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Pillar design and coal burst experience in Utah Book Cliffs longwall operations

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International Journal of Mining Science and Technology 2021年第1期31卷 33-41页

作者： Christopher Mark michael gauna Mine Safety and Health Administration Technical Support PittsburghPA 15236USA

Longwall mining has existed in Utah for more than half a *** of this mining occurred at depths of cover that significantly exceed those encountered by most other US longwall *** cover causes high ground stress,which can combine with geology to create a coal burst *** every longwall mine operating within the Utah’s Book Cliffs coalfield has been affected by coal *** design has been a key component in the burst control strategies employed by mines in the Book ***,most longwall mines employed double-use two-entry yield pillar ***-use signifies that the gate system serves first as the headgate,and then later serves as the tailgate for the adjacent *** the 1996 burst fatality at the Aberdeen Mine,the inter-panel barrier design was *** this layout,a wide barrier pillar protects each longwall panel from the previously mined panel,and each gate system is used just *** paper documents the deep cover longwall mining conducted with each type of pillar design,together with the associated coal burst *** of the six longwall mining complexes in the Book Cliffs having a coal burst history is described on a panel-by-panel *** analysis shows that where the mining depth exceeded 450 m,each design has been employed for about 38000 total m of longwall panel *** double-use yield pillar design has been used primarily at depths less than 600 m,however,while the inter-panel barrier design has been used mainly at depths exceeding 600 *** its greater depth of use,the inter-panel barrier gate design has been associated with about one-third as much face region burst activity as the double-use yield pillar design.

关键词： Longwall ground control Coal burst Pillar design Yield pillar

A negative feedback loop controls ROS production in plant immunity

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Molecular Plant 2021年第8期14卷 1221-1222页

作者： michael Wrzaczek Institute of Plant Molecular Biology Biology CentreCzech Academy of Sciences37005 Ceske BudejoviceCzech Republic Organismal and Evolutionary Biology Research Programme Viikki Plant Science CentreUniversity of Helsinki00014 HelsinkiFinland

Over the past two decades the view of reactive oxygen species(ROS)as merely cytotoxic compounds has changed considerably(Waszczak et al.,2018).While still being considered as reactive chemicals with potentially devastating detrimental effects,ROS have been shown to be used by plants and animals alike as messengers in numerous signaling networks,including responses to biotic and abiotic environmental cues as well as developmental processes(Waszczak et al.,2018;Zandalinas et al.,2020).

关键词： immunity chemicals numerous

Neural differentiation protocols:how to choose the correct approach

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Neural Regeneration Research 2023年第6期18卷 1273-1274页

作者： michael Telias Flaum Eye Institute University of RochesterRochesterNYUSA

Pluripotent stem cells in neural differentiation:characterization and potential:The establishment and use of pluripotent stem cells(PSCs),including embryonic(ESCs)and induced(iPSCs),constitutes a major scientific breakthrough of the last *** PSCs hold the potential to deliver regenerative therapies in many diseases,including neurological *** general approach is to produce functioning human neurons and glial cells in vitro,to be later implanted in the diseased nervous system,replacing dysfunctional or dead *** addition,human and other animal-sourced PSCs make useful and dynamic in vitro models for neurodevelopmental,neurodegenerative and psychiatric disorders,enabling researchers to continuously produce normal and diseased neurons to investigate basic mechanistic questions,which can eventually lead to new ***,the development of efficient protocols to induce neural differentiation in ESCs and iPSCs is currently a major effort in the field(Mertens et al.,2016).

关键词： eventually breakthrough approach

PERTURBATIONS OF ZEROS OF SOLUTIONS TO SECOND ORDER DIFFERENTIAL EQUATIONS WITH POLYNOMIAL COEFFICIENTS

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Acta Mathematica Scientia 2012年第3期32卷 1083-1092页

作者： michael gil' Department of Mathematics Ben Gurion University of the NegevP.O.Box 653Beer-Sheva 84105Israel

Let P（z） and P（z） be polynomials of the same degree. We consider the equations u＂ = P（z）u and u＂ = P（z）u （z ∈ C） whose solutions are u（z） and u（z）, respectively. Let Zk（U） and zk（u）, k = 1, 2,..., be the zeros of u（z） and u（z）, respectively. We derive bounds for the quantity sup j inf k｜1/zk（u）-1/zj（u）｜

关键词： Complex differential equation zeros of solutions perturbation of zeros

Towards a unified classification of wear

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Friction 2013年第4期1卷 333-340页

作者： michael VARENBERg Department of Mechanical Engineering Technion-IITHaifa 32000Israel

Since the beginning of the systematic study of wear,many classification schemes have been ***,though covering the whole field in sum,they stay only loosely connected to each other and do not build a complete general *** this end,here we try to combine and integrate existing approaches into a general simple scheme unifying known wear types into a consistent *** suggested scheme is based on three classifying criterions answering the questions“why”,“how”and“where”and defining a 3-D space filled with the known wear *** system can be used in teaching to introduce students to such complex phenomena as wear and also in engineering practice to guide wear mitigation initiatives.

关键词： relative motion energy dissipation surface disturbance surface state surface damage

A study on turbulence modulation via an analysis of turbulence anisotropy-invariants

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Science China(Physics,Mechanics & Astronomy) 2010年第3期53卷 508-513页

作者： michael MANHART Fachgebiet Hydromechanik Technische Universitaet Muechen Munich 80333 Germany

We investigate the turbulence modulation by particles in a turbulent two-phase channel flow via an analysis of turbulence anisotropy-invariants. The fluid turbulence is calculated by a large eddy simulation with a point-force two-way coupling model and particles are tracked by the Lagrangian trajectory method. The channel turbulence follows the two-component turbulence state within the viscous sub-layer region and outside the region the turbulence tends to follow the right curve of the anisotropy-invariant. The channel turbulence, interacting with heavy particles, is modulated to the two-component turbulence limit state near the wall and is separate from the axisymmetric turbulence state in the turbulence anisotropy-invariants map. The fluctuations of streamwise component are transferred to the other two components and hence the anisotropy decreases due to particle modulation. The study has deepened the understanding of the turbulence modulation mechanism in two-phase turbulent flows.

关键词： turbulence modulation turbulence anisotropy turbulent two-phase channel flow large eddy simulation two-way coupling

Biodiversity and taphonomy of the Early Cambrian guanshan biota,eastern Yunnan

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Science China Earth Sciences 2010年第12期53卷 1765-1773页

作者： michael STEINER Freie Universitt Berlin D-12249 BerlinGermany

The guanshan biota from eastern Yunnan(Cambrian Series 2,early Stage 4) is a Burgess Shale-type fossil biota with abundant exceptionally preserved soft-bodied fossils after the discovery of the well-known Cambrian Chengjiang fauna and Kaili biota in South *** geological settings,sedimentology,taphonomy,and the fossil assemblage of the guanshan biota are briefly summarized *** guanshan biota consists of about 60 taxa belonging to more than 10 metazoan groups and algae,among which the lobopods,eldonids,hyolithids with helens,and green algae are reported for the first *** common occurrence of soft-bodied preservation in many groups,notably the trilobites and brachiopods,makes the guanshan biota a significant fossil lagersttte for understanding the metazoan evolution during Cambrian explosion and taphonomy of the Burgess Shale-type fossils.

关键词： soft-bodied fossils guanshan biota Cambrian Cambrian Explosion Burgess Shale-type preservation

Subsets of Euclidean Space with Nearly Maximal gowers Norms

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Acta Mathematica Sinica,English Series 2019年第6期35卷 771-782页

作者： michael CHRIST Department of Mathematics University of CaliforniaBerkeley

A set E ? R^d whose indicator function 1_E has maximal gowers norm, among all sets of equal measure, is an ellipsoid up to Lebesgue null sets. If 1_E has nearly maximal gowers norm then E nearly coincides with some el... 详细信息

关键词： Symmetrization gowers norms maximizers

Near Equality in the Riesz–Sobolev Inequality

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Acta Mathematica Sinica,English Series 2019年第6期35卷 783-814页

作者： michael CHRIST Department of Mathematics University of CaliforniaBerkeley

The Riesz–Sobolev inequality provides a sharp upper bound for a trilinear expression involving convolution of indicator functions of sets. Equality is known to hold only for indicator functions of appropriately situated intervals. We characterize ordered triples of subsets of R^1 that nearly realize equality, with quantitative bounds of power law form with the optimal exponent.

关键词： Riesz–Sobolev inequality Freǐman’s theorem