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Spark plasma sintering (SPS) is an ultrafast sintering method for the preparation of ceramics and ceramic composites with simple geometrical shapes, with the combined application of uniaxial pressure. This study aims to propose an SPS densification method for Si3N4 ceramic balls without necessitating alterations to tools and equipment. The Si3N4 ceramic balls intended for sintering are positioned within a SiC powder bed inside the conventional die used in SPS. The study systematically investigates the effects of presintering temperature (1400°C, 1500°C, and 1600°C) and SPS temperature (1600°C, 1700°C, and 1800°C) on the sphericity, relative density, phase composition, microstructure, and mechanical properties of Si3N4 ceramic balls. Experimental findings reveal that Si3N4 ceramic balls exhibiting an optimal combination of sphericity (0.94 ± 0.02), relative density (98.4%), and mechanical properties (Vickers hardness: 17.5 ± 0.4 GPa, fracture toughness: 6.4 ± 0.1 MPa·m1/2) were successfully achieved at a pre‐sintering temperature and SPS temperature of 1600°C, coupled with the use of a SiC powder bed and SPS method. Consequently, the SPS method demonstrates its capability to fabricate Si3N4 ceramic balls with excellent performance. [ABSTRACT FROM AUTHOR]

Coordinate measuring machines (CMMs) are utilized to acquire coordinate data from manufactured surfaces for inspection reasons. These data are employed to gauge the geometric form errors associated with the surface. An optimization procedure of fitting a substitute surface to the measured points is applied to assess the form error. Since the traditional least-squares approach is susceptible to overestimation, it leads to unreasonable rejections. This paper implements a modified differential evolution (DE) algorithm to estimate the minimum zone femoral head sphericity. In this algorithm, opposition-based learning is considered for population initialization, and an adaptive scheme is enacted for scaling factor and crossover probability. The coefficients of the correlation factor and the uncertainty propagation are also measured so that the result's uncertainty can be determined. Undoubtedly, the credibility and plausibility of inspection outcomes are strengthened by evaluating measurement uncertainty. Several data sets are used to corroborate the outcome of the DE algorithm. CMM validation shows that the modified DE algorithm can measure sphericity with high precision and consistency. This algorithm allows for an adequate initial solution and adaptability to address a wide range of industrial problems. It ensures a proper balance between exploitation and exploration capabilities. Thus, the suggested methodology, based on the computational results, is feasible for the online deployment of the sphericity evaluation. The adopted DE strategy is simple to use, has few controlling variables, and is computationally less expensive. It guarantees a robust solution and can be used to compute different form errors. [ABSTRACT FROM AUTHOR]

Determining the shape parameters of sand particles helps to understand the geotechnical properties of sand. This study aims to determine the roundness and sphericity of Jumunjin sand utilizing artificial intelligence (AI). A dataset comprising 1000 sand particle images from Jumunjin sand was used for testing. The training set included approximately 28,000 images, created through a combination of synthetic data (5000 images) and additional data augmentation techniques to address data imbalance issues. Unlike traditional methods for determining roundness and sphericity, this research proposes a model that combines a regression model with a convolutional neural network (CNN), using ResNet and DenseNet as the backbone networks. The results, evaluated based on the coefficient of determination (R2) between the predicted values using the DenseNet169 model and the true values, yielded an R2 of 0.695 for roundness and 0.979 for sphericity. When classifying based on the Krumbein and Sloss chart using the trained model, the DenseNet169 model demonstrated the highest accuracy (73.6%), precision (77.9%), and recall (77.2%). A comparison between AI predictions and human evaluations revealed considerable variation in human classification, depending on the observers, whereas the AI model consistently exhibited robust performance in determining both roundness and sphericity. [ABSTRACT FROM AUTHOR]

Purpose: Investigating the performance of the new Dophi™ M150E Microwave Ablation System, in terms of temperature distribution, ablation size and shape, reproducibility. Materials and Methods: The Dophi™ M150E Microwave Ablation System was tested on ex vivo liver, lung and kidney, at 6 different settings of time, power and number of MW antennas (single antenna: 50 and 100 W at 5 and 10 min; double antenna: 75 W at 5 and 10 min). The temperature distribution was recorded by Fiber Bragg Grating sensors, placed at different distances from the antennas. The ablation axes were measured and the sphericity index was calculated. Results: The standard deviation of ablation axes was < 5 mm, except at the highest energy and time setting for the lung. A maximum temperature rise of ~ 80 °C was measured. The measured ablation axes are overall comparable with the manufacture's values, especially at lower power and with one MW antenna (average maximum difference is 7 mm). The mean sphericity index of 0.95, 0.79 and 0.9 was obtained for the liver, lung and kidney, respectively, with a single antenna. With double antenna setup, the sphericity index was closer to 1 when 75 W for 10 min were used. Conclusions: Dophi™ M150E allows good reproducibility of ablation axes for all cases except in the lung at the highest energy level. With one antenna, an almost spherical ablation area for the liver and kidney was obtained. Using double antenna results in more homogeneous temperature distribution within the tissue compared to single antenna. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study examines the effects of process parameters on the physical and chemical properties of capsules obtained by encapsulating pomegranate juice concentrate using the alginate beads. Alginate concentration, CaCl2 concentration, dripping speed, and dripping height were selected as independent variables, while shape factor, sphericity, and total phenolic content of the capsules were the dependent variables. The optimum process conditions were determined as alginate concentration 1.6%, CaCl2 3%, drip rate 0.77 and drip height 10 cm. Results indicated that the physical and chemical properties of the microcapsules were influenced by different process conditions. Results indicated that the physical and chemical properties of the microcapsules were influenced by different process conditions. Increased dripping rate and height improved capsule sphericity, while higher alginate concentrations negatively affected droplet sphericity. Additionally, decreased alginate concentrat ion and dripping height positively influenced the total phenolic content of the capsules. [ABSTRACT FROM AUTHOR]

In recent years, postharvest loss has been a serious concern. However, knowledge of the mechanical properties is vital to developing any postharvest technology for rice production better. The objective of this research is to conduct a comparative analysis of the mechanical properties of selected paddy rice at different variety-moisture content interactions. The mechanical properties of AGRA rice, CRI-Amankwatia, CRI-Enapa, and CRI-Dartey, four local varieties developed in Ghana, are compared at 11.5%, 13.0% and 16.5% on wet basis moisture content. Tukey's Honest Significant Difference (HSD) comparisons test was conducted during data analysis to compare all possible pairwise combinations of the various varieties and moisture content interaction. From the results, it was concluded that CRI-Dartey, at 16.5%, recorded the highest Sphericity and Aspect Ratio of 0.391 mm3 and 0.298 mm3, respectively. For grain mass, AGRA rice at 13.0% also recorded 0.0312 g as the highest score. The GM1000, Angle of Repose and Bulk density CRI-Amankwatia at 16.5 % moisture content recorded the highest score of 29.33 g, 47.3o, and 654.0 kg/m3, respectively. AGRA rice at 13.0% observed the highest value of 1685.8 for kg/m3 true density, and the highest value for porosity was 70.83%, which was recorded by CRI-Enapa at 11.5 % moisture content. In all cases, the difference in mean value was less than the Least Square Difference. This indicates that there were no significant statistical differences between their mean values, indicating that technologies developed and adapted for one variety can equally be used for all the other varieties.

The measure of sphericity for positive semi-definite matrices plays a crucial role in understanding their geometric properties, especially in high-dimensional settings. This paper introduces a robust measure of sphericity, which remains invariant under orthogonal transformations and scaling. We explore its behavior in finite-dimensional cases. Additionally, we investigate the stochastic case by considering a normal distribution, analyzing the asymptotic normality of random matrices and its implications on the convergence properties of the proposed measure. [ABSTRACT FROM AUTHOR]

The adhesion of dust particles on the surface of the dust collector tends to cause great resistance to the dust collector and affects the operating efficiency. In order to visualize particles in the filtration process and to grasp the mechanism of particle viscosity and sphericity on filtration performance, a numerical simulation study was conducted to investigate the deposition behavior of particles during filtration, employing FLUENT-EDEM coupling technology. By examining the deposition process, the role of particle characteristics on dust behavior within the entire filtration system was elucidated. The effects of varying particle surface energy and particle sphericity on filtration pressure drop and cake porosity were analyzed. The findings reveal that under the force of the air, particles on the surface of the filter membrane experience compaction, leading to a reduction in the porosity of the formed cake layer. The diminution of porosity serves to impede the air, consequently augmenting the pressure drop across the filtration system and hindering the operational efficacy of the dust collector. As the surface energy of the particles increases, the adhesive forces between particles are intensified, leading to an elevation in the porosity of the cake layer and a subsequent decrease in the pressure drop. When the surface energy of the particles is increased from 0.01 J/m2 to 0.04 J/m2, the porosity experiences a modest increase of only 9.1%, yet the pressure drop is significantly reduced by half, amounting to a decrease of 1594 Pa. Under high particle surface energy, as filtration air velocity increases, particles are compressed, resulting in a decrease in cake porosity and an increase in pressure drop. Concurrently, our findings indicate that as the sphericity of particles increases, their surfaces become increasingly smooth which in turn results in a decreased porosity of the cake layer and, consequently, an elevation in the filtration pressure drop. [ABSTRACT FROM AUTHOR]

To explore the size, morphology, and distribution patterns of internal pore defects in WE43 magnesium alloy formed by laser powder bed fusion (LPBF), as well as their impact on its mechanical properties, computer tomography (CT), metallographic microscopy, and scanning electron microscopy were used to observe the material's microstructure and the morphology of tensile test fractures. The study revealed that a large number of randomly distributed non-circular pore defects exist internally in the LPBF-formed WE43 magnesium alloy, with a defect volume fraction of 0.16%. Approximately 80% of the defects had equivalent diameters concentrated in the range of 10∼40 μm, and 56.2% of the defects had sphericity values between 0.65∼0.7 μm, with the maximum defect equivalent diameter being 122 μm. There were a few spherical pores around 20 μm in diameter in the specimens, and unfused powder particles were found in pore defects near the edges of the parts. Under the test conditions, the fusion pool structure of LPBF-formed WE43 magnesium alloy resembled a semi-elliptical shape with a height of around 66 μm, capable of fusion three layers of powder material in a single pass. Columnar grains formed at the edge of individual fusion pools, while the central area exhibited equiaxed grains. The "scale-like pattern" formed by overlapping fusion pool structures resulted in the microstructure of LPBF-formed WE43 magnesium alloy mainly consisting of fine equiaxed grains with a size of 2.5 μm and columnar grains distributed in a band-like manner. [ABSTRACT FROM AUTHOR]

The performance of gravel layer in highways is influenced by the properties of the gravel particles. The particle shape is a key characteristic affecting the bearing capacity of the gravel layer, represented by angularity and sphericity indices. The impact of particle angularity and sphericity on the macroscopic and microscopic mechanical properties of gravel soil was investigated through discrete element simulation employing the overlapping rigid clusters method. Numerical models of triaxial tests for gravel soil with different particle shapes under the same porosity conditions were established, and the evolution of internal friction angle, volumetric strain, mechanical coordination number, structure, and contact force chain was explored. The results indicate that the internal friction angle increases with the increase of angularity index (AI) and decreases with the increase of sphericity index (SPH). Under large strains, the shear dilation ratio significantly increases with increasing AI, while it initially increases and then decreases with the increase of SPH. On a microscopic scale, the mechanical coordination number increases with AI and decreases with SPH. The deviatoric fabric increase with the increase of AI and the decrease with SPH. Particle shape influences the distribution of microscopic contact force chains, thereby affecting the macroscopic shear strength. [ABSTRACT FROM AUTHOR]

This work focuses on porosity formation during the welding of dissimilar aluminium alloys (cast and sheet) by pulsed gas metal arc welding (GMAW) with different travel speeds (12–14 mm/s) and by friction stir welding (FSW). The case study concerns the assembling of a battery-pack enclosure prototype. The welded specimens were scanned by 3D X-ray computed tomography. The cast base material (BM) shows a porosity percentage of 1.45%, and it is characterized by pores with a strong hyperbolic relationship between equivalent diameter and sphericity. Considering the GMAW beads, porosity rises with the travel speed (from 1.80 to 5.12%), due to the reduction of the opening window in which pores can escape. Pores with volume higher than 0.10 mm3 rise with the travel speed, representing from 9.75 to 32.98% of the total porosity. These pores are responsible for the weaker hyperbolic connection for sphericity found for the GMAW beads. On the other hand, FSW mixes and homogenizes the pores in the cast BM. The novelty of the paper lays in proving the strong potentialities of FSW for weld porosity reduction. A re-designing of the battery-pack enclosures is necessary to limit arc welding in marginal areas, which are not crucial for sealing but necessary to create a stable platform to be subsequently sealed with FSW. [ABSTRACT FROM AUTHOR]

While the macroscopic mechanical properties of earthen-site soils have undergone extensive experimental and modeling studies, few research efforts focus on the relationship between the overall mechanical behavior and micro-pore structure. We developed a microstructure-based finite element model to investigate the influence of micro-pore structure on the macroscopic mechanical behavior of earthen-site soils. Scanning electron microscopy images of the untreated and consolidated soils were processed to compare the changes in equivalent diameter, sphericity, and porosity of the soils after consolidation. According to the pore parameter range of the untreated and consolidated soils, the effects of micro-pores on the soil behavior are specifically conducted under both static and dynamic loads. The relationships between pore characteristics and stiffness, strength, and ultrasonic wave velocity are established.

The article argues that scientific cosmology, the study of the Universe’s origin, evolution, and structure, remains an essential and integral part of scientific thinking. The article traces the roots of scientific thinking back to ancient Greek philosophy, particularly the work of Plato and Aristotle. These philosophers were the first to provide a clear justification for scientific knowledge, laying the foundation for its development in subsequent centuries. However, modern science no longer accepts their justifications as definitive. This raises the question: how can scientific thinking function without the traditional foundations laid by the Greeks? The article proposes a solution: general concepts can objectively exist as a property of the inherent uniformity and isotropy of space and time. This is not limited to just geometric and physical forms but extends to social, cultural, and other realms. Space can be understood as having dimensions, sets of characteristics used to define an object. These “spaces” are abstract constructs humans create to solve specific problems. The same object can occupy homogenous or heterogeneous spaces, depending on the problem being tackled. Time, unlike space, is irreversible and intrinsically anisotropic. However, it can be considered quasi-isotropic and quasi-homogeneous in some specific cases. The development of these concepts of homogeneity and heterogeneity in both physical (geometric) space and time constitutes the foundation of scientific cosmology.

Abstract Background The presence of mediastinal lymph node metastasis is important because it is related to the treatment and prognosis of lung cancer. Although prevalently used, evaluation of lymph nodes is not always reliable. We introduced sphericity as a criterion for evaluating morphologic differences between metastatic and nonmetastatic nodes. Methods We reviewed the cases of 66 patients with N2 disease and of 68 patients with N0-1 disease who underwent lobectomy with mediastinal dissection between January 2012 and December 2021. The sphericity of the dissected station lymph nodes, which represents how close the node is to being a true sphere, was evaluated along with the diameter and volume. Each parameter was obtained and evaluated for ability to predict metastasis. Results Metastatic lymph nodes had a larger short-axis diameter (average: 8.2 mm vs. 5.4 mm, p

The best practice for killing decapod crustaceans lacking a centralized ganglion has been debated for a century. Currently, there is a movement away from live boiling towards electrocution and mechanical splitting or spiking, which are efficient in the large commercial setting but may be unavailable and impractical for small decapods such as shrimp and prawn in the small-scale setting of, e.g., the household. Here, using carcasses of varying sizes of prawn, crayfish, lobster and green and brown crab, we used micro-CT imaging to measure surface area and sphericity in relation to body mass. Then, we measured heating profiles at the anterior ganglion and in the core of carcasses of the same species when exposed to standardized boiling regimes. We found a relationship with positive allometry between surface area and body mass for all species and a decrease in sphericity with mass. Heating times until proposed stunning (26 °C) and killing (44 °C) varied with body size and starting temperature and exceeded minutes for larger species. For a small species like prawn, times to stunning and killing by boiling are comparable to electrocution times and within the acceptable range compared to recreational killing of other sentient beings such as game mammals.

Coordinate measuring machines (CMMs) are utilized to acquire coordinate data from manufactured surfaces for inspection reasons. These data are employed to gauge the geometric form errors associated with the surface. An optimization procedure of fitting a substitute surface to the measured points is applied to assess the form error. Since the traditional least-squares approach is susceptible to overestimation, it leads to unreasonable rejections. This paper implements a modified differential evolution (DE) algorithm to estimate the minimum zone femoral head sphericity. In this algorithm, opposition-based learning is considered for population initialization, and an adaptive scheme is enacted for scaling factor and crossover probability. The coefficients of the correlation factor and the uncertainty propagation are also measured so that the result’s uncertainty can be determined. Undoubtedly, the credibility and plausibility of inspection outcomes are strengthened by evaluating measurement uncertainty. Several data sets are used to corroborate the outcome of the DE algorithm. CMM validation shows that the modified DE algorithm can measure sphericity with high precision and consistency. This algorithm allows for an adequate initial solution and adaptability to address a wide range of industrial problems. It ensures a proper balance between exploitation and exploration capabilities. Thus, the suggested methodology, based on the computational results, is feasible for the online deployment of the sphericity evaluation. The adopted DE strategy is simple to use, has few controlling variables, and is computationally less expensive. It guarantees a robust solution and can be used to compute different form errors.

In phytoplankton ecology the shape of microalgae appears predominantly as a categorical variable. Using shape-realistic 3D models of 220 microalgae we proposed and calculated six shape metrics and tested how these relate to each other and to the size of the microalgae. We found that some of the metrics are more sensitive to elongation, while others are related to multicellularity. We found a linear relationship between shape measures and the greatest axial linear dimensions of the microalgae. Our findings suggest that there is an evolutionary trade-off between the shape and size of the microalgae. It is important to stress that we found that surface area to volume ratio of the microalgae are hyperbolic functions of the length and volume for each shape. In our study, we demonstrated that the proposed shape metrics serve as suitable quantitative traits, and help to understand better how simple shapes evolved to more complex outlines. [ABSTRACT FROM AUTHOR]

This study aims to suggest a new method for predicting 3D sphericity through traditional 2D image processing through a novel sieving analysis. The 3D sphericity indices of grains (over 3000 particles for each material) from seven irregular granular materials are determined using μCT slices. These indices are then compared with existing 2D indices obtained through SEM image processing. Additionally, seven synthetic materials (semi-regular in size and shape) are also assessed to account for unusual particle shapes. The findings shed light on the role of sphericity in the rate at which particles pass through sieve openings. The results indicate that the initial passing rate of grains is strongly correlated with the 3D sphericity indices, which significantly decrease as sphericity decreases. The proposed method involves a sequential sieving test, performed similarly to the conventional sieving test but conducted sequentially at different time steps. Several correlations between 3D sphericity and its 2D counterparts are presented, which can successfully predict the 3D sphericity indices. Additionally, two empirical equations are proposed to predict the most frequent flatness and elongation aspect ratios, used in the Zingg diagram. Furthermore, the grading analysis derived from both 2D and 3D image processing is compared with sieve analysis. The results show that, unlike the 2D results, the grading curves obtained from 3D image processing are in excellent agreement with the sieve analysis. A corrected grading curve, derived from traditional 2D image processing, is proposed to align with 3D grading curves. [ABSTRACT FROM AUTHOR]

The article argues that scientific cosmology, the study of the Universe's origin, evolution, and structure, remains an essential and integral part of scientific thinking. The article traces the roots of scientific thinking back to ancient Greek philosophy, particularly the work of Plato and Aristotle. These philosophers were the first to provide a clear justification for scientific knowledge, laying the foundation for its development in subsequent centuries. However, modern science no longer accepts their justifications as definitive. This raises the question: how can scientific thinking function without the traditional foundations laid by the Greeks? The article proposes a solution: general concepts can objectively exist as a property of the inherent uniformity and isotropy of space and time. This is not limited to just geometric and physical forms but extends to social, cultural, and other realms. Space can be understood as having dimensions, sets of characteristics used to define an object. These "spaces" are abstract constructs humans create to solve specific problems. The same object can occupy homogenous or heterogeneous spaces, depending on the problem being tackled. Time, unlike space, is irreversible and intrinsically anisotropic. However, it can be considered quasi-isotropic and quasi-homogeneous in some specific cases. The development of these concepts of homogeneity and heterogeneity in both physical (geometric) space and time constitutes the foundation of scientific cosmology. [ABSTRACT FROM AUTHOR]

The morphology characteristics (sphericity, roundness, and surface roughness) affecting the destruction of gangue minerals on graphite flakes during the grinding process were systematically analyzed. Coupled with MS and SEM, sphericity analysis showed that graphite was flaky, which was similar to muscovite but different from granulous quartz and albite, and the roundness of the four minerals from high to low was graphite, quartz, albite, and muscovite. AFM analysis showed that the surface roughness of graphite and muscovite was very low compared to that of quartz and albite (higher than quartz). The size and crystal integrity of graphite flakes were both destroyed by gangues during the grinding process, and the destruction of quartz and albite was serious compared to that of muscovite. Sphericity dominantly affected the destruction: the larger the sphericity, the more serious the destruction, which was also negatively related to roundness but positively related to surface roughness. [ABSTRACT FROM AUTHOR]

This study focuses on the significant impact of moisture content on the engineering properties of cowpea seeds, which is vital for designing effective agricultural tools, equipment, and machines. We specifically examined two cowpea seed varieties, SAMPEA-16 and SAMPEA-14, across different moisture levels (10, 15, 20, 25, and 30% wb). Our findings show distinct variations in the physical characteristics of these seeds as the moisture content changes. For both SAMPEA-16 and SAMPEA-14, we observed changes in average length, width, and thickness at each moisture level. At moisture contents ranging from 10% to 30% wb, the dimensions for SAMPEA-16 were 11.20 mm by 9.10 mm by 8.61 mm, gradually changing to 10.60 mm by 8.80 mm by 8.50 mm, and for SAMPEA-14, they ranged from 8.30 mm by 6.50 mm by 6.50 mm to 8.40 mm by 6.50 mm by 6.40 mm. Significantly, the 1000 seed mass for SAMPEA-16 increased from 302.30 g to 404.80 g within the 15% to 30% moisture range, while the sphericity varied from 0.849 to 0.877. For SAMPEA-14, similar trends were observed with the sphericity shifting from 0.848 to 0.852. Additionally, the true density for SAMPEA-14 and SAMPEA-16 changed from 1034.12 kg m-3 to 1074.40 kg m-3 and 1089.61 kg m-3 to 1116.87 kg m-3, respectively. Another notable finding is the increase in the angle of repose with moisture content. For SAMPEA-16, it rose from 22.40˚ to 30.23˚, and for SAMPEA-14, from 23.22˚ to 34.28˚, as moisture content increased from 10% to 30%. Furthermore, the terminal velocity for both varieties increased with moisture, with SAMPEA-14 ranging from 4.92 to 5.25, and SAMPEA-16 from 5.72 to 6.16, at 10% to 25% moisture content. The insights from this study are crucial for the design of agricultural machinery, processing units, and storage facilities, aiming to enhance the quality and quantity of cowpea produce. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, the important scientific and technical problem of creating multifunctional composite materials for shipbuilding and ocean engineering was solved. The work aimed to study the thermal deformation processes of sintering glass microspheres to obtain lightweight glass composites with a cellular structure that provides positive buoyancy and sound insulation properties. For this purpose, glass microspheres of Na2O‒SiO2 and Na2O‒B2O3‒SiO2 composition with a dispersion of 10 to 60 μm were used as raw materials. They were sintered to form a closed, porous structure. The theoretical substantiation of technological parameters is based on the concepts of solid state and glassy state chemistry and physicochemical concepts of glass softening processes. The process of hot-pressing glass microspheres without plasticisers and additives was investigated. The author’s own laboratory equipment was used for the experiments. The sintering intensity was determined from the results of shrinkage processes; the kinetic shrinkage curves were constructed in semilogarithmic coordinates. The glass composite samples were examined by optical and electron microscopy. As a criterion, the storage of spherical microspheres under the influence of simultaneous heating to 700 °C with the application of pressure in the range of 0,5 to 1,5 MPa was chosen. It was established that the formation of a predominantly closed-porous structure of glass composites with a density of 350...600 kg/m3 occurs by the mechanisms of viscous glass phase flow through liquefaction processes in the walls of microspheres. At the same time, shrinkage processes in the linear direction reach up to 50%.

The analysis of sands, and the foundation systems with which they interact, are largely dependent on macroscale behavioral parameters that represent the aggregated response of several microscale characteristics. This research paper examines the influence of surface texture, or smoothness, on the behavior of sands. The challenge of estimating or measuring smoothness, due to its microscale feature domain, is addressed through an examination of six artificially graded sand specimens. These specimens are evaluated both visually and numerically to characterize their surface smoothness. The first approach described is a simple visual method that uses a smoothness scale consistent with those of roundness and sphericity. This method, which can be performed with a tool as simple as a hand lens, evaluates a group of representative particles collectively. The second approach is also a visual evaluation, but it utilizes images obtained via scanning electronic microscopy, traditional optical microscopy, and newer low-cost digital microscopes that can be rapidly connected to a smartphone or laptop. To validate these visual estimates, a novel third approach is introduced. This approach is a more objective numerical analysis measurement technique that enables rapid and economic quantification of smoothness. This technique may assist both practitioners and academics in their understanding of the macroscale response of coarse-grained soils. In addition to the visual methods, this research also conducted several laboratory index tests to observe the mechanical behavior of the specimens, considering their particle shape and surface smoothness properties. The results indicate that angular sands have greater minimum and maximum void ratios, a larger difference between the minimum and maximum void ratios, greater critical state friction angles, and greater flow rates through an orifice of fixed size. When adjusted for surface smoothness using the proposed approach, the behavior of the sands—particularly the limit void ratio results—appears to be more predictable in some cases. These results provide additional evidence of particle smoothness contributing to the strength behavior of sand, which may be particularly useful in the domains of slope stability, land reclamation, soil–structure interaction, and soil dynamics.

The measure of sphericity for positive semi-definite matrices plays a crucial role in understanding their geometric properties, especially in high-dimensional settings. This paper introduces a robust measure of sphericity, which remains invariant under orthogonal transformations and scaling. We explore its behavior in finite-dimensional cases. Additionally, we investigate the stochastic case by considering a normal distribution, analyzing the asymptotic normality of random matrices and its implications on the convergence properties of the proposed measure.

To explore the size, morphology, and distribution patterns of internal pore defects in WE43 magnesium alloy formed by laser powder bed fusion (LPBF), as well as their impact on its mechanical properties, computer tomography (CT), metallographic microscopy, and scanning electron microscopy were used to observe the material’s microstructure and the morphology of tensile test fractures. The study revealed that a large number of randomly distributed non-circular pore defects exist internally in the LPBF-formed WE43 magnesium alloy, with a defect volume fraction of 0.16%. Approximately 80% of the defects had equivalent diameters concentrated in the range of 10∼40 μm, and 56.2% of the defects had sphericity values between 0.65∼0.7 μm, with the maximum defect equivalent diameter being 122 μm. There were a few spherical pores around 20 μm in diameter in the specimens, and unfused powder particles were found in pore defects near the edges of the parts. Under the test conditions, the fusion pool structure of LPBF-formed WE43 magnesium alloy resembled a semi-elliptical shape with a height of around 66 μm, capable of fusion three layers of powder material in a single pass. Columnar grains formed at the edge of individual fusion pools, while the central area exhibited equiaxed grains. The “scale-like pattern” formed by overlapping fusion pool structures resulted in the microstructure of LPBF-formed WE43 magnesium alloy mainly consisting of fine equiaxed grains with a size of 2.5 μm and columnar grains distributed in a band-like manner.

The adhesion of dust particles on the surface of the dust collector tends to cause great resistance to the dust collector and affects the operating efficiency. In order to visualize particles in the filtration process and to grasp the mechanism of particle viscosity and sphericity on filtration performance, a numerical simulation study was conducted to investigate the deposition behavior of particles during filtration, employing FLUENT-EDEM coupling technology. By examining the deposition process, the role of particle characteristics on dust behavior within the entire filtration system was elucidated. The effects of varying particle surface energy and particle sphericity on filtration pressure drop and cake porosity were analyzed. The findings reveal that under the force of the air, particles on the surface of the filter membrane experience compaction, leading to a reduction in the porosity of the formed cake layer. The diminution of porosity serves to impede the air, consequently augmenting the pressure drop across the filtration system and hindering the operational efficacy of the dust collector. As the surface energy of the particles increases, the adhesive forces between particles are intensified, leading to an elevation in the porosity of the cake layer and a subsequent decrease in the pressure drop. When the surface energy of the particles is increased from 0.01 J/m2 to 0.04 J/m2, the porosity experiences a modest increase of only 9.1%, yet the pressure drop is significantly reduced by half, amounting to a decrease of 1594 Pa. Under high particle surface energy, as filtration air velocity increases, particles are compressed, resulting in a decrease in cake porosity and an increase in pressure drop. Concurrently, our findings indicate that as the sphericity of particles increases, their surfaces become increasingly smooth which in turn results in a decreased porosity of the cake layer and, consequently, an elevation in the filtration pressure drop.

ObjectiveSpinal meningiomas (SM) account for 25%–46% of all primary spinal tumors and show an excellent long-term disease control in case of complete resection. Therefore, the postoperative functional outcome is of high importance. To date, reports on dorsally located SM are scarce. Moreover, the impact of radiomics shape features on the functional outcome after surgery for primary dorsal SMs has not been analyzed yet.MethodsWe retrospectively performed an analysis of shape-based radiomic features in 3D slicer software and quantified the tumor volume, surface area, sphericity, surface area to volume ratio and tumor canal ratio. Subsequently, we evaluated the correlation between the radinomic parameters and the postoperative outcome according to Modified Japanese Orthopedic Association (mJOA) score.ResultsBetween 2010 and 2022, we identified 24 Females and 2 Males operated on dorsal SMs in our institutional database. The most common SM localization was thoracic spine (n = 20), followed by cervical (n = 4), and lumbar (n = 2). The univariate analysis and the receiver operating characteristic (ROC) analysis showed a strong diagnostic performance of sphericity in the prediction of postoperative functional outcome based on mJOA score (AUC of 0.79, sphericity cut-of value 0.738; p = 0.01). Subsequently, the patients were divided into two groups (mJOA improved vs. mJOA stable/worsened). Patients with improved mJOA score showed significantly higher sphericity (0.79 ± 0.1 vs. 0.70 ± 1.0; p = 0.03). Finally, we divided the cohort based on sphericity (

The prognostic impact of tumor volume and tumor sphericity was analyzed in 95 patients affected by oral cancer. The pre-operative computed tomography (CT) scans were used to segment the tumor mass with threshold tools, obtaining the corresponding volume and sphericity. Events of recurrence and tumor-related death were detected for each patient. The mean follow-up time was 31 months. A p-value of 0.05 was adopted. Mean tumor volume resulted higher in patients with recurrence or tumor-related death at the Student's t-test (respectively, 19.8 cm3 vs. 11.1 cm3, p = 0.03; 23.3 cm3 vs. 11.7 cm3, p = 0.02). Mean tumor sphericity was higher in disease-free patients (0.65 vs. 0.59, p = 0.04). Recurrence-free survival and disease-specific survival were greater for patients with a tumor volume inferior to the cut-off values of 21.1 cm3 (72 vs. 21 months, p < 0.01) and 22.4 cm3 (85 vs. 32 months, p < 0.01). Recurrence-free survival and disease-specific survival were higher for patients with a tumor sphericity superior to the cut-off value of 0.57 (respectively, 49 vs. 33 months, p < 0.01; 56 vs. 51 months, p = 0.01). To conclude, tumor volume and sphericity, three-dimensional parameters, could add useful information for better stratification of prognosis in oral cancer. [ABSTRACT FROM AUTHOR]

Identifying sands is an important requirement in many geotechnical exploration projects. Knowledge of the sand type can help in estimating the physical and mechanical properties of a soil. Previous studies revealed that machine learning approaches using neural networks (NN) can correctly identify up to 75% of individual sand particles using size and shape descriptors. This study explores the efficacy of deep learning methods for automatically classifying sand types from individual images of sand particles. Dynamic image analysis (DIA) was employed to generate a large data set of sand particle images, which were then used for training a deep learning model known as convolutional neural networks (CNN). The analysis was based on 40,000 binary particle images for twenty types of sand. The work demonstrates that computer vision has a remarkable ability to automatically classify 64% of individual sand particles among 20 types of sand, the accuracy for sand clusters can reach up to 100%, when a CNN model augmented with size and shape data was employed. The effects of domain size, size and shape parameters, and the selected CNN model on the classification accuracy were also investigated. The results demonstrate that sand classification using a larger number of sand types resulted in a lower classification accuracy. Classification accuracy of individual particles achieved using CNN were 10%–15% better than those achieved using NN. CNN can automatically and adaptively learn the spatial hierarchy of features which is superior to the handcrafted size and shape parameters, used by NN for identifying sand particles. The study suggests that classification accuracy benefits from data augmentation use of more particle orientations, even at the cost of trimming some particles, and suffers from reduction in image resolution. While model training requires a lot of computational work, a pretrained CNN model may potentially be tuned to run on mobile phones, which points to the potential for real-time field deployment to enable automatic soil classification on-site. [ABSTRACT FROM AUTHOR]

The microsphere profile of probe tips has to be measured and compensated to improve the measurement accuracy of micro-coordinate measuring machines (micro-CMMs) to less than several hundred nanometers. A high-precision radius and sphericity measurement method for the microsphere of the CMM probe tip is proposed in this article. Different circumferences of the tested microsphere are measured, and the true radius of any measuring point on the surface can be obtained after separating the runout errors. Then the sphericity of the tested microsphere can be evaluated by the minimum zone sphere method. A corresponding measuring system is developed based on the analysis of the primary error model and mechanical model, and verification experiments are conducted using a ruby microsphere (A-5000-7801, Renishaw Corporation) as the reference, whose claimed diameter and sphericity are 700 µm and 130 nm, respectively. Six groups of repeated experiments are performed, and 18 000 measurement points on 15 circumferences are recorded in each group of experiments. Results show that the average radius of the tested microsphere is 350.003 µm, and the average sphericity error is 208 nm with a standard deviation of 5.3 nm. Finally, the expanded uncertainty of the measurement results of the developed system is calculated as 209 nm (k = 1.96, normal distribution). The proposed method and system can be used in the precision measurements and compensations for probe tips of micro-CMMs and other parts, such as microspheres used in micro-bearings and micro-manufacturing machines. [ABSTRACT FROM AUTHOR]

A plasma-arc unit of industrial type of up to 50 kw total power for deposition of functional coatings on critical parts and spheroidization of wire materials is presented. A feature of the unit is application of a system of water cooling of plasmatron internal components, modified design of the nozzle and cathode parts and reduction of plasmatron overall dimensions, ensuring a higher productivity of the process, widening of its application areas, improvement of mechanical and technological characteristics of the produced granules and coatings, etc. presented is the microstructure and results of studying the granulometric composition of the dispersed phase, which are indicative of producing dense coatings with less than 1 % porosity, forming from granules of a spherical shape predominantly in a narrow particle size range of 20-100 μm. [ABSTRACT FROM AUTHOR]

Obstruction flatness of a strongly pseudoconvex hypersurface Σ in a complex manifold refers to the property that any (local) Kähler-Einstein metric on the pseudoconvex side of Σ, complete up to Σ, has a potential − log ⁡ u such that u is C ∞ -smooth up to Σ. In general, u has only a finite degree of smoothness up to Σ. In this paper, we study obstruction flatness of hypersurfaces Σ that arise as unit circle bundles S (L) of negative Hermitian line bundles (L , h) over Kähler manifolds (M , g). We prove that if (M , g) has constant Ricci eigenvalues, then S (L) is obstruction flat. If, in addition, all these eigenvalues are strictly less than one and (M , g) is complete, then we show that the corresponding disk bundle admits a complete Kähler-Einstein metric. Finally, we give a necessary and sufficient condition for obstruction flatness of S (L) when (M , g) is a Kähler surface (dim ⁡ M = 2) with constant scalar curvature. [ABSTRACT FROM AUTHOR]

BACKGROUND: Geometric calibration is essential in developing a reliable computed tomography (CT) system. It involves estimating the geometry under which the angular projections are acquired. Geometric calibration of cone beam CTs employing small area detectors, such as currently available photon counting detectors (PCDs), is challenging when using traditional-based methods due to detectors' limited areas. OBJECTIVE: This study presented an empirical method for the geometric calibration of small area PCD-based cone beam CT systems. METHODS: Unlike the traditional methods, we developed an iterative optimization procedure to determine geometric parameters using the reconstructed images of small metal ball bearings (BBs) embedded in a custom-built phantom. An objective function incorporating the sphericities and symmetries of the embedded BBs was defined to assess performance of the reconstruction algorithm with the given initial estimated set of geometric parameters. The optimal parameter values were those which minimized the objective function. The TIGRE toolbox was employed for fast tomographic reconstruction. To evaluate the proposed method, computer simulations were carried out using various numbers of spheres placed in various locations. Furthermore, efficacy of the method was experimentally assessed using a custom-made benchtop PCD-based cone beam CT. RESULTS: Computer simulations validated the accuracy and reproducibility of the proposed method. The precise estimation of the geometric parameters of the benchtop revealed high-quality imaging in CT reconstruction of a breast phantom. Within the phantom, the cylindrical holes, fibers, and speck groups were imaged in high fidelity. The CNR analysis further revealed the quantitative improvements of the reconstruction performed with the estimated parameters using the proposed method. CONCLUSION: Apart from the computational cost, we concluded that the method was easy to implement and robust. [ABSTRACT FROM AUTHOR]

The analysis of sands, and the foundation systems with which they interact, are largely dependent on macroscale behavioral parameters that represent the aggregated response of several microscale characteristics. This research paper examines the influence of surface texture, or smoothness, on the behavior of sands. The challenge of estimating or measuring smoothness, due to its microscale feature domain, is addressed through an examination of six artificially graded sand specimens. These specimens are evaluated both visually and numerically to characterize their surface smoothness. The first approach described is a simple visual method that uses a smoothness scale consistent with those of roundness and sphericity. This method, which can be performed with a tool as simple as a hand lens, evaluates a group of representative particles collectively. The second approach is also a visual evaluation, but it utilizes images obtained via scanning electronic microscopy, traditional optical microscopy, and newer low-cost digital microscopes that can be rapidly connected to a smartphone or laptop. To validate these visual estimates, a novel third approach is introduced. This approach is a more objective numerical analysis measurement technique that enables rapid and economic quantification of smoothness. This technique may assist both practitioners and academics in their understanding of the macroscale response of coarse-grained soils. In addition to the visual methods, this research also conducted several laboratory index tests to observe the mechanical behavior of the specimens, considering their particle shape and surface smoothness properties. The results indicate that angular sands have greater minimum and maximum void ratios, a larger difference between the minimum and maximum void ratios, greater critical state friction angles, and greater flow rates through an orifice of fixed size. When adjusted for surface smoothness using the proposed approach, the behavior of the sands—particularly the limit void ratio results—appears to be more predictable in some cases. These results provide additional evidence of particle smoothness contributing to the strength behavior of sand, which may be particularly useful in the domains of slope stability, land reclamation, soil–structure interaction, and soil dynamics. [ABSTRACT FROM AUTHOR]

This article demonstrates how to perform univariate repeated measures ANOVA (U-RM-ANOVA) as a special case of structural equation models (SEMs). In the literature, sphericity is usually defined in terms of variances of pairwise differences of within-subject conditions. This article illustrates the original definition by Huynh and Feldt (1970) in terms of (co)variances of contrasts using SEM and demonstrates how to impose, test, and relax sphericity, and how to test main/interaction effects with and without the assumption of sphericity in SEM. We perform two simulation studies. The first study compares Mauchly’s sphericity test with an SEM based test and shows that the two approaches have a very similar Type 1 error and power. The second study compares U-RM-ANOVA with SEM for different degrees of departure from sphericity and shows that U-RM-ANOVA and SEM have similar statistical properties in terms of Type 1 error, power, as well as similar bias and efficiency of effect size estimates of main and interaction effects. We furthermore show how to implement sphericity in latent variable models and provide software to perform the proposed tests and analyses.

Featured Application: Porous ceramic supports, and catalytic ceramic carrier. The proper application of millimeter-sized spherical porous ceramic supports in catalytic operations relies on their ease of handling, convenient separation, recyclability, high-catalyst-solid loading, and the optimum mass transfer of reactants and products. However, common granulation techniques of spherical carriers entail complex liquid-phase-based processes under severe conditions and the use of toxic or expensive reagents. The present study discusses the manufacturing of porous ceramic granules derived from an inexpensive silica source (diatomite, solid network) and a biopolymer cross-linked by ion exchange (sodium alginate, patterning structure). The results indicated that, with fixed granulation conditions, porous diatomite granules with a sphericity of approximately 0.9 could be successfully obtained by optimization of the diatomite/sodium alginate dispersion to a 30.07 wt.% solid content and 1560 mPa·s viscosity (at ~0.3 s−1). Moreover, the described manufacturing process was proven effective in developing hierarchically porous diatomite granules that were heat-treated at 1200 °C with high sphericity (~0.9), acceptable compressive strength (5.17 ± 0.31 MPa), and porosity features (total porosity: 69.0 ± 2.9%, macropore size: 2.777 μm, mesopore size: 35.34 nm), establishing them as well-matched support materials for either catalytic or adsorption applications. [ABSTRACT FROM AUTHOR]

Achieving homogeneity and reproducibility in the size, shape, and morphology of active pharmaceutical ingredient (API) particles is crucial for their successful manufacturing and performance. Herein, we describe a new method for API particle engineering using melt-jet printing technology as an alternative to the current solvent-based particle engineering methods. Paracetamol, a widely used API, was melted and jetted as droplets onto various surfaces to solidify and form microparticles. The influence of different surfaces (glass, aluminum, polytetrafluoroethylene, and polyethylene) on particle shape was investigated, revealing a correlation between substrate properties (heat conduction, surface energy, and roughness) and particle sphericity. Higher thermal conductivity, surface roughness, and decreased surface energy contributed to larger contact angles and increased sphericity, reaching a near-perfect micro-spherical shape on an aluminum substrate. The integrity and polymorphic form of the printed particles were confirmed through differential scanning calorimetry and X-ray diffraction. Additionally, high-performance liquid chromatography analysis revealed minimal degradation products. The applicability of the printing process to other APIs was demonstrated by printing carbamazepine and indomethacin on aluminum surfaces, resulting in spherical microparticles. This study emphasizes the potential of melt-jet printing as a promising approach for the precise engineering of pharmaceutical particles, enabling effective control over their physiochemical properties. [ABSTRACT FROM AUTHOR]

Dietary fibers (DF) are separated by different methods, of which the dry processing method is relatively unexplored. For the first time, a dry process (elutriator) is reported to be used to recover DF from fruit peel. In this study, an elutriator was designed to separate DF from sweet lime peel (SLP) powder. Separated product was analyzed for total dietary fiber (TDF), and micrographs were taken using scanning electron microscopy (SEM) to understand the surface morphology. Effect of particle size and terminal velocity on the separation of DF was studied. Physical properties that are deterministic in the efficient separation of DF by dry separation methods are particle bulk density, equivalent spherical diameter, sphericity, and terminal velocities of fibers. Further, particle size, terminal velocity, and other operating parameters were optimized using Response Surface Methodology (RSM). By using an elutriator, the concentration of TDF increased from 62.15 to 82.26%. RSM models applied successfully for TDF and yield. A relationship between independent parameters like air velocity, particle size, and dependent parameters like yield and TDF recovered was developed. The generalized relationship was validated on SLP and predicted air velocity of 2.04 m/s and particle size 926.85 micron, which is found to meet experimental results as the best conditions to operate elutriator. A general model to predict air velocity to separate DF for the given peel waste based on particle bulk density, equivalent spherical diameter, and sphericity is proposed and validated. [ABSTRACT FROM AUTHOR]

A plasma-arc unit of industrial type of up to 50 kW total power for deposition of functional coatings on critical parts and spheroidization of wire materials is presented. A feature of the unit is application of a system of water cooling of plasmatron inner components, modified design of the nozzle and cathode parts and reduction of plasmatron overall dimensions, ensuring a higher productivity of the process, widening of its application areas, improvement of mechanical and technological characteristics of the produced granules and coatings, etc. Presented is the microstructure and results of studying the granulometric composition of the dispersed phase, which are indicative of producing dense coatings with less than 1 % porosity, which form from granules of a spherical shape predominantly in a narrow particle size range of 20…100 μm. 17 Ref., 1 Tabl., 9 Fig. [ABSTRACT FROM AUTHOR]

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The three-body coupling grinding mode of a ball ensures the batch diameter variation and batch consistency of precision ball machining based on the principle of ball forming, resulting in a structure that is simply and feasibly controllable. The change in the rotation angle can be jointly determined using the fixed load of the upper grinding disc and the rotation speed coordination of the inner and outer discs of the lower grinding disc. Related to this, the rotation speed is an important index to guarantee grinding uniformity. To ensure the quality of three-body coupling grinding, this study aims to establish the best mathematical control model of the rotation speed curve of the inner and outer discs in the lower grinding disc. Specifically, it includes two aspects. First, the optimization of the rotation speed curve was mainly studied, and the machining process was simulated with three speed curve combinations: 1, 2, and 3. By analyzing the evaluation index of ball grinding uniformity, the results revealed that the third speed curve combination had the best grinding uniformity, and the three speed curve combinations were optimized on the basis of the traditional triangular wave speed curve. Furthermore, the obtained double trapezoidal speed curve combination not only achieved the traditionally verified stability performance but also overcame the shortcomings of the other speed curves. The mathematical model established in this way was equipped with a grinding control system, which improved the fine control ability of the rotation angle state of the ball blank under the three-body coupling grinding mode. It also obtained the best grinding uniformity and sphericity and laid a theoretical foundation for achieving a grinding effect that was close to the ideal circumstance during mass production. Second, via theoretical comparison and analysis, it was determined that the ball shape and sphericity deviation (SPD) were more accurate than the standard deviation (STD) of the two-dimensional trajectory point distribution. The SPD evaluation method was also investigated via the optimization analysis of the rotation speed curve by means of the ADAMAS simulation. The obtained results coincided with the STD evaluation trend, thus laying a preliminary foundation for subsequent applications. [ABSTRACT FROM AUTHOR]