This work is concerned with the interaction between condensing aerosol dynamics and hydrodynamic mixing within ow configurations in which aerosol particles form (nucleate) from a supersaturated vapor and supersaturation is induced by the mixing of two streams (a saturated stream and a cold one). Two canonical hydrodynamic configurations are proposed for the investigation. The First is the steady one-dimensional opposed-ow configuration. The setup consists of the two (saturated and cold) streams owing from opposite nozzles. A mixing layer is established across a stagnation plane in the center where nucleation and other aerosol dynamics are triggered. The second is homogeneous isotropic turbulence in a three-dimensional periodic domain. Patches of a hot saturated gas mix with patches of a cold one. A mixing layer forms across the growing interface where the aerosol dynamics of interest occur. In both configurations, a unique analogy is observed. The results reveal a complex response to variations in the mixing rates. Depending on the mixing rate, the response of the number density falls into one of two regimes. For fast mixing rates, the maximum reached number density of the condensing droplets increases with the hydrodynamic time. We refer to this as the nucleation regime. On the contrary, for low mixing rates, the maximum reached number density decreases with the hydrodynamic time. We refer to this as the consumption regime. It is shown that vapor scavenging by the aerosol phase is key to explaining the transition between these two regimes.

This thesis is to investigate the voltage sag, transient stability and operation feasibility of power islanding with different types of dispersed generation in distribution systems. One radial distribution feeder of Taiwan Power Company (TPC) is selected for computer simulation. The mathematical models of dispersed generations including exciters, governors of steam turbine and frequency controller of wind-driven induction generator are used in the simulation program of Matlab/Simulink. Applying the dispersed generation system with synchronous and induction generators at different locations of the test feeder by executing the short circuit and motor starting analysis to find the discrepancy in the voltage sag and the relation between the motor voltage with the motor power. Finally the simulation analysis of transient stability is executed for unbalance distribution systems with dispersed generations of steam turbines and wind-driven turbines by considering two different operation scenarios after the distribution system has been disconnected from TPC system. Different load and output power control of dispersed generation are applied to maintain the stable operation of the islanding power system. Based on the transient stability analysis, it is suggested that the service reliability of power system with critical loads can be enhanced by the dispersed power generation with proper design of load shedding and output power control.

The main objective of my thesis is to develop a numerical model for small-scale thermal energy storage system and to see the effect of dispersing nano-particles and using fractal-like branching heat exchanger in phase change material for our proposed thermal energy storage system. The associated research problems investigated for phase change material (PCM) are the low thermal conductivity and low rate of heat transfer from heat transfer fluid to PCM in thermal energy storage system. In this study an intensive study is carried out to find the best material for thermal storage and later on as a high conductive nano-particle graphite is used to enhance the effective thermal conductivity of the mixed materials. As a thermal storage material molten solar Salt (60% NaNO3+40%KNO3) has been selected, after that detailed numerical modeling of the proposed design has been done using MATLAB algorithm and following the fixed grid enthalpy method. The model is based on the numerical computation of 1-D finite difference method using explicit scheme. The second part of the study is based on enhancing the heat transfer performance by introducing the concept of fractal network or branching heat exchanger. Results from the numerical computation have been utilized for the comparison between a conventional heating system (with a simple single tube as a heat exchanger) and a passive PCM thermal energy storage system with branching heat exchanger using NTU-effectiveness method and charging time calculation. The comparison results show a significant amount improvement using branching network and mixing nano-particle in terms of heat transfer (13.5% increase in effectiveness of branching level-02 heat exchangers from the conventional one ), thermal conductivity (increased 73.6% with 20% graphite nano-particle mix with solid PCM), charging time (57% decrease of charging time for the effect of both the dispersion of Graphite nano-particle and branching heat exchange) and pressure drop (36% decrease in level-02 branching). The results of this study prove that the proposed medium temperature TES system coupled with solar ORC can be the stepping-stone for energy efficient and sustainable future in small-scale/building level as the system proves to be better in terms of enhanced heat transfer, increased thermal conductivity and reduced pumping power and overall sustainability.

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Mono-dispersed supported Ni catalysts were synthesized using the water-CTAB-hexanol reverse micellar system. The core of the reverse micelles contained an aqueous solution of NiCl2. Dynamic light scattering measurements showed that microemulsions having a water-to-surfactant molar ratio, Wo, of 10 lead to reverse micelles with lowest polydispersity, longest stability, and size range of interest. At an oil-to-aqueous phase ratio of 2, the diameter of the reverse micelles was found to increase with Wo in a linear fashion. At higher values of Wo (i.e. 25-30), the polydispersity was found to increase when lowering the amount of surfactant in the system. Ultimately, O/A = 2 and Wo = 10 were chosen as optimal conditions for microemulsion preparation. The aqueous NiCl2 concentration within the micelles was varied between 0.1 and 0.001 M. DLS results showed that although the average micelle diameter was between 70-83 nm throughout the range of metal salt concentrations, the crystallite size estimate based upon the reported micelle diameter and known aqueous NiCl2 concentration ranged between 2 to 7 nm. Therefore, the Ni crystallite size was varied by changing the aqueous NiCl2 concentration due to instability issues arising when changing the value of Wo. After deposition onto an alumina mesh support, the particles were dried, calcined, and reduced to produce Ni clusters. SEM and EDS analysis was used to confirm the presence of Ni compounds after the calcination stage. By the varying the aqueous NiCl2 concentration within the micelles, .0039, .0013, and .00039 wt. % Ni catalysts were produced and characterized using SEM. Particles in the size range of 10-14 nm were noticed for the .0039 wt. % Ni catalysts after reduction, 7-11 nm for .0013 wt. % Ni, and 5-9 nm for .00039 wt. % Ni. The lower-end of these particle size ranges was comparable to the crystallite size estimates. Ethane hydrogenolysis and ethylene hydrogenation reactions were conducted over the emulsion-prepared catalysts in order to determine particle size effects on catalytic activity. Results showed that the catalytic activity, defined in terms of per unit metal surface atom (or TON, turnover number), decreases with increasing particle size for the hydrogenolysis reaction. This trend may be due to an intrinsic size effect in which smaller particles exhibit the chemical or structural properties necessary for achieving a higher reaction rate. The results for ethylene hydrogenation showed that the reaction rate did not significantly change with crystallite size, confirming that the reaction is facile or structure-insensitive.

The purpose of thesis is to investigate the transient stability and operation feasibility of power islanding with different type of dispersed generation in distribution system. A substation of Taipower system is selected for case study to simulate the system transient stability. The mathematical models of dispersed generations including exciters, governors of gas turbine and pitch controller of wind-driven induction generator are used in the simulation program. To represent the load behavior more accurately, the load ratio of residence, commercial, industrial customer class and the composition of electric equipments in feeder, such as induction motors, air conditioners etc, have been identified through load survey study. The load models of end users are employed in simulation to solve the power consumption as function of bus voltage and system frequency. Besides, the dynamic model of induction motors is integrated to solve more accurate system power demand under transient condition. The simulation analysis of transient stability is executed for unbalance distribution system with dispersed generations of gas turbines and wind-driven turbines with three operations sceneries after the distribution system has been disconnected from Taipower system. Different load shedding schemes and output power control of dispersed generation are considered to maintain the stable operation of islanding power system. It is suggested that the system reliability of power system can be enhanced by the dispersed power generation with proper design of load shedding in the transient stability analysis.

With existing numerical models for fluid particle systems in CHEM, the acoustic-particle interactions associated with two-phase dilute dispersed flow can be captured and the particle model can be validated using experimental and analytical data and verified using numerical techniques. The experimental and analytical data come from Zink and Delsasso and provides data for particles of diameters 5 to 15 microns for frequencies between 500Hz to 13600Hz. In the particle number density measurements by Zink and Delsasso there was a 10% estimated error range. Using the fourth order skew symmetric flux in CHEM and the built in Eulerian and Lagrangian particle models, the sound wave dissipation was captured and found to be within the margin of error. Two additional tests were conducted to measure the effect of nonlinear acoustics and increased bulk density on the dissipation. Nonlinear effects showed no significant effect and the linear increase in bulk density showed a linear increase in dissipation.

Thesis advisor: Ryan Chahrour / Expectations formation is central to macroeconomics. Households, firms, and policymakers must form expectations not only about fundamentals, but about what other agents’ beliefs are, because others’ beliefs will determine their actions. The three essays in this dissertation examine empirically and theoretically how agents use both public and private information to form expectations. The first two essays combine a models of optimizing behavior and forecasting with data on the macroeconomy, financial prices, and macroeconomic forecasts to examine the extent to which economic agents learn about the macroeconomy from financial prices and monetary policy actions. The third essay examines theoretically how members of a committee use public and private information to form beliefs when they care both about having accurate forecasts and coordinating actions with others. All three essays emphasize that frictions in expectations formation are a salient feature of the world, and understanding the extent and importance of those frictions is important for both positive and normative questions in macroeconomics and finance. Beliefs about the future determine the willingness of financial market participants to save and invest, and theory suggests they should value more highly assets which are expected to pay higher returns during recessionary periods when consumption is otherwise low. Hence, financial prices reflect macroeconomic expectations. In the first essay, titled "Macroeconomic Disagreement in Treasury Yields," I explore how agents with idiosyncratic, private information form beliefs about both the macroeconomy and the beliefs of other agents. Using data on United States Treasury debt, the macroeconomy, and individual inflation forecasts, I estimate the precision of bond traders’ information about the macroeconomy and how much they disagree with each other. I allow for traders to learn both from private signals and from asset prices, which aggregate the beliefs of all the traders in the market. I find that bond prices are moderately informative about macroeconomic variables, but are the source of most of the information traders have about monetary policy and the beliefs of others. In contrast to studies which assume full information, risk premia are much less important than slow-adjusting interest rate expectations for explaining the behavior of long-run yields. The most important signal for bond traders appears to be the Federal Reserve’s short-run rate, which encodes information about the macroeconomy and the central bank’s intended future policy. Nevertheless, the fact that traders held disparate beliefs about the macroeconomy, and especially about the long-run inflation target of the Federal Reserve, elevated long-term yields on average. The first essay demonstrates empirically that financial market participants learn about the macroeconomy from monetary policy actions. However, it is silent on how monetary policymakers form beliefs about the macroeconomy, or how the information in monetary policy rates endogenously affects macroeconomic outcomes. In the second essay "Your Guess is as Good as Mine: Central Bank Information and Monetary Policy," I use data on private sector forecasts and forecasts from the Federal Reserve Board staff to examine the typical assumption of common information between firms and monetary policymakers. Using forecasts from a survey of professional forecasters and from the Federal Reserve Board staff, I show evidence against the typical assumption of common information between monetary policymakers and the private sector, and also that policymakers are, at best, only weakly better at forecasting than private forecasters. Based on this evidence, I augment an otherwise standard monetary policy model by relaxing the common information assumption. Instead, I assume there is idiosyncratic, private information among price-setting firms, and between firms and the central banker. Firms combine private information about aggregate conditions with the observed monetary policy rate to form expectations about fundamentals and the beliefs of rival firms. The central banker must form expectations about firms’ beliefs because those beliefs will determine inflation and overall economic activity. But as a result of their differences in information sets, firms must form expectations about other firms’ expectations, and what the central banks’ expectations of their expectations are. I examine the ability of this model to fit the data and find that the model can capture features of both firm and central bank inflation expectations, but in the absence of imperfect information among households, it is difficult to simultaneously match the forecast data and data on real activity. This result points to the sensitivity of models with dispersed information to the underlying assumptions about how central bankers will respond to exogenous shocks. The second chapter emphasized how the assumptions economists make regarding monetary policymakers’ information is critical for understanding their actions. Motivated by this example, my third chapter "Information Investment in a Coordination Game" explores theoretically how members of a committee who are uncertain about others’ beliefs decide on a binary action, and how their decision to pay close attention to public or private signals is related to their desire to accurately forecast versus coordinating their behavior with others. I show that when it is assumed that information decisions among committee members are symmetric - everyone pays the same amount of attention to the same things - there is a unique outcome of the coordination game. However, I further show that it is difficult to guarantee that committee members will all choose a symmetric allocation of information. Aside from the direct cost of acquiring better information, allocating attention to more accurate signals can harm welfare when coordination motives are dominant. In a set of numerical exercises, however, I show that it is possible for a unique equilibrium to exist, and that actions that do not have a large impact on the payoffs of committee members (such as changing the size of the committee) may nevertheless have large impacts on the accuracy of the committee’s forecasts. This suggests a possible tension between the welfare of the committee, which benefits from consensus, and the welfare of those affected by the committee’s actions, which likely depends on whether the committee takes the objectively correct action. My dissertation has important implications for both academic economists and policymakers. Understanding the sources of business cycle fluctuations and the determinants of asset prices requires grappling with the fact that people have differences in beliefs. Empirical evidence suggests that agents’ beliefs are shaped by both idiosyncratic forces and by public announcements and policy decisions, and economists’ models need to reflect these features of the world. Policy, too, is affected by the information available to policymakers, and to understand how policymakers have acted in the past and should act in the future, it is necessary to take seriously the ways their belief formation deviates from the full information rational expectations benchmark.

Persistent and secure store for web objects is an attractive feature in today?s web world and possess a good potential for exploration. Persistence of a storage mechanism refers to its ability to store an object for extremely long time periods. Resilience refers to its fault tolerance ability or its ability to retrieve the object completely even if a part of that object is lost due to any catastrophic failures like disk failure. It is also important that this storage mechanism is able to store this object in a secure manner. In the current world, usability of any storage mechanism is enhanced multiple times if it could be used from a web interface. This thesis considers different techniques that provide these properties and proposes a storage mechanism that makes use of information dispersal techniques that is suited to store data securely, with an emphasis on availability and resilience. A working prototype of this storage mechanism was developed as a part of this thesis and is made available as a library for program developers. This library provides APIs to store and retrieve data as well as a daemon for error control. The APIs to store and retrieve data also accepts HTTP requests, which increase its usability to web developers. The performance of this prototype was measured and is presented using graphs. Finally a demonstration of the applications of this prototype is also provided.

The ecological effects and mechanistic efficiency of chemical oil spill countermeasures must be evaluated prior to their ethical application during real spill response scenarios. Equally important is the ability to monitor the effectiveness of any spill response in real time, permitting informed response management. In-situ sensors are key components of such event based monitoring and continuous monitoring programs. This project investigates crude oil toxicity as a particulate suspension, suitability of in-situ instrumentation to measure crude oil suspensions, and the applicability of using acoustic backscatter to measure suspended solids and sub-surface oil droplet suspension concentrations. The ecological effects to inter- and sub-tidal sediment dwelling organisms exposed to crude oil, both treated with a chemical dispersant and un-treated, was evaluated. Elevated toxicity, expressed as percent mortality and reduced luminescence, and oil concentrations were observed in inter-tidal sediments receiving oil only treatments compared to oil-plus-dispersant treatments. Sub-tidal sediments showed heterogeneous distribution of crude oil with elevated amphipod mortality compared to no oil controls suggesting an oil-sediment aggregation mechanism. A separate laboratory scale study found that the soluble crude oil fractions were responsible for the observed mortality in pelagic species while the more dominant oil droplet fractions were relatively non-toxic. Subsequent studies focused on the in-situ detection of crude oil and particle suspensions in aqueous environments. The first showed that both in-situ fluorescence spectroscopy and Laser In-Situ Scattering Transmissometry (LISST) can effectively measure crude oil concentrations in aqueous environments. The applicability of the LISST implies that crude oil in an aqueous medium can be measured as a particle suspension. Acoustic backscatter (ABS) was investigated for its applicability as a surrogate measurement technology for aqueous particle suspensions. This study showed a log linear correlation between ABS and volume concentration (VC) over a variable particle size distribution. This correlation is due to the dependency of both ABS and VC to the particle size distribution. Log-linear ABS responses to oil-droplet suspension volume concentrations were also demonstrated. However, the inability to reproduce response factors suggests that more work is required to produce viable calibrations that may be used for sub-surface oil plume detection.