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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Uranium-234 in vadose zone and perched waters of the Apache Leap Tuff, Central Arizona

Hardin, Ernest Lauriston, January 1996 (has links) (PDF)
Thesis (Ph.D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 336-344).

Measurements of oxygen concentration and diffusion rate in soil

Willey, C. R. January 1964 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1964. / Typescript. Vita. Includes bibliographical references (leaves 54-57).

Evaluation of ambient and chilled aeration strategies to maintain the quality of stored grain in tropical climates and during summer in temperate climates

Morales Quiros, Alejandro January 1900 (has links)
Master of Science / Department of Grain Science and Industry / Carlos Campabadal Teran / The use of grain aeration as a tool to minimize post-harvest losses requires lower ambient temperature (≤ 20°C) and relative humidity (≤ 70%) conditions than what is usually available during the summer season in temperate climates and throughout the year in some tropical climate regions. Warm and moist conditions contribute to pest problems and increase dependence on chemical control for pest reduction as part of grain management strategies. The grain chilling technology is a non-chemical alternative to cool grain stored under high risk climatic conditions. For this research project, the grain chilling technology was tested in a 1,350-ton low moisture content wheat silo during the 2015 and 2016 summer harvests in Kansas. The grain temperature was lowered from a maximum of 39°C to a minimum of 17°C in less than 250 hours. The results showed that chilled grain maintained at temperatures under 20°C reduced the development rate of insect pests compared to grain stored at temperatures over 25°C and cooled with ambient aeration. However, the cost of grain chilling was calculated to be between 0.26 and 0.32 $/t higher than using ambient aeration. Through computer simulation it was possible to evaluate the performance of the grain chiller against four different ambient aeration strategies for paddy rice stored under the tropical climatic conditions of the North Pacific coast of Costa Rica. After six months of storage, the minimum grain temperature achieved through ambient aeration was 30.8°C using an aeration strategy based on a grain-ambient temperature differential greater than 10°C. Grain chilling lowered the average grain temperature from 35°C to below 15°C in 117 hours and the maximum average temperature it registered after six months of storage was 15.5°C. The economic evaluation of the simulated ambient aeration and chilling strategy determined that the operational costs of grain chilling were between 2 and 4 $/t lower than ambient aeration plus fumigation. However, the initial cost of the grain chiller made the net present cost (NPC) of the chilling strategy between 0.22 and 0.85 $/t higher than the cost of ambient aeration plus fumigation over a 10-year analysis. Several potential financial options were analyzed to make the grain chiller more economically feasible for a rice miller in Costa Rica. It was concluded that the grain chilling technology can reduce grain temperatures below 20°C in a relatively short period of time, which helps control insect populations and maintain grain quality during summer storage in temperate climates and in tropical climates. Utilizing grain chilling reduced operational costs between 78% and 88% when compared to using chemical control of pests. Additionally, it was determined that an initial cost of $74,700 for the grain chiller would require a 16% discount or at least 10,641 t to be chilled annually to make this technology viable for the Costa Rican rice milling industry. Leasing the grain chiller (ten equal payments of $10,926) or adding a premium sell price of 1 $/t to chilled rice would make this technology feasible compared to the traditional grain management strategies utilized in Costa Rica.

Some exceptional effects of aeration on corn bin wall stresses /

Risch, Eric January 1982 (has links)
No description available.

Investigation of the treatment of mixed tannery wastewater

Song, Zhi January 2000 (has links)
No description available.

Studies on a novel aerator for wastewater treatment

Guest, Adam Julian January 2000 (has links)
No description available.

Impact of Artificial Aeration on Nutrients in Small Eutrophic Lakes

Balangoda, Anusha January 2014 (has links)
Video summarizing Ph.D. dissertation for a non-specialist audience. / Civil and Environmental Engineering / College of Engineering

Evaluation of an extended aeration treatment plant

McCulloch, Gary Eugene, 1944- January 1970 (has links)
No description available.

Integrating an Intermittent Aerator for a Swine Wastewater Treatment System

Wang, Zhiyu 05 1900 (has links)
Integrating an intermittent aeration for the treatment of combined dilute and anaerobic digested swine wastewater in a field swine wastewater treatment system was investigated. Four operations models in term of ratio of aeration to no-aeration of 60:36, 5:1, 4:2 and 3:3 hour were evaluated. At the HRT of 3.2 days and ration of aeration to non-aeration of 3:3, the removal efficiency of BOD5, Total-N, TSS and Total-P of 98.0%, 92.4%, 95.6% and 59.4% could be achieved, respectively. The effluent quality of BOD5, NO3ˉ–N, NH4+–N and TSS concentrations were 35±12mg/l, 2.6±0.8 mg/l, 36±28 mg/l and 78±13 mg/l, respectively. The operational criteria were developed for integrating the intermittent aeration in the swine wastewater treatment system (including anaerobic reactors and sedimentation unit). Economical evaluation of the swine wastewater treatment system integrating the intermittent aeration unit was conducted. It was found that break even point was the operation of 166 pigs if the biogas and stabilized sludge were utilized. If the byproducts were not utilized, the cost of the treatment system are $12.30, $7.92, $7.21, $7.06 and $6.09 for the operation of 300, 1000, 2000, 3000 and 5000 pigs per year, respectively. Integrating the intermittent aeration unit in the swine waste treatment system provides the effective odor control, reduction of energy cost and treated wastewater reuse without creating the deterioration of environmental quality. / Thesis (M. S.)--University of Hawaii at Manoa, 1997. / Includes bibliographical references (leaves 172-180).UHM: Has both book and microform. / U.S Geological Survey/ Water Resource Research Institute (FY 95/96)

Adsorption of VOC vapors at the air-water interface in unsaturated media

Enright, Bryn Alison. January 1998 (has links) (PDF)
Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 100-102).

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