• Structural Engineering and Mechanics
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• 제73권6호
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• pp.725-735
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• 2020

The present investigation deals with the thermomechanical interactions in an orthotropic thermoelastic homogeneous body in the context of fractional order theory of thermoelasticity due to time harmonic sources. The application of a time harmonic concentrated and distributed sources has been considered to show the utility of the solution obtained. Assuming the disturbances to be harmonically time dependent, the expressions for displacement components, stress components and temperature change are derived in frequency domain. Numerical inversion technique has been used to determine the results in physical domain. The effect of frequency on various components has been depicted through graphs.

• Coupled systems mechanics
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• 제9권5호
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• pp.397-410
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• 2020

The present investigation is concerned with two-dimensional deformation in a homogeneous isotropic non local thermoelastic solid with two temperatures due to thermomechanical sources. The theory of memory dependent derivatives has been used for the study. The bounding surface is subjected to concentrated and distributed sources (mechanical and thermal sources). The Laplace and Fourier transforms have been used for obtaining the solution to the problem in the transformed domain. The analytical expressions for displacement components, stress components and conductive temperature are obtained in the transformed domain. For obtaining the results in the physical domain, numerical inversion technique has been applied. Numerical simulated results have been depicted graphically for explaining the effects of nonlocal parameter on the components of displacements, stresses and conductive temperature. Some special cases have also been deduced from the present study. The results obtained in the investigation should be useful for new material designers, researchers and physicists working in the field of nonlocal material sciences.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.18-18
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• 2002

Although it was suggested in 1962 that an efficient wavelength conversion could be achieved using ferroelectric crystals of periodic 180° domains, it was not until 1990's that quasi-phase-matching (QPM) became realized, as technology for periodic poling of LiNbO₃ crystals was readily available. Since ferroelectric domain inversion brings about change of the sign of second-order nonlinear susceptibility, periodically poled ferroelectric structures provide an ideal way of achieving QPM for second-harmonic generation and optical parametric oscillation. Periodically poled ferroelectric domains can also be utilized for optical devices, such as Brags electrooptic modulators. fabrication of stable periodic domain structures depends on a number of poling parameters of a ferroelectric crystal, such as coercive field, internal field and electrical conductivity. We present poling kinetics of KNbO₃ crystals, which involve domain nucleation and growth, backswitching, relaxation of internal field. Optimum poling conditions were established by designing a proper wave shape of external field. We demonstrate an efficient second-harmonic generation using QPM in a periodically poled KNbO₃ crystal.

• Coupled systems mechanics
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• 제8권1호
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• pp.39-53
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• 2019

Here in this investigation, a two-dimensional thermoelastic problem of thick circular plate of finite thickness under fractional order theory of thermoelastic diffusion has been considered in frequency domain. The effect of frequency in the axisymmetric thick circular plate has been depicted. The upper and lower surfaces of the thick plate are traction free and subjected to an axisymmetric heat supply. The solution is found by using Hankel transform techniques. The analytical expressions of displacements, stresses and chemical potential, temperature change and mass concentration are computed in transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain. Numerically simulated results are depicted graphically. The effect frequency has been shown on the various components.

• Coupled systems mechanics
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• 제9권6호
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• pp.521-538
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• 2020

The present study is concerned with the thermoelastic interactions in a two dimensional homogeneous, transversely isotropic thermoelastic solid with new modified couple stress theory without energy dissipation and with two temperatures in frequency domain. The time harmonic sources and Hankel transform technique have been employed to find the general solution to the field equations.Concentrated normal force, normal force over the circular region, thermal point source and thermal source over the circular region have been taken to illustrate the application of the approach. The components of displacements, stress, couple stress and conductive temperature distribution are obtained in the transformed domain. The resulting quantities are obtained in the physical domain by using numerical inversion technique. Numerically simulated results are depicted graphically to show the effect of angular frequency on the resulted quantities.

• Advances in materials Research
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• 제11권1호
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• pp.23-39
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• 2022

This work deals with the two-dimensional deformation in a homogeneous isotropic nonlocal magneto-thermoelastic solid with two temperatures under the effects of inclined load at different inclinations. The mathematical model has been formulated by subjecting the bounding surface to a concentrated load. The Laplace and Fourier transform techniques have been used for obtaining the solution to the problem in transformed domain. The expressions for nonlocal thermal stresses, displacements and temperature are obtained in the physical domain using a numerical inversion technique. The effects of nonlocal parameter, rotation and inclined load in the physical domain are depicted and illustrated graphically. The results obtained in this paper can be useful for the people who are working in the field of nonlocal thermoelasticity, nonlocal material science, physicists and new material designers. It is found that there is a significant difference due to presence and absence of nonlocal parameter.

• Coupled systems mechanics
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• 제11권4호
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• pp.297-313
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• 2022

The objective of this paper is to study the effect of frequency in a two-dimensional orthotropic thermoelastic rotating solid with fractional order heat transfer in generalized thermoelasticity with two-temperature due to inclined load. As an application the bounding surface is subjected to uniformly and linearly distributed loads (mechanical and thermal source). The problem is solved with the help of Fourier transform. Assuming the disturbances to be harmonically time dependent, the expressions for displacement components, stress components, conductive temperature and temperature change are derived in frequency domain. Numerical inversion technique has been used to determine the results in physical domain. The results are depicted graphically to show the effect of frequency on various components. Some particular cases are also discussed in the present research.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.997-1002
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• 2001

This paper describes an implementation of inverse filter using SVD in order to recover the input in multi-channel system. The matrix formulation in SISO system is extended to MIMO system. In time and frequency domain we investigates the inversion of minimum phase system and non-minimum phase system. To execute an effective inversion of non-minimum phase system, SVD is introduced. First of all we computes singular values of system matrix and then investigates the phase property of system. In case of overall system is non-minimum phase, system matrix has one (or more) very small singular value(s). The very small singular value(s) carries information about phase properties of system. Using this property, approximate inverse filter of overall system is founded. The numerical simulation shows potentials in use of the inverse filter.

• 한국통신학회논문지
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• 제27권4C호
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• pp.316-325
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• 2002

This paper investigates the restoration schemes which are applied to the MPLS domain upon a network failure. We define the following three restoration service models by combining the various restoration schemes: "FIS-based protection service" (FIS: failure indication signal), "inversion traffic protection service" and "1+1 protection service". After a qualitative analysis of the performance in them, we have analyzed it on quantitative basis by the simulation. According to the simulation results, "1+1 protection service" guarantees the fastest and most lossless restoration service among them; however, it results in consuming considerable bandwidth and producing an amount of control traffic, which means poor network utilization. On the other hand, "FIS-based protection service" spends less bandwidth and generates less control traffic, which means better network utilization, but produces poor restoration service. "Inversion traffic protection service" provides the medium restoration service and utilization between "1+1 protection service" and "FIS-based protection service."

• 한국전자파학회논문지
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• 제11권6호
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• pp.939-945
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• 2000

손실 반공간 묻혀 원동형 산란체와 주면 매질의 특성을 반복 기법 최적화 역산란을 적용하여 구했다. 산란파는 경계요소법을 이용하여 계산하였으며 산란체의 크기, 위치 내부매질의 비유전율, 도전율, 주변 매질의 비유전율, 도전율 등의 파라미터는 측정 산란파로부터 유전 알고리즘과 Levenberg-Marquardt 알고리즘의 혼합 알고리즘을 이요하여 역으로 계산하였다. 산란타의 측정오차에 의한 illposedness는 파수 영역에서 자수함수적으로 감쇠하는 감쇠모드를 제거하여 안정하시켰다.