8,068 research outputs found

    Simulation of metal powder packing behaviour in laser-based powder bed fusion

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    Laser-based powder bed fusion (L-PBF) is a method of additive manufacturing, in which metal powder is fused into solid parts, layer by layer. L-PBF shows high promise for manufacture of functional Tungsten parts, but the development of Tungsten powder feedstock for L-PBF processing is demanding and expensive. Therefore, computer simulation is explored as a possible tool for Tungsten powder feedstock development at EOS Finland Oy, with whom this thesis was made. The aim of this thesis was to develop a simulation model of the recoating process of an EOS M 290 L-PBF system, as well as a validation method for the simulation. The validated simulation model can be used to evaluate the applicability of the used simulation software (FLOW-3D DEM) in powder material development, and possibly use the model as a platform for future application with Tungsten powder. In order to reduce complexity and uncertainties, the irregular Tungsten powder is not yet simulated, and a well-known, spherical EOS IN718 powder feedstock was used instead. The validation experiment is based on building a low, enclosed wall using the M 290 L-PBF system. Recoated powder is trapped inside as the enclosure is being built, making it possible to remove the sampled powder from a known volume. This enables measuring the powder packing density (PD) of the powder bed. The experiment was repeated five times and some sources of error were also quantified. Average PD was found to be 52 % with a standard deviation of 0.2 %. The simulation was modelled after the IN718 powder and corresponding process used in the M 290 system. Material-related input values were found by dynamic image analysis, pycnometry, rheometry, and from literature. PD was measured with six different methods, and the method considered as most analogous to the practical validation experiment yielded a PD of 52 %. Various particle behavior phenomena were also observed and analyzed. Many of the powder bed characterization methods found in literature were not applicable to L-PBF processing or were not representative of the simulated conditions. Many simulation studies were also found to use no validation, or used a validation method which is not based on the investigated phenomena. The validation model developed in this thesis accurately represents the simulated conditions and is found to produce reliable and repeatable results. The simulation model was parametrized with values acquired from practical experiments or literature and closely matched the validation experiment, and could therefore be considered a truthful representation of the powder recoating process of an EOS M 290. The model can be used as a platform for future development of Tungsten powder simulation

    Irish Ocean Climate and Ecosystem Status Report

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    Summary report for Irish Ocean Climate & Ecosystem Status Report also published here. This Irish Ocean Climate & Ecosystem Status Summary for Policymakers brings together the latest evidence of ocean change in Irish waters. The report is intended to summarise the current trends in atmospheric patterns, ocean warming, sea level rise, ocean acidification, plankton and fish distributions and abundance, and seabird population trends. The report represents a collaboration between marine researchers within the Marine Institute and others based in Ireland’s higher education institutes and public bodies. It includes authors from Met Éireann, Maynooth University, the University of Galway, the Atlantic Technological University, National Parks and Wildlife, Birdwatch Ireland, Trinity College Dublin, University College Dublin, Inland Fisheries Ireland, The National Water Forum, the Environmental Protection Agency, and the Dundalk Institute of Technology.This report is intended to summarise the current trends in Ireland’s ocean climate. Use has been made of archived marine data held by a range of organisations to elucidate some of the key trends observed in phenomena such as atmospheric changes, ocean warming, sea level rise, acidification, plankton and fish distributions and abundance, and seabirds. The report aims to summarise the key findings and recommendations in each of these areas as a guide to climate adaptation policy and for the public. It builds on the previous Ocean Climate & Ecosystem Status Report published in 2010. The report examines the recently published literature in each of the topic areas and combines this in many cases with analysis of new data sets including long-term time series to identify trends in essential ocean variables in Irish waters. In some cases, model projections of the likely future state of the atmosphere and ocean are presented under different climate emission scenarios.Marine Institut

    The Active CryoCubeSat Technology: Active Thermal Control for Small Satellites

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    Modern CubeSats and Small Satellites have advanced in capability to tackle science and technology missions that would usually be reserved for more traditional, large satellites. However, this rapid growth in capability is only possible through the fast-to-production, low-cost, and advanced technology approach used by modern small satellite engineers. Advanced technologies in power generation, energy storage, and high-power density electronics have naturally led to a thermal bottleneck, where CubeSats and Small Satellites can generate more power than they can easily reject. The Active CryoCubeSat (ACCS) is an advanced active thermal control technology (ATC) for Small Satellites and CubeSats, which hopes to help solve this thermal problem. The ACCS technology is based on a two-stage design. An integrated miniature cryocooler forms the first stage, and a single-phase mechanically pumped fluid loop heat exchanger the second. The ACCS leverages advanced 3D manufacturing techniques to integrate the ATC directly into the satellite structure, which helps to improve the performance while simultaneously miniaturizing and simplifying the system. The ACCS system can easily be scaled to mission requirements and can control zonal temperature, bulk thermal rejection, and dynamic heat transfer within a satellite structure. The integrated cryocooler supports cryogenic science payloads such as advanced LWIR electro-optical detectors. The ACCS hopes to enable future advanced CubeSat and Small Satellite missions in earth science, heliophysics, and deep space operations. This dissertation will detail the design, development, and testing of the ACCS system technology

    THE DEVELOPMENT OF TYPE 2 IMMUNE AGONISTS AS PRO-REGENERATIVE IMMUNOTHERAPIES

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    Adult mammals have large deficits in their ability to heal traumatic soft-tissue injuries without subsequent scarring and long-term fibrosis. Type 2 innate and adaptive immunity has been strongly connected to wound healing and has been shown to be a critical factor for the healing of musculoskeletal injuries. Helminth parasites are a well characterized class of pathosymbionts that have co-evolved to boost host type 2 immune responses, which ultimately enhance the mutual survival of the parasite and host through the promotion of anti-inflammatory and wound healing mechanisms. While many aspects of the immune response to helminth infection and egg products have been well-characterized, the mechanistic link of type 2 immunity to tissue regeneration, and the potential for safely using helminth products as immunotherapies in wound repair remains unclear. Here, we develop and validate a pro-regenerative immunotherapy from Schistosoma mansoni (S. mansoni) helminth egg products. In agreement with previous literature, we found that soluble egg antigens (SEA) boosted type 2 immune signatures, but also increased inflammatory signatures we have previously associated with diminished tissue repair. Seeking to develop an immunotherapy to boost short-term type 2 immune responses, decrease inflammation, and incorporate pro-resolving aspects of helminth egg products, we modify the isolation process to establish a new formulation of SEA. We apply this ‘regenerative’ SEA (RSEA) to murine skeletal muscle injuries and find that the short-term accumulation of T helper type 2 cells, regulatory T cells, and eosinophils correlated with decreased expression of pro-inflammatory signatures. Further, we find that this led to a decrease in tissue fibrosis and improved functional repair when assessed at later timepoints post-injury. Seeking to determine the regenerative potential of RSEA in semi-immune privileged tissues, we apply RSEA in articular joint and corneal injury models and find crucial myeloid-adipose-lymphocyte interactions may be driving the type 2 immunity repair process. Lastly, we compare other type 2 agonists in the wound to RSEA at early stages and propose mechanistic pathways that may be crucial to the pro-regenerative responses found among some type 2 agonists

    Panel-based Assessment of Ecosystem Condition of Norwegian Barents Sea Shelf Ecosystems

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    The System for Assessment of Ecological Condition, coordinated by the Norwegian Environment Agency, is intended to form the foundation for evidence-based assessments of the ecological condition of Norwegian terrestrial and marine ecosystems not covered by the EU Water Framework Directive. The reference condition is defined as “intact ecosystems”, i.e., a condition that is largely unimpacted by modern industrial anthropogenic activities. An ecosystem in good ecological condition is defined as a system that does not deviate substantially from this reference condition in structure, functions or productivity. This means that, in practice, what is assessed here is the extent to which an ecosystem is impacted by anthropogenic drivers. This report describes the first operational assessment of the ecological condition of Norwegian Arctic and Sub-Arctic marine shelf ecosystems in the Barents Sea. The assessment method employed is the Panel-based Assessment of Ecosystem Condition (PAEC1), and the current assessment has considered to what extent the Barents Sea shelf ecosystems deviate from the reference condition2 by evaluating change trajectories

    Infertility: An Evaluation of Treatment Modalities and Ethical Considerations

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    This thesis reviews a variety of options for treatment of infertility, along with ethical considerations for each. The basis for ethical concerns will be primarily a biblical worldview, as the goal is to support Christian couples in decisions regarding infertility treatment. The biblical worldview is outlined to provide readers with an understanding of its core principles, and the Bible is used as the primary source for ethical discussion. The most common etiologies of infertility are outlined, followed by treatment modalities grouped by category. While some modalities present very few ethical concerns, others require careful consideration in many regards. Many of these treatments fall into ethical grey areas, and thus the decision regarding their allowability is left in the hands of the reader. While this thesis discusses a wide variety of treatment modalities, it is not intended to encompass every possible option. The most commonly utilized and those with significant ethical concerns are addressed

    The Poetics of Renunciation: The Jamesian Tradition of Recognition in Modern and Contemporary Transatlantic Novels

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    The present dissertation offers fresh readings of the renunciation pattern observed in some seminal literary fiction of the twentieth and twenty-first centuries. By foregrounding recognition (anagnorisis) as the dominant literary preoccupation for canonical modernists such as Henry James and Edith Wharton, the present study tackles the ever-present problematic issue of passivity of action existing in modern and contemporary transatlantic fiction. It has been argued that even though anagnorisis, in the Aristotelian sense of the word, has often been employed as the most critical plot element by modernist and contemporary writers, this revelatory moment tends to produce passivity in the modern protagonists rather than to induce a dramatic action. In this sense, I argue that some well-known contemporary novelists, such as Kazuo Ishiguro and Ian McEwan, are strictly Jamesian in treating the concept of recognition. The method of study relies on close readings in a comparative mode. Also, to shed light on the characters’ passivity, I partially incorporated Emmanuel Levinas’ phenomenology of aesthetics. Levinas is primarily a philosopher of ethics, but he has an interesting philosophy on art and aestheticism. His philosophy of aesthetics is drawing more attention from critics in recent years. Similar to philosophers such as Plato, and Benjamin, Levinas is a critic of art and aestheticism. Like Adorno, Levinas believes that art and artistic practices have such power that can derail the subject’s intentionality from the real towards the non-real or imaginary. For him, since an aesthetic image is pleasurable and complete, it does not need to enter a dialogue with a world outside itself; hence it is an autonomous existence that provides an escape route for the subject and disengages him/her from the real world. In this dissertation, I argue that the passivity observed in modern protagonists is due to their engagement with the aesthetic mental image. It is due to this aesthetic image that they are gradually disengaged from the real world. Therefore, the protagonists prioritize the imaginary over the real. As a result, the recognition loses its functionality because the ego is already lulled by the aesthetic image

    Bayazid Abad (Bayazi Awa): Transition of Material Patterns from the Middle Bronze to the Iron Age in North-Western Iran

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    This study focuses on the tomb of Bayazid Abad, located in North-Western Iran near Hasanlu. The tomb contains artifacts from the Middle Bronze Age, Late Bronze Age, and Iron Age I and II, providing valuable insights into the material culture of the region during those periods. The findings from Bayazid Abad are analyzed alongside those from Hasanlu and Dinkha to understand the broader cultural context. The dating and recognition of the Bronze Age and Iron Age in North-Western Iran were initially based on excavations at Hasanlu. However, the understanding of the site's stratigraphy and dating has evolved over time, with Michael Danti's comprehensive study being particularly significant. This dissertation aligns with Danti's chronology, which encompasses architecture, pottery, seals, beads, weapons, and other artifacts from Bayazid Abad, given the strong connection between the two sites. By studying the burial goods from Bayazid Abad, this research aims to expand our knowledge of the material culture in North-Western Iran from the second to the first millennium BC. The primary objectives include determining the cultural period(s) represented by Bayazid Abad, exploring the connections between the tomb and neighboring sites such as Hasanlu and Dinkha, and enhancing the existing database of North-Western Iranian material culture. While previous studies focused mainly on pottery, Bayazid Abad offers the opportunity to investigate other aspects of material culture beyond ceramics. The tomb's significant collection of artifacts can provide valuable insights into various cultural practices and traditions of the region

    Animal Welfare - Environment - Sustainable Development Nexus: Scoping Study

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    A detailed report on the links between animal welfare, environmental health and global sustainability. Issues discussed include climate change, biodiversity, pollution and waste management, one health, sustainable development and just transitions
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