1,926 research outputs found

    A beam steering technique using dielectric wedges.

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    The thesis describes a method of' beam steering aimed at producing a useful amount of deflection of an antenna beam from boresight, by a simple and Inexpensive method. For large antennas, It is difficult, as well as expensive, to steer the beam by more than a few beamwidths. The method studied was developed with particular reference to the beam steering requirements of Direct Broadcast Satellite flat plate antennas. The method involves two dielectric wedges, having circular faces, placed In front of the antenna. By adjusting the relative angular position of the wedges, the beam can be steered In any direction, up to a maximum value from the antenna boresight direction. The maximum value of the deflection is determined by the wedge angle and the dielectric constant of the wedge material. This method of beam steering Is Independent of frequency. Frequency limitations are, however, set by the need for a matching layer on the wedge faces to reduce the loss due to reflection and also due to interference of multiple reflection effects on the radiation pattern. Extensive investigations are made (both theoretical and experimental) to predict the performance of the wedges as the beam Is steered. The effect of reflection is studied and a new matching technique is devised. Other practical considerations for example, stepping the wedges for weight reduction, the effect of loss in the dielectric material and cross polar performance are also taken into account. Some effort is given to explore the possibility of using metal loaded artificial dielectrics using polyurethane as the base material. Finally, a number of charts are presented to determine the amount of beam steering for an arbitrary position of the wedges

    Tourists’ Personal Development Through Participatory Consumer-Generated Content

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    The paper seeks to investigate key factors influencing the personal development of tourists. This study examines the relationship between participatory consumer-generated content and tourists’ capabilities, emotions, and skills, as well as the moderating effect of previous tourists’ experiences. To evaluate the research model, 301 valid responses were examined using the PLS-SEM technique. The empirical findings showed that participatory consumer-generated content positively relates to tourists’ capabilities, emotions, and skills. Moreover, previous tourists’ experiences moderate the relationships of participatory consumer-generated content with tourists’ capabilities and skills; however, previous tourists’ experiences have no moderation effect on tourists’ emotions. Thus, our paper's findings offer valuable contributions to theory and practice. Practitioners and authorities should stimulate users to share their tourism experiences and take the initiative to share easily traceable and searchable data. Moreover, businesses should implement activities that encourage tourists to share their experiences as soon as possible and make travel and tourism websites and social media platforms readily available

    Corporate Social Responsibility, Sustainability Governance and Sustainable Performance: A Preliminary Insight

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    This conceptual paper aims to investigate corporate social responsibility (CSR) practises in the tourism sector. Drawing on the existing literature, this study conceptualises the linkage between CSR, sustainability governance, and sustainable performance. Moreover, this study conceptualises three sub-dimensions of CSR. The integration of CSR in the tourism sector is significant and novel. An analytical review is conducted to present conceptual linkage and research implications. The finding implies that CSR positively influences the sustainable performance of organisations and sustainable governance plays a mediating role between relationships. This study provides important implications that help tourism industry practitioners to realise the significance of reducing environmental and social problems, which cause by tourism activities. Further, this study obtains support from institutional theory to explain the relationships of governance mechanism and CSR that leads to economic performance as well as create value for nature and the local community. Additionally, the future direction of research is provided that highlights some important avenues in the sustainability fiel

    Carbon neutrality concept and progress

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    Sufficient scientific evidence now shows that Earth’s temperature is warmer than before. The temperature of the planet (global warming) is becoming s source of climate change that is estimated to have negative consequences for all living beings (Sovacool and Griffiths, 2020). Climate change, if it keeps moving in the direction in which it is heading now, will have severe consequences for anything and everything that exists on this planet. This is not a man-made story; rather, the argument is established upon the data collected by international organizations such as United Nations’ Intergovernmental Panel on Climate Change, Environmental Protection Agency, and NASA, among others. Data on global warming have been gathered across multiple time periods and analyzed for a very long time to arrive at the conclusion of severe and unpleasant consequences for everyone and everything on the planet. Excessive carbon dioxide emis- sions is the main contributing factor of global warming. However, it is not only carbon dioxide that causes global warming—many other gases are harmful to the climate, such as carbon dioxide, methane, and nitrous oxide, as well as hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. This is not an exhaustive list, but for now, think of greenhouse gases as a catch-all term for the harmful substances we are pumping into the atmo- sphere. Since carbon dioxide has the most significant share among harmful gases, academic and nonacademic researchers study carbon dioxide more than other gases

    Enhancing business performance through green human resource management practices: an empirical evidence from Malaysian manufacturing industry

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    Sustainability has come under public policy limelight. Organizations are investing to minimize the impact of environmental degradation to build their image as an environmentally friendly firm, which contributes to their business performance as well. Literature suggests that green organizational indicators are found to be positively related to firm sustainable performance. More specifically green human resource management (GHRM) practices strengthen the firm’s environmental practices and enhance employee morale toward green practices. The paper aims to investigate the impact of GHRM indicators on environmental performance (EP) and business performance (BP)

    The differential modulation of receptor tyrosine kinase Axl in human mesenchymal stromal cell responses to modified titanium surfaces

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    Osseointegration is the process of de novo bone regeneration on the surface of an endosseous titanium (Ti) implant in vivo. This neo formation of bone underlies the physical integration of a Ti implant in bone at a level sufficient to restore loss of function; for example, of mastication due to absent teeth. The outer atoms of a bulk of Ti metal form a stable and passive surface oxide layer that serves as a substrate for the amalgamation of tissue reparative components, which entail the formation of an osseous bond between tissue and fixture. This interaction was empirically demonstrated to be highly affected by the characteristics of the surface an implant in experimental studies querying the varied effects of additive or subtractive physical modifications, as well as altered chemical compositions, of Ti implant surfaces on osseointegration. Subsequent clinical and experimental practices have demonstrated that rough surfaced implants perform comparatively ‘better’ than their smooth surfaced counterparts by promoting bone growth on the fixture. Moreover, a particular surface modification that yields high surface energy combined with a widely tested micron scaled topographical roughness (modSLA) has been shown to further promote the timely enhancement of osseointegration compared to its hydrophobic rough counterpart (SLA). The biological mechanisms underlying this apparent enhancement of osseointegration by modified Ti implant surfaces are still subject to intense study due to the materials’ implications in bone related tissue engineering applications. Amongst the several views being opined is a proposition mainly arising from in vitro experimentation, which suggests modified Ti implant surfaces possess an ‘intrinsic’ osteoinductive potential that affects uncommitted reparative cells by inducing a temporal and magnitudinal enhancement in cellular differentiation and function; in turn, implying the early formation of functional osteoblasts and bone tissue matrix in an in vivo scenario. The observations of differential cellular behavior include the apparent modulation by the modified surfaces, of a cell surface receptor tyrosine kinase Axl in human osteoblasts. The proposed role of the receptor in negatively regulating osteogenic mineralisation in uncommitted pericytic cells suggests an association with the altered response of cells to these substrates. The aim of this project was to examine and test the hypothesised differential modulation of Axl in the responses of human marrow derived mesenchymal stromal cells to modified Ti implant substrates

    Preventing oxidation of canola and sunflower oils by addition of pomegranate seed oil

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    The study was designed to explore the antioxidative effect of pomegranate seed oil (PSO) at different concentrations (5 and 7%) against oxidation of plant-based oils (canola oil and sunflower oil) during storage (60 days) as compared to artificial antioxidant butylated hydroxyanisole (BHA, 200 ppm). Rancimat and Schaal oven analysis were employed for the assessment of potential consequences of PSO against oxidation in plant based oils. The variation in total phenolic contents (TPC), antioxidant activity, peroxide value (POV), and tocopherol contents during storage were evaluated by Schaal oven test at 62 °C. The substantially (P≤0.05) higher induction period (IP) values were observed for PSO blended oil samples as compared to blank oil samples. The addition of PSO in plant-based oils improved the oxidative stability by enhancing the antioxidant potential and TPC, decreasing POV, and slowing down the degradation of tocopherol contents during storage. The findings of the present study suggest that PSO might be used as an alternative potential antioxidant to synthetic antioxidants

    Engineered photocatalysts for detoxification of waste water

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    This report describes progress on the development of engineered photocatalysts for the detoxification of water polluted with toxic organic compounds and heavy metals. We examined a range of different oxide supports (titania, alumina, magnesia and manganese dioxide) for tin uroporphyrin and investigated the efficacy of a few different porphyrins. A water-soluble octaacetic-acid-tetraphenylporphyrin and its derivatives have been synthesized and characterized in an attempt to design a porphyrin catalyst with a larger binding pocket. We have also investigated photocatalytic processes on both single crystal and powder forms of semiconducting SiC with an ultimate goal of developing a dual-semiconductor system combining TiO{sub 2} and SiC. Mathematical modeling was also performed to identify parameters that can improve the efficiency of SiC-based photocatalytic systems. Although the conceptual TiO{sub 2}/SiC photodiode shows some promises for photoreduction processes, SiC itself was found to be an inefficient photocatalyst when combined with TiO{sub 2}. Alternative semiconductors with bandgap and band potentials similar to SiC should be tested in the future for further development and a practical utilization of the dual photodiode concept

    Industrial Digitization, the Use of Real-Time Information, and Operational Agility: Digital and Information Perspectives for Supply Chain Resilience

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    Change is the permanent reality of the digital business world. Firms manage it by their ability and capability to cope with short-term and long-term deviations and disruptions. This paper presents an examination of the supply chain resilience (SCR) of firms operating in the Malaysian Service Sector. The data for this study were collected from 157 managers of 59 firms operating in seven sub-service sectors. Following Organizational Information Processing Theory (OIPT) and reviewing the relevant literature for the conceptualization, we tested a framework that suggests that the use of real-time information (URTI) enhances the SCR. We also found that the industrial digital environment has an important link with the URTI. The results indicate that the URTI is significantly associated with SCR and operational agility, which partially mediates the relationship between the URTI and SCR. We further discuss the theoretical contributions and implications with practical, and policy implications arising from this research

    A new cascaded spectral subtraction approach for binaural speech dereverberation and its application in source separation

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    In this work we propose a new binaural spectral subtraction method for the suppression of late reverberation. The pro- posed approach is a cascade of three stages. The first two stages exploit distinct observations to model and suppress the late reverberation by deriving a gain function. The musical noise artifacts generated due to the processing at each stage are compensated by smoothing the spectral magnitudes of the weighting gains. The third stage linearly combines the gains obtained from the first two stages and further enhances the binaural signals. The binaural gains, obtained by indepen- dently processing the left and right channel signals are com- bined using a new method. Experiments on real data are per- formed in two contexts: dereverberation-only and joint dere- verberation and source separation. Objective results verify the suitability of the proposed cascaded approach in both the contexts
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