599 research outputs found

    Development of inflatable structures at the University of Southampton

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    Inflatable technology for space applications is under continual development and advances in high strength fibres and rigidizable materials have pushed the limitations of these structures. This has lead to their application in deploying large-aperture antennas, reflectors and solar sails. However, many significant advantages can be achieved by combining inflatable structures with structural stiffeners such as tape springs. These advantages include control of the deployment path of the structure while it is inflating (a past weakness of inflatable structure designs), an increased stiffness of the structure once deployed and a reduction in the required inflation volume. Such structures have been previously constructed at the Jet Propulsion Laboratory focusing on large scale booms. However, due to the high efficiency of these designs they are also appealing to small satellite systems. This article outlines ongoing research work performed at the University of Southampton into the field of small satellite hybrid inflatable structures. Inflatable booms have been constructed and combined with tape spring reinforcements to create simple hybrid structures. These structures have been subjected to bending tests and compared directly to an equivalent inflatable tube without tape spring reinforcement. This enables the stiffness benefits to be determined with respect to the added mass of the tape springs. The paper presents these results, which leads to an initial performance assessment of these structures

    Nuclear Technologies in a Sustainable Energy System; Selected Papers from an IIASA Workshop, May 25-27, 1981

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    This book stems from the effort within IIASA to explore possible "sustainable" global energy systems that might eventually replace the current "consumptive" system. In investigating the possible contributions nuclear technologies might make to a sustainable energy system, it had become clear that it is not so much particular, distinct technologies within the nuclear family that should be examined but rather particularly advantageous configurations of mutually complementary technologies. Only when one considers exploiting a whole spectrum of arrangements of fission breeders, fusion reactors, and accelerators does the true potential of nuclear power become apparent

    Dilaton as the Higgs boson

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    We propose a model where the role of the electroweak Higgs field is played by the dilaton. The model contains terms which explicitly violate gauge invariance, however it is shown that this violation is fictitious, so that the model is a consistent low energy effective theory. In the simplest version of the idea the resulting low energy effective theory is the same as the top mode standard model.Comment: 6 pages, v2 with expanded discussio

    Healthy hardwoods. A field guide to pests, diseases and nutritional disorders in subtropical hardwoods.

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    Healthy hardwoods: A field guide to pests, diseases and nutritional disorders in subtropical hardwoods can be used to help identify the common damaging insects, fungi and nutritional disorders in young eucalypt (Eucalyptus and Corymbia species) plantations in subtropical eastern Australia. This guide includes photographs of each insect, fungus and nutritional disorder and the damage they cause, along with a brief description to aid identification. A brief host list for insects and fungi, including susceptibility and occurrence, is provided as a guide only. A hand lens will be useful, especially to identify fungi. Although it is possible to identify insects and fungi from these photographs, laboratory examination will sometimes be necessary. For example, microscopes and culturing media might be used to identify fungi. Information about four exotic pests and diseases has also been included in the Biosecurity threats chapter. Potentially, these would have a severe impact on plantation and natural forests if introduced into Australia. To prevent establishment of these pests, early detection and identification is crucial. If an exotic insect or disease is suspected, then an immediate response is required. Usually, the first response will be to contact the nearest Australian Quarantine and Inspection Service office or forestry agency to seek advice

    Universality classes in nonequilibrium lattice systems

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    This work is designed to overview our present knowledge about universality classes occurring in nonequilibrium systems defined on regular lattices. In the first section I summarize the most important critical exponents, relations and the field theoretical formalism used in the text. In the second section I briefly address the question of scaling behavior at first order phase transitions. In section three I review dynamical extensions of basic static classes, show the effect of mixing dynamics and the percolation behavior. The main body of this work is given in section four where genuine, dynamical universality classes specific to nonequilibrium systems are introduced. In section five I continue overviewing such nonequilibrium classes but in coupled, multi-component systems. Most of the known nonequilibrium transition classes are explored in low dimensions between active and absorbing states of reaction-diffusion type of systems. However by mapping they can be related to universal behavior of interface growth models, which I overview in section six. Finally in section seven I summarize families of absorbing state system classes, mean-field classes and give an outlook for further directions of research.Comment: Updated comprehensive review, 62 pages (two column), 29 figs included. Scheduled for publication in Reviews of Modern Physics in April 200

    Thermodynamics of SU(3) gauge theory on anisotropic lattices

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    Finite temperature SU(3) gauge theory is studied on anisotropic lattices using the standard plaquette gauge action. The equation of state is calculated on 163×816^{3} \times 8, 203×1020^{3} \times 10 and 243×1224^{3} \times 12 lattices with the anisotropy ξas/at=2\xi \equiv a_s / a_t = 2, where asa_s and ata_t are the spatial and temporal lattice spacings. Unlike the case of the isotropic lattice on which Nt=4N_t=4 data deviate significantly from the leading scaling behavior, the pressure and energy density on an anisotropic lattice are found to satisfy well the leading 1/Nt21/N_t^2 scaling from our coarsest lattice, Nt/ξ=4N_t/\xi=4. With three data points at Nt/ξ=4N_t/\xi=4, 5 and 6, we perform a well controlled continuum extrapolation of the equation of state. Our results in the continuum limit agree with a previous result from isotropic lattices using the same action, but have smaller and more reliable errors.Comment: RevTeX, 21 pages, 17 PS figures. A quantitative test about the benefit of anisotropic lattices added, minor errors corrected. Final version for PR

    Integrating group Delphi, fuzzy logic and expert systems for marketing strategy development:the hybridisation and its effectiveness

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    A hybrid approach for integrating group Delphi, fuzzy logic and expert systems for developing marketing strategies is proposed in this paper. Within this approach, the group Delphi method is employed to help groups of managers undertake SWOT analysis. Fuzzy logic is applied to fuzzify the results of SWOT analysis. Expert systems are utilised to formulate marketing strategies based upon the fuzzified strategic inputs. In addition, guidelines are also provided to help users link the hybrid approach with managerial judgement and intuition. The effectiveness of the hybrid approach has been validated with MBA and MA marketing students. It is concluded that the hybrid approach is more effective in terms of decision confidence, group consensus, helping to understand strategic factors, helping strategic thinking, and coupling analysis with judgement, etc

    Angular momenta creation in relativistic electron-positron plasma

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    Creation of angular momentum in a relativistic electron-positron plasma is explored. It is shown that a chain of angular momentum carrying vortices is a robust asymptotic state sustained by the generalized nonlinear Schrodinger equation characteristic to the system. The results may suggest a possible electromagnetic origin of angular momenta when it is applied to the MeV epoch of the early Universe.Comment: 20 pages, 6 figure

    Absorptive capacity and market orientation in public service provision

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    This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of Strategic Marketing on 05.04.2012, available online at: http://www.tandfonline.com/10.1080/0965254X.2011.643915The application of market orientation to public organisations does not adequately account for the unique features of this context. Drawing on absorptive capacity literature, this is the first study to examine the role of the organisation's learning environment on the market orientation-performance interface for two opposing public management contexts. The research involved a national survey questionnaire to 1060 internal and external public leisure service providers in England. Empirical testing through structural equation modelling revealed that not all dimensions of market orientation are universally positive and marketing scholars should seek to examine and understand market orientation in the context of the organisation and its learning mechanisms, as absorptive capacity has clear and different moderation effects under different management contexts. © 2012 Copyright Taylor and Francis Group, LLC

    Cytogenetic characterization of telomeres in the holocentric chromosomes of the lepidopteran Mamestra brassicae

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    Telomeres of the Mamestra brassica holocentric chromosomes were studied by Southern blotting, in-situ hybridization and Bal31 assay evidencing the presence of the telomeric (TTAGG)(n) repeat. Successively, molecular analysis of telomeres showed that TRAS1 transposable elements were present at the subtelomeric regions of autosomes but not in the NOR-bearing telomeres of the Z and W sex chromosomes. TRAS1 appeared to be transcriptionally active and non-methylated, as evaluated by RT-PCR and digestion with MspI and HpaII. Finally, dot-blotting experiments showed that the 2.8 +/- 0.5% of the M. brassicae genome consists of TRAS1
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