scholarly journals Mechanical Mechanism of Water Injection to Enhance the Stability of Soft Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Chuanqi Zhu ◽  
Hao Fan ◽  
Wanrong Liu ◽  
Shaobo Li
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Liquid Bridge ◽  
Capillary Tube ◽  
Water Injection ◽  
Physical And Mechanical Properties ◽  
Point Load ◽  
Displacement Curve ◽  
Angle Of Internal Friction ◽  
Soft Coal

The physical and mechanical properties of soft coal body constitute one of the most important factors inducing coal wall spalling. In order to explore the mechanical essence of coal instability disaster and stability enhancement of water injection, the 7# coal in Huainan mining area is taken as the research object. Firstly, the distribution characteristics of coal particle size, point-load strength, original water content, microstructure characteristics, and shear strength of coal under different water contents are measured by laboratory tests. Then, based on the test results, the cementation morphology and force evolution law of granular coal water in coal body are analyzed using liquid bridge theory. The results show the following: (1) With the increase of particle size, the mass ratio of granular coal increases gradually. The percentage of particle coal with particle size less than 2.5 mm accounts for 47.157%, fractal dimension is 2.172, and uniaxial compressive strength and tensile strength are 3.822 MPa and 0.165 MPa, respectively. (2) The coal body is dry (the original moisture content is 1.336%), containing a large number of loose particles, pores, fissures, and other microfabrics. This “low water content and multiporosity” feature is the essential reason for its low strength, fragmentation, and instability and disaster. (3) In the process of water content increasing from 0.966% to 26.580%, the shear stress-displacement curve of coal body gradually changes from softening type to hardening type, and the failure type transitions from brittleness to ductility. The cohesive force increases first and then decreases, while the angle of internal friction almost has no change. (4) After reasonable water injection, the shape of liquid bridge in coal body changes into capillary tube, and the liquid bridge force reaches the maximum value, which transforms from a highly unstable bulk to a stable continuum. The research results have important theoretical significance and practical value for the safe and efficient mining of soft coal seams.

scholarly journals Experimental Study on Strength Influencing Factors of Calcareous Nodule Soil in Northern Jiangsu

2021 ◽  
Author(s):  
Xiaolong Wang ◽  
Jianling Gu ◽  
Song Xu ◽  
Shengdong Gu
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Soil Layer ◽  
Physical And Mechanical Properties ◽  
Triaxial Tests ◽  
Long Time ◽  
Confining Pressures ◽  
Calcareous Concretion ◽  
Time Required ◽  
The Impact

The physical and mechanical properties of calcareous concretion soil depend largely on the shape, size and distribution of calcareous concretion soil besides the impact of soil layer. Due to the long time required for clay saturation, consolidation, and shearing, as well as the tedious sample preparation, larger triaxial tests of calcareous nodules have not been carried out. In this chapter, based on the medium triaxial test of calcareous nodules, the strength characteristics of remolded soil samples under different confining pressures are studied. By controlling parameters such as calcareous nodules particle size and water content, the impact of different test conditions on the strength of calcareous nodules is analysed, and the variation rule is analysed. It is concluded that the impact of nodular particle size on soil strength is not obvious at 20% nodular content. The impact of different water content on the strength of soil is more regular, showing hardening characteristics, in line with the natural law.

Mikrokapsul Ekstrak Bawang Tiwai sebagai Pengawet Pangan

2016 ◽  
Vol 9 (1) ◽  
pp. 73-79
Author(s):  
Suroto Hadi Saputra ◽  
Paluphy Eka Yustini
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Rank Test ◽  
Water Particle ◽  
Range Test

Applications bawang tiwaiextractin the form ofpastaI have everdone in thefoodpreservativehaving troubleamong othersinsolubleandmixedwell withthe doughingredientsof food. One alternativeto overcome these problemsismicroencapsulated bawang tiwai extract.In this study, bulb bawangtiwaiextractedwithethanol 98%. Researchusinga completely randomized designfactorial3x2was repeated3times. The firstfactorcomposition ofthe coating materialwith 3 levels, the secondfactorwith 2degreetemperature.  Analysisof variance and dunken multiplerangetestfurthertestat5% confidence levelusing thesoftwareSPSSversion20. Results oftreatment ofthe coating materialcompositionandtemperatureas well as theinteractionsignificantly affected thephenol content, water content, solubilityin water, particle size andconcentration of ethanol. The results of analysisduncanmultiplerank testof showdifferentlevels ofphenol, water content, solubilityin water, particle size andconcentration of ethanol. The results showedthe highest valuein treatment(s1p1) phenolcontent of1.50%, (s2p1) lowwater content15.27%, (s1p1) watersoluble extracthighestlevel of87.45% (s2p1) 216.77smallestparticlesizeand(s2p1) lowethanollevels15, 17ppmABSTRAKAplikasi ekstrak bawang tiwai dalam bentuk pasta yang pernah dilakukan dalam pengawet pangan mengalami kesulitan antara lain tidak mudah larut dan tercampur secara baik dengan bahan adonan pangan. Salah satu alternatif untuk mengatasi permasalahan tersebut adalah mikroenkapsulasi ekstrak bawang tiwai.  Dalam penelitian ini, umbi bawang tiwai diekstrak dengan etanol 98%. Penelitian menggunakan rancangan acak lengkap faktorial 3 x 2 diulang 3 kali. Faktor pertama komposisi bahan penyalut dengan 3 taraf, faktor kedua suhu dengan 2 taraf. Hasil analisis sidik ragam dan uji lanjut dunken multiple range test pada tingkat kepercayaan 5% menggunakan soft ware SPSS versi 20. Analisa parameter pada penelitian ini antara lain kadar fenol, kadar air, kadar sari larut air dan ukuran partikel. Hasil perlakuan komposisi bahan penyalut dan suhu serta interaksi berpengaruh nyata terhadap kadar fenol, kadar air, kelarutan dalam air, ukuran partikel dan kadar etanol. Hasil analisisduncan multiple rank test (DMRT) menunjukkan berbeda nyata terhadap kadar fenol, kadar air, kelarutan dalam air, ukuran partikel dan kadar etanol. Hasil penelitian menunjukkan nilai tertinggi pada perlakuan (s1p1) kadar fenol 1,50 %, (s2p1) kadar air terendah 15,27%, (s1p1) kadar sari larut air tertinggi 87,45%(s2p1) ukuran partikel terkecil 216,77 dan (s2p1) kadar etanol terendah 15, 17 ppm. Kata kunci : bawang tiwa,  mikroenkapsulasi, maltodekstrin, na-kaseinat, pengawet pangan.

scholarly journals Effect of Particle Size Distribution on Laser Powder Bed Fusion Manufacturability of Copper

2021 ◽  
Author(s):  
Massimiliano Bonesso ◽  
Pietro Rebesan ◽  
Claudio Gennari ◽  
Simone Mancin ◽  
Razvan Dima ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Physical And Mechanical Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Cooling Channels ◽  
Scan Speed

AbstractOne of the major benefits of the Laser Powder Bed Fusion (LPBF) technology is the possibility of fabrication of complex geometries and features in only one-step of production. In the case of heat exchangers in particular, this is very convenient for the fabrication of conformal cooling channels which can improve the performance of the heat transfer capability. Yet, obtaining dense copper parts printed via LPBF presents two major problems: the high reflectivity of 1 μm (the wavelength of commonly used laser sources) and the high thermal conductivity of copper that limits the maximum local temperature that can be attained. This leads to the formation of porous parts.In this contribution, the influence of the particle size distribution of the powder on the physical and mechanical properties of parts produced via LPBF is studied. Three copper powders lots with different particle size distributions are used in this study. The effect on densification from two laser scan parameters (scan speed and hatching distance) and the influence of contours scans on the lateral surface roughness is reported. Subsequently, samples manufactured with the optimal process parameters are tested for thermal and mechanical properties evaluation.

Comparison of Water Thickness Profiles of Compressed PEMFC GDLs

2011 ◽  
Author(s):  
Pradyumna Challa ◽  
James Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Water Injection ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Injection Rate ◽  
Water Levels ◽  
Ex Situ

In this paper, through-plane liquid water distribution is analyzed for two polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). The experiments were conducted in an ex situ flow field apparatus with 1 mm square channels at two distinct flow rates to mimic water production rates of 0.2 and 1.5 A/cm2 in a PEMFC. Synchrotron radiography, which involves high intensity monochromatic X-ray beams, was used to obtain images with a spatial and temporal resolution of 20–25 μm and 0.9 s, respectively. Freudenberg H2315 I6 exhibited significantly higher amounts of water than Toray TGP-H-090 at the instance of breakthrough, where breakthrough describes the event in which liquid water reaches the flow fields. While Freudenberg H2315 I6 exhibited a significant overall decrease in liquid water content throughout the GDL shortly after breakthrough, Toray TGP-H-090 appeared to retain breakthrough water-levels post-breakthrough. It was also observed that the amount of liquid water content in Toray TGP-H-090 (10%.wt PTFE) decreased significantly when the liquid water injection rate increased from 1 μL/min to 8 μL/min.

Corrigendum to

2018 ◽  
Vol 83 ◽  
pp. 511 ◽  
Author(s):  
Peng Guo ◽  
Jinglin Yu ◽  
Shujun Wang ◽  
Shuo Wang ◽  
Les Copeland
Keyword(s):  
Particle Size ◽  
Physicochemical Properties ◽  
Durum Wheat ◽  
Water Content ◽  
Starch Digestibility ◽  
In Vitro Starch Digestibility ◽  
Wheat Grains

scholarly journals Shear strength characteristics of Jerash expansive soil

2021 ◽  
Vol 3 (2) ◽  
pp. 74-80
Author(s):  
Talal Masoud
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Direct Shear Test ◽  
Shear Test ◽  
Expansive Soil ◽  
Content Increase ◽  
Direct Shear ◽  
Initial Water ◽  
Angle Of Internal Friction

The results of the direct shear test on Jerash expansive soil show the effect of the initial water content on the cohesion (c) and on the angel of internal friction ( ) [shear strength parameters].it show that, as the initial water increase, the cohesion (c) of Jerash expansive soil also increase up to the shrinkage limit, after that increase of water even small amount, decrease the cohesion of the soil. On the other hand, the results of direct shear test show also  that as the water content increase, the angle of internal friction ( )remain unchanged up to shrinkage limit , any increase of water cause a large decrease on the angle of internal friction of Jerash expansive soil.

scholarly journals KUALITAS PAPAN KOMPOSIT DARI LIMBAH FINIR KAYU LAPIS BERDASARKAN UKURAN PARTIKEL DAN WAKTU PENGEMPAAN DENGAN MENGGUNAKAN PEREKAT LIMBAH PLASTIK POLIPROPILENA

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Alfonsus Rodriquez ◽  
Ahmad Yani ◽  
Fathul Yusro
Keyword(s):  
Particle Size ◽  
Physical And Mechanical Properties ◽  
Particle Sizes ◽  
Hot Press ◽  
Factor B ◽  
Pressing Time ◽  
Materials Used ◽  
Absorption Thickness ◽  
Water Contents

This study aims to analyze the quality of composite boards from plywood veneers waste and polypropylene plastic waste adhesives base on particle sizes, pressing times, and both of interaction towards physical and mechanical properties also to obtain the particle sizes and pressing time properly with the result that produce the qualified standard boards of JIS A 5908-2003. This research carried out at the wood workshop, laboratory of technology and processing of woods (the faculty of forestry, university of Tanjungpura), and the laboratory of PT. Duta Pertiwi Nusantara. The materials used in this study were plywood veneers waste and polypropylene plastic by 50% : 50% comparison. The research method was utilized the completely randomized factorial design by two treatment factors. Factor A was particle sizes that consisting of 6 mesh, 8 mesh, and 10 mesh. Factor B was pressing time that consisting of 10 minutes, 15 minute, and 20 minutes. Composite boards were created by 30 x 30 x 1 size in centimetres by means the density target was 0,7 gr/cm3. The pressing was done by hot press in 180oC temperature and composite boards conditioning for 14 days. The results of this study showed that the density, water absorption, thickness, Modulus of Repture (MOR), internal bonding, holding strength of screws in the composite boards have been qualified the standard of JIS A 5908-2003. While, the water contents and Modulus of Elasticity (MOE) testing were not qualified the standard of JIS 5908-2003. The treatment that produce the optimum composite boards which quality JIS A 5908-2003 standard was on the 8 mesh particle size treatment by means of 15 minutes pressing time.Keywords: Composite Board, Particle Size, Polypropylene Plastics, Pressing Time, Veneers Waste.

Statistical Modelling of the Particle Size Composition of an Alumina Matrix for No-Cement Self-Flowing Refractory Castables

2006 ◽  
Vol 514-516 ◽  
pp. 604-608 ◽  
Author(s):  
Abílio P. Silva ◽  
Ana M. Segadães ◽  
Tessaleno C. Devezas
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Raw Materials ◽  
Size Composition ◽  
Statistical Modelling ◽  
Matrix Composition ◽  
Mechanical Resistance ◽  
Particle Size Composition ◽  
Refractory Castables ◽  
System Properties

In the processing of any particulate system (including refractory castables), the finer sized particle fraction (matrix or filler) is mostly responsible for the final system properties. Alumina fine powders were used in this work as raw materials, namely two tabular alumina fractions (–500 mesh and –230 mesh) and a commercial reactive alumina. Statistical modelling and the Response Surface Methodology (Statistica, Mixtures Designs and Triangular Surfaces module) were used to optimise the particle size composition of the three-component mixtures leading to matrix maximum flowability. The mixing methodology, aimed at minimising the water content, was kept constant. No-cement alumina castables produced with the various fine size powder mixtures, were used to prepare test-pieces. After drying and sintering, their mechanical resistance (MoR), density, porosity, water absorption, thermal shock behaviour and microstructure were evaluated. The results obtained evidenced the relevance of variables such as the water content per unit specific surface area, needed to reach the self-flow “turning point”, and validated the statistical optimisation method used. Moreover those results showed the existence of a matrix composition range, which favours the formation of a flow-bed that enables the aggregate self-flow.

Experimental Study on the Effects of Internal Erosion on the Physical and Mechanical Properties of Tailings Under Unsteady Seepage

2021 ◽  
Author(s):  
Rong Gui ◽  
Guicheng He
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Shear Strength ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Internal Erosion ◽  
Average Particle ◽  
Sand Column ◽  
Sedimentary Characteristics ◽  
Seepage Erosion

Abstract In this paper, the hydraulic sedimentary model was established to investigate the effects of dry beach slope on the sedimentary characteristics of tailings, and the sand column model was built to investigate the effects of seepage erosion on the physical and mechanical properties of sedimentary tailings under unsteady seepage.The results show that the slope of dry beach have a great effect on the sedimentary characteristics of tailings, the average particle size of tailings decreases along the slope of dry beach, and the larger the slope, the more obvious the stratification of the tailings. The migration of fine-grained tailings caused by seepage erosion increases the permeability of the tailings and reduces the shear strength of the tailings. After seepage erosion,the average particle size of 1#tailings sample, 2#tailings sample and 3#tailings sample increased by 6.4%, 12.0% and 2.4% respectively, the hydraulic conductivity of 1# tailings sample, 2# tailings sample and 3# tailings increased by 27.2%,17.9%, and 15.3% respectively after internal erosion, and the shear strength of 1#tailings sample, 2#tailings sample and 3#tailings sample tailings sample decreased by 20.9 %, 15.1% and 12.4% respectively.

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