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Scotland and regime change : strategic security and the revolution of 1688-1690
No full textIn recent years there has been a fundamental reappraisal of the so-called 'Glorious Revolution' in the British Isles, mainly through the work of Tim Harris and Steve Pincus. Cultural aspects of the impact of the Dutch in English society after the Revolution have also been explored in the work of Lisa Jardine. Scotland has certainly been included in the work of Harris and Pincus, but there is still a need to reappraise the Revolution in Scotland. This MRes will focus on the theme of regime change and strategic security as the new Williamite regime in Scotland dealt with the issues of an internal Jacobite rising, the external threat of a Franco-Irish invasion of Scotland, and the wider context of the Nine Years' War (1688-97) in continental Europe. Thus, Scotland needs to be regarded as part of that wider European conflict. Conceptually, this will be approached via the prism of state development, absolutism and international relations in continental Europe, as well as via the Pocockian model of the Second War of the Three Kingdoms (1688-91).In recent years there has been a fundamental reappraisal of the so-called 'Glorious Revolution' in the British Isles, mainly through the work of Tim Harris and Steve Pincus. Cultural aspects of the impact of the Dutch in English society after the Revolution have also been explored in the work of Lisa Jardine. Scotland has certainly been included in the work of Harris and Pincus, but there is still a need to reappraise the Revolution in Scotland. This MRes will focus on the theme of regime change and strategic security as the new Williamite regime in Scotland dealt with the issues of an internal Jacobite rising, the external threat of a Franco-Irish invasion of Scotland, and the wider context of the Nine Years' War (1688-97) in continental Europe. Thus, Scotland needs to be regarded as part of that wider European conflict. Conceptually, this will be approached via the prism of state development, absolutism and international relations in continental Europe, as well as via the Pocockian model of the Second War of the Three Kingdoms (1688-91)
Mathematical aggregation of probabilistic expert judgements
Get PDFPreviously held under moratorium from 21st November 2017 until 21st November 2022.Mathematical aggregation of the probabilistic expert’s judgements in a structured expertjudgement analysis is said to be relevant and critical. Due to absence of data, the judgementsof the experts are used to perform forecasting and risk analysis. However, there is a gapin the literature where there may exist correlation in such judgements. This research isconcerned with the situation where multiple experts are providing their numerical probabilityassessment for multiple quantities of interest. For each quantity of interest, there is a needof linear optimal weight on the basis of the experts’ judgement. This optimality is achievedby minimising the mean squared error (MSE) between the unbiased judgements provided bythe experts for a quantity of interest, whose true value is unknown. Further, it has beenassumed that the judgements of the experts is dependent on the sets of multiple quantitiesof interests, while, their errors presented in the judgements are correlated. This thesispresents two novel mathematical methods towards aggregating expert’s judgement throughlinear pooling. The first method is based on the empirical Bayes parametric formulation,and the second method is non-parametric. Both the chosen methods are compared usinga stimulation study. This is to examine the performance of a given dependency structurewhich is further illustrated using a case study. In this context, a highly positive correlatedexpert gets the least weight when compared to an independent or negatively correlatedexperts. As stated in literature and reaffirmed through the simulation studies in this thesis,asymptotically the non-parametric approach has a slower error rate convergence, wherethe error is defined in terms of the MSE in comparison to the parametric empirical Bayesmethod. Based on the simulation study and the case study results, it is found that theempirical Bayes method outperforms the non-parametric method.Mathematical aggregation of the probabilistic expert’s judgements in a structured expertjudgement analysis is said to be relevant and critical. Due to absence of data, the judgementsof the experts are used to perform forecasting and risk analysis. However, there is a gapin the literature where there may exist correlation in such judgements. This research isconcerned with the situation where multiple experts are providing their numerical probabilityassessment for multiple quantities of interest. For each quantity of interest, there is a needof linear optimal weight on the basis of the experts’ judgement. This optimality is achievedby minimising the mean squared error (MSE) between the unbiased judgements provided bythe experts for a quantity of interest, whose true value is unknown. Further, it has beenassumed that the judgements of the experts is dependent on the sets of multiple quantitiesof interests, while, their errors presented in the judgements are correlated. This thesispresents two novel mathematical methods towards aggregating expert’s judgement throughlinear pooling. The first method is based on the empirical Bayes parametric formulation,and the second method is non-parametric. Both the chosen methods are compared usinga stimulation study. This is to examine the performance of a given dependency structurewhich is further illustrated using a case study. In this context, a highly positive correlatedexpert gets the least weight when compared to an independent or negatively correlatedexperts. As stated in literature and reaffirmed through the simulation studies in this thesis,asymptotically the non-parametric approach has a slower error rate convergence, wherethe error is defined in terms of the MSE in comparison to the parametric empirical Bayesmethod. Based on the simulation study and the case study results, it is found that theempirical Bayes method outperforms the non-parametric method
Faults as episodic conduits for hydrocarbons, CO2 and groundwater in sandstones
Get PDFConstraining the dynamic feedback between deforming porous media and fluid is crucial for understanding hydrocarbon reservoirs, CO2 storage sites and other evolving porous media. In particular, predicting complex fault architecture at depth, currently relies on deterministic algorithms, that do not take account of these dynamic coupling. For instance, creation of permeability due to fracturing may permit fluid flow to enter a fault zone, resulting in cementation (strengthening) or alteration (weakening) of the fault and host rocks.;The resulting changes in rock strength may enhance or retard further fracturing and may even result in a switch of deformation mechanism.;Temporal and spatial evolution of fluid flow through faulted porous rocks has been studied in a field site in SE Utah, USA. The field area presents a well-exposed fault system that contains evidence for flow of multiple phases of groundwater with varying chemistries and flow of hydrocarbons. By detailed field mapping and microstructural observations of the fault rocks and of the evidence for fluid flow (e.g. bleaching and hydrocarbon staining) the fluid flow history and evolving flow properties of the rocks has been unravelled.;The 6km long fault presents an erosional scarp of up to 20m high at its centre. This scarp is dissected with canyons that permit cross-sectional views of the fault and associated alteration which has been mapped. The field area contains two general classes of lithology. In porous sandstones, deformation is accommodated by deformation bands and fractures. In tight limestones and siltstones deformation is accommodated by fracturing and the formation of clay-rich fault rocks. Evidence for multiple fluid flow events can be observed.;Hydrocarbon staining is confined to the coarsest grained layers in the sandstones, and to fractures in all lithologies. Bleaching surrounds fractures in the fault damage zone and along bedding in the fault zone.;This thesis presents evidence for a reduction in porosity due to increased burial and cementation to be the biggest influence on deformation mechanisms for fault growth and evolution. Evidence of the evolving structural and hydrogeological properties of the fault zone are explored. This thesis discusses how such data can be used to improve the predictive capability of fault zone properties at depth where the faults have accommodated post-faulting fluid flow.Constraining the dynamic feedback between deforming porous media and fluid is crucial for understanding hydrocarbon reservoirs, CO2 storage sites and other evolving porous media. In particular, predicting complex fault architecture at depth, currently relies on deterministic algorithms, that do not take account of these dynamic coupling. For instance, creation of permeability due to fracturing may permit fluid flow to enter a fault zone, resulting in cementation (strengthening) or alteration (weakening) of the fault and host rocks.;The resulting changes in rock strength may enhance or retard further fracturing and may even result in a switch of deformation mechanism.;Temporal and spatial evolution of fluid flow through faulted porous rocks has been studied in a field site in SE Utah, USA. The field area presents a well-exposed fault system that contains evidence for flow of multiple phases of groundwater with varying chemistries and flow of hydrocarbons. By detailed field mapping and microstructural observations of the fault rocks and of the evidence for fluid flow (e.g. bleaching and hydrocarbon staining) the fluid flow history and evolving flow properties of the rocks has been unravelled.;The 6km long fault presents an erosional scarp of up to 20m high at its centre. This scarp is dissected with canyons that permit cross-sectional views of the fault and associated alteration which has been mapped. The field area contains two general classes of lithology. In porous sandstones, deformation is accommodated by deformation bands and fractures. In tight limestones and siltstones deformation is accommodated by fracturing and the formation of clay-rich fault rocks. Evidence for multiple fluid flow events can be observed.;Hydrocarbon staining is confined to the coarsest grained layers in the sandstones, and to fractures in all lithologies. Bleaching surrounds fractures in the fault damage zone and along bedding in the fault zone.;This thesis presents evidence for a reduction in porosity due to increased burial and cementation to be the biggest influence on deformation mechanisms for fault growth and evolution. Evidence of the evolving structural and hydrogeological properties of the fault zone are explored. This thesis discusses how such data can be used to improve the predictive capability of fault zone properties at depth where the faults have accommodated post-faulting fluid flow
The effect of weather and climate change on the operation of meshed power networks
Get PDFWeather outages affect power systems all over the world. In January 1998 Canada experienced the 'Great Ice Strom' which hit an area spanning from Eastern Ontario to Southern Quebec. 15 years later, it experienced another ice storm which left 600,000 people without power at the peak. Wind storms can also cause severe damage to power systems such as wind storms Lothar and Martin that hit France in December 1999. Due to never experiencing winds this high, nearly 3.4 million homes were left without power for up to 17 days. In the future outage rates may increase but we are unaware of what the current effects are, for example is there is any relationship between durations and the intensity of the weather or what the probabilities of these events causing an outage are. However, the weather experienced by each country, even areas within a country can vary. This thesis will present a five stage methodology that was developed for the analysis of both the current effects of weather on power transmission systems and also, the future effects. It also applied this methodology to the GB transmission network as a test case to identify the outcomes interms of network reliability to possible changes in climate. To complete this analysis outage datasets, provided by the transmission companies of GB, were acquired to help understand what the current effects of weather are. It was determined that the three main weather types that cause weather related outages on the GB transmission network were, Lightning, Snow, Sleet, Blizzards & Ice and Wind, Gales and Windborne Objects'. It also compared observational weather data to reanalysis data and lightning strike data and a lightning strike proxy to verify reanalysis data as a suitable replicator of past weather data. A correlation analysis between weather variables and weather related outages was completed to identify the weather indicator for the associated outage. From this fragility curves of failure rates for the dominant weather-related outages based on the weather that is occurring were developed. Using climate projections seven weather test cases were developed for the state sampling model and eight for the sequential simulation. In each case a different weather variable was changed to understand the effect they will have. It was concluded there are varying levels of confidence in climate change predictions making it difficult to assess the risk that poses to transmission networks. Reanalysis was found to be an acceptable replication of past observation data and CAPE was determined as a good proxy for lightning strikes. It was found there was an overall increase in failure rates and that there was an increase in all system indices, suggesting there would be increases in the magnitude and number of load shedding events.Weather outages affect power systems all over the world. In January 1998 Canada experienced the 'Great Ice Strom' which hit an area spanning from Eastern Ontario to Southern Quebec. 15 years later, it experienced another ice storm which left 600,000 people without power at the peak. Wind storms can also cause severe damage to power systems such as wind storms Lothar and Martin that hit France in December 1999. Due to never experiencing winds this high, nearly 3.4 million homes were left without power for up to 17 days. In the future outage rates may increase but we are unaware of what the current effects are, for example is there is any relationship between durations and the intensity of the weather or what the probabilities of these events causing an outage are. However, the weather experienced by each country, even areas within a country can vary. This thesis will present a five stage methodology that was developed for the analysis of both the current effects of weather on power transmission systems and also, the future effects. It also applied this methodology to the GB transmission network as a test case to identify the outcomes interms of network reliability to possible changes in climate. To complete this analysis outage datasets, provided by the transmission companies of GB, were acquired to help understand what the current effects of weather are. It was determined that the three main weather types that cause weather related outages on the GB transmission network were, Lightning, Snow, Sleet, Blizzards & Ice and Wind, Gales and Windborne Objects'. It also compared observational weather data to reanalysis data and lightning strike data and a lightning strike proxy to verify reanalysis data as a suitable replicator of past weather data. A correlation analysis between weather variables and weather related outages was completed to identify the weather indicator for the associated outage. From this fragility curves of failure rates for the dominant weather-related outages based on the weather that is occurring were developed. Using climate projections seven weather test cases were developed for the state sampling model and eight for the sequential simulation. In each case a different weather variable was changed to understand the effect they will have. It was concluded there are varying levels of confidence in climate change predictions making it difficult to assess the risk that poses to transmission networks. Reanalysis was found to be an acceptable replication of past observation data and CAPE was determined as a good proxy for lightning strikes. It was found there was an overall increase in failure rates and that there was an increase in all system indices, suggesting there would be increases in the magnitude and number of load shedding events
Development and control of pharmaceutical solids using extrusion and granulation
Get PDFNowadays, the pharmaceutical industry is seeking manufacturing processes that enable the delivery of high quality medicines with less cost and delivery time. The introduction of flexible manufacturing equipment such as twin-screw equipment can be used for these purposes and be part of a continuous manufacturing platform. Hot-Melt Extrusion (HME) and Twin-Screw Granulation (TSG) are two applications that can be used with the same processing equipment and reduce the number of stages involved in the manufacturing process. In this thesis the use of HME to produce amorphous solid dispersions of the poorly water soluble drug albendazole is investigated. HME enabled the transformation of the drug solid state from crystalline to amorphous by optimised processing parameters and the use of two suitable hydrophilic polymers as carriers. Amorphous solid dispersions showed an increase of albendazole dissolution properties. Differences in drug release rate indicated possible molecular interactions between the drug molecule and one of the polymers studied. Further studies are required to investigate the type of possible interactions. Computed tomography was used to determine the density differences and the internal structure properties of the extruded materials. This thesis studied the impact of screw element design, processing parameters and mechanism behind granule formation in twin-screw wet granulation. The use of conveying elements only achieved a poor liquid distribution due to the low shear applied. Combined screw configurations of mixing and conveying elements resulted in better liquid distribution properties. Excess of fines production was attributed to a breakage mechanism caused by the use of the distributive feed screw. These results can contribute towards the design of space of TSG processes. Overall, this thesis showed that the optimisation of processing parameters in HME and TSG can lead to the enhancement of product properties which would be beneficial for continuous manufacturing platforms.Nowadays, the pharmaceutical industry is seeking manufacturing processes that enable the delivery of high quality medicines with less cost and delivery time. The introduction of flexible manufacturing equipment such as twin-screw equipment can be used for these purposes and be part of a continuous manufacturing platform. Hot-Melt Extrusion (HME) and Twin-Screw Granulation (TSG) are two applications that can be used with the same processing equipment and reduce the number of stages involved in the manufacturing process. In this thesis the use of HME to produce amorphous solid dispersions of the poorly water soluble drug albendazole is investigated. HME enabled the transformation of the drug solid state from crystalline to amorphous by optimised processing parameters and the use of two suitable hydrophilic polymers as carriers. Amorphous solid dispersions showed an increase of albendazole dissolution properties. Differences in drug release rate indicated possible molecular interactions between the drug molecule and one of the polymers studied. Further studies are required to investigate the type of possible interactions. Computed tomography was used to determine the density differences and the internal structure properties of the extruded materials. This thesis studied the impact of screw element design, processing parameters and mechanism behind granule formation in twin-screw wet granulation. The use of conveying elements only achieved a poor liquid distribution due to the low shear applied. Combined screw configurations of mixing and conveying elements resulted in better liquid distribution properties. Excess of fines production was attributed to a breakage mechanism caused by the use of the distributive feed screw. These results can contribute towards the design of space of TSG processes. Overall, this thesis showed that the optimisation of processing parameters in HME and TSG can lead to the enhancement of product properties which would be beneficial for continuous manufacturing platforms
Bifibrational parametricity : from zero to two dimensions
Get PDFIn this thesis we use bifibrations in order to study relational parametricity. There are three main contributions in this thesis. First, through the lenses of bifibrations, we give a new framework for models of parametricity. This allows us to make some of the underlying categorical structure in Reynolds' original work clearer. Using the same approach we then give a universal property for the interpretation of forall types: they are characterized as terminal objects in a certain category. The universal property permits us to prove both Reynolds' Identity Extension Lemma and Abstraction Theorem. The third contribution consists in defining two-dimensional parametricity. The insight derived from the bifibrational approach leads to a generalization of parametricity to proof relevant relations, incorporating higher-dimensional relations between relations. We call the resulting theory two-dimensional parametricity.In this thesis we use bifibrations in order to study relational parametricity. There are three main contributions in this thesis. First, through the lenses of bifibrations, we give a new framework for models of parametricity. This allows us to make some of the underlying categorical structure in Reynolds' original work clearer. Using the same approach we then give a universal property for the interpretation of forall types: they are characterized as terminal objects in a certain category. The universal property permits us to prove both Reynolds' Identity Extension Lemma and Abstraction Theorem. The third contribution consists in defining two-dimensional parametricity. The insight derived from the bifibrational approach leads to a generalization of parametricity to proof relevant relations, incorporating higher-dimensional relations between relations. We call the resulting theory two-dimensional parametricity
Household and skill disaggregation in multi-sectoral models of the Scottish economy
Get PDFThis thesis constructs and applies multi-sectoral models that can be used by policy makers to assess potential system-wide impacts and trade-offs of policies set out in Scotland's Economic Strategywith particular focus on analysing the skill-dimension.This thesis begins by building a Social Accounting Matrix (SAM) for Scotland and then disaggregates this by educational characteristics of the Scottish workforce. This forms the foundation upon which subsequent modelling frameworks are developed. Next, the SAM is used to compare methods for calculating Input-Output Type II multipliers. Significant differences across these methods do not appear to be explicitly acknowledged or understood in the current literature.The potential distributional effects of exogenous demand shocks within the Scottish economy are analysed using a SAM model that contains disaggregated household accounts and two types of labour. The SAM is also used to identify the skill intensity of key structural component of the Scottish economy.The SAM is then applied to calibrate an extended version of the AMOS Computable General Equilibrium(CGE) model. This model is subsequently employed to analyse the system-wide impacts of policy relevant shocks. A variety of export demand shocks are modelled to identify the likely impacts of export orientated policies. This facilitates the separate identification of disparate labour market impacts, whilst also detailing policy relevant system-wide effects in a multi sectoral modelling framework. The skill intensity of exports, as also assessed in the SAM model, is revisited in a CGE modelling context.A key policy in the Economic Strategy is 'to make better use of skills in the workplace'. This is interpreted as a labour augmenting efficiency improvement where fewer workers are required to produce the same level of output. Given the importance of the skill dimension alternative cases of labour-augmenting efficiency improvements are explored within the skill-disaggregated AMOS model.This thesis constructs and applies multi-sectoral models that can be used by policy makers to assess potential system-wide impacts and trade-offs of policies set out in Scotland's Economic Strategywith particular focus on analysing the skill-dimension.This thesis begins by building a Social Accounting Matrix (SAM) for Scotland and then disaggregates this by educational characteristics of the Scottish workforce. This forms the foundation upon which subsequent modelling frameworks are developed. Next, the SAM is used to compare methods for calculating Input-Output Type II multipliers. Significant differences across these methods do not appear to be explicitly acknowledged or understood in the current literature.The potential distributional effects of exogenous demand shocks within the Scottish economy are analysed using a SAM model that contains disaggregated household accounts and two types of labour. The SAM is also used to identify the skill intensity of key structural component of the Scottish economy.The SAM is then applied to calibrate an extended version of the AMOS Computable General Equilibrium(CGE) model. This model is subsequently employed to analyse the system-wide impacts of policy relevant shocks. A variety of export demand shocks are modelled to identify the likely impacts of export orientated policies. This facilitates the separate identification of disparate labour market impacts, whilst also detailing policy relevant system-wide effects in a multi sectoral modelling framework. The skill intensity of exports, as also assessed in the SAM model, is revisited in a CGE modelling context.A key policy in the Economic Strategy is 'to make better use of skills in the workplace'. This is interpreted as a labour augmenting efficiency improvement where fewer workers are required to produce the same level of output. Given the importance of the skill dimension alternative cases of labour-augmenting efficiency improvements are explored within the skill-disaggregated AMOS model
An investigation into the characteristics and optimisation of a high-pressure common rail injection system
Get PDFThe primary aim of this research was to predict the emissions and fuel savings when replacing a mechanical fuel oil injection system with a high pressure common rail one. The work in this study consists of two parts. In the first part, a novel routine is proposed for the optimisation of electronic fuel injectors and their dynamic response, including the needle valve opening delay and the needle valve closing delay (The needle valve opening delay refers to the delay between the control signal being trigged and the needle valve being fully open; the needle valve closing delay refers to the delay between the control signal deactivating and the needle valve being fully closed).;Two injectors (Type-I and Type-II) were included; their one-dimensional (1D) models were built in AMESim software and validated respectively.;A parametric study on the Type-I fuel injector was conducted before the optimisation process in order to examine the effects of various parameters including the control piston diameter (CPD), control oil (i.e. the fuel oil used for control in a typical solenoid electronic fuel injector) inlet passage diameter (IPD) and control oil outlet passage diameter (OPD) on injection characteristics, i.e. injection rate, injection mass, needle valve lift and control chamber pressure.;Then, the optimisation of the injector dynamic response was investigated by the proposed routine in modeFRONTIER software. In detail, the routine included the following steps: First, a random sequence was adopted in the design of experiment (DOE) type. Then, an NSGA-II (Non-dominated Sorting Genetic Algorithm II) algorithm was selected. Next, a whole electronic fuel injector model was chosen, where the displacements of the needle valve were generated.;These data were first written into an input file, and to do this, appropriate writing and reading rules needed to be developed. The text file was read by the MATLAB code, where the control signal and needle valve displacement timings were calculated. The valve opening delay and the valve closing delay were thus obtained from these timings. Additionally, a constraint was set between the control oil inlet passage diameter and control oil outlet passage diameter in that the former should be smaller than the latter in each run.;The CPD, OPD and IPD were the three design parameters to be varied in the optimisation process of the Type-I fuel injector at a specific rail pressure. However, three more design parameters (the spring preload force (SPF), nozzle orifice number (NZN) and nozzle orifice diameter (NZD)) were involved in the optimisation process of the Type-II fuel injector under three different rail pressures (80 MPa, 120 MPa and 160 MPa).;The optimal design with the best trade-off between the valve opening delay and the valve closing delay of each fuel injector was singled out via a scattering chart. Results show that the optimum Type-I fuel injector achieved reductions of 40% and 25% of the baseline design on the valve opening delay and valve closing delay respectively. The optimal design of the Type-II fuel injector also achieved a huge reduction at all three rail pressures.;Specifically, the valve opening delay was reduced by 29.8%, 29.2% and 20.9%, and the valve closing delay was reduced by 25.6%, 24.5% and 30.1% at 80 MPa, 120 MPa and 160 MPa rail pressures respectively. RSM (response surface method) contour maps were used to study the interactions between design parameters. Results indicated that the CPD, IPD and OPD and their interactions are influential design parameters for the valve opening delay, while the IPD has a dominant effect on the valve closing delay.;. A large CPD together with a large IPD was found to increase the valve opening delay dramatically. Surprisingly, the effects of the spring preload force (SPF) on the valve closing delay are noticeable at low rail pressures. The valve closing delay decreases with an increase in the spring preload force. The feasibility and efficiency of the proposed routine was validated both on the Type-I fuel injector and the Type-II fuel injector. It was not only achieved great reductions on both the valve opening delay and the valve closing delay, but was also able to comprehensively disclose the effects and interactions of the design parameters on the injector dynamic response.;In the second part, Type-II fuel injector matches with the combustion chamber of a medium-speed marine diesel engine was conducted by a CFD model of the medium-speed marine diesel engine built in AVL FIRE software. The model was validated by using the cylinder pressures, rate of heat release (ROHR) and NOx emissions under four engine loads, i.e. L25 (25%), L50 (50%), L75 (75%) and L100 (100%) loads.;Seven engine design parameters, including four injection-related parameters (spray angle, nozzle protrusion length, injection timing and swirl ratio) and three combustion chamber geometry parameters (bowl diameter, centre crown height and toroidal radius), were examined by a parametric study and a multi-objective optimisation.;The parametric study was carried out to discover the sensitivity of design parameters on the objectives (nitrogen oxides (NOx) emissions, soot emissions and specific fuel oil consumption (SFOC)). In it, each engine design parameter was investigated independently under three engine loads (25% engine load was excluded due to the fact that it is very unstable operating condition). Results showed that the injection-related parameters were found to have much more influence than the combustion chamber geometries. In addition, the injection timing, one of the injection-related parameters, has the largest influence on the objectives.;In the optimisation study, two algorithms (the nonlinear programming by quadratic Lagrangian (NLPQL) algorithm and multi-objective genetic algorithm (MOGA)) were used in two stages, initially separately and then sequentially, for the first time in the engine optimisation domain. This study aims to reduce the NOx emission, soot emissions as well as to improve fuel economy. Detailed comparisons were made for NOx emissions, soot emissions and SFOC as well as the design parameters.;The optimisation study showed that the NLPQL algorithm failed to obtain optimal designs whilst the MOGA offered more feasible Pareto designs. Since the NLPQL algorithm is a local optimisation method, and as a result it is affected by the selection of appropriate initial conditions. The optimal design with the best trade-off between NOx and soot emissions obtained by the MOGA was set as the starting point of the NLPQL algorithm. In this case, a better design with lower NOx emissions and soot emissions was obtained.;The combustion processes of these optimal designs were also analysed and compared in detail. Late injection and small swirl ratio were reckoned to be the main reasons for reducing NOx emissions. In the end, contour maps generated by response surface method (RSM) were applied in order to gain a better understanding of the interaction and sensitivity of the design parameters on NOx emissions, soot emissions and SFOC.;Results indicated that NOx emissions and soot emissions can be greatly reduced by adopting a late injection, a low swirl and a large spray angle, but fuel economy was sacrificed.The primary aim of this research was to predict the emissions and fuel savings when replacing a mechanical fuel oil injection system with a high pressure common rail one. The work in this study consists of two parts. In the first part, a novel routine is proposed for the optimisation of electronic fuel injectors and their dynamic response, including the needle valve opening delay and the needle valve closing delay (The needle valve opening delay refers to the delay between the control signal being trigged and the needle valve being fully open; the needle valve closing delay refers to the delay between the control signal deactivating and the needle valve being fully closed).;Two injectors (Type-I and Type-II) were included; their one-dimensional (1D) models were built in AMESim software and validated respectively.;A parametric study on the Type-I fuel injector was conducted before the optimisation process in order to examine the effects of various parameters including the control piston diameter (CPD), control oil (i.e. the fuel oil used for control in a typical solenoid electronic fuel injector) inlet passage diameter (IPD) and control oil outlet passage diameter (OPD) on injection characteristics, i.e. injection rate, injection mass, needle valve lift and control chamber pressure.;Then, the optimisation of the injector dynamic response was investigated by the proposed routine in modeFRONTIER software. In detail, the routine included the following steps: First, a random sequence was adopted in the design of experiment (DOE) type. Then, an NSGA-II (Non-dominated Sorting Genetic Algorithm II) algorithm was selected. Next, a whole electronic fuel injector model was chosen, where the displacements of the needle valve were generated.;These data were first written into an input file, and to do this, appropriate writing and reading rules needed to be developed. The text file was read by the MATLAB code, where the control signal and needle valve displacement timings were calculated. The valve opening delay and the valve closing delay were thus obtained from these timings. Additionally, a constraint was set between the control oil inlet passage diameter and control oil outlet passage diameter in that the former should be smaller than the latter in each run.;The CPD, OPD and IPD were the three design parameters to be varied in the optimisation process of the Type-I fuel injector at a specific rail pressure. However, three more design parameters (the spring preload force (SPF), nozzle orifice number (NZN) and nozzle orifice diameter (NZD)) were involved in the optimisation process of the Type-II fuel injector under three different rail pressures (80 MPa, 120 MPa and 160 MPa).;The optimal design with the best trade-off between the valve opening delay and the valve closing delay of each fuel injector was singled out via a scattering chart. Results show that the optimum Type-I fuel injector achieved reductions of 40% and 25% of the baseline design on the valve opening delay and valve closing delay respectively. The optimal design of the Type-II fuel injector also achieved a huge reduction at all three rail pressures.;Specifically, the valve opening delay was reduced by 29.8%, 29.2% and 20.9%, and the valve closing delay was reduced by 25.6%, 24.5% and 30.1% at 80 MPa, 120 MPa and 160 MPa rail pressures respectively. RSM (response surface method) contour maps were used to study the interactions between design parameters. Results indicated that the CPD, IPD and OPD and their interactions are influential design parameters for the valve opening delay, while the IPD has a dominant effect on the valve closing delay.;. A large CPD together with a large IPD was found to increase the valve opening delay dramatically. Surprisingly, the effects of the spring preload force (SPF) on the valve closing delay are noticeable at low rail pressures. The valve closing delay decreases with an increase in the spring preload force. The feasibility and efficiency of the proposed routine was validated both on the Type-I fuel injector and the Type-II fuel injector. It was not only achieved great reductions on both the valve opening delay and the valve closing delay, but was also able to comprehensively disclose the effects and interactions of the design parameters on the injector dynamic response.;In the second part, Type-II fuel injector matches with the combustion chamber of a medium-speed marine diesel engine was conducted by a CFD model of the medium-speed marine diesel engine built in AVL FIRE software. The model was validated by using the cylinder pressures, rate of heat release (ROHR) and NOx emissions under four engine loads, i.e. L25 (25%), L50 (50%), L75 (75%) and L100 (100%) loads.;Seven engine design parameters, including four injection-related parameters (spray angle, nozzle protrusion length, injection timing and swirl ratio) and three combustion chamber geometry parameters (bowl diameter, centre crown height and toroidal radius), were examined by a parametric study and a multi-objective optimisation.;The parametric study was carried out to discover the sensitivity of design parameters on the objectives (nitrogen oxides (NOx) emissions, soot emissions and specific fuel oil consumption (SFOC)). In it, each engine design parameter was investigated independently under three engine loads (25% engine load was excluded due to the fact that it is very unstable operating condition). Results showed that the injection-related parameters were found to have much more influence than the combustion chamber geometries. In addition, the injection timing, one of the injection-related parameters, has the largest influence on the objectives.;In the optimisation study, two algorithms (the nonlinear programming by quadratic Lagrangian (NLPQL) algorithm and multi-objective genetic algorithm (MOGA)) were used in two stages, initially separately and then sequentially, for the first time in the engine optimisation domain. This study aims to reduce the NOx emission, soot emissions as well as to improve fuel economy. Detailed comparisons were made for NOx emissions, soot emissions and SFOC as well as the design parameters.;The optimisation study showed that the NLPQL algorithm failed to obtain optimal designs whilst the MOGA offered more feasible Pareto designs. Since the NLPQL algorithm is a local optimisation method, and as a result it is affected by the selection of appropriate initial conditions. The optimal design with the best trade-off between NOx and soot emissions obtained by the MOGA was set as the starting point of the NLPQL algorithm. In this case, a better design with lower NOx emissions and soot emissions was obtained.;The combustion processes of these optimal designs were also analysed and compared in detail. Late injection and small swirl ratio were reckoned to be the main reasons for reducing NOx emissions. In the end, contour maps generated by response surface method (RSM) were applied in order to gain a better understanding of the interaction and sensitivity of the design parameters on NOx emissions, soot emissions and SFOC.;Results indicated that NOx emissions and soot emissions can be greatly reduced by adopting a late injection, a low swirl and a large spray angle, but fuel economy was sacrificed
Distributed sensing for MIMO radar systems
Get PDFThe research presented in this thesis deals with the concepts of distributed sensing for multiple-input multiple-output (MIMO) radar systems and important signal processing algorithms with regard to multiple sensing optimisations. These novel algorithms include an edge detection scheme based on the phase stretch transform (PST) for synthetic aperture radar (SAR) imaging systems, the application of the fractional Fourier transform (FrFT) in generating new waveform libraries and the synthesis of a generalised MIMO ambiguity function (AF) based on the Kullback-Leibler divergence (KLD). In particular, a new edge detection algorithm for SAR images is proposed. This method is an enhanced scheme that is based on the phase stretch transform (PST). The high-accuracy of the presented edge detection method is tested and verified experimentally using two SAR image datasets. Experimental results show that thresholding and further morphological operation leads in excellent edge extraction despite the noise embedded into the image. Including PST into the structure of the edge detection algorithm is proved to be very advantageous, since the efficiency in edge determining could be improved by means of tuning the strength and wrap parameters of PST phase kernel. It is shown that the proposed method is very effective and capable to remove embedded noise and introduced artefacts even from image parts corresponding to the surface of the sea. A novel waveform design scheme is proposed to create waveform libraries employing the FrFT. Additionally an efficient algorithm based on a modified Gerchberg-Saxton algorithm (MGSA) is developed to reconstruct the proposed fractional waveform libraries under constant envelope (CE) constrain. This efficient technique is capable of generating novel libraries of phase-coded waveforms through FrFT and optimise the signal retrieval, while the signal waveforms retain their constant modulus. Specifically, the reconstruction of sequences from the FrFTbased waveforms is achieved by means of the error reduction algorithm (ERA). The performance of this new method is evaluated via simulation analysis, showing the good properties of the waveforms in terms of AF performance parameters and in attaining high diversity between waveforms for both fractional and CE fractional libraries. In addition, the applicability of the derived fractional waveforms is experimentally validated, while their performance is evaluated through comparing with conventional techniques in a distributed MIMO radar scenario. Moreover, a novel-multiplexing scheme also based on the FrFT is introduced enabling radar systems to operate in a message exchange mode via embedding the required information into fractional waveforms. The efficiency of the proposed waveform design is evaluated regarding the AF properties of the communicating radar (Co-Radar) waveform. A new, generalised AF is presented based on the KLD and applied in a MIMO radar signal model. The proposed MIMO AF can be factorised into auto-correlation and cross-correlation signal matrices, and channel correlation matrices. Moreover, it is shown that the proposed MIMO AF maximally stretches between 0 and 1, while also being flexible for various geometrical and operating signal configurations. The relationship of the proposed MIMO AF with other definition is also examined, showing that it reduces to the traditional Woodward definition when the same signal model is assumed. In addition, the behaviour of the proposed MIMO AF is investigated for different target placements and operating waveforms highlighting the advantages of each configuration. Finally, the good performance of the AF is demonstrated in a simulated MIMO radar system.The research presented in this thesis deals with the concepts of distributed sensing for multiple-input multiple-output (MIMO) radar systems and important signal processing algorithms with regard to multiple sensing optimisations. These novel algorithms include an edge detection scheme based on the phase stretch transform (PST) for synthetic aperture radar (SAR) imaging systems, the application of the fractional Fourier transform (FrFT) in generating new waveform libraries and the synthesis of a generalised MIMO ambiguity function (AF) based on the Kullback-Leibler divergence (KLD). In particular, a new edge detection algorithm for SAR images is proposed. This method is an enhanced scheme that is based on the phase stretch transform (PST). The high-accuracy of the presented edge detection method is tested and verified experimentally using two SAR image datasets. Experimental results show that thresholding and further morphological operation leads in excellent edge extraction despite the noise embedded into the image. Including PST into the structure of the edge detection algorithm is proved to be very advantageous, since the efficiency in edge determining could be improved by means of tuning the strength and wrap parameters of PST phase kernel. It is shown that the proposed method is very effective and capable to remove embedded noise and introduced artefacts even from image parts corresponding to the surface of the sea. A novel waveform design scheme is proposed to create waveform libraries employing the FrFT. Additionally an efficient algorithm based on a modified Gerchberg-Saxton algorithm (MGSA) is developed to reconstruct the proposed fractional waveform libraries under constant envelope (CE) constrain. This efficient technique is capable of generating novel libraries of phase-coded waveforms through FrFT and optimise the signal retrieval, while the signal waveforms retain their constant modulus. Specifically, the reconstruction of sequences from the FrFTbased waveforms is achieved by means of the error reduction algorithm (ERA). The performance of this new method is evaluated via simulation analysis, showing the good properties of the waveforms in terms of AF performance parameters and in attaining high diversity between waveforms for both fractional and CE fractional libraries. In addition, the applicability of the derived fractional waveforms is experimentally validated, while their performance is evaluated through comparing with conventional techniques in a distributed MIMO radar scenario. Moreover, a novel-multiplexing scheme also based on the FrFT is introduced enabling radar systems to operate in a message exchange mode via embedding the required information into fractional waveforms. The efficiency of the proposed waveform design is evaluated regarding the AF properties of the communicating radar (Co-Radar) waveform. A new, generalised AF is presented based on the KLD and applied in a MIMO radar signal model. The proposed MIMO AF can be factorised into auto-correlation and cross-correlation signal matrices, and channel correlation matrices. Moreover, it is shown that the proposed MIMO AF maximally stretches between 0 and 1, while also being flexible for various geometrical and operating signal configurations. The relationship of the proposed MIMO AF with other definition is also examined, showing that it reduces to the traditional Woodward definition when the same signal model is assumed. In addition, the behaviour of the proposed MIMO AF is investigated for different target placements and operating waveforms highlighting the advantages of each configuration. Finally, the good performance of the AF is demonstrated in a simulated MIMO radar system
Enhanced FRT control strategies for VSC-HVDC connected offshore wind farms
Get PDFStrathclyde theses - ask staff. Thesis no. : T15151The EU has a binding target of 20% of energy to come from renewables by 2020, with an associated CO2 emissions reduction target of 20% (relative to 1990) and a 20% reduction in energy usage by the same date. This is the so-called 20/20/20 target. The UK target is for 15% of energy to be sourced from renewables by this date. For this target to be met, over 30% of electricity will need to be generated from renewables and it is anticipated that 31GW of this will come from wind power, with 13 GW onshore and 18GW offshore, by 2020. At present 6 GW of wind power have been installed onshore and 3.5+ GW offshore. To increase offshore capacity by at least a factor of five in 5 years, whilst minimising the cost of energy, presents very significant design, operational and logistical challenges. As the offshore infrastructure is established and connected big challenges are introduced such as the development of reliable and cost effective wind farm electrical collectors and offshore transmission systems, and the design and implementation of enhanced controls to enable wind farms to support power system operation and maintain system stability.The objective of this thesis is to present, discuss and solve technical barriers for offshore grids. This research is based on simulation studies of control structures of Doubly-fed Induction Generator (DFIG) and Fully-Rated Converter (FRC) wind turbine generators, and VSC-HVDC offshore transmission systems. Simulation results validate the enhancements achieved in the control strategies of both wind turbine generators and VSC-HVDC. These enhanced controls enable the VSC-HVDC connected wind farms to comply with Grid Code requirements such as Fault Ride-Through and provision of voltage and frequency support. The thesis also discusses the pros and cons of installing modifications in the control system of the point-to-point HVDC converters. Furthermore, this research includes a mathematical analysis of the specific conditions of the VSC converters and the AC and DC transmission lines which need to be established in order to ensure the efficient performance of wind farms, and thus to comply with Grid Codes requirements.;Matlab/Simulink software - specifically the SimPowerSystem tool for transient simulation - is used to model and examine a series of proposed scenarios. To achieve the objectives of this thesis and thus to investigate and provide an explanation of the operational system of the DFIG/FRC wind turbines, their interconnection to the offshore cluster substation (VSC converter) and the HVDC connection, basic models have been designed, analysed and tested. A variety of modifications in the control system of the power converters have been applied in order to obtain a better dynamic response in each scenario (single point connection with basic point-to-point connection or more complex offshore scenarios which incorporate several offshore wind farms connected to one offshore cluster substation). These new models (wind turbines and VSC-HVDC) have been compared with the basic models to facilitate the analysis of both systems.The EU has a binding target of 20% of energy to come from renewables by 2020, with an associated CO2 emissions reduction target of 20% (relative to 1990) and a 20% reduction in energy usage by the same date. This is the so-called 20/20/20 target. The UK target is for 15% of energy to be sourced from renewables by this date. For this target to be met, over 30% of electricity will need to be generated from renewables and it is anticipated that 31GW of this will come from wind power, with 13 GW onshore and 18GW offshore, by 2020. At present 6 GW of wind power have been installed onshore and 3.5+ GW offshore. To increase offshore capacity by at least a factor of five in 5 years, whilst minimising the cost of energy, presents very significant design, operational and logistical challenges. As the offshore infrastructure is established and connected big challenges are introduced such as the development of reliable and cost effective wind farm electrical collectors and offshore transmission systems, and the design and implementation of enhanced controls to enable wind farms to support power system operation and maintain system stability.The objective of this thesis is to present, discuss and solve technical barriers for offshore grids. This research is based on simulation studies of control structures of Doubly-fed Induction Generator (DFIG) and Fully-Rated Converter (FRC) wind turbine generators, and VSC-HVDC offshore transmission systems. Simulation results validate the enhancements achieved in the control strategies of both wind turbine generators and VSC-HVDC. These enhanced controls enable the VSC-HVDC connected wind farms to comply with Grid Code requirements such as Fault Ride-Through and provision of voltage and frequency support. The thesis also discusses the pros and cons of installing modifications in the control system of the point-to-point HVDC converters. Furthermore, this research includes a mathematical analysis of the specific conditions of the VSC converters and the AC and DC transmission lines which need to be established in order to ensure the efficient performance of wind farms, and thus to comply with Grid Codes requirements.;Matlab/Simulink software - specifically the SimPowerSystem tool for transient simulation - is used to model and examine a series of proposed scenarios. To achieve the objectives of this thesis and thus to investigate and provide an explanation of the operational system of the DFIG/FRC wind turbines, their interconnection to the offshore cluster substation (VSC converter) and the HVDC connection, basic models have been designed, analysed and tested. A variety of modifications in the control system of the power converters have been applied in order to obtain a better dynamic response in each scenario (single point connection with basic point-to-point connection or more complex offshore scenarios which incorporate several offshore wind farms connected to one offshore cluster substation). These new models (wind turbines and VSC-HVDC) have been compared with the basic models to facilitate the analysis of both systems
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