The Experts below are selected from a list of 9183 Experts worldwide ranked by ideXlab platform
Hakan F Oztop - One of the best experts on this subject based on the ideXlab platform.
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forced convection of ferrofluids in a vented cavity with a rotating cylinder
International Journal of Thermal Sciences, 2014Co-Authors: Fatih Selimefendigil, Hakan F OztopAbstract:Abstract In this study, numerical investigation of the forced convection of ferrofluid in a square cavity with ventilation ports in the presence of an adiabatic rotating cylinder is carried out. The governing equations are solved with a finite element based solver. The effects of Reynolds number (20 ≤ Re ≤ 400), angular rotational speed of the cylinder (−500 ≤ Ω ≤ 500), strength and location of the magnetic dipole (0 ≤ γ ≤ 250), (0.2 ≤ a ≤ 0.8, −0.8 ≤ b ≤ −0.2) on the flow and thermal fields are numerically studied. It is observed that the length and size of the recirculation zones can be condtrolled with magnetic dipole strength and angular rotational speed of the cylinder. When the magnetic dipole is closer to the bottom wall of the cavity, flow is accelerated towards the bottom wall with larger influence area. The increasing values of the angular rotational speed of the cylinder in the Clockwise Direction enhance the heat transfer.
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estimation of the mixed convection heat transfer of a rotating cylinder in a vented cavity subjected to nanofluid by using generalized neural networks
Numerical Heat Transfer Part A-applications, 2014Co-Authors: Fatih Selimefendigil, Hakan F OztopAbstract:In this study, numerical investigation of mixed convection in a square cavity with ventilation ports filled with nanofluids in the presence of an adiabatic rotating cylinder is conducted. The governing equations are solved with a commercial finite element code (COMSOL). The effects of Grashof number (Gr = 103 to Gr = 105), Reynolds number (Re = 50 to Re = 300), nanoparticle volume fraction (φ = 0 to φ = 0.05), and cylinder rotation angle (Ω = −5 to Ω = 5) on the flow and thermal fields are numerically studied for a range of different parameter sets. The generalized neural network (GRNN) is used to predict the thermal performance of the system. It is observed that the heat transfer increases almost linearly with increasing the nanoparticle volume fraction. The increasing rotation angle in the Clockwise Direction generally enhances the heat transfer. Moreover, the validation results with artificial neural networks show that generalized neural nets show better performance compared to radial basis and feed-fo...
Seiji Shinkai - One of the best experts on this subject based on the ideXlab platform.
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helical ribbon aggregate composed of a crown appended cholesterol derivative which acts as an amphiphilic gelator of organic solvents and as a template for chiral silica transcription
Journal of the American Chemical Society, 2001Co-Authors: Jong Hwa Jung, Hedeki Kobayashi, Mitsutoshi Masuda, Toshimi Shimizu, Seiji ShinkaiAbstract:New crown-appended cholesterol-based organogelator 1, which has two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton-binding site, and one crown moiety as a cation-binding site, was synthesized, and the gelation ability was evaluated in organic solvents. It can gelate acetic acid, acetonitrile, acetone, ethanol, 1-butanol, 1-hexanol, DMSO, and DMF under 1.0 wt %, indicating that 1 acts as a versatile gelator of various organic solvents. To characterize the aggregation mode in the organogel system, we observed a CD spectrum of the acetic acid gel 1. In the CD spectrum, the λθ=0 value appears at 353 nm, which is the same as the absorption maximum λmax = 353 nm. The positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient in a Clockwise Direction. Very surprisingly, the TEM images of the 1 + acetic acid gel resulted in the helical ribbon and the tubular structures. Sol−gel polymerization of tetraethoxys...
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helical ribbon aggregate composed of a crown appended cholesterol derivative which acts as an amphiphilic gelator of organic solvents and as a template for chiral silica transcription
Journal of the American Chemical Society, 2001Co-Authors: Jong Hwa Jung, Hedeki Kobayashi, Mitsutoshi Masuda, And Toshimi Shimizu, Seiji ShinkaiAbstract:New crown-appended cholesterol-based organogelator 1, which has two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton-binding site, and one crown moiety as a cation-binding site, was synthesized, and the gelation ability was evaluated in organic solvents. It can gelate acetic acid, acetonitrile, acetone, ethanol, 1-butanol, 1-hexanol, DMSO, and DMF under 1.0 wt %, indicating that 1 acts as a versatile gelator of various organic solvents. To characterize the aggregation mode in the organogel system, we observed a CD spectrum of the acetic acid gel 1. In the CD spectrum, the λθ=0 value appears at 353 nm, which is the same as the absorption maximum λmax = 353 nm. The positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient in a Clockwise Direction. Very surprisingly, the TEM images of the 1 + acetic acid gel resulted in the helical ribbon and the tubular structures. Sol−gel polymerization of tetraethoxys...
Fatih Selimefendigil - One of the best experts on this subject based on the ideXlab platform.
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forced convection of ferrofluids in a vented cavity with a rotating cylinder
International Journal of Thermal Sciences, 2014Co-Authors: Fatih Selimefendigil, Hakan F OztopAbstract:Abstract In this study, numerical investigation of the forced convection of ferrofluid in a square cavity with ventilation ports in the presence of an adiabatic rotating cylinder is carried out. The governing equations are solved with a finite element based solver. The effects of Reynolds number (20 ≤ Re ≤ 400), angular rotational speed of the cylinder (−500 ≤ Ω ≤ 500), strength and location of the magnetic dipole (0 ≤ γ ≤ 250), (0.2 ≤ a ≤ 0.8, −0.8 ≤ b ≤ −0.2) on the flow and thermal fields are numerically studied. It is observed that the length and size of the recirculation zones can be condtrolled with magnetic dipole strength and angular rotational speed of the cylinder. When the magnetic dipole is closer to the bottom wall of the cavity, flow is accelerated towards the bottom wall with larger influence area. The increasing values of the angular rotational speed of the cylinder in the Clockwise Direction enhance the heat transfer.
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estimation of the mixed convection heat transfer of a rotating cylinder in a vented cavity subjected to nanofluid by using generalized neural networks
Numerical Heat Transfer Part A-applications, 2014Co-Authors: Fatih Selimefendigil, Hakan F OztopAbstract:In this study, numerical investigation of mixed convection in a square cavity with ventilation ports filled with nanofluids in the presence of an adiabatic rotating cylinder is conducted. The governing equations are solved with a commercial finite element code (COMSOL). The effects of Grashof number (Gr = 103 to Gr = 105), Reynolds number (Re = 50 to Re = 300), nanoparticle volume fraction (φ = 0 to φ = 0.05), and cylinder rotation angle (Ω = −5 to Ω = 5) on the flow and thermal fields are numerically studied for a range of different parameter sets. The generalized neural network (GRNN) is used to predict the thermal performance of the system. It is observed that the heat transfer increases almost linearly with increasing the nanoparticle volume fraction. The increasing rotation angle in the Clockwise Direction generally enhances the heat transfer. Moreover, the validation results with artificial neural networks show that generalized neural nets show better performance compared to radial basis and feed-fo...
Jong Hwa Jung - One of the best experts on this subject based on the ideXlab platform.
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helical ribbon aggregate composed of a crown appended cholesterol derivative which acts as an amphiphilic gelator of organic solvents and as a template for chiral silica transcription
Journal of the American Chemical Society, 2001Co-Authors: Jong Hwa Jung, Hedeki Kobayashi, Mitsutoshi Masuda, Toshimi Shimizu, Seiji ShinkaiAbstract:New crown-appended cholesterol-based organogelator 1, which has two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton-binding site, and one crown moiety as a cation-binding site, was synthesized, and the gelation ability was evaluated in organic solvents. It can gelate acetic acid, acetonitrile, acetone, ethanol, 1-butanol, 1-hexanol, DMSO, and DMF under 1.0 wt %, indicating that 1 acts as a versatile gelator of various organic solvents. To characterize the aggregation mode in the organogel system, we observed a CD spectrum of the acetic acid gel 1. In the CD spectrum, the λθ=0 value appears at 353 nm, which is the same as the absorption maximum λmax = 353 nm. The positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient in a Clockwise Direction. Very surprisingly, the TEM images of the 1 + acetic acid gel resulted in the helical ribbon and the tubular structures. Sol−gel polymerization of tetraethoxys...
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helical ribbon aggregate composed of a crown appended cholesterol derivative which acts as an amphiphilic gelator of organic solvents and as a template for chiral silica transcription
Journal of the American Chemical Society, 2001Co-Authors: Jong Hwa Jung, Hedeki Kobayashi, Mitsutoshi Masuda, And Toshimi Shimizu, Seiji ShinkaiAbstract:New crown-appended cholesterol-based organogelator 1, which has two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton-binding site, and one crown moiety as a cation-binding site, was synthesized, and the gelation ability was evaluated in organic solvents. It can gelate acetic acid, acetonitrile, acetone, ethanol, 1-butanol, 1-hexanol, DMSO, and DMF under 1.0 wt %, indicating that 1 acts as a versatile gelator of various organic solvents. To characterize the aggregation mode in the organogel system, we observed a CD spectrum of the acetic acid gel 1. In the CD spectrum, the λθ=0 value appears at 353 nm, which is the same as the absorption maximum λmax = 353 nm. The positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient in a Clockwise Direction. Very surprisingly, the TEM images of the 1 + acetic acid gel resulted in the helical ribbon and the tubular structures. Sol−gel polymerization of tetraethoxys...
Hedeki Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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helical ribbon aggregate composed of a crown appended cholesterol derivative which acts as an amphiphilic gelator of organic solvents and as a template for chiral silica transcription
Journal of the American Chemical Society, 2001Co-Authors: Jong Hwa Jung, Hedeki Kobayashi, Mitsutoshi Masuda, Toshimi Shimizu, Seiji ShinkaiAbstract:New crown-appended cholesterol-based organogelator 1, which has two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton-binding site, and one crown moiety as a cation-binding site, was synthesized, and the gelation ability was evaluated in organic solvents. It can gelate acetic acid, acetonitrile, acetone, ethanol, 1-butanol, 1-hexanol, DMSO, and DMF under 1.0 wt %, indicating that 1 acts as a versatile gelator of various organic solvents. To characterize the aggregation mode in the organogel system, we observed a CD spectrum of the acetic acid gel 1. In the CD spectrum, the λθ=0 value appears at 353 nm, which is the same as the absorption maximum λmax = 353 nm. The positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient in a Clockwise Direction. Very surprisingly, the TEM images of the 1 + acetic acid gel resulted in the helical ribbon and the tubular structures. Sol−gel polymerization of tetraethoxys...
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helical ribbon aggregate composed of a crown appended cholesterol derivative which acts as an amphiphilic gelator of organic solvents and as a template for chiral silica transcription
Journal of the American Chemical Society, 2001Co-Authors: Jong Hwa Jung, Hedeki Kobayashi, Mitsutoshi Masuda, And Toshimi Shimizu, Seiji ShinkaiAbstract:New crown-appended cholesterol-based organogelator 1, which has two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton-binding site, and one crown moiety as a cation-binding site, was synthesized, and the gelation ability was evaluated in organic solvents. It can gelate acetic acid, acetonitrile, acetone, ethanol, 1-butanol, 1-hexanol, DMSO, and DMF under 1.0 wt %, indicating that 1 acts as a versatile gelator of various organic solvents. To characterize the aggregation mode in the organogel system, we observed a CD spectrum of the acetic acid gel 1. In the CD spectrum, the λθ=0 value appears at 353 nm, which is the same as the absorption maximum λmax = 353 nm. The positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient in a Clockwise Direction. Very surprisingly, the TEM images of the 1 + acetic acid gel resulted in the helical ribbon and the tubular structures. Sol−gel polymerization of tetraethoxys...