142 research outputs found

    Investigating the concept, practice and strategy of human resource development in Saudi public organisations

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    This thesis explores how HRD is conducted in the under-researched context of the Arab Middle East, specifically in Saudi Arabian public organisations. Four research questions are addressed: how HRD is conceptualized by practitioners; what systems, processes and approaches are currently prevalent in these organisations, to what extent the HRD function in these organisations is strategic and what are the main challenges facing HRD now and in the future in Saudi public organisations. A mixed – methods approach was adopted, grounded on a pragmatic rationale. Quantitative data were collected from a questionnaire survey of HRD managers in all 158 public organisations; 115 usable responses were returned. Issues emerging from the survey were then explored in depth via semi – structured interviews with a non- random sample of 23 managers. Findings revealed a conceptualization of HRD similar that in the West, reflecting notions of human capital, whole – person development, improved productivity and keeping pace with environmental change. However, participants were caught in competing dynamics of tradition versus modernization and centralizations versus decentralization, which undermined their efforts and left them frustrated. With regard to the strategic role of HRD, again, reality did not match the rhetoric. HRD was often relegated to an administrative role and practitioners excluded from decision-making. Long-term benefits were commonly sacrificed to short – term cost concerns. It is concluded that the main challenges facing HRD now and in the future in Saudi Arabia are the need for practitioners to be creative and proactive in asserting their influence and developing the professional status of HRD; the struggle to balance competing cultural assumptions and to develop a culturally appropriate model of HRD; and the need for greater clarity in the governmental HRD strategy by which the public organisations‟ HRD efforts are both encouraged and constrained

    Metal-dielectric-metal plasmonic resonators for active beam steering in the infrared

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    Cataloged from PDF version of article.Active beam-steering devices near the optical frequencies have long been sought after due to their applications in communication, defense, and display technologies; however, the challenge lies in achieving actively tunable structures near these frequencies. An array of metal-dielectric-metal plasmonic resonators is demonstrated as a dynamic beam-steering device to operate at midinfrared wavelengths. We numerically demonstrate continuous-angle beam steering of 8.75° by making use of tunable properties of silicon as the active dielectric. The proposed device achieves a refractive index insensitive divergence angle and it operates in a 650 nm wide spectral window around 10 μm wavelength. The results of this Letter pave the way to exploiting active beam steering in various applications at midinfrared wavelengths. © 2013 Optical Society of Americ

    Resistive Switching based Electro-Optical Modulation

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    Cataloged from PDF version of article.Resistive switching enables optical modulation via atomic scale modifications that induce change in the refractive index of active device materials. The formation of filaments and migration of atoms around these filaments between high resistance and low resistance states results in the modulation of the free carrier concentration and, hence, the optical constants of the material

    Ultrahigh contrast one-way optical transmission through a subwavelength slit

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    Cataloged from PDF version of article.We computationally demonstrate one-way optical transmission characteristics of a subwavelength slit. We comparatively study the effect in single layer and double layer metallic corrugations. We also investigate the effect of a dielectric spacer layer between double corrugations to control the volumetric coupling of plasmon and optical modes. We computationally show unidirectional transmission behavior with an ultrahigh contrast ratio of 53.4 dB at λ01.56 μm. Volumetric coupling efficiency through the nanoslit strongly depends on the efficient excitation of both the surface plasmon resonance and metal–insulator–metal waveguide modes. We show that the behavior is tunable in a wide spectral range (C) Springer Science+Business Media, LLC 201

    Effect of Gold Nanoparticles Size on Light Scattering for Thin Films Amorphous-Silicon Cells

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    Cataloged from PDF version of article.In this work, the effect of gold (Au) nanoparticles on the performance of a-Si:H solar cells is investigated experimentally. The solar cell stack is grown on a highly doped p-type Si wafer and consists of 20nm heavily doped p-type a-Si, 500nm undoped a-Si, 20nm heavily doped n-type a-Si and finally 80nm Indium Tin Oxide (ITO) on the top. Au nanoparticles of 10, 20, 50, 80, 100, 200 and 400nm are spin coated on top of the ITO before metallization. The plasmonic effect of the Au nanoparticles allows for additional scattering at the surface thus reducing the overall reflectivity. The larger the nanoparticle size the more scattering is obtained and the median reflectivity drops from about 23% to 18%. The results show an increase in the short-circuit current density (Jsc) and efficiency with increasing nanoparticle size. The Jsc increases from 9.34 to 10.1mA/cm2. In addition, the efficiency increases from 4.28% to 5.01%. © 2014 Elsevier Ltd

    Triangular metallic gratings for large absorption enhancement in thin film Si solar cells

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    Cataloged from PDF version of article.We estimate high optical absorption in silicon thin film photovoltaic devices using triangular corrugations on the back metallic contact. We computationally show 21.9% overall absorptivity in a 100-nm thick silicon layer, exceeding any reported absorptivity using single layer gratings placed on the top or the bottom, considering both transverse electric and transverse magnetic polarizations and a wide spectral range (280 - 1100 nm). We also show that the overall absorptivity of the proposed scheme is relatively insensitive to light polarization and the angle of incidence. We also discuss the implications of potential fabrication process variations on such a device. ©2012 Optical Society of Americ

    An all-ZnO microbolometer for infrared imaging

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    Cataloged from PDF version of article.Microbolometers are extensively used for uncooled infrared imaging applications. These imaging units generally employ vanadium oxide or amorphous silicon as the active layer and silicon nitride as the absorber layer. However, using different materials for active and absorber layers increases the fabrication and integration complexity of the pixel structure. In order to reduce fabrication steps and therefore increase the yield and reduce the cost of the imaging arrays, a single layer can be employed both as the absorber and the active material. In this paper, we propose an all-ZnO microbolometer, where atomic layer deposition grown zinc oxide is employed both as the absorber and the active material. Optical constants of ZnO are measured and fed into finite-difference-time-domain simulations where absorption performances of microbolometers with different gap size and ZnO film thicknesses are extracted. Using the results of these optical simulations, thermal simulations are conducted using finite-element-method in order to extract the noise equivalent temperature difference (NETD) and thermal time constant values of several bolometer structures with different gap sizes, arm and film thicknesses. It is shown that the maximum performance of 171 mK can be achieved with a body thickness of 1.1 μm and arm thickness of 50 nm, while the fastest response with a time constant of 0.32 ms can be achieved with a ZnO thickness of 150 nm both in arms and body. © 2014 Elsevier B.V. All rights reserved

    Metal-dielectric-metal plasmonic resonators for active beam steering in the infrared

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    Active beam-steering devices near the optical frequencies have long been sought after due to their applications in communication, defense, and display technologies; however, the challenge lies in achieving actively tunable structures near these frequencies. An array of metal-dielectric-metal plasmonic resonators is demonstrated as a dynamic beam-steering device to operate at midinfrared wavelengths. We numerically demonstrate continuous-angle beam steering of 8.75° by making use of tunable properties of silicon as the active dielectric. The proposed device achieves a refractive index insensitive divergence angle and it operates in a 650 nm wide spectral window around 10 μm wavelength. The results of this Letter pave the way to exploiting active beam steering in various applications at midinfrared wavelengths. © 2013 Optical Society of America

    Electrically controlled resistive switching assisted active ultra-broadband optical tunability in the infrared

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    We present an electrically tunable optical device with ultra-broadband tunability operating in 2-10 μm spectrum. We also, for the first time, optically observe resistive switching behavior in reflection measurements under electrical bias. © 2013 IEEE

    Resistive switching-based electro-optical modulation

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