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Effects of magnet Size and Geometry on magnetic Levitation Force

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Chinese Physics Letters 2007年第9期24卷 2664-2666页

作者： m. K. alqadi h. m. al-khateeb F. Y. alzoubi N. Y. Ayoub Department of Physics Jordan University of Science and Technology Irbid Jordan School of Natural Applied Sciences German Jordanian University Amman Jordan

We obtain analytical relations for the levitation force as a function of dimensions of the superconductor-magnet system. The force has been calculated on the basis of the dipole-dipole interaction model. The effect of thickness of the superconductor on the levitation force is investigated. The results show that the influence of geometry and thickness of the magnet becomes significantly large at small levitation distances. Furthermore, approximating the permanent magnet as a point dipole results in an inaccurate estimation of the levitation force.

关键词： mEISSNER STATE

Angular Dependence of Lateral and Levitation Forces in Asymmetric Small magnet/Superconducting Systems

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Chinese Physics Letters 2007年第9期24卷 2700-2703页

作者： h. m. al-khateeb m. K. alqadi F. Y. alzoubi N. Y. Ayoub Department of Physics Jordan University of Science and Technology Irbid Jordan School of Applied Natural Sciences German Jordanian University Amman Jordan

The dipole-dipole interaction model is used to calculate the angular dependence of lateral and levitation forces on a small permanent magnet and a cylindrical superconductor in the meissner state lying laterally off the symmetric axis of the cylinder. Under the assumption that the lateral displacement of the magnet is small compared with the physical dimensions of the system, we obtain analytical expressions for the lateral and levitation forces as functions of geometrical parameters of the superconductor as well as the height, the lateral displacement and the orientation of magnetic moment of the magnet. The effect of thickness and radius of the superconductor on the levitation force is similar to that for a symmetric magnet/superconducting cylinder system, but within the range of lateral displacement. The splitting in the levitation force increases with the increasing angle of orientation of the magnetic moment of the magnet. For a given lateral displacement of the magnet, the lateral force vanishes when the magnetic moment is perpendicular to the surface of the superconductor and has a maximum value when the moment is parallel to the surface. For a given orientation of the magnetic moment, the lateral force has a linear relationship with the lateral displacement. The stability of the magnet above the superconducting cylinder is discussed in detail.

关键词： ThIN SUPERCONDUCTING DISKS mEISSNER STATE mAGNETIC-LEVITATION PERmANENT-mAGNET CERAmICS CYLINDER SAmPLE

Vibrations in magnet/Superconductor Levitation Systems

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Chinese Physics Letters 2006年第6期23卷 1641-1644页

作者： F. Y. alzoubi h. m. al-khateeb m. K. alqadi N. Y. Ayoub Department of Physics Jordan University of Science and Technology Irbid Jordan Department of Physics Yarmouk University Irbid Jordan School of Applied Natural Sciences German Jordanian University Amman Jordan

The problem of a small magnet levitating above a very thin superconducting disc in the meissner state is analysed. The dipole-dipole interaction model is employed to derive analytical expressions for the interaction energy, levitation force, magnetic stiffness and frequency of small vibrations about the equilibrium position in two different configurations, i.e. with the magnetic moment parallel and perpendicular to the superconductor. The results show that the frequency of small vibrations decreases with the increasing levitation height for a particular radius of the superconducting disc, which is in good agreement with the experimental results. however, the frequency increases monotonically up to saturation by increasing the radius of the disc for a particular height of the magnet. In addition, the frequency of vibrations is higher when the system is in the vertical configuration than that when the system is in the horizontal configuration.

关键词： mEISSNER STATE SmalL mAGNET FORCE STIFFNESS SUPERCONDUCTORS SIZE

L-shell x-ray fluorescence relative intensities for elements with 62≤Z≤83 at 18 keV and 23 keV by synchrotron radiation

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Chinese Physics B 2023年第8期32卷 270-273页

作者： m alqadi S al-humaidi h alkhateeb F alzoubi Department of Physics Jordan University of Science and TechnologyIrbidJordan

The relative intensities of L-subshell x-ray fluorescence(XRF)for elements with atomic numbers 62≤Z≤83 were measured at two excitation energies,18 keV and 23 keV,using a synchrotron radiation source at a beamline of the Synchrotron Light Center for Experimental Science and Applications in the middle East(SESAmE),*** experimentally measured results of the relative intensities were compared with the calculated results using the subshell fluorescence yield and the Coster-Kronig transition probabilities recommended by Campbell and the values based on the Dirac-hartree-Slater model by *** experimental and theoretical results are in *** this work,L XRF relative intensities for the elements Sm,Gd,Tb,Er,Ta,W,Re,hg,Pb and Bi at energies of 18 keV and 23 keV were measured.

关键词： L shell x-ray fluorescence(XRF) relative intensities synchrotron radiation

Widely tunable linear-cavity multiwavelength fiber laser with distributed Brillouin scattering

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Chinese Optics Letters 2011年第3期9卷 51-53页

作者： m.Ajiya m.h.al-mansoori m.A.mahdi Department of Electrical Engineering Faculty of TechnologyBayero University Faculty of Engineering Sohar University Wireless and Photonics Networks Research Center Faculty of EngineeringUniversiti Putra Malaysia

We demonstrate a multiple wavelength Brillouin/erbium fiber laser in a linear cavity *** laser cavity is made up of a fiber loop mirror on one end of the resonator and a virtual mirror generated from the distributed stimulated Brillouin scattering effect on the other *** to the weak reflectivity provided by the virtual mirror,self-lasing cavity modes are completely suppressed from the laser *** Brillouin pump and 1480-nm pump powers of 2 and 130 mW,respectively,11 channels of the demonstrated laser with an average total power of 7.13 dBm can freely be tuned over a span of 37-nm wavelength from 1530 to 1567 nm.

关键词： EDFA Widely tunable linear-cavity multiwavelength fiber laser with distributed Brillouin scattering dBm nm OSNR DCF SBS

mhD natural convection with Joule and viscous heating effects in iso-flux porous medium-filled enclosures

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Applied mathematics and mechanics(English Edition) 2010年第9期31卷 1105-1112页

作者： Y.m.al-BADAWI h.m.DUWAIRI mechanical Engineering Department Faculty of Engineering and TechnologyThe University of Jordan

In this study, the magnetohydrodynamics （mhD） natural convection heat transfer with Joule and viscous heating effects inside an iso-flux porous medium-filled inclined rectangular enclosure is studied numerically. An iso-heat flux is applied for heating and cooling the two opposing walls of the enclosure while the other walls are adiabatic. The Forchheimer extension of Darcy-Oberbeck-Boussinesq and energy equations is transformed into a dimensionless form using a set of suitable variables instead of a finite difference scheme. The governing parameters are the magnetic influence number, the modified Rayleigh number, the inclination angle, and the aspect ratio of the enclosure. The results show that viscous and Joule heating effects decrease heat transfer rates.

关键词： magnetohydrodynamics (mhD) natural convection porous media

Dual-Wavelength Passively Q-Switched Ytterbium-Doped Fiber Laser Based on aluminum Oxide Nanoparticle Saturable Absorbers

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Chinese Physics Letters 2017年第11期34卷 24-27页

作者： S.K.m.al-hayali S.Selleri A.h.al-Janabi Institute of Laser for Postgraduate Studies University of Baghdad Department of Information Engineering Parma University

We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （al2O3-NP） thin film. A thin film of al2O3 was prepared by embedding al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 khz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.

关键词： SA Dual-Wavelength Passively Q-Switched Ytterbium-Doped Fiber Laser Based on aluminum Oxide Nanoparticle Saturable Absorbers

Non-integer Order Control Scheme for Pressurized Water Reactor Core Power

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Computers, materials & Continua 2022年第7期72卷 651-662页

作者： Ibrahim m.mehedi maher h.al-Sereihy Asmaa Ubaid al-Saggaf Ubaid m.al-Saggaf Department of Electrical and Computer Engineering(ECE) King Abdulaziz UniversityJeddah21589Saudi Arabia Center of Excellence in Intelligent Engineering Systems(CEIES) King Abdulaziz UniversityJeddah21589Saudi Arabia

Tracking load changes in a pressurized water reactor(PWR)with the help of an efficient core power control scheme in a nuclear power station is very *** reason is that it is challenging to maintain a stable core power according to the reference value within an acceptable tolerance for the safety of *** overcome the uncertainties,a non-integer-based fractional order control method is demonstrated to control the core power of *** available dynamic model of the reactor core is used in this *** power is controlled using a modified state feedback approach with a non-integer integral scheme through two different approximations,CRONE(Commande Robuste d’Ordre Non Entier,meaning Non-integer orderRobust Control)and FOmCON(non-integer order modeling and control).Simulation results are produced using mATLAB■*** non-integer results are compared with an integer order PI(Proportional Integral)algorithm to justify the effectiveness of the proposed ***-spacemodel Core power control Non-integer control Pressurized water reactor PI controller CRONE FOmCON.

关键词： Sate-space model core power control non-integer control pressurized water reactor PI controller CRONE FOmCON

Two-Point Resistance on the Centered-Triangular Lattice

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Chinese Physics Letters 2018年第2期35卷 6-10页

作者： m.Q.Owaidat A.A.al-Badawi J.h.Asad mohammed al-Twiessi Department of Physics Al-Hussein Bin Talal University Department of Physics Faculty of SciencesTaibah University Department of Physics Faculty of Arts and SciencesPalestine Technical University

The resistance between any two lattice points in an infinite, centered-triangular lattice of equal resistors is determined using the lattice Green function method. It is shown that the two-point resistance on the centered-triangular lattice is expressed in terms of the resistance of a triangular lattice. Some exact values for the resistance near the origin of the lattice are presented. For large separation between lattice points the asymptotic forms of the resistance are calculated.

关键词： Two-Point Resistance on the Centered-Triangular Lattice