Low Aspect Ratio Research Articles

Fast Ewald summation for Stokes flow with arbitrary periodicity

A fast and spectrally accurate Ewald summation method for the evaluation of stokeslet, stresslet and rotlet potentials of three-dimensional Stokes flow is presented. This work extends the previously developed Spectral Ewald method for Stokes flow to periodic boundary conditions in any number (three, two, one, or none) of the spatial directions, in a unified framework. The periodic potential is split into a short-range and a long-range part, where the latter is treated in Fourier space using the fast Fourier transform. A crucial component of the method is the modified kernels used to treat singular integration. We derive new modified kernels, and new improved truncation error estimates for the stokeslet and stresslet. An automated procedure for selecting parameters based on a given error tolerance is designed and tested. Analytical formulas for validation in the doubly and singly periodic cases are presented. We show that the computational time of the method scales like O(Nlog⁡N) for N sources and targets, and investigate how the time depends on the error tolerance and window function, i.e. the function used to smoothly spread irregular point data to a uniform grid. The method is fastest in the fully periodic case, while the run time in the free-space case is around three times as large. Furthermore, the highest efficiency is reached when applying the method to a uniform source distribution in a primary cell with low aspect ratio. The work presented in this paper enables efficient and accurate simulations of three-dimensional Stokes flow with arbitrary periodicity using e.g. boundary integral and potential methods.

Investigation of Overflow-Water-Assisted Femtosecond Laser-Induced Plasma Modulation of Microchannel Morphology

Laser-induced plasma micromachining (LIPMM) process is an effective approach to create microfeatures with high aspect ratio (AR) and reduced heat affected zone (HAZ). Therefore, LIPMM plays a crucial role in improving the morphology of microchannels. In this study, microchannels were fabricated using a femtosecond laser with two distinct sets of process parameters under three different processing methods: overflow-water-assisted laser-induced plasma micromachining (OF-LIPMM), laser direct writing (LDW), and static water laser-induced plasma micromachining (S-LIPMM). Furthermore, single-factor experiments were conducted to systematically analyze the effects of four parameters, namely single-pulse energy, scanning speed, scanning times, and frequency, on the HAZ, AR, and material removal rate (MRR) of the microchannels. Finally, the optimized parameters determined from the single-factor experiments were applied for large-scale grid fabrication on a surface. The experimental results revealed that OF-LIPMM enables the creation of two different kinds of microchannel surfaces: one microchannel was fabricated with a higher AR of 3:1 and a larger HAZ, while another microchannel was created with a lower AR of 1:1 and a reduced HAZ. Moreover, the parameters investigated in the single-factor experiments can be applied to large-scale processing. The results also indicate that variations of the scanning speed, frequency, and single-pulse energy have similar effects on the machining characteristics of the three processing methods. The findings enable the generation of microchannels with favorable morphological characteristics and have significant implications for the large-scale production of both types of microchannels.

Efficiency enhancement of GaAs nanowire array-based solar cell by plasmonic Al nanoparticles

Gallium arsenide (GaAs) nanowire (NW) solar cells (SCs) have piqued the interest of researchers because they exhibit superior light-harvesting and anti-reflection properties along with reduced material consumption compared to their planar counterparts. However, the high surface-to-volume ratio associated with these NWs degrades their performance in practical applications. Light trapping is considered one of the most crucial parameters for producing low-cost high-efficiency NW-SCs. Thus, numerous light-trapping strategies have been explored, among which surface plasmon resonance (SPR) based optical absorption enhancement using metal nanoparticles (NPs) has emerged as a potential method. The role of plasmonic aluminum (Al) NPs in the efficiency enhancement of GaAs NW SC has not yet been explored. Therefore, in this study, a vertically aligned GaAs NW SC structure incorporated with Al NPs has been investigated using the finite-difference time-domain (FDTD) method. The sidewalls of GaAs NWs are embellished with uniformly arranged Al NPs with diameters ranging from 30 to 60 nm. The excitation of localized surface plasmon resonance in metal NPs results in significant light absorption enhancement at the GaAs near-band of the proposed structure. The results demonstrate that even with a low aspect ratio (D/P) of 0.3, optimizing the geometrical parameters of the NPs results in a 41.96 % increase in power conversion efficiency (PCE) and a 45 % increase in absorption efficiency at 800 nm for the proposed structure when compared to the bare structure. Hence, our suggested structure which utilizes the light-trapping mechanism of Al NPs proves to be a cost-effective and promising material combination for high-efficiency nanoscale SCs.

Effects of anisotropy and off‐axis angle on buckling behavior of carbon/epoxy Z‐pin under axial pressure

AbstractThe axial buckling load of single carbon fiber or composite strands is typically predicted using Euler's formula, developed for isotropic materials. This study introduces anisotropy in a mechanical carbon/epoxy Z‐pin model under axial pressure. It examines the influence of compressive modulus, shear modulus, off‐axis angle, and aspect ratio on its buckling behavior. Results show that the axial instability performance of the Z‐pin decreases with lower compression, shear modulus, and aspect ratio while keeping the tensile modulus fixed. Anisotropy decreases buckling load by up to 14% compared with Euler's formula, which only considers tensile modulus. Additionally, the impact of the deflection Angle between the pressure and pin‐axis can be ignored when it is less than 3°.Highlights Euler formula overestimates composite Z‐pin buckling force under axial pressure. Anisotropy decreases buckling load by up to 14% for carbon/epoxy. Shear modulus is more influential on Z‐pin with a small aspect ratio. For off‐axial compression angles <3°, influence can be ignored.

Annular vertical cylindrical thermochemical storage system with innovative flow arrangements for improved heat dispatch towards space heating requirements

Thermochemical energy storage is a potential solution for low-temperature seasonal energy storage systems and for improving renewable solar thermal energy share in the global energy mix. Such systems can help in meeting the heating requirements in the Indian Himalayan region in an environment-friendly manner. A few studies have attempted to understand the performance of strontium bromide hexahydrate-monohydrate-based storage as a thermochemical energy storage medium. The present study evaluates the performance of the vertical cylindrical annular reactor configuration, considering innovative radial airflow configurations. A two-dimensional axisymmetric model has been developed to study the effect of the various geometrical and operating parameters. During the charging (dehydration) process, the outward flow configuration exhibits substantially higher exergy efficiency as against the inward flow counterpart, with the difference being more pronounced (∼6–8%) at lower aspect ratios (0.5–1.0). The flow work requirement is higher for the outward flow during the hydration (discharging process), resulting in better performance for the inward flow counterpart. Upon increasing the volumetric air flow rate, the pressure drop across the reactive bed is found to increase substantially, leading to lower exergy efficiencies for higher flow rates. During the hydration process, the exergy efficiency for the inward flow becomes almost constant (∼15%) for a relative humidity level exceeding 60%, whereas that for the outward flow gradually increases to reach ∼ 5% for an 80% relative humidity. The ratio of thermal energy stored to the flow work required is higher for the outward flow. The energy output to flow work ratio is about 35% higher for the inward flow for the aspect ratio of 4.

A shortened process of tri-modal microstructure developing in Ti-6Al-4V alloy via electropulsing-induces grain spheroidization

A shortened process combining electropulsing treatment (EPT) and conventional heat treatment (HT) has been applied to develop a tri-modal microstructure in Ti-6Al-4V alloy. The tri-modal microstructure produced by this process has good overall mechanical properties (tensile strength ∼1110 MPa, elongation ∼22.7%). The rapid development of the tri-modal microstructure is attributed to the EPT production of low aspect ratio (LAR) V-poor martensite, which results from the EPT limiting the growth of high-temperature β grains and the diffusion of elements. The α grains decomposed from LAR martensite during the HT process retain a low aspect ratio morphology which can be easily spheroidized. LAR α grains do not undergo phase transformation at two-phase temperature (950 °C) but follow the cylinderization mechanism of spheroidization that relies more on the geometry of the grains than on the high density of dislocation substructures. In this study, the effects of the three types of grains on material strength and ductility are analyzed in detail.

Fluid flow and mixing in a novel intermittently rotating bioreactor for CAR-T cell therapy manufacturing

This work explores the mixing and fluid dynamics in a novel bioreactor currently used for the automated manufacturing of CAR-T cell therapy, which offers a single-dose cure for several forms of advanced blood cancer. The cylindrical bioreactor has a low aspect ratio and a free surface. Agitation is achieved by intermittent rotation of the entire vessel around its central axis. No engineering characterisation has been conducted to date for this system in a bioprocessing context. The study examines the fluid dynamics problems of spin-up from rest and spin-down to rest. Novel Particle Image Velocimetry and Planar Laser-Induced Fluorescence data is presented alongside reflective flakes results, shedding light on the different transient flow regions inside the intermittently rotating bioreactor, and determining the timescales of macro- and micromixing. The results presented can be used to design a custom rotation pattern of the bioreactor for improved mixing performance during the cell expansion step.

Conceputal Sizing and Multicriteria Optimization of UAV for Snow Studies

This paper describes a methodology for conceptual design and sizing of a UAV to be used for snow cover evaluation and other scientific studies in lower Himalayas. The problem is posed in a multi-criteria optimization framework with wing span (representing size) and stall speed (representing performance) as the two conflicting objective functions. Eleven design variables are considered, which relate to the geometry and mass. In addition, an engine selection parameter is also used. Inequality and equality constraints are imposed on the design. The design is optimized with genetic algorithm independently for takeoff mass and stall speed. Multi-objective optimization is carried out for the stall speed and wing span as objective functions. For most cases, the optimum configuration has the lowest wing aspect ratio, highest wing t/c ratio, smallest aircraft length and highest flap area fraction. Low aspect ratio and high t/c for the wing result in lower wing weight.

Investigation of the porosity of L/LL4 ordinary chondrite Bjurböle using synchrotron radiation microtomography and scanning electron microscopy: Implications for parent body evolution

Porosity is an essential property of chondritic meteorites and is closely related to the genesis, thermal evolution, metamorphism, and thermal properties of the meteorite parent bodies. We study porosity, its texture, and shapes at sub-micron resolution in 3D and 2D within a 0.35 cm3 sample of the L/LL4 ordinary chondrite (OC) Bjurböle using two techniques, synchrotron radiation microtomography (SRμCT) and scanning electron microscopy (SEM). We employ automated segmentation tools that can be applied to both SRμCT and SEM data. Successful segmentation results can be achieved by combining visual qualitative examination and machine learning algorithms.We report novel measurement results of three-dimensional porosity properties of Bjurböle, such as aspect ratio and connectivity of void spaces, and compare the results of 2D and 3D porosity analysis. The Bjurböle sample in this study is a complex, highly porous, and friable medium and the dominant type of porosity is intergranular, continuous porosity, which contains almost all porosity volume. The shapes of the void volumes have an important effect on the connectivity of the porosity and thermal transport properties. Positive correlations between void diameter and aspect ratio as well as void volume and connectivity are present in Bjurböle, which indicate that smaller voids have lower aspect ratios and lower connectivity. In Bjurböle, small, near-spherical voids with few connections have the highest relative frequency, whereas larger void spaces with higher aspect ratios and connectivity are significantly fewer. Completely isolated pores, i.e., voids surrounded by solid material, also have a high relative frequency, and they exist within the chondrules and the matrix. However, the volume percentage of these pores is negligible compared to that of the continuous porosity.Our results support the previously measured high porosities of Bjurböle. The volume percentage of intergranular void spaces, in particular in the matrix, and the measured high porosities are not in line with the results of thermal evolution and sintering models of chondritic parent bodies regarding petrologic type 4, which implies that Bjurböle originates from a parent body with an initial onion shell structure that fragmented during or after its metamorphic peak and quickly reaccreted into a rubble pile.

Performance Improvement of A Low Aspect Ratio Axial Flow Compressor Rotor by Means of Turbulence Generator

The present paper reports results of an experimental investigation aimed at improving the performance and operating range of an axial flow compressor using a simple passive means. A total of four configurations are tested, namely, (i) basic rotor configuration without any passive means, (ii) rotor with modified partial shroud (MPS), (iii) rotor with MPS and turbulence generator, TG, placed on the casing at the leading edge of the rotor blade and (iv) rotor with MPS and turbulence generator, TG1, placed on the casing at 44 mm upstream of the leading edge of the rotor blade. The turbulence generators are made of velcro tape. The rotor performance is determined by measuring static pressure on the casing, upstream and downstream of the rotor blade. In addition, five hole probe traverses are made at the rotor exit at five flow coefficients (at, above and below design flow coefficients). From the casing static pressure measurements, stall flow coefficient of rotor (with MPS + TG1) is found to be decreased. From the five hole probe measurements, rotor (with MPS + TG1) is found to have improved total and static pressure coefficients compared to rotor (with MPS). Slightly reduced performance of this rotor compared to the basic configuration is attributed to the adverse effects of MPS. The improved performance of the rotor (with MPS + TG1) is attributed to the energization of the casing wall boundary layer at the rotor inlet, due to vortexes generated by TG1.

Non-planar bioprinting with molding assistance for irregular wound shape

Most human organs and tissues have different shapes, which vary per individual. When printing biomedical scaffolds using material extrusion-based additive manufacturing bioprinters, sacrificial layers are generally used to support the suspended parts of the scaffold. However, the in-process generation of sacrificial layers is time-consuming and the scaffold can be damaged when removing the sacrificial layers. In this study, a novel non-planar grid slicing (NPGS) process was proposed for printing irregularly shaped tissues with low aspect ratios (for example, skin wounds), where the required 3D shape is formed following the deposition of non-planar paths, layer-by-layer. By stacking layers of bioink onto a non-planar support base, the NPGS process considerably reduced the total length of the deposition paths and number of fragmented paths. Therefore, it can reduce the use of costly bioink and improve the success rate of the scaffold printing. The proposed NPGS process and traditional planar slicing (TPS) process were used to fabricate scaffolds that conform to the shape and depth of two clinical wounds. Compared to TPS, NPGS reduced the total length of the deposition paths and number of fragmented paths (paths shorter than 5 mm) by 49.2% and 59.6%, respectively. In animal testing, a large irregular wound was created on the rat's dorsal skin and treated with tri-cell-laden hydrogel printed by the NPGS process, demonstrating full repair after 28 days. The NPGS process shows great potential for customized biofabrication in tissue engineering.

Highly Efficient Anchor-Free Oriented Small Object Detection for Remote Sensing Images via Periodic Pseudo-Domain

With the continuous progress of remote sensing image object detection tasks in recent years, researchers in this field have gradually shifted the focus of their research from horizontal object detection to the study of object detection in arbitrary directions. It is worth noting that some properties are different from horizontal object detection during oriented object detection that researchers have yet to notice much. This article presents the design of a straightforward and efficient arbitrary-oriented detection system, leveraging the inherent properties of the orientation task, including the rotation angle and box aspect ratio. In the detection of low aspect ratio objects, the angle is of little importance to the orientation bounding box, and it is even difficult to define the angle information in extreme categories. Conversely, in the detection of objects with high aspect ratios, the angle information plays a crucial role and can have a decisive impact on the quality of the detection results. By exploiting the aspect ratio of different targets, this letter proposes a ratio-balanced angle loss that allows the model to make a better trade-off between low-aspect ratio objects and high-aspect ratio objects. The rotation angle of each oriented object, which we naturally embed into a two-dimensional Euclidean space for regression, thus avoids an overly redundant design and preserving the topological properties of the circular space. The performance of the UCAS-AOD, HRSC2016, and DLR-3K datasets show that the proposed model in this paper achieves a leading level in terms of both accuracy and speed.

Role of crack offset and loading condition on fracture behavior of wire specimen

Accurate stress intensity factor (SIF) solutions for cylindrical specimens with varied wire aspect ratios, crack aspect ratio, relative crack depth and crack offset are required to evaluate the fracture toughness of high strength yet brittle rods, cables, fibres and wire specimens. The mode I geometric factor (GF) solutions of various crack configurations in a cylindrical fracture specimen in tension have been determined using linear elastic fracture mechanics in earlier studies. In the present study, finite element analysis (FEA) was used to compute these as a function crack offset and wire aspect ratios for two different boundary conditions-constrained and unconstrained. In constrained loading condition, the GF was seen to decrease significantly with crack offset for wires at lower aspect ratio in all the 3 crack curvatures – concave, straight and convex. GF stabilized as the wire aspect ratio was increased beyond 40. In unconstrained loading the GF values were independent of the wire aspect ratio and crack offset for the 3 crack curvatures.

Morphology evolution of electrodeposited lithium on metal substrates

Lithium (Li) metal is deemed to be the high-energy-density anode material for next generation batteries, but its practical application is impeded by the uneven electrodeposition during charge of battery, which leads to the low Coulombic efficiency and potential safety issue. Here, multiscale modeling is fabricated to understand the morphology evolution of Li during electrodeposition process, from the self-diffusion of Li adatoms on electrode surface, to the nucleation process, and to the formation of Li microstructures, revealing the correlation between final morphology and deposition substrates. Energy batteries and self-diffusion of Li adatom on various substrates (lithium, copper, nickel, magnesium, and silver) result in the different nucleation size, which is calculated by kinetic Monte Carlo simulation based on classical nucleation theory. Formation of Li substructures that are grown from Li nuclei, is revealed by phase field modeling coupled with cellular automaton method. Our results show that larger Li nuclei is obtained under faster self-diffusion of Li adatom, leading to the low aspect ratio of Li substructures and the subsequent morphology evolution of electrodeposited Li. Furthermore, the electrodeposition of Li is strongly regulated by the selection of substrates, giving the practical guideline of anode design in rechargeable Li metal batteries. It is worthy to mention that this method to investigate the electro-crystallization process involving nucleation and growth can be transplanted to the other metallic anode, such as sodium, potassium, zinc, magnesium, calcium and the like.

Melt Diffusion-Moderated Crystal Growth and its Effect on Euhedral Crystal Shapes

Abstract Crystal growth is often described as either interface-controlled or diffusion-controlled. Here, we study crystal growth in an intermediate scenario where reaction rates at the crystal-melt interface are similar to the rates of diffusive transport of ions through the melt to the advancing crystal surface. To this end, we experimentally investigated euhedral plagioclase crystal shapes in dry mafic (basaltic) and hydrous silicic (haplodacitic) melts. Aspect ratios and inferred relative growth rates of the 3D short (S) and intermediate (I) crystal dimensions vary significantly between mafic and silicic melts, with δS:δI = 1:6–1:20 in basalt and 1:2.5–1:8 in hydrous haplodacite. The lower aspect ratios of plagioclase grown in the silicic melt coincide with 10 to 100× lower melt diffusion rates than in the mafic melt. Using an anisotropic growth model, we show that such differences in melt diffusivity can explain the discrepancy in plagioclase aspect ratios: if interface reaction and melt diffusion rates are of similar magnitude, then the growth of a crystal facet with high interfacial reaction rates may be limited by melt diffusion, while another facet of the same crystal with lower interfacial reaction rates may grow uninhibited by melt diffusivity. This selective control of melt diffusion on crystal growth rates results in progressively more equant crystal shapes as diffusivity decreases, consistent with our experimental observations. Importantly, crystals formed in this diffusion-moderated, intermediate growth regime may not show any classical diffusion-controlled growth features. The proposed model was developed for plagioclase microlites but should be generalisable to all anisotropic microlite growth in volcanic rocks.

Evaluating cooling and thermal performances of a double pipe rectangular Earth-to-Air Heat Exchanger provided with a convection zone

Earth-to-Air Heat Exchanger performances depend on many parameters, among them the pipe geometric shape which is also found be influential. On account of their large exchange surface, rectangular buried pipes are more performing compared to the circular ones. In this study, an innovative technique of improving heat transfer consisting in incorporating a convection zone within these systems is proposed. In view of its high thermal performance and harmless nature compared to organic liquids, water is used for filling the convection zone within a double pipe rectangular underground exchanger operating in cooling mode and submitted to the summery climatic conditions of the Algerian Saharan region. Moreover, a thorough investigation is conducted for assessing the response of the double pipe rectangular exchanger to the variation of its sizing and operating parameters in the presence of such a layer. The findings reveal that the presence of a convection zone makes the double pipe rectangular exchanger more performing in terms of the air temperature reduction and cooling energy production, even in the case where the basic system usually is ineffective due to using a larger pipe section, a smaller length, or higher air flow. For instance, the outlet temperature supplied by the exchanger with a convection zone at a pipe section of 1256 cm2 is found to dwindle by 2 °C compared to the basic system. Likewise, the average efficiency at a pipe length of 20 m rises to 83 % for the former, while drops to 72 % for the latter. It is also shown that at high air flow of 1780.4 m3/h, the cooling energy yielded by the improved exchanger rises to more than twice of that obtained with the unimproved one. Further, the integration of a convection zone is a cheaper and useful way for more enhancing the performance of commercial rectangular PVC pipes on account of their low aspect ratio. Thus, it follows that the novel technique of using rectangular buried pipes integrated with convection zones can to be considered as a powerful improving way that could be eventually combined with other techniques for further maximizing the profitability of these systems.

System efficiency of packed bed TES with radial flow vs. axial flow – Influence of aspect ratio

This paper compares the net system efficiency, including thermal efficiency and pressure drop effects, of radial versus axial flow packed beds for thermal energy storage. The traditional packed bed system is a cylindrical geometry where fluid flows axially from one end to another. However, issues of thermal stratification and high-pressure drop have led to recent studies on radial flow systems. One potential benefit is the reduced pressure drop in a radial flow system. This paper compares the performance of radial flow and axial flow systems at a range of aspect ratios (AR = H/Dbed) from 0.21 to 1.92 using a numerical model where the storage volume is held constant in all cases. When the radial flow bed is at a low aspect ratio (short/wide), the thermal front is improved but the pressure drop is high. At a high aspect ratio, the velocity is reduced in radial flow, leading to decreased pressure drop but an increased spreads in the thermal front that lowers thermal efficiency. The opposite trends are noted in axial flow. Thermal efficiencies of 83–91 % were noted for radial flow, while they ranged from 85 to 94 % in axial flow. Net efficiencies including pressure drop ranged from 74 to 82 % for radial flow and 80–87 % for axial flow. In both systems, a peak net efficiency was noted between the highest and lowest aspect ratio. While some aspect ratios with radial flow outperform axial flow from a net efficiency perspective, the results show that the highest net efficiency from axial flow is higher than that from radial flow. Overall, this paper highlights the importance of innovative TES designs and their potential to improve energy efficiency.

Heat transfer measurements in an inclined low aspect ratio Rayleigh–Bénard convection cell under feedback control

We report experimental results on the inclined Rayleigh–Bénard convection of a moderate aspect ratio convection cell using a high Prandtl aqueous solution of glycerol. The main goal of the present work is to measure continuously the transition from a convective condition into a purely conduction regime by a smooth quasi-static variation of the tilt angle of the convection cell with respect to the gravity vector in 180° at Rayleigh numbers just above of convection onset. Flow circulation inside the convection cell is indirectly detected by temperature sensors located at the bounding active plates. Changes in the temporal evolution of the heat transfer curve appear directly related to flow transitions between characteristic flow patterns from transversal rolls evolving into an unicellular single roll convective pattern and then a conductive state. For small tilt angles 6°≤γ≤20° time signal fluctuations on both the Nusselt number and temperature readings were observed. Flow visualizations and PIV measurements provided a complementary view of the convective flow pattern being associated to transitions in the Nusselt number evolution with the tilt angle of the cell. For small tilt angle transitions, we observed a loss of rolls process followed by a reorganization of the flow which might be the responsible of the Nusselt unsteadiness.

ZIF-8 nanoplate/6FDA-DAM membrane for hydrogen extraction from propane dehydrogenation process

High-aspect ratio materials can enhance gas separation performance compared to low-aspect ratio materials when incorporated into a polymer matrix to form mixed matrix membranes (MMMs). However, the filler shape effect on various properties of MMMs was not thoroughly discussed. Herein, we fabricated a mixed matrix membrane with two different shapes of metal-organic framework (MOF) and examined the MOF filler shape effect on mechanical, thermal, and gas separation properties. Zeolitic imidazolate framework-8 nanoplates (NZIF-8) were synthesized by conversion method with an aspect ratio of 20. Isotropic ZIF-8 particles (IZIF-8) were also synthesized, and both fillers were hybridized with a 6FDA-DAM (PI) polymer. 20 wt% NZIF-8/PI membrane exhibited high mechanical properties of 0.282 GPa for hardness and 3.5 GPa for modulus, which is higher than that of IZIF-8/PI membranes. The membrane was stable in high temperatures which is comparable to the pristine PI membrane, showing long-term thermal stability at 300 °C. Furthermore, high aspect ratio fillers allowed significant enhancement in hydrogen separation performance, showing hydrogen permeability of around 1800 Barrer with hydrogen/propane selectivity of 260 at 20 wt% ZIF-8 nanoplate loading, which is much enhanced than the membrane with isotropic ZIF-8 particles. The separation performances were consistent in ternary mixture separation under different conditions. These highly stable and selective properties can be promising for hydrogen extraction from the propane dehydrogenation process.

Dense Disordered Jammed Packings of Hard Spherocylinders with a Low Aspect Ratio: A Characterization of Their Structure.

This work numerically investigates dense disordered (maximally random) jammed packings of hard spherocylinders of cylinder length L and diameter D by focusing on L/D ∈ [0,2]. It is within this interval that one expects that the packing fraction of these dense disordered jammed packings ϕMRJhsc attains a maximum. This work confirms the form of the graph ϕMRJhsc versus L/D: here, comparably to certain previous investigations, it is found that the maximal ϕMRJhsc = 0.721 ± 0.001 occurs at L/D = 0.45 ± 0.05. Furthermore, this work meticulously characterizes the structure of these dense disordered jammed packings via the special pair-correlation function of the interparticle distance scaled by the contact distance and the ensuing analysis of the statistics of the hard spherocylinders in contact: here, distinctly from all previous investigations, it is found that the dense disordered jammed packings of hard spherocylinders with 0.45 ≲ L/D ≤ 2 are isostatic.