Search

Adsorptive C2H2/C2H4 separation using metal–organic frameworks (MOFs) has emerged as a promising technology for the removal of C2H2 (acetylene) impurity (1 %) from C2H4 (ethylene). The practical application of these materials involves the optimization of separation performance as well as development of scalable and green production protocols. Herein, we report the efficient C2H2/C2H4 separation in a MOF, Cu(OH)INA (INA: isonicotinate) which achieves a record C2H2 packing density of 351 mg cm−3 at 0.01 bar through high affinity towards C2H2. DFT (density functional theory) calculations reveal the synergistic binding mechanism through pore confinement and the oxygen sites in pore wall. The weakly basic nature of binding sites leads to a relatively low heat of adsorption (Qst) of approximately 36 kJ/mol, which is beneficial for material regeneration and thermal management. Furthermore, a scalable and environmentally friendly synthesis protocol with a high space‐time yield of 544 kg m−3 day−1 has been developed without using any modulating agents. This material also demonstrates enduring separation performance for multiple cycles, maintaining its efficacy after exposure to water or air for three months. [ABSTRACT FROM AUTHOR]

Adsorptive C2H2/C2H4 separation using metal–organic frameworks (MOFs) has emerged as a promising technology for the removal of C2H2 (acetylene) impurity (1 %) from C2H4 (ethylene). The practical application of these materials involves the optimization of separation performance as well as development of scalable and green production protocols. Herein, we report the efficient C2H2/C2H4 separation in a MOF, Cu(OH)INA (INA: isonicotinate) which achieves a record C2H2 packing density of 351 mg cm−3 at 0.01 bar through high affinity towards C2H2. DFT (density functional theory) calculations reveal the synergistic binding mechanism through pore confinement and the oxygen sites in pore wall. The weakly basic nature of binding sites leads to a relatively low heat of adsorption (Qst) of approximately 36 kJ/mol, which is beneficial for material regeneration and thermal management. Furthermore, a scalable and environmentally friendly synthesis protocol with a high space‐time yield of 544 kg m−3 day−1 has been developed without using any modulating agents. This material also demonstrates enduring separation performance for multiple cycles, maintaining its efficacy after exposure to water or air for three months. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSThe aggregate size and particle-size distribution (PSD) can change the packing density, slump, and strength of concrete. The micromechanical effects of aggregate size on the slump and strength remain unclear. The current numerical study examined concrete behavior using slump and uniaxial compressive strength (UCS) tests considering the aggregate size distribution using the discrete element method. The effect of the aggregate size on the packing density, UCS, and slump of the concrete was analyzed. To accomplish this, we evaluated how variations in the uniformity and curvature coefficients of the PSD, as well as the specific surface area of the samples, were affected by changes in aggregate size. Although the simulations were based on standard specimens from the laboratory, the results showed good agreement with the documented experimental results. Briefly, at a 40–60% fine aggregate content, the packing density and compressive strength of the concrete reached their peaks and caused a decrease in the height of the slump. The uniformity and curvature coefficients did not influence the slump height. The induced shear band could be tracked during the UCS tests and the crack angles could be measured. At the optimum fine content (40–60%), the shear bands were primarily localized and propagated through the samples having different fine contents.The use of the optimum level of the concrete fine aggregate content ensured its workability and strength.This optimum level of fine aggregate was 40–60%.The discrete element method can be used to evaluate the role of particle size on the performance of concrete.The particle size distribution changed the macro-parameters of the concrete.The maximum packing density was determined to be 40–60% of fine aggregates.The use of the optimum level of the concrete fine aggregate content ensured its workability and strength.This optimum level of fine aggregate was 40–60%.The discrete element method can be used to evaluate the role of particle size on the performance of concrete.The particle size distribution changed the macro-parameters of the concrete.The maximum packing density was determined to be 40–60% of fine aggregates. [ABSTRACT FROM AUTHOR]

To investigate the mechanism of polypropylene fiber (PPF) on the rheological and thixotropic properties of cemented paste backfill containing mineral admixtures, the concept of water film thickness (WFT) was introduced. The packing density of the tailings-binder-PPF (TBP) system was measured in dry and wet conditions and the WFT was calculated accordingly. Additionally, the rheological parameters (yield stress, thixotropy, etc.) of the fiber-reinforced cemented paste backfill (FRCPB) were quantified. The results demonstrate that the wet packing test is a more appropriate method for measuring the packing density of the TBP system. The PPF length has a slight adverse effect on the packing density, and the packing density initially increases and then decreases with the PPF content. The reasons can be attributed to the filling effect and wedge effect of the fibers, respectively. In addition to the packing density, the thixotropy of FRCPB is also affected by the interaction of fibers. WFT is a crucial factor affecting the yield stress of FRCPB, with which it exhibits a strong linear relationship. The study identified that the optimum PPF content for enhancing the rheological and thixotropic properties of CPB is 0.2%, with a fiber length of 9 mm, balancing flowability and stability for practical application in mining backfill operations. These insights can guide the optimization of CPB mixtures, enhancing their flowability and stability during placement in mined-out spaces. By improving the fill quality and reducing the risk of blockage during backfill operations, the results offer practical benefits in increasing the safety and efficiency of underground mining activities. [ABSTRACT FROM AUTHOR]

Powder deposition of even and homogeneous layers is a major aspect of every powder bed fusion process. Powder sieving is commonly performed to powder batches outside of the PBF machine, prior to the part manufacturing stage. In this work, sieving is examined as a method of powder deposition rather than a method to solely filter out agglomerates and oversized particles. Initially, a DEM powder model that has been validated experimentally is implemented, and the sieving process is modelled. The sieving process is optimized in order to maximize mass flow, duration of its linear stage and total mass sieved during linearity. For this, a Taguchi design of experiments with subsequent analysis of variance is deployed, proving that the larger the initial powder loaded in the sieve, the larger the sieve stimulation necessary, both in terms of oscillating frequency and amplitude. The sieve's aperture shape is also evaluated, proving that the more sides the canonical polygon has, the less the mass flow per aperture for the same maximum passing particle size. Then, the quality of the layer produced via controlled sieving is examined via certain layer quality criteria, such as the surface roughness, layer thickness deviation, surface coverage ratio and packing density. The findings prove that controlled sieving can outperform powder deposition via a non-vibrated doctor blade recoater, both in terms of layer surface quality and duration of layer deposition, as proven by surface skewness and kurtosis evaluation. [ABSTRACT FROM AUTHOR]

Hydration of cement materials is accompanied by the formation of calcium silicate hydrates (CSH). Accordingly, the hydration process is completed in the early, middle, and late periods, leading to the formation of two types of CSH phases: of low density (LD) and high density (HD). Usually, under normal conditions, LD CSH is formed in the middle period, while the formation of HD CSH predominates in the later stage. In using the nanoindentation method, it becomes possible to explain the nanogranular nature of the CSH gel, which is characterized by the contact forces of the CSH gel particles for these phases. Studies of cement stone samples at W/C = 0.21 and at the content of hydrothermal SiO2 nanoparticles in the combined additive 0.000006 wt.% and multilayer carbon nanotubes (MCNT) 0.00004 wt.% for cement showed that the effect of nanoparticles on the structure of the CSH gel becomes more pronounced, since the volume fraction of the LD phase of the CSH gel with a low packing density of nanogranules becomes significantly lower than the fraction of the HD phase with increased hexagonal packing density of nanogranules. [ABSTRACT FROM AUTHOR]

In this investigation, four types of sands as alternatives to river sand, namely, crushed sand (CS), marine sand, fine recycled concrete aggregate (FRCA), and fine reclaimed asphalt pavement (FRAP), were studied for their potential for cement-concrete pavement applications. Initially, the physicochemical and morphological characteristics of these sands were understood and later linked to the hydration kinetics and the behavior of cement-mortar systems in both the fresh and hardened states. Due to their evenly graded particle size distribution, CS and FRCA exhibited higher packing densities despite having more gradient angularity, whereas the interlocking capacity of FRAP was found to be affected by the agglomerated particles. Morphology, fineness modulus, and chemical composition of the sands were observed to be the dominating parameters affecting the hydration kinetics and thus the performance of the mortar mixes. Improving these parameters, especially the grain size distribution, could help in enhancing the potential of these sands for pavement applications. [ABSTRACT FROM AUTHOR]

Dump slope is mainly attributed to the deep excavation of a mine. In the present work, the dump in Kunyang phosphate mine located in Sanjia Village was investigated. The geographic and geologic settings were first studied according to the field investigation. Aiming at the actual dump scenario, a rainfall system was designed to simulate the process of dump instability induced by rainfall. The novelty lies in conducting comprehensive tests on fundamental parameters, including water content, particle size, compactness, and engineering mechanical properties, through analogous simulation experiments. In addition, the SLIDE software was adopted to analyse the dumps in each mining area and subsequently determine the sliding disaster mode of the dumps in Kunyang phosphate mine. The comparative analysis of the dumps in these different mining areas showed that the dump in No. 6 mining area has a greater factor of safety (FS) and better stability (instability will not occur). Secondly, the stability of the dumps in No. 2, No. 3 and No. 4 is better than that in No. 5, but they have not reached the ultimate equilibrium state (instability will not occur). Nevertheless, the FS of the dump in No. 1 mining area approached or even fell below 1. Thus, it is predicted that a small‐scale landslide disaster may have occurred (instability). Moreover, the dynamic evolution characteristics of dump disasters with different accumulation densities were revealed by model device tests. Finally, the obvious tube surge phenomenon before sliding was observed. [ABSTRACT FROM AUTHOR]

Purpose: To compare the embolization effects of a non-fibered pushable coil with a conventional fibered pushable coil in an in vitro bench-top experiment. Materials and Methods: A simplified vascular phantom with 4 channels (1 for the non-fibered coil, 1 for the fibered coil, and 2 for continuous circuit flow) was used. A single coil of the longest length was inserted to evaluate the effect of single-coil embolization, and 3 consecutive coils were inserted to assess the effect of multiple-coil embolization. Post-embolization angiography was performed to obtain flow variables (time to peak [TTP], relative peak intensity [rPI], and angiographic flow reduction score [AFRS]) from time density curves. The packing densities of the two coil types were calculated, and the AFRS of each channel was determined by dividing the TTP by the rPI. Results: When inserting a single coil, the conventional fibered coil demonstrated better flow reduction, as indicated by a higher AFRS (25.6 vs. 17.4, P=0.034). However, the non-fibered coil exhibited a significantly higher packing density (12.9 vs. 2.4, P=0.001). Similar trends were observed with multiple coils. Conclusion: The conventional fibered pushable coil showed better flow reduction efficiency, while the non-fibered pushable coil had a higher packing density, likely due to the flexibility of the coil loops. A better understanding of the distinct characteristics of different pushable coils can enhance the outcomes of various vascular embolization. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) is a high-tech concrete whose excellent mechanical and durability characteristics are ascribed to the homogeneity and high packing density of its matrix. However, due to the high contents of cement and silica fume usually necessaries for achieving this packing density, UHPC's final cost and carbon-footprint are far higher than standard concretes. Therefore, over the last few years, the spotlight of UHPC's research has focused sharply on the analysis of locally available supplementary cementitious materials as partial replacement of cement and silica fume. This article presents an investigation to analyze the effect of rice husk ash (RHA) as partial substitution of cement in a previously optimized mixture of recycled-glass-UHPC by means of several statistical tools. Cementitious materials employed in this research involved silica fume, limestone powder, recycled glass powder and ordinary Portland cement (OPC). Based on the results, it can be concluded that RHA addition in the optimized glass UPHC yields to a significant decrease in the workability of concrete and a slight decrease of compressive strength. Results also demonstrated the high interaction between the RHA and water contents, which could be ascribed to the water absorption and internal curing provided by RHA particles. [ABSTRACT FROM AUTHOR]

This study investigates the interplay between particle shape, grading and initial sample density, three of the most important factors influencing the mechanical behaviour of sheared granular assemblies. Using the discrete element method (DEM), two-dimensional assemblies of varying initial sample density, particle aspect ratio, AR , and coefficients of uniformity, C u , were prepared and subjected to drained biaxial shearing until the critical state was reached. We assessed the interplay between each of these parameters by evaluating whether the effect of any given parameter on a mechanical quantity is influenced by any other parameter. Our analyses show that the effect of some of these key parameters on mechanical response, can indeed be influenced by other key parameters. The effect of the particle AR on the peak shear strength for the initially dense assemblies differs when compared with the medium-dense assemblies. The mechanical coordination number of the assemblies at the initial state correlates with the peak strength thereby explaining the interplay between particle AR and initial sample density on the peak shear strength. The linear relationship established between strength and dilatancy for a combination of all assemblies studied suggests that the strength-dilatancy relationship is a unique characteristic of granular assemblies. The dilatancy of the assemblies correlates strongly with the amount of contacts lost during shearing. The interplays found between particle shape, grading and initial sample density in this study show that to develop robust constitutive models for the prediction of granular material behaviour, the effects of multiple factors must be considered. [ABSTRACT FROM AUTHOR]

Crystal structure determines electrochemical energy storage characteristics; this is the underlying logic of material design. To date, hundreds of electrode materials have been developed to pursue superior performance. However, it remains a great challenge to understand the fundamental structure-performance relationship and achieve quantitative crystal structure design for efficient energy storage. In this review, we introduce the concept of crystal packing factor (PF), which can quantify crystal packing density. We then present and classify the typical crystal structures of attractive cathode/anode materials. Comparative PF analyses of different materials, including polymorphs, isomorphs, and others, are performed to clarify the influence of crystal packing density on energy storage performance through electronic and ionic conductivities. Notably, the practical electronic/ionic conductivities of energy storage materials are based on their intrinsic characteristics related to the PF yet are also affected by extrinsic factors. The PF provides a novel avenue for understanding the electrochemical performance of pristine materials and may offer guidance on designing better materials. Additional approaches involve size regulation, doping, carbon additives, and other methods. We also propose extended PF concepts to understand charge storage and transport behavior at different scales. Finally, we provide our insights on the major challenges and prospective solutions in this highly exciting field. [ABSTRACT FROM AUTHOR]

Due to a shortage of river sand for concrete production, manufactured sand (MS) made from crushed rock has gradually become a substitute. It inherently contains some fines content, which has significant effects on the performance of concrete. To study the effects of the MS type and fines content on the workability, cohesiveness, and strength, concrete mixes made with granite MS or limestone MS and different fines contents at various water/binder ratios were tested. Moreover, the packing density, water film thickness (WFT), paste film thickness (PFT), and microstructures of the concrete mixes produced were examined to investigate if their changes were the root causes of the effects of the MS used. It was found that the use of granite MS attained higher workability and strength but lower cohesiveness, which apparently were caused by the higher packing density and larger WFT and PFT. Also, regardless of the MS type, a fines content of about 10% was the optimum for highest packing density and best concurrent workability-cohesiveness-strength performance. Correlation analysis revealed that the MS and fines content exerted their influences on the workability and cohesiveness through the WFT and PFT, and on the strength through the packing density and microstructure. [ABSTRACT FROM AUTHOR]

Over the past few decades, enhancing the sustainability of concrete structures has become a worldwide necessity. This study proposes a mathematical model for predicting compressive strength (CS), aiming to further the objective of designing sustainable concretes incorporating silica-fume as a partial cementing replacement material. The article outlines the formulation, calibration, evaluation and validation of the proposed model. Various factors related to concrete mixture and age were considered in the formulation of the CS model, which employed multiple sub-models including a cement hydration model that considers cement chemical composition and hydration rate, along with other factors like aggregate packing density, capillary porosity, air pores, standard cement strength, paste-to-aggregate bond strength and presence of supplementary cementing materials. An experimental program consisting of 10 different concrete mixtures was designed to calibrate and evaluate the model. The model was then validated using databases from multiple literature sources, which consisted of 50 data points with diverse materials and mixture proportions, to test its accuracy and generalization capability. Results show that the proposed model closely matches the experimental data and has no sign of anomalies or distinct trends. The model's coefficient of determination and standard error are 0.97 and 4.0 MPa, respectively. Moreover, model validation demonstrates high predictability and generalization capability, with a corresponding coefficient of determination and standard error of 0.93 and 4.4 MPa, respectively. Overall, this research suggests that the proposed mathematical model is a reliable tool to predict the CS of sustainable concretes that utilize silica-fume as a partial cementing replacement material. [ABSTRACT FROM AUTHOR]

Fly ash is a fine powdery particle collected from the unit operations of coal combustion furnaces in thermal power plants. Retained fly ash at bottom of hopper has been mixed with water and dumped in lagoons in form of slurry as pond ash (PA) or lagoon ash. Ground Granulated Blast Furnace Slag (GGBS) is a by-product obtained from steel industry. In this study, three phase of concrete specimens were prepared. In first phase, the specimens were prepared using 100% cement with various water-to-cementitious ratios. In second phase, specimens were prepared with varying water-tocementitious ratios and PA contents ranging from 0 to 20%. Finally, the third phase, specimens were prepared to determine the optimal PA content, with GGBS ranging from 0 to 25%. The mechanical and rheological properties of different proportions of PA and GGBS have been experimentally investigated at 28 days. In addition, the flow ability and packing density of different proportions of PA and GGBS various mixes were tested. The test results revealed that combination of PA and GGBS up to 27% would enhance the fresh and harden properties of cementitious material. The rheological behaviour of optimal PA and GGBS concrete were tested at 28 days using scanning electron microscope (SEM). The results confirmed that the addition of PA and GGBS resulting in a denser, less porous, and more compact CSH microstructure in concrete. [ABSTRACT FROM AUTHOR]

The one-to-one contact of coarse aggregate is considered to be the main source for the resistance to permanent deformation and to an extent to fatigue damage. Therefore, it is imperative that the mixture is placed with an interlocked coarse-aggregate skeleton. The conventional mix design approaches generally follow dense graded aggregate gradations, which target for maximum density without accounting the one-to-one contact of coarse aggregates. The current study describes an approach for analysing particle packing in bituminous mixtures based on the compressible packing model (CPM), which provides an analytical expression for the estimation of aggregate packing density. Three mixtures with chosen particle packing indicators and a conventional dense graded mixture are subjected to repeated load haversine compression at temperatures between 25 $^{\circ }$ ∘ and 55 $^{\circ }$ ∘ for a frequency range of 0.01–25 Hz. Selection of binder content is carried out based on equivalent compactability criteria. The link between the packing density of aggregate gradation, dynamic modulus, phase angle, master curve parameters, and relaxation spectrum is evaluated in this study. It is observed that dynamic modulus at high temperature, and low frequency, the phase angle, master curve parameters and the relaxation spectrum exhibit sensitivity to the variation in aggregate gradation. [ABSTRACT FROM AUTHOR]

It is known that optimum packing of coarse and finer fractions in grading of aggregates has proved to improve the mechanical, durability and sustainable properties of concretes. In the present work, composite cement (CC) prepared by interblending of fly ash (FA) and granulated blast furnace slag (GBFS) with ordinary Portland cement (OPC) was used to prepare four grades of CC concretes, viz. M20, M30, M40 and M50, based on guidelines recommended by three international standards, viz. Indian Standard 10262:2019 (IS), American Concrete Institute 211.1-91:2000 (ACI), British Standard 8500-2:2015 (BS) and the reference modified Andreassen model (MAM) through ideal packing curves. The main aim of this study is to establish the influence of ideal gradation of total particulate matrix of concrete constituents on fresh, mechanical and sustainable properties of concretes. In the design of MAM-based concrete mixes, the total particulate matter comprising of coarse aggregates, fine aggregates, cement, FA and GBFS was optimized to match the ideal packing curves of MAM. The particle size distribution curves obtained for total particulate matrix of four grades of concretes designed as per IS, ACI and BS are compared with ideal packing curves of MAM. The concrete mixes designed as per MAM showed better sustainable properties and comparable mechanical properties with respect to concrete mixes designed using other international standards. [ABSTRACT FROM AUTHOR]

Thin HfO2 films atomic layer deposited from hafnium alkyl amide and oxygen plasma were analysed using spectroscopic ellipsometry and X-ray reflectivity. Low refractive index of the material for samples with less than 30 nm thickness marks the index inhomogeneity at the first stage of growth. The transition from rising density to a more stable growth takes place at about 10 to 25 nm film thickness. HfO2 films used for resistive switching experiments demonstrate either clockwise or counterclockwise behaviour depending on the film thickness. The reason for this may be the disruption of the conductive filament at different metal-insulator interfaces, which could be favoured by several mechanisms. [ABSTRACT FROM AUTHOR]

In Szirmai (Ars Math Contemp 16:349–358, 2019) we proved that to each saturated congruent hyperball packing there exists a decomposition of the 3-dimensional hyperbolic space H 3 into truncated tetrahedra. Therefore, in order to get a density upper bound for hyperball packings, it is sufficient to determine the density upper bound of hyperball packings in truncated simplices. In this paper we prove, using the above results and results of the papers Miyamoto (Topology 33(4): 613–629, 1994) and Szirmai (Mat Vesn 70(3): 211–221, 2018), that the density upper bound of the saturated congruent hyperball (hypersphere) packings related to the corresponding truncated tetrahedron cells is realized in regular truncated tetrahedra with density ≈ 0.86338 . Furthermore, we prove that the density of locally optimal congruent hyperball arrangement in a regular truncated tetrahedron is not a monotonically increasing function of the height (radius) of the corresponding optimal hyperball, unlike the ball (sphere) and horoball (horosphere) packings. [ABSTRACT FROM AUTHOR]

The development of advanced soft magnetic devices requires high-performance soft magnetic materials and a high degree of design freedom. Fe-based nanoparticles are attracting attention as high-performance soft magnetic materials. When using nanoparticles as a starting material, achieving high packing density without changing their particle size remains a challenge. Nanoparticle films with high particle density consisting of Fe-Ni soft magnetic nanoparticles were fabricated by direct deposition using the cold-spray technique. The packing density of the particles was estimated to be greater than 78%, which is 20% larger than that of conventional compression-molded products at room temperature. The size of the Fe-Ni nanoparticles in the film was maintained, and no grain growth was observed after cold spraying. The magnetic permeability of the nanoparticle films was higher than that of the compression-molded products because of the larger packing density of the particles. These results indicate that the cold-spray technique is suitable for the fabrication of bulk-like structures using nanoparticle materials. [ABSTRACT FROM AUTHOR]

We provide a tight result for a fundamental problem arising from packing disks into a circular container: The critical density of packing disks in a disk is 0.5. This implies that any set of (not necessarily equal) disks of total area δ ≤ 1 / 2 can always be packed into a disk of area 1; on the other hand, for any ε > 0 there are sets of disks of area 1 / 2 + ε that cannot be packed. The proof uses a careful manual analysis, complemented by a minor automatic part that is based on interval arithmetic. Beyond the basic mathematical importance, our result is also useful as a blackbox lemma for the analysis of recursive packing algorithms. [ABSTRACT FROM AUTHOR]

The ternary blended cement with finer slag and silica fume (SF) could improve the packing density (PD) through the filling effect. The excess water (water more than needed for filling into voids between the cement particles) can be released to improve the fresh properties and densify the microstructure which is beneficial for improving the hardened properties. To verify the hypothesis and reveal how and why (cement + slag + SF) the ternary blends could bring such advantages, the binder pastes incorporating slag and SF with various water-to-binder ratios were produced to determine the PD experimentally. To evaluate the optimum water demand (OWD) for maximum wet density, the influence of the dispersion state of the binder on PD was investigated using the wet packing density approach. The effect of PD of various binary and ternary binder systems on water film thickness (WFT), fluidity, setting time, and compressive strength development of cement paste was also investigated. The results show that the ternary blends could improve the PD and decrease the water film thickness (WFT). The enhanced PD and altered WFT are able to increase fluidity and compressive strength. The ternary blends could improve the compressive strengths by increasing PD and exerting nucleation and pozzolanic effects. [ABSTRACT FROM AUTHOR]

Arrays of buildings with pitched roofs are common in urban and suburban areas of European cities. Large-eddy simulations are performed to predict the boundary-layer flows over flat and pitched-roof cuboids to gain a greater understanding of the impact of pitched roofs on urban boundary layers. The simulation methodology is validated for an array of flat roof cuboids. Further simulations show that changes in the type of grid conformity have a negligible effect on the mean flow field and turbulent stresses, while having a visible, but small, effect on the dispersive stresses for a given packing density. Comparisons are made for flat and 45 ∘ pitched roof cuboid arrays at packing densities of 16.7% and 33.3%. The interactions between pitched-roof buildings and their effect on the urban boundary layer are considerably different to those of flat-roof buildings. The pitched roofs at a packing density of 33.3% leads to significant changes in the mean flow field, the Reynolds stresses, and the aerodynamic drag. Further work investigates the effects of changes in turbulence level and atmospheric thermal stratification in the approaching flow. Importantly, in comparison to a flat-roof array, the pitched-roof one at a packing density of 33.3% evidently increase the friction velocity and greatly reduces the effects of stable stratification conditions and changes in inflow turbulence level. [ABSTRACT FROM AUTHOR]

A wavy circuit is one of the structures used in flexible devices, which endure high stretch ratios during operation. In this study, we focus on the importance of the section tilting angle of the wavy circuit. Both simulation and experiment reveal that the plane wavy circuit is highly affected by the buckling of the circuit, and buckling is influenced by the gap between circuits. On the other hand, the buckling effect tends to decrease when the tilting angle of the circuit section increases. We conclude that increasing the tilting angle of the wavy circuit provides an advantage in designing a flexible device that nullifies the gap-buckling tendency of the wavy circuit, and gives extra margin in the design process. [ABSTRACT FROM AUTHOR]

Aggregate particle size distributions, shape characteristics, proportions and compaction level collectively influence packing density and, in turn, concrete properties. However, the available packing density prediction models either do not account for aggregate shape characteristics or if they do, the calculations are complicated and applicable only for well-graded aggregate systems. Hence, there is a need for the development of a simple and systematic model to predict aggregate packing density. The Aggregate Image Measurement System (AIMS) was used to obtain the shape parameters of aggregates. Aggregate shape indices were developed to correlate binary (gap-graded) aggregates. A new simple and structured RNP (Ramakanta Nabodyuti Prakash) model is presented in this paper for the estimation of packing density of binary coarse aggregate combinations with the use of shape parameters. The model was developed using a discrete element method (DEM) simulation in EDEM and validated using the experimental results. In the final section of the study, the compressive strength of engineered gap-graded concrete was also evaluated to test the applicability of the model. [ABSTRACT FROM AUTHOR]

Large quantities of fresh produce are exported every year to international markets across the world using refrigerated freight containers (RFCs). However, many packaging systems are legacy designs for older shipping technologies. For fruit, more than 10% of the RFC floor area is unused by current packaging systems, and designs often do not facilitate adequate cooling conditions. This study showed that novel packaging designs could improve packing density by up to 19%. Two new packaging systems were investigated using CFD to emulate conditions similar to forced-air cooling (FAC) and a RFC, respectively. The proposed packaging increased floor area utilisation to about 98%. The FAC energy efficiency was improved by 29%. An analysis of the results indicates considerable cooling improvements are possible by modifying vent hole designs and using taller cartons. The study thus demonstrated substantial merits to implementing new fruit packaging systems. • Packaging systems were assessed using a multiparameter evaluation approach. • Design of novel packaging systems that utilise 98% of container floor area. • Cooling efficiency of forced-air cooling improved by 29% with new carton design. • Improved container cooling efficiency feasible by designing taller cartons. • New design is ergonomic, backwards compatible and improves cooling and density. [ABSTRACT FROM AUTHOR]

In the fabric industry, textile yarns are the fundamental building blocks. Hence, visualizing and studying yarn structure is essential to understand the structure and behavior of the fibers. Obtaining the yarn's cross-section images is crucial in the calculations of yarn's porosity; furthermore, a more precise expansion for the fiber's migration can be concluded from the cross-sectional images. In this paper, three different methods (microtome, micro-computed tomography, and epoxy grinding–polishing methods) to image and visualize the yarn's cross-section are presented. The experimental techniques are compared in terms of result useability, time of preparation, and overall outcome of the cross-sectional image. The images can be used for fiber distribution, air gap calculation, and twist analysis as well. The fiber diameter distribution of polyester yarn was measured based on the images obtained by the three different methods; the average fiber diameter measured based on the combined data from the three different methods was found to be 10.90 ± 0.30 µm. [ABSTRACT FROM AUTHOR]

Endovascular coil embolization is one of the primary treatment techniques for cerebral aneurysms. Although it is a well-established and minimally invasive method, it bears the risk of suboptimal coil placement which can lead to incomplete occlusion of the aneurysm possibly causing recurrence. One of the key features of coils is that they have an imprinted natural shape supporting the fixation within the aneurysm. For the spatial discretization, our mathematical coil model is based on the discrete elastic rod model which results in a dimension-reduced 1D system of differential equations. We include bending and twisting responses to account for the coils natural curvature and allow for the placement of several coils having different material parameters. Collisions between coil segments and the aneurysm wall are handled by an efficient contact algorithm that relies on an octree based collision detection. In time, we use a standard symplectic semi-implicit Euler time stepping method. Our model can be easily incorporated into blood flow simulations of embolized aneurysms. In order to differentiate optimal from suboptimal placements, we employ a suitable in silico Raymond–Roy-type occlusion classification and measure the local packing density in the aneurysm at its neck, wall region and core. We investigate the impact of uncertainties in the coil parameters and embolization procedure. To this end, we vary the position and the angle of insertion of the micro-catheter, and approximate the local packing density distributions by evaluating sample statistics. [ABSTRACT FROM AUTHOR]

Polymer dielectric materials in high-frequency communication applications needs to meet strict requirements, and the future development trend is high performance and environmental friendly materials. Herein, we propose a design strategy for simultaneously adjusting multiple performances by building blocks (naphthyl, diphenyl ether, and phenyl). The synthesized copolyester containing phenylene ether structures exhibits good comprehensive properties, including high thermal stability (the temperature at 5 wt% weight loss, 475–495 °C) and inherent flame retardancy (limiting oxygen index 37.8 %∼40.1 %, UL-94 V-0 level), low water absorption (0.16 %∼0.46 %), low dielectric constant (3.04–3.31 @10 GHz) and low dielectric loss (0.0020–0.0028 @10 GHz). The crankshaft naphthyl and bent diphenyl ether structures together change the free volume or spacing of polymer chains, thereby effectively affecting the density or motility of the polarizable groups. These aromatic structures also possess high charring-ability, thus enabling the polymers with the inherent high flame retardancy. Since only carbon, hydrogen, and oxygen elements are introduced into the copolyesters, it supplies a solving approach to eliminate the potential chemical concern arising from introducing heteroatoms such as halogen or phosphorus into polymers. [Display omitted] • Successfully synthesized green copolyesters containing only C, H, O, and free of halogens. • Adjusting the aromatic structural unit customizes the polymer's performance to specific requirements. • The prepared copolyester exhibits good comprehensive performances for high-speed, high-frequency communications. [ABSTRACT FROM AUTHOR]

Self-assembled monolayers (SAMs) technology is considered a potential surface modification technique for addressing challenges in micro/nanostructure fabrication. Bulk metallic glasses (BMGs) are ideal materials for micro/nanostructure moulds. In this study, the surface of Zr-based bulk metallic glasses (Zr-based BMGs) was modified using phosphonic acid SAMs. The findings indicate that phosphonic acid SAMs can effectively reduce the surface free energy of Zr-based BMGs, successfully converting its surface from hydrophilic to hydrophobic and significantly reducing its friction coefficient by up to 90.0 %. Moreover, compared to traditional crystalline Zr-3 alloy, SAMs technology provides significantly better modification effects on amorphous Zr-based BMG surfaces. Experimental results show that among the three different SAMs, the packing density is highest for the mixed hexylphosphonic acid–dodecylphosphonic acid (HPA–DDPA) SAMs, followed by pure dodecylphosphonic acid (DDPA) SAMs, with pure hexylphosphonic acid (HPA) SAMs showing the lowest packing density. The water contact angle for HPA–DDPA SAMs reaches 101.4°, representing a 68.7 % increase compared to the bare plate. Additionally, phosphonic acid SAMs can significantly reduce the friction coefficient of Zr-based BMG surfaces, effectively suppressing oxidative wear and abrasive wear, thereby improving surface wear resistance. The packing density of phosphonic acid SAMs is the primary factor influencing surface wettability and frictional performance, with both wettability and frictional performance increasing monotonically as packing density increases. This is attributed to shear forces and van der Waals forces at the interface. Under specific loads, HPA–DDPA SAMs exhibit excellent lubrication and wear resistance, attributed to the elastic response and compliance of the SAMs. In conclusion, this paper successfully prepares various phosphonic acid SAMs on Zr-based BMGs surfaces and provides a detailed elucidation of the enhancement mechanisms in hydrophobicity and wear resistance through the study of SAMs molecular packing density. • Introduced a novel surface modification technique for amorphous bulk metallic glass materials. • Proved self-assembled monolayers are more suitable for amorphous material surface modification than crystalline. • Zr-based bulk metallic glasses with phosphonic acid monolayers showed improved hydrophobicity and wear resistance. [ABSTRACT FROM AUTHOR]

Silica fume (SF) is widely used in the developing of high-performance geopolymer systems. Previous studies have shown that using different types of SF may have different influences on the performance of geopolymers. What are the key factors (affecting the properties of geopolymers) still need to be clarified? This paper investigated the effects of three types of silica fume (SF1− SF3) with various silica contents (98.0%, 94.7% and 53.1%) and particle sizes (D 50 : 3.3 μm, 3.1 μm and 11.8 μm) on the rheology and compressive strength of alkali-activated calcium alumina cement (CAC)/fly ash mortar. The incorporation of SF can significantly increase the plastic viscosity. The increase in plastic viscosity was due to the ball-bearing action of the spherical SF particles, which reduced the friction between the particles under shearing. Replacing 20% of the fly ash with SF1 and SF2 improved the compressive strength of geopolymer mortars while the incorporation of SF3 decreased the compressive strength at the same replacement ratio. Inductively coupled plasma (ICP) spectrometry results indicated that the amorphous silica in the SFs was dissolved in an alkali solution. Activators with high concentrations of monomer and dimmer silicon groups may promote the reaction between precursors and activators. The formation of additional aluminosilicate gels reduced the amount of large capillary pores (500 nm to 1000 nm), leading to improved strength. The incorporation of coarse SF3 introduced extra voids in the mixture, as suggested by calculations of packing density, leading to reduced strength. • From a chemical perspective, SF effect is governed by Si dissolution rate. • From a physical perspective, SF effect is governed by its PSD. • Low SiO 2 content SF increases strength of geopolymers at low dosage. • CPM can optimize mix composition of SF-geopolymer systems. [ABSTRACT FROM AUTHOR]

Accurate prediction of particle packing density remains challenging. Herein, the particle packing is simulated by discrete element modeling and the packing density results are used to evaluate the 3-parameter particle packing model. When the 3-parameter model is applied to binary and ternary blended mixes, the mean absolute errors in packing density prediction are 0.96% and 1.37%, respectively. Overall, the accuracy of the 3-parameter model is very good when applied to binary blends but not as good when applied to ternary blends, especially when the intermediate size particles are dominant. The discrete element modeling reveals that even when the intermediate size particles are dominant, there are significant particle interactions between the smaller size and larger size particles, which have not been properly accounted for in the existing packing models. Hence, there is still room for improving the existing packing models, requiring further discrete element modeling to study particle interactions. • Potential enhancements for 3-parameter model in multi blends are explored. • Particle packing in binary and ternary blends simulated with discrete element method. • 3-parameter model performs better for binary blends (0.96%) than ternary blends (1.37%). • Intermediate-sized particles foster significant interactions between smaller and larger ones. [ABSTRACT FROM AUTHOR]

• A novel approach using Hyperspectral camera Imaging for remote sensing. • Generation of maps containing useful information of soil parameters such as Packing Density. • Improving Precision Tillage planning methods and their applications. • Decision-making is easier thanks to field soil compaction management strategies. • Data collection is easier thanks to a grid sampling technique. Precision tillage (PT) is an innovative method that aims to take mechanical actions in the soil only where it is needed to curb the impact of heavy machinery usage on the soil. This research explores the use of remote sensing to measure relevant soil parameters to implement a PT strategy. This was achieved by combining traditional soil properties measurements and a non-contact approach based on taking hyperspectral camera (HSC) data in the field. Six methods were generated and divided into two sets to determine soil properties to make PT decisions. The first set includes mathematical functions that were generated from the ground true data (GTD). The second set includes functions that were generated from the remotely sensed HSC data and have a relationship with the methods in the first set. It was possible to tune the functions' parameters to increase the accuracy. In addition, prediction error categories set at 5 % intervals were used to select the best method. The results show that a tuned method based on the GTD has an overall error below 5 %, and a tuned method based on HSC data has an overall error below 10 %. [ABSTRACT FROM AUTHOR]

Worldwide yarn diversity in terms of structure and properties has increased in recent years. Especially composite yarns produced by multiple components have become very preferable in both weaving and knitting sectors. Among these yarns, core and dual core-spun yarn are more prominent in some areas due to their particular performance. In this study, the structure and properties of plain, elastane cored, and elastane + filament cored composite yarns, which were spun by using cotton as sheath fibers, are comparatively investigated. With a constant Ne 16/1 linear density, a carded yarn production line with modified ring-spinning system was used to produce the composite samples using 5.56% elastane ratio for both and 13.79% polybutylene terephthalate (PBT) ratio for dual core. It was observed that the strength of the composite yarns decreased, while the elongation values at the time of breaking tended to increase. There was some deterioration in transition from plain yarn to dual core composite yarn in terms of unevenness and yarn defects, while some improvement was observed in terms of yarn hairiness. In order to dwell on the causes of this situation, the surface and cross-sectional images of the yarns were also studied. [ABSTRACT FROM AUTHOR]

This study investigated the mechanical properties and microstructures of three ultra-high-performance strain-hardening cementitious composites (UHP-SHCCs) with different mix proportions and curing conditions. The binders comprised ordinary Portland cement (OPC), silica fume, and ground granulated blast furnace slag (GGBS); the specimens were cured under air and wet curing conditions for 28 and 91 days, respectively. Compressive and direct tensile tests were performed, along with subsequent microstructural analyses using the particle packing theory and scanning electron microscopy, on the composite matrix and reinforcing polyethylene (PE) fibers. The test results indicate that the inclusion of GGBS, more than 50% (by weight of OPC), leads to a decrease in compressive and tensile strength by up to 35.7% but an increase in ductility by up to 55.9%. In addition, a higher content of GGBS resulted in larger deviations based on the curing conditions. The wet curing condition was more effective for the development of a higher energy absorption capacity than the air curing condition at a curing age of 28 d. By contrast, 91 d of wet curing resulted in the lowest strain energy in this study, mainly because of the considerably reduced strain capacity. [ABSTRACT FROM AUTHOR]

Based on the globular model with the use of the values of porosity and particle size, a method is presented for calculating the structure parameters of porous monofractional powder composite materials for filters. A formula for determining the average (hydraulic) radius of the capillaries of permeable materials has been obtained, which is more accurate than the Kozeny formula. The results of calculating the average radius of capillaries and of the permeability of porous powder materials by the proposed dependences are presented, which are in better agreement with experimental data than calculations by the Kozeny formula. [ABSTRACT FROM AUTHOR]

• A well-dispersed Yb 2 Si 2 O 7 suspension prepared in ethanol produces crack-free and homogeneous green coatings using EPD. • The amount of dispersant controls the number of free ions affecting packing density and crack formation on green coatings. • A sharp current density drop at the beginning of EPD causes loose adhesion ultimately delamination of green coatings. • Hardness measurement of the green coatings is correlated with the EPD coatings packing density. • A schematic model illustrates the importance of green coating properties on the preparation of crack-free sintered coating. This study examines the electrophoretic deposition of Yb 2 Si 2 O 7 particles on SiC substrates to produce Environmental Barrier Coatings. To prepare crack-free and homogeneous green coatings, the effect of the solvent, dispersant concentration, and pH were investigated. Ethanol provided a well-dispersed suspension and crack-free coating which was shown by sedimentation tests and microstructure analysis. The effect of the dispersant concentration was investigated with zeta potential measurement and microstructure analysis with a concentration above 0.5 g/L resulting in higher ionic strength and producing cracked and uneven coatings. The ionic strength was also associated with the powder packing density with larger indentation impressions measured for loosely packed coatings. The deposition rate depended on the suspension properties influenced coating integrity with delamination evidenced by analysing the current density drop during deposition. Sintering of the green coatings having different densities and microstructure showed their importance in the preparation of uniform and dense sintered coatings. [ABSTRACT FROM AUTHOR]

• Investigation of ZnO/water nanofluid effect on the performance of a wet cooling tower. • Improving the thermal performance of the wet cooling tower using ZnO/water nanofluid. • Increasing the thermal performance of the wet cooling tower by enhancing nanofluid concentration. • Employing three PVC packing with different densities. • Enhancing the thermal performance of the wet cooling tower using denser packing. This article deals with an experimental investigation on the thermal performance of a mechanical draft wet cooling tower when using Zinc Oxide (ZnO) nanoparticles and three packing types with different densities. Stable nanofluids with different weight concentrations of ZnO/water were prepared through a two-step procedure using distilled water. First of all, the influence of three packing types including 7,9 and 18 layers are investigated on the thermal performance of the wet cooling tower using ZnO/water nanofluid with a weight concentration of 0.1%. Secondly, five ZnO/water nanofluids with weight concentrations of 0.02, 0.04, 0.06, 0.08, and 0.1% are utilized to examine the effects of nanoparticle concentration on the performance. The results indicate that water temperature difference, cooling efficiency, and tower characteristic could enhance by increasing layers of packing and weight concentrations of nanofluid. Moreover, the nanofluid effects are more notable when the denser packing is used. [ABSTRACT FROM AUTHOR]

Supplementary cementitious materials (SCMs) have become a part of cementitious composites in the manufacturing of cement for improved performance and sustainability. Composite cement is one such type of cement in which ordinary Portland cement (OPC) is partially replaced with fly ash and granulated blast furnace slag (GBFS). In this study, the replacement levels of fly ash and GBFS are optimized to 20% and 30%, respectively, with a 50% OPC content. Apart from the superior properties of these binding materials, a better packing of aggregate comes in handy for improved properties. In this study, the modified Taufer model (MTM) and J. D. Dewar (JDD) model of proportioning the fine aggregates are adopted for improved packing density to obtain better mixes, and a comparison is made with proportions recommended by Indian standard (IS) 383 and IS 650. The packing density obtained in proportioning fine aggregates using the MTM, JDD, IS 650:2008, and IS 383:2016 methods are 0.6814, 0.6737, 0.6238, and 0.6008, respectively. The aggregate sizes recommended based on particle packing models (PPM) particularly, the MTM method tends to improve the packing by reducing the voids content. A direct influence of such effective packing can be observed from the microstructure studies conducted on different samples. MTM samples evidenced better packing compared to other methods of proportioning the mixes. The compound phase changes and development of microstructure were examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), a back scattered electron (BSE), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Also, the quantification of portlandite and calcium carbonate available in the samples was determined using thermogravimetric analysis (TGA) and differential thermal analysis (DTA) for different proportions. At 28 days, the specimens cast using MTM showed 11.11% and 15.5% higher compressive strength than the specimens prepared using IS 650:2008 and IS 383:2016, respectively. At every stage of curing, MTM mixes exhibited superior compressive strength. [ABSTRACT FROM AUTHOR]

In this work, a method combining the spray-drying process and rolling ball method was first selected to mass fabricate Li 2 TiO 3 tritium breeder ceramic pebbles. Herein, we overcome the issues namely complex production, high manufacturing cost, and lower mechanical strength in previous reports. The Li 2 TiO 3 powder with high packing density after the spray drying process will self-agglomerate to form denser structured pebbles during the rolling ball process assisted by sesbania gum binder solution. The stability of slurry, different binder, binder concentrations, the formation mechanism, and the morphology of green pebbles were investigated by using viscometer, SEM. Moreover, the force on the Li 2 TiO 3 green pebbles was also analyzed during the rolling ball process. After the debinding and densification process, the Li 2 TiO 3 pebbles have a uniform diameter of 1.2 mm and good sphericity of 0.97. The Micro-CT instrument showed that the internal structure of the Li 2 TiO 3 pebbles was dense. The experiment's confirmation shows that the Li 2 TiO 3 ceramic pebbles sintered at 1000 °C have optimal mechanical properties such as a crushing load of 108 N and relative density of 92.4%TD, which is much larger than that of the pebbles obtained using traditional methods. This work not only overcomes the core-shell structure but also provides a new platform for better mechanical properties for studying the other materials systems in the future. [ABSTRACT FROM AUTHOR]

Aggregate size distribution is an important parameter in asphalt mixture design and performance. The main objective of this study is to develop a framework to define the aggregate structure of asphalt mixtures when fine and coarse aggregate stockpiles are blended. To develop this framework, an analytical model for binary mixtures is proposed. The model considers the effect of size ratio and air volume between the particles on the aggregate structure and packing density of binary mixtures. Based on this model, three aggregate structures, namely coarse pack (CP), dense pack (DP) and fine pack (FP), are defined. The model is validated using a series of 3D discrete element simulation. Furthermore, the simulation of multi-sized aggregate blends using two representative sizes for fine and coarse stockpiles was carried out to apply the proposed analytical model to actual aggregate blends. In order to assess how well the model applies to asphalt mixtures, compaction parameters including compaction slope (CS), initial density (Nini), locking point and compaction energy index (CEI) were analyzed. The numerical simulations verify the proposed analytical model can satisfactorily determine the particle structure of binary and multi-sized asphalt mixture gradations and can be used to better design asphalt mixtures for improved performance. [ABSTRACT FROM AUTHOR]

This paper aims to establish the relationships between microscopic and macroscopic properties for uniform sphere packings under gravity. The packings are generated by the discrete element method under different conditions with the packing density ranging from about 0.2 to 0.74. The microscopic properties are the structural properties commonly used, including coordination number and various topological and metric properties from the Voronoi-Delaunay tessellation. The results show that these properties can be correlated with packing density. The correlations can be used to estimate different structural properties which are otherwise difficult to obtain in practice. [Display omitted] • A series of packings with density from 0.2 to 0.74 are constructed by DEM. • Various micro properties and standard deviations are quantitatively characterized. • Correlation between micro property and packing density is established. • Quasi-universality in the packings of equal spheres is confirmed. [ABSTRACT FROM AUTHOR]

Packing properties are determined by the dynamic deposition history and affected by many variables. In this work, DEM is used to study the effects of dropping height, deposition intensity and friction coefficient on the dynamic response and stable-state packing properties of ellipsoidal particles. The results demonstrate that with dropping height increasing, packing density increases but the bed becomes less ordered. Dropping height affects the densification process of ellipsoids more significantly than spheres. At high dropping height, the transition period of the orientation angle in the densification process almost disappears for oblate particles, while it becomes longer for prolate particles. With the increase of deposition intensity, packing density decreases significantly, but orientational order changes slightly. With the increase of sliding friction coefficient, packing density and orientational order decrease dramatically. The difference in packing density is mainly caused by dynamic pouring process rather than the densification process. [Display omitted] • Packing density increases with dropping height but structure becomes less ordered. • Dropping height affects densification of ellipsoids more obviously than spheres. • Packing density decreases significantly with deposition intensity. • Sliding friction strongly affects packing density and structures of ellipsoids. • Sliding friction affects the dynamic pouring process more significantly. [ABSTRACT FROM AUTHOR]

[Display omitted] • Theoretical model for band gap variations in semiconducting nanoparticles. • Extension of the bond energy model for cohesive energy. • Incorporated almost all the parameters required for explanation of the band gap. • Band gap of nanoparticles increases when the particle size reduces. • The shape become more asymmetrical at nanoscale of material. We have studied the variation of band gap of low dimensional solids using modified cohesive energy model with their varying shape and size by extending bond energy model for cohesive energy. We have incorporated almost all the parameters required for providing a more thorough relationship between the properties of nanoparticles and the band gap. The band gap of the compound semiconducting nanoparticles, ZnX and CdX (X = S, Se, Te) have been calculated. It has been observed that the band gap of nanoparticles increases when the particle size reduces, and the shape become more asymmetrical. [ABSTRACT FROM AUTHOR]

The topsoil Land Use and Cover Area frame Statistical survey (LUCAS) aims at collecting harmonised data about the state of soil health over the extent of European Union (EU). In the LUCAS 2018 survey, bulk density has been analysed for three depths, i.e., 0–10 cm = 6140 sites; 10–20 cm = 5684 sites and 20–30 cm =139 sites. The laboratory analysis and the assessment of the results conclude that the bulk density at 10–20 cm is 5–10% higher compared to 0–10 cm for all land uses except woodlands (20%). In the 0–20 cm depth, croplands have 1.5 times higher bulk density (mean: 1.26 g cm−3) compared to woodlands (mean: 0.83 g cm−3). The main driver for bulk density variation is the land use which implies that many existing pedotransfer rules have to be developed based on land use. This study applied a methodological framework using an advanced Cubist rule-based regression model to optimize the spatial prediction of bulk density in Europe. We spatialised the circa 6000 LUCAS samples and developed the high-resolution map (100 m) of bulk density for the 0–20 cm depth and the maps at 0–10 and 10–20 cm depth. The modelling results showed a very good prediction (R2: 0.66) of bulk density for the 0–20 cm depth which outperforms previous assessments. The bulk density maps can be used to estimate packing density which is a proxy to estimate soil compaction. Therefore, this work contributes to monitoring soil health and refine estimates on carbon and nutrients stocks in the EU topsoil. [Display omitted] • A Bulk density (BD) assessment based on the ∼6000 samples collected across the EU. • High resolution map (100 m) of bulk density for the 0–20 cm using Cubist regression model. • The main driver for bulk density variation is the land cover type. • Croplands have almost 1.5 times higher bulk density compared to woodlands. • Compared to pedotransfer rules, there is an overestimation of BD in woodlands (∼25%). [ABSTRACT FROM AUTHOR]

In repositories for high-level radioactive waste, bentonite pellet mixtures serve to fill joints between compacted blocks of bentonite and the gaps between these blocks and the concrete lining. Gradation significantly influences the packing density of on-site backfill mixtures. This study specifically examined Gaomiaozi (GMZ) bentonite pellet mixtures, characterized by particle sizes ranging from 0.25 to 10 mm. We systematically categorized these mixtures for packing density testing and modified the linear packing model based on measured values, establishing a model suitable for predicting the packing density of bentonite pellet mixtures. The reliability of the modified linear packing model was evaluated by comparing errors between measured and theoretical values. Using this modified model, we determined the maximum packing density and the corresponding optimal gradation for GMZ bentonite pellet mixtures. The research underscores that the modified linear packing model yields highly accurate predictions, with the error between theoretical and measured packing density staying within 3%. Notably, the maximum packing density recorded for GMZ bentonite pellet mixtures is 0.840. The optimal gradation indicates that pellets with particle sizes of 0.5–0.25 mm should have the largest mass fraction, at 0.45. Additionally, pellets with particle sizes of 10–5 mm have a mass fraction of 0.40, while the mass fractions of pellets with particle sizes of 5–2 mm, 2–1 mm, and 1–0.5 mm are all 0.05. Furthermore, bentonite pellet mixtures featuring the optimal gradation achieve a maximum dry density of 1.88 g/cm³ at a water content of 11.9%, surpassing the maximum dry density achieved by mixtures with Hoffmann and Fuller gradations by 0.02 g/cm³. • Modification of the linear packing model tailored to bentonite pellet mixtures. • Validation of the accuracy of the modified linear packing model using measured packing density values. • Calculation of the maximum packing density and its associated gradation for GMZ bentonite pellet mixtures. • Assessment of the compaction characteristics of bentonite pellet mixtures featuring the optimal gradation. [ABSTRACT FROM AUTHOR]

The packing state of granular material has significant effects on its mechanical properties. It is essential to compare the mechanical properties in the same physical state. Spherocylinders and intersecting spherocylinders are widely used particle shapes both in scientific researches and engineering applications. In this work, we generate the maximally random jammed (jamming onset) packings of spherocylinders and intersecting spherocylinders via the adaptive shrinking cell algorithm. Then we obtain the bulk modulus and measure the structural stability of these packings by the discrete element method. For all the shapes concerned, the bulk modulus first increases and then decreases with the increase of the aspect ratio and is positively correlated with the packing density. We also observe that the structural stability increases as the aspect ratio grows, and the friction improves the bulk modulus and structural stability simultaneously. These results are beneficial for guiding granular material design in engineering applications. [Display omitted] • The mechanical properties of intersecting spherocylinders are studied at the MRJ state. • We investigate the effect of particle shape on bulk modulus and structural stability. • We solidify the particles near the boundary to form a wall which eliminates the wall effect. • We observe that long multi-branched particles have low density but high stability. [ABSTRACT FROM AUTHOR]

Bifurcated granular flow in a 2D channel with two lateral exits is numerically investigated by the discrete element method. Under the fixed inflow rate condition, the outflow rate is equal to the inflow rate in the dilute flow state and rapidly declines when dilute-to-dense flow transition (DDFT) occurs. The flow rate and the transition can be controlled by adjusting the sizes of the two exits. These observations can be explained by the relationship between the flow rate and the packing density in the bottleneck region under the fixed grain condition. Beverloo's formula is valid to describe the dependence of the dense flow rate on the exit size for bifurcated and non-bifurcated granular flows. The packing density in the bottleneck region plays a crucial role on the flow state. In specific, DDFT occurs at 0.6, and the dense flow terminates at 0.79. [Display omitted] • The bifurcated flow state can be controlled by adjusting two lateral exits. • The flow properties in the bottleneck region play crucial role on the flow state. • The dilute-to-dense flow transition happens at the packing density 0.6. • The dense flow state occurs at the packing density 0.79. [ABSTRACT FROM AUTHOR]

Solid-state anaerobic digestion (SS-AD) is a promising process for organic waste treatment. The feeding amount and packing density is an important factor to affect the mass transfer and operating efficiency in SS-AD. This study investigated three different loading amounts of substrates, with the packing densities as 269 g/L, 337 g/L and 422 g/L, which were labelled as Batch 1, Batch 2 and Batch 3, respectively. The agricultural wastes, chicken manure and corn straw, were applied as feeding substrates. Leachate recirculation was employed to enhance the mass transfer. Several operating parameters were tested and the spatial distribution of microbial communities as well as the kinetics of biogas production were analyzed. Batch 2 and Batch 3 both showed good performance, although the higher packing density and leachate recirculation caused blockage in Batch 3. In contrast, Batch 1 with inadequate load worked inefficiently. In Batch 2, the spatial distribution of microorganisms was relatively uniform. Petrimonas and Ruminofilibacter were the dominant bacteria. The genus of Methanosarcina held 81%-94% of the archaea. The recirculation of leachate not only promoted the distribution and degradation of organic matters, but also made the soluble substrates and intermediates aggregate in the lower layer, affecting the distribution of the microorganisms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use of granite polishing waste (GPW) as paste and aggregate replacement is studied. • This can reduce cement consumption, aggregate depletion and waste disposal. • Packing of paste phase, aggregate phase and whole concrete mix is densified. • Strength can be improved despite using less cement to attain better sustainability. • Adding GPW to replace up to 7.5% paste and up to 10% aggregate is highly effective. Previous research demonstrated that the packing density, water film thickness and paste film thickness have great effects on the performance of a concrete mix. On this basis, it is herein proposed a strategy of adding a powder waste as both paste and aggregate replacements to reduce the cement and aggregate consumptions for sustainable development and to improve the packing densities of both the paste phase and aggregate phase for performance improvement. To evaluate such strategy, 25 concrete mixes incorporating granite polishing waste (GPW) as paste and aggregate replacements were tested. The results revealed that the addition of GPW as paste replacement up to 7.5% and as aggregate replacement up to 10% would most effectively increase the packing densities of the paste phase, aggregate phase and whole concrete mix, and thereby increasing the strength of the concrete, despite reduction in cement content. Such increases in packing density would also increase the excess water and excess paste to avoid excessive reductions in the water and paste film thicknesses, which are needed to maintain workability. Last but not least, separate optimization of the paste phase and aggregate phase is an effective way of optimizing the concrete mix design. [ABSTRACT FROM AUTHOR]