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Techniques in the optical detection of magnetic resonance using nitrogen-vacancy centre ensembles in diamond
Get PDFStudies were performed to progress the application of nitrogen-vacancy (NV) centres to the sensing of magnetic fields.;A magnetometer using an NV centre ensemble contained within a 150 μm diameter diamond was built. Using an adapted epi-fluorescence microscopy setup and 2 mW of optical excitation, a sensitivity of 70 ± 26 nT/Hz1/2 was achieved with a bandwidth of 3.1 kHz. This was 110 times above the shot-noise limit of 639 pT/Hz1/2 and 1129 times above the spin projection noise limit of 62 pT/Hz1/2. This was likely due to noise in the laser, microwaves and detectors. The experimental method requires large improvements in spin dephasing time (T2*) to enable the intended detection of marine worm action potentials via bio-magnetism.;Secondly, two-photon excited optical detection of magnetic resonance (2PODMR) of NV centre ensembles was successfully demonstrated. This proves two-photon excited magnetometry with NV centres possible. The 2PODMR linewidth and contrast were found to be reduced by 39.6 % and 73.7 % respectively, when compared with measurements of single-photon excited ODMR. The reduction in ODMR contrast can only partially be explained by the increased temperature and lower NV-/NV0 ratio under two-photon excitation.;Two-photon excited fluorescence was also found to saturate at low fluorescence rates compared with single-photon excited fluorescence. This is likely to be related to previously measured effects where 1064 nm excitation has quenched 532 nm excited fluorescence.;Finally, a first step towards building a magneto-sensitive laser using NV centres for ultra-sensitive magnetometry was made. Direct measurements of stimulated emission from NV centre ensembles contained within a mm scale diamond were attempted but were inconclusive. Despite measuring a change in probe power using a pump-probe setup, the wavelength, power and temporal dependencies were not fully consistent with a measurement of stimulated emission. However, ODMR was successfully measured using the probe beam.Studies were performed to progress the application of nitrogen-vacancy (NV) centres to the sensing of magnetic fields.;A magnetometer using an NV centre ensemble contained within a 150 μm diameter diamond was built. Using an adapted epi-fluorescence microscopy setup and 2 mW of optical excitation, a sensitivity of 70 ± 26 nT/Hz1/2 was achieved with a bandwidth of 3.1 kHz. This was 110 times above the shot-noise limit of 639 pT/Hz1/2 and 1129 times above the spin projection noise limit of 62 pT/Hz1/2. This was likely due to noise in the laser, microwaves and detectors. The experimental method requires large improvements in spin dephasing time (T2*) to enable the intended detection of marine worm action potentials via bio-magnetism.;Secondly, two-photon excited optical detection of magnetic resonance (2PODMR) of NV centre ensembles was successfully demonstrated. This proves two-photon excited magnetometry with NV centres possible. The 2PODMR linewidth and contrast were found to be reduced by 39.6 % and 73.7 % respectively, when compared with measurements of single-photon excited ODMR. The reduction in ODMR contrast can only partially be explained by the increased temperature and lower NV-/NV0 ratio under two-photon excitation.;Two-photon excited fluorescence was also found to saturate at low fluorescence rates compared with single-photon excited fluorescence. This is likely to be related to previously measured effects where 1064 nm excitation has quenched 532 nm excited fluorescence.;Finally, a first step towards building a magneto-sensitive laser using NV centres for ultra-sensitive magnetometry was made. Direct measurements of stimulated emission from NV centre ensembles contained within a mm scale diamond were attempted but were inconclusive. Despite measuring a change in probe power using a pump-probe setup, the wavelength, power and temporal dependencies were not fully consistent with a measurement of stimulated emission. However, ODMR was successfully measured using the probe beam
Enhancing livestock and human health monitoring via analysis of electronic sensor data
Get PDFThis thesis presents a body of work involving novel algorithms for enhancing the effectiveness of low-cost sensors in monitoring applications. A holistic approach has been taken in this work in that modelling, simulation, and monitoring tools have been developed from scratch with a number of novel ideas. As its first contribution, the thesis presents a new simulation tool, WSNSIM - a tool for performance analysis of wireless sensor networks (WSN) formed by sensor nodes deployed on farm animals for monitoring of health and oestrus. In this application of wireless sensor networks, the mobility and herding patterns are modelled using statistical tools such as the Gamma density function, mean index of adequacy (MIA), exponential distribution, K-means clustering etc. to give rise to network simulation that is based on accurate herd behaviour. The simulation results are used in evaluation of novel protocol ideas customized to the needs of farm monitoring. The paper [153] presents a new simulation tool for performance analysis of wireless sensor networks (WSN) deployed on farm animals. The second and third key contributions of the thesis investigate monitoring of human body joints for the purpose of gait and upper limb motion assessment. Unlike the standard approach of marker-based joint monitoring for motion assessment, this work investigates the viability of the Kinect sensor for joint motion monitoring. To this end, two novel tools are developed that incorporate statistical, image processing and computer vision algorithms. The first tool GLSKEL is an intuitive 3D interface and kinematics model for continuous motion capture and analysis of human gait that can be useful for clinical practitioners. The second tool, JAFAKEC helps with tracking and calculation of joint angles based on point cloud data. This functionality can be very helpful for monitoring of the gait and arm motions of mobility-impaired patients using the Kinect sensor. This thesis also details the mathematical methods and algorithms applied on the point cloud to improve accuracy of the joint angle calculation.This thesis presents a body of work involving novel algorithms for enhancing the effectiveness of low-cost sensors in monitoring applications. A holistic approach has been taken in this work in that modelling, simulation, and monitoring tools have been developed from scratch with a number of novel ideas. As its first contribution, the thesis presents a new simulation tool, WSNSIM - a tool for performance analysis of wireless sensor networks (WSN) formed by sensor nodes deployed on farm animals for monitoring of health and oestrus. In this application of wireless sensor networks, the mobility and herding patterns are modelled using statistical tools such as the Gamma density function, mean index of adequacy (MIA), exponential distribution, K-means clustering etc. to give rise to network simulation that is based on accurate herd behaviour. The simulation results are used in evaluation of novel protocol ideas customized to the needs of farm monitoring. The paper [153] presents a new simulation tool for performance analysis of wireless sensor networks (WSN) deployed on farm animals. The second and third key contributions of the thesis investigate monitoring of human body joints for the purpose of gait and upper limb motion assessment. Unlike the standard approach of marker-based joint monitoring for motion assessment, this work investigates the viability of the Kinect sensor for joint motion monitoring. To this end, two novel tools are developed that incorporate statistical, image processing and computer vision algorithms. The first tool GLSKEL is an intuitive 3D interface and kinematics model for continuous motion capture and analysis of human gait that can be useful for clinical practitioners. The second tool, JAFAKEC helps with tracking and calculation of joint angles based on point cloud data. This functionality can be very helpful for monitoring of the gait and arm motions of mobility-impaired patients using the Kinect sensor. This thesis also details the mathematical methods and algorithms applied on the point cloud to improve accuracy of the joint angle calculation
Design and implementation of fractional order PID controllers for process control systems
Get PDFNew methods of designing Fractional Order PID (FOPID) controllers are developed for regulating product's purity in distillation columns. It is widely known that poorly tuned PID controllers lead to bad quality of products and accompanied reduction in profit margin in the process industry. In distillation columns, tight composition control of products with 98% purity level is not achievable with simple pressure controllers only due to sensitivity to disturbances. Therefore, FOPID controllers are proposed to solve these multivariable impurity problems. FOPID controllers have extra tuning parameters that can counteract effects of time delays in distillation columns if properly tuned. This property is exploited as a tool for improved performance. Original contributions of this thesis include the development of three new design methods for multivariable FOPID controllers and results are analysed using inverse maximum singular value of relevant sensitivity functions to assess robust stability. Several conventional PID controller design methods are also reviewed for the purpose of comparison. Thereafter, a decentralised FOPID control system is developed for multivariable systems based on plant's critical frequency point and results show improved performance over conventional PID controllers. The proposed critical frequency point method provides very easy-to-use tuning rules similar to Cohen-Coontuning rule for integer-order PID controllers. In addition, a new decentralised multivariable FOPID controller is also proposed based on Internal Model Control(IMC) method but settings are tuned using Biggest Log-magnitude Technique (BLT). This IMC-FOPID control design scheme overcomes the need for critical frequency point experiments. Another contribution of this thesis is the development of a novel discrete Fractional Order Predictive PI (FOPPI) control design scheme suitable for linear multivariable systems. Comparative study of these methods is presented.Simulation results prove that both top and bottoms products' purity of 98% are achievable with improved disturbance rejection when using the proposed FOPPI controller. In comparison, simpler FOPID control design schemes developed in continuous time are found to meet design objectives but at the expense of having a more conservative control action.New methods of designing Fractional Order PID (FOPID) controllers are developed for regulating product's purity in distillation columns. It is widely known that poorly tuned PID controllers lead to bad quality of products and accompanied reduction in profit margin in the process industry. In distillation columns, tight composition control of products with 98% purity level is not achievable with simple pressure controllers only due to sensitivity to disturbances. Therefore, FOPID controllers are proposed to solve these multivariable impurity problems. FOPID controllers have extra tuning parameters that can counteract effects of time delays in distillation columns if properly tuned. This property is exploited as a tool for improved performance. Original contributions of this thesis include the development of three new design methods for multivariable FOPID controllers and results are analysed using inverse maximum singular value of relevant sensitivity functions to assess robust stability. Several conventional PID controller design methods are also reviewed for the purpose of comparison. Thereafter, a decentralised FOPID control system is developed for multivariable systems based on plant's critical frequency point and results show improved performance over conventional PID controllers. The proposed critical frequency point method provides very easy-to-use tuning rules similar to Cohen-Coontuning rule for integer-order PID controllers. In addition, a new decentralised multivariable FOPID controller is also proposed based on Internal Model Control(IMC) method but settings are tuned using Biggest Log-magnitude Technique (BLT). This IMC-FOPID control design scheme overcomes the need for critical frequency point experiments. Another contribution of this thesis is the development of a novel discrete Fractional Order Predictive PI (FOPPI) control design scheme suitable for linear multivariable systems. Comparative study of these methods is presented.Simulation results prove that both top and bottoms products' purity of 98% are achievable with improved disturbance rejection when using the proposed FOPPI controller. In comparison, simpler FOPID control design schemes developed in continuous time are found to meet design objectives but at the expense of having a more conservative control action
The development of a satellite-enabled tool for offshore wind resource optimisation
Get PDFThe actual offshore wind farms are mainly located near the shore, only tens of kilometres offshore. The development of this sector is forecasting offshore wind farms over deeper seas. This fact is complicating and increasing the cost of a wind resource monitoring campaign by meteorological masts. Hence, the industry has been searching for cheaper technologies capable to measure wind vectors on deep seas, such as floating LIDAR or satellites.;The European project NORSEWInD created wind atlases from satellite measurements for the North, Irish and Baltic Seas. After that project, the creation of software to undertake wind resource assessments by satellites was aimed by a new project named WindRes. This aim was the starting point of the present thesis.;New software was created which merges knowledge from different fields, microwave remote sensing, satellite Earth Observation and wind resource assessment. The capabilities of the tool, and more important, the capabilities of satellites to match requirements by the wind industry were tested. In this initial analysis, advantages and disadvantages were identified as well as lack of knowledge. Two main points were concluded to need further research; the vertical extrapolation of wind vectors, and the creation of climatology from satellites measurements.;In a second analysis, different extrapolation methods suggested in the literature were tested. These include methods to calculate aerodynamic surface roughness length (z0) and friction velocity, (u*). The logarithmic law, the law to calculate wind speed in the surface layer at different heights, is dependent on these two parameters, z0 and u*. Since previous methodologies were found to mismatch in situ measurements, a new expression for z0 was developed.;New equations were reached by application of knowledge in oceanography and boundary layer meteorology. Although a definitive expression was not reached, the high z0 values found under young waves conditions suggested the need of a complete logarithmic law for offshore environments. Results pointed the necessity to include the energy transfer from wind to the sea into the logarithmic law.The actual offshore wind farms are mainly located near the shore, only tens of kilometres offshore. The development of this sector is forecasting offshore wind farms over deeper seas. This fact is complicating and increasing the cost of a wind resource monitoring campaign by meteorological masts. Hence, the industry has been searching for cheaper technologies capable to measure wind vectors on deep seas, such as floating LIDAR or satellites.;The European project NORSEWInD created wind atlases from satellite measurements for the North, Irish and Baltic Seas. After that project, the creation of software to undertake wind resource assessments by satellites was aimed by a new project named WindRes. This aim was the starting point of the present thesis.;New software was created which merges knowledge from different fields, microwave remote sensing, satellite Earth Observation and wind resource assessment. The capabilities of the tool, and more important, the capabilities of satellites to match requirements by the wind industry were tested. In this initial analysis, advantages and disadvantages were identified as well as lack of knowledge. Two main points were concluded to need further research; the vertical extrapolation of wind vectors, and the creation of climatology from satellites measurements.;In a second analysis, different extrapolation methods suggested in the literature were tested. These include methods to calculate aerodynamic surface roughness length (z0) and friction velocity, (u*). The logarithmic law, the law to calculate wind speed in the surface layer at different heights, is dependent on these two parameters, z0 and u*. Since previous methodologies were found to mismatch in situ measurements, a new expression for z0 was developed.;New equations were reached by application of knowledge in oceanography and boundary layer meteorology. Although a definitive expression was not reached, the high z0 values found under young waves conditions suggested the need of a complete logarithmic law for offshore environments. Results pointed the necessity to include the energy transfer from wind to the sea into the logarithmic law
Power system restorations assisted by wind power
Get PDFThis thesis investigates power systems restoration procedure and the possibility of using wind power to assist restorations. Three main factors motivate this approach: the sharp growth on wind power production during recent years, the absence of wind power on restoration procedures, and recent blackouts cases which stability issues delayed the restoration procedure.;Stability studies are the base of this investigation, where a series of tools are proposed and developed due to the disparate condition of a restoration procedure.The first tool is a power flow routine, where stochastic simulations address wind speed's randomness. This computational program calculates indexes of collapse for voltage stability.;This computational routine also encompasses a methodology built from an energy function tool for visualizing power systems' vulnerable and robust areas.This thesis applies the tool for restoration analysis, where its validation has been published on an academic journal. This thesis also proposes a novel methodology for visualizing the robustness areas, which uses the energy function output to form a graphical representation as the system diagram's background.;This thesis designs procedures and controllers for the dynamic simulation analysis. The first is the definition of a procedure used to simulate the synchronization of wind farms during restorations. This procedure aims to mitigate impacts caused by wind farms on power systems, where two loop controls achieve the desired response. Finally, one can find an initialization procedure for wind turbines, regarding restoration conditions.;The robustness areas tool validation shows that one can achieve positive results on angular stability by reinforcing vulnerable areas. The guidelines proposed by the robustness areas tool test the Brazilian system operator's restoration procedure. A number of analysis and simulations assess the proposed approach efficiency.The IEEE 30 bus system, which is a benchmark for stability studies, shows the impact of wind power on restorations. Part of the Brazilian power system addresses the proposed methodology on a real case scenario.;Finally, this thesis presents a list of recommendations, which intends to guide future works to include wind power on restorations and to extend the proposed approach to other power systems.This thesis investigates power systems restoration procedure and the possibility of using wind power to assist restorations. Three main factors motivate this approach: the sharp growth on wind power production during recent years, the absence of wind power on restoration procedures, and recent blackouts cases which stability issues delayed the restoration procedure.;Stability studies are the base of this investigation, where a series of tools are proposed and developed due to the disparate condition of a restoration procedure.The first tool is a power flow routine, where stochastic simulations address wind speed's randomness. This computational program calculates indexes of collapse for voltage stability.;This computational routine also encompasses a methodology built from an energy function tool for visualizing power systems' vulnerable and robust areas.This thesis applies the tool for restoration analysis, where its validation has been published on an academic journal. This thesis also proposes a novel methodology for visualizing the robustness areas, which uses the energy function output to form a graphical representation as the system diagram's background.;This thesis designs procedures and controllers for the dynamic simulation analysis. The first is the definition of a procedure used to simulate the synchronization of wind farms during restorations. This procedure aims to mitigate impacts caused by wind farms on power systems, where two loop controls achieve the desired response. Finally, one can find an initialization procedure for wind turbines, regarding restoration conditions.;The robustness areas tool validation shows that one can achieve positive results on angular stability by reinforcing vulnerable areas. The guidelines proposed by the robustness areas tool test the Brazilian system operator's restoration procedure. A number of analysis and simulations assess the proposed approach efficiency.The IEEE 30 bus system, which is a benchmark for stability studies, shows the impact of wind power on restorations. Part of the Brazilian power system addresses the proposed methodology on a real case scenario.;Finally, this thesis presents a list of recommendations, which intends to guide future works to include wind power on restorations and to extend the proposed approach to other power systems
An investigation into the sensitivity of the River Dee catchment to climate changes and the implications of this for the Galloway Hydroelectric Power Scheme
No full textEffective future water resources management is key to meeting the challenges of the water-energy nexus. Climate change is often highlighted as a risk to future resources, yet the impact of climate change on water resources can also be localised, complex and multifaceted, bringing potentially both benefit and threat to systems. The aim of this research is to understand response of rivers to future climate to assess potential opportunities or threat to natural resources for the Galloway Hydroelectric Power Station.;Hydrological and meteorological data was assessed for the River Dee over the past 30 years (1985 to 2014) to identify trends by which responses of rivers to changing local climate parameters can be better understood. Sensitivity analysis was conducted to investigate and isolate which climatic factors force hydrological changes in the area. Results are assessed alongside climate projections, to understand how future climate changes will impact river flow, and thus future hydropower.;Results show that the River Dee is responsive to temperature exclusively in the dry, summer months. It is understood that temperatures in the region do not reach high enough to trigger a hydrological response during the winter months i.e. catchments remain wet and saturated. This picture presents risks for dry season river flow, as climate projections suggest an annual increase to temperatures, presenting the opportunity for raised summer temperatures to significantly reduce flow volume.;Results also show the River Dee is responsive to evapotranspiration and precipitation, dominantly, throughout the year. If winter flows rise to the projected rates, it may lead to reservoirs reaching storage capacity quicker and therefore buffer the opportunity to harness future water resource to full potential.;These results, coupled with 2050 and 2080 climate projections, should not necessarily be cause for concern, but a trigger for awareness raising in management of water resource practices.Effective future water resources management is key to meeting the challenges of the water-energy nexus. Climate change is often highlighted as a risk to future resources, yet the impact of climate change on water resources can also be localised, complex and multifaceted, bringing potentially both benefit and threat to systems. The aim of this research is to understand response of rivers to future climate to assess potential opportunities or threat to natural resources for the Galloway Hydroelectric Power Station.;Hydrological and meteorological data was assessed for the River Dee over the past 30 years (1985 to 2014) to identify trends by which responses of rivers to changing local climate parameters can be better understood. Sensitivity analysis was conducted to investigate and isolate which climatic factors force hydrological changes in the area. Results are assessed alongside climate projections, to understand how future climate changes will impact river flow, and thus future hydropower.;Results show that the River Dee is responsive to temperature exclusively in the dry, summer months. It is understood that temperatures in the region do not reach high enough to trigger a hydrological response during the winter months i.e. catchments remain wet and saturated. This picture presents risks for dry season river flow, as climate projections suggest an annual increase to temperatures, presenting the opportunity for raised summer temperatures to significantly reduce flow volume.;Results also show the River Dee is responsive to evapotranspiration and precipitation, dominantly, throughout the year. If winter flows rise to the projected rates, it may lead to reservoirs reaching storage capacity quicker and therefore buffer the opportunity to harness future water resource to full potential.;These results, coupled with 2050 and 2080 climate projections, should not necessarily be cause for concern, but a trigger for awareness raising in management of water resource practices
Keeper : a novel and critical reflection on historical fiction as a genre
Get PDFPreviously held under moratorium from 11 February 2019 until 20 April 2022.This practice-led PhD thesis consists of two sections: a creative element and criticalcommentary. ‘Keeper’ is a historical crime fiction novel. Set in the slums of RegencyLondon, the story is about the effects of trauma on the individual, and gentrification on thecommunity. It looks at what family means for different people, and how the ties of blood andfriendship are tested.Both third-person and first-person focalisation are employed, as the story is told fromtwo different perspectives – one that of an injured soldier who is relatively new to therookery, and the other an orphaned girl who has never seen the world beyond it. The third-person voice is connected to and often overwhelmed by the past, and this is reflected in theuse of the past tense, which contrasts with the immediacy of first-person present tense. Thenarrative utilises the investigation of a murder to scrutinise the development of British societyin the early nineteenth century, through a fictional examination of historical events and theirsocial consequences. An author’s note provides insight into the research process.The critical commentary explores the origins and theoretical response to the historicalnovel. The commentary touches on the nineteenth century split between academic historyand historical fiction, which promoted an artificial opposition between history and fiction,and discusses the lack of scholarly definitions of the genre. Issues surrounding theclassifications that are available are examined, before a new definition is proposed.The practical challenges of the historical novel are explored through interviews withsix authors of historical fiction. An analysis of these interview transcripts and HilaryMantel’s Reith Lectures is used to argue that the writers’ approach to research, andengagement with sources, demonstrates a working methodology from which aspiring writersmay learn.This practice-led PhD thesis consists of two sections: a creative element and criticalcommentary. ‘Keeper’ is a historical crime fiction novel. Set in the slums of RegencyLondon, the story is about the effects of trauma on the individual, and gentrification on thecommunity. It looks at what family means for different people, and how the ties of blood andfriendship are tested.Both third-person and first-person focalisation are employed, as the story is told fromtwo different perspectives – one that of an injured soldier who is relatively new to therookery, and the other an orphaned girl who has never seen the world beyond it. The third-person voice is connected to and often overwhelmed by the past, and this is reflected in theuse of the past tense, which contrasts with the immediacy of first-person present tense. Thenarrative utilises the investigation of a murder to scrutinise the development of British societyin the early nineteenth century, through a fictional examination of historical events and theirsocial consequences. An author’s note provides insight into the research process.The critical commentary explores the origins and theoretical response to the historicalnovel. The commentary touches on the nineteenth century split between academic historyand historical fiction, which promoted an artificial opposition between history and fiction,and discusses the lack of scholarly definitions of the genre. Issues surrounding theclassifications that are available are examined, before a new definition is proposed.The practical challenges of the historical novel are explored through interviews withsix authors of historical fiction. An analysis of these interview transcripts and HilaryMantel’s Reith Lectures is used to argue that the writers’ approach to research, andengagement with sources, demonstrates a working methodology from which aspiring writersmay learn
"Talkin' 'Bout Regeneration" : exploring place consumption, consumer and spatial vulnerability in a neighbourhood community
No full textThis thesis was previously held under moratorium from 21 September 2018 until 21 September 2023This thesis examines the regeneration of an established neighbourhood community, asubject of close scrutiny by both the media and local authorities. The overall aim ofthis research is to provide a contemporary consumer perspective of gentrification byexploring the lived experience of vulnerable consumers who reside in an area ofcomplex transience and temporality. Grounded within Consumer Culture Theory(CCT) this research incorporates literature streams from communities of consumption,place literature and consumer vulnerability. Previous research on consumption communities has focused on the brands and products that bring these people together, however, this research gleans the lessons learned from such studies and applies this theory to the traditional neighbourhood community. In addition to consumer research, literature surveying urban regeneration, housing studies and gentrification is explored. As its research context: Raploch, Stirling provides the backdrop for this ethnography as it is consistently placed in the bottom 5% of deprived areas in Scotland. Given its prominence in the Scottish media and vibrant historical background, Raploch amalgamates numerous characteristics of contemporary urban regeneration projects. At its core this thesis makes four key contributions to knowledge; firstly, it compares the real and imagined lived experience of residents and outsiders and how these perceptions are shaped by the representations from the media and the wider city population. Secondly, it examines a consumption community brought together by geographic location and third place attachment rather than brands, products or services. Thirdly, through the changes in the physical community and new residents entering the neighbourhood, the collective and spatial vulnerability of Raploch and its residents is explored. Lastly, this thesis considers the gentrification process in this area and concludes that it must be reconceptualised to fully explain contexts where land is not a limited resource and development projects where social housing stock is compulsory.This thesis examines the regeneration of an established neighbourhood community, asubject of close scrutiny by both the media and local authorities. The overall aim ofthis research is to provide a contemporary consumer perspective of gentrification byexploring the lived experience of vulnerable consumers who reside in an area ofcomplex transience and temporality. Grounded within Consumer Culture Theory(CCT) this research incorporates literature streams from communities of consumption,place literature and consumer vulnerability. Previous research on consumption communities has focused on the brands and products that bring these people together, however, this research gleans the lessons learned from such studies and applies this theory to the traditional neighbourhood community. In addition to consumer research, literature surveying urban regeneration, housing studies and gentrification is explored. As its research context: Raploch, Stirling provides the backdrop for this ethnography as it is consistently placed in the bottom 5% of deprived areas in Scotland. Given its prominence in the Scottish media and vibrant historical background, Raploch amalgamates numerous characteristics of contemporary urban regeneration projects. At its core this thesis makes four key contributions to knowledge; firstly, it compares the real and imagined lived experience of residents and outsiders and how these perceptions are shaped by the representations from the media and the wider city population. Secondly, it examines a consumption community brought together by geographic location and third place attachment rather than brands, products or services. Thirdly, through the changes in the physical community and new residents entering the neighbourhood, the collective and spatial vulnerability of Raploch and its residents is explored. Lastly, this thesis considers the gentrification process in this area and concludes that it must be reconceptualised to fully explain contexts where land is not a limited resource and development projects where social housing stock is compulsory
Mechanical analysis and simulation of the nitinol ring-stent : assessing the radial strength, fatigue safety and compaction strains
Get PDFThis thesis was previously held under moratorium from 10th September 2018 until 10th September 2023.Disease of the vascular system is often treated by ‘minimally invasive’ endovascular methods, which are less traumatic than conventional ‘open surgery’. The endovascular treatments, including implants, are delivered to the target area by catheter devices. The aorta, the largest artery in the body which stems from the heart, is susceptible to aneurysms and dissection of the arterial wall layers, which can both be fatal if left untreated. These specific conditions are often treated with endovascular stent-graft implants: flexible polymer conduits supported by metallic structures. Vascutek, a company based near Glasgow, is unique in designing and producing stent-grafts based on the ‘ringstent’ technology: the structural annular components being formed of multiple turns of a superelastic alloy called Nitinol. Competitors in the stent-graft market mainly implement the more common ‘Z-stent’ structure, also usually with Nitinol. The work of this thesis addresses the requirement of Vascutek to have advanced methods of analysing the mechanical performance of ring-stents in terms of: the loading which they apply to vessels; their fatigue performance in the pulsatile environment of the cardiac cycle, and the ability to compact into small diameter delivery systems without incurring detrimental levels of material strain. Building on previous efforts at The University of Strathclyde, the work presented here represents the first complete development, and thorough validation, of a Finite Element simulation methodology which captures the ‘bundle’ geometry and mechanical response of the multiple-strand ring-stent technology. A unique method has been devised to capture and simulate the non-linear response of human aortic tissue, specific to thoracic or abdominal locations and for a range of patient ages. Currently, there exists no standard approach in the industry to mechanically represent artery, partly due to the variability and difficulty of obtaining data. The bespoke Finite Element Analysis capabilities have provided the first quantification of the ‘radial strength’ of ring-stents, and knowledge of how the radial force is distributed on the artery wall. This includes evidence that if devices are implanted at high ‘oversize’, distribution is less uniform and there is no significant increase in total radial force. Furthermore; the first reliable simulation of the ring-stents interacting with the non-linear arterial response has been executed; the results showing a significant reduction to the vessels’ physiological motion and a corresponding increase in factor of safety when compared to assessments made assuming linear elastic artery. The latter goes beyond current standard practice for fatigue, and will allow justification of design of new products which are in development. An understanding, and verification, of how classic beam theory can be used to inform ring-stent design has also been provided. The methodology devised here has also been used to inform and analyse a component level Nitinol wire fatigue-to-failure test programme required to attain the strain based limits, against which the device simulations are assessed. This combined work (empirical side undertaken by colleagues at Vascutek) is a unique study, which successfully defines the fatigue strength of Nitinol wire at multiple ‘non-zero’ mean-strain states. Regarding the analysis on compaction of ring-stents, geometric mathematical tools and Micro Computed Tomography X-Ray imaging have been implemented in the design process, providing fidelity in measuring strain levels and insight to optimise the designs to allow the highly desirable reduction in catheter profile. To truly optimise the profile of delivery systems, a more complete understanding of the effects of straining Nitinol to high levels is required, which is ongoing in further research collaborations with The University of Strathclyde.Disease of the vascular system is often treated by ‘minimally invasive’ endovascular methods, which are less traumatic than conventional ‘open surgery’. The endovascular treatments, including implants, are delivered to the target area by catheter devices. The aorta, the largest artery in the body which stems from the heart, is susceptible to aneurysms and dissection of the arterial wall layers, which can both be fatal if left untreated. These specific conditions are often treated with endovascular stent-graft implants: flexible polymer conduits supported by metallic structures. Vascutek, a company based near Glasgow, is unique in designing and producing stent-grafts based on the ‘ringstent’ technology: the structural annular components being formed of multiple turns of a superelastic alloy called Nitinol. Competitors in the stent-graft market mainly implement the more common ‘Z-stent’ structure, also usually with Nitinol. The work of this thesis addresses the requirement of Vascutek to have advanced methods of analysing the mechanical performance of ring-stents in terms of: the loading which they apply to vessels; their fatigue performance in the pulsatile environment of the cardiac cycle, and the ability to compact into small diameter delivery systems without incurring detrimental levels of material strain. Building on previous efforts at The University of Strathclyde, the work presented here represents the first complete development, and thorough validation, of a Finite Element simulation methodology which captures the ‘bundle’ geometry and mechanical response of the multiple-strand ring-stent technology. A unique method has been devised to capture and simulate the non-linear response of human aortic tissue, specific to thoracic or abdominal locations and for a range of patient ages. Currently, there exists no standard approach in the industry to mechanically represent artery, partly due to the variability and difficulty of obtaining data. The bespoke Finite Element Analysis capabilities have provided the first quantification of the ‘radial strength’ of ring-stents, and knowledge of how the radial force is distributed on the artery wall. This includes evidence that if devices are implanted at high ‘oversize’, distribution is less uniform and there is no significant increase in total radial force. Furthermore; the first reliable simulation of the ring-stents interacting with the non-linear arterial response has been executed; the results showing a significant reduction to the vessels’ physiological motion and a corresponding increase in factor of safety when compared to assessments made assuming linear elastic artery. The latter goes beyond current standard practice for fatigue, and will allow justification of design of new products which are in development. An understanding, and verification, of how classic beam theory can be used to inform ring-stent design has also been provided. The methodology devised here has also been used to inform and analyse a component level Nitinol wire fatigue-to-failure test programme required to attain the strain based limits, against which the device simulations are assessed. This combined work (empirical side undertaken by colleagues at Vascutek) is a unique study, which successfully defines the fatigue strength of Nitinol wire at multiple ‘non-zero’ mean-strain states. Regarding the analysis on compaction of ring-stents, geometric mathematical tools and Micro Computed Tomography X-Ray imaging have been implemented in the design process, providing fidelity in measuring strain levels and insight to optimise the designs to allow the highly desirable reduction in catheter profile. To truly optimise the profile of delivery systems, a more complete understanding of the effects of straining Nitinol to high levels is required, which is ongoing in further research collaborations with The University of Strathclyde
K+ as a privileged facilitator of electron transfer reactions?
Get PDFThis thesis was previously held under moratorium from 22 August 2019 until 22 August 2024.The first part of these studies examines the role of KOtBu in electron transfer reactions when DMF is the solvent. Here, deprotonation of DMF leads to carbamoyl anion 1, which has been
previously suggested to be an electron donor; in contrast, this thesis proposes the formation of the DMF dimer dianion 4 as the electron donor, based on experimental investigations.[1] Scheme 1. KOtBu-mediated DMF dimerisation and electron donor formation.[1] [Figure in thesis text] An extension of the capability for KOtBu to act as a powerful base is illustrated with deprotonation of aromatic and aliphatic aldehydes and formamides such as 5 and 7. This reaction type could be important for understanding the process which underpins formation of carbohydrates in the prebiotic era. Scheme 2. C-C bond formation promoted by strong bases. [Figure in thesis text] Long-standing controversial reports of electron transfer from KOtBu to benzophenone have been studied and resolved. These results now establish that a complex is formed between the two reagents, with the potassium ion providing the linkage. Photoactivation at room temperature by irradiation at defined wavelength (365 or 400 nm), or even by winter daylight, leads to the development of the blue colour of the potassium salt of benzophenone ketyl anion, whereas no reaction is observed when the reaction mixture is maintained in darkness or when NaOtBu is used.[2] Scheme 3. Photoreduction of benzophenone by KOtBu.[2] [Figure in thesis text] The second part of this study deploys KH in electron transfer reactions. Whilst in THF, KH promotes a concerted nucleophilic aromatic substitution, in benzene it promotes electron transfer reactions via organic electron donor formation. Here, again KH was found to have unique properties, different from NaH.[3] Scheme 4. Example of radical pathways triggered by KH in benzene as solvent. [3] [Figure in thesis text] The last part of this study reveals an unprecedented reactivity of K metal with benzene in presence of π-activators. Potassium cation is found to be more effective than sodium cation, promoting SET and reductive coupling of benzene leading to coupled product 11. The reaction in the absence of any cation source shows no reaction. Scheme 5. K metal determines homocoupling of benzene in presence of selected additives. [Figure in thesis text]The first part of these studies examines the role of KOtBu in electron transfer reactions when DMF is the solvent. Here, deprotonation of DMF leads to carbamoyl anion 1, which has been
previously suggested to be an electron donor; in contrast, this thesis proposes the formation of the DMF dimer dianion 4 as the electron donor, based on experimental investigations.[1] Scheme 1. KOtBu-mediated DMF dimerisation and electron donor formation.[1] [Figure in thesis text] An extension of the capability for KOtBu to act as a powerful base is illustrated with deprotonation of aromatic and aliphatic aldehydes and formamides such as 5 and 7. This reaction type could be important for understanding the process which underpins formation of carbohydrates in the prebiotic era. Scheme 2. C-C bond formation promoted by strong bases. [Figure in thesis text] Long-standing controversial reports of electron transfer from KOtBu to benzophenone have been studied and resolved. These results now establish that a complex is formed between the two reagents, with the potassium ion providing the linkage. Photoactivation at room temperature by irradiation at defined wavelength (365 or 400 nm), or even by winter daylight, leads to the development of the blue colour of the potassium salt of benzophenone ketyl anion, whereas no reaction is observed when the reaction mixture is maintained in darkness or when NaOtBu is used.[2] Scheme 3. Photoreduction of benzophenone by KOtBu.[2] [Figure in thesis text] The second part of this study deploys KH in electron transfer reactions. Whilst in THF, KH promotes a concerted nucleophilic aromatic substitution, in benzene it promotes electron transfer reactions via organic electron donor formation. Here, again KH was found to have unique properties, different from NaH.[3] Scheme 4. Example of radical pathways triggered by KH in benzene as solvent. [3] [Figure in thesis text] The last part of this study reveals an unprecedented reactivity of K metal with benzene in presence of π-activators. Potassium cation is found to be more effective than sodium cation, promoting SET and reductive coupling of benzene leading to coupled product 11. The reaction in the absence of any cation source shows no reaction. Scheme 5. K metal determines homocoupling of benzene in presence of selected additives. [Figure in thesis text
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