Texas A&M University-Kingsville: AKM Digital Repository
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A study of the bonded indebtedness of Robstown Independent School District
No full textThe minutes of the board of education of each independent school district in Texas must, according to state law, carry an annual resolution stating the amount of the tax rate for each hundred dollar valuation. The resolution must, also, give the division to be made of the tax rate between local maintenance and interest and seeking fund requirements. Upon the basis of this regulation school districts may allocate up to fifty percent of all local tax income to bond service requirements
Willacy County, Texas, second graders: a study of ages and achievements
No full textA federal court ruling to stop segregation of pupils of Spanish Culture was handed down in Austin on June 15, 1948. This caused the teachers of Anglo-culture children in the Rio Grande Valley of Texas, who were to teach Spanish-culture children for the first time, to make an urgent plea for help when school began last year, September 1948. They were pleading for help hints on how to teach, or "what to do with it" second and third grade classes consisting of both Anglo and Spanish-culture children because they had never had an opportunity
A case study: accounting system design and installation -- departmentalized, full-service retail hardware and appliance store
No full textThe business under examination is located in a town of 15,000 within less than an hour's drive of a semi metropolitan center. The immediate community depends almost entirely upon agriculture, its only major industry and principal source income. The store situated on a major highway in the downtown shopping center. The building, which covers one quarter of the city block, is occupied under a long-term lease and a part of it is subleased to another enterprise
Allied control machinery for Japan
No full textWhereas the was in the Pacific is, ipso facto, of no concern hope, certain arrangements made among the powers of the pacific looking towards the ultimate surrender of Japan set fourth principals which were supposed to be followed in the surrender and the subsequent occupation. First of these came at the Cario Conference of November 1943. The war, by this time, was showing signs of ultimate, though distant, victory for the allied powers concerned
A hierarchical design methodology for polygeneration microgrid deployment in medium-sized communities
No full textPower infrastructure must become greener, more efficient, resilient and reliable. The power grid must accommodate diverse sources of generation, allow consumer participation, maintain and restore power during man-made and natural disasters, provide high-quality power, all this, while being affordable, efficient, resilient and reliable. Of special interest is the community level, to assure comfort, health, and safety of final users. Microgrids can be a solution to achieve these goals. Here, we consider “polygeneration” microgrids; these advanced microgrids can deal with electricity but also with heat, cold, purified water, biofuels, and other products. In this work, we fill a literature gap by presenting a general framework for microgrid and polygeneration microgrid modeling, design and optimization in the context of community level. The problem is approached at three levels. Level One, the optimal planning and operation strategy of individual polygeneration microgrids. Optimal planning is achieved using particle swarm optimization to design systems that will reduce CO2 emissions, fuel consumption, and overall cost compared to a conventional system. A decision support system is implemented by comparing different operational strategies that will further improve performance on a day-ahead and hour-ahead perspective. Level Two, the optimal power trading method and interconnection configuration in networks of transactive microgrids and the utility grid that will minimize operational costs and assure system stability. A model of two interconnected microgrids and the utility grid is implemented, several cases combining three energy trading mechanisms and six interconnection configurations are tested. Controller parameters and operational costs are optimized for each case. Level Three, the effect of multiple interconnected microgrids embedded at the community level on improving overall voltage stability and cost. A model of two direct current (DC) microgrids and a DC community grid is implemented. High penetration of solar photovoltaic (PV) generation and several contingencies are modeled to prove that voltage stability and improved operational cost can be achieved. Results for level 1 show that optimally designed polygeneration microgrids can achieve a significant reduction of CO2 emissions, fuel consumption, and overall cost compared to a conventional system. A decision support system is implemented to choose the optimal operational strategy that will further improve savings. Results for level 2, show that interconnected microgrids can be optimized to improve operational cost and frequency stability. And, for level 3, interconnected microgrids embedded in a community can improve operational cost and voltage stability. This work addresses an important aspect of microgrid deployment. The intention is to integrate a multi-level framework to be used by stakeholders to aid in the planning and subsequent deployment of successful microgrids and polygeneration microgrids at the community level
Monitoring and modeling of VOC emissions near oil and gas production sites using a wireless sensor network
No full textEmissions of air pollutants such as volatile organic compounds (VOCs) from oil and gas extraction activities have become a big environmental concern for certain regions. The projected increase in future wells aggravates this concern. Continuous monitoring and understanding emissions from oil and gas extraction not only assist management to track and take action on operational issues but also provide valuable data for creating a more accurate emissions inventory that can be used to help make regulatory policies. Most previous studies focus on qualifying emissions based on limited field measurements, which may not be able to capture emission variations from the oil and gas sector. The goal of this research is to develop a low-cost, low-maintenance, and continuous monitoring technology to track long-term emissions from the oil and gas extraction process and apply the measured concentrations to estimate total emissions.
A wireless sensor network (WSN) technology was developed for continuous monitoring non-methane volatile organic compounds (NMVOCs) from oil and gas extraction activities. The wireless sensor network includes multiple photoionization detectors (PIDs) for data collecting and a central data hub for data transferring using Bluetooth and Internet. It integrates several open-source platforms and utilizes solar energy for operation. PIDs were co-located and compared with an Automated Gas Chromatography monitor in a monitoring site. No statistical difference was observed in measuring NMVOCs. WSN also passed regional severe weather test by exposing it to high ambient temperature of South Texas for three months. This low-cost technology meets the needs of continuous monitoring and can be used as alarms in managing facility safety.
To estimate emissions of NMVOCs, three individual field campaigns were conducted in Shape Ranch, Dimmit County, Texas using WSN. With measured concentrations of NMVOCs from the WSN, an air dispersion modeling and inverse dispersion technique was applied to estimate emissions from either a single source or multiple sources. The study indicated that WSN captured the emission variation which were compared with the estimate results by using emission factors method (AP-42), and emission estimated by AP-42 is 40 times more than the method presented in the dissertation. Moreover, the Monte Carlo (MC) simulation was used to quantify and identify the source of uncertainties associated with emission estimates. The wind factor was found to cause the largest uncertainty, contributing 50.5% of the total variation in emission estimates.
The wireless sensor network has been successfully developed and tested in collecting field NMVOCs data. This low-cost and low-maintenance emission-monitoring platform can help oil and gas extraction facilities provide early warnings of operational safety. Integrating WSN measurement and dispersion modeling allows in field emissions estimates from oil and gas extraction activities, which could make an important contribution to improving environmental policies
Estimation of dispersion index using auxiliary information
No full textIn this thesis, we consider the problem of estimating the dispersion index in the presence of auxiliary information. We proposed a naive estimator for the dispersion index, then derive the bias and the mean squared error expressions. In the presence of auxiliary information, we also proposed a ratio type estimator and a regression type estimator of the dispersion index. The expressions of bias and mean squared error are derived in each case. We then define a new measure of dispersion index using three quartiles of a study variable. Using the same three quartiles we also developed a new measure of empirical mode. Using these quartiles, we derive the bias and mean squared error. We develop a ratio type estimator and a regression type estimator and derive the bias and mean square error expressions, using an auxiliary variable. We investigated the performance through a simulation study. Applications of the proposed estimators to the available secondary real data sets are also investigated. SAS codes involved in the simulation studies and real data applications are also included
Influence of roads and landscape features on the spatial ecology and mortality of ocelots in South Texas
No full textUrban development is the leading cause of habitat loss, replacing natural areas with infrastructure and road networks. Roads can negatively impact wildlife populations through habitat fragmentation, decreased landscape connectivity, and wildlife-vehicle collisions. Ocelots (Leopardus pardalis) are a federally endangered felid, with the sole breeding populations in the United States restricted to the Lower Rio Grande Valley of South Texas, an area of extensive anthropogenic expansion. Vehicle collisions are the highest sources of mortality for ocelots in Texas. Mitigation strategies, such as wildlife crossing structures, have been implemented throughout South Texas in the last 3 decades to combat the negative effects of roads on the ocelot populations. However, there has only been 1 documented case of an ocelot using a road crossing structure. The goal of my project was to analyze ocelot landscape use and response to road networks to inform potential locations for future road crossing structures designed for ocelot recovery. I examined the landscape structure surrounding ocelot-vehicle collision sites to understand the relationship between the spatial structure of land cover and where ocelots are iv struck by vehicles. I also examined the landscape structure surrounding wildlife crossing structures implemented for ocelot use to understand potential reasons ocelots may not use the structures. Lastly, I evaluated the relationship between biological and road-related factors and ocelot mortality risk, to determine which factors contribute to the probability of mortality from vehicle collision. Results from this study will improve conservation efforts for the endangered ocelot by illustrating the need for strategies to mitigate vehicle collisions and improve landscape connectivity. These results can be used for the placement of future road crossing structures more likely to be used by ocelots
The effect of thermotherapy on Huanglongbing-affected citrus trees in Texas
No full textHuanglongbing (HLB) is a disease that severely affects citrus production worldwide and associated with the Gram-negative bacterium, ‘Candidatus Liberibacter asiaticus,’ (CLas). To mitigate the disease, chemical and heat therapies are currently being evaluated by citrus growers in Florida. However, these methods have not been tested in Texas citrus orchards. In this study, thermotherapy treatments were applied to HLB-affected citrus trees to evaluate tree recovery and assess their effect on CLas titers and other foliar diseases of citrus. Thermotherapy was applied on a 6-year old Rio Red grapefruit orchard with high HLB incidence using randomized split block design. Results show that thermotherapy did not reduce CLas titers in symptomatic leaves. However, randomly selected leaves decreased in CLas titers after heat treatment for several months and increased after 9 months post treatment. Thermotherapy treatments reduced the disease index and AUDPC of greasy spot in HLB positive trees, while melanose severity was not affected by treatments. Physiological measurements show that HLB positive trees treated with thermotherapy had smaller leaf area than untreated trees and treated HLB negative trees. Canopy growth was also negatively affected by thermotherapy, as treated trees showed 2% mean growth compared to untreated trees that had an average of 9% canopy growth (P= 0.0275). Bloom count was not affected by thermotherapy however fruit set was reduced in heat treated trees. Fruit yield was not affected by thermotherapy and it was significantly higher on HLB- negative trees compared to positive trees. Conversely, HLB affected trees had lower content of °Brix with a high acidity % as well as and the most fruit showing lopsided symptoms. Therefore, the application of thermotherapy was not deemed effective for HLB management in this region
The kinds and processes of mathematics a child needs to know in order to succeed in an eighth grade general science course
No full textFor the past ten years (1930-1939) the writer has been a teacher of eighth grade general science. During that time, observation had been made of difficulty with which pupils approach subject matter of mathematical nature. The following examples of mathematical situations that occurred in the writer’s classroom illustrate this difficulty