large overseas markets. However, the equipment corrosion caused by high-sulfur petroleum coke during graphitization and the unclear sulfur release mechanism limits its industrial application. Herein, the sulfur release characteristics and its effects on the microstructure and electrochemical properties of graphite were systematically investigated through heat treatment of petroleum coke with varying sulfur content at different temperatures. According to the rapid sulfur release characteristics of high-sulfur coke at 1400°C, an innovative pre-carbonization desulfurization process at about 1400 °C is proposed before the traditional graphitization process. Meanwhile, the impact of sulfur release on the microstructure and electrochemical properties of graphite during graphitization was systematically analyzed using XRD, TEM, cross-sectional SEM, and CV, a mechanism was proposed in which sulfur release promotes short-range while inhibiting long-range order in graphitization. Due to the abundance of micro-mesoporous structures, grain boundaries, and small-sized grains produced by sulfur release, high-sulfur petroleum coke-based graphite exhibits excellent fast-charging performance. Compared with the capacity at 0.2C, PC-7.24 %S-CG maintained 52.5 % of its capacity at 1C, which was much higher than that of PC-0.85 %S-CG (34.9 %). Moreover, a sulfur content threshold of 4 % was further established based on changes in compaction density. This work offers new insights into the application of high-sulfur coke for artificial graphite anodes.

Linear and Nonlinear Optical Properties of Symmetric and Asymmetric Double Triangular Quantum Dots Withinside the Presence of Magnetic Field

AbstractLinear and third‐order nonlinear optical absorption coefficients and relative refractive index changes in symmetric and asymmetric double triangular quantum dots are examined theoretically. The dependence of these optical properties on the magnetic field is examined. After calculating energies and wave functions within the effective mass and parabolic band approaches, analytical expressions of linear and nonlinear optical properties are obtained using the compact density matrix approach and iterative method. Numerical calculations are presented for typical GaAs/AlGaAs material. The results show that the magnetic field causes different effects on the and transitions. Moreover, the calculated results also reveal that the resonance frequency and nonlinear contribution are different in symmetric and asymmetric structures. As a result, it is concluded that the magnetic field plays a vital and important role in the electronic and optical properties of the system and can be used to tune the inter‐subband transitions and change the corresponding optical sensitivities.

Applicability of two-phase modeling with compression experiments for snow compaction dynamics

Compaction is a rheological process which, in many fields, has been modeled using a 1-D two-phase continuum framework. However, only recently has it been posed as a promising method for modeling the densification of snow into glacial ice, where the conventional model is empirical or semi-empirical. Here, we explore the applicability of a standard one-dimensional two-phase continuum framework for modeling snow compaction through theoretical and laboratory methods by analyzing and simplifying theory, and then experimentally constraining the model coefficient. We find in our theory analysis that the limit of slow compaction is reached such that air evacuation during the compaction process does not impede the deformation of ice grains. Model-data comparisons are performed using data from a series of uniaxial compression experiments of snow samples under a range of compaction rates (1 × 10−6 to 3 × 10−5 m s−1) and densities (250 to 450 kg m−3) at −10° and –20 °C, which show good measures of fit (r2>0.996). By defining a linear effective pressure function, we then constrain the model parameter by tuning against the data. While our model follows proper simplification of theory, the temperature and microstructural dependence are determined exclusively by the model parameter in a rheological formulation with the strain rate, and much scatter still exists. Within the selected range of compaction rates and densities, our results indicate that a 1-D two-phase model with a continuum framework alone does not likely capture important processes involved in the compaction process.

Parametric modeling and optimization of the intake port in a naturally aspirated opposed rotary piston engine across the full speed range

The opposed rotary piston (ORP) engine offers advantages such as compact size, simple structure, and high power density, making it highly promising for long-endurance unmanned aerial vehicles (UAVs). Parametric modeling of intake ports and the investigation of structural parameters on intake characteristics for ORP engines are crucial for improving the intake performance. In this paper, based on the kinematic model of the ORP engine, parametric modeling of the intake and exhaust ports are performed, a 3D numerical model is established to explore the intake characteristics at different engine speeds. The impact of intake delayed closing angle (IDCA), intake inclination angle (IIA), and dual intake ports on the intake characteristics of the ORP engine are investigated. Finally, the combustion characteristics and performance metrics of the engine using optimized intake ports are compared against the baseline intake phase. The results indicate that the CGE and pumping loss of the ORP engine initially increase and then decrease with rising engine speed. The CGE exceeds 92 % at 1000 r·min−1 and 94 % at 5000 r·min−1 when the IDCA are set at 8° and the IIA at −20°. The pumping losses at 4000 r·min−1 and 5000 r·min−1 are reduced by 33.3 % and 30.9 %, respectively, after intake port optimization. The performance metrics at 1000 r·min−1 and 2000 r·min−1 show a slight decline compared to pre-optimization due to lower turbulence kinetic energy (TKE) and intake backflow. However, at 3000–5000 r·min−1, the optimized intake port structure significantly improves performance metrics of the ORP engine.

Surat’s sustainable future: analyzing compact urban development and population density trends

Rapid urbanization is a challenge for the cities of developing countries like India. The share of an urban area is rapidly increasing in dynamically growing cities. Due to this, the land use is altered, causing sprawl and unplanned development. The consumption of resources is greater, and the impact on the surroundings is negative. The compact city concept is always more efficient and cost effective compared to unplanned organic growth. The compact city optimizes available land resources with its maximum possible capacity in accordance with other available natural resources. The primary study objective is to assess the growth trend of Surat city using satellite images, geographic information system techniques, and census data for the last few years. The analysis considers population density for different city wards from 1991 to 2020. Based on the land use land cover change carried out using the maximum likelihood method from the satellite images, the rate of spreading out, its direction, and causes are also found. In this study, population density is a crucial attribute of the compact city concept. The study shows that wardwise density is increasing in a specific direction and making that portion of the city a dense, compact development. This is observed in ward numbers 48, 42, and 35 in the east, north, and southeast directions from Central Business District, respectively. The average population density in persons per sq. km is continuously increasing from 5006 to 20329 at city level which also shows the compact city development for Surat. The governing authorities must incorporate the compact city concept into the planning policy for sustainable urban development. By this, policymakers can understand housing needs to promote affordable housing, invest in infrastructure development and public services, and identify areas where sustainable transportation options, such as public transit, walking, or cycling, need improvement.

RESULTS OF COMPARISON TESTS FOR CHOOSING THE TYPE OF ROLLER

The article presents the results of the experimental studies on determining the optimal values of the roller of the plowed land and selecting its type on the basis of this. In experimental studies, the provision of complete processing of the field surface is ensured mainly by the selection of the type of roller and the planer for installation on the roller, in order to obtain the required level of moisture for seed germination according to agrotechnical requirements. it is noted that there are gear-plate, rod working parts. In order to verify these obtained results, we made plate, gear-plate, and rod coils, which have a constant diameter, and conducted experimental studies using them. In experimental studies, after using different rollers with a constant diameter, the influence of soil compaction, density and tensile strength was studied. In order to reduce the influence of various variable factors on the obtained results, the experiments were carried out on a specially prepared agro background, that is, it was first plowed and then leveled. In order to test the theoretically based parameters of the roller selected for conducting experimental studies in field conditions, the bases of the roller with a coverage width of 1.5 m and fixed-diameter bases with slats, toothed-slats, and wire plates to be installed on them were developed. released and prepared. Based on the results of experimental studies, the following can be noted: in order to ensure that the compaction quality and density of the soil meet the agrotechnical requirements, and to ensure that the rolling resistance is minimal, it is necessary to have a gear-plate roller.

Impact of delayed compaction on the geoengineering properties of stabilised pond ash

ABSTRACT The impact of delayed compaction on the geoengineering properties of pond ash (PA) treated with geopolymer, Portland cement, and hydrated lime is presented in this paper. The gradation, compacted dry density (CDD), unconfined compressive strength (UCS), California bearing ratio (CBR), hydraulic conductivity, and compressibility index of PA treated with 3%, 9%, and 15% additive contents were evaluated at 0, 3, 6, 12, 24, 48, and 72 h delay periods. The mineralogical and morphological changes in the stabilised material were assessed using X-ray diffraction and scanning electron microscope analysis. The results show an enhancement in the particle size of PA with delay time due to the development of cementitious products and agglomeration of particles. Delay in compaction causes a reduction in dry density and strength properties, whereas hydraulic conductivity and compressibility index increase with delay time. The formation of cementitious products and agglomeration during delay periods leads to improper compaction and deteriorates the mechanical performance. The formations of both sodium-based geopolymer compounds and calcium-based hydration products contribute to the superior geoengineering properties of geopolymer-stabilised PA compared to cement and lime-stabilised PA, which have Ca-based hydration products alone. The developed mathematical models predict the engineering properties of stabilised PA with higher R-square values (>0.90). Based on this study, it is concluded that the geopolymer is more effective as a stabiliser than lime and cement.

Regulatory mechanism of soil and water conservation measures on understorey erosion in a subtropical hilly region

Vegetation restoration affects soil erosion by altering near soil-surface characteristics and hydrodynamic mechanisms. However, the regulatory mechanisms of vegetation restoration in reducing soil erosion under forests are not fully clear. Five soil and water conservation measures (SWCM) with different vegetation structures and characteristics were used in the pure forest of Pinus massoniana which included the grass and shrub, grass, grass and shrub + level furrow, grass, shrub and trees and grass + fish-scale pits, to analyze the impact of vegetation restoration on near soil-surface characteristics and soil erosion. The data were analyzed using Structural Equation Modeling (SEM) to find the key indicators affecting soil erosion under forest. The findings revealed that, as opposed to the control plots (CK), there were significant alterations in the near soil-surface attribute following the application of SWCM. These changes were characterized by an increase in soil porosity, soil water content, soil nutrient content, root biomass, litter, and vegetation cover, and a decrease in soil compaction, disintegration coefficient, and bulk density, with the most significant improvement occurring in 0–10 cm soil layer. The SWCM significantly reduced soil erosion, with runoff and soil loss reduction ranging from 60.46 % to 74.09 % and 67.62 % to 79.99 %, respectively. Structural equation models revealed the influence of SWCM on soil erosion. Specifically, soil water content and litter had a favourable influence on reducing soil erosion, root biomass had a direct positive impact on soil erosion, and vegetation cover directly leads to a reduction in soil erosion. Soil physical properties primarily influenced soil erosion through their effect on vegetation cover. Combining bioengineering and vegetation measures is superior at enhancing soil structure, improving nutrient content, and decreasing soil erosion compared to single vegetation measures. It is recommended to combine bioengineering with vegetation strategies to effectively curb understory forest erosion and enhance soil quality in pine forests.

Impact of the feed particle size distribution and its packing characteristics on compression comminution

Due to its lower energy consumption than a conventional grinding circuit, there is an increased interest in the mining industry in the High-Pressure Grinding Rolls (HPGR) technology. Despite the benefits, the high quantity of material required to size the HPGR makes it difficult for new mines to consider this technology. The piston press test has been used at The University of British Columbia to predict the behavior of the HPGR. It is possible to predict energy requirements, size reduction, and throughput by utilizing a small amount of material to size the HPGR. The bulk material’s particle size distribution (PSD) plays an important role in how the particle bed will pack. This study investigates the differences in compressing three different sample PSDs obtained from the same copper ore crushed to −12.5 mm. The first PSD corresponds to the natural distribution resulting from the crusher. The second is created artificially to match the Fuller curve PSD, which theoretically should have the highest packing density. The third corresponds to a truncated feed produced by removing the fines (−300μm) from the natural feed. Tests were performed using a piston-and-die press test apparatus to compress the samples at different force levels. Entirely different behaviors are obtained while compressing the same material with different PSDs. Particularly, the Fuller curve PSD achieves a 31%–40% higher grinding rate than the natural feed, while the truncated feed achieves a 9%–30% higher grinding rate than the natural feed. Differences in the specific energy consumption, grinding efficiency, and final compacted densities highlight the critical influence of feed particle size distribution on the energy usage and generation of fine particles, underscoring the importance of optimizing these parameters for energy-efficient mineral processing. The overall findings indicate that an HPGR feed particle size distribution that matches the Fuller curve and, therefore, has a maximum packing density, results in the most energy-efficient comminution.

Estimating the compacted dry density of gravelly soil with oversized particles

The compacted dry density of gravelly soils containing particles that are too large for ordinary laboratory compaction tests is usually estimated by measuring the dry density of the base sample obtained by removing over-sized particles then correcting the measured value by the Walker-Holtz Equation (W&H Eq.). It is known that the W&H Eq. overestimates the dry density of gravelly soils and this trend becomes stronger as the mass ratio P of oversized particles increases. It seems that a satisfactory solution is not yet available. A comprehensive series of laboratory compaction tests was performed on a wide variety of gravelly soil samples with different particle sizes, grading uniformities and particle shapes. The followings were found. The ratio, X, of the maximum dry density predicted by the W&H Eq. to the measured value increases linearly from unity as P increases from zero up to approximately 0.75. The slope of the X-P relation, (X − 1.0) / P, increases as the coefficient of uniformity or the fines content of the base sample increases and as the gravel particles become more angular in a synergistic manner. It is proposed to estimate the maximum dry density of compacted gravelly soil containing oversized particles by dividing the value predicted from the W&H Eq. by X obtained from the substitution of P into the relevant X-P relation. Proposed based on the above is an effective and efficient compaction method for gravelly soils containing oversized particles that controls the degree of saturation and the compaction energy.