检索结果-南通市图书馆

Appearance of Negative Differential Conductivity in Graphene Nanoribbons.at High-Harmonics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Graphene 2013年第2期2卷 61-65页

作者： Mus.h Rabiu s.muel Y. Mens.h sulemana s. abukari Department of Applied Phys.cs University for Development Studies Navrongo Ghana Phys.cs.Department Center for Laser and Fiber Optics University of Cape Coast Cape Coast Ghana

We theoretically s.udy current dynamics.of graphene nanoribbons.s.bject to DC-AC driven fields. We s.ow that graphene exhibits.negative differential conductivity (NDC) at high-harmonics. NDC occurs.in the neighborhood where a cons.ant electric field is.equal to amplitude of ac field. We als. obs.rve NDC at both even and odd harmonics.and at wave mixing of two commens.rate frequencies. The even harmonics.are more pronounced than the odd harmonics. A pos.ible us. of the pres.nt method for generating terahertz frequencies.at even harmonics.in graphene is.s.gges.ed.

关键词： Graphene Nanoribbon Energy s.ectrum Electronic Conductivity Terahertz Negative Differential Conductivity

Anomalous.Vis.os.ty of Vortex Hall s.ates.in Graphene

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 Applied Mathematics.and Phys.cs 2015年第12期3卷 1654-1661页

作者： Rabiu Mus.h s.muel Y. Mens.h Ibrahim Y. s.ini sulemana s. abukari Department of Applied Mathematics Faculty of Mathematical Sciences University for Development Studies Navrongo Campus Upper East Ghana Department of Phys.cs Laser and Fiber Optics Center University of Cape Coast Cape Coast Ghana

We s.udy temperature effect on anomalous.vis.os.ty of Graphene Hall fluid within quantum many-vortex hydrodynamics. The commonly obs.rved filling fraction, in the range is.cons.dered. An expres.ion for anomalous.vis.os.ty dependent on a geometric parameter-Hall expans.on coefficient is.obtained at finite temperatures. It aris.s.from s.rained induced ps.udo-magnetic field in addition to an anomalous.term in vortex velocity, which is.res.ons.ble for renormalization of vortex-vortex interactions. We obs.rved that both terms.greatly modify the anomalous.vis.os.ty as.well as.an enhancement of weakly obs.rved v fractions. Finite values.of the expans.on coefficient produce cons.ant and infinite vis.os.ties.at varying temperatures. The infinities.are identified as.energy gaps.and s.gges. temperatures.at which new s.able quantum hall filling fractions.could be s.en. This.phenomenon is.us.d to es.imate energy gaps.of already meas.red fractional Quantum Hall s.ates.in Graphene.

关键词： Euler Hydrodynamics Quantum Hall Fluid Vortex Dynamics Fractional Quantum Hall Effect Anomalous Vis.os.ty Hall Expans.on Coefficient

Generation and Propagation of Ultras.nic Waves.in Piezoelectric Graphene Nanoribbon

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Acous.ics 2013年第3期3卷 38-42页

作者： Mus.h Rabiu s.muel Y. Mens.h sulemana s. abukari Matthew Amekpewu Baah s.fa-Ntiri Anthony Twum Univers.ty for Development s.udies Faculty of Applied Science Department of Applied Physics Navrongo Ghana Univers.ty of Cape Coas. Center for Laser and Fiber Optics Physics Department Cape Coast Ghana

Generation and propagation of ultras.nic waves.in s.ngle layer Graphene Nanoribbon is.s.udied us.ng s.mi-clas.ical approach. When piezoelectric Graphene Nanoribbon (GNR) is.expos.d to time varying light beam, ultras.nic waves.are produced which propagate in the medium. At low frequencies. we obs.rved os.illations.of the ultras.nic obs.rvables. velocity change and attenuation which are characteris.ics.of mas.les. Dirac fermions.in graphene. Exploiting this.os.illatory behavior, we es.imate graphene’s.electronic mobility to be around . Propagating ultras.nic waves.can be amplified, depending on the electric field amplitude. s.ecifically, amplification occurs.when drift velocity exceeds.s.und velocity. This.s.heme can be employed for efficient ultras.nic amplifier device operation.

关键词： Current Dens.ty Negative Differential Conductivity Commens.rable Frequencies

Direct Current Generation in Carbon Nanotubes.by Terahertz Field

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Condens.d Matter Phys.cs 2016年第1期6卷 56-62页

作者： sulemana s. abukari Frederick s.m s.muel Y. Mens.h Natalia G. Mens.h Rabiu Mus.h Anthony Twum Patrick M. Amoah Alfred Owus. Department of Phys.cs Laser and Fibre Optics Centre University of Cape Coast Cape Coast Ghana Department of Mathematics University of Cape Coast Cape Coast Ghana Department of Applied Phys.cs University for Development Studies Navorongo Ghana

We report on a theoretical inves.igation of a direct current generation in carbon nanotubes.(CNTs. that are s.imulated axially by terahertz (THz) field. We cons.der the kinetic approach bas.d on the s.miclas.ical Boltzmann’s.trans.ort equation with cons.ant relaxation time approximation, together with the energy s.ectrum of an electron in the tight-binding approximation. Our res.lts.indicate that for s.rong THz-fields. there is.s.multaneous.generation of DC current in the axial and circumferential directions.of the CNTs. even at room temperature. We found that a THz-field can induce a negative conductivity in the CNTs.that leads.to the THz field induced DC current. For varying amplitude of the THz-field, the current dens.ty decreas.s.rapidly and modulates.around zero with interval of negative conductivity. The interval decreas.s.with increas.ng the amplitude of the THz-field. We s.ow that the THz-field can caus. fas. s.itching from a zero DC current to a finite DC current due to the quas.-ballis.ic trans.ort, and that electron s.attering is.a neces.ary condition for s.itching.

关键词： Carbon Nanotubes Terahertz Fields DC Voltage Generation Negative Conductivity Electron s.attering Ballis.ic Trans.ort

External Electric Field Effect on Electrons.Trans.ort in Carbon Nanotubes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Condens.d Matter Phys.cs 2013年第4期3卷 169-172页

作者： sulemana s. abukari s.muel Y. Mens.h Mus.h Rabiu Kofi W. Adu Natalia G. Mens.h Kwadwo A. Dompreh Anthony Twum Matthew Amekpewu Department of Applied Phys.cs University for Development Studies Navorongo Ghana Department of Mathematics University of Cape Coast Cape Coast Ghana Department of Phys.cs Laser and Fibre Optics Centre University of Cape Coast Cape Coast Ghana Department of Phys.cs The Pennsylvania State University Altoona USA Materials.Res.arch Ins.itute The Pennsylvania State University University Park USA

We cons.der a s.mple model of carbon nanotubes.(CNTs. s.bject to external electric field E(t). Us.ng a tight-binding approximation for the des.ription of energy bands.of CNTs. together with the s.andard Boltzmann trans.ort equation and cons.ant relaxation time, we predict the effect of s.lf-induced trans.arency and abs.lute negative conductivity. The predicted effects.may be us.ful in diagnos.ics.of carbon nanotubes.as.well as.in the amplification and efficiency convers.on of electromagnetic s.gnals.

关键词： Carbon Nanotubes Electric Field Electric Current Dens.ty Negative Differential Conductivity

High-Frequency Electric Field Induced Nonlinear Electron Trans.ort in Chiral Carbon Nanotubes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Condens.d Matter Phys.cs 2015年第4期5卷 294-300页

作者： sulemana s. abukari s.muel Y. Mens.h Mus.h Rabiu Kofi W. Adu Natalia G. Mens.h Anthony Twum Alfred Owus. Kwadwo A. Dompreh Patrick Mens.h-Amoah Matthew Amekpewu Department of Phys.cs Laser and Fibre Optics Centre University of Cape Coast Cape Coast Ghana Department of Applied Phys.cs University for Development Studies Navorongo Ghana Department of Phys.cs The Pennsylvania State University-Altoona Altoona USA Materials.Res.arch Ins.itute The Pennsylvania State University University Park USA Department of Mathematics University of Cape Coast Cape Coast Ghana

We inves.igate theoretically the high frequency complex conductivity in carbon nanotubes.that are s.imulated axially by a s.rong inhomogeneous.electric field of the form E(t)=E0+E1cos.ωt). Us.ng the kinetic approach bas.d on Boltzmann’s.trans.ort equation with cons.ant relaxation time approximation and the energy s.ectrum of the electron in the tight-binding approximation, together with Bhatnagar-Gros.-Krook collis.on integral, we predict high-frequency nonlinear effects.along the axial and the circumferential directions.of the carbon nanotubes.that may be us.ful for the generation of high frequency radiation in the carbon nanotubes.

关键词： Carbon Nanotubes High Frequency Electric Field Electric Current Dens.ty Complex Conductivity

Domain s.ppres.ion in the Negative Differential Conductivity Region of Carbon Nanotubes.by Applied AC Electric Field

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Condens.d Matter Phys.cs 2012年第4期2卷 274-277页

作者： sulemana s. abukari s.muel Y. Mens.h Kofi W. Adu Natalia G. Mens.h Kwadwo A. Dompreh Anthony Twum Chales.L. Y. Amuah Matthew Amekpewu Mus.h Rabiu Department of Applied Phys.cs University for Development Studies Navorongo Ghana Department of Phys.cs Laser and Fibre Optics Centre University of Cape Coast Cape Coast Ghana Department of Phys.cs The Pennsylvania State University Altoona USA Materials.Res.arch Ins.itute The Pennsylvania State University University Park USA National Centre for Mathematical s.iences Ghana Atomic Energy Commission Accra Ghana Department of Mathematics University of Cape Coast Cape Coast Ghana

We s.udy theoretically the electron trans.ort properties.in achiral carbon nanotubes.under the influence of an external electric field E(t) us.ng Boltzmann’s.trans.ort equation to derive the current-dens.ty. A negative differential conductivity (NDC) is.predicted in quas.-s.atic approximation i.e., ωτ 0 is.equal to the amplitude of the AC electric field E1. The peak of the NDC intens.ty occurs.at very weaker fields.than that of s.perlattice under the s.me conditions. The peak intens.ty decreas.s.and s.ifts.to right with the increas. in the amplitude of the ac field. This.mechanis. s.ppres.es.the domain formation and therefore could be us.d in terahertz frequency generation.

关键词： Carbon Nanotubes Negative Differential Conductivity and Generation of Terahertz Radiation

Performing arts.as.a s.cial technology for community health promotion in northern Ghana

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Family Medicine and Community Health 2016年第1期4卷 22-36页

作者： Michael Fris.kopf Has.n Hamze Mubarak Alhas.an Ibrahim abukari Zukpeni sulemana Abu David Zakus Faculty of Arts.and Faculty of Medicine and Dentis.ry University of Alberta382 FABEdmonton AB T6H 3S9Canada 9851 Waller Court Richmond BC V7E5S9 Canada Grooming Dot Org P.O.Box TL 1324Postal Code 00233House No.CH.EXT 14Bolga RoadAgric AreaTamaleNorthern RegionGhanaWest Africa Grooming Dot Org P.O.Box TL 1817Post Code:00233TamaleNorthern RegionGhanaWest Africa Tamale Youth Home Cultural Group P O Box 601Tamale N/RA Ext.32 HiltopGhanaWest Africa Faculty of Community s.udies School of Occupational and Public HealthRyerson UniversityRoom POD249350 Victoria StreetTorontoON M5B 2K3Canada

Objective:We pres.nt firs.-phas. res.lts.of a performing arts.public health intervention,‘s.nging and Dancing for Health,’aiming to promote healthier behaviors.in Ghana’s.impoveris.ed Northern *** hypothes.ze that live mus.c and dance drama provide a powerful technology to overcome barriers.s.ch as.illiteracy,lack of adequate media acces.,inadequate health res.urces.and entrenched s.ciocultural *** res.arch objective is.to evaluate this.***:In this.firs. phas.,we evaluated the effectivenes. of arts.interventions.in improv-ing knowledge and behaviors.as.ociated with reduced incidence of malaria and cholera,focus.ng on bas.c information and s.mple practices.s.ch as.proper hand *** with the Youth Home Cultural Group,we codeveloped two‘dance dramas.delivering health mes.ages.through di-alog,lyrics.and drama,us.ng mus.c and dance to attract s.ectators.focus.attention,infus. emotion,and s.cialize *** als. des.gned knowledge,attitude,and behavior s.rveys.as.meas.rement *** purpos.ve s.mpling,we s.lected three contras.ing tes. villages.in the vicinity,contras.ing in s.ze and *** cooperation of chiefs.elders.elected officials.and Gha-na Health s.rvice officers.we conducted a bas.line s.rvey in each ***,we performed the interventions.and s.bs.quently conducted follow-up *** a more qualitative approach,we als. tracked a s.lect s.bgroup,conducted focus.group s.udies.and collected ***-veys.were coded and data were analyzed by Epi ***:Both quantitative and qualitative methods.indicated that thos. who attended the dance drama performances.were likelier than thos. who did not attend to lis. the caus.l,preven-tive,and trans.is.ion factors.of malaria and ***,the s.me attendees.were likelier than nonattendees.to lis. s.me activities.they do to prevent malaria,cholera,and other s.nitation-related dis.as.s.proving that dance dramas.were highly effective both in rais.

关键词： Mus.c dance drama edutainment community health s.nitation malaria Ghana

Computational Dynamics.of s.agnation Point Flow of Micropolar Fluid Pas. Vertical Porous.Plates

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 Applied Mathematics.and Phys.cs 2023年第11期11卷 3484-3504页

作者： Ayando Timothy Ibrahim Y. s.ini Mus.h sulemana Faculty of Phys.cal s.iences University for Development Studies Tamale Ghana

This.work examines.the flow of a micropolar fluid over a vertical porous.plate at the MHD s.agnation point under vis.ous.dis.ipation, convective boundary conditions. and thermal radiation. The governing partial differential equations.and a s.t of s.milarity parameters.were us.d to trans.orm them into ordinary differential equations. The Runge-Kutta fourth-order algorithm is.us.d in conjunction with the Newton Raphs.n s.ooting technique to numerically s.lve the generated s.lf-s.milar equations. Res.lts.were tabulated both numerically and graphically, and examples.for different controlling factors.are quantitatively analyzed. According to the s.udy, the vortex vis.os.ty parameter (k) caus.s.the velocity profiles.to ris. while the magnetic parameter, s.ction parameter, and radiation parameter caus. them to fall. In contras., as.the flow’s.s.ction and prandtl values.ris., s. do the magnetic parameter, radiation, and vortex vis.os.ty, while the thicknes. of the thermal boundary layer decreas.s. .

关键词： MHD Vis.ous.Dis.ipation Thermal Radiation Microrotation Micropolar Fluid