7103 research outputs found
Sort by
Self-generated magnetic fields in intense laser-solid interactions relevant to relativistic plasma astrophysics
Get PDFThis thesis reports on self-generated magnetic fields in ultra-intense laser interactions with dense plasma and the role that these play in the dynamics of relativistic electrons, and, subsequently, ion acceleration. This includes an investigation of resistive magnetic fields generated within solids and their influence on the transport of multi-mega-Ampere currents of energetic electrons. It also includes investigations of magnetic fields in foils expanded to near-critical density, produced by the Biermann battery and Weibel instability mechanisms. The first part of the thesis explores the transport of relativistic electrons in relatively thick solids, specifically, different allotropes of lithium, silicon and carbon. This is initially explored numerically. Simulations, performed using a three-dimensional hybrid-particle-in-cell codes are used to investigate how the material resistivity-temperature profile affects fast electron transport via self-generated magnetic fields. The degree of lattice order in the material strongly affects electrical resistivity at low temperatures. By considering resistivity-temperature profiles intermediate to those of ordered and disordered arrangements of ions, it is shown that the magnitude and shape of the resistivity-temperature profile at low temperatures strongly affects the growth of self-generated resistive magnetic fields and the onset of resistive transport instabilities. The scaling of these effects to scenarios relevant to the fast ignition scheme for inertial confinement fusion is also discussed. Following this, the influence of the low temperature electrical resistivity on the onset of the resistive filamentation instability is investigated, both experimentally and numerically, in targets consisting of layers of ordered and disordered forms of carbon. It is demonstrated that the thickness of the disordered carbon layer influences the degree of filamentation of the fast electron beam, with strong filamentation produced for thickness of the order of 60µm or greater. Furthermore, it is also shown that the position of the disordered carbon layer (within the layered target) has a minimal influence on the growth of the resistive filamentation instability. The second part of the thesis explores the influence of self-generated magnetic fields on the dynamics of electron motion in ultrathin foil targets expanding to near-critical density and undergoing relativistic induced transparency. The generation of a plasma jet, supported by a self-generated azimuthal magnetic field is explored. The parameters of the jet and its sensitivity to the experimental parameters are characterised. Following this, the onset of Weibel instability-generated magnetic fields is investigated, as diagnosed by the formation of bubble-like structures in the beam of protons accelerated from the foil. The sensitivity of the Weibel-generated magnetic fields to the decompression of the target is explored. An analysis of the scaling of the relativistic plasma jet is presented, exploring the possibility of employing these laboratory-generated structures as analogues of astrophysical relativistic plasma jet phenomena.This thesis reports on self-generated magnetic fields in ultra-intense laser interactions with dense plasma and the role that these play in the dynamics of relativistic electrons, and, subsequently, ion acceleration. This includes an investigation of resistive magnetic fields generated within solids and their influence on the transport of multi-mega-Ampere currents of energetic electrons. It also includes investigations of magnetic fields in foils expanded to near-critical density, produced by the Biermann battery and Weibel instability mechanisms. The first part of the thesis explores the transport of relativistic electrons in relatively thick solids, specifically, different allotropes of lithium, silicon and carbon. This is initially explored numerically. Simulations, performed using a three-dimensional hybrid-particle-in-cell codes are used to investigate how the material resistivity-temperature profile affects fast electron transport via self-generated magnetic fields. The degree of lattice order in the material strongly affects electrical resistivity at low temperatures. By considering resistivity-temperature profiles intermediate to those of ordered and disordered arrangements of ions, it is shown that the magnitude and shape of the resistivity-temperature profile at low temperatures strongly affects the growth of self-generated resistive magnetic fields and the onset of resistive transport instabilities. The scaling of these effects to scenarios relevant to the fast ignition scheme for inertial confinement fusion is also discussed. Following this, the influence of the low temperature electrical resistivity on the onset of the resistive filamentation instability is investigated, both experimentally and numerically, in targets consisting of layers of ordered and disordered forms of carbon. It is demonstrated that the thickness of the disordered carbon layer influences the degree of filamentation of the fast electron beam, with strong filamentation produced for thickness of the order of 60µm or greater. Furthermore, it is also shown that the position of the disordered carbon layer (within the layered target) has a minimal influence on the growth of the resistive filamentation instability. The second part of the thesis explores the influence of self-generated magnetic fields on the dynamics of electron motion in ultrathin foil targets expanding to near-critical density and undergoing relativistic induced transparency. The generation of a plasma jet, supported by a self-generated azimuthal magnetic field is explored. The parameters of the jet and its sensitivity to the experimental parameters are characterised. Following this, the onset of Weibel instability-generated magnetic fields is investigated, as diagnosed by the formation of bubble-like structures in the beam of protons accelerated from the foil. The sensitivity of the Weibel-generated magnetic fields to the decompression of the target is explored. An analysis of the scaling of the relativistic plasma jet is presented, exploring the possibility of employing these laboratory-generated structures as analogues of astrophysical relativistic plasma jet phenomena
Economic burden of diarrheal diseases and effect of vaccination - experience from a lower middle-income country
Get PDFDiarrheal diseases remain one of the major global public health problems and a leading cause of morbidity and mortality in low- and middle-income countries like Bangladesh. Though the diseases are preventable and could be managed with low-cost interventions, the morbidity due to diarrheal diseases remains stable and has become the top causes of hospitalization of Bangladesh. Therefore, significant resources are consumed for treating patients with diarrhea. Among all of the diarrheal diseases, cholera and rotavirus are mainly responsible for severe diarrhea while endemic cholera is one of the largest burdens for Bangladesh.;Vaccination is the most cost-effective investment for preventing the spread of vaccine-preventable diseases; Bangladesh is also committed to introduce cholera and rotavirus vaccination in the national Expanded Program on Immunization (EPI) schedule. This thesis investigates the health and economic burden of diarrheal diseases in Bangladesh and intends to generate evidence for policymakers about future nationwide cholera and rotavirus vaccination programs which have been inadequately studied.;To achieve this aim, I have conducted a series of empirical studies for assessing the prevalence, economic burden of diarrheal diseases, economics of cholera vaccination, demand for cholera vaccines and the cost-effectiveness of future childhood rotavirus vaccination. The thesis is based on seven papers while five of them are primary survey-data driven and two of them are based on secondary data sources and modeling.;As cholera and rotavirus infections are life-threating conditions to high-risk people and children, the thesis sort out that such preventive programs could avert a substantial number of cases, deaths, and hospitalizations and appeared as a cost-effective investment. The thesis is also point out that there is a lack of good quality information on disease incidence, mortality, and the economic burden in the country. Therefore, further research is needed for proper understanding for priority setting in diarrhea control. The thesis also highlights the potential demand for cholera vaccines in the community; therefore, individuals may not wait for the public vaccination campaign if the vaccines are available in private market.;I believe that my thesis is provides a better understanding of the economics of diarrheal diseases and will contribute to the decision-making process regarding the prevention of diarrheal infections by strengthening the case for future oral cholera and rotavirus vaccination program in Bangladesh for the benefit of society.Diarrheal diseases remain one of the major global public health problems and a leading cause of morbidity and mortality in low- and middle-income countries like Bangladesh. Though the diseases are preventable and could be managed with low-cost interventions, the morbidity due to diarrheal diseases remains stable and has become the top causes of hospitalization of Bangladesh. Therefore, significant resources are consumed for treating patients with diarrhea. Among all of the diarrheal diseases, cholera and rotavirus are mainly responsible for severe diarrhea while endemic cholera is one of the largest burdens for Bangladesh.;Vaccination is the most cost-effective investment for preventing the spread of vaccine-preventable diseases; Bangladesh is also committed to introduce cholera and rotavirus vaccination in the national Expanded Program on Immunization (EPI) schedule. This thesis investigates the health and economic burden of diarrheal diseases in Bangladesh and intends to generate evidence for policymakers about future nationwide cholera and rotavirus vaccination programs which have been inadequately studied.;To achieve this aim, I have conducted a series of empirical studies for assessing the prevalence, economic burden of diarrheal diseases, economics of cholera vaccination, demand for cholera vaccines and the cost-effectiveness of future childhood rotavirus vaccination. The thesis is based on seven papers while five of them are primary survey-data driven and two of them are based on secondary data sources and modeling.;As cholera and rotavirus infections are life-threating conditions to high-risk people and children, the thesis sort out that such preventive programs could avert a substantial number of cases, deaths, and hospitalizations and appeared as a cost-effective investment. The thesis is also point out that there is a lack of good quality information on disease incidence, mortality, and the economic burden in the country. Therefore, further research is needed for proper understanding for priority setting in diarrhea control. The thesis also highlights the potential demand for cholera vaccines in the community; therefore, individuals may not wait for the public vaccination campaign if the vaccines are available in private market.;I believe that my thesis is provides a better understanding of the economics of diarrheal diseases and will contribute to the decision-making process regarding the prevention of diarrheal infections by strengthening the case for future oral cholera and rotavirus vaccination program in Bangladesh for the benefit of society
Finding the plot : a plot-based housing development model applied to physical regeneration in Glasgow
No full textUrban change, and the failure of conventional, post-war planning and development in Glasgow has left a legacy of vacant and derelict land in the city. This represents an underutilised asset that can be brought back into use as a public resource, contributing to the city's regeneration, and helping to slow the rate of population loss to the suburbs. Access to this land resource, primarily for housebuilding, can be assisted by the adoption of the principles of plot-based urbanism. Plot-based urbanism offers an innovative approach to development, based on an urban structure made up of fine-grained elements, in the form of plots, capable of incremental development by a range of agencies. The morphological study of traditional, pre-war masterplanning methods in Glasgow suggests that a typically disaggregated pattern of land subdivision remains of great relevance for development, and that the physical form and organisation of urban land may enhance the capacity for neighbourhood self-organisation. This study undertakes analysis of historic changes in plot formation, and uses the results to suggest ways of making housing investment more informed and responsive to urban change. It derives core principles of land subdivision, and presents these principles in a set of normative design codes that can be used to pass effective control over the process of land subdivision in regeneration areas to a range of potential developers. By doing so, activity in housing-led regeneration can be increased beyond the rate possible by our current reliance on existing public and private development models. It is argued that the publicly-funded sector could take on the role of lead provider of opportunity, through the adoption of new plot-based development processes, thereby supporting communities in the sustainable reuse of vacant inner-city land.Urban change, and the failure of conventional, post-war planning and development in Glasgow has left a legacy of vacant and derelict land in the city. This represents an underutilised asset that can be brought back into use as a public resource, contributing to the city's regeneration, and helping to slow the rate of population loss to the suburbs. Access to this land resource, primarily for housebuilding, can be assisted by the adoption of the principles of plot-based urbanism. Plot-based urbanism offers an innovative approach to development, based on an urban structure made up of fine-grained elements, in the form of plots, capable of incremental development by a range of agencies. The morphological study of traditional, pre-war masterplanning methods in Glasgow suggests that a typically disaggregated pattern of land subdivision remains of great relevance for development, and that the physical form and organisation of urban land may enhance the capacity for neighbourhood self-organisation. This study undertakes analysis of historic changes in plot formation, and uses the results to suggest ways of making housing investment more informed and responsive to urban change. It derives core principles of land subdivision, and presents these principles in a set of normative design codes that can be used to pass effective control over the process of land subdivision in regeneration areas to a range of potential developers. By doing so, activity in housing-led regeneration can be increased beyond the rate possible by our current reliance on existing public and private development models. It is argued that the publicly-funded sector could take on the role of lead provider of opportunity, through the adoption of new plot-based development processes, thereby supporting communities in the sustainable reuse of vacant inner-city land
Voices of the Cold War in Britain, 1945 - 1962
No full textThis thesis investigates the civilian experience of the Cold War between 1945 and1962 through 44 original oral history interviews with 48 individuals. As the first oral history of everyday life in Cold War Britain it examines the generation born before1945 and the experience of growing up in postwar Britain. The thesis situates these oral histories within the changing emotional landscape that contextualised Britain's Cold War, comparing and contrasting experiences through cultural and documentary sources, as well as oral testimony. This combination of sources and methodologies offers a fresh perspective on two civilian communities that were integral to Britain's early nuclear weapons developments: civil defence recruits and anti-nuclear campaigners. It is also the first study of its kind to compare these group experiences with those of a general cohort of civilian interviewees. An emotions history approach is central to the argument that personal experiences of Second World War memory, gender norms, and the media, coupled with unprecedented technological and cultural postwar developments, contributed to perceptions of nuclear security and Britain's role in Cold War foreign policy. While many individuals responded differently to the Cold War in this period, the thesis shows that such actions were often anchored in similar motivations. The thesis argues that the conditions of postwar emotional cultures underpinned individual and collective perspectives on Britain's role in the Cold War, revealing how the logic of Cold War military strategies and power structures affected and were absorbed by civilians indirectly implicated in a peacetime conflict. As such, this thesis contributes directly to current scholarship on the cultural, social and political history of Cold War Britain.This thesis investigates the civilian experience of the Cold War between 1945 and1962 through 44 original oral history interviews with 48 individuals. As the first oral history of everyday life in Cold War Britain it examines the generation born before1945 and the experience of growing up in postwar Britain. The thesis situates these oral histories within the changing emotional landscape that contextualised Britain's Cold War, comparing and contrasting experiences through cultural and documentary sources, as well as oral testimony. This combination of sources and methodologies offers a fresh perspective on two civilian communities that were integral to Britain's early nuclear weapons developments: civil defence recruits and anti-nuclear campaigners. It is also the first study of its kind to compare these group experiences with those of a general cohort of civilian interviewees. An emotions history approach is central to the argument that personal experiences of Second World War memory, gender norms, and the media, coupled with unprecedented technological and cultural postwar developments, contributed to perceptions of nuclear security and Britain's role in Cold War foreign policy. While many individuals responded differently to the Cold War in this period, the thesis shows that such actions were often anchored in similar motivations. The thesis argues that the conditions of postwar emotional cultures underpinned individual and collective perspectives on Britain's role in the Cold War, revealing how the logic of Cold War military strategies and power structures affected and were absorbed by civilians indirectly implicated in a peacetime conflict. As such, this thesis contributes directly to current scholarship on the cultural, social and political history of Cold War Britain
The development of organic peroxide mediated oxidations
Get PDFThis thesis describes the development of two novel metal-free oxidations processes: a method to selective synthesis anti-diols directly from commercially available alkene starting materials and an organocatalytic sulfoxidation procedure using diketones as catalysts.;Chapter 1 describes a novel metal-free method for the one-pot anti-dihydroxylation of alkenes to form diols using malonoyl peroxide 13. The reaction conditions were optimised and the scope of the optimal conditions were examined with a variety of stilbene, styrene and indene derivatives to give the corresponding anti-diols in good to excellent yields and selectivities. Following this, a variety of mechanistic investigations were undertaken, revealing key intermediates and allowing the proposal of a mechanism. Scheme 1-1. Optimised conditions of anti-dihydroxylation discussed in Chapter 1. [see thesis for graphic representation];Chapter 2 demonstrates the development of an organocatalytic sulfoxidation using diketone catalysts. Following a significant optimisation process, the scope of sulfoxidation, showing a wide tolerance of functional groups, was explored. Mechanistic investigation was also undertaken, exploring the intermediates isolated from the procedure and an exploration of the reactivity using tool compounds. The stoichiometric process was also investigated to generate kinetics and a postulated transition state. Scheme 1-2. Optimised conditions of organocatalytic sulfoxidation discussed in Chapter 2. [see thesis for graphic representation];Chapter 3 contains the experimental procedures and analytical data generated for all the compounds synthesised within this thesis.This thesis describes the development of two novel metal-free oxidations processes: a method to selective synthesis anti-diols directly from commercially available alkene starting materials and an organocatalytic sulfoxidation procedure using diketones as catalysts.;Chapter 1 describes a novel metal-free method for the one-pot anti-dihydroxylation of alkenes to form diols using malonoyl peroxide 13. The reaction conditions were optimised and the scope of the optimal conditions were examined with a variety of stilbene, styrene and indene derivatives to give the corresponding anti-diols in good to excellent yields and selectivities. Following this, a variety of mechanistic investigations were undertaken, revealing key intermediates and allowing the proposal of a mechanism. Scheme 1-1. Optimised conditions of anti-dihydroxylation discussed in Chapter 1. [see thesis for graphic representation];Chapter 2 demonstrates the development of an organocatalytic sulfoxidation using diketone catalysts. Following a significant optimisation process, the scope of sulfoxidation, showing a wide tolerance of functional groups, was explored. Mechanistic investigation was also undertaken, exploring the intermediates isolated from the procedure and an exploration of the reactivity using tool compounds. The stoichiometric process was also investigated to generate kinetics and a postulated transition state. Scheme 1-2. Optimised conditions of organocatalytic sulfoxidation discussed in Chapter 2. [see thesis for graphic representation];Chapter 3 contains the experimental procedures and analytical data generated for all the compounds synthesised within this thesis
Multi-dimensional thermal response & permeability characterization for porous ablative materials
Get PDFIn space missions, the atmospheric entries present a critical challenge for the design of spacecraft due to the extreme external environment that they must endure. Thermal protection systems (TPSs) are required to prevent any damage to the spacecraft, its internal components or passengers. A very common and highly reliable TPS type is based on the use of ablative materials. The improvement of the ablator simulation procedure in its entirety, from the fist phases of the design process to the exceptionally accurate modelling of the material behaviour in the final stages, is the focus of the study herein presented. In order to achieve this goal, two activities were completed: the creation of a new simulation tool and the precise characterization of porous material permeability. The simulation tool consists of a novel and low computationally demanding coupled methodology able to simulate the three-dimensional behaviour of ablative TPSs. This tool is composed by the Ablative Response Code (ARC), which was specifically designed for this task, and reduced order aero-thermodynamic models. The property characterization was performed using the DSMC (Direct Simulation Monte Carlo) method. This activity evaluated the changes in permeability, commonly considered constant, caused by the variations in temperature and pressure occurring during a (re-)entry. The combination of the activities generated for this dissertation can be used for both the design of future mission TPSs and the development of next generation ablative materials. Simulation results produced for several test cases with different planets' atmospheres and examples of possible applications are presented as confirmation of the developed methods relevance for ablative design and development.In space missions, the atmospheric entries present a critical challenge for the design of spacecraft due to the extreme external environment that they must endure. Thermal protection systems (TPSs) are required to prevent any damage to the spacecraft, its internal components or passengers. A very common and highly reliable TPS type is based on the use of ablative materials. The improvement of the ablator simulation procedure in its entirety, from the fist phases of the design process to the exceptionally accurate modelling of the material behaviour in the final stages, is the focus of the study herein presented. In order to achieve this goal, two activities were completed: the creation of a new simulation tool and the precise characterization of porous material permeability. The simulation tool consists of a novel and low computationally demanding coupled methodology able to simulate the three-dimensional behaviour of ablative TPSs. This tool is composed by the Ablative Response Code (ARC), which was specifically designed for this task, and reduced order aero-thermodynamic models. The property characterization was performed using the DSMC (Direct Simulation Monte Carlo) method. This activity evaluated the changes in permeability, commonly considered constant, caused by the variations in temperature and pressure occurring during a (re-)entry. The combination of the activities generated for this dissertation can be used for both the design of future mission TPSs and the development of next generation ablative materials. Simulation results produced for several test cases with different planets' atmospheres and examples of possible applications are presented as confirmation of the developed methods relevance for ablative design and development
Bio-inspired acoustic sensors and systems - from biology to engineering exploiting feedback computation
Get PDFIn order to design sensors and systems that can be sensitive to small signal levels even when immersed by background noise, may require out-of-the-box thinking. Biology can provide inspiration to achieve that, allowing the engineering landscape to borrow interesting ideas with the aim to solve current human problems. Biological sensor, system and signal processing designs are a result of many million years of evolutionary processes, which make them very-power efficient and well-adapted to perform their functions in a living organism.;This thesis is an example of how acoustic engineering can look into biology in order to get inspiration to design novel ways for detecting, encoding and processing sound information. Sometimes the challenges behind innovation are on finding the proper tools to conceptualize and prototype novel ideas. Bio-inspired engineering offers a possible pathway for new technological advances using theoretical reasoning and appropriate physical modelling. Therefore, this body of work is a research study, which borrows ideas from biology and employs engineering techniques to prototype some new concepts of sensors, systems and signal processing.;Moreover, it suggests an unconventional methodology in acoustic engineering, aiming to demonstrate that novel acoustic sensor system concepts can perform peripheral signal processing at the transducer level such like some natural sensory systems do. Here, from the engineering perspective, the aim is to delay as much as possible the digitalization task while exploiting analogue mechanical-electrical-feedback based computations, therefore, a smart acoustic sensory system concept can be created targeting real-time signal processing applications.In order to design sensors and systems that can be sensitive to small signal levels even when immersed by background noise, may require out-of-the-box thinking. Biology can provide inspiration to achieve that, allowing the engineering landscape to borrow interesting ideas with the aim to solve current human problems. Biological sensor, system and signal processing designs are a result of many million years of evolutionary processes, which make them very-power efficient and well-adapted to perform their functions in a living organism.;This thesis is an example of how acoustic engineering can look into biology in order to get inspiration to design novel ways for detecting, encoding and processing sound information. Sometimes the challenges behind innovation are on finding the proper tools to conceptualize and prototype novel ideas. Bio-inspired engineering offers a possible pathway for new technological advances using theoretical reasoning and appropriate physical modelling. Therefore, this body of work is a research study, which borrows ideas from biology and employs engineering techniques to prototype some new concepts of sensors, systems and signal processing.;Moreover, it suggests an unconventional methodology in acoustic engineering, aiming to demonstrate that novel acoustic sensor system concepts can perform peripheral signal processing at the transducer level such like some natural sensory systems do. Here, from the engineering perspective, the aim is to delay as much as possible the digitalization task while exploiting analogue mechanical-electrical-feedback based computations, therefore, a smart acoustic sensory system concept can be created targeting real-time signal processing applications
Looking back and moving forward : an exploration of survivors' narratives of historical institutional child abuse
Get PDFAt a time when nations and states across the world are critically examining historical childcare practices, it may be overlooked that until the late 1980s, there was little public awareness of the abuse of children in public care. Since then, despite public inquiries, autobiographies and scholarly writing, little research has explored the influence of such experiences on care leavers' lives. This study sets out to address this.;Fourteen adult care leavers shared personal narratives of childhood experiences in residential care between 1915 and the early 1970s and adult lives thereafter. Experiences varied widely but narratives converged in that all identified themselves as having encountered what is now known as historical institutional child abuse. Most identified this as having impacted varyingly on personal identity, self-confidence, adult relationships and emotional wellbeing. This study explores survivors' narratives and the process whereby they made meaning of experiences of historical institutional child abuse over the course of their lives.;To fully understand survivors' narratives, it was necessary to consider a number of contextual factors. Interviews with ten participants from service provider agencies helped explain the obstacles encountered by survivor participants in completing their life narratives while literature illuminated the changing constructs of childhood, child abuse and children's rights; changes in law, the developing notion of transitional justice and the process whereby historical institutional child abuse has come to be perceived as historical injustice.;These have been influenced in turn by processes associated with late modernity, which impacted on personal lives and service providers' systems and practice. Arguably what has been the public narrative of the care of vulnerable children in Scotland historically is now being challenged by survivors' narratives.;This study offers lessons for practice, in respect of survivors of historical institutional child abuse and children in care today.At a time when nations and states across the world are critically examining historical childcare practices, it may be overlooked that until the late 1980s, there was little public awareness of the abuse of children in public care. Since then, despite public inquiries, autobiographies and scholarly writing, little research has explored the influence of such experiences on care leavers' lives. This study sets out to address this.;Fourteen adult care leavers shared personal narratives of childhood experiences in residential care between 1915 and the early 1970s and adult lives thereafter. Experiences varied widely but narratives converged in that all identified themselves as having encountered what is now known as historical institutional child abuse. Most identified this as having impacted varyingly on personal identity, self-confidence, adult relationships and emotional wellbeing. This study explores survivors' narratives and the process whereby they made meaning of experiences of historical institutional child abuse over the course of their lives.;To fully understand survivors' narratives, it was necessary to consider a number of contextual factors. Interviews with ten participants from service provider agencies helped explain the obstacles encountered by survivor participants in completing their life narratives while literature illuminated the changing constructs of childhood, child abuse and children's rights; changes in law, the developing notion of transitional justice and the process whereby historical institutional child abuse has come to be perceived as historical injustice.;These have been influenced in turn by processes associated with late modernity, which impacted on personal lives and service providers' systems and practice. Arguably what has been the public narrative of the care of vulnerable children in Scotland historically is now being challenged by survivors' narratives.;This study offers lessons for practice, in respect of survivors of historical institutional child abuse and children in care today
Design and development of autonomous robotic machine for knee arthroplasty
No full textRobotic aided surgery has become mainstream in many fields of medical science. Two systems have been developed to assist unicompartmental knee arthroplasty. One of these systems is the Blue Belt system which is a hand-held robotic tool designed to remove the damaged surfaces of the patient's knee to aid the surgeon during knee replacement surgery. Another more expensive system is the Mako Rio robot, it provides better accuracy and precision and is haptic.;However, both the Blue Belt and the Mako Rio robot are expensive which is an obstacle for widespread adoption in the field. These systems are also manually driven by an operating surgeon for historic medico-legal reasons.;In this research, a Novel system was developed to provide the required accuracy and precision but in a more affordable automatic system. It was guided by an OptiTrack motion capture navigation system. A CNC machine was built to drive the cutting burr across the knee joint. Multiple software applications were developed to enable the operation of the system such as communication with the navigation system, cluster marker identification and tracking, path planning, wireless communication, and CNC control. The system can perform the cutting phase in the surgery autonomously.;The system has been tested on two sets of tibia and femur artificial bones and then the cut shape was analysed. The mean error of the cutting process was 1.9 mm with standard deviation of 0.55 mm for the tibial bones. The femural bones also showed improved surface finish.Robotic aided surgery has become mainstream in many fields of medical science. Two systems have been developed to assist unicompartmental knee arthroplasty. One of these systems is the Blue Belt system which is a hand-held robotic tool designed to remove the damaged surfaces of the patient's knee to aid the surgeon during knee replacement surgery. Another more expensive system is the Mako Rio robot, it provides better accuracy and precision and is haptic.;However, both the Blue Belt and the Mako Rio robot are expensive which is an obstacle for widespread adoption in the field. These systems are also manually driven by an operating surgeon for historic medico-legal reasons.;In this research, a Novel system was developed to provide the required accuracy and precision but in a more affordable automatic system. It was guided by an OptiTrack motion capture navigation system. A CNC machine was built to drive the cutting burr across the knee joint. Multiple software applications were developed to enable the operation of the system such as communication with the navigation system, cluster marker identification and tracking, path planning, wireless communication, and CNC control. The system can perform the cutting phase in the surgery autonomously.;The system has been tested on two sets of tibia and femur artificial bones and then the cut shape was analysed. The mean error of the cutting process was 1.9 mm with standard deviation of 0.55 mm for the tibial bones. The femural bones also showed improved surface finish
Novel methods for enhancing accuracy and stability of power hardware-in-the-loop simulations
Get PDFNovel methods for the interface between the simulation and hardware of Power Hardware-In-the-Loop (PHIL) configurations have been analysed, developed and experimentally evaluated in this thesis, for enhancing the applicability of PHIL simulations, increasing its stability and accuracy performance.;Time delay is proven to be a critical limiting factor for PHIL simulations. Appropriately, a characterisation methodology for the time delay present within PHIL has been established, by which individual identification of time delay sources as well as time delay dynamics within the different components are reviewed. As a result, variable time delay has been identified within these configurations and mitigation techniques for the time delay and its variability are presented.;Furthermore, a time delay compensation scheme using Sliding Discrete Fourier Transform (SDFT) is demonstrated experimentally to improve the accuracy and stability of PHIL, even when harmonic components are present.;Detailed stability analysis of PHIL simulations performed provides clarification on the stability conditions of Ideal Transformer Method (ITM) Interface Algorithms (IAs). Additional improvements to PHIL IAs have been evaluated, with novel adaptive IAs established to provide enhanced stability.;Finally, enhancement of applicability of PHIL simulations is also experimentally proven with the implementation of an initialization process to a large scale power system application, in which the time delay compensation algorithm is also integrated.Novel methods for the interface between the simulation and hardware of Power Hardware-In-the-Loop (PHIL) configurations have been analysed, developed and experimentally evaluated in this thesis, for enhancing the applicability of PHIL simulations, increasing its stability and accuracy performance.;Time delay is proven to be a critical limiting factor for PHIL simulations. Appropriately, a characterisation methodology for the time delay present within PHIL has been established, by which individual identification of time delay sources as well as time delay dynamics within the different components are reviewed. As a result, variable time delay has been identified within these configurations and mitigation techniques for the time delay and its variability are presented.;Furthermore, a time delay compensation scheme using Sliding Discrete Fourier Transform (SDFT) is demonstrated experimentally to improve the accuracy and stability of PHIL, even when harmonic components are present.;Detailed stability analysis of PHIL simulations performed provides clarification on the stability conditions of Ideal Transformer Method (ITM) Interface Algorithms (IAs). Additional improvements to PHIL IAs have been evaluated, with novel adaptive IAs established to provide enhanced stability.;Finally, enhancement of applicability of PHIL simulations is also experimentally proven with the implementation of an initialization process to a large scale power system application, in which the time delay compensation algorithm is also integrated
Access Repository Dashboard
Do you manage STAX (Strathclyde Repository)? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!