5,897 research outputs found

    Smooth Random Surfaces from Tight Immersions?

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    We investigate actions for dynamically triangulated random surfaces that consist of a gaussian or area term plus the {\it modulus} of the gaussian curvature and compare their behavior with both gaussian plus extrinsic curvature and ``Steiner'' actions.Comment: 7 page

    Energy, greenhouse gas emissions and irrigated agriculture

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    On-farm energy efficiency is becoming a significant issue for highly mechanised irrigated agricultural industries due to rising energy costs and concern over greenhouse gas (GHG) emissions. Energy represents a major cost and one of the fastest growing input costs to primary producers. The Australian cotton growing industry is highly mechanised and heavily reliant on fossil fuels (electricity and diesel). Within highly mechanised farming systems such as those used within the cotton industry, machinery costs can represent 40 – 50% of the cotton farm input costs. Given the major dependence on machinery (direct energy inputs) and rising energy costs, energy use efficiency is an emerging issue for the Australian Cotton Industry. Both previous and current work undertaken by the National Centre for Engineering in Agriculture (NCEA) is studying direct on farm energy use which involves a number of case study cotton farms to understand the contribution of direct energy use to cotton production and greenhouse gas emissions. The results from this work show that energy use varies depending on the cropping enterprise and the farming system and that there are significant opportunities to reduce energy and costs. In comparison the greenhouse gas emissions (GHGs) from direct energy use can be similar and in fact greater than the GHGs generated by nitrogen based fertiliser

    Crossover Between Weakly and Strongly Self-avoiding Random Surfaces

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    We investigate the crossover between weak and strong self-avoidance in a simulation of random surfaces with extrinsic curvature. We consider both dynamically triangulated and rigid surfaces with the two possible discretizations of the extrinsic curvature term.Comment: 5 page

    An Effective Model for Crumpling in Two Dimensions?

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    We investigate the crumpling transition for a dynamically triangulated random surface embedded in two dimensions using an effective model in which the disordering effect of the XX variables on the correlations of the normals is replaced by a long-range ``antiferromagnetic'' term. We compare the results from a Monte Carlo simulation with those obtained for the standard action which retains the XX's and discuss the nature of the phase transition.Comment: 5 page

    Ising Model Coupled to Three-Dimensional Quantum Gravity

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    We have performed Monte Carlo simulations of the Ising model coupled to three-dimensional quantum gravity based on a summation over dynamical triangulations. These were done both in the microcanonical ensemble, with the number of points in the triangulation and the number of Ising spins fixed, and in the grand canoncal ensemble. We have investigated the two possible cases of the spins living on the vertices of the triangulation (``diect'' case) and the spins living in the middle of the tetrahedra (``dual'' case). We observed phase transitions which are probably second order, and found that the dual implementation more effectively couples the spins to the quantum gravity.Comment: 11 page

    The Use of High Strength Geosynthetics in Deep Soil Mixed Levee Foundations

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    The construction and design of flood protection embankment levees within coastal areas has become a focal point for infrastructure management. The levees are usually constructed over soils with very poor bearing capacity due to their proximity to flood plains. The foundation soils create issues with long-term settlement, changing the protection height and creating the need to periodically build the levee back to the design height. In order to reduce settlements and the maintenance required to preserve design height protection, a deep foundation is needed for proper long term load transfer. Deep soil mixing (DSM) has become a popular deep foundation solution for just this type of geotechnical issue. Deep soil mixing is a technique used to create cement/soil bonded columns that are utilized as end load bearing elements. The columns are used to bridge the soft foundation soils and create a semi rigid foundation for support of the levee embankment. This solution was recently used by the Corp of Engineers in New Orleans for a protection levee. For this project, a high strength geosynthetic was incorporated into the design and installed over the columns. This paper will outline the considerations necessary for geosynthetic inclusion within deep soil mixed foundations. With the proper use of reinforcement, these applications can become even more efficient in time and cost vs. unreinforced
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