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Column flotation cells have become the most popular machine designed for industrial applications that require the separation and concentration of wanted or unwanted minerals from the rest material associated in a pulp. To achieve this process separation an air sparging device, which is required to produce bubbles in the flotation cell is required. In column flotation operations, Sparger sparging devices are employed in column flotation operations to generate small bubbles into the cell with the aim to carry the the desired mineral to the surface for later be recovered and proceeded. However, field studies suggest that air injector sparging systems are not always optimized. Two of the reasonsReasons that contributinge to the lack of optimization areis unfavorable state are: (i) ineffective internal design of the sparging system, and (ii) poor operation techniques employed inby the industrial processing industrial plants. The present project intends to better understand sparging performance into the column cell and how to optimize sparging systems more effectively. To achieve this end, With this in mind, data of for gas-water injection rate, froth addition, and inlet-pressure have been collected and analyzed. The This data not only will facilitate an insight of to better operational practices that plant operators can employ to improve column performance, but it also will make it possible to correct flaws in the design of the sparging systems currently used in column flotation operations. / Master of Science

This thesis presents the results of a study of the effect of variations of systemic parameters on the structural response of single degree of freedom systems subjected to Incremental Dynamic Analysis. The systemic parameters are mass, stiffness, damping, yield strength and geometric stiffness. Each of these parameters was varied one at a time while the other values were kept constant. For each variation of parameters a set of single-record IDA curves was obtained. Five to six ground motions were used for this study to generate the single-record IDA curves. These ground motions were scaled prior to their application on the structure. The scaling factor was based on the spectral acceleration at the fundamental frequency of the structure at 5% of critical damping. The scale factor is affected if the system parameters are changed. An important issue for this study was whether to persist with scaling corresponding to the median value from the range of the values of the parameter or to update the scaling according to the system. Based on some tests using both methods, the median scaling approach was found to be more suitable. The IDA curves for variation of parameters were then investigated to identify any trends that may help in qualitatively predicting the response of a system relative to another system. The response was measured by the peak displacement and the maximum base shear of the system. A clear trend was identified when the damping or the yield strength was varied. However, no definite trend was observed when the material stiffness or the geometric stiffness of the system was varied. / Master of Science

Second harmonic (SH) microscopy represents a powerful tool for the investigation of crystalline systems, such as ferroelectrics and their domain walls (DWs). Under the condition of normal dispersion, i.e., the refractive index at the SH wavelength is larger as compared to the refractive index at the fundamental wavelength, n(2ω) . n(ω), bulk crystals will generate no SH signal. Should the bulk, however, contain DWs, an appreciable SH signal will still be detectable at the location of DWs stemming from the Čerenkov mechanism. In this work, we demonstrate both how SH signals are generated in bulk media and how the Čerenkov mechanism can be inhibited by using anomalous dispersion, i.e., n(ω) . n(2ω). This allows us to quantitatively estimate the relative strength of the Čerenkov compared to other SH contrast mechanisms in DWs, such as the interference contrast. The results are in agreement with previous experiments based on the geometric separation of the signals. Due to the observed, strong Čerenkov contrast, such signal contributions may not be neglected in polarimetry studies of ferroelectric DWs in the future.

The Memphis, Tennessee National Weather Service (NWS) currently has issues with their atmospheric dispersion index (LVORI), and is looking for a new index that better represents smoke dispersion in their County Warning Area (CWA). Forecast soundings at hour 00 and hour 48 from the North American Mesoscale (NAM) model were collected at various locations in the southeastern United States. Using the data collected, a new index equation was developed. A bootstrapping analysis was performed to determine if the mean index number corresponding to low visibility was statistically significantly different and greater than the mean index number corresponding to high visibility for forecast hour 00 and hour 48. Based on the results of this study, the mean index number was greater for low visibility, but was not statistically significantly different for forecast hour 00. For forecast hour 48, the mean index number was greater and statistically significantly different for low visibility.

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