753 research outputs found

    Where does solar-aided seawater desalination make sense? A method for identifying sustainable sites

    Get PDF
    AbstractGlobal water planners are increasingly considering seawater desalination as an alternative to traditional freshwater supplies. Since desalination is both expensive and energy intensive, taking advantage of favorable natural and societal conditions while siting desalination facilities can provide significant financial and environmental returns. Currently, policy makers do not use a location-specific integrated analytical framework to determine where natural and societal conditions are conducive to desalination. This analysis seeks to fill that gap by demonstrating a multi-criteria, geographically-resolved methodology for identifying suitable regions for desalination infrastructure where 1) available renewable resources can offset part of the fossil energy load; 2) feedwater characteristics reduce the total energy needed for desalination; and 3) human populations have capacity and willingness to pay for desalinated water. This work demonstrates the method with a quantitative global analysis that identifies favorable sites for solar-aided seawater reverse osmosis desalination (SWRO) based on specific target criteria. Location-based data about natural conditions (solar insolation, ocean salinity, and ocean temperature) are integrated and mapped with social indicators (water stress, prevailing water prices, and population) to identify regions where solar-aided SWRO has the highest potential. This work concludes that water-stressed tropical and subtropical cities show the highest potential for economically sustainable solar-aided SWRO

    Tension of APEL: Perceptions of higher education in further education lecturers

    Get PDF
    This article examines the perceptions of Accrediting Prior Experiential Learning (APEL) from the point of view of lecturers delivering higher education in further education institutions. Despite the fact that APEL is recognised as potentially providing a range of benefits for higher education providers, students and employers, little research has been carried out with those responsible for accreditation. Data were obtained using an online survey to collect information from lecturers about their awareness of and support for APEL. Analysis of this information reveals that confusion about the purpose and implementation remain the main barriers to APEL for this group, and that providing appropriate support for staff could be an effective mechanism for overcoming this. The implications of this study are discussed in relation to the higher education in further education context, with specific reference to the Foundation degree. © 2011 Further Education Research Association

    Classical simulation of measurement-based quantum computation on higher-genus surface-code states

    Full text link
    We consider the efficiency of classically simulating measurement-based quantum computation on surface-code states. We devise a method for calculating the elements of the probability distribution for the classical output of the quantum computation. The operational cost of this method is polynomial in the size of the surface-code state, but in the worst case scales as 22g2^{2g} in the genus gg of the surface embedding the code. However, there are states in the code space for which the simulation becomes efficient. In general, the simulation cost is exponential in the entanglement contained in a certain effective state, capturing the encoded state, the encoding and the local post-measurement states. The same efficiencies hold, with additional assumptions on the temporal order of measurements and on the tessellations of the code surfaces, for the harder task of sampling from the distribution of the computational output.Comment: 21 pages, 13 figure

    On Dijkgraaf-Witten Type Invariants

    Get PDF
    We explicitly construct a series of lattice models based upon the gauge group ZpZ_{p} which have the property of subdivision invariance, when the coupling parameter is quantized and the field configurations are restricted to satisfy a type of mod-pp flatness condition. The simplest model of this type yields the Dijkgraaf-Witten invariant of a 33-manifold and is based upon a single link, or 11-simplex, field. Depending upon the manifold's dimension, other models may have more than one species of field variable, and these may be based on higher dimensional simplices.Comment: 18 page

    Quantum Mechanics on the h-deformed Quantum Plane

    Full text link
    We find the covariant deformed Heisenberg algebra and the Laplace-Beltrami operator on the extended hh-deformed quantum plane and solve the Schr\"odinger equations explicitly for some physical systems on the quantum plane. In the commutative limit the behaviour of a quantum particle on the quantum plane becomes that of the quantum particle on the Poincar\'e half-plane, a surface of constant negative Gaussian curvature. We show the bound state energy spectra for particles under specific potentials depend explicitly on the deformation parameter hh. Moreover, it is shown that bound states can survive on the quantum plane in a limiting case where bound states on the Poincar\'e half-plane disappear.Comment: 16pages, Latex2e, Abstract and section 4 have been revise

    Changing the spatial location of electricity generation to increase water availability in areas with drought: a feasibility study and quantification of air quality impacts in Texas

    Get PDF
    The feasibility, cost, and air quality impacts of using electrical grids to shift water use from drought-stricken regions to areas with more water availability were examined. Power plant cooling represents a large portion of freshwater withdrawals in the United States, and shifting where electricity generation occurs can allow the grid to act as a virtual water pipeline, increasing water availability in regions with drought by reducing water consumption and withdrawals for power generation. During a 2006 drought, shifting electricity generation out of the most impacted areas of South Texas (~10% of base case generation) to other parts of the grid would have been feasible using transmission and power generation available at the time, and some areas would experience changes in air quality. Although expensive, drought-based electricity dispatch is a potential parallel strategy that can be faster to implement than other infrastructure changes, such as air cooling or water pipelines.National Science Foundation (U.S.). Office of Emerging Frontiers in Research and Innovation (Grant 0835414)United States. Dept. of Energ
    • …
    corecore