<p>PARANDEKAR, AMEY, VIJAY. Development of a Decision Support Framework for Integrated Watershed Water Quality Management and a Generic Genetic Algorithm Based Optimizer. (Under the direction of Dr. S. Ranji Ranjithan.)The watershed management approach is a framework for addressing water quality problems at a watershed scale in an integrated manner that considers many conflicting issues including cost, environmental impact and equity in evaluating alternative control strategies. This framework enhances the capabilities of current environmental analysis frameworks by the inclusion of additional systems analytic tools such as optimization algorithms that enable efficient search for cost effective control strategies and uncertainty analysis procedures that estimate the reliability in achieving water quality targets. Traditional optimization procedures impose severe restrictions in using complex nonlinear environmental processes within a systematic search. Hence, genetic algorithms (GAs), a class of general, probabilistic, heuristic, global, search procedures, are used. Current implementation of this framework is coupled with US EPA's BASINS software system. A component of the current research is also the development of GA object classes and optimization model classes for generic use. A graphical user interface allows users to formulate mathematical programming problems and solve them using GA methodology. This set of GA object and the user interface classes together comprise the Generic Genetic Algorithm Based Optimizer (GeGAOpt), which is demonstrated through applications in solving interactively several unconstrained as well as constrained function optimization problems.Design of these systems is based on object oriented paradigm and current software engineering practices such as object oriented analysis (OOA) and object oriented design (OOD). The development follows the waterfall model for software development. The Unified Modeling Language (UML) is used for the design. The implementation is carried out using the JavaTM programming environment<P>

<p>Akunuri, Naveen Venkata. Modeling the Performance, Emissions, and Costs of Texaco Gasifier-Based Integrated Gasification Combined Cycle Systems. (Under the guidance of Dr. H. Christopher Frey)Integrated Gasification Combined Cycle (IGCC) systems are an advanced power generation concept with the flexibility to use coal, heavy oils, petroleum coke, biomass, and waste fuels to produce electric power as a primary product. IGCC systems typically produce sulfur as a byproduct. IGCC systems are characterized by high thermal efficiencies and lower environmental emissions than conventional pulverized coal-fired plants. This study deals with the development and application of new systems models for estimating the performance, emissions, and cost of entrained-flow gasification-based power generation systems, including characterization of uncertainty in the estimates. The study focuses on modeling and assessment of three Texaco gasifier-based systems using ASPEN, a steady-state chemical process simulator. The first model is a coal-fueled IGCC system with a radiant and convective high temperature gas cooling design. The second and third models use a total quench high temperature gas cooling design with one of them using coal as fuel and the other using heavy residual oil as fuel. ASPEN-based performance models were developed for all three cases by substantially modifying a performance model previously developed by the U.S Department of Energy's Federal Energy Technology Center. New models for auxiliary power loads, emissions, and capital, annual, and levelized costs were developed for all three systems. The system models incorporate details regarding key process areas, such as mass and energy balances for the gas turbine and gasifier. The gas turbine process area performance model was calibrated to published data for operation on natural gas and also to data for operation on syngas. Example case studies were done on each of the IGCC system models and the results obtained were compared with each other. The models developed captured the critical interactions between the various process areas of the IGCC systems. The radiant and convective-based system has higher plant thermal efficiency of 39.4 percent, higher total capital cost of $/kW 1732, and higher cost of electricity of 50.88 mills/kWh than the total quench based-system models. The coal-fueled total quench model has lower plant efficiency of 35.0 percent when compared to that of 39.3 percent of the heavy residual oil-fueled total quench-based system model. However, the total capital cost of $/kW 1540 and cost of electricity of 47.67. mills/kWh of the former are higher when compared to those of the latter which are $/kW 1129 and 26.96 mills/kWh respectively. Since the IGCC systems are in the early stages of development, there are inherent uncertainties in the performance and cost parameters. Probabilistic performance models were developed for each of the IGCC systems using a probabilistic modeling capability previously developed for ASPEN. Probabilistic analysis provides a systematic framework for the evaluation of technological risks such as possibility of poor performance, high emissions, and high costs compared to more conventional technologies. The probabilistic analysis techniques were applied to case studies to evaluate and identify the key uncertainties in the inputs of the IGCC system models. The probabilistic analysis indicated that the range of the plant thermal efficiency of the radiant and convective coal-fueled model (38.0 - 39.5 percent) and that of the total quench heavy residual oil-fueled (37.9 - 39.5 percent) is higher than that of the total quench coal-fueled model (33.5 - 35.1 percent). However, the range of cost of electricity of radiant and convective coal-fueled model (45.4 - 55.6 mills/kWh) and that of total quench coal-fueled model (46.5 - 51.9 mills/kWh) are significantly higher than the range of cost of electricity of the total quench heavy residual oil-fueled model (27.0 - 32.2 mills/kWh) The probabilistic analysis reduced the total number of uncertainties from 40 to 16 in the coal-fueled cases and to 12 in the heavy residual oil-fueled case. The uncertainties in costs can be further reduced by providing detailed cost estimates and the need for the same has to be evaluated. The models can be utilized as benchmarks for comparison with more advanced power generation technologies.<P>

<p>Vaswani, Sudeep. Development of Models for Calculating the Life Cycle Inventory of Methanol by Liquid Phase and Conventional Production Processes. (Under the direction of Drs. Morton A. Barlaz and H. Christopher Frey).This study deals with the development of an ASPEN PLUS process model for the liquid phase methanol (LPMEOH) process,which is in the demonstration phase at Eastman Chemical Company, TN. The model will ultimately be integrated with MSW gasification model being modeled separately and used inan integrated gasification combined cycle (IGCC) system to co-produce methanol and power from syngas obtained from MSWgasification. The LPMEOH process uses syngas as a startingmaterial for methanol production. Model results for anexample case are presented and the life cycle inventory (LCI) of methanol has been calculated starting from syngas. When methanol is produced from the LPMEOH process, its production by conventional processes is avoided. Thus, an EXCEL spreadsheet model of methanol production using conventional process has also been developed. This model calculates the LCI of methanol from conventional process which is used to calculate the emissions avoided per kg ofmethanol produced by the LPMEOH process. For LPMEOH process model, it is found that the performance of the model is dependent on syngas conversion in methanol reactor. Syngas conversion is a function of reactor pressure, syngas space velocity in methanol reactor, molar ratio of recycle gases to fresh syngas feed, and H2/CO molar ratio in syngas feed. The syngas composition mainly depends on the source from which it is obtained (e.g. coal gasification, MSW gasification). LPMEOH process model has the capability to process syngas of varying compositions.Sensitivity analysis of LPMEOH process model has been presented. Based on the sensitivity analysis, it is shown that for syngas compositions limited in hydrogen content, the reactor pressure of or higher than 750 psig must be used. Further it is shown that recycling the unreacted gases has an advantage of more methanol production compared to the case with no recycle. It is also shown that the syngas feed with low H2/CO ratio has lower methanol production than syngas with higher H2/CO ratio. It therefore recommended that the syngas with low H2/CO ratio be adjusted via water-gas shift reaction such that the H2/CO ratio increases thereby resulting in a higher methanol production. It is also learnt that net steam demand in the LPMEOH process increases as the syngas becomes limited in its hydrogen content. This is expected to have some implications when the LPMEOH process is combined with an IGCC system. The LCI of methanol produced by LPMEOH process varies widely with change in syngas composition and process conditions such as reactor pressure, space velocity in methanol reactor, and recycle ratio. The main contribution to the LCI occurs from the combustion of purge gases to produce steam in a boiler. The steam generated offsets the emissions from other contributors of the LCI. The sensitivity analysis of the LCI of methanol production from LPMEOH reveals that the methanol LCI is quite sensitive to the changes in syngas composition, reactor pressure, syngas space velocity and the recycle ratio.The sensitivity analysis of conventional methanol production has also been discussed. It is found that the LCI of conventional process is not very sensitive to changes in natural gas composition, which is used as a raw material for methanol production. The change in syngas conversion in methanol reactor also does not cause the overall LCI of methanol to change significantly.The ultimate objective of the study is to compare the LCI of methanol produced by conventional process with that by LPMEOH process to determine if there is any advantage to methanol production by using LPMEOH technology on syngas derived from MSW gasification. The effect of an LPMEOH process on a gasification system would be an incremental increase in fuel use. Because of the incremental fuel use there would be an increase in elemental sulfur recovered, slag production, and some pollutant emissions. However, an overall LCI of methanol for LPMEOH process would require the calculation of the LCI associated with gasification.<P>

<p>Yellow warning signs are an important and abundant type of traffic control device. Improving warning signs could be a cost-effective countermeasure at hazardous locations, especially rural locations where approximately 61% of the Nation's traffic fatalities occur. The use of fluorescent yellow sheeting in place of standard yellow sheeting provides a method to increase the conspicuity of the traffic sign while conforming to the guidelines specified by the Manual of Uniform Traffic Control Devices. The 3M Corporation, and later other companies, developed a long-lasting fluorescent yellow retroreflective sign. Although the properties of the fluorescent yellow sheeting indicate that the conspicuity of the signs is much higher, the increased conspicuity ultimately must prompt a change in motorist behavior for highway safety to be improved. Therefore, the purpose was this research was to evaluate the effectiveness of fluorescent yellow warning signs in improving highway safety at hazardous locations. A before and after study used surrogate measures to evaluate the safety effectiveness of replacing existing yellow warning signs (engineer or high intensity grade) with fluorescent yellow warning signs (diamond grade) at seven hazardous locations. The results of this effort indicate that fluorescent yellow warning signs increased the safety at four of the seven sites by providing a more conspicuous warning to motorists. However, since surrogate measures were used, the actual collision savings are unknown.<P>

<p>Evolutionary algorithms are becoming increasingly valuable in solving large-scale, realistic engineering problems. Most of these problems deal with sufficiently complex issues that typically conflict with each other, thus requiring multi objective (MO) analyses to assist in identifying compromise solutions. The focus of this paper is to develop and test a new multi objective evolutionary algorithm (MOEA). The new procedure, Noninferior Surface Tracing Evolutionary Algorithm (NSTEA), builds upon two fundamental concepts that are established in the mathematical programming literature for MO analysis. Implicit implementation of Pareto optimality and beneficial seeding of initial population are instrumental in the improved performance. NSTEA was evaluated by solving a suite of test problems reported in the MOEA literature. Performance with respect to accuracy, coverage, and spread of noninferior solutions generated by NSTEA is evaluated and compared with those of solutions generated by four other MOEAs that are widely accepted. Also, in some cases, comparisons are made with noninferior sets generated using mathematical programming techniques. Overall, NSTEA performs relatively better than the other MOEAs when tested on these problems. Application and performance evaluation of NSTEA in solving a real-world MO engineering optimization problem was also conducted. In comparison to published mathematical programming-based noninferior solutions, the NSTEA solutions performed well. In summary, this paper contributes to the MOEA literature by presenting NSTEA as a good alternative evolutionary algorithm-based multi objective method that is relatively simple to implement and to incorporate into existing implementations of evolutionary algorithm-based optimization procedures. <P>

<p>Seismic building codes, such as the Uniform Building Code (UBC) do not allow the equivalent lateral force (ELF) procedure to be used for structures with vertical irregularities. The UBC defines a structure to be irregular based on the ratio of magnitudes of either strength, stiffness, mass, setback or offset of one floor to that of an adjacent floor. The criteria defining the limits of irregularity are somewhat arbitrary, but are introduced in the code to provide unambiguous, enforceable provisions. The purpose of this study is to quantify the definition of irregular structures for four different vertical irregularities - stiffness, strength, mass and nonstructural masonry infills. A total of 87 building structures with interstory stiffness and strength ratios ranging from 0.09 to 1.89 and 0.27 to 1.07, respectively, and mass ratios of 1.0, 2.5, and 5.0 are considered for a detailed parametric study. The lateral force resisting systems (LFRS) considered are special moment resisting frames and shear walls. These LFRS's are designed based on the forces obtained from the equivalent lateral force procedure. An ELF) analysis. Finally, nonlinear dynamic analysis is performed in order to assess the seismic performance of these buildings. The results show that the restrictions on the applicability of the equivalent lateral force procedure are unnecessarily conservative for irregular structures. Most structures considered in this study, designed on the basis of the ELF approach, perform reasonably well. In some cases, however, there is an initiation of an undesirable collapse mechanism. It is recommended that capacity based criteria in the design phase be appropriately used in the vicinity of the irregularity in order to ensure desired performance and behavior.<P>

<p>The rocking response of rigid bodies with rectangular footprint, freely standing on a horizontal rigid plane is studied analytically. Rigid bodies are subjected to simulated single component of horizontal earthquake time histories. The effect of the baseline correction, applied to simulated excitations, on the rocking response is first examined. The sensitiveness of rocking motion to the details of simulated earthquakes and the geometric properties of rigid bodies (i.e., slenderness ratio and sizeparameter) as well as the coefficient of restitution is investigated. Because of the demonstrated sensitivity of rocking response of rigid bodies to these factors, prediction of rocking stability must be made in the framework of probability theory. Therefore, using a large number of simulated earthquakes, the effects of duration and shape of intensity function of simulated earthquakes on the overturning probability of rigid bodies are next studied. In the case when a rigid body is placed on any floor of a building, the corresponding overturning probability is compared to that of a body placed on theground. For this purpose, several shear frames with fundamental natural period of vibration ranging from 0.5 sec(stiff) to 2.0 sec (flexible) are employed. Finally, the viability of the energy balance equation which was introduced by Housner in 1963 (The behavior of inverted pendulum structures during earthquakes, Bulletin of Seismological Society of America, 53, 2, 403-417) and widelyused by the nuclear power industry to estimate the rocking stability of rigid bodies is evaluated. <P>

<p>MEHTA, RINAV C. Comparison of Refuse Decomposition in the Presence and Absence of Leachate Recirculation at the Yolo County, California Test Cells. (Under the direction of Morton A. Barlaz.)A side by side comparison of two 8,000-metric ton test cells, one operated with (enhanced) and one without (control) leachate recirculation, was performed to evaluate the effects of leachate recirculation on refuse decomposition at Yolo County, CA. After about three years of operation, refuse was excavated in three borings of the enhanced cell (E1, E2 and E3) and two borings in the control cell (C1 and C2). The objective of this study was to present a comparison of test cell performance with respect to moisture content, settlement, methane production and solids decomposition. Refuse moisture content data show that leachate recirculation resulted in an increase in refuse moisture content, but also show that the refuse in the enhanced cell was not uniformly wet. The average moisture content in E1, E2 and E3 was 38.8, 31.7 and 34.8%, respectively, while the average moisture content in C1 and C2 was 14.6 and 19.2%, respectively. The extent of decomposition was determined by the biochemical methane potential (BMP) and the ratio of cellulose plus hemicellulose to lignin ((C+H)/L). BMP analysis showed the average methane potential in the enhanced and control cells to be 24.0 and 30.9 mL CH4/dry-gm, respectively, and the (C+H)/L of 1.09 and 1.44. These data correlates well with the measured methane production in the enhanced and control cell of 54 and 26 L CH4/wet-kg, respectively. Thus, laboratory and field data shows more decomposition in the enhanced cell relative to the control cell. While the overall averages may not appear significantly different, a closer look at the performance of E1 shows a difference in both moisture content and solids decomposition when compared to the control cell. Hence, the extent of decomposition varies within the enhanced cell. The sampling program conducted for the Yolo County test cells, in concert with data on settlement, methane production and the volume of liquid actually recycled, represents perhaps the most complete set of data available to date on a field-scale leachate recirculation landfill.<P>

<p>ROOKER, ALEXANDRIA PETTWAY. A Critical Evaluation of Factors Required to Terminate the Post-closure Monitoring Period at Solid Waste Landfills. (Under the direction of Dr. Morton Barlaz).The objective of this research is to identify and evaluate parameters that could be useful for defining the end of the post-closure monitoring period, or that time at which the landfill is stable with respect to environmental emissions. Parameters evaluated in the report include leachate composition, leachate production, and gas production. In addition, the evaluation of leachate composition and quantity is combined to evaluate surface water impacts associated with the release of leachate to surface water. To determine if a landfill has reached stability, the following data are needed: the concentrations of ammonia and BOD in the leachate, leachate production rates, and gas production rates. In order for the landfill to be declared stable, the leachate should not deplete oxygen resources, exert toxicity, or increase eutrophication if it is released to surface water. In addition, gas production rates should be low enough so that their emission does not represent a significant release of a greenhouse gas or cause an odor nuisance or explosion hazard. Ultimately, the technical criteria for landfill stability evaluated in this research should be applied to a full-scale landfill to test the usefulness of the proposed approach. <P>

<p>ABSTRACTMURRAY, THOMAS LANG. Application of the Water Quality Management Decision Support System (WQMDSS) in an Illustrative Watershed Management Study (Under the direction of Dr. S. Ranjithan.)Development of total maximum daily loads (TMDLs) for critical pollutants in impaired watersheds is becoming a standard approach in environmental management. This requires the identification of future loading of contributing pollutants, and the development of a plan to allocate the necessary reductions among the point and nonpoint sources in the watershed to achieve this loading. To support water quality model-based TMDL development, US EPA has released the modeling framework BASINS-Better Assessment Science Integrating Point and Nonpoint Source, which incorporates several watershed water quality models within a GIS-based data management system. Current capabilities of BASINS enable simulation of watershed water quality associated with a TMDL, thus supporting TMDL development via a trial-and-error approach. The limitations of the trial-and-error approach are addressed via systematic search procedures implemented within the Water Quality Management Decision Support System (WQMDSS) that is designed to aid stakeholders and decision-makers efficiently identify TMDLs. The focus of the research presented in this paper is to demonstrate the applicability of WQMDSS in developing TMDLs for a realistic illustrative case study. Using the data for the Suwanee Creek Watershed in Georgia, which underwent a recent TMDL study, a series of illustrative scenarios are examined to consider varying target total suspended solids (TSS) loading rates, as well as different instream water quality parameters. The instream water quality is estimated using a calibrated HSPF model. Future land use development plans, with and without consideration of riparian buffer strips for nonpoint source control, to meet instream water quality goals are identified. Through this illustrative study, a range of uses of WQMDSS in watershed-scale TMDL development is demonstrated.<P>