• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.4
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• pp.309-332
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• 2016

Finite element method has been applied to solve the fundamental governing equations of natural convective, electrically conducting, incompressible fluid flow past an infinite vertical plate surrounded by porous medium in presence of thermal radiation, viscous dissipation, Soret and Dufour effects. In this research work, the results of coupled partial differential equations are found numerically by applying finite element technique. The sway of significant parameters such as Soret number, Dufour number, Grashof number for heat and mass transfer, Magnetic field parameter, Thermal radiation parameter, Permeability parameter on velocity, temperature and concentration evaluations in the boundary layer region are examined in detail and the results are shown in graphically. Furthermore, the effect of these parameters on local skin friction coefficient, local Nusselt number and Sherwood numbers is also investigated. A very good agreement is noticed between the present results and previous published works in some limiting cases.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.685-688
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• 1997

In this paper, we introduce a new adaptive controller for induction motor based on singular perturbation theory. The design of 5th induction motor was changed for the 3rd modeling using the singular perturbation method. The resulting boundary layer and quasi-steady-state systems are made exponentially stable. Therefore the statements of Tychonov's theorm are valid for an infinite time interval for induction motor, too.

• Steel and Composite Structures
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• v.27 no.4
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• pp.439-451
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• 2018

In the present investigation, a plane P (longitudinal) wave is made incident upon a transversely isotropic magnetothermoelastic solid slab of uniform thickness, interposed between two different semi-infinite viscoelastic solids. The transversely isotropic magnetothermoelastic sandwiched layer is homogeneous with combined effects of two temperature, rotation and Hall current in the context of GN Type-II and Type-III (1993) theory of thermoelasticity. The amplitude ratios of various reflected and refracted waves are obtained by using appropriate boundary conditions. The effect of energy dissipation on various amplitude ratios of longitudinal wave with angle of incidence are depicted graphically. Some cases of interest are also deduced from the present investigation.

• International Journal of Advanced Culture Technology
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• v.7 no.4
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• pp.268-273
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• 2019

The apparent soil resistivity is used for estimating multilayer soil parameters, such as, layer's depth and soil resistivity. The soil parameters are estimated by continuously revising those parameters until the error between the measured and calculated apparent soil resistivity reaches to allowable level. The equation for calculating the apparent soil resistivity is complicated and time consumed, because it is composed of an infinite integral which includes a zero order Bessel's function of the first kind. In this paper, a fast algorithm for calculating the apparent soil resistivity of horizontal multilayer earth structure is proposed using exponential sampling method.

• Structural Engineering and Mechanics
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• v.84 no.1
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• pp.35-48
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• 2022

This paper investigates the artificial neural network (ANN) to predict the dimensionless parameters for contact pressures and contact lengths under the rigid punch, the initial separation loads, and the initial separation distances of a contact problem. The problem consisted of two elastic infinitely layers (EL) loaded by means of a rigid cylindrical punch and resting on a half-infinite plane (HP). Firstly, the problem was formulated and solved theoretically using the Theory of Elasticity (ET). Secondly, the contact problem was extended based on the ANN. External load, the radius of punch, layer heights, and material properties were created by giving examples of different values used at the training and test stages of ANN. Finally, the accuracy of the trained neural networks for the case was tested using 134 new data, generated via ET solutions to determine the best network model. ANN results were compared with ET results, and well agreements were achieved.

• KCI Concrete Journal
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• v.13 no.2
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• pp.10-18
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• 2001

The spectral analysis of surface waves (SASW) method, which is an in-situ seismic technique, has mainly been developed and used for many years to determine the stiffness profile of layered media (such as asphalt concrete and layered soils) in an infinite half-space. This paper presents a modified experimental technique for nondestructive evaluation of in-place cement mortar compressive strength in single-layer concrete slabs of rather a finite thickness through a correlation to surface wave velocity. This correlation can be used in the quality control of early age cement mortar structures and in evaluating the integrity of structural members where the infinite half space condition is not met. In the proposed SASW field test, the surface of the structural members is subjected to an impact, using a 12 mm steel ball, to generate surface wave energy at various frequencies. Two accelerometer receivers detect the energy transmitted through the medium. By digitizing the analog receiver outputs, and recording the signals for spectral analysis, surface wave velocities can be identified. Modifications to the SASW method includes the reduction of boundary reflections as adopted on the surface waves before the point where the reflected compression waves reach the receivers. In this study, the correlation between the surface wave velocity and the compressive strength of cement mortar is developed using one 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slab of 2,000 psi (140 kgf/$\textrm{cm}^2$) and two 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slabs of 3,000 psi (210 kgf/$\textrm{cm}^2$).

• Tunnel and Underground Space
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• v.12 no.3
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• pp.171-178
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• 2002

A dynamic analysis of a horseshoe_shaped tunnel near to cavity was performed to study the effect of the cavity on the dynamic behavior of the tunnel. In order to obtain the dynamic response of the tunnel embedded in a semi-infinite domain, a hybrid numerical technique was primarily developed. A dynamic fundamental solution in frequency domain for multi-layered half planes was derived and subsequently incorporated in the boundary element method. Coupling of the boundary element method for the far field with the finite element method for the near field is made by imposing compatibility condition of a displacement at the interface. The boundary element method is then coupled with the finite element method, which is utilized to model the near field including the tunnel and the cavity. In order to demonstrate the validity of the proposed technique, dynamic responses of single and multiply-layered semi-infinite structural systems are obtained by using the Kicker waveform and investigated in the limestone layer to find how the being and the location of the cavity affect the dynamic characteristics of the system.

• Structural Engineering and Mechanics
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• v.41 no.6
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• pp.711-734
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• 2012

The foundation of a tall building frame resting on settable soil mass undergoes differential settlements which alter the forces in the structural members significantly. For tall buildings it is essential to consider seismic forces in analysis. The building frame, foundation and soil mass are considered to act as single integral compatible structural unit. The stress-strain characteristics of the supporting soil play a vital role in the interaction analysis. The resulting differential settlements of the soil mass are responsible for the redistribution of forces in the superstructure. In the present work, the nonlinear interaction analysis of a two-bay ten-storey plane building frame- layered soil system under seismic loading has been carried out using the coupled finite-infinite elements. The frame has been considered to act in linear elastic manner while the soil mass to act as nonlinear elastic manner. The subsoil in reality exists in layered formation and consists of various soil layers having different properties. Each individual soil layer in reality can be considered to behave in nonlinear manner. The nonlinear layered system as a whole will undergo differential settlements. Thus, it becomes essential to study the structural behaviour of a structure resting on such nonlinear composite layered soil system. The nonlinear constitutive hyperbolic soil model available in the literature is adopted to model the nonlinear behaviour of the soil mass. The structural behaviour of the interaction system is investigated as the shear forces and bending moments in superstructure get significantly altered due to differential settlements of the soil mass.

• Journal of Radiation Protection and Research
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• v.1 no.1
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• pp.22-30
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• 1976

The perturbation of dose distribution adjacent to cavities in high energy electron has shown that the percentage of dose increase varies markedly as a function of the build-up layer, the length and thickness of the cavities, and the electron energy. The dose distribution showed that cavities similar in size to those encountered in the head and neck measured by industrial film dosimetry and corrected by ionization chambers. The most increased doses by measuring are resulted in a localized dose of up to 130% of that measured at the depth of maximum dose within a homogeneous tissue equivalent phantom. The measured values and correction factors of dose perturbation due to air cavities showed in diagrams and would be summarized as follows. 1. In $8{\sim}12MeV$ electron beams, the most marked dose is observed when the build-up layer thickness is 0.5cm and cavity volume is $2{\times}2{\times}2cm^3$. 2. The highest dose point is located under cavity when the energy is increased and cavity length is longer. 3. The cavity length at which the maximum percentage dose occurs decreases with increasing energy. 4. The highest percentage cavity doses are obtained when the energy is high, the build-up layer is thin, the thickness of the cavity is large, and the length of the cavity is approximately 1 to 3cm. 5. The doses of upper portion of cavity are less than the standard dose distribution as 5 to 10%. 6. The maximum range of electron beam are extended as much as thickness of cavity. 7. A cavity having a length of 5cm closely approximates a cavity of infinite length.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1821-1828
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• 2010

Laser shock peening(LSP) is an innovative surface treatment technique, and it has been successfully used to improve the fatigue performance of metallic components. It is widely known, that cracks caused by metal fatigue occur only at the location where the metal is subject to tension, and not at the location where the metal is subjected to compression. Therefore, LSP can be employed to improve fatigue life because it generates a high-magnitude compressive residual stress on the surface and interior of metallic components. In this study, we analyzed the applicability of the LSP method in improving fatigue performance and evaluated the various parameters that influence the compressive residual stress. Further, we analyzed the change in the mechanical properties such as surface dynamic stress and the compressive residual stress on the surface and interior of metallic components.