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Residential water heating is linked to the primary source of waterborne disease outbreaks in the United States, and accounts for greater energy demand than the combined water/wastewater utility sector. To date, there has been little research that can guide decision-making with regards to water heater selection and operation to minimize energy costs and the likelihood of waterborne disease. We have outlined three types of systems that currently dominate the marketplace: 1) a standard hot water tank with no hot water recirculation (STAND), 2) a hot water tank with hot water recirculation (RECIRC), and 3) an on-demand tankless hot water system with no hot water recirculation (DEMAND). Not only did the standard system outperform the hot water recirculation system with respect to temperature profile during flushing, but STAND also operated with 32 – 36% more energy efficiency. Although RECIRC did in fact save some water at the tap, when factoring in the energy efficiency reductions and associated water demand, RECIRC actually consumed up to 7 gpd more and cost consumers more money. DEMAND operated with virtually 100% energy efficiency, but cannot be used in many circumstances dependent on scaling and incoming water temperature, and may require expensive upgrades to home electrical systems. RECIRC had greater volumes at risk for pathogen growth when set at the lower end of accepted temperature ranges, and lower volumes at risk when set at the higher end when compared to STAND. RECIRC also tended to have much lower levels of disinfectant residual (40 -850%), 4-6 times as much hydrogen, and 3-20 times more sediment compared to standard tanks without recirculation. DEMAND had very small volumes of water at risk and relatively high levels of disinfection. A comparison study of optimized RECIRC conditions was compared to the baseline modes of operation. Optimization increased energy efficiency 5.5 – 60%, could save consumers 5 – 140% and increased the disinfectant residual up to 560% higher disinfectant residual as compared to the baseline RECIRC system. STAND systems were still between 3 – 55% more energy efficient and could save consumers between $19 - $158 annual on water and electrical costs. Thus, in the context of “green” design, RECIRC systems provide a convenience to consumers in the form of nearly instant hot water, at a cost of higher capital, operating and overall energy costs. / Ph. D.

Opportunistic pathogens (OPs) can naturally colonize premise (i.e., building) plumbing and are the leading cause of disease associated with potable water in the U.S. and many other countries. While secondary disinfectant is added by utilities prior to water distribution through pipes, the residual in water at the property line is sometimes insufficient to suppress OP growth. Conditions encountered in premise plumbing can further diminish disinfectant in water after it crosses the property line. This dissertation examines how multiple factors at play in drinking water distribution systems and premise plumbing influence OP growth in order to inform development of rational guidance to reduce incidence of waterborne illness. Operating an at-scale cross-linked polyethylene (PEX) plumbing system with one water flush per day, influent chloramine always decayed within four hours in stagnant pipes containing mature biofilms, which is 2-3 orders of magnitude faster than in the same water not contacting pipes. Chloramine often followed second order decay kinetics, though decay rate coefficients were highly variable with some taps eventually transitioning from second to first order decay over time or with increasing influent chloramine concentration. The rate of chloramine decay was unexpectedly reduced in the water heater tank compared to room temperature pipes, possibly due to lower surface-area-to-volume ratio and higher temperature within the tank. A complementary glass jar experiment confirmed that, contrary to expectations, chloramine could decay slower at the higher temperature of 37-39°C maintained in the water heater, compared to the cooler 19-30°C typical of the pipes. These findings demonstrate the need for disinfectant decay models specific to conditions encountered in premise plumbing. Nitrification, a key microbial process that can catalyze chloramine decay, was typically complete within 24 hours after water entered the stagnant pipes. Counterintuitively, the water heater had a relatively lower rate of nitrification along with some detectable denitrification. This work also showed that oxygen, essential for aerobic microbial growth, can permeate through walls of PEX pipe and enter into the water from the atmosphere of the building. Considering the unique array of conditions that were found to influence the persistence of disinfectants in premise plumbing, a new approach was proposed for managing OP risk, referred to herein as the "CT framework." CT was defined as the integral of the chlorine concentration (C) at a point in the premise plumbing versus water retention time (T). Legionella pneumophila was not detectable in pipes with a CT > 78 mg*min/L over a 24 hour period, which is comparable to reported CT thresholds for 3-log inactivation of biofilm-associated L. pneumophila in batch experiments. There was a tradeoff between control of L. pneumophila and Mycobacterium avium in the water heater, as M. avium increased by >1 log as influent chloramine and CT increased, while L. pneumophila decreased by >1.5 logs. Further research is needed to elucidate the influence of factors such as water storage tank hydrodynamics and sediment on the persistence of different OPs. Building water retention time was also found to be an overarching variable that governs microbial growth in some circumstances in premise plumbing. Total cell counts and L. pneumophila occurrence mirrored expected trends based on the classic microbial growth curve with phases of lag, exponential growth, stationary growth, and decay. The location in the plumbing system where each phase dominated depended on water retention time, disinfectant level, and temperature. The microbial growth curve considerations add an additional dimension to the CT framework for predicting L. pneumophila growth potential in premise plumbing. Specifically, elevated heat or chloramine, was able to temporarily suppress or even eliminate growth, but the phases of classic microbial growth could be restarted once disinfectant or very high temperatures were absent. Total cell counts and L. pneumophila typically peaked at a building water retention time of 7 days, demonstrating that once a week flushing guidance to protect public health may not be advantageous in all situations. Collectively, this work offers fundamental and practical insights into factors driving disinfectant decay and microbial proliferation in premise plumbing, offering a modified CT and microbial growth concept framework to help guide the management of OPs in premise plumbing. / Doctor of Philosophy / Access to safe drinking water is fundamental to human health and wellbeing and is considered to be a human right by some agencies. Opportunistic pathogens (OPs) can grow in some drinking water systems and cause deadly diseases, such as Legionnaires' Disease. Legionnaires' Disease and illnesses caused by other OPs are now the leading cause of drinking water-associated disease in the U.S. and many other countries. Chlorine or chloramine are disinfectants required to be present in treated drinking water in the U.S. before it is piped through the distribution systems to consumers. This helps to limit growth of OPs and other microbes in the distribution systems. However, the concentration of disinfectant that remains in water as it crosses the property line is sometimes inadequate to suppress OP growth. Even if the amount of disinfectant entering a building is boosted, there are some plumbing materials and circumstances that can quickly reduce the disinfectant. These challenges are sometimes worsened by water and energy conservation efforts, which extend the time water spends in a building and presents tradeoffs with preventing OP growth. This dissertation examines how multiple factors at play in drinking water distribution systems and building plumbing individually and collectively influence OP growth, with a goal of developing rational guidance to reduce incidence of waterborne illness. Experiments were conducted using a large at-scale building plumbing system. These experiments revealed new insights into the relationship among factors such as how long the water stagnates in pipes, water temperature, the disinfectant concentration at each tap, and the level of specific OPs of concern. Chloramine was gone within four hours of stagnation in plastic cross-linked polyethylene (PEX) pipes containing a mature biofilm, which is 100-1000× faster than observed in the same water that did not contact pipes. The rate at which chloramine disappeared changed with conditions from tap to tap, or with time at a given tap, in ways that were unexpected based on prior assumptions. Further, the hydraulic characteristics and low temperature of the water heater influenced chloramine decay in the tank in a way that increased survival and release of OPs. We found that other microbes residing in pipes, such as nitrifying microbes, can also play a role in decay of disinfectant and their activity also is controlled by the water retention time and temperature in the system. These findings reinforce the need to thoroughly understand how chemical, biological, and hydraulic factors combine to influence OP growth in buildings. To account for the array of factors that contribute to the decay of disinfectant, we introduce premise plumbing "CT" as a new integrative framework to guide management of OPs. We define CT as the integral of the disinfectant concentration (C) at a stagnant point in the building plumbing verses the time (T) water has resided at that point, to characterize the ability of the water to kill or suppress growth of bacteria. If the calculated CT values in the at-scale plumbing system were high enough, Legionella pneumophila, the OP that causes Legionnaires' Disease, was never detected in pipes. However, if CT was too low, L. pneumophila was not controlled. Oddly, M. avium, another problematic OP, exhibited a contradictory trend within the water heater. This indicates that the CT concept may not control M. avium in chloraminated water heaters with complex water flow patterns and sediment. Higher chloramine caused lower L. pneumophila and higher M. avium in the water heater, but this tradeoff did not occur in cold water pipes when the room temperature was below that required for OP growth, indicating that room temperature setpoint could be a significant factor for OP control in buildings. Building water retention time, which is the time that water takes to move through the plumbing before it is consumed from a tap, was identified in this research to be a key driver of microbial growth that can be readily controlled by building managers. Trends of total microbial cell count and L. pneumophila in the premise plumbing system and complementary experiments followed all the phases of growth associated with bacteria in a simple glass jar, including a lag, rise, peak, and then decay of cells. Elevated heat or chloramine was able to temporarily suppress growth or even kill cells, but the phases of growth were again observed once the chemical or thermal disinfectant was removed. In any building, there is likely a frequency of flushing water at a given tap that is "worst case" for bacterial growth. In the absence of disinfectant, bacteria in pipes that are frequently supplied with nutrients through fresh water can be expected to have sustained growth, but if bacteria are starved of nutrients, there is some die off. In our system, total microbial cell counts and L. pneumophila peaked at a water retention time of about one week. Thus, this work suggests that current advice to flush building pipes once a week might sometimes create issues with microbial growth rather than solve them. Collectively, this research advances both fundamental and practical understanding of the factors driving disinfectant decay and microbial proliferation in premise plumbing. The premise plumbing CT and microbial growth concept framework is introduced to help inform better management of building water systems to prevent or remediate the growth of pathogens and reduce risk of human infection.

Opportunistic premise plumbing pathogens (OPPPs) are responsible for many infections linked to drinking water. The annual cost of disease caused by these waterborne pathogens is $850 million. Key characteristics of these opportunistic waterborne pathogens include: disinfectant- resistant, biofilm formation, thermal-tolerance, desiccation-resistant, growth in amoebae and growth in low oxygen conditions. Methylobacterium spp. have been recognized as an emerging OPPP, so the purpose of this study was to investigate these waterborne bacteria in more detail to determine whether they have all characteristics of OPPPs. Seven Methylobacterium spp. strains were studied to measure growth in laboratory broth medium and drinking water, measure hydrophobicity on surfaces found in household plumbing, measure adherence and biofilm formation to surfaces found in household plumbing and measure susceptibility to hot water heater temperatures. Methylobacterium spp. were found to aggregate in lab broth medium and drinking water, hydrophobic on different surfaces in household plumbing, adhere readily and form biofilm on different surfaces and thermal-tolerant to water heater temperatures. These results support and identify Methylobacterium spp. as opportunistic premise plumbing pathogens. / Master of Science / Opportunistic premise plumbing pathogens (OPPPs) are microbial residents of drinking water systems and premise plumbing that cause infection. Premise plumbing includes water pipes in hospitals, houses, apartment buildings or office buildings. OPPPs share a number of characteristics that contribute to their growth and survival in drinking water systems. In this study, <i>Methylobacterium</i> spp., an emerging OPPP, were studied to see if they share all of the characteristics of OPPPs. Seven <i>Methylobacterium</i> spp. strains were studied to measure growth in laboratory broth medium and drinking water, measure hydrophobicity (ability to repel water) on surfaces found in household plumbing, measure adherence to surfaces found in household plumbing and measure susceptibility to high temperatures. <i>Methylobacterium</i> spp. were found to form clusters of cells in lab broth medium and drinking water, hydrophobic on different surfaces in household plumbing, adhere readily on different surfaces and resistant to high temperatures. These results support <i>Methylobacterium</i> spp. are opportunistic premise plumbing pathogens. This is important because there is now a better understanding of how <i>Methylobacterium</i> spp. survive in drinking water systems to prevent its growth and persistence. This study was also able to determine which pipe surfaces support the least amount of <i>Methylobacterium</i> spp. growth to be used be used by plumbers and homeowners to reduce exposure to <i>Methylobacterium</i> spp.

Assimilable organic carbon (AOC) is a suspected contributor to growth of microbes, including pathogens, in plumbing systems. Two phases of research were completed to improve knowledge of AOC and other forms of organic carbon in premise plumbing. In the first phase, the AOC Standard Method 9217B was compared to a new luminescence-based AOC in terms of time, cost, convenience, and sources of error. The luminescence method was generally more accurate, as it better captured the peak growth of the test organisms. It was also less expensive and less time-consuming. A few approaches to improving the accuracy of the method and detect possible errors were also presented. In the second phase of research, the possibility of AOC generation in premise plumbing was reviewed and then tested in experiments. It has been hypothesized that removal of AOC entering distribution systems might be a viable control strategy for opportunistic premise plumbing pathogens (OPPPs), but if AOC was generated in premise plumbing systems this approach would be undermined. Possible sources of AOC creation in premise plumbing, which is herein termed "distribution system derived biodegradable organic carbon (DSD-BDOC)," include: leaching of organic matter from cross linked polyethylene (PEX) pipes, autotrophic oxidation of H2 generated from metal corrosion (e.g. sacrificial magnesium anode rods and iron pipes), rendering of humic substances more biodegradable by sorption to oxides such as Fe(OH)3, and accumulation of AOC on filters and sediments. The potential for various plumbing and pipe materials to generate AOC was compared in controlled simulated water heater experiments. Under the worst-case condition, generation up to 645 µg C/L was observed. IT was not possible to directly confirm the biodegradability of the generated organic carbon, and there were generally no correlations between suspected generation of organic carbon and either heterotrophic plate counts (HPC) or of bacterial 16S rRNA genes. DSD-BDOC was also explored in a simulated distribution system with two disinfectant types (chlorine and chloramine) and three pipe materials (PVC, cement, and iron). TOC increased with water age, probably due to leaching of organics from PVC and possibly the aforementioned DSD-BDOC due to autotrophic reactions of nitrifiers and iron-related bacteria. As before, relationships between the higher levels of organic carbon and either HPC or 16S were not observed. / Master of Science

Reasoners can be used to derive implicit consequences from an ontology. Sometimes unwanted consequences are revealed, indicating errors or privacy-sensitive information, and the ontology needs to be appropriately repaired. The classical approach is to remove just enough axioms such that the unwanted consequences vanish. However, this is often too rough since mere axiom deletion also erases many other consequences that might actually be desired. The goal should not be to remove a minimal number of axioms but to modify the ontology such that only a minimal number of consequences is removed, including the unwanted ones. Specifically, a repair should rather be logically entailed by the input ontology, instead of being a subset. To this end, we introduce a framework for computing fixed-premise repairs of $\mathcal{EL}$ TBoxes. In the first variant the conclusions must be generalizations of those in the input TBox, while in the second variant no such restriction is imposed. In both variants, every repair is entailed by an optimal one and, up to equivalence, the set of all optimal repairs can be computed in exponential time. A prototypical implementation is provided. In addition, we show new complexity results regarding gentle repairs. / This is an extended version of an article accepted at the 45th German Conference on Artificial Intelligence (KI 2022).

<p>Significant seasonal changes in chemical and microbiological water quality can occur in buildings at different fixture locations due to temperature and time dependent reaction rates. Here, a series of calibrated plumbing hydraulic-water quality models were developed for the extensively monitored Retrofitted Net-zero Energy, Water & Waste (ReNEWW) house in West Lafayette, Indiana USA. Knowledge gaps that inhibited higher resolution water quality modeling were also identified. The eight new models predict the absolute level of free chlorine, total trihalomethanes (TTHM), Cu (Copper), Fe (Iron), Pb (lead), NO₃^–(nitrate-nitrogen), heterotrophic plate count (HPC), and <i>Legionella spp.</i> concentration at each fixture for plumbing use, operational characteristics, and design layouts of the plumbing system. Model development revealed that the carrying capacity to describe Legionella spp. growth (and other organisms) under water usage and plumbing design conditions is lacking in the literature. This information needed for higher resolution modeling. Reducing building water use by 25% prompted increased absolute concentrations of HPC and Legionella, each increasing by a factor of about 10⁵. When the service line length was increased, Legionella spp. concentrations increased by up to 10⁶gene copies /L in the Summer season. The proposed modeling framework can be used to support better planning, design, analysis, and operational decision-making.</p>

Cloud services and solutions have served as a shift in the computer industry and create new opportunities for users. Clouds have been described as easily usable and fluid in terms of expansion and contraction depending on the real-time needs. Although the cloud is promoted with several benefits, it is not always apparent for the users that this is the case. Understanding both the benefits and challenges that exist is substantial for a successful adoption to cloud. This master’s thesis is conducted in collaboration with Exsitec ABand aims to investigate how the adoption of the cloud service Microsoft Azure will affect the development process. Also, it aims to provide a best practice for potentially needed updated working procedures, in terms of satisfaction and learnability. The investigation was performed through interviews and the System Usability Scale, to assess how the end users experienced development in a cloud environment. The thesis revealed that the Azure portal has low overall usability, but that there also exists an inconsistency of that perception. Two major factors that contributed to the satisfaction and learnability was the lack of documentation and that the Azure portal was considered hard to master. The SUS score revealed that the mean value was below an acceptable level, and thus changes in the company’s working procedures need to be implemented. Internal documentation regarding how the company should use both cloud in general, as well as the portal in particular, are required in order to increase the learnability and subjective satisfaction.

In this exegesis I have attempted to formulate a primary toolset for dramatic writing that I can apply to create dramatic structure in plays, the chief example being my play Albatross (included herein). This toolset is contingent upon Aristotle's basic tenet of drama, that "tragedy is an imitation of an action" (2002: 10). This exegesis theorises that the work of modern writers on drama such as Spencer, Packard, Catron, Lamott, See, Hicks and many others, fundamentally accords with Aristotle on this point, such that the tools they espouse can collectively be considered a standard set for dramatic writing. Beyond this, my research has led me to believe that there is a primary subset of tools specific to creating dramatic structure. These tools, formulated from dramatic theory, best capture my own way of thinking about my writing practice. I divide them into two types: the first, tools of creation, comprise Theme and Values; Character and their Values; Characters and Action; Character Orchestration and Obstacles; and Event and Significant Change. The second, tools of evaluation, are Passivity; Stakes; and Premise. Together these eight tools have been responsible for creating dramatic structure in the play, Albatross.

This thesis focuses on the ubiquitous cloud computing trend and particularly Software as a Service. The main goal is to specify all pros and cons of this concept for its customers and also cloud providers. The global perspective is then specified to Software as a Service and deployment of SaaS ERP products. The next goal is to define an appropriate method to analyze a company's needs prior to switching to the cloud. Furthermore, recommendations as to whether the cloud is better than an on-premise version should result from the previous analysis. Another aim is to form a process for successful switch to the cloud and ensure all important aspects of using cloud services are covered. Theoretical findings and recommendations are used in a practical example of SaaS ERP deployment. To reach all goals, a theoretical analysis of all available monograph and electronic sources, covering cloud computing and consultations with experts from the company; Algotech BSC, were used. The main added value is in the dual point of view on the topic, from customer's and provider's viewpoints with a more detailed focus on ERP. The author suggests the right procedure for switching to the cloud, guidance with calculating ROI, TCO and preparing all necessary contracts and agreements.