检索结果-南通市图书馆

Asymmetry ratio as a parameter of Eu^3＋ local environment in phosphors

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2018年第5期36卷 474-481页

作者： Ilya E. Kolesnikov Alexey V. Povolotskiy Daria V. Mamonova Evgeny Yu. Kolesnikov Alexey V. Kurochkin Erkki Lahderanta Mikhail D. Mikhailov Saint Petersburg State University 7/9 Universitetskaya nab. 199034 St.petersburg.Russia Lappeenranta University of Technology LUT Skinnarilankatu 34 53850 Lappeenranta Finland Scientific and Technological Institute of Optical Material Science VNTs S. I. Vavilov State Optical Institute Babushkina 36-1 192171 St. Petersburg Russia Volga State University of Technology Lenin Sq. 3 424000 Yoshkar-Ola Russia

Study of the local environment of certain ion is quite a complex problem. Due to the unique luminescent properties, Eu^3＋ ions can be used as a structural probe. In this paper, effect of doping concentration,excitation wavelength and excitation mechanism on asymmetry ratio was systematically studied using Y3Al5O12：Eu^3＋, YVO4：Eu^3＋ and Y2O3：Eu^3＋nanophosphors. The asymmetry ratio gives information about the local surrounding and environmental changes around the Eu^3＋ ions. Asymmetry ratios of YAG：Eu^3＋and YVO4：Eu^3＋ nanopowders were calculated using standard technique and the obtained average values were found to be 0.75 and 8.2, respectively. However, it is found that standard method of asymmetry ratio calculation is suitable only for samples where all Eu^3＋ ions occupy one site. The ＂multisite model＂ of asymmetry ratio calculation was developed and used for Y2O3：Eu^3＋ nanocrystalline powders. Average value of asymmetry ratio for Eu^3＋ ions occupied ＂normal＂ sites is 6.0 and for Eu^3＋ ions occupied ＂defect＂sites is 2.3.

关键词： Eu3+ Oxide powders Luminescence Asymmetry ratio Structural probe Rare earths

Application of thermally stimulated acoustic emission method to assess the thermal resistance and related properties of coals

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2018年第2期28卷 243-249页

作者： E.A.Novikov R.O.Oshkin V.L.Shkuratnik S.A.Epshtein N.N.Dobryakova National University of Science and Technology(MISiS) Moscow 119049Russia

Traditional methods of coal thermal resistance characterization are informative but considerably timeconsuming and require utilization of a complex and expensive equipment. This limits the effectiveness of their application. In this paper, authors experimentally investigated potential application of thermally stimulated acoustic emission method for developing of relatively simple and rapid coals thermal resistance assessment method. Features of thermally stimulated acoustic emission of anthracite, lignites and bituminous coal samples subject to cyclic thermal loading have been experimentally *** the first time, it has been shown that there exists a relationship of such patterns with structural parameters and properties of the coal samples, as well as their thermal resistance. The results indicate the possibility of applying the method of thermally stimulated acoustic emission to control processes of cryogenic disintegration and thermal resistance of fossil coals. The description of the equipment and methodological support needed for the implementation of this method have been provided.

关键词： Acoustic emission Fossil coal Thermal resistance Cryogenic disintegration Structure Properties

Multi-Objective Weather Routing Algorithm for Ships Based on Hybrid Particle Swarm Optimization

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2022年第1期21卷 28-38页

作者： ZHAO Wei WANG Hongbo GENG Jianning HU Wenmei ZHANG Zhanshuo ZHANG Guangyu State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130000China China State Shipbuilding Corporation(CSSC)Marine Technology Co. Ltd.Beijing 100070China

Maritime transportation has become an important part of the international trade *** promote its sustainable de-velopment,it is necessary to reduce the fuel consumption of ships,decrease navigation risks,and shorten the navigation ***-cordingly,planning a multi-objective route for ships is an effective way to achieve these *** this paper,we propose a multi-ob-jective optimal ship weather routing system *** on this framework,a ship route model,ship fuel consumption model,and navigation risk model are established,and a non-dominated sorting and multi-objective ship weather routing algorithm based on particle swarm optimization is *** fasten the convergence of the algorithm and improve the diversity of route solutions,a mutation operation and an elite selection operation are introduced in the *** on the Pareto optimal front and Pareto optimal solution set obtained by the algorithm,a recommended route selection criterion is ***,two sets of simulated navigation simulation experiments on a container ship are *** experimental results show that the proposed multi-objective optimal weather routing system can be used to plan a ship route with low navigation risk,short navigation time,and low fuel consumption,fulfilling the safety,efficiency,and economic goals.

关键词： weather routing particle swarm optimization route planning multi-objective optimization

Supercritical CO_2: Properties and Technological Applications-A Review

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2019年第3期28卷 394-430页

作者： NIKOLAI Polikhronidi RABIYAT Batyrova ASLAN Aliev ILMUTDIN Abdulagatov Thermodynamics of Fluids and Critical Phenomena Institute of Physics of the Dagestan Scientific Center of the Russian Academy of Sciences Mountain Botanical Garden of the Dagestan Scientific Center of the russian Academy of Sciences Thermophysics Division Geothermal Research Institute of the Russian Academy of Sciences Physical Chemistry Department Dagestan State University

The main goal of the present paper is to assess the available information so as to obtain a general procedure for dealing with the critical enhancement of the thermodynamic and transport properties of supercritical CO_2 and CO_2 containing binary mixtures for practical and scientific applications. The present review provides comprehensive analysis of the thermodynamic and transport properties of supercritical carbon dioxide and CO_2 containing binary mixtures(experiment and theory) and their various technological and scientific applications in different natural and industrial processes. The available information for the thermodynamic and transport properties(experiment and theory) enhancement(anomaly) of supercritical carbon dioxide and SC CO_2 + solute mixtures is comprehensively reviewed. The effect of long-range order parameter fluctuations on the thermodynamic and transport properties of supercritical fluids(SC CO_2) will be discussed. Simplified scaling type equation based on mode-coupling theory of critical dynamics with two critical amplitudes and one cutoff wave number as fluid-specific parameters was used to accurately predict of the transport properties of supercritical carbon dioxide. The recommended values of the specific parameters(asymptotic critical amplitudes) of the carbon dioxide for practical(prediction of the thermodynamic and transport properties of the supercritical CO_2 for technological applications) and scientific use were provided. The role of the critical line shapes of the carbon dioxide containing binary mixture(SC CO_2+solvent) in determination of the critical behavior of the mixture near the critical point of pure supercritical solvent(CO_2) is discussed. Krichevskii parameter concept for a description of thermodynamic behavior of dilute near-critical SC CO_2+solute mixtures is also discussed. The structural and thermodynamic properties of the carbon dioxide containing binary mixtures near the critical point of pure solvent(CO_2) are d

关键词： carbon dioxide critical point equation of state supercritical fluid thermodynamic properties transport properties

Terahertz frequency selective surfaces using heterostructures based on two-dimensional diffraction grating of single-walled carbon nanotubes

在线全文

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2023年第1期14卷 21-35页

作者： Pavel Evgenjevich Timoshenko Alexander Lerer Sergei Bernardovich Rochal Pavel E.Timoshenko Faculty of Physics Southern Federal UniversityRostov-on-DonRussia Southern Federal University Rostov-on-DonRussia

For single-walled carbon nanotubes(SWCNTs)with a length of 1-50μm,the surface plasmon-polariton(SPP)resonance is within the terahertz frequency range;therefore,SWCNT lattices can be used to design frequency-selective surface(FSS).A numerical model of electromagnetic wave diffraction on a two-dimensional periodic SWCNT lattice can be described by an integro-differential equation of the second-order with respect to the surface current along *** equation can be solved by the Bubnov-Galerkin *** dependence of reflecting and transmitting electromagnetic waves for FSSs near the SPP resonance is studied *** is shown that the resonances are within the lowerfrequency part of the terahertz *** also estimate the relaxa-tion frequency of an individual SWCNT and demonstrate the applic-ability of the Kubo formula for graphene conductivity to array of strips similar in size to SWCNTs under consideration.

关键词： Carbon nanotubes gratings graphene surface plasmon polaritons dielectric response functions

A Pseudo-Spectral Scheme for Systems of Two-Point Boundary Value Problems with Left and Right Sided Fractional Derivatives and Related Integral Equations

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

Computer Modeling in Engineering & Sciences 2021年第7期128卷 21-41页

作者： I.G.Ameen N.A.Elkot M.A.Zaky A.S.Hendy E.H.Doha Department of Mathematics Faculty of ScienceAl-Azhar UniversityCairoEgypt Department of Mathematics Faculty of ScienceCairo UniversityGiza12613Egypt Department of Applied Mathematics Physics DivisionNational Research CentreDokkiCairo12622Egypt Department of Computational Mathematics and Computer Science Institute of Natural Sciences and MathematicsUral Federal UniversityYekaterinburg620002Russia Department of Mathematics Faculty of ScienceBenha UniversityBenha13511Egypt

We target here to solve numerically a class of nonlinear fractional two-point boundary value problems involving left-and right-sided fractional *** main ingredient of the proposed method is to recast the problem into an equivalent system of weakly singular integral ***,a Legendre-based spectral collocation method is developed for solving the transformed ***,we can make good use of the advantages of the Gauss quadrature *** present the construction and analysis of the collocation *** results can be indirectly applied to solve fractional optimal control problems by considering the corresponding Euler–Lagrange *** numerical examples are given to confirm the convergence analysis and robustness of the scheme.

关键词： Spectral collocation method weakly singular integral equations two-point boundary value problems convergence analysis

Uncertainty of Climate Response to Natural and Anthropogenic Forcings Due to Different Land Use Scenarios

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

Advances in Atmospheric Sciences 2011年第5期28卷 1215-1232页

作者： Alexey V.ELISEEV Igor I.MOKHOV A. M. Obukhov Institute of Atmospheric Physics Russian Academy of Sciences3 Pyzhevsky 119017 Moscow Russia

The *** Institute of Atmospheric Physics,russian Academy of Sciences （IAP RAS） climate model （CM） of intermediate complexity is extended by a spatially explicit terrestrial carbon cycle *** experiments with the IAP RAS CM are performed forced by the reconstructions of anthropogenic and natural forcings for the 16th to the 20th centuries and by combined SRES （Special Report on Emission Scenarios） A2-LUH （Land Use Harmonization） anthropogenic scenarios for the 21st ***,the impact of uncertainty in land-use scenarios on results of simulations with a coupled climate-carbon cycle model is *** simulations of the model realistically reproduced historical changes in carbon cycle *** the IAP RAS CM,climate warming reproduced in the 20th and 21st centuries enhanced terrestrial net primary production but terrestrial carbon uptake was suppressed due to an overcompensating increase in soil *** year 2100,the simulations the model forced by different land use scenarios diverged markedly,by about 70 Pg （C） in terms of biomass and soil carbon stock but they differed only by about 10 ppmv in terms of atmospheric carbon dioxide content.

关键词： terrestrial carbon cycle climate model anthropogenic scenarios uncertainty in projections

Ship Weather Routing Based on Hybrid Genetic Algorithm Under Complicated Sea Conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2023年第1期22卷 28-42页

作者： ZHOU Peng ZHOU Zheng WANG Yan WANG Hongbo State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityJilin 130012China

Considering the effects of increased economic globalization and global warming,developing methods for reducing shipping costs and greenhouse gas emissions in ocean transportation has become *** to its key role in modern navigation technology,ship weather routing is the research focus of several scholars in this *** study presents a hybrid genetic algorithm for the design of an optimal ship route for safe transoceanic navigation under complicated sea *** the basis of the basic genetic algorithm,simulated annealing algorithm is introduced to enhance its local search ability and avoid premature convergence,with the ship’s voyage time and fuel consumption as optimization ***,a mathematical model of ship weather routing is developed based on the grid system.A measure of fitness calibration is proposed,which can change the selection pressure of the algorithm as the population *** addition,a hybrid crossover operator is proposed to enhance the ability to find the optimal solution and accelerate the convergence speed of the ***,a multi-population technique is applied to improve the robustness of the algorithm using different evolutionary strategies.

关键词： genetic algorithm simulated annealing algorithm weather routing ship speed loss

Helix unwinding in ferroelectric liquid crystals induced by tilted electric field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第7期24卷 341-344页

作者： Nail G.Migranov Aleksey A.Kudreyko Bashkir State Pedagogical University Department of General and Theoretical Physics Ufa State Petroleum Technological University Department of Physics

Helix unwinding in ferroelectric liquid crystals induced by an electric field is theoretically studied on the basis of the continuum theory. By applying a weak electric field tilted to the smectic layers, the contribution of the dielectric interaction energy density to the total free energy density is increased. Approximation methods are used to calculate the free energy for different tilt angles between the electric field and the smectic layers. The obtained results suggest selecting the optimal number of pitches in the film that matches to the minimum of the free energy.

关键词： ferroelectric liquid crystals helicoidal structure thin films Euler's equation