Master of Science / Department of Industrial and Manufacturing Systems Engineering / Todd Easton / Integer Programming is used to solve numerous optimization problems. This class of mathematical models aims to maximize or minimize a cost function restricted to some constraints and the solution must be integer. One class of widely studied Integer Program (IP) is the Multiple Knapsack Problem (MKP). Unfortunately, both IPs and MKPs are NP-hard, potentially requiring an exponential time to solve these problems. Utilization of cutting planes is one common method to improve the solution time of IPs. A cutting plane is a valid inequality that cuts off a portion of the linear relaxation space. This thesis presents a new class of cutting planes referred to as merged knapsack cover inequalities (MKCI). These valid inequalities combine information from a cover inequality with a knapsack constraint to generate stronger inequalities. Merged knapsack cover inequalities are generated by the Merging Knapsack Cover Algorithm (MKCA), which runs in linear time. These inequalities may be improved by the Exact Improvement Through Dynamic Programming Algorithm (EITDPA) in order to make them stronger inequalities. Theoretical results have demonstrated that this new class of cutting planes may cut off some space of the linear relaxation region. A computational study was performed to determine whether implementation of merged knapsack cover inequalities is computationally effective. Results demonstrated that MKCIs decrease solution time an average of 8% and decrease the number of ticks in CPLEX, a commercial IP solver, approximately 4% when implemented in appropriate instances.

Master of Agribusiness / Department of Agricultural Economics / John A. Fox / The cost of wheat is the largest input cost for a flour mill, and as a result, profitability in wheat flour milling is determined in large part by milling efficiency – i.e., the amount of flour extracted per unit of wheat milled. In this project the objective was to quantify the influence of several measurable variables on flour mill efficiency. Data was collected from two commercial milling units of similar size. Linear regression was then used to estimate the relationship between flour yield and variables measuring grain characteristics and environmental factors. The analysis suggests that increasing ambient temperature and the occurrence of downtime both have a significant negative effect on flour yield. A significant difference in flour yield efficiency was also found between the two mills.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / Chih-Hang Wu / The fast advancement in computer technologies in the recent years has made the use of simulation to estimate stock/equity performances and pricing possible; however, determining the optimal exercise time and prices of American options using Monte-Carlo simulation is still a computationally challenging task due to the involved computer memory and computational complexity requirements. At each time step, the investor must decide whether to exercise the option to get the immediate payoff, or hold on to the option until a later time. Traditionally, the stock options are simulated using Monte-Carlo methods and all stock prices along the path are stored, and then the optimal exercise time is determined starting at the final time period and continuing backward in time. Also, as the number of paths simulated increases, the number of simultaneous equations that need to be solved at each time step grow proportionally. Currently, two theoretical methods have emerged in determining the optimal exercise problem. The first method uses the concept of least-squares approach in linear regression to estimate the value of continuing to hold on to the option via a set of randomly generated future stock prices. Then, the value of continuing can be compared to the payoff at current time from exercising the option and a decision can be reached, which gives the investor a higher value. The second method uses the finite difference approach to establish an exercise boundary for the American option via an artificially generated mesh on both possible stock prices and decision times. Then, the stock price is simulated and the method checks to see if it is inside the exercise boundary. In this research, these two solution approaches are evaluated and compared using discrete event simulation. This allows complex methods to be simulated with minimal coding efforts. Finally, the results from each method are compared. Although a more conservative method cannot be determined, the least-squares method is faster, more concise, easier to implement, and requires less memory than the mesh method. The motivation for this research stems from interest in simulating and evaluating complicated solution methods to the optimal exercise problem, yet requiring little programming effort to produce accurate and efficient estimation results.

Master of Agribusiness / Department of Agricultural Economics / Ted C. Schroeder / During the last 20 years important changes have taken place in the Uruguayan beef chain. Production of grain finished cattle has become a common practice, supply agreements between packers and groups of farmers have increased and packers have begun to own feedyards. Consequently, the number of cattle pre-committed for procurement by a packer has increased significantly. Three sourcing methods are commonly used by packers to ensure captive supply of grain finished fed cattle: marketing agreements, custom feeding and owning a feedyard. The objective of this thesis is to determine the method or combination of methods that result in improved Uruguayan packer profitability through enhanced packer plant management and utilization. To achieve this objective, a quantitative and qualitative analysis using the different sourcing methods was carried out. The analysis looked to identify the drivers that determine why packers resort to one method of procurement rather than other, or a combination of them; and to determine the methods that result in better packer economic results and plant management. The results show that there is no difference between using marketing agreements and custom feedyards, and that resorting to owned feedyards entails higher costs, using current values for feedyard feed and yardage and 2005-2009 average cattle prices. When different scenarios are assessed, custom feeding emerges as the most cost effective option, followed by marketing agreements. However, when qualitative analysis is included, some doubts arise regarding the quantitative advantage of custom feedyards over the alternatives, and a combination of marketing agreements and owned feedyards may be the best option.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / Jessica L. Heier Stamm / In many humanitarian and public health settings, multiple organizations act independently to locate facilities to serve an affected population. As a result of this decentralized decision-making environment, individuals’ access to facility resources may suffer in comparison to a hypothetical system in which a single planner locates the facilities to optimize access for all. Furthermore, due to the unanticipated nature of humanitarian events and the urgency of the need, responders often must cope with a high level of uncertainty regarding the future supply of resources and demand for relief. The contributions of this thesis address the challenges that arise due to the decentralized and dynamic nature of humanitarian response. The first goal of this research is to quantify the difference between decentralized system performance and that possible with a centralized planner. The second goal is to demonstrate the value and feasibility of using a dynamic, rolling-horizon framework to optimize facility location decisions over time. This work compares individuals’ access to health facilities resulting from location decisions made by decentralized decision-makers to the access achieved by a centralized model that optimizes access for all. Access is measured using a special case of the gravity model, the Enhanced Two-Step Floating Catchment Area (E2SFCA) method, which is a distance-weighted ratio of capacity to demand. The E2SFCA method is integrated with integer programming to optimize public access to health facilities. This method is applied to the location of cholera treatment facilities in Haiti, which has been afflicted with a cholera epidemic since October 2010. This research finds that access varied significantly across Haiti, and in the month of February 2011, thirty-seven of the 570 sections, representing 474,286 persons (4.8 percent of the population), did not have adequate access to cholera treatment facilities. Using centralized models to optimize accessibility, performance can be improved but no single model is dominant. This paper recommends use of an efficiency-oriented model in conjunction with an equity constraint to make facility location decisions in future responses. Finally, this work successfully integrates measures of access and equity into a rolling-horizon facility location model and demonstrates that these measures can be incorporated in a full-scale implementation to provide dynamic decision support to planners. This paper advocates for greater awareness of the impact of decentralization in humanitarian response and recommends that future work be undertaken to discover incentives and strategies to mitigate the impact of decentralization in future responses.

Doctor of Philosophy / Department of Hotel, Restaurant, Institution Management and Dietetics / Carol W. Shanklin / Protection motivation theory (PMT) was used in this study to investigate food service directors' food bioterrorism risk perception and their intentions to implement a food defense management plan in their operations. A cross sectional study using the self administered survey was conducted to test hypotheses. All measurement items for the construct of interests were assessed using a 7-point Likert type scales. Questionnaires were mailed in March 2007 to a national sample of 2,200 randomly selected on-site food service directors employed in school districts and healthcare operations. A total 449 usable completed questionnaires were received. Descriptive statistics were performed to investigate directors' perceptions, motivations and intentions independently. Before testing the actual hypotheses, confirmatory factor analysis was conducted to assess reliability and construct validity of the measurement model. Food service directors perceived that the result of a food terrorist attack would be severe but the chances it would occur in their operations is limited. They agreed that implementation of a food defense management plan would be effective to address food terrorism issue in their operations. They were highly motivated to protect the operation from an attack and to avoid the risk of terrorism and intended to implement a food defense plan in their operation. Based on the hypotheses testing, results revealed that motivation to protect the operation against food bioterrorism is higher when directors perceived a higher level of risk (severity and vulnerability), rated the effectiveness of a food defense management plan in protecting the operation high, and perceived that their operations were able to implement it. In turn, high level of motivation to protect the operation led to higher level of implementation intention. Results of the study can be used to design communication resources developed to enhance food service directors' intention to implement a food defense management plan. Educational and informational resources related to intentional food contamination and its defense should emphasize response efficacy and possibility perception.