• Honam Mathematical Journal
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• v.38 no.3
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• pp.435-454
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• 2016

This paper investigates the effect of dual-phase-lags on a thermoviscoelastic orthotropic solid with a cylindrical cavity. The cylindrical cavity is subjected to a thermal shock varying heat and its material is taken to be of Kelvin-Voigt type. The phase-lag thermoelastic model, Lord and Shulman's model and the coupled thermoelasticity model are employed to study the thermomechanical coupling, thermal and mechanical relaxation (viscous) effects. Numerical solutions for temperature, displacement and thermal stresses are obtained by using the method of Laplace transforms. Numerical results are plotted to illustrate the effect phase-lags, viscoelasticity, and the variability thermal conductivity parameter on the studied fields. The variations of all field quantities in the context of dual-phase-lags and coupled thermoelasticity models follow similar trends while the Lord and Shulman's model may be different. The influence of viscosity parameter and variability of thermal conductivity is very pronounced on temperature and thermal stresses of the thermoviscoelastic solids.

• Advances in materials Research
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• v.12 no.3
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• pp.211-226
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• 2023

The present work is considered to study the two-dimensional problem in an orthotropic magneto-thermoelastic media and examined the effect of thermal phase-lags and GN-theories on Rayleigh waves in the light of fractional order theory with combined effect of rotation and hall current. The boundary conditions are used to derive the secular equations of Rayleigh waves. The wave properties such as phase velocity, attenuation coefficient are computed numerically. The numerical simulated results are presented graphically to show the effect of phase-lags and GN-theories on the Rayleigh wave phase velocity, attenuation coefficient, stress components and temperature change. Some particular cases are also discussed in the present investigation.

• Earthquakes and Structures
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• v.13 no.2
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• pp.201-209
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• 2017

This work aims to analyze the thermo-viscoelastic interaction in an orthotropic solid cylinder. The medium is considered to be variable thermal conductivity and subjected to temperature pulse. Analytical solution based on dual-phase-lags model with Voigt-type for behavior of viscoelastic material has been effectively proposed. All variables are deduced using method of Laplace transforms. Numerical results for different distribution fields, such as temperature, displacement and stress components are graphically presented. Results are discussed to illustrate the effect of variability thermal conductivity parameter as well as phase-lags and viscoelasticity on the field quantities. Results are obtained when the viscosity is ignored with and without considering variability of thermal conductivity. A comparison study is made and all results are investigated.

• Wind and Structures
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• v.35 no.6
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• pp.395-403
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• 2022

The present research is concerned with the study of Stoneley wave propagation at the interface of two dissimilar homogeneous orthotropic magneto-thermoelastic solids with fractional order theory of type GN-III with three phase-lags and combined effect of hall current and rotation. With the help of appropriate boundary conditions the secular equations of Stoneley waves are obtained in the form of determinant. The characteristics of wave such as phase velocity, attenuation coefficient and specific loss are computed numerically. The effect of rotation on the Stoneley wave's phase velocity, attenuation coefficient, specific loss, displacement components, stress components and temperature change has been depicted graphically. Some particular cases are also derived in this problem.

• Steel and Composite Structures
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• v.42 no.6
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• pp.723-732
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• 2022

The present research is concerned to study the effect of fractional parameter and rotation on the propagation of Rayleigh waves in an orthotropic magneto-thermoelastic media with three-phase-lags in the context of fractional order theory of generalized thermoelasticity with combined effect of rotation and hall current. The secular equations of Rayleigh waves are derived by using the appropriate boundary conditions. The wave properties such as phase velocity, attenuation coefficient are computed numerically and the numerical simulated results are presented through graphs to show the effect on all the components. Some special cases are also discussed in the present investigation.

• Earthquakes and Structures
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• v.10 no.3
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• pp.681-697
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• 2016

The model of two-temperature magneto-thermoelasticity for a non-simple variable-thermal-conductivity infinitely-long solid cylinder is established. The present cylinder is made of an isotropic homogeneous thermoelastic material and its bounding plane is traction-free and subjected to a time-dependent temperature. An exact solution is firstly obtained in Laplace transform space to obtain the displacement, incremental temperature, and thermal stresses. The inversion of Laplace transforms has been carried out numerically since the response is of more interest in the transient state. A detailed analysis of the effects of phase-lags, an angular frequency of thermal vibration and the variability of thermal conductivity parameter on the field quantities is presented.

• Composite Materials and Engineering
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• v.3 no.3
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• pp.241-262
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• 2021

In this article, we studied the effect of two-temperature in a two-dimensional orthotropic thermoelastic media with fractional order heat transfer in generalized thermoelasticity with three-phase-lags due to thermomechanical sources. The boundary of the surface is subjected to linearly distributed and concentrated loads (mechanical and thermal source). The solution of the problem is obtained with the help of Laplace and Fourier transform techniques. The expressions for displacement components, stress components and conductive temperature are derived in transformed domain. Numerical inversion technique is used to obtain the results in physical domain. The effect of two-temperature on all the physical quantities has been depicted with the help graphs. Some special cases are also discussed in the present investigation.

• Structural Engineering and Mechanics
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• v.87 no.5
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• pp.475-485
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• 2023

The present study deals with wave propagation in a modified couple-stress generalized thermoelastic solid under the effect of gravity and magnetic field. The problem is solved by a refined microtemperatures multi-phase-lags thermoelastic theory. The Fourier series and Laplace transforms will be used to obtain the general solution for any set of boundary conditions. Some comparisons have been shown in figures to estimate the effects of the gravity field, the magnetic field, and different theories of thermoelasticity in the presence of the hall current effect on all the physical quantities. Some particular cases of special interest have been deduced from the present investigation.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.641-648
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• 1997

Mutual information is useful for analyzing nonlinear dependence in time series in much the same way as correlation is used to characterize linear dependence. We use multivariate kernel density estimators for the estimation of mutual information at different time lags for single and multiple time series. This approach is tested on a variety of hydrologic data sets, and suggested an appropriate delay time $ au$ at which the mutual information is almost zerothen multi-dimensional phase portraits could be constructed from measurements of a single scalar time series.

• Ocean and Polar Research
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• v.33 no.3
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• pp.309-319
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• 2011

This is a preliminary study of the feasibility of obtaining reliable tidal current harmonic constants, using one month of current observations, to verify the accuracy of a tidal model. An inference method is commonly used to separate out the tidal harmonic constituents when the available data spans less than a synodic period. In contrast to tidal constituents, studies of the separation of tidal-current harmonics are rare, basically due to a dearth of the long-term observation data needed for such experiments. We conducted concurrent and monthly harmonic analyses for tidal current velocities and heights, using 2 years (2006 and 2007) of current and sea-level records obtained from the Tidal Current Signal Station located in the narrow waterway in front of Incheon Lock, Korea. Firstly, the l-year harmonic analyses showed that, with the exception of $M_2$ and $S_2$ semidiurnal constituents, the major constituents were different for the tidal currents and heights. $K_1$, for instance, was found to be the 4th major tidal constituent but not an important tidal current constituent. Secondly, we examined monthly variation in the amplitudes and phase-lags of the $S_2$ and $K_1$ current-velocity and tide constituents over a 23-month period. The resultant patterns of variation in the amplitudes and phase-lags of the $S_2$ tidal currents and tides were similar, exhibiting a sine curve form with a 6-month period. Similarly, variation in the $K_1$ tidal constant and tidal current-velocity phase lags showed a sine curve pattern with a 6-month period. However, that of the $K_1$ tidal current-velocity amplitude showed a somewhat irregular sine curve pattern. Lastly, we investigated and tested the inference methods available for separating the $K_2$ and $S_2$ current-velocity constituents via monthly harmonic analysis. We compared the effects of reduction in monthly variability in tidal harmonic constants of the $S_2$ current-velocity constituent using three different inference methods and that of Schureman (1976). Specifically, to separate out the two constituents ($S_2$ and $K_2$), we used three different inference parameter (i.e. amplitude ratio and phase-lag diggerence) values derived from the 1-year harmonic analyses of current-velocities and tidal heights at (near) the short-term observation station and from tidal potential (TP), together with Schureman's (1976) inference (SI). Results from these four different methods reveal that TP and SI are satisfactorily applicable where results of long-term harmonic analysis are not available. We also discussed how to further reduce the monthly variability in $S_2$ tidal current-velocity constants.