7,521 research outputs found

    Revealing Casual Pathways to Sustainable Water Service Delivering Using fsQCA

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    This study aimed to build on theory and practice regarding the combinations of conditions that influence water service sustainability when external partners are involved. The study investigates 26 well projects that have been implemented in developing countries with the assistance of Engineers Without Borders-USA (EWB-USA). Using past literature on sustainable water service delivery in developing communities, emergent coding techniques with project documents, and surveys with EWB-USA team members, this study identifies a set of project conditions to conduct fuzzy-set Qualitative Comparative Analysis (fsQCA). Findings show that the presence of a water committee cannot alone account for project sustainability. Additional conditions, such as technology and construction processes, project governance, and community engagement practices must also be considered for project sustainability. The relationship between construction quality and financial sustainability is also discussed. Overall, the findings from this research contribute to sector theory and reveal distinct pathways towards sustainable water services. These findings informed recommendations for EWB-USA well project implementation and management, and demonstrate the utility of fsQCA as a tool to navigate the complexities of water service delivery by external partners and improve understanding to increase water service sustainability

    Alternative determinism principle for topological analysis of chaos

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    The topological analysis of chaos based on a knot-theoretic characterization of unstable periodic orbits has proved a powerful method, however knot theory can only be applied to three-dimensional systems. Still, the core principles upon which this approach is built, determinism and continuity, apply in any dimension. We propose an alternative framework in which these principles are enforced on triangulated surfaces rather than curves and show that in dimension three our approach numerically predicts the correct topological entropies for periodic orbits of the horseshoe map.Comment: Accepted for publication as Rapid Communication in Physical Review

    Regulating the employment dynamics of domestic supply chains

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    This paper sheds light on the role that the regulation of primarily domestic, rather than global, supply chains could play in protecting and enhancing standards of workplace health and safety, as well as employment standards more generally. The analysis presented confirms the potential relevance of such regulation in these regards. However, it also reinforces existing evidence pointing to the fact that only very rarely will market-related considerations on their own prompt purchasers to seek to directly influence the employment practices of their suppliers. The paper ends therefore by highlighting a number of key issues relating to the design of regulatory initiatives aimed at protecting and enhancing employment conditions within supply chains

    Protecting workers through supply chains: lessons from two construction case studies

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    Two case studies of the successful use of supply chains to support the effective management of health and safety on constructions sites are analysed to identify the factors supporting this success. The analysis reveals that a combination of external regulatory pressures and an industry structure facilitative of the establishment and implementation of ‘good practice’ played a crucial role in the outcomes achieved. It is concluded therefore that while the findings lend weight to policy initiatives to utilise the power dynamics in supply chains to protect working conditions, they also suggest that surrounding institutional and industrial contexts exert a potentially crucial influence over their effectiveness. Consequently, it is further argued that such initiatives need to be responsively shaped to them

    Black Hole Entropy, Topological Entropy and the Baum-Connes Conjecture in K-Theory

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    We shall try to exhibit a relation between black hole entropy and topological entropy using the famous Baum-Connes conjecture for foliated manifolds which are particular examples of noncommutative spaces. Our argument is qualitative and it is based on the microscopic origin of the Beckenstein-Hawking area-entropy formula for black holes, provided by superstring theory, in the more general noncommutative geometric context of M-Theory following the Connes- Douglas-Schwarz article.Comment: 17 pages, Latex, contains an important paragraph in section 2 which gives a better understandin

    Cellular automata and Lyapunov exponents

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    In this article we give a new definition of some analog of Lyapunov exponents for cellular automata . Then for a shift ergodic and cellular automaton invariant probability measure we establish an inequality between the entropy of the automaton, the entropy of the shift and the Lyapunov exponent

    Plate-impact loading of cellular structures formed by selective laser melting

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    Porous materials are of great interest because of improved energy absorption over their solid counterparts. Their properties, however, have been difficult to optimize. Additive manufacturing has emerged as a potential technique to closely define the structure and properties of porous components, i.e. density, strut width and pore size; however, the behaviour of these materials at very high impact energies remains largely unexplored. We describe an initial study of the dynamic compression response of lattice materials fabricated through additive manufacturing. Lattices consisting of an array of intersecting stainless steel rods were fabricated into discs using selective laser melting. The resulting discs were impacted against solid stainless steel targets at velocities ranging from 300 to 700 m s-1 using a gas gun. Continuum CTH simulations were performed to identify key features in the measured wave profiles, while 3D simulations, in which the individual cells were modelled, revealed details of microscale deformation during collapse of the lattice structure. The validated computer models have been used to provide an understanding of the deformation processes in the cellular samples. The study supports the optimization of cellular structures for application as energy absorbers. © 2014 IOP Publishing Ltd

    Resonance distribution in open quantum chaotic systems

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    In order to study the resonance spectra of chaotic cavities subject to some damping (which can be due to absorption or partial reflection at the boundaries), we use a model of damped quantum maps. In the high-frequency limit, the distribution of (quantum) decay rates is shown to cluster near a ``typical'' value, which is larger than the classical decay rate of the corresponding damped ray dynamics. The speed of this clustering may be quite slow, which could explain why it has not been detected in previous numerical data.Comment: 4 pages. Compared with version 2, we have slightly modified the figures, corrected some misprints, and added the values for the fits in figure
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