4,990 research outputs found

    Toward Closing the Loop between Infrastructure Investments and Societal and Economic Impacts

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    The long-term value proposition of transportation infrastructure investments can be significantly distorted if the short term effects of spatial externalities on land-use patterns, economic expansions, and migration patterns are not properly included in the analysis. Some of these effects occur over a short period of time and soon after the investment materializes, while others take longer and follow more steady patterns. In this paper, we develop a novel dynamical model of a primal society with constructs that are specifically geared toward transportation infrastructure expansions and investments. The model quantifies the impact of these expansions on some key performance indicators and on the overall utility and production capacity of the society. We argue that traditional analytical models that work on the premises of stationary behavior and a static response of society to changes in infrastructure do not correctly capture these effects. The land use patterns and spatial expansion computed from the model are validated against existing theory on land use. Preliminary results on how to use the model for value proposition analysis are also presented using simple case studies.This is the author accepted manuscript. The final version is available from Taylor & Francis via http://dx.doi.org/10.1080/0013791X.2015.106535

    Joint Optimization of Operation and Maintenance Policies for Solar-Powered Microgrids

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    In a solar-powered microgrid (MG), the optimal maintenance strategy is influenced by the downtime cost of the photovoltaic (PV) system, which in turn depends on the operation PV within the MG network. Also, the dispatch policy used in the MG will influence the economic feasibility of maintenance plans. In this paper, we present an approach for optimizing the operation and maintenance policy jointly for a solar-powered MG considering the dependence between the two policies. The two-layered approach presented in this paper seeks to unify the practicality of simulation and the efficiency of analytical models. In the upper layer, we optimize the operation of MG by solving the optimal power dispatch within the MG network using linear programming approach. Then, we calculate the penalty costs under the aging conditions of PV systems. In the bottom layer, by incorporating the penalty costs as input parameters, we use a continuous-time Markov chain model to calculate the optimal maintenance policy for the PV system. The proposed approach could be used in the stipulation process between MG owner and PV system maintenance provider to minimize the money waste on both sides.This research was partly funded by the EPSRC/Innovate UK Centre for Smart Infrastructure and Construction (EP/N021614/1) and also supported by Sustain-Owner (Sustainable Design and Management of Industrial Assets through Total Value and Cost of Ownership), a project sponsored by the EU Framework Programme Horizon 2020, MSCA-RISE-2014: Marie Skodowska-Curie Research and Innovation Staff Exchange (Rise) (grant agreement number 645733 Sustain-owner H2020-MSCA-RISE-2014)

    Low-cost emissions cuts in container shipping: thinking inside the box

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    Container shipping has become an emission-intensive industry; existing regulations, however, continue to display limitations. Technical emissions reduction measures require large, long-term investments, while operational measures may negatively impact transportation costs and supply-chain practices. For container shipping to become more sustainable, innovative, low-cost technological solutions are required. This study discusses such a technological game-changer which utilizes a lighter container type that, contrary to conventional ones, does not require wood in its floor. In this regard, emissions reductions are achieved both due to lower fuel consumption and tree savings. We estimate the global impact of this technology until 2050 using an integrated assessment model and considering different projections about future characteristics of the container fleet. Our results indicate that the adoption of the examined technology can reduce emissions by 4.7–18.8% depending on the main fuel used in container shipping lines, saving also a total of about 44 million trees

    On Some Complex Aspects of the (2+1)-dimensional Broer-Kaup-Kupershmidt System

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    The improved Bernoulli sub-equation function method is used in extracting some new exponential function solutions to the (2+1)-dimensional Broer-Kaup-Kupershmidt system. It is of vital effort to look for more solutions of the (2+1)-dimensional Broer-Kaup-Kupershmidt system, which are very helpful for coastal and civil engineers to apply the nonlinear water models in a harbor and coastal design. All the obtained solutions satisfied the (2+1)-dimensional Broer-Kaup-Kupershmidt system. The two- and three-dimensional shapes of all the obtained solutions in this paper are also presented. All the computations and the graphics plots in this study are carried out with the aid of the Wolfram Mathematica 9

    Markov Properties of Electrical Discharge Current Fluctuations in Plasma

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    Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma. Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate the Kramers-Moyal's coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation. In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties compared with the observed in the experiment. We also provide an exact decomposition of temporal correlation function by using Kramers-Moyal's coefficients. We show that for the stationary time series, the two point temporal correlation function has an exponential decaying behavior with a characteristic correlation time scale. Our results confirm that, there is no definite relation between correlation and Markov time scales. However both of them behave as monotonic increasing function of discharge current intensity. Finally to complete our analysis, the multifractal behavior of reconstructed time series using its Keramers-Moyal's coefficients and original data set are investigated. Extended self similarity analysis demonstrates that fluctuations in our experimental setup deviates from Kolmogorov (K41) theory for fully developed turbulence regime.Comment: 25 pages, 9 figures and 4 tables. V3: Added comments, references, figures and major correction

    Hidden attractors in fundamental problems and engineering models

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    Recently a concept of self-excited and hidden attractors was suggested: an attractor is called a self-excited attractor if its basin of attraction overlaps with neighborhood of an equilibrium, otherwise it is called a hidden attractor. For example, hidden attractors are attractors in systems with no equilibria or with only one stable equilibrium (a special case of multistability and coexistence of attractors). While coexisting self-excited attractors can be found using the standard computational procedure, there is no standard way of predicting the existence or coexistence of hidden attractors in a system. In this plenary survey lecture the concept of self-excited and hidden attractors is discussed, and various corresponding examples of self-excited and hidden attractors are considered
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