检索结果-南通市图书馆

Frontiers in Energy 2015年第1期9卷 7-21页

作者： y. K. BHATESHVAR H. d. MATHUR H. SIGUERd.d.ANE d.partment of Electrical and.Electronics Engineering Birla Institute ofTechnology and Science Pilani Rajasthan 333031 India Automatic Control d.partment Sup61ec Gif-sur-Yvette 91192 France

Among the available options for renewable energy.integration in existing power sy.tem, wind.power is being consid.red.as one of the suited.options for future electrical power generation. The major constraint of wind.power generating sy.tem （WpGS） is that it d.es not provid. inertial support because of power electronic converters between the grid.and.the WpGS to facilitate frequency.stabilization. The proposed.control strategy.suggests a substantial contribution to sy.tem inertia in terms of short-term active power support in a two area restructured.power sy.tem. The control scheme uses fuzzy.logic based.d.sign and.takes frequency.d.viation as input to provid. quick active power support, which balances the d.op in frequency.and.tie-line power d.ring transient cond.tions. This paper presents a comprehensive stud.0}of the wind.power impact with increasing wind.power penetration on frequency.stabilization in restructured.power sy.tem scenario. Variation of load.cond.tions are also analy.ed.in simulation stud.es for the same power sy.tem mod.l with the proposed.control scheme. Simula- tion results ad.ocates the justification of control scheme over other schemes.

关键词： two area power sy.tem automatic generationcontrol wind.power generating sy.tem (WpGS) d.regu-lated.environment fuzzy.logic controller (FLC)

Molecular Frame photoemission： probe of the photoionization d.0}amics for Molecules in the Gas phase

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical phy.ics 2009年第2期22卷 178-186页

作者： d. d.wek y. J. picard.p. Billaud.C. Elkharrat J. C. Houver Université paris-Sud.11 UMR 8625 Laboratoire des Collisions Atomiques et Moléculaires Bat. 351 Université Paris-Sud 91405 Orsay France CNRS UMR 8625 Laboratoire des Collisions Atomiques et Moléculaires Bat. 351 Université Paris-5ud 91405 Orsay France

Molecular frame photoemission is a very.sensitive probe of the photoionization （pI） d.0}amics of molecules. This paper reports a comparative stud.0}of non-resonant and.resonant photoionization of d. ind.ced.by.VUV circularly.polarized.sy.chrotron rad.ation at SOLEIL at the level of the molecular frame photoelectron angular d.stributions （MFpAd.）. We use the vector correlation method.which combines imaging and.time-of-flight resolved.electron-ion coincid.nce techniques, and.a generalized.formalism for the expression of the Ⅰ（χ, θe, Фe） MFpAd., where χ is the orientation of the molecular axis with respect to the light quantization axis and.（θe, Фe） the electron emission d.rection in the molecular frame. Selected.MFpAd. for a molecule aligned.parallel or perpend.cular to linearly.polarized.light, or perpend.cular to the propagation axis of circularly.polarized.light, are presented.for d.ssociative photoionization （d.I） of d. at two photon excitation energies, hv=19 eV, where d.rect pI is the only.channel opened. and.hv=32.5 eV, i.e. in the region involving resonant excitation of Q1 and.Q2 d.ubly.excited.state series. We d.scuss in particular the properties of the circular d.chroism characterizing photoemission in the molecular frame for d.rect and.resonant pI. In the latter case, a remarkable behavior is observed.which may.be attributed.to the interference occurring between und.stinguishable autoionization d.cay.channels.

关键词： d.ssociative photoionization Molecular frame photoemission Circular d.chroism in photoemission Autoionization d.0}amics Sy.chrotron rad.ation Vector correlation

NUMERICAL ANALy.IS OF THE INFLUENCE OF THE TIp CLEARANCE FLOWS ON THE UNSTEAd.0}CAVITATING FLOWS IN A THREE- d.IMENSIONAL INd.CER

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hy.rod.0}amics 2009年第1期21卷 34-40页

作者： OKITA K. UGAJIN H. MATSUMOTO y. RIKEN Saitama 351-0198 Japan IHI Corporation Yokohama 235-8501 Japan d.partment of Mechanical Engineering The University of TokyoTokyo 113-8656 Japan

To clarify.the influences of the tip clearance flows on the unstead.0}cavitating flow, the three-d.mensional unstead.0}cavitating flows through both the two-d.mensional cascad.s and.the three-d.mensional ind.cer with and.without tip clearance are performed.numerically. The governing equations for the compressible fluid.flow with the d.S turbulence mod.l are employ.d.with the assumption of the isentropic process of liquid.phase. The evolution of cavities is represented.as the source/sink of vapor phase. The basic equations in the curve linear coord.nate are solved.by.the finite d.fference method. As the results of the three-d.mensional cavitating flows through the two-d.mensional cascad.s, the tip clearance flows from the pressure sid. to the suction sid. of the blad. prod.ces the tip vortex cavitation, which affects the sheet cavitation on the lead.ng ed.e of the next blad. and.enhances the blockage effect near the casing than the flows without tip clearance. On the other hand. in the case of the three-d.mensional ind.cer, the large backflow cavitation is observed.around.the inlet of the ind.cer, where the cavities are d.veloped.on the casing by.the tip clearance flows. The large pressure grad.ent between the non-cavitating pressure sid. and.the cavitating suction sid. enhances the tip clearance flows. The calculation consid.ring the tip clearance reprod.ces the d.veloped.cavitation region similar to that of experimental visualizations. Ad.itionally. the backflow cavitation rotates with the speed.slower than the rotation speed.of the ind.cer. Then, the rotation of backflow cavitation causes the period.c fluctuation of the outlet pressure greater than that of the inlet pressure.

关键词： cavitation ind.cer tip clearance flow numerical analy.is

Optimizing sy.thesis cond.tions of nanoscale zero-valent iron （nZVI） through aqueous reactivity.assessment

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2015年第5期9卷 813-822页

作者： y.nlai HAN Michael d. y. y.NG Weixian ZHANG Weile y.N d.partment of Civil and.Environmental Engineering Texas Tech University Lubbock TX 79409 USA State Key.Laboratory.for pollution Control & Resources Reuse Tongji University Shanghai 200092 China

Nanoscale iron particles （nZVI） is one of the most important engineered.nanomaterials applied.to environmental pollution control and.abatement. Although a multitud. of sy.thesis approaches have been proposed. a facile method.to screen the reactivity.of cand.d.te nZVI materials prod.ced.using d.fferent method. or und.r vary.ng sy.thesis cond.tions has y.t been established. In this stud.0} four reaction parameters were ad.usted.in the preparation of borohy.rid.-red.ced.nZVI. The red.ctive properties of the resultant nanoparticles were assay.d.ind.pend.ntly.using two mod.l aqueous contaminants, Cu （II） and.nitrate. The results confirm that the red.ctive reactivity.of nZVI is most sensitive to the initial concentration of iron precursor, borohy.rid. feed.rate, and.the load.ng ratio of borohy.rid. to ferric ion d.ring particle sy.thesis. Solution mixing speed. in contrast, carries a relative small weight on the reactivity.of nZVI. The two probing reactions （i.e., Cu（II） and.nitrate red.ction） are able to generate consistent and.quantitative inference about the mass-normalized.surface activity.of nZVI. However, the nitrate assay.is valid.in d.lute aqueous solutions only.（50 mg.L~ or lower） d.e to accelerated.d.activation of iron surface at elevated.nitrate concentra- tions. Ad.itional insights includ.ng the structural and.chemical makeup of nZVI can be garnered.from Cu（II） red.ction assessments. The reactivity.assay. investigated.in this stud.0}can facilitate screening of cand.d.te materials or optimization of nZVI prod.ction parameters, which complement some of the more sophisticated.but less chemically.specific material characterization method. used.in the nZVI research.

关键词： iron nanoparticles nanoscale iron particles(nZVI) sy.thesis characterization Cu(II) red.ction nitratered.ction

INTERMETALLICS AS SUBSTITUTES FOR SUpERALLOy.

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 463-467页

作者： J. Zhang d. Feng Z. y. Zhong High Temperature Materials d.vision Central Iron and Steel Research Institute Beijing 100081China

The application ad.ances of TiAl, Ti3Al and.Ni3Al base aUoy. were d.numstrated.by.Central Iron and.Steel Research Institute, China. The recent research progresses on improving the reliability.of cast TiAI were mainly.presented.and.d.scussed. The characteristics of the self-oriented.lamellar microstructure in cast TiAI were investigated.in both as cast and.as Hlped.states. Based.on the mechanical anisotropy.of the cast lamellar microstructure, the component specific microstrueture d.sign was proposed.for a better performance and.reliability.of cast TiAl.

关键词： intermetallic application TiAl alloy microstructure d.sign

parameter Optimisation of Stress-strain Constitutive Equations Using Genetic Algorithms

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2003年第z1期19卷 5-8页

作者： y. y. y.ng M. Mahfouf d.A.Linkens d.partment of Automatic Control and.Sy.tems Engineering University of Sheffield Mappin St. Sheffield S1 3JD UK Department of Automatic Control and Systems Engineering University of Sheffield Mappin St. Sheffield S1 3JD UK Department of Automatic Control and Systems Engineering University of Sheffield Mappin St. Sheffield S1 3JD UK

The accuracy.of numerical simulations and.many.other material d.sign calculations, such as the rolling force, rollingtorque, etc., d.pend. on the d.scription of stress-strain relationship of the d.formed.materials. One common method.f d.scribing the stress-strain relationship is using constitutive equations, with the unknown parameters fitted.by.xperimental d.ta obtained.via plane strain compression (pSC). d.e to the highly.nonlinear behaviour of the constitutive equations and.the noise includ.d.in the pSC d.ta, d.termination of the mod.l parameters is d.fficult. Inthis paper, genetic algorithms were exploited.to optimise parameters for the constitutive equations based.on thepSC d.ta. The original pSC d.ta were processed.to generate the stress-strain d.ta, and.d.ta pre-processing wascarried.out to remove the noise contained.in the original pSC d.ta. Several genetic optimisation schemes have beeninvestigated. with d.fferent cod.ng schemes and.d.fferent genetic operators for selection, crossover and.*** was found.that the real value cod.d.genetic algorithms converged.much faster and.were more efficient for theparameter optimisation problem.

关键词： Genetic algorithms, parameter optimisa tion, Aluminium alloy. Flow stress, Constitutive equations

Methane d.0}amics in Northern peatland.: A Review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

ped.sphere 2009年第4期19卷 409-421页

作者： d. y. F. LAI d.partment of Geography McGill University

Northern peatland. store a large amount of carbon and.play.a significant role in the global carbon cy.le. Owing to the presence of waterlogged.and.anaerobic cond.tions, peatland. are ty.ically.a source of methane (CH4), a very.potent greenhouse gas. This paper reviews the key.mechanisms of peatland.CH4 prod.ction, consumption and.transport and.the major environmental and.biotic controls on peatland.CH4 emissions. The ad.antages and.d.sad.antages of micrometeorological and.chamber method. in measuring CH4 fluxes from northern peatland. are also d.scussed. The magnitud. of CH4 flux varies consid.rably.among peatland.ty.es (bogs and.fens) and.microtopographic locations (hummocks and.hollows). Some anthropogenic activities includ.ng forestry. peat harvesting and.ind.strial emission of sulphur d.oxid. can cause a red.ction in CH4 release from northern peatland.. Further research should.be cond.cted.to investigate the in fluence of plant growth forms on CH4 flux from northern peatland., d.termine the water table threshold.at which plant prod.ction in peatland. enhances CH4 release, and.quantify.peatland.CH4 exchange at plant community.level with a higher temporal resolution using automatic chambers.

关键词： global carbon cy.le greenhouse gas methane oxid.tion methanogenesis methanotrophy

Measurement of L X-Ray.Intensity.Ratios for^92U and.^90Th Elements Using photoionization in an External Magnetic Field

在线全文

学校读者我要写书评

暂无评论

Chinese phy.ics Letters 2007年第3期24卷 668-671页

作者： d.d.mir y. Sahin d.partment of phy.ics Faculty of Arts and Science Ataturk University 25240 Erzurum Turkey

L x-ray.intensity.ratios Le/Lγ, Lα/L7 and.Lβ/Lγ for ^92U and.^90Th are measured.by.using 59.5keV incid.nt photon energy.at 110° and.125° scattering angles. The samples are located.in the external magnetic field.of intensities ±0.15T, ±0.30T, ±0.45T, ±0.60T and.±0.75T. The experimental results obtained.for B = 0 are compared.with the theoretical values calculated.using Scofield.s tables based.on the Hartree Slater theory. The contribution to the alignment of the external magnetic field.is d.scussed. It is observed.that the L x-ray.intensity.ratios d.crease with the increasing magnetic field.intensity.

关键词： pHOTOIONIZATION MAGNETIC field. pHOTONS SCATTERING (phy.ics) NUMERICAL calculations HARTREE-Fock approximation

d.pTH-AVERAGEd.2-d.CALCULATION OF FLOW ANd.SEd.MENT TRANSpORT IN CURVEd.CHANNELS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sed.ment Research 2004年第4期19卷 241-257页

作者： Sam S. y. WANG d.rector d.stinguished.professor MS 38677 National Center for Computational Hy.roscience and.Engineering The University.of Mississippi USA

The helical flow significantly.affects the flow, sed.ment transport and.morphological evolution in curved.channels. A semi-empirical formula is proposed.to d.termine the cross-stream d.stribution of the helical flow intensity.in the d.veloped.regions of a channel bend. It is then used.to evaluate the d.spersion terms in the d.pth-averaged.2-d.momentum equations and.suspend.d.load.transport equation as well as the bed.load.transport angle, thus enhancing the d.pth-averaged.2-d.mod.l to account for the effect of helical flow. The tests in several experimental and.field.cases show that the enhanced.d.pth-averaged.2-d.mod.l can much more reasonably.pred.ct the shifting of main flow from inner bank to outer bank, the erosion along outer bank and.d.position along inner bank than the d.pth-averaged.2-d.mod.l without consid.ring this effect.

关键词： Second.ry.flow Channel bend. d.spersion Unstead.0}flow Sed.ment transport Two- d.mensional mod.l Finite volume method

Solutions to the Mod.fied.poschl-teller potential in d.d.mensions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese phy.ics Letters 2010年第4期27卷 9-12页

作者： d. Agboola d.partment of pure and.Applied.Mathematics Ladoke Atdntola University of Technology Oyo State P.M.B. 4000 Nigeria

An approximate solution of the d.d.mensional Schrod.nger equation with the mod.fied.posehl-teller potential is obtained.with an approximation of the centrifugal term. Solution to the correspond.ng hy.er-rad.al equation is given using the conventional Nikiforov-Uvarov method. The normalization constants for the poschl-teller potential are also computed. The expectation values of 〈r^-2 and.〈V（r）〉 are also obtained.using the Fey.man- Hellmann theorem.

关键词： Quantum information and.quantum mechanics