The Effect of Foam Core Density on the Flexural and Axial Behaviour of Sandwich Panels of Varying Slenderness with Natural Flax-FRP and Glass-FRP Composite Skins

This study investigates the effect of foam core density and skin type on the behaviour of sandwich panels as structural beams tested in four-point bending and axially compressed columns of varying slenderness and skin thickness. Bio-composite unidirectional flax fibre-reinforced polymer (FFRP) is compared to conventional glass-FRP (GFRP) as the skin material used in conjunction with three polyisocyanurate (PIR) foam cores with densities of 32, 64 and 96 kg/m3. Eighteen 1000 mm long flexural specimens were fabricated and tested to failure comparing the effects of foam core density between three-layer FFRP skinned and single-layer GFRP skinned panels. A total of 132 columns with slenderness ratios (kLe/r) ranging from 22 to 62 were fabricated with single-layer GFRP skins, and one-, three-, and five-layer FFRP skins for each of the three foam core densities. The columns were tested to failure in concentric axial compression using pinned-end conditions to compare the effects of each material type and panel height. All specimens had a foam core cross-section of 100x50 mm with 100 mm wide skins of equal thickness. In both flexural and axial loading, panels with skins comprised of three FFRP layers showed equivalent strength to those with a single GFRP layer for all slenderness ratios and core densities examined. Doubling the core density from 32 to 64 kg/m3 and tripling the density to 96 kg/m3 led to flexural strength increases of 82 and 213%, respectively. Both FFRP and GFRP columns showed a similar variety of failure modes related to slenderness. Low slenderness of 22-25 failed largely due to localized single skin buckling, while those with high slenderness of 51-61 failed primarily by global buckling followed by secondary skin buckling. Columns with intermediate slenderness experienced both localized and global failure modes. High density foam cores more commonly exhibited core shear failure. Doubling the core density of the columns resulted in peak axial load increases, across all slenderness ratios, of 73, 56, 72 and 71% for skins with one, three and five FFRP layers, and one GFRP layer, respectively. Tripling the core density resulted in respective peak load increases of 116, 130, 176 and 170%.

Comprehensive Characterization of Measurement Data Gathered by the Pressure Tube to Calandria Tube Gap Probe

Multi-frequency eddy current measurements are employed in estimating pressure tube (PT) to calandria tube (CT) gap in CANDU fuel channels, a critical inspection activity required to ensure fitness for service of fuel channels. In this thesis, a comprehensive characterization of eddy current gap data is laid out, in order to extract further information on fuel channel condition, and to identify generalized applications for multi-frequency eddy current data. A surface profiling technique, generalizable to multiple probe and conductive material configurations has been developed. This technique has allowed for identification of various pressure tube artefacts, has been independently validated (using ultrasonic measurements), and has been deployed and commissioned at Ontario Power Generation. Dodd and Deeds solutions to the electromagnetic boundary value problem associated with the PT to CT gap probe configuration were experimentally validated for amplitude response to changes in gap. Using the validated Dodd and Deeds solutions, principal components analysis (PCA) has been employed to identify independence and redundancies in multi-frequency eddy current data. This has allowed for an enhanced visualization of factors affecting gap measurement. Results of the PCA of simulation data are consistent with the skin depth equation, and are validated against PCA of physical experiments. Finally, compressed data acquisition has been realized, allowing faster data acquisition for multi-frequency eddy current systems with hardware limitations, and is generalizable to other applications where real time acquisition of large data sets is prohibitive.

Financial media, globalisation, and China’s economic integration: comparing narrative construction of the Economist and Caijing

In June 2015, legal frameworks of the Asian Infrastructural Investment Bank were signed by its 57 founding members. Proposed and initiated by China, this multilateral development bank is considered to be an Asian counterpart to break the monopoly of the World Bank and the International Monetary Fund. In October 2015, China’s Central Bank announced a benchmark interest rate cut to combat the economic slowdown. The easing policy coincides with the European Central Bank’s announcement of doubts over US Fed’s commitment to raise interest rates. Global stock markets responded positively to China’s move, with the exception of the indexes from Wall Street (Bland, 2015; Elliott, 2015). In the meantime, China’s ‘One Belt, One Road’ (or New Silk Road Economic Belt) became atopic of discourse in relation to its growing global economy, as China pledged $40 billion to trade and infrastructure projects (Bermingham, 2015). The foreign policy aims to reinforce the economic belt from western China through Central Asia towards Europe, as well as to construct maritime trading routes from coastal China through the South China Sea (Summers, 2015). In 2012, The Economist launched a new China section, to reveal the complexity of the‘meteoric rise’ of China. John Micklethwait, who was then the chief editor of the magazine, said that China’s emergence as a global power justified giving it a section of its own(Roush, 2012). In July 2015, Hu Shuli, the former chief editor of Caijing, announced the launch of a think tank and financial data service division called Caixin Insight Group, which encompasses the new Caixin China Purchasing Managers Index (PMI). Incooperation with with Markit Group, a principal global provider of PMI, the index soon became a widely cited economic indicator. One anecdote from November’s Caixin shows how much has changed: in a high-profile dialogue between Hu Shuli and Kevin Rudd, Hu insisted on asking questions in English; interestingly, the former Prime Minister of Australia insisted on replying in Chinese. These recent developments point to one thing: the economic ascent of China and its increasing influence on the power play between economics and politics in world markets. China has begun to take a more active role in rule making and enforcement under neoliberal frameworks. However, due to the country’s size and the scale of its economy in comparison to other countries, China’s version of globalisation has unique characteristics. The ‘Capitalist-socialist’ paradox is vital to China’s market-oriented transformation. In order to comprehend how such unique features are articulated and understood, there are several questions worth investigating in the realms of media and communication studies,such as how China’s neoliberal restructuring is portrayed and perceived by different types of interested parties, and how these portrayals are de-contextualised and re-contextualised in global or Anglo-American narratives. Therefore, based on a combination of the themes of globalisation, financial media and China’s economic integration, this thesis attempts to explore how financial media construct the narratives of China’s economic globalisation through the deployment of comparative and multi-disciplinary approaches. Two outstanding elite financial magazines, Britain’s The Economist, which has a global readership and influence, and Caijing, China’s leading financial magazine, are chosen as case studies to exemplify differing media discourses, representing, respectively, Anglo-American and Chinese socio-economic and political backgrounds, as well as their own journalistic cultures. This thesis tries to answer the questions of how and why China’s neoliberal restructuring is constructed from a globally-oriented perspective. The construction primarily involves people who are influential in business and policymaking. Hence, the analysis falls into the paradigm of elite-elite communication, which is an important but relatively less developed perspective in studying China and its globalisation. The comparing of characteristics of narrative construction are the result of the textual analysis of articles published over a ten-year period (mid-1998 to mid-2008). The corpus of samples come from the two media outlets’ coverage of three selected events:China becoming a member of the World Trade Organization, its outward direct investment, and the listing of stocks of Chinese companies in overseas exchanges, which are mutually exclusive in sample collection and collectively exhaustive in the inclusion of articles regarding China’s economic globalisation. The findings help to understand that, despite language, socio-economic and political differences, elite financial media with globally-oriented readerships share similar methods of and approaches to agenda setting, the evaluation of news prominence, the selection of frame, and the advocacy of deeply rooted neoliberal ideas. The comparison of their distinctive features reflects the different phases of building up the sense of identity in their readers as global elites, as well as the different economic interests that are aligned with the corresponding readerships. However, textual analysis is only relevant in terms of exploring how the narratives are constructed and the elements they include; textual analysis alone prevents us from seeing the obstacles and the constrains of the journalistic practices of construction. Therefore, this thesis provides a brief discussion of interviews with practitioners from the two media, in order to understand how similar or different narratives are manifested and perceived, how the concept of neoliberalism deviates from and is justified in the Chinese context, and how and for what purpose deviations arise from Western to Chinese contexts. The thesis also contributes to defining financial media in the domain of elite communication. The relevant and closely interlocking concepts of globalisation, elitism and neoliberalism are discussed, and are used as a theoretical bedrock in the analysis of texts and contexts. It is important to address the agenda-setting and ideological role of elite financial media, because of its narrative formula of infusing business facts with opinions,which is important in constructing the global elite identity as well as influencing neoliberal policy-making. On the other hand, ‘journalistic professionalism’ has been redefined, in that the elite identity is shared by the content producer, reader and the actors in the news stories emerging from the much-compressed news cycle. The professionalism of elite financial media requires a dual definition, that of being professional in the understanding of business facts and statistics, and that of being professional in the making sense of stories by deploying economic logic.

Análisis de la información y documentación científica española sobre el fenómeno de las smart cities, el hábitat de los nativos digitales

Estudiosos de todo el mundo se están centrando en el estudio del fenómeno de las ciudades inteligentes. La producción bibliográfica española sobre este tema ha crecido exponencialmente en los últimos años. Las nuevas ciudades inteligentes se fundamentan en nuevas visiones de desarrollo urbano que integran múltiples soluciones tecnológicas ligadas al mundo de la información y de la comunicación, todas ellas actuales y al servicio de las necesidades de la ciudad. La literatura en español sobre este tema proviene de campos tan diferentes como la Arquitectura, la Ingeniería, las Ciencias Políticas y el Derecho o las Ciencias Empresariales. La finalidad de las ciudades inteligentes es la mejora de la vida de sus ciudadanos a través de la implementación de tecnologías de la información y de la comunicación que resuelvan las necesidades de sus habitantes, por lo que los investigadores del campo de las Ciencias de la Comunicación y de la Información tienen mucho que decir. Este trabajo analiza un total de 120 textos y concluye que el fenómeno de las ciudades inteligentes será uno de los ejes centrales de la investigación multidisciplinar en los próximos años en nuestro país.

Infrared image enhancement based on hybrid-domain consideration and data fusion methods

Au cours des dernières décennies, l’effort sur les applications de capteurs infrarouges a largement progressé dans le monde. Mais, une certaine difficulté demeure, en ce qui concerne le fait que les objets ne sont pas assez clairs ou ne peuvent pas toujours être distingués facilement dans l’image obtenue pour la scène observée. L’amélioration de l’image infrarouge a joué un rôle important dans le développement de technologies de la vision infrarouge de l’ordinateur, le traitement de l’image et les essais non destructifs, etc. Cette thèse traite de la question des techniques d’amélioration de l’image infrarouge en deux aspects, y compris le traitement d’une seule image infrarouge dans le domaine hybride espacefréquence, et la fusion d’images infrarouges et visibles employant la technique du nonsubsampled Contourlet transformer (NSCT). La fusion d’images peut être considérée comme étant la poursuite de l’exploration du modèle d’amélioration de l’image unique infrarouge, alors qu’il combine les images infrarouges et visibles en une seule image pour représenter et améliorer toutes les informations utiles et les caractéristiques des images sources, car une seule image ne pouvait contenir tous les renseignements pertinents ou disponibles en raison de restrictions découlant de tout capteur unique de l’imagerie. Nous examinons et faisons une enquête concernant le développement de techniques d’amélioration d’images infrarouges, et ensuite nous nous consacrons à l’amélioration de l’image unique infrarouge, et nous proposons un schéma d’amélioration de domaine hybride avec une méthode d’évaluation floue de seuil amélioré, qui permet d’obtenir une qualité d’image supérieure et améliore la perception visuelle humaine. Les techniques de fusion d’images infrarouges et visibles sont établies à l’aide de la mise en oeuvre d’une mise en registre précise des images sources acquises par différents capteurs. L’algorithme SURF-RANSAC est appliqué pour la mise en registre tout au long des travaux de recherche, ce qui conduit à des images mises en registre de façon très précise et des bénéfices accrus pour le traitement de fusion. Pour les questions de fusion d’images infrarouges et visibles, une série d’approches avancées et efficaces sont proposés. Une méthode standard de fusion à base de NSCT multi-canal est présente comme référence pour les approches de fusion proposées suivantes. Une approche conjointe de fusion, impliquant l’Adaptive-Gaussian NSCT et la transformée en ondelettes (Wavelet Transform, WT) est propose, ce qui conduit à des résultats de fusion qui sont meilleurs que ceux obtenus avec les méthodes non-adaptatives générales. Une approche de fusion basée sur le NSCT employant la détection comprime (CS, compressed sensing) et de la variation totale (TV) à des coefficients d’échantillons clairsemés et effectuant la reconstruction de coefficients fusionnés de façon précise est proposée, qui obtient de bien meilleurs résultats de fusion par le biais d’une pré-amélioration de l’image infrarouge et en diminuant les informations redondantes des coefficients de fusion. Une procédure de fusion basée sur le NSCT utilisant une technique de détection rapide de rétrécissement itératif comprimé (fast iterative-shrinking compressed sensing, FISCS) est proposée pour compresser les coefficients décomposés et reconstruire les coefficients fusionnés dans le processus de fusion, qui conduit à de meilleurs résultats plus rapidement et d’une manière efficace.

Convex Optimization Algorithms and Statistical Bounds for Learning Structured Models

Thesis (Ph.D.)--University of Washington, 2016-08

Those Who Belong and Those Who Don’t: Physical and Mental Borders in Europe

Europe promotes migration and mobility but new or ‘different’ Europeans are still stigmatised and marginalised in our societies. Today, neither refugee status nor citizenship can tear down the mental borders between people who inhabit the same cities or neighbourhoods. Sociology professor Nira Yuval-Davis writes about the meaning of borders, and how they make us differentiate between ‘us’ and ‘the other’ in our daily lives.

Discrete-event Simulation and Optimization to Improve the Performance of a Healthcare System

Thesis (Ph.D.)--University of Washington, 2016-08

Dithen: A Computation-as-a-Service Cloud Platform For Large-Scale Multimedia Processing

We present Dithen, a novel computation-as-a-service (CaaS) cloud platform specifically tailored to the parallel ex-ecution of large-scale multimedia tasks. Dithen handles the upload/download of both multimedia data and executable items, the assignment of compute units to multimedia workloads, and the reactive control of the available compute units to minimize the cloud infrastructure cost under deadline-abiding execution. Dithen combines three key properties: (i) the reactive assignment of individual multimedia tasks to available computing units according to availability and predetermined time-to-completion constraints; (ii) optimal resource estimation based on Kalman-filter estimates; (iii) the use of additive increase multiplicative decrease (AIMD) algorithms (famous for being the resource management in the transport control protocol) for the control of the number of units servicing workloads. The deployment of Dithen over Amazon EC2 spot instances is shown to be capable of processing more than 80,000 video transcoding, face detection and image processing tasks (equivalent to the processing of more than 116 GB of compressed data) for less than $1 in billing cost from EC2. Moreover, the proposed AIMD-based control mechanism, in conjunction with the Kalman estimates, is shown to provide for more than 27% reduction in EC2 spot instance cost against methods based on reactive resource estimation. Finally, Dithen is shown to offer a 38% to 500% reduction of the billing cost against the current state-of-the-art in CaaS platforms on Amazon EC2 (Amazon Lambda and Amazon Autoscale). A baseline version of Dithen is currently available at dithen.com.

Likelihood-Based Inference for Partially Observed Multi-Type Markov Branching Processes

Thesis (Ph.D.)--University of Washington, 2016-08

Improving Wood Fuel Pellets for Household Use : Perspectives on Quality, Efficiency and Environment

Bioenergy is one of many contributors to reducing the use of fossil fuels in order to mitigate climate change by decreasing CO2-emissions, and the potential for biofuels are large. The wood fuel pellets are a refined biofuel made of sawdust, which is dried and compressed to achieve improved fuel and transportation properties. In 2007 the amount of wood fuel pellets used for heating purposes in Sweden was 1715000 tons. The aims of this work was: to examine the moisture content and emission of monoterpenes during the drying and pelletising steps of the pellets production (Paper I); to investigate how the recirculation of drying gases affects the energy efficiency of rotary dryers and how the energy efficiency is related to the capacity of the dryer. (Paper II); to analyse the causes of the problems encountered by household end-users of pellets and investigate whether an improved pellet quality standard could reduce these problems (Paper III); to investigate how the energy consumption of the pelletising machine and chosen pellet quality parameters were affected using an increased amount of rapeseed cake in wood fuel pellets (Paper IV); and to identify gaps of knowledge about wood fuel pellet technology and needs for further research on quality, environmental and health aspects throughout the wood fuel pellet chain, from sawdust to heat. (Paper V).

Gewebeansatz-Strukturen auf pyritisierten Steinkernen von Ammonoideen

3400 pyritized internal moulds of Upper Devonian, Triassic, Jurassic and Lower Cretaceous ammonoids show various soft tissue attachment structures. They are preserved as regularly distributed black patterns on the moulds. All structures can be interpreted as attachment areas of muscles, ligaments and intracameral membranes. Paired structures are developed along the umbilicus and on the flanks of the moulds, unpaired ones appear on the middle of their dorsal and ventral sides. Strong lateral muscles cause paired twin lines on the flanks of the phragmocone and of the body chamber. A ventral muscle is deduced from small rounded or crescent shaped spots in front of each septum on the ventral side. These spots are often connected, forming a band-like structure. Broad dark external bands on the ventral side of the phragmocone, ventral preseptal areas in the posterior part of the living chamber, small twin lines or oval shaped areas on the ventral side of the living chamber represent paired or unpaired attachment areas of the hyponome muscle. A middorsal muscle is documented by small roughened areas in front of each dorsal lobe. Dark spots along the umbilicus, often connected and thus forming a band-like structure (tracking band), are remains of a pair of small dorsolateral muscles at the posterior end of the soft body. Dark bands, lines and rows of small crescent shaped structures behind the tips of sutural lobes are due to spotlike fixation places of the posterior part of the mantle and their translocation before subsequent septal secretion. Devonian goniatites had a paired system of lateral and ventrolateral muscles preserved on the moulds as black or incised lines on the flanks of the living chamber and as dark preseptal areas, ventrally indented. These structures represent the attachment areas of paired lateral cephalic and paired ventral hyponome retractors. Fine black lines on the phragmocone situated parallel to the sutures (pseudosutures) represent a rhythmical secretion of camera! membranes during softbody translocation. Goniatites had a paired system of lateral and ventrolateral muscles, whilst Neoammonoids have a paired lateral and dorsolateral system, and, additionally, an unpaired system on the ventral and on the dorsal side. Mesoammonoids show only a paired lateral and an unpaired dorsal one. Fine black lines situated parallel to the saddles and behind the lobes of the suture line can be interpreted as structures left during softbody translocation and a temporary attachment of rhythmical secreted cameral membranes. Cameral membranes had supported the efficiency of the phragmocone. Only some of the observed structures are also present in recent Nautilus. Differences in the form and position of attachment sites between ammonoids and recent Nautilus indicate different soft body organizations between ammonoids and nautiloids. The attachment structures of goniatites especially of tornoceratids can be compared with those of Nautilus which indicates Richter - Gewebeansatz-Strukturen bei Ammonoideen 3 a comparable mode of life. Differences in the form and position of attachment structures between goniatites and ammonites may indicate an increasing differentiation of the muscular system in the phylogeny of this group. Different soft body organization may depend on shell morphology and on a different mode of life. On the modification or reduction of distinct muscle systems ammonoids can be assigned to different ecotypes. Based on shell morphology and the attachment areas of cephalic and hyponome retractor muscles two groups can be subdivided: - Depressed, evolute morphotypes with longidome body-chambers show only small ventral hyponome retractor muscles. Lateral cephalic retractors are not developed. These morphotypes are adapted to a demersal mode of life. Without strong cephalic retractor muscles no efficient jet propulsion can be produced. These groups represent vertical migrants with efficient phragmocone properties (multilobate sutures, cameral membranes, narrow septal spacing). - Compressed, involute moiphotypes with brevidome body-chambers show strong cephalic and hyponome retractor muscles and represent a group of active swimmers. These morphotypes were able to live at different depths, in the free water column or/and near the seafloor. They are not confined only to one habitat. Most of the examined genera and species belong to this group. Changes of the attachment structures in the course of ontogeny confirm that juveniles of Amaltheus and Quenstedtoceras lived as passive planche drifters in upper and intermediate parts of the free water column after hatching. At the end of the juvenile stage with a shell diameter of 0,3 - 0,5 cm cephalic retractor muscles developed. With the beginning of an active swimming mode of life (neanic stage) the subadult animals left the free water column and moved into shallow water habitats. Fuciniceras showed no marked changes in the attachment structures during ontogeny. This indicates that there occur no differences in the mode of life between juvenile and adult growth stages. Based on attachment structures and shell morphology of Devonian goniatites their relation to the systematic position permits statements about probable phylogenetic relationships between the Cheiloceratidae and Tornoceratidae. In some cases attachment structures of ammonites permit statements about phylogenetic relationships on family and genus level.

Tensor Completion for Multidimensional Inverse Problems with Applications to Magnetic Resonance Relaxometry

This thesis deals with tensor completion for the solution of multidimensional inverse problems. We study the problem of reconstructing an approximately low rank tensor from a small number of noisy linear measurements. New recovery guarantees, numerical algorithms, non-uniform sampling strategies, and parameter selection algorithms are developed. We derive a fixed point continuation algorithm for tensor completion and prove its convergence. A restricted isometry property (RIP) based tensor recovery guarantee is proved. Probabilistic recovery guarantees are obtained for sub-Gaussian measurement operators and for measurements obtained by non-uniform sampling from a Parseval tight frame. We show how tensor completion can be used to solve multidimensional inverse problems arising in NMR relaxometry. Algorithms are developed for regularization parameter selection, including accelerated k-fold cross-validation and generalized cross-validation. These methods are validated on experimental and simulated data. We also derive condition number estimates for nonnegative least squares problems. Tensor recovery promises to significantly accelerate N-dimensional NMR relaxometry and related experiments, enabling previously impractical experiments. Our methods could also be applied to other inverse problems arising in machine learning, image processing, signal processing, computer vision, and other fields.

Hierarchical Reconstruction Method for Solving Ill-posed Linear Inverse Problems

We present a detailed analysis of the application of a multi-scale Hierarchical Reconstruction method for solving a family of ill-posed linear inverse problems. When the observations on the unknown quantity of interest and the observation operators are known, these inverse problems are concerned with the recovery of the unknown from its observations. Although the observation operators we consider are linear, they are inevitably ill-posed in various ways. We recall in this context the classical Tikhonov regularization method with a stabilizing function which targets the specific ill-posedness from the observation operators and preserves desired features of the unknown. Having studied the mechanism of the Tikhonov regularization, we propose a multi-scale generalization to the Tikhonov regularization method, so-called the Hierarchical Reconstruction (HR) method. First introduction of the HR method can be traced back to the Hierarchical Decomposition method in Image Processing. The HR method successively extracts information from the previous hierarchical residual to the current hierarchical term at a finer hierarchical scale. As the sum of all the hierarchical terms, the hierarchical sum from the HR method provides an reasonable approximate solution to the unknown, when the observation matrix satisfies certain conditions with specific stabilizing functions. When compared to the Tikhonov regularization method on solving the same inverse problems, the HR method is shown to be able to decrease the total number of iterations, reduce the approximation error, and offer self control of the approximation distance between the hierarchical sum and the unknown, thanks to using a ladder of finitely many hierarchical scales. We report numerical experiments supporting our claims on these advantages the HR method has over the Tikhonov regularization method.