8,568 research outputs found

    Meso-scale FDM material layout design strategies under manufacturability constraints and fracture conditions

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    In the manufacturability-driven design (MDD) perspective, manufacturability of the product or system is the most important of the design requirements. In addition to being able to ensure that complex designs (e.g., topology optimization) are manufacturable with a given process or process family, MDD also helps mechanical designers to take advantage of unique process-material effects generated during manufacturing. One of the most recognizable examples of this comes from the scanning-type family of additive manufacturing (AM) processes; the most notable and familiar member of this family is the fused deposition modeling (FDM) or fused filament fabrication (FFF) process. This process works by selectively depositing uniform, approximately isotropic beads or elements of molten thermoplastic material (typically structural engineering plastics) in a series of pre-specified traces to build each layer of the part. There are many interesting 2-D and 3-D mechanical design problems that can be explored by designing the layout of these elements. The resulting structured, hierarchical material (which is both manufacturable and customized layer-by-layer within the limits of the process and material) can be defined as a manufacturing process-driven structured material (MPDSM). This dissertation explores several practical methods for designing these element layouts for 2-D and 3-D meso-scale mechanical problems, focusing ultimately on design-for-fracture. Three different fracture conditions are explored: (1) cases where a crack must be prevented or stopped, (2) cases where the crack must be encouraged or accelerated, and (3) cases where cracks must grow in a simple pre-determined pattern. Several new design tools, including a mapping method for the FDM manufacturability constraints, three major literature reviews, the collection, organization, and analysis of several large (qualitative and quantitative) multi-scale datasets on the fracture behavior of FDM-processed materials, some new experimental equipment, and the refinement of a fast and simple g-code generator based on commercially-available software, were developed and refined to support the design of MPDSMs under fracture conditions. The refined design method and rules were experimentally validated using a series of case studies (involving both design and physical testing of the designs) at the end of the dissertation. Finally, a simple design guide for practicing engineers who are not experts in advanced solid mechanics nor process-tailored materials was developed from the results of this project.U of I OnlyAuthor's request

    Scaling up integrated photonic reservoirs towards low-power high-bandwidth computing

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    Building body identities - exploring the world of female bodybuilders

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    This thesis explores how female bodybuilders seek to develop and maintain a viable sense of self despite being stigmatized by the gendered foundations of what Erving Goffman (1983) refers to as the 'interaction order'; the unavoidable presentational context in which identities are forged during the course of social life. Placed in the context of an overview of the historical treatment of women's bodies, and a concern with the development of bodybuilding as a specific form of body modification, the research draws upon a unique two year ethnographic study based in the South of England, complemented by interviews with twenty-six female bodybuilders, all of whom live in the U.K. By mapping these extraordinary women's lives, the research illuminates the pivotal spaces and essential lived experiences that make up the female bodybuilder. Whilst the women appear to be embarking on an 'empowering' radical body project for themselves, the consequences of their activity remains culturally ambivalent. This research exposes the 'Janus-faced' nature of female bodybuilding, exploring the ways in which the women negotiate, accommodate and resist pressures to engage in more orthodox and feminine activities and appearances

    Assessing Agroecological Principles at the Intervale in Burlington, Vermont: A Case Study and Multimethod Research with a Participatory Approach in a Peri-Urban Socioecological System

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    The emerging field of urban agroecology promises to mend the prevalent unsustainable rupture between rural and urban/peri-urban agri-food endeavors since global industrial conglomerates took power. My research contributes to the efforts of mending this rupture by, first, advancing the academic discussion on how to fill an evidence-based gap on the use of the much theorized multidimensional and cross-disciplinary principles of agroecology to assess community-based agri-food systems beyond the farm level. To do so, my research uses the fifteen principles of agroecology proposed by the non-profit Coopération Internationale pour le Développement et la Solidarité (CIDSE, 2018). Second, my research expands the understanding of how these agroecological principles may be put into practice in different cases and scenarios, especially in urbanized environments. This investigation uses a single significant case study methodology to share a place-based experience as a possible example of urban agroecology. The case study is a 340-acre information-rich peri-urban organic agroecosystem in Burlington, Vermont, owned and managed by the Intervale Center. My research investigates how the Intervale, a non-profit organization and socioecological system, may be practicing agroecology and consider opportunities to strengthen such practices. My investigation involves a principles-focused and context-sensitive baseline assessment (inspired by Patton, 2018) using a qualitative multimethod framework and a participatory action research (PAR) approach. The multimethod framework triangulates a 'practical' PAR stream of inquiry for the co-creation of knowledge with a purposive sample of participants (semi-structured interviews with visual tools such as CIDSEs agroecological principles infographic, site mapping, and photovoicing) and a 'theoretical' stream where the researcher connects theory to practice (participatory observation, photo-documentation, and document analysis) for an integrated analysis. According to observations and participants' responses, the Intervale follows agroecological principles. The collective practices related to the agroecological principles of strengthening local food producers and community and nourishing biodiversity and soils are most prevalent at the Intervale. The organization also plays a noticeable role under the principle of enhancing the power of the local market and building on a social and solidarity economy. There are also some specific areas of intervention in the organizations operations to achieve higher levels of agroecological transformation, especially under the principles of fostering more diversity and solidarity, encouraging stronger participation of food producers, and promoting more farmer-to-farmer exchanges. Conclusively, this research reduces the evidence-based gap between the theory supporting a set of agroecological principles and their application beyond the farm level and in an urbanized setting. The comprehensive methodology and the results illuminate how the Intervale's placed-based practices could serve as an example to advance urban agroecology in North America and even other regions

    Committing to the Discomfort of Care and Curiosity: Investigations of Cows' Welfare, Lives, and Relationships

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    In this dissertation, I investigate cow welfare on grass-fed beef farms to, in part, question and examine the possibility of grass-fed beef farming in providing cows with more care than conventional beef farming. In connection with this, I analyze cow welfare to explore the agencies, subjectivities, and relationships of cows whose lives are taken in the name of food. I unpack grass-fed beef farmers' understandings and practices of cow welfare and use animal geographies, biopolitics, and critical food studies to unearth the ethical complexities of farmer-cow relations, which complicate and strengthen cow welfare's multidimensionality. Alongside working with farmers, I acknowledge and engage with cows as research subjects who teach me about their welfare, lives, and intimate relationships with others. Woven into my analysis of cow welfare is my exploration of the entanglement of caring, loving, profiting, and killing that underscores farmer-cow relationships. Within this context, I write about the different ways that I physically, mentally, and emotionally navigated this exploration as a vegan, feminist animal geographer committed to the discomfort of care and curiosity that an analysis of life, death, and relationality summoned within me. Through the process of navigating this discomfort, I offer my own ethics of care with animals

    Engineering Tools to Probe and Manipulate the Immune System at Single-Cell Resolution

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    My thesis focuses on developing experimental and computational tools to probe and manipulate cellular transcriptomes in the context of human health and disease. Chapter 1 and 2 focus on published work where we leverage single-cell RNA sequencing (scRNA-seq) to understand human immune variability, characterize cell-type specific biases of multiple viral variants within an animal, and assess temporal immune response in the brain to delivery of genetic cargo via an adeno-associated virus (AAV). Chapter 3 and 4 present progress I have made on tools for exporting RNA extracellularly and engineering of a transcription factor for modulating macrophage state. For probing cellular transcriptome states, we have developed a platform using multiplexed single-cell sequencing and out-of-clinic capillary blood extraction to understand temporal and inter-individual variability of gene expression within immune cell types. Our platform enables simplified, cost-effective profiling of the human immune system across subjects and time at single-cell resolution. To demonstrate the power of our platform, we performed a three day time-of-day study of four healthy individuals, generating gene expression data for 24,087 cells across 22 samples. We detected genes with cell type-specific time-of-day expression and identified robust genes and pathways particular to each individual, all of which could have been missed if analyzed with bulk RNA-sequencing. Also, using scRNA-seq, we have developed a method to screen and characterize cellular tropism of multiple AAV variants. Additionally, I have looked at AAV-mediated transcriptomic changes in animals injected with AAV-PHP.eB three days and twenty-five days post-injection. I have found that there is an upregulation of genes involved in p53 signaling in endothelial cells three days post-injection. In the context of manipulating cellular transcriptomic states, I demonstrate that a fusion between RNA targeting enzyme, dCas13, and capsid-forming neuronal protein, Arc, is able to form a capsid-like structure capable of encapsulating RNA. I also present methods and preliminary data for tuning macrophage states through mutations in transcription factor EB (TFEB) using scRNA-seq as a readout.</p

    The SOAS Journal of Postgraduate Research, vol. 14 (2020-21)

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    Behavioral Economics & Machine Learning Expanding the Field Through a New Lens

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    In this thesis, I investigate central questions in behavioral economics as well as law and economics. I examine well-studied problems through a new methodological lens. The aim is to generate new insights and thus point behavioral scientists to novel analytical tools. To this end, I show how machine learning may be used to build new theories by reducing complexity in experimental economic data. Moreover, I use natural language processing to show how supervised learning can enable the scientific community to expand limited datasets. I also investigate the normative impact of the use of such tools in social science research or decision-making as well as their deficiencies

    Adaptive task selection using threshold-based techniques in dynamic sensor networks

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    Sensor nodes, like many social insect species, exist in harsh environments in large groups, yet possess very limited amount of resources. Lasting for as long as possible, and fulfilling the network purposes are the ultimate goals of sensor networks. However, these goals are inherently contradictory. Nature can be a great source of inspiration for mankind to find methods to achieve both extended survival, and effective operation. This work aims at applying the threshold-based action selection mechanisms inspired from insect societies to perform action selection within sensor nodes. The effect of this micro-model on the macro-behaviour of the network is studied in terms of durability and task performance quality. Generally, this is an example of using bio-inspiration to achieve adaptivity in sensor networks
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