58 research outputs found

    A systematic comparison of continuous and discrete mixture models

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    Modellers are increasingly relying on the use of continuous random coefficients models, such as Mixed Logit, for the representation of variations in tastes across individuals. In this paper, we provide an indepth comparison of the performance of the Mixed Logit model with that of its far less commonly used discrete mixture counterpart, making use of a combination of real and simulated datasets. The results not only show significant computational advantages for the discrete mixture approach, but also highlight greater flexibility, and show that, across a host of scenarios, the discrete mixture models are able to offer comparable or indeed superior model performance

    The liberalisation of maritime transport and the island regions in EU. Evidence from Greece

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    The liberalisation of maritime transport constitutes a substantial and vital progress not only in the maritime transport market but also in influencing the development of distant island regions. In the European Union (EU), the establishment of the legal framework and policy regarding the liberalisation is standing from the year of 1992. In Greece, the first attempt to harmonize the inevitable political and state framework was in 2001 (2932/2001 Act). Prevailing factors encumbered the liberalisation planning and implementing, mainly because of the incoherent procedures applied and the partial cover of principal issues regarding impingement of public interests and goods relative to island development. In our paper, we provide strongly support to the argument that the major initiative considering the development of island regions throughout European territory is that European Policy for the liberalisation of maritime transport should be oriented to the distinctive needs of island regions. Moreover, we provide a “road map” for completion of the liberalisation procedures. Hence, we address specific proposals and measures towards the healing of the inadequate regional development

    The social dimension of globalization: A review of the literature

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    With globalization affecting so many inter-connected areas, it is difficult to grasp its full impact. This literature review of over 120 sources considers the impact of globalization on wages and taxes, poverty, inequality, insecurity, child labour, gender, and migration. Opening with some stylized facts concerning globalization in 1985-2002, the authors then highlight recent findings on these areas, reporting on controversies and on emerging consensus where it exists. There follows a review of national and international policy responses designed to make globalization more sustainable and equitable and to deliver decent jobs, security and a voice in decision-making

    Stability of split flow fans

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    The performance requirements of turbofan engines demands a stability and transient capability beyond that associated with the past generations of gas turbine engines. The axial flow fan unit is most vulnerable to loading limitations due to the primary problems associated with the compression process, its sensitivity to inlet distortion and the difficulty to design for an overall optimum blade duty in a machine of wide radial blade loading distribution. The development of mathematical models with some capability of predicting the stable operating range of an axial flow fan has to overcome the difficulties associated with the modelling of the radially distinct flow regions and their dynamic interaction. ' The current investigation combined the available knowledge of one-dimensional models (based on the principles of conservation of mass, linear momentum and energy) with the assumptions of the parallel compressor theory, in order to develop a linearized system of equations for stability analysis (surge prediction). The stability conditions which emerged from this approach were applied on the experimentally derived characteristics of a low hub to tip ratio split flow fan in a manner which involved the modelling of the dynamic interaction of the inner and outer flow region of the fan. The development of the governing equations was achieved by applying one-dimensional flow analysis to the inner and outer section of the fan. Their interaction was modelled on the experimentally obtained radial movement of the splitter streamline and the discharge ,static pressure 'radial distribution. The inner and outer region were treated as a lumped volume element search operating on a local masflow averaged total pressure rise characteristic and alternatively acting in conjunction with a common nozzle and separate nozzles. The experimental investigation was carried out on a low hub totipratio two-stage split flow fan(with the facility of independent bypass and core throttles)in order to examine the localised and overall performance of such a fan(and the staling processes involved)and to enable the application of the stability analysis. The influence of reducing the distance between the fan flow spliter and the last bladerowasal so investigated, «The mathematical mode1s predicted the point of dynamic instability within 4.52 of the experimental observed mas flow rate and pressure is value

    The Potential of Gas Turbine Propulsion in Modern Merchant Shipping

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    Stability of split flow fans

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