scholarly journals Effect of Particle Size Distributions and Shapes on the Failure Behavior of Dry Coke Aggregates

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5558
Author(s):  
Alireza Sadeghi-Chahardeh ◽  
Roozbeh Mollaabbasi ◽  
Donald Picard ◽  
Seyed Mohammad Taghavi ◽  
Houshang Alamdari
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Rolling Resistance ◽  
Structural Defects ◽  
Failure Behavior ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Resistance Model ◽  
The Stability ◽  
Carbon Anodes

Carbon anodes participate in chemical reactions to reduce alumina in the Hall–Héroult process, of which coke aggregates make up a major part. The failure analysis of coke aggregates not only leads to a better understanding of the deformation mechanisms of anode paste under compressive loading but also can identify potential causes of structural defects in carbon anodes, such as horizontal cracks. The coke aggregates are composed of particles with different size distributions and shapes, which may strongly affect the failure behavior of the anode during compaction. In this paper, the effects of particle size distributions and shapes on the mechanical behavior and the failure of coke aggregates are investigated using the discrete element method modeling technique. The numerical results reveal that, although the mechanical behavior of coke mixtures is generally dependent on larger particles, the presence of fine particles in the coke aggregates reduces fluctuations in the stress–strain diagram. In addition, the rolling resistance model is employed as a parameter representing the effect of particle shape. It is shown that the rolling resistance model can be an alternative to the overlapped spheres model, which has a higher computational cost than the rolling resistance model. The second-order work criterion is used to evaluate the stability of the coke aggregates, the results of which indicate that the addition of fine particles as well as increasing the rolling resistance between the particles increases the stability range of the coke aggregates. Moreover, by using the analysis of micro-strain contour evaluations during the compaction process, it is shown that, both by adding fine particles to the coke mixture and by increasing the rolling resistance between the particles, the possibility of creating a compression band in the coke aggregates is reduced. Since the presence of the compaction bands in the anode paste creates an area prone to horizontal crack generations, the results of this study could lead to the production of carbon anodes with fewer structural defects.

scholarly journals A sample formation procedure to obtain homogeneous post-erosion particle size distribution

2019 ◽  
Vol 92 ◽  
pp. 02015
Author(s):  
Shijin Li ◽  
Adrian R. Russell
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Internal Erosion ◽  
Triaxial Tests ◽  
Experimental Investigations ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
The Matrix ◽  
Homogeneous Particle ◽  
Coarse Soil

Internal erosion (suffusion) is caused by water seeping through the matrix of coarse soil and progressively transporting out fine particles. The mechanical strength of soils within water retaining structures may be affected after internal erosion occurs. However, most experimental investigations on the mechanical consequences of internal erosion have used triaxial tests on samples having nonhomogeneous particle size distributions along their lengths. Such nonhomogeneities arise from the most commonly used sample formation procedure, in which seeping water enters one end of a sample and washes fine particles out the other. In this paper a new soil sample formation procedure is presented which results in homogeneous particle size distributions along the direction of seepage, that is at all locations along a sample's length.

scholarly journals Dust Particle Size Distributions during Spring in Yinchuan, China

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Jiangfeng Shao ◽  
Jiandong Mao
Keyword(s):  
Particle Size ◽  
Wind Speed ◽  
Dust Particle ◽  
Dust Storm ◽  
Fine Particles ◽  
Dust Particles ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Mass Distributions ◽  
Mass Size

Dust particle size distributions in Yinchuan, China, were measured during March and April 2014, using APS-3321 sampler. The distributions were measured under different dust conditions (background, floating dust, blowing dust, and dust storm) and statistical analyses were performed. The results showed that, under different dust conditions, the instantaneous number concentrations of dust particles differed widely. For example, during blowing sand and dust storm conditions, instantaneous dust particles concentrations varied substantially, while, under floating dust conditions, concentration differences were relatively small. The average dust particles size distributions were unimodal under all dust conditions, but the average surface area and mass size distributions were all bimodal. These distributions had peaks in different locations under different dust conditions. Under different dust conditions, wind speed and humidity were very important factors for particles size distributions. With increasing wind speed and decreasing humidity, fine particles were dominant in the atmosphere and the number and mass distributions of the coarse particles were indicative of long-range transport from surrounding deserts. Different dust conditions had different influences on PM1, PM2.5, and PM10concentrations.

Influence of particle-size distribution homogeneity on shearing of soils subjected to internal erosion

2020 ◽  
Vol 57 (11) ◽  
pp. 1684-1694
Author(s):  
Shijin Li ◽  
Adrian R. Russell ◽  
David Muir Wood
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Soil Sample ◽  
Size Distribution ◽  
Fine Particles ◽  
Internal Erosion ◽  
Triaxial Tests ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Homogeneous Particle

Internal erosion (suffusion) is caused by water seeping through the matrix of coarse soil and progressively transporting out fine particles. The mechanical strength and stress–strain behavior of soils within water-retaining structures may be affected by internal erosion. Some researchers have set out to conduct triaxial erosion tests to study the mechanical consequences of erosion. Prior to conducting a triaxial test they subject a soil sample, which has an initially homogeneous particle-size distribution and density throughout, to erosion by causing water to enter one end of a sample and wash fine particles out the other. The erosion and movement of particles causes heterogeneous particle-size distributions to develop along the sample length. In this paper, a new soil sample formation procedure is presented that results in homogeneous particle-size distributions along the length of an eroded sample. Triaxial tests are conducted on homogeneous samples formed using the new procedure as well as heterogeneous samples created by the more commonly used approach. Results show that samples with homogeneous post-erosion particle-size distributions exhibit slightly higher peak deviator stresses than those that were heterogeneous. The results highlight the importance of ensuring homogeneity of post-erosion particle-size distributions when assessing the mechanical consequences of erosion. Forming samples using the new procedure enables the sample’s response to triaxial loading to be interpreted against a measure of its initially homogenous state.

scholarly journals Size-segregated particle number and mass concentrations from different emission sources in urban Beijing

2020 ◽  
Vol 20 (21) ◽  
pp. 12721-12740
Author(s):  
Jing Cai ◽  
Biwu Chu ◽  
Lei Yao ◽  
Chao Yan ◽  
Liine M. Heikkinen ◽  
...  
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Source Apportionment ◽  
Particle Number ◽  
Fine Particles ◽  
Size Distributions ◽  
Vehicular Emissions ◽  
Particle Size Distributions ◽  
Chemical Fingerprints ◽  
Mass Concentrations

Abstract. Although secondary particulate matter is reported to be the main contributor of PM2.5 during haze in Chinese megacities, primary particle emissions also affect particle concentrations. In order to improve estimates of the contribution of primary sources to the particle number and mass concentrations, we performed source apportionment analyses using both chemical fingerprints and particle size distributions measured at the same site in urban Beijing from April to July 2018. Both methods resolved factors related to primary emissions, including vehicular emissions and cooking emissions, which together make up 76 % and 24 % of total particle number and organic aerosol (OA) mass, respectively. Similar source types, including particles related to vehicular emissions (1.6±1.1 µg m−3; 2.4±1.8×103 cm−3 and 5.5±2.8×103 cm−3 for two traffic-related components), cooking emissions (2.6±1.9 µg m−3 and 5.5±3.3×103 cm−3) and secondary aerosols (51±41 µg m−3 and 4.2±3.0×103 cm−3), were resolved by both methods. Converted mass concentrations from particle size distributions components were comparable with those from chemical fingerprints. Size distribution source apportionment separated vehicular emissions into a component with a mode diameter of 20 nm (“traffic-ultrafine”) and a component with a mode diameter of 100 nm (“traffic-fine”). Consistent with similar day- and nighttime diesel vehicle PM2.5 emissions estimated for the Beijing area, traffic-fine particles, hydrocarbon-like OA (HOA, traffic-related factor resulting from source apportionment using chemical fingerprints) and black carbon (BC) showed similar diurnal patterns, with higher concentrations during the night and morning than during the afternoon when the boundary layer is higher. Traffic-ultrafine particles showed the highest concentrations during the rush-hour period, suggesting a prominent role of local gasoline vehicle emissions. In the absence of new particle formation, our results show that vehicular-related emissions (14 % and 30 % for ultrafine and fine particles, respectively) and cooking-activity-related emissions (32 %) dominate the particle number concentration, while secondary particulate matter (over 80 %) governs PM2.5 mass during the non-heating season in Beijing.

Observations on fresh forage intake, ingesta particle size and nutrient digestibility in four species of macropod

2003 ◽  
Vol 51 (6) ◽  
pp. 627 ◽  
Author(s):  
R. G. Lentle ◽  
I. D. Hume ◽  
K. J. Stafford ◽  
M. Kennedy ◽  
B. P. Springett ◽  
...  
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Tammar Wallaby ◽  
Nutrient Digestibility ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Tooth Morphology ◽  
In The Wild ◽  
Oral Processing ◽  
Free Ranging

The particle-size distributions of the ingesta of the sacciform forestomach in free-ranging animals of a grazing macropod species [Macropus eugenii (tammar wallaby)], a grazer/browser [Macropus parma (parma wallaby)], a browser/grazer [Petrogale penicillata (brush-tailed rock-wallaby)] and a browser [Wallabia bicolor (swamp wallaby)] from Kawau Island, New Zealand, were compared with those of captive animals maintained on a standing ryegrass (Lolium perenne) sward. Nutrient digestibility was also measured in tammar and parma wallabies fed ryegrass or browse, i.e. fresh mahoe (Melicytus ramiflora) and this was related to particle-size distributions of the ingesta.There were significant differences in the particle size distributions of digesta from tammar and parma wallabies in the wild but not in captivity. In free-ranging animals the ingesta from both browsing species, the brush-tailed rock-wallaby and the parma wallaby, contained consistently greater proportions of coarse particles and smaller proportions of fine particles than did those of the tammar wallaby. These differences may be correlated with reported differences in their tooth morphologies. However, the presence of significant differences in particle-size distributions of the digesta between brush-tailed rock-wallabies and parma wallabies when constrained to grass, despite reported similarities in their tooth morphology, suggests that factors other than tooth morphology contribute to differences in the oral processing of food by browsing and grazing macropods. There were greater proportions of grass fragments in the coarse than in the finer fractions of ingesta from free-ranging brush-tailed rock-wallabies, indicating that this species is less effective at chewing grass.There were no overall differences between tammar and parma wallabies in the digestibilities of organic matter, neutral-detergent fibre (NDF) or acid-detergent fibre (ADF) but the NDF and ADF digestibilites of both species increased significantly with increase in the proportion of fine ingesta particles and with increase in mass of fermentative digesta.These findings indicate the importance of oral processing to digestive efficiency in macropods and the relationship between oral processing and tooth morphology.

Late Quaternary Records of the Atmospheric Input of Eolian Dust to the Center of the Chinese Loess Plateau

1994 ◽  
Vol 41 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Xiaoye Zhang ◽  
Zhisheng An ◽  
Tuo Chen ◽  
Guangyu Zhang ◽  
Richard Arimoto ◽  
...  
Keyword(s):  
Particle Size ◽  
Loess Plateau ◽  
Fine Particles ◽  
Late Quaternary ◽  
Chinese Loess Plateau ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Chinese Loess ◽  
Eolian Dust ◽  
The Chinese Loess Plateau

AbstractThe concentrations of 15 elements and mineral grain-size distributions were determined for Late Quaternary loess sediments from the Chinese Loess Plateau. Particle-size distributions of the loess were approximately log-normal for each of three modes (i.e., 0.04 to 1 μm diameter, 2 to 20 μm, and 20 to 200 μm) that integrate the transport and deposition of eolian dust. The mass particle-size distributions of typical crustal elements (Si, Ca, Fe, Ti, K, Mn, and V) in paleosol and loess samples show patterns similar to those of mineral aerosols, but higher concentrations occur in the submicrometer sediment particles. Absolute principal component analysis of the elemental data suggests that the loess can be described in terms of synsedimentary and postdepositional concentration and subvertical migration of CaCO3 and various elements through the deposit. A variety of geochemical indicators in the loess are apparently sensitive to Asian monsoon variations; these include the mass ratio of course to fine particles, the concentration ratios of certain trace elements, the elemental fluxes associated with eolian dust, and the bulk concentration of Ca in the sediments.

INFLUENCE OF PARTICLE SIZE ON THE RHEOLOGICAL PROPERTIES OF MAGNETORHEOLOGICAL SUSPENSIONS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1416-1422 ◽  
Author(s):  
A.-M. TRENDLER ◽  
H. BÖSE
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Yield Stress ◽  
Fine Particles ◽  
Elastic Behavior ◽  
Shear Load ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Magnetorheological Suspensions ◽  
Field Strengths

Magnetorheological suspensions with different particle sizes including bimodal particle size distributions have been rheologically investigated. The results show a continuous decrease in the base viscosity without magnetic field when increasing the ratio of coarse to fine particles, which is in accordance with the observed trend of sedimentation stability of the samples. However, measurements of the shear stress with a rising magnetic flux density demonstrate higher values for MR suspensions with special mixtures of coarse and fine particles indicating a strengthening of the particle interactions in the magnetic field. The change of the viscoelastic properties of the MR suspensions in dependence on the field strength and shear load (amplitude) have been studied with oscillatory experiments. As expected, at low field strengths, the viscous behavior dominates and, at high field strengths, the elastic behavior, but differences in the crossover field strengths between the two regimes occur for the different particle size distributions. The shear load variation also shows differences between the various MR suspensions indicating the highest yield stress for the sample with only fine particles without magnetic field, but the lowest yield stress at moderate field strengths.

scholarly journals Parameters Influencing the Emission of Ultrafine Particles during 3D Printing

2021 ◽  
Vol 18 (21) ◽  
pp. 11670
Author(s):  
Radomír Chýlek ◽  
Libor Kudela ◽  
Jiří Pospíšil ◽  
Ladislav Šnajdárek
Keyword(s):  
Particle Size ◽  
3D Printing ◽  
Experimental Evaluation ◽  
Fine Particle ◽  
Ultrafine Particles ◽  
Fine Particles ◽  
3D Printer ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Printing Method

This paper presents a complex and extensive experimental evaluation of fine particle emissions released by an FDM 3D printer for four of the most common printing materials (ABS, PLA, PET-G, and TPU). These thermoplastic filaments were examined at three printing temperatures within their recommended range. In addition, these measurements were extended using various types of printing nozzles, which influenced the emissions considerably. This research is based on more than a hundred individual measurements for which a standardized printing method was developed. The study presents information about differences between particular printing conditions in terms of the amount of fine particles emitted as well as the particle size distributions during printing periods. This expands existing knowledge about the emission of ultrafine particles during 3D printing, and it can help reduce the emissions of these devices to achieve cleaner and safer 3D printer operations.

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