The objective of this research is to develop distributed approaches to optimizing network traffic. Two problems are studied, which include exploiting social networks in routing packets (coupons) to desired network nodes (users in the social network), and developing a rate based transport protocol, which will guarantee that all the flows in a network (e.g. Internet) meet a delay constraint per packet. Firstly, we will study social networks as a means of obtaining information about a system. They are increasingly seen as a means of obtaining awareness of user preferences. Such awareness could be used to target goods and services at them. We consider a general user model, wherein users could buy different numbers of goods at a marked and at a discounted price. Our first objective is to learn which users would be interested in a particular good. Second, we would like to know how much to discount these users such that the entire demand is realized, but not so much that profits are decreased. We develop algorithms for multihop forwarding of such discount coupons over an online social network, in which users forward coupons to each other in return for a reward. Coupling this idea with the implicit learning associated with backpressure routing (originally developed for multihop wireless networks), we would like to demonstrate how to realize optimal revenue. We will then propose a simpler heuristic algorithm and try to show, using simulations, that its performance approaches that of backpressure routing. As the second problem, we look at the traditional formulation of the total value of information transfer, which is a multi-commodity flow problem. Here, each data source is seen as generating a commodity along a fixed route, and the objective is to maximize the total system throughput under some concept of fairness, subject to capacity constraints of the links used. This problem is well studied under the framework of network utility maximization and has led to several different distributed congestion control schemes. However, this idea of value does not capture the fact that flows might associate value, not just with throughput, but with link-quality metrics such as packet delay, jitter and so on. The traditional congestion control problem is redefined to include individual source preferences. It is assumed that degradation in link quality seen by a flow adds up on the links it traverses, and the total utility is maximized in such a way that the quality degradation seen by each source is bounded by a value that it declares. Decoupling source-dissatisfaction and link-degradation through an ?effective capacity? variable, a distributed and provably optimal resource allocation algorithm is designed, to maximize system utility subject to these quality constraints. The applicability of our controller in different situations is illustrated, and results are supported through numerical examples.

Carbon foams exhibit numerous unique properties which are attractive for light weight applications such as aircraft and spacecraft as a tailorable material. Carbon foams, when exposed to air, oxidize at temperatures as low as 500-600 degrees Celsius. The research objectives of this study are to assess the degree of oxidation of carbon foam by experimental and computational methods and evaluate the degradation in stiffness of the bulk foam as a function of oxygen concentration profile, time and temperature. In parallel to simulation, oxidation tests are conducted to observe changes in morphology and to calculate the apparent activation energy. Degradation patterns in the carbon foam microstructure are categorized through optical microscopy (OM) images post oxidation. The influence of microstructure and temperature on the oxygen concentration profile is investigated in parametric models with varying porosity. The degradation in bulk foam stiffness is found to be strongly dependent on the temperature and non-uniform oxygen concentration profile. The overall results enhance the design of experiments for high temperature and oxidative environments, illustrating the relationship between foam microstructure and oxygen concentration in porous media.

The hydraulic fracturing treatment is an essential tight sand gas reservoir stimulation that employs viscous fluid to break the formation rock to create a fracture and transport the propping agent to support the fracture from naturally healing. Despite proven economic benefit, the hydraulic fracture fluid damages the producing formation and the propped fracture. To analyze the gel damage effect quantitatively, the filter cake thickness is used as a parameter that has not been measured before. This project was divided into two stages. The first stage built up a filter cake and measured the filter cake thickness by a laser profilometer. A correlation between leakoff volume and filter cake thickness was produced. The second stage eroded the filter cake by flowing original fracturing fluid through the core sample to study the fracturing fluid shear clean up effect on filter cake thickness. The filter cake was built up in the lab and the thickness was measured with different methods. The profilometer has been tested as an effective tool to measure the filter cake thickness. A correlation for crosslinked guar fracture fluid filter cake thickness was produced. An experiment setup used to shear erode the filter cake was built and tested. The results showed the filter cake was not eroded at 200 s-1 shear rate.

This dissertation includes three studies, devoted to trying to understand inequality in health between people from different social groups in a democratic society. In the U.S., social inequality in health takes various forms and the key to understanding how democracy solves the problem of inequality lies in a complex set of political and social factors. I take an institutional approach and focus on examining how political and policy institutions, their administrative processes, and the policy implementation environment are linked to social inequality in health. The first essay, Whose Baby Matters More, uses a theoretical framework for evaluating heterogeneous group responses to public health policies and depicts how racial disparities in health are rooted in group heterogeneity in policy responses. The second essay, Anxious Girls and Inactive Boys, focuses on how state-level policy interventions and social capital interactively affect gender differences in health. The third essay, Responsibility for Equity, explores the link between publicness of state healthcare systems and social equity in healthcare access. In the first essay, I focus on racial disparities in infant mortality rates and pool state-level data from 1990 to 2006. The empirical analysis suggests that enhancing the capacity of state healthcare systems is critical to improving population health. Blacks and whites, nevertheless, exhibit different responses to the same policy. Racial disparities could be reduced only when policy interventions generate more relative benefits for Blacks. In the second essay, I find that social capital conditions the effect of public health policies with regard to managing childhood obesity. There are gender differences, moreover, in health outcomes and behavioral responses to state and local-level obesity policies. In the third essay, I find that different institutional factors exhibit different impact on inequality in healthcare access. While public finance resources may reduce inequality in healthcare access, public ownership and the public healthcare workforce do not have significant association with inequality in healthcare access. State Medicaid eligibility rules exhibit moderate impact on inequality in healthcare access.

Nuclear energy is a growing field worldwide due to its wide range of applications in various walks of life. It, however, deals with radioactive materials, specifically special nuclear material, which, if misused, could result in catastrophic consequences. In order to protect this precious resource and ensure its use for the good of mankind, safeguard systems are more important than ever. Current Market solutions are wide ranged but have a large number of disadvantages, some of which include high cost, constant updates, and incomplete efforts. The rising need of a cost effective, efficient, and integrated radioactive safeguard system serves as motivation for the solution outlined in this thesis. The thesis outlines a solution structured around the three pillars of the international safeguards program, namely, visual surveillance and motion detection, containment analysis, and non-destructive analysis. The hardware around each of these pillars work together with a clean and user-friendly application to provide a secure safeguards system that is both flexible and extensible.

The extraction-condensing cogeneration system is a popular technology for heat and power integration which can be used by petrochemical process. To compare with back pressure system, extraction-condensing system has better flexibility for process control. However, the thermal efficiency of extraction- condensing system could be affected by the amount of effective heat to process. If the effective heat to process and the plant power demand were not well designed, the cogeneration system may violate government regulation of ¡§qualified cogeneration system¡¨ by MOEA, or the system economics can not meet investor¡¦s requirement. From another point of view, if the cogeneration system bias original design operating condition or it has to run under low loading, the energy efficiency will move away from the target. A 94.9 MW extraction-condensing system of a petrochemical plant was selected as an example. For the purpose of data requisition, the author established a model to predict main steam flow, extraction steam flow, and power generation load. Moreover, a set of equations for the calculation of heat rate of turbine plant was developed. Besides, a Microsoft Excel calculation sheet was programmed to compute real time plant thermal efficiency. The actual operation data was compared with computer simulation. Results show (1) To meet the regulation, the process steam shall exceed 100 t/h with rated power generation. (2) For the minimum generator load (about 20 MW), the effective heat to process must exceed 78% in order to ensure a 52% overall thermal efficiency. (3) Low load means low thermal efficiency of this system. Some energy conservation ideas of this cogeneration system were assessed. Four ideas were presented, including (1) Increase boiler feed water temperature during low evaporation load. (2) Recovering of flash steam vented from blow down tank for the heating of boiler combustion air. (3) Control of cooling tower fans speed by using frequency inverter. (4) Utilization of hydraulic coupled forced draft fan. The total benefit of these energy conservation ideas is 2,546.44 kilo-liter fuel oil equivalent.

This study aimed at investigating the perceptions of primary school students and teachers on effective teacher characteristics. The sample consisted of 450 primary school students from 6th, 7th and 8th grades and 150 teachers from 9 primary schools in the Province of Afyonkarahisar. Data were gathered from the participants via Effective Teacher Characteristics Questionnaire (ETCQ) developed by the researcher. Both descriptive and inferential statistics were utilized to analyze the data. Principal Component Analysis was used to find out the perceived dimensions of effective teacher characteristics questionnaire. Repeated Measures ANOVA was employed for the priorities of students within these dimensions and MANOVA was used to investigate whether there were significant differences among students&rsquo / perceptions with respect to certain background variables. Descriptive statistics were used to analyze the responses of teachers for the questionnaire. Results of the study indicated that primary school students perceived the effective teacher characteristics with respect to teachers&rsquo / (1) relations with students, (2) personal traits and in-class behavior, (3) teaching ability, (4) motivating personality, (5) professional demeanor, (6) classroom management and (7) feedback &amp / evaluation. Students give the most importance to &lsquo / teaching ability&rsquo / and &lsquo / personality traits and in-class behavior&rsquo / dimensions. Descriptive statistics showed that teachers give the most importance to the items related with field knowledge, pedagogical knowledge and teaching ability.

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Coupling between the electric field, magnetic field, and strain of composite materials is achieved when electro-elastic (piezoelectric) and magneto-elastic (piezomagnetic) particles are joined by an elastic matrix. Although the matrix is neither piezoelectric nor piezomagnetic, the strain field in the matrix couples the E field of the piezoelectric phase to the B field of the piezomagnetic phase. This three-phase electro-magneto-elastic composite should have greater ductility and formability than a two-phase composite in which E and B are coupled by directly bonding two ceramic materials with no compliant matrix. A finite element analysis and homogenization of a representative volume element is performed to determine the effective electric, magnetic, mechanical, and coupled-field properties of an elastic (epoxy) matrix reinforced with piezoelectric and piezomagnetic fibers as functions of the phase volume fractions, the fiber (or particle) shapes, the fiber arrangements in the unit cell, and the fiber material properties with special emphasis on the symmetry properties of the fibers and the poling directions of the piezoelectric and piezomagnetic fibers. The effective magnetoelectric moduli of this three-phase composite are, however, less than the effective magnetoelectric coefficients of a two-phase piezoelectric/piezomagnetic composite, because the epoxy matrix is not stiff enough to transfer significant strains between the piezomagnetic and piezoelectric fibers.

An experimental and numerical investigation of heat transfer enhancement in a three dimensional channel using wall mounted porous baffles was conducted. The module average heat transfer coefficients were measured in a uniformly heated rectangular channel with staggered positioned porous baffles. A numerical procedure was implemented, in conjunction with a commercially available Navier-Stokes solver, to model the turbulent flow in porous media. The Brinkman-Forchheimer-Extended Darcy model was used for modeling fluid flow through the porous baffles. Conventional, oneequation, and two-equation models were used for heat transfer modeling. The accuracy and characteristics of each model were investigated and discussed. The results were compared with experimental data. Baffles were mounted alternatively on the top and bottom walls. Heat transfer coefficients and pressure loss for periodically fully developed flow and heat transfer were obtained for different pore densities (10, 20, and 40 pores per inch (PPI)) with two different baffle heights ( / h h B D = 1/3 and 2/3), and two baffle thicknesses ( / t h B D = 1/3 and 1/12). The Reynolds number (Re) was varied from 20,000 to 50,000. To compare the effect of foam metal baffles, the data for conventional solid-type baffles was obtained for ( / t h B D =1/3). The maximum uncertainties associated with the module Nusselt number and friction factor were 5.8% and 4.3%, respectively. The experimental procedure was validated by comparing the data for the straight channel without baffles ( / h h B D = 0) with those in the literature. The use of porous baffles resulted in heat transfer enhancement as high as 300% compared to heat transfer in straight channels without baffles. However, the heat transfer enhancement per unit increase in pumping power was less than one for the range of parameters studied in this work. Correlation equations were developed for the heat transfer enhancement ratio and the heat transfer enhancement per unit increase in pumping power in terms of Reynolds number. The conventional theoretical model, the dispersion conductivity model, and the modified two-phase model using the local thermal non-equilibrium theory were considered. The results from each model were compared against the experimental data, and compared to each other to investigate the efficiency of each model. Also, the characteristics of each model were discussed.