2017 MU theses - Access restricted to UM
Permanent URI for this collection
Browse
Recent Submissions
Item Experimental assessment of advanced thermal imaging for detecting voids in ducts(University of Missouri--Columbia, 2017) Dawson, James; Washer, Glenn A.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] This research will evaluate the ability of a transient based Infrared Thermography (IRT) technology called the Infrared Ultra Time Domain (IR-UTD) system to detect defects in Post Tensioned (PT) ducts. In recent years, there has been an increasing number of bridges in the National Bridge Inventory (NBI) constructed using PT concrete design. Post Tensioning is a design concept in which steel tendons are placed inside plastic or galvanized steel ducts that are embedded within the concrete itself. If not constructed properly, voids are created during the construction process. These voids allow water and chlorides to ingress into the ducts and cause the steel tendons to corrode. A PT specimen will be cast with embedded defects at known locations and exposed to diurnal heating and cooling cycles. The IR system will collect data while the specimen is fully exposed to the environment. Data will also be collected after an air controlled enclosure is constructed around the specimen to simulate the temperature gradient that the outer wall of a box girder bridge is subjected to. This research shows that in direct sunlight, the IR-UTD processing produced indications from implanted defects of varying sizes inside of a galvanized steel duct. Additionally, the effect from having air control on the inside of the structure didn't significantly affect the results. To obtain a full scope of the abilities of the IRT system, a procedure to properly insulate the specimen to prevent uneven thermal gradients will be necessary. Testing during the summer months where the sun is in the sky for a longer period would also be beneficial.Item Dynamic response of cold-formed steel roof trusses subject to blast load(University of Missouri--Columbia, 2017) Clayton, Gabriela Alexandria; Salim, Hani A., 1966-[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The popularity of cold-formed steel building components has seen rapid growth in recent years due to its low cost, high strength, and ability to accommodate restrictive design constraints. Despite its extensive use, blast design criteria do not exist for cold-formed steel roof components. Considerable damage sustained by roof members can lead to failure of the structure and detriment to the safety of its inhabitants. Thus, development of adequate design procedures preventing failure of cold-formed steel roof components subject to blast loading is needed. Identifying the behavior and response of cold-formed steel roof structures subject to blast loading is the first step in creating adequate design techniques. The research conducted utilizes experimental and numerical analysis. Experimental research is necessary to better understand the response of cold-formed steel trusses subject to blast loading. This portion of research is comprised of testing three small-scale cold-formed steel roof trusses. The response of trusses subject to loading is evaluated up to ultimate failure. Numerical analysis evaluates 28 roof beam elements subject to a calculated blast load and equivalent roof blast loads. While equivalent loading procedures ease computational effort, the accuracy of such methods remains unknown and must be evaluated. The results of experimental testing provided an understanding of the dynamic response of cold-formed steel trusses subject to blast load. This is a significant contribution as it provides a basis to create design methods for cold-formed steel roof components. The results of numerical analysis indicated that equivalent loading procedures result in significant error in the response of roof components subject to blast load. This finding is pertinent in design because it indicates correction factors should be developed to amend inaccuracies in current procedures. Both of these findings contribute to increasing the safety of building design.Item Oxidized mesoporous ZrO2/carbon composites for arsenic removal(University of Missouri--Columbia, 2017) Zhang, Lingxuan; Deng, Baolin[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] This study is mainly focused on the synthesis and characterization of oxidized mesoporous ZrO2/Carbon composites, determining the best air oxidation time, and comparing the adsorption performances of arsenate on oxidized mesoporous ZrO2/Carbon composites and unoxidized composites. The mesoporous ZrO2/Carbon composites were synthesized via a facile evaporation induced triconstituent co-assembly approach by using Pluronic F127 as a template and zirconium oxychloride octahydrate and resol as Zr and carbon sources, respectively(Li, Xu et al. 2010). The oxidized samples were produced by oxidation at 400[degrees]C in the presence of air. The oxidized composites were characterized by X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Preliminary experiments showed a relatively low adsorption capacity of unoxidized composites, while air oxidation could improve the arsenic adsorption performance by mesoporous ZrO2/Carbon composites. The best air oxidation time was then determined by investigating the adsorption of arsenic by samples oxidized for various time, tested at pH = 4.7 and an initial arsenic concentration of 50ppb. Experiments demonstrated that the best air oxidation time was 20min (OMZC-20) based on its ability to adsorb arsenate. Initial arsenate concentrations and pH values varied while the ionic strength was kept constant by adding NaNO3. The Freundlich model fitted experimental data better than the Langmuir and Temkin models. The optimal pH values for arsenate adsorption was 2-4, and the adsorption capacity decreased with increasing pH from neutral to alkaline values.Item Biochar and compost application effects on grapevine growth and physiology(University of Missouri--Columbia, 2017) Weber, Timothy D.; Kwasniewski, Misha T.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Biochar has the potential to be a local and renewable resource produced from waste byproducts that can replenish soils and build fertility. The objective of this research was to determine if biochar is a useful soil amendment in Missouri vineyards. Studies were conducted in 2015 and 2016 to investigate possible benefits of biochar, compost, and biochar mixed with compost at selected application rates to vineyard soils. Results indicate that the benefit of biochar and compost were rate dependent in the 2015 study. In this study, one-year-old 'Valvin Muscat' grapevines growing in a soilless media amended with [less than or equal to]70 % biochar resulted in reduced leaf number, area, and weight, shoot growth, and root weight. An overall reduction in biomass production and nutrient accumulation was observed when plants were grown soil amended with high rates of biochar. However, when the application rate was reduced, fewer differences were detected. In the 2016 study, soil fertility and water availability were not limiting, therefore, no significant benefit or reduction in plant growth and development of oneyear- old 'Norton' and 'Chardonel' grapevines were observed. Surface application of biochar may have minimal impact on grapevine growth and development in mid- Missouri.Item Uio-66 particles embedded PVDF hollow fiber membrane for arsenate removal(University of Missouri--Columbia, 2017) Yuan, Mengxi; Deng, Baolin[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Excessive arsenate in drinking water is a threat to human health. In this study, UiO-66 particles embedded PVDF hollow fiber membrane (HFM) was fabricated for the removal of arsenate from aqueous solutions. This study examined combining adsorption and membrane filtration for arsenate treatment, the results showed that the technology could remove arsenate efficiently. UiO-66 particles were synthesized first and evaluated by batch adsorption experiments including adsorption isotherm, pH effect and kinetics tests. The as-prepared UiO-66 particles had a BET surface area of 918 m2/g. The maximum adsorption capacity of UiO-66 was 267 mg/g at pH4.7, which was ranked at the top of all sorbents reported for arsenate removal. UiO-66 particles were active for arsenate in a wide pH range from 1 to 10, with the adsorption capacity reaching the highest at pH2.5. UiO-66 particles were then placed into PVDF HFM to treat solutions containing 100ppb of arsenate. As (V) removal performances were studied for 6 types of UiO-66 embedded HFM with different UiO-66 contents, and the filtration experiments were conducted at pH4.7 and a constant ionic strength of 0.05 mol/L controlled by NaNO3. Experiments demonstrated that the raw HFM with no UiO-66 particles could not remove arsenate from water, which was expected due to the large pores of HFM, but the adsorption capacity was increased significantly after the addition of UiO-66 particles. With a membrane surface area of 0.0045 m2, a maximum permeate volume of 34L could be obtained prior to arsenate breakthrough at 10ppb. The UiO-66 particles-embedded HFM was characterized by morphology, hydrophilicity, rejection, and ATR-FTIR.