A radiative transfer model for a homogeneous plane parallel vegetative canopy is developed. A method to decompose and calculate the uncollided, once scattered, and multiply scattered radiation components is also presented based on the turbid medium approach. The new model accounts for the some effects exhibited only by homogenous vegetation canopies. This allows the simulation of the scattering processes within the plant canopy as a function of the traditional canopy architecture parameters such as leaf area index (LAI), leaf reflectance and transmittance, and also the canopy height and leaf size, stem etc... This model integrates two different approaches: the turbid medium approach and an approach that takes into account the finite size of the leaves. Furthermore, a state of the art leaf radiation transfer model (PROSPECT) is incorporated into the new model that provides leaf scattering properties as inputs (transmittance and reflectance vs. wavelength). Based on the proposed canopy model, a computer code in MATLAB was formulated using the discrete ordinates numerical method. This was used to calculate the bi-directional reflectance factor for a given geometry and a viewing angle from a plant canopy. The code for the new model is modular and very simple to use. The new model has been validated against other radiative transfer models, and compared with measured data. The results obtained using the model are in good agreement with the measured data.

Drip irrigation design is a multi-step routine that has to be carried out in a step by step fashion with each step covering a part of the design process. An expert system has been developed with a set of external programs to accomplish the drip system design. The expertise used in the present expert system knowledge base was induced from engineering handbooks and articles as well as personal consultations. The expert system has been developed in such a way that a variety of cases can be handled. In addition, to simulate the human expert, a new drip irrigation design evaluation factor has been introduced (Design Success Indicator, DSI) in order to estimate the system response on field depending on the confidence of data being used. The results are very promising with respect to the expertise used. However many parts of the knowledge-base have to be fine-tuned in order to reach a highly performing expert system.

<p> Slow sand filters (SSF) have been used to treat surface water to drinking water standards for over a century. Today many cities, including London still treat surface waters to drinking water standards, however because there are viruses that are not efficiently removed by a slow sand filter and are not killed by chlorine, communities have turned to the use of micro filtration and/or reverse osmosis to provide safe drinking water. These technologies are much more efficient if organics are removed and turbidity reduced to less than 1 Nephelometric Turbidity Units (NTU). The greenhouse industry is another potential user of slow sand filters. They are not able to recycle irrigation drainage water without it being treated to reduce bacteria, virus, and fungi. </p><p> The objective of this research was to develop management strategies for SSF that specifically meet the needs of entities using SSF for pretreatment of potable water or use in a greenhouse. This data was used to test a scour system that resulted in scouring 80 percent of the organic layer in the filter and suspending the solids for 40 minutes. A conceptual design was done for a full scale SSF that took advantage of the scour and suspension data to clean the SSF at the end of a run cycle. SSF were able to consistently produce water with a turbidity less than 1 (NTU) and with the infiltration capacity of 0.27 m³m^-2. For greenhouse effluent a 1,000 square meter greenhouse that is discharging 3,600 L d^-1 of drainage water would require a 12.6 m² SSF, and the SSF for the community requiring treatment of 4.7 million liters per day of raw water was 730 m². The innovative cleaning system based on an air/water jet was developed to clean the SSF. Experiments were run to determine the amount of time that the solids were suspended and a scour system developed to exceed these times. The entire time for cleaning and recovery of the SSF was an average of 118 minutes for the greenhouse system and 170 minutes for the SSF serving a small community.</p>

<p> The greenhouse industry is interested in light emitting diodes (LEDs) as a light source supplement to solar light to improve plant growth and development. Before LEDs can be adopted as supplemental light for greenhouse crops, plant responses to LED spectral quality need to be investigated. Tomato and cucumber seedlings were grown under different supplemental blue and red photon flux ratios (B:R ratios) under high (16-19 mol m^&ndash;2 d^&ndash;1) and low (5-9 mol m^&ndash;2 d^&ndash;1) solar daily light integrals (DLIs). The supplemental daily light integral was 3.6 mol m^&ndash;2 d^&ndash;1. A treatment without supplemental light served as a control. Both tomato and cucumber seedlings had increased growth rate and improved morphology when grown under the supplemental LED light compared to the control. However, no significant differences were observed for any growth and morphological parameters measured in this study between the different B:R ratios for both cucumber and tomato transplants under high DLI conditions. Cucumber seedlings showed a tendency to decrease dry mass, leaf number and leaf area under low DLI conditions with increasing B:R ratio. Tomato seedlings did not show any differences between the different B:R ratios under low DLI conditions. Seedlings growth and morphology under supplemental LED light were compared to those under supplemental high pressure sodium (HPS) light. Cucumber seedlings under supplemental HPS light had greater shoot dry mass than those under the supplemental red LED light. Tomato shoot dry mass showed no differences between the HPS and red LED supplemental light treatments. Cucumber seedlings were also grown under supplemental LED pulsed lighting and supplemental LED continuous lighting. Cucumber seedlings showed no differences in shoot dry mass and net photosynthetic rate between the treatments. Collectively, these studies concluded that red LED is preferred for supplemental lighting and the increase of blue light does not offer any benefits unless the efficiency of blue LEDs largely exceeds the red LEDs. The results of this research can be used for fixture development by LED manufactures and as a decision making tool for the adoption of supplemental LED lighting by greenhouse growers.</p>

Two depths (10 and 20 cm) of floating sphagnum peat covers were compared to uncovered swine slurries in storage, as a nitrogen conservation method. The test was repeated over three consecutive summers. / Following a nitrogen mass balance analysis, for the manure stored in tanks of limited diameter but full depth, the slurries covered with the two depths of peat conserved 60% and 76% of their nitrogen, while that uncovered conserved only 54%. / The sphagnum peat reduced manure evaporation during storage and helped conserve nitrogen during the tank mixing operation. / A drying temperature of 105$ sp circ$C gave the sphagnum peat moss the most hydrophobicity to keep it floating over liquid manures. The sphagnum peat conserved nitrogen by absorbing the manure moisture rather than by fixing the volatilized ammonia. / Applied to rye grass, the peat treated manure improved the nitrogen uptake efficiency by 140 190% and 190% to 340%, as opposed to untreated manure and chemical fertilizers, respectively.

<p> Ethanol and other biofuels from cellulosic feedstocks are currently the most promising candidates to replace a large fraction of gasoline consumption in the United States and reduce greenhouse gas emissions. Gaps in current approaches to estimating the net greenhouse gas emissions from second-generation biofuels may lead to underestimation of the carbon intensity of these fuels. Current life cycle assessment models of biofuels do not sufficiently account for biomass losses and emissions associated with the harvest and storage of biomass feedstocks, which can require additional fuel and materials use on the farm as well as reducing the effective yield of a crop at the biorefinery gate. The goal of this dissertation is to quantify the range of likely impacts of feedstock storage on the net greenhouse gas emissions from biofuel production. </p><p> A broad survey of published forage and bioenergy studies was used to assess the range of likely feedstock dry matter losses during storage by several methods. These loss distributions, as well as updated parameters for biomass harvesting processes and potential direct emissions of non-CO₂ greenhouse gases during biomass decomposition were incorporated into the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model to determine the effects on life cycle global warming impact. Methods for laboratory-scale storage experiments were developed using a variety of potential bioenergy feedstocks harvested at Purdue University. Experiments with corn stover and switchgrass under controlled temperature and moisture conditions were conducted to determine rates of dry matter loss and methane and nitrous oxide emissions during storage. </p><p> Results show that updating biofuels life cycle analysis models to include harvest and storage of biomass feedstocks can substantially increase net greenhouse gas emissions from 2.0&ndash;10.0 gCO₂e/MJ ethanol. Differences between storage methods are significant: materials use and direct emissions of methane may lead to greater emissions during wet storage, while covering dry bales reduced average emissions and variability. Both methane and nitrous oxide are produced during aerobic biomass storage at the laboratory scale, though at low rates which may not substantially affect the carbon intensity of cellulosic biofuels. </p><p> Incorporating harvest and storage parameters into biofuels life cycle assessment models significantly alters both point estimates and stochastic analyses of greenhouse gas emissions. While ethanol from cellulosic feedstocks still provides a greater than 60% reduction in greenhouse gases compared to gasoline, storage processes should be considered when assessing the extent to which biofuels reduce net fossil energy use and climate change emissions. </p>

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1110. Adviser: Vijay Singh. Includes bibliographical references (leaves 111-116) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Kentucky, 2005. / (UnM)AAI3198303. Source: Dissertation Abstracts International, Volume: 66-12, Section: B, page: 6754. Director: Richard S. Gates.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 3232. Adviser: Yuanhui Zhang. Includes bibliographical references (leaves 110-115) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6956. Adviser: Lei F. Tian. Includes bibliographical references (leaves 119-127) Available on microfilm from Pro Quest Information and Learning.