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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Now showing 1 - 5 of 2974
  • Publication
    Evaluation of tropical bamboo species with potential as a renewable source for charcoal
    ( 2008) Sanon, Antoine ; Papadopoulos, Christopher ; College of Agricultural Sciences ; Valencia, Elide ; Brian, Irish ; Other ; Zapata, Rocio
    This research investigated the use of bamboo as a highly renewable primary material for charcoal production. Bamboo (Bambusaea) is an efficient, accessible and economical resource that can meet the demand for fuel and provide added income while mitigating land ecosystem damaged. Bamboo charcoal has been tested and proven to be a viable biomass in many countries for domestic use and commercial applications. The potential to develop bamboo charcoal in Haiti, where over 85% of the population relies on biomass energy for domestic uses was explored. This research sourced samples of 19 tropical bamboo species maintained at USDA-ARS Tropical Agricultural Research Station (TARS) in Mayagüez, Puerto Rico, to measure its calorific value. Three tree wood species, Caoba, (Swietenia Mahogany), Mango, (Mangifera indica), and Ucar (Bucida buceras) were tested to compare its calorific value. For each bamboo and tree species, three replications were prepared in raw form (air dried or oven dried, but not carbonized), and three replications were carbonized to produce charcoal. Carbonization was performed in a metal can, fueled by propane, at a peak temperature of 500oC. Calorific value for each raw and charcoal sample was determined using the IKA Oxygen Bomb Calorimeter. The mean results showed that bamboo charcoal has higher calorific value range than raw bamboo wood (25.92MJ/kg vs 17.97MJ/kg), and also has similar calorific value to tree wood charcoal (25.92MJ/kg vs 26.78MJ/kg). Raw bamboo also has similar calorific value as raw tree wood (17.97MJ/kg vs 17.26MJ/kg). The research also determined that calorific value is not related to wall thickness. These results, which show similar capacities for bamboo and tree wood, has potential to sustainably impact the local environment, because charcoal producers can explore the use of bamboo as a viable alternative to tree wood. Finally, through conversations with local charcoal producers in Haiti, this research reveals a consciousness of the negative environmental impacts of using trees for charcoal, and a willingness to experiment with bamboo as an alternative.
  • Publication
    Evaluación de propiedades físicas y mecánicas de algunos bambús tropicales cultivados en Mayagüez, Puerto Rico
    ( 2016) Acevedo Acevedo, Pablo ; Papadopoulos, Christopher ; College of Engineering ; Acosta, Felipe ; Suárez, Luis ; Department of Civil Engineering ; Cruz-Pol, Sandra
    La actual crisis ecológica y social que enfrentamos en el mundo exige adoptar enfoques alternativos que valoren la labor humana, la redistribución justa de los recursos y el bienestar con la Naturaleza. Desde el campo de la ingeniería estructural se puede avanzar hacia estos objetivos a través de la bioconstrucción, el cual entre muchos factores considera el uso y manejo responsable de los materiales locales y naturales. Dentro de este contexto, el bambú y su utilización tiene un gran potencial como fuente de tecnología apropiada para Puerto Rico. El bambú leñoso es una grama gigante (familia poaceae) de rápido crecimiento con múltiples beneficios ecológicos y sociales. Dentro del sector de la construcción alternativa su material ha sido identificado por sus buenas capacidades mecánicas, sustentabilidad ambiental, alta renovabilidad en producción y socialmente resiliente, entre otras. Dada su naturaleza, múltiples factores (anatómicos, geográficos, geométricos y otros) afectan directamente su desarrollo creando variaciones en sus propiedades físicas y mecánicas. Por lo tanto, el estudio detallado de estas propiedades se convierte en un componente indispensable para el análisis y diseño estructural adecuado con bambú. Estudios precedentes a las propiedades físicas y mecánicas del bambú en Puerto Rico se limitan a una investigación (Properties of Some Bamboos Cultivated in the Western Hemisphere, 1956). No obstante, las especies estudiadas y los métodos experimentales utilizados no satisfacen los factores de aplicabilidad constructiva con bambú y de comparación con investigaciones más contemporáneas. Por otro lado, esta tesis sigue un protocolo de prueba utilizando los requisitos del ISO-22157 1&2 y una selección de especie tomando en cuenta factores como el cumplimiento con maduración optima, disponibilidad y su potencial de uso para sistemas estructurales. Las seis especies de bambús seleccionadas (Bambusa vulgaris, Bambusa tulda, Bambusa oldhamii, Dendrocalamus asper, Gigantochloa apus y Guadua angustifolia) fueron muestreadas de la colección de bambús tropicales del Tropical Agricultural Research Station (TARS-USDA), Mayagüez, Puerto Rico. Para las mismas se algunas propiedades físicas y mecánicas básicas incluyendo la densidad, contenido de humedad, el módulo de elasticidad, el esfuerzo último a compresión paralelo a la fibra, el esfuerzo último cortante paralelo a la fibra y el momento flector último. Además, se adjunta otros experimentos cortos enfocados en entender las influencias de factores físicos en el comportamiento mecánico del bambú y la evaluación en efectividad para ocho alternativas de soluciones preservantes. El rango de valores promedios obtenidos, dentro de todas las especies, para esfuerzos últimos en muestras húmedas fue de: compresión paralelo a la fibra 4.84 - 8.09 ksi (33.40 - 55.79 MPa), cortante paralelo a la fibra 0.87 - 1.27 ksi (5.93 - 8.77 MPa), flexión 8.62 - 17.17 ksi (59.47 - 117.54 MPa) y módulo de elasticidad 2,361 - 3,644 ksi (16.28 - 25.48 GPa). La comparación directa de estos valores con los recolectados de otras investigaciones presentan patrones de cercanía o similitud. En general, esta tesis permitió el desarrollo de las instalaciones del Laboratorio de Materiales y Estructuras del Departamento de Ingeniería Civil y Agrimensura de la Universidad de Puerto Rico, Recinto de Mayagüez, para ejecutar pruebas mecánicas de bambú, brindado oportunidades a investigaciones futuras. Por otro lado, este trabajo también sirvió como foco de inspiración para el desarrollo de otras actividades como clases, talleres, charlas comunitarias y colaboraciones, entre otras, con la finalidad de promover la investigación y desarrollo sustentable del bambú, particularmente en Puerto Rico.
  • Publication
    Computational study of foreshocks in the Burridge-Knopoff earthquake model using machine learning
    ( 2023-12-13) Ortega Chagueza, Jesus G. ; Ramos , Rafael A. ; College of Arts and Sciences - Sciences ; Vanacore, Elizabeth ; Santana, Samuel ; Department of Physics ; Almodovar, Israel
    The study of mechanical models of earthquake faults is important for understanding the different behaviors observed in real earthquakes. The model considered for this work was introduced by Burridge and Knopoff, consisting of blocks connected by linear springs in contact with a moving rough surface. A numerical simulation of the model was implemented, revealing a variety in event size that follows a power-law distribution. As the next step, a database of artificial earthquakes was created with the purpose of training an artificial neural network (ANN) model capable of estimating the magnitude of the events generated by the simulation. The ANN models show satisfactory results in estimating the magnitude of artificial seismic events; however, there are still significant aspects to be discovered before they can be effectively applied to real seismic events.
  • Publication
    Reproductive success and chicks diet of the Least Tern (Sternula antillarum) in the South-southwest of Puerto Rico
    ( 2023-12-11) Ramos Vazquez, Luis ; Puente-Rolón, Alberto R. ; College of Arts and Sciences - Sciences ; Tossas-Cavalliery, Adrianne ; Alfaro, Mónica ; Department of Biology ; Sánchez-Quintero, Dilsom
    The Least Tern (Sternula antillarum) is a small seabird widespread in North America that breeds in the Caribbean region. Although it is listed as a species of least concern, its population is decreasing in the eastern United States and the Caribbean. The breeding season ranges from mid-May to early August, and it prefers coastal habitats. However, there is a lack of information about breeding and diet in Puerto Rico. To fill this gap, I investigated the breeding biology of the Least Tern in the South-southwest of Puerto Rico. I monitored 222 nests across two colony sites in the South-southwest of Puerto Rico during the 2021 and 2022 breeding seasons. My study found that the breeding success of Least Terns in Puerto Rico is low, given predation and flooding. However, the Least Terns in both sites are improving their hatching success despite low fledgling and breeding success due to predation, human disturbance, and flooding. The Yellow-crowned Night-Heron (Nyctanassa violacea) and the Red-tailed boa (Boa constrictor), are new threats to the Least Terns on the Island. The study also found that Least Terns in the South-southwest of Puerto Rico nest in rocks and sand with debris but without vegetation at the nest. The main prey identified in the fecal samples was scaled sardines (Harengula jaguana) and silversides (Atheriniformes sp.), for Peñuelas and Cabo Rojo, respectively. Overall, my study provides critical new insights into the breeding biology of this tern species in Puerto Rico. These findings highlight the challenges that are facing this species and suggest areas where conservation efforts could be focused. Further studies are needed to understand better the impact of these challenges on breeding productivity and to develop conservation strategies to protect Least Terns in Puerto Rico.
  • Publication
    Design and optimization of puzzle-based storage systems with unidimensional movements
    ( 2023-12-14) Blanco Quintana, Andrés ; Carlo-Colón, Héctor J. ; College of Engineering ; Bartolomei-Suárez, Sonia M. ; Pagán-Parés, Omell ; Department of Industrial Engineering ; Rodríguez-Román, Daniel
    Puzzle-Based Storage Systems (PBS) are very high-density parts-to-person storage systems for unit loads. This type of system is composed of a grid with 𝑚 rows and 𝑛 columns. The grid is composed of cells that may carry loads on top of them. Retrieving a load from a PBS requires sequentially moving loads to cells without a load until the required load reaches the output point. Since loads need to be slid into cells without a load, these cells are commonly referred to as escorts. A paradigm for Puzzle-Based Storage Systems (PBS) is that all cells are designed with the capability to transport loads horizontally and vertically. This study challenges this paradigm by proposing unidimensional PBS (UPBS), where some cells are limited to transporting loads either horizontal or vertical movements. UPBS require a lower investment cost, compared to traditional PBS, at the expense of lower throughput capacity. This thesis introduces the concept of UPBS and presents a linear program (LP) formulation to find the optimal load retrieval path for a single load using a single escort in a UPBS. The LP is solved recursively to understand the cost-to-throughput tradeoffs of unidimensional designs for a 4×4 grid system. It is concluded that it is possible to design UPBS with 25% of the possible unidimensional cells, while reducing the throughput by approximately 10%. A multi-escort formulation for the single load problem is also proposed and used in combination with an existing PBS formulation to understand UPBS design tradeoffs for systems with multiple escorts and a single input/output point. It is concluded that UPBS can be designed such that the capital investment cost to throughput tradeoff is favorable when retrieving a single load. An existing decentralized PBS algorithm for retrieving multiple loads considering multiple input/output points was coded in Python and modified for UPBS. Upon proper validation of the code, it was used to develop managerial insights for designing UPBS. For UPBS systems with simultaneous retrievals, multiple escorts, and multiple I/O Points, the layout depends on the number of loads requested at the same time (i.e., WIP level). For low WIP levels, it is possible to design UPBS with 33.33% of unidimensional rows, which would have implications of a 9.82% increase in throughput and for medium WIP levels with 41.66% of unidimensional rows would have implications of a 9.29% increase in throughput. The increase of throughput is a consequence of the decentralized PBS algorithm forcing some unrequested loads out of the system to prevent gridlocks. Therefore, UPBS with single and multiple escorts can maintain their throughput, with a lower investment cost.