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Characterisation of reversed phase chromatography peptide separation systems
Get PDFWith the advancement of the biopharmaceutical industry, it is imperative to have a firm understanding of the peptide separation system. The chromatographic profile can be extremely complex for peptides with various impurities or degradation products, thus it is essential to be able to maximise selectivity differences to identify each species. This thesis endeavoured to understand the influencing factors to enable rational decisions to be made during method development strategies.;A peptide-based characterisation protocol was developed and applied to commercialised stationary phases, known as the Peptide RPC Column Characterisation Protocol. A design of experiment robustness study was executed to ensure the validity of the protocol was maintained. Chemometric analysis was performed which identified three classifications of columns from which stationary phases can be selected with either similar or different selectivity. The approach was validated using two tryptic digested peptides, with promising results.;Although there are small molecule characterisation protocols already defined in the literature, it was confirmed that the peptide-based protocol is needed due to a lack of correlation between the small molecule and peptide-based protocols.;A comprehensive mobile phase study on a typical C18 phase also identified vast selectivity differences over a range of pH values, which was achieved using different ammonium-based salts, with interesting additives and ion pairs. The study ascertained the greatest differences were achieved under low pH conditions, thus the main focus for method development should be in that region. An initial study which observed the effect of temperature and organic modifiers identified the importance of evaluating these parameters during method development. Finally, the applicability of the results on other columns was determined.;The conclusions can provide a firm platform to develop a comprehensive method development strategy, which should provide a more rational approach for screening relevant stationary phases and mobile phases to truly maximise selectivity differences.With the advancement of the biopharmaceutical industry, it is imperative to have a firm understanding of the peptide separation system. The chromatographic profile can be extremely complex for peptides with various impurities or degradation products, thus it is essential to be able to maximise selectivity differences to identify each species. This thesis endeavoured to understand the influencing factors to enable rational decisions to be made during method development strategies.;A peptide-based characterisation protocol was developed and applied to commercialised stationary phases, known as the Peptide RPC Column Characterisation Protocol. A design of experiment robustness study was executed to ensure the validity of the protocol was maintained. Chemometric analysis was performed which identified three classifications of columns from which stationary phases can be selected with either similar or different selectivity. The approach was validated using two tryptic digested peptides, with promising results.;Although there are small molecule characterisation protocols already defined in the literature, it was confirmed that the peptide-based protocol is needed due to a lack of correlation between the small molecule and peptide-based protocols.;A comprehensive mobile phase study on a typical C18 phase also identified vast selectivity differences over a range of pH values, which was achieved using different ammonium-based salts, with interesting additives and ion pairs. The study ascertained the greatest differences were achieved under low pH conditions, thus the main focus for method development should be in that region. An initial study which observed the effect of temperature and organic modifiers identified the importance of evaluating these parameters during method development. Finally, the applicability of the results on other columns was determined.;The conclusions can provide a firm platform to develop a comprehensive method development strategy, which should provide a more rational approach for screening relevant stationary phases and mobile phases to truly maximise selectivity differences
Risk-based, sensor-fused detection of flooding casualties for emergency response
No full textThe inherent complexity of the flooding process on large passenger vessels has, in recent years, been recognised. Accounting for the fact that traditional emergency response is a highly time consuming and manual process, prone to human misjudgement or error, this might lead to severe consequences. This is also highly paradoxical given that the most important variables in an emergency are Time-to-Capsize and Time-to-Evacuate. The research culminating in this PhD dissertation has, therefore, been directed towards the development of a framework where sensor-technology and analytics are utilised to a higher degree, in an attempt to improve real-time information providing risk-informed situational awareness in flooding emergencies involving large cruise vessels, thus enabling optimised emergency response. A fully probabilistic prediction methodology has been developed and presented. The methodology takes advantage of available sensor readings as supportive evidence and utilises inference in the form of probabilistic multi-sensor data fusion techniques for manipulating conditional probability distributions. This targets the observed distribution, enabling reduction in uncertainty (probabilistic inference). The framework and its corresponding comprehensive probabilistic models are further seen to be highly suitable for implementation as a Life-Cycle flooding risk management framework.;A range of probabilistic models in the form of likelihood functions have been developed for a specific sample vessel using the state-of-the-art time-domain simulation code PROTEUS3. This enables the simulation of a damaged ship in a dynamic operational climate imposed by waves. Implementation and testing of the framework on a range of realistic test scenarios reveals that the method identifies the expected damaged region for all cases despite not having an exhaustive sensor array. This clearly provides improved survival assessment to enable the crew to implement emergency response in a more timely, targeted and efficient manner in accordance with the main aim set out in the thesis. Finally, having implemented the framework on an existing cruise vessel with the as-built sensor array indicates that the methodology may be implemented on a large cruise vessel without changes to the flooding detection system, as it is seen that the as-built sensor arrays allow for accurate predictions by relying entirely on the presented methodology. This allows for reliable estimation of realtime flooding risk in passenger ships through its life-cycles and most importantly, when it really matters, namely in emergencies. This is an innovation offering unique tangible benefits.The inherent complexity of the flooding process on large passenger vessels has, in recent years, been recognised. Accounting for the fact that traditional emergency response is a highly time consuming and manual process, prone to human misjudgement or error, this might lead to severe consequences. This is also highly paradoxical given that the most important variables in an emergency are Time-to-Capsize and Time-to-Evacuate. The research culminating in this PhD dissertation has, therefore, been directed towards the development of a framework where sensor-technology and analytics are utilised to a higher degree, in an attempt to improve real-time information providing risk-informed situational awareness in flooding emergencies involving large cruise vessels, thus enabling optimised emergency response. A fully probabilistic prediction methodology has been developed and presented. The methodology takes advantage of available sensor readings as supportive evidence and utilises inference in the form of probabilistic multi-sensor data fusion techniques for manipulating conditional probability distributions. This targets the observed distribution, enabling reduction in uncertainty (probabilistic inference). The framework and its corresponding comprehensive probabilistic models are further seen to be highly suitable for implementation as a Life-Cycle flooding risk management framework.;A range of probabilistic models in the form of likelihood functions have been developed for a specific sample vessel using the state-of-the-art time-domain simulation code PROTEUS3. This enables the simulation of a damaged ship in a dynamic operational climate imposed by waves. Implementation and testing of the framework on a range of realistic test scenarios reveals that the method identifies the expected damaged region for all cases despite not having an exhaustive sensor array. This clearly provides improved survival assessment to enable the crew to implement emergency response in a more timely, targeted and efficient manner in accordance with the main aim set out in the thesis. Finally, having implemented the framework on an existing cruise vessel with the as-built sensor array indicates that the methodology may be implemented on a large cruise vessel without changes to the flooding detection system, as it is seen that the as-built sensor arrays allow for accurate predictions by relying entirely on the presented methodology. This allows for reliable estimation of realtime flooding risk in passenger ships through its life-cycles and most importantly, when it really matters, namely in emergencies. This is an innovation offering unique tangible benefits
The development of gold nanorod arrays in alumina as a substrate for multi-analyte SER(R)S sensing
Get PDFSurface enhanced Raman spectroscopy (SERS) and the closely related surface enhanced resonance Raman spectroscopy (SERRS) play increasingly more important roles in both sensing and optical imaging applications. However, their widespread commercial use has been restricted in part by the lack of suitable substrates. Those currently available provide some but not all of the properties desirable in an ideal SERS substrate. Therefore, there is a need to provide a substrate with substantial signal enhancement with uniformity and repeatability of response over the entire surface. It is also advantageous for certain applications that the nanostructured substrate is also electrically conducting. The ideal substrate would also be capable of both single- and multi-analyte analysis, providing versatility through end user customisation to meet specific needs. In addition to robustness, ease of handling, surface regeneration and cost effectiveness are also desirable. This work details the progress made towards developing such a SERS substrate. The main focus was the electrochemical production of ordered gold nanorod arrays (AuNR) in a porous anodised aluminium oxide (AAO) template that enabled good control of morphology, height, width and the spacing between vertically orientated rods. Optimisation work performed on the AAO template fabrication significantly reduced 'pore branching' that had previously occurred at the top of the AAO template. Comparison studies of electrodeposited AuNR that were formed in the pores to create SERS substrates were carried out. A controlled etching step was developed to partially expose the AuNR while maintaining electrical contact. SERS studies were initially performed using two well-established reporter molecules, one resonant (malachite green) and one non-resonant (4-mercaptobenzoic acid) with the excitation laser. The signal enhancement achieved with the AuNR was vastly superior to that obtained from a commercially available substrate (Klarite®), a monolayer of gold nanoparticles (NP) and a thin gold film. The signal was found to be uniform over the whole surface. A number of cleaning methods were also explored to enable repeat use and surface regeneration over several cycles. An AuNR surface patterning method was also developed to multi-analyte detection on a single substrate. This comprised of AuNR 'dots', which can be individually functionalised. Finally, the application of the substrate for in-situ electrochemical studies was demonstrated in a specially designed flow-cell that allowed for controlled etching, cleaning and surface modification of the SERS substrate to be effected.Surface enhanced Raman spectroscopy (SERS) and the closely related surface enhanced resonance Raman spectroscopy (SERRS) play increasingly more important roles in both sensing and optical imaging applications. However, their widespread commercial use has been restricted in part by the lack of suitable substrates. Those currently available provide some but not all of the properties desirable in an ideal SERS substrate. Therefore, there is a need to provide a substrate with substantial signal enhancement with uniformity and repeatability of response over the entire surface. It is also advantageous for certain applications that the nanostructured substrate is also electrically conducting. The ideal substrate would also be capable of both single- and multi-analyte analysis, providing versatility through end user customisation to meet specific needs. In addition to robustness, ease of handling, surface regeneration and cost effectiveness are also desirable. This work details the progress made towards developing such a SERS substrate. The main focus was the electrochemical production of ordered gold nanorod arrays (AuNR) in a porous anodised aluminium oxide (AAO) template that enabled good control of morphology, height, width and the spacing between vertically orientated rods. Optimisation work performed on the AAO template fabrication significantly reduced 'pore branching' that had previously occurred at the top of the AAO template. Comparison studies of electrodeposited AuNR that were formed in the pores to create SERS substrates were carried out. A controlled etching step was developed to partially expose the AuNR while maintaining electrical contact. SERS studies were initially performed using two well-established reporter molecules, one resonant (malachite green) and one non-resonant (4-mercaptobenzoic acid) with the excitation laser. The signal enhancement achieved with the AuNR was vastly superior to that obtained from a commercially available substrate (Klarite®), a monolayer of gold nanoparticles (NP) and a thin gold film. The signal was found to be uniform over the whole surface. A number of cleaning methods were also explored to enable repeat use and surface regeneration over several cycles. An AuNR surface patterning method was also developed to multi-analyte detection on a single substrate. This comprised of AuNR 'dots', which can be individually functionalised. Finally, the application of the substrate for in-situ electrochemical studies was demonstrated in a specially designed flow-cell that allowed for controlled etching, cleaning and surface modification of the SERS substrate to be effected
Utilising active play interventions to improve physical activity and fundamental movement skills in children
Get PDFThis thesis was previously held under moratorium from 8 August 2019 until 10 July 2023.This thesis aimed to determine the effects of active play interventions on physical activity and fundamental movement skills (FMS) in children. Active play is “a form of gross motor or total body movement in which young children exert energy in a freely chosen, fun, and unstructured manner”, but is a neglected area of research. This thesis presents four unique papers. Firstly, a systematic review (Chapter 3- published in BMC Public Health) on the effect of active play interventions on children’s physical activity levels, moderate-to-vigorous intensity physical activity (MVPA), and FMS. The next two papers, a pragmatic evaluation and feasibility cluster RCT (Chapters 5 and 6) evaluated a school based ‘Active Play’ intervention, which consisted of a 1-hour outdoor physical activity session per week, incorporating 30 minutes of facilitated games and 30 minutes of free play. The pragmatic evaluation (chapter 5- published in Preventive Medicine Reports) aimed to determine the effect of participating in Active Play on school day physical activity, the proportion of time spent in MVPA during a typical session and FMS. The pragmatic evaluation was used to inform a feasibility cluster RCT (chapter 6- submitted to the Journal of Pilot and Feasibility Studies), which explored the feasibility of the Active Play intervention, and presented preliminary findings on four outcomes: physical activity levels, FMS, inhibition, and maths fluency. Paper four (Chapter 7- submitted to the Scottish Educational Review) aims to discuss the benefits of active play, summarise research into active play interventions and reflect on lessons learned for the school-based Active Play intervention. There were three main findings from the present thesis: a) active play is an under researched area that needs greater focus, b) the school-based Active Play intervention is promising (benefits from high amounts of MVPA) and c) children from Scotland have poor FMS.This thesis aimed to determine the effects of active play interventions on physical activity and fundamental movement skills (FMS) in children. Active play is “a form of gross motor or total body movement in which young children exert energy in a freely chosen, fun, and unstructured manner”, but is a neglected area of research. This thesis presents four unique papers. Firstly, a systematic review (Chapter 3- published in BMC Public Health) on the effect of active play interventions on children’s physical activity levels, moderate-to-vigorous intensity physical activity (MVPA), and FMS. The next two papers, a pragmatic evaluation and feasibility cluster RCT (Chapters 5 and 6) evaluated a school based ‘Active Play’ intervention, which consisted of a 1-hour outdoor physical activity session per week, incorporating 30 minutes of facilitated games and 30 minutes of free play. The pragmatic evaluation (chapter 5- published in Preventive Medicine Reports) aimed to determine the effect of participating in Active Play on school day physical activity, the proportion of time spent in MVPA during a typical session and FMS. The pragmatic evaluation was used to inform a feasibility cluster RCT (chapter 6- submitted to the Journal of Pilot and Feasibility Studies), which explored the feasibility of the Active Play intervention, and presented preliminary findings on four outcomes: physical activity levels, FMS, inhibition, and maths fluency. Paper four (Chapter 7- submitted to the Scottish Educational Review) aims to discuss the benefits of active play, summarise research into active play interventions and reflect on lessons learned for the school-based Active Play intervention. There were three main findings from the present thesis: a) active play is an under researched area that needs greater focus, b) the school-based Active Play intervention is promising (benefits from high amounts of MVPA) and c) children from Scotland have poor FMS
Optimisation of generators for direct drive offshore wind turbines
Get PDFA large proportion of offshore wind turbine designs are now based on directly driven permanent magnet synchronous generators using rare earth materials. The objective of this study is to optimise permanent magnet synchronous generators for offshore direct drive wind turbines in order to reduce the cost of energy, reduce the use of rare earth materials and increase the machine efficiency. A 6MW wind turbine design is assumed and parametric electromagnetic and structural generator models are introduced for a surface-mounted magnet generator topology (using magnets with high BHmax) and a flux-concentrating variant (using magnets with both higher and lower BHmax). Finite element method models are used to check key dependent variables calculated by the analytical models. These are optimised using a hybrid Genetic Algorithm and Pattern Search process with four different objective functions. -- Further steps to improve the quality of the model include the effect of generator mass on the design, cost of the turbine tower and foundation and the impact of generator diameter limits have on the choice of optimum independent variables. Further optimizations are carried out for different power ratings (6 MW, 8 MW and 10 MW), choice of magnet grades, BHmax and working temperature. The effect of variable power factor and sensitivity to magnet specific cost, availability, operation and maintenance cost, wind conditions and rest of the turbine cost are also investigated in this study. -- A detailed thermal model is used to estimate the effect of temperature due to power losses, calculate the cooling airflow requirements to bring the magnet operating temperature from 120°C to 80°C and controlling the cooling air flow for variable losses. Allowing the use of cheaper temperature grades of magnets, the additional cooling reduces winding losses and improves the effective BHmax of the magnets. -- Discussions and conclusions highlights the impact of different investigations on the optimal generator design and find out the possible best way to optimise the generator for offshore wind energy application.A large proportion of offshore wind turbine designs are now based on directly driven permanent magnet synchronous generators using rare earth materials. The objective of this study is to optimise permanent magnet synchronous generators for offshore direct drive wind turbines in order to reduce the cost of energy, reduce the use of rare earth materials and increase the machine efficiency. A 6MW wind turbine design is assumed and parametric electromagnetic and structural generator models are introduced for a surface-mounted magnet generator topology (using magnets with high BHmax) and a flux-concentrating variant (using magnets with both higher and lower BHmax). Finite element method models are used to check key dependent variables calculated by the analytical models. These are optimised using a hybrid Genetic Algorithm and Pattern Search process with four different objective functions. -- Further steps to improve the quality of the model include the effect of generator mass on the design, cost of the turbine tower and foundation and the impact of generator diameter limits have on the choice of optimum independent variables. Further optimizations are carried out for different power ratings (6 MW, 8 MW and 10 MW), choice of magnet grades, BHmax and working temperature. The effect of variable power factor and sensitivity to magnet specific cost, availability, operation and maintenance cost, wind conditions and rest of the turbine cost are also investigated in this study. -- A detailed thermal model is used to estimate the effect of temperature due to power losses, calculate the cooling airflow requirements to bring the magnet operating temperature from 120°C to 80°C and controlling the cooling air flow for variable losses. Allowing the use of cheaper temperature grades of magnets, the additional cooling reduces winding losses and improves the effective BHmax of the magnets. -- Discussions and conclusions highlights the impact of different investigations on the optimal generator design and find out the possible best way to optimise the generator for offshore wind energy application
Multi-scale material growth and erosion in extreme environments
Get PDFThis work sets out to develop a model to analyse surface growth during high energy deposition. This is important to applications such as hypersonics and thin-film growth. We considered Molecular Dynamics (MD), an atomistic model which captures key details but can only simulate small systems at short timescales due to computational cost. We also considered kinetic Monte Carlo (kMC), a mesoscale model lacking a lot of the fine detail but using a vastly reduced computational cost, allowing the analysis of larger systems over longer timeframes. The many-body Sutton-Chen potential was employed in preference to the Lennard-Jones (a simple pairwise potential) in the MD code, capturing electronic density effects and how they affect the surface atom interactions. How the average surface height and surface roughness was affected by high energy atomic impingement was analysed for a variety of systems. A kMC code was then created that made use of the MD statistics to recreate the surface growth patterns, while allowing for much larger and longer simulations. Using MD, the average surface height initially decreases before growing linearly. Meanwhile the surface roughness grows rapidly initially before increasing more slowly. Analysis of the effect of polar and azimuthal angles showed that the surface started eroding above a polar angle of 50°, and that using random or fixed azimuthal angles angle only affected the surface substantially at polar angles above 70°. Using kMC, a surface size of 56 by 28 lattice sites served well as a model system for the deposition of 2.5 monolayers while larger surfaces were required to avoid finite size effects during the deposition of 40 monolayers. We conclude that we have developed a model that can be used to simulate the evolution of a surface during high energy deposition, applicable to realistic sizes and timeframes.This work sets out to develop a model to analyse surface growth during high energy deposition. This is important to applications such as hypersonics and thin-film growth. We considered Molecular Dynamics (MD), an atomistic model which captures key details but can only simulate small systems at short timescales due to computational cost. We also considered kinetic Monte Carlo (kMC), a mesoscale model lacking a lot of the fine detail but using a vastly reduced computational cost, allowing the analysis of larger systems over longer timeframes. The many-body Sutton-Chen potential was employed in preference to the Lennard-Jones (a simple pairwise potential) in the MD code, capturing electronic density effects and how they affect the surface atom interactions. How the average surface height and surface roughness was affected by high energy atomic impingement was analysed for a variety of systems. A kMC code was then created that made use of the MD statistics to recreate the surface growth patterns, while allowing for much larger and longer simulations. Using MD, the average surface height initially decreases before growing linearly. Meanwhile the surface roughness grows rapidly initially before increasing more slowly. Analysis of the effect of polar and azimuthal angles showed that the surface started eroding above a polar angle of 50°, and that using random or fixed azimuthal angles angle only affected the surface substantially at polar angles above 70°. Using kMC, a surface size of 56 by 28 lattice sites served well as a model system for the deposition of 2.5 monolayers while larger surfaces were required to avoid finite size effects during the deposition of 40 monolayers. We conclude that we have developed a model that can be used to simulate the evolution of a surface during high energy deposition, applicable to realistic sizes and timeframes
Effective hyperspectral band selection and multispectral sensing based data reduction and applications in food analysis
Get PDFThis thesis focuses on the development of new band selection algorithms and sensing technology to accommodate for the growing demand in commercial and industrial hyperspectral imaging applications. Hyperspectral imaging is inherently complex as it combines two-dimensional spatial image information with highly resolved spectral measurements in a three-dimensional data structure. With rising dimensionality of the data, the required complexity of mathematical models increases exponentially. Dimensionality reduction in the form of band selection is analysed in this thesis, as it preserves physical interpretability of the original data. Two separate approaches are developed. The first one defines an optimisation heuristic for a criterion for band subsets carrying most information and least redundancies. The second approach embeds the identification of the most relevant bands into the reconstruction of the whole dataset. Both approaches successfully reduce the data amount while maintaining the classification accuracy. This thesis further develops a prototype for a cost-effective, portable and easy-to-use hyperspectral imaging system. RGB LED based time-multiplexed illumination enables rapid acquisition of multi-channel images that are subsequently used to reconstruct spectral signatures from hyperspectral prior via a multilayer perceptron. It is shown that a very accurate reconstruction is possible for a limited number of desired signatures that are sufficiently distinct. Lastly, the thesis focuses on industrial case studies of hyperspectral imaging in the context of food quality monitoring. The capabilities of SWIR and UV imaging were compared to estimate the smokiness of Scotch Whisky from the concentration of phenolic flavour compounds on barley malt used for distillation. UV imaging shows potential to estimate the concentration but is in its current state of technological development not ready for implementation, as opposed to SWIR, which due to its maturity, has the potential to be implemented in a production environment. Problems arising when imaging food products are examined on the example of salmon fillets.This thesis focuses on the development of new band selection algorithms and sensing technology to accommodate for the growing demand in commercial and industrial hyperspectral imaging applications. Hyperspectral imaging is inherently complex as it combines two-dimensional spatial image information with highly resolved spectral measurements in a three-dimensional data structure. With rising dimensionality of the data, the required complexity of mathematical models increases exponentially. Dimensionality reduction in the form of band selection is analysed in this thesis, as it preserves physical interpretability of the original data. Two separate approaches are developed. The first one defines an optimisation heuristic for a criterion for band subsets carrying most information and least redundancies. The second approach embeds the identification of the most relevant bands into the reconstruction of the whole dataset. Both approaches successfully reduce the data amount while maintaining the classification accuracy. This thesis further develops a prototype for a cost-effective, portable and easy-to-use hyperspectral imaging system. RGB LED based time-multiplexed illumination enables rapid acquisition of multi-channel images that are subsequently used to reconstruct spectral signatures from hyperspectral prior via a multilayer perceptron. It is shown that a very accurate reconstruction is possible for a limited number of desired signatures that are sufficiently distinct. Lastly, the thesis focuses on industrial case studies of hyperspectral imaging in the context of food quality monitoring. The capabilities of SWIR and UV imaging were compared to estimate the smokiness of Scotch Whisky from the concentration of phenolic flavour compounds on barley malt used for distillation. UV imaging shows potential to estimate the concentration but is in its current state of technological development not ready for implementation, as opposed to SWIR, which due to its maturity, has the potential to be implemented in a production environment. Problems arising when imaging food products are examined on the example of salmon fillets
Offsite timber systems multi-factor productivity index
Get PDFThe construction industry in the UK has been characterised in recent years by stagnating productivity. Offsite methods of construction which involve building in a factory environment, have been suggested as part of the solution to this issue. Within the current economic context, this thesis focussed on timber systems and examined the existing literature relating to their Multi-Factor Productivity (MFP) measurements, identifying a gap in knowledge relating to comparative MFP index for different offsite timber systems. A subsequent market perception survey amongst built environment professionals highlighted an opportunity for offsite timber systems to increase efficiency. However the responses indicated the importance of examining advanced offsite timber systems such as Volumetric Timber Construction (VTC) in comparison to established in the UK market panelised timber systems. A manufacturing survey was then undertaken which compared the productivity ofVTC manufacturers in the UK and mainland Europe with open and closed timber panel manufacturing techniques in the UK. The main findings from the survey were that the European VTC and UK panelised manufacturers had similarly high productivity and the UKVTC manufacturers had potential for growth. The MFP of four timber construction projects was then analysed: two low-rise residential projects (using open timber panel and VTC), and two mid-rise residential developments (one using closed timber panels and one using cross laminated timber). The results revealed that increased offsite completion in the factory could result in increased construction productivity however external and internal works were still a major challenge to efficiency. The overall analysis was used to outline a theoretical framework for an innovative MFP index with five key quantified variables and five secondary qualitative variables. This index facilitates the measurement and comparison of construction productivity between a variety of different structural systems and is one of the unique contributions to knowledge generated in this thesis.The construction industry in the UK has been characterised in recent years by stagnating productivity. Offsite methods of construction which involve building in a factory environment, have been suggested as part of the solution to this issue. Within the current economic context, this thesis focussed on timber systems and examined the existing literature relating to their Multi-Factor Productivity (MFP) measurements, identifying a gap in knowledge relating to comparative MFP index for different offsite timber systems. A subsequent market perception survey amongst built environment professionals highlighted an opportunity for offsite timber systems to increase efficiency. However the responses indicated the importance of examining advanced offsite timber systems such as Volumetric Timber Construction (VTC) in comparison to established in the UK market panelised timber systems. A manufacturing survey was then undertaken which compared the productivity ofVTC manufacturers in the UK and mainland Europe with open and closed timber panel manufacturing techniques in the UK. The main findings from the survey were that the European VTC and UK panelised manufacturers had similarly high productivity and the UKVTC manufacturers had potential for growth. The MFP of four timber construction projects was then analysed: two low-rise residential projects (using open timber panel and VTC), and two mid-rise residential developments (one using closed timber panels and one using cross laminated timber). The results revealed that increased offsite completion in the factory could result in increased construction productivity however external and internal works were still a major challenge to efficiency. The overall analysis was used to outline a theoretical framework for an innovative MFP index with five key quantified variables and five secondary qualitative variables. This index facilitates the measurement and comparison of construction productivity between a variety of different structural systems and is one of the unique contributions to knowledge generated in this thesis
Leadership for lean six sigma
Get PDFContinuous improvement is an important business strategy for many organizations, and in the last few years Lean Six Sigma has become one of the most popular and proven business process improvement methodologies.Lean and Six Sigma developed as independent business improvement initiatives, before converging in the past decade. The success of Lean Six Sigma deployment depends on a series of process/quality improvement projects undertaken in organisations: although a vast amount of literature has explored the topic of Lean Six Sigma, most of it has centred around the technical aspects, specific case studies or problems, leaving a gap in knowledge about the impact of leadership on successful implementation.The aim of this research is to assess the impact of organizational leadership on the deployment of Lean Six Sigma in organisations and thereby develop a dependency model to facilitate its successful implementation. A mixed-methods approach, using survey and semi-structured interviews, was adopted.This research identifies leadership as a critical success factor for Lean Six Sigma deployment in organizations, details what leadership traits are needed for a successful deployment, differentiating by industry sector, and presents a leadership dependency model.Building on the existing literature, this research extends and helps refine our understanding of Lean Six Sigma and leadership, identifying the traits a leader needs to display to increase the chances of successful deployment.Continuous improvement is an important business strategy for many organizations, and in the last few years Lean Six Sigma has become one of the most popular and proven business process improvement methodologies.Lean and Six Sigma developed as independent business improvement initiatives, before converging in the past decade. The success of Lean Six Sigma deployment depends on a series of process/quality improvement projects undertaken in organisations: although a vast amount of literature has explored the topic of Lean Six Sigma, most of it has centred around the technical aspects, specific case studies or problems, leaving a gap in knowledge about the impact of leadership on successful implementation.The aim of this research is to assess the impact of organizational leadership on the deployment of Lean Six Sigma in organisations and thereby develop a dependency model to facilitate its successful implementation. A mixed-methods approach, using survey and semi-structured interviews, was adopted.This research identifies leadership as a critical success factor for Lean Six Sigma deployment in organizations, details what leadership traits are needed for a successful deployment, differentiating by industry sector, and presents a leadership dependency model.Building on the existing literature, this research extends and helps refine our understanding of Lean Six Sigma and leadership, identifying the traits a leader needs to display to increase the chances of successful deployment
Closing the gap between guidance and practice : an investigation of the relevance of design guidance to practitioners using object-oriented technologies
Get PDFThis thesis investigates if object oriented guidance is relevant in practice, and how this affects software that is produced. This is achieved by surveying practitioners and studying how constructs such as interfaces and inheritance are used in open-source systems. Surveyed practitioners framed 'good design' in terms of impact on development and maintenance. Recognition of quality requires practitioner judgement (individually and as a group), and principles are valued over rules. Time constraints heighten sensitivity to the rework cost of poor design decisions. Examination of open source systems highlights the use of interface and inheritance. There is some evidence of 'textbook' use of these structures, and much use is simple. Outliers are widespread indicating a pragmatic approach. Design is found to reflect the pressures of practice - high-level decisions justify 'designed' structures and architecture, while uncertainty leads to deferred design decisions - simpler structures, repetition, and unconsolidated design. Sub-populations of structures can be identified which may represent common trade-offs. Useful insights are gained into practitioner attitude to design guidance. Patterns of use and structure are identified which may aid in assessment and comprehension of object oriented systems.This thesis investigates if object oriented guidance is relevant in practice, and how this affects software that is produced. This is achieved by surveying practitioners and studying how constructs such as interfaces and inheritance are used in open-source systems. Surveyed practitioners framed 'good design' in terms of impact on development and maintenance. Recognition of quality requires practitioner judgement (individually and as a group), and principles are valued over rules. Time constraints heighten sensitivity to the rework cost of poor design decisions. Examination of open source systems highlights the use of interface and inheritance. There is some evidence of 'textbook' use of these structures, and much use is simple. Outliers are widespread indicating a pragmatic approach. Design is found to reflect the pressures of practice - high-level decisions justify 'designed' structures and architecture, while uncertainty leads to deferred design decisions - simpler structures, repetition, and unconsolidated design. Sub-populations of structures can be identified which may represent common trade-offs. Useful insights are gained into practitioner attitude to design guidance. Patterns of use and structure are identified which may aid in assessment and comprehension of object oriented systems
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