检索结果-南通市图书馆

Enhanced dielectric performance of Dy-substituted YMn2O5 for high-frequency applications

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2021年第5期31卷 762-771页

作者： H.Chouaibi K.Khirouni E.Dhahri laboratoire de physique Appliquée Faculté des Sciences Université de Sfax laboratoire de physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement Faculté des Sciences de Gabès Cité Erriadh Université de Gabès

The dielectric performances as well as the effects of Dy3+ions content at A sites of YMn2O5（YMO） [x=0（YDM0）and x=0.4(YDM0.4)] polycrystalline samples were *** compounds were synthesized via sol-gel method.X-Ray diffraction and Raman measurements proved the high quality of the compounds that crystallized in an orthorhombic structure with the Pbam space ***,impedance spectroscopy and electrical modulus studies revealed that both samples exhibited a non-debye's type of *** decrease of impedance for YDM0.4compared to the pure YDM0,may be attributed to the decrease in charge transfer *** the fit of impedance spectra,they confirmed that both compounds were simultaneously capacitive and ***,the activation energies obtained from Modulus and complex impedance were proven to be neighboring,suggesting that the relaxation process refers to electron *** each compound,the evolution of ε'and tan & with temperature indicated a clearer relaxor behavior,namely the existence of two *** first one detected at low temperature is related to the charge carriers hopping between Mn3+and Mn4+and the second at high temperature is associated with oxygen *** reduced hopping rate with Dy3+substitution for Y3+ions at A sites is responsible for the decrease in dielectric constant and dielectric *** significant findings demonstrate that these materials can be invested in a fruitful use in UV photo-detector and power applications in high frequency as microwave,millimeter wave signal processing,for civilian,military and space applications.

关键词： Multiferroic Relaxation phenomenon High dielectric constant Relaxor behavior

Comparative Study of Entanglement and Wigner Function for Multi-Qubit GHZ-Squeezed State

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2017年第12期67卷 729-734页

作者： Fatima-Zahra Siyouri laboratoire de physique Thèorique Département de Physique Faculté des Sciences Université Mohammed Ⅴ-Agdal

In this paper we address the possibility of using the Wigner function to capture the quantum entanglement present in a multi-qubit system. For that purpose, we calculate both the degree of entanglement and the Wigner function for mixed tripartite squeezed states of Greenberger–Horne–Zeilinger(GHZ) type then we compare their behaviors. We show that the role of Wigner function in detecting and quantifying bipartite quantum correlation [Int. J. Mod. Phys. B30(2016) 1650187] may be generalized to the multipartite case.

关键词： negativity of Wigner function entanglement squeezed states tripartite GHZ non-classicality

Magnetic properties of Mn-doped GaN with defects:ab-initio calculations

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2011年第8期20卷 297-303页

作者： E.Salmani A.Benyoussef H.Ez-Zahraouy E.H.Saidi lMPHE Departement de PhysiqueFacult'e des SciencesUniversit'e Mohammed V-AgdalRabatMorocco lPHE Departement de PhysiqueFacult'e des SciencesUniversit'e Mohammed V-AgdalRabatMorocco

According to first-principles density functional calculations, we have investigated the magnetic properties of Mn- doped GaN with defects, Ga1-x-yVGxMny N1-z-tVNzOt with Mn substituted at Ga sites, nitrogen vacancies VN, gallium vacancies VG and oxygen substituted at nitrogen sites. The magnetic interaction in Mn-doped GaN favours the ferromagnetic coupling via the double exchange mechanism. The ground state is found to be well described by a model based on a Mn3＋-d5 in a high spin state coupled via a double exchange to a partially delocalized hole accommodated in the 2p states of neighbouring nitrogen ions. The effect of defects on ferromagnetic coupling is investigated. It is found that in the presence of donor defects, such as oxygen substituted at nitrogen sites, nitrogen vacancy antiferromagnetic interactions appear, while in the case of Ga vacancies, the interactions remain ferromagnetic; in the case of acceptor defects like Mg and Zn codoping, ferromagnetism is stabilized. The formation energies of these defects are computed. Furthermore, the half-metallic behaviours appear in some studied compounds.

关键词： diluted magnetic semiconductor GaN:Mn defects ab-initio magnetic properties

Environments favorable to healthy lifestyles:A systematic review of initiatives in Canada

在线全文

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2018年第1期7卷 7-18页

作者： Tegwen Gadais Maude Boulanger Francois Trudeau Marie-Claude Rivard Département des sciences de l’activité physique Universitédu Québec à Montréal Département de psychologie Universitédu Québec à Trois Rivières Département des sciences de l’activité physique Université du Québec à Trois Rivières

Background: In recent years, a number of initiatives aimed at promoting healthy lifestyles in health-friendly environments have been *** purpose of this review is to synthesize initiatives conducted in Canada and documented in publications for the period 1995–2015 in order to gain a better understanding of their objectives and ***: A systematic review of Canadian initiatives published over the past 20 years was conducted from multiple databases(i.e., Scopus,SPORTDiscus, Pub Med, Academic search complete, ***, Cairn, and Erudit). In total, 264 publications were identified and retained for the final analysis based on 5 criteria:(1) publication between 1995 and 2015,(2) online availability,(3) research conducted in Canada,(4) main topic related to environments favorable to healthy lifestyles(EFHl), and(5) publication in French or ***: A sharp increase in the number of studies on EFHl was observed between 2010 and 2015(57%). Two major lifestyle components—physical activity and nutrition—and 2 environmental aspects—neighborhood and built environment—were the elements most frequently examined regarding adults(48%), young people(34%), and seniors(9%), using quantitative(60%) and qualitative(18%) methods. Furthermore, the analysis reveals a greater focus on the municipal(53%) than the national or provincial levels(31%).Conclusion: This work is a first map of Canadian studies related to EFHl. It clarifies the definition of EFHl and classifies its components. As well,it documents the issues raised, the research methods employed, and the role of stakeholders, while outlining a new research agenda that includes dimensions of EFHl formerly neglected by researchers, namely, political and sociocultural spheres of action.? 2018 Production and hosting by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license(http://***/licenses/by-nc-nd/4.0/).

关键词： Built environment Canada Favorable environment Healthy lifestyle Initiatives Neighborhood Nutrition Physical activity

Surface Effects on Wannier Excitons in Superlattices:Monte Carlo Simulation

在线全文

学校读者我要写书评

暂无评论

Chinese Physics letters 2002年第8期19卷 1164-1167页

作者： K. Afif A. Benyoussef J. Diouri laboratoire de Magnétisme Faculté des Sciences BP 1014 Rabat Morocco Groupe d'Electronique et de physique du Solide Faculté des Sciences BP 2121 Tetouan Morocco

Using a Monte Carlo quadrature, we calculate by a variational method the binding energy Eb of Wannier excitons in N-period m-CdMnTe/n-CdTe superlattices, including or not including the step discontinuity in the potential barrier at the interface, and with varying N as well as well width. The calculation is performed in the framework of the effective mass approximation for both heavy-hole and light-hole excitons. The degree of exciton localization dependence on these parameters is accurately illustrated.

关键词： Monte Carlo methods

laser Polarization Orientations in(e,2e)Reactions in Atoms

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics letters 2015年第8期32卷 62-65页

作者： Ajana I. Makhoute A. Khalil D. UFR de physique du Rayonnement et des Interactions laser-Matière Faculté des SciencesUniversité Moulay Ismail

Second-order Born calculations are performed to investigate the triple differential cross sections of coplanar asymmetric laser-assisted （e, 2e） collisions for hydrogen and helium targets. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing the Volkov solutions in both the initial and final channels. detailed calculations of the scattering amplitudes are performed using the Sturmian basis expansion. The state of the ejected electron is described by a Coulomb-Volkov wave function. Two geometries are investigated in which the laser polarization vector is either parallel to the incident momentum of the projectile or parallel to the momentum transfer. Our numerical results show that, in the low energy range, these two laser polarization orientations give the same shape and the same order of magnitude of laser-assisted ionization cross sections of helium and hydrogen targets.

关键词： laser Polarization Orientations in e,2e)Reactions in Atoms

Exotic Hadrons and Underlying Z_(2,3) Symmetries

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2015年第12期64卷 697-700页

作者： Adil Belhaj Salah Eddine Ennadifi Moulay Brahim Sedra Département de physique Faculté PolydisciplinaireUniversité Sultan Moulay Slimane lPHE-MS Faculté des SciencesUniversité Mohammed V Département de physique SIMO-FSKFaculté des SciencesUniversité Ibn Tofail Kénitra

The recent observation of higher quark combinations, tetraquarks and pentaquarks, is a strong indication of more exotic hadrons. Using Z_2 and Z_3 symmetries and standard model data, a general quark combination producing new hadronic states is proposed in terms of polygon geometries according to the Dynkin diagrams of ?_n affine lie algebras. It has been shown that Z_(2,3) invariance is crucial in the determination of the mesonic or the baryonic nature of these states. The hexagonal geometry is considered in some details producing both mesonic and baryonic states. A general class of this family is also presented.

关键词： standard model exotic hadrons and lie symmetries

Exact Solution of D-Dimensional Klein-Gordon Oscillator with Minimal length

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2010年第2期53卷 231-236页

作者： Y.Chargui l.Chetouani A.Trabelsi Unit de Recherche de physique Nuclaire et des Hautes Energies Facult des Sciences de Tunis Dpartement de physique Thorique Institut de Physique Universit de Constantine Route Ain El Bey Unite de Recherche de physique Nucleaire et des Hautes Energies Faculte des Sciences de Tunis Centre National des sciences et Technologies Nuclaires

Specific modifications of the usual canonical commutation relations between position and momentumoperators have been proposed in the literature in order to implement the idea of the existence of a minimal observablelength. Here, we study a consequence of this proposal in relativistic quantum mechanics by solving in the momentumspace representation the Klein-Gordon oscillator in arbitrary dimensions. The exact bound states spectrum and thecorresponding momentum space wave function are obtained. Following Chang et al. (Phys. Rev. D 65 (2002) 125027),we discuss constraint that can be placed on the minimal length by measuring the energy levels of an electron in a penningtrap.

关键词： Klein-Gordon oscillator minimal length energy spectrum

Bound in continuum states and induced transparency in mesoscopic demultiplexer with two outputs

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第12期29卷 429-437页

作者： Z labdouti T Mrabti A Mouadili E H El Boudouti F Fethi B Djafari-Rouhani lPMR Dèpartement de PhysiqueFacultèdes SciencesUniversitèMohammed IOujdaMorocco lSTA Dèpartement de PhysiqueFacultèPolydisciplinaire de LaracheUniversitèAbdelmalek EssaadiTètouanMorocco lPMCER Dèpartement de PhysiqueFacultèdes Sciences et Techniques de MohammediaUniversitèHassan IICasablancaMorocco IEMN UMR CNRS 8520UFR de PhysiqueUniversitède Lille59655 Villeneuve d'AscqFrance

We investigate the electronic transport in a simple mesoscopic cross structure made of two wires(stubs)grafted at the same point along a quantum *** show that the structure may exhibit important phenomena such as bound in continuum(BIC)*** states are transformed into electromagnetically induced transparency(EIT)resonance by detuning slightly the lengths of the *** last phenomenon is used to propose and study a mesoscopic demultiplexer device with an input waveguide and two output *** give closed-form expressions of the geometrical parameters that allow a selective transfer of a given state in the first waveguide without perturbing the second *** effect of temperature on the transmission resonances is also examined by using landauer-Büttiker *** analytical results of the dispersion relation and transmission and reflection coefficient are obtained using the Green's function method.

关键词： mesoscopic structure demultiplexer device bound states in continuum(BIC) EIT resonance