<p> A three dimensional photoelastic method of analyzing the stresses in toroids, such as Bourdon Tubes, is proposed in this thesis, The experimental techniques and procedures developed are documented in detail, The experimental method is used to study a thick walled toroidal shell under a uniform internal pressure. </p> <p> The principal stresses on the inside and outside surfaces of the shell were determined and from these the maximum shear stresses calculated. The experimental results are compared to Lame's solution of a thick walled ring under iniform internal pressure, a thin walled toroidal shell subjected to uniform internal pressure, and a long, straight thin walled cylinder with closed ends loaded by internal pressure. </p> / Thesis / Master of Engineering (ME)

The focus of this research is the isolation of waterborne pathogens which are one of the grand challenges to human health, costing the lives of about 2.5 million people worldwide each year. The aim was to develop new microfluidic techniques for selectively concentrating and detecting waterborne pathogens. Detection of microbes in water can greatly help reduce deaths; however, analytical instruments cannot readily detect them due to the extreme dilution of these microbes, and hence, require significant sample concentration. Current methods are expensive and either require days to process or are not sufficiently robust for water monitoring. Microfluidic chips based on insulator-based dielectrophoresis (iDEP) provide a promising solution to these problems and have been previously used to selectively concentrate biological particle such as bacteria. The microfluidic devices in this work were created with a 3D mircofabrication technique, which we also developed as part of this project. The core process of the technique is the etching of 3D structures in silicon with a single plasma etch utilizing an effect known as reactive ion etch lag (RIE lag). Using this unique process, 3D devices are fabricated in both silicon and the polymer polydimenthylsiloxane (PDMS). Using both numerical modeling and experimental results, we show how these 3D structures enhance the performance of the dielectrophoretic devices. The main findings indicate that 3D structures can help reduce Joule heating in the devices and lower the applied voltage necessary to operate the devices. Additionally, within this work, we develop a new dielectrophoresis technique called off-chip passivated-electrode, insulator-based dielectrophoresis microchip (O"DEP). This technique combines the sensitivity of electrode-based dielectrophoresis (eDEP) with the high-throughput and inexpensive device characteristics of insulator-based dielectrophoresis. The result is a cartridge based system which is accessible, economical, high-performance, and high-throughput technologies allowing timely detection of pathogenic bacteria. / Ph. D.

Oesophageal cancer is an aggressive malignancy with an overall five-year survival of 5-10% and two-thirds of patients have irresectable disease at diagnosis. Accurate staging of oesophageal cancer is important as survival closely correlates with the stage of the tumour, nodal involvement and presence of metastases (TNM staging). Endoscopic ultrasonography (EUS) is currently the most reliable modality for providing accurate T and N staging. Depending on findings of the staging, various treatment options including endoscopic, oncological, and surgical treatments may be performed. It was theorised that the development of three-dimensional radial endoscopic ultrasonography would reduce the operator dependence of EUS and provide accurate dimensional and volume measurements to aid planning and monitoring of treatment. This thesis investigates the development of a three dimensional endoscopic ultrasound technique that can be used with the radial echoendoscopes. Various agar-based tissue mimicking material (TMM) recipes were characterised using a scanning acoustic macroscope to obtain the acoustic properties of attenuation, backscatter and speed of sound. Using these results, a number of endoscopic ultrasound phantoms were developed for the in-vitro investigation and evaluation of 3D-EUS techniques. To increase my understanding of EUS equipment, the imaging and acoustic properties of the EUS endoscopes were characterised using a pipe phantom and a hydrophone. The dual ‘single element’ mechanical and ‘multi-element’ electronic echoendoscopes were investigated. Measured imaging properties included dead space, low contrast penetration, and pipe length. The measured acoustic properties included transmitted beam plots, active working frequency and peak pressures. Three-dimensional ultrasound techniques were developed for specific application to EUS. This included the study of positional monitoring systems, reconstruction algorithms and measurement techniques. A 3D-EUS system was developed using a Microscribe positional arm and frame grabber card, to acquire the 3D dataset. A Matlab 3D-EUS toolbox was written to reconstruct and analyse the volumes. The 3D-EUS systems were evaluated on the EUS phantom and in clinical cases. The usefulness of the 3D-EUS systems was evaluated in a cohort of patients, who were routinely investigated by conventional EUS for a variety of upper gastrointestinal pathology. 3D-EUS accurately staged early tumours and provided the necessary anatomical information to facilitate treatment. With regards to more advanced tumours, 3D-EUS was more accurate than EUS in T and N staging. 3D-EUS gave useful anatomical details in a variety of benign conditions such as varicies and GISTs.

Three dimensional (3D) woven composites have attracted the interest of academia and industry thanks to their damage tolerance characteristics and automated fabric manufacturing. Although much research has been conducted to investigate their out-of-plane "through thickness" properties, still their in-plane properties are not fully understood and rely on extensive experimentation. The aim of this work is to study the electromechanical behaviour of three different fibre architectures of 3D woven composites "orthogonal (ORT), layer-to-layer (LTL) and angle interlock (AI)" loaded, in three different orientations "warp (0º), weft (90º) and off-axis (45º)", in quasi-static tension. Stress/strain response is captured as well as damage initiation and evolution up to final failure. The ORT architecture demonstrated a superior behaviour, in the off-axis direction, demonstrated by high strain to failure (~23%) and high translaminar energy absorption (~40 MJ/m3). The z-binder yarns in ORT suppress delamination and allow larger fibre rotation during the fibre "scissoring motion" that enables further strain to be sustained. In-situ electrical resistance variation is monitored using a four-probe technique to correlate the resistance variation with the level of damage induced while loading. Monotonic and cyclic "load/unload" tests are performed to investigate the effect of piezo-resistivity and residual plasticity on resistance variation while damage is captured by X-ray scanning during interrupted tests at predefined load levels. In addition, this study investigates the potential of using 3D woven composites in joint assemblies through open-hole tension and "single fastener double-lap joint" bearing strength tests. 3D woven composites in the off-axis orientation, especially ORT, demonstrate a potential for overcoming some of the major challenges for composite joints' applications which are the pseudo-ductility, stress redistribution away from the notch and notch insensitivity. Finally, the study proposes a micro-mechanics based damage model to simulate the response of 3D orthogonal woven composites loaded in tension. The proposed model differs from classical damage mechanics approaches in which the evolution law is obtained by retrofitting global experimental observations.

The purpose of this experimental study was to investigate the effect of stereoscopic three-dimensional (S3D) images on productive and receptive recall of foreign language vocabulary. S3D images are highly-realistic and differ from non-stereoscopic three-dimensional (NS3D) images in that they provide the impression of the added third dimension of depth. This within-subject study exposed the participants (N = 82) in a controlled setting to a series of carefully designed and randomly distributed NS3D and S3D images. The subjects were then given immediate productive and receptive tests of foreign language vocabulary items that were represented by NS3D and S3D images. Quantitative data consisted of the scores from the vocabulary tests. Qualitative data, gathered through background questionnaires and follow-up surveys, included a mixture of open-ended and Likert questions. The statistical analyses of the data using a series of paired t-tests showed NS3D and S3D images to be equally effective for vocabulary recall. In addition, significantly more subjects found S3D images to be engaging and/or more useful, while subjects also indicated that they perceived the main benefits of learning with S3D images to come from enhanced focus, realism, engagement, and association. At the same time, some learners reported being distracted and experiencing discomfort while viewing S3D images. Post hoc tests revealed that lower performance on S3D images was driven only by those subgroups that exhibited discomfort and / or lack of experience with S3D technology.

No description available.

Electrical trees are micrometre-size tubular channels of degradation in high voltage polymeric insulation, a precursor to failure of electrical power plant. Hence, electrical trees critically affect the reliability of power systems and the performance of new insulation designs. Imaging laboratory-grown electrical trees has been an important tool for studying how trees develop. Commonly, electrical trees prepared in transparent or translucent polymers are imaged using traditional optical methods. Consequently, most of the analysis has been based on two-dimensional (2D) images of trees, thus, valuable information may be lost. However, electrical trees are complex interconnected structures that require a tree-dimensional (3D) approach for more complete analysis. This thesis investigates a method for imaging and analysis of electrical trees to characterise their 3D structure and provide a platform for further modelling. Laboratory created electrical trees were imaged using X-ray Computed Tomography (XCT) and Serial Block-Face Scanning Electron Microscopy (SBFSEM), 3D imaging techniques that provide sub-micrometre spatial resolution. Virtual replicas of the trees, which are the 3D geometrical models representing the real electrical trees, were generated and new indices to characterise the 3D structure of electrical trees were developed. These parameters were indicative of differences in tree growth and thus, they can be used to investigate patterns and classify the structure of electrical trees. The progression of the tree was analysed using cross-sections of the tree that are orthogonal to the growth: the number of tree channels and area covered by them were measured. The fractal dimension of the tree was calculated from the 3D model and from the 2D projections, the latter being lower for all the tree-type structures studied. Parameters from the skeleton of the tree such as number of nodes, segment length, tortuosity and branch angle were measured. Most of the mean segment lengths ranged 6-13 µm, which is in accordance to the 10µm proposed by various tree-growth models. The capabilities of XCT and SBFSEM imaging techniques were evaluated in their application to electrical trees. Bush and branch trees, including early-growth electrical trees (of length 20-40 µm), were analysed and compared using the comprehensive tool of visualisation and characterisation developed. A two-stage tree-growth experiment was conducted to analyse the progression and development of tree branches using XCT: tree channels after the second stage of growth were wider than after the first, while the fractal dimension remained the same. The capabilities of XCT and SBFSEM were tested for imaging electrical trees in optically-opaque materials such as micro and nano-filled epoxy compounds. The general structure of trees in epoxy filled up to 20 wt% micro-silica was observed using both techniques. The use of a virtual replica as the 3D geometrical model for the simulation of the electric field distribution using Finite Element Analysis (FEA) was preliminary explored. A combination of the imaging techniques is proposed for a more complete structural analysis of trees. It is believed that a great impact towards understanding electrical treeing will be achieved using the 3D technical platform developed in this thesis.

The pro-oxidative and pro-inflammatory mechanisms have been implicated in various human diseases including neurological and psychiatric disorders. However, there is only limited information available on the etiology in the progression of neurological damage to brain. The emergence of tissue engineering with the growing interest in mechanistic studies of brain injury now raises great opportunities to study complex physiological and pathophysiological process in vitro. Therefore, the prime goals of this study include: (1) Determination of the molecular and cellular mechanisms responsible for blast- and radiation-induced brain injuries and (2) Development of a three-dimensional (3D) model system in order to mimic in vivo-like microenvironments to further broaden our knowledge in pro-oxidative and pro-inflammatory mechanisms and their cellular responses within 3D constructs. In the first study, we demonstrated that blast exposure induced specific molecular and cellular alterations in pro-oxidative and pro-inflammatory environments in the brain and neuronal loss with adverse behavioral outcome. The results provide evidence that pro-oxidative and pro-inflammatory environments in the brain could play a potential role in blast-induced neuronal loss and behavioral deficits. In the second study, we investigated that fractionated whole-brain irradiation induced specific molecular and cellular alterations in pro-oxidative and pro-inflammatory environments in the brain along with elevation of reactive oxygen species (ROS)-generating protein (NOX-2) and microglial activation. Additionally, the contribution of NOX-2 in fractionated whole-brain radiation-induced oxidative stress was observed by dramatic amelioration of ROS generation after pharmacological inhibition of NOX-2. These results support that NOX-2 may play a pivotal role in fractionated whole-brain radiation-induced pro-oxidative and pro-inflammatory pathways in mouse brain. In the third study, we developed an in vitro 3D experimental model of brain inflammation by encapsulating microglia in collagen hydrogel with computational analysis of 3D constructs. The results indicated that our newly developed in vitro 3D model system provides a more physiologically relevant environment to mimic in vivo responses. In conclusion, these data may be beneficial in defining a cellular and molecular basis of pathophysiological mechanisms of brain injuries. Furthermore, it may provide new opportunities for preventive and therapeutic interventions for patients with brain injuries and associated neurological disorders. / Ph. D.

Visualisation, the representation of data in visual form, is at the core of our ability to communicate information. Without clear representation, data would remain in its raw form thus greatly hindering the communication process. This is especially the case when the data source is large, complex and subject to change. One such area is related to the use of computer based simulation tools for thermal analysis. This research investigates the potential of visualisation to improve the ways in which thermal analysis data are presented to building services engineers, with a view to increasing the accuracy and efficiency of its interpretation. The approach taken throughout followed a pattern of research, development, demonstration and evaluation. The research phase included a detailed review of existing visualisation theory and an extensive user requirement survey. The development phase produced three working visualisation software prototypes, each of which was demonstrated or evaluated within the sponsoring company. Whilst the initial emphasis of the research was advanced Three-Dimensional (3D) visualisation, extensive user requirement analysis indicated that comparing multiple datasets in an intuitive manner was more important. In response, the research focused on combining techniques in ways which supported the rapid comparison of multiple files and the data contained within. The final prototype combines techniques for data storage and manipulation with information visualisation techniques and advanced 3D graphics. These elements are tightly integrated within a single application that facilitates the management and interpretation of data from multiple analysis models. Evaluation of the prototype showed high levels of user satisfaction and improvements in the accuracy and efficiency of data interpretation. The techniques demonstrated by the prototype were also understood and liked by the users of thermal analysis tools. Several of the techniques, such as the new Force Directed Difference Diagrams, have potential applications outside of building services engineering. The research has demonstrated it is possible to improve the representation and interpretation of building performance data using visualisation techniques.

La sobriété énergétique du bâti devient aujourd’hui un élément clé en phase de conception. L’intégration en amont d’outils numériques, notamment la réalité virtuelle (RV). Nous a conduit, dans cette recherche, à nous concentrer sur les résultats de simulations thermiques visualisées dans un environnement virtuel. La contribution est portée sur la représentation et la perception dans un EV de ces données issues de simulation. Nous nous limitons à la caractérisation de l’efficacité énergétique en processus de conception. Cette étude vise la prédiction des performances thermiques dans des systèmes de réalité virtuelle. Les problématiques de formats de données et de flux de travail entre la modélisation classique CAO (Conception Assistée par Ordinateur), les simulations thermiques, et la visualisation immersive sont également traitées. Il existe plusieurs outils logiciels dédiés à la représentation de simulations thermiques en EV et le premier enjeu de ces travaux fut de sélectionner l’outil approprié. De nombreux modeleurs CAO, logiciels de simulation thermique et outils de RV sont disponibles ; ils diffèrent notamment par leurs approches (fonctionnalités et environnement logiciel). La problématique d’interopérabilité (formats d’échange entre les outils logiciels) requiert de bâtir un flux de travail structuré. Les difficultés d’intégration entre outils CAO et outils de simulation, et les barrières au transfert vers des systèmes de réalité virtuelle sont également décrits. Il est apparu pertinent d'utiliser le Building Information Model (BIM) de plus en plus utilisé parmi les acteurs de l’architecture, ingénierie et construction (AIC). Puis nous avons poursuivi par l’évaluation des tendances actuelles en matière de représentation de données thermiques issues de simulation dans un EV, par la création de méthode de transfert de données de sorte à les intégrer au flux de travail. Après un état de l’art sur la simulation thermique et une évaluation des travaux connexes, nous décrivons l'application, la méthode et les outils pour parvenir à nos objectifs. Une proposition de procédé de transfert de données et de présentation de données en EV est formulée et évaluée. Le flux d’échanges de données s’effectue en trois phases, de sorte à optimiser les passages entre la CAO, le calcul thermique et la réalité virtuelle. La représentation des données dans l’EV est réalisée grâce à une visualisation immersive et interactive. Une expérimentation a été conduite de sorte à évaluer des sujets : Le scénario consistait en une visualisation interactive de données thermiques selon 4 modalités en environnement virtuel. L’interface développée pour l’interaction a été voulue intuitive et conviviale. L’application contient un modèle 3D réaliste du projet (salle Gunzo) dans deux configurations : état actuel et état rénové. Les données thermiques sont restituées selon plusieurs métaphores de représentation. L’expérimentation développe une approche qui associe au scénario de rénovation virtuelle une configuration matérielle/logicielle. Les résultats obtenus se concentrent sur la visualisation, l'interaction et le retour subjectif des utilisateurs. Quatre métaphores de visualisation sont testées et leur évaluation porte notamment sur deux critères : leurs capacités à restituer les résultats de simulation thermique ; le degré d’interaction et la perception de l’utilisateur des impacts de ses actions. L’évaluation subjective révèle les préférences des utilisateurs et montre que les métaphores de représentation ont une influence sur la précision et l’efficience de l’interprétation des données. Ces travaux montrent que les techniques de représentation et de visualisation de données de simulation ont un effet sur la pertinence de leur interprétation. La méthode décrite spécifie les modalités de transfert de la donnée depuis la phase conception jusqu’aux outils et systèmes de RV. Sa souplesse lui permet d’être transposée à tout type de projet (…) / The importance of energy efficiency as well as integration of advances in sustainable buildingdesign and VR technology have lead this research to focus on thermal simulation results visualized in avirtual environment (VE). The emphasis is on the representation of thermal building simulation (TBS)results and on the perception of thermal data simulated in a VE. The current application of the designprocess through energy efficiency in VR systems is limited mostly to building performance predictionsand design review, as the issue of the data formats and the workflow used for 3D modeling, thermalcalculation and VR visualization.Different applications and tools involved to represent TBS in VE are become the challenge ofthis work. Many 3D modeller, thermal simulation tools and VR tools are available and they are differ intheir function and platform. Issues of data format exchange, appropriate tools and equipments from thissituation require an interoperability solution that needs to be structured in a workflow method.Significances and barriers to integration design with CAD and TBS tools are also outlined in order totransfer the model to VR system. Therefore, the idea then is to use Building Information Model (BIM)extensively used in Architecture, Engineering and Construction (AEC) community. It then continued toevaluate the current trends for TBS representation in VE, to create data transfer method, and tointegrate them in the workflow. After a review in thermal simulation and an evaluation of related works,we specify the application, method and tools for our objectives.An application of a method of data transfer and presentation of data in VE are formulated andtested. This effort conduct using a specific data workflow which performed the data transfer through 3phases. This relies on the smooth exchange of data workflow between CAD tools, thermal calculationtools and VR tools. Presentation of data in VE is conducted through immersive visualization andintuitive interaction. An experiment scenario of a thermal simulation in VR system was created tointeractively visualize the results in the immersion room and tested by some respondents. The systeminclude with friendly interface for interaction. It presents a realistic 3D model of the project (Gunzoroom) in existing condition and renovated version, and their TBS results visualized in somevisualization metaphor. In the experiment, the method which bundled in an application brings togetherwithin a couple of virtual scenario and a software/hardware solution. The obtained results concentrateon visualization, interaction and its feedback. Some visualization metaphor are tested and evaluated topresent more informative TBS results where the user can interact and perceive the impact of theiraction.Evaluation of the application prototype showed various levels of user satisfaction, andimprovements in the accuracy and efficiency of data interpretation. The research has demonstrated it ispossible to improve the representation and interpretation of building performance data, particularly TBSresults using visualization techniques. Using specific method, the data flow that starts from the designprocess is completely and accurately channelled to the VR system. The method can be used with anykind of construction project and, being a flexible application, accepts new data when necessary,allowing for a comparison between the planned and the constructed.