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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

Nonlinear continuous bi-inductance electrical line with dissipative elements:Dynamics of the low frequency modulated waves

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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

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.

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极限拍摄大冒险

小哥白尼（趣味科学） 2013年第6期 2-7页

作者： a.f V.b bbC

带上一幅100年来都未曾更新过的地图,登上俄罗斯的破冰船——哦,也许是老掉牙的"金羊毛"号——那艘首次穿越南极的小艇,再聚齐一大帮志同道合、勇敢又可爱的家伙,奔赴南极和北极的冰天雪地,完成跨越地球的极限拍摄!

关键词：熔岩湖金羊毛杰夫山烟着陆点就这样影像制作大卫保暖内衣下甲

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.

UV/visible spectroscopic analysis of CO^(3+) and CO^(2+) during the dissolution of cobalt from mixed Co-Cu oxidized ores

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 260-269页

作者： J. Ndalamo a.f. Mulaba-bafubiandi b.b. Mamba Department of Chemical Technology University of Johannesburg Department of Extraction Metallurgy University of Johannesburg

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H2SO4 and SO2 as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solu-tions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO2. fur-thermore, UV/visible spectroscopy confirmed that as SO2 was flushed into the acidified leaching solution, Co3＋ bearing minerals were re-duced to the readily soluble Co2＋ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co3＋ to Co2＋ bearing minerals when SO2 is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co3＋, Co2＋, and Cu2＋ complexes, as shown by their UV/visible spectra, are also discussed.

关键词： cobalt metallurgy dissolution leaching reaction kinetics spectroscopic analysis

Impact analysis of compressor rotor blades of an aircraft engine

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frontiers of Structural and Civil Engineering 2019年第3期13卷 505-514页

作者： Y b SUDHIR SASTRY b G KIROS f HAILU R bUDARAPU Department of Aeronautical Engineering Institute of Aeronautical EngineeringDundigalHyderabad 500043India Department of Aeronautical Engineering College of EngineeringDefense UniversityBishoftu 1041Ethiopia School of Mechanical Sciences Indian Institute of Technology BhubaneswarBhubaneswar 752050India

frequent failures due to foreign particle impacts are observed in compressor blades of the interceptor fighter MIG-23 aircraft engines in the Ethiopian air force,supplied by the Dejen Aviation *** this paper,we made an attempt to identify the causes of failure and hence recommend the suitable materials to withstand the foreign particle *** and stress analysis of one of the recently failed MIG-23 gas turbine compressor blades made up of the following Aluminum based alloys:6061-T6,7075-T6,and 2024-T4,has been performed,apart from the impact analysis of the rotor blades hit by a granite *** numerical results are correlated to the practical *** on the modal,stress and impact analysis and the material properties of the three considered alloys,alloy 7075-T6 has been recommended as the blade material.

关键词： axial flow compressor rotor and stator blades aircraft engine stress and impact analysis aluminum alloys