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Chinese Physics b 2020年第4期29卷 179-189页

作者： S M Ngounou f b pelap Unite de Recherche de Mecanique et de Modelisation des Systèmes Physiques(UR-2 MSP) Faculte des SciencesUniversite de DschangBP 69 DschangCameroun Unite de Recherche de Matiere Condensee d'Electronique et de Traitement du Signal(UR-MACETS) Faculte des SciencesUniversite de DschangBP 67 DschangCameroun

The dynamics of modulated waves in a nonlinear bi-inductance transmission line with dissipative elements are *** show the existence of two frequency modes and carry out intensive investigations on the low frequency *** to the multiple scales method,the behavior of these waves is investigated and the dissipative effects are *** appears that the dissipation coefficient increases with the carrier wave *** the continuous approximation,we derive that the propagation of these waves is governed by the complex Ginzburg-Landau equation instead of the Korteweg-de-Vries equation as previously *** studies of the dynamics of plane waves in the line reveal the existence of three additional regions in the dispersion curve where the modulational phenomenon is *** the low frequency mode,we demonstrate that the network allows the propagation of dark and bright *** findings are in perfect agreement with the analytical predictions.

关键词： dissipative bi-inductance network low frequency mode continuous approximation complex Ginzburg-Landau equation

Dynamics of high-frequency modulated waves in a nonlinear dissipative continuous bi-inductance network

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Chinese Physics b 2021年第6期30卷 193-205页

作者： S M Ngounou f b pelap Unitéde Recherche de Mécanique et de Modélisation des Systèmes Physiques(UR-2 MSP) Facultédes SciencesUniversitéde DschangBP 69 DschangCameroun Unitéde Recherche de Matière Condensée d'Electronique et de Traitement du Signal(UR-MACETS) Facultédes SciencesUniversitéde DschangBP 67 DschangCameroun

This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coefficient whose evolution in terms of the carrier wave frequency is checked. There appears that the dissipation coefficient increases with the carrier wave frequency. In the linear limit and for high frequency waves, study of the asymptotic behavior of plane waves reveals the existence of two additional regions in the dispersion curve where the modulational phenomenon is observed compared to the lossless line. based on the multiple scales method exploited in the continuum approximation using an appropriate decoupling ansatz for the voltage of the two different cells, it appears that the motion of modulated waves is described by a dissipative complex Ginzburg–Landau equation instead of a Korteweg–de Vries equation. We also show that this amplitude wave equation admits envelope and hole solitons in the high frequency mode. from basic sources, we design a programmable electronic generator of complex signals with desired characteristics, which delivers signals exploited as input waves for all our numerical simulations. These simulations are performed in the LTspice software that uses realistic components and give the results that corroborate perfectly our analytical predictions.

关键词： dissipative bi-inductance network high-frequency mode continuous approximation dissipative complex Ginzburg–Landau equation programmable electronic generator LT-Pspice observations

Dynamics of the plane and solitary waves in a Noguchi network:Effects of the nonlinear quadratic dispersion

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Chinese Physics b 2020年第3期29卷 105-111页

作者： S A T fonkoua M S Ngounou G R Deffo f b pelap S b Yamgoue A fomethe Unite de Recherche de Matiere Condensee d’Electronique et de Traitement du Signal(UR-MACETS) Faculte des SciencesUniversite de DschangBP 67 DschangCameroun Unite de Recherche de Mecanique et de Modelisation des Systemes Physiques(UR-2MSP) Faculte des SciencesUniversite de DschangBP 69 DschangCameroun Department of Physics Higher Teacher Training College BambiliUniversity of BamendaP.O.Box 39 BamendaCameroon

We consider a modified Noguchi network and study the impact of the nonlinear quadratic dispersion on the dynamics of modulated waves. In the semi-discrete limit, we show that the dynamics of these waves are governed by a nonlinear cubic Schrodinger equation. from the graphical analysis of the coefficients of this equation, it appears that the nonlinear quadratic dispersion counterbalances the effects of the linear dispersion in the frequency domain. Moreover, we establish that this nonlinear quadratic dispersion provokes the disappearance of some regions of modulational instability in the dispersion curve compared to the results earlier obtained by pelap et al.(Phys. Rev. E 91 022925(2015)). We also find that the nonlinear quadratic dispersion limit considerably affects the nature, stability, and characteristics of the waves which propagate through the system. furthermore, the results of the numerical simulations performed on the exact equations describing the network are found to be in good agreement with the analytical predictions.

关键词： Noguchi network nonlinear quadratic dispersion modulational instability soliton

Time Dependent Entropy and Decoherence in a Modified Quantum Damped Harmonic Oscillator

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Journal of Quantum Information Science 2014年第4期4卷 214-226页

作者： f. b. pelap A. fomethe A. J. fotue M. P. Djemmo Tabue Laboratoire de Mécanique et de Modélisation des Systèmes Physiques (L2MSP) Faculté des Sciences Université de Dschang Dschang Cameroon Laboratory of Mesoscopy and Multilayers Structures Faculty of Science University of Dschang Dschang Cameroon

The time dependence of probability and Shannon entropy of a modified damped harmonic oscillator is studied by using single and double Gaussian wave functions through the feynman path method. We establish that the damped coefficient as well as the system frequency and the distance separating two consecutive waves of the initial double Gaussian function influences the coherence of the system and can be used to control its decoherence.

关键词： Modified Damped Harmonic Oscillator feynman Path Integral Decoherence Shannon Entropy Distribution Probability

Exact solitary wave solutions of a nonlinear Schrdinger equation model with saturable-like nonlinearities governing modulated waves in a discrete electrical lattice

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Chinese Physics b 2018年第12期27卷 420-430页

作者： Serge bruno Yamgoue Guy Roger Deffo Eric Tala-Tebue francois beceau pelap Department of Physics Higher Teacher Training College BambiliThe University ofBamendaP.O.Box 39Bamenda Cameroon Unite de Recherche de Mecanique et de Modelisation des Systemes Physiques (UR-2MSP) Faculte des SciencesUniversite de DschangBP 69DschangCameroun Department of Telecommunication and Network Engineering Fotso Victor University Institute of TechnologyThe University of DschangP.O.Box 134BandjounCameroon

In this paper, we introduce and propose exact and explicit analytical solutions to a novel model of the nonlinear Schr¨odinger(NLS) equation. This model is derived as the equation governing the dynamics of modulated cutoff waves in a discrete nonlinear electrical lattice. It is characterized by the addition of two terms that involve time derivatives to the classical equation. Through those terms, our model is also tantamount to a generalized NLS equation with saturable;which suggests that the discrete electrical transmission lines can potentially be used to experimentally investigate wave propagation in media that are modeled by such type of nonlinearity. We demonstrate that the new terms can enlarge considerably the forms of the solutions as compared to similar NLS-type equations. Sine–Gordon expansion-method is used to derive numerous kink, antikink, dark, and bright soliton solutions.

关键词： nonlinear Schrdinger equation nonlinear time derivative terms saturable nonlinearity exact solitary solutions

Exact transverse solitary and periodic wave solutions in a coupled nonlinear inductor-capacitor network

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Chinese Physics b 2018年第9期27卷 434-443页

作者： Serge bruno Yamgoué Guy Roger Deffo Eric Tala-Tebue francois beceau pelap Department of Physics Higher Teacher Training College Bambili the University of Bamenda Unité de Recherche de Mécanique et de Modélisation des Systèmes Physiques (UR-2MSP) Faculté des Sciences Université de Dschang Department of Telecommunication and Network Engineering Fotso Victor University Institute of Technology The University of Dschang P.O. Box 134 Bandjoun Cameroon

Through two methods, we investigate the solitary and periodic wave solutions of the differential equation describing a nonlinear coupled two-dimensional discrete electrical lattice. The fixed points of our model equation are examined and the bifurcations of phase portraits of this equation for various values of the front wave velocity are presented. Using the sineGordon expansion method and classic integration, we obtain exact transverse solutions including breathers, bright solitons,and periodic solutions.

关键词： nonlinear electrical lattices two-dimensional network sine-Gordon expansion exact transverse solitary wave solutions

Axial magnetic field effect in numerical analysis of high power Cherenkov free electron laser

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Chinese Physics b 2019年第6期28卷 176-183页

作者： f bazoubAND b Maraghechi Department of Physics Fasa UniversityPost code 74616-86131FasaIran Department of Physics Manhattanville CollegePurchaseNew York 10577USA

Cherenkov free electron laser(CfEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab along a growing radiation. The set of coupled nonlinear differential equations of motion is solved to study the electron dynamics. for three sets of parameters, in high power CfEL, it is found that an axial magnetic field is always necessary to keep the electron beam in the interaction region and its optimal strength is reported for each case. At the injection point, the electron beam’s distance above the dielectric surface is kept at a minimum value so that the electrons neither hit the dielectric nor move away from it to the weaker radiation fields and out of the interaction region. The optimal electron beam radius and current are thereby calculated. This analysis is in agreement with two previous numerical studies for a cylindrical waveguide but is at odds with analytical treatments of a flat dielectric that does not use an axial magnetic field. This is backed by an interesting physical reasoning.

关键词： Cherenkov free electron laser axial magnetic field flat dielectric slab electron beam

born from a flood: The Salton Sea and Its Story of Survival

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Journal of Earth Science 2016年第1期27卷 89-97页

作者： Andrew f.b.Tompson Atmospheric Earth and Energy Division Lawrence Livermore National Laboratory Livermore

The Salton Sea is a terminal lake located in the deepest point of the topographically closed Salton Trough in southeastern California. It is currently the largest lake in area in the state. It was created by a flooding event along the Colorado River in 1905-1907, similar to the way historical floods over past centuries created ephemeral incarnations of ancient Lake Cahuilla in the same location. Its position at the center of today＇s Imperial Valley, a hot and arid locale home to some of the most productive irrigated agricultural lands in the United States, has ensured its ongoing survival through a delicate balance between agricultural runoff, its principal form of input, and vast evaporation losses. Nevertheless, its parallel role as a recreational resource and important wildlife habitat, established over its first century of existence, is threatened by increasing salinity decreasing water quality, and reduced water allocations from the Colorado River that feeds the valley＇s agriculture. The Salton Sea faces an increasingly uncertain future that will be influenced by reduced water imports from the Colorado River, demands for additional water sources to support farming and energy industries in the valley, and needs to stabilize the lake salinity, maintain recreational resources, and preserve what have become important ecosystems and wildlife habitats.

关键词： Salton Sea flood terminal lake water agriculture salinity wildlife habitat.

Three-dimensional simulation of long-wavelength free-electron lasers with helical wiggler and ion-channel guiding

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Chinese Physics b 2013年第7期22卷 183-191页

作者： f. Jafari bahman b. Maraghechi Department of Physics Amirkabir University of Technology

A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （fEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear differential equations for electron orbits and fields of TE 11 mode in a cylindrical waveguide are solved numerically by the Runge–Kutta algorithm with averages calculated by the Gaussian quadrature technique. Self-fields and space-charge effects are neglected, and the electron beam is assumed to be cold and slippage is ignored. The parameters correspond to the Compton regime. Evolution of the radiation power and growth rate along the wiggler is studied. Ion-channel density is chosen to obtain optimum efficiency. Simulations are preformed for the fEL operating in the neighborhood of 35 GHz and 16.5 GHz for the electron beam energies of 250 keV and 400 keV, respectively. The result of the saturated efficiency was found to be in good agreement with the simple estimation based on the phase-trapping model.

关键词： free-electron laser helical wiggler ion-channel guiding

Effect of functionalized Multi-walled Carbon Nanotubes with Poly(N-vinyl pyrrolidone-co-2-acrylamido-2-methyl-1-propanesulfonic acid) on the Release of Tramadol Hydrochloride

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Chinese Journal of Polymer Science 2015年第3期33卷 376-385页

作者： Ahmed Awadallah-f Tahia b.Mostafa National Center for Radiation Research and Technology Chemistry Department University College for WomenAin Shams University

Multi-walled carbon nanotubes （MWCNTs） were grafted with poly（N-vinyl-2-pyrrolidone） and with poly（2- acrylamido-2-methyl-1-propanesulfonic acid） at different compositions by using y-rays technique as initiator. The MWCNTs, MWCNT-graft-PNVP, MWCNT-graft-PAMPS and MWCNTs-graft-P（NVP-co-AMPS） were characterized by fourier transform infra red （fTIR） spectroscopy, X-ray diffraction （XRD）, thermal gravimetric analysis （TGA）, elemental analysis and high-resolution transmission electron microscopy （HR-TEM）. The results indicated that the grafting processes of PNVP, PAMPS and P（NVP-co-AMPS） occurred on to the surfaces of MWCNTs without destroying the framework of MWCNTs. Tramadol hydrochloride （TH） was loaded as model drug and its release behavior was analyzed via various kinetic models. Release of the loaded TH was studied in simulated gastric fluid （SGf, pH = 1.2） and simulated intestinal fluid （SIf, pH = 7.4） at 37 ℃. Controlled release of TH from grafted MWCNTs was investigated. The outcome results suggest that the grafted MWCNTs could be used as a promising matrix candidate for oral drug delivery system by harmonization between the composition and pH level of the simulated biological fluids.

关键词： Polymer grafting Gamma irradiation Multi-walled carbon nanotubes Controlled release Tramdol hydrochloride.