13,824 research outputs found

    Dynamics of Elastic Capsules in constricted Microfluidic Channels

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    In this dissertation, we investigate computationally the transient dynamics of an elastic capsule in a square microchannel with two different types of constriction (i.e., a square or a rectangular constriction), and compare them with those owing to a droplet passing. The confinement and expansion dynamics of the fluid flow results in a rich deformation behavior for the capsule, from an elongated shape at the constriction entrance, to a flattened parachute shape at its exit. Larger capsules are shown to take more time to pass the constriction and cause higher additional pressure difference, owing to higher flow blocking. Our work highlights the effects of two different mechanisms for non-tank-treading transient capsule dynamics. The capsule deformation results from the combined effects of the surrounding and inner fluids normal stresses on the soft particles interface, and thus when the capsule viscosity increases, its transient deformation decreases, as for droplets. However, the capsule deformation is not able to create a strong enough inner circulation (owing to restrictions imposed by the material membrane), and thus the viscosity ratio does not affect much the capsule velocity and the additional pressure difference. In addition, the weak inner circulation results in a positive additional pressure difference even for low viscosity capsules, in direct contrast to low-viscosity droplets which create a negative. In addition, we focus on the hydrodynamic forces exerted on the constriction owing to the capsule passing by considering different capsule sizes, flow rates and viscosity ratios. As the capsule size increases, the forces increase owing to the higher flow blocking. The hydrodynamic forces on the constriction are only weakly affected by the viscosity ratio. For low-viscosity capsules, the additional hydrodynamic forces on the constriction are positive in direct contrast to low-viscosity droplets which create negative additional hydrodynamic forces on the constriction due to their strong inner circulation. Finally, we investigate the effects of the constriction type for the transient capsule dynamics. In the square constriction, the capsule is more deformed owing to the larger flow changes associated with the smaller cross-section area of this constriction. The higher flow blocking results in an increase of the capsule velocity, the additional pressure difference and the hydrodynamic forces exerted on the constriction owing to the capsule passing. Our findings suggest that the high cytoplasmatic viscosity, owing to the protein hemoglobin required for oxygen transport, does not affect adversely the motion of non-tank-trading erythrocytes in vascular capillaries

    Defining Video Space Art within Video Installations in the Context of Spaces and Spectators

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    This thesis is to introduce and examine Video Space Art as a form of Video Art. Being primarily practice-based research, it offers a theoretical and conceptual framework to find a better understanding for my artistic practices. The thesis studies the classification of Video Art. It contains an extended discussion of the place of Video Space Art in the context of Video Installation. Furthermore, the distinctions are made from Video Sculpture by theorizing space and spectator. The thesis develops the language of Video Installation. It proposes that the two main elements of Video Space Art are space and spectator. It provides a conceptual discussion of real and virtual space and the role of the spectator in Video Art are established. It then explores the languages in developed media of pictorial art, sculpture, architecture and landscape architecture. Because Video Installation is a hybrid medium, the languages found in these media are applied to deepen its meanings. Video Space Art is defined as a space-time experience that includes people as participants. The thesis applies these theories to artworks to distinguish Video Space Art from Video Sculpture. Nam Jun Paik's Magnet TV (1965), Eagle Eye (1996) and TV Clock (1963-81), Shigeko Kubota's Three Mountains (1976-79), and Bill Viola's Heaven and Earth (1992), The Crossing (1996) and Passage(1987), Dan Graham's Present Continuous Past(s)(1974), Bruce Nauman's Live-Taped Video Corridor(1969-70), David Hall's Progressive Recession (1975), and Peter Campus' Negative Crossing (1974) are among the artworks explored. The extended discussion of the concepts and concerns behind these artworks are followed by the classification of these artworks into Video Space Art and Video Sculpture. In addition to these artworks, the analyses of the elements of Video Space Art are applied to my own practical works: Two (1999), It Takes me 15 Minutes to go to School (2000), and Love Potion in my Heart (2004). (The appendix to this thesis contains the documentation of my works in DVD ROM format). The theoretical analysis presented in this thesis sheds light on the classification of Video Installation. A survey conducted identifies the works of Video Space Art. By defining Video Space Art, as distinct from Video Sculpture I have refined aspects of the theoretical base and extended the understanding of my own practical work

    The Effect Of Short-Term Debt On Accrual Based Earnings Management And Real Earnings Management

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    This study investigates whether short-term debt is related to earnings management. Short-term debt is divided into total current liabilities, debt in current liabilities and short-term borrowings. In addition, this study examines how short-term debt is related to how firms manage their earnings. I use discretionary accruals and real operating decisions as the earnings management method. The study finds that debt in current liabilities only has a statistically significant impact on accrual earnings management, and short-term borrowings are only shown to have a statistically significant impact on real earnings management. These results indicate that managers engage in accrual earnings management of debt included in current liabilities and use real earnings management of short-term borrowings from financial institutions.Therefore, this evidence indicates that managers engage in accrual earnings management of debt in included current liabilities when they face the liquidity risk of short-term debt, and the firms with debt financing constraints are likely to manage real earnings in spite of enhanced firm monitoring by lenders such as financial institutions. The findings in this study may have implications in the debate about the monitoring function of financial institutions such as banks

    Woman in Art

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    This thesis describes the author\u27s creation of sculptures combining glass and metal, in which she tests the boundary between realism and abstraction, and that between jewelry and sculpture. This sculpture is intended to embody the voluptuous and sensual nature of the human female form

    Developing Hawaii Tourism Dashboard

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    Corporate Social Responsibility in the U.S. Travel Industry

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    As the travel industry consists of various sectors, which often depend on environmental and cultural resources, socially responsible business policies, programs and practices are essential to achieve sustainable tourism at the local as well as the global level. nonetheless, it has yet to be known how the industry perceives and practices corporate social responsibility (CSR) activities. Thus, this study aims to better understand the opinions about and engagementin (CSR) by the the U.S. travel industry. Results of a survey conducted to the members of Travel Industry Association of America can provide travel companies with an important reference point about the concept of and practices of CSR by the industry members. Moreover, results of this study will reveal areas for further research

    The Persistent Difficulty of Early Fraction Ideas in Early Secondary School Mathematics

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    This study explored the nature of difficulties of seventh and eighth grade students who struggled building their conceptual understanding of early fraction ideas, in particular ordering fractions. The participants engaged in a sequence of lessons that involved the use of fraction circles. The intervention of four weekly class sessions was adapted from the Rational Number Project (RNP) curriculum that has been created for and refined through teaching experiments in the RNP research since 1979. Pre and post group interviews were conducted with each student group for a sufficient identification of the nature of the students’ difficulties. This study identified the whole number dominance strategies used by the students for ordering fractions before and even after the intervention. The students also revealed minimal use of informal ordering strategies that involve more conceptual than procedural understanding of the concept of initial fraction ideas. Considering the short intervention, there was subtle (but meaningful) evidence for a positive influence of the fraction circle model developed within the RNP on students’ developing understanding of early fraction ideas. This study suggests the need of a remedial intervention for early secondary students showing the persistent difficulty with early fraction ideas. Students need to be given enough time with not only concrete models but also appropriate usage of language to support a complete understanding of how to use the models. Keywords: Rational Number Project (RNP), fraction circle model, initial fraction ideas, ordering fraction

    Creating a Virtual World for Mathematics

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    A virtual world was created using the popular sandbox game Minecraft to support the development of preservice teachers’ knowledge for teaching mathematics. Preservice teachers explored the virtual world for a geometry activity involving area and volume problems. They then discussed how this integration of technology could support students’ effective learning of mathematics in a meaningful way. The findings of the study demonstrated that to a certain extent the Minecraft activity supported the transfer of knowledge from preservice teachers’ mathematics content knowledge to their mathematics pedagogical and instructional practice knowledge. Preservice teachers appreciated the usefulness and effectiveness of the Minecraft activity in enhancing the teaching and learning of mathematics by visualizing mathematical concepts in the virtual world. This integration of technology also gave them an opportunity for professional growth. Although this study focuses on preservice teachers’ perspectives on the Minecraft activity, the technology integration using Minecraft will also be beneficial for students because it engages them in active and discovery learning
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