113,893 research outputs found

    Benchmarking the performance of UK electricity distribution network operators: a study of quality, efficiency and productivity using data envelopment analysis

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    The aim of this thesis is twofold. The first is to develop a comprehensive methodology for assessing performance and then to apply it to the UK electricity distribution network operators (DNOs) to analyse the impact of the regulatory reforms and privatisation introduced in 1990-91 on their quality, efficiency and productivity developments. The models and methods developed will not only be useful in the electricity distribution context but also to other organisations that need to assess and monitor both their efficiency and quality. These objectives are realised through the use of the Data Envelopment Analysis (DEA) method, the main subject area of this thesis. This method has recently become very popular in the empirical literature due to the minimal assumptions underlying it, the case of handling multiple inputs and outputs, and its usefulness in the measurement of productivity. Performance measurement needs to keep pace with the changes in the industry. With the developments in energy and regulatory policy, and the enactment of the Utilities Act 2000, the focus of regulation has broadened from a narrow economic focus towards a wider one of protecting the interests of consumers. The latter includes not only price but also quality of service. Given this broadening focus, it is essential that performance measurement takes into account these aspects. This thesis incorporates new dimensions into efficiency and productivity measurement of electricity distribution network operators by taking into account the quality characteristics of electricity distribution operations. The dimensions of quality of service in electricity distribution were defined in this study, namely the quality of supply dimension and the quality of customer service dimension. Plausible measures of service quality were suggested. In order to provide a more balanced performance assessment, the new DEA model that incorporates the quantity as well as the quality of the services that distribution network operators provide their customers was used. In this study, only the quality of supply dimension was used in the analysis. (The quality of customer service dimension was omitted due to lack of data). Besides this, in order to achieve a more comprehensive assessment, both the operating and capital costs of distribution operations were included as inputs. The technological realities of the electricity distribution production process were captured in this study by taking into account the production trade-offs that exist between inputs and outputs. When trade-offs occur, the reduction in one factor can lead to increases in another, thereby reducing the overall reduction. The reflection of production trade-offs provides more reliable results than can be utilised in management and policy making. The production trade-offs were accounted by developing an enhanced DEA model using weight restrictions that are constructed on the basis of production trade-offs. The enhanced DEA model thus was referred to as the ‘weight-restricted’ model. This model developed was used to evaluate the DNOs efficiencies in 1999/00. A new productivity index called the ‘weight-restricted’ Malmquist productivity index was also developed in order to evaluate the quality and productivity changes of the DNOs since 1990/91. This new index is similar in spirit to the Malmquist productivity index but it reflects production trade-offs and service quality rather than just quantities per se. In this regard, the index is more appropriate to evaluate the DNOs. The index was decomposed in this study into its root components of efficiency change and technological change

    Energy Efficiency and Quality of Services in Virtualized Cloud Radio Access Network

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    Cloud Radio Access Network (C-RAN) is being widely studied for soft and green fifth generation of Long Term Evolution - Advanced (LTE-A). The recent technology advancement in network virtualization function (NFV) and software defined radio (SDR) has enabled virtualization of Baseband Units (BBU) and sharing of underlying general purpose processing (GPP) infrastructure. Also, new innovations in optical transport network (OTN) such as Dark Fiber provides low latency and high bandwidth channels that can support C-RAN for more than forty-kilometer radius. All these advancements make C-RAN feasible and practical. Several virtualization strategies and architectures are proposed for C-RAN and it has been established that C-RAN offers higher energy efficiency and better resource utilization than the current decentralized radio access network (D-RAN). This project studies proposed resource utilization strategy and device a method to calculate power utilization. Then proposes and analyzes a new resource management and virtual BBU placement strategy for C-RAN based on demand prediction and inter-BBU communication load. The new approach is compared with existing state of art strategies with same input scenarios and load. The trade-offs between energy efficiency and quality of services is discussed. The project concludes with comparison between different strategies based on complexity of the system, performance in terms of service availability and optimization efficiency in different scenarios

    Benchmarking the performance of UK electricity distribution network operators : a study of quality, efficiency and productivity using data envelopment analysis

    Get PDF
    The aim of this thesis is twofold. The first is to develop a comprehensive methodology for assessing performance and then to apply it to the UK electricity distribution network operators (DNOs) to analyse the impact of the regulatory reforms and privatisation introduced in 1990-91 on their quality, efficiency and productivity developments. The models and methods developed will not only be useful in the electricity distribution context but also to other organisations that need to assess and monitor both their efficiency and quality. These objectives are realised through the use of the Data Envelopment Analysis (DEA) method, the main subject area of this thesis. This method has recently become very popular in the empirical literature due to the minimal assumptions underlying it, the case of handling multiple inputs and outputs, and its usefulness in the measurement of productivity. Performance measurement needs to keep pace with the changes in the industry. With the developments in energy and regulatory policy, and the enactment of the Utilities Act 2000, the focus of regulation has broadened from a narrow economic focus towards a wider one of protecting the interests of consumers. The latter includes not only price but also quality of service. Given this broadening focus, it is essential that performance measurement takes into account these aspects. This thesis incorporates new dimensions into efficiency and productivity measurement of electricity distribution network operators by taking into account the quality characteristics of electricity distribution operations. The dimensions of quality of service in electricity distribution were defined in this study, namely the quality of supply dimension and the quality of customer service dimension. Plausible measures of service quality were suggested. In order to provide a more balanced performance assessment, the new DEA model that incorporates the quantity as well as the quality of the services that distribution network operators provide their customers was used. In this study, only the quality of supply dimension was used in the analysis. (The quality of customer service dimension was omitted due to lack of data). Besides this, in order to achieve a more comprehensive assessment, both the operating and capital costs of distribution operations were included as inputs. The technological realities of the electricity distribution production process were captured in this study by taking into account the production trade-offs that exist between inputs and outputs. When trade-offs occur, the reduction in one factor can lead to increases in another, thereby reducing the overall reduction. The reflection of production trade-offs provides more reliable results than can be utilised in management and policy making. The production trade-offs were accounted by developing an enhanced DEA model using weight restrictions that are constructed on the basis of production trade-offs. The enhanced DEA model thus was referred to as the ‘weight-restricted’ model. This model developed was used to evaluate the DNOs efficiencies in 1999/00. A new productivity index called the ‘weight-restricted’ Malmquist productivity index was also developed in order to evaluate the quality and productivity changes of the DNOs since 1990/91. This new index is similar in spirit to the Malmquist productivity index but it reflects production trade-offs and service quality rather than just quantities per se. In this regard, the index is more appropriate to evaluate the DNOs. The index was decomposed in this study into its root components of efficiency change and technological change.EThOS - Electronic Theses Online ServiceAssociation of Commonwealth Universities (ACU)GBUnited Kingdo

    Enhancing ecosystem services through targeted bioenergy support policies

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    © 2017 While policy-makers in the bioenergy sector have paid considerable attention over the past decade to the risks that energy cropping can pose to forests, soils and food security, there has been less focus on how bioenergy policies can be designed to enhance ecosystem services. Some perennial energy crops have demonstrated the potential to provide habitat for biodiversity, improve soil health, enhance water quality, mitigate dryland salinity and sequester carbon. While much uncertainty exists around which forms of energy cropping might deliver these benefits, opportunities exist to preferentially support beneficial energy crops through the adaptation of existing bioenergy policies. This article provides a global review of bioenergy policy instruments that identifies existing and potential mechanisms for promoting the enhancement of ecosystem services. While many existing bioenergy support policies promote fuel supply (a provisioning service) and climate change mitigation (a regulating service), it is less common for bioenergy policies to actively enhance ecosystem services such as habitat provision, soil improvement and water regulation. Further opportunities to promote these ecosystem services exist through structured tax concessions, sub-mandates, banding and renewable energy auctions, but careful consideration needs to be given to trade-offs between services, risks of disservices and the need for complementary non-energy policies

    Adaptive cooperative communications for enhancing QoS in vehicular networks

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    In a vehicular network with high mobility, it is challenging to ensure reliable and efficient connections among vehicles and between vehicles and roadside communication units (or infrastructure) such as base stations or WiFi hot spots. In this paper, we propose a method that utilizes cooperative communications for a combined vehicle-to-infrastructure (V2I) with vehicle-to-vehicle (V2V) approach to improving quality of service (QoS) across the vehicular network. In this approach, we have obtained the closed-form expressions of key QoS performances such as outage probability, throughput, energy efficiency, packet delivery ratio, packet loss rate and average end-to-end-delay for different investigated transmission schemes. These performances can be optimized by adaptively selecting appropriate transmission schemes and, as a results, good trade-offs between system reliability and efficiency can also be achieved under various environmental conditions

    Integrated Process Planning and Scheduling in Commercial Smart Kitchens

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    This paper describes the possibility of applying a generic, cloud-based Optimisation as a Service facility to food cooking planning and scheduling in a commercial kitchen. We propose a chromosome encoding and customisation of the classic MOEA/D multi-objective genetic algorithm. The applicability of the proposed approach is evaluated experimentally for two scenarios different with respect to the number of cooking appliances and the amount of the ordered food. The proposed system managed to determine the trade-offs between cooking time, energy dissipation and food quality

    An Analysis of Performance Interference Effects on Energy-Efficiency of Virtualized Cloud Environments

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    Co-allocated workloads in a virtualized computing environment often have to compete for resources, thereby suffering from performance interference. While this phenomenon has a direct impact on the Quality of Service provided to customers, it also changes the patterns of resource utilization and reduces the amount of work per Watt consumed. Unfortunately, there has been only limited research into how performance interference affects energy-efficiency of servers in such environments. In reality, there is a highly dynamic and complicated correlation among resource utilization, performance interference and energy-efficiency. This paper presents a comprehensive analysis that quantifies the negative impact of performance interference on the energy-efficiency of virtualized servers. Our analysis methodology takes into account the heterogeneous workload characteristics identified from a real Cloud environment. In particular, we investigate the impact due to different workload type combinations and develop a method for approximating the levels of performance interference and energy-efficiency degradation. The proposed method is based on profiles of pair combinations of existing workload types and the patterns derived from the analysis. Our experimental results reveal a non-linear relationship between the increase in interference and the reduction in energy-efficiency as well as an average precision within +/-5% of error margin for the estimation of both parameters. These findings provide vital information for research into dynamic trade-offs between resource utilization, performance, and energy-efficiency of a data center

    Run-time Energy Management for Mobiles

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    Due to limited energy resources, mobile computing requires an energy-efficient a rchitecture. The dynamic nature of a mobile environment demands an architecture that allows adapting to (quickly) changing conditions. The mobile has to adapt d ynamically to new circumstances in the best suitable manner. The hardware and so ftware architecture should be able to support such adaptability and minimize the energy consumption by making resource allocation decisions at run-time. To make these decisions effective, a tradeoff has to be made between computation , communication and initialization costs (both time and energy). This paper describes our approach to construct a model that supports taking such decisions

    Trade-offs and synergies in the ecosystem service demand of urban brownfield stakeholders

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    Brownfield site redevelopment presents an opportunity to create urban green spaces that provide a wide range of ecosystem services. It is important, therefore, to understand which ecosystem services are demanded by stakeholders and whether there are trade-offs or synergies in this demand. We performed a quantitative survey of ecosystem service demand from brownfield sites that included all major stakeholder groups. Results showed that there was a strong trade-off between demand for services related to property development (e.g. ground strength and low flood risk) and all other services, which were linked to vegetated sites. There was a secondary, but weak, trade-off between demand for services of more ‘natural’ vegetated sites (e.g. with a biodiversity protection role) and those linked to aesthetics and recreation. Stakeholders with a strong preference for biodiversity protection formed a distinct group in their ecosystem service demands. While a ‘development’ vs ‘green space’ trade-off may be unavoidable, the general lack of strong trade-offs in demand for other services indicated that the creation of multifunctional greenspaces from former brownfield sites would be desirable to most stakeholders, as long as these are biophysically possible
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