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Alternating-current losses in two-layer superconducting cables consisting of second-generation superconductors coated by U-shaped ferromagnetic materials

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Chinese Physics B 2013年第12期22卷 509-513页

作者： Ahmet Cicek Fedai Inanir Fedor gmry Department of Physics Faculty of Arts and Sciences Mehmet Akif Ersoy University Department of Physics Faculty of Arts and Sciences Recep Tayyip Erdog an University Institute of Electrical Engineering Slovak Academy of Sciences Du'bravska' Cesta 9 842 39 Bratislava Slovakia

Alternating-current losses in a two-layer superconducting cable, each layer being composed of 15 closely-spaced rectangular wires made up of second-generation superconductors when the ends of wires are coated by either a non-magnetic or strong ferromagnetic material having a U profile is numerically investigated. Computations are carried out through the finite-element method. The alternating-current losses do not increase significantly if the relative permeability of the coating is increased three orders of magnitude, provided that the current amplitude is less than half of the critical current in a superconducting wire. However, the losses are much higher for ferromagnetic coating if the amplitude of the applied current oscillating at 50 Hz is close to the critical current. The ferromagnetic coating is seen to accumulate the magnetic field lines normally on its surfaces, while the field lines are parallel to the long axes of the wires, leading to more significant flux penetration in the coated regions. This facilitates a uniform low-loss current flow in the uncoated regions of the wires. In contrast, coating with a non-magnetic material gives rise to a considerably smaller current flow in the uncoated regions, whereas the low-loss flow is maintained in the coated regions. moreover, the current flows in opposite directions in the coated and uncoated regions, where the direction in each region is converse for the two materials.

关键词： second-generation superconductor two-layer cable ferromagnetic coating U profile alternating-current losses

Laboratory generation of Solitary Waves:An Inversion Technique to Improve Available methods

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China Ocean Engineering 2014年第1期28卷 57-66页

作者： A.Romano m.guerrini g.Bellotti 琚烈红 University of Roma Tre Via Vito Volterra 62Rome 00146Italy Nanjing Hydraulic Research Institute

Solitary waves are often used in laboratory experiments to study tsunamis propagation and interaction with coasts. However, the experimental shape of the waves may differ from the theoretical one. In this paper, a correction technique aiming at minimizing the discrepancies between the two profiles is presented. Laboratory experiments reveal their effectiveness in correcting the experimental shape of solitary waves, mainly for low nonlinearities.

关键词： tsunamis solitary waves correction technique laboratory generation

Kinetic Study on CO_2 Reforming of methane

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Chinese Journal of Chemical Engineering 2001年第2期9卷 190-195页

作者： C.E.Quincoces m.g.gonzález Centro de Investigacion y Desarrollo en Procesos Cataliticos (CINDECA) 阿根廷

The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio ＞ 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.

关键词： CH4 reforming Ni catalysts syngas

modulational Instability of Optical Vortices in Engineered Saturable media

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Engineering 2022年第10期17卷 31-43页

作者： D.g.Pires N.m.Litchinitser Department of Electrical and Computer Engineering Duke UniversityDurhamNC 27708USA

Propagation of light beams in turbid media such as underwater environments,fog,clouds,or biological tissues finds increasingly important applications in science and technology,including bio-imaging,underwater communication,and free-space communication *** many of these applications traditionally relied on conventional,linearly polarized gaussian beams,light possesses many degrees of freedom that are still largely unexplored,such as spin angular momentum(SAm)and orbital angular momentum(OAm).Here,we present nonlinear light-matter interactions of such complex light beams with"rotational"degrees of freedom in engineered nonlinear colloidal *** making use of both variational and perturbative approach,we consider non-cylindrical optical vortices,elliptical optical vortices,and higher-order Bessel beams integrated in time(HOBBIT)to predict the dynamics and stability of the evolution of these *** results may find applications in many scenarios involving light transmission in strongly scattering environments.

关键词： Optical vortex Orbital angular momentum modulation instability Turbid media

Physical-Chemical Characterization of Nanodispersed Powders Produced by a Plasma-Chemical Technique

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Plasma Science and Technology 2007年第3期9卷 273-279页

作者： m.gEORgIEVA g.VISSOKOV Iv.gRANCHAROV Department of Technology of Inorganic Substances University of Chemical Technology and Metallurgy8St.Kliment Ohridski Blvd.1756 SofiaBulgaria

This article presents a review on the physical-chemical properties and characteristics of plasma-chemically produced nanodispersed powders （NDP）, such as metals, oxides, nitrides, carbides, and catalysts. The plasma-chemical preparatior~ of the powders was carried out in thermal plasma （TP） created by means of high-current electric arcs, plasma jets, high-frequency （HF） discharges, etc. We also discuss certain properties and characteristics of the NDPs, which are determined largely by the conditions of preparation.

关键词： plasma-chemical treatment nitrides thermodynamic analysis

Comparisons of electrical and optical properties between graphene and silicene A review

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Chinese Physics B 2018年第2期27卷 299-313页

作者： Wirth-Lima A J Silva m g Sombra A S B Laboratory of Telecommunications and materials Science and Engineering-www.locem.ufc.br-Fortaleza CearaBrazil Department of Physics Science CenterFederal University of Ceara(U.F C.)-FortalezaCear4Brazil State University of Vale do Acarau SobralCeardBrasil

Two-dimensional （2D） metamaterials are considered to be of enormous relevance to the progress of all exact sciences. Since the discovery of graphene, researchers have increasingly investigated in depth the details of electrical/optical proper- ties pertinent to other 2D metamaterials, including those relating to the silicene. In this review are included the details and comparisons of the atomic structures, energy diagram bands, substrates, charge densities, charge mobilities, conductivities, absorptions, electrical permittivities, dispersion relations of the wave vectors, and supported electromagnetic modes related to graphene and silicene. Hence, this review can help readers to acquire, recover or increase the necessary technological basis for the development of more specific studies on graphene and silicene.

关键词： graphene silicene electrical/optical properties

A cavitation aggressiveness index within the Reynolds averaged Navier Stokes methodology for cavitating flows

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Journal of Hydrodynamics 2015年第4期27卷 579-586页

作者： KOUKOUVINIS P. BERgELES g. gAVAISES m. Department of Engineering and mathematical Science City University London

The paper proposes a methodology within the Reynolds averaged Navier Stokes（RANS） solvers for cavitating flows capable of predicting the flow regions of bubble collapse and the potential aggressiveness to material damage. An aggressiveness index is introduced, called cavitation aggressiveness index（CAI） based on the total derivative of pressure which identifies surface areas exposed to bubble collapses, the index is tested in two known cases documented in the open literature and seems to identify regions of potential cavitation damage.

关键词： cavitation aggressiveness index(CAI) cavitation erosion multiphase cavitating flows

Energy transport for ion acoustic waves in a spin polarized quantum plasma

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Communications in Theoretical Physics 2020年第1期72卷 124-129页

作者： m Ayub Z Iqbal H A Shah g murtaza Salam Chair Department of PhysicsG.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics G.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics Mirpur University of Science and TechnologyMirpur-10250(AJK)Pakistan

The separate spin evolution quantum hydrodynamics(SSE-QHD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum *** results show that the energy flow speed decreases with spin polarization *** is also shown that it decreases with the increasing rate up to a certain range of wave number and then it goes to zero *** is observed that Bohm potential suppresses the energy flow *** is also noticed that the energy flow speed deviates from the group velocity even in the absence of Bohm potential ***,the contribution of of Bohm poential effect in spin polarized plasma reduces the extent of deviation.

关键词： spin polarization quantum plasma ion acoustic wave energy flow speed

Impacts of longterm conservation measures on ecosystem services in Northwest Ethiopia

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International Soil and Water Conservation Research 2020年第1期8卷 47-55页

作者： Woubet g.Alemu Assefa m.melesse Department of Earth and Environment Florida International UniversityMiamiFL33199USA

A Soil Conservation Research Program(SCRP)has been on-going in Anjeni Watershed,Amhara Region,Ethiopia since the 1980s,focussing particularly on soil-based,graded fanya juu *** study was carried out to examine the long-term impacts of these soil and water conservation measures in improving ecosystem services.A comparative analysis was made with a non-treated 100 ha adjacent watershed(Zikrie).The Revised Universal Soil Loss Equation(RUSLE)was used in a geographic infor-mation system(gIS)to quantify soil *** soil samples were taken 30 cm deep soil pits in the loss and deposition zones in the terraced Anjeni and topo-sequential soil samples on both *** analysis was carried out at the National Soil Testing Laboratory(NSTL)of *** texture,pH and OC were analyzed for the 91 soil samples.A gIS analysis of the RUSLE factors was made on a 5 m grid cell *** mean annual soil loss rate in Anjeni was estimated to be 37 t ha^-1 yr^-1,while that of the adjacent non-conserved Zikrie was 45 t ha^-1 yr^-*** total estimated soil loss in Anjeni watershed was 4214 t yr^-*** valleys in the Anjeni watershed had the maximum mean annual esti-mated soil loss hazard(86 t ha^-1 yr^-1).Cultivated land had medium mean annual estimated soil loss(44 t ha^-1 yr^-1)due to the soil conservation *** the soil-based graded fanya juu terraces with biological soil conservation measures is important for the stability of the ecosystem.

关键词： Soil and water conservation Soil loss RUSLE gIS Anjeni