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Vulnerability of short range wireless technologies to impulsive noise in electricity substations
Get PDFThe technical reliability and economic advantages of using sensors, communications and computing to more precisely monitor and control the state of electrical power systems are many. Implementing some of the communications functions wirelessly is cheaper, more flexible and more convenient than an implementation with their wired counterparts. Whilst wireless networks offer these obvious benefits over wired networks, concerns remain which need to be addressed. One such concern is the performance of wireless networks in the electromagnetically aggressive substation environment; an environment that is particularly rich in impulsive noise due to the presence of partial discharge, power electronics switching and other transient processes. -- This thesis investigates the degree to which the dominantly impulsive noise environment of an electricity substation will degrade the performance of wireless technologies, primarily designed to operate in a Gaussian noise environment. -- The electricity-substation noise environment is modelled as both a Middleton class-A process and a symmetric α-stable process. Values of model parameters are estimated from a database of impulsive noise measurements made in a 400/275/132 kV air-insulated substation. Computer simulations are then employed to evaluate the physical layer bit-error-ratio performance of the candidate wireless networking technologies including WLAN, Bluetooth and Zigbee. -- All candidate technologies are shown to suffer a departure in performance degradation from that expected in a Gaussian noise environment in the high SNR region whereas AWGN dominates in the low SNR region. In the high SNR region, there appears to be a noise floor which reduces the effect of an increase in SNR on the corresponding BER.The technical reliability and economic advantages of using sensors, communications and computing to more precisely monitor and control the state of electrical power systems are many. Implementing some of the communications functions wirelessly is cheaper, more flexible and more convenient than an implementation with their wired counterparts. Whilst wireless networks offer these obvious benefits over wired networks, concerns remain which need to be addressed. One such concern is the performance of wireless networks in the electromagnetically aggressive substation environment; an environment that is particularly rich in impulsive noise due to the presence of partial discharge, power electronics switching and other transient processes. -- This thesis investigates the degree to which the dominantly impulsive noise environment of an electricity substation will degrade the performance of wireless technologies, primarily designed to operate in a Gaussian noise environment. -- The electricity-substation noise environment is modelled as both a Middleton class-A process and a symmetric α-stable process. Values of model parameters are estimated from a database of impulsive noise measurements made in a 400/275/132 kV air-insulated substation. Computer simulations are then employed to evaluate the physical layer bit-error-ratio performance of the candidate wireless networking technologies including WLAN, Bluetooth and Zigbee. -- All candidate technologies are shown to suffer a departure in performance degradation from that expected in a Gaussian noise environment in the high SNR region whereas AWGN dominates in the low SNR region. In the high SNR region, there appears to be a noise floor which reduces the effect of an increase in SNR on the corresponding BER
Electrochemical recovery of copper from distillery spent lees
Get PDFWhile the copper stills used in the whiskey purifcation process are vital to its avor profile, low levels of copper corrosion lead to low but environmentally relevant copper concentrations in distillery waste. This is particularly the case for spent lees, the by-product of the second distillation, as, unlike the first distillation by-product, its only avenue is treatment and discharge.;With diminishing copper reserves, it is increasingly necessary to investigate ways that copper waste, including copper containing solutions, can be recovered for reuse. This work investigates electrochemical copper recovery from spent lees. Initial bench-scale studies investigated the impact of spent lees other waste constituents on copper recovery, finding insignificant or insufficiently large differ-ences between the electrochemical behaviour of simulated waste and pure copper solution.;Consequently, copper recovery was tested with weakly acidic copper sulphate in a 4.5 L batch reactor using a porous carbon felt cathode. Application of currents of 105 mA (5 A/m2) could reduce the copper concentration below the reliable detection limit of 2 ppm within 6 hours, albeit at a Coulombic efficiency less than 40 %. Applying less current resulted in lower efficiencies, suspected to be related to corrosion. The efficiency increased to 86.1 + 1.4 % when the current was increased to 1.05 A, and the process duration decreased to under 2 hours.;When operating with real spent lees, the process was slower and less efficient. However, the difference was not statistically significant, predominantly due to uncertain copper concentration measurements. Real spent lees are notably more resistive, resulting in nearly double the energy cost compared to pure copper solution. Consequently, despite reasonable rates and efficiencies, the current process requires too much energy due to the high resistivity of the spent lees.While the copper stills used in the whiskey purifcation process are vital to its avor profile, low levels of copper corrosion lead to low but environmentally relevant copper concentrations in distillery waste. This is particularly the case for spent lees, the by-product of the second distillation, as, unlike the first distillation by-product, its only avenue is treatment and discharge.;With diminishing copper reserves, it is increasingly necessary to investigate ways that copper waste, including copper containing solutions, can be recovered for reuse. This work investigates electrochemical copper recovery from spent lees. Initial bench-scale studies investigated the impact of spent lees other waste constituents on copper recovery, finding insignificant or insufficiently large differ-ences between the electrochemical behaviour of simulated waste and pure copper solution.;Consequently, copper recovery was tested with weakly acidic copper sulphate in a 4.5 L batch reactor using a porous carbon felt cathode. Application of currents of 105 mA (5 A/m2) could reduce the copper concentration below the reliable detection limit of 2 ppm within 6 hours, albeit at a Coulombic efficiency less than 40 %. Applying less current resulted in lower efficiencies, suspected to be related to corrosion. The efficiency increased to 86.1 + 1.4 % when the current was increased to 1.05 A, and the process duration decreased to under 2 hours.;When operating with real spent lees, the process was slower and less efficient. However, the difference was not statistically significant, predominantly due to uncertain copper concentration measurements. Real spent lees are notably more resistive, resulting in nearly double the energy cost compared to pure copper solution. Consequently, despite reasonable rates and efficiencies, the current process requires too much energy due to the high resistivity of the spent lees
Development of a safety culture assessment and improved framework to enhance maritime safety
Get PDFPreviously held under moratorium from 22nd March 2018 until 22nd March 2023.The maritime industry has experienced numerous catastrophic accidents and theseaccidents are traditionally attributed to human and organizational factors. Recently,the shipping industry aims to implement an effective safety culture in order to avoidreoccurrence of these events as requested by the IMO International SafetyManagement (ISM) Code. However, the ISM Code does not provide a structuredassessment and improvement methodology to address this issue and therefore theenvisaged impact has not yet been achieved due to a lack of structured approach toenhance maritime safety culture. Therefore, this thesis aims to develop a novel safety culture assessment and improvement framework to identify safety related problems of any shipping company, address the vulnerabilities and develop improvement strategies to enhance safety culture maturity levels. Such a comprehensive and structured framework which seeks improvement areas via the combinations of the subjective and objective assessments along with action plans does not exist in the maritime domain. The framework proposes three assessments and one improvement sub methods, namely: Safety Climate Assessment, Key Performance Indicators (KPIs) Assessment, Overt Observations and Improvement Methods & Action Plans Firstly, safety culture assessment questionnaires are distributed to the shipping companies and these surveys are supported by semi-structured interviews in order to capture attitude and perceptions of the employees towards safety. Secondly, company key performance indicators are collected and correlated with the survey data for further clarification. KPI data are also used for trend analysis to capture the KPIs which have a positive impact on safety performance of a shipping company. Finally, on board observation studies take place to capture the main drivers of the safety performance of a shipping company. When all the assessments are completed, the action plans and improvement methodologies are proposed to address the identified gaps.The maritime industry has experienced numerous catastrophic accidents and theseaccidents are traditionally attributed to human and organizational factors. Recently,the shipping industry aims to implement an effective safety culture in order to avoidreoccurrence of these events as requested by the IMO International SafetyManagement (ISM) Code. However, the ISM Code does not provide a structuredassessment and improvement methodology to address this issue and therefore theenvisaged impact has not yet been achieved due to a lack of structured approach toenhance maritime safety culture. Therefore, this thesis aims to develop a novel safety culture assessment and improvement framework to identify safety related problems of any shipping company, address the vulnerabilities and develop improvement strategies to enhance safety culture maturity levels. Such a comprehensive and structured framework which seeks improvement areas via the combinations of the subjective and objective assessments along with action plans does not exist in the maritime domain. The framework proposes three assessments and one improvement sub methods, namely: Safety Climate Assessment, Key Performance Indicators (KPIs) Assessment, Overt Observations and Improvement Methods & Action Plans Firstly, safety culture assessment questionnaires are distributed to the shipping companies and these surveys are supported by semi-structured interviews in order to capture attitude and perceptions of the employees towards safety. Secondly, company key performance indicators are collected and correlated with the survey data for further clarification. KPI data are also used for trend analysis to capture the KPIs which have a positive impact on safety performance of a shipping company. Finally, on board observation studies take place to capture the main drivers of the safety performance of a shipping company. When all the assessments are completed, the action plans and improvement methodologies are proposed to address the identified gaps
Young people & volunteering : attitudes and experiences in areas of multiple deprivation
Get PDFIn the run-up to the Year of Young People 2018, youth volunteering was cast in the political limelight following the Scottish Government's intention to 're-invigorate volunteering'. Yet, despite higher levels of youth than adult volunteering, young people's engagement is unequally structured by gender and area-based deprivation. Although there is a significant literature on youth volunteering, comparatively little is known about under-16s and how opportunities for volunteering are shaped by lived experiences in areas of multiple deprivation.;This thesis addresses this gap by examining attitudes towards volunteering, routes and barriers to participation as well as the meanings volunteering acquires for those who do it.;The thesis draws on qualitative fieldwork with male and female volunteers and non volunteers, aged 12-18, and with youth workers in local government and youth organisations. Different perspectives on volunteering are used to frame the ways in which participants approached volunteering. Bourdieu's theory of practice isemployed to explore the relationship between objective conditions and subjective dispositions and their implications for facilitating and impeding volunteering. The concepts of 'bonding' and 'bridging social capital' are also used to understand the nature of participants' relationships and their impact on volunteering.;Findings indicate participants had broadly positive views of volunteering. However, there was widespread belief that it was considered a stigmatised activity due to its perceived incompatibility with peer norms. This stigma was also associated with the lack of information participants received about volunteering, as well as infrastructural issues limiting the support available to them. The notion of the 'participant-to-volunteer' transition is proposed to capture the way in which many participants started volunteering.;This idea reflects the histories volunteers had as attendees at youth organisations prior to volunteering in them. Such foundations provided a base from which calls to volunteer could be responded to positively. Aspects of 'traditional' and 'new' approaches to volunteerism were evident inparticipants' motivations. However, volunteering was predominantly valued for its relational and affective aspects, the sense of agency it provided and the opportunities it facilitated for personal development.In the run-up to the Year of Young People 2018, youth volunteering was cast in the political limelight following the Scottish Government's intention to 're-invigorate volunteering'. Yet, despite higher levels of youth than adult volunteering, young people's engagement is unequally structured by gender and area-based deprivation. Although there is a significant literature on youth volunteering, comparatively little is known about under-16s and how opportunities for volunteering are shaped by lived experiences in areas of multiple deprivation.;This thesis addresses this gap by examining attitudes towards volunteering, routes and barriers to participation as well as the meanings volunteering acquires for those who do it.;The thesis draws on qualitative fieldwork with male and female volunteers and non volunteers, aged 12-18, and with youth workers in local government and youth organisations. Different perspectives on volunteering are used to frame the ways in which participants approached volunteering. Bourdieu's theory of practice isemployed to explore the relationship between objective conditions and subjective dispositions and their implications for facilitating and impeding volunteering. The concepts of 'bonding' and 'bridging social capital' are also used to understand the nature of participants' relationships and their impact on volunteering.;Findings indicate participants had broadly positive views of volunteering. However, there was widespread belief that it was considered a stigmatised activity due to its perceived incompatibility with peer norms. This stigma was also associated with the lack of information participants received about volunteering, as well as infrastructural issues limiting the support available to them. The notion of the 'participant-to-volunteer' transition is proposed to capture the way in which many participants started volunteering.;This idea reflects the histories volunteers had as attendees at youth organisations prior to volunteering in them. Such foundations provided a base from which calls to volunteer could be responded to positively. Aspects of 'traditional' and 'new' approaches to volunteerism were evident inparticipants' motivations. However, volunteering was predominantly valued for its relational and affective aspects, the sense of agency it provided and the opportunities it facilitated for personal development
Maximising wind farm connections : an investigation of novel voltage management and principles of access techniques in active distribution networks
Get PDFPower production from stochastic wind generators connected at the lower voltage levels on the distribution network where weak strength of the network prevails, can make voltage management particularly challenging for network operators. Distribution network operators (DNO's) tend to manage their networks conservatively by imposing stricter operational limits when deciding whether to allow generators to connect or not. Voltage rise limitation is a major barrier and impacts significantly on the capacities of generators that can be connected at lower voltage and weak distribution networks.;This thesis develops and presents novel voltage control techniques which involves a coordination of active network management (ANM) technological solutions and principles of access (PoA) arrangements specific for wind farm connections managed under voltage constraint conditions. The proposed coordinated voltage control and PoA techniques effectively mitigate the voltage rise limitation and enhance the capacity of the network to connect more wind generation. The research presented assesses the performance of the strategy and it quantifies the benefit to the wind generators by using time-series optimal power flow methods on a realistic UK 11 kV distribution network.;The proposed ANM solution provides DNO's alternative control options to address the voltage rise problem to facilitate cheaper and faster DG connections, deferring the need for costly and time-consuming reinforcement. It offers wind farm owners, exible options to minimise excessive curtailment by controlling their voltage at the point of connection. It provides a guide for suitable locations for future wind farm investment. It quantifies the risks and uncertainties associated with the different commercial arrangements and proposes alternative PoA suitable for voltage constrained networks.Power production from stochastic wind generators connected at the lower voltage levels on the distribution network where weak strength of the network prevails, can make voltage management particularly challenging for network operators. Distribution network operators (DNO's) tend to manage their networks conservatively by imposing stricter operational limits when deciding whether to allow generators to connect or not. Voltage rise limitation is a major barrier and impacts significantly on the capacities of generators that can be connected at lower voltage and weak distribution networks.;This thesis develops and presents novel voltage control techniques which involves a coordination of active network management (ANM) technological solutions and principles of access (PoA) arrangements specific for wind farm connections managed under voltage constraint conditions. The proposed coordinated voltage control and PoA techniques effectively mitigate the voltage rise limitation and enhance the capacity of the network to connect more wind generation. The research presented assesses the performance of the strategy and it quantifies the benefit to the wind generators by using time-series optimal power flow methods on a realistic UK 11 kV distribution network.;The proposed ANM solution provides DNO's alternative control options to address the voltage rise problem to facilitate cheaper and faster DG connections, deferring the need for costly and time-consuming reinforcement. It offers wind farm owners, exible options to minimise excessive curtailment by controlling their voltage at the point of connection. It provides a guide for suitable locations for future wind farm investment. It quantifies the risks and uncertainties associated with the different commercial arrangements and proposes alternative PoA suitable for voltage constrained networks
Formation of electronic contracts of sale and its impact on Iraqi traditional commercial contracts
Get PDFThe internet has become a tool for performing contracts in commerce and accordingly, the contract formation process has experienced some significant developments. Generally, these electronic contracting practices have not yet received appropriate treatment in Iraqi law. Consequently, this thesis argues that some traditional contract rules, especially those in the Iraqi Civil Code (ICC) and the Iraqi E-signature and Transactions Act (IESTA), are currently insufficient for regulating legal agreements resulting from new contracts. Although not wholly comparative research, the analysis of the Iraqi law herein will however be accompanied by analysis of Sharia doctrines. Consequently, this thesis fundamentally considers the ICC, the IESTA and Sharia law, but also considers other jurisdictions to a limited degree. The rationale for this is to weigh how other jurisdictions have been successfully dealing with electronic contract formation. The primary objective is to scrutinise the likelihood of embracing appropriate foreign laws for adaptation as suitable amendments of Iraqi law. Sharia law dates back over 1400 years and some of its rules are nowadays inapplicable. The most appropriate example is the Maliki's view, which makes it mandatory for the offeree to accept or reject the offer instantly when the offer reaches him, this view is now in applicable. However, the majority of these rules are still in force. In Iraq, applying the traditional rules of contract formation is out-of-date and such rules are inappropriate for adjudicating disputes arising from the electronic contracting process. This thesis recommends that the Iraqi law must become more efficient and more easily applicable to regulate electronic contracts. In particular, the Iraqi legislature should revise the ICC and IESTA as regards contract formation rules to provide legal certainty in electronic contracting. Accordingly, ICC articles 82, 87 and 88 should be updated to take into consideration the unique nature of contracts formed over the internet. It should also treat new means of communication independently, taking into consideration the different nature of each means, for instance, the postal rule fits to contracts conducted by email, but it does not fit to those conducted by phone calls.The internet has become a tool for performing contracts in commerce and accordingly, the contract formation process has experienced some significant developments. Generally, these electronic contracting practices have not yet received appropriate treatment in Iraqi law. Consequently, this thesis argues that some traditional contract rules, especially those in the Iraqi Civil Code (ICC) and the Iraqi E-signature and Transactions Act (IESTA), are currently insufficient for regulating legal agreements resulting from new contracts. Although not wholly comparative research, the analysis of the Iraqi law herein will however be accompanied by analysis of Sharia doctrines. Consequently, this thesis fundamentally considers the ICC, the IESTA and Sharia law, but also considers other jurisdictions to a limited degree. The rationale for this is to weigh how other jurisdictions have been successfully dealing with electronic contract formation. The primary objective is to scrutinise the likelihood of embracing appropriate foreign laws for adaptation as suitable amendments of Iraqi law. Sharia law dates back over 1400 years and some of its rules are nowadays inapplicable. The most appropriate example is the Maliki's view, which makes it mandatory for the offeree to accept or reject the offer instantly when the offer reaches him, this view is now in applicable. However, the majority of these rules are still in force. In Iraq, applying the traditional rules of contract formation is out-of-date and such rules are inappropriate for adjudicating disputes arising from the electronic contracting process. This thesis recommends that the Iraqi law must become more efficient and more easily applicable to regulate electronic contracts. In particular, the Iraqi legislature should revise the ICC and IESTA as regards contract formation rules to provide legal certainty in electronic contracting. Accordingly, ICC articles 82, 87 and 88 should be updated to take into consideration the unique nature of contracts formed over the internet. It should also treat new means of communication independently, taking into consideration the different nature of each means, for instance, the postal rule fits to contracts conducted by email, but it does not fit to those conducted by phone calls
The place of poetry in victorian Dundee
Get PDFThis thesis was completed on the AHRC-funded collaborative doctoral studentship, 'Poetry, song and community in the industrial city: Victorian Dundee,' a partnership between the University of Strathclyde and Dundee Central Library. Using the library's extensive archival collections of broadsides, published books, newspapers, and manuscripts, I consider the role poetry and song played in the city's public culture during the nineteenth century.;I argue that poetry and song, forms which nineteenth-century writers and performers did not see a clear distinction between, were an essential part of conversations about life in a rapidly changing city for the citizens of Victorian Dundee. This is evident not only through the content of the poems and songs themselves, but also through the changing context of their print and performance. I also argue that the verse culture of Victorian Dundee has had a lasting effect on both literary and folk-song culture in Scotland.;Certain places within the city became a particular focus for these verse conversations. These tend to be places whose meaning and function were central to Dundee's idea of itself as an industrial city. I have selected five places, or types of places, which were the inspiration for and place of composition for poetry, to discuss in detail. These are the River Tay, the city streets, textile workplaces, parks and green spaces, and central meeting rooms. Examining poems and songs about these places, and their distribution and reception, demonstrates the importance of verse culture as a part of daily life in Victorian Dundee.This thesis was completed on the AHRC-funded collaborative doctoral studentship, 'Poetry, song and community in the industrial city: Victorian Dundee,' a partnership between the University of Strathclyde and Dundee Central Library. Using the library's extensive archival collections of broadsides, published books, newspapers, and manuscripts, I consider the role poetry and song played in the city's public culture during the nineteenth century.;I argue that poetry and song, forms which nineteenth-century writers and performers did not see a clear distinction between, were an essential part of conversations about life in a rapidly changing city for the citizens of Victorian Dundee. This is evident not only through the content of the poems and songs themselves, but also through the changing context of their print and performance. I also argue that the verse culture of Victorian Dundee has had a lasting effect on both literary and folk-song culture in Scotland.;Certain places within the city became a particular focus for these verse conversations. These tend to be places whose meaning and function were central to Dundee's idea of itself as an industrial city. I have selected five places, or types of places, which were the inspiration for and place of composition for poetry, to discuss in detail. These are the River Tay, the city streets, textile workplaces, parks and green spaces, and central meeting rooms. Examining poems and songs about these places, and their distribution and reception, demonstrates the importance of verse culture as a part of daily life in Victorian Dundee
Four-wave mixing in rubidium vapour with structured light and an external cavity
Get PDFThis thesis was previously held under moratorium from 26th October 2018 until 15th April 2021.Thermal atomic vapours are an experimentally simple and efficient system in which to study wave mixing processes. We investigate a resonantly enhanced four-wave mixing (FWM) process in rubidium vapour, which coherently converts 780nm and 776nm light to 5.2 µm and 420 nm. Firstly, we use this system to explore the coherent frequency conversion of structured light, in particular Laguerre-Gauss (LG) beams. These modes, and more generally the orbital angular momentum (OAM) that they carry, are important research tools for optical manipulation, imaging and communication. Previous qualitative studies have demonstrated OAM transfer from the near-infrared pump beams to the generated 420nm light. We investigate this further by making the first quantitative measurements of the 420nm transverse mode for a range of values of pump OAM. Our results indicate that the FWM process is likely to be an efficient source of OAM-entangled 5.2 µm and 420nm light, with a spiral bandwidth that increases with increasing pump OAM. Using independently shaped pump beams, we also study FWM for more general pump modes, including beams carrying opposite handedness of OAM, coherent superpositions of LG modes, and for the first time in this system, radial LGmodes. This work shows the importance of OAM conservation and Gouy phase matching in the FWM process, and is relevant for similar schemes involving the inscription and storage of transverse modes in atomic vapours. Finally, we report the first use of a ring cavity to both increase the output power and narrow the linewidth of the generated 420nm light. For Gaussian pump beams, the low-finesse cavity, which is singly resonant with the 420nmlight, increases the maximum 420nm output power from 340 µW (single pass) to 940 µW (cavity-enhanced), and narrows the linewidth from 33MHz (single pass) to < 1MHz (cavity-enhanced), resulting in a narrow linewidth, tunable light source suitable for near resonant rubidium studies.Thermal atomic vapours are an experimentally simple and efficient system in which to study wave mixing processes. We investigate a resonantly enhanced four-wave mixing (FWM) process in rubidium vapour, which coherently converts 780nm and 776nm light to 5.2 µm and 420 nm. Firstly, we use this system to explore the coherent frequency conversion of structured light, in particular Laguerre-Gauss (LG) beams. These modes, and more generally the orbital angular momentum (OAM) that they carry, are important research tools for optical manipulation, imaging and communication. Previous qualitative studies have demonstrated OAM transfer from the near-infrared pump beams to the generated 420nm light. We investigate this further by making the first quantitative measurements of the 420nm transverse mode for a range of values of pump OAM. Our results indicate that the FWM process is likely to be an efficient source of OAM-entangled 5.2 µm and 420nm light, with a spiral bandwidth that increases with increasing pump OAM. Using independently shaped pump beams, we also study FWM for more general pump modes, including beams carrying opposite handedness of OAM, coherent superpositions of LG modes, and for the first time in this system, radial LGmodes. This work shows the importance of OAM conservation and Gouy phase matching in the FWM process, and is relevant for similar schemes involving the inscription and storage of transverse modes in atomic vapours. Finally, we report the first use of a ring cavity to both increase the output power and narrow the linewidth of the generated 420nm light. For Gaussian pump beams, the low-finesse cavity, which is singly resonant with the 420nmlight, increases the maximum 420nm output power from 340 µW (single pass) to 940 µW (cavity-enhanced), and narrows the linewidth from 33MHz (single pass) to < 1MHz (cavity-enhanced), resulting in a narrow linewidth, tunable light source suitable for near resonant rubidium studies
Development and evaluation of a multimodality tracking and navigation assisted robotic fetal surgery system
Get PDFMinimally Invasive Surgeries have been on the rise since the early 1980s and have developed into several forms of Minimal Access Surgeries. Since the amount of anatomical impact is considerably less than open procedures, the principles of such Minimal Access Surgeries have recently been used in intra-uterine fetal procedures. However, these procedures are associated with several difficulties that arise from minimal access, such as decreased visualization, anatomical orientation, precision and force transmission. A combination of micro endoscopy and ultrasound has been widely used to aid the surgeon's perception of anatomical orientation. But the inaccuracies due to the inherent principles of ultrasound and the narrow field of view limit the orientation, perception and anatomical relationship and therefore, can impact the surgical outcome. While handling fragile anatomical structures, the perception of force can be of prime importance which can be limited by the narrow size of the instruments used. Also, the lack of feedback from the instruments used could result in un-noticed overshoot.This project proposed a new robotic surgery system to solve the problems in Minimal Access Fetal Surgeries by improving the perception of visualization, orientation and force feedback. The proposed system is comprised of, a new robotic fetoscope with haptic feedback, integrated with a tracking and navigation system and a complete software environment. Five experiments were performed to evaluate the efficacy of the proposed robotic surgery system in terms of orientation accuracy, dexterity, the time taken for the procedure, force feedback and the effectiveness and implementation of safety parameters of overshoot protection in surgical assistance. The results of the experiments demonstrated a better efficacy can be achieved by using the proposed tracking and navigation system in combination with the robotic equipment. As the proposed system can give the surgeon the positional orientation, precise controls and a better perception of the entire surgery, it is hoped that further improvements in hardware and software user interface can lead to a surgeon friendly system which can save numerous lives in the near future.Minimally Invasive Surgeries have been on the rise since the early 1980s and have developed into several forms of Minimal Access Surgeries. Since the amount of anatomical impact is considerably less than open procedures, the principles of such Minimal Access Surgeries have recently been used in intra-uterine fetal procedures. However, these procedures are associated with several difficulties that arise from minimal access, such as decreased visualization, anatomical orientation, precision and force transmission. A combination of micro endoscopy and ultrasound has been widely used to aid the surgeon's perception of anatomical orientation. But the inaccuracies due to the inherent principles of ultrasound and the narrow field of view limit the orientation, perception and anatomical relationship and therefore, can impact the surgical outcome. While handling fragile anatomical structures, the perception of force can be of prime importance which can be limited by the narrow size of the instruments used. Also, the lack of feedback from the instruments used could result in un-noticed overshoot.This project proposed a new robotic surgery system to solve the problems in Minimal Access Fetal Surgeries by improving the perception of visualization, orientation and force feedback. The proposed system is comprised of, a new robotic fetoscope with haptic feedback, integrated with a tracking and navigation system and a complete software environment. Five experiments were performed to evaluate the efficacy of the proposed robotic surgery system in terms of orientation accuracy, dexterity, the time taken for the procedure, force feedback and the effectiveness and implementation of safety parameters of overshoot protection in surgical assistance. The results of the experiments demonstrated a better efficacy can be achieved by using the proposed tracking and navigation system in combination with the robotic equipment. As the proposed system can give the surgeon the positional orientation, precise controls and a better perception of the entire surgery, it is hoped that further improvements in hardware and software user interface can lead to a surgeon friendly system which can save numerous lives in the near future
Efficient moving mesh methods for Q-tensor models of liquid crystals
Get PDFAs devices using liquid crystals become ever smaller and increasingly complex, there is a commensurate increase in the need for more effective numerical modelling tools in the area. In this thesis, an adaptive finite element method is used to solve a non-linear singularly perturbed boundary value problem which arises from a one dimensional Q-tensor model of liquid crystals.;The adaptive non-uniform mesh is generated by equidistribution of a selection of strictly positive monitor functions. By an appropriate selection of the monitor function parameters, it is shown that the computed numerical solution converges at an optimal rate with respect to the mesh density and that the solution accuracy is robust to the size of the singular perturbation parameter.;A robust and efficient numerical scheme is then used to solve the system of six coupled partial differential equations which arises from Q-tensor theory. The key novel feature is the use of a full moving mesh partial differential equation (MMPDE) approach to generate an adaptive mesh which accurately resolves important solution features.;This includes the use of a new monitor function based on a local measure of biaxiality. The behaviour of the method is illustrated on a one-dimensional time-dependent problem in a π-cell geometry with an applied electric field. The numerical results show that, as well as achieving optimal rates of convergence in space and time, higher levels of solution accuracy and a considerable improvement in computational efficiency are obtained compared to other moving mesh methods used by previous authors on similar problems.;The numerical scheme is then extended to tackle a two-dimensional π-cell problem. It is shown that the adaptive moving mesh method copes well with the presence of moving defects, with the mesh adapting and relaxing to capture the motion, growth and annihilation of the defects.As devices using liquid crystals become ever smaller and increasingly complex, there is a commensurate increase in the need for more effective numerical modelling tools in the area. In this thesis, an adaptive finite element method is used to solve a non-linear singularly perturbed boundary value problem which arises from a one dimensional Q-tensor model of liquid crystals.;The adaptive non-uniform mesh is generated by equidistribution of a selection of strictly positive monitor functions. By an appropriate selection of the monitor function parameters, it is shown that the computed numerical solution converges at an optimal rate with respect to the mesh density and that the solution accuracy is robust to the size of the singular perturbation parameter.;A robust and efficient numerical scheme is then used to solve the system of six coupled partial differential equations which arises from Q-tensor theory. The key novel feature is the use of a full moving mesh partial differential equation (MMPDE) approach to generate an adaptive mesh which accurately resolves important solution features.;This includes the use of a new monitor function based on a local measure of biaxiality. The behaviour of the method is illustrated on a one-dimensional time-dependent problem in a π-cell geometry with an applied electric field. The numerical results show that, as well as achieving optimal rates of convergence in space and time, higher levels of solution accuracy and a considerable improvement in computational efficiency are obtained compared to other moving mesh methods used by previous authors on similar problems.;The numerical scheme is then extended to tackle a two-dimensional π-cell problem. It is shown that the adaptive moving mesh method copes well with the presence of moving defects, with the mesh adapting and relaxing to capture the motion, growth and annihilation of the defects
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