University College London

London, Greater London, United Kingdom

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Institute of Child Health
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Institute of Neurology
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Department of Computer Science
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Publication History View all

  • [Show abstract] [Hide abstract]
    ABSTRACT: The use of recycled rubber as a possible aggregate in concrete is known to result in a reduction of compressive and flexural strength. This paper summarises the results of initial studies on the effect of surface-treating rubber crumb (obtained from discarded tires) with ultraviolet (UV) radiation, with the aim of mitigating such losses. Investigation focussed on changing the surface energy, and therefore the bond strength, between cement and rubber. To identify the most effective UV wavelength for this purpose, a water retention test method was utilized, resulting in the selection of the UV-C wavelength range for treatment. Additionally, specimens containing rubber, treated for different time periods, were subjected to flexural testing. As expected, the addition of untreated crumb rubber resulted in a degradation of flexural strength, however exposure to UV-C generated, at best, values only 6% weaker than those of rubberless specimens, indicating the benefits of the investigated surface treatment.
    Cement and Concrete Composites 09/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Dy2O3–Y2O3 co-doped ZrO2 would potentially exhibit lower thermal conductivity and higher coefficient of thermal expansion, which is a promising ceramic thermal barrier coating material for aero-gas turbines and high temperature applications in metallurgical and chemical industry. In this study, Dy2O3–Y2O3 co-doped ZrO2 ceramics were prepared using solid state reaction methods. Dy0.5Zr0.5O1.75 and Dy0.25Y0.25Zr0.5O1.75 consist of pure cubic fluorite phase, whereas both Dy0.06Y0.072Zr0.868O1.934 and Dy0.02Y0.075Zr0.905O1.953 have tetragonal and cubic composite phases. The influence of the chemical composition on coefficient of thermal expansion (CTE) and the thermal conductivity was investigated by varying the content of rare earth dopant. Dy0.06Y0.072Zr0.868O1.934 exhibited a lower thermal conductivity and higher coefficient of thermal expansion as compared with standard 8 wt% Y2O3 stabilized ZrO2 which is used in conventional thermal barrier coatings. The compatibility between the thermally grown oxide that consists of Al2O3 and the new compositions is critical to ensure the durability of thermal barrier coatings. Hence, the compatibility between Al2O3 and Dy2O3–Y2O3 co-doped YSZ was investigated by mixing two types of powders and eventually sintered at 1300 °C. Dy0.06Y0.072Zr0.868O1.934 is compatible with Al2O3, whereas YAlO3 and Dy3Al2(AlO4)3 were formed when Dy0.25Y0.25Zr0.5O1.75 and Al2O3 were mixed and sintered.
    Ceramics International 09/2014; 40(8):11593–11599.
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    ABSTRACT: The formation and evolution of oil-water interfacial waves at the inlet section of a horizontal test pipe was investigated experimentally via high-speed imaging. Images were collected with a Phantom Miro 4 camera at a rate of 1,000 fps. Wave velocity, amplitude, frequency and wave length at different oil-water flow rates (input ratios, r = 0.6 – 2.5; mixture velocities, Umix = 0.8 – 2 ms-1) were calculated from the images. The fluids used were tap water (ρ = 1,000 kgm-3, μ = 0.001 kgm-1s-1) and Exxsol D140 oil (ρ = 830 kgm-3, μ = 0.0055 kgm-1s-1). The waves formed via a KH mechanism immediately after the junction where the two fluids joined and at a velocity roughly equal to half the mixture velocity with a frequency in the range 11 – 20 Hz for all flowrate combinations. Once formed, and at a short distance from the junction the wave amplitudes decreased while the wave velocities and the wavelengths increased. The frequency, however, remained constant. Experimental data was compared against predictions of the wave theory and the instability analysis. The propagation of interfacial waves at half the mixture velocity was predicted by the theory of dynamic waves. Results from the inviscid stability analysis at the inlet agreed qualitatively with the flow pattern map of fully-developed flow, but quantitative differences were seen, which could be due to the viscosity of the oil phase.
    Experimental Thermal and Fluid Science 09/2014;

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  • Address
    Gower Street, WC1E 6BT , London, Greater London, United Kingdom
  • Head of Institution
    Malcolm John Grant, CBE
  • Website
    http://www.ucl.ac.uk/
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    +44 (0) 20 7679 2000
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Top publications last week by downloads

 
Journal of the American Psychoanalytic Association 02/2006; 54(2):537-59.
209 Downloads
 
Pakistan Journal of Botany. 01/2005; 37:739-748.
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