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In order to describe the movement characteristics of large-particle high-density charge and the development process of flow field and flame spreading in the chamber, a new modified and simplified p...

The effects of corona wire distribution on characteristics of electrostatic precipitators were numerically studied. The electric field, charge density and removal efficiency were discussed at various Sww/Swp (ratio of wire-wire length to wire-plate length). The electric field and charge density had an oscillating distribution on the collecting plates. With the decrease of Sww/Swp, the electric field on collecting plates increased. The average corona current decreased continuously while the total current increased first and then decreased. The large particle removal efficiency increased continuously while the efficiency for small particles increased first and then decreased. The highest small particle removal efficiency was obtained at Sww/Swp = 1.2.

Particle mixtures with a wide range of sizes, shapes, and densities may experience significant segregation. In the hopper discharging process, segregation predominantly happens on the free surface of mixtures with size ratio

The size-controlled preparation of Mo powders is always a challenge and important task in the molybdenum metallurgy. In the current study, Mo powders with controllable sizes are synthesized by hydrogen reduction of MoO2 powders with the assistance of Mo nuclei in the range of 900–1100 °C. The influences of the particle sizes of Mo nuclei, the additive amount as well as reaction temperature on the morphology and particle sizes of the final products are studied. For the hydrogen reduction of MoO2 without any additive, the obtained Mo powders always have large particle sizes. However, the addition of small amounts of nuclei in MoO2 can help Mo nucleate dispersedly, and the growth of Mo could be also controlled by adjusting the sizes of added nuclei, amount of addition and the reaction temperature. With the addition of Mo nuclei, the different sizes of Mo powders with the good dispersity can be prepared. As adding commercial Mo powders with the particle size of about 2.03 μm, the micron-sized Mo powders ranged from 2.11 μm to 3.25 μm could be prepared. While for the case of adding ultrafine Mo nuclei of about 170 nm, Mo powders from 0.28 μm to 0.88 μm can be obtained. Moreover, the more the amounts of nuclei added and the lower the reaction temperature (in the range of 900–1100 °C) is, the smaller the particle size of the prepared Mo powder will be. The current method is a facile and feasible method, and is potential to be used for industrial production of Mo powder with controllable particle sizes.

The frequency and temperature dependences of the magnetic susceptibility of magnetic colloids with large particle sizes placed in porous media have been found to be different from the similar dependences for bulk samples. The observed peculiarities can be explained by the influence of surface phenomena on the processes of relaxation of the magnetic moment of colloidal particles.

High shear granulation of powders with a wide size distribution can lead to the formation of core-shell particles consisting of a few larger particles in the core with a shell of fine particles. We demonstrate successful scale down of core-shell granule formation and, using a new model for interpreting observed cross-sections, show that above a critical speed the shell-thickness remains constant at about ~5% of the granule diameter with a crushing strength of about 5.5 MPa. Below this speed and at low fill-levels, shell-thickness increases and granule strength reduces. Under a low mixing intensity at the lowest fill-levels core-shell particles are not formed at all. Theoretical work on the strength of liquid bridges shows that small particles attached to each other would redistribute more easily than the same particles attached to a large particle. We propose therefore that a detachment-reattachment process is responsible for the formation of core-shell granules.

LiNi0.8Co0.1Mn0.1O2 with unique shell-pore structures is synthesized by a modified co-precipitation method. SEM images show that the synthesized materials are consisted of large particle (10–15 μm) with pores dispersed in the shell structure. Ex-situ SEM and ex-situ XRD analyses imply that the shell-pore may help to relieve the microstress generated during the long cycles, thus suppressing the formation of microcracks, alleviating the corrosion from electrolyte since less fresh interface exposed, and finally maintaining the layered structure. In addition, the shell-pore structure may also help improving the wettability of electrolyte and accelerating the Li ions transport. Accordingly, the samples with shell-pore structure own better cycle stability and rate performance. Specifically, they exhibit capacity retention of 90.33% after 100 cycles at 1C rate with the capacity of 169.7 mAh/g. It also improves the rate performance with the capacity of 157.3 mAh/g at 2C rate and 144.1 mAh/g at 5C rate respectively. Moreover, the modified co-precipitation method helps improving the compacted density of the as-prepared material.

We present a theoretical investigation on the dynamic characteristics of a nanomechanical resonator attached with an adsorbate at an arbitrary position. Cantilevered and bridged configurations are both considered for the resonators. Closed-form expressions relating the exact mode shape and the resonant frequency of the loaded resonator are obtained analytically using the Rayleigh–Ritz theorem, from which the relationship between the adsorbate mass and changes in the dynamic characteristics can be obtained. The results indicate that the mode shape change due to adsorption of a relatively large particle can influence the performance of the nanomechanical resonator considerably.

Zeolite synthesis using faujasite-type (FAU) zeolites as the starting silica/alumina source in the presence of various organic structure-directing agents (OSDAs) with cyclic alkylammonium structures was investigated. The obtained zeolite phases strongly depended on the structure of the OSDA and the Si/Al ratio of the starting FAU. Zeolites with different framework structures, such as BEA, MFI, CHA, and LEV, were obtained. Among the used OSDAs, methylpropylpyrrolidinium, butylmethylpyrrolidinium, and methylpropylpiperidinium effectively produced nanosized BEA and MFI zeolites, whereas dimethylpiperidinium and cyclohexyltrimethylammonium produced CHA and LEV zeolites, respectively. The nanosized MFI and BEA zeolites obtained through zeolite hydrothermal conversion exhibited remarkably smaller particle sizes and higher external surface area as compared to those of the conventional MFI and BEA zeolite samples synthesized using tetrapropylammonium and tetraethylammonium, respectively. We also found that the highly crystalline nanosized BEA and MFI zeolites exhibited better catalytic performance in the dehydration of benzyl alcohol to benzyl ether as compared to the conventional zeolites with large particle sizes. In addition, nanosized MFI zeolites, synthesized using FAU as a starting material and cyclic ammonium compounds, showed catalytic activities superior to those of the nanosized MFI zeolites synthesized from amorphous starting materials and cyclic ammonium compounds.

Undoubtedly, the yield stress is the most relevant rheological property of a magnetorheological (MR) fluid. However, available analytical and simulation methodologies to compute the magnetostatic interparticle interactions that govern the yield stress, fail at large particle concentrations and large strain levels. In this communication we propose a 3D finite element methodology (FEM), to compute the yield stress, that grounds on a reduced magnetic field formulation and periodic boundary conditions. This approach takes into account multibody and multipolar interactions and satisfactorily simulates large concentrations and strains. Experiments are also carried out in a torsional magnetorheometer for a wide range of MR formulations. Experimental results obtained are in very good agreement with FEM simulations.

Here we evaluate the performance of bump arrays to separate large particles from non-Newtonian slurries with Bingham and Cross rheology. Bump arrays in deterministic lateral displacement devices separate large particles from small particles using arrays of staggered posts. Large particles, defined as those with radii larger than the distance between the edge of a post and the stagnation streamline from the next downstream post, must bump toward one side of the device, whereas particles smaller than this distance slalom from entrance to exit without net lateral displacement. Although these devices have been used to separate a wide variety of large particles from blood cells to sand, partition of large particles from non-Newtonian fluids remains unexplored. Yet, an important set of modestly concentrated slurries, including Hanford nuclear waste, displays non-Newtonian rheology. Here we evaluate the influence of non-Newtonian rheology on the large-small particle size cutoff in bump arrays using a model that explores the influence of yield stresses, ratios of zero and infinite shear viscosities, and Cross’s exponent under strictly laminar well-developed conditions. Surprisingly, we find that viscosity ratios and Cross’s exponent make no significant difference on the particle cutoffs between large particles that bump and small particles that slalom around the posts from entrance to exit. In contrast, we find that yield stresses do significantly affect the size cutoff. As the yield stress increases, velocity profiles become more plug like lowering the size cutoff. For nuclear waste separations where removing large particles is a priority, increasing yield stresses is conservative.

For subsea mining, it is important to predict the pressure loss in oscillating pipes with pulsating flow for the safe and reliable operation of ore lifting. In the present paper, the authors focused on the pulsating internal flow in static vertical pipe and carried out slurry transport experiment to investigate the effects of flow fluctuation on the pressure loss. The alumina beads and glass beads were used as the solid particles in the experiment, and the fluctuating periods and amplitudes of pulsating water flow were varied. The time-averaged pressure losses calculated by the prediction method for the steady flow proposed in the past by the authors agreed well with the experimental ones. As for the fluctuating component of pressure loss, the calculation results using the quasi-steady expression of a mixture model were compared with the experimental data. The calculated results were different from experimental ones for alumina beads of which densities are almost same as those of the ores of Seafloor Massive Sulfides. It suggests that the expression is insufficient to predict the pressure loss for heavy solid particles. The calculated ones, however, provided those in the safety side. On the other hand, the calculated results for light solid particles such as glass beads agreed well with the experimental ones. It means that the expression would be applicable to the prediction of pressure loss for the mining of manganese nodules which are lighter than the ores of Seafloor Massive Sulfides.

In the process of hydraulic lifting of solid mineral particles on the seabed, the two-phase flow in the pipeline causes wall wear, which reduces the reliability of the hydraulic lifting system. In this research, based on the coupled computational fluid dynamics (CFD) and discrete element method (DEM), the numerical simulation of large particle solid–liquid two-phase flow and wall wear in a bend pipe with different wall shapes was conducted to provide solutions for reducing wall wear. By adding bumps to the bend pipe wall to change the shape of its inner wall, under the working conditions of particle concentrations of 1–10% and particle sizes of 1–3 mm, wear experiments and calculations for the bend pipe with bumps at different positions were performed. With comparative analysis, it was found that the location of the bump in the bend pipe had an important influence on the maximum wear rate. When the bump was located near the location where the particles collided with the prototype bend pipe for the first time, the maximum wear rate decreased the most significantly. The particle mass flow rate will also affect the wear reduction effect of the bump on the bend pipe wall.

We measure the upward force acting on a single, unconstrained, large particle in a granular medium of small particles flowing over inclined plane using discrete element method (DEM) simulation. Based on the computed force, we obtain an expression for the flux of large particles in a binary mixture of large and small particles and predict the equilibrium concentration profile and the velocity profile of the flowing layer. The theoretical predictions are in very good agreement with the DEM simulation results for a wide range of concentrations of large particles and inclination angles.

Heavy metals, including chromium, are associated with developed industrialization and technological processes, causing imbalanced ecosystems and severe health concerns. The current study is of supreme priority because there is no previous work that dealt with the modeling of the optimization of the biosorption process by the immobilized cells. The significant parameters (immobilized bacterial cells, contact time, and initial Cr6+ concentrations), affecting Cr6+ biosorption by immobilized Pseudomonas alcaliphila, was verified, using the Plackett–Burman matrix. For modeling the maximization of Cr6+ biosorption, a comparative approach was created between rotatable central composite design (RCCD) and artificial neural network (ANN) to choose the most fitted model that accurately predicts Cr6+ removal percent by immobilized cells. Experimental data of RCCD was employed to train a feed-forward multilayered perceptron ANN algorithm. The predictive competence of the ANN model was more precise than RCCD when forecasting the best appropriate wastewater treatment. After the biosorption, a new shiny large particle on the bead surface was noticed by the scanning electron microscopy, and an additional peak of Cr6+ was appeared by the energy dispersive X-ray analysis, confirming the role of the immobilized bacteria in the biosorption of Cr6+ ions.

A three-dimensional numerical simulation of the motion – heat-transfer coupling characteristics of waste tyre particles in a rotary kiln at 773–973 K was performed in this study. The particle dynamics and heat transfer characteristics were solved on a Lagrange grid. The motion model considered particle collisions using a nonslip collision model. Based on the particle motion results obtained, we considered three heat transfer mechanisms: particle–particle collision heat conduction, wall–particle radiation heat transfer, and wall–particle collision heat conduction. Subsequently, we established a mathematical model wherein the heat transfer associated with a particle is determined by its position in each time step, and implemented it on a JAVA platform to perform calculations. Finally, we obtained the temperature of each particle at each moment in the entire process. Further analysis of the simulation results shows that the average temperature and temperature standard deviation is governed by the wall temperature, rotation speed, and particle size.

The synthesis of a porous-type of TiO2 with rutile structure was studied. The focuses were on the thermal treatment temperature and time. AEROXIDE® TiO2 P 25, as a fumed TiO2, was thermally treated in a vertical-type tubular furnace by the natural dropping method. Even though the thermal treatment time was less than 1 s, a drastic increase of polymorphism from anatase structure to rutile structure was observed. The relationships between the rutile structure transformation ratio and surface area of obtained porous type of TiO2 were investigated depending on the thermal treatment temperature. The porous-type of fumed TiO2 showed high dispersibility in the sedimentation test although is showed large particle size.

A 2D cylinder transient heat transfer model was developed for single-particle oil shale pyrolysis in the fixed-bed reactor. Variations of physical properties of oil shale were considered in this model. The developed model was solved using ANSYS after determining boundary conditions. And then intraparticle temperature distribution was obtained during oil shale pyrolysis. Moreover, effects of particle size and heating rate on intraparticle temperature distribution were investigated. The radius of 30-mm oil shale and pyrolysis time were divided into ten equal intervals to calculate temperature at any time and any position during the sample pyrolysis. The calculated results reasonably agreed with actually measured temperature.

Geckos have one of the world's most efficient reversible adhesion systems. Even walking in dusty conditions, geckos can dislodge up to 80% of contaminants and recover their adhesion capability after walking as few as four steps. Thus far, artificial dry self-cleaning materials inspired by the geckos' hierarchical fibrillar structure have been only able to remove 55% of collected large particle contaminants with 30 steps. Challenges, including low mechanical strength, low stiffness, and short fatigue time keep these materials from being used in practical applications. This study involves the novel fabrication of dry self-cleaning surfaces with a high mechanical performance and an outstanding dry self-cleaning property. Imposing a load-drag-pull process similar to a gecko's foot adhesion process, our biomimetic surfaces could dislodge up to 59% of microparticles (∼8 μm) with as few as five steps. Furthermore, the surface had an excellent screening ability at low temperatures regardless of the surface roughness similarity. The surfaces were also proven to be scratch resistant. The biomimetic surfaces exhibit enhanced dry self-cleaning and mechanical properties and could be promising in applications such as reusable adhesives, biochips, aerospace satellite waste collection, and screening equipment.

To increase hardness and to reduce surface roughness of an extruded billet, an oil containing fine ceramic particles was used in extrusion. During extrusion, the fine ceramic particles in the oil flowed into the interface between the billet and die. The some particles were embedded on the billet surface by deformation. The hardness in the surface of extruded billet increased by the embedded particles. The billet surface was polished by the particles in the oil. The hard fine ceramic particles such as SiO2, ZrO2 and Al2O3 having 20 nm to 1000 nm in the particle diameter were used for aluminium alloy A5056 billets. The effects of material, the particle diameter and constituent on the hardness and surface roughness of the extruded billet were investigated. To reduce the surface roughness, the large particle diameter with the high constituent was effective. The hardness of the extruded billet using the oil containing fine ceramic particles was larger than that without the fine ceramic particles. It was found that the use of the oil containing the fine ceramic particles is effective in hardening and reducing the surface roughness of the extruded billet.

This paper describes an extensive study on thermal conductivity (TC) of polymer composites with randomly distributed hybrid fillers. Finite element method in combination with user-defined code is used to predict accurately the TC of these composites under many effects and effective parameters such as volume fractions (VFs) and TC ratios of fillers to that of the matrix. A literature review on the TC prediction models of hybrid-filler polymer composites is studied and discussed. The effects of particle distribution and particle size of hybrid filler are also taken into account and analyzed. It was found that these effects become important and affect significantly to the effective TC, particularly at high VF, high TC, and large particle size. Remarkably, a modified Hashin-Shtrikman model is first proposed based on an extensively numerical results. It can be widely utilized for predicting the TC of polymer composites with randomly distributed hybrid fillers accurately and effectively, regardless of non-spherical filler shape.

The clinical ultrasound (US)-based theranostic biomedicine suffers from the critical issue that traditional microbubbles (MBs) have lots of drawbacks such as low stability, large particle size, difficult structural control, etc. The unique composition, structure and functionality of inorganic micro/nanoplatforms have shown their great prospect for solving these critical issues and drawbacks of traditional organic MBs. This review summarizes and discusses the state-of-art development on exploring inorganic micro/nanoparticles for versatile US-based biomedical applications, ranging from US imaging, photoacoustic imaging, sonodynamic therapy, high intensity-focused US ablation and US-triggered chemotherapy. These inorganic micro/nanoplatforms include silica-based particles, Au, carbon nanotubes, TiO2, manganese oxide, iron oxide, Prussian blue, inorganic gas-generating nanoparticles and their versatile composite micro/nanosystems. Especially, their unique structure/composition-functionality relationships and biocompatibility/biosafety in US-based theranostics have been discussed and revealed in detail. Their facing challenges and future developments are finally discussed to promote their further clinical translations. It is highly expected that these inorganic micro/nanoplatforms will enter the clinical stage to benefit the personalized theranostics biomedicine based on their unique functionalities and high performance as necessarily required in US-based theranostics.

Colloid mill attrition can remove the oxidized layer from oxidized coal surface. The effects of colloid mill gap space and milled pulp density were investigated according to the flotation response. It was found that both particle size reduction and flotation recovery enhancement were higher at higher pulp density and smaller gap space. When colloid mill worked at higher pulp density and smaller gap space, oxidized layers of coal particles could be removed more thoroughly. In addition, the greater reduction in particle size at higher pulp density and smaller gap space should be conductive to the flotation of oxidized coal because large particle size of oxidized coal is considered not suitable for its flotation. Because colloid mill was successfully applied in improving oxidized coal flotation, the results of this paper will promote the industrial application of colloid mill into effective flotation of oxidized coal in coal preparation plants.

In a fluidized bed system, mean trajectories of fuel particles within the bed of fluidized inert particles are governed by the associated drag forces and characterize hydrodynamic, chemical and thermal processes taken place in the system. A large particle size ratio between the bed material and the fuel particles affects the hydrodynamics of gas-solid multiphase flows via influencing the drag forces between solid phases. The present work focuses on the analysis of forces between the two solid phases with large size ratios using the Lagrangian simulations of discrete element method (DEM). The results are spatially averaged over variable control volume size for comparison to the continuum interphase momentum transfer model. Using our DEM simulation results, a correction factor of drag force is presented versus the size of averaging control volume usable in continuum models. In addition, the role of inhomogeneity of particles distribution within the averaging box is discussed. Post-print / Final draft

We develop a tensorial constitutive model for dense, shear-thickening particle suspensions subjected to time-dependent flow. Our model combines a recently proposed evolution equation for the suspension microstructure in rate-independent materials with ideas developed previously to explain the steady flow of shear-thickening ones, whereby friction proliferates among compressive contacts at large particle stresses. We apply our model to shear reversal, and find good qualitative agreement with particle-level, discrete-element simulations whose results we also present., Comment: 6 pages, 4 figures

In this paper, a new recycled aggregate concrete (RAC) was produced with composite coarse aggregate and fine recycled aggregate. The composite coarse aggregate was mixed into continuous gradation by large particle natural aggregate with small particle recycled aggregate. To explore the time-dependent developments of the compressive strength and splitting tensile strength of this new RAC, 320 groups of cubic specimens were tested at different curing ages from 3 days to 360 days to measure the compressive and splitting tensile strengths. The amount of large particle natural aggregate varied from zero to 70% in mass of the total coarse aggregate. The water/cement ratio was taken as 0.60, 0.49, 0.41 and 0.36 to represent four strength grades of the RAC at about C20, C30, C40 and C50. Based on the tested results, the curves of the compressive and tensile strengths of the RAC that changed with curing age are plotted, which clearly exhibit that the amount of large particle natural aggregate had a rational range in different strength grades of the RAC which had better aging strength. When the RAC was no larger than C30 with a water/cement ratio of 0.60 and 0.49, the amount of large particle natural aggregate should be no more than 30%, when the RAC was no less than C40 with a water/cement ratio of 0.41 and 0.36, the amount of large particle natural aggregate should be no less than 50%. Along with the general prediction of the strength development of all the tested RAC, the optimal predictive formulas are proposed for the strength development of RAC with a rational amount of natural aggregate. Meanwhile, the strength developments of RAC with a rational amount of natural aggregate are assessed by the time-dependent models proposed by the ACI Committee 209 and CEB-FIP MC 2010.

In a consortium analysis of a large particle captured from the coma of comet 81P/Wild 2 by the Stardust spacecraft, we report the discovery of a field of fine-grained material (FGM) in contact with a large sulfide particle. The FGM was partially located in an embayment in the sulfide, so appears to have been largely protected from damage during hypervelocity capture in aerogel. Some of the FGM particles are indistinguishable in their characteristics from common components of chondritic-porous interplanetary dust particles (CP-IDPs), including glass with embedded metals and sulfides (GEMS) and equilibrated aggregates (EAs). The sulfide exhibits surprising Ni-rich lamellae, which may indicate that this particle experienced a long-duration heating event after its formation but before incorporation into Wild 2. We discuss the relationship of the FGM to the sulfide, to other Wild 2 particles and to the history of the Solar nebula.

Significance Despite being a leading cause of foodborne illnesses, accounting for 58% of all outbreaks and over 96% of nonbacterial outbreaks, there are no approved treatments available for norovirus infections. Assembled shells of the viruses without genetic materials enclosed are currently being used as candidates for vaccine trials. Although the virus shells have been thought to exist in a single-sized assembly, our structures in near-atomic detail reveal clear variations in size between different outbreak strains, and in spatial and angular arrangements of the antigenic surface spikes. The structures we present serve as valuable templates for facilitating vaccine formulations., Noroviruses are a leading cause of foodborne illnesses worldwide. Although GII.4 strains have been responsible for most norovirus outbreaks, the assembled virus shell structures have been available in detail for only a single strain (GI.1). We present high-resolution (2.6- to 4.1-Å) cryoelectron microscopy (cryo-EM) structures of GII.4, GII.2, GI.7, and GI.1 human norovirus outbreak strain virus-like particles (VLPs). Although norovirus VLPs have been thought to exist in a single-sized assembly, our structures reveal polymorphism between and within genogroups, with small, medium, and large particle sizes observed. Using asymmetric reconstruction, we were able to resolve a Zn2+ metal ion adjacent to the coreceptor binding site, which affected the structural stability of the shell. Our structures serve as valuable templates for facilitating vaccine formulations.

In order to study the wear characteristic of a centrifugal pump at different mass concentrations, simulation and experimental research were carried out. The simulation was based on the DPM (discrete phase model) to complete the coupling of particles and the flow field. The experimental research included a performance test and a wear test. Through the comparison of the simulation and experimental research results, the relationship between the particle movement and the wear was analyzed, and the flow field was analyzed through the energy gradient theory. The energy gradient and the particle movement were combined to explain the wear characteristics. When the particles entered the impeller flow area, they directly hit the leading edge of the blade and the hub wall. The particles were sinking due to the flow field, which caused the particles to accumulate near the hub and the pressure surface. These places were at the most severely worn wall. The farther away from the axis the position was, the greater the relative velocity difference between the particles and the wall was, so that wear occurred first in these places. The low-energy properties near the hub made particles gather there, which was also the most serious cause of hub wear.

Segregation of granular materials under vibration or flow conditions such as the Brazil nut effect has been well known, however, there is yet no consensus mechanisms to explain this phenomenon. This study attempts to investigate particle buoyant forces in the segregation process. To explain the difference of the segregation behavior for the large particle with different size, a modified calculation method of particle buoyant force is suggested for considering the effect of particle size ratio. A simple verification illustrates its validity.

The perovskite membrane with large particle size, uniform coverage and high quality is the prerequisite for the preparation of efficient and stable perovskite solar cells. Various additives have been used to increase the grain size and improve the film morphology and crystal quality. In this paper, methylammonium chloride (MACl) was proposed to obtain high crystalline quality of [Formula: see text] perovskite absorption layer. The results show that the adding ammonium methyl chloride into the precursor of tricationic perovskite not only passivates surface defects to form high-quality and large-grain perovskite films, but also facilitates the formation of pure [Formula: see text]-phase [Formula: see text]. Meanwhile, the designed perovskite precursor solutions were used to fabricate mesoporous perovskite solar cells (PSCs). Owing to the perovskite layer consisting of optimized MACl doping, the short-circuit current density [Formula: see text] of PSCs reaches 23.81 mA/cm2, which is 2.73 mA/cm2 higher than the primary [Formula: see text] based on PSCs. The obtained power conversion efficiency (PCE) increases from 13.67% to 17.59%.

The breakup dynamics of compound droplets containing large particle inside (S/W/O) in a flow-focusing microfluidic device were systematically investigated, and four typical flow regimes, regarding multiple-encapsulation, slug, transition and cobble, are distinguished. At low flow rate of outer fluid, Qc

The goal of this study was to justify the reprocessing of recycled HDDR Nd-Fe-B powders with spark plasma sintering (SPS) and to investigate the dependence of the final magnetic properties on SPS and thermal treatment. The initial recycled HDDR powder of the composition Nd13.4Dy0.6Fe78.6B6.1Nb0.4Al0.7 with 4760 ppm O2 content, coercivity (HCi) = 830 kA/m, and large particle size distribution

Experiment were conducted to investigated the flow characteristics of airlift pumps operating in gas-liquid-solid three phase flow by employing a high-speed camera. The results showed that an intermittent flow consisted of film and liquid slug appeared in airlift pumps with a flow frequency of 1.5–2.6 Hz. The portion of slug body directly determined the performance of airlift pumps due to a large particle concentration. In practical engineering, some methods for increasing the portion of slug body could be used for better pump performance.

This paper mainly studied the influence of particle size distribution on the explosion risk of aluminum powder under the span of large particle size distribution. The measurement was carried out with the 20 L explosion ball and the Hartmann tube. The statistical analysis was used to analyze the relevance between the parameters of explosion risk and the particle size parameters. Test results showed that with the increase of particle size, the sensitivity parameter increases and the intensity parameter deceleration decreases. The effect of particle size change on MEC and MIE of small particle size aluminum powder is relatively small but greater impact on Pm and (dP/dt)m. The small particle size components greatly increasing the sensitivity of the explosion and accelerating the rate of the explosion reaction; while the large particle size component contributes to the maximum explosion pressure. D3,2 particle size dust determines the risk of aluminum powder explosion.

This paper investigates the effect of clay content on the shear strength of clay–sand mixtures. Bentonite and Jumunjin sand were mixed to prepare clay–sand mixtures with varying clay contents of 5, 10, 15, 20, 25 and 30%. The shear strength of clay–sand mixture was measured using direct shear tests and angle of repose tests in dry condition. The angle of repose of the clay–sand mixture was measured to be greater than that of pure sand for the studied range of clay contents. Likewise, the internal friction angle of the clay–sand mixture was measured to be higher than that of pure sand, reaching a peak at the clay content of 10%. Theoretically, the behavior of the clay–sand mixtures was to be governed by large size particles at clay contents smaller than 23.5%, which agrees well with the visual inspection on the mixtures. At clay content of 25.1% or greater, where the contribution of large particle was theoretically assumed to be none, the results from the angle of repose tests were significantly scattered, indicating that the clay started playing a key role in the behavior of mixtures.

The flow of particulate materials is critical during processes such as mixing, compression and packing. Non-cohesive arching, a feature characteristic of coarse and free-flowing particles, has been studied extensively for silos and hoppers. However, the arching of powders during die fill has received much less attention. In this study, die fill performance of coarse and free-flowing nonpareils was evaluated using a specially designed die filling device in order to investigate the impact of non-cohesive arching during die fill under gravity flow. Through evaluating die fill performance, the arching phenomenon during dynamic conditions of die fill could be captured. Nonpareils with large particle size increased the likelihood of arching and caused poorer die fill performance for narrow orifices. In contrast, die fill in large orifices was generally better with larger particles due to reduced inter-particulate friction. Both particle size and size distribution influenced non-cohesive arching during die fill. Forced feeding did not appear to affect die fill performance and non-cohesive arching. A critical particle size range beyond which die fill performance would decrease, particularly for the narrow orifices, was identified. Findings from this study provided a better insight into non-cohesive arching during die fill.

We present simulation studies of solid solutions formed upon compression of mixtures of Lennard-Jones particles with diameter ratios 2:1 and 3:1. Grand canonical Monte Carlo (GCMC) and Gibbs-Duhem integration were used to determine the compositions of coexisting solid and liquid phases at several pressures and fixed temperature. Concentrations of small particles dissolved in interstitial sites of the large-particle lattice, under liquid-solid coexistence conditions, were determined directly from GCMC simulations. Indirect methods were used to calculate levels of small particles dissolved substitutionally, either singly or in plural, with the average number of small solutes occupying a lattice site vacated by a large particle increasing with higher pressure. In the cases studied, the fraction of small solutes occupying these substitutional sites was found to be small (2% or lower, depending on the mixture and conditions), but to stay roughly constant with increasing pressure. Structural and dynamic characteristics of the solid solutions are described and compared with reported characteristics of the related interstitial solid solution formed by hard spheres.

The efficiency of the klystrons is great interest at large particle accelerators, in terms of power consumption and performance of accelerators. To increase the efficiency, TETD (Toshiba Electron Tubes & Devices co., ltd.) introduced core oscillation and smooth bunching approach into a TETD's commercial model klystron for early evaluation by minimal changes. The efficiency of the design result was 59% at 6MW peak output RF power, and that of test result was 58%. It was proved that new approach was useful, and expansion to other conventional models could be expected due to simple structure and minimal modification.

A new method named two-step emulsification process was developed to synthesize high solid content waterborne polyurethanes by strict control of the bimodal particle size distribution. In the first step, a series of 40% solid content polyester-based (WPU-1) with low content of hydrophilic group and large particle size were firstly synthesized. In the second step, polyether-based prepolymers (WPU-2 prepolymers) with high content of hydrophilic group were firstly prepared and WPU-1 emulsions were used to emulsify WPU-2 prepolymers to obtain the final emulsions with high solid content (WPU-3). The particle size of WPU-3 present bimodal distribution and the diameter ratio and volume percentage of large particles to small particles in WPU-3 were able to be strictly controlled by this method. The viscosity of WPU-3 with 55% solid content was only 489.1 mPa s −1 when the diameter ratio of large particles to small particles was 9.2 and the volume percentage of large particles was 74%.

In this study, micron-sized spherical AlN granules were delicately synthesized by carbothermal reduction–nitridation (CRN) route with the aid of Y 2 O 3 additive. The effects of synthesis parameters and Y 2 O 3 content on the nitridation rate, particle size and especially on the surface morphology were systematically investigated. The results showed that the reduction and nitridation of intermediate Y-aluminates were extremely significant to promote the formation of micro-sized spherical AlN granules by improving the nitridation rate, increasing the grain size, providing the spherical morphology and promoting the uniform growth of AlN granules. Furthermore, the elevated N 2 gas pressure, high reaction temperature also made contribution to the formation of spherical morphology and large particle size. Based on the experimental results, the underlying reaction mechanism in the carbothermal synthesis of spherical AlN granules with Y 2 O 3 was attentively proposed.

Electrochemical performances of LiCoO2 as a candidate material for supercapacitor are systematically investigated. LiCoO2 nanomaterials are synthesized via hydrothermal reaction with consequent calcination process. And the particle size increases as the calcination temperature rises. LCO-650 sample with the largest particle size displays the maximum capacitances of 817.5 F·g−1 with the most outstanding capacity retention rate of 96.8% after 2000 cycles. It is shown that large particle size is beneficial to the electrochemical and structural stability of LiCoO2 materials. We speculate that the micron-sized waste LiCoO2 materials have great potential for supercapacitor application. It may provide a novel recovered approach for spent LIBs and effectively relieve the burdens on the resource waste and environment pollution.

Although tire-derived aggregate (TDA) has been used widely as lightweight fill in civil engineering applications, the properties governing its response under cyclic loading are not well und...

It is known that pastes of fine powder, for example those of clay, retain memory of shaking applied early in a drying process. This memory results in the appearance of anisotropic patterns of desiccation cracks after drying. In this work, we find a similar behavior in pastes consisting of large granular particles, specifically cornstarch and Lycopodium spores. Because of the large particle size, we were able to observe particle arrangements in Lycopodium paste with micro-focus X-ray computerized tomography ( $\mu$ CT). We prepared pastes consisting of Lycopodium particles and water. Agar was added to the paste in order to allow for solidification during a drying process. In these samples, we found statistical anisotropy induced by shaking applied early in the drying process. This anisotropy possesses a feature that was predicted on the basis of results obtained in previous experimental and theoretical studies.

Deterioration and damage of pavements require rapid and durable full-depth repair. This study proposes an innovative rapid repair structure for the incorporation of precast slabs, graded gravel bases, and grouting technology in concrete pavements. Two representative grouting materials and two types of graded gravel bases with different particle size compositions were selected to construct four types of rapid repair structures. Static stepwise loading, fatigue loading, and lateral loading tests were conducted to evaluate both the effectiveness and feasibility of the rapid repair structures by measuring deformation, strain, and pressure as well as by examining the failure modes of the repair structures. The results indicated that the high strength grouting material contributes to the mechanical properties and bonding performance of the repair structure. Moreover, a well-compacted base is critical for the deformation uniformity of the repair structures and a graded gravel base with large particle size provides firm support, which is conducive to the infiltration of grouting material. The rapid repair structure proposed in this work not only reduces the time and cost required to re-open traffic, but also meets the requirements of a semi-permanent repair of concrete pavement. However, a full-scale investigation needs to be conducted to assess the mechanical properties for rapid repair structure.