1,484 research outputs found

    Where\u27s the air conditioning switch? : Identifying problems for sustaining local architectural traditions in the contemporary United Arab Emirates

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    This paper examines the perception of vernacular architecture in the modern cities of the United Arab Emirates (UAE) and how this view creates obstacles in sustaining historic building forms and techniques. I argue that the greatest obstacle is the complex symbolic role that these buildings play in modern nation-building. While historic buildings are viewed with nostalgia, they are also not deemed suitable for contemporary life and have been isolated in the process of economic and social development. Separated from enlivening social activities, historic architecture in the UAE seems destined to survive only as outdoor museum displays

    Digital architectural reconstruction: New media technology and their use as educational tools in the Arabian Gulf

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    The Department of Art and Design at Zayed University has instigated a collaborative research project incorporating faculty and student work in cooperation with the archaeological staff at the National Museum of Ras al-Khaimah focused on documenting the vernacular architecture of Ras al-Khaimah. The project is important for a number of reasons, including the massive development now undertaken in the United Arab Emirates and the fact that all our students are female in a still male-dominated society

    Capacity markets and the EU target model – a Great Britain case study

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    The growth of interconnection between national electricity markets is key to the development and competitive efficiency of the Single EU Market for Electricity. However, in parallel with the development of the Single Market, a growing number of EU Member States have implemented – or are in the process of developing – national Capacity Mechanisms in order to ensure future security of supply, which may distort the cross-border trade of energy across interconnectors and reduce total welfare. In particular, the Electricity Market Reform (EMR) legislative package recently brought in by the UK government introduced a Capacity Market (in which two rounds of auctions have taken place to date) for the provision of generation capacity from 2018. In order to ensure that such national markets do not distort the wider energy market, it is important that the role of cross-border capacity, and the availability of interconnector capacity, is correctly consolidated into such mechanisms. In the first annual GB auction the net contribution of interconnection was included on a conservative basis informed by historical data, and while interconnectors have since been permitted to bid into the Capacity Market at a de-rated value (in a similar manner to domestic generation), generators in other markets are still not able to explicitly participate. This may continue to introduce market distortions and adversely impact both short-term dispatch and long-term investment decisions in both the GB and neighbouring markets. A number of routes are available to resolve this through a mechanism to permit cross-border participation of generators, but this requires resolution of a number of complicating factors, not least a means for properly allocating transmission capacity without introducing further distortions to the energy market. Alternative solutions could be enacted at an EU-level, such as through the alignment of Capacity Mechanisms to a common model, or the introduction of an EU-wide single Capacity Mechanism, but the current regulatory focus appears to remain on resolution of such issues at a national level

    Synthesis of wind time series for network adequacy assessment

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    When representing the stochastic characteristics of wind generators within power system simulations, the spatial and temporal correlations of the wind resource must be correctly modelled to ensure that reserve and network capacity requirements are not underestimated. A methodology for capturing these correlations within a vector auto-regressive (VAR) model is presented, and applied to a large-scale reanalysis dataset of historical wind speed data for the British Isles. This is combined with a wind speed-to-power conversion model trained against historically metered data from wind farms on the Great Britain (GB) electricity system in order to derive a lightweight model for simulating injections of wind power across a transmission network. The model is demonstrated to adequately represent ramp rates, both at a site and network level, as well as the individual correlations between sites, while being suitable for network adequacy studies which may require the simulation of many years of operation

    Adequacy assessment of future electricity networks

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    Liberalisation of electricity markets, changing patterns in the generation and use of electricity and new technologies are some of the factors that result in increased uncertainty about the future operating conditions of our power system. In this context, planning for future investments in power system requires careful selection and assessment of future operating conditions. This paper revisits the notion of power system adequacy and highlights the need for consideration of some factors that have hitherto tended not to be part of a transmission expansion planning process, in particular in respect of the credible range of possible values of system operating conditions and transitions between successive operating states. Firstly, we present some definitions of power system operational regions. Secondly, we present a stochastic optimisation model that measures the adequacy of a transmission network for given future operating conditions. Uncertainties in demand and generation are modelled using a large number of scenarios. The optimisation model identifies the critical future operating conditions needing the special attention of a power system planner. The proposed model is simulated on a 39-bus network, whereby it is shown that this model can identify critical operating conditions that need the attention of a system planner

    Scaling of space and timelike response of confined relativistic particles

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    The response of a relativistic particle bound in a linear confining well is calculated as a function of the momentum and energy transfer, q, \nu. At large values of |q| the response exhibits scaling in the variable y=\nu-|q|, which is proportional to the Nachtmann variable, \xi. The approach to scaling is studied at smaller values of |q|. Scaling occurs at \nu~|q| at relatively small |q|, and its validity extends over the entire \xi range as |q| increases; this behavior is observed in electron-proton scattering. About 10% of the response at large |q| is in the timelike region where \nu>|q|, and it is necessary to include it to fulfill the particle number sum rule. The Gross-Llewellyn Smith and Gottfried sum rules are discussed in the context of these results.Comment: 10 pages, 5 figures; submitted to Physics Letters

    Folding of a donor–acceptor polyrotaxane by using noncovalent bonding interactions

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    Mechanically interlocked compounds, such as bistable catenanes and bistable rotaxanes, have been used to bring about actuation in nanoelectromechanical systems (NEMS) and molecular electronic devices (MEDs). The elaboration of the structural features of such rotaxanes into macromolecular materials might allow the utilization of molecular motion to impact their bulk properties. We report here the synthesis and characterization of polymers that contain π electron-donating 1,5-dioxynaphthalene (DNP) units encircled by cyclobis(paraquat-p-phenylene) (CBPQT4+), a π electron-accepting tetracationic cyclophane, synthesized by using the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The polyrotaxanes adopt a well defined “folded” secondary structure by virtue of the judicious design of two DNP-containing monomers with different binding affinities for CBPQT4+. This efficient approach to the preparation of polyrotaxanes, taken alongside the initial investigations of their chemical properties, sets the stage for the preparation of a previously undescribed class of macromolecular architectures

    Parton Distributions for the Octet and Decuplet Baryons

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    We calculate the parton distributions for both polarized and unpolarized octet and decuplet baryons, using the MIT bag, dressed by mesons. We show that the hyperfine interaction responsible for the ΔN\Delta - N and Σ0Λ\Sigma^0 - \Lambda splittings leads to large deviations from SU(3) and SU(6) predictions. For the Λ\Lambda we find significant polarized, non-strange parton distributions which lead to a sizable Λ\Lambda polarization in polarized, semi-inclusive epep scattering. We also discuss the flavour symmetry violation arising from the meson-cloud associated with the chiral structure of baryons.Comment: 29 pages, 15 figure

    Dynamics of Light Antiquarks in the Proton

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    We present a comprehensive analysis of the recent data from the E866 experiment at Fermilab on Drell-Yan production in pD and pp collisions, which indicates a non-trivial x-dependence for the asymmetry between u-bar and d-bar quark distributions in the proton. The relatively fast decrease of the asymmetry at large x suggests the important role played by the chiral structure of the nucleon, in particular the pi-N and pi-Delta components of the nucleon wave function. At small x the data require an additional non-chiral component, which may be attributed to the Pauli exclusion principle as first suggested by Field and Feynman.Comment: version to appear in Phys. Rev.

    Parton energy loss limits and shadowing in Drell-Yan dimuon production

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    A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/c proton beam incident on Be, Fe and W targets is reported. The behavior of the Drell-Yan ratios at small target parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross section ratios as a function of the incident parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus
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