Master of Science / Department of Chemical Engineering / Keith Hohn / Acid catalysts have been shown to be very successful in the pretreatment of cellulosic biomass to improve glucose yield and improve overall yield of ethanol. This report presents the results of a techno-economic study that looks into the use of nanoscale magnetic solid acid catalysts for glucose production. Magnetic solid acid catalysts are an improvement over using diluted acid due to eliminating acid-waste generation and corrosion hazards. Their magnetic nature also allows them to be easily separated from reaction products by an external magnetic force. After the technology is analyzed, a series of unit operations is proposed to go from the laboratory scale to the industrial plant scale. The next step was to develop material and energy balances using HYSYS process simulation software. Capital and operating costs are estimated and all the information is combined into a discounted cash flow economic model. The economic portion of the report uses a probabilistic cost assessment. It is used to quantify the range of risks in the project from swings in feedstock costs, differences in yield from catalysts, and any other significant variables. Both capital costs (initial equipment & construction investment) and operating costs (feedstock supply, chemicals, and personnell) are included with ranges of error based on databases and expert opinion. This method of evaluating investment efficiency can be helpful for predicting the cost benefits of proposed future research. The yield and percent catalyst magnetically recovered is assumed based on laboratory research to simplify the model. A 2000 metric tons of biomass per day facility was analyzed. Using the magnetic solid acid catalyst technology, the capital costs are estimated to be $160 million and this technology saves around 10% of capital costs compared to ethanol plants that uses conventional acid hydrolysis. The yield of the magnetic solid acid catalysts should be around 75% to compete with existing ethanol technologies. The metric used for this report is the discount profitability index (DPI) which is the ratio of future cash flows divided by investment. A DPI “hurdle rate” of 1.3 is used, which is similar to industry economic metrics of projects that include new process plants. The calculated DPI for the project is 1.38 DPI which is higher than using conventional cellulose treatment technologies. The recommendation is continue to study this technology’s large scale applicability before attempting any plant pilot studies.

Master of Science / Department of Biological & Agricultural Engineering / James M. Steichen / Military maneuvers involve effectively moving soldiers and equipment across training lands, and this often involves crossing streams. Fording of streams by military vehicles poses a potential for degradation of stream habitats through change of bank angle or excess shear of stream banks and the resultant generation of excessive quantities of sediment, possibly exceeding Total Maximum Daily Loads (TMDL) limits for water quality downstream. This study examines the impact of low water fords on stability of six stream reaches at Fort Riley. Streams with constructed low water fords were mapped and classified according to Rosgen Stream Classification System (1996). Results indicate that some of these streams exhibit some level of instability, which includes bed form changes, accelerated stream bank erosion and backwater pool formation in the vicinity of stream crossings. Poorly constructed fords may act as dams disrupting the transport of sediment along the stream reaches, posing a potential shift in stream equilibrium. Another factor contributing to stream instability is sediment generated from upland areas and routed through approach roads leading to stream crossing sites. The sediment deposited into streams at these crossing locations is a water quality concern, and again poses the potential of disrupting stream equilibrium. Field observations indicate that poorly located stream crossings can alter the direction of stream flow, causing bank erosion on areas immediately below stream crossings. This demonstrates the importance of locating stream crossings on stable locations along a stream reach. Some of the stream reaches also show signs of success ional change. These stream changes have direct implications on the low water fords on Fort Riley. As a result of these stream changes, there will be need to constantly modify the designs and construction techniques of the low water fords in order to accommodate changes in stream dimensions, pattern and profile. Finally, criteria for site selection, design and construction of low water fords are discussed.

Master of Science / Department of Biological & Agricultural Engineering / Robert E. Wolf / Traditionally, growers spray uniform application of pesticides over the target area regardless of variations in pest infestations. In recent years, variable rate application (VRA) technologies have made it possible to apply pesticides in variable rates across the field. In pesticide application, nozzles play a vital role. In general, pesticides are applied using conventional nozzles. Most conventional nozzles vary flow rates only over a 2:1 range when operated within the recommended pressure range due to a fixed spray orifice. Conventional nozzles vary droplet sizes tremendously when there are speed and application rate changes which results in inefficient application. Conventional nozzles have limitations when used for VRA. A new nozzle called Varitarget nozzle (U.S. Patent No. 5,134,961) was developed and marketed by Bui, (2005) to overcome the limitations with conventional nozzles. Varitarget nozzles have a variable orifice that changes in size in response to pressure changes, allowing varying flow rates with a minimal change in droplet size. Laboratory tests and field tests were conducted to study the performance of Varitarget nozzle. Varitarget black/blue and clear/yellow caps were evaluated in this study. Lab studies were conducted to measure Varitarget characteristics compared to conventional nozzles. The flow rate ratios of Varitarget nozzle black and clear caps were 12:1 and 10:1 while the conventional nozzles produced flow rate ratios ranging from only 3:1 to 4:1. The measured flow rate of Varitarget nozzle black and clear caps was similar to that published by the manufacturer up to 40 psi and varied higher after 40 psi. Both Varitarget black and clear cap nozzle was within the standard VMD requirements until 40 psi and showed increasing trend while the conventional nozzles matched the standard VMD requirements. The VT black and clear cap nozzles showed better coverage at higher pressures when compared to conventional nozzles. CV values for VT black and clear capped nozzles were less than 10% which indicates capability of good uniform distribution. Spray angle of 110 degrees for VT black and clear capped nozzles was consistent over a range of pressures. Field studies were also conducted to compare the Varitarget to conventional nozzles. In the varying speed study, droplet size varied from 498 to 621 microns with a SD of 47.50 for VT black nozzle and 465 to 599 microns with a SD of 54.08 for VT clear cap nozzle as the speed varied from 4 to 12 mph. In the varying application rate study, The droplet size varied from 432 to 510 microns with a SD of 27.84 for VT black nozzle and 355 to 452 microns with a SD of 39.80 as the application rate varied from 4 to 12 GPA. In both studies, the observed pressure range required for spraying was minimum and varied slightly.

Master of Science / Department of Agronomy / Scott A. Staggenborg / Spatial variability in plant available water can be caused by uncontrollable factors such as topography and soil texture as well as controllable factors such as residue management. Research located on the High Plains evaluated the impact of wheat (Triticum aestivum L.) stubble height on snow catch, plant available water at seeding, and optimal corn seeding rates. Treatments consisted of stripper harvest height of 71 cm (28 in.), cut heights of 25 cm (10 in.), and 10 cm (4 in.) Measured snow depths were significantly different among treatments (p<0.0001) with equivalent precipitation of 5.77 (2.27), 3.25 (1.28), and 1.73 cm (0.68 in.) for the stripped, 25 cm, and 10 cm heights respectively. Available soil water at planting increased 24% as stubble height increased from 10 to 71 cm (4 to 28 in) in one year of the study. Two corn hybrids of varying maturity (97 and 108 days) were planted into the stubble treatments at seeding rates ranging from 2.47 to 5.43 plants m[superscript]-2 (10 to 22 000 plants ac[superscript]-1). In the dry year, the long season hybrid responded positively to increasing population in tall stubble and negatively in short stubble. Yield of the short season hybrid increased with increasing stubble height and was mostly unresponsive to population. Grain yields of both hybrids responded positively to increasing plant population in a wet year. Treatments also affected the yield components of yield plant[superscript]-1, kernel weight, and kernels plant[superscript]-1. Managing seeding rates for uncontrollable factors was attempted with small-plot and field scale research across 3 fields in northeast Kansas. A relationship between soil electro-conductivity (EC) and measured water holding capacity values was developed for one study field. This quadratic relationship was significant (p<0.0001) and explained variability in water holding capacity with respect to EC quite well (R[superscript]2=0.6239). Responses from small plots showed that sites differing in population response characteristics could be identified. Field scale data was used to derive a function describing optimal seeding rate with respect to soil EC. In the field under study, optimal seeding rates varied from 3.08 to 8.74 plants m[superscript]-2 (12 500 to 35 375 plants ac-1).

No description available.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Naiqian Zhang / Suspended sediment concentration (SSC) in water is one of the most important parameters to evaluate water quality. Monitoring SSC provides important information on determining sediment transport for soil erosion research and soil/water conservation practices. Sediment mass transported at a given time can be assessed by simultaneous SSC and water flow velocity measurements. Fouling, including bio-fouling, has damaging impact on optical SSC measurements over the long term. In this study, an inexpensive, real-time, self-cleaning, optical sediment and flow velocity sensor was developed. Laboratory experiments were conducted on a previously designed SSC sensor. A light modulation algorithm was designed to reduce the influence of ambient light, especially sunlight, on measurement accuracy. Statistical models to predict SSC based on measured light intensities were established and compared with neural network models. The statistical analysis showed that soil texture played an important role in SSC measurement accuracy while the designed sensor was capable of reducing the effect of water color on sensor performance. Neural-network models can further remove the influence of soil texture type on SSC measurement. The sensor design was simplified based on a stepwise selection analysis. Long-term field experiments were conducted in Kansas and Georgia to evaluate the sensor performance, the effect of fouling, including bio-fouling, on sensor lenses, and the effect of temperature on the measurement. Methods of removing the fouling effect through data correction were developed. Results indicated that the designed optical SSC sensor was capable of providing rapid response to SSC fluctuations in water flow. Temperature of the water body has an insignificant impact on SSC measurement. In order to reduce fouling, an air-blast cleaning mechanism was integrated into the optical sediment sensor. Laboratory experiments in a manually created fouling environment were conducted to observe the fouling process on sensor cases made of different materials, and to verify the effectiveness of air-blast cleaning in reducing fouling. Results indicated that air-blast cleaning mechanism was capable of reducing clay/silt fouling on sensor signals. The duration and frequency of air-blast cleaning can be determined and adjusted depending on actual field conditions. An air pressure drop test was conducted on the hose carrying pressurized air. Results showed negligible pressure drop.A flow velocity measurement function based on the cross-correlation principle was integrated into the optical sediment sensor. An experiment was conducted in laboratory to examine the sensor performance on velocity measurement using a closed circulation system. A solution of blue colorant, Brilliant Blue FCF, was used as an artificial source to absorb light emitted by LEDs in the sensor and the signal variation patterns were measured. The results indicated that the cross-correlation-based velocity sensor was capable of measuring water flow velocity within in a certain velocity range using the dye injection method.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Stacy L. Hutchinson / Precipitation impacts hydrologic structures, agricultural production, water resources management, and recreational activities, all of which significantly affect a state’s economy. Water control structure design is based on the maximum runoff rate resulting from storms with a specific return period and duration. The Rainfall Frequency Atlas (National Weather Service Technical Paper 40, 1961) (TP-40) provided statistical rainfall analysis as the basis for hydrologic structure design until the information was updated for Kansas in February 2013 (National Oceanic and Atmospheric Administration Atlas 14, volume 8) (Atlas-14). With growing concern about the effects of global climate change and predictions of more precipitation and extreme weather events, it is necessary to explore rainfall distribution patterns using the most current and complete data available. In this work, the changes in rainfall patterns were studied using the daily rainfall data from 23 stations in Kansas and 15 stations from adjacent states with daily rainfall data of 1890 through 2012. Analysis showed an increase in extreme precipitation events in Kansas with increase in magnitude from the northwest to southeast part of the state. A comparison of results of the TP-40 analysis to period 1980–2009, showed that approximately 84% of the state had an increase in short-term rainfall event magnitudes. In addition, trend analyzes on the total annual rainfall indicated a gradual increase at 21 out of 23 stations, including eight statistically significant trends. A change-point analysis detected a significant sudden change at twelve stations as early as 1940 and as recently as 1980. The increasing trend, particularly after the significant change-points, is useful in updating water management plans and can assist with agricultural production decisions such as crop selection and new plant variety development. A comparison between 10-yr, 24-hr storms from TP-40 and Atlas-14 indicated a change of -12% to 5% in Kansas. However, the number of exceedances from the 10-yr, 1-, 2-, 3-, 4-, 7-, and 10-day storms demonstrated a tendency towards more exceedances, particularly in the last five decades. Results of this study are useful for hydrologic structure design and water resources management in order to prevent accepting additional risk of failure because of the current changing climate.

Master of Science / Department of Biological & Agricultural Engineering / Gary A. Clark / This report presents the methods to determine the minimum number of collectors to accurately measure the coefficient of uniformity and the average depth of applied water from fixed plate and moving plate center pivot sprinkler irrigation systems. This research conducted an uniformity analysis and an average depth analysis. In the uniformity analysis, catch can collected data from center pivot system tests were divided into base sets of 60 data points. Each base set was further divided into subsets of 30 data points each. T-tests were used to compare the CU values from the base data sets with CU values from each of the subsets. In the average depth analysis, center pivot system catch can data were divided into base sets with 20 data points. Each base data set was divided into 19 subsets. The 1st subset was generated by removing an exterior data point from the base set which was identified by number 1. The 2nd subset was generated by removing other exterior data point (identified by number 20) from the previously generated subset (1st subset). In this manner, a total of 19 subsets for each base set were generated by removing an exterior point from each previous subset. The percent difference (change) in average depth of each subset from the value of the average depth of the base set was calculated. The percent difference in average depth was then plotted against the associated number of collectors. Both analyses documented that a decrease in the number of collectors from the original density of collectors is acceptable to determine the uniformity and averaged depth of applied water from center pivot spans. Results from the uniformity analysis demonstrated that 20 collectors were as effective as 60 collectors to quantify the uniformity of a system. The depth analysis showed that 9 to 12 collectors may be needed to measure the average depth of a system (or a portion of a system) to within 5% to 7.5% of the true value.

Doctor of Philosophy / Department of Biological and Agricultural Engineering / Ronaldo G. Maghirang / Emission of particulate matter (PM) and various gases from open-lot beef cattle feedlots is becoming a concern because of the adverse effects on human health and the environment; however, scientific information on feedlot emissions is limited. This research was conducted to estimate emission rates of PM[subscript]10 from large cattle feedlots. Specific objectives were to: (1) determine feedlot PM[subscript]10 emission rates by reverse dispersion modeling using AERMOD; (2) compare AERMOD and WindTrax in terms of their predicted concentrations and back-calculated PM[subscript]10 emission rates; (3) examine the sensitivity of both AERMOD and WindTrax to changes in meteorological parameters, source location, and receptor location; (4) determine feedlot PM[subscript]10 emission rates using the flux-gradient technique; and (5) compare AERMOD and computational fluid dynamics (CFD) in simulating particulate dispersion from an area source. PM[subscript]10 emission rates from two cattle feedlots in Kansas were determined by reverse dispersion modeling with AERMOD using PM[subscript]10 concentration and meteorological measurements over a 2-yr period. PM[subscript]10 emission rates for these feedlots varied seasonally, with overall medians of 1.60 and 1.10 g /m[superscript]2 -day. Warm and prolonged dry periods had significantly higher PM emissions compared to cold periods. Results also showed that the PM[subscript]10 emissions had a diurnal trend; highest PM[subscript]10 emission rates were observed during the afternoon and early evening periods. Using particulate concentration and meteorological measurements from a third cattle feedlot, PM[subscript]10 emission rates were back-calculated with AERMOD and WindTrax. Higher PM[subscript]10 emission rates were calculated by AERMOD, but their resulting PM[subscript]10 emission rates were highly linear (R[superscript]2 > 0.88). As such, development of conversion factors between these two models is feasible. AERMOD and WindTrax were also compared based on their sensitivity to changes in meteorological parameters and source locations. In general, AERMOD calculated lower concentrations than WindTrax; however, the two models responded similarly to changes in wind speed, surface roughness, atmospheric stability, and source and receptor locations. The flux-gradient technique also estimated PM[subscript]10 emission rates at the third cattle feedlot. Analyses of PM[subscript]10 emission rates and meteorological parameters indicated that PM[subscript]10 emissions at the feedlot were influenced by friction velocity, sensible heat flux, temperature, and surface roughness. Based on pen surface water content measurements, a water content of at least 20% (wet basis) significantly lowered PM[subscript]10 emissions at the feedlot. The dispersion of particulate from a simulated feedlot pen was predicted using CFD turbulence model ([kappa]-[epsilon] model) and AERMOD. Compared to CFD, AERMOD responded differently to wind speed setting, and was not able to provide detailed vertical concentration profiles such that the vertical concentration gradients at the first few meters from the ground were negligible. This demonstrates some limitations of AERMOD in simulating dispersion for area sources such as cattle feedlots and suggests the need to further evaluate its performance for area source modeling.

Doctor of Philosophy / Department of Agronomy / P.V. Vara Prasad / Agriculture is the largest (90%) consumer of all fresh water in the world. The consumptive use of water by vegetation represented by the process evapotranspiration (ET) has a vital role in the dynamics of water, carbon and energy fluxes of the biosphere. Consequently, mapping ET is essential for making water a sustainable resource and also for monitoring ecosystem response to water stress and changing climate. Over the past three decades, numerous thermal remote sensing based ET mapping algorithms were developed and these have brought a significant theoretical and technical advancement in the spatial modeling of ET. Though these algorithms provided a robust, economical, and efficient tool for ET estimations at field and regional scales, yet the uncertainties in flux estimations were large, making evaluation a difficult task. The main objective of this study was to evaluate and improve the performance of widely used remote sensing based energy balance models, namely: the Surface Energy Balance Algorithm for Land (SEBAL), Mapping Evapotranspiration at high Resolution and with Internalized Calibration (METRIC), and Surface Energy Balance System (SEBS). Data used in this study was collected as part of a multi-disciplinary and multi-institutional field campaign BEAREX (Bushland Evapotranspiration and Agricultural Remote Sensing Experiment) that was conducted during 2007 and 2008 summer cropping seasons at the USDA-ARS Conservation and Production Research Laboratory (CPRL) in Bushland, Texas. Seventeen high resolution remote sensing images taken from multispectral sensors onboard aircraft and field measurements of the agro-meteorological variables from the campaign were used for model evaluation and improvement. Overall relative error measured in terms of mean absolute percent difference (MAPD) for instantaneous ET (mm h[superscript]-[superscript]1) were 22.7%, 23.2%, and 12.6% for SEBAL, METRIC, and SEBS, respectively. SEBAL and METRIC performances for irrigated fields representing higher ET with limited or no water stress and complete ground cover surfaces were markedly better than that for dryland fields representing lesser ET and greater soil water deficits with sparser vegetation cover. SEBS algorithm performed equally well for both irrigated and dryland conditions but required accurate air temperature data. Overall, this study provides new insights into the performance of three widely used thermal remote sensing based algorithms for estimating ET and proposed modifications to improve the accuracy of estimated ET for efficient management of water resources.