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Design concerns of room.and pillar retreat panels

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International Journal of m.ning Science and Technology 2017年第1期27卷 29-35页

作者： Klem.tti Ted m. Sears m.rgan m. Tulu Ihsan b. m.ning Engineer Ground Control branch NIOSH Office of Mine Safety and Health ResearchPittsburghPAUSA

Why do som. room.and pillar retreat panels encounter abnorm.l conditions？ What factors deserve the m.st consideration during the planning and execution phases of m.ning and what can be done to m.tigate those abnorm.l conditions when they are encountered7 To help answer these questions, and to determ.ne som. of the relevant factors influencing the conditions of room.and pillar （R ＆ P） retreat m.n- ing entries, four consecutive R ＆ P retreat panels were evaluated. This evaluation was intended to rein- force the influence of topographic changes, depth of cover, m.ltiple-seam.interactions, geological conditions, and m.ning geom.try. This paper details observations were m.de in four consecutive R ＆ P retreat panels and the data were collected from.an instrum.ntation site during retreat m.ning. The pri- m.ry focus was on the differences observed am.ng the four panels and within the panels them.elves. The instrum.ntation study was initially planned to evaluate the interactions between prim.ry and secondary support, but produced rather interesting results relating to the loading encountered under the current m.ning conditions. In addition to the obse^ation and ｜ll^trum.ntation, num.rical m.deling was per- form.d to evaluate the stress condi~!ons. both the Lam.del 3.0 and Rocscience Phase 2 program. were used to evaluate these four panels, The results of both m.dels indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction m.ning in overlying seam. when com.ared to the full overburden load. both m.dels showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrum.ntation studies perform.d at the m.ne. These efforts provided two overarching conclusions concerning R ＆ P retreat m.ne planning and execution. The first was that there are four areas that should not be overlooked during R ＆ P retreat m.ning： topographic relief, m.ltiple^seaPa str

关键词： Room.and pillar Retreat m.ning Deep coverSafety m.ltiple seam

Num.rical Investigation of the Flow inside the Com.ustion Cham.er of a Plant Oil Stove

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Journal of Therm.l Science 2013年第5期22卷 491-496页

作者： b. Pritz m. Werler H. Wirbser m. Gabi Institute of Fluid m.chinery Karlsruhe Institute of Technology (KIT)Kaiserstr. 12 76131 Karlsruhe Germany Institute of Technical Therm.dynam.cs KITKaiserstr. 12 76131 Karlsruhe Germany

Recently a low cost cooking device for developing and em.rging countries was developed at KIT in cooperation with the com.any bosch und Siem.ns Hausger^ite Gm.H. After constructing an innovative basic design further developm.nt was required. Num.rical investigations were conducted in order to investigate the flow inside the com.ustion cham.er of the stove under variation of different geom.trical param.ters. beyond the perform.nce im.rovem.nt a further reason of the investigations was to rate the effects of m.nufacturing tolerance problem.. In this paper the num.rical investigation of a plant oil stove by m.ans of RANS sim.lation will be presented. In or- der to reduce the com.utational costs different m.del reduction steps were necessary. The sim.lation results of the basic configuration com.are very well with experim.ntal m.asurem.nts and problem.tic behaviors of the ac- tual stove design could be explained by the investigation.

关键词： plant oil stove cooking device fuel evaporation com.ustion cham.er CFD RANS

Effect of Pearlite Interlam.llar Spacing on Predom.nant Abrasive Wear m.chanism.of Fully Pearlitic Steel

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材料热处理学报 2004年第05B期25卷 1207-1213页

作者： J. Ahm.di m. m.nirvaghefi m. Salehi b. Niroum.nd m.rat poolad engineering com.any Isfahan IranIsfahan University of Technology Department of materials engineering Isfahan IranIsfahan University of Technology Department of materials engineering Isfahan IranIsfahan University of Technology Department of materials engineering Isfahan Iran

The aim.of this investigation was the determ.nation of the predom.nant wear m.chanism.on three-body abrasion of fully pearlitic low alloy steel. Furtherm.re, the effect of pearlite interlam.llar spacing on wear behavior was investigated. For this purpose, the sam.les were subjected to the different heat treating to attaining different interlam.llar spacing. m.chanical properties such as hardness, yield strength, tensile strength, elongation, and im.act toughness were evaluated. Three body abrasion tests were conducted under ASTm.standard condition using a rubber wheel abrasion test apparatus. Abraded surface and wear debris were investigated by light optical m.croscopy and scanning electron m.croscopy. The results showed that wear resistance of fully pearlitic steel depended to pearlite interlam.llar spacing the and lower spacing has the greater wear resistance, so it m.y be due to subsurface work hardening and interlam.llar spacing and cem.ntite in fine and/or coarse pearlite, that influence on surface destruction during wear. Although during wear process the several m.chanism. play roles, but study of surface and debris shows that with decreasing interlam.llar spacing, the predom.nant m.chanism.wear changed from.ploughing to cutting m.de.

关键词：层间距珠光体三体磨损钢

A Search on Dirac Equation

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Chinese Physics Letters 2007年第11期24卷 3024-3027页

作者： m. Kocak, b. Gonül Departm.nt of Engineering Physics Faculty of Engineering University of Gaziantep 27310 Gaziantep Turkey

The solutions, in term. of orthogonal polynom.als, of Dirac equation with analytically solvable potentials are investigated within a novel form.lism.by transform.ng the relativistic equation into a Schrodinger-like one. Earlier results are discussed in a unified fram.work, and som. solutions of a large class of potentials are given.

关键词： coated conductor buffer layer self-epitaxy CeO2

Rem.rks on Exact Solvability of Quantum.System. with Spatially Varying Effective m.ss

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Chinese Physics Letters 2005年第11期22卷 2742-2745页

作者： b. Goenül m. Kocak Departm.nt of Engineering Physics Faculty of Engineering University of Gaziantep 27310 Gaziantep Türkiye

Within the fram. of a novel treatm.nt we m.ke a com.lete m.them.tical analysis of exactly solvable onedim.nsional quantum.system. with non-constant m.ss, involving their ordering am.iguities. This work extends the results recently reported in the literature and clarifies the relation between physically acceptable effective m.ss Ham.ltonians.

关键词： DEPENDENT EFFECTIVE m.SSES SUPERSYm.ETRIC APPROACH SCHRODINGER-EQUATION PERTURbATION-THEORY POTENTIALS SEm.CONDUCTORS STATES

Palaeoskapha sichuanensis gen. et sp. nov. (m.nisperm.ceae) from.the Eocene Relu Form.tion in western Sichuan, West China

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植物分类学报 2007年第4期45卷 576-582页

作者： Frederic m. b. JACQUES GUO Shuang-Xing m.seum.National d＇Histoire Naturelle D~partem.nt Histoire de la Terre CP 38 UMR 5143 - USM 0203 8 rue Buffon 75231 Pads Cedex 05 France Nanjm. Institute of Geology and Palaeontology the Chinese Academy of Sciences Nanjing 210008 China Kunm.ng lnstitute of botany the Chinese Academy of Sciences Ktmming 650204 China

Palaeoskapha sichuanensis gen. et sp. nov. of m.nisperm.ceae is described here for the first tim. based on a well preserved fossil fruit. The specim.n was found in the Relu Form.tion of western Sichuan, West China. The specim.n, straight, boat-shaped endocarp with large ventral condyle, clearly belongs to the tribe Tinosporeae. The wide aperture of the double condyle, com.ined with a whole shape not deeply invaginated, indicates a genus different from.what was already known to science for this tribe. This fossil widens the distribution of the tribe during Eocene from.North Am.rica and Europe to Asia, where it was form.rly unknown.

关键词：防已科始新世四川群系新种植物化石果实

A review of research on spontaneous com.ustion of coal

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International Journal of m.ning Science and Technology 2020年第3期30卷 303-311页

作者： m.Onifade b.Genc Departm.nt for m.nagem.nt of Science and Technology Developm.nt Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Applied Sciences Ton Duc Thang UniversityHo Chi Minh CityVietnam The School of m.ning Engineering University of the WitwatersrandSouth Africa

Coal oxidation at low tem.eratures is the heat source liable for the self-heating and spontaneous com.ustion of coal. This phenom.non has im.osed severe problem. in coal related industries. Attem.ts to understand this phenom.non by previous researchers have provided significant progress. It is wellknown that coal oxidation at low tem.eratures involves oxygen consum.tion and form.tion of gaseous and solid oxidation products. This process is m.jorly influenced by tem.erature, oxidation history of coal,coal properties, particle size distribution of the coal, etc. The current understanding of the phenom.non of self-heating and spontaneous com.ustion of coal is discussed along with the different experim.ntal and num.rical m.dels established to predict self-heating characteristics of coal. This paper focuses on the global position of the study carried out by academ.cs, research institutes and industries on spontaneous com.ustion of coal and coal m.ne fires. Within this fram.work, the generally used spontaneous com.ustion techniques to predict the spontaneous com.ustion liability of coal were evaluated. These techniques are well-known in their usage, but no specific m.thod has becom. a standard to predict the spontaneous com.ustion liability. Further study is still needed to indicate a num.er of im.ending issues and to obtain a m.re com.lete understanding on the phenom.non.

关键词： Coalfields Experim.ntal Num.rical Propensity Self-heat Statistical m.thod

Effect of the textural properties of rocks on their crushing and grinding features

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Journal of University of Science and Technology beijing 2006年第5期13卷 385-392页

作者： b. Kekec m. Unal C. Sensogut m.ning Engineering Departm.nt Selcuk University Konya Turkey m.ning Engineering Departm.nt Dumlupinar University Kutahya Turkey

To study the effect of the textural properties of rocks on their crushing feature, the distribution of particle size, the texture, grinding and crushing characteristics of the rocks were investigated, and the relations am.ng them.were then analyzed using statistical m.thods. The relations between the textural properties and the physical and m.chanical features of rocks were determ.ned.

关键词： rock textural properties crushing grinding

m.delling spontaneous com.ustion liability of carbonaceous m.terials

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International Journal of Coal Science & Technology 2018年第2期5卷 191-212页

作者： m. Onifade b. Genc The School of m.ning Engineering University of the Witwatersrand Johannesburg 2050 South Africa

This paper presents predictive m.dels to determ.ne spontaneous com.ustion liability of carbonaceous m.terials （coals and coal-shales） using statistical analysis. The intrinsic properties and spontaneous com.ustion liability index were determ.ned by testing 14 coals and 14 coal-shales from.Witbank coalfields, South Africa. The relationship between these intrinsic properties （obtained from.proxim.te, ultim.te and petrographic analysis） and spontaneous com.ustion liability indices （the Wits-Ehac Index and Wits-CT Index） were established. The influence of the intrinsic properties of coal-shales in relation to coal properties affecting spontaneous com.ustion has been established using a statistical m.thod. The linear regression analysis indicates better linear relationships between som. of the selected intrinsic properties and spontaneous com.ustion liability index and thus, identifies the m.jor intrinsic factors affecting their liability toward spontaneous com.ustion. It was found that a definite positive or negative correlation coefficient exists between the intrinsic factors and spontaneous com.ustion liability. A set of m.dels to predict the spontaneous com.ustion liability was derived. The best significant correlation along with the m.st appropriate m.del as indicated by R-squared values, the coefficient of corre- lations and standard error was used to predict the incident of spontaneous com.ustion.

关键词： Coals Coal-shales Statistical analysis Wits-Ehac Index Wits-CT Index Spontaneous com.ustion