• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.209-218
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• 2024

The present paper is focused on the study of the propagation of plane waves in thermoelastic media under a modified Green-Lindsay (MG-L) model having the influence of non-local and two temperature. The problem is formulated for the considered model in dimensionless form and is explained by using the reflection phenomenon. The plane wave solution of these equations indicates the existence of three waves namely Longitudinal waves (LD-Wave), Thermal waves (T-wave), and Shear waves (SV-wave) from a stress-free surface. The variation of amplitude ratios is computed analytically and depicted graphically against the angle of incidence to elaborate the impact of non-local, two temperature, and different theories of thermoelasticity. Some particular cases of interest are also deduced from the present investigation. The present study finds applications in a wide range of problems in engineering and sciences, control theory, vibration mechanics, and continuum mechanics.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.171-174
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• 2010

In the paper, a printed dual-dipole array antenna is presented. A 4-way planar SIW power divider is adopted for feeding the array antenna. The dual-dipole is adopted as radiation elements which greatly improves the impedance band. The measured bandwidth larger than 31 % for VSWR$\leq$1.5 operating near 14 GHz is achieved and in agreement with the simulated results. The radiation E-plane and H-plane radiation pattern is presented in the paper. The radiation gain is also presented in the paper.

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.113-124
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• 2018

In the present paper, we have considered a layered medium of two semi-infinite nonlocal elastic solids with intermediate transversely isotropic magnetothermoelastic solid. The intermediate slab is of uniform thickness with the effects of two temperature, rotation and Hall current and with and without energy dissipation. A plane longitudinal or transverse wave propagating through one of the nonlocal elastic solid half spaces, is made incident upon transversely isotropic slab and it results into various reflected and refracted waves. The amplitude ratios of various reflected and refracted waves are obtained by using appropriate boundary conditions. The effect of nonlocal parameter on the variation of various amplitude ratios with angle of incidence are depicted graphically. Some cases of interest are also deduced.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1512-1518
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• 2018

The problem of scalar wave scattering by a sphere on or near a planar substrate is analytically solved. The solution is a set of wave functions coming in the form of infinite series of spherical and plane waves. In air, the incident plane wave is either scattered by the sphere or reflected from the substrate. A part of these scattered or reflected waves propagate to the other object where it is reflected and scattered again. Such processes of scattering and reflection repeat in turn indefinitely to generate multiply scattered waves, which are represented in the corresponding terms in the infinite series. The term in the series can be arranged in a recognizable manner to explicitly reveal the involved process and the multiplicity of scattering.

• Structural Engineering and Mechanics
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• v.23 no.1
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• pp.63-74
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• 2006

In this paper, the scattering of harmonic elastic anti-plane shear waves by two collinear cracks in functionally graded materials is investigated by means of nonlocal theory. The traditional concepts of the non-local theory are extended to solve the fracture problem of functionally graded materials. To overcome the mathematical difficulties, a one-dimensional non-local kernel is used instead of a two-dimensional one for the anti-plane dynamic problem to obtain the stress field near the crack tips. To make the analysis tractable, it is assumed that the shear modulus and the material density vary exponentially with coordinate vertical to the crack. By use of the Fourier transform, the problem can be solved with the help of a pair of triple integral equations, in which the unknown variable is the displacement on the crack surfaces. To solve the triple integral equations, the displacement on the crack surfaces is expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularities are present at crack tips.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.108-114
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• 1998

This paper presents the design and fabrication of waveguide E-plane metal insert bandpass filter for milli-meter waves which is analyzed transmission characteristics by calculating the generalized scattering matrix using mode-matching method. The bandpass filter was fabricated to verify the proposed method by the WR-34 rectangular waveguide to operate in 30.085 ~ 30.885 GHz. The fabricated waveguide E-plane metal insert band- pass filter was established the fact that it is so adaptive for milli-meter waves due to the measured data closely consistent with the results of analysis using mode-matching method, that is, the maximum value of insertion loss is 0.8 dB and the return loss is below -15 dB.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.6
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• pp.766-772
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• 2003

The pseudospectral method for stability analysis was used to find the most influential disturbance mode for transition of plane channel flows and Blasius flow at their critical Reynolds numbers. A number of various oblique disturbance waves were investigated for their pseudospectra and resolvent norm contours in each flow, and an exhaustive search method was employed to find the disturbing waves to which the flows become most unstable. In plane Poiseuille flow an oblique disturbance with a wavelength of 3.59h (where h is the half channel width) at an angle $28.7^{\circ}$ was found to be the most influential for the flow transition to turbulence, and in plane Couette flow it is an oblique wave with a wavelength of 3.49h at an angle of $19.4^{\circ}$. But in Blasius flow it was found that the most influential mode is a normal wave with a wavelength of $3.44{\delta}_{999}$. These results imply that the most influential disturbance mode is closely related to the fundamental acoustic wave with a certain shear sheltering in the respective flow geometry.

• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.135-138
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• 2007

Using a Shack-Hartmann sensor and sub-wavelength sized pinhole point source, we develope an optical testing system that measures the wavefront error of high numerical aperture and small sized optical components. The subwavelength sized pinhole generates perfect spherical waves with large diffraction angle and this makes possible to test high numerical aperture optics. The Shack-Hartmann sensor reconstructs the wavefront and calculates the aberrations. We make a home-made reference plane wave source which generates nearly perfect plane waves and the calibration with this plane source gives the overall uncertainty of the optical testing system 0.010 $\lambda$ rms.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1321-1324
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• 2007

In this paper, the in-plane end vibration of a cylindrical shell has been analyzed. The theoretical result has showed that the strong in-plane vibration at the ends of the cylindrical shell can be generated by the evanescent wave field, which is excited along about half the length of the shell. This has been also observed from experimental result. The evanescent waves are generated due to mode conversion of elastic waves at the ends of the cylindrical shells. The results show that the strong in-plane end vibration can be generated in cylindrical shells.

• Coupled systems mechanics
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• v.9 no.5
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• pp.411-432
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• 2020

This research is devoted to the study of plane wave propagation in homogeneous transversely isotropic (HTI) magneto-thermoelastic rotating medium with combined effect of Hall current and two temperature due to multi-dual-phase lag heat transfer. It is analysed that, for 2-D assumed model, three types of coupled longitudinal waves (quasi-longitudinal, quasi-transverse and quasi-thermal) are present. The wave characteristics like phase velocity, specific loss, attenuation coefficients, energy ratios, penetration depths and amplitude ratios of transmitted and reflected waves are computed numerically and illustrated graphically and compared for different theories of thermoelasticity. Some particular cases are also derived from this research.