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Journal articles on the topic 'Non-Spherical shape'

Author: Grafiati

Published: 4 June 2021

Last updated: 11 February 2022

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1

Chand, R., R. Hadj Lajimi, S. Uddin, S. Meghwar, U. Farooq, and N. Rekik. "Numerical Simulations on Mixing Dynamics of Spherical and Non-Spherical Tablets in a Pan Coater." Engineering, Technology & Applied Science Research 9, no. 6 (December 1, 2019): 5029–32. http://dx.doi.org/10.48084/etasr.3178.

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Discrete element simulations provide valuable insight into the mixing dynamics of granular materials in industry. In this paper, numerical work is conducted in order to find the influence of pan rotational velocity and particle shape on mixing behavior. Four types of particles of different shapes were chosen: spherical, non-spherical type 1 (disk shape), non-spherical type 2 (capsule shape), and non-spherical type 3 (triangular shape). The pan mixer was filled with ~ 30 % volume of the same shape with the particles and was rotated at 15 RPM, 30 RPM, 45 RPM, and 60 RPM. The particles were colored as bottom-particles, middle-particles, and top-particles in order to visualize mixing efficiency. The homogeneity of the mixtures was determined by using contact dynamics of particles. The results show that fast-rotating pan (30-60 RPM) provides good mixing for all shapes of particles. However, non-spherical particles do not show as good mixing as spherical particles.

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2

Santos, Elias Gomes, Luiz Carlos da Silva Carvalho, André Luiz Amarante Mesquita, Luiz Moreira Gomes, Kelvin Alves Pinheiro, and Alexandre Luiz Amarante Mesquita. "Discrete element modeling of non-spherical particles using a spherical shape." REM - International Engineering Journal 73, no. 3 (September 2020): 361–69. http://dx.doi.org/10.1590/0370-44672019730101.

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3

Watanabe, Chihiro, and Ryoichi Monzen. "Coarsening of Precipitated Particles with Non-spherical Shape." Materia Japan 52, no. 10 (2013): 475–83. http://dx.doi.org/10.2320/materia.52.475.

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4

Volgina, Liudmila, and Anastasiia Romanova. "Hydraulic size of non-spherical solid particles." E3S Web of Conferences 97 (2019): 05034. http://dx.doi.org/10.1051/e3sconf/20199705034.

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The paper studies impact of determining the diameter of solid particles on the calculation of the hydraulic particle size in the water flow. The relevance of the topic is also connected with the use of calculation of hydraulic size in hydraulic engineering in forecasting: downstream erosion, the formation of shoals, canals, bottom spillages, etc. Most of the empirical formulas for calculating the hydraulic particle size are applicable to spherical particles. However, the nature of the solid particles rarely has a spherical shape. The aim of this work is to investigate experimentally the dependence of the hydraulic size of the diameter of the solid particles. Different approaches to determining the diameter solid particles are analyzed, as for non-spherical particles finding the diameter is an independent and complex problem. For the experimental research solid particles of different shapes and sizes were used. The diameter is included in the empirical formulas for hydraulic size linearly, and to the power of 2 or 0.5. Therefore, the dependence of the experimental hydraulic size on the diameter was correlated with the corresponding functions. The shape of the particle significantly affects the value of the hydraulic size and depends on the diameter to the power of (0.5).

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5

Spârchez, Zeno. "The Separation of Spherical Shape Powder Particles from the Non-Spherical Ones." Advanced Materials Research 23 (October 2007): 87–90. http://dx.doi.org/10.4028/www.scientific.net/amr.23.87.

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The conditions needed for an efficient separation together with the most important factors influencing the accuracy of the separation are emphasized. Some relationships that allow the evaluation of the covering degree of the separation surface and the volume of the charge with single dimension particles corresponding to a unit separation surface are presented. The efficiency of spherical shape particles separation and the productivity of the separation process have been analysed. Some technical and practical considerations on the separation process are given.

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6

Andersen, Anders, and Julia Dölger. "Planktonic encounter rates with non-spherical encounter zones." Journal of The Royal Society Interface 16, no. 156 (July 2019): 20190398. http://dx.doi.org/10.1098/rsif.2019.0398.

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We present general formulae for planktonic predator–prey encounter rates with encounter zones of convex shape and randomly moving point-like prey with ballistic motion. When the predator is not moving, we show that the encounter rate is independent of the shape of the encounter zone around it and proportional to the product of the surface area of the encounter zone and the prey speed. By contrast, the shape of the encounter zone plays a role when both the predator and the prey are moving. Slow predator motion results in only a weak increase of the encounter rate relative to the non-motile predator situation, but it may lead to a significant shift in where prey impact the surface of the encounter zone. By analysing disc-like and rod-like encounter zones with lengthwise and sideways motion, respectively, we show that fast predator motion may significantly influence the encounter rate, depending on the shape and the direction of motion of the encounter zone.

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7

Ranjan, Shashi, Kerwin Kwek Zeming, Roland Jureen, Dale Fisher, and Yong Zhang. "DLD pillar shape design for efficient separation of spherical and non-spherical bioparticles." Lab Chip 14, no. 21 (September 11, 2014): 4250–62. http://dx.doi.org/10.1039/c4lc00578c.

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8

Yang, Zhongqiang, Wilhelm T. S. Huck, Stuart M. Clarke, Ali R. Tajbakhsh, and Eugene M. Terentjev. "Shape-memory nanoparticles from inherently non-spherical polymer colloids." Nature Materials 4, no. 6 (May 15, 2005): 486–90. http://dx.doi.org/10.1038/nmat1389.

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9

Spârchez, Zeno. "Fabrication of Metal Powders Having Spherical Shape Particles (an Overview)." Advanced Materials Research 23 (October 2007): 95–98. http://dx.doi.org/10.4028/www.scientific.net/amr.23.95.

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On the basis of a graphical classification devised by the author, the paper presents a brief analysis of the principal methods and procedures used for elaborating powders having spherical particles. The than discussion is focused on emphasizing and classifying the influence factors related to the material, processing method and equipment, which enables the obtaining of spherical particles. In the case of those methods which lead to both spherical and non-spherical particles, additional operations are needed the separation of the non-spherical particles, possibly followed by their conversion to spherical particles in a thermal field.

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10

Ji, W. M., F. Y. Jiang, and C. X. Chu. "CALCULATION AND ANALYSIS ON SCATTERING CHARACTERISTICS OF NON-SPHERICAL PARTICLES OF HAZE." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W9 (October 25, 2019): 83–88. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w9-83-2019.

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Abstract. The light scattering characteristics of sulfate, one of the main pollutant particles in haze, are calculated by T-Matrix method at a target wavelength of 550 nm. The variation between shape factors (such as effective radius and aspect ratio) and scattering phase functions with different types and shapes are analysed in small scale range. The influence of shape factors on scattering cross section and depolarization ratio of particles are also discussed. Results show that the shape of particles has great effects on the spatial distribution of scattering energy, and the scattering properties of particles are sensitive to aspect ratio. The depolarization of spherical particles is close to zero, while the difference between ellipsoidal and cylindrical particles reaches several orders of magnitude. When the equivalent radius is larger than 1.0 μm, the mean depolarization ratio of the non-spherical particles is greater than 0.2. The mean depolarization ratio and scattering cross section of non-spherical particle change continuously with a certain aspect ratio and particle size range, and the shape of some particles can be therefore distinguished under certain conditions.

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11

Shklyaev, Sergey, John F. Brady, and Ubaldo M. Córdova-Figueroa. "Non-spherical osmotic motor: chemical sailing." Journal of Fluid Mechanics 748 (May 1, 2014): 488–520. http://dx.doi.org/10.1017/jfm.2014.177.

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AbstractThe behaviour of a non-spherical osmotic motor – an axisymmetric catalytic particle self-propelling in a dilute dispersion of reactant particles – is considered. In contrast to a conventional osmotic motor that creates differences in concentration, and hence in osmotic pressure, due to asymmetry in reaction rate along its surface (e.g. a Janus particle with reactive and non-reactive patches), a non-spherical particle is able to move even with uniform chemical activity on its surface. For small departures from a sphere the velocity of self-propulsion is proportional to the square of the non-sphericity or distortion of the particle shape. It is shown that the inclusion of hydrodynamic interactions (HI) may drastically change the self-propulsion. Except for very slow chemical reactions, even the direction of self-propulsion changes with and without HI. Numerical calculations at finite non-sphericity suggest that the maximum velocity of self-propulsion is obtained by a sail-like motor shape, leading to the name ‘chemical sailing’. Moreover, no saturation in the speed of propulsion is found; the motor velocity increases as the area of this ‘sail’ grows and its thickness decreases. The self-propulsion of a non-spherical particle releasing products of a chemical reaction – a constant flux motor – is also considered.

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12

Räisänen, Petri, Risto Makkonen, Alf Kirkevåg, and Jens B. Debernard. "Effects of snow grain shape on climate simulations: sensitivity tests with the Norwegian Earth System Model." Cryosphere 11, no. 6 (December 13, 2017): 2919–42. http://dx.doi.org/10.5194/tc-11-2919-2017.

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Abstract. Snow consists of non-spherical grains of various shapes and sizes. Still, in radiative transfer calculations, snow grains are often treated as spherical. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this study, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of three non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (0.77–0.78 in the visible region) than in the spherical case ( ≈ 0.89). Therefore, for the same effective snow grain size (or equivalently, the same specific projected area), the snow broadband albedo is higher when assuming non-spherical rather than spherical snow grains, typically by 0.02–0.03. Considering the spherical case as the baseline, this results in an instantaneous negative change in net shortwave radiation with a global-mean top-of-the-model value of ca. −0.22 W m−2. Although this global-mean radiative effect is rather modest, the impacts on the climate simulated by NorESM are substantial. The global annual-mean 2 m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further demonstrated that the effect of snow grain shape could be largely offset by adjusting the snow grain size. When assuming non-spherical snow grains with the parameterized grain size increased by ca. 70 %, the climatic differences to the SPH experiment become very small. Finally, the impact of assumed snow grain shape on the radiative effects of absorbing aerosols in snow is discussed.

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13

Yi, Song Lin, Zhi Ming Wang, Xian Zhong Yi, Wen Ni Wan, and Hai Ying Qi. "Shape Description and Sedimentation Characteristics of Non Spherical Regular Particles." Applied Mechanics and Materials 316-317 (April 2013): 1083–86. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.1083.

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The research progress on settling characteristics of non-spherical particles is summarized. Three new filling coefficients in three directions of cuboid are defined. Combining with the existing parameters, a new mathematical model of drag coefficient CD is proposed that using six variables describes the shape information of arbitrary shape particles. This equation is derived and shows reasonable accuracy with the error being less than 1%.

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14

Cour-Palais, Burton G. "The shape effect of non-spherical projectiles in hypervelocity impacts." International Journal of Impact Engineering 26, no. 1-10 (December 2001): 129–43. http://dx.doi.org/10.1016/s0734-743x(01)00075-6.

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15

Mukhina, Ksenia D., and Sergey A. Chivilikhin. "The influence of non-spherical nanoparticles’ shape on sedimentation process." Journal of Physics: Conference Series 741 (August 2016): 012181. http://dx.doi.org/10.1088/1742-6596/741/1/012181.

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16

Brzobohatý, Oto, Martin Šiler, Jan Trojek, Lukáš Chvátal, Vítězslav Karásek, and Pavel Zemánek. "Non-spherical gold nanoparticles trapped in optical tweezers: shape matters." Optics Express 23, no. 7 (March 23, 2015): 8179. http://dx.doi.org/10.1364/oe.23.008179.

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17

Carpenter, J. D., R. J. Gowland, B. Wilshire, and J. M. Clark. "Non-spherical particles for assessment of aerosol shape analysis systems." Journal of Aerosol Science 23 (January 1992): 205–8. http://dx.doi.org/10.1016/0021-8502(92)90385-9.

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18

Yu, Qingfen, Sameh Othman, Sabyasachi Dasgupta, Thorsten Auth, and Gerhard Gompper. "Nanoparticle wrapping at small non-spherical vesicles: curvatures at play." Nanoscale 10, no. 14 (2018): 6445–58. http://dx.doi.org/10.1039/c7nr08856f.

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Wrapping of nanoparticles that enter and exit vesicles depends on several important parameters, such as particle size and shape, vesicle size and reduced volume, and membrane spontaneous curvature. This implies complex wrapping behavior where particle wrapping transitions and vesicle shape transitions are intimately coupled.

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19

Gialitaki, Anna, Alexandra Tsekeri, Vassilis Amiridis, Romain Ceolato, Lucas Paulien, Emmanouil Proestakis, Eleni Marinou, Moritz Haarig, Holger Baars, and Dimitris Balis. "Is Near-Spherical Shape “the New Black” for Smoke ?" EPJ Web of Conferences 237 (2020): 02017. http://dx.doi.org/10.1051/epjconf/202023702017.

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We present smoke lidar measurements from the Canadian fires of 2017. The advected smoke layers over Europe are detected at both tropospheric and stratospheric heights, with the latter presenting non-typical values of the Particle Linear Depolarization Ratio (PLDR) with strong wavelength dependence from the UV to the Near-IR. Specifically, the PLDR values are of the order of 22, 18 and 4% at 355, 532 and 1064 nm respectively. In an attempt to interpret these results, we apply the hypothesis that smoke particles have near-spherical shapes. Scattering calculations with the T-matrix code support other findings in the literature ([1]- [2]), showing that the near-spherical shape (or closely similar shapes as in [2]), is the only shape that has been shown to reproduce the observed PLDR and Lidar Ratio (LR) values of the stratospheric smoke particles at the three measurement wavelengths.

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20

Gao, Lei, and Yu Ma. "Enhanced group velocity in composite media of particles with non-spherical shape or shape distribution." Journal of Physics A: Mathematical and General 38, no. 35 (August 16, 2005): 7765–71. http://dx.doi.org/10.1088/0305-4470/38/35/010.

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21

Tseng, Lin Yu, and Shiueng Bien Yang. "A genetic clustering algorithm for data with non-spherical-shape clusters." Pattern Recognition 33, no. 7 (July 2000): 1251–59. http://dx.doi.org/10.1016/s0031-3203(99)00105-3.

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22

Toyama, Shigeki, Tsutomu Aragaki, Kazunori Murase, and Mitsunori Kishi. "Shape coefficient of a non-spherical particle to characterize heat transfer." Advanced Powder Technology 1, no. 1 (1990): 13–24. http://dx.doi.org/10.1016/s0921-8831(08)60724-4.

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23

Loth, E. "Drag of non-spherical solid particles of regular and irregular shape." Powder Technology 182, no. 3 (March 2008): 342–53. http://dx.doi.org/10.1016/j.powtec.2007.06.001.

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24

Chen, Lu Min, Qi Lin, and Zhi Zhong Zhu. "Simulation and Analysis of Attitude of Non-Spherical Particles in Drum Granulation." Advanced Materials Research 889-890 (February 2014): 170–73. http://dx.doi.org/10.4028/www.scientific.net/amr.889-890.170.

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The process of drum granulation is forming agglomerate by infiltrating liquid or binder into solid fine powder to produce bond force. Seed particles present different shapes features in granulation process. Different shapes of particles will have different movement trajectory and attitude under the condition of different location or rotational speed in the cylinder. The motion pose of different shape particles are analyzed by the simulation method using discrete element method, this way is better for us to control the time of powder in different drum position and frequency of adding powders per time. Research provides the theoretical basis on regulatory means and control parameters for adding powders and guarantee the production efficiency.

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25

Liang, Heng Chang, Guo Qing Zhou, and Xiang Yu Shang. "Elasto-Plastic Numerical Analysis on Elliptic Cavity Expansion under Uniform Pressure." Advanced Materials Research 243-249 (May 2011): 2162–66. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2162.

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Analysis of the expansion of cylindrical and spherical cavities in soil and rock provides a versatile and accurate geomechanics approach for study of important problems in geotechnical engineering. As the method getting more important, the analysis of non-circular shape cavity is becoming significance. The paper has investigated the cavity wall shape varying characteristic and elasto-plastic distribution of stress of elliptic shape cavity under internal uniform pressure during the expansion period through ABAQUS FEM numerical. It pointed that the elliptic cavity wall will tend to circle shape as the internal uniform pressure increasing. It also gain that the elasto-plastic distribution around the elliptic cavity is bigger than spherical cavity’s and smaller than spherical cavity’s when material and pressure are same . The stress characters and the cavity wall transfiguration result is useful for estimate non-circular shape cavity expansion.

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26

Hao, Nanjing, Laifeng Li, and Fangqiong Tang. "Shape matters when engineering mesoporous silica-based nanomedicines." Biomaterials Science 4, no. 4 (2016): 575–91. http://dx.doi.org/10.1039/c5bm00589b.

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27

Ijaz, N., Ahmed Zeeshan, and S. U. Rehman. "Effect of electro-osmosis and mixed convection on nano-bio-fluid with non-spherical particles in a curved channel." Mechanics & Industry 19, no. 1 (2018): 108. http://dx.doi.org/10.1051/meca/2017040.

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This paper resigns to study effects of electro-kinetic force due to presence of electrical charge layer on the walls of the channel. The nano-bio-fluid fills the void between two concentric curved plates. The flow is induced due to peristaltic wave on flexible walls. The effects of mixed convection along with heat transfer are accounted. Furthermore, the focus is on effects of shapes of non-spherical nanoparticles in nano-bio-fluid and its effects on the flow. Nanofluids are important in treatment of cancer and other diseases in tissues which are normally not reachable by normal drug procedures. The problem is modeled for four types of non-spherical nanoparticles of alumina in aqueous base fluid. Numerical solution is obtained using Mathematica. Some important results are displaced through graphs. Empirical observations display that a significantly greater velocity for nanofluid with blade shape particles is offered followed by brick shaped particles. Numerical experiment also deems a rise in heat transfer due to presence of blade shapes particles.

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28

Bobbi, Elena, Bassem Sabagh, Sally-Ann Cryan, James A. Wilson, and Andreas Heise. "Anisotropic polymer nanoparticles with solvent and temperature dependent shape and size from triblock copolymers." Polymer Chemistry 10, no. 25 (2019): 3436–43. http://dx.doi.org/10.1039/c9py00363k.

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29

Friess, Fabian, Christian Wischke, and Andreas Lendlein. "Microscopic analysis of shape-shiftable oligo(ε-caprolactone) - based particles." MRS Advances 4, no. 59-60 (2019): 3199–206. http://dx.doi.org/10.1557/adv.2019.392.

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ABSTRACTSpherical particles are routinely monitored and described by hydrodynamic diameters determined, e.g., by light scattering techniques. Non-spherical particles such as prolate ellipsoids require alternative techniques to characterize particle size as well as particle shape. In this study, oligo(ε-caprolactone) (oCL) based micronetwork (MN) particles with a shape-shifting function based on their shape-memory capability were programmed from spherical to prolate ellipsoidal shape aided by incorporation and stretching in a water-soluble phantom matrix. By applying light microscopy with automated contour detection and aspect ratio analysis, differences in characteristic aspect ratio distributions of non-crosslinked microparticles (MPs) and crosslinked MNs were detected when the degrees of phantom elongation (30-290%) are increased. The thermally induced shape recovery of programmed MNs starts in the body rather than from the tips of ellipsoids, which may be explained based on local differences in micronetwork deformation. By this approach, fascinating intermediate particle shapes with round bodies and two opposite sharp tips can be obtained, which could be of interest, e.g., in valves or other technical devices, in which the tips allow to temporarily encage the switchable particle in the desired position.

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30

Nader, François, Patrick Pizette, Nicolin Govender, Daniel N. Wilke, and Jean-François Ferellec. "Modelling realistic ballast shape to study the lateral pull behaviour using GPU computing." EPJ Web of Conferences 249 (2021): 06003. http://dx.doi.org/10.1051/epjconf/202124906003.

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The use of the Discrete Element Method to model engineering structures implementing granular materials has proven to be an efficient method to response under various behaviour conditions. However, the computational cost of the simulations increases rapidly, as the number of particles and particle shape complexity increases. An affordable solution to render problems computationally tractable is to use graphical processing units (GPU) for computing. Modern GPUs offer up 10496 compute cores, which allows for a greater parallelisation relative to 32-cores offered by high-end Central Processing Unit (CPU) compute. This study outlines the application of BlazeDEM-GPU, using an RTX 2080Ti GPU (4352 cores), to investigate the influence of the modelling of particle shape on the lateral pull behaviour of granular ballast systems used in railway applications. The idea is to validate the model and show the benefits of simulating non-spherical shapes in future large-scale tests. The algorithm, created to generate the shape of the ballast based on real grain scans, and using polyhedral shape approximations of varying degrees of complexity is shown. The particle size is modelled to scale. A preliminary investigation of the effect of the grain shape is conducted, where a sleeper lateral pull test is carried out in a spherical grains sample, and a cubic grains sample. Preliminary results show that elementary polyhedral shape representations (cubic) recreate some of the characteristic responses in the lateral pull test, such as stick/slip phenomena and force chain distributions, which looks promising for future works on railway simulations. These responses that cannot be recreated with simple spherical grains, unless heuristics are added, which requires additional calibration and approximations. The significant reduction in time when using non-spherical grains also implies that larger granular systems can be investigated.

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Yuan, Ye, Wei Deng, and Shuixiang Li. "Structural universality in disordered packings with size and shape polydispersity." Soft Matter 16, no. 18 (2020): 4528–39. http://dx.doi.org/10.1039/d0sm00110d.

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32

Song, Zi Biao, Chun Ge, Shu Xiong Zhang, and Xiao Lu Wu. "Mathematical Model Studies on Dispersion of Fine Non-Spherical Particles in Enclosed Spaces." Advanced Materials Research 756-759 (September 2013): 4699–702. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4699.

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Study on the fine particle dispersion in the room is very important for creating and maintaining a healthy indoor environment. The paper presented a new dispersion model of fine non-spherical particles formulated in a Lagrangian way based on its dynamic characteristics. In this model, the effects of gravity, resistance, particles shape and random force were taken into account. The influences of gravity and non-spherical particles shape on its dispersion process were analyzed in theory. Simulation result and theory analysis showed the models established in the paper performed better than the random walk model.

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33

Kirchschlager, Florian, and Gesa H. M. Bertrang. "Self-scattering of non-spherical dust grains." Astronomy & Astrophysics 638 (June 2020): A116. http://dx.doi.org/10.1051/0004-6361/202037943.

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Context. The understanding of (sub-)millimetre polarisation has made a leap forward since high-resolution imaging with the Atacama Large (sub-)Mm Array (ALMA) became available. Amongst other effects, self-scattering (i.e. the scattering of thermal dust emission on other grains) is thought to be the origin of millimetre polarisation. This opens the first window to a direct measurement of dust grain sizes in regions of optically thick continuum emission as it can be found in protoplanetary discs and star-forming regions. However, the newly derived values of grain sizes are usually around ~100 μm and thus one order of magnitude smaller than those obtained from more indirect measurements, as well as those expected from theory (~1 mm). Aims. We see the origin of this contradiction in the applied dust model of current self-scattering simulations: a perfect compact sphere. The aim of this study is to test our hypothesis by investigating the impact of non-spherical grain shapes on the self-scattering signal. Methods. We applied discrete dipole approximation simulations to investigate the influence of the grain shape on self-scattering polarisation in three scenarios: an unpolarised and polarised incoming wave under a fixed and a varying incident polarisation angle. Results. We find significant deviations of the resulting self-scattering polarisation when comparing non-spherical to spherical grains. In particular, tremendous deviations are found for the polarisation signal of grains when observed outside the Rayleigh regime, that is for >100 μm sized grains observed at the 870 μm wavelength. Self-scattering by oblate grains produces higher polarisation degrees compared to spheres, which challenges the interpretation of the origin of observed millimetre polarisation. A (nearly) perfect alignment of the non-spherical grains is required to account for the observed millimetre polarisation in protoplanetary discs. Furthermore, we find conditions under which the emerging scattering polarisation of non-spherical grains is flipped in orientation by 90°. Conclusions. These results show clearly that the perfect compact sphere is an oversimplified model, which has reached its limit. Our findings point towards a necessary re-evaluation of the dust grain sizes derived from (sub-)millimetre polarisation.

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Chen, Jian, Dominik Krengel, and Hans-Georg Matuttis. "Experimental study of particle shape dependence of avalanches inside a rotating drum." EPJ Web of Conferences 249 (2021): 06001. http://dx.doi.org/10.1051/epjconf/202124906001.

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We investigate the avalanches of spherical and non-spherical granular particles inside half-filled rotating drums. The time series of the center of gravity of the particle assemblies are obtained via image analysis and their single-sided amplitude (SSA) spectra are analyzed. The spectra features of this new indicator turn out to be characteristic for the avalanches, in terms of the existence of peaks in the low-frequency range and the decay rate of high frequency components. The SSA spectrum has a peak for the packings of non-spherical particles but not for the spherical particles. The high frequency part is characterized by a power law decay 1/ f a (a > 0) . A 1/ f -decay is found only for the spherical particles. For the packings of cornered particles, the exponents significantly deviate from a = 1. As 1/ f spectra are often associated with self-organized criticality and therefore a scale invariance of the dynamics, we may conclude that there is no scale-invariant structure for granular avalanches. Considering the small number of particles and the regularity of convex particle shapes being used, the spectral features revealed in this study could be utilized for validating particle simulations.

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35

Gustafsson, Mats, Christian Sohl, and Gerhard Kristensson. "Physical limitations on antennas of arbitrary shape." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 463, no. 2086 (July 18, 2007): 2589–607. http://dx.doi.org/10.1098/rspa.2007.1893.

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In this paper, physical limitations on bandwidth, realized gain, Q -factor and directivity are derived for antennas of arbitrary shape. The product of bandwidth and realizable gain is shown to be bounded from above by the eigenvalues of the long-wavelength, high-contrast polarizability dyadics. These dyadics are proportional to the antenna volume and are easily determined for an arbitrary geometry. Ellipsoidal antenna volumes are analysed in detail, and numerical results for some generic geometries are presented. The theory is verified against the classical Chu limitations for spherical geometries and shown to yield sharper bounds for the ratio of the directivity and the Q -factor for non-spherical geometries.

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Mills, O. P., W. I. Rose, and C. M. Riley. "Measurements of Fine Volcanic ASH Via Stereoscopy in the Scanning Electron Microscope." Microscopy and Microanalysis 4, S2 (July 1998): 502–3. http://dx.doi.org/10.1017/s1431927600022637.

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Volcanic eruptions inject tons of silicic material into the atmosphere. Large, dense material falls out within a few hours whereas fine size fractions, < 10 μm radius ash, may remain airborne for weeks to months. Protection of human population centers and aircraft requires predictive atmospheric transport models. Many of these models assume the ash particles are spherical but abundant qualitative studies of ash particles demonstrate irregular shapes ranging from parachute-like bubble-wall shards to polygonal shaped mineral grains. These non-spherical shapes increase atmospheric drag. The accuracy of transport models may be improved with a better understanding of the actual shapes found in fine ash particles. Therefore, the objective of this study is to accurately determine three-dimensional shape measurements via stereoscopic methods using the scanning electron microscope.The scanning electron microscope is an ideal imaging platform for collection of stereo pairs because of its utility in stereoscopic height measurement.

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Pozrikidis, C. "Inviscid drops with internal circulation." Journal of Fluid Mechanics 209 (December 1989): 77–92. http://dx.doi.org/10.1017/s0022112089003046.

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The shape of a moving inviscid axisymmetric drop is considered as a function of surface tension and of the intensity of the internal circulation. In a frame of reference moving with the drop, the drop is modelled as a region of diffused vorticity which is bounded by a vortex sheet, and is imbedded in streaming flow. First, an asymptotic analysis is performed for a slightly non-spherical drop whose circulation is very close to that required for the spherical shape. The results indicate that steady drop shapes may exist at all but a number of distinct values of the Weber number, the lowest two of which are 4.41 and 6.15. For highly deformed drops, the problem is formulated as an integral equation for the shape of the drop, and for the strength of the bounding vortex sheet. A numerical procedure is developed for solving this equation, and numerical calculations are performed for Weber numbers between 0 and 4.41. Limiting members in the computed family of solutions contain spherical drops, and inviscid bubbles with vanishing circulation. Computed new shapes include saucer-like shapes with a rounded main body and an elongated tip. The relationship between inviscid drops and drops moving at large Reynolds numbers is discussed.

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Guédra, Matthieu, and Claude Inserra. "Bubble shape oscillations of finite amplitude." Journal of Fluid Mechanics 857 (October 25, 2018): 681–703. http://dx.doi.org/10.1017/jfm.2018.768.

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Shape oscillations arising from the spherical instability of an oscillating bubble can be sustained in a stationary acoustic field. Describing such a steady state requires that nonlinear saturation effects are accounted for to counteract the natural exponential growth of the instability. In this paper, we analyse the establishment of finite-amplitude bubble shape oscillations as a consequence of nonlinear interactions between spherical and non-spherical modes. The set of coupled dynamical equations describing the volume pulsation and the shape oscillations is solved using a perturbation technique based on the Krylov–Bogoliubov method of averaging. A set of first-order differential equations governing the slowly varying amplitudes and phases of the different modes allows us to reproduce the exponential growth and subsequent nonlinear saturation of the most unstable, parametrically excited, shape mode. Solving these equations for steady-state conditions leads to analytical expressions of the modal amplitudes and derivations of the conditionally stable and absolutely stable thresholds for shape oscillations. The analysis of the solutions reveals the existence of a hysteretic behaviour, indicating that bubble shape oscillations could be sustained for acoustic pressures below the classical parametric threshold.

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Chocolatl Torres, Misael, Sylvain Bernès, and Ulises Salazar Kuri. "Refinement of K[HgI3]·H2O using non-spherical atomic form factors." Acta Crystallographica Section E Crystallographic Communications 77, no. 7 (June 4, 2021): 681–85. http://dx.doi.org/10.1107/s2056989021005582.

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The crystal structure model for potassium triiodidomercurate(II) monohydrate, K[HgI3]·H2O, based on single-crystal data, was reported 50 years ago [Nyqvist & Johansson (1971). Acta Chem. Scand. 25, 1615–1629]. We have now redetermined this structure with X-ray diffraction data at 0.70 Å resolution collected at 153 K using Ag Kα radiation. Combined quantum mechanical methods (ORCA) and computation of non-spherical scattering form factors (NoSpherA2) allowed the refinement of the shape of the water molecule with anisotropic H atoms, despite the presence of heavy elements in the crystal. The refined shape of the water molecule via this Hirshfeld refinement is close to that determined for liquid water by neutron diffraction experiments. Moreover, the Laplacian of the electron density clearly shows how electron density accumulates along the O—H σ-valence bonds in the water molecule.

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Kim, Ki Woong, Yong Ho Lee, and Sung Won Park. "Performance of Signal Space Separation Depending on Sensor Array Arrangement in Biomagnetic Measurements." Key Engineering Materials 480-481 (June 2011): 1418–25. http://dx.doi.org/10.4028/www.scientific.net/kem.480-481.1418.

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Signal source separation (SSS) has widely been adopted for magnetoencephalography (MEG) to reduce external magnetic noise interference. The basic idea of SSS is based on decomposing measured fields into spherical harmonic bases. Due to the feature, the performance of SSS strongly depends on the shape of a measuring sensor array. In this article, we show the noise reduction performances in several different shapes of the sensor and array and demonstrate SSS is only effective for a non-spherical sensor array or for a gradiometric arrangement.

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Sivak, J. G. "Shape and focal properties of the cephalopod ocular lens." Canadian Journal of Zoology 69, no. 10 (October 1, 1991): 2501–6. http://dx.doi.org/10.1139/z91-354.

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The shape and focal properties (spherical aberration) of lenses from the eyes of three cephalopod species, the cuttlefish Rosia pacifica, the squid Loligo opalescens, and the octopus Octopus dofleini, were measured and compared with descriptions of teleost lenses. The method used involved photographing the refractive effect of lenses in solution on an array of fine parallel helium–neon laser beams. Though the cephalopod lenses approach the sphericity characteristic of teleost lenses, the equatorial lens diameter is somewhat greater (2.3–10.5% in Loligo) than the axial diameter. Spherical aberration of the lens is largely neutralized, indicating the existence of a gradient refractive index. However, the lenses show some non-monotonic variation in focal length with distance from the centre of the lens. The ability of the cephalopods to control pupil size may minimize the need to control spherical aberration.

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Schneiders, Lennart, Konstantin Fröhlich, Matthias Meinke, and Wolfgang Schröder. "The decay of isotropic turbulence carrying non-spherical finite-size particles." Journal of Fluid Mechanics 875 (July 22, 2019): 520–42. http://dx.doi.org/10.1017/jfm.2019.516.

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Direct particle–fluid simulations of heavy spheres and ellipsoids interacting with decaying isotropic turbulence are conducted. This is the rigorous extension of the spherical particle analysis in Schneiders et al. (J. Fluid Mech., vol. 819, 2017, pp. 188–227) to $O(10^{4})$ non-spherical particles. To the best of the authors’ knowledge, this represents the first particle-resolved study on turbulence modulation by non-spherical particles of near-Kolmogorov-scale size. The modulation of the turbulent flow is precisely captured by explicitly resolving the stresses acting on the fluid–particle interfaces. The decay rates of the fluid and particle kinetic energy are found to increase with the particle aspect ratio. This is due to the particle-induced dissipation rate and the direct transfer of kinetic energy, both of which can be substantially larger than for spherical particles depending on the particle orientation. The extra dissipation rate resulting from the translational and rotational particle motion is quantified to detail the impact of the particles on the fluid kinetic energy budget and the influence of the particle shape. It is demonstrated that the previously derived analytical model for the particle-induced dissipation rate of smaller particles is valid for the present cases albeit these involve significant finite-size effects. This generic expression allows us to assess the impact of individual inertial particles on the local energy balance independent of the particle shape and to quantify the share of the rotational particle motion in the kinetic energy budget. To enable the examination of this mechanistic model in particle-resolved simulations, a method is proposed to reconstruct the so-called undisturbed fluid velocity and fluid rotation rate close to a particle. The accuracy and robustness of the scheme are corroborated via a parameter study. The subsequent discussion emphasizes the necessity to account for the orientation-dependent drag and torque in Lagrangian point-particle models, including corrections for finite particle Reynolds numbers, to reproduce the local and global energy balance of the multiphase system.

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Yan, Sheng-Nan, Tian-Yu Wang, Tian-Qi Tang, An-Xing Ren, and Yu-Rong He. "Simulation on hydrodynamics of non-spherical particulate system using a drag coefficient correlation based on artificial neural network." Petroleum Science 17, no. 2 (December 24, 2019): 537–55. http://dx.doi.org/10.1007/s12182-019-00411-2.

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AbstractFluidization of non-spherical particles is very common in petroleum engineering. Understanding the complex phenomenon of non-spherical particle flow is of great significance. In this paper, coupled with two-fluid model, the drag coefficient correlation based on artificial neural network was applied in the simulations of a bubbling fluidized bed filled with non-spherical particles. The simulation results were compared with the experimental data from the literature. Good agreement between the experimental data and the simulation results reveals that the modified drag model can accurately capture the interaction between the gas phase and solid phase. Then, several cases of different particles, including tetrahedron, cube, and sphere, together with the nylon beads used in the model validation, were employed in the simulations to study the effect of particle shape on the flow behaviors in the bubbling fluidized bed. Particle shape affects the hydrodynamics of non-spherical particles mainly on microscale. This work can be a basis and reference for the utilization of artificial neural network in the investigation of drag coefficient correlation in the dense gas–solid two-phase flow. Moreover, the proposed drag coefficient correlation provides one more option when investigating the hydrodynamics of non-spherical particles in the gas–solid fluidized bed.

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Singh, Madan, Benedict Molibeli Taele, and Ghanshyam Patel. "Effect of Shape and Size on Curie Temperature, Debye Frequency, Melting Entropy and Enthalpy of Nanosolids." Oriental Journal of Chemistry 34, no. 5 (October 18, 2018): 2282–91. http://dx.doi.org/10.13005/ojc/340508.

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The shape and size dependent melting thermodynamics of metallic nanoparticles are predicted by application of bond theory model, free of any adjustable parameter. Thermodynamic properties like Debye frequency, Curie temperature, melting entropy and enthalpy of Al, Sn, In, Cu, β-Fe and Fe3O4 for spherical and non spherical shapes nanoparticles with different size have been studied. In this model, the effects of relaxation factor for the low dimension solids are considered. The depression in Debye frequency, Curie temperature, melting entropy and enthalpy is predicted. The model predictions are supported by the available experimental and simulation results.

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Garcia, Elena A., Hanying Luo, Courtney E. Mack, and Margarita Herrera-Alonso. "Effect of side-chain length on solute encapsulation by amphiphilic heterografted brush copolymers." Soft Matter 16, no. 38 (2020): 8871–76. http://dx.doi.org/10.1039/d0sm01190h.

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46

Li, Ming Qi, and Hui Su Chen. "Misestimation of the ITZ Thickness around Non-Spherical Aggregates." Materials Science Forum 1036 (June 29, 2021): 432–41. http://dx.doi.org/10.4028/www.scientific.net/msf.1036.432.

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The ITZ (interfacial transition zone) in concrete has very high porosity and permeability, which affects concrete’s macroscopic mechanical properties and transport properties. Two-dimensional (2D) areal analysis and one-dimensional (1D) linear analysis are usually used to study ITZ’s microstructure. However, 3D microstructure is difficult to be characterized by 1D and 2D information. For example, 2D cross-section planes do not always intercept both the ITZ and the corresponding aggregate, which causes some ITZ regions are ignored by researchers. Therefore, ITZ’s volume and thickness will be misestimated, and leads to the misestimation of the diffusivity. In this paper, the effect of aggregate’s shape on the misestimation of ITZ thickness t is studied. The results reveal that the misestimation increases with the increasing sphericity s of aggregates.

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Little, Christopher A., Christopher Batchelor-McAuley, Neil P. Young, and Richard G. Compton. "Shape and size of non-spherical silver nanoparticles: implications for calculating nanoparticle number concentrations." Nanoscale 10, no. 34 (2018): 15943–47. http://dx.doi.org/10.1039/c8nr06062b.

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Clerici, Davide, Francesco Mocera, and Aurelio Somà. "Shape Influence of Active Material Micro-Structure on Diffusion and Contact Stress in Lithium-Ion Batteries." Energies 14, no. 1 (December 29, 2020): 134. http://dx.doi.org/10.3390/en14010134.

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Electrochemical-mechanical modelling is a key issue to estimate the damage of active material, as direct measurements cannot be performed due to the particles nanoscale. The aim of this paper is to overcome the common assumptions of spherical and standalone particle, proposing a general approach that considers a parametrized particle shape and studying its influence on the mechanical stresses which arise in active material particles during battery operation. The shape considered is a set of ellipsoids with variable aspect ratio (elongation), which aims to approximate real active material particles. Active material particle is divided in two domains: non-contact domain and contact domain, whether contact with neighbouring particles affects stress distribution or not. Non-contact areas are affected by diffusion stress, caused by lithium concentration gradient inside particles. Contact areas are affected simultaneously by diffusion stress and contact stress, caused by contact with neighbouring particles as a result of particle expansion due to lithium insertion. A finite element model is developed in Ansys™APDL to perform the multi-physics computation in non-spherical domain. The finite element model is validated in the spherical case by analytical models of diffusion and contact available for simple geometry. Then, the shape factor is derived to describe how particle shape affects mechanical stress in non-contact and contact domains.

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Liu, L. X., and J. D. Litster. "The effect of particle shape on the spouting properties of non-spherical particles." Powder Technology 66, no. 1 (April 1991): 59–67. http://dx.doi.org/10.1016/0032-5910(91)80082-t.

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50

Abou-Chakra, H., J. Baxter, and U. Tüzün. "Three-dimensional particle shape descriptors for computer simulation of non-spherical particulate assemblies." Advanced Powder Technology 15, no. 1 (2004): 63–77. http://dx.doi.org/10.1163/15685520460740070.

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