Study on Change Rules of Factors Affecting Gas Loss during Coalbed Air Reverse Circulation Sampling

The gas loss in sampling is the root of coalbed gas content measurement error. The pressure and particle size have a significant impact on the gas loss. Using the self-developed coal particle pneumatic pipeline transportation experimental system, this study investigated the pressure and particle size changes in the sampling pipeline. It is found that the sampling process can be divided into four stages: no flow field stage, sample outburst stage, stable conveying stage, and tail purging stage. The extreme pressure in the sampling pipeline appears at the sample outburst stage; and the pressure in the pipeline has levelled off after sharp decrease in the stable conveying stage. It is also found that the extreme pressure increases first and then decreases with the increase of particle size. The duration of outburst stage is negatively correlated with particle size, and that of stable conveying stage is positively correlated with particle size. In addition, the results show that the loss rate of 1–3 mm particles is the smallest after the test but that particles less than 1 mm increase by about two times and particles greater than 3 mm decrease by more than three times. The study also shows that the particle size distribution of coal samples is a single peak with left skew distribution, and the gas reverse circulation sampling test does not change the location of the peak but makes it higher and sharper. The single size coal sample is more likely to collide than the mixture. This study can help to advance the understanding of impact factors on gas loss during reverse circulation sampling.

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A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

Advances in Mechanical Engineering ◽

10.1177/16878140211017812 ◽

2021 ◽

Vol 13 (5) ◽

pp. 168781402110178

Author(s):

Zhengang Liu ◽

Weinan Diao ◽

Zhenxia Liu ◽

Fei Zhang

Keyword(s):

Particle Size ◽

Particle Deposition ◽

Numerical Study ◽

Stokes Number ◽

Capture Efficiency ◽

Particle Capture ◽

Factors Affecting ◽

Pressure Surface ◽

Deposition Area ◽

Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

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Physicochemical factors affecting the wettability of copper mine blasting dust

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00411-x ◽

2021 ◽

Author(s):

Longzhe Jin ◽

Jianguo Liu ◽

Jingzhong Guo ◽

Jiaying Wang ◽

Tianyang Wang

Keyword(s):

Particle Size ◽

Physicochemical Properties ◽

Pore Structure ◽

Total Pore Volume ◽

Open Pit ◽

X Rays ◽

Factors Affecting ◽

Copper Mine ◽

Mineral Components ◽

Hydrophobic Component

AbstractTo investigate the factors affecting the wettability of copper mine blasting dust, the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust (HLBD) and hydrophobic blasting dust (HBBD) using water flotation method. The physicochemical properties of HLBD and HBBD were measured and compared with each other. The properties included particle size distributions (PSDs), micromorphologies, pore structures, mineral components and surface organic carbon functional groups. The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability. Specifically, particle size of HBBD is smaller than that of HLBD, and their respiratory dust (less than 10 µm) accounts for 61.74 vol% and 53.00 vol%, respectively. The pore structure of HBBD is more developed, and the total pore volume of HBBD is 1.66 times larger than that of HLBD. The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction (XRD); however, the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD, this may be the reason for the poor wettability of HBBD. This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

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Research on the hydrographic survey cycle for updating navigational charts

Journal of Navigation ◽

10.1017/s0373463320000776 ◽

2021 ◽

pp. 1-13

Author(s):

Jing Duan ◽

Xiaoxia Wan ◽

Jianan Luo

Keyword(s):

Neural Network ◽

Bp Neural Network ◽

Calculation Model ◽

Impact Factors ◽

Factors Affecting ◽

Material Resources ◽

Hydrographic Survey ◽

Survey Planning ◽

The Impact ◽

The Relationship

Abstract Due to the vast ocean area and limited human and material resources, hydrographic survey must be carried out in a selective and well-planned way. Therefore, scientific planning of hydrographic surveys to ensure the effectiveness of navigational charts has become an urgent issue to be addressed by the hydrographic office of each coastal state. In this study, a reasonable calculation model of hydrographic survey cycle is established, which can be used to make the plan of navigational chart updating. The paper takes 493 navigational charts of Chinese coastal ports and fairways as the research object, analyses the fundamental factors affecting the hydrographic survey cycle and gives them weights, proposes to use the BP neural network to construct the relationship between the cycle and the impact factors, and finally establishes a calculation model of the hydrographic survey cycle. It has been verified that the calculation cycle of the model is effective, and it can provide reference for hydrographic survey planning and chart updating, as well as suggestions for navigation safety.

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Tailoring Adsorption Induced Switchability of a Pillared Layer MOF by Crystal Size Engineering

10.26434/chemrxiv.12917933.v1 ◽

2020 ◽

Author(s):

Leila Abylgazina ◽

Irena Senkovska ◽

Sebastian Ehrling ◽

Volodymyr Bon ◽

Petko Petkov ◽

...

Keyword(s):

Particle Size ◽

Low Frequency ◽

Polar Molecules ◽

Adsorption Enthalpy ◽

Factors Affecting ◽

University Of Technology ◽

Order Of Magnitude ◽

Crystal Structural ◽

Critical Particle Size ◽

Characteristic Adsorption

The pillared layer framework DUT-8(Zn) (Zn2(2,6-ndc)2(dabco), 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane, DUT = Dresden University of Technology) is a prototypical switchable MOF, showing characteristic adsorption and desorption induced open phase (op) to closed phase (cp) transformation associated with huge changes in cell volume. We demonstrate switchability strongly depends on a framework-specific critical particle size (dcrit). The solvent removal process (pore desolvation stress contracting the framework) significantly controls the cp/op ratio after desolvation and, subsequently, the adsorption induced switchability characteristics of the system. After desolvation, the dense cp phase of DUT-8(Zn) shows no adsorption-induced reopening and therefore is non-porous for N2 at 77 K and CO2 at 195 K. However, polar molecules with a higher adsorption enthalpy, such as the polar molecules such as chloromethane at 249 K and dichloromethane (DCM) at 298 K can reopen the macro-sized crystals upon adsorption. For macro-sized particles, the outer surface energy is negligible and only the type of metal (Zn, Co, Ni) controls the DCM-induced gate opening pressure. The framework stiffness increases from Zn to Ni as confirmed by DFT calculations, X-ray crystal structural analyses, and low frequency Raman spectroscopy. The partial disintegration of the Zn based node hinges produces an overall increased stabilization of cp vs. op phase shifts the critical particle size at which switchability starts to become suppressed to even lower values (dcrit < 200 nm) as compared to the Ni-based system (dcrit ≈ 500 nm). Hence, the three factors affecting switchability (energetics of the empty host, (Eop-Ecp) (I), particle size (II), and desolvation stress (III)) appear to be of the same order of magnitude and should be considered collectively, not individually.

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Paleolimnology of Lake Yamanaka as reflected on particle-size distribution

Bulletin of the Department of Geology ◽

10.3126/bdg.v14i0.5437 ◽

1970 ◽

Vol 14 ◽

pp. 35-42 ◽

Cited By ~ 1

Author(s):

Danda Pani Adhikari

Keyword(s):

Particle Size ◽

Grain Size ◽

Size Distribution ◽

Central Japan ◽

Size Frequency Distribution ◽

Factors Affecting ◽

Mean Grain Size ◽

The Mean ◽

Main Factors ◽

Lake Size

A 17.63 m long bore-hole core extracted from the deepest part of Lake Yamanaka, one of the Fuji-five Lakes at the northeasternfoot of Mount Fuji, central Japan, composed of sediment with intercalations of scoria fallout deposits. The sediment of the upper11.4 m was investigated for grain-size distribution by using a laser diffraction particle size analyser. The mean grain-size profileshowed various degrees of fluctuations, both short-and long-terms, and the size-frequency distribution revealed unimodal-trimodalmixing of sediments. Changes in lake size and water depth appear to be the main factors affecting the variability in the grain-sizedistribution and properties. The lake level appears low during 7000–5000 cal BP and 2800–1150 cal BP and relatively high during5000–2800 cal BP and 1150 cal BP– present.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5437Bulletin of the Department of Geology Vol.14 2011, pp.35-42

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Examining partial proportional odds model in analyzing severity of high-speed railway accident

Smart and Resilient Transport ◽

10.1108/srt-10-2020-0022 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Jing Wang ◽

Yinghan Wang ◽

Yichuan Peng ◽

Jian John Lu

Keyword(s):

High Speed ◽

Proportional Odds Model ◽

Impact Factors ◽

Proportional Odds ◽

High Speed Railway ◽

Severity Level ◽

Content Type ◽

Factors Affecting ◽

Partial Proportional Odds Model ◽

The Impact

Purpose The operation safety of the high-speed railway has been widely concerned. Due to the joint influence of the environment, equipment, personnel and other factors, accidents are inevitable in the operation process. However, few studies focused on identifying contributing factors affecting the severity of high-speed railway accidents because of the difficulty in obtaining field data. This study aims to investigate the impact factors affecting the severity of the general high-speed railway. Design/methodology/approach A total of 14 potential factors were examined from 475 data. The severity level is categorized into four levels by delay time and the number of subsequent trains that are affected by the accident. The partial proportional odds model was constructed to relax the constraint of the parallel line assumption. Findings The results show that 10 factors are found to significantly affect accident severity. Moreover, the factors including automation train protection (ATP) system fault, platform screen door and train door fault, traction converter fault and railway clearance intrusion by objects have an effect on reducing the severity level. On the contrary, the accidents caused by objects hanging on the catenary, pantograph fault, passenger misconducting or sudden illness, personnel intrusion of railway clearance, driving on heavy rain or snow and train collision against objects tend to be more severe. Originality/value The research results are very useful for mitigating the consequences of high-speed rail accidents.

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Factors Affecting the Particle Size of Bio-Calcium Carbonate Synthesized from Industrial Eggshell Waste

MATERIALS TRANSACTIONS ◽

10.2320/matertrans.mf201708 ◽

2018 ◽

Vol 59 (8) ◽

pp. 1220-1224 ◽

Cited By ~ 1

Author(s):

Ajchara I. Putkham ◽

Somchai Ladhan ◽

Apipong Putkham

Keyword(s):

Particle Size ◽

Calcium Carbonate ◽

Factors Affecting ◽

Eggshell Waste

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The Hydrodynamic Dispersion Characteristics of Coral Sands

Journal of Marine Science and Engineering ◽

10.3390/jmse7090291 ◽

2019 ◽

Vol 7 (9) ◽

pp. 291 ◽

Cited By ~ 1

Author(s):

Xiang Cui ◽

Changqi Zhu ◽

Mingjian Hu ◽

Xinzhi Wang ◽

Haifeng Liu

Keyword(s):

Particle Size ◽

Porous Media ◽

Flow Velocity ◽

Molecular Diffusion ◽

Dispersion Coefficient ◽

Hydrodynamic Dispersion ◽

Dispersion Characteristics ◽

Factors Affecting ◽

Mechanical Dispersion ◽

Freshwater Aquifers

Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion characteristics of solute in calcareous sands and the particle size, degree of compactness, and gradation of porous media, with a discussion of the types of dispersion mechanisms in coral sands. It was found that the particle size of coral sands was an important parameter affecting the dispersion coefficient, with the dispersion coefficient increasing with particle size. Gradation was also an important factor affecting the dispersion coefficient of coral sands, with the dispersion coefficient increasing with increasing d10. The dispersion coefficient of coral sands decreased approximately linearly with increasing compactness. The rate of decrease was −0.7244 for single-grained coral sands of particle size 0.25–0.5 mm. When the solute concentrations and particle sizes increased, the limiting concentration gradients at equilibrium decreased. In this study, based on the relative weights of molecular diffusion versus mechanical dispersion under different flow velocity conditions, the dispersion mechanisms were classified into five types, and for each type, a corresponding flow velocity limit was derived.

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Experimental Analyses of the Major Parameters Affecting the Intensity of Outbursts of Coal and Gas

The Scientific World JOURNAL ◽

10.1155/2014/185608 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9

Author(s):

W. Nie ◽

S. J. Peng ◽

J. Xu ◽

L. R. Liu ◽

G. Wang ◽

...

Keyword(s):

Water Content ◽

Relative Intensity ◽

Gas Content ◽

Horizontal Load ◽

Vertical Load ◽

Range Analysis ◽

Factors Affecting ◽

Mining Depth ◽

Physical Experiments ◽

Relative Threshold

With an increase in mining depth and production, the intensity and frequency of outburst of coal and gas have a tendency to increase. Estimating the intensity of outbursts of coal and gas plays an important role because of its relation with the risk value. In this paper, we described the semiquantitative relations between major parameters and intensity of outburst based on physical experiments. The results showed increment of geostress simulated by horizontal load (from 1.4, 2.4, 3.2, to 3.4 MPa) or vertical load (from 2, 3, 3.6, to 4 MPa) improved the relative intensity rate (3.763–7.403% and 1.273–7.99%); the increment of porosity (from 1.57, 2.51, 3, to 3.6%) improved the relative intensity rate from 3.8 to 13.8%; the increment of gas pressure (from 0, 0.5, 0.65, 0.72, 1, to 1.5 Mpa) induced the relative intensity rate to decrease from 38.22 to 0%; the increment of water content (from 0, 2, 4, to 8%) caused the relative intensity rate to drop from 5.425 to 0.5%. Furthermore, sensitivity and range analysis evaluates coupled factors affecting the relative intensity. In addition, the distinction with initiation of outburst of coal and gas affected by these parameters is discussed by the relative threshold of gas content rate.

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Changes in Particle Size Composition under Seepage Conditions of Reclaimed Soil in Xinjiang, China

Processes ◽

10.3390/pr6100201 ◽

2018 ◽

Vol 6 (10) ◽

pp. 201 ◽

Cited By ~ 1

Author(s):

Zizhao Zhang ◽

Wanghua Sui ◽

Kaikai Wang ◽

Guobin Tang ◽

Xiaoping Li

Keyword(s):

Particle Size ◽

Fine Particle ◽

Granulometric Composition ◽

Fine Particles ◽

Land Reclamation ◽

Sharp Decrease ◽

Size Composition ◽

Particle Content ◽

Reclaimed Soil ◽

Different Depths

The distribution of reclaimed soil particle size under seepage conditions after the management period will directly determine the success or failure of reclamation work. The geotechnical experimental method was used in this paper to study the changes in the granulometric composition of soil. The results show that the granulometric composition of the reclaimed soil varied obviously at different depths. The granulometric composition of the soil at a depth of 10 cm was not much different from undisturbed reclaimed soil (URS). At a depth of 30 cm, as the sharp decrease of the content of fine particles resulted in coarser reclaimed soil, the soil became more uniform, with an increase in porosity and water content. At a depth of 50 cm, the fine particle content was generally slightly lower than that of URS. At a depth of 70 cm, the fine particle content of the soil greatly exceeded that of the URS, with the finest soil particles and lowest porosity. The main reason for the above-mentioned changes of granulometric composition in the reclaimed soil was the seepage in soil caused by irrigation during the management period. The research results can provide a reference for management after land reclamation at non-metallic mines in Xinjiang, China.

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