2,108 research outputs found

    Using real options for an eco-friendly design of water distribution systems

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    Copyright © 2015 IWA Publishing. The definitive peer-reviewed and edited version of this article is published in Journal of Hydroinformatics volume 17 (1), pp. 20-35 (2015), DOI 10.2166/hydro.2014.122 and is available at www.iwapublishing.com.This paper presents a real options approach to handling uncertainties associated with the long-term planning of water distribution system development. Furthermore, carbon emissions associated with the installation and operation of water distribution networks are considered. These emissions are computed by taking an embodied energy approach to the different materials used in water networks. A simulated annealing heuristic is used to optimise a flexible eco-friendly design of water distribution systems for an extended life horizon. This time horizon is subdivided into different time intervals in which different possible decision paths can be followed. The proposed approach is applied to a case study and the results are presented according to a decision tree. Lastly, some comparisons and results are used to demonstrate the quality of the results of this approach.Programa Operacional Factores de Competitividade – COMPETEFCT – Fundação para a Ciência e Tecnologi

    Estimating the value of service exports by destination from different parts of Great Britain: 2015

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    This is the first time we are publishing service export figures by country of destination for countries, regions and industries in Great Britain; our analysis includes around 45% of total service exports and excludes finance, travel and transport because of data limitations. London dominated the absolute value of service exports to the EU, contributing 42% of the total EU exports (around £15.6 billion) in 2015. The EU market was more significant for service exports from the North East and West Midlands compared with London and the North West. In the North East, half of total service exports went to the EU, whereas this figure is only one-quarter for the North West. Real estate, professional, scientific and technical industries were the largest exporters of services, followed by information and communication industries, then services connected to manufacturing, generating 35%, 29% and 15% of the total service exports respectively. Of all Great Britain service exports in 2015, 10% went to the Commonwealth (around £9.8 billion), and London generated almost half of those exports (around £4.6 billion). Of Asian markets, Japan was the single largest destination for service exports from London and the East (receiving about £0.8 billion and £0.2 billion respectively), while the single largest Asian destination from Yorkshire and The Humber, Wales and the South West was Saudi Arabia

    Decision support for optimal design of water distribution networks: A real options approach

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    12th International Conference on Computing and Control for the Water Industry, CCWI2013There is a growing concern about how the technical, managerial and financial capacity of drinking water systems can be sustained in the long run with future uncertainties. A water supply system is critical for the well- being of a community and it must provide water in sufficient quantity, of appropriate quality and without interruption. People have high expectations for the proper functioning of these systems but the future is uncertain and it is very difficult to conceive an infallible infrastructure. This work proposes a real options (ROs) approach that takes into account future uncertainty associated with water distribution networks. The ROs methodology extends traditional analysis to include flexible strategic implementation. This work describes a decision support methodology to design water networks that are adaptable over a long-term planning horizon. Representing design strategies as decision trees allows decision makers to easily adapt the system according to future circumstances. Results show that the ROs solution makes it possible to save on resources through an analysis based on an extended and uncertain planning horizonPrograma Operacional Factores de Competitividade – COMPETEFCT – Fundação para a Ciência e Tecnologi

    Radiation hardness of small-pitch 3D pixel sensors up to HL-LHC fluences

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    A new generation of 3D silicon pixel detectors with a small pixel size of 50×\times50 and 25×\times100 μ\mum2^{2} is being developed for the HL-LHC tracker upgrades. The radiation hardness of such detectors was studied in beam tests after irradiation to HL-LHC fluences up to 1.4×10161.4\times10^{16} neq_{\mathrm{eq}}/cm2^2. At this fluence, an operation voltage of only 100 V is needed to achieve 97% hit efficiency, with a power dissipation of 13 mW/cm2^2 at -25^{\circ}C, considerably lower than for previous 3D sensor generations and planar sensors.Comment: 5 pages, 2 figures, Proceedings of TIPP 2017, Beijing (International Conference on The Technology and Instrumentation in Particle Physics 2017

    A Dynamic Adaptive Approach for Water Distribution Network Design

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    This is the author accepted manuscript. The final version is available from American Society of Civil Engineers via the DOI in this record In the face of a highly uncertain future, there is a need for water utilities to develop structured approaches for the long-term strategic design of water distribution networks (WDNs). A new conceptual framework for developing an integrative approach based on a multicriteria decision analysis (MCDA), embracing an optimization model to size flexible alternatives, is proposed. The flexible solutions are evaluated through MCDA for all the criteria (investment costs, carbon emissions, resilience, and reliability of WDNs) across all the scenarios generated for the sake of robustness and will help to adapt WDNs to changing conditions over a long planning horizon, divided into phases. The alternatives are ranked through two different MCDA methods, Preference Ranking Organization METHod for Enrichment of Evaluations (PROMETHEE) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), so that decision makers will have more comprehensive information for analyzing highly ranked design solutions and after the first phase, solutions for the other phases can be reassessed by the same dynamic adaptive framework

    Explicit expressions for state estimation sensitivity analysis in water systems

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The implementation of state estimation techniques to water systems enables the hydraulic state of a given network to be computed at any time. However, errors in both measurements and model parameters can severely affect the quality of the state estimate, thus sensitivity analysis is crucial to assess its performance. The aim of this paper is to provide general explicit expressions for the sensitivities of the objective function and the primal variables of the state estimation problem with respect to both measurements and roughness parameters based on the perturbation of the Karush-Kuhn-Tucker (KKT) conditions. Additionally, among all the possible applications of sensitivity analysis, two specific forms of such analysis for water systems are presented: identifiability of roughness parameters, and linear state estimate approximation. The merit of these applications is illustrated by means of a case study, which highlights the usefulness of compact sensitivity formulae to further understanding of state estimation solutions

    On the coherence/incoherence of electron transport in semiconductor heterostructure optoelectronic devices

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    This paper compares and contrasts different theoretical approaches based on incoherent electron scattering transport with experimental measurements of optoelectronic devices formed from semiconductor heterostructures. The Monte Carlo method which makes no a priori assumptions about the carrier distribution in momentum or phase space is compared with less computationally demanding energy-balance rate equation models which assume thermalised carrier distributions. It is shown that the two approaches produce qualitatively similar results for hole transport in p-type Si1-xGex/Si superlattices designed for terahertz emission. The good agreement of the predictions of rate equation calculations with experimental measurements of mid- and far-infrared quantum cascade lasers, quantum well infrared photodetectors and quantum dot infrared photodetectors substantiate the assumption of incoherent scattering dominating the transport in these quantum well based devices. However, the paper goes on to consider the possibility of coherent transport through the density matrix method and suggests an experiment that could allow coherent and incoherent transport to be distinguished from each other

    Exploring the value of defence jobs in the UK

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