• Title, Summary, Keyword: shrinking sheet

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Numerical Study of Entropy Generation with Nonlinear Thermal Radiation on Magnetohydrodynamics non-Newtonian Nanofluid Through a Porous Shrinking Sheet

  • Bhatti, M.M.;Abbas, T.;Rashidi, M.M.
    • Journal of Magnetics
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    • v.21 no.3
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    • pp.468-475
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    • 2016
  • In this article, entropy generation on MHD Williamson nanofluid over a porous shrinking sheet has been analyzed. Nonlinear thermal radiation and chemical reaction effects are also taken into account with the help of energy and concentration equation. The fluid is electrically conducting by an external applied magnetic field while the induced magnetic field is assumed to be negligible due to small magnetic Reynolds number. The governing equations are first converted into the dimensionless expression with the help of similarity transformation variables. The solution of the highly nonlinear coupled ordinary differential equation has been obtained with the combination of Successive linearization method (SLM) and Chebyshev spectral collocation method. Influence of all the emerging parameters on entropy profile, temperature profile and concentration profile are plotted and discussed. Nusselt number and Sherwood number are also computed and analyzed. It is observed that entropy profile increases for all the physical parameters. Moreover, it is found that when the fluid depicts non-Newtonian (Williamson fluid) behavior then it causes reduction in the velocity of fluid, however, non-Newtonian behavior enhances the temperature and nanoparticle concentration profile.

Study on the Spinning Processes Combined with Shear and Shrinking Deformation (전단 및 교축변형이 조합된 복합스피닝 공정에 관한 연구)

  • 이항수;강정식
    • Transactions of Materials Processing
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    • v.8 no.5
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    • pp.507-519
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    • 1999
  • An approach using the energy method has veen proposed for the analysis of cone spinning having the complicated deformation modes mixed by shear and normal deformation. In the proposed method, the corresponding solution is found through optimization of the total energy dissipation with respect to the parameters assumed by the velocity field defined as the variation of the length in longitudinal direction. The sheet blank is divided into three layers to consider the bending effect and the energy dissipated by shear deformation is superposed to the energy consumption due to normal deformation related with the shrinking deformation is superposed to the energy consumption due to normal deformation related with the shrinking deformation of axi-symmetric sheet element for the evaluation of total deformation energy. In order to check the validity of the proposed method, the complex spinning for making the conical cup is analyzed and the computed results are compared with the experimental results. In comparison of the computed results with existing experimental results,, the good agreement is obtained for the variation of outer radius and the distribution of thickness, and it has thus been shown that the present approach is applicable to the analysis of complex spinning.

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Effects of Molding Condition on Surface Unevenness of GMT-Sheet Moldings (GMT-Sheet 성형품의 표면요철에 미치는 성형조건의 영향)

  • Kim, Hyoung-Seok;Kim, Jin-Woo;Kim, Yong-Jae;Lee, Dong-Gi
    • Composites Research
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    • v.23 no.5
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    • pp.30-38
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    • 2010
  • Observing of GMT-Sheet in molding conditions, we have investigated unexpected phenomenons of moldings surface. In microscope investigation, we observe that there exist deficiencies on the surface of GMT-Sheet moldings, such as the spherulite, fiber projection, crack, fiber exposure, micro-weldline, pinhole and winding. They are caused to arise unevenness and phenomenons influence polish on surface. Especially, the major cause of the unevenness, effected to surface roughness, is a shrinking of matrix in the process of holding pressure and cooling temperature. The higher holding pressure load in a molding process and the lower demolding temperature in an annealing experiment, the better GMT-Sheet moldings improved its appearance.

Characteristics of Gate Oxides with Cobalt Silicide Process (복합 코발트 실리사이드 공정에 따른 게이트 산화막의 특성변화)

  • Song, Oh-sung;Cheong, Seong-hwee;Yi, Sang-don;Lee, Ki-yung;Ryu, Ji-ho
    • Korean Journal of Materials Research
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    • v.13 no.11
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    • pp.711-716
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    • 2003
  • Gate length, height, and silicide thickness have all been shrinking linearly as device density has progressively increased over the years. We investigated the effect of the cobalt diffusion during the silicide formation process on the 60$\AA$-thick gate oxide lying underneath the Ti/Co and Co/Ti bilayers. We prepared four different cobalt silicides, which have similar sheet resistance, made from the film structure of Co/Ti(interlayer), and Ti(capping layer)/Co, and peformed the current-voltage, time-to-break down, and capacitance-voltage measurements. Our result revealed that the cobalt silicide process without the Ti capping layer allowed cobalt atoms to diffuse into the upper interface of gate oxides. We propose that 100$\AA$-thick titanium interlayer may lessen the diffusion of cobalt to gate oxides in 1500-$\AA$ height polysilicon gates.