6,817 research outputs found

    DECISION SYSTEMS RESEARCH FOR THE TOURISM/RECREATION INDUSTRY

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    Resource /Energy Economics and Policy,

    On raw coding of chaotic dynamics

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    Hysteresis phenomenon in deterministic traffic flows

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    We study phase transitions of a system of particles on the one-dimensional integer lattice moving with constant acceleration, with a collision law respecting slower particles. This simple deterministic ``particle-hopping'' traffic flow model being a straightforward generalization to the well known Nagel-Schreckenberg model covers also a more recent slow-to-start model as a special case. The model has two distinct ergodic (unmixed) phases with two critical values. When traffic density is below the lowest critical value, the steady state of the model corresponds to the ``free-flowing'' (or ``gaseous'') phase. When the density exceeds the second critical value the model produces large, persistent, well-defined traffic jams, which correspond to the ``jammed'' (or ``liquid'') phase. Between the two critical values each of these phases may take place, which can be interpreted as an ``overcooled gas'' phase when a small perturbation can change drastically gas into liquid. Mathematical analysis is accomplished in part by the exact derivation of the life-time of individual traffic jams for a given configuration of particles.Comment: 22 pages, 6 figures, corrected and improved version, to appear in the Journal of Statistical Physic

    Irrational homeowners? How aesthetics and heritage values influence thermal retrofit decisions in the United Kingdom

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    In order to reduce CO2 emissions in line with UK policy, existing UK homes need to be retrofitted to high thermal standards. A large proportion of these homes have traditional or aesthetically pleasing features which people are reluctant to compromise for the sake of thermal efficiency. A minority of such dwellings are protected by statute, but millions are not. There is a dearth of structured discussion on the issues owners of such homes face when planning thermal retrofits. This study begins with a literature review of sustainable development, heritage and aesthetics. It then reports the results of qualitative interviews with retrofitting owners of such homes in Cambridge, UK. It finds homeowners struggling to balance thermal issues against a range of heritage and aesthetic concerns which often overlap or clash. Homeowners develop their own logic in working these through, and their aesthetic convictions strongly influence what happens with retrofitting. The interviews suggest that concern for the heritage embodied in the housing stock can be one reason current policy does not always engage homeowners in retrofitting.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S2214629615300566

    Quantification of (p)rebound effects in retrofit policies - Why does it matter?

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    The ‘prebound effect’ characterises how average heating energy consumption in older homes is consistently lower than these buildings' calculated energy ratings, and helps explain why energy savings from thermal upgrades are often lower than anticipated. This paper explores the conceptual links between prebound and rebound effects and aims to quantify these behavioural effects. It applies the resulting mathematical model to empirical examples of actual and calculated energy consumption at scales of individual dwelling and national housing stock. These show that the rebound effect, as defined in econometrics literature, can only indicate proportionate reductions in energy consumption and can mask high levels of absolute consumption. The prebound effect, however, can identify under- and over-consumption regardless of rebound effects. A combination of high prebound effect and low income suggests fuel poverty, and the rebound effect here is less relevant regarding total energy consumption. Policymakers should identify housing with high prebound effects in order to eliminate fuel poverty, and be aware of inaccuracies in calculating payback time where economic viability of retrofits is mandated. Further research is needed to understand motivations and practices in households that have high prebound effects and to identify specific priority groups for thermal retrofit policy.The authors wish to thank Benoit Allibe, Marie-Helen Laurent and Jean-Narie Cayla of Electricite de France, for making data on French houses available for use in this paper.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.energy.2015.12.03

    Preparation and properties of amorphous MgB2_2/MgO superstructures: A new model disordered superconductor

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    In this paper we introduce a novel method for fabricating MgB2_2/MgO multilayers and demonstrate the potential for using them as a new model for disordered superconductors. In this approach we control the annealing of the MgB2_2 to yield an interesting new class of disordered (amorphous) superconductors with relatively high transition temperatures. The multilayers appear to exhibit quasi-two-dimensional superconductivity with controlled anisotropy. We discuss the properties of the multilayers as the thickness of the components of the bilayers vary.Comment: 7 pages, 8 figure

    Bifractality of the Devil's staircase appearing in the Burgers equation with Brownian initial velocity

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    It is shown that the inverse Lagrangian map for the solution of the Burgers equation (in the inviscid limit) with Brownian initial velocity presents a bifractality (phase transition) similar to that of the Devil's staircase for the standard triadic Cantor set. Both heuristic and rigorous derivations are given. It is explained why artifacts can easily mask this phenomenon in numerical simulations.Comment: 12 pages, LaTe

    Critical thickness and orbital ordering in ultrathin La0.7Sr0.3MnO3 films

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    Detailed analysis of transport, magnetism and x-ray absorption spectroscopy measurements on ultrathin La0.7Sr0.3MnO3 films with thicknesses from 3 to 70 unit cells resulted in the identification of a lower critical thickness for a non-metallic, non-ferromagnetic layer at the interface with the SrTiO3 (001) substrate of only 3 unit cells (~12 Angstrom). Furthermore, linear dichroism measurements demonstrate the presence of a preferred (x2-y2) in-plane orbital ordering for all layer thicknesses without any orbital reconstruction at the interface. A crucial requirement for the accurate study of these ultrathin films is a controlled growth process, offering the coexistence of layer-by-layer growth and bulk-like magnetic/transport properties.Comment: 22 pages, 6 figures, accepted for publication in Physical Review
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