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1
Kolbl, Josef Karl. "Low-noise frequency synthesis and picosecond timing for satellite laser ranging systems." Thesis, University of Central Lancashire, 2001. http://clok.uclan.ac.uk/20201/.
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The main aims of the research are to develop various high-speed hardware circuits based on the latest electronic devices and integrated circuit technologies to provide time measurement with one picosecond accuracy, thereby enabling the development of a satellite laser ranging (SLR) system with submillimeter precision. Different types of oscillators and frequency multipliers have been developed (RF and microwave) in order to provide a synchronous and low phase noise clock signal to the SLR timing system, which is phase-locked to the Universal Time Clock (UTC). A technique to quantify phase noise in signal sources is presented and verified. The development of the ranging system encompasses the analog timing verniers, the digital timing system, acquisition and processing of the ranging data, and the controlling of the peripherals, like the laser. The mixed analog/digital timing system architecture provides a time interval determination of two events with picosecond accuracy. Optical calibration techniques and an electronic timing calibration technique were developed to provide calibration of the timing system down to one picosecond accuracy and femtoseconds of resolution, traceable to the International Standard (speed of light, metric standard). The work done has led to several electronic modules for measuring precisely laser runtimes to artificial satellites and to the Moon which are now in successful and permanent operation in five SLR stations around Tokyo, one SLR station in Australia, and one SLR station in Germany. Furthermore, the work has produced three papers and two patents and won the First Prize of Innovation Awards from Deggendorf Government. The research and development work pushed the picosecond timing technology to an extent where the SLR stations in Australia, Tokyo and Germany now have a significant improvement in their ranging data accuracy in comparison to their previous timing equipment, thereby achieving more precise environmental monitoring.
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Macwhannell, Robert. "An investigation of Organisational Carbon Accounting (OCA) practices in the defence sector to determine how these can best support low carbon technology innovation." Thesis, University of Central Lancashire, 2018. http://clok.uclan.ac.uk/23077/.
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‘Climate change’ and ‘defence’ are becoming closely associated topics, particularly in relation to the potential that the defence sector has to support the development of low carbon technologies. This exploratory research applies an inductive approach and a strongly archival strategy in order to investigate how Organisational Carbon Accounting (OCA) practices in the defence sector can best support low carbon technology innovation. It takes an interdisciplinary approach to the literature, drawing on the fields of Carbon Accounting, Defence Industrial Policy, and Innovation Studies. It finds that there some difficulties allocating emissions to organisations in existing OCAs, which are particularly marked in the defence sector due to close working relationships between organisations. These allocations can result in abstract OCAs that do not always reflect the underlying activities causing emissions to be produced. In contrast, ‘Project Level’ Carbon Accounts focused on large-scale collaborative programmes can better account for the emissions of the defence sector in an understandable way that engages new and relevant actors to defence-energy debates. These accounts are therefore more likely than existing OCA practices to support low carbon technology development across innovation networks. A positive selection environment for low carbon technologies can be promoted if these ‘Project-Level’ Carbon Accounts are presented within an appropriate strategic framework, and this research describes the relevance of the defence sector concepts of ‘resilience’ and ‘endurance’ and the related metric of the Fully Burdened Cost of Energy (FBCE). The findings emphasise the value of sector-level analyses of OCA practices, which are not represented in the literature at present. The sector-level perspective can help identify relevant methods from the wider Carbon Accounting field that can improve existing organisational approaches. More importantly, it can help researchers engage with the fundamental question of what Carbon Accounting is for, by analysing how the OCA practices within a specific sector support or inhibit its most effective contribution to climate change mitigation.
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Thakore, Renuka. "A strategic engagement model for delivering energy efficiency initiatives in the English housing sector." Thesis, University of Central Lancashire, 2016. http://clok.uclan.ac.uk/18647/.
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Housing sectors have particular significance and impact on resource use, deployment and sustainability. Given this, they are inextricably enmeshed in a raft of conjoined issues, ranging from energy, production and consumption, through to effective governance structures and leveraged sustainable transformations. However, the real challenges facing the Housing sectors rest with the supportive societal structures which underpin the operationalisation of these issues. This includes such factors as consultation and engagement, and the identification of critical drivers and proven solutions – which are tangible barriers for sustainable transformations (particularly in the English housing system). This research presents a conceptual model – STRIDES (Strategic Tri-level Relational Interventions for Delivering Energy efficiency and Sustainability), which purposefully addresses the aforementioned barriers, and critically challenges thinking and engagement. STRIDES explicitly captures 5-INs, which embodies interrelated essential conditions needed for successful transformation. This conceptual model was developed using a mixed-method approach, engaging constructivism/interpretivism to guide the development and augmentation of this (to ensure maximum relevance and impact). The English housing system was used as the primary lens – which helped both shape and inform the research methodological approach. STRIDES was developed through: an online survey questionnaire (for systems-knowledge); Delphi questionnaires (for target-knowledge); and focus group discussions (for transformative-knowledge). The theoretical constructs and methods revealed exclusive hidden dialogue of composite correlated multi-perspective stakeholders, which highlighted tri-level influences on interdependent system-components for effective governance of sustainable transformations. Recognising and prioritising relationally responsive emerging strategies arising from STRIDES help stakeholders appreciate subtle nuances and forces across and beyond contexts. This helps positioning, especially to shape/tailor strategic interventions to deliver meaningful objectives of these sustainable transformations.
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Prince, Mark. "Smart microsystems for cell manipulations." Thesis, Aston University, 2006. http://publications.aston.ac.uk/12241/.
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This thesis documents the design, manufacture and testing of a passive and non-invasive micro-scale planar particle-from-fluid filter for segregating cell types from a homogeneous suspension. The microfluidics system can be used to separate spermatogenic cells from testis biopsy samples, providing a mechanism for filtrate retrieval for assisted reproduction therapy. The system can also be used for point-of-service diagnostics applications for hospitals, lab-on-a-chip pre-processing and field applications such as clinical testing in the third world. Various design concepts are developed and manufactured, and are assessed based on etched structure morphology, robustness to variations in the manufacturing process, and design impacts on fluid flow and particle separation characteristics. Segregation was measured using image processing algorithms that demonstrate efficiency is more than 55% for 1 µl volumes at populations exceeding 1 x 107. the technique supports a significant reduction in time over conventional processing, in the separation and identification of particle groups, offering a potential reduction in the associated cost of the targeted procedure. The thesis has developed a model of quasi-steady wetting flow within the micro channel and identifies the forces across the system during post-wetting equalisation. The model and its underlying assumptions are validated empirically in microfabricated test structures through a novel Micro-Particle Image Velocimetry technique. The prototype devices do not require ancillary equipment nor additional filtration media, and therefore offer fewer opportunities for sample contamination over conventional processing methods. The devices are disposable with minimal reagent volumes and process waste. Optimal processing parameters and production methods are identified with any improvements that could be made to enhance their performance in a number of identified potential applications.
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Bansal, Dheeraj. "An advanced real-time predictive maintenance framework for large scale machine systems." Thesis, Aston University, 2005. http://publications.aston.ac.uk/12235/.
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This thesis introduces and develops a novel real-time predictive maintenance system to estimate the machine system parameters using the motion current signature. A crucial concept underpinning this project is that the motion current signature contains information relating to the machine system parameters and that this information can be extracted using nonlinear mapping techniques, such as neural networks. Towards this end, a proof of concept procedure is performed, which substantiates this concept. A simulation model, TuneLearn, is developed to simulate the large amount of training data required by the neural network approach. Statistical validation and verification of the model is performed to ascertain confidence in the simulated motion current signature. Validation experiment concludes that, although, the simulation model generates a good macro-dynamical mapping of the motion current signature, it fails to accurately map the micro-dynamical structure due to the lack of knowledge regarding performance of higher order and nonlinear factors, such as backlash and compliance. Failure of the simulation model to determine the micro-dynamical structure suggests the presence of nonlinearity in the motion current signature. This motivated us to perform surrogate data testing for nonlinearity in the motion current signature. Results confirm the presence of nonlinearity in the motion current signature, thereby, motivating the use of nonlinear techniques for further analysis. Outcomes of the experiment show that nonlinear noise reduction combined with the linear reverse algorithm offers precise machine system parameter estimation using the motion current signature for the implementation of the real-time predictive maintenance system. Finally, a linear reverse algorithm, BJEST, is developed and applied to the motion current signature to estimate the machine system parameters.
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Slack, Paul Stephen. "A novel detection method for determining a surgeon's fatigue and hand tremor." Thesis, Aston University, 2007. http://publications.aston.ac.uk/12238/.
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The thesis presents new methodology and algorithms that can be used to analyse and measure the hand tremor and fatigue of surgeons while performing surgery. This will assist them in deriving useful information about their fatigue levels, and make them aware of the changes in their tool point accuracies. This thesis proposes that muscular changes of surgeons, which occur through a day of operating, can be monitored using Electromyography (EMG) signals. The multi-channel EMG signals are measured at different muscles in the upper arm of surgeons. The dependence of EMG signals has been examined to test the hypothesis that EMG signals are coupled with and dependent on each other. The results demonstrated that EMG signals collected from different channels while mimicking an operating posture are independent. Consequently, single channel fatigue analysis has been performed. In measuring hand tremor, a new method for determining the maximum tremor amplitude using Principal Component Analysis (PCA) and a new technique to detrend acceleration signals using Empirical Mode Decomposition algorithm were introduced. This tremor determination method is more representative for surgeons and it is suggested as an alternative fatigue measure. This was combined with the complexity analysis method, and applied to surgically captured data to determine if operating has an effect on a surgeon’s fatigue and tremor levels. It was found that surgical tremor and fatigue are developed throughout a day of operating and that this could be determined based solely on their initial values. Finally, several Nonlinear AutoRegressive with eXogenous inputs (NARX) neural networks were evaluated. The results suggest that it is possible to monitor surgeon tremor variations during surgery from their EMG fatigue measurements.
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Shalan, Mohamad A. "The integration of multi-source data to improve the classification of remotely sensed images." Thesis, Aston University, 2005. http://publications.aston.ac.uk/12246/.
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The number of remote sensing platforms and sensors rises almost every year, yet much work on the interpretation of land cover is still carried out using either single images or images from the same source taken at different dates. Two questions could be asked of this proliferation of images: can the information contained in different scenes be used to improve the classification accuracy and, what is the best way to combine the different imagery? Two of these multiple image sources are MODIS on the Terra platform and ETM+ on board Landsat7, which are suitably complementary. Daily MODIS images with 36 spectral bands in 250-1000 m spatial resolution and seven spectral bands of ETM+ with 30m and 16 days spatial and temporal resolution respectively are available. In the UK, cloud cover may mean that only a few ETM+ scenes may be available for any particular year and these may not be at the time of year of most interest. The MODIS data may provide information on land cover over the growing season, such as harvest dates, that is not present in the ETM+ data. Therefore, the primary objective of this work is to develop a methodology for the integration of medium spatial resolution Landsat ETM+ image, with multi-temporal, multi-spectral, low-resolution MODIS \Terra images, with the aim of improving the classification of agricultural land. Additionally other data may also be incorporated such as field boundaries from existing maps. When classifying agricultural land cover of the type seen in the UK, where crops are largely sown in homogenous fields with clear and often mapped boundaries, the classification is greatly improved using the mapped polygons and utilising the classification of the polygon as a whole as an apriori probability in classifying each individual pixel using a Bayesian approach. When dealing with multiple images from different platforms and dates it is highly unlikely that the pixels will be exactly co-registered and these pixels will contain a mixture of different real world land covers. Similarly the different atmospheric conditions prevailing during the different days will mean that the same emission from the ground will give rise to different sensor reception. Therefore, a method is presented with a model of the instantaneous field of view and atmospheric effects to enable different remote sensed data sources to be integrated.
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Kamnis, Spyros. "Development of multiphase and multiscale mathematical models for thermal spray process." Thesis, Aston University, 2007. http://publications.aston.ac.uk/12243/.
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High velocity oxyfuel (HVOF) thermal spraying is one of the most significant developments in the thermal spray industry since the development of the original plasma spray technique. The first investigation deals with the combustion and discrete particle models within the general purpose commercial CFD code FLUENT to solve the combustion of kerosene and couple the motion of fuel droplets with the gas flow dynamics in a Lagrangian fashion. The effects of liquid fuel droplets on the thermodynamics of the combusting gas flow are examined thoroughly showing that combustion process of kerosene is independent on the initial fuel droplet sizes. The second analysis copes with the full water cooling numerical model, which can assist on thermal performance optimisation or to determine the best method for heat removal without the cost of building physical prototypes. The numerical results indicate that the water flow rate and direction has noticeable influence on the cooling efficiency but no noticeable effect on the gas flow dynamics within the thermal spraying gun. The third investigation deals with the development and implementation of discrete phase particle models. The results indicate that most powder particles are not melted upon hitting the substrate to be coated. The oxidation model confirms that HVOF guns can produce metallic coating with low oxidation within the typical standing-off distance about 30cm.
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Bambury, M. C. "Development of a sediment yield model for South East Ghana in the regions around Lake Volta." Thesis, Aston University, 2007. http://publications.aston.ac.uk/12245/.
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In Ghana, a country with an expanding population and high potential for economic growth, agriculture is an important resource; however, most of the crop production is restricted to low technology shifting cultivation agriculture. The high intensity seasonal rainfall coincides with the early growing period of many of the crops meaning that plots are very susceptible to erosion, especially on steep sided valleys in the region south of Lake Volta. This research investigated the processes of soil erosion by rainfall with the aim of producing a sediment yield model for a small semi-agricultural catchment in rural Ghana. Various types of modelling techniques were considered to discover those most applicable to the sub-tropical environment of Southern Ghana. Once an appropriate model had been developed and calibrated, the aim was to look at how to enable the scaling up of the model using sub-catchments to calculate sedimentation rates of Lake Volta. An experimental catchment was located in Ghana, south west of Lake Volta, where data on rainstorms and the associated streamflow, sediment loads and soil data (moisture content, classification and particle size distribution) was collected to calibrate the model. Additional data was obtained from the Soil Research Institute in Ghana to explore calibration of the Universal Soil Loss Equation (USLE, Wischmeier and Smith, 1978) for Ghanaian soils and environment. It was shown that the USLE could be successfully converted to provide meaningful soil loss estimates in the Ghanaian environment. However, due to experimental difficulties, the proposed theory and methodology of the sediment yield model could only be tested in principle. Future work may include validation of the model and subsequent scaling up to estimate sedimentation rates in Lake Volta.
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Tam, B. K. Y. "A novel actuated digit with tactile feedback for clinical applications." Thesis, Aston University, 2006. http://publications.aston.ac.uk/12247/.
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This thesis describes the work carried out on the development of a novel digit actuator system with tactile perception feedback to a user and demonstrated as a master-slave system. For the tactile surface of the digit, contrasting sensor elements of resistive strain gauges and optical fibre Bragg grating sensors were evaluated. A distributive tactile sensing system consisting of optimised neural networking schemes was developed, resulting in taxonomy of artificial touch. The device is suitable for use in minimal invasive surgical (MIS) procedures as a steerable tip and a digit constructed wholly from polymers makes it suitable for use in Magnetic Resonance Imaging (MRI) environments enabling active monitoring of the patient during a procedure. To provide a realistic template of the work the research responded to the needs of two contrasting procedures: palpation of the prostate and endotracheal intubation in anaesthesia where the application of touch sense can significantly assist navigation. The performance of the approach was demonstrated with an experimental digit constructed for use in the laboratory in phantom trials. The phantom unit was developed to resemble facets of the clinical applications and digit system is able to evaluate reactive force distributions acting over the surface of the digit as well as different descriptions of contact and motion relative to the surface of the lumen. Completing control of the digit is via an instrumented glove, such that the digit actuates in sympathy with finger gesture and tactile information feedback is achieved by a combination of the tactile and visual means.
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Zhang, Yumin. "Virtual manufacturing - a study of some important issues relating to the transformation of traditional manufacturing organisations." Thesis, Aston University, 2006. http://publications.aston.ac.uk/12237/.
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This thesis starts with a literature review, outlining the major issues identified in the literature concerning virtual manufacturing enterprise (VME) transformation. Then it details the research methodology used – a systematic approach for empirical research. next, based on the conceptual framework proposed, this thesis builds three modules to form a reference model, with the purpose of clarifying the important issues relevant to transforming a traditional manufacturing company into a VME. The first module proposes a mechanism of VME transformation – operating along the VME metabolism. The second module builds a management function within a VME to ensure a proper operation of the mechanism. This function helps identify six areas as closely related to VME transformation: lean manufacturing; competency protection; internal operation performance measurement; alliance performance measurement; knowledge management; alliance decision making. The third module continues and proposes an alliance performance measurement system which includes 14 categories of performance indicators. An analysis template for alliance decision making is also proposed and integrated into the first module. To validate these three modules, 7 manufacturing organisations (5 in China and 2 in the UK) were investigated, and these field case studies are analysed in this thesis. The evidence found in these organisations, together with the evidence collected from the literature, including both researcher views and literature case studies, provide support for triangulation evidence. In addition, this thesis identifies the strength and weakness patterns of the manufacturing companies within the theoretical niche of this research, and clarifies the relationships among some major research areas from the perspective of virtual manufacturing. Finally, the research findings are summarised, as well as their theoretical and practical implications. Research limitations and recommendations for future work conclude this thesis.
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Lamont, D. R. "Decompression illness and its regulation in contemporary UK tunnelling : an engineering perspective." Thesis, Aston University, 2006. http://publications.aston.ac.uk/12242/.
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This thesis records the findings of a retrospective study of decompression illness (DCI) in the UK compressed air tunnelling industry since the mid-1980s. The thesis describes how the study arose, its scope and objectives, along with an overview of tunnelling and shaft-sinking. The development of compressed air working techniques is reviewed along with a description of decompression practice and DCI, and an outline of relevant legislation and guidance. The acquisition and manipulation of data to form a number of databases and spreadsheets on which the analysis was performed is discussed. That analysis examined measures of DCI incidence and quantified that incidence using these measures. Also considered is the variation in tolerance and susceptibility to DCI in the workforce, and the phenomenon of acclimatisation. An examination of the extent to which men worked on multiple contracts and the variation in their susceptibility to DCI on these contracts is included. The main conclusions are that a number of measures of DCI incidence were identified, some more appropriate than others and that the incidence of DCI when so measured was high, disproportionately so in shift workers. No reasonably practicable restrictions on exposure were identified which would have allowed the retention of air-only decompression. Oxygen decompression looked promising but had yet to be used sufficiently extensively to generate enough data for analysis. Recommendations included one that an alternative technique for monitoring the effectiveness of decompression should be developed. The thesis ends with recommendations for further research.
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Tran, Tuan D. "Global optimisation of cold-formed steel sections." Thesis, Aston University, 2007. http://publications.aston.ac.uk/12239/.
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In this thesis, standard algorithms are used to carry out the optimisation of cold-formed steel purlins such as zed, channel and sigma sections, which are assumed to be simply supported and subjected to a gravity load. For zed, channel and sigma section, the local buckling, distortional buckling and lateral-torsional buckling are considered respectively herein. Currently, the local buckling is based on the BS 5950-5:1998 and EN 1993-1-3:2006. The distortional buckling is calculated by the direct strength method employing the elastic distortional buckling which is calculated by three available approaches such as Hancock (1995), Schafer and Pekoz (1998), Yu (2005). In the optimisation program, the lateral-torsional buckling based on BS 5950-5:1998, AISI and analytical model of Li (2004) are investigated. For the optimisation program, the programming codes are written for optimisation of channel, zed and sigma beam. The full study has been coded into a computer-based analysis program (MATLAB).
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Petra, Mohamad Iskandar. "Novel hardwired distributive tactile sensing system for medical applications." Thesis, Aston University, 2007. http://publications.aston.ac.uk/12240/.
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This thesis described the research carried out on the development of a novel hardwired tactile sensing system tailored for the application of a next generation of surgical robotic and clinical devices, namely a steerable endoscope with tactile feedback, and a surface plate for patient posture and balance. Two case studies are examined. The first is a one-dimensional sensor for the steerable endoscope retrieving shape and 'touch' information. The second is a two-dimensional surface which interprets the three-dimensional motion of a contacting moving load. This research can be used to retrieve information from a distributive tactile sensing surface of a different configuration, and can interpret dynamic and static disturbances. This novel approach to sensing has the potential to discriminate contact and palpation in minimal invasive surgery (MIS) tools, and posture and balance in patients. The hardwired technology uses an embedded system based on Field Programmable Gate Arrays (FPGA) as the platform to perform the sensory signal processing part in real time. High speed robust operation is an advantage from this system leading to versatile application involving dynamic real time interpretation as described in this research. In this research the sensory signal processing uses neural networks to derive information from input pattern from the contacting surface. Three neural network architectures namely single, multiple and cascaded were introduced in an attempt to find the optimum solution for discrimination of the contacting outputs. These architectures were modelled and implemented into the FPGA. With the recent introduction of modern digital design flows and synthesis tools that essentially take a high-level sensory processing behaviour specification for a design, fast prototyping of the neural network function can be achieved easily. This thesis outlines the challenge of the implementations and verifications of the performances.
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Chu, Xiao-ting. "Failure analysis of cold-formed steel sections." Thesis, Aston University, 2004. http://publications.aston.ac.uk/12234/.
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The purlin-sheeting system has been the subject of numerous theoretical and experimental investigations over the past 30 years, but the complexity of the problem has led to great difficulty in developing a sound and general model. The primary aim of the thesis is to investigate the failure behaviours of cold-formed zed and channel sections for use in purlin-sheeting systems. Both the energy method and finite strip method are used to develop an approach to investigate cold-formed zed and channel section beams with partial-lateral restraint from the metal sheeting when subjected to a uniformly distributed transverse load. The stress analysis of cold-formed zed and channel section beams with partially-lateral restraint from the metal sheeting when subjected to a uniformly distributed transverse load is investigated firstly by using the analytical model based on the energy method in which the restraint actions of the sheeting are modelled by using two springs representing the translational and rotational restraints. The numerical results have showed that the two springs have significantly different influences on the stresses of the beams. The influence of the two springs has also been found to depend on the anti-sag bar and the position of the loading line. A novel method is presented for analysing the elastic local buckling behaviour of cold-formed zed and channel section beams with partial-lateral restraint from metal sheeting when subjected to a uniformly distributed transverse load, which is carried out by inputting the cross sectional stresses with the largest compressive stress into the finite strip analysis. By using the presented novel method, individual influences of warning stress, partially lateral restraints from the sheeting and the dimensions of the cross section and position of the loading line on the buckling behaviour are investigated.
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Chileshe, C. M. "A converter compensator for power factor control in 3-phase induction machines." Thesis, Aston University, 1996. http://publications.aston.ac.uk/12244/.
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The advent of the harmonic neutralised shunt Converter Compensator as a practical means of reactive power compensation in power transmission systems has cleared ground for wider application of this type of equipment. An experimental 24-pulse voltage sourced convector has been successfully applied in controlling the terminal power factor of a 1.5kW, 240V three phase cage rotor induction motor, whose winding has been used in place of the usual phase shifting transformers. To achieve this, modifications have been made to the conventional stator winding of the induction machine. These include an unconventional phase spread and facilitation of compensator connections to selected tapping points between stator coils to give a three phase winding with a twelve phase connection to the twenty four pulse converter. Theoretical and experimental assessments of the impact of these modifications and attachment of the compensator have shown that there is a slight reduction in the torque developed at a given slip and in the combined system efficiency. There is also an increase in the noise level, also a consequence of the harmonics. The stator leakage inductance gave inadequate coupling reactance between the converter and the effective voltage source, necessitating the use of external inductors in each of the twelve phases. The terminal power factor is fully controllable when the induction machine is used either as a motor or as a generator.
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Jenkins, David William. "Risk assessment applied to consumer products with reference to CE marking machines for use at work." Thesis, Aston University, 2004. http://publications.aston.ac.uk/12230/.
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New Approach Directives now govern the health and safety of most products whether destined for workplace or domestic use. These Directives have been enacted into UK law by various specific legislation principally relating to work equipment, machinery and consumer products. This research investigates whether the risk assessment approach used to ensure the safety of machinery may be applied to consumer products. Crucially, consumer products are subject to the Consumer Protection Act (CPA) 1987, where there is no direct reference to 'assessing risk'. This contrasts with the law governing the safety of products used in the workplace, where risk assessment underpins the approach. New Approach Directives are supported by European harmonised standards, and in the case of machinery, further supported by the risk assessment standard, EN 1050. The system regulating consumer product safety is discussed, its key elements identified and a graphical model produced. This model incorporates such matters as conformity assessment, the system of regulation, near miss and accident reporting. A key finding of the research is that New Approach Directives have a common feature of specifying essential performance requirements that provide a hazard prompt-list that can form the basis for a risk assessment (the hazard identification stage). Drawing upon 272 prosecution cases, and with thirty examples examined in detail, this research provides evidence that despite the high degree of regulation, unsafe consumer products still find their way onto the market. The research presents a number of risk assessment tools to help Trading Standards Officers (TSOs) prioritise their work at the initial inspection stage when dealing with subsequent enforcement action.
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He, Bai-sen. "Osmotic dehydration in plant tissues." Thesis, Aston University, 2005. http://publications.aston.ac.uk/12236/.
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The primary aim of the thesis is to provide a comprehensive investigation of the osmotic dehydration processes in plant tissue. Effort has been concentrated on the modelling for simulating the processes. Two mathematical models for simulating the mass transfer during osmotic dehydration processes in plant tissues are developed and verified using existing experimental data. Both models are based on the mechanism of diffusion and convection of any mobile material that can transport in plant tissues. The mass balance equation for the transport of each constituent is established separately for intracellular and extra-cellular volumes with taking into account the mass transfer across the cell membrane the intracellular and extra-cellular volumes and the shrinkage of the whole tissue. The contribution from turgor pressure is considered in both models. Model two uses Darcy’s law to build the relation between shrinkage velocity and hydrostatic pressure in each volume because the plant tissue can be considered as the porous medium. Moreover, it has been extended to solve the multi-dimensional problems. A lot of efforts have been made to the parameter study and the sensitivity analyses. The parameters investigated including the concentration of the osmotic solution, diffusion coefficient, permeability of the cell membrane, elastic modulus of the cell wall, critical cell volume etc. The models allow us to quantitatively simulate the time evolution of intracellular and extra-cellular volumes as well as the time evolution of concentrations in each cross-section.
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Panopoulos, Georgios D. "Economic aspects of safety in the Greek construction industry." Thesis, Aston University, 2003. http://publications.aston.ac.uk/12233/.
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The thesis addresses the economic impacts of construction safety in Greece. The research involved the development of a methodology for determining the overall costs of safety, namely the sum of the costs of accidents and the costs of safety management failures (with or without accident) including image cost. Hitherto, very little work has been published on the cost of accidents in practical case studies. Moreover, to the author’s belief, no research has been published that seeks to determine in real cases the costs of prevention. The methodology developed is new, transparent, and capable of being replicated and adapted to other employment sectors and to other countries. The methodology was applied to three construction projects in Greece to test the safety costing methodology and to offer some preliminary evidence on the business case for safety. The survey work took place between 1999 and 2001 and involved 27 months of costing work on site. The study focuses on the overall costs of safety that apply to the main (principal) contractor. The methodology is supported by 120 discrete cost categories, and systematic criteria for determining which costs are included (counted) in the overall cost of safety. A quality system (in compliance with ISO9000 series) was developed to support the work and ensure accuracy of data gathering. The results of the study offer some support for the business case for safety. Though they offer good support for the economics of safety as they demonstrate need for cost effectiveness. Subject to important caveats, those projects that appeared to manage safety more cost-effectively achieved the lowest overall safety cost. Nevertheless, results are significantly lower than of other published works for two main reasons; first costs due to damages with no potential to injury were not included and second only costs to main constructor were considered. Study’s results are discussed and compared with other publish works.
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Saadat, Nasser. "Thin film bearings with phase change of lubricant." Thesis, Aston University, 1991. http://publications.aston.ac.uk/15380/.
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The possible evaporation of lubricant in fluid film bearings has been investigated theoretically and by experiment using a radial flow hydrostatic bearing supplied with liquid refrigerant R114. Good correlation between measured and theoretical values was obtained using a bespoke computational fluid dynamic model in which the flow was assumed to be laminar and adiabatic. The effects of viscous dissipation and vapour generation within the fluid film are fully accounted for by applying a fourth order Runge-Kutta routine to satisfy the radial and filmwise transverse constraints of momentum, energy and mass conservation. The results indicate that the radial velocity profile remains parabolic while the flow remains in the liquid phase and that the radial rate of enthalpy generation is then constant across the film at a given radius. The results also show that evaporation will commence at a radial location determined by geometry and flow conditions and in fluid layers adjacent to the solid boundaries. Evaporation is shown to progress in the radial direction and the load carrying capacity of such a bearing is reduced significantly. Expressions for the viscosity of the liquid/vapour mixture found in the literature survey have not been tested against experimental data. A new formulation is proposed in which the suitable choice of a characteristic constant yields close representation to any of these expressions. Operating constraints imposed by the design of the experimental apparatus limited the extent of the surface over which evaporation could be obtained, and prevented clear identification of the most suitable relationship for the viscosity of the liquid/vapour mixture. The theoretical model was extended to examine the development of two phase flow in a rotating shaft face seal of uniform thickness. Previous theoretical analyses have been based on the assumption that the radial velocity profile of the flow is always parabolic, and that the tangential component of velocity varies linearly from the value at the rotating surface, to zero at the stationary surface. The computational fluid dynamic analysis shows that viscous shear and dissipation in the fluid adjacent to the rotating surface leads to developing evaporation with a consequent reduction in tangential shear forces.
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(5930396), Jack D. Williams. "Magnetically-Coupled Circuits Systems for Wireless Excitation of Passive Stimulators for Stimulation Therapies and Application as a Treatment for Glaucoma." Thesis, 2019.
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The practice of delivering an electrical current waveform to an excitable tissue such as a structure in the brain, nerve fiber, or muscle to relieve the symptoms of disease constitutes an electrical stimulation therapy. Electrical stimulation therapies supported by implantable devices provide effective treatment options for people suffering from treatment-resistant chronic diseases that often fail to respond to medication and other traditional therapies [1, 2]. However, implantable electrical stimulators traditionally approved by the Food and Drug Administration (FDA) use implanted batteries that require surgical replacement over years of operation and limit therapies to applications with minimal constraints on implant mass, volume, and rigidity [3, 4]. Previous works have proposed to eliminate batteries in implantable stimulators by using magnetically-coupled coils to deliver energy through radio-frequency (RF) fields, exciting alternating currents on implantable devices to be converted into stimulus pulses by rectifiers [5, 6]. Implantable stimulators without batteries may be excited by an alternative theory of operation without the use of RF fields that eliminates the need for a rectifier and permits stimulators with minimal complexity.
This work proposes an original use of magnetically-coupled circuits theory for the wireless excitation of electrical stimulation current waveforms on passive stimulators that eliminates the need for an implanted battery. The principle of the technique is to drive stimulation current waveforms on passive stimulators with electromotive forces excited by applied time-varying magnetic fields via the phenomena described by Faraday’s law of induction [7-9]. The proposed systems require a wearable driving component and a passive driven component that may either be worn or implanted. The wearable driving component must include a battery, pulse-generating circuitry, and a primary coil, whereas the driven component is a passive device requiring only a secondary coil with electrodes to contact tissue. The pulse-generating circuitry of the driving component may be implemented readily such that the design of the coils defines the challenge in the implementation of the proposed systems. The design of the coils for the proposed systems presents the potential for a nontrivial optimization problem with conflicting objectives; possible objectives for the design of the coils include maximizing the attainable peak amplitudes of the stimulation currents, obtaining various characteristics of a desired stimulation current waveform, and minimizing the variation of the stimulation currents with varying displacements between the coils. The problem posed by the design of the coils for the proposed systems is addressed by direction obtained from theoretical analyses and experiments performed in this work that supplement direction from the literature [5, 10-12]. The potential utility of the proposed theory of operation is demonstrated by enabling the first chronic electrical stimulation therapy for glaucoma, the leading cause of irreversible blindness worldwide. The system designed for the glaucoma stimulation therapy and the methods used to quantify its electrical performance are presented along with data from experimental therapeutic trials with human participants.
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(5930270), Mehdi Shishehbor. "Numerical Investigation on the Mechanical Properties of Neat Cellulose Nanocrystal." Thesis, 2020.
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Nature has evolved efficient strategies to make materials with hierarchical internal structure that often exhibit exceptional mechanical properties. One such example is found in cellulose, which has achieved a high order of functionality and mechanical properties through a hierarchical structure with an exceptional control from the atomic level all the way to the macroscopic level. Cellulose is present in a wide variety of living species (trees, plants, algae, bacteria, tunicates), and provides the base reinforcement structure used by organisms for high mechanical strength, high strength-to-weight ratio, and high toughness. Additionally, being the most abundant organic substance on earth, cellulose has been used by our society as an engineering material for thousands of years, and are prolific within our society, as demonstrated by the enormity of the world-wide industries in cellulose derivatives, paper/packaging, textiles, and forest products.
More recently, a new class of cellulose base particles are being extracted from plants/trees, cellulose nanocrystals (CNCs), which are spindle-shaped nano-sized particles (3 ̶ 20 nm in width and 50 ̶ 500 nm in length) that are distinct from the more traditional cellulose materials currently used (e.g. molecular cellulose and wood pulp). They offer a new combination of particle morphology, properties and chemical functionalities that enable CNCs for use in applications that were once thought impossible for cellulosic materials.
CNCs have shown utility in many engineering applications, for example, biomedical, nanocomposites, barrier/separation membranes and cementitious materials. To gain greater insight as to how best use CNCs in various engineering application areas, a comprehensive understanding of the mechanics of CNCs is needed. The characterization of the mechanical properties of nanomaterials via experimental testing has always been challenging due to their small size, resulting in large uncertainties related to testing near sensitivity limits of a given technique, the same is true when characterizing CNCs. For CNCs, to help offset limitations in experimental testing, numerical modeling has been useful in predicting the mechanical properties of CNCs. We present a continuum-based structural model to study the mechanical behavior of cellulose nanocrystals (CNCs), and analyze the effect of bonded and non-bonded interactions on the mechanical properties under various loading conditions. In particular, this model assumes the uncoupling between the bonded and nonbonded interactions and their behavior is obtained from atomistic simulations.
For large deformations and when there is interaction and dynamics of many particles involved, continuum models could become as expensive as MD simulations. In addition, it has been shown that traditional material models in the continuum mechanics context, cannot model all the mechanical properties of CNC, especially for large deformation. To overcome these setbacks and to be able to model real size of CNC, 50-1000 nm, and/or to increase the number of particles involved in the simulation, a so called ‘‘coarse-grained’’ (CG) model for mechanical and interfacial properties of CNC is proposed. The proposed CG model is based on both mechanical properties and crystal-crystal interactions. Parametrization of the model is carried out in comparison with all-atom (AA) molecular dynamics and experimental results of some specific mechanical and interfacial tests.
Subsequently, verification is done with other tests. Finally, we analyze the effect of interface properties on the mechanical performance of CNC-based materials including, bending of a CNC bundle, tensile load and fracture in bioinspired structure of CNCs such as staggered brick-and-mortar and Bouligand structures of interest.
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(11186220), Julianna Gesun. "Beyond Surviving: Developing and Testing a Model of Thriving for Engineering Students." Thesis, 2021.
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The goal of my dissertation is to take a step toward shifting the narrative in engineering from “surviving” to “thriving” so that more engineering students can reach their full potential in college and beyond. Many engineering students experience barriers such as the hardships of engineering culture, which are exacerbated for women and underrepresented racial/ethnic minorities(such as Black, Latinx, and Indigenous students). These barriers are well documented in research and well discussed in interventions to support engineering student success, under the assumption that helping students cope with these cultural and systemic barriers will, by itself, lead to their success. My research on engineering thriving challenges this assumption by asserting that the skills engineering students need to succeed academically, socially, and personally differ from the skills they need to “survive” cultural and systemic barriers.This dissertation employs an exploratory multiphase research design, with three studies, to develop a model of thriving for undergraduate engineering students. The first study consists of a scoping literature review of 68 papers to define and characterize engineering thriving as the process in which engineering students develop and refine competencies that allow them to function optimally in engineering programs. From this definition, the second study employs a Delphi process with 47 experts to develop a model of engineering thriving that includes 1) internal thriving competencies; 2) external thriving outcomes; 3) engineering culture, systemic factors, resources, context and situation; and 4) how these three broader categories function together. The third study tests some of these relationships proposed in the model of engineering thriving using structural equation modeling(SEM) on a large dataset of responses by over 2,000 undergraduate U.S. engineering students to a survey that measured various constructs associated with thriving. Findings from the SEM analysis suggest that gratitude was one of the most important competencies for engineering student thriving, and that a holistic model approach accounted for 79% of the variance in engineering students’ belongingness and 25% of the variance in perceptions of faculty caring(two external thriving outcomes).
Understanding and supporting more engineering thriving has positive implications for students, recruitment and outreach, and engineering programs. Thriving is multidimensional and, thus, supporting engineering students to achieve traditional success metrics (such as academic performance and graduation) goes hand in hand with supporting their personal and social development and wellbeing. Recruitment and outreach of K-12 students can benefit from viewing engineering as an attractive and inspirational career, combating negative stereotypes that currently deter students from pursuing engineering. Engineering programs can benefit from developing a reputation and culture of thriving. However, cultural change requires the collective investment from all members of the engineering community.
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(10716507), Alexis Margaret Corda. "Advancements of a Silicon-on-Insulator Thermoelectric Sensor for Biomedical Applications." Thesis, 2021.
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Heat can be used as a reliable biomarker of cell metabolism. Assessing changes in metabolic activity is useful to study normal bioactivity or factors which may stimulate or inhibit cell proliferation. Methods which measure the heat of cell metabolism over time must be sensitive to the small changes. Thermoelectric sensors, which work by the Seebeck effect, are one method which has shown adequate sensitivity. This type of sensor directly converts heat energy into electrical energy without the use of a power source. Current research into sensors for cell metabolism may list lengthy, complex, and expensive procedures or include materials with rare or toxic elements. This work establishes a design approach of a silicon-based thermoelectric sensor for cell metabolism measurement which incorporates abundant and non-toxic materials and a simple procedure based on standard MEMS fabrication methods. The foundation for the sensor design is discussed. Fabrication was done using optical lithography, reactive ion etching, and electron beam evaporation which are standard and well known in industry. Sensor quality was characterized successfully based on the defined design parameters. Preliminary data has been recorded on the Coli cell metabolism. Finally, recommendations to improve heat insulation, include sensor calibration, and optimize manufacturing parameters are given for future work on this design to advance sensitivity and commercial potential.
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(10994988), Minglu Li. "ENVIRONMENTAL FACTORS AFFECT SOCIAL ENGINEERING ATTACKS." Thesis, 2021.
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Social engineering attacks can have serious consequences when it comes to information security. A social engineering attack aims at sensitive personal information by using personality weaknesses and using manipulation techniques. Because the user is often seen as the weakest link, techniques like phishing, baiting, and vishing, and deception are used to glean important personal information successfully. This article will analyze the relationship between the environment and social engineering attacks. This data consists of 516 people taking a survey. When it comes to discovering the relationship, there are two parts of the analysis. One is a high-dimensional analysis using multiple algorithms to find a connection between the environment and people’s behavior. The other uses a text analysis algorithm to study the pattern of survey questions, which can help discover why certain people have the same tendency in the same scenario. After combining these two, we might show how people have different reactions when dealing with social engineering attacks due to environmental factors.
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(5929757), James S. Holly. "“Of The Coming Of James”: A Critical Autoethnography On Teaching Engineering To Black Boys As A Black Man." Thesis, 2018.
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In W. E. B. Du Bois’ The Souls of Black Folk there is a story entitled “Of the Coming of John” that features two boys named John, one black from a poor family, the other white from a wealthy family. As the two are away at college each family awaits ‘of the coming of John,’ the title is also a reference to maturity because black John becomes disillusioned with race relations as he is awakened to the injustices that seemed so normal. Like black John, I too went to college far away from my hometown, developed a heightened awareness of society’s racism, and retained a desire to return home to teach youth in my community. And like black John, I want to teach by implementing a pedagogy that promotes equity for black Americans amid inequitable conditions.The research problem addressed in this study relates to the absence of sociopolitical teaching practices in K-12 engineering education, which I argue is necessary for equitable inclusion of underrepresented racial/ethnic minorities in general, and black males in particular. Black Americans are plagued by racial inequities that transcend all domains of societal living (e.g., economics, education, health, etc.); this lamentable reality is the direct result of historical disenfranchisement of this racial group within the United States. Therefore, engineering must be taught with pertinence to the social, political, and cultural realities of the pupils. This self-study was an investigation into my story of living as a black male and studying engineering, and how my experience (along with my sociological understanding of other black males) shaped the way I taught engineering to black boys. Critical autoethnography was used to articulate the cultural and experiential knowledge that guided my instructional methods. Black Critical Theory, an offshoot of Critical Race Theory, served as one theoretical framework for this study because it centralizes the prevalence of anti-blackness as a lens to understand the experiences of black citizens. African American Male Theory is a complementary framework as it takes a broader ecological perspective to analyze the experiences of black male citizens. Taken together, these frameworks reveal the distinct features of American life negotiated by black males.
Resultantly, my life events led me to merge black racial identity, black politics, and the dynamics surrounding the education of black boys to teach K-12 engineering within a critical race pedagogical framework. I was socialized to be present and authentic among the people I want to lead and serve, hence, my devotion to community-engage scholarship. I grew tired of watching educators give-up on black students or become volatile, therefore, I spent time with the hyper-marginalized to build up the requisite resilience to avoid dysfunctional teaching and a cynical demeanor. I have felt undervalued and left-out in some classroom experiences, so I prioritize connecting with students over presenting content. I’ve witnessed engineering educators ostracize and belittle students unwilling to assimilate to its cultural norms, contrarily, I taught black boys with the goal of making engineering relatable to them, not vice versa.