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A multi-layered mechanism to evaluate the quality of transformed public spaces in Mediterranean waterfronts : the case of Alexandria's waterfront
No full textThe transformation of port cities throughout history has impacted various urban settings. In particular, the transformation and modernization of the Ottoman Empire's port cities has altered urban characteristics, reshaped the urban settings and resulted in new public behavior never existed before. This has been evident in urban spaces and waterfronts where functional, social and perceptual aspects are continually changing. Such a transformation demonstrates the importance of public spaces and their qualities not only on a physical level but also as a stimulator of social life. This is mainly true in Alexandria where its old public spaces (squares) on the waterfront in the city centre play a critical role in the urban structure of the city and its residents' daily life. Enhancing these public spaces requires a complete analysis which generates new knowledge about their quality, current and potential use, as well as future prospects. This research addresses the assessment of public squares in the Eastern harbour of Alexandria, placing emphasis on their physical qualities, setting an appropriate context for people's diverse activities and whether they contribute to users' satisfaction and public life. Utilising a multi-layered method for evaluating these spaces to offer suggestions for improving the quality of life in Alexandria through enhancing the quality of its public spaces, the research strategy develops into a people-based approach and involves studying the analytical context as (a) spatial aspects, by exploring the physical and spatial structure of the selected public spaces and their function, (b) social and perceptual aspects, by exploring the users' perceptions, professional's perceptions and users' behaviour.;The research adopts a case study method choosing five old public spaces (squares) on the waterfront for their characteristic features, and a multi-layered methodological approach. A range of different qualitative and quantitative tools, was implemented systematically including: (1) An impressionistic inventory assessment to explain the current situation of the public spaces, (2) a walking tour assessment to evaluate the qualities of functional, social and perceptual attributes from a professional perspective, (3) observation and behavioural mapping to understand the users' behavioural pattern and finally, (4) an attitude survey involving user reactions to public spaces and visual preference questionnaires to understand the users' perception of the spaces under investigation to interpret various forms of experiences that take place.;The findings reveal several aspects of the selected public squares while emphasizing different qualities that support and stimulate the general liveability of the city life while demonstrating qualities that need to be enhanced. The transformed selected spaces; squares; could not considered as high quality spaces, although there were positive qualities within each. The transformed spaces appeared to have a serious problem in the provision and quality of the public facilities. Others problems, such as safety and poor maintenance emerged as basic problems, which could not be dealt with at the open space level from experts'perspectives. Residents and users considered the transformed spaces have a high potential usage, as they perceive that the quality of the spaces make possible for them to interact with each other. Consequently, this is driven by place attachment. The examination draws some conclusions, which will develop into general recommendations. Underscoring the physical and spatial characteristics of urban space is critical for sustaining social interaction as these demonstrate that it is crucial to have a participatory process of design and management to assert that the delivery of the regenerated spaces (squares) or creating ones should meet the continuously transforming users' expectations.The transformation of port cities throughout history has impacted various urban settings. In particular, the transformation and modernization of the Ottoman Empire's port cities has altered urban characteristics, reshaped the urban settings and resulted in new public behavior never existed before. This has been evident in urban spaces and waterfronts where functional, social and perceptual aspects are continually changing. Such a transformation demonstrates the importance of public spaces and their qualities not only on a physical level but also as a stimulator of social life. This is mainly true in Alexandria where its old public spaces (squares) on the waterfront in the city centre play a critical role in the urban structure of the city and its residents' daily life. Enhancing these public spaces requires a complete analysis which generates new knowledge about their quality, current and potential use, as well as future prospects. This research addresses the assessment of public squares in the Eastern harbour of Alexandria, placing emphasis on their physical qualities, setting an appropriate context for people's diverse activities and whether they contribute to users' satisfaction and public life. Utilising a multi-layered method for evaluating these spaces to offer suggestions for improving the quality of life in Alexandria through enhancing the quality of its public spaces, the research strategy develops into a people-based approach and involves studying the analytical context as (a) spatial aspects, by exploring the physical and spatial structure of the selected public spaces and their function, (b) social and perceptual aspects, by exploring the users' perceptions, professional's perceptions and users' behaviour.;The research adopts a case study method choosing five old public spaces (squares) on the waterfront for their characteristic features, and a multi-layered methodological approach. A range of different qualitative and quantitative tools, was implemented systematically including: (1) An impressionistic inventory assessment to explain the current situation of the public spaces, (2) a walking tour assessment to evaluate the qualities of functional, social and perceptual attributes from a professional perspective, (3) observation and behavioural mapping to understand the users' behavioural pattern and finally, (4) an attitude survey involving user reactions to public spaces and visual preference questionnaires to understand the users' perception of the spaces under investigation to interpret various forms of experiences that take place.;The findings reveal several aspects of the selected public squares while emphasizing different qualities that support and stimulate the general liveability of the city life while demonstrating qualities that need to be enhanced. The transformed selected spaces; squares; could not considered as high quality spaces, although there were positive qualities within each. The transformed spaces appeared to have a serious problem in the provision and quality of the public facilities. Others problems, such as safety and poor maintenance emerged as basic problems, which could not be dealt with at the open space level from experts'perspectives. Residents and users considered the transformed spaces have a high potential usage, as they perceive that the quality of the spaces make possible for them to interact with each other. Consequently, this is driven by place attachment. The examination draws some conclusions, which will develop into general recommendations. Underscoring the physical and spatial characteristics of urban space is critical for sustaining social interaction as these demonstrate that it is crucial to have a participatory process of design and management to assert that the delivery of the regenerated spaces (squares) or creating ones should meet the continuously transforming users' expectations
The effect of environmental stress on antibiotic production by streptomyces
No full textAntibiotic Resistance is a world-wide issue that increases with every year. The World Health Organisation (WHO) has identified priority pathogenic microorganisms with dangerous resistance to 'last-resort' antibiotics, these are the 'ESKAPE' pathogens.To face this problem, we investigated novel antibiotic-producing bacteria. The majority of currently available originate from organisms belonging to the Actinobacteria Phylum. Unfortunately, no significant compounds have been discovered in decades and so this has lead us to search in sparsely researched locations such as the hyper-arid Atacama Desert in Chile and compare them to more commonly researched North European soil samples which are naturally more hydrated. In this project we studied bacteria isolated from soil samples from Chiles Atacama Desert and the west of Scotland. Relevant strains were selected by unique morphology and by antimicrobial-activity. Bioactivity tests were performed on all isolates grown on 4 different media against 'ESKAPE' pathogens, Bacillus subtilis and Saccharomyces cerevisiae across which all were inhibited in the streak assays and all but Klebsiella pneumoniae and Pseudomonas aeruginosa in plug assays. Those presenting relevant bioactive profiles were taxonomically identified using 16S rRNAgene sequencing as members of the genera; Streptomyces, Micromonospora and Methylobacterium. Amongst those, isolate identified as Streptomyces narbones is presented activity against a clinical isolate of carbapenem-resistant Acinetobacterbaumannii. In Addition, Streptomyces puniceus presented a unique morphology that was not seen before in Streptomyces. Moreover, elicitation of bio-active compounds from antimicrobial-producing isolates was achieved by increasing osmotic stress or supplementing with Nitrogen or Humic acid. Further studies to compliment this project would include whole-genome sequencing of the most interesting strains in tandem with mass spectrometry to identify the active compounds and activation of crypticbiosynthetic gene clusters through elicitation.Antibiotic Resistance is a world-wide issue that increases with every year. The World Health Organisation (WHO) has identified priority pathogenic microorganisms with dangerous resistance to 'last-resort' antibiotics, these are the 'ESKAPE' pathogens.To face this problem, we investigated novel antibiotic-producing bacteria. The majority of currently available originate from organisms belonging to the Actinobacteria Phylum. Unfortunately, no significant compounds have been discovered in decades and so this has lead us to search in sparsely researched locations such as the hyper-arid Atacama Desert in Chile and compare them to more commonly researched North European soil samples which are naturally more hydrated. In this project we studied bacteria isolated from soil samples from Chiles Atacama Desert and the west of Scotland. Relevant strains were selected by unique morphology and by antimicrobial-activity. Bioactivity tests were performed on all isolates grown on 4 different media against 'ESKAPE' pathogens, Bacillus subtilis and Saccharomyces cerevisiae across which all were inhibited in the streak assays and all but Klebsiella pneumoniae and Pseudomonas aeruginosa in plug assays. Those presenting relevant bioactive profiles were taxonomically identified using 16S rRNAgene sequencing as members of the genera; Streptomyces, Micromonospora and Methylobacterium. Amongst those, isolate identified as Streptomyces narbones is presented activity against a clinical isolate of carbapenem-resistant Acinetobacterbaumannii. In Addition, Streptomyces puniceus presented a unique morphology that was not seen before in Streptomyces. Moreover, elicitation of bio-active compounds from antimicrobial-producing isolates was achieved by increasing osmotic stress or supplementing with Nitrogen or Humic acid. Further studies to compliment this project would include whole-genome sequencing of the most interesting strains in tandem with mass spectrometry to identify the active compounds and activation of crypticbiosynthetic gene clusters through elicitation
The role of sphingosine-1-phosphate in the epithelial to mesenchymal transition in cancer cells
No full textSphingosine-1-Phosphate (S1P) is a bioactive lipid that has been shown to regulate hallmark cancer characteristics, one of which is Epithelial to Mesenchymal Transition (EMT). EMT is the mechanism by which an epithelial cell gains the motility to migrate throughout the body by shifting from a stationary epithelial phenotype to a migratory mesenchymal phenotype. The aim of this study was to investigate the role S1P plays in EMT, proliferation and migration in A549 lung epithelial carcinoma and PANC-1 pancreatic epithelial carcinoma cell lines. Changes in the expression of E-cadherin (an epithelial cell marker) and vimentin (amesenchymal cell marker) were difficult to detect, which compromised the aim to investigate the role for S1P. However, results revealed that S1P2, S1P3 and S1P4 receptors were functional within A549 cells. The phospho-p38 MAPK pathway was coupled to these receptors when activated selectively, particularly for S1P3, and activation of all three receptor types inhibited proliferation. S1P stimulation however, promoted migration of A549 cells. PANC-1 cells also had the unexpected presence of S1P4 receptors. Activation of S1P4 in these cells decreased proliferation but increased PANC-1 cell migration and phosphorylation of ERK-1/2 and p38MAPK. PANC-1 cells also contained functional S1P1 and S1P2 receptors that inhibited proliferation. Overall, a pharmacological approach demonstrated that S1P receptors regulate cancer cell proliferation, migration and signal pathways in a cell-specific manner.Sphingosine-1-Phosphate (S1P) is a bioactive lipid that has been shown to regulate hallmark cancer characteristics, one of which is Epithelial to Mesenchymal Transition (EMT). EMT is the mechanism by which an epithelial cell gains the motility to migrate throughout the body by shifting from a stationary epithelial phenotype to a migratory mesenchymal phenotype. The aim of this study was to investigate the role S1P plays in EMT, proliferation and migration in A549 lung epithelial carcinoma and PANC-1 pancreatic epithelial carcinoma cell lines. Changes in the expression of E-cadherin (an epithelial cell marker) and vimentin (amesenchymal cell marker) were difficult to detect, which compromised the aim to investigate the role for S1P. However, results revealed that S1P2, S1P3 and S1P4 receptors were functional within A549 cells. The phospho-p38 MAPK pathway was coupled to these receptors when activated selectively, particularly for S1P3, and activation of all three receptor types inhibited proliferation. S1P stimulation however, promoted migration of A549 cells. PANC-1 cells also had the unexpected presence of S1P4 receptors. Activation of S1P4 in these cells decreased proliferation but increased PANC-1 cell migration and phosphorylation of ERK-1/2 and p38MAPK. PANC-1 cells also contained functional S1P1 and S1P2 receptors that inhibited proliferation. Overall, a pharmacological approach demonstrated that S1P receptors regulate cancer cell proliferation, migration and signal pathways in a cell-specific manner
Development of biomimetic MEMS microphones inspired by Ormia Ochracea working in audio range
Get PDFThe design, fabrication, characterization and analysis of two categories of novel Micro-electro-mechanical-system microphones inspired by the fly Ormia ochracea's ears are presented in this thesis. The first category is the microphone composed of two coaxial single crystal silicon plates rotating along the same beam fixed to a certain thickness substrate that produces four resonance frequencies - two more resonance frequencies than previously published designs, which broadens the working frequency bands that having efficient directional response. Depending on the position of the torsional beam, the first can also be divided into two models: the symmetric dual-plate model and the asymmetric dual-plate model. Both models use the same fabrication process, and the mechanical vibrations of their diaphragms are sensed by deposited piezoelectric material. The symmetric dual-plate model offers sine dependence response at the two rocking modes and cosine dependence response at the bending modes. The asymmetric dual-plate is built to unify the directional response at four resonance frequencies. Its torsional beam is biased from the centre in order to create a mass difference between the diaphragm on the two sides of the torsional beam, which not only results in cosine dependence responses at all four resonance frequencies but also beyond the resonance. The second category is designed particularly for low-frequency hearing aids that enhances the acoustic response at low frequency band below 3 kHz. This microphone has two resonance frequencies of which one is down to 500 Hz, and it is also allocated both capacitive comb-finger sensing and piezoelectric sensing units. It has uniform bi-directional response below the frequency of interest. Chapter 1 gives the basic knowledge of the acoustic and microphones as well as the literature review of Omira ochracea and its previous inspired microphones. Chapter 2 and Chapter 3 relate to the dual-plate multi-band operational microphones, including their modal analysis, finite element simulation and electrical measurement. Chapter 4 presents the MEMS microphone operating at low-frequency range. The noise performance is improved along with the development process. Chapter 5 summaries the features of each categories and lists the future work of the research.The design, fabrication, characterization and analysis of two categories of novel Micro-electro-mechanical-system microphones inspired by the fly Ormia ochracea's ears are presented in this thesis. The first category is the microphone composed of two coaxial single crystal silicon plates rotating along the same beam fixed to a certain thickness substrate that produces four resonance frequencies - two more resonance frequencies than previously published designs, which broadens the working frequency bands that having efficient directional response. Depending on the position of the torsional beam, the first can also be divided into two models: the symmetric dual-plate model and the asymmetric dual-plate model. Both models use the same fabrication process, and the mechanical vibrations of their diaphragms are sensed by deposited piezoelectric material. The symmetric dual-plate model offers sine dependence response at the two rocking modes and cosine dependence response at the bending modes. The asymmetric dual-plate is built to unify the directional response at four resonance frequencies. Its torsional beam is biased from the centre in order to create a mass difference between the diaphragm on the two sides of the torsional beam, which not only results in cosine dependence responses at all four resonance frequencies but also beyond the resonance. The second category is designed particularly for low-frequency hearing aids that enhances the acoustic response at low frequency band below 3 kHz. This microphone has two resonance frequencies of which one is down to 500 Hz, and it is also allocated both capacitive comb-finger sensing and piezoelectric sensing units. It has uniform bi-directional response below the frequency of interest. Chapter 1 gives the basic knowledge of the acoustic and microphones as well as the literature review of Omira ochracea and its previous inspired microphones. Chapter 2 and Chapter 3 relate to the dual-plate multi-band operational microphones, including their modal analysis, finite element simulation and electrical measurement. Chapter 4 presents the MEMS microphone operating at low-frequency range. The noise performance is improved along with the development process. Chapter 5 summaries the features of each categories and lists the future work of the research
Development of technologies for a toxoplasma gondii vaccine
Get PDFStudies were undertaken to test the utility of Surface Antigen 1 (SAG1), a surface glycoprotein and Cyclophilin 18 (TgCyc18) a chemokine mimic specific for CCR5 as a vaccine in a murine model of T. gondii infection. SAG1 has been shown to provide some protection against infection in previous studies. As Cyc18 induces, IL-12 when it binds to CCR5 it could act as an adjuvant to drive Th1 and CD8+ T cell development. As SAG1 is known to undergo post-translational modification, initial experiments focused on development of a novel eukaryotic expression system. The system as envisaged would utilise heterologous expression of filamentous L. mexicana secreted acid phosphatases fused to the proteins of interest in Leishmania tarentolae. It was anticipated that these filaments would facilitate purification. Plasmids were constructed and transfected into L. tarentolae. Recombinant parasites were found to express and secrete the fusion protein into the media. The identities of proteins were confirmed by immunoblot, immunofluorescence, ELISA, and mass spectrometry. Levels of secreted proteins were too low for vaccination studies. DNA vaccination was used as an alternative approach.;TgSAG1 and TgCyc18 genes were cloned into the eukaryotic expression vector (pVAX-1). pVAX-Cyc18 induced IL-12 in murine bone marrow-derived dendritic cells. The inclusion of TgCyc18 gene in the vaccine augmented Th1 cell activation in BALB/c mice as their splenocytes produced significantly greater levels of IFN-ɣ, TNF-α, IL-2 and IgG2a compared with mice vaccinated with SAG1 alone. These mice also had reduced weight loss compared with mice vaccinated with SAG1 alone. Addition of SAG4 and SAG4.2 genes to this vaccine cocktail conferred significant protection following oral challenge with T. gondii cysts as measured by the reduction of mortality rate and reduced body weight loss. These results demonstrate that TgCyc18 has potential as adjuvant in multicomponent vaccines where a Th1 response is required.Studies were undertaken to test the utility of Surface Antigen 1 (SAG1), a surface glycoprotein and Cyclophilin 18 (TgCyc18) a chemokine mimic specific for CCR5 as a vaccine in a murine model of T. gondii infection. SAG1 has been shown to provide some protection against infection in previous studies. As Cyc18 induces, IL-12 when it binds to CCR5 it could act as an adjuvant to drive Th1 and CD8+ T cell development. As SAG1 is known to undergo post-translational modification, initial experiments focused on development of a novel eukaryotic expression system. The system as envisaged would utilise heterologous expression of filamentous L. mexicana secreted acid phosphatases fused to the proteins of interest in Leishmania tarentolae. It was anticipated that these filaments would facilitate purification. Plasmids were constructed and transfected into L. tarentolae. Recombinant parasites were found to express and secrete the fusion protein into the media. The identities of proteins were confirmed by immunoblot, immunofluorescence, ELISA, and mass spectrometry. Levels of secreted proteins were too low for vaccination studies. DNA vaccination was used as an alternative approach.;TgSAG1 and TgCyc18 genes were cloned into the eukaryotic expression vector (pVAX-1). pVAX-Cyc18 induced IL-12 in murine bone marrow-derived dendritic cells. The inclusion of TgCyc18 gene in the vaccine augmented Th1 cell activation in BALB/c mice as their splenocytes produced significantly greater levels of IFN-ɣ, TNF-α, IL-2 and IgG2a compared with mice vaccinated with SAG1 alone. These mice also had reduced weight loss compared with mice vaccinated with SAG1 alone. Addition of SAG4 and SAG4.2 genes to this vaccine cocktail conferred significant protection following oral challenge with T. gondii cysts as measured by the reduction of mortality rate and reduced body weight loss. These results demonstrate that TgCyc18 has potential as adjuvant in multicomponent vaccines where a Th1 response is required
Solid-state lasers with tunable output properties enabled by MEMS mirrors
Get PDFThe use of micro-electro-mechanical systems (MEMS) as intracavity elements in lasers has grown in interest in recent decades. A variety of MEMS mirrors have recently been shown to provide miniaturized alternatives to conventional Q-switch devices. They have the potential to reduce system cost through batch fabrication and reduce the electrical power demand of such systems. The aim of this thesis was to investigate the novel use of MEMS mirrors within solid-state lasers as intracavity tuning elements.;The MEMS mirrors used for this work were fabricated using a commercial multi-user process that has been used and characterized extensively by the Centre for Microsystems and Photonics. Two MEMS mirror designs were investigated: one with four electrothermal (ET) actuators and one with an electrostatic (ES) comb-drive actuator. Both mirrors could be driven at their mechanical resonance to result in resonant scanning, while the ET mirror could also be tilted to a fixed angle. The ES mirror movement occurred on one axis while the tilt angle of the ET mirror could be controlled on two axes due to the radial positioning of the four ET actuators. Both mirrors were optically coated after fabrication to enhance their reflectance in the near infrared.;The fabricated MEMS mirrors were investigated as intracavity tuning elements for three solid-state laser concepts. The first was a Q-switched Nd: YAG laser with tunable temporal characteristics enabled by separate actuation of two MEMS mirrors. The second was an Yb: KGW laser with tunable output wavelength enabled by a prism and an ET mirror in the Littman configuration. The third was a Q-switched Yb: KGW laser with tunable output wavelength and pulse duration enabled by dual-axis actuation of a single ET mirror combined with a prism in the Littman configuration.;To my knowledge, the above-mentioned investigations are the first of their kind and show clear potential for the advancement of MEMS in solid-state laser technology. Such lasers could be appealing for biomedical and automotive applications such as photoacoustic imaging and lidar. Development of a reliable method to deposit a high-reflectance coating on the surface of the MEMS mirrors would also enable power-scaling of the laser output, making the concepts compatible with defence and manufacturing applications such as range finding and laser processing.The use of micro-electro-mechanical systems (MEMS) as intracavity elements in lasers has grown in interest in recent decades. A variety of MEMS mirrors have recently been shown to provide miniaturized alternatives to conventional Q-switch devices. They have the potential to reduce system cost through batch fabrication and reduce the electrical power demand of such systems. The aim of this thesis was to investigate the novel use of MEMS mirrors within solid-state lasers as intracavity tuning elements.;The MEMS mirrors used for this work were fabricated using a commercial multi-user process that has been used and characterized extensively by the Centre for Microsystems and Photonics. Two MEMS mirror designs were investigated: one with four electrothermal (ET) actuators and one with an electrostatic (ES) comb-drive actuator. Both mirrors could be driven at their mechanical resonance to result in resonant scanning, while the ET mirror could also be tilted to a fixed angle. The ES mirror movement occurred on one axis while the tilt angle of the ET mirror could be controlled on two axes due to the radial positioning of the four ET actuators. Both mirrors were optically coated after fabrication to enhance their reflectance in the near infrared.;The fabricated MEMS mirrors were investigated as intracavity tuning elements for three solid-state laser concepts. The first was a Q-switched Nd: YAG laser with tunable temporal characteristics enabled by separate actuation of two MEMS mirrors. The second was an Yb: KGW laser with tunable output wavelength enabled by a prism and an ET mirror in the Littman configuration. The third was a Q-switched Yb: KGW laser with tunable output wavelength and pulse duration enabled by dual-axis actuation of a single ET mirror combined with a prism in the Littman configuration.;To my knowledge, the above-mentioned investigations are the first of their kind and show clear potential for the advancement of MEMS in solid-state laser technology. Such lasers could be appealing for biomedical and automotive applications such as photoacoustic imaging and lidar. Development of a reliable method to deposit a high-reflectance coating on the surface of the MEMS mirrors would also enable power-scaling of the laser output, making the concepts compatible with defence and manufacturing applications such as range finding and laser processing
Additive manufacturing (3D print) of air-coupled diaphragm ultrasonic transdrucers
Get PDFAir-coupled ultrasound is a non-contact technology that has become increasingly common in Non Destructive Evaluation (NDE) and material evaluation. Normally, the bandwidth of a conventional transducer can be enhanced, but with a cost to its sensitivity. However, low sensitivity is very disadvantageous in air-coupled devices. This thesis proposes a methodology for improving the bandwidth of an air-coupled micro-machined ultrasonic transducer (MUT) without sensitivity loss by connecting a number of resonating pipes of various length to a cavity in the backplate. This design is inspired by the pipe organ musical instrument, where the resonant frequency (pitch) of each pipe is mainly determined by its length. The −6 dB bandwidth of the "pipe organ" inspired air-coupled transducer is 55.7% and 58.5% in transmitting and receiving modes, respectively, which is ∼5 times wider than a custom-built standard device. After validating the concept via a series of single element low-frequency prototypes, two improved designs: the multiple element and the high-frequency single element pipe organ transducers were simulated in order to tailor the pipe organ design to NDE applications.Although the simulated and experimental performance of the pipe organ inspired transducers are proved to be significantly better than the conventional designs, conventional micro-machined technologies are not able to satisfy their required 3D manufacturing resolution. In recent years, there has been increasing interest in using additive manufacturing (3D printing) technology to fabricate sensors and actuators due to rapid prototyping, low-cost manufacturing processes, customized features and the ability to create complex 3D geometries at micrometre scale. This work combines the ultrasonic diaphragm transducer design with a novel stereolithographic additive manufacturing technique. This includes developing a multi-material fabrication process using a commercial digital light processing printer and optimizing the formula of custom-built functional (conductive and piezoelectric) materials. A set of capacitive acoustic and ultrasonic transducers was fabricated using the additive manufacturing technology. The additive manufactured capacitive transducers have a receiving sensitivity of up to 0.4 mV/Pa at their resonant frequency.Air-coupled ultrasound is a non-contact technology that has become increasingly common in Non Destructive Evaluation (NDE) and material evaluation. Normally, the bandwidth of a conventional transducer can be enhanced, but with a cost to its sensitivity. However, low sensitivity is very disadvantageous in air-coupled devices. This thesis proposes a methodology for improving the bandwidth of an air-coupled micro-machined ultrasonic transducer (MUT) without sensitivity loss by connecting a number of resonating pipes of various length to a cavity in the backplate. This design is inspired by the pipe organ musical instrument, where the resonant frequency (pitch) of each pipe is mainly determined by its length. The −6 dB bandwidth of the "pipe organ" inspired air-coupled transducer is 55.7% and 58.5% in transmitting and receiving modes, respectively, which is ∼5 times wider than a custom-built standard device. After validating the concept via a series of single element low-frequency prototypes, two improved designs: the multiple element and the high-frequency single element pipe organ transducers were simulated in order to tailor the pipe organ design to NDE applications.Although the simulated and experimental performance of the pipe organ inspired transducers are proved to be significantly better than the conventional designs, conventional micro-machined technologies are not able to satisfy their required 3D manufacturing resolution. In recent years, there has been increasing interest in using additive manufacturing (3D printing) technology to fabricate sensors and actuators due to rapid prototyping, low-cost manufacturing processes, customized features and the ability to create complex 3D geometries at micrometre scale. This work combines the ultrasonic diaphragm transducer design with a novel stereolithographic additive manufacturing technique. This includes developing a multi-material fabrication process using a commercial digital light processing printer and optimizing the formula of custom-built functional (conductive and piezoelectric) materials. A set of capacitive acoustic and ultrasonic transducers was fabricated using the additive manufacturing technology. The additive manufactured capacitive transducers have a receiving sensitivity of up to 0.4 mV/Pa at their resonant frequency
Optimising non-destructive examination of newbuilding ship hull structures by developing a data-centric risk and reliability framework based on fracture mechanics
Get PDFThis thesis was previously held under moratorium from 18/11/19 to 18/11/21Ship structures are made of steel members that are joined with welds. Welded connections may contain various imperfections. These imperfections are inherent to this joining technology. Design rules and standards are based on the assumption that welds are made to good a workmanship level. Hence, a ship is inspected during construction to make sure it is reasonably defect-free. However, since 100% inspection coverage is not feasible, only partial inspection has been required by classification societies. Classification societies have developed rules, standards, and guidelines specifying the extent to which inspection should be performed.In this research, a review of rules and standards from classification bodies showed some limitations in current practices. One key limitation is that the rules favour a “one-size-fits-all” approach. In addition to that, a significant discrepancy exists between rules of different classification societies.In this thesis, an innovative framework is proposed, which combines a risk and reliability approach with a statistical sampling scheme achieving targeted and cost-effective inspections. The developed reliability model predicts the failure probability of the structure based on probabilistic fracture mechanics. Various uncertain variables influencing the predictive reliability model are identified, and their effects are considered. The data for two key variables, namely, defect statistics and material toughness are gathered and analysed using appropriate statistical analysis methods.A reliability code is developed based Convolution Integral (CI), which estimates the predictive reliability using the analysed data. Statistical sampling principles are then used to specify the number required NDT checkpoints to achieve a certain statistical confidence about the reliability of structure and the limits set by statistical process control (SPC). The framework allows for updating the predictive reliability estimation of the structure using the inspection findings by employing a Bayesian updating method.The applicability of the framework is clearly demonstrated in a case study structure.Ship structures are made of steel members that are joined with welds. Welded connections may contain various imperfections. These imperfections are inherent to this joining technology. Design rules and standards are based on the assumption that welds are made to good a workmanship level. Hence, a ship is inspected during construction to make sure it is reasonably defect-free. However, since 100% inspection coverage is not feasible, only partial inspection has been required by classification societies. Classification societies have developed rules, standards, and guidelines specifying the extent to which inspection should be performed.In this research, a review of rules and standards from classification bodies showed some limitations in current practices. One key limitation is that the rules favour a “one-size-fits-all” approach. In addition to that, a significant discrepancy exists between rules of different classification societies.In this thesis, an innovative framework is proposed, which combines a risk and reliability approach with a statistical sampling scheme achieving targeted and cost-effective inspections. The developed reliability model predicts the failure probability of the structure based on probabilistic fracture mechanics. Various uncertain variables influencing the predictive reliability model are identified, and their effects are considered. The data for two key variables, namely, defect statistics and material toughness are gathered and analysed using appropriate statistical analysis methods.A reliability code is developed based Convolution Integral (CI), which estimates the predictive reliability using the analysed data. Statistical sampling principles are then used to specify the number required NDT checkpoints to achieve a certain statistical confidence about the reliability of structure and the limits set by statistical process control (SPC). The framework allows for updating the predictive reliability estimation of the structure using the inspection findings by employing a Bayesian updating method.The applicability of the framework is clearly demonstrated in a case study structure
Understanding performance measurement from a social systems perspective
Get PDFThis thesis was previously held under moratorium from 3 December 2019 to 3 December 2021.Performance measurement (PM) systems fail to predict organisational outcomes reliably because organisations face futures so inherently unknowable that it is impossible to comprehend the full range of potential outcomes open to them. Organisations are complex, adaptive, social systems whose distinctive activity is decision-making. They are heterogeneous entities whose capabilities, behaviours, and circumstances are unique, emerging from their histories and previous decisions. Organisational reality is a social construct delivered through practice. This thesis investigates whether considering PM from a social systems perspective improves PM’s effectiveness. The argument made is organisations connect through social systems and operate through practice with people, processes, and their interactions fundamental to how they perform. A middle-range management theory is presented aimed at making organisations the best they can be with the resources available to them and in the economic circumstances they find themselves. It does this by understanding and reconfiguring the organisation’s social system using a structured approach to optimise business processes and performance measures based on a combination of emergent behaviour and practice. Given the reality of radical uncertainty the focus is not on predicting outcomes but on uncovering the explanatory mechanisms behind events caused by specific managed improvement interventions. Understanding the behaviour of dynamically interacting components is done using realist evaluation based on social interactions, emergent powers and social intervention mechanisms. This approach changed behaviours and performance outcomes in case study organisations. The use of an ‘inside-out’ social systems perspective, coupled to critical realism with its focus on explanation, enabled the causal relationships of importance to be identified and the performance ‘black box’ to be opened up. This research contributes to closing the PMM theory-practice gap by proposing the performance focus needs to be on the social system rather than the measures, that is, on the ‘means’ rather than the ‘ends’. It also offers a competing theoretical framework to organisational control theory for PMM, one grounded in social systems and practice theory. The social systems perspective is not considered specific to PM and potentially can be applied to all other business processesPerformance measurement (PM) systems fail to predict organisational outcomes reliably because organisations face futures so inherently unknowable that it is impossible to comprehend the full range of potential outcomes open to them. Organisations are complex, adaptive, social systems whose distinctive activity is decision-making. They are heterogeneous entities whose capabilities, behaviours, and circumstances are unique, emerging from their histories and previous decisions. Organisational reality is a social construct delivered through practice. This thesis investigates whether considering PM from a social systems perspective improves PM’s effectiveness. The argument made is organisations connect through social systems and operate through practice with people, processes, and their interactions fundamental to how they perform. A middle-range management theory is presented aimed at making organisations the best they can be with the resources available to them and in the economic circumstances they find themselves. It does this by understanding and reconfiguring the organisation’s social system using a structured approach to optimise business processes and performance measures based on a combination of emergent behaviour and practice. Given the reality of radical uncertainty the focus is not on predicting outcomes but on uncovering the explanatory mechanisms behind events caused by specific managed improvement interventions. Understanding the behaviour of dynamically interacting components is done using realist evaluation based on social interactions, emergent powers and social intervention mechanisms. This approach changed behaviours and performance outcomes in case study organisations. The use of an ‘inside-out’ social systems perspective, coupled to critical realism with its focus on explanation, enabled the causal relationships of importance to be identified and the performance ‘black box’ to be opened up. This research contributes to closing the PMM theory-practice gap by proposing the performance focus needs to be on the social system rather than the measures, that is, on the ‘means’ rather than the ‘ends’. It also offers a competing theoretical framework to organisational control theory for PMM, one grounded in social systems and practice theory. The social systems perspective is not considered specific to PM and potentially can be applied to all other business processe
Engineering fungal-mycelia for soil improvement
Get PDFThis thesis was previously held under moratorium from 19/11/2019 to 2/07/2021.Most of the conventional materials, processes and techniques used by geotechnical engineers for ground improvement are associated with the emission of greenhouse gases. Global targets for reducing carbon emissions therefore pose a direct challenge to research and practice in the field of geotechnical engineering and has led to the development of interdisciplinary approaches seeking alternative low carbon technologies that are resilient to climate change. This thesis presents a novel, potentially low-carbon technique involving the use of fungal hyphal networks of Pleurotus ostreatus (P. ostreatus) for ground engineering applications. An investigation was carried out to understand the range of environmental conditions suitable for growth of P. ostreatus in sand. Subsequently, the influence of the growth of P. ostreatus on the hydraulic and mechanical behaviour of sand was explored, in particular the influence on soil wettability, soil water retention curve, infiltration behaviour, saturated hydraulic conductivity and the stress-strain behaviour of sands. In addition, the influence of growth of P. ostreatus on the erodibility of sand was assessed using the Jet erosion test. The results presented in this thesis demonstrate that the treatment of sand with P. ostreatus (i) induced extreme water repellency, (ii) caused a shift of the soil water retention curve increasing the air entry value from ~0.6 to 6 kPa (iii) reduced the rate of infiltration of water into sand (iv) lowered saturated hydraulic conductivity by one order of magnitude from 1.3 x 10-4 to 3.1 x 10-5 ms-1 (v) inhibited the development of dilatancy during shearing with an associated loss of peak shear strength and (vi) significantly improved the resistance of sand to erosion. These results provide for the first time, evidence of the influence of the growth of fungal hyphae on the hydro-mechanical behaviour of soils within a geotechnical engineering context. The findings of this thesis implies that there is the potential to deploy fungal hyphal networks as a low carbon technique in areas of ground improvement where resistance of surface erosion and/or the creation of a semi-permeable barrier is required.Most of the conventional materials, processes and techniques used by geotechnical engineers for ground improvement are associated with the emission of greenhouse gases. Global targets for reducing carbon emissions therefore pose a direct challenge to research and practice in the field of geotechnical engineering and has led to the development of interdisciplinary approaches seeking alternative low carbon technologies that are resilient to climate change. This thesis presents a novel, potentially low-carbon technique involving the use of fungal hyphal networks of Pleurotus ostreatus (P. ostreatus) for ground engineering applications. An investigation was carried out to understand the range of environmental conditions suitable for growth of P. ostreatus in sand. Subsequently, the influence of the growth of P. ostreatus on the hydraulic and mechanical behaviour of sand was explored, in particular the influence on soil wettability, soil water retention curve, infiltration behaviour, saturated hydraulic conductivity and the stress-strain behaviour of sands. In addition, the influence of growth of P. ostreatus on the erodibility of sand was assessed using the Jet erosion test. The results presented in this thesis demonstrate that the treatment of sand with P. ostreatus (i) induced extreme water repellency, (ii) caused a shift of the soil water retention curve increasing the air entry value from ~0.6 to 6 kPa (iii) reduced the rate of infiltration of water into sand (iv) lowered saturated hydraulic conductivity by one order of magnitude from 1.3 x 10-4 to 3.1 x 10-5 ms-1 (v) inhibited the development of dilatancy during shearing with an associated loss of peak shear strength and (vi) significantly improved the resistance of sand to erosion. These results provide for the first time, evidence of the influence of the growth of fungal hyphae on the hydro-mechanical behaviour of soils within a geotechnical engineering context. The findings of this thesis implies that there is the potential to deploy fungal hyphal networks as a low carbon technique in areas of ground improvement where resistance of surface erosion and/or the creation of a semi-permeable barrier is required
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