Optimal Energy Management and Control of Microgrids in Modern Electrical Power Systems

Dissanayake Ralalage, Anushka Madushan Oklahoma State University ProQuest Dissertations & 2020 해외박사(DDOD)

Microgrids (MGs) are becoming more popular in modern electric power systems owing to their reliability, efficiency, and simplicity. The proportional-integral (PI) based droop control mechanism has been widely used in the MG control domain as the setpoint generator for the primary controller which has several drawbacks. In order to mitigate these issues, and to enhance the transient and steady-state operations in islanded MGs, advanced control and intelligent optimization methodologies are presented in this dissertation. First, to improve the existing PI-based droop relationship in DCMGs, a multi-objective optimization (MOO) based optimal droop coefficient computation method is proposed. Considering the system voltage regulation, system total loss minimization, and enhanced current sharing among the distributed generators (DGs), the Pareto optimal front is obtained using the Elitist non dominated sorting genetic algorithm (NSGA II). Then, a fuzzy membership function approach is introduced to extract the best compromise solution from the Pareto optimal front. The drawbacks of PI-based droop control cannot be entirely mitigated by tuning the droop gains. Hence, a droop free, approximate optimal feedback control strategy is proposed to optimally control DGs in islanded DCMGs. Further, to gain the fully optimal behavior, and to mitigate constant power load (CPL) instabilities, a decentralized optimal feedback control strategy is also introduced for the active loads (ALs) in the MG. In both algorithms, the approximate dynamic programming (ADP) method is employed to solve the constrained input infinite horizon optimal control problem by successive approximation of the value function via a linear in the parameter (LIP) neural network (NN). The NN weights are updated online by a concurrent reinforcement learning (RL) based tuning algorithm, and the convergence of the unknown weights to a neighborhood of the optimal weights is guaranteed without the persistence of excitation (PE). Finally, a local optimal control strategy is presented to path optimization of islanded ACMGs to enhance the transient operations while mitigating the voltage and frequency deviations caused by the traditional droop control. Optimal state and control transient trajectories in the d-q reference frame are obtained by Pontryagin’s minimum principle which drives each DG from a given initial condition to their steady-state manifold. Both simulation and experimental results are presented to validate the concepts.

Healthy Living intervention for female primary caregivers of infants and toddlers

Morgan, Kerry D Oklahoma State University ProQuest Dissertations & 2016 해외박사(DDOD)

Background: Obesity has emerged as a significant health issue among both adults and youth in the United States. Nationally, 1 in 12 children aged 2--5 years are obese. Common recommendations to counter obesity in children include dietary modifications, increased physical activity, and decreased sedentary time, including screen time. One avenue to influence these behavioral targets in infant and toddler children may be to influence parent behavior. Objective: The principal aim of the present study was to determine the effects of a Healthy Living intervention on female primary caregivers' fruit and vegetable consumption, sugar-sweetened beverage consumption, physical activity level, and television viewing time. The effects of the intervention on self-efficacy and anthropometric outcomes were also examined. Methods: A quantitative, quasi-experimental, pretest/posttest, attention-placebo comparison design was used to evaluate intervention effectiveness. The Healthy Living treatment condition was compared to an early childhood education attention-placebo comparison condition. The Transtheoretical Model (TTM) served as the guiding framework for Healthy Living intervention development and implementation. Community lay advisors recruited participants and also delivered the treatment and attention-placebo comparison conditions. A total of 82 female primary caregivers were recruited for participation; 58 completed both the pretest and posttest assessment (26 were in the treatment condition and 32 were in the attention-placebo comparison condition). Results: There were no statistically significant between-group differences for any of the behavioral outcomes, self-efficacy, or anthropometric outcomes. Regardless of condition, female primary caregivers' mean sugar-sweetened beverage calorie consumption, F(1, 53) = 6.62, p = .01, and mean body mass index, F(1, 43) = 4.06, p = .05, decreased significantly form pretest to posttest. Discussion: Although this investigation suggests the Healthy Living treatment condition was no more effective than the attention-placebo comparison condition, findings do support the utility of the community lay advisor approach in recruiting and retaining hard-to-reach participants. This approach may also enhance participant self-efficacy; however, additional research is needed to examine this relationship. Keywords: lay advisor, transtheoretical model, behavior change, self-efficacy, obesity.

Effects of Land Use and Management Practices on Grassland Butterfly Communities

Geest, Emily Altair Oklahoma State University ProQuest Dissertations & 2021 해외박사(DDOD)

Grassland butterflies are undergoing worldwide population declines due to habitat loss and degradation. Rangelands in the southern Great Plains; can provide habitat for grassland butterflies depending on management practices. As grasslands decline, grassland-dependent species, such as grassland butterflies, undergo widespread population losses. To manage remaining grasslands, patch-burn grazing, prescribed fire, and mowing/haying are commonly implemented management practices across the southern Great Plains. However, the impact of management on the butterfly communities is complex, and the effects of different management regimes on butterfly communities are not clear. I investigated the impact of time since prescribed fire and season of fire on butterfly communities in cattle-grazed rangelands in north-central Oklahoma. Species richness varied by time since fire and season of fire, with older spring-burned sites having the highest species richness. Diversity indices and evenness varied by treatment, with older spring-burned sites having the lowest evenness and inverse Simpson’s Diversity while recently spring-burned sites had the lowest Shannon-Wiener Diversity of all treatments. Patch-burn grazing creates a mosaic of successional vegetation stages which can benefit different butterfly species and support the overall community. To untangle the effects of variable management regimens and habitat characteristics on butterfly community composition and butterfly community traits, I conducted butterfly and flowering forb surveys at sites across north-central Oklahoma. A total of 942 butterflies were recorded across 39 species over two years, with community measures differing by site. Neither land use intensity nor habitat characteristics had measurable effects on overall butterfly community composition or butterfly community traits. This research adds to the growing body of literature on butterfly community ecology and highlights the need for further studies to understand what factors drive butterfly community patterns. Finally, I created ecological niche models for five Speyeria species of conservation interest by combining each species’ known occurrences with climate and environmental variables to identify important response variables and determine the potential distribution of suitable habitat for each species. Response variables differed among species, which highlights each species’ different climate and habitat needs. This demonstrates the value of citizen science and photo sharing websites for providing important data for evaluating species distributions.

Bermudagrass Characteristics under Simulated Sod Production and Athletic Field Paint Applications

Segars, Chrissie Ann Oklahoma State University ProQuest Dissertations & 2017 해외박사(DDOD)

Bermudagrass is arguably the most important turfgrass grown in the transition zone in the United States. It has a wide variety of uses and many characteristics desired by consumers. Learning to properly manage bermudagrass under a wide variety o.

Essays on the Rural Opioid Crisis

Meadowcroft, Devon P Oklahoma State University ProQuest Dissertations & 2019 해외박사(DDOD)

Rural areas in the U.S. have been notably affected by the opioid crisis, resulting in higher rates of opioid-related deaths and misuse than their urban counterparts. This dissertation assesses the effectiveness of existing strategies aimed at reducing opioid misuse, and also describes an Extension-led effort to engage rural communities struggling with this issue. The first study focuses on opioid treatment programs (OTPs) in the South census region. Through coarsened exact matching (CEM), the study determines if OTP presence is associated with reductions in the opioid-related death rate in counties nearby the OTP. Rural and urban counties are analyzed separately, to see if the results vary for these different types of areas. The findings of this study suggest that OTPs are not negatively associated with future opioid-related deaths, in either rural or urban counties. The second study examines prescription drug monitoring programs (PDMPs), which are statewide online programs that monitor controlled substance prescriptions. Multiple correspondence analysis is used to create a measure of a state's PDMP robustness. The aim of this study is to evaluate if states with more stringent PDMPs in place are associated with increased incidences of illicit opioid deaths, due to prescription opioids being more difficult to obtain in these areas. Results show that continuous measures of PDMP strength are not generally associated with the prescription opioid- or heroin-related death rate. Yet, one model does confirm the hypothesis that stricter PDMPs are related to more illicit opioid use. When the PDMP scores are broken into quartiles in the models, only the lowest quartile of scores (i.e. least stringent) is seen to have a negative association with overdose deaths. For the third study, a series of three community meetings were held in Ardmore, Oklahoma. Community stakeholders attended these meetings, and a variety of data collection techniques assessed where they would like to direct future resources aimed at reducing opioid misuse in their area. The participants noted that they would like funding to go towards increasing access to opioid treatment options, and to youth education programs in their community.

The Effects of Prescribed Fire on Black Bear Forage Availability, Resource Selection, and Distribution in the Interior Highlands

Yaklin, Danielle M Oklahoma State University ProQuest Dissertations & 2017 해외박사(DDOD)

Black bears (Ursus americanus) were extirpated from Oklahoma in the early 1900's but have recolonized the eastern part of the state since they were reintroduced into Arkansas in the 1950's and 1960's. Bears now occur in fragmented, human-dominated areas that are managed for human interests. Forest management practices such as prescribed fire have been shown to be beneficial for wildlife by opening up the canopy and allowing more light to penetrate to the understory, stimulating forage production. Because bears must gain substantial fat reserves to last through winter and are highly dependent on seasonal food sources, I investigated the effects of prescribed fire on the availability of key black bear forage items and subsequent bear movements and resource selection in the Ouachita Mountains of southeast Oklahoma. To determine whether prescribed fire positively or negatively affected common black bear forage items, I surveyed soft mast, ants, and hard mast within prescribed burn units in the Ouachita National Forest in Oklahoma between May 2014 and January 2017. I used GPS locations from 60 black bears collared between May 2014 and August 2016 in resource selection functions to determine if bears selected areas of a particular time since fire. Lastly, I used GPS locations from collared black bears in the Ozark and Ouachita Mountains of Oklahoma in ecological niche models to predict future range expansion westward into Oklahoma. Forage production was highly variable and species-specific. Soft mast was influenced by year, topography, land cover and prescribed fire, but ants and hard mast were not influenced by fire. Bears seemed to select burned areas with more soft mast, but that was variable by sample year. Bears selected hardwood-dominated forests more in autumn when hard mast was important in their diets. Niche models demonstrated bears used forests and higher elevations similarly to resource selection results. Bears have the potential to expand their range farther west in Oklahoma, although areas of expansion will be fragmented and likely have low population density.

Essays on Consumer Demand for Recreational Activities

Cha, Wonkyu Oklahoma State University ProQuest Dissertations & 2017 해외박사(DDOD)

The first essay presents research on paddlefish anglers' preferences for catch-and-release regulations in Oklahoma. Stated preference (SP) data from a choice experiment is used to identify the effect of a hypothetical catch-and-release regulatio. The second essay develops a site choice model to examine the risk preferences of recreational anglers, who may prefer sites with high catch rates but do not have perfect foresight about catch rates at any particular site. Risk preferences are im. The third essay examines the impact of perceptions of extreme weather events on outdoor recreation demand. Perceptions about weather condition are important determinants for outdoor recreation decisions because individual considers for both actu.

A Comparative Study of Oral Proficiency in Direct (OPI) and Semi-direct (VOCI) Testing Modes: Measures of Complexity, Accuracy, and Fluency

Alzahrani, Nawal Ali Oklahoma State University ProQuest Dissertations & 2020 해외박사(DDOD)

This study aims at comparing oral proficiency performance at two oral proficiency testing modes, namely Oral Proficiency Interview (OPI) and Video Oral Communication Instrument (VOCI) in terms of specific measures of complexity (length of ASUs, and MS-TTR), accuracy (error-free ASUs), and fluency (frequency of filled and silent pauses). It also examines the relation between task type and CAF measures in both testing modes. It further explores the test takers’ perceptions and preferences towards the direct testing mode (OPI) and the semi-direct testing mode (VOCI), and then compares those perceptions and preferences with their testing performance in terms of the CAF measures. In order to achieve the goals of this study, four instruments were used to collect the data (OPI, VOCI, online background survey, and interviews conducted in Arabic). Convenience sampling was used to recruit nine senior Saudi male students, majoring in different fields in Engineering at a South-Central University in the United States. OPIs and VOCIs responses were recorded, then manually transcribed using InqScribe software. Wilcoxon Signed Rank test reveals that while complexity measures did not show any statistically significant differences in both testing modes, accuracy (Error-free ASU) and fluency (Silent pauses) showed significant differences in the OPI and VOCI testing modes. It was also found that the narrative task impacted the MS-TTR in the VOCI testing mode and the number of silent pauses in the OPI testing mode. Participants reported a variety of positive and negative perceptions towards OPI and VOCI. This study further presents information about test takers’ experiences about both tests. It was also found that participants had a higher accuracy and fluency in the OPI testing that they claimed they felt more comfortable with. The current research suggests possible empirical and practical implications and some questions for future studies.

From soil ecology to human nutrtition: Crop symbiosis with arbuscular mycorrhizal fungi in agroecosystems

Cobb, Adam Benjamin Oklahoma State University ProQuest Dissertations & 2016 해외박사(DDOD)

The Green Revolution helped us reduce global poverty, hunger, and malnutrition over the past 30 years. My research is part of an emerging Brown Revolution that is unlocking the power of living soil to sustainability provide human needs. We are losing soil more quickly than it is being replenished---worldwide, an area of farmland the size of half an Oklahoma erodes away every year; however, arbuscular mycorrhizal (AM) fungi are microorganisms that can stabilize and enhance soil, while benefitting most of our crops with increased water and nutrients. A teacup of healthy soil contains enough AM fungi to stretch across 30 football fields from end to end, but some agricultural practices reduce the abundance of AM fungi on farms. These practices degrade soil stability and fertility over time, resulting in a waste of water, a waste of fertilizers, and environmental damage. My research seeks to harness the benefits of AM fungi for sustainable food production and nutrition. We focused on sorghum and cowpea, because they are important in many developing countries, but their efficiency and drought-tolerance also make them ideal for places like Oklahoma. In the greenhouse and field, we assessed differences in plant response to AM fungi to discover which crop genotypes are the most effective partners. Then we examined how that partnership affected agricultural efficiency and seed (grain) nutritional contents, such as protein, zinc, and iron. We also assessed the impact of alternative fertility amendments (biochar, worm compost, reduced commercial fertilizers) and farm management practices (intercropping) on AM abundance, crop yield, and nutrition. More AM responsive genotypes and alternative amendments were shown to increase yield and/or key nutritional contents. Nearly 1 out of every 3 people on this planet are malnourished, and they often need more dietary protein, zinc, and iron; therefore, our results indicate that AM fungi improve soil health and human health as well. Crop genetics, alternative soil amendments, and farm management can enhance the benefits of AM fungi, and we can utilize them to help us regenerate our soils and nourish our growing population.

Storage and Electronic Mold Odor Detection of Winter Canola Seed with Safety Implications for Quality Loss

Moore, Kevin Gerald Oklahoma State University ProQuest Dissertations & 2017 해외박사(DDOD)

Winter canola has seen increasing adoption as a rotational crop with small cereal grains in the southern United States. Considerable effort has been devoted to the development of new canola varieties suited to this region, but less effort has been placed on understanding issues related to post-harvest storage and handling of the crop. This study investigates three such issues. First, lining the inside of unaerated grain bins with polyethylene material in an attempt to improve storage quality in secondary storage facilities. There was not a significant difference between canola seed stored with and without the liner. If low quality grain bins must be used for short-term storage, the bottom of the bin can be lined with grain bag material for the purpose of sealing and moisture exclusion. Second, the development of a low-cost electronic nose capable of detecting mold in stored canola seed. This device was able to classify canola seed as moldy or clean with a 3% error rate. Third, measurement of the pressure on the torso of a grain entrapment victim in canola, corn, soybeans, and wheat to provide information to first responders and health professionals in the event of a grain storage accident. This pressure was found to range from 1.6 to 4.0 kPa (0.23 to 0.57 psi). This does not appear sufficient to limit respiration in an otherwise healthy adult male.