Theses & Dissertations
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This collection is exclusively made up of theses, dissertations, and project reports submitted as a requirement for completing a graduate degree at UPR-Mayagüez.
If you are a UPRM graduate student and you are looking for information related to the deposit process, please refer to https://libguides.uprm.edu/repositorioUPRM/tesis
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PublicationModeling open channel flow at the confluence of lateral discharging pipes into receiving channels( 2024-07-10)Storm runoff from major and minor systems is often discharged into water bodies through lateral conduits, mimicking natural river confluence phenomena. This forms a flowing body of water with new hydraulic conditions. The interaction between storm sewer outlets and receiving water bodies presents challenges in engineering design, particularly regarding flow conditions and elevation changes. Few storm sewer design manuals consider and regulate the confluence due to the lateral drainage pipe. Despite the availability of Computational Fluid Dynamics (CFD) software, which is accurate but varies in terms of time and computational power costs, practical solutions for engineers remain limited. The objective of this study is to determine the hydraulic behavior of storm sewer discharges in receiving water bodies flowing like open channels. By leveraging advancements in computer processing power, the research seeks to develop practical guidelines and design aids for engineers to assess storm sewer outlets’ hydraulics at junctions using more accessible 1D models. Confluence flow behavior was captured using the OpenFOAM CFD model. The results are presented as normalized contour maps for three junction angle configurations: 30, 60, and 90 degrees. These show how a change in the confluence angle affects the overall water levels within the channel by increasing and decreasing them in certain critical areas around the confluence point. Velocities and water levels downstream show change depending on the initial flow regime where subcritical flow increases the Froude number at lower angles and supercritical flow decreases the Froude number at higher angles. Given these findings, increases in channel wall shear stress and overtopping can occur depending on the confluence angle.
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PublicationEfecto de la disponibilidad de pasto en diferentes épocas del año sobre el perfil de la leche producida por el ganado lechero en Puerto Rico( 2024-07-09)In winter (January to March) and summer (July to September), the effect of forage availability on production and composition in terms of fat, protein, and lactose in milk was evaluated. To this end, a study was carried out on two dairy farms, Lajas (rotational grazing) and San Sebastián (intensive rotational grazing). On each farm, forage was sampled in winter (March) and summer (September); and concentrate (supplemented to rotational grazing), only once. Samples were analyzed for chemical composition and a yield estimate was obtained using the disk method (Santillan et al., 1979). The Lajas concentrate was higher in NDF and ADF; and that of San Sebastián had more protein and energy. In winter, CP, TDN, NEL, Ca, and K were lower in the forage from Lajas than in that from San Sebastián. In summer, CP, ADF, NEL, TDN, Ca, and P were lower in the forage from San Sebastián than in that from Lajas. On both farms, daily DM yield was higher in summer; and, it was greater in San Sebastián than in Lajas, in both periods. However, the availability of DM per cow per cycle and per cow per day was greater in Lajas, in both seasons; and, on both farms, in summer. The climate, the quality of the forage and concentrate, as well as the yield by farm and season, influenced the milk production and its quality. Dairy protein was lower in summer than in winter on both farms. Milk production and lactose were lower in San Sebastián than in Lajas; while, the opposite case occurred for the fat and protein variables. There were interactions between farm and season on fat, protein, and lactose (P < 0.05). Fat percentage was lower in summer on the San Sebastián farm; and lower in winter, on the Lajas farm (P < 0.0002). Protein was higher in winter on both farms (P < 0.0333). Lactose increased, as fat and protein decreased (P < 0.0001). A change in climate and season will not necessarily result in significant differences in milk, fat, and lactose production.
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PublicationAssessment and optimization of an innovative radon mitigation technique in residential buildings( 2024-07-10)Radon, a naturally occurring radioactive gas, poses health risks in enclosed spaces. Studies show nearly six percent of U.S. homes face high radon levels requiring mitigation. Traditional methods, though effective, can be costly and impractical for some dwellings. The Environmental Protection Agency (EPA) urges innovative mitigation strategies. Recent research suggests activated charcoal systems could be viable but require more case studies for EPA endorsement. Radon concentrations are higher near entry points. This study aims to determine if adsorption device placement affects radon distribution and concentration over time. This study, via numerical simulations, analyzes radon distribution in a ventilated room to optimize mitigation device placement. The effect of adsorption and radioactive decay is simulated along with a local sink. If placement impacts distribution, a multi-stage suction device with an activated charcoal filter is proposed. This approach could provide sustainable mitigation for low-income housing, improving public health by safeguarding vulnerable populations.
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PublicationThe ecological importance of marine sponges inhabiting Puerto Rican shallow & mesophotic coral reef ecosystems( 2024-04-09)This research consists primarily of four studies that investigate the ecological and functional roles that marine sponges play in supporting biodiversity and maintaining reef resilience across shallow (<30 m depth) and mesophotic (>30 m depth) coral reef ecosystems (MCEs). Findings from the Guánica Biosphere Reserve shelf edge show distinct benthic assemblages of sponge species. Shallow surveys yielded a higher species richness than mesophotic, with 60 and 54 species respectively, and an overall total of 71 species identified from both depths, with 45 species overlapping (63.0%). The study of infaunal communities within the sciophilous calcareous sponge Clathrina lutea revealed a rich diversity of associated fauna, emphasizing the ecological significance of these small sponges as habitat and/or as a refuge for undescribed macrofauna. At least four disease-like conditions affecting the giant barrel sponge, Xestospongia muta, within shallow and mesophotic coral reefs in Puerto Rico were observed and described. These conditions, including the description of an emerging disease, Xestospongia-Tissue Hardening Condition (X-THC), threaten the overall health of the Xestospongia species complex, the sponge community, and their associated fauna. Evidence supporting the hypothesis that X. muta functions as a micro-oasis for biodiversity confirms its critical ecological role as an ecosystem foundational species. By introducing the framework OA2SIS: Oscillators, Attractors, and Amplifiers of Symbiotic Interactions between Species, highlights X. muta’s evolutionary and ecological significance in coral reef ecosystems, as potential facilitators of symbiotic interactions. Combined, these results solidify the ecological and evolutionary importance of marine sponges within coral reefs, their protection and conservation should be a high priority for coral reef and coastal managers.
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PublicationProblema generalizado de doble fase sobre dominios arbitrarios( 2024-07-16)The English abstract for this thesis is included in this item record as a pdf file. To view the abstract, select it from the item's list of files or paste the following address on your browser's address bar: https://tinyurl.com/35y9a27r