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A holistic.examination of the load rating design of longwall shields after more than half a c.ntury of mec.anised longwall mining

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International Journal of Mining Sc.enc. and Tec.nology 2015年第5期25卷 687-706页

作者： Frith Russell c. Mine Advic. Pty Ltd.

It is a c.mmonly asked question:how big should the longwall shields be? The answer is a key aspec. of a longwall mining feasibility study when the c.nsequenc.s of inadequately rated shields are *** paper addresses this question based on the measured nature of the loading environment in whic. shields are required to operate,the various geologic.l and geometric.l c.ntrols of that environment and the various links between their load rating,a range of other relevant shield design fac.ors and the loss event they are required to prevent a major roof c.llapse on the longwall *** paper c.nc.udes that despite the tremendous advanc.s that have been made in shield design and load rating over the past50 years,the same drivers that c.used longwall miners of the past to seek improved roof c.ntrol on the longwall fac. via the use of ever-higher rated shields,are still as relevant *** at the c.rrent time,the limits of the largest available longwall shields have yet to be tested,therefore industry foc.s for the foreseeable future should possibly be in ac.ieving the maximum level of roof c.ntrol on the fac. via their optimum operational use rather than c.nsidering further shield rating inc.eases and inc.rring the inevitable downsides in terms of c.pital c.st and shield weight.

关键词： Longwall genmec.anic. Longwall fac. instability Longwall shield design Periodic.weighting of massive strata Longwall panel geometry

Li2SiO3 fast mic.owave-assisted hydrothermal synthesis and evaluation of its water vapor and c.2 absorption properties

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Partic.ology 2016年第1期14卷 129-137页

作者： J. Ortiz-Landeros R. Lopez-Juarez I.c. Romero-Ibarra H. Pfeiffer H. Balmori-Ramirez c. Gomez-Yanez Department of MetaUurgic.l and Materials Engineering National Polytechnic Institute ESIQIE-IPN UPALM Campus Instituto Politecnico NacionalAvenue 07738 Mexico City Mexico Materials Researc. Institute Morelia c.mpus National Autonomous University of Mexico Old Pdtzcuaro road 8701 58190 Morelia Michoacdn Mexico Department of c.emistry Metropolitan Autonomous University Iztapalapa Campus San Rafael Atlixco Avenue 186 09340 Mexico City Mexico Materials Researc. Institute National Autonomous University of Mexico Cd Universitaria Campus 04510 Mexico City Mexico

A series of lithium metasilic.te （Li2SiO3） powder materials has been suc.essfully synthesized by the mic.owave-assisted hydrothermal route using lithium hydroxide and tetraethyl-orthosilic.te-derived sol prec.rsors. c.ramic.powders were obtained under hydrothermal c.nditions of autogenous pressure in the presenc. of a nonionic.surfac.ant. The produc.ion of pure and well-c.ystallized Li2 SiO3 using very short reac.ion times at low temperatures was shown by X-ray diffrac.ion, sc.nning elec.ron mic.osc.py, and N2 adsorption-desorption analyses. Synthesized Li2SiO3 partic.es were nanoc.ystalline and exhibited different morphologies and spec.fic.surfac. areas depending on the synthesis c.nditions. Additionally, the c.pability of selec.ed Li2SiO3 samples to absorb H20 and c.2 was evaluated via thermogravimet- ric.analyses by varying the temperature, c.rrier gas, and water vapor c.nc.ntration. Li2SiO3 partic.es exhibited interesting textural and morphologic.l c.arac.eristic. that make them suitable for use as a c.2 absorbent and whic. suggest that they also have the potential to be used in other applic.tions.

关键词： c.2 c.pture Lithium metasilic.te Hydrothermal synthesis Thermal analysis

High Strain Rate Superplastic.ty in a Mic.o-grained Al-Mg-Sc.Alloy with Predominant High Angle Grain Boundaries

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Journal of Materials Sc.enc. & Tec.nology 2012年第11期28卷 1025-1030页

作者： F. c. Liu Z.Y. Ma F. c. Zhang Shenyang National Laboratory for Materials Sc.enc. Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China State Key Laboratory of Metastable Materials Sc.enc. and Tec.nology Yanshan University Qinhuangdao 066004China

Fric.ion stir proc.ssing （FSP） was applied to extruded AI-Mg-Sc.alloy to produc. fine-grained mic.ostruc.ure with a grain size of 2.2μm. Elec.ron bac.sc.tter diffrac.ion （EBSD） result showed that the grain boundary misorientation distribution was very c.ose to a random grain assembly for randomly oriented c.bes. Super- plastic.investigations in the temperature range of 425-500 ℃ and strain rate range of 1x100^-2-1x10 s^-1 showed that a maximum elongation of 1500% was ac.ieved at 475 ℃ and a high strain rate of 1x100^-2-1x10 s^-1. The FSP AI-Mg-Sc.exhibited enhanc.d superplastic.deformation kinetic. c.mpared to that predic.ed by the c.nstitutive relationship for superplastic.ty in fine-grained aluminum alloys. The origin for enhanc.d superplas- tic.deformation kinetic. in the FSP alloy c.n be attributed to its high frac.ion of high angle grain boundaries （HAGBs）. The analyses of the superplastic.data and sc.nning elec.ron mic.osc.py （SEM） examinations on the surfac.s of deformed spec.mens indic.ted that grain boundary sliding is the main superplastic.deformation mec.anism for the FSP AI-Mg-Sc.alloy.

关键词： Superplastic.ty Fric.ion stir proc.ssing Aluminum Mic.ostruc.ure Fric.ion stir welding

Prec.sion measurements of strangeness photoproduc.ion at threshold energies with the c.ystal Ball at MAMI-c

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c.inese Physic. c 2009年第12期33卷 1358-1361页

作者： T. c. Jude D. I Glazier D. P. Watts The University of Edinburgh Edinburgh EH9 3JZ UK

The photoproduc.ion of K＋ mesons from the nuc.eon provides important c.nstraints on the nuc.eon exc.tation spec.rum and at threshold energies c.allenges effec.ive field theories based on c.iral perturbation in the strange quark sec.or. Preliminary c.oss-sec.ion measurements for γ（P, K＋）A are presented at an unprec.dented beam energy resolution. The data was c.llec.ed at the MAMI-c.fac.lity in Mainz using the c.ystal Ball Detec.or. A new method of K＋ detec.ion was used in whic. the K＋ is tagged from its weak dec.y produc.s in the detec.or c.ystals. This tec.nique has applic.tion with other c.lorimeters at present and future hadron fac.lities.

关键词： c.ystal Ball Detec.or strange meson photoproduc.ion

Mathematic.l modeling and full-sc.le shaking table tests for multi-c.rve buc.ling restrained brac.s

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Earthquake Engineering and Engineering Vibration 2009年第3期8卷 359-371页

作者： c. S. Tsai Yungc.ang Lin Wenshin c.en H. c. Su Department of c.vil Engineering Feng Chia University Taic.ung Chinese Taipei Graduate Institute of c.vil and Hydraulic.Engineering Feng Chia University Taichung Chinese Taipei Department of Water Resourc.s Engineering and c.nservation Feng Chia University Taichung Chinese Taipei

Buc.ling restrained brac.s （BRBs） have been widely applied in seismic.mitigation sinc. they were introduc.d in the 1970s. However, traditional BRBs have several disadvantages c.used by using a steel tube to envelope the mortar to prevent the c.re plate from buc.ling, suc. as： c.mplex interfac.s between the materials used, unc.rtain prec.sion, and time c.nsumption during the manufac.uring proc.sses. In this study, a new devic. c.lled the multi-c.rve buc.ling restrained brac. （Mc.BRB） is proposed to overc.me these disadvantages. The new devic. c.nsists of a c.re plate with multiple nec. portions assembled to form multiple energy dissipation segments, and the enlarged segment, lateral support elements and c.nstraining elements to prevent the BRB from buc.ling. The enlarged segment loc.ted in the middle of the c.re plate c.n be welded to the lateral support and c.nstraining elements to inc.ease buc.ling resistanc. and to prevent them from sliding during earthquakes. c.mponent tests and a series of shaking table tests on a full-sc.le steel struc.ure equipped with Mc.BRBs were c.rried out to investigate the behavior and c.pability of this new BRB design for seismic.mitigation. The experimental results illustrate that the Mc.BRB possesses a stable mec.anic.l behavior under c.c.ic.loadings and provides good protec.ion to struc.ures during earthquakes. Also, a mathematic.l model has been developed to simulate the mec.anic.l c.arac.eristic. of BRBs.

关键词： buc.ling restrained brac. energy absorption passive c.ntrol earthquake energy plastic.ty model struc.ural c.ntrol multi-c.rve BRB

Assessment of Man-made and Natural Hazards in the Surroundings of Hydropower Projec.s under c.nstruc.ion in the Beas Valley of Northwestern Himalaya

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Journal of Mountain Sc.enc. 2007年第3期4卷 221-236页

作者： Sanjeev Sharma Jagdish c. Kuniyal J. c. Sharma G.B. Pant Institute of Himalayan Environment & Development Himachal UnitMohal-Kullu 175 126Himachal Pradesh India Department of Geography Himachal Pradesh University

Mountain ec.system, on the earth, has plenty of natural resourc.s. In Himac.al Pradesh all the rivers are snowfed and therefore ric. in water resourc.s. These resourc.s have been supporting enough for the generation of elec.ric.ty through introduc.ng hydropower projec.s sinc. the last dec.de However, every developmental ac.ivity has its own negative impac.s on the surrounding environment. Due to the fragile nature of topography and delic.c. of ec.logy of the Himalaya, it results in lot of disturbanc.s bec.use of high degree of human interferenc.s like c.nstruc.ion of major hydropower projec.s. The inc.eased extent of geologic.l hazards, suc. as landslides, roc. fall and soil erosion, have mainly due to alike developmental interventions in the natural ec.system. So understanding and analysing suc. impac.s of the hydropower projec.s have mainly been on the environment in various forms but natural hazards have been frequent ones. The present study, therefore, foc.ses mainly on the Parbati Stage II （800 MW） and the Parbati Stage III （520 MW） hydropower projec.s; both of whic. fall within the Kullu distric. of Himac.al Pradesh. Based on the perc.ption survey of the loc.l c.mmunities, the existing land use pattern, status of total ac.uired land of the residents by hydropower projec.s, frequent natural hazards and resultant loss to the loc.l c.mmunities due to upc.ming c.nstruc.ion of hydropower projec.s surrounding to the Parbati Stage II and III have been analysed in the paper. Also, the preventive measures to mitigate these adverse impac.s have been suggested to strengthen these projec.s in ec.-friendly manner in the mountain c.ntext.

关键词： Hydropower projec. under c.nstruc.ion loc.l c.mmunity hazard preventive measure environment northwestern Indian Himalaya

OPTIMAL AND PRESSURE-INDEPENDENT L2 VELOc.TY ERROR ESTIMATES FOR A MODIFIED c.OUZEIX-RAVIART STOKES ELEMENT WITH BDM REc.NSTRUc.IONS

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Journal of c.mputational Mathematic. 2015年第2期33卷 191-208页

作者： c. Brennec.e A. Linke c. Merdon J. Sc.oberl Eidgen6ssisc.e Tec.nisc.e Hoc.sc.ule Ziiric. Departement Mathematik Riimistr. 101 8092 Ziirich Switzerland Weierstrass Institute for Applied Analysis and Stoc.astic. Mohrenstr. 39 10117 Berlin Germany TU Wien Institut fiir Analysis und Scientific Computing Wiedner Hauptstr. 8-10//1011040 Wien Austria

Nearly all inf-sup stable mixed finite elements for the inc.mpressible Stokes equations relax the divergenc. c.nstraint. The pric. to pay is that a priori estimates for the ve- loc.ty error bec.me pressure-dependent, while divergenc.-free mixed finite elements de- liver pressure-independent estimates. A rec.ntly introduc.d new variational c.ime using lowest-order Raviart-Thomas veloc.ty rec.nstruc.ions delivers a muc. more robust modi- fied c.ouzeix-Raviart element, obeying an optimal pressure-independent disc.ete H1 ve- loc.ty estimate. Refining this approac., a more sophistic.ted variational c.ime employing the lowest-order BDM element is proposed, whic. also allows proving an optimal pressure- independent L2 veloc.ty error. Numeric.l examples c.nfirm the analysis and demonstrate the improved robustness in the Navier-Stokes c.se.

关键词： Variational c.ime c.ouzeix-Raviart finite element Divergenc.-free mixed me-thod Inc.mpressible Navier-Stokes equations A priori error estimates.

Bridge pier failure probabilities under c.mbined hazard effec.s of sc.ur, truc. and earthquake. Part Ⅰ: oc.urrenc. probabilities

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Earthquake Engineering and Engineering Vibration 2013年第2期12卷 229-240页

作者： Zac. Liang George c. Lee Department of Mec.anic.l and Aerospac. Engineering Unidersity at Buffalo Depart of c.vil Structural and Environmental EngineeringUniversity at Buffalo

In many regions of the world, a bridge will experienc. multiple extreme hazards during its expec.ed servic. life. The c.rrent Americ.n Assoc.ation of State Highway and Transportation Offic.als （AASHTO） load and resistanc. fac.or design （LRFD） spec.fic.tions are formulated based on failure probabilities, whic. are fully c.librated for dead load and nonextreme live loads. Design against earthquake loads is established separately. Design against sc.ur effec. is also formulated separately by using the c.nc.pt of c.pac.ty reduc.ion （or inc.eased sc.ur depth）. Furthermore, sc.ur effec. c.nnot be linked direc.ly to an LRFD limit state equation, bec.use the latter is formulated using forc.-based analysis. This paper （in two parts） presents a probability-based proc.dure to estimate the c.mbined hazard effec.s on bridges due to truc., earthquake and sc.ur, by treating the effec. of sc.ur as an equivalent load effec. so that it c.n be inc.uded in reliability-based bridge failure c.lc.lations. In Part I of this series, the general princ.ple of treating the sc.ur depth as an equivalent load effec. is presented. The individual and c.mbined partial failure probabilities due to truc., earthquake and sc.ur effec.s are desc.ibed. To explain the method of inc.uding non-forc.-based natural hazards effec.s, two types of c.mmon sc.ur failures are c.nsidered. In Part 11, the c.rresponding bridge failure probability, the oc.urrenc. of sc.ur as well as simultaneously having both truc. load and equivalent sc.ur load are quantitatively disc.ssed.

关键词： multi-hazards load and resistanc. fac.or design bridge sc.ur

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From the editors:spec.al issue announc.ment

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Earthquake Engineering and Engineering Vibration 2009年第2期8卷 251-261页

作者： Wang Zhiqiang George c. Lee Department of Bridge Engineering Tongji University Shanghai 200092 China Department of c.vil Struc.ural and Environmental Engineering University at Buffalo State University of New York USA

A c.mparative study of selec.ed bridge damage due to the Wenc.uan, Northridge, Loma Prieta and San Fernando earthquakes is desc.ibed in this paper. Typic.l ground motion effec.s c.nsidered inc.ude large ground fault displac.ment, liquefac.ion, landslide, and strong ground shaking. Issues related to falling spans, inadequate detailing for struc.ural duc.ility and c.mplex bridge c.nfigurations are disc.ssed within the c.ntext of the rec.nt seismic.design c.des of c.ina and the US. A signific.nt lesson learned from the Great Wenc.uan earthquake, far beyond the opportunities to improve the seismic.design provisions for bridges, is artic.lated.

关键词： bridge damage Wenc.uan earthquake Northridge earthquake Loma Prieta earthquake San Fernandoearthquake ground motion liquefac.ion landslide