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Acta Mechanica Sinica 2010年第4期26卷 567-572页

作者： D.J.Colquitt A.B.Movchan I.S.Jones w.daniels Department of Mathematical Sciences University of Liverpool School of Engineering John Moores University Serco Assurance walton House 404 The QuadrantBirchwood ParkRisleyWarringtonCheshireWA3 6GAUK

The paper presents a computational model for elastic waves in a structured weld adjacent to the free surface of an elastic solid. The main emphasis is on the interaction of waves with the micro-structure of the weld. Effects of localisation and channeling of waves are addressed. A model of a grain structure within the weld is also considered.

关键词： Macro-structured welds waves in stratified media Dispersion Localisation

VARIATIONAL DISCRETIZATION OF A CONTROL-CONSTRAINED PARABOLIC BANG-BANG OPTIMAL CONTROL PROBLEM

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Journal of Computational Mathematics 2020年第1期38卷 14-40页

作者： Nikolaus von daniels Michael Hinze Schwerpunkt Optimierung und Approximation Universitat HamburgBundesstrase 5520146 HamburgGermany

we consider a control-constrained parabolic optimal control problem without Tikhonov term in the tracking *** the numerical treatment,we use variational discretization of its Tikhonov regularization:For the state and the adjoint equation,we apply Petrov-Galerkin schemes in time and usual conforming finite elements in *** prove a-priori estimates for the error between the discretized regularized problem and the limit *** these estimates are not robust if the regularization parameter tends to zero,we establish robust estimates,which--depending on the problem's regularity——enhance the previous *** the special case of bang-bang solutions,these estimates are further improved.A numerical example confirms our analytical findings.

关键词： Optimal control Heat equation Control constraints Finite elements A-priori error estimates Bang-bang controls

Predicting release and aquatic effects of total dissolved solids from Appalachian USA coal mines

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International Journal of Coal Science & Technology 2014年第2期1卷 152-162页

作者： w.L.daniels C.E.Zipper Z.w.Orndorff Department of Crop and Soil Environmental Sciences Virginia TechBlacksburgVA 24061USA

Appalachian USA coal mines have been implicated as major stressors to aquatic life in headwater streams via discharge of total dissolved solids(TDS).This paper summarizes column leaching studies of spoils(n>50)and refuse and TDS effects on local water quality and biotic *** initial pH of most materials is *** specific conductance(SC)values range from 500-1,000 to >3,000 μs/cm,but 2/3 of materials drop below 500 ls/cm after several pore volumes of *** of mining-influenced streams have found altered aquatic life,relative to natural conditions with no mining influence,at SC ranging from-200 to-700 ls/cm with depressed aquatic life consistently associated with elevated TDS;mechanisms causing such effects are under *** suggest that active mine operations should be modified to place high TDS producing materials in ways that reduce contact with percolating drainage waters.

关键词： Mine spoil weathering-Acid base accounting water quality Valley fills

A 15-year-Long catalog of seismicity in the Eastern Tennessee Seismic Zone(ETSZ)using matched filter detection

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Earthquake Research Advances 2023年第1期3卷 92-105页

作者： Clara daniels Zhigang Peng School of Earth and Atmospheric Sciences Georgia Institute of TechnologyAtlanta311 Ferst DrAtlantaGA30318USA Applied Research Associates BurlingtonMAUSA

we present a detailed catalog of 13671 earthquakes in the Eastern Tennessee Seismic Zone(ETSZ)that spans January 1,2005 to July 31,*** apply a matched filter detection technique on over 15 years of continuous data,resulting in arguably the most complete catalog of seismicity in the ETSZ *** magnitudes of newly detected events are determined by computing the amplitude ratio between the detections and templates using a principal component *** also compute the b-value for the new catalog and comparatively relocate a subset of newly detected events using XCORLOC and hypoDD,which shows a more defined structure at *** find the greatest concentration along and to the east of the New York-Alabama Lineament,as defined by the magnetic anomaly,supporting the argument that this feature likely is related to the generation of seismicity in the *** examine seismicity in the vicinity of the watts Bar Reservoir,which is located about 5 km from the epicenter of the M_(w) 4.4 December 12,2018 Decatur,Tennessee earthquake,and find possible evidence for reservoir modulated seismicity in this *** also examine seismicity in the entire ETSZ to search for a correlation between shallow earthquakes and seasonal hydrologic *** results show limited evidence for hydrologicallydriven shallow seismicity due to seasonal groundwater levels in the ETSZ,which contradicts previous studies hypothesizing that most intraplate earthquakes are associated with the dynamics of hydrologic cycles.

关键词： Eastern Tennessee Seismic Zone Matched filter detection Intraplate earthquakes Reservoir modulated seismicity

Electron Density and Optical Emission Measurements of SF_6/O_2 Plasmas for Silicon Etch Processes

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Plasma Science and Technology 2012年第4期14卷 316-320页

作者： M.M.MORSHED S.M.daniels National Centre for Plasma Science and Technology School of Electronic EngineeringDublin City UniversityGlasnevinDublin 9Ireland

This work investigates internal plasma process parameters using a hairpin resonance probe and optical emission spectroscopy. The dependence of electron density and atomic fluorine on the percentage of oxygen in an SF6/O2 discharge was measured using these methods. An RIE Oxford Instruments 80 plus chamber was used for the experiments. Two different process powers （100 w and 300 w） at a constant pressure （100 mTorr） were used, and it was found that the optical emission intensity of the 703.7 nm and 685.6 nm lines of atomic fluorine increased rapidly as oxygen was added to the SF6 discharge, reached their maximum at an O2 fraction of 20% and then decreased with further addition of oxygen. The plasma electron density was also strongly influenced by the addition of O2.

关键词： OES hairpin probe SF6 O2 electron density atomic fluorine

Plasma Treatment of Natural Jute Fibre by RIE 80 plus Plasma Tool

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Plasma Science and Technology 2010年第3期12卷 325-329页

作者： M.M.MORSHED M.M.ALAM S.M.daniels National Centre for Plasma Science and Technology Dublin City University Nanomaterials Processing Laboratory School of Electronic EngineeringDublin City University

Plasma treatment can be used to modify the structure of natural fibre like jute for a variety of applications. Environmentally friendly jute fibre was treated with argon and oxygen plasma. The treated samples were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR） and optical microscope. The macromolecular and microstructural changes in cellulose confirmed the change by plasma treatment. The XRD results confirmed that the crystal size and the crystallinity of the plasma treated fibre increased. Argon plasma treated fibre had a smooth and compact surface, compared to oxygen plasma treated fibre. The maximum stain （i.e. stress） concentrated in the oxygen plasma treated fibre. Optical micrographs showed the oxygen plasma treated fibre tended to rupture due to higher strain （i.e., stress） compared to fibre with argon plasma treatment. FTIR results also provided the evidence of change in the chemical constituents with plasma treatment.

关键词： natural jute fibre plasma treatment crystallinity chemical composition

Environmental issues from coal mining and their solutions

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Mining Science and Technology 2010年第2期20卷 215-223页

作者： BIAN, Zhengfu INYANG, Hilary I daniels, John L OTTO, Frank STRUTHERS, Sue institute of land resources china university of mining & technologyxuzhou 221008china global institute for energy and environmental systems university of north carolinacharlotte nc 28223usa global institute for energy and environmental systems university of north carolinacharlotte nc 28223usa natural science foundation of the usa arlington va 22230usa department of geoengineering and mining university of applied sciencebochum 44801germany skapa mining services orkney kw172sxuk

The environmental challenges from coal mining include coal mine accidents,land subsidence,damage to the water environment,mining waste disposal and air *** are either environmental pollution or landscape change.A conceptual framework for solving mine environmental issues is *** processes,or remediation measures,are designed to address environmental *** measures are proposed to handle landscape *** total methane drainage from 56 Chinese high methane concentration coal mines is about 101.94 million cubic *** this methane,19.32 million,35.58 million and 6.97 million cubic meters are utilized for electricity generation,civil fuel supplies and other industrial purposes,*** 39% of the methane is emitted into the *** production of coal mining wastes can be decreased 10% by reuse of mining wastes as underground fills,or by using the waste as fuel for power plants or for raw material to make bricks or other infrastructure *** proper use of mined land must be decided in terms of local physical and socio-economical *** European countries more than 50% of previously mined lands are reclaimed as forest or grass ***,in China more than 70% of the mined lands are reclaimed for agricultural purposes because the large population and a shortage of farmlands make this *** of rural communities or native residential improvement is one environmental problem arising from *** suggest two ways to reconstruct a farmer's house in China.

关键词： mine environment management of mining wastes reuse of mine gas mined land reclamation clean coal mining

Polarization reversal via a transient relaxor state in nonergodic relaxors near freezing temperature

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Journal of Materiomics 2019年第4期5卷 634-640页

作者： Chang-Hyo Hong Hanzheng Guo Xiaoli Tan John E.daniels wook Jo School of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan44919Republic of Korea Department of Materials Science and Engineering Iowa State UniversityAmesIA50011USA School of Materials Science and Engineering University of New South WalesNew South Wales2052Australia

Among the unresolved issues in the study of relaxor ferroelectrics is the role of freezing temperature,across which the dynamics of polarization reversal in relaxor ferroelectrics *** presence of this freezing temperature is best manifested by the appearance of a double polarization hysteresis loop just above the freezing *** that the polarization pinching evolving into a double hysteresis starts well below the freezing temperature,there exists a transient temperature regime between the nonergodic and the ergodic relaxor *** clarify the role of the freezing temperature on the pinching,the polarization reversal near the freezing temperature of relaxor(Pb_(1-x)La_(x))(Zr_(1-y)T_(y))_(1-x/4)O_(3)(PLZT)was monitored using three in situ electric field methods:electrocaloric effect,neutron diffraction,and transmission electron *** demonstrate that the pinching results from a two-step process,1)domain detexturization in the ferroelectric state and 2)miniaturization of *** observation explains the recently reported gap between the depolarization temperature T_(d) and the ferroelectric-torelaxor transition temperature T_(F-R) in lead-free *** further show that T_(d) and T_(F-R),which have long been considered identical in lead-based relaxors,are not the *** current study suggests that the mismatch between T_(d) and TF-R is an inherent feature in both lead-based and lead-free relaxor ferroelectrics.

关键词： Relaxor Nanodomains In situ Neutron diffraction Transmission electron microscopy

South Africa＇s Media Freedom Landscape and the Closures in Democracy

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Journalism and Mass Communication 2015年第1期5卷 9-19页

作者： Glenda daniels University of witwatersrand Johannesburg South Afi'ica

This research uses a theoretical conceptual method based on Chantal Mouffe＇s Radical Democracy which blended with Derrida＇s deconstruction thesis about ＂democracy to come＂ to reach findings on the state of South Africa＇s media freedom landscape. The method is contained in the conceptual framework. The article provides the constitutional legal landscape--or the overarching laws of the land--and the co-regulatory framework within which journalists work. There are four research explications： the Protection of State Information Bill （dubbed the Secrecy Bill）, a painting of the president and Freedom of Expression, an arson attack on a community radio station and finally, the death of a photojournalist at the hands of police. The argument here is that the death, the arson attack, the Secrecy Bill, and the shut-down of dissent during the exhibition of the painting of the president all undermine democracy and signify significant closures for the media in the now 20-year-old post-apartheid South Africa. The analysis and reflections will be framed within theories of radical democracy, which argue for more fights and contestations and more voices from the margins in order to deepen democracy, rather than rational consensus which closes the spaces for greater plurality.

关键词： radical democracy media freedom of expression secrecy closures aporias