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Users' relevance criteria for videos in leisure contexts
Get PDFRelevance is a fundamental concept in the Information Retrieval field. As part of the relevance judgment process, users apply several relevance criteria to judge retrieved objects. Relevance judgments and the criteria used to make these judgments are known to be dynamic. Many research attempted to explore relevance criteria users apply when making relevance judgment decisions and examine the dynamic selection of relevance criteria at different stages of the search process. Previous relevance criteria studies focussed on work contexts and the information judged was mainly in text format; with the result that little is known about relevance criteria and its dynamic aspects when applied in leisure contexts, specifically for video content. The purpose of this research is to understand how typical users of YouTube judge the relevance of videos in leisure contexts; what are the reasons users give when judging video material as relevant or not relevant? Furthermore, the research investigates the dynamic aspects of relevance criteria by examining the differences in relevance criteria at the stages of selecting and viewing videos for leisure. This research encompasses two main studies. In the first study, a naturalistic diary was performed in which 30 participants completed diaries providing details on their video relevance criteria. In the second study, 24 participants were asked to search YouTube for leisure purposes followed by a semi-structured interview to elicit relevance criteria usage at different stages of the search process. In total, 28 relevance criteria were identified through the analyses of the diaries' contents and they were grouped into eight categories. The findings revealed that criteria related to the content of the video are the most dominant group of criteria with Topicality being the most dominant criterion. There is a considerable overlap between leisure relevance criteria and previous relevance criteria studies in academic or work-related contexts, but the importance of these criteria varies among different contexts. New criteria, e.g. Habit, emerged from the data which tend to be more related to leisure contexts. The findings of the dynamic use of relevance criteria study showed significant differences between the selecting and viewing stages in term of the use of relevance criteria with, some criteria being preferred in the selection stage while others are more important at the viewing stage of video interaction. The findings also demonstrated that applying different methods (naturalistic diary study and recorded sessions with interviews) revealed similar and consistent findings.This research attempted to enrich the current literature by investigating users' video relevance criteria in leisure contexts. Understanding the changes in relevance criteria during the search process provides new insights into the dynamic aspects of relevance judgment and aids the design of information retrieval systems.Relevance is a fundamental concept in the Information Retrieval field. As part of the relevance judgment process, users apply several relevance criteria to judge retrieved objects. Relevance judgments and the criteria used to make these judgments are known to be dynamic. Many research attempted to explore relevance criteria users apply when making relevance judgment decisions and examine the dynamic selection of relevance criteria at different stages of the search process. Previous relevance criteria studies focussed on work contexts and the information judged was mainly in text format; with the result that little is known about relevance criteria and its dynamic aspects when applied in leisure contexts, specifically for video content. The purpose of this research is to understand how typical users of YouTube judge the relevance of videos in leisure contexts; what are the reasons users give when judging video material as relevant or not relevant? Furthermore, the research investigates the dynamic aspects of relevance criteria by examining the differences in relevance criteria at the stages of selecting and viewing videos for leisure. This research encompasses two main studies. In the first study, a naturalistic diary was performed in which 30 participants completed diaries providing details on their video relevance criteria. In the second study, 24 participants were asked to search YouTube for leisure purposes followed by a semi-structured interview to elicit relevance criteria usage at different stages of the search process. In total, 28 relevance criteria were identified through the analyses of the diaries' contents and they were grouped into eight categories. The findings revealed that criteria related to the content of the video are the most dominant group of criteria with Topicality being the most dominant criterion. There is a considerable overlap between leisure relevance criteria and previous relevance criteria studies in academic or work-related contexts, but the importance of these criteria varies among different contexts. New criteria, e.g. Habit, emerged from the data which tend to be more related to leisure contexts. The findings of the dynamic use of relevance criteria study showed significant differences between the selecting and viewing stages in term of the use of relevance criteria with, some criteria being preferred in the selection stage while others are more important at the viewing stage of video interaction. The findings also demonstrated that applying different methods (naturalistic diary study and recorded sessions with interviews) revealed similar and consistent findings.This research attempted to enrich the current literature by investigating users' video relevance criteria in leisure contexts. Understanding the changes in relevance criteria during the search process provides new insights into the dynamic aspects of relevance judgment and aids the design of information retrieval systems
The behaviour of charge on the surface of polymeric materials
Get PDFIn the high voltage industry one of the factors limiting the performance of a pulse power system is the build-up of charge on the surface of the insulators. In these systems solid insulators are used to support the conductors. When operating pulse power systems in repetitive mode, the accumulation of charge on the insulators after each pulse can promote "surface flashover" and cannot be ignored as a limiting factor in the design of the system.The aim of this project was to enhance knowledge of the effect of accumulated charge on the surface conductivity, the surface charging/discharging behaviour and the surface charge decay behaviour of polymeric insulators. The project was carried out in 2 stages.Firstly surface charging/discharging transient currents were observed using a concentric cylindrical measurement system for uncharged PMMA and PMMA samples charged by exposure to corona. The charging/discharging transients were analysed to characterise possible conduction mechanisms and the DC steady state currents were used to calculate the surface conductivities. Charging the sample surfaces with corona led to an increase in the surface conductivities of the samples. The behaviour of the charging/discharging transients were complex and fitted well against 3 and 4 term exponential functions. Differences in behaviour were also observed due to sample thickness.;In the second stage of the project surface charge decay measurements were performed on PMMA samples that were subjected to corona charging. This was done to determine the relative importance of surface conductivity and charge neutralisation to the decay of surface charge. A novel charge probe based on varactors was developed and calibrated to perform these measurements. This system was novel in its use on measurements of surface charge on polymeric materials. The measured surface potentials from the varactor probe were used to calculate the surface charge density distributions. It was observed that most of the charge accumulates near the electrodes. Analysis of the total surface charge showed that the rate of charge decay was higher when the decay occurs through the surface conduction mechanism as compared to conduction through gas neutralisation, where no significant charge decay was observed. The rates of charge decay for thin and thick samples, which were corona charged at a grid voltage of 1 kV, were observed to be 0.027 {cedil}{9D}{9E}{aelig}C/min and 0.048 {cedil}{9D}{9E}{aelig}C/min, respectively, for neutralisation through the gas; while the corresponding rates of charge decay through surface conduction were observed to be 0.096 {cedil}{9D}{9E}{aelig}C/min and 0.18 {cedil}{9D}{9E}{aelig}C/min, respectively. Evidence of the crossover effect has been observed in certain geometries. Correlations have been made between the charge decay measurements and the transient behaviours observed in the first part of the project. The charge decay behaviours were found to be in good correlation with the surface conductivities observed for corona treated samples where an external field was applied across the sample surface.In the high voltage industry one of the factors limiting the performance of a pulse power system is the build-up of charge on the surface of the insulators. In these systems solid insulators are used to support the conductors. When operating pulse power systems in repetitive mode, the accumulation of charge on the insulators after each pulse can promote "surface flashover" and cannot be ignored as a limiting factor in the design of the system.The aim of this project was to enhance knowledge of the effect of accumulated charge on the surface conductivity, the surface charging/discharging behaviour and the surface charge decay behaviour of polymeric insulators. The project was carried out in 2 stages.Firstly surface charging/discharging transient currents were observed using a concentric cylindrical measurement system for uncharged PMMA and PMMA samples charged by exposure to corona. The charging/discharging transients were analysed to characterise possible conduction mechanisms and the DC steady state currents were used to calculate the surface conductivities. Charging the sample surfaces with corona led to an increase in the surface conductivities of the samples. The behaviour of the charging/discharging transients were complex and fitted well against 3 and 4 term exponential functions. Differences in behaviour were also observed due to sample thickness.;In the second stage of the project surface charge decay measurements were performed on PMMA samples that were subjected to corona charging. This was done to determine the relative importance of surface conductivity and charge neutralisation to the decay of surface charge. A novel charge probe based on varactors was developed and calibrated to perform these measurements. This system was novel in its use on measurements of surface charge on polymeric materials. The measured surface potentials from the varactor probe were used to calculate the surface charge density distributions. It was observed that most of the charge accumulates near the electrodes. Analysis of the total surface charge showed that the rate of charge decay was higher when the decay occurs through the surface conduction mechanism as compared to conduction through gas neutralisation, where no significant charge decay was observed. The rates of charge decay for thin and thick samples, which were corona charged at a grid voltage of 1 kV, were observed to be 0.027 {cedil}{9D}{9E}{aelig}C/min and 0.048 {cedil}{9D}{9E}{aelig}C/min, respectively, for neutralisation through the gas; while the corresponding rates of charge decay through surface conduction were observed to be 0.096 {cedil}{9D}{9E}{aelig}C/min and 0.18 {cedil}{9D}{9E}{aelig}C/min, respectively. Evidence of the crossover effect has been observed in certain geometries. Correlations have been made between the charge decay measurements and the transient behaviours observed in the first part of the project. The charge decay behaviours were found to be in good correlation with the surface conductivities observed for corona treated samples where an external field was applied across the sample surface
Colloidal quantum dot and hybrid lasers
Get PDFThis thesis presents research on solution-processed semiconductor lasers, with an emphasis on colloidal quantum dot (CQD) lasers, aimed at progressing the state of the art of the technology. A particular focus is placed on demonstrating such lasers under long (>nanosecond) pulse pumping in order to bring this device technology closer to applications. Alloyed-core CdSSe CQDs with a ZnS outer shell that emit in the visible are studied. These were prepared in a solid-state thin-film overcoated with a polymeric cladding (polyvinyl alcohol or PVA) to demonstrate a distributed feedback(DFB) laser having a bilayer waveguide structure. It is shown that the PVA symmetrises the laser structure and reduces the modal losses, in turn enabling the lowest threshold operation in the nanosecond regime for CQD lasers at the time;13.5 μJ/cm2 at 5 ns. The format is also beneficial for the photostability of the laser. The CQDs are also demonstrated as the gain material of a robust, orange-emitting Vertical-Cavity Surface-Emitting Laser (VCSEL). Oscillation threshold comprised between 1 and 20 mJ/cm2 for 5ns pump pulse duration are obtained. For a broad area excitation (250 μm at 1/e2 radius), the operation is highly multimode and characterised by spatio-temporal instabilities. When pumped with a spot size at or below 100μm in radius, the VCSEL is observed to be single mode for low pump energies while additional longitudinal modes, as well as transverse mode,appear as the pumping level is increased. A study of the polarisation of the CQD laser emission for different polarisation of the pump was carried out and the Stokes parameters calculated. Results show that the pump polarisation has no significant effect on the VCSEL polarisation. While the bulk of the research concerns CQDs, two types of organic semiconductors were also applied to the aforementioned DFB laser structure. Poly(paraphenylenevinylene) (PPV) copolymer Super Yellow leading to what is to the best of our knowledge, the only case of completely ambient lasing using Super Yellow. Refractive index sensing with the laser was attempted and results are summarised. The second type in fact consisted of two organic semiconductor materials from the same novel family of autofluorescence molecules respectively named Blue 4 and Blue 6. These are investigated for the first time as laser materials. Both materialsshow signs of random lasing when prepared in a solid-state film. Single mode lasing in distributed feedback format is also demonstrated with Blue 4.This thesis presents research on solution-processed semiconductor lasers, with an emphasis on colloidal quantum dot (CQD) lasers, aimed at progressing the state of the art of the technology. A particular focus is placed on demonstrating such lasers under long (>nanosecond) pulse pumping in order to bring this device technology closer to applications. Alloyed-core CdSSe CQDs with a ZnS outer shell that emit in the visible are studied. These were prepared in a solid-state thin-film overcoated with a polymeric cladding (polyvinyl alcohol or PVA) to demonstrate a distributed feedback(DFB) laser having a bilayer waveguide structure. It is shown that the PVA symmetrises the laser structure and reduces the modal losses, in turn enabling the lowest threshold operation in the nanosecond regime for CQD lasers at the time;13.5 μJ/cm2 at 5 ns. The format is also beneficial for the photostability of the laser. The CQDs are also demonstrated as the gain material of a robust, orange-emitting Vertical-Cavity Surface-Emitting Laser (VCSEL). Oscillation threshold comprised between 1 and 20 mJ/cm2 for 5ns pump pulse duration are obtained. For a broad area excitation (250 μm at 1/e2 radius), the operation is highly multimode and characterised by spatio-temporal instabilities. When pumped with a spot size at or below 100μm in radius, the VCSEL is observed to be single mode for low pump energies while additional longitudinal modes, as well as transverse mode,appear as the pumping level is increased. A study of the polarisation of the CQD laser emission for different polarisation of the pump was carried out and the Stokes parameters calculated. Results show that the pump polarisation has no significant effect on the VCSEL polarisation. While the bulk of the research concerns CQDs, two types of organic semiconductors were also applied to the aforementioned DFB laser structure. Poly(paraphenylenevinylene) (PPV) copolymer Super Yellow leading to what is to the best of our knowledge, the only case of completely ambient lasing using Super Yellow. Refractive index sensing with the laser was attempted and results are summarised. The second type in fact consisted of two organic semiconductor materials from the same novel family of autofluorescence molecules respectively named Blue 4 and Blue 6. These are investigated for the first time as laser materials. Both materialsshow signs of random lasing when prepared in a solid-state film. Single mode lasing in distributed feedback format is also demonstrated with Blue 4
Computational modelling of self-assembling triblock copolymer surfactants for use in the synthesis mesoporous silica
Get PDFBlock copolymers find applications in many fields, including adhesives,plastics, drug delivery and photonics. Several of these rely on the ability of block copolymers to self-assemble into ordered mesophases in solution. One such application of particular interest to our research group is their use as templates in the synthesis of porous silica materials, such as SBA-15. Because of their highly ordered pores, high surface areas, high functionality and low cost, mesoporous silicas have been of great interest for an increasing variety of applications and research. Understanding the synthesis mechanism for this class of materials, however, models that can predict how block copolymer templates self-assemble in aqueous solution. This study aims to produce an accurate coarse-grained, CG, model of self-assembling block copolymers, including those used in the synthesis of SBA-15 mesoporous silica (i.e., Pluronic surfactants). Such a model will enable us to probe the large time and length scales that are needed to describe the mesostructure formation from solution, thus clarifying themechanisms by which these materials are formed.;Our approach was based on the established MARTINI CG force field,which has been previously applied to model these systems. We have found that existing models were unable to accurately describe micelle aggregation self-assembly of Pluronic surfactants, although they are designed to match single-chain properties.To parameterise and validate new self-assembly models for Pluronics,we performed a a series of intermediate CG model parameterisations;alkane models, PEO and PPO models, and finally, Pluronic surfactant models. We have thus systematically tested the existing MARTINIparameters for the alkane solvent basis of these systems againstexperimental values such as density, Gibbs free energies of solvation,enthalpies of vaporisation, self-diffusion coefficients, and radii of gyration. By noting where the MARTINI model was lacking, we were then able to parameterise 1-bead, 2-bead, 3-bead, and 4-bead 2:1, 3:1,4:1, and 5:1 mapped alkane models, methodically matching Lennard-Jones and bonded parameters to known density, Gibbs free energies of solvation, and enthalpies of vaporisation properties, and validating the models against experimental self-diffusion coefficients and shearviscosity, and simulated radii of gyration.;These models were then parameterised for non-bonded interaction parameters with MARTINI water, specifically for free energy of solvation, and further validated for use in polyethylene, a polymer with a similar carbon backbone to alkanes, by matching densiity and radii of gyration.We then validated seven existing coarse-grained PEO and four existing coarse-grained PPO models, for 1-bead and 2-bead model simulations,against known experimental and simulated data such as Gibbs free energies of solvation, enthalpies of vaporisation, densities, and selfdiffusion coefficients. The two models that best matched the 2-beadsimulation results, one for PEO and one for PPO, were chosen and then calibrated for free energy of solvation in our 4:1 and 2:1 mapped hexadecane and hexane models, and a parameterised 3.5:1 heptanemodel that was interpolated from our original alkane model results.Longer chains of these two models were then validated against simulated end-to-end distances, relaxation times and radii of gyration data, and were observed in polar and nonpolar solvents to ensure their behaviour adhered to theory for self-assembly (i.e. the modelsdisplayed the correct hydrophobicity and hydrophilicity typical of PEOand PPO within these solvents).;When we had established alkane and PEO and PPO models that had the best adherence to experimental and simulated data, we finally moved on to Pluronic surfactant simulations. We chose suitable PEO-PPO interaction parameters from the same study as our chosen PPOmodel, and we create eight Pluronic models for Pluronic L31, L35, L44,L62, L64, P85, P123, and F38. Melts of seven of these models were compared to experimental and simulated properties including densities,shear viscosities, heat capacities, and radii of gyration, and larger chain simulations of three of the models, Pluroincs L35, L44, and P123were run in MARTINI water. These larger simulations, as well as another of Pluronic P123 in our 2:1 mapped hexane model, were evaluated for self-assembly and aggregation, and the micellisation free energies and aggregation numbers of the resulting aggregates were calculated against experimental data and theory.This process has lead to improved mapping schemes and adjusted parameters for alkane solvent models, PEO and PPO models with the most accurate properties in themselves and in those alkane solvents,and ultimately, Pluronic models with self-assembly behaviour. It is unfortunate, however that this process also inevitably ended up being more time-consuming and difficult than expected and we were unable to progress any farther with this thesis. We expect that in the future our models will be combined with existing models of silica precursors to effectively model and analyse SBA-15 synthesis.Block copolymers find applications in many fields, including adhesives,plastics, drug delivery and photonics. Several of these rely on the ability of block copolymers to self-assemble into ordered mesophases in solution. One such application of particular interest to our research group is their use as templates in the synthesis of porous silica materials, such as SBA-15. Because of their highly ordered pores, high surface areas, high functionality and low cost, mesoporous silicas have been of great interest for an increasing variety of applications and research. Understanding the synthesis mechanism for this class of materials, however, models that can predict how block copolymer templates self-assemble in aqueous solution. This study aims to produce an accurate coarse-grained, CG, model of self-assembling block copolymers, including those used in the synthesis of SBA-15 mesoporous silica (i.e., Pluronic surfactants). Such a model will enable us to probe the large time and length scales that are needed to describe the mesostructure formation from solution, thus clarifying themechanisms by which these materials are formed.;Our approach was based on the established MARTINI CG force field,which has been previously applied to model these systems. We have found that existing models were unable to accurately describe micelle aggregation self-assembly of Pluronic surfactants, although they are designed to match single-chain properties.To parameterise and validate new self-assembly models for Pluronics,we performed a a series of intermediate CG model parameterisations;alkane models, PEO and PPO models, and finally, Pluronic surfactant models. We have thus systematically tested the existing MARTINIparameters for the alkane solvent basis of these systems againstexperimental values such as density, Gibbs free energies of solvation,enthalpies of vaporisation, self-diffusion coefficients, and radii of gyration. By noting where the MARTINI model was lacking, we were then able to parameterise 1-bead, 2-bead, 3-bead, and 4-bead 2:1, 3:1,4:1, and 5:1 mapped alkane models, methodically matching Lennard-Jones and bonded parameters to known density, Gibbs free energies of solvation, and enthalpies of vaporisation properties, and validating the models against experimental self-diffusion coefficients and shearviscosity, and simulated radii of gyration.;These models were then parameterised for non-bonded interaction parameters with MARTINI water, specifically for free energy of solvation, and further validated for use in polyethylene, a polymer with a similar carbon backbone to alkanes, by matching densiity and radii of gyration.We then validated seven existing coarse-grained PEO and four existing coarse-grained PPO models, for 1-bead and 2-bead model simulations,against known experimental and simulated data such as Gibbs free energies of solvation, enthalpies of vaporisation, densities, and selfdiffusion coefficients. The two models that best matched the 2-beadsimulation results, one for PEO and one for PPO, were chosen and then calibrated for free energy of solvation in our 4:1 and 2:1 mapped hexadecane and hexane models, and a parameterised 3.5:1 heptanemodel that was interpolated from our original alkane model results.Longer chains of these two models were then validated against simulated end-to-end distances, relaxation times and radii of gyration data, and were observed in polar and nonpolar solvents to ensure their behaviour adhered to theory for self-assembly (i.e. the modelsdisplayed the correct hydrophobicity and hydrophilicity typical of PEOand PPO within these solvents).;When we had established alkane and PEO and PPO models that had the best adherence to experimental and simulated data, we finally moved on to Pluronic surfactant simulations. We chose suitable PEO-PPO interaction parameters from the same study as our chosen PPOmodel, and we create eight Pluronic models for Pluronic L31, L35, L44,L62, L64, P85, P123, and F38. Melts of seven of these models were compared to experimental and simulated properties including densities,shear viscosities, heat capacities, and radii of gyration, and larger chain simulations of three of the models, Pluroincs L35, L44, and P123were run in MARTINI water. These larger simulations, as well as another of Pluronic P123 in our 2:1 mapped hexane model, were evaluated for self-assembly and aggregation, and the micellisation free energies and aggregation numbers of the resulting aggregates were calculated against experimental data and theory.This process has lead to improved mapping schemes and adjusted parameters for alkane solvent models, PEO and PPO models with the most accurate properties in themselves and in those alkane solvents,and ultimately, Pluronic models with self-assembly behaviour. It is unfortunate, however that this process also inevitably ended up being more time-consuming and difficult than expected and we were unable to progress any farther with this thesis. We expect that in the future our models will be combined with existing models of silica precursors to effectively model and analyse SBA-15 synthesis
Study of solution processable emissive materials for organic light emitting diodes
Get PDFPreviously held under moratorium from 22 August 2019 until 22 August 2022.Organic light emitting diodes have played a major role in the display industry in the last ten years. Today, they have found commercial applications in smartphones, televisions, cameras and much more. This recent commercialisation is mainly due to the large performance enhancement in luminance, efficiency and lifetime observed in the last decade. The development of new organic emitting materials is obviously a key part of this success. Consisting of polymers, oligomers or small molecules, these emitters usually follow a simple synthetic path and, thanks to a facile functionalisation, they can be easily adapted to the desired project. However, they constantly need improvement to reach their full potential as efficient, cheap and lightweight light sources. Being able to obtain good performing solution processed emissive materials would be a major step towards the achievement of these goals. Chapter I includes a brief introduction to the history of OLEDs and their development, followed by a summarised description of the theory of OLEDs. Chapter II studies the different factors that influence OLED performances. A wellknown PPV polymer is used during this study. The emissive layer is first optimised in a conventional architecture. Then a change of architecture allows the study of optimising the transport/blocking layers on the device performance. Chapters III introduce two novel series of materials for red and green emission. Both series are based on a benzothiadiazole core and fluorene arms. The fluorene arm length and the terminal groups are varied and the influence of these changes are studied. The knowledge acquired in the previous chapter is applied to characterise and optimise the different emissive materials. In chapter IV the hole mobility of each material is measured in order to have a better understanding of the inner mechanisms of the devices and a solution processed electron transport is proposed as a way to improve their devices performances.Organic light emitting diodes have played a major role in the display industry in the last ten years. Today, they have found commercial applications in smartphones, televisions, cameras and much more. This recent commercialisation is mainly due to the large performance enhancement in luminance, efficiency and lifetime observed in the last decade. The development of new organic emitting materials is obviously a key part of this success. Consisting of polymers, oligomers or small molecules, these emitters usually follow a simple synthetic path and, thanks to a facile functionalisation, they can be easily adapted to the desired project. However, they constantly need improvement to reach their full potential as efficient, cheap and lightweight light sources. Being able to obtain good performing solution processed emissive materials would be a major step towards the achievement of these goals. Chapter I includes a brief introduction to the history of OLEDs and their development, followed by a summarised description of the theory of OLEDs. Chapter II studies the different factors that influence OLED performances. A wellknown PPV polymer is used during this study. The emissive layer is first optimised in a conventional architecture. Then a change of architecture allows the study of optimising the transport/blocking layers on the device performance. Chapters III introduce two novel series of materials for red and green emission. Both series are based on a benzothiadiazole core and fluorene arms. The fluorene arm length and the terminal groups are varied and the influence of these changes are studied. The knowledge acquired in the previous chapter is applied to characterise and optimise the different emissive materials. In chapter IV the hole mobility of each material is measured in order to have a better understanding of the inner mechanisms of the devices and a solution processed electron transport is proposed as a way to improve their devices performances
Aspirations and experiments : a long view of the role of 'community' in social welfare provision in the west of Scotland
Get PDFCommunities and their potential contribution to social welfare and public sector reform are a key focus for current policy in Scotland and the UK more generally. This study addresses the extent to which such a focus is new and considers what historical perspectives might bring to the understanding of this agenda.The study develops three new historical accounts of community contribution to social welfare drawn from a period of two centuries in the west of Scotland. Accounts of such activities, particularly in disadvantaged communities, are still limited and the study adds to the literature in this area. Using archival and documentary sources, supplemented with interviews, it develops accounts of the St John's Experiment, Kinning Park Co-operative Women's Guild and Paisley Community Development Project. The accounts also provided the basis for engagement with present-day community organisations.While all three accounts are context-specific and instructive individually as products of different historical contexts, social philosophies and strategies for change, they are also of interest for the similarities in the practice models adopted, the issues addressed and the extent of impact. They highlight long-held aspirations for the role that communities might play in relation to social welfare which are often not fully realised. Obstacles to impact are found in those very levels of aspiration, assumptions about the resource requirements and the extent to which power and control remain external to the communities concerned.The study concludes that the current 'turn' to community at a time of transition and transformation within social welfare can be seen to have clear parallels in the past. There are practical lessons that might be learned and the value of the three historical accounts may also be found at the level of imagination: in their ability to support a narrative of hope and stimulate ideas about alternatives to the present.Communities and their potential contribution to social welfare and public sector reform are a key focus for current policy in Scotland and the UK more generally. This study addresses the extent to which such a focus is new and considers what historical perspectives might bring to the understanding of this agenda.The study develops three new historical accounts of community contribution to social welfare drawn from a period of two centuries in the west of Scotland. Accounts of such activities, particularly in disadvantaged communities, are still limited and the study adds to the literature in this area. Using archival and documentary sources, supplemented with interviews, it develops accounts of the St John's Experiment, Kinning Park Co-operative Women's Guild and Paisley Community Development Project. The accounts also provided the basis for engagement with present-day community organisations.While all three accounts are context-specific and instructive individually as products of different historical contexts, social philosophies and strategies for change, they are also of interest for the similarities in the practice models adopted, the issues addressed and the extent of impact. They highlight long-held aspirations for the role that communities might play in relation to social welfare which are often not fully realised. Obstacles to impact are found in those very levels of aspiration, assumptions about the resource requirements and the extent to which power and control remain external to the communities concerned.The study concludes that the current 'turn' to community at a time of transition and transformation within social welfare can be seen to have clear parallels in the past. There are practical lessons that might be learned and the value of the three historical accounts may also be found at the level of imagination: in their ability to support a narrative of hope and stimulate ideas about alternatives to the present
Feelings toolkit : a new evaluation tool for very young children
Get PDFThe Feelings Toolkit is a new evaluation tool developed for very young children aged 3 to 5 years old. The tool can be used to evaluate feelings after very young children interact with computer products. It has two versions: the Wafiy Feelings Toolkit and Alisya Feelings Toolkit. It uses photographic representation and bipolar adjectives, good versus bad. The photographs were modelled by two nursery-aged children, one boy and one girl, representing one positive feeling (good), one neutral feeling, and one negative feeling (bad).;It is difficult to find a suitable tool or method to evaluate feelings after very young children interact with computer products. But it is crucial to involve very young children in evaluating children's computer products since they are the users. Many researchers have developed tools and methods for older children aged above five.;The Feelings Toolkit was developed using an iterative design approach and children's participation in the UK. The development process involved six stages; design and testing of (1) Smiley Feelings Toolkit, (2) Pictorial Feelings Toolkit, (3) Wafiy Feelings Toolkit, and (4) Alisya Feelings Toolkit. Then (5) exploratory sessions were conducted to learn about children's reactions to using the tool. Finally, (6) the tool was validated with older children in Malaysia. The final Feelings Toolkit was produced and was evaluated by very young children in kindergarten and at home.;The Feelings Toolkit is an efficacious tool to be used with computer and non-computer products. It can be used by parents at home, children's product designers and developers in the office or school, technology manufacturers in the factory, child psychologists in the clinic or school, and children's trainers or facilitators in the camp or school. The tool can be utilized by teachers during teaching and learning activities too. It is recommended to use the Feelings Toolkit as an addition to interviews and observation, not as a replacement.The Feelings Toolkit is a new evaluation tool developed for very young children aged 3 to 5 years old. The tool can be used to evaluate feelings after very young children interact with computer products. It has two versions: the Wafiy Feelings Toolkit and Alisya Feelings Toolkit. It uses photographic representation and bipolar adjectives, good versus bad. The photographs were modelled by two nursery-aged children, one boy and one girl, representing one positive feeling (good), one neutral feeling, and one negative feeling (bad).;It is difficult to find a suitable tool or method to evaluate feelings after very young children interact with computer products. But it is crucial to involve very young children in evaluating children's computer products since they are the users. Many researchers have developed tools and methods for older children aged above five.;The Feelings Toolkit was developed using an iterative design approach and children's participation in the UK. The development process involved six stages; design and testing of (1) Smiley Feelings Toolkit, (2) Pictorial Feelings Toolkit, (3) Wafiy Feelings Toolkit, and (4) Alisya Feelings Toolkit. Then (5) exploratory sessions were conducted to learn about children's reactions to using the tool. Finally, (6) the tool was validated with older children in Malaysia. The final Feelings Toolkit was produced and was evaluated by very young children in kindergarten and at home.;The Feelings Toolkit is an efficacious tool to be used with computer and non-computer products. It can be used by parents at home, children's product designers and developers in the office or school, technology manufacturers in the factory, child psychologists in the clinic or school, and children's trainers or facilitators in the camp or school. The tool can be utilized by teachers during teaching and learning activities too. It is recommended to use the Feelings Toolkit as an addition to interviews and observation, not as a replacement
Investigation and improvement of Wells turbine performance : fluid analysis & 2nd law of thermodynamics study
Get PDFThere have been several attempts to establish efficient methods to convert the energy of marine waves into electrical power. Wells turbine, with an Oscillating Water Column(OWC), is one of such methods. Wells turbine is the most common type of self-rectifying air turbine employed by OWC wave energy devices due to its technical simplicity, reliability, and design robustness. Because Wells turbine is subject to early stall, which negatively limits its performance, there were many endeavours to improve the energy extraction performance of Wells turbine within the stall regime. However,those endeavours were based only on the first law of thermodynamics analysis, without relying on the second law analysis. Since the second law of thermodynamics is concerned with the generation rate of entropy and accordingly the useful work, it is important to take the entropy generation rate into account while improve the performance of Wells turbine.The main objective of this thesis is to analyse and improve the performance of Wells turbine under sinusoidal wave based on the entropy generation minimization method for various passive flow control technique parameters. To achieve this purpose, two-dimensional numerical models for Wells turbine aerofoils under sinusoidal wave flow conditions were built and used to investigate the single and multi-slots as passive flow control means. Different operating conditions with various design parameters were investigated. Furthermore, the turbine blade with optimum slots number, location and angle were investigated using the oscillating water system based on the real data from the northern coast of Egypt.Firstly, in addition to the commonly used first law analysis, the present study utilized an entropy generation minimization method to examine the impact of the flow control method on the entropy generation characteristics around the turbine blade. The obtained results indicate that the global entropy generation rate has a different value according to the aerofoil design. It was determined that a certain aerofoil geometry always gives a global entropy generation rate less than that of other aerofoil geometries under sinusoidal inlet velocity. Furthermore, the angle of attack radically affects the second law efficiency.Subsequently, a comprehensive investigation was carried out on the passive flow control effect on the entropy generation as well as the torque coefficient. It was found that with the use of passive flow control, the entropy generation around the aerofoil section increases. On the other hand, torque coefficient of aerofoil increases before the stall happens and continues to increase within the stall regime. A significantly delayed stall is also observed with the use of the passive flow control. Moreover, aerofoils with two,three and four slots were investigated to improve the performance of Wells turbine in the stall regime. The optimum slots number and locations were determined based on minimizing the global entropy generation rate in addition to increasing the torque coefficient. Furthermore, the optimum angle for single slot aerofoil was confirmed to provide a lower global entropy generation rate as well as a higher torque coefficient than the zero angle slot before and after the stall.Finally, from the modelling results, it can be concluded that the operating conditions based on real data for the northern coast of Egypt are very suitable for the oscillating water column system with Wells turbine as a wave energy converter. Moreover, by adopting the optimum slots number, location, and angle, the performance of Wellsturbine can be significantly improved for a wide range of operating conditions.There have been several attempts to establish efficient methods to convert the energy of marine waves into electrical power. Wells turbine, with an Oscillating Water Column(OWC), is one of such methods. Wells turbine is the most common type of self-rectifying air turbine employed by OWC wave energy devices due to its technical simplicity, reliability, and design robustness. Because Wells turbine is subject to early stall, which negatively limits its performance, there were many endeavours to improve the energy extraction performance of Wells turbine within the stall regime. However,those endeavours were based only on the first law of thermodynamics analysis, without relying on the second law analysis. Since the second law of thermodynamics is concerned with the generation rate of entropy and accordingly the useful work, it is important to take the entropy generation rate into account while improve the performance of Wells turbine.The main objective of this thesis is to analyse and improve the performance of Wells turbine under sinusoidal wave based on the entropy generation minimization method for various passive flow control technique parameters. To achieve this purpose, two-dimensional numerical models for Wells turbine aerofoils under sinusoidal wave flow conditions were built and used to investigate the single and multi-slots as passive flow control means. Different operating conditions with various design parameters were investigated. Furthermore, the turbine blade with optimum slots number, location and angle were investigated using the oscillating water system based on the real data from the northern coast of Egypt.Firstly, in addition to the commonly used first law analysis, the present study utilized an entropy generation minimization method to examine the impact of the flow control method on the entropy generation characteristics around the turbine blade. The obtained results indicate that the global entropy generation rate has a different value according to the aerofoil design. It was determined that a certain aerofoil geometry always gives a global entropy generation rate less than that of other aerofoil geometries under sinusoidal inlet velocity. Furthermore, the angle of attack radically affects the second law efficiency.Subsequently, a comprehensive investigation was carried out on the passive flow control effect on the entropy generation as well as the torque coefficient. It was found that with the use of passive flow control, the entropy generation around the aerofoil section increases. On the other hand, torque coefficient of aerofoil increases before the stall happens and continues to increase within the stall regime. A significantly delayed stall is also observed with the use of the passive flow control. Moreover, aerofoils with two,three and four slots were investigated to improve the performance of Wells turbine in the stall regime. The optimum slots number and locations were determined based on minimizing the global entropy generation rate in addition to increasing the torque coefficient. Furthermore, the optimum angle for single slot aerofoil was confirmed to provide a lower global entropy generation rate as well as a higher torque coefficient than the zero angle slot before and after the stall.Finally, from the modelling results, it can be concluded that the operating conditions based on real data for the northern coast of Egypt are very suitable for the oscillating water column system with Wells turbine as a wave energy converter. Moreover, by adopting the optimum slots number, location, and angle, the performance of Wellsturbine can be significantly improved for a wide range of operating conditions
Expedient access to C-aryl linked saturated heterocyclic motifs
Get PDFThis thesis was previously restricted to Strathclyde users only from 1st March 2019 until 1st March 2024.Over the past decade, there has been a significant increase in the overall degree of saturation in candidate molecules. Increased sp3 character has been linked to a variety of improved physicochemical properties, including greater solubility and an improved likelihood of clinical success. Based on this, a range of methods have been developed to synthesise compounds with high saturation, particularly with respect to sp2-sp3 cross-coupling reactions. Many of these approaches suffer from severe drawbacks, such as a lack of generality and the requirement for bespoke, complex catalyst systems. After initial investigation into a Suzuki-Miyaura approach towards the molecules of interest, the development of a one-pot Suzuki-Miyaura-hydrogenation was explored. This method was found to be highly general and tolerant of a wide range of functionalities. Scheme 1: Developed Suzuki-Miyaura-hydrogenation methodology [Figure available in print copy]. Subsequently, the methodology was extended to allow for a transfer hydrogenation protocol. This process was broadly applicable to a range of synthetic methods, including an array format and the synthesis of multiple biologically active compounds. Scheme 2: Developed Suzuki-Miyaura-transfer-hydrogenation methodology [Figure available in print copy].Over the past decade, there has been a significant increase in the overall degree of saturation in candidate molecules. Increased sp3 character has been linked to a variety of improved physicochemical properties, including greater solubility and an improved likelihood of clinical success. Based on this, a range of methods have been developed to synthesise compounds with high saturation, particularly with respect to sp2-sp3 cross-coupling reactions. Many of these approaches suffer from severe drawbacks, such as a lack of generality and the requirement for bespoke, complex catalyst systems. After initial investigation into a Suzuki-Miyaura approach towards the molecules of interest, the development of a one-pot Suzuki-Miyaura-hydrogenation was explored. This method was found to be highly general and tolerant of a wide range of functionalities. Scheme 1: Developed Suzuki-Miyaura-hydrogenation methodology [Figure available in print copy]. Subsequently, the methodology was extended to allow for a transfer hydrogenation protocol. This process was broadly applicable to a range of synthetic methods, including an array format and the synthesis of multiple biologically active compounds. Scheme 2: Developed Suzuki-Miyaura-transfer-hydrogenation methodology [Figure available in print copy]
Advanced surface engineering : evaluation of SprayStir
No full textThe objective of this study was the development of an innovative surface engineering technology, referred to as SprayStir, which combines two existing surface engineering processes; cold spray (CS) and friction stir processing (FSP).Cold spray facilitated the deposition of particle reinforced metal matrix composite (MMC) coatings, which were subsequently refined and imbedded within the near-surface region of the substrate by FSP.;SprayStir was employed to produce particle reinforced MMC surfaces that demonstrated superior erosion performance than that of unreinforced substrate alloy. Throughout this study, SprayStir was applied to several coating and substrate combinations, and their respective erosion performance established through slurry erosion testing. The volume of the resulting war scars was measured to compare the erosion performance of SprayStirred MMCs containing different particle reinforcements.;Furthermore, the microstructure of the as-received substrate alloys, the cold spray deposited coatings, and the SprayStirred MMCs were characterised to establish the influence of FSP on the distribution of the particle reinforcements within the near-surface region. Whilst the primary aim of this investigation was to enhance the erosion performance of the as-received substrate, the contribution of erosion, corrosion and synergy of the total mass loss was also measured to identify if the corrosion performance of the as-received substrate was adversely affected by the application of SprayStir.;The results presented herein show that the erosion performance of the SprayStirred specimens is superior to that of the cold spray deposited coatings and the as-received substrate alloy. The improved erosion performance was attributed to the presence of fine, evenly dispersed reinforcing particles within the near-surface region that restrict the amount of material removed during the slurry erosion testing by altering the erosion mechanisms that operate on the specimen surface. The results from this investigation have therefore provided a proof of concept for the SprayStir technology when applied to the aluminium and steel substrates discussed throughout this study.The objective of this study was the development of an innovative surface engineering technology, referred to as SprayStir, which combines two existing surface engineering processes; cold spray (CS) and friction stir processing (FSP).Cold spray facilitated the deposition of particle reinforced metal matrix composite (MMC) coatings, which were subsequently refined and imbedded within the near-surface region of the substrate by FSP.;SprayStir was employed to produce particle reinforced MMC surfaces that demonstrated superior erosion performance than that of unreinforced substrate alloy. Throughout this study, SprayStir was applied to several coating and substrate combinations, and their respective erosion performance established through slurry erosion testing. The volume of the resulting war scars was measured to compare the erosion performance of SprayStirred MMCs containing different particle reinforcements.;Furthermore, the microstructure of the as-received substrate alloys, the cold spray deposited coatings, and the SprayStirred MMCs were characterised to establish the influence of FSP on the distribution of the particle reinforcements within the near-surface region. Whilst the primary aim of this investigation was to enhance the erosion performance of the as-received substrate, the contribution of erosion, corrosion and synergy of the total mass loss was also measured to identify if the corrosion performance of the as-received substrate was adversely affected by the application of SprayStir.;The results presented herein show that the erosion performance of the SprayStirred specimens is superior to that of the cold spray deposited coatings and the as-received substrate alloy. The improved erosion performance was attributed to the presence of fine, evenly dispersed reinforcing particles within the near-surface region that restrict the amount of material removed during the slurry erosion testing by altering the erosion mechanisms that operate on the specimen surface. The results from this investigation have therefore provided a proof of concept for the SprayStir technology when applied to the aluminium and steel substrates discussed throughout this study
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