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Measurements of dihadron correlations relative to the event plane in Au+Au collisions at√^(S)NN=200 GeV

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Chinese Physics C 2021年第4期45卷 198-241页

作者： H.Agakishiev M.M.Aggarwal Z.Ahammed A.V.Alakhverdyants I.Alekseev J.Alford B.D.Anderson C.D.Anson D.Arkhipkin G.S.Averichev J.Balewski D.r.Beavis N.K.Behera r.Bellwied M.J.Betancourt r.r.Betts A.Bhasin A.K.Bhat H.Bichsel J.Bieleik J.Bielcikova B.Biritz L.C.Bland W.Borowski J.Bouchet E.Braidot A.V.Brandin A.Bridgeman S.G.Brovko E.Bruna S.Bueltmann I.Bunzarov T.P.Burton X.Z.Cai H.Caines M.Calderon de la Barca Sanchez D.Cebra r.Cendejas M.C.Cervantes Z.Chajecki P.Chaloupka S.Chattopadhyay H.F.Chen J.H.Chen J.Y.Chen L.Chen J.Cheng M.Cherney A.Chikanian K.E.Choi W.Christie P.Chung M.J.M.Codrington r.Corliss J.G.Cramer H.J.Crawford S.Dash A.Davila Leyva L.C.De Silvat r.r.Debbe T.G.Dedovich A.A.Derevschikov r.Derradi de Souza L.Didenko P.Djawotho S.M.Dogra X.Dong J.L.Drachenberg J.E.Draper J.C.Dunlop L.G Efimov M.Elnim J.Engelage G Eppley M.Estienne L.Eun O.Evdokimov r.Fatemi J.Fedorisin A.Feng r.G.Fersch P.Filip E.Finch V.Fine Y.Fisyak C.A.Gagliardi D.r.Gangadharan A.Geromitsos F.Geurts P.Ghosh Y.N.Gorbunov A.Gordon O.Grebenyuk D.Grosnick S.M.Guertin A.Gupta W.Guryn B.Haag O.Hajkova A.Hamed L-X.Han J.W.Harris J.P.Hays-Wehle M.Heinz S.Heppelmann A.Hirsch E.Hjort G.W.Hoffmann D.J.Hofiman B.Huang H.Z.Huang T.J.Humanic L.Huo G.Igo P.Jacobs W.W.Jacobs C.Jena F.Jin J.Joseph E.G.Judd S.Kabana K.Kang J.Kapitan K.Kauder H.Ke D.Keane A.Kechechyan D.Kettler D.P.Kikola J.Kiryluk A.Kisiel V.Kizka A.G.Knospe D.D.Koetke T.Kollegger J.Konzer I.Koralt L.Koroleva W.Korsch L.Kotchenda V.Kouchpil P.Kravtsov K.Krueger M.Krus L.Kumar P.Kurnadi M.A.C.Lamont J.M.Landgraf S.LaPointe J.Lauret A.Lebedev r.Lednicky J.H.Lee W.Leight M.J.LeVine C.Lil L.Li N.Li W.Li X.Li X.Li Y.Li Z.M.Li M.A.Lisa F.Liu H.Liu J.Liu T.Ljubicic W.J.Llope r.S.Longacre W.A.Love Y.Lu E.V.Lukashov X.Luo G.L.Ma Y.G.Mai D.P.Mahapatra r.Majka O.I.Mall L.K.Mangotra r.Manweiler S.Margetis C.Markert H.Masui H.S.Matis Yu.A.Matulenko D.MeDonald T.S.McShane A.Meschanin r.Milner N.G.Minaev S.Mioduszewski A.Mischke M.K.Mitrovski B.Mohanty M.M.Mondal B.Morozov D.A.Morozov M.G.Munhoz M Argonne National Laboratory Argonnellinois 60439USA Brookhaven National Laboratory UptonNew York 11973USA University of Califomia BerkeleyCaliformnia 94720USA University of California DavisCalifornia 95616USA University of Califormnia Los AngelesCalifomia 90095USA Universidade Estadual de Campinas Sao PauloBrazil University of Illinois at Chicago ChicagoIlinois 60607USA Creighton University OmahaNebraska 68178USA Czech Technical University in Prague FNSPEPrague11519Czech Republic Nuclear Physics Institute AS Cr 25068 Rez/PragueCzech Republic University of Frankfurt FrankfurtGermany Institute of Physics Bhubaneswar 751005India Indian Institute of Technology MumbaiIndia Indiana University BloomingtonIndiana 47408USA Alikhanov Instiute for Theoretical and Experimental Physics MoscowRussia University of Jammu Jammu 180001India Joint Institute for Nuclear research Dubna141980Russia Kent State University KentOhio 44242USA University of Kentucky LexingtonKentucky40506-0055USA Institute of Modern Physics LanzhouChina Lawrence Berkeley National Laboratory BerkeleyCalifornia 94720USA Massachusetts Institute of Technology CambridgeMA 02139-4307USA Mx-Planck-Institut fir Physik MunichGermany Michigan State University East LansingMichigan 48824USA Moscow Engineering Physics Institute Moscow Russia NIKHEF and Utrecht University AmsterdamThe Netherlands Ohio State University ColumbusOhio 43210USA Old Dominion University NorfolkVA23529USA Panjab University Chandigarh 160014India PennsyIvania State University University ParkPennsylvania 16802USA Institute of High Energy Physics ProtvinoRussia Purdue University West LafayetteIndiana 47907USA Pusan National University PusanRepublic of Korea University of rajasthan Jaipur 302004India rice University HoustonTexas 77251USA Universidade de Sao Paulo Sao PauloBrazil University of Science&Technology of China Hefei 230026.China Shandong University JinanShandong 250100China Shanghai Institute of Applied Physics Shanghai 201800Chi

Dihadron azimuthal correlations containing a high transverse momentum(pr)trigger particle are sensit-ive to the properties of the nuclear medium created at rHIC through the strong interactions occurring between the traversing parton and the medium,*** measurements revealed a strong modification to di-hadron azimuthal correlations in Au+Au collisions with respect to ptp and d+Au *** modification in-creases with the collision centrality,suggesting a path-length or energy density dependence to the je-quenching *** paper reports STAr measurements of dihadron azimuthal correlations in mid-central(20%-60%)Au+Au collisions at√^(S)NN=200 GeV as a function of the trigger particle's azimuthal angle relative to the event plane,Ф_(s)=|Ф_(t)-ψ_(Ep)|.The azimuthal correlation is studied as a function of both the trigger and associated particle *** subtractions of the combinatorial background and anisotropic flow,assuming Zero Yield At Minimum(ZYAM),are *** correlation results are first discussed with subtraction of the even harmonic(elliptic and quadrangu-lar)flow *** away-side correlation is strongly modifed,and the modification varies withФ_(s),with a double-peak structure for out-of-plane trigger *** near-side ridge(long range pseudo-rapidity△_(η)correla-tion)appears to drop with increasingФ_(s)while the jet-like component remains approximately *** correla-tion functions are further studied with the subtraction of odd harmonic triangular flow background arising from *** is found that the triangular flow,while responsible for the majority of the amplitudes,is not sufficient to explain theφs-dependence of the ridge or the away-side double-peak *** dropping ridge withФ_(s)could be attributed to aФ_(s)-dependent lliptie anisotropy;however,the physics mechanism of the ridge remains an open *** with aФ_(s)-dependent elliptic flow,the away-side correlation structure

关键词： relativistic heavy ion collisions dihadron correlations jet-medium interactions anisotropic flow background event plane

The design of a laboratory apparatus to simulate the dust generated by longwall shield advances

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International Journal of Coal Science & Technology 2019年第4期6卷 577-585页

作者： Michael r.Shahan William randolph reed CDC NIOSH PittsburghPA 15236USA

A laboratory apparatus (shield dust simulator) was designed and constructed to simulate the dust generated during the advance of longwall hydraulic roof supports,or *** objective of the study was to develop a tool that could be used to test the hypothesis that foam applied to a mine roof prior to a shield advance could be used to reduce the respirable dust generated during shield *** paper will outline the design parameters for the development of thesystem,as well as describe baseline testing of coal and limestone *** show that the average instantaneous respirable dust concentrated during simulated shield *** intervals were calculated from the instantaneous respirable dust data to determine the repeatability of the data produced by the device.

关键词： Coal mining Longwall shields Dust control

Laboratory results of foam application testing for longwall shield dust control in a simulated environment

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International Journal of Coal Science & Technology 2021年第2期8卷 217-227页

作者： W.r.reed M.r.Shahan Y.Zheng A.Mazzella CDC-NIOSH PittsburghPAUSA

There were 37 longwall faces operating in mines in the United States in *** average panel width for these longwalls was approximately 368.5 m(1209 ft).This translates to a range of approximately 170-240 shields per longwall,depending upon the width of *** movement of longwall shields is a significant contributor to respirable dust overexposures to longwall *** is expected to have the potential to reduce this shield dust *** foam is applied to the area on the roof between the coal face and the shield tip after the shearer *** this study,the longwall shield dust simulator was used to test three foam agents for their ability to control dust from longwall shield *** showed that at low-velocity ventilation(≈3.0 m/s(600 fpm))all foam agents were able to produce dust reduction levels of at least 45%.At high-velocity ventilation(≈5.1 m/s(1000 fpm)),the reductions were lower and more variable,ranging from being undeterminable for one foam agent to having 46%-63%reductions for the other two foam agents,with one instance of an increase in dust ***,the use of foam agents can provide longwall shield dust *** factors are roof coverage and the ability of foam to remain on the roof for extended time periods.

关键词： Longwall Shields Foam respirable Dust Silica Dust

Coal pillar design when considered a reinforcement problem rather than a suspension problem

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International Journal of Mining Science and Technology 2018年第1期28卷 11-19页

作者： russell Frith Guy reed Mine Advice Pty Ltd New South Wales 2282Australia

Current coal pillar design is the epitome of suspension design.A defined weight of unstable overburden material is estimated, and the dimensions of the pillars left behind are based on holding up that material to a prescribed factor of *** principle, this is no different to early roadway roof support ***, for the most part, roadway roof stabilisation has progressed to reinforcement, whereby the roof strata is assisted in supporting *** is now the mainstay of efficient and effective underground coal *** and reinforcement are fundamentally different in roadway roof stabilisation and lead to substantially different requirements in terms of support hardware characteristics and their *** suspension, the primary focus is the total load-bearing capacity of the installed support and ensuring that it is securely anchored outside of the unstable roof *** contrast, reinforcement recognises that roof de-stabilisation is a gradational process with ever-increasing roof displacement magnitude leading to ever-reducing *** roof support characteristics relate to such issues as system stiffness, the location and pattern of support elements and mobilising a defined thickness of the immediate roof to create(or build) a stabilising strata *** objective is to ensure that horizontal stress is maintained at a level that prevents mass roof *** paper presents a prototype coal pillar and overburden system representation where reinforcement, rather than suspension, of the overburden is the stabilising mechanism via the action of in situ horizontal *** roadway roof reinforcement principles can potentially be applied to coal pillar design under this *** merit of this is evaluated according to failed pillar cases as found in a series of published *** on the findings, a series of coal pillar system design considerations for bord and pillar type mine workings are ***

关键词： Coal pillar design Overburden stability rock reinforcement Bord and pillar mining

Limitations and potential design risks when applying empirically derived coal pillar strength equations to real-life mine stability problems

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International Journal of Mining Science and Technology 2019年第1期29卷 17-25页

作者： russell Frith Guy reed Mine Advice Pty Ltd

The method of determining coal pillar strength equations from databases of stable and failed case histories is more than 50 years old and has been applied in different countries by different researchers in a range of mining situations. While common wisdom sensibly limits the use of the resultant pillar strength equations and methods to design scenarios that are consistent with the founding database, there are a number of examples where failures have occurred as a direct result of applying empirical design methods to coal pillar design problems that are inconsistent with the founding database. This paper explores the reasons why empirically derived coal pillar strength equations tend to be problem-specific and should be considered as providing no more than a pillar strength ‘‘index." These include the non-consideration of overburden horizontal stress within the mine stability problem, an inadequate definition of supercritical overburden behavior as it applies to standing coal pillars, and the non-consideration of overburden displacement and coal pillar strain limits. All of which combine to potentially complicate and confuse the back-analysis of coal pillar strength from failed cases. A modified coal pillar design representation and model are presented based on coal pillars acting to reinforce a horizontally stressed overburden, rather than suspend an otherwise unstable self-loaded overburden or section, the latter having been at the core of historical empirical studies into coal pillar strength and stability.

关键词： Coal pillar design Pillar strength Overburden mechanics Limitations of pillar design

Effects of dust controls on respirable coal mine dust composition and particle sizes:case studies on auxiliary scrubbers and canopy air curtain

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International Journal of Coal Science & Technology 2024年第3期11卷 86-101页

作者： F.Animah C.Keles W.r.reed E.Sarver Department of Mining and Minerals Engineering Virginia Polytechnic Institute&State UniversityBlacksburgVAUSA National Institute of Occupational Safety and Health(NIOSH) PittsburghPAUSA

Control of dust in underground coal mines is critical for mitigating both safety and health *** decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effectiveness of various dust control technologies in coal *** studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains(CACs)to reduce respirable dust in key operator *** detailed dust characterization was not a focus of such studies,this is a growing area of *** preserved filter samples from three previous NIOSH studies,the current work aims to explore the effect of two different scrubbers(one wet and one dry)and a roof bolter CAC on respirable dust composition and particle size *** this,the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive *** indicate that dust composition was not appreciably affected by either scrubber or the ***,the wet scrubber and CAC appeared to decrease the overall particle size *** an effect of the dry scrubber was not consistently observed,but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return *** from the insights gained with respect to the three specific dust control case studies revisited here,this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.

关键词： respirable dust Dust control SEM–EDX Scrubber Canopy air curtain Silica

A causation mechanism for coal bursts during roadway development based on the major horizontal stress in coal:Very specific structural geology causing a localised loss of effective coal confinement and Newton’s second law

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International Journal of Mining Science and Technology 2020年第1期30卷 39-47页

作者： russell Frith Guy reed Aaron Jones Mine Advice Pty Ltd BeresfieldNew South Wales 2322Australia

In 2017,one of the international authorities on coal bursts,Mark Christopher,published a paper entitled"Coal bursts that occur during development:A rock mechanics enigma",in which several relevant technical issues were *** paper outlines what is considered to be a credible,first-principles,mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of"constraint"to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ,albeit on a statistically very rare *** basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales,Australia,in 2014 and from the Sunnyside District in Utah,the United ***"cause and effect"model for development of coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events,being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst *** model could also form the basis for a robust,riskbased approach utilising a"hierarchy of controls",to the operational management of the development coal burst ***,the use of pre-mining predictions for likely burst-prone and non-burstprone areas,the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate,and finally the development of an operational Trigger Action response Plan(TArP)that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place.

关键词： Development coal burst Wing-cracks Austar Mine Sunnyside Mine Major horizontal stress in coal

Fundamental principles of an effective reinforcing roof bolting strategy in horizontally layered roof strata and areas of potential improvement

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International Journal of Mining Science and Technology 2018年第1期28卷 67-77页

作者： russell Frith Guy reed Martin McKinnon Mine Advice Pty Ltd New South Wales 2282Australia

It is arguable that the development of reinforcing roof bolting systems has largely stagnated in recent times, primarily due to the prevailing industry view that few, if any, further improvements can be made to what currently ***, this paper contends that reinforcing roof bolting systems can be further refined by considering both the specific manner by which horizontally bedded roof strata loses its natural self-supporting ability and the specific means by which reinforcing roof bolts act to promote or retain this natural self-supporting *** Australian coal industry has insisted on minimising bolt-hole diameter to maximise load transfer and on targeting full-encapsulation by any means necessary for many *** has led to a significant, albeit unintended, consequence in terms of overall roof bolting effectiveness, namely increased resin pressures during bolt installation and the associated potential for opening bedding planes that may have, otherwise, remained closed during the bolt installation *** that the natural self-supporting ability of roof strata is strongly linked to whether bedding planes are open or closed, logically, minimising resin pressures should be a significant *** paper focuses primarily on three key issues that relate directly to the function of the roof bolting system itself:(1) the importance of proper resin mixing in the context of maximising load transfer strength and stiffness,(2) the importance of minimising resin pressures developed during bolt installation, and(3) the importance of maximising the effectiveness of the available bolt *** mine operators should be invested in improving the individual effectiveness of each installed roof bolt, even by relatively small incremental amounts, so this is an important topic for discussion within the mining community.

关键词： roof bolts Strata reinforcement Partial-encapsulation Pre-tension resin mixing Improved bolt effectiveness

An assessment of coal pillar system stability criteria based on a mechanistic evaluation of the interaction between coal pillars and the overburden

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International Journal of Mining Science and Technology 2017年第1期27卷 9-15页

作者： reed Guy Mctyer Kent Frith russell Mine Advice Pry Ltd NewcastleNSW 2322Australia

Coal pillar design has historically assigned a factor of safety(Fo S) or stability factor(SF) according to their estimated strength and the assumed overburden load acting on them. Acceptable Fo S values have been assigned based on past mining experience or a statistical link between Fo S and probability of failure(Po F). Pillar width-to-height(w/h) ratio has long been established as having a material influence on both pillar strength and its potential failure mode. However, there has been significant disagreement on using both factor of safety(Fo S) and w/h as part of pillar system stability criterion, as compared to using Fo S in isolation. This paper will argue that there are valid technical reasons to bring w/h ratio into system stability criteria(other than its influence on pillar strength), as it is related to the post-failure stiffness of the pillar, as measured in situ, and its interaction with overburden stiffness. When overburden stiffness is also brought into pillar system stability considerations, two issues emerge. The first is the width-todepth(W/D) ratio of the panel and whether it is sub-critical or super-critical from a surface subsidence perspective. The second relates to a re-evaluation of pillar Fo S based on whether the pillar is in an elastic or non-elastic(i.e., post-yield) state in its as-designed condition, as this is relevant to maintaining overburden stiffness at the highest possible level. The significance of the model is the potential to maximise both reserve recovery and mining efficiencies without any discernible increase in geotechnical risk, particularly in thick seams and higher depth of cover mining situations. At a time when mining economics are, at best, marginal, removing potentially unnecessary design conservatism is of interest to all mine operators and is an important topic for discussion amongst the geotechnical community.

关键词： Coa] pillars Stability Overburden Post-failure behaviour Stability criteria