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Plasma Science and Technology 2019年第1期21卷 63-71页

作者： A m EL SHERBINI m m HAGRASS m R m RIZK E A EL-BADAWY Laboratory of Laser and New materials Faculty of Science Cairo University Faculty of Engineering Electrical Engineering Department Alexandria University

Plasma ignition threshold of nanoparticle-based and bulk silver targets was measured in air. The plasma was initiated by a Nd:YAG laser at wavelengths of 355, 532, and 1064 nm. The plasma ignition was monitored utilizing the prominent Ag I line at 546.5 nm. Lower ignition thresholds of the nanoparticle-based silver target were estimated at 0.4?±?0.02, 0.34?±?0.04, and 0.27?±?0.035 J cm^(-2) coupled with the different laser wavelengths, respectively. In contrast, the bulk silver target plasma exhibited an order of magnitude higher ignition threshold. A three orders of magnitude enhanced emission intensity from the nano-based target over the bulk target was achieved at lower levels of laser irradiation. A reduction of the thermal diffusion length of the nanosilver was assumed in order to theoretically predict this reduction in the plasma threshold. In addition, the effect of self-reversal on the resonance lines was taken into consideration.

关键词： NELIBS enhancement nanosilver laser plasma threshold

Hunting down the ohmic contact of organic field-effect transistor

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Chinese Physics B 2019年第11期28卷 382-387页

作者： m micjan m Novota P Telek m Donoval m Weis Institute of Electronics and Photonics Slovak University of Technology

We report properties of contact resistances observed on pentacene organic field-effect transistors(OFET) with four different source/drain electrodes, namely, copper(Cu), gold(Au), silver(Ag), and germanium(Ge). The metals were selected to provide a wide range of energy barriers for charge injection, from blocking contact to smooth injection. All OFETs exhibited strong voltage dependence of the contact resistance, even for devices with smooth injection, which is in strong disagreement with the definition of ohmic contacts. A comparison with current crowding, resistive network, Fowler–Nordheim tunneling, and electric field enhanced thermionic injection(Schottky emission) pointed to importance of local electric fields and/or electrostatic field charges.

关键词： organic field-effect transistors contact resistance charge injection

Performance of m-QAm, m-DPSK and m-PSK with mRC diversity in a Nakagami-m fading channel

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Journal of Central South University 2014年第4期21卷 1347-1352页

作者： Alam S.m.Shamsul Alam Choi GoangSeog Department of Information and Communication Engineering Chosun University

The nature of a wireless communication channel is very unpredictable. To design a good communication link, it is required to know the statistical model of the channel accurately. The average symbol error probability(ASER) was analyzed for different modulation schemes. A unified analytical framework was presented to obtain closed-form solutions for calculating the ASER of m-ary differential phase-shift keying(m-DPSK), coherent m-ary phase-shift keying(m-PSK), and quadrature amplitude modulation(QAm) over single or multiple Nakagami-m fading channels. moreover, the ASER was estimated and evaluated by using the maximal ratio-combining(mRC) diversity technique. Simulation results show that an error rate of the fading channel typically depends on Nakagami parameters(m), space diversity(N), and symbol rate(m). A comparison between m-PSK, m-DPSK, and m-QAm modulation schemes was shown, and the results prove that m-ary QAm(m-QAm) demonstrates better performance compared to m-DPSK and m-PSK under all fading and non-fading conditions.

关键词： m-ary differential phase-shift keying(m-DPSK) m-ary phase shift keying(m-PSK) Nakagami-m fading channel probability density function(PDF) symbol error rate(SER) m-ary quadrature amplitude modulation(m-QAm)

Effect of Bohm quantum potential in the propagation of ion–acoustic waves in degenerate plasmas

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Chinese Physics B 2016年第10期25卷 222-229页

作者： m m Hasan m A Hossen A Rafat A A mamun Department of Physics Jahangirnagar University

A theoretical investigation has been carried out on the propagation of the ion–acoustic(IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries(K-dV), modified K-dV(m K-dV), and mixed m K-dV(mm K-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features(phase speed, amplitude, width,etc.) of the IA solitary waves(SWs), the SWs solutions of the K-dV, m K-dV, and mm K-d V are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects(arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g.,white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser–solid matter interaction experiments, etc., are mentioned.

关键词： Bohm quantum potential degenerate relativistic plasma electron and positron quantum effect

Influence of cerium ions on structure-dependent magnetic properties of Ba-Sr m-type hexaferrite nanocrystals

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Journal of Rare Earths 2024年第2期42卷 364-372,I0005页

作者： Ram A.Pawar Sunil m.Patange P.m.Dighe Sher Singh meena Abdullah GAl-Sehemi mehboobali Pannipara Santosh S.Jadhav Department of Physics ArtsCommerce and Science CollegeAhmednagar413711MaharashtraIndia Department of Physics Shri Krishna MahavidyalayaGunjotiDistOsmanabad413606MaharashtraIndia Padmashri Vikhe Patil College of Arts Science and CommercePravaranagarA/P.Loni(Kd)Tal.RahataDistAhmednagar413713MaharashtraIndia Solid State Physics Division Bhabha Atomic Research CentreMumbai400085MaharashtraIndia Department of Chemistry King Khalid UniversityAbha61413Saudi Arabia Department of Physics D.S.M's ArtsCommerce and Science CollegeJintur431509MaharashtraIndia

The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) where x=0.0-0.2 with Δx=*** hexaferrite powders were prepared using the sol-gel self-ignition route and structurally characterized by means of powder X-ray diffraction and Fourier transform infrared *** creation of the m-type hexaferrite phase within the synthesized samples was revealed from the Rietveld refinement of the X-ray *** occurrence of a secondary phase of CeO_(2) was revealed within the hexaferrites for the substitution,x> *** refined X-ray diffraction data were utilized to compute the lattice parameters,X-ray density,and lattice parameter *** crystal structure plotted from the refined XRD data reveals the occupancy of the ions at different lattice *** XPS data of the hexaferrite were analyzed to confirm the oxidation states of the constituent *** nanocrystalline nature of the hexaferrites was revealed from the crystallite sizes calculated using Scherer's *** analysis of FTIR spectra confirms that only a fraction of Ce^(3+)accommodated in the lattice and the remaining Ce content reside in the form of the CeO_(2) *** morphology of the hexaferrites was analyzed from the FESEm profiles of the ferrite *** magnetic behavior study was performed by analyzing the Curie temperature,hysteresis loops,and hyperfine interactions by means of susceptibility,V.S.m,and mossbauer spectroscopy,*** hexaferrites with increasing coercivity,decreasing saturation magnetization,and decreasing Curie temperature are reported in the *** substituted Ce^(3+)ions inhibit the grain growth and create lattice imperfections giving rise to hexaferrites with tuned magnetic parameters suitable for different applications.

关键词： Ba-Sr hexaferrite Ce^(3+)substitution XPS Saturation magnetization Coercivity m?ssbauer spectroscopy

Damage Identification of A TLP Floating Wind Turbine by meta-Heuristic Algorithms

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China Ocean Engineering 2015年第6期29卷 891-902页

作者： m.m.Ettefagh mechanical Engineering Department University of Tabriz

Damage identification of the offshore floating wind turbine by vibration/dynamic signals is one of the important and new research fields in the Structural Health monitoring（SHm）. In this paper a new damage identification method is proposed based on meta-heuristic algorithms using the dynamic response of the TLP（Tension-Leg Platform） floating wind turbine structure. The Genetic Algorithms（GA）, Artificial Immune System（AIS）, Particle Swarm Optimization（PSO）, and Artificial Bee Colony（ABC） are chosen for minimizing the object function, defined properly for damage identification purpose. In addition to studying the capability of mentioned algorithms in correctly identifying the damage, the effect of the response type on the results of identification is studied. Also, the results of proposed damage identification are investigated with considering possible uncertainties of the structure. Finally, for evaluating the proposed method in real condition, a 1/100 scaled experimental setup of TLP Floating Wind Turbine（TLPFWT） is provided in a laboratory scale and the proposed damage identification method is applied to the scaled turbine.

关键词： floating wind turbine multi-body dynamics damage identification meta-heuristic algorithms optimization

Approximate solutions for the problem of liquid film flow over an unsteady stretching sheet with thermal radiation and magnetic field

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Applied mathematics and mechanics(English Edition) 2018年第6期39卷 867-876页

作者： m.m.KHADER Department of mathematics and Statistics College of ScienceAl-Imam Mohammad Ibn Saud Islamic University(IMSIU) Department of mathematics Faculty of ScienceBenha University

The proposed method is based on replacement of the unknown function by a truncated series of the shifted Legendre polynomial expansion. An approximate formula of the integer derivative is introduced. Special attention is given to study the convergence analysis and derive an upper bound of the error for the presented approximate formula. The introduced method converts the proposed equation by means of collocation points to a system of algebraic equations with shifted Legendre coefficients. Thus, after solving this system of equations, the shifted Legendre coefficients are obtained. This efficient numerical method is used to solve the system of ordinary differential equations which describe the thin film flow and heat transfer with the effects of the thermal radiation, magnetic field, and slip velocity.

关键词： liquid film thermal radiation unsteady stretching sheet Legendrecollocation method convergence analysis

mssbauer and electron microscopy study of martensitic transformations in an Fe-mn-mo alloy

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International Journal of minerals,metallurgy and materials 2010年第4期17卷 448-452页

作者： T.Kirindi U.Sari m.Kurt Department of Computer Education and Instructional Technology Kirkkale University Kirkkale 71450Turkey Institute of Sciences Kirkkale University Yahsihan CampusKirkkale 71450Turkey

The kinetic,morphological,crystallographic,and magnetic characteristics of thermally induced martensites in Fe-13.4wt% mn-5.2wt%mo alloy were investigated by scanning electron microscopy（SEm）,transmission electron microscopy（TEm）,and m（o｜¨）ssbauer *** experimental results reveal that two types of thermal-induced martensites,e（hcp） andα＇（bcc） martensites,are formed in the as-quenched condition,and these transformations have athermal *** addition to the Fe-mn alloy does not change the coexistence ofεandα＇ martensites with the mn content between 10wt%and 15wt%.Besides,m（o｜¨）ssbauer spectra reveal a paramagnetic character with a singlet for theγ（fcc） austenite andεmartensite phases and a ferromagnetic character with a broad sextet for theα＇ martensite phase. The volume fraction ofα＇ martensite forming in the quenched alloy is much more than that of theεmartensite.

关键词： Fe-mn alloy molybdenum martensitic transformation scanning electron microscopy(SEm) transmission electron microscopy(TEm) mossbauer spectroscopy

Optimizing the Preparation Parameters of Nanocrystalline Zirconia for Catalytic Applications

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Acta metallurgica Sinica(English Letters) 2013年第5期26卷 565-573页

作者： m.m.Abd El-Latif m.S.Showman A.m.Ibrahim m.m.Soliman Fabrication Technology Department Advanced Technology and New Materials Research Institute(ATNMRI) City of Scientific Research and Technological Applications (SRTA-City) Dharyya Colleges for Science and Atrs Qassim University Surface Chemistry and Catalysis Laboratory Physical Chemistry Department National Research Center Department of materials Science Institute of Graduate Studies and Research Alexandria University

Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations＇ temperature are *** size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction（XRD）, thermo gravimetric analysis（TGA）, diferential scanning calorimetry（DSC）, BET surface area, scanning electron microscopy（SEm） and transmission electron microscopy（TEm）. The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations＇ temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity（60%） for synthesis of butyl acetate ester.

关键词： Tetragonal zirconia Nanocrystalline zirconia Precipitation synthesis Catalytic properties of zirconia Esterification with zirconia

Dissipative dynamics of an entangled three-qubit system via non-Hermitian Hamiltonian: Its correspondence with markovian and non-markovian regimes

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Chinese Physics B 2021年第3期30卷 283-292页

作者： m Rastegarzadeh m K Tavassoly Laser and Optics Group Faculty of PhysicsYazd UniversityYazd 89195-741Iran

We investigate an entangled three-qubit system in which only one of the qubits experiences the decoherence effect by considering a non-Hermitian Hamiltonian,while the other two qubits are isolated,i.e.,do not interact with environment,***,the time evolution of the density matrix(for the pure as well as mixed initial density matrix)and the corresponding reduced density matrices are obtained,by which we are able to utilize the dissipative non-Hermitian Hamiltonian model with markovian and non-markovian regimes via adjusting the strange of the non-Hermitian term of the total Hamiltonian of the under-considered system.

关键词： non-Hermitian Hamiltonian entanglement concurrence measure markovian and non-markovian regimes