Ce travail de thèse s’inscrit dans le cadre du projet INTERREG Luminoptex et vise à réaliser des diodes organiques de redressement pour des applications de récupération d’énergie électromagnétique pour de l’éclairage ambiant autonome sur support textile. Des diodes à base de pentacène et de polymère P3HT ont été fabriquées selon deux configurations: verticale et coplanaire en utilisant aussi bien des procédés simples et peu couteux que des procédés de lithographie électronique. Les performances de ces diodes ont été améliorées par l’utilisation de monocouches auto assemblées SAM de PFBT (2,3,4,5-6 pentafluorobenzénethiol) qui permettent de réduire les barrières d’injection des porteurs de charges denviron 0.5eV. Dans le cas des diodes polymères, une couche d’injection à base de P3HT dopé au Triflate de cuivre a été étudiée et utilisée pour l’amélioration de l’injection. Des rapports de rectification élevés ont été obtenus ( 107) avec des tensions de fonctionnement très faibles (de 20 à 80mV). Les travaux de simulation ont montré par ailleurs, que ces diodes peuvent atteindre des fréquences de fonctionnement de l’ordre du GHz.Ces composants ont été ensuite réalisés sur substrat flexible de papier pour un transfert sur les surfaces textiles. / This thesis work is a part of the INTERREG Luminoptex project and aims to produce organic rectifier diodes for electromagnetic energy harvesting applications for autonomous ambient lighting on textile support. Pentacene oligomer and P3HT polymer diodes have been fabricated in two configurations: vertical and coplanar structures using soft technology and low cost processes or electron beam lithography technique. The performance of these diodes has been improved by the use of PFBT (2,3,4,5-6 pentafluorobenzenethiol) SAM self-assembled monolayers that reduce the injection barriers of charge carriers by about 0.5eV. In the case of polymer diodes, an injection layer based on P3HT doped with copper triflate was studied and used to improve the current injection. High rectification ratios were obtained ( up to 107) with very low operating voltages (from 20 to 80mV). Simulation study has also shown that these diodes can reach operating frequencies in the GHz range. These devices were then made on a flexible paper substrate for transfer to textile surfaces.

Architecture is a representation of our society’s aspirations and of our social, economic and political paradigms. Since 1994, has the city of Pretoria been successfully represented? Does the city succeed architecturally in creating space that is democratic and that embraces our country’s diversity? The large influx of people within the city of Pretoria has created a terrain consisting of a series of contradictions and conflicts. These conflicts and contradictions within the city are a result of social, economic, spatial, physical and historical tensions that exist within society's social, economic and political paradigms. Physical and spatial reactions have occurred as a result of these tensions that exist within the city of Pretoria. This dissertation will explore these urban spaces that are in tension and investigate what opportunities and limitations such spaces offer the city of Pretoria. The objective is to consider what architectural intervention will arise from the resolution, synthesis or conflict of these tensions. Can these spaces that are in tension within the city foster a new post-apartheid way of city-making. / Dissertation (MArch(Prof))--University of Pretoria, 2010. / Architecture / unrestricted

The main purpose of this mini-dissertation is to understand the relationship between gender, land, culture and the tension between African culture and the constitution in the context of communities under traditional authorities in South Africa. South African has a number of communities residing in the former ‘homelands’ or Bantustan States created by the apartheid government and colonists. These communities have their own cultures and custom and their relationship is generally governed by indigenous law. However some of their cultures and customs have been adulterated by colonists who imposed Western imported laws which subjected indigenous law to a repugnancy clause, whereby sections of indigenous law that were considered to be in conflict with the Western principles of justice, equity and fairness were regarded as inferior and unenforceable. For communities under traditional authorities land is very important as it is used for building a home and for subsistence farming. However all land in these communities is held in trust by the Chief who allocates it to communities members in line with indigenous law. With the adulteration of African culture and the introduction of legislation to enforce patriarchy in South Africa by colonists, as an example, by the use of the Black Administration Act of 1927, the system currently used to allocate land in traditional communities is gender based and discriminates against women and this creates tension between the currently used custom of allocating land and the Bill of Rights. The mini-dissertation proposes that that tension between African culture and the Bill of Rights could possibly be mediated using the African philosophy of Ubuntu / Mini Dissertation (LLM)--University of Pretoria, 2019. / Public Law / LLM / Unrestricted

The project analyzes the relationship and role that music plays in building tension in horror movies. To investigate the topic, three types of film music were identified: traditional, ambient, and soundtrack. Subsequently, nine horror scenes were chosen that were believed to induce tension, with three being traditional scores, three being ambient scores, and three being soundtracks. Each traditional and ambient score and soundtrack clip was from a different horror subgenre that included supernatural, body, and slasher horror. The music of these nine clips was then analyzed using spectrograms to create tension arcs that were compared to the visuals in the scene. An experiment was then conducted that took these nine scenes and separated them into three variables that included sound+video, video only, and sound only. Participants were placed into one of three groups associated with these variables at random, and were asked to rate their feelings of tension in each clip via a tension slider. Their responses were then compared to a theoretical curve that was created from the analysis of the clips. The results showed that there was a small correlation between the theoretical response and the responses between sound & video. There was another small correlation between sound+video and sound. This showed that music created tension in a similar way to the complete scene, except for in the case of soundtracks, and that music is possibly a larger contributor to tension than the visuals of a scene.

Among the basal bony fishes, the American paddlefish (Polyodon spathula) has a unique respiratory strategy of ram-ventilation. However, despite the increasing problems caused by hypoxia in natural habitats occupied by this species, little information exists about their response to hypoxia. Four studies were conducted to examine the physiological and biochemical responses of juvenile paddlefish (150-181 g) to acute and chronic hypoxia. Acute hypoxia tolerance, aerobic metabolic rates and swimming capabilities of paddlefish in an intermittent respirometer or swim flume were evaluated under normoxic (partial pressures of oxygen [pO2] =140 mm Hg) and hypoxic (pO2 =62 mm Hg) conditions at 18 °C and 26 °C. Additionally, blood oxygen transport, blood acid-base balance and metabolic stress were evaluated in paddlefish independently exposed to 4 different pO2s: normoxia =148 mm Hg, mild hypoxia =89 mm Hg, moderate hypoxia =59 mm Hg and extreme hypoxia =36 mm Hg, at 21°C. Blood samples were collected from paddlefish after they had been exposed to treatment pO2’s for 0.25, 2, 6, 24 and 72 hours, and analyzed for hematocrit, pO2, total oxygen content, pCO2, pH, hemoglobin, Na+, K+, Ca2+, Cl-, glucose, lactate, etc. A third study used 1-D and 2-D J-resolved 1H NMR to analyze metabolite changes in muscle tissue of paddlefish exposed to normoxia (148 mm Hg), or acute (0.25 h) or chronic (72 h) moderate hypoxia (59 mm Hg). The last study examined the effect of moderate hypoxia (pO2: 59 mm Hg) and subsequent recovery in normoxia (pO2: 148 mm Hg) on plasma cortisol, blood oxygen transport, blood acid-base balance, metabolic, ion-osmoregulation and enzyme parameters in paddlefish. The results indicate that paddlefish have a critical pO2 of 74 mm Hg at 18 °C and 89 mm Hg at 26 °C and a lethal oxygen threshold of ~2 mg/ L. Sensitive to moderate hypoxia, death occured after 3-8 hours of extreme hypoxia. Paddlefish have reduced capacity for metabolic depression and, as a result, survival in hypoxia is limited due to a reduction in both aerobic and anaerobic (glycogen and glucose) energy stores as well as the accumulations of toxic H+ and lactate. Nonetheless recovery is possible.

A need exists for a more robust method of evaluating musculoskeletal injuries resulting from impact conditions, particularly blasts. Computational modeling is a promising method of achieving this goal. The accuracy of a model depends on high quality mechanical properties for each component. This study examined the mechanical properties of porcine muscle along with structure property relationships. Fresh muscle was tested in compression and tension at strain rates of 0.1 s-1, 0.01 s-1, and 0.001 s-1. Viscoelastic properties were observed including strain rate dependency, stress state dependency, anisotropy, relaxation, and hysteresis. Image analysis was conducted in compression on controls, 30% strain, and 50% strain, relating stress-strain data with structural changes. The effect of rigor was also seen in the tensile response of muscle. Thawed tissue was examined to investigate the effects of freezing. It was found that freezing did not significantly change the mechanical properties, but substantial microstructural changes did occur.

The earliest man-made irrigation systems in recorded history date back to the ancient Egypt and Mesopotamia era. After thousands of years of experience, exploration, and experimenting, mankind have learned how to construct canals and dams and use pipes and pumps to direct and control water flow, but till this day, there are still some behaviors of water and other simple fluids that surprise us. One such example is the lotus effect: a surface-tension effect which allows raindrops to roll freely on a lotus leaf as if they were drops of mercury. One of the key factors that determine how a fluid system behave is the size-scale. Fluids flow at small scales very differently than they do at large scales. The standard comparing to which small and large are defined is the capillary length. A number of surface-tension related phenomena are unfamiliar because they are only noticeable at length-scales of a few millimeters or below, and they look nothing like what we would expect fluids to behave when dominated by gravity. As fascinating as many of them may seem at first glance, surface-tension phenomena are actually not that far away from our daily lives. Surface tension is everywhere because it costs energy to create areas of surfaces and interfaces, just like it costs energy to deform a solid (resulting in elasticity) or to elevate a weight (resulting in gravity). To minimize energy, a surface or an interface has the tendency to contract, and this tendency generates surface tension. The size of a system significantly affects the relative strengths of surface-tension effects comparing to effects of body forces, most commonly gravity. By equating the estimated magnitudes of surface tension and gravitational forces of a system, a length scale, know as the capillary length, can be defined. The capillary length of water on earth is about 2.7 mm. At the length scale of everyday objects, which is usually above the capillary length, surface-tension effects are not always prominent, because at those scales the competing force, gravity, is often much stronger. That is why the surface of a glass of water is more or less flat. However, as the size-scale decreases, surface tension decreases a lot slower than gravity, so when the size of a fluid system gets down to below the capillary length, surface tension takes over. One of the defining characteristics of this moment in human history, is the tremendous efforts we are putting into the research and engineering of micro- and nano-scale materials and structures − systems where surface tension is often the predominant force. It is important to study surface-tension effects so that we can use them to our advantage. In this Ph.D. dissertation, we have investigated some important surface-tension phenomena including capillarity, wetting, and wicking. We mainly focus on the geometric aspects of these problems, and to learn about how structures affect properties. Understanding these phenomena can help develop fabrication methods (Chapter 2), study surface properties (Chapter 3), and design useful devices (Chapter 4) at scales below the capillary length. In the first project (Chapter 2), we used numerical simulations and experiments to study the meniscus of a fluid confined in capillaries with complicated cross-sectional geometries. In the simulations, we computed the three-dimensional shapes of the menisci formed in polygonal and star-shaped capillaries with sharp or rounded corners. Height variations across the menisci were used to quantify the effect of surface tension. Analytical solutions were derived for all the cases where the cross-sectional geometry was a regular polygon or a regular star-shape. Power indices that characterize the effects of corner rounding were extracted from simulation results. These findings can serve as guide for fabrications of unconventional three-dimensional structures in Capillary Force Lithography experiments [J. Feng (2011) (a)]. Experimental demonstrations of the working principle was also performed. Although quantitative matching between simulation and experimental results was not achieved due to the limitation of material properties, clear qualitative trends were observed and interesting three-dimensional nano-structures were produced. A second project (Chapter 3) focused on developing techniques to produce three-dimensional hierarchically structured superhydrophobic surfaces with high aspect ratios. We experimented with two different high-throughput electron-beam-lithography processes featuring single and dual electron-beam exposures. After a surface modification procedure with a hydrophobic silane, the structured surfaces exhibited two distinct superhydrophobic behaviors − high and low adhesion. While both types of superhydrophobic surfaces exhibited very high (approximately 160_) water advancing contact angles, the water receding contact angles on these two different types of surfaces differed by about 50_ _ 60_, with the low-adhesion surfaces at about 120_ _ 130_ and the high-adhesion surfaces at about 70_ _ 80_. Characterizations of both the microscopic structures and macroscopic wetting properties of these product surfaces allowed us to pinpoint the structural features responsible for specific wetting properties. It is found that the advancing contact angle was mainly determined by the primary structures while the receding contact angle is largely affected by the side-wall slope of the secondary features. This study established a platform for further exploration of the structure aspects of surface wettability [J. Feng (2011) (b)]. In the third and final project (Chapter 4), we demonstrated a new type of microfluidic channel that enable asymmetric wicking of wetting fluids based on structure-induced direction-dependent surface-tension effect. By decorating the side-walls of open microfluidic channels with tilted fins, we were able to experimentally demonstrate preferential wicking behaviors of various IPA-water mixtures with a range of contact angles in these channels. A simplified 2D model was established to explain the wicking asymmetry, and a complete 3D model was developed to provide more accurate quantitative predictions. The design principles developed in this study provide an additional scheme for controlling the spreading of fluids [J. Feng (2012)]. The research presented in this dissertation spreads out across a wide range of physical phenomena (wicking, wetting, and capillarity), and involves a number of computational and experimental techniques, yet all of these projects are intrinsically united under a common theme: we want to better understand how simple fluids respond to small-scale complex surface structures as manifestations of surface-tension effects. We hope our findings can serve as building blocks for a larger scale endeavor of scientific research and engineering development. After all, the pursue of knowledge is most meaningful if the results improve the well-being of the society and the advancement of humanity.

Tensions and conflicts are a regular, but complex, part of organizational life. Triangulating multiple related theories is useful in gaining deeper insights into the complexities of tension or conflict management processes in organizations. This dissertation consists of three related essays that collectively contribute to answering a common research question: How and why tensions or conflicts are experienced and managed in different organizational contexts? The focus is on how three theoretical perspectives (contingency, paradox and dialectic) can be deployed to understand tension or conflict management in different contexts. This topic is relevant for three reasons. First, recent evidence demonstrates that both tensions and conflicts have constructive potential for individual and/or organizational change. Second, conflict studies have been shifting from short-term focused resolution to long-term-oriented transformation. This trend suggests that conflict studies might benefit from tension research, which is often long-term oriented due to the persistence of organizational tensions. Third, the advancement of tension research at the organization level calls for more tension research at the individual level. This presents a good opportunity to complement conflict studies, which mainly focus on individual and team level analyses. The dissertation uses a multi-perspective framework to analyze tension or conflict management in three organizational contexts that are rich in tensions and conflicts: family businesses, innovation in government, and the entrepreneurial university. The contingency perspective features either-or thinking that stresses the importance of making either-or choices according to contingencies. The paradox perspective features both-and thinking which favours strategies that address competing demands simultaneously. The dialectic perspective involves more-than thinking that aims to transcend tensions or conflicts through third parties, reframing, or other workarounds. The study of three different contexts (family business, government, and the university) allows for a better understanding of how different contexts shape the manifestation of tensions and conflicts and influence the choice of tension and conflict management strategies. The first essay (presented in chapter 2 and co-authored with Professor Mark Freel) is based on a literature review of family-related conflicts and how these conflicts are managed in family businesses. The review illustrates how the popularity of certain conflict management strategies is associated with some unique aspects of family businesses, such as the prevalence of relationship conflicts and the relatively high emotional bonding in families. The second essay (presented in chapter 3 and co-authored with Professor Samia Chreim) uses a longitudinal case study to examine how tension management evolves regarding two tensions observed in a government innovation diffusion process: control versus resistance and competing interests among stakeholders. The study demonstrates how tension management strategies evolve from simple to complex through a mechanism of joint learning between innovators and the government. The study also finds that tensions can be leveraged strategically to move the innovation project forward. The third essay (presented in chapter 4 and co-authored with Professor Samia Chreim and Professor Mark Freel) explores how academic and non-academic staff in two Canadian universities manage the reward and resource tensions associated with entrepreneurship-related activities. The study finds that individuals' strategies in managing the reward tension influence the type of entrepreneurship-related activities they engage in, and individuals' strategies in managing the resource tension influence the scale and scope of entrepreneurship-related activities at the university level. The study also illustrates that power relations are dynamic and that the implementation of both-and strategies can help balance power relations in a tension context. Collectively, the three essays in this dissertation shed light on how organizations, teams or individuals manage tensions or conflicts in three organizational contexts featuring hybrid logics (family and business; innovation and bureaucracy; entrepreneurship and scholarship). The multi-perspective framework has proved useful as a tool for analyzing both tension and conflict management. It also helps to frame important new research questions around topics such as how constructive potential is realized, why certain management strategies are more or less popular, and how strategies evolve with different types of tension or conflict.

The study and design of light-weight automobiles has emerged as an important area of interest in the government, academia, and the manufacturing industry. Significant advances in vehicle weight reduction technologies have taken place in almost all fields of transportation. Weight reduction is identified as a key factor to achieving fuel-economy, energy efficiency and environmental safety. The main objective of this thesis is to investigate cost effective design methodologies that enable fabrication of light weight structures, which subsequently result in a fuel saving. A few important techniques and trends of weight reduction in the automotive industry over the past few years are studied as part of the thesis. A summary from the survey of various approaches to weight reduction is presented in the literature review. This thesis is based on the theory of semi-tension fields, which was originally applied towards the design of structures in the aircraft industry. A semi-tension field is a post buckling phenomenon in which the load is continued to be carried even after the web has buckled. The advantage of semi-tension fields is twoold: first, by using this theory the structural stability of the original structure is retained; and secondly, its application replaces a comparatively heavy-weight shear resistant web with a thin web, potentially resulting in reduced weight. The semi-tension field theory is applied to the redesign of back panel of a prototype Ford F-150 pick up truck, which was modeled and analyzed using IDEAS Master Series 8 FEA software. The literature review also consists of the survey of several advances in the Semi-tension fields theory, and the corresponding trends in weight reduction. Analytical theories related to semi-tension field-based design and the respective mathematical formulations have also been described. Finite element analyses of the design that resulted from the application of the theory were carried out and results were validated using analytical theories. A technical paper demonstrating the redesign of a door beam was also studied and results are presented as an appendix.

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