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Limsup Results and LiL for Partial sum Processes of a Gaussian Random Field

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Acta Mathematica sinica,English series 2008年第9期24卷 1497-1506页

作者： Yong-Kab choi Mikls CsRG Department of Mathematics and RiNs Gyeongsang National University Jinju 660-701 Republic of Korea school of Mathematics and statistics Carleton University 1125 Colonel By DriveOttawa K1S 5B6 Canada

Let {ξ j ; j ∈ ℤ+ d be a centered stationary Gaussian random field, where ℤ+ d is the d-dimensional lattice of all points in d-dimensional Euclidean space ℝd, having nonnegative integer coordinates. For each j = (j ... 详细信息

Let {ξsUB> j sUB>; j ∈ ℤsUB>+sUB>sUP> d sUP>be a centered stationary Gaussian random field, where ℤsUB>+sUB>sUP> d sUP>is the d-dimensional lattice of all points in d-dimensional Euclidean space ℝsUP>dsUP>, having nonnegative integer coordinates. For each j = (j sUB>1 sUB>, ..., jd) in ℤsUB>+sUB>sUP> d sUP>, we denote |j| = j sUB>1 sUB>... j sUB>d sUB>and for m, n ∈ ℤsUB>+sUB>sUP> d sUP>, define s(m, n] = ΣsUB> msUB>ζsUB> j sUB>, σsUP>2sUP>(|n−m|) = Es sUP>2 sUP>(m, n], s sUB>n sUB>= s(0, n] and s sUB>0 sUB>= 0. Assume that σ(|n|) can be extended to a continuous function σ(t) of t > 0, which is nondecreasing and regularly varying with exponent α at b ≥ 0 for some 0 some additional conditions, we study limsup results for increments of partial sum processes and prove as well the law of the iterated logarithm for such partial sum processes.

关键词： stationary Gaussian random field regularly varying function large deviation probability law of the iterated logarithm

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)

Path properties of l_p-valued Gaussian random fields

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science China Mathematics 2007年第10期50卷 1501-1520页

作者： Yong-Kab choi Miklós CsRGO Department of Mathematics Gyeongsang National UniversityJinju 660-701Korea school of Mathematics and statistics Carleton University1125 Colonel By DriveOttawaK1S 5B6Canada

General limit theorems are established for l^p-valued Gaussian random fields indexed by a multidimensional parameter,which contain both almost sure moduli of continuity and limits of large increments for the l^p-value... 详细信息

关键词： l^p-valued Gaussian random field modulus of continuity large deviation probability regularly varying function

On Rayleigh expansion for nonlinear long water waves

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Journal of Hydrodynamics 2019年第6期31卷 1115-1126页

作者： Wooyoung choi Department of Mathematical sciences New Jersey Institute of TechnologyNewarkNJ 07102-1982USA

We consider strongly nonlinear long waves on the surface of a homogeneous fluid *** modifying the formulation for the high-order spectral(HOs)method for waves in water of finite depth,we present a higher-order nonlinear system for the surface elevation and the velocity potential on the free surface to describe the two-dimensional evolution of large amplitude long *** is shown that the resulting system preserves the Hamiltonian structure of the Euler equations and can be transformed to the strongly nonlinear long-wave model for the depth-averaged *** to truncation of the linear dispersion relation for water waves,both the system for the surface velocity potential and that for the depth-averaged velocity are ill-posed when the order of approximation is odd and even,*** avoid this ill-posedness,fully dispersive models are also *** the same order approximation,the long-wave model is found more effective for numeral studies of large amplitude long waves than the finite-depth model.

关键词： Long surface gravity waves strongly nonlinear waves Hamiltonian system regularized model

infrared-harvesting colloidal quantum dot inks for efficient photovoltaics: impact of surface chemistry and device engineering

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Journal of Materials science & Technology 2023年第16期147卷 224-240页

作者： Younghoon Kim Min-Jae choi Jongmin choi Department of Chemistry Kookmin UniversitySeoul02707Republic of Korea Department of Chemical and Biochemical Engineering Dongguk UniversitySeoul04620Republic of Korea Department of Energy science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu42988Republic of Korea

Colloidal quantum dots(CQDs)are promising semiconducting materials,which can be used as a photoactive layer in various optoelectronic applications,because of their size-tunable bandgap energy,solution processability,and excellent optical and optoelectronic *** particular,these features have generated great interest in the development of CQD solar cells and led to a rapid increase in their power conversion *** improvements were enabled by many innovative approaches in terms of CQD’s surface chemistry and device architecture *** this review,a critical overview of the research progress in CQD solar cells is presented with a focus on the strategies adopted for achieving record efficiency in CQD solar *** strategies include the use of organic/inorganic surface ligands,pre-and post-treatment of CQDs,and solid-state/solution-phase ligand ***,we provide an understanding of the research history to inspire the rational design of next-generation CQD optoelectronic devices,such as solar cells,light-emitting diodes,and *** research on the development of infrared CQD solar cells as complementary platforms to other solar cell technologies is also critically discussed to provide another perspective on CQD technologies.

关键词： Quantum dot Lead sulfide Ligand exchange Colloidal ink infrared light solar cell

Mathematical modeling and simulations of stress mitigation by coating polycrystalline particles in lithium-ion batteries

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 947-962页

作者： N.iQBAL J.choi s.F.sHAH C.LEE s.LEE Department of Mechanical Roboticsand Energy EngineeringDongguk University-SeoulSeoul 04620Republic of Korea

A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more ***,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress *** paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.

关键词： lithium-ion battery(LiB) polycrystalline particle coating finite element simulation Ni-rich LiNixMnyCo_(z)O_(2)(x>0.8)(NMC)

influence of Ti^(4+) doping on hyperfine field parameters of Mg_(0.95)Mn_(0.05)Fe_(2-2x)Ti_(2x)O_4(0≤x≤0.7)

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Journal of Central south University 2010年第6期17卷 1139-1143页

作者： KUMAR s PRAKAsH R ALiMUDDiN choi H K KOO B H sONG J i CHUNG H JEONG H LEE C G school of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and BK21 Eco-Friendly Heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscopy measurements at room temperature. From the analysis of the Moessbauer spectra, it is observed that s-electron density, electric field gradient （EFG）, quadrupole coupling constant （QCC） and the net hyperfine magnetic fields acting on the Moessbauer nuclei-FeA^3＋ and FeB^3＋ change with the increase of Ti^4＋ doping in Mg0.95Mn0.05Fe2O4. The hyperfine magnetic field decreases with the increase of Ti^4＋ doping.

关键词： spinel ferrite Moessbauer spectroscopy hyperfine magnetic field isomer shift Ti^4+ doping

inclusive quasielastic neutrino-nucleus scattering with energy density functional nuclear models

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Chinese Physics C 2024年第8期48卷 153-158页

作者： K.s.Kim soonchul choi Hana Gil Chang Ho Hyun school of liberal arts and science korea aerospace universitygoyang 10540korea Center for exotic nuclear studies institute for basic sciencedaejeon 34126korea Center for extreme nuclear matters korea universityseoul 02841korea Department of physics education daegu universitygyeongsan 38453korea

in this study,we calculated the inclusive charged-current neutrino-nucleus scattering from ^(40)Ar in the quasielastic *** explore the effect of uncertainties stemming from the nuclear structure,we used the KiDs(Korea-iBs-Daegu-sKKU)nuclear energy density functional and skyrme force models,namely sLy4,ski3,and *** models were selected to have distinct behavior in terms of the density dependence of the symmetry energy and the effective mass of the *** the charged-current neutrino scattering,the single-and double-differential cross sections were calculated for various *** cross sections are reported as a function of the incident neutrino *** theoretical cross sections were compared with experimental data,and the roles of the effective mass and symmetry energy were investigated in terms of charged-current neutrino-nucleus scattering.

关键词： energy density functional neutrino-nucleus scattering symmetry energy effective mass of the nucleon

impedance spectroscopy study on Mn_(1+x)Fe_(2-2x)Ti_xO_4(0≤x≤0.5) ferrites

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Journal of Central south University 2010年第6期17卷 1133-1138页

作者： KUMAR s BATOO K M PRAKAsH R choi H K KOO B H sONG J i CHUNG H JEONG H LEE C G school of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea King Abdullah institute for Nanotechnology King Saud UniversityRiyadh 11451Saudi Arabia Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Precision & Mechanical Engineering and BK21 Eco-Friendly Heat & Cold Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The complex impedance spectroscopy and surface morphology of Mn1+xFe2-2xTixO4(0≤x≤0.5) system,prepared using a conventional solid state reaction technique,were *** impedance spectroscopy measurements were carried out at room temperature in the frequency range of 42-5 *** electrical processes in the samples were modeled in the form of an equivalent circuit made up of a combination of two parallel RC circuits attributed to grain and grain *** DC conductivity obtained by extrapolation of AC data using impedance spectroscopy and four-probe method increases at 10% doping of Ti *** energy-dispersive X-ray(EDX) pattern confirmed the homogeneous mixing of the Mn,Fe,Ti and O atoms in pure and doped ferrite samples.

关键词： spinel ferrite magnetic properties impedance spectroscopy Ti4+ ions doping