Particulate Materials Research Articles

Определение оптимальных параметров воздушного потока создаваемого пневмопогрузчиком уборочно-транспортного агрегата

The design of working bodies of a harvesting and transport unit (HTU) for hay collection is considered. The HTU consists of a hay pickup, a pneumatic loader and an assembly chamber. The process of filling the chamber was investigated, and the characteristics of the pneumatic loader ensuring high-quality performance of this process were determined. The main requirement for the pneumatic loader is the ability to create and maintain technological parameters – air flow rate at a corresponding air flow velocity. An analytical expression was obtained for the trajectory of a hay mass particle at the outlet of the loader depending on the air flow velocity and the angle to the horizontal. The relationship between this velocity and the parameters of the material particle flight trajectory and the dimensions of the assembly chamber was established. The optimal parameters of the velocity of 22-25 m/s correspond to the following overall dimensions: length – 5.0 m, height – up to 4.0 m.

Shear characteristics of nonuniform distribution of granular materials in ring shear test and impact on landslides

Knowledge of the shear behavior of landslide soil is very important for understanding landslide dynamics. This study investigated the shear behavior of base soil particle materials using ring shear tests with glass beads. Samples with varying particle sizes and distributions were examined to explore how particle size affects shear behavior at different shear velocities. Analysis of the samples included assessment of shear stress, displacement-shear stress fluctuations, and changes in the shear stress standard deviation. Results showed that with increasing shear displacement, shear stress fluctuations stabilize. Rather large difference particle size differences lead to more uniform particle mixing and a lower shear stress standard deviation. Conversely, when smaller particles predominate, particle mixing is less uniform, resulting in a higher shear stress standard deviation. Additionally, this study discussed the shear dilation and compaction mechanisms of samples under large displacement shear.

Selective on-site detection and quantification of polystyrene microplastics in water using fluorescence-tagged peptides and electrochemical impedance spectroscopy

In this study, we developed a method for the on-site selective detection and quantification of microplastics in various water matrices using fluorescence-tagged peptides combined with electrochemical impedance spectroscopy (EIS). Among the types of plastics found in seawater, polystyrene (PS) microplastics were selected. Fluorometry, scanning electron microscopy (SEM), and Raman spectroscopy were used to verify the specific interaction of these peptides with PS spherical particles of different sizes (ranging from 0.1 to 250 µm). Principal component analysis (PCA) was employed to determine the effects of temperature (25–65 °C), incubation time (5 and 10 min), and particle size on plastic-peptide bonding efficiency, based on fluorescence intensity. For each water type (pure, tap, NaCl (0.5 M), and seawater), EIS plots (Nyquist and Bode) were generated. Significant factors affecting the EIS response, including particle size, shape, and material, were analyzed by measuring electrical parameters for different microplastic concentrations (50 ppb to 20 ppm). The EIS parameters changed with increasing plastic concentration, determining a limit of detection (LOD) of 50 ppb (ng/mL) for pure and tap water and 400 ppb for saline water, as the lowest concentration producing a significant change in EIS parameters compared to the baseline. The sensor proved highly effective for detecting microplastics in low ionic strength environments such as pure and tap water. However, in high ionic strength environments like saline and seawater, the detection capability diminished, likely due to the masking effect of ions on the EIS response.

Topological Data Analysis for Particulate Gels.

Soft gels, formed via the self-assembly of particulate materials, exhibit intricate multiscale structures that provide them with flexibility and resilience when subjected to external stresses. This work combines particle simulations and topological data analysis (TDA) to characterize the complex multiscale structure of soft gels. Our TDA analysis focuses on the use of the Euler characteristic, which is an interpretable and computationally scalable topological descriptor that is combined with filtration operations to obtain information on the geometric (local) and topological (global) structure of soft gels. We reduce the topological information obtained with TDA using principal component analysis (PCA) and show that this provides an informative low-dimensional representation of the gel structure. We use the proposed computational framework to investigate the influence of gel preparation (e.g., quench rate, volume fraction) on soft gel structure and to explore dynamic deformations that emerge under oscillatory shear in various response regimes (linear, nonlinear, and flow). Our analysis provides evidence of the existence of hierarchical structures in soft gels, which are not easily identifiable otherwise. Moreover, our analysis reveals direct correlations between topological changes of the gel structure under deformation and mechanical phenomena distinctive of gel materials, such as stiffening and yielding. In summary, we show that TDA facilitates the mathematical representation, quantification, and analysis of soft gel structures, extending traditional network analysis methods to capture both local and global organization.

Study on the performance of electrostatic agglomeration enhances magnetic filter material for filtering fugitive particles in the iron and steel industry

In this work, a new method is proposed to utilize a magnetic filter material to suppress the escape of fugitive particles in the iron and steel industry. The magnetic filter material was prepared using the impregnation method, exhibiting superior demagnetization resistance. The magnetic field effect generated by magnetic filter material was combined with the diffusion, interception, and inertial effects of traditional filtration mechanisms to enhance the removal of fugitive particles. The magnetic polyimide filter material improves the filtration efficiency of particles with a diameter less than 2.0 μm by approximately 20% compared with polyimide filter materials. In addition, the filtration performance was further enhanced through electrostatic agglomeration. When the positive electrode voltage is +18 kV, and the negative electrode voltage is −16 kV, after the bipolar pre-charging treatment of fugitive particles with a diameter of 0.1–1.0 μm, the magnetic polyimide filter material can achieve a filtration efficiency of more than 90%, the magnetic polyimide (P84), magnetic polyphenylene sulfide (PPS), and magnetic fiberglass filter materials all achieve a filtration efficiency of over 94% with a diameter of 0.5–1.0 μm. This study lays the foundation for the proposal new dust removal methods for the iron and steel industry.

Effects of particle gradation and material proportions on the mechanical properties of crushed stone aggregates under cyclic loading

To enhance the service performance of the subgrade and optimize subgrade design, we conduct a comprehensive analysis of the impact of gradation on the mechanical properties of crushed stone aggregates, considering both macroscopic and microscopic perspectives. And this paper establishes intricate relationships between deformation parameters, fragmentation, and gradation within crushed stone aggregates, shedding light on the nuanced variations in microscopic mechanical properties across various gradations. The research outcomes underscore that the cumulative deformation and resilience modulus of crushed stone aggregate gradually stabilized after 1000 loadings. The curvature coefficients of gradations 3 and 4 were significantly smaller than those of gradations 1 and 2, which were 1.09 and 0.92, respectively. The gradations with smaller curvature coefficients had better uniformity and density. The addition of limestone increased the resilience modulus of aggregate, but also increased the cumulative deformation. The best effect was achieved when the ratio of quartz to limestone in the aggregate was 3:1. For the failure form of crushed stone aggregate, the failure form of gradation 1 with less fine particle content was mainly characterized by crushing, while the failure forms of gradations 2, 3, and 4 were mainly grinding. When limestone was added to the aggregate, the failure form was also mainly grinding. In addition, the crushing degree of crushed stone aggregate was closely related to the change in the distribution coefficient r. The smaller the change, the lower the crushing degree. The crushing degree was the smallest when gradation 4 and the ratio of quartz to limestone was 3:1, and the change values were 0.038 and 0.073, respectively. The simulation results further show that when the aggregate gradation is 4 or the limestone content is less than 50 %, the microcrack content decreases, while the microcracks and force chains are more uniformly distributed.

Review on the Polymeric and Chelate Gel Precursor for Li-Ion Battery Cathode Material Synthesis.

The rapid design of advanced materials depends on synthesis parameters and design. A wide range of materials can be synthesized using precursor reactions based on chelated gel and organic polymeric gel pathways. The desire to develop high-performance lithium-ion rechargeable batteries has motivated decades of research on the synthesis of battery active material particles with precise control of composition, phase-purity, and morphology. Among the most common methods reported in the literature to prepare precursors for lithium-ion battery active materials, sol-gel is characterized by simplicity, homogeneous mixing, and tuning of the particle shape. The chelate gel and organic polymeric gel precursor-based sol-gel method is efficient to promote desirable reaction conditions. Both precursor routes are commonly used to synthesize lithium-ion battery cathode active materials from raw materials such as inorganic salts in aqueous solutions or organic solvents. The purpose of this review is to discuss synthesis procedure and summarize the progress that has been made in producing crystalline particles of tunable and complex morphologies by sol-gel synthesis that can be used as active materials for lithium-ion batteries.

Why heterogeneous cloud particles matter. Iron-bearing species and cloud particle morphology affect exoplanet transmission spectra

The possibility of observing spectral features in exoplanet atmospheres with space missions like the James Webb Space Telescope (JWST) and Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) necessitates the accurate modelling of cloud particle opacities. In exoplanet atmospheres, cloud particles can be made from multiple materials and be considerably chemically heterogeneous. Therefore, assumptions on the morphology of cloud particles are required to calculate their opacities. The aim of this work is to analyse how different approaches to calculate the opacities of heterogeneous cloud particles affect the optical properties of cloud particles and how this may influence the interpretation of data observed by JWST and future missions. We calculated cloud particle optical properties using seven different mixing treatments: four effective medium theories (EMTs; Bruggeman, Landau-Lifshitz-Looyenga (LLL), Maxwell-Garnett, and Linear), core-shell, and two homogeneous cloud particle approximations. We conducted a parameter study using two-component materials to study the mixing behaviour of 21 commonly considered cloud particle materials for exoplanets. To analyse the impact on observations, we studied the transmission spectra of HATS-6b, WASP-39b, WASP-76b, and WASP-107b. Materials with large refractive indices, like iron-bearing species or carbon, can change the optical properties of cloud particles when they comprise less than 1<!PCT!> of the total particle volume. The mixing treatment of heterogeneous cloud particles also has an observable effect on transmission spectroscopy. Assuming core-shell or homogeneous cloud particles results in less muting of molecular features and retains the cloud spectral features of the individual cloud particle materials. The predicted transit depths for core-shell and homogeneous cloud particle materials are similar for all planets used in this work. If EMTs are used, cloud spectral features are broader and the cloud spectral features of the individual cloud particle materials are not retained. Using LLL leads to fewer molecular features in transmission spectra than when using Bruggeman.

Sedimentation of heterogeneous particles in a porous material

Filtration of suspensions and colloids in porous materials occurs during the construction and operation of hydraulic structures, tunnels and underground storage facilities. Filtration models are used to calculate the penetration of grout into loose soil, when treating drinking water and industrial wastewater. During the filtration process, suspended particles pass through large pores and get stuck at the entrance of small-diameter pores. The trapped particles form a stationary deposit. A model of filtration of a polydisperse suspension in a porous material is considered. The purpose of the work is to study sediment profiles – the dependence of the concentration of deposited particles on the distance to the porous material inlet at a fixed time. An exact solution to the model was constructed using the method of characteristics. It has been shown that when filtering a polydisperse suspension, the distribution of sediment differs for different types of particles. The sediment profile of the largest particles always decreases monotonically, but the sediment profile of the smallest particles is not monotonic. It decreases at short times, then a maximum point appears on the graph, moving along the porous medium as time increases. After the maximum point reaches the porous material exit, the sediment profile becomes monotonically increasing. The sediment profiles of intermediate size particles and the total sediment profile are either monotonic or non-monotonic depending on the model parameters. The behavior of maximum points of non-monotonic profiles has been studied.

Modeling of the effect of fibers on ECC slurry fluidity based on an amended water film thickness theory

Knowing the influence mechanisms of fibers on ECC slurry fluidity and implementing the prediction of ECC slurry fluidity attach vital significance to the design and application of ECC. Based on traditional water film thickness (WFT) theories, this paper introduces the difference in surface WFT of reactive fibers and binding material particles with excess water distribution coefficient and further gives a modified formula for water film calculation and a WFT based ECC fluidity model. Through 40 tests and fitting, the excess water distribution coefficient with respect to distinct fibers and relevant parameters of the ECC fluidity model are obtained. The results indicate that the new model is applicable to different types of fibers, and the fluidity of ECC slurry can be described using an equation, with the R2 of the new equation reaching 0.97. Finally, based on the proposed model, the impact of PP and PVA fibers on the fluidity of ECC slurry can be summarized in two aspects: the wedge effect of the fibers reduces the packing density of the ECC powder, leading to a decrease in the excess water ratio; the water distribution in the ECC slurry is altered by the fibers, resulting in a decrease in the water film thickness on the surface of the cementitious material particles, ultimately causing a decline in the fluidity of the ECC slurry.

Investigation on the mechanical and thermal properties of metal-PLA composites fabricated by FDM

PurposeThe aim of this study is to investigate the printing parameters of fused deposition modeling (FDM), a material extrusion-based method, and to examine the mechanical and thermal properties of their polylactic acid (PLA) components reinforced with copper, bronze, and carbon fiber micro particles.Design/methodology/approachTensile test samples were created by extruding composite filament materials using FDM-based 3D printer. Taguchi method was used to design experiments where layer thickness, infill density, and nozzle temperature were the printing variables. Analysis of variance (ANOVA) was applied to determine the effect of these variables on tensile strength.FindingsThe results of this study showed that the reinforcement of metal particles in PLA material reduces strength and increases elongation. The highest tensile strength was obtained when the layer thickness, infill density, and nozzle temperature were set to 100 µm, 60%, and 230 °C, respectively. As a result of thermal analysis, cooper-PLA showed the highest thermal resistance among metal-based PLA samples.Originality/valueIt is very important to examine the mechanical and thermal quality of parts fabricated in FDM with metal-PLA composites. In the literature, the mechanical properties of metal-reinforced composite PLA parts have been examined using different factors and levels. However, the fabrication of parts using the FDM method with four different metal-added PLA materials has not been examined before. Another unique aspect of the study is that both mechanical and thermal properties of composite materials will be examined.

Development of PIND system based on resonant sensors and research on material identification methods for redundant particles

Abstract Aiming at the problems of the existing particle impact noise detection (PIND) system, such as low detection accuracy, high rate of misjudgment and missed judgment, and the inability to judge the material of internal redundant particles in real time, a method for automatic detection and material identification of redundant particles based on neural network recognition is proposed, and an automatic detection system for redundant particles of sealed electronic devices is developed. The system is equipped with multi-channel piezoelectric resonant sensors, which convert the redundant particle impact noise signal into a voltage signal, and then transmit the signal to the host using a high-speed data acquisition system. The upper computer uses a short-term energy threshold detection method to extract signal pulses; Then, a variety of time and frequency domain features are extracted and combined with wavelet domain features; Finally, by training the multi output neural network prediction model, it can automatically judge whether there are redundant particles in the tested parts, and automatically give the material information of the redundant particles. Experiments show that the accuracy of the system for material recognition of redundant particles with a mass greater than 0.1 mg can reach 88.6%.

Effect of brackish water inundation on temperate coastal acid sulfate soils under different vegetation types

AbstractCoastal wetland soils are frequently underlain by sulfidic materials. Sea level fluctuations can lead to oxidation of sulfidic materials in acid sulfate soils (ASS) and increased acidity which mobilises trace metals when water levels are low, and inundation of coastal wetland soils and reformation of sulfidic materials when water levels are high. We measured the effect of surface water level fluctuations in soils from coastal wetland sites under four different vegetation types: Apium gravedens (AG), Leptospermum lanigerum (LL), Phragmites australis (PA) and Paspalum distichum (PD) on an estuarine floodplain in southern Australia. We assessed effects of fluctuating water levels on reduced inorganic sulfur (RIS) in terms of acid volatile sulfide (AVS), chromium reducible sulfur (CRS) and trace metals (Fe, Al, Mn, Zn, Ni). Intact soil cores were incubated under dry, flooded and wet–dry cycle treatments of 14 days for a total of 56 days. The flooded treatment increased RIS concentrations in most depths in the AG, PA and PD sites. Lower CRS concentrations occurred in all sites in the dry treatment due to oxidation of sulfidic materials when the surface layer was exposed to lower water levels. CRS was positively correlated with SOC in all treatments. The highest net acidity occurred in the dry treatment and lowest occurred in the flooded treatment in most sites. Inundation with seawater caused SO42− reduction and decreased soluble Fe in the PA and PD sites. General decreases in Al, Zn and Ni concentrations in flooded treatments may have been due to adsorption onto colloids or co‐precipitation with slight increases in pH. SO42− concentrations decreased in the LL, PA and PD sites in the flooded treatment due to reformation of pyrite. In general, accumulation of RIS in soils under different vegetation types following brackish water inundation varied according to vegetation type, which may be linked to differences in organic material input and particle size distribution. Geochemical characteristics reflected whether oxidation or reduction processes dominated at each site in the wet–dry cycle treatments, with oxidation dominating in the LL and PA sites and reduction dominating in the AG and PD sites. This is likely due to more readily decomposable organic matter forming sulfidic materials during short periods of inundation.

Vision-based mixed color detection of plastic particles.

In the production process of high-end PP-R pipes, mixing different colored raw material particles can result in uneven color in the final product, affecting its appearance quality. in addition, color mixing can reduce the physical properties of the pipes, impacting their durability and safety. To address this issue, we propose a visual, non-destructive inspection solution based on image processing technology. The solution aims to enhance detection efficiency and accuracy by reducing background interference and enabling adaptive adjustments in various environments. Initially, the K-Means image segmentation algorithm is employed to eliminate complex background factors from the original image, significantly improving image segmentation accuracy. Subsequently, the Gaussian mixture model algorithm is utilized to automatically extract the color threshold of the foreground image after background removal, facilitating adaptive algorithm adjustments. Finally, the mean value algorithm is introduced to swiftly and accurately identify plastic particles of different colors using the automatically obtained color thresholds. Experimental results demonstrate that this method can quickly and accurately identify different color particles and effectively support the rejection of impurity particles. Through this approach, the algorithm achieves an average detection accuracy of 99.3%.

Simulating solid-state battery cathode manufacturing via wet-processing with resolved active material geometries

Prior to the development of a solid-state battery cell, researchers have limited knowledge about the microstructure of the electrodes and how they are affected by manufacturing. Therefore, numerical simulations can be considered as a powerful tool to link the fabrication process to the final microstructure of the electrode. In this paper, a numerical simulation of a wet-processed solid-state battery cathode with a formulation of 75 % LiNi9Mn0.5Co0.5O2 (NMC), 17.5 %LPSCl, 5 % Timcal C65 and 2.5 % Polyisobutene (PIB) is presented. From nano-computed tomography images, realistic shapes of active material particles are extracted and used in the simulation, which is well-calibrated to experimental data. In particular, we study the effects of calendering on the microstructure of the simulated cathode and deduce structure-property relations.

The effects of raw materials particle sizes on the solid-state reaction progress, morphology and magnetic properties of M-type strontium hexaferrites

In this work, the effects of SrCO3 and Fe2O3 particle size on the reaction process, morphology and magnetic properties of M-type strontium hexaferrites (SrM) have been further studied. Pure strontium hexaferrite magnetic sample based on SrCO3 and Fe2O3 molar ratio of 1:6 has been successfully prepared at 1150 °C. The results indicated that Fe2O3 particle size was the main factor of affecting the formation of SrM, a pure SrM phase magnetic sample was able to obtain at lower calcination temperatures by using fine Fe2O3 powder as raw material, and at the same calcination temperature, a sample using fine Fe2O3 powder as raw material was able to obtain pure SrM phase magnetic sample with shorter holding time. When the mean particle size of Fe2O3 was below 60 nm, a pure SrM phase magnetic sample was able to form at 1150 °C at a molar ratio of 1:6 of SrCO3 and Fe2O3. In this case, the magnetic parameters of the sample with the optimum magnetic parameters were saturation magnetization MS = 77.8 emu/g and coercive force HC = 4122 Oe. And the solid-state reaction process of the corresponding samples was slightly faster when the mean particle size ratio of Fe2O3 and SrCO3 was between 0.35 and 0.36. Assuming that a SrCO3 particle is surrounded by Fe2O3 particles, it can be inferred that the corresponding molar ratio of Fe and Sr of the nearest raw material particles is between 3.6 and 3.8.

A Planar-Cavity Receiver Configuration for High-Temperature Solar Thermal Processes

Next-generation concentrating solar thermal power (CSP) technologies target a wide spectrum of applications including electricity generation, thermochemical processes, and industrial process heat for broad decarbonization potential. Many of these applications require higher temperatures than those of current commercial nitrate salt systems. Particulate materials are promising candidates for next-generation high-temperature heat transfer and low-cost storage media and can facilitate operation over a wide temperature range. However these materials necessitate novel receiver configurations to accept the high incident flux concentrations that enable high solar-to-thermal receiver efficiency. One option is a novel light-trapping planar cavity receiver configuration in which small cavity-like structures are formed from opaque planar surfaces such that a high incident flux concentration at the cavity aperture is reduced to a wall-absorbed solar flux concentration that is manageable within limited wall-to-particle heat transfer rates. The paper introduces the receiver configuration and provides calculated optical performance for a preliminary 50 MWt receiver design.

Polarization analysis of two baryons with various spin combinations produced in electron-positron annihilation

We develop a systematic approach to analyze polarization correlations of two baryons B1B¯2 produced in the electron-positron annihilation process. With spin density matrices for arbitrary spin particles established in the standard, the Cartesian, and the helicity forms, we provide analyses of polarization correlations for two baryons with various spin combinations. This framework can be applied to determine the spin and the parity of excited baryons, and therefore offers opportunities for the investigation of baryon spectrum and transition form factors in present and future electron-positron annihilation experiments. Published by the American Physical Society 2024

Development, characterization and validation of a novel physics-informed equivalent circuit model for silicon–graphite battery cells

The widespread deployment of electric vehicles (EVs), as well as the growing requirements both from manufacturers and consumers, necessitate an increase in energy density with regard to current lithium-ion batteries (LIBs). In this regard, one of the most promising alternatives is the addition of silicon to conventional graphite anodes, thus giving rise to energy-dense LIBs. However, this entails a significant increment in modeling, parameterization and computational complexities due to the interactions between both negative electrode materials. In this article, we present a novel physics-informed equivalent circuit model for cells with blended electrodes, which is able to provide accurate results with respect to a state-of-the-art electrochemical model, not only for the output voltage (≤25 mV RMS), but also internal states, namely active material particle surface concentrations (≤1.2 %) and current distribution (≤2.6 %) at a much lower computational cost. Furthermore, this formulation also allows for a notable simplification of model parameterization. Hence, we describe thorough static and dynamic parameterization processes from half-cell experimental data and impedance measurements. Finally, we validate the proposed model in constant-current as well as dynamic operation, highlighting the influence that the choice of hysteresis model has on the latter. We understand that the presented model is an interesting alternative for the modeling of cells with blended electrodes, and is also suitable for its implementation in Battery Management Systems (BMSs) in EVs.

2D Discrete Element Simulation of Electrode Structural Evolutions in Li‐Ion Battery During Drying and Calendering

Drying and calendering are critical steps in the manufacture of electrodes for lithium‐ion battery that affect their mechanical and electrochemical properties. A 2D representative volume element (RVE) model, including active material and carbon binder domain particles of different shapes and sizes, is developed. The evolution of the RVE structure is simulated using the discrete element method, providing insight into changes in velocity, coordination number, porosity, pore size distribution, tortuosity, and stress. Based on this analysis, a three‐step drying scheme is proposed in accordance with the experimental drying results. In addition, the calendering process significantly improves the mechanical integrity and electronic conductivity of the electrode. Through simulations and experimental observations of changes in surface morphology and porosity, an optimal compression ratio of about 20% is determined for the electrode.