• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.39-47
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• 2003

Sufficient conditions for asymptotic behavior of the solutions of nonlinear forced neutral delay differential equations with impulses are found. The results given in [2,4,6,7］are generalized and improved.

• Nuclear Engineering and Technology
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• v.29 no.6
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• pp.459-467
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• 1997

The steady-state behavior of recycling neutral atoms in a tokamak edge region has been analyzed through a two-dimensional Monte Carlo simulation. A particle tracking algorithm used in earlier research on the neutral particle transport is applied to this Monte Carlo simulation in order to perform more accurate calculations with the EDGETRAN code which was previously developed for a two-dimensional edge plasma transport in the authors' laboratory. The physical model of neutral recycling includes charge-exchange and ionization interactions between plasmas and neutral atoms. The reflection processes of incident particles on the device wall are described by empirical formulas. Calculations for density, energy, and velocity distributions of neutral deuterium-tritium atoms have been carried out for a medium-sized tokamak with a double-null configuration based on the KT-2 conceptual design. The input plasma parameters such as plasma density, ion and electron temperatures, and ion fluid velocity are provided from the EDGETRAN calculations. As a result of the present numerical analysis, it is noticed that a significant drop of the neutral atom density appears in the region of high plasma density and that the similar distribution of neutral energy to that of plasma ions is present as frequently reported in other studies. Relations between edge plasma conditions and the neutral recycling behavior are discussed from the numerical results obtained herein.

• Journal of applied mathematics & informatics
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• v.8 no.1
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• pp.111-128
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• 2001

In this paper, we consider the oscillation of the second-order neutral difference equation Δ²(x/sub n/ - px/sub n-r/) + q/sub n/f(x/sub n/ - σ/sub n/) = 0 as well as the oscillatory behavior of the corresponding ordinary difference equation Δ²z/sub n/ + q/sub n/f(R(n,λ)z/sub n/) = 0

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.37-51
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• 2004

In this paper, we consider the asymptotic behavior of solutions of the forced nonlinear neutral difference equation $\Delta[x(n)-\sumpi(n)x(n-k_i)]+\sumqj(n)f(x(n-\iota_j))=r(n)$ with sign changing coefficients. Some sufficient conditions for every solution of (*) to tend to zero are established. The results extend and improve some known theorems in literature.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.6
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• pp.281-287
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• 2001

In order to obtain guidelines for design and operation of a new plasma source by a magnetic neutral loop discharge(NLD), the electron behavior was studied experimentally and numerically. Experimentally, the magnetic field gradient was changed over a wide range, and it was found that there existed an optimum value for efficient plasma production. Analyses of the electron behavior were performed using a model that included effects of a three dimensional electromagnetic field configuration considering the spatial decay of the electric field, and the limitation to the motion of electron caused by the existence of walls and thus electron loss at wall surfaces. These three dimensional factors were found to explain the existence of the optimum magnetic field gradient. It was shown that the L dependence of the plasma production efficiency was firstly decided by the finite decay length of the electric field strength, which was further modified by electron elastic collisions with neutral atoms which drove the electron to walls. The latter effect tends to reduce the optimum value of L.

• Bulletin of the Korean Mathematical Society
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• v.45 no.2
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• pp.299-312
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• 2008

In this paper, we establish some oscillation criteria for nonautonomous second order neutral delay dynamic equations $(x(t){\pm}r(t)x({\tau}(t)))^{{\Delta}{\Delta}}+H(t,\;x(h_1(t)),\;x^{\Delta}(h_2(t)))=0$ on a time scale ${\mathbb{T}}$. Oscillatory behavior of such equations is not studied before. This is a first paper concerning these equations. The results are not only can be applied on neutral differential equations when ${\mathbb{T}}={\mathbb{R}}$, neutral delay difference equations when ${\mathbb{T}}={\mathbb{N}}$ and for neutral delay q-difference equations when ${\mathbb{T}}=q^{\mathbb{N}}$ for q>1, but also improved most previous results. Finally, we give some examples to illustrate our main results. These examples arc [lot discussed before and there is no previous theorems determine the oscillatory behavior of such equations.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.107-112
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• 2001

Laser Thomson scattering measurements of electrom temperature and density in a neutral loop discharge (NLD) plasma were performed in order to reveal the electron behavior around the neutral loop (NL). The experimental results were examined by using a simulation model that included effects of a three dimensional electromagnetic field with spatial decay of the RF electric field, and the limitation of the spatial extent of the electron motion and collision effect. From the experiments and modeling of the electron behavior, it was found that NLD plasma posses the electron temeprature $T_{e}$ and density ne peaks around the NL is essential for the formation of plasma. Also, the optimum condition of plasma production could be simply estimated by the calculation of $U_{av}$ and $F_{0}$././.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2236-2241
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• 2009

In this study, the electron behavior was investigated numerically in order to obtain guidelines for design and operation of a new plasma source by a magnetic neutral loop discharge (NLD). The optimum plasma production was investigated by using a 3-dimensional simulation model which enables the electron behavior calculation from source region to downstream region. The results showed that the high-density plasma produced around the magnetic neutral loop (NL) is transferred from the NL region to the downstream region along magnetic force lines. Also the avaraged electron energy is increased with the normalized RF electric field (F), which can be used to characterize the plasma production efficiency of NLD system. Considering the relation between F and plasma production, in-depth plasma control can be achieved at a given specific process condition.

• Advances in aircraft and spacecraft science
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• v.11 no.2
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• pp.129-152
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• 2024

The applicability of a novel incremental-iterative technique with 2D differential/integral quadrature method (DIQM) in analyzing the nonlinear behavior of Bi-directional functionally graded (BDFG) porous plate based on neutral surface is verified in the present works. A formulation of four variables high shear deformation theory is used to describe the kinematic relations with respect to neutral surface rather than mid-plane. Bi-directional material distributions are presented by power functions through both thickness and axial directions. Porosities and voids are distributed by different cosine functions. The large deformations are included within the sense of nonlinear von Kármán strains. The integro-differential equilibrium equations with associated modified boundary conditions are solved numerically and iteratively by using 2D DIQM. Model validations and parametric analysis are depicted to present the influence of neutral axis, nonlinear strains, gradation indices, elastic foundations, and modified boundary conditions on the static deflection in addition to normal and shear stresses. The proposed model is effective in analyzing the static behavior of many real applications in nuclear reactors, marine and aerospace structures with large deformations.

• Earthquakes and Structures
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• v.10 no.2
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• pp.451-461
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• 2016

A new first-order shear deformation theory is developed for dynamic behavior of functionally graded beams. The equations governing the axial and transverse deformations of functionally graded plates are derived based on the present first-order shear deformation plate theory and the physical neutral surface concept. There is no stretching-bending coupling effect in the neutral surface based formulation, and consequently, the governing equations and boundary conditions of functionally graded beams based on neutral surface have the simple forms as those of isotropic plates. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.