Doctor of Philosophy / Department of Electrical and Computer Engineering / Caterina Scoglio / Vector-borne diseases not only cause devastating economic losses, they also significantly impact human health in terms of morbidity and mortality. From an economical and humane point of view, mitigation and control of vector-borne diseases are essential. Studying dynamics of vector-borne disease transmission is a challenging task because vector-borne diseases show complex dynamics impacted by a wide range of ecological factors. Understanding these factors is important for the development of mitigation and control strategies. Mathematical models have been commonly used to translate assumptions concerning biological (medical, demographical, behavioral, immunological) aspects into mathematics, linking biological processes of transmission and dynamics of infection at population level. Mathematical analysis translates results back into biology. Classical deterministic epidemic models do not consider spatial variation, assuming space is homogeneous. Spatial spread of vector-borne diseases observed many times highlights the necessity of incorporating spatial dynamics into mathematical models. Heterogeneous demography, geography, and ecology in various regions may result in different epidemiological characteristics. Network approach is commonly used to study spatial evolution of communicable diseases transmitted among connected populations. In this dissertation, the spread of vector-borne diseases in time and space, is studied to understand factors that contribute to disease evolution. Network-based models have been developed to capture different features of disease transmission in various environments. Network nodes represent geographical locations, and the weights represent the level of contact between regional pairings. Two competent vector populations, Aedes mosquitoes and Culex mosquitoes, and two host populations, cattle and humans were considered. The deterministic model was applied to the 2010 Rift Valley fever outbreak in three provinces of South Africa. Trends and timing of the outbreak in animals and humans were reproduced. The deterministic model with stochastic parameters was applied to hypothetical Rift Valley fever outbreak on a large network in Texas, the United States. The role of starting location and size of initial infection in Rift Valley fever virus spread were studied under various scenarios on a large-scale network. The reproduction number, defined as the number of secondary infections produced by one infected individual in a completely susceptible population, is typically considered an epidemic threshold of determining whether a disease can persist in a population. Extinction thresholds for corresponding Continuous-time Markov chain model is used to predict whether a disease can perish in a stochastic setting. The network level reproduction number for diseases vertically and horizontally transmitted among multiple species on heterogeneous networks was derived to predict whether a disease can invade the whole system in a deterministic setting. The complexity of computing the reproduction number is reduced because the expression of the reproduction number is the spectral radius of a matrix whose size is smaller than the original next generation matrix. The expression of the reproduction number may have a wide range of applications to many vector-borne diseases. Reproduction numbers can vary from below one to above one or from above one to below one by changing movement rates in different scenarios. The observations provide guidelines on executing movement bans in case of an epidemic. To compute the extinction threshold, corresponding Markov chain process is approximated near disease free equilibrium. The extinction threshold for Continuous-time Markov chain model was analytically connected to the reproduction number under some assumptions. Numerical simulation results agree with analytical results without assumptions, proposing a mathematical problem of proving the existence of the relationships in general. The distance of the extinction threshold were shown to be closer to one than the reproduction number. Consistent trends of probability of extinction varying with disease parameters observed through numerical simulations provide novel insights into disease mitigation, control, and elimination.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Caterina Scoglio / Society increasingly depends on networks for almost every aspect of daily life. Over the past decade, network science has flourished tremendously in understanding, designing, and utilizing networks. Particularly, network science has shed light on the role of the underlying network topology on the dynamic behavior of complex systems, including cascading failure in power-grids, financial contagions in trade market, synchronization, spread of social opinion and trends, product adoption and market penetration, infectious disease pandemics, outbreaks of computer worms, and gene mutations in biological networks. In the last decade, most studies on complex networks have been confined to a single, often homogeneous network. An extremely challenging aspect of studying these complex systems is that the underlying networks are often heterogeneous, composite, and interdependent with other networks. This challenging aspect has very recently introduced a new class of networks in network science, which we refer to as multilayer and interconnected networks. Multilayer networks are an abstract representation of interconnection among nodes representing individuals or agents, where the interconnection has a multiple nature. For example, while a disease can propagate among individuals through a physical contact network, information can propagate among the same individuals through an online information-dissemination network. Another example is viral information dissemination among users of online social networks; one might disseminate information received from a Facebook contact to his or her followers on Twitter. Interconnected networks are abstract representations where two or more simple networks, possibly with different dynamics over them, are interconnected to each other. For example, in zoonotic diseases, a virus can move from the network of animals, with some transmission dynamics, to a human network, with possibly very different dynamics. As communication systems are evolving more and more toward integration with computing, sensing, and control systems, the theory of multilayer and interconnected networks seems to be crucial to successful communication systems development in cyber-physical infrastructures. Among the most relevant dynamics over networks is epidemic spreading. Epidemic spreading dynamics over simple networks exhibit a clear example where interaction between non-complex dynamics at node level and the topology leads to a complex emergent behavior. A substantial line of research during the past decade has been devoted to capturing the role of the network on spreading dynamics, and mathematical tools such as spectral graph theory have been greatly useful for this goal. For example, when the network is a simple graph, the dominant eigenvalue and eigenvector of the adjacency matrix have been proven to be key elements determining spreading dynamics features, including epidemic threshold, centrality of nodes, localization of spreading sites, and behavior of the epidemic model close to the threshold. More generally, for many other dynamics over a single network, dependency of dynamics on spectral properties of the adjacency matrix, Laplacian matrix, or some other graph-related matrix, is well-studied and rigorously established, and practical applications have been successfully derived. In contrast, limited established results exist for dynamics on multilayer and interconnected networks. Yet, an understanding of spreading processes over these networks is very important to several realistic phenomena in modern integrated and composite systems, including cascading failure in power grids, financial contagions in trade market, synchronization, spread of social opinion and trends, product adoption and market penetration, infectious disease pandemics, and outbreak in computer worms. This dissertation focuses on spreading processes on multilayer and interconnected networks, organized in three parts. The first part develops a general framework for modeling epidemic spreading in interconnected and multilayer networks. The second part solves two fundamental problems: introducing the concept of an epidemic threshold curve in interconnected networks, and coexistence phenomena in competitive spreading over multilayer networks. The third part of this dissertation develops an epidemic model incorporating human behavior, where multi-layer network formulation enables modeling and analysis of important features of human social networks, such as an information-dissemination network, as well as contact adaptation. Finally, I conclude with some open research directions in the topic of spreading processes over multilayer and interconnected networks, based on the resulting developments of this dissertation.

Doctor of Philosophy / Department of Chemical Engineering / Peter H. Pfromm / The expanded Renewable Fuel Standard (RFS2), established under the Energy Independence and Security Act (EISA) of 2007, mandates the production of 136.3 GL/year of renewable fuels in the U.S. in 2022: 56.8 GL/year of corn-ethanol, 60.6 GL/year of second generation biofuels such as cellulosic ethanol, and 18.9 GL/year of advanced biofuels such as biomass-based diesel. One of the several challenges when a biochemical conversion technique is used to produce bioethanol from corn and cellulosic feedstock is the high energy demand for recovering and purifying ethanol, which is mainly due to the low concentration of ethanol in the fermentation broth and the challenging water-ethanol vapor liquid equilibrium. Dilute ethanol from the fermentation broth can be separated and concentrated aided by salt extractive distillation to directly produce fuel ethanol leading to significant energy savings. Techniques other than highly energy intensive evaporative salt concentration/crystallization and solids drying for recovering salt, which is used to facilitate distillation, have rarely been considered. In this study, a novel combination of electrodialysis and spray drying was investigated to recover the salt. Salt extractive distillation – with salt recovery enabled by electrodialysis – was conceptually integrated in the fermentation broth-ethanol separation trains of corn and cellulosic ethanol facilities and investigated through process simulation with Aspen Plus® 2006.5 to reduce the recovery and purification energy demand of bioethanol. Experiments for the electrodialytic concentration of calcium chloride from high diluate concentrations, prevalent in the salt recovery process when calcium chloride is used as the salt separating agent in the salt extractive distillation of bioethanol, were carried out to determine the fundamental transport properties of an ion exchange membrane pair comprising commercially available membranes for implementation in the conceptual process designs. The maximum calcium chloride concentration achievable through electrodialytic concentration is 34.6 wt%, which is mainly limited by the water transport number. In case of corn-ethanol, retrofitted salt extractive distillation resulted in an energy demand reduction of about 20% and total annual cost savings on the order of MM$0.5 per year when compared with the state-of-the-art rectification/adsorption process for producing fuel ethanol from the beer column distillate. In case of cellulosic ethanol, salt extractive distillation with direct vapor recompression provided the highest energy savings of about 22% and total annual cost savings on the order of MM$2.4 per year when compared with the base case comprising conventional distillation and adsorption for recovering and purifying ethanol from the fermentation broth. Based on the conceptual process design studies, an overall maximum energy savings potential of 1.5*10[superscript]17 J or about 0.14 Quad (as natural gas higher heating value) per year could be estimated for the targeted 56.8 GL of corn-ethanol and 60.6 GL of cellulosic ethanol to be produced in the U.S in 2022 when salt extractive distillation enabled by electrodialysis is implemented in the fermentation broth-ethanol separation trains of the corn and cellulosic ethanol facilities.

Master of Science / Department of Civil Engineering / Dunja Peric / The main objective of this study was to experimentally investigate the Mohr-Coulomb strength parameters of masonry sand mixed with varying amounts of water and lignin. Lignin is a plant-derived biomass, which is a co-product of bio-fuel production. It exhibits binding qualities when mixed with water thus making it an ideal candidate for sustainable non-traditional sand stabilization. An experimental program was devised and carried out to quantify the compaction and early age stress-strain and dilatancy responses of sand-lignin mixes. The program included sieve analysis, Atterberg limit tests, standard Proctor tests, and direct shear tests. The experimental results were used to find the cohesion and the angle of internal friction of the tested material, therefore determining the influence of the amount of lignin and water on the strength of the samples. An extensive data analysis was subsequently completed to gain deeper understanding of the underlying strength gain mechanism. It was found that the normalized cohesion benefit due to lignin is controlled by two variables; water to lignin ratio and void ratio. The lignin and water create a paste, which provides particle bonding at the contacts of sand particles, thus increasing the stress-bearing cross sectional area. Increase in the portion of cross-sectional area occupied by water and lignin normalized by gravimetric lignin content, increases the normalized cohesion up to a point, while the cohesion per gravimetric lignin content decreases with the increasing area ratio. This in turn indicates that cohesion increases only up to 6% of lignin, beyond which it starts to decrease due to the presence of too much fine material within the pores. The presence of lignin in the pores consistently decreases the angle of internal friction. However, for all configurations with lignin tested herein, cohesion was larger than for dry sand, thus indicating strength benefits at low confining pressures or at normal stresses below the so-called limiting normal stress.

Master of Science / Department of Civil Engineering / Mustaque Hossain / A recent study at Kansas State University has shown that asphalt producers in Kansas are producing hot-mix asphalt (HMA) mixtures with lower asphalt contents than those in the job-mix formula. These drier mixtures are thought to be susceptible to moisture. This project evaluated the effect of asphalt content on rutting and moisture resistance of HMA. Two different mixtures and four varying asphalt contents, optimum and lower, were selected. Another large-size mixture with four varying asphalt contents was also studied. The Hamburg Wheel Tracking Device (HWTD)test (TEX-242-F) and the Kansas Standard Test-56 (KT-56), or modified Lottman test, were used to predict moisture damage and rutting potential of these mixes. All specimens tested were prepared with the Superpave gyratory compacter. Results of this study showed the drier mixtures performed better in rutting and were less susceptible to moisture.Asphalt content significantly affects the number of wheel passes in the HWTD test. The study also revealed a weak correlation between asphalt film thickness and performance test results. Thus, the effect of varying asphalt content is nonconclusive from a durability point of view. However, performance simulations using a theoretical model show that very dry mixes in asphalt pavements are likely to have shorter performance lives.

Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / The design of power amplifiers in any semi-conductor process is not a trivial exercise and it is often encountered that the simulated solution is significantly different than the results obtained. Oscillatory phenomena occurring either in-band or out of band and sometimes at subharmonic intervals can render a design useless. Other less apparent effects such as jumps, hysteresis and continuous spectrum, often referred to as chaos, can also invalidate a design. All of these problems might have been identified through a more rigorous approach to stability analysis. Designing for stability is probably the one area of amplifier design that receives the least amount of attention but incurs the most catastrophic of effects if it is not performed properly. Other parameters such as gain, power output, frequency response and even matching may have suitable mitigation paths. But the lack of stability in an amplifier has no mitigating path. In addition to the loss of the design there are the increased production cycle costs, costs involved with investigating and resolving the problem and the costs involved with schedule slips or delays resulting from it. The Linville or Rollett stability criteria that many microwave engineers follow and rely exclusively on is not sufficient by itself to ensure a stable and robust design. It will be shown that the belief that unconditional stability is obtained through an analysis of the scattering matrix S to determine if K>1 and [delta][supscript]s<1 can fail and other tools must be used to validate circuit stability. With the emphasis being placed on stability, a 1W pulse modulated S-band power amplifier is designed using a battery of analysis tools in addition to the standard Linville or Rollett criteria to rigorously confirm the stability of the circuit. Test measurements are then presented to confirm the stability of the design and illustrate the results. The research shown contributes to the state of the art by offering a detailed approach to stability design and then applying the techniques to the design of a 1W pulse modulated S-band power amplifier demonstrating the first with 20 nanosecond pulse width switching and single digit nanosecond rise and fall times at 1 Watt power levels.

Doctor of Philosophy / Civil Engineering / Asadollah Esmaeily / Accurate and realistic assessment of the performance of columns in general, and those in critical locations that may cause progressive failure of the entire structure, in particular, is significantly important. This performance is affected by the load history, pattern, and intensity. Current design code does not consider the effect of load pattern on the load and displacement capacity of columns. A primary research sponsored by Kansas Department of Transportation (KDOT) was conducted as the initial step of the present study (No. K-TRAN: KSU-11-5). The main goals of the KDOT project were: (1) investigation of new KDOT requirements in terms of the column design procedure and detailing and their consistency with AASHTO provisions; (2) verification of the KDOT assumptions for the plastic hinge regions for columns and bridge piers, (3) provide assessment of the load capacity of the existing columns and bridge piers in the light of the new specifications and using the new load demand as in the new provisions; and finally recommendations for columns and bridge piers that do not meet the new requirements. A conclusion was drawn that there is a need for conducting more studies on the realistic performance of Reinforced Concrete (RC) sections and columns. The studies should have included performance of RC members under various loading scenarios, assessment of columns capacity considering confinement effect provided by lateral reinforcement, and investigation on performance of various monotonic and cyclic material models applied to simulate the realistic performance. In the study reported here, monotonic material models, cyclic rules, and plastic hinge models have been utilized in a fiber-based analytical procedure, and validated against experimental data to simulate behavior of RC section under various loading scenarios. Comparison of the analytical predictions and experimental data, through moment–curvature and force–deflection analyses, confirmed the accuracy and validity of the analytical algorithm and models. The performance of RC columns under various axial and lateral loading patterns was assessed in terms of flexural strength and energy dissipation. FRP application to enhance ductility, flexural strength, and shear capacity of existing deficient concrete structures has increased during the last two decades. Therefore, various aspects of FRP-confined concrete members, specifically monotonic and cyclic behavior of concrete members confined and reinforced by FRP, have been studied in many research programs, suggesting various monotonic models for concrete confined by only FRP. Exploration of existing model performances for predicting the behavior of several tested specimens shows a need for improvement of existing algorithms. The model proposed in the current study is a step in this direction. FRP wrapping is typically used to confine existing concrete members containing conventional lateral steel reinforcement (tie/spiral). The confining effect of lateral steel reinforcement in analytical studies has been uniquely considered in various models. Most models consider confinement due to FRP and ignore the effect of conventional lateral steel reinforcement. Exploration of existing model performances for predicting the behavior of several tested specimens confined by both FRP and lateral steel shows a need for improvement of existing algorithms. A model was proposed in this study which is a step in this direction. Performance of the proposed model and four other representative models from literature was compared to experimental data from four independent databases. In order to fulfill the need for a simple, yet accurate analytical tool for performance assessment of RC columns, a computer program was developed that uses relatively simple analytical methods and material models to accurately predict the performance of RC structures under various loading conditions, including cyclic lateral displacement under a non-proportionally variable axial load (Esmaeily and Xiao 2005, Esmaeily and Peterman 2007). However, it was limited to circular, rectangular, and hollow circular/rectangular sections and uniaxial lateral curvature or displacement. In this regards, a computer program was developed which is the next generation of the aforesaid program with additional functionality and options. Triangulation of the section allows opportunity for cross-sectional geometry. Biaxial lateral curvature/displacement/force combined with any sequence of axial load provides opportunity to analyze the performance of a reinforced concrete column under any load and displacement path. Use of unconventional reinforcement, such as FRP, in lateral as well as longitudinal direction is another feature of this application.

Master of Science / Industrial & Manufacturing Systems Engineering / Shing I. Chang / The process capability is a measurable property of a process related to the specification of a product. Traditionally, process capability analysis (PCA) measurements are expressed by a process capability ratio (PCR). When using a typical PCR to measure process capability, there are certain assumptions, and critics have been made towards PCR, that some the assumptions are violated. Much research has been conducted to ratify the situations when some of the assumptions are violated. This thesis, is going to demonstrate a research towards process capability using Sample Entropy method. The desirable outcome would be that this method can avoid violating the assumptions.

Master of Science / Department of Grain Science and Industry / Xiuzhi Susan Sun / Soybean oil-based resin for transparent flexible coating applications were formulated by dihydroxyl soybean oil (DSO) with commercial epoxy monomers (i.e., epoxidized soybean oil (ESO) and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECHM)). The resin was formed to thermoset polymers using cationic ring-opening photopolymerization. The ether crosslinking and post-polymerization of the polymeric network were observed using Fourier transform infrared spectroscopy. Thermal properties of the bio-based coating materials and their copolymerization behaviors were examined using a differential scanning calorimetry and a thermogravimetric analyzer. Crosslink density and molecular weight between crosslink were obtained from dynamic mechanical analysis. ECHM/DSO (1: 1.43 weight ratio) films showed the highest elongation at break (49.2 %) with a tensile strength of 13.7 MPa. After 2 months storage, the elongation at break and tensile strength of films were 32 % and 15.1 MPa, respectively. ESO/DSO films (w/w ratios of 1:0.1, 1:0.15, and 1:0.2) exhibited stable flexibility around 11-13 % of elongations at break without significant reductions of tensile strengths (2.5 to 4.4 MPa) during 2-months shelf life. Optical transparencies of the films were comparable to commercial glass and polymers, and water uptake properties (0.72 and 2.83%) were significantly low.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / M. H. Hosni / B. W. Jones / This dissertation focuses on airflow distribution in the longitudinal direction of a wide-body mockup aircraft cabin, turbulence energy and dissipation rates, and the effect of thermal plumes, generated by passengers, on airflow distribution within the cabin. The mockup cabin utilized for this study mimics a Boeing 767 passenger cabin and includes 11 rows in the longitudinal direction with each row consisting of seven seats. Each seat is occupied by an inflatable manikin which is instrumented with a 10 meters long wire heater generating approximately 100 Watts of distributed sensible heat, representing heat load from a sedentary human being. In order to investigate the fluid dynamics characteristics of the airflow within the cabin, different experimental techniques were implemented. Smoke visualization was used to qualitatively visualize the general airflow pattern inside the cabin. A tracer gas composed mainly of carbon dioxide was used to track the airflow distribution inside the cabin. The tracer gas was released in several locations and then sampled at various locations throughout the mockup cabin. The release and sampling of the tracer gas allowed tracing the airflow inside the cabin using non dispersive infrared sensors. Combining results from different release-sampling scenarios gave better understanding of the chaotic and three-dimensional nature of the airflow behavior inside the cabin. Air speed and turbulence parameters were evaluated using omni-directional probes. Finally, the effect of the heat generated by the thermal manikins on the airflow behavior was investigated. The results from the airflow visualization and the tracer gas were complementary and showed that there were multiple air circulations along the length of the cabin. The dimension of the circulations were controlled by the minimum physical distance inside the cabin. The identified-isotropic turbulence were spread over the full width of the cabin in the front and middle sections of the cabin, whereas, multiple-smaller circulations were identified in the rear section. Cabin sections identified with high speed fluctuations were associated with higher turbulence kinetic energy levels and lower local dissipation rates. These sections served as driving forces to create the circulations identified in the tracer gas experiments. Furthermore, the heat generated by the thermal manikins was shown to significantly impact the behavior of the gaseous flow inside the cabin, the turbulence parameters, and speed fluctuations. Detailed uncertainty analysis was conducted to estimate the uncertainty limits for the measurements taken. The uncertainty estimates obtained for the tracer gas results ranged from ±14% for the test cases with the heated manikins to ±17% with the corresponding unheated manikins cases. The data uncertainty limits for the turbulence parameters were of higher levels due to limitations associated with the omni-directional probes used to measure the speed. With flow repeatability phenomena in same locations inside the mockup cabin during different days reaching up to ±10%, the uncertainty estimates were considered acceptable for these chaotic and highly random airflow conditions within the cabin.