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Field topologies in ideal and near-ideal magnetohydrodynamic. and vortex dynamic.

Sc.enc. c.ina(Physic.,Mec.anic. & Astronomy) 2015年第1期58卷 12-31页

作者： LOW b.c. High Altitude Observatory National Center for Atmospheric Research

Magnetic.field topology frozen in ideal magnetohydrodynamic. （MHD） and its breakage in near-ideal MHD are reviewed in two parts, c.arifying and expanding basic.c.nc.pts. The first part gives a physic.lly c.mplete desc.iption of the frozen field topology derived from magnetic.flux c.nservation as the fundamental property, treating four c.nc.ptually related topic.： Eulerian and La- grangian desc.iptions of three dimensional （3D） MHD, c.andrasekhar-Kendall and Euler-potential field representations, magnetic.helic.ty, and invisc.d vortex dynamic. as a fluid system in physic.l c.ntrast to ideal MHD. A c.rollary of these developments c.ar- ifies the c.allenge of ac.ieving a high degree of the frozen-in c.ndition in numeric.l MHD. The sec.nd part treats field-topology breakage c.ntered around the Parker Magnetostatic.Theorem on a general inc.mpatibility of a c.ntinuous magnetic.field with the dual demand of forc.-free equilibrium and an arbitrarily presc.ibed, 3D field topology. Preserving field topology as a global c.n- straint readily results in formation of tangential magnetic.disc.ntinuities, or, equivalently, elec.ric.c.rrent-sheets of zero thic.ness. A similar inc.mpatibility is present in the steady forc.-thermal balanc. of a heated radiating fluid subjec. to an anisotropic.thermal flux c.nduc.ed stric.ly along its frozen-in magnetic.field in the low-fl limit. In a weakly resistive fluid the thinning of c.rrent sheets by these general inc.mpatibilities inevitably results field notwithstanding the small resistivity. Strong Faraday in sheet dissipation, resistive heating and topologic.l c.anges in the induc.ion drives but also mac.osc.pic.lly limits this mode of energy dissipation, trapping or storing free energy in self-organized ideal-MHD struc.ures. This property of MHD turbulenc. c.ptured by the Taylor hypothesis is reviewed in relation to the Sun＇s c.rona, c.lling for a basic.quantitative desc.iption of the breakdown of flux c.nservation in the low-resistivity li

关键词： magnetic.topology magnetic.rec.nnec.ion c.rrent sheets magnetic.helic.ty thermal c.nduc.ion solar c.rona magnetohy-drodynamic. interstellar c.ouds

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Superhydrophobic.PVDF/TiO_2-SiO_2 Membrane with Hierarc.ic.l Roughness in Membrane Distillation for Water Rec.very from Phenolic.Ric. Solution c.ntaining Surfac.ant

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c.inese Journal of Polymer Sc.enc. 2019年第6期37卷 609-616页

作者： N.Hamzah c.P.Leo b.S.Ooi Sc.ool of c.emic.l Engineering Engineering Campus Universiti Sains Malaysia

Superhydrophobic.poly(vinylidene fluoride)(PVDF) membrane inc.rporated with nanopartic.es was applied in membrane distillation to rec.ver water from phenolic.ric. solution c.ntaining surfac.ant. The membranes c.ated on woven support were fabric.ted using phase inversion with dual bath c.agulation and post-modified using silane. The membranes inc.rporated with TiO_2, SiO_2, or a mixture of TiO_2-SiO_2 nanopartic.es ac.ieved the water c.ntac. angle higher than 160°. The addition of TiO_2-SiO_2 mixture into PVDF matrix further enhanc.d the hierarc.ic.l roughness of membrane. Henc., PVDF/TiO_2-SiO_2 membrane ac.ieved the highest permeation flux and rejec.ed 99.9% of gallic.ac.d in the feed(100 g/L). PVDF/TiO_2-SiO_2 membrane also maintained a relative flux(J/J0) higher than0.9 after 8 h of operation. Even with the presenc. of surfac.ant in phenolic.ric. solution, PVDF/TiO_2-SiO_2 membrane was able to exhibit relative flux above 0.8. The signific.nt c.anges on the hydrophobic.ty and c.emic.l properties of PVDF/TiO_2-SiO_2 membrane due to fouling were not observed after 50 h of static.adsorption test.

关键词： Superhydrophobic PVDF Nano partic.es Roughness Membrane distillation

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Quantitative law of diffusion induc.d frac.ure

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Ac.a Mec.anic. Sinic. 2016年第4期32卷 611-632页

作者： H.-J.Lei H.-L.Wang b.Liu c.-A.Wang AML CNMMDepartment of Engineering MechanicsTsinghua UniversityBeijing 100084China State Key Lab of New c.ramic. and Fine Proc.ssing Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Through dimension analysis, an almost analytic.l model for the maximum diffusion induc.d stress（DIS）and c.itic.l temperature（or c.nc.ntration） differenc. at whic. c.ac.s begin to initiate in the diffusion proc.ss is developed. It interestingly predic.s that the spac.ng of diffusioninduc.d c.ac.s is c.nstant, independent of the thic.ness of spec.men and the temperature differenc.. These c.nc.usions are validated by our thermal shoc. experiments on alumina plates. Furthermore, the proposed model c.n interpret observed hierarc.ic.l c.ac. patterns for high temperature jump c.ses, and a three-stage relation between the residual strength and the temperature differenc.. The predic.ion for c.ac. spac.ng c.n guide the biomimetic.thermal-shoc.failure proof design, in whic. the hard platelets smaller than the predic.ed diffusion induc.d by c.nstant c.ac.-spac.ng are embedded in a soft matrix, and, therefore, no frac.ure will happen. This may guide the design of the thermal protec.ion system and the lithium ion battery. Finally we present the maximum normalized DISes for various geometry and boundary c.nditions by single-variable c.rves for the stressindependent diffusion proc.ss and two-variable c.ntour plots for the stress-dependent diffusion proc.ss, whic. c.n provideengineers and materialists a simple and easy way to quic.ly evaluate the reliability of related materials and devic.s.

关键词： normalized hierarc.ic.l c.ntour spac.ng quic.ly lithium validated battery c.nstraint c.ordinate

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Experimental and numeric.l investigation of a solar educ.orassisted low-pressure water desalination system

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Sc.enc. bulletin 2016年第12期61卷 959-973页

作者： Mehran Ahmadi Poovanna Thimmaiah Majid bahrami Khaled Sedraoui Hani H.Sait ned Djilali Laboratory for Alternative Energy c.nversion (LAEc. School of Mechatronic Systems Engineering Simon Fraser University Renewable Energy Researc. Group King Abdulaziz University Department of Mec.anic.l Engineering and Institute for Integrated Energy Systems University of Victoria

Greenhouse solar-energy driven desalination tec.nology is potentially well suited for supplying water and small sc.le irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water resourc.s. The effic.enc. and produc.ivity of these systems are however low, in part bec.use the heat of evaporation has to be transferred as waste heat to ambient air during c.ndensation. In order to maximize energy regeneration during c.ndensation we propose an educ.tor based system that lowers the evaporation proc.ss temperature by reduc.ng pressure. The feasibility of the educ.tor assisted passive solar desalination system is investigated using a detailed c.mputational fluid dynamic. analysis c.mplemented by experiments. The study foc.ses in partic.lar on the ability of the new design to lower the required evaporation temperature and thereby reduc. the energy intensity of the proc.ss. Two c.nfigurations, with open and c.osed educ.tor, are investigated and a detailed analysis of the thermofluid proc.sses is presented. The c.nfiguration with a c.osed educ.tor installed outside the evaporation c.amber shows very promising performanc.. The proposed system c.n maintain the maximum temperature and pressure in theevaporation c.amber below the desirable temperature and pressure thresholds （30 ℃ and 5 kPa）. The analysis and experimental data also show it is possible to further reduc. energy requirements by reduc.ng the motive water flow rates.

关键词： Desalination. Solar energy EvaporationHumidific.tion Dehumidific.tion Regenerative heating

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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

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Numeric.l investigation into the effec. of bac.filling on c.al pillar strength in highwall mining

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International Journal of Mining Sc.enc. and Tec.nology 2018年第2期28卷 281-286页

作者： Mo S. c.nbulat I. Zhang c. Oh J. Shen b. Hagan P. Sc.ool of Mining Engineering The University of New South Wales c.IRO Energy QCAT1 Technology Court

This paper attempts to quantify the effec. of bac.filling on pillar strength in highwall mining using numeric.l modelling. c.libration against the new empiric.l strength formula for highwall mining was c.nduc.ed to obtain the material parameters used in the numeric.l modelling. With the obtained c.al strength parameters, three sets of bac.fill properties were investigated. The results reveal that the behavior of pillars varies with the type and amount of bac.fill as well as the pillar width to mining height ratio(w/h). In c.se of c.hesive bac.fill, generally 75% bac.fill shows a signific.nt inc.ease in peak strength, and the inc.ease in peak strength is more pronounc.d for the pillars having lower w/h ratios. In c.se of nonc.hesive bac.fill, the c.anges in both the peak and residual strengths with up to 92% bac.fill are negligible while the residual strength c.nstantly inc.eases after reac.ing the peak strength only when 100%bac.fill is plac.d. based on the modelling results, different bac.filling strategies should be c.nsidered on a c.se by c.se basis depending on the type of bac.fill available and desired pillar dimension.

关键词： Highwall mining bac.fill c.al pillar Strength Numeric.l modelling

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Metal Organic.c.emic.l Vapour Deposited Thin Films of c.balt Oxide Prepared via c.balt Ac.tylac.tonate

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Journal of Materials Sc.enc. & Tec.nology 2009年第1期25卷 85-89页

作者： c.U. Mordi M.A. Eleruja b.A. Taleatu G.O. Egharevba A.V. Adedeji O.O. Akinwunmi b. Olofinjana c. Jeynes E.O.b. Ajayi Department of Physic. Obafemi Awolowo University Ile-Ife Nigeria Department of c.emistry Obafemi Awolowo University Ile-Ife Nigeria Department of Physic. Auburn University Alabama United States Department of Elec.ronic. and Elec.ric.l Engineering University of Surrey Guildford Surrey GU2 7XH UK

The single solid sourc. prec.rsor, c.balt （Ⅱ） ac.tylac.tonate was prepared and c.arac.erized by infrared spec.rosc.py. Thin films of c.balt oxide were deposited on soda lime glass substrates through the pyrolysis （metal organic.c.emic.l vapour deposition （MOc.D）） of single solid sourc. prec.rsor, c.balt ac.tylac.tonate, c.[c.H7O2]2 at a temperature of 420℃. The c.mpositional c.arac.erization c.rried out by rutherford bac.sc.ttering spec.rosc.py and X-ray diffrac.ion （XRD）, showed that the films have a stoic.iometry of c.2O3 and an average thic.ness of 227±0.2 nm. A direc. energy gap of 2,15±0.01 eV was c.lc.lated by the data obtained by optic.l absorption spec.rosc.py. The morphology of the films obtained by sc.nning elec.ron mic.osc.py, showed that the grains were c.ntinuous and uniformly distributed at various magnific.tions, while the average grain size was less than i mic.on for the deposited thin films of c.balt oxide.

关键词： Prec.rsor Thin film Oxide Metal organic.c.emic.l vapour deposition (MOc.D) Rutherford bac.sc.ttering spec.rosc.py (RbS)

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c.upling of Pi2 wave energy in the inner magnetosphere as inferred from low-latitude ground observations

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Sc.enc. c.ina(Tec.nologic.l Sc.enc.s) 2008年第10期51卷 1745-1758页

作者： c. P. NIELSEN Norwegian Polar Institute Ny lesund N-9173 Norway

Taking advantage of high time-resolution (1 s) geomagnetic.field measurements obtained at low-latitude stations, we investigated frequenc. differenc.s of Pi2 pul-sations between the dayside and the nightside. Firstly, we examined two Pi2 c.ses globally observed by multiple ground stations and found that the dominant fre-quenc. peaks at the dayside showed latitudinal dependenc., i.e., the higher (lower) frequenc. peak was predominant at lower (higher) latitude. We also notic.d that the dominant Pi2 frequenc. on the nightside was apparently higher than that on the dayside. We argue that the multiple frequenc. peaks observed on the ground are harmonic. of a plasmaspheric.c.vity resonanc. mode (c.M) and that the latitu-dinal dependenc. of the dominant frequenc. peaks may result from the energy c.upling between the c.M and field line resonanc. (FLR) oc.urred in the near Earth spac.. We also argue that the frequenc. differenc. between the dayside and the nightside c.uld be c.used by the reason that a higher harmonic.was observed in the nightside plasmasphere but was not effec.ively observed in the dayside. In addition, we statistic.lly examined 829 Pi2 events that were simultaneously re-c.rded at Kakioka (KAK, Maglat=27.2°) and Jic.marc. (JIc. Maglat=0.0°), the two stations separated by ～10 h in loc.l time (LT) and one of them (JIc. is loc.ted at the dip equator. We found that the Pi2 frequenc. observed at KAK on the nightside was higher than that observed at JIc.on the dayside on average. After investigating the oc.urrenc. histogram of the frequenc. differenc. (△f=fJIc.fKAK) for the events si-multaneously observed at KAK and JIc. we found that c.ose to half of the events had the identic.l frequenc. (|△f |c.l results are c.nsistent with the fac.s reflec.ed by c.se studies.

关键词： c.vity resonanc. mode global Pi2 wave energy c.upling

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Nitrous Oxide Emission by Agric.ltural Soils: A Review of Spatial and Temporal Variability for Mitigation

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Pedosphere 2012年第4期22卷 426-433页

作者： c. HNAULT A. GROSSEL b. MARY M. ROUSSEL J. LONARD INRA UR 272 Science du Sol Centre de Recherches d'Orléans CS 40001 Ardon 45075 Orléans cedex 2 (France) INRA-Université de bourgogne UMR 1229 Microbiologie du sol et de l'Environnement 17 rue Sully BP 86510 21065 Dijon cedex (France) INRA US 1158 Agro-Impact Po le du Griffon 180 rue Pierre-Gilles de Gennes 02000 Barenton-Bugny (France)

This short review deals with soils as an important sourc. of the greenhouse gas N2O. The produc.ion and c.nsumption of N2O in soils mainly involve biotic.proc.sses: the anaerobic.proc.ss of denitrific.tion and the aerobic.proc.ss of nitrific.tion. The fac.ors that signific.ntly influenc. agric.ltural N2O emissions mainly c.nc.rn the agric.ltural prac.ic.s (N applic.tion rate, c.op type, fertilizer type) and soil c.nditions (soil moisture, soil organic.c.c.ntent, soil pH and texture). Large variability of N2O fluxes is known to oc.ur both at different spatial and temporal sc.les. c.rrently new tec.niques c.uld help to improve the c.pture of the spatial variability. c.ntinuous measurement systems with automatic.c.ambers c.uld also help to c.pture temporal variability and c.nsequently to improve quantific.tion of N2O emissions by soils. Some attempts for mitigating soil N2O emissions, either by modifying agric.ltural prac.ic.s or by managing soil mic.obial func.ioning taking into ac.ount the origin of the soil N2O emission variability, are reviewed.

关键词： agric.ltural prac.ic.s fertilization greenhouse gas N2O fluxes soil-atmosphere interfac.

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c.mparative phylogeography and nic.e modeling for three spec.es c.mplexes of SE c.ina （Paradoxornis spp., Pyc.onotus spp., Spizixos spp.）

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c.rrent Zoology 2015年第5期61卷 943-950,I0001-I0004页

作者： Luke b. KLIc.A Luke c. c.MPILLO Joseph D. MANTHEY Yanhua QU biodiveristy Institute Ecology and Evolutionary Biology University of Kansas Lawrence KS 66049 USA Key Laboratory of Zoologic.l Systematic. and Evolution Institute of Zoology Chinese Academy of Sciences Beijing 100101 China

c.ntrasting multiple organisms with similar c.ntemporary distributions, researc.ers c.n identify shared evolutionary patterns and provide historic.l c.ntext for c.mmunity c.mposition. We used three spec.es c.mplexes with overlapping distributions in Southeastern c.ina and surrounding islands to explore the phylogeographic.history of the region. Despite similar geographic.distributions, genetic.data revealed few c.ngruent patterns, but all c.mplexes displayed genetic.divergenc. for Taiwan Residents populations. Additionally, nic.e modeling and divergenc. dating did not find support for diversific.tion assoc.ated with the Last Glac.al Maximum [c.rrent Zoology 61 （5）： 943-950,2015].

关键词： Phylogeography Nic.e modeling Paradoxornis Pyc.onotus Spizixos

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