scholarly journals Optimization of proppant parameters for CBM extraction using hydrofracturing by orthogonal experimental process

2020 ◽  
Vol 17 (3) ◽  
pp. 493-505 ◽  
Author(s):  
Haoze Li ◽  
Bingxiang Huang ◽  
Qingying Cheng ◽  
Xinglong Zhao
Keyword(s):  
Particle Size ◽  
Orthogonal Test ◽  
Coal Mass ◽  
Tensile Fracture ◽  
Experimental Conditions ◽  
Embedded Value ◽  
Fracture Area ◽  
Creep Time ◽  
Experimental Process ◽  
The Impact

Abstract Proppant placement concentration, particle size and creep time are important factors that affect the embedment of proppant into coal. Based on multistage creep, an orthogonal test is conducted, and an optimal proppant scheme for different closure stresses obtained. The results show that with increased proppant placement concentration, the number of coal fractures increases and the elastic modulus of the fracture area decreases. As the proppant particle size decreases, the plasticity of fracture-proppant assemblies increases gradually. The yield limit is highest when the particle size is 20/40 mesh. During the proppant embedding process, localization or uneven distribution of proppant results in tensile stress parallel to the fracture surface, which induces tensile fracture in the coal. In the fracture-proppant assembly areas, proppant fractures are severe and yield lines appear. As proppant concentration increases, more energy is accumulated during the proppant compaction stage, resulting in energy release producing craters and crevasses. The energy released also causes increased stress in the proppant-coal contact area and fracturing to the coal mass. The longer the creep time, the weaker the impact and the smaller is fluctuation. Moreover, we find that the orthogonal test can effectively analyze the importance of each parameter. Proppant placement concentration was found to have the highest influence on the process of proppant embedding into coal, followed by particle size and then time. Under experimental conditions, the lowest proppant-embedded value in coal samples was observed with proppant placement concentration of 2 kg m−2 and particle size of 20/40 mesh.

scholarly journals The Impact of Selected Pretreatment Procedures on Iron Dissolution from Metallic Iron Specimens Used in Water Treatment

2019 ◽  
Vol 11 (3) ◽  
pp. 671 ◽  
Author(s):  
Rui Hu ◽  
Arnaud Ndé-Tchoupé ◽  
Mesia Lufingo ◽  
Minhui Xiao ◽  
Achille Nassi ◽  
...  
Keyword(s):  
Particle Size ◽  
Water Treatment ◽  
Metallic Iron ◽  
Future Research ◽  
Dilute Solution ◽  
Steel Wool ◽  
Experimental Conditions ◽  
Iron Dissolution ◽  
Iron Iron ◽  
The Impact

Studies were undertaken to determine the reasons why published information regarding the efficiency of metallic iron (Fe0) for water treatment is conflicting and even confusing. The reactivity of eight Fe0 materials was characterized by Fe dissolution in a dilute solution of ethylenediaminetetraacetate (Na2–EDTA; 2 mM). Both batch (4 days) and column (100 days) experiments were used. A total of 30 different systems were characterized for the extent of Fe release in EDTA. The effects of Fe0 type (granular iron, iron nails and steel wool) and pretreatment procedure (socking in acetone, EDTA, H2O, HCl and NaCl for 17 h) were assessed. The results roughly show an increased iron dissolution with increasing reactive sites (decreasing particle size: wool > filings > nails), but there were large differences between materials from the same group. The main output of this work is that available results are hardly comparable as they were achieved under very different experimental conditions. A conceptual framework is presented for future research directed towards a more processed understanding.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Ultrafiltration of silica sols

1989 ◽  
Vol 54 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Milan Stakić ◽  
Slobodan Milonjić ◽  
Vladeta Pavasović ◽  
Zoja Ilić
Keyword(s):  
Particle Size ◽  
Silica Particle ◽  
Specific Resistance ◽  
Membrane Surface ◽  
Membrane Resistance ◽  
Experimental Conditions ◽  
Surface Unit ◽  
Silica Sols ◽  
Filtration Flux ◽  
Batch Cell

Ultrafiltration of three laboratory made silica and two commercial silica sols was studied using Amicon YC membrane in a 200 ml capacity batch-cell. The effect of silica particle size, stirring conditions, pressure, pH and silica contents on ultrafiltration was investigated. The results obtained indicate that the smaller particles have, disregarding the stirring conditions, lower filtration flux. The differences observed in filtration flux are more pronounced in the conditions without stirring. The obtained value of the membrane resistance is independent of the conditions investigated (stirring, pressure, pH, silica contents and particle size). The values of the resistance of polarized solids, specific resistance, and the mass of gel per membrane surface unit were calculated for all experimental conditions.

scholarly journals Glucuronides Hydrolysis by Intestinal Microbial β-Glucuronidases (GUS) Is Affected by Sampling, Enzyme Preparation, Buffer pH, and Species

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1043
Author(s):  
Christabel Ebuzoeme ◽  
Imoh Etim ◽  
Autumn Ikimi ◽  
Jamie Song ◽  
Ting Du ◽  
...  
Keyword(s):  
Enzyme Preparation ◽  
Reaction System ◽  
Reaction Rates ◽  
Experimental Conditions ◽  
Model Animal ◽  
Fresh Feces ◽  
Time Buffer ◽  
Exogenous Compounds ◽  
Activity Loss ◽  
The Impact

Glucuronides hydrolysis by intestinal microbial β-Glucuronidases (GUS) is an important procedure for many endogenous and exogenous compounds. The purpose of this study is to determine the impact of experimental conditions on glucuronide hydrolysis by intestinal microbial GUS. Standard probe 4-Nitrophenyl β-D-glucopyranoside (pNPG) and a natural glucuronide wogonoside were used as the model compounds. Feces collection time, buffer conditions, interindividual, and species variations were evaluated by incubating the substrates with enzymes. The relative reaction activity of pNPG, reaction rates, and reaction kinetics for wogonoside were calculated. Fresh feces showed the highest hydrolysis activities. Sonication increased total protein yield during enzyme preparation. The pH of the reaction system increased the activity in 0.69–1.32-fold, 2.9–12.9-fold, and 0.28–1.56-fold for mouse, rat, and human at three different concentrations of wogonoside, respectively. The Vmax for wogonoside hydrolysis was 2.37 ± 0.06, 4.48 ± 0.11, and 5.17 ± 0.16 μmol/min/mg and Km was 6.51 ± 0.71, 3.04 ± 0.34, and 0.34 ± 0.047 μM for mouse, rat, and human, respectively. The inter-individual difference was significant (4–6-fold) using inbred rats as the model animal. Fresh feces should be used to avoid activity loss and sonication should be utilized in enzyme preparation to increase hydrolysis activity. The buffer pH should be appropriate according to the species. Inter-individual and species variations were significant.

scholarly journals Waterfall Algorithm as a tool of investigation the geometrical features of granular porous media

2021 ◽  
Author(s):  
Wojciech Sobieski
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Lattice Boltzmann ◽  
Granular Media ◽  
Density Ratio ◽  
Geometrical Features ◽  
Granular Porous Media ◽  
Collision Density ◽  
Boltzmann Method ◽  
The Impact

AbstractThe paper describes the so-called Waterfall Algorithm, which may be used to calculate a set of parameters characterising the spatial structure of granular porous media, such as shift ratio, collision density ratio, consolidation ratio, path length and minimum tortuosity. The study is performed for 1800 different two-dimensional random pore structures. In each geometry, 100 individual paths are calculated. The impact of porosity and the particle size on the above-mentioned parameters is investigated. It was stated in the paper, that the minimum tortuosity calculated by the Waterfall Algorithm cannot be used directly as a representative tortuosity of pore channels in the Kozeny or the Carman meaning. However, it may be used indirect by making the assumption that a unambiguous relationship between the representative tortuosity and the minimum tortuosity exists. It was also stated, that the new parameters defined in the present study are sensitive on the porosity and the particle size and may be therefore applied as indicators of the geometry structure of granular media. The Waterfall Algorithm is compared with other methods of determining the tortuosity: A-Star Algorithm, Path Searching Algorithm, Random Walk technique, Path Tracking Method and the methodology of calculating the hydraulic tortuosity based on the Lattice Boltzmann Method. A very short calculation time is the main advantage of the Waterfall Algorithm, what meant, that it may be applied in a very large granular porous media.

scholarly journals Linking gas and particle ejection dynamics to boundary conditions in scaled shock-tube experiments

2021 ◽  
Vol 83 (8) ◽  
Author(s):  
Valeria Cigala ◽  
Ulrich Kueppers ◽  
Juan José Peña Fernández ◽  
Donald B. Dingwell
Keyword(s):  
Particle Size ◽  
Shock Tube ◽  
Initial Conditions ◽  
Volcanic Eruptions ◽  
Tube Length ◽  
Experimental Investigations ◽  
Clear Correlation ◽  
Angular Deviation ◽  
Dynamic Nature ◽  
Experimental Conditions

AbstractPredicting the onset, style and duration of explosive volcanic eruptions remains a great challenge. While the fundamental underlying processes are thought to be known, a clear correlation between eruptive features observable above Earth’s surface and conditions and properties in the immediate subsurface is far from complete. Furthermore, the highly dynamic nature and inaccessibility of explosive events means that progress in the field investigation of such events remains slow. Scaled experimental investigations represent an opportunity to study individual volcanic processes separately and, despite their highly dynamic nature, to quantify them systematically. Here, impulsively generated vertical gas-particle jets were generated using rapid decompression shock-tube experiments. The angular deviation from the vertical, defined as the “spreading angle”, has been quantified for gas and particles on both sides of the jets at different time steps using high-speed video analysis. The experimental variables investigated are 1) vent geometry, 2) tube length, 3) particle load, 4) particle size, and 5) temperature. Immediately prior to the first above-vent observations, gas expansion accommodates the initial gas overpressure. All experimental jets inevitably start with a particle-free gas phase (gas-only), which is typically clearly visible due to expansion-induced cooling and condensation. We record that the gas spreading angle is directly influenced by 1) vent geometry and 2) the duration of the initial gas-only phase. After some delay, whose length depends on the experimental conditions, the jet incorporates particles becoming a gas-particle jet. Below we quantify how our experimental conditions affect the temporal evolution of these two phases (gas-only and gas-particle) of each jet. As expected, the gas spreading angle is always at least as large as the particle spreading angle. The latter is positively correlated with particle load and negatively correlated with particle size. Such empirical experimentally derived relationships between the observable features of the gas-particle jets and known initial conditions can serve as input for the parameterisation of equivalent observations at active volcanoes, alleviating the circumstances where an a priori knowledge of magma textures and ascent rate, temperature and gas overpressure and/or the geometry of the shallow plumbing system is typically chronically lacking. The generation of experimental parameterisations raises the possibility that detailed field investigations on gas-particle jets at frequently erupting volcanoes might be used for elucidating subsurface parameters and their temporal variability, with all the implications that may have for better defining hazard assessment.

scholarly journals Evaluation of Marblewood Dust’s (Marmaroxylon racemosum) Effect on Ignition Risk

2021 ◽  
Vol 11 (15) ◽  
pp. 6874
Author(s):  
Miroslava Vandličkova ◽  
Iveta Markova ◽  
Katarina Holla ◽  
Stanislava Gašpercová
Keyword(s):  
Particle Size ◽  
Dust Particles ◽  
Wood Dust ◽  
Sieve Analysis ◽  
Granulometric Analysis ◽  
Analysis Measurement ◽  
Risk Research ◽  
Minimum Ignition Temperature ◽  
The Impact

The paper deals with the selected characteristics, such as moisture, average bulk density, and fraction size, of tropical marblewood dust (Marmaroxylon racemosum) that influence its ignition risk. Research was focused on sieve analysis, granulometric analysis, measurement of moisture level in the dust, and determination of the minimum ignition temperatures of airborne tropical dust and dust layers. Samples were prepared using a Makita 9556CR 1400W grinder and K36 sandpaper for the purpose of selecting the percentages of the various fractions (<63, 63, 71, 100, 200, 315, 500 μm). The samples were sized on an automatic vibratory sieve machine Retsch AS 200. More than 65% of the particles were determined to be under 100 μm. The focus was on microfractions of tropical wood dust (particles with a diameter of ≤100 µm) and on the impact assessment of particle size (particle size <100 µm) on the minimum ignition temperatures of airborne tropical dust and dust layers. The minimum ignition temperature of airborne marblewood dust decreased with the particle size to the level of 400 °C (particle size 63 μm).

scholarly journals A flexible ChIP-sequencing simulation toolkit

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
An Zheng ◽  
Michael Lamkin ◽  
Yutong Qiu ◽  
Kevin Ren ◽  
Alon Goren ◽  
...  
Keyword(s):  
Ground Truth ◽  
Peak Calling ◽  
Simulation Framework ◽  
Experimental Conditions ◽  
Ground Truth Data ◽  
Chip Sequencing ◽  
Genome Wide ◽  
Experimental Parameters ◽  
Differential Binding ◽  
The Impact

Abstract Background A major challenge in evaluating quantitative ChIP-seq analyses, such as peak calling and differential binding, is a lack of reliable ground truth data. Accurate simulation of ChIP-seq data can mitigate this challenge, but existing frameworks are either too cumbersome to apply genome-wide or unable to model a number of important experimental conditions in ChIP-seq. Results We present ChIPs, a toolkit for rapidly simulating ChIP-seq data using statistical models of key experimental steps. We demonstrate how ChIPs can be used for a range of applications, including benchmarking analysis tools and evaluating the impact of various experimental parameters. ChIPs is implemented as a standalone command-line program written in C++ and is available from https://github.com/gymreklab/chips. Conclusions ChIPs is an efficient ChIP-seq simulation framework that generates realistic datasets over a flexible range of experimental conditions. It can serve as an important component in various ChIP-seq analyses where ground truth data are needed.

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