In this thesis, low-cost free chlorine sensors for monitoring drinking water have been developed. The starting material, pencil lead, was modified using a ammonium carbamate solution. The main emphasis for this technology is the low cost, scalable and environmental friendly process. The resultant materials were highly sensitive to free chlorine. The second discovery was an advanced understanding of the unsteady state mass transfer during the sensing process, using the customly expanded Cottrell equation. This method could qualitatively indicated the absence of free chlorine, for applications where the removal of free chlorine is the goal. This method allowed better interpretation of transient data and simplified setup. The third discovery was the use of pulsed amperometric detection to detect free chlorine at a much higher sensitivity, while reducing the complexity of the setup, further reducing the cost. This method was based on the previous findings plus understanding of the reaction kinetics. The resultant sensors detected free chlorine with a detection of 0.0414 ppm, while the regulations require the free chlorine to be above 0.2 ppm. The response time was less than three seconds. The range of detection was up to around 20 ppm. The cost of materials for one sensor was less than ten dollars. The maintenance was minimal due to the lack of consumables. The operation could be as a meter or as a device in a large instrument. The target use of the sensors include small and distant communities, bottling industries, fruit and vegetable washing industries. The free chlorine sensing techniques can be readily expanded to biology, environment, and big data applications, based on the knowledge gained through the study. / Thesis / Doctor of Philosophy (PhD) / Low-cost sensors were developed to monitor free chlorine in drinking water for end users, especially in small and distant communities. Free chlorine keeps lethal microorganism pathogens from re-growing after disinfection. Re-growth is more likely to happen in these communities due to poor infrastructure and less usage-driven flow. The contributions include: • A low-cost sensing material for free chlorine based on pencil lead • Determination of operating range of the sensor • Study of sensing mechanisms • Efficiency improvement and cost reduction • Research articles, conference presentations, patent applications, and industrial collaboration based on above research The resultant sensor is easy to use, robust in practical conditions and requires low maintenance, suitable for small and distant communities. Future work is the integration with sensing systems and the application of knowledge gained in this thesis for sensing applications in other fields.

Each year approximately 7,500 low-income Virginia families are enrolled in the Expanded Food and Nutrition Education Program (EFNEP), administered through the Virginia Cooperative Extension (VCE). Chronic disease and health conditions cost society an estimated $250 billion each year in medical charges and lost productivity. It has been assumed that the numerous diet and food-related changes made by EFNEP participants will lead to a reduction in the risk of chronic disease among homemakers, and perhaps, other family members. Thus, the improved diets and behaviors resulting from EFNEP participation may result in substantial future savings in healthcare costs among participants. This study explores the possibility of potential economic benefits for the Virginia EFNEP participants. In 1996, the Virginia Cooperative Extension was awarded a grant from the Cooperative State, Research, Education, and Extension Service, United States Department of Agriculture (CSREES, USDA) to conduct a cost-benefit study of EFNEP in Virginia. Though computation of the cost-benefit ratio for the Virginia adult EFNEP includes both direct and indirect benefits, this study addressed only the assessment of the direct tangible benefits based on the savings from economic costs of avoided diseases. Existing EFNEP data for the 1996 fiscal year was used to identify optimal nutritional behaviors that can delay or prevent the onset of certain chronic diseases and health conditions. The economic costs of diseases were identified from scientific literature and translated as potential benefits. The administration costs of EFNEP were also compiled. The total direct tangible benefit for the diseases and conditions identified was estimated to be $17,770,722. Along with the indirect tangible benefits ($321,462), the total tangible benefits for the Virginia EFNEP was calculated to be $18,092,184. The direct tangible costs associated with the Virginia EFNEP in 1996 was $1,922,204. The benefit-cost ratio for the Virginia EFNEP for the 1996 fiscal year for the subset of the population practicing the optimal nutritional behaviors is calculated at $9.41/$1.00 (a $9.41 return for every $1 invested in EFNEP in Virginia). Also, a benefit of $2.45 to $1.00 was calculated when only 25% of those participants practicing optimal nutritional behaviors were assumed retain these behaviors through life. For a program of the magnitude of EFNEP, these results are very gratifying. / Ph. D.

Researchers have consistently found that students and their parents have a distorted view of the costs of college attendance (Grodsky & Jones, 2004; Horn, Chen, & Chapman, 2003; Ikenberry & Hartle, 1998; Mumper, 1996). Those who are able to give an estimate of the tuition for various higher education alternatives often overestimate the actual price. When asked to estimate the tuition that in-state undergraduates would pay at four-year colleges in a given year, most students and their parents thought that the price was twice the actual amount (Horn et al., 2003b). Seventy-one percent of all individuals, and 83% of African-Americans believed that college was unaffordable for most families. The majority of individuals over-estimated the price by several thousands of dollars (Hartle, 1998). This study examined the literature on perceived price and used the theoretical construct based on the work of Nobel Prize winner Gary Becker to develop a methodology for studying whether students' perceived price of has a statistically significant impact on their plan to attend college and their actual matriculation. Applying Becker's theory, having faulty information on the price of attendance would result in people incorrectly weighting the cost-benefit equation and making what could be considered irrational decisions in the presence of complete information. Highlighting the problem of misperceived price is the contribution this study makes to the literature. Further study is warranted to determine the extent to which individuals use misperceived prices to make decisions on whether to plan to attend higher education. / Ph. D.

This dissertation consists of three essays in Applied Econometrics that seek a better understanding of different aspects of risk and risk management tools. The first essay is about mortality risk in Virginia coal regions. With a focus on the mortality of non-malignant respiratory diseases (NMRD), I estimate the impact of living in a coal county and find that coal-mining county residency significantly increases the probability of dying from NMRD. This statistical association is accentuated by surface coal mining, high smoking rates, lower health insurance coverage, and a shortage of doctors. The second essay evaluates the cost of a price risk management tool called futures hedging. A variety of measures illustrate considerable changes in hedging costs over time. Quantile regression results show that substantial price volatility and high margin requirements are the main factors driving high hedging costs from 2007 to 2013. The third paper investigates a health risk management tool, a public health insurance program in China called New Cooperative Medical Scheme (NCMS). I apply contract theory to characterize local governments' selective incentives in NCMS benefit designs. Empirical analysis of China Health and Nutrition Survey data indicate challenges of financial sustainability of this scheme in poor regions. The NCMS plan tends to under-cover the services that are moderately predictable and negatively correlated with plan profits, such as outpatient treatments. Preventive services are generally over-provided, perhaps due to the incentive to attract healthy participants. / Doctor of Philosophy / This dissertation uses quantitative analysis to investigate three economic problems related to different aspects of risk. The first question is, what affects the respiratory health of Virginia coal mining counties' residents? Using respiratory mortality as the variable of interest, this paper finds that surface coal mining, high smoking rates, and lack of health access jointly contribute to the elevated risk of dying from respiratory diseases in our study area. The second research problem is about a price risk management tool called "hedging": purchasing contracts in the futures market to offset price movements in the cash markets. Based on historical data of corn and soybeans, I simulate the cost of hedging and find this risk management tool is not cheap, especially in 2007 to 2013. The high cost is mainly due to substantial price fluctuations in the recent decade. As a health risk management tool, health insurance is the focus of my third study. In China rural areas, a public health scheme aimed to reduce a resident's risk of suffering medical impoverishment by spreading the risk over residents in a county. County governments were relatively free to design the implementation and benefit plans. This study reveals that most New Cooperative Medical Scheme (NCMS) benefit plans are not efficient to achieve the scheme's objective. Facing high risk of fund deficits, local insurance programs in poor regions are likely to under-cover health services, such as outpatient treatments. If this scheme were allowed to charge higher prices from high-risk enrollees instead of a flat-rate premium, its efficiency might be improved.

Continuous integration (CI) is a widely used practice in modern software engineering. Unfortunately, it is also an expensive practice — Google and Mozilla estimate their CI systems in millions of dollars. In this dissertation, I propose a collection of novel build selection approaches that are able to save the cost of CI. I also propose the first exhaustive comparison of techniques to improve CI including build and test granularity approaches. I firstly design a build selection approach (SMARTBUILDSKIP) for CI cost reduction in a balanceable way. The evaluation of SMARTBUILDSKIP shows that it can save a median of 30% of builds by only incurring a median delay of 1 build in a median of 15% of failing builds under its most conservative configuration. To minimize the delayed failure observation, I then propose the second build selection approach (PRECISEBUILDSKIP) that can save cost without delaying failure observation. We find that PRECISEBUILDSKIP can save a median of 5.5% of builds while capturing the majority of failing builds (100% in median) from the evaluation. After that, I evaluate the strengths and weaknesses of 10 techniques that can improve CI including SMARTBUILDSKIP. The findings of the comparison motivate my next work to design a hybrid technique (HYBRIDBUILDSKIP) that combines these techniques to produce more cost-saving while keeping a low proportion of failing builds that are delayed in observation. Finally, I design an experiment to understand how different weights of test duration among the whole build duration can influence the cost-saving of build and test selection techniques. / Doctor of Philosophy / Modern software developing teams commonly use the continuous integration as the practice of automating and testing the integration of code changes from multiple contributors into a single software project. The best practice of continuous integration requires this process happens as frequently as possible because the bugs can be found earlier and easier before the change sets grow too large. However, continuous integration process can be time-consuming and in most cases the code change is bug-free. This means that developers may have to wait for a long time only to get a result with no actionable feedback. Thus, in this dissertation, I present multiple selection approaches to selectively execute the continuous integration process based on the prediction of the outcome - if the outcome is predicted to be passing with no actionable feedback, the approach will decide to skip the current execution. The evaluation result shows that my approaches can save the cost of continuous integration while keeping the value of it (finding bugs earlier).

A simulation model analyzes cost effectiveness of remote facility monitoring for risk reduction in rural water supply systems by performing a break-even analysis that compares operating costs with manual and remote monitoring. Water system operating cost includes the value of water loss (i.e., realized risk) resulting from operating excursions which are inversely related to mechanical reliability. Reliability is controlled by facility monitoring that identifies excursions enabling operators to implement mitigating measures. Cost effectiveness refers to the cost relationship among operating alternatives that reveals changed economic conditions at different operating rates inherent in the inverse relationship between fixed and variable costs. Break-even analysis describes cost effectiveness by identifying the operating rate above which the more capital intensive alternative will result in lower operating cost. Evidence indicates that increased monitoring frequency associated with remote monitoring can reduce water system operating cost by improving reliability, but whether remote monitoring is cost effective depends upon system-specific factors. The lack of a documented tool for evaluating this type of cost effectiveness led to the project objective of developing a model that performs break-even analysis by simulating water system operating costs as functions of system size (delivery rate). When the spreadsheet-based static deterministic parametric simulation model is run for the Tazewell County, Virginia water system based upon 1998 data, break even is predicted at approximately fifty-five percent of annual capacity (116,338,000 gallons) with operating cost of $1,043,400. Maximum annual operating cost reduction from a $317,600 investment provides payback in nine years. / Master of Science

This research presents a framework system dynamics (simulation) model that evaluates the effect of maintenance policies on system performance and life-cycle cost. The model highlights factors such as learning, aging and the technological upgrades that occur during the life-cycle of a system. The metrics used to measure the effectiveness of maintenance policies are the system life-cycle cost and cumulative breakdowns. In this research, a varying maintenance policy has been modeled using system dynamics methodology to determine the future performance of the system that is dependent upon its past performance when breakdowns occur randomly. The main objective of this modeling approach is to balance the cost of preventive maintenance actions with the opportunity losses due to system breakdowns. The approach used in this research primarily involves forecasting future breakdowns using an average of accumulated opportunity losses. This research effort was mainly aimed at developing a (framework) model to determine effective maintenance policy for a system and evaluating the effect on the life-cycle cost for various scenarios. This model could further form the basis of a decision support system for maintenance modeling. / Master of Science

The focus of this dissertation is on tax and agency costs rationales for the use of long term leases. While much attention has been given to the valuation effects of debt and equity financing, the literature is surprisingly scant on the valuation effects of lease financing. This research develops a model that demonstrates that lease contracts can create wealth in two ways: one, by partially alleviating the Myers' underinvestment problem created by the issuance of risky debt and the other, by effectively transferring tax shields from low income lessees to high income lessors. The implications of the model are formulated into testable hypotheses which are empirically tested in both financial leases and sale and leaseback transactions. Several new empirical findings are reported in the study. Evidence presented indicates that the market reacts favorably to lease announcements by lessees involved in either sale and leaseback transactions or financial leases. No general conclusions could be drawn for the valuation impact for lessors. In addition, the results suggest that tax motives are of primary importance in explaining the use of lease financing. However, the agency cost rationale is not confirmed by the data. / Ph. D.

Yes / Oil and Gas plants consist of a set of heat exchangers, which are used in recovering the waste heat from product streams to preheat the oil. The heat transfer coefficient of exchangers declines considerably during the operation period due to fouling. Fouling in heat exchangers is a complex phenomenon due to the acceleration of many layers of chemical substances across tubes of heat exchangers resulting from chemical reactions and surface roughness. In this paper, the fouling process was determined as a critical failure in the heat exchanger. Failure is an accelerated fouling layer across the heat exchanger tubes, which can be the reason for the clogging of tubes. Hence, a risk assessment was conducted using the Risk-Based Inspection (RBI) approach to estimate the probability of fouling in heat exchangers. The results showed that the RBI approach can be used successfully to predict the suitable time to shut down the plant and conduct the fouling cleaning process.

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