• Title/Summary/Keyword: nonlinear medium

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Vibration and instability of nanocomposite pipes conveying fluid mixed by nanoparticles resting on viscoelastic foundation

  • Natanzi, Abolfazl Jafari;Jafari, Gholamreza Soleimani;Kolahchi, Reza
    • Computers and Concrete
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    • v.21 no.5
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    • pp.569-582
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    • 2018
  • In this study, nonlinear vibration and stability of a polymeric pipe reinforced by single-walled carbon naotubes (SWCNTs) conveying fluid-nanoparticles mixture flow is investigated. The Characteristics of the equivalent composite are determined using Mori-Tanaka model considering agglomeration effects. The surrounding elastic medium is simulated by orthotropic visco-Pasternak medium. Employing nonlinear strains-displacements, stress-strain energy method the governing equations were derived using Hamilton's principal. Differential quadrature method (DQM) is used for obtaining the frequency and critical fluid velocity. The influence of volume percent of SWCNTs, agglomeration, geometrical parameters of pipe, viscoelastic foundation and fluid velocity are shown on the frequency and critical fluid velocity of pipe. Results showed the increasing volume percent of SWCNTs leads to higher frequency and critical fluid velocity.

Fractional order thermoelastic wave assessment in a two-dimension medium with voids

  • Hobiny, Aatef D.;Abbas, Ibrahim A.
    • Geomechanics and Engineering
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    • v.21 no.1
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    • pp.85-93
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    • 2020
  • In this article, the generalized thermoelastic theory with fractional derivative is presented to estimate the variation of temperature, the components of stress, the components of displacement and the changes in volume fraction field in two-dimensional porous media. Easily, the exact solutions in the Laplace domain are obtained. By using Laplace and Fourier transformations with the eigenvalues method, the physical quantities are obtained analytically. The numerical results for all the physical quantities considered are implemented and presented graphically. The results display that the present model with the fractional derivative is reduced to the Lord and Shulman (LS) and the classical dynamical coupled (CT) theories when the fractional parameter is equivalent to one and the delay time is equal to zero and respectively.

A study on thermo-elastic interactions in 2D porous media with-without energy dissipation

  • Alzahrani, Faris;Abbas, Ibrahim A.
    • Steel and Composite Structures
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    • v.38 no.5
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    • pp.523-531
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    • 2021
  • The generalized thermoelastic analysis problem of a two-dimension porous medium with and without energy dissipation are obtained in the context of Green-Naghdi's (GNIII) model. The exact solutions are presented to obtain the studying fields due to the pulse heat flux that decay exponentially in the surface of porous media. By using Laplace and Fourier transform with the eigenvalues scheme, the physical quantities are analytically presented. The surface is shocked by thermal (pulse heat flux problems) and applying the traction free on its outer surfaces (mechanical boundary) through transport (diffusion) process of temperature to observe the analytical complete expression of the main physical fields. The change in volume fraction field, the variations of the displacement components, temperature and the components of stress are graphically presented. Suitable discussion and conclusions are presented.

Impact in bioconvection MHD Casson nanofluid flow across Darcy-Forchheimer Medium due to nonlinear stretching surface

  • Sharif, Humaira;Hussain, Muzamal;Khadimallah, Mohamed A.;Naeem, Muhammad Nawaz;Ayed, Hamdi;Tounsi, Abdelouahed
    • Smart Structures and Systems
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    • v.28 no.6
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    • pp.791-798
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    • 2021
  • Current investigation aims to analyze the characteristics of magnetohydrodynamic boundary layer flow of bioconvection Casson fluid in the presence of nano-size particles over a permeable and non-linear stretchable surface. Fluid passes through the Darcy-Forchheimer permeable medium. Effect of different parameter such as Darcy-Forchheimer, porosity parameter, magnetic parameter and Brownian factor are investigated. Increasing Brownian factor leads to the rapid random movement of nanosize particles in fluid flows which shows an expansion in thermal boundary layer and enhances the nanofluid temperature more rapidly. For large values of Darcy-Forchheimer, magnetic parameter and porosity factor the velocity profile decreases. Higher values of velocity slip parameter cause decreasing trend in momentum layer with velocity profile.

Analysis of photothermal response in a two-dimensional semiconducting material thermally excited by pulse heat flux

  • Saeed, Tareq;Abbas, Ibrahim
    • Structural Engineering and Mechanics
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    • v.82 no.4
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    • pp.469-476
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    • 2022
  • A mathematical model of Lord-Shulman photo-thermal theorem induced by pulse heat flux is presented to study the propagations waves for plasma, thermal and elastic in two-dimensional semiconductor materials. The medium is assumed initially quiescent. By using Laplace-Fourier transforms with the eigenvalue method, the variables are obtained analytically. A semiconductor medium such as silicon is investigated. The displacements, stresses, the carrier density and temperature distributions are calculated numerically and clarified graphically. The outcomes show that thermal relaxation time has varying degrees of effects on the studying fields.

Pump Light Power of Wideband Optical Phase Conjugator using HNL-DSF in WDM Systems with MSSI (MSSI 기법을 채택한 WDM 시스템에서 HNL-DSF를 이용한 광대역 광 위상 공액기의 펌프 광 전력)

  • Lee Seong real;Cho Sung eun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.3A
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    • pp.168-177
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    • 2005
  • In this paper, we numerically investigated the optimum pump light power resulting best compensation of pulse distortion due to both chromatic dispersion and self phase modulation (SPM) in long-haul 3×40 Gbps wavelength division multiplexing (WDM) systems. We used mid-span spectral inversion (MSSI) method with path-averaged intensity approximation (PAIA) as compensation approach, which have highly nonlinear dispersion shifted fiber (HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that HNL-DSF is an useful nonlinear medium in OPC for wideband WDM transmission, and in order to achieve the excellent compensation the pump light power is selected to equal the conjugated light power into the latter half fiber section with the input light power of WDM channel depending on total transmission length. Also we confirmed that compensation degree of WDM channel with small conversion efficiency is improved by using pump light power increasing power conversion ratio upper than 1.

Characteristics of Compensation for WDM Transmission with Equally Spaced Channels using Mid-Span Spectral Inversion (채널 간격이 일정한 WDM 전송에서의 Mid-Span Spectral Inversion을 이용한 보상 특성)

  • 이성렬;임황빈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.6
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    • pp.619-626
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    • 2004
  • In this paper, we investigated the compensation characteristics of distorted 16-channel WDM signal due to chromatic dispersion self phase modulation(SPM) and four-wave mixing(FWM). The bit rate and uniform frequency spacing of WDM channels are assumed to be 40 Gbps and 100 ㎓, respectively. The compensation method used in this approach is mid- span spectral inversion(MSSI), Highly-nonlinear dispersion shifted fiber(HNL-DSF) is used as a nonlinear medium of optical phase conjugator(On) in order to widely compensate WDM signal band. We confirmed that applying MSSI in WDM channels within special input power level compensates overall interferenced channels mainly due to FWM. But for long wavelength WDM channels having lower conjugated light power with respect to signal light power, compensation quality is deteriorated as dispersion coefficient of fiber becomes higher. Consequently, we confirmed that it is effective D apply MSSI with HNL-DSF as a nonlinear medium of OPC to WDM transmission link with relative small dispersion in order to compensate equally spaced WDM channels.

Wideband Optical Phase Conjugator using HNL-DSF in WDM Systems with Path-Averaged Intensity Approximation Mid-Span Spectral Inversion (경로 평균 강도 근사 기법의 MSSI를 채택한 WDM 시스템에서 HNL-DSF를 갖는 광대역 광 위상 공액기)

  • Lee, Seong-Real;Lee, Yun-Hyun
    • Journal of Advanced Navigation Technology
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    • v.7 no.1
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    • pp.14-21
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    • 2003
  • We investigated the optimum pump light power compensating distorted WDM signal due to both chromatic dispersion and self phase modulation (SPM). The considered system is $3{\times}40$ Gbps intensity modulation direct detection (IM/DD) WDM transmission system with path-averaged intensity approximation (PAIA) mid-span spectral inversion (MSSI) as compensation method. This system have highly nonlinear dispersion shifted fiber (HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that HNL-DSF is an useful nonlinear medium in OPC for wideband WDM transmission, and the excellent compensation is obtained when the pump light power of HNL-DSF OPC was selected to equalize the conjugated light power into the second half fiber section with the input WDM signal light power depending on total transmission length. By this approach, it is verified the possibility to realize a long-haul high capacities WDM system by using PAIA MSSI compensation method, which have HNL-DSF OPC with optimal pump light power depending on transmission length.

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Design and Fabrication of the Frequency Tripper for Medium Power (중전력 주파수 3체배기 설계 및 제작)

  • Roh, Hee-Jung;Lee, Byung-Sun
    • 전자공학회논문지 IE
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    • v.47 no.3
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    • pp.47-52
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    • 2010
  • In this paper, a frequency tripler has been designed with 100mW medium-power using P-HEMT. It is designed to obtain 7.2GHz frequency at the output that is an integer multiple of 2.4GHz input frequency by using nonlinear device that produces 3rd harmonic. The frequency tripler is designed by using load-pull simulation. To suppress the 2nd and fundamental, notch filter is used for the frequency tripler. The tripler is designed to obtain about 21dBm output power with 15dBm input, i.e., 6dB conversion gain and the suppression of 20dBc at fundamental, and 30dBc at the second harmonics.