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The concept of human dignity and its use in legal and political discourses on commercial sex
Get PDFUsing post structural discourse analysis (Laclau and Mouffe 1985), this thesis explores the use of the concept of dignity in jurisprudence on commercial sex, as well as in the discourses produced by abolitionist activists and sex worker rights activists who campaign for (different) legal reforms in this area. Rao's (2011) taxonomy of dignity is deployed as a framework for the analysis of both textual sources and empirical data gathered through interviews with activists. Two principal forms of 'dignity talk' are identified: 'fundamentally incompatible' discourses, which argue that prostitution is always and inherently a violation of dignity; and 'dignity as workers' discourses, which propose that dignity is promoted through the social and legal recognition of commercial sex as a form of work. Where these discourses converge is in their emphasis on the 'intrinsic dignity' of people who sell sex as a way to highlight the potential harms that they face, even while the source of these harms are framed in radically different ways. Beyond this, there is clear divergence, with those who propagate 'fundamentally incompatible' discourses relying on a version of dignity that is principally designed to uphold communitarian norms, while those who use 'dignity as workers' discourses deploy a concept of dignity focused on social recognition. An awareness of the stigma faced by sex workers informs the analysis, and the connections between stigma, dignity and dehumanisation are explored. It is argued that the notion of dignity is strongly associated, in current times, with prevailing ideas of what it means to be a human being. Framing commercial sex, therefore, as a practice that violates dignity, represents it as 'beneath humanity', which may serve to reinforce stigma by positioning sex workers as dehumanised subjects. 'Dignity as workers' discourses, meanwhile, help to challenge stigma by representing sex workers as complex and agentic subjects, but these risk reifying existing economic structures, a situation which may perpetuate inequalities within the sex industry. The thesis concludes with thoughts on ways forward for using 'dignity talk' in discourses on sex work while avoiding the potentially harmful consequences identified.Using post structural discourse analysis (Laclau and Mouffe 1985), this thesis explores the use of the concept of dignity in jurisprudence on commercial sex, as well as in the discourses produced by abolitionist activists and sex worker rights activists who campaign for (different) legal reforms in this area. Rao's (2011) taxonomy of dignity is deployed as a framework for the analysis of both textual sources and empirical data gathered through interviews with activists. Two principal forms of 'dignity talk' are identified: 'fundamentally incompatible' discourses, which argue that prostitution is always and inherently a violation of dignity; and 'dignity as workers' discourses, which propose that dignity is promoted through the social and legal recognition of commercial sex as a form of work. Where these discourses converge is in their emphasis on the 'intrinsic dignity' of people who sell sex as a way to highlight the potential harms that they face, even while the source of these harms are framed in radically different ways. Beyond this, there is clear divergence, with those who propagate 'fundamentally incompatible' discourses relying on a version of dignity that is principally designed to uphold communitarian norms, while those who use 'dignity as workers' discourses deploy a concept of dignity focused on social recognition. An awareness of the stigma faced by sex workers informs the analysis, and the connections between stigma, dignity and dehumanisation are explored. It is argued that the notion of dignity is strongly associated, in current times, with prevailing ideas of what it means to be a human being. Framing commercial sex, therefore, as a practice that violates dignity, represents it as 'beneath humanity', which may serve to reinforce stigma by positioning sex workers as dehumanised subjects. 'Dignity as workers' discourses, meanwhile, help to challenge stigma by representing sex workers as complex and agentic subjects, but these risk reifying existing economic structures, a situation which may perpetuate inequalities within the sex industry. The thesis concludes with thoughts on ways forward for using 'dignity talk' in discourses on sex work while avoiding the potentially harmful consequences identified
Investigating the use of fast repetition rate fluorometry in understanding algal physiology in optically complex oceans
Get PDFIncreased mechanisation and burning of fossil fuels has resulted in year-on-year increases in the concentration of atmospheric carbon dioxide, a key greenhouse gas. Phytoplankton are photosynthesising organisms that are ubiquitous with water and responsible for approximately 50 % of global primary productivity. These organisms have adapted, evolved, and survived over many millions of years, however, the current rate of change being introduced into the biosphere by anthropogenic climate change raises significant questions about how these organisms will adapt to rapidly changing ocean temperatures and acidity.;It is possible to determine the physiological state of phytoplankton using changes in the variable fluorescence output from the photosynthetic pathways present in all phytoplankton. Here this was achieved using a Fast Repetition Rate fluorometer (FRRf). Algal dynamics respond rapidly to changes in environmental conditions making it essential that measurements are made as quickly and accurately as possible.;A core aim of this thesis was to conduct a series of characterisation experiments to optimise the use and define the limits of performance of the FRRf with particular focus on the impact of conducting measurements in optically complex Case II waters. In April, 2015, the Marine Optics and Remote Sensing Group here at the University of Strathclyde together with colleagues from the Helmholtz Zentrum Geesthacht (HZG) in Germany, and Wet Labs Inc. (USA) undertook a research cruise around UK coastal waters.;During this cruise, FRRf was used to determine the physiological status of phytoplankton in a variety of optically complex waters with support from data produced by a host of in situ and lab-based instruments. Data was analysed to establish if any simple patterns could be observed between the physical, optical, and biogeochemical parameters measured in combination with the FRRf measurements with it being found that temporal variability had the most impact on algal physiology.;Subsequently, temporal variability over the course of a single day was investigated using a full day of measurements at a single location in Loch Fyne. A series of six measurements were made over the course of the day providing an opportunity to analyse the impact of overhead conditions on the in situ algal dynamics. Using the inherent optical properties (IOP) data collected at Loch Fyne, it was possible to model the underwater light fields using Hydrolight radiative transfer modelling, which was combined with the FRRf data measured over the day to produce estimates of the daily, column-integrated gross primary productivity (DCIGPP).;This DCIGPP model was compared to three existing models for net primary productivity (NPP) from the literature so as to determine how useful an estimate of GPP the DCIGPP model provided. Using a value for the respiration rate of 97 % from the literature, good agreement was found between the DCIGPP-NPP estimates and the estimates of NPP from the VGPM and CbPM models. This suggests that the model of DCIGPP based on FRRf data is potentially useful in estimating the daily gross primary productivity.Increased mechanisation and burning of fossil fuels has resulted in year-on-year increases in the concentration of atmospheric carbon dioxide, a key greenhouse gas. Phytoplankton are photosynthesising organisms that are ubiquitous with water and responsible for approximately 50 % of global primary productivity. These organisms have adapted, evolved, and survived over many millions of years, however, the current rate of change being introduced into the biosphere by anthropogenic climate change raises significant questions about how these organisms will adapt to rapidly changing ocean temperatures and acidity.;It is possible to determine the physiological state of phytoplankton using changes in the variable fluorescence output from the photosynthetic pathways present in all phytoplankton. Here this was achieved using a Fast Repetition Rate fluorometer (FRRf). Algal dynamics respond rapidly to changes in environmental conditions making it essential that measurements are made as quickly and accurately as possible.;A core aim of this thesis was to conduct a series of characterisation experiments to optimise the use and define the limits of performance of the FRRf with particular focus on the impact of conducting measurements in optically complex Case II waters. In April, 2015, the Marine Optics and Remote Sensing Group here at the University of Strathclyde together with colleagues from the Helmholtz Zentrum Geesthacht (HZG) in Germany, and Wet Labs Inc. (USA) undertook a research cruise around UK coastal waters.;During this cruise, FRRf was used to determine the physiological status of phytoplankton in a variety of optically complex waters with support from data produced by a host of in situ and lab-based instruments. Data was analysed to establish if any simple patterns could be observed between the physical, optical, and biogeochemical parameters measured in combination with the FRRf measurements with it being found that temporal variability had the most impact on algal physiology.;Subsequently, temporal variability over the course of a single day was investigated using a full day of measurements at a single location in Loch Fyne. A series of six measurements were made over the course of the day providing an opportunity to analyse the impact of overhead conditions on the in situ algal dynamics. Using the inherent optical properties (IOP) data collected at Loch Fyne, it was possible to model the underwater light fields using Hydrolight radiative transfer modelling, which was combined with the FRRf data measured over the day to produce estimates of the daily, column-integrated gross primary productivity (DCIGPP).;This DCIGPP model was compared to three existing models for net primary productivity (NPP) from the literature so as to determine how useful an estimate of GPP the DCIGPP model provided. Using a value for the respiration rate of 97 % from the literature, good agreement was found between the DCIGPP-NPP estimates and the estimates of NPP from the VGPM and CbPM models. This suggests that the model of DCIGPP based on FRRf data is potentially useful in estimating the daily gross primary productivity
Iridium(I) complexes for the functionalisation of carbon-hydrogen bonds
Get PDFThe development of catalytic systems for the functionalisation of carbon-hydrogen bonds has been an intensive area of research for the last 5 decades. In this context, transition metal complexes play a crucial role in reaction discovery, mechanistic evaluation and synthetic applications. In the Kerr group, this technology has been explored in the context of hydrogen isotope exchange, resulting in the development of highly active iridium(I) complexes bearing phosphines and NHC ligands. Despite their broad functional group compatibility, existing methods for isotope exchange are ineffective in the labelling of sterically encumbered directing groups. Hence, in the first chapter we investigate the synthesis of three new iridium(I) complexes bearing chelating phosphine-functionalised NHC ligands, and their application in the isotope exchange of sterically hindered carbamates. Our initial studies revealed high catalytic efficiency and tolerance for steric encumbrance, prompting us to perform a combined theoretical and experimental investigation of the reaction mechanism.Therefore, by conducting DFT calculations and kinetic experiments, we were able to identify a rich dynamic behaviour in solution and ultimately propose a reaction mechanism. Additionally, our interest in the activation of carbon-hydrogen bonds resulted in the exploration of a theoretical model for the prediction of enthalpies of activation, resulting in the identification of relevant electronic and steric descriptors.From the knowledge gathered in our initial studies, the second chapter describes the application of our novel iridium catalysts in the functionalisation of carbon-hydrogen bonds in the context of hydroarylation of olefins. Thus, we identified carboxylic acids as suitable directing groups for this transformation and employed Design of Experiments to optimise the reaction conditions. Synthetic studies were focused on the preparation of 14 substrates, enabling quick assessment of the capabilities and limitations of this reaction. These investigations resulted in a synthetic method suitable for the synthesis of bi- and tricycles featuring tertiary and quaternary benzylic stereocentres in a racemic fashion.Finally, we investigated the mechanism of this process by DFT calculations, which led us to identify a plausible reaction pathway which should guide future kinetic evaluations.The development of catalytic systems for the functionalisation of carbon-hydrogen bonds has been an intensive area of research for the last 5 decades. In this context, transition metal complexes play a crucial role in reaction discovery, mechanistic evaluation and synthetic applications. In the Kerr group, this technology has been explored in the context of hydrogen isotope exchange, resulting in the development of highly active iridium(I) complexes bearing phosphines and NHC ligands. Despite their broad functional group compatibility, existing methods for isotope exchange are ineffective in the labelling of sterically encumbered directing groups. Hence, in the first chapter we investigate the synthesis of three new iridium(I) complexes bearing chelating phosphine-functionalised NHC ligands, and their application in the isotope exchange of sterically hindered carbamates. Our initial studies revealed high catalytic efficiency and tolerance for steric encumbrance, prompting us to perform a combined theoretical and experimental investigation of the reaction mechanism.Therefore, by conducting DFT calculations and kinetic experiments, we were able to identify a rich dynamic behaviour in solution and ultimately propose a reaction mechanism. Additionally, our interest in the activation of carbon-hydrogen bonds resulted in the exploration of a theoretical model for the prediction of enthalpies of activation, resulting in the identification of relevant electronic and steric descriptors.From the knowledge gathered in our initial studies, the second chapter describes the application of our novel iridium catalysts in the functionalisation of carbon-hydrogen bonds in the context of hydroarylation of olefins. Thus, we identified carboxylic acids as suitable directing groups for this transformation and employed Design of Experiments to optimise the reaction conditions. Synthetic studies were focused on the preparation of 14 substrates, enabling quick assessment of the capabilities and limitations of this reaction. These investigations resulted in a synthetic method suitable for the synthesis of bi- and tricycles featuring tertiary and quaternary benzylic stereocentres in a racemic fashion.Finally, we investigated the mechanism of this process by DFT calculations, which led us to identify a plausible reaction pathway which should guide future kinetic evaluations
A conceptual model of trust in emergency evacuation : evidence from Indonesian volcano eruptions
Get PDFThis research develops a conceptual model of trust during emergency evacuations in Indonesia. Drawing upon the cultural theory of Douglas (1978) as the theoretical basis, this research explores and identifies the main components required to build a conceptual model in agent-based modelling and simulation (ABMS) by: (1) improving the existing situational judgment test (SJT) scoring method for clustering people's trust into cultural categories; (2) identifying the differences between each cultural category; and (3) investigating the factors that encourage people in each category to shift to another category when they face three different situations.To accomplish the research goal, a two-case comparative study in Merapi and Sinabung is conducted using: (1) semi-structured interviews with government representatives, non-government leaders, and anthropologists; and (2) an empirical survey of villagers in Merapi and Sinabung. The interview results are analysed using thematic analysis, which provides the information needed to develop the initial conceptual model and to construct the SJT used in the survey questionnaire. The survey results are then analysed using three different methods: (1) hierarchical and k-means clustering, to improve the existing SJT scoring method; (2) a non-parametric test to identify the differences between cultural categories; and (3) multinomial logistic regression (MLR) to identify the factors encouraging people in each category to shift to another category. Finally, the survey results are used to verify the initial conceptual model developed following the interviews.The research finds that the hierarchical and k-means clustering methods can successfully improve the existing SJT scoring method due to the higher consistency achieved in the validation process. Four and two cultural categories are found in Merapi and Sinabung, respectively. On the other hand, this research also successfully distinguishes between the cultural categories based on attributes grouped into three aspects - socio-demographic, evacuation behaviour, and psychological aspects - and identifies the factors that encourage people in each category to shift to another category when they face three different situations: (1) when the volcano shows eruption signs; (2) when a long duration eruption occurs; and (3) when the volcano erupts. These results are used as the main components to verify the initial conceptual model of trust. The verified conceptual model developed in this research can be utilised in the future as a basis on which to simulate people's trust during emergency evacuations using ABMS, and can also help policy-makers in Indonesian disaster management to better comprehend future ABMS.This research develops a conceptual model of trust during emergency evacuations in Indonesia. Drawing upon the cultural theory of Douglas (1978) as the theoretical basis, this research explores and identifies the main components required to build a conceptual model in agent-based modelling and simulation (ABMS) by: (1) improving the existing situational judgment test (SJT) scoring method for clustering people's trust into cultural categories; (2) identifying the differences between each cultural category; and (3) investigating the factors that encourage people in each category to shift to another category when they face three different situations.To accomplish the research goal, a two-case comparative study in Merapi and Sinabung is conducted using: (1) semi-structured interviews with government representatives, non-government leaders, and anthropologists; and (2) an empirical survey of villagers in Merapi and Sinabung. The interview results are analysed using thematic analysis, which provides the information needed to develop the initial conceptual model and to construct the SJT used in the survey questionnaire. The survey results are then analysed using three different methods: (1) hierarchical and k-means clustering, to improve the existing SJT scoring method; (2) a non-parametric test to identify the differences between cultural categories; and (3) multinomial logistic regression (MLR) to identify the factors encouraging people in each category to shift to another category. Finally, the survey results are used to verify the initial conceptual model developed following the interviews.The research finds that the hierarchical and k-means clustering methods can successfully improve the existing SJT scoring method due to the higher consistency achieved in the validation process. Four and two cultural categories are found in Merapi and Sinabung, respectively. On the other hand, this research also successfully distinguishes between the cultural categories based on attributes grouped into three aspects - socio-demographic, evacuation behaviour, and psychological aspects - and identifies the factors that encourage people in each category to shift to another category when they face three different situations: (1) when the volcano shows eruption signs; (2) when a long duration eruption occurs; and (3) when the volcano erupts. These results are used as the main components to verify the initial conceptual model of trust. The verified conceptual model developed in this research can be utilised in the future as a basis on which to simulate people's trust during emergency evacuations using ABMS, and can also help policy-makers in Indonesian disaster management to better comprehend future ABMS
The impact of double dents on pipeline integrity
Get PDFPipelines are used for the transportation of various products across the world. Most of these pipelines are installed underground, which makes it harder to detect a failure or to repair the pipeline when it is damaged. A dent is defined as a plastic deformation in a pipeline which can turn into a threat by causing stress concentration, and as a result the pipeline may fail, which can result in safety, economic and environmental disasters. Guidance is therefore needed for operators to identify which dents could potentially be damaging to pipeline safety and to consider which dents require further action such as excavation or repairing.Experimental research on dents on a pipeline has been made for decades. To understand the severity of such defects on pipelines, various methodologies related to dent assessment have been developed based on the results of experimental studies as well as Finite Element Analysis (FEA).Although many studies have been conducted on a single dent defects, there is no published guidance or assessment methods to determine the severity of multiple dent defects when they are detected in pipelines because current assessment methods or published guidelines treat dents as isolated defect which does not consider interactions with each other. Understanding and predicting the behaviour of pipelines that are subjected to a multiple dents will require an assessment to determine how severe the effect could be.Analysis was carried with three standard parameters; dent depth, effects of distance between the dents and effects of indenter diameters. The objective for this study is to create a Finite Element Model (FEM) to develop a parametric study to determine interaction effect of each dents considering the dent shape, distance between the dents and the effect of internal pressure.Pipelines are used for the transportation of various products across the world. Most of these pipelines are installed underground, which makes it harder to detect a failure or to repair the pipeline when it is damaged. A dent is defined as a plastic deformation in a pipeline which can turn into a threat by causing stress concentration, and as a result the pipeline may fail, which can result in safety, economic and environmental disasters. Guidance is therefore needed for operators to identify which dents could potentially be damaging to pipeline safety and to consider which dents require further action such as excavation or repairing.Experimental research on dents on a pipeline has been made for decades. To understand the severity of such defects on pipelines, various methodologies related to dent assessment have been developed based on the results of experimental studies as well as Finite Element Analysis (FEA).Although many studies have been conducted on a single dent defects, there is no published guidance or assessment methods to determine the severity of multiple dent defects when they are detected in pipelines because current assessment methods or published guidelines treat dents as isolated defect which does not consider interactions with each other. Understanding and predicting the behaviour of pipelines that are subjected to a multiple dents will require an assessment to determine how severe the effect could be.Analysis was carried with three standard parameters; dent depth, effects of distance between the dents and effects of indenter diameters. The objective for this study is to create a Finite Element Model (FEM) to develop a parametric study to determine interaction effect of each dents considering the dent shape, distance between the dents and the effect of internal pressure
Investigation of the role of microplastics in the transport of potentially toxic element species in the marine environment
No full textThis thesis was previously restricted to Strathclyde users only until 30th September 2023.There is growing global concern about the impact of microplastics on the marine environment, with evidence emerging that plastic pellets can be a vector for potentially toxic elements (PTE). In this thesis, PTE content was first investigated in petroleum based (polyethylene, polypropylene and polyethylene terephthalate) and bio-based (poly(hydroxybutyrate-co-hydroxyvalerate)) virgin plastic pellets. Various elements associated with plastics' manufacture were detected.;Next, sorption experiments were conducted to assess the capacity of virgin and laboratory-weathered pellets to take up As, Cd, Cr and Pb from controlled media of deionised, fresh and artificial seawater, with analysis by ICP-MS (Agilent 7700x instrument). All types of plastics showed the ability to take up the PTE studied and the total amounts were in the order Pb > As > Cd > Cr when single element solutions were studied and Pb > Cd > Cr > As from a multi-element solution.;It was found that weathered pellets took up greater amounts of PTE than virgin ones. The surface of virgin, laboratory-weathered and beached pellets collected from Kuwait and Scotland were then imaged and their chemical composition determined using a scanning electron microscope with energy-dispersive EDS analyser (JEOL JSM-6010LA). Analysis revealed changes in pellet morphology following weathering.;Elements detected were associated with aspects of plastic production or taken up from the ambient environment. Beached pellets were identified by ATR-FTIR as predominantly polyethylene and polypropylene. When examples were subjected to sequential cold acid digestion followed by microwave extraction, larger amount of PTE were released by the cold digestion step, indicating the analytes were relatively weakly bound.;Samples from Kuwait released higher amounts of PTE than samples from Scotland. In vitro bioaccessibility of PTE to simulated fish stomach was estimated using two methods, a modified SBET and a 0.1 M HCl extraction. Lead was found to be the most bioaccessible of the PTE studied.There is growing global concern about the impact of microplastics on the marine environment, with evidence emerging that plastic pellets can be a vector for potentially toxic elements (PTE). In this thesis, PTE content was first investigated in petroleum based (polyethylene, polypropylene and polyethylene terephthalate) and bio-based (poly(hydroxybutyrate-co-hydroxyvalerate)) virgin plastic pellets. Various elements associated with plastics' manufacture were detected.;Next, sorption experiments were conducted to assess the capacity of virgin and laboratory-weathered pellets to take up As, Cd, Cr and Pb from controlled media of deionised, fresh and artificial seawater, with analysis by ICP-MS (Agilent 7700x instrument). All types of plastics showed the ability to take up the PTE studied and the total amounts were in the order Pb > As > Cd > Cr when single element solutions were studied and Pb > Cd > Cr > As from a multi-element solution.;It was found that weathered pellets took up greater amounts of PTE than virgin ones. The surface of virgin, laboratory-weathered and beached pellets collected from Kuwait and Scotland were then imaged and their chemical composition determined using a scanning electron microscope with energy-dispersive EDS analyser (JEOL JSM-6010LA). Analysis revealed changes in pellet morphology following weathering.;Elements detected were associated with aspects of plastic production or taken up from the ambient environment. Beached pellets were identified by ATR-FTIR as predominantly polyethylene and polypropylene. When examples were subjected to sequential cold acid digestion followed by microwave extraction, larger amount of PTE were released by the cold digestion step, indicating the analytes were relatively weakly bound.;Samples from Kuwait released higher amounts of PTE than samples from Scotland. In vitro bioaccessibility of PTE to simulated fish stomach was estimated using two methods, a modified SBET and a 0.1 M HCl extraction. Lead was found to be the most bioaccessible of the PTE studied
Central nervous system organisation following traumatic incomplete spinal cord injury (iSCI) : a longitudinal clinical study
Get PDFTraumatic spinal cord injury (SCI) triggers pathophysiological consequences and secondary injuries that combine to determine the extent and final outcome of SCI. This study is aimed at examining a set of electrophysiological tests for their potential practicality and accuracy in assessing incomplete SCI and associated clinical presentation. These electrophysiological tests, which are less frequently used in clinical practice, included somatosensory evoked potential (SEP) methods improved with the addition of Dermatomal SEP (D-SEP) and analysis of event related synchronisation (ERS) and desynchronisation (ERD), potentially providing more information about the ascending spinal tracts sub-serving examined sensory modalities. In a manner complementary to this sensory assessment, transcranial magnetic stimulation (TMS) of cerebral cortex was used to assess integrity and function of descending motor cortico-spinal tracts (CST) sub-serving signals from cortical pyramidal neurons to corresponding muscles above and below specified SCI levels. Coupled simultaneous electroencephalography (EEG) and surface electromyography (EMG) from corresponding muscles, Cortico-Muscular Coherence (CMC), was analysed to expose any EEG-EMG synchrony to highlight functional relationships of cerebral motor cortex and target muscles served. Information from sensory and motor spinal tract assessment of 9 SCI patients was charted alongside clinical assessment of neurological function using the American Spinal Injuries Association (ASIA) scale obtaining valid comparative electrophysiological clinical means of longitudinal follow up of any possible improvement or deterioration seen following SCI. Similar electrophysiological assessment was performed for 14 healthy volunteers (normal subjects used as control) obtaining normative data. The resulting data were collected for computational analysis and results obtained on the integrity and function of SCI lesions, as well as trends in electrophysiological measurements. These data also informed ways to predict possible recovery and outcome of SCI. The study faced technical challenges that stood out as limitations to the full potentials.? The electrophysiological tests carried out for SCI patients in acute hospital settings are extremely challenging, raising fundamental questions of how these tests could be brought into the acute clinical setting in the caring for SCI patients. Individual electrophysiological tests included conventional SEP measurements. These were relatively straightforward as part of assessing SCI patients. These include improved SEP measures combined with electrophysiological means of assessing the integrity of peripheral nerves. D-SEPs are generally less reliable than standard mixed-nerve SEPs; however, with the improvements, D-SEP measurements brings useful anatomical detection of level information. For both SEP and D-SEP measurements, reporting of abnormalities might have been enhanced by improving specificity of deciding abnormal results relating to amplitude and latency. Motor Evoked Potentials (MEP) parameters are a reliable electrophysiological measure of motor function, and are used in concordance with the clinical Asia Impairment Scale scores. MEP parameters have a potential relevance to functional outcomes such as hand function and walking following SCI. An area of improvement of MEP includes estimation of central conduction time (CCT) to allow detection of any peripheral nerve abnormality or degeneration affecting MEP measurements. However, the Cortico-Muscular Coherence (CMC) is not easy to obtain due to clinical factors and the use of medications in the context of SCI. CMC however has potential for future improved measures of muscle function in patients with recovering muscle power tested at time intervals. Overall, combining improved SEP and MEP measurements offer better information on sensory and motor function and pathways, respectively. This offers the best chance of obtaining reliable comprehensive information on injured spinal tracts and their recovery process. The study concluded that examined electrophysiological methods of assessing sensory and motor spinal tracts were sensitive, reproducible and accurate. They are reliable for use in assessing SCI patients in an acute hospital setting. This study focussed on the technical challenges facing these electrophysiological methods used in the clinical setting for accurately measurement of outcome or recovery following SCI.Traumatic spinal cord injury (SCI) triggers pathophysiological consequences and secondary injuries that combine to determine the extent and final outcome of SCI. This study is aimed at examining a set of electrophysiological tests for their potential practicality and accuracy in assessing incomplete SCI and associated clinical presentation. These electrophysiological tests, which are less frequently used in clinical practice, included somatosensory evoked potential (SEP) methods improved with the addition of Dermatomal SEP (D-SEP) and analysis of event related synchronisation (ERS) and desynchronisation (ERD), potentially providing more information about the ascending spinal tracts sub-serving examined sensory modalities. In a manner complementary to this sensory assessment, transcranial magnetic stimulation (TMS) of cerebral cortex was used to assess integrity and function of descending motor cortico-spinal tracts (CST) sub-serving signals from cortical pyramidal neurons to corresponding muscles above and below specified SCI levels. Coupled simultaneous electroencephalography (EEG) and surface electromyography (EMG) from corresponding muscles, Cortico-Muscular Coherence (CMC), was analysed to expose any EEG-EMG synchrony to highlight functional relationships of cerebral motor cortex and target muscles served. Information from sensory and motor spinal tract assessment of 9 SCI patients was charted alongside clinical assessment of neurological function using the American Spinal Injuries Association (ASIA) scale obtaining valid comparative electrophysiological clinical means of longitudinal follow up of any possible improvement or deterioration seen following SCI. Similar electrophysiological assessment was performed for 14 healthy volunteers (normal subjects used as control) obtaining normative data. The resulting data were collected for computational analysis and results obtained on the integrity and function of SCI lesions, as well as trends in electrophysiological measurements. These data also informed ways to predict possible recovery and outcome of SCI. The study faced technical challenges that stood out as limitations to the full potentials.? The electrophysiological tests carried out for SCI patients in acute hospital settings are extremely challenging, raising fundamental questions of how these tests could be brought into the acute clinical setting in the caring for SCI patients. Individual electrophysiological tests included conventional SEP measurements. These were relatively straightforward as part of assessing SCI patients. These include improved SEP measures combined with electrophysiological means of assessing the integrity of peripheral nerves. D-SEPs are generally less reliable than standard mixed-nerve SEPs; however, with the improvements, D-SEP measurements brings useful anatomical detection of level information. For both SEP and D-SEP measurements, reporting of abnormalities might have been enhanced by improving specificity of deciding abnormal results relating to amplitude and latency. Motor Evoked Potentials (MEP) parameters are a reliable electrophysiological measure of motor function, and are used in concordance with the clinical Asia Impairment Scale scores. MEP parameters have a potential relevance to functional outcomes such as hand function and walking following SCI. An area of improvement of MEP includes estimation of central conduction time (CCT) to allow detection of any peripheral nerve abnormality or degeneration affecting MEP measurements. However, the Cortico-Muscular Coherence (CMC) is not easy to obtain due to clinical factors and the use of medications in the context of SCI. CMC however has potential for future improved measures of muscle function in patients with recovering muscle power tested at time intervals. Overall, combining improved SEP and MEP measurements offer better information on sensory and motor function and pathways, respectively. This offers the best chance of obtaining reliable comprehensive information on injured spinal tracts and their recovery process. The study concluded that examined electrophysiological methods of assessing sensory and motor spinal tracts were sensitive, reproducible and accurate. They are reliable for use in assessing SCI patients in an acute hospital setting. This study focussed on the technical challenges facing these electrophysiological methods used in the clinical setting for accurately measurement of outcome or recovery following SCI
Analytical methods for satellite constellation reconfiguration and reconnaissance using low-thrust manoeuvres
Get PDFStrathclyde theses - ask staff. Thesis no. : T15003A fully-analytical general perturbation solution to a restricted low-thrust circular to circular Lambert rendezvous problem with tangential thrust and an optional coast arc is developed. The solution requires no iteration and is solved rapidly to generate a full range of possible manoeuvres to achieve the desired goal. The speed of the solution allows for large-scale problems involving numerous spacecraft and manoeuvres to be studied; this is demonstrated by applying the method to a range of mission scenarios. In the first scenario, a full range of manoeuvres providing rapid flyover of Los Angelesis generated, giving an insight to the trade-space and allowing the manoeuvre that best fulfils the mission priorities to be selected. Using a CubeSat equipped with electro-spray propulsion, these manoeuvres can reduce the time to overight by more than 85%, for less than 20 m/s velocity change, when compared with a non-manoeuvring satellite. The second scenario considers a constellation of 24 satellites that can manoeuvre to provide targeted coverage of a region of the Earth as required. A full set of manoeuvres for all satellites is generated for four sequential targets, allowing the most suitable manoeuvre strategy to be selected; regional improvements in coverage of more than ten times are shown to be achievable when compared to a static constellation. Finally, deploying a constellation of spacecraft by using low-thrust manoeuvres to achieve the desired configuration is studied. Deploying a constellation of 24 satellites using this technique could reduce launch costs by 75% compared with traditional methods. These cases demonstrate the advantages that manoeuvrable satellites can provide, but it is the analytical general perturbation solution, which allows for rapid exploration of these complex problems, that is the key contribution of this work.A fully-analytical general perturbation solution to a restricted low-thrust circular to circular Lambert rendezvous problem with tangential thrust and an optional coast arc is developed. The solution requires no iteration and is solved rapidly to generate a full range of possible manoeuvres to achieve the desired goal. The speed of the solution allows for large-scale problems involving numerous spacecraft and manoeuvres to be studied; this is demonstrated by applying the method to a range of mission scenarios. In the first scenario, a full range of manoeuvres providing rapid flyover of Los Angelesis generated, giving an insight to the trade-space and allowing the manoeuvre that best fulfils the mission priorities to be selected. Using a CubeSat equipped with electro-spray propulsion, these manoeuvres can reduce the time to overight by more than 85%, for less than 20 m/s velocity change, when compared with a non-manoeuvring satellite. The second scenario considers a constellation of 24 satellites that can manoeuvre to provide targeted coverage of a region of the Earth as required. A full set of manoeuvres for all satellites is generated for four sequential targets, allowing the most suitable manoeuvre strategy to be selected; regional improvements in coverage of more than ten times are shown to be achievable when compared to a static constellation. Finally, deploying a constellation of spacecraft by using low-thrust manoeuvres to achieve the desired configuration is studied. Deploying a constellation of 24 satellites using this technique could reduce launch costs by 75% compared with traditional methods. These cases demonstrate the advantages that manoeuvrable satellites can provide, but it is the analytical general perturbation solution, which allows for rapid exploration of these complex problems, that is the key contribution of this work
Harvesting energy from electric fields for powering wireless sensors within air-insulated substations
No full textAging equipment in the electricity grid requires close monitoring to ensure the safe operation of the network. The lack of reliable and cost effective ways for supplying power has hindered the large scale installation of wireless condition monitoring sensors in the electricity grid. Electric fields of elevated strength exist in high voltage plants, such as air-insulated substations. Advances in technology have been reducing the power consumption of wireless sensors. Harvesting energy from the electric fields could be a viable way of supplying power to the wireless sensors if the technical challenges can be overcome.;This study reports the progress in the field of energy harvesting, surveys the electric fields inside air-insulated substations, explains the physical phenomenon of charge induction inside electric fields in detail, investigates charge transfer techniques, proposes solutions to the technical challenges and presents the design and assembly of a demonstration unit. The successful operation of the demonstration unit shows that harvesting energy from the electric fields has the potential to enable large scale installation of wireless condition monitoring sensors in the electricity grid.Aging equipment in the electricity grid requires close monitoring to ensure the safe operation of the network. The lack of reliable and cost effective ways for supplying power has hindered the large scale installation of wireless condition monitoring sensors in the electricity grid. Electric fields of elevated strength exist in high voltage plants, such as air-insulated substations. Advances in technology have been reducing the power consumption of wireless sensors. Harvesting energy from the electric fields could be a viable way of supplying power to the wireless sensors if the technical challenges can be overcome.;This study reports the progress in the field of energy harvesting, surveys the electric fields inside air-insulated substations, explains the physical phenomenon of charge induction inside electric fields in detail, investigates charge transfer techniques, proposes solutions to the technical challenges and presents the design and assembly of a demonstration unit. The successful operation of the demonstration unit shows that harvesting energy from the electric fields has the potential to enable large scale installation of wireless condition monitoring sensors in the electricity grid
Analysis and practical assessment of converter-dominated power systems : stability constraints, dynamic performance and power quality
Get PDFFor years, large power systems have been predominantly managed using the very well known synchronous machine on the generation side. With the increasing penetration of load and generation interfaced by converter-based systems, the conventional syn-chronous machine is being gradually replaced by these new devices. However, this slow and steady change of the generation technology has led to side-effects which can affect to the local stability and, if no remedial action is taken, system-wide stability.;The main objective of this thesis is to understand, expose and overcome the weak-nesses of converter-dominated grids within a laboratory environment. To do so, a converter of 10kVA has been built implementing the standard D-Q axis Current Injection (DQCI) control and, for first time to date, the Virtual Synchronous Machine with Zero Inertia (VSM0H). Further developments have been made to this control strategy to implement this theoretical algorithm into a real system.;The solutions proposed in this thesis for converter-dominated grids are based on the Grid Forming Nodes (GFN) solution. This composition suggests the usage of a combination of DQCI and Virtual Synchronous Machine (VSM) converters to achieve stability within converter-dominated grids. However, there is limited understanding about VSM functioning. Initially, the application of VSM-style converters was proposed as a natural replacement of the real synchronous machine present in the system without understanding which are the specific weaknesses that affect to this type of grid. Due to the aforementioned reasons, this thesis aims to provide a more scientific and rigorous explanation of why the GFN solution can provide stability for converter-dominated power systems. Using the converter built, it is possible to recreate scenarios where the technical challenges involved in power systems can be understood.;Going from well-established solutions for relatively low Levels of Penetration (LoP), such as grid-friendly or smart converters, to an insightful explanation of why these solutions are not valid for converter-dominated grids with high values of LoP. This thesis puts more emphasis on the latter case, assessing experimentally the GFN solution for representative scenarios and control strategies used in the converter built explicitly for this project.;Initially, three experiments are conducted to identify the weaknesses of converter-dominated grids. During these initial scenarios, it has been found that DQCI converters behave as current sources from the grid point of view, following an already imposed voltage signal. As current sources, DQCI converters do not provide effective voltage regulation. On the contrary, GFN/VSM converters behave as voltage sources behind an inductance from the grid point of view. Thus, they contribute to the entire grid stability by assuring the local voltage stiffness. However, further experiments with unbalanced and non-linear loads have found that this capability is finite and directly dependent on the equivalent converter filter impedance.;During the execution of the experiments, there have been additional contributions explained throughout this thesis:;The virtual resistor technique. Incorporating an additional feed-forward term into the inner current loop, the stabilizing effect of the parasitic inductor resistance is simulated. As result, the inner control loop operates in a more stable manner.;The explanation, implementation and validation of a novel control strategy which makes the converter operate with variable speed response depending on the grid events. This adaptive functioning leads to a more robust operation for both the converter and the grid.;A new control strategy based on the VSM0H (so called in this thesis as VSM0H+). Measuring the negative sequence voltage present in the grid, it is possible to add a compensation term which can provide an almost perfect voltage regulation under the presence of heavily unbalanced loads.For years, large power systems have been predominantly managed using the very well known synchronous machine on the generation side. With the increasing penetration of load and generation interfaced by converter-based systems, the conventional syn-chronous machine is being gradually replaced by these new devices. However, this slow and steady change of the generation technology has led to side-effects which can affect to the local stability and, if no remedial action is taken, system-wide stability.;The main objective of this thesis is to understand, expose and overcome the weak-nesses of converter-dominated grids within a laboratory environment. To do so, a converter of 10kVA has been built implementing the standard D-Q axis Current Injection (DQCI) control and, for first time to date, the Virtual Synchronous Machine with Zero Inertia (VSM0H). Further developments have been made to this control strategy to implement this theoretical algorithm into a real system.;The solutions proposed in this thesis for converter-dominated grids are based on the Grid Forming Nodes (GFN) solution. This composition suggests the usage of a combination of DQCI and Virtual Synchronous Machine (VSM) converters to achieve stability within converter-dominated grids. However, there is limited understanding about VSM functioning. Initially, the application of VSM-style converters was proposed as a natural replacement of the real synchronous machine present in the system without understanding which are the specific weaknesses that affect to this type of grid. Due to the aforementioned reasons, this thesis aims to provide a more scientific and rigorous explanation of why the GFN solution can provide stability for converter-dominated power systems. Using the converter built, it is possible to recreate scenarios where the technical challenges involved in power systems can be understood.;Going from well-established solutions for relatively low Levels of Penetration (LoP), such as grid-friendly or smart converters, to an insightful explanation of why these solutions are not valid for converter-dominated grids with high values of LoP. This thesis puts more emphasis on the latter case, assessing experimentally the GFN solution for representative scenarios and control strategies used in the converter built explicitly for this project.;Initially, three experiments are conducted to identify the weaknesses of converter-dominated grids. During these initial scenarios, it has been found that DQCI converters behave as current sources from the grid point of view, following an already imposed voltage signal. As current sources, DQCI converters do not provide effective voltage regulation. On the contrary, GFN/VSM converters behave as voltage sources behind an inductance from the grid point of view. Thus, they contribute to the entire grid stability by assuring the local voltage stiffness. However, further experiments with unbalanced and non-linear loads have found that this capability is finite and directly dependent on the equivalent converter filter impedance.;During the execution of the experiments, there have been additional contributions explained throughout this thesis:;The virtual resistor technique. Incorporating an additional feed-forward term into the inner current loop, the stabilizing effect of the parasitic inductor resistance is simulated. As result, the inner control loop operates in a more stable manner.;The explanation, implementation and validation of a novel control strategy which makes the converter operate with variable speed response depending on the grid events. This adaptive functioning leads to a more robust operation for both the converter and the grid.;A new control strategy based on the VSM0H (so called in this thesis as VSM0H+). Measuring the negative sequence voltage present in the grid, it is possible to add a compensation term which can provide an almost perfect voltage regulation under the presence of heavily unbalanced loads
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