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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 80-88). Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Includes autobiographical sketch of author. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 176-179).

Nitrogen-based fertilizer industry in United States is undergoing major changes the demand for which is primarily driven by agriculture. Traditionally, this industry sources anhydrous ammonia through imports from Canada and U.S.-Gulf, the latter comprises bulk of imports, or produces domestically to be supplied as is or converted into urea or UAN variations of nitrogen-based fertilizer with various combinations with other minerals. With change in composition of crops and increasing acreage of crops that are fertilizer intensive, there is an increased demand for nitrogen-based fertilizer in order to promote foliar growth as a standalone form, for example Urea, or in combination, for example Di-ammonium phosphate (DAP). Second compelling reason for change in industry is reduction in prices of natural-gas, in part due to oil exploration, that makes it cheaper to produce anhydrous ammonia domestically. Anhydrous ammonia is perquisite for making other types of nitrogen-based fertilizer and highly energy intensive. Thus, lower natural-gas prices provide incentive for domestic firms to either expand existing fertilizer plants or opens up the possibility of new entrants. Many companies/firms have recently announced their plans to expand existing plants or open new units, exerting competitive pressure on an industry that already has lot of surplus capacity but highly competitive in terms of production costs and technology used. It is to be noted that natural-gas prices are volatile; therefore, any commitment to expand or open new plant is subject to volatility in demand, natural-gas prices, and import price of fertilizers. The purpose of this dissertation is to analyze spatial competition among U.S. nitrogen-based fertilizer plants and their respective market boundaries. This dissertation also derives the structure of the supply chain for nitrogen-based fertilizer in the United States (at macro level); and the stochastic spatial-optimization model to account for risk in random variables. Locational information is used to account for spatial nature of problem, and linear and mixed-integer based optimization techniques are applied to arrive at current and most likely future cases. Combination of linear optimization, and mixed-integer, and geographical information systems helps in determining regional areas where competition is expected to be ruinous and most intense; and provide insights on viability of newly announced fertilizer plants that are most likely to be successful and significantly impact the structure of overall supply chain. / Upper Great Plains Transportation Institute (UGPTI)

O fosfogesso, também denominado gesso agrícola, sub produto das industrias de fertilizantes fosfatados, pode ser utilizado como condicionador do solo devido a sua capacidade de proporcionar melhorias ao sistema solo-planta. No entanto, este resíduo concentra os radionuclídeos das séries do U e Th, presentes na rocha fosfatada usada como matéria prima, que podem impactar o meio ambiente. Com a finalidade de se verificar a concentração dos radionuclídeos biodisponíveis , foram analisadas amostras de fosfogesso e de fertilizantes fosfatados monoamônio fosfato e fertilizante superfosfato triplo, de duas procedências nacionais. A determinação da concentração de 226Ra, 228Ra e 210Pb se iniciou com a análise por espectrometria gama. Em seguida as amostras foram submetidas a um processo de extração branda com solução de EDTA-NH4 (0,05M) para que então o material lixiviado fosse analisado por meio de contagem alfa e beta total em detector proporcional de fluxo gasoso. Foram obtidos valores médios de extração de 1,6% - 1,7% para 210Pb, 0,5% - 1,4% para o 226Ra e 0,1% - 1,0% para o 228Ra nas amostras de fosfogesso. A baixa porcentagem de extração obtida para os radionuclídeos pode ser explicada tendo-se em vista que a solubilidade do fosfogesso variou de 7,7% a 16%. Para os fertilizantes fosfatados do tipo monoamônio fosfato os valores médios de extração foram inferiores a 26% para o 226Ra, inferiores a 10% para o 228Ra e inferiores a 10% para o 210Pb. Apesar da solubilidade da ordem de 77% dos fertilizantes fosfatados do tipo monoamônio fosfato, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. Para os fertilizantes fosfatados do tipo superfosfato triplo os valores médios de extração foram de 2,3% para o 226Ra, 1,2% para o 228Ra e 11,3% para o 210Pb. Mesmo com a solubilidade de 66% os fertilizantes fosfatados do tipo superfosfato triplo, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. / Phosphogypsum, also called gypsum, by-product of the phosphate fertilizer industry, can be used as soil conditioner since it provides improvements in the soil-plant system. However, this by-product concentrates radionuclides of the U and Th series, present in the phosphate rock used as raw material, which can impact the environment. In order to study the bioavailability of radionuclides, samples of phosphogypsum and phosphate fertilizers (monoammonium phosphate and triple superphosphate) were analyzed. The concentration of 226Ra, 228Ra and 210Pb were determined by gamma spectrometry. The samples were leached with a mild EDTA-NH4 (0,05M) solution and the radionuclides present in the final solution were determined by total alpha and beta counting on a gas flow proportional counter. The percentage of extraction varied from 1.6% to 1.7% for 210Pb, from 0.5% to 1.4% for 226Ra and from 0.1% to 1.0% for the 228Ra in phosphogypsum samples. The low percentage of extraction obtained for the radionuclides can be partly explained by the low solubility of phosphogypsum, which ranged from 7.7% to 16%. For the monoammonium phosphate samples the percentage of extraction were less than 26% for 226Ra, less than 10% for 228Ra and less than 10% for 210Pb. In spite of the high solubility of 77% of monoammonium phosphate in the EDTA-NH4 (0,05M) solution, low concentrations of radionuclides were observed in the extracted solution. For the triple superphosphate samples, the percentage of extraction was 2.3% for 226Ra, 1.2% for 228Ra and 11.3% for 210Pb. In spite of the high solubility of 66% of triple superphosphate in the EDTA-NH4 solution, low concentrations of radionuclides were observed in the extracted solution.

O fosfogesso, também denominado gesso agrícola, sub produto das industrias de fertilizantes fosfatados, pode ser utilizado como condicionador do solo devido a sua capacidade de proporcionar melhorias ao sistema solo-planta. No entanto, este resíduo concentra os radionuclídeos das séries do U e Th, presentes na rocha fosfatada usada como matéria prima, que podem impactar o meio ambiente. Com a finalidade de se verificar a concentração dos radionuclídeos biodisponíveis , foram analisadas amostras de fosfogesso e de fertilizantes fosfatados monoamônio fosfato e fertilizante superfosfato triplo, de duas procedências nacionais. A determinação da concentração de 226Ra, 228Ra e 210Pb se iniciou com a análise por espectrometria gama. Em seguida as amostras foram submetidas a um processo de extração branda com solução de EDTA-NH4 (0,05M) para que então o material lixiviado fosse analisado por meio de contagem alfa e beta total em detector proporcional de fluxo gasoso. Foram obtidos valores médios de extração de 1,6% - 1,7% para 210Pb, 0,5% - 1,4% para o 226Ra e 0,1% - 1,0% para o 228Ra nas amostras de fosfogesso. A baixa porcentagem de extração obtida para os radionuclídeos pode ser explicada tendo-se em vista que a solubilidade do fosfogesso variou de 7,7% a 16%. Para os fertilizantes fosfatados do tipo monoamônio fosfato os valores médios de extração foram inferiores a 26% para o 226Ra, inferiores a 10% para o 228Ra e inferiores a 10% para o 210Pb. Apesar da solubilidade da ordem de 77% dos fertilizantes fosfatados do tipo monoamônio fosfato, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. Para os fertilizantes fosfatados do tipo superfosfato triplo os valores médios de extração foram de 2,3% para o 226Ra, 1,2% para o 228Ra e 11,3% para o 210Pb. Mesmo com a solubilidade de 66% os fertilizantes fosfatados do tipo superfosfato triplo, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. / Phosphogypsum, also called gypsum, by-product of the phosphate fertilizer industry, can be used as soil conditioner since it provides improvements in the soil-plant system. However, this by-product concentrates radionuclides of the U and Th series, present in the phosphate rock used as raw material, which can impact the environment. In order to study the bioavailability of radionuclides, samples of phosphogypsum and phosphate fertilizers (monoammonium phosphate and triple superphosphate) were analyzed. The concentration of 226Ra, 228Ra and 210Pb were determined by gamma spectrometry. The samples were leached with a mild EDTA-NH4 (0,05M) solution and the radionuclides present in the final solution were determined by total alpha and beta counting on a gas flow proportional counter. The percentage of extraction varied from 1.6% to 1.7% for 210Pb, from 0.5% to 1.4% for 226Ra and from 0.1% to 1.0% for the 228Ra in phosphogypsum samples. The low percentage of extraction obtained for the radionuclides can be partly explained by the low solubility of phosphogypsum, which ranged from 7.7% to 16%. For the monoammonium phosphate samples the percentage of extraction were less than 26% for 226Ra, less than 10% for 228Ra and less than 10% for 210Pb. In spite of the high solubility of 77% of monoammonium phosphate in the EDTA-NH4 (0,05M) solution, low concentrations of radionuclides were observed in the extracted solution. For the triple superphosphate samples, the percentage of extraction was 2.3% for 226Ra, 1.2% for 228Ra and 11.3% for 210Pb. In spite of the high solubility of 66% of triple superphosphate in the EDTA-NH4 solution, low concentrations of radionuclides were observed in the extracted solution.

Identifying the determinants of compensation is important from employee and firm financial perspectives. This analysis examines the compensation of three different skill level categories - managerial, specialized, and general. The types of compensation examined include salaries, bonuses, benefits, and total compensation. Neoclassical theory is represented in the models by net return, managerialist theory by annual sales volume and form of ownership, and human capital theory by both education after high school and agribusiness work experience. Also controlled for in the models are the potential effect of salary on bonuses and benefits. Major findings include that annual sales volume, education after high school, and agribusiness work experience are the important determinants of salaries and total compensation. Bonuses for managers tend to increase with annual sales volume, and bonuses for employees in specialized and general skill level categories tend to be lower for those employed by cooperatives. Benefits tend to increase with salary. From the employee’s perspective, these findings indicate that, in order to maximize salary and total compensation, employees should seek employment in larger firms, attend college, and gain work experience. To decrease the variability of compensation associated with a high reliance on bonuses, specialized and general skill level employees may want to seek employment in a cooperative. Employees should realize that increases in benefits are linked to increases in salaries. From the firm’s perspective, smaller firms need to recognize that larger firms provide higher compensation. Hence, smaller firms may have to offer other amenities to attract, retain, and motivate employees. To attain more educated and experienced employees, firms will have to provide higher compensation. Cooperatives desiring performance oriented employees may have to alter their compensation packages to include higher bonuses. / Master of Science

Made available in DSpace on 2014-10-09T12:49:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:13Z (GMT). No. of bitstreams: 1 09824.pdf: 13805608 bytes, checksum: bb156d35d4219c1080d090fad1bf255b (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:99/06952-4

Made available in DSpace on 2014-10-09T12:49:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:13Z (GMT). No. of bitstreams: 1 09824.pdf: 13805608 bytes, checksum: bb156d35d4219c1080d090fad1bf255b (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:99/06952-4