Comparison of low-temperature co-fired ceramic and direct bonded copper for single ended primary inductance topology

This work examines the thermal dissipation characteristics of Low-Temperature Co-fired Ceramic (LTCC) and Direct Bonded Copper (DBC) with the implementation of a Single Ended Primary Inductance Converter (SEPIC) topology. The advantages and disadvantages of the two substrates will be explored in addition to a description of the design and control of the SEPIC. It will be shown that the DBC implementation is superior with regards to thermal dissipation, but that LTCC has advantages in high- density packaging, RF applications, and embedded components. These substrates and converters provide many advantages in industrial applications that include automotive and grid level implementations. Additional comments about best practices in the fabrication and design process are also included

Consumer-Driven Nutrient Recycling in Arctic Alaskan Lakes: Controls, Importance for Primary Productivity, and Influence on Nutirient Limitation

In lakes, fish and zooplankton can be both sources and sinks of nitrogen (N) and phosphorus (P) through the consumption of organic N and P, and subsequent excretion of bioavailable inorganic forms. These source/sink dynamics, known as consumer-driven nutrient recycling (CNR), may, in turn, control the availability of potentially limiting nutrients for algal primary production. In this dissertation I investigate the importance and controls of CNR as a source of inorganic N and P for primary production (Chapter 2). I then examine zooplankton CNR as a mechanism for increasing nutrient mean resident time (MRT) in the mixed layer of lakes (Chapter 3). Finally, I assess whether zooplankton communities dominated by different taxa can affect N versus P deficient conditions for phytoplankton production through differential N and P recycling rates (Chapter 4). Direct excretion of N and P by fish communities was modest in arctic lakes, and accounted for \u3c 4 % of the N and P required for primary production. Recycling of N and P by zooplankton communities was relatively high, and the fraction of algal N and P demand supplied by zooplankton CNR ranged from 4 - 90% for N and 7 - 107% for P. MRT of 15N, measured in the mixed layer of an arctic lake, was ~16 days, compared to 14 days predicted by a ecosystem model simulation with zooplankton N recycling and 8 days in a model simulation where zooplankton N recycling was absent. The 75% increase in N MRT between model simulations with and without zooplankton recycling suggests that zooplankton N recycling is an important mechanism for retaining N in lake ecosystems. I observed relatively high negative correlations between precipitation and phytoplankton N (r = -0.33) and P (r = -0.30) deficiencies. I also observed a significant positive correlation (r = 0.42, p = 0.03) between zooplankton communities with higher copepod biomass, relative to cladoceran biomass, and phytoplankton N-deficient conditions. These results suggest that when precipitation is high N and P deficiency is low in the phytoplankton. When precipitation is low, however, zooplankton communities composed primarily of copepods contribute to N-deficient conditions for phytoplankton production

The Influence of Soil Properties on Marsh Edge Erosion

Coastal Louisiana exhibits some of the highest rates of land conversion to open water in the world. This is most apparent in Terrebonne Bay, Barataria Bay, and Breton Sound (Couvillion et. al, 2011). The hypothesis is made that locally generated wind waves are responsible for the observed land loss. Recent research has attempted to relate the marsh edge erosion rate to wave energy flux density. Under the appropriate assumptions, this relationship is modeled reasonably well by a linear relationship between erosion rate and wave energy flux. Such a model is a valuable tool for coastal resource management. A deficiency of some of the proposed models is the exclusion of the marsh\u27s resistivity to erosion or, generally speaking, its strength. Marsh edge strength is a complex function of abiotic, biotic, and geochemical factors. A plausible assumption however is that geotechnical soil properties form a governing set of parameters with respect to erosion. The inclusion of spatially varying, site-specific soil properties in addition to the hydrodynamic driving force is then a logical step towards improving any model of marsh edge erosion. A parametric wave generation model is validated with an existing, observed wave record and a state-of-the-art numerical model. The parametric model is used to calculate wave energy flux at the marsh edge study sites in Terrebonne Bay, LA over 9 years. A key subset of soil parameters is identified from an extensive geotechnical and geological data set. The geotechnical data set was derived from a related field campaign in the Mississippi river delta\u27s coastal region which has a simimlar age and sediment source. The distribution of a proposed influential soil property in marsh edge strength (undrained shear strength) is used to demonstrate the site-specific differences in the relationship between observed marsh edge erosion and modeled wave energy flux density. Recommendations for the future success of modeling marsh edge erosion in the Mississippi river delta region are provided based on the applicability and suitability of the soil property framework and the method of modeling wave energy flux in Terrebonne Bay

Increasing Retention Rates for South Hall Residency

Stephen F. Austin State University\u27s Residence Life Department aims to improve resident retention in South Hall through renovation and interior design. By improving the spaces meant for student use, we hope to increase the involvement and comfort of the residents. The existing structure was not designed for today\u27s amenities and accessibility standards. By enlarging doorways, adding an elevator, and de-compartmentalizing the community spaces, the building becomes much more accessible to people with disabilities. These open spaces also fit into the contemporary styles of living and promote interaction between the residents and other occupants

Comparison of low-temperature co-fired ceramic and direct bonded copper for single ended primary inductance topology

This work examines the thermal dissipation characteristics of Low-Temperature Co-fired Ceramic (LTCC) and Direct Bonded Copper (DBC) with the implementation of a Single Ended Primary Inductance Converter (SEPIC) topology. The advantages and disadvantages of the two substrates will be explored in addition to a description of the design and control of the SEPIC. It will be shown that the DBC implementation is superior with regards to thermal dissipation, but that LTCC has advantages in high- density packaging, RF applications, and embedded components. These substrates and converters provide many advantages in industrial applications that include automotive and grid level implementations. Additional comments about best practices in the fabrication and design process are also included

The Bell Academy: A Bridge Semester Where Engineering Students Transform Into Student Engineers Who Thrive In Industry Placements

Iron Range Engineering is an innovative learning program using project-based and work-based pedagogies. The Bell Academy (BA) is a semester-long bridge experience between the first two years of STEM foundation and the final two years spent in full-time industry co-op placements. The curriculum within the academy is delivered within three domains: technical, design, and professional. The transformation to thriving as a student engineer in an industry placement is intentionally embedded in each stage of the program as students develop higher levels of self-awareness, professional responsibility, and self-directedness. Students not only gain technical engineering knowledge, but also apply that knowledge within team-based, ill-structured design projects, acting as engineering consultants to industry clients. Technical learning is delivered in one-credit modules, which supports both the development of the individual as a student engineer and the execution of the project. Professional competencies are learned in-situ as teams encounter natural struggles. Development is supported through workshops, which cover topics such as conflict management, leadership, technical writing, data science, public speaking, inclusive action, etc. Through iterative assignments and practice, such as resume development, negotiation, and interviewing, students develop a skills portfolio to identify and acquire a position to begin and maintain their career. Through more than a decade of implementation, several unique learning strategies have been developed and refined. The paper will briefly describe the model used and provide the strategies as potential tools for adaptation and implementation in engineering programs worldwide