This dissertation investigates the effects of changes in technologies and trade-related policies on income inequality. The first chapter shows that an advancement in labor saving technologies, known as automation, raises the agglomeration of economic activity in large cities and increases wage inequality across regions. I show novel stylized facts about the relationship between city size and the routineness of tasks performed by workers. I develop a general equilibrium model of a spatial economy where automation affects the type of tasks performed by workers and is related to a firm's choice of production location. The model generates several predictions that are consistent with stylized facts and existing empirical evidence: larger cities have greater agglomerations of firms and grow larger when firms can automate more tasks in the production process. The model predicts that an increase in automation raises wage dispersion between larger and smaller cities. A 20% rise in automation increases wages in the top decile of largest cities by about 8% and lowers wages in smaller cities by about 2-8% and hence widens the wage gap by about 10 to 16 %. The second chapter investigates the effect of exchange rate volatility on the intensive and extensive margin of trade, and on income inequality within a country. It finds that the greater volatility in exchange rates lowers trade margins and income inequality. I derive testable predictions regarding the impact of exchange rate volatility on trade margins at the firm level and on income distribution at the industry level. I empirically test these predictions using firm-level microdata. Empirical results provide clear support in favor of the model's predictions about the effects of volatility on trade margins. Finally, in the third chapter, my coauthors and I investigate the effect of Bangladesh’s graduation from Least Developed Country (LDC) status on the price of insulin, an essential medicine for diabetes, and on households’ welfare and poverty. We find that upon Bangladesh’s graduation from LDC status, the price of insulin could rise as much as 11 times the current price for patented insulin if an unregulated monopoly is allowed. This would significantly reduce welfare and increase the incidence of poverty for households with members suffering from diabetes.

This research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micrometers], from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40°C-50°C. The solidification mechanism is referred to as Temperature Induced Forming and is described by polymeric bridges formed between nanoparticles in suspension at elevated temperatures, resulting in a solid structure. The polymer network results from the ionization of alumina at elevated temperatures whereby polymeric binders adhere to newly formed charged sites on the alumina particle. This study aims to investigate the aspects of manufacturing microstructures in microfluidic Tjunctions, droplet morphology, size and frequency of production. Preliminary low solid concentration experiments (1%-10% volume concentration of alumina in H2O) have indicated solidification and a regression in droplet diameter when heated near the saturation temperature of the water used to disperse the particles. The microstructures from this solidification process are uniform and are estimated to be 30 [micrometers] in size.

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The objective of the current research is to study the effect of mechanical vibration on catalyst layer degradation via Platinum (Pt) particle agglomeration and growth in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEM Fuel Cell). This study is of great importance, since many PEM fuel cells operate under a vibrating environment, such as the case of vehicular applications, and this may influence the catalyst layer degradation and fuel cell performance. Through extensive literature review, there are only few researches that have been studied the effect of mechanical vibration on PEM fuel cells. These studies focused only on PEM fuel cell performance under vibration for less than 50 hours and none of them considered the degradation of the fuel cell components, such as MEA and its catalyst layer. To study the effect of the mechanical vibration on the catalyst layer an accelerated test with potential cycling was specially designed to simulate a typical vehicle driving condition. The length of the accelerated test was designed to be 300 hour with potential cycling comprised of idle running, constant load, triangle (variable) load and overload running at various mechanical vibration conditions. These mechanical vibration conditions were as follows: 1g 20 Hz, 1g 40 Hz, 4g 20 Hz and 4g 40 Hz. No vibration tests were also conducted to study the influence of operating time and were used as a baseline for comparison study. The series of accelerated tests were followed by microscopy and spectroscopy analyses using environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD). An ESEM was used to qualitatively analyze pristine and degraded catalyst. TEM and XRD were used to quantitatively analyze catalyst layer degradation via Pt agglomeration and growth in pristine and degraded states. For each test condition, PEM fuel cell performance by means of Voltage - Current (VI) curves was monitored and recorded. It was observed that the mean diameter of Pt particles tested under mechanical vibration is 10% smaller than the ones that were tested under no vibration conditions. The Pt particles in the order of 2 to 2.5 nm in the pristine state have grown to 6.14 nm (after 300 hour accelerated test at no vibration condition), to 5.64 nm (after 300 hours accelerated test under 4g 20 Hz vibration condition) and to 5.55 nm (after 300 hours accelerated test under 1g 20 Hz vibration condition). The mean Pt particle diameters, after 300 hour accelerated test under 1g 40 Hz and 4g 40 Hz vibration conditions, were 5.89 nm. With an increase of the mean Pt particle diameter, the active surface area of the catalyst layer of the MEA decreases and as a result, performance of MEA and PEM fuel also decreases. It was observed that performance of the MEA tested under no vibration condition is about 10% lower than the one tested under 1g 20 Hz. The VI curve showed that the lowest performance of the MEA after 300 hour accelerated test corresponded to no vibration conditions and equaled to 7.85 Watts at 0.5 V (Pt particle size ~ 6.14 nm) and highest performance, corresponded to the MEA tested under 1g 20 Hz, and equaled to 8.66 Watts at 0.5 V (Pt particle size ~ 5.55 nm). / Mechanical Engineering

Master of Science / Froth flotation is a common method in mineral processing to separate material based on hydrophobicity. This process becomes less efficient, however, as particle size is reduced. Because of this ultrafine particles are often discarded prior to froth flotation, and contributes to a substantial amount of coal waste in impoundments. An impoundment is a dam built using coarse reject to hold fine reject in slurry. Because of the land-use and risk of an impoundment failure, these impoundments pose an environmental liability. To address ultrafine coal rejection, researchers at Virginia Tech development the hydrophobic-hydrophilic separation (HHS) process. Unlike in froth flotation, HHS uses an organic solvent to separate and dewater hydrophobic particles from hydrophilic minerals. Past work on the HHS process yielded promising results. In particular, the HHS process has produced a low-ash (<2%) and low moisture (<8%) product, which makes it viable for a feed stock for carbon products. With this in mind, the goal of this work is to make the HHS process more robust by improving the understanding of the effects of auxiliary processes, such as grinding, pre-concentration, and reagent conditioning, on the HHS process. This work also contains work on the interaction between two primary unit operations in the HHS process: oil agglomeration and de-emulsification. Lastly, to make the HHS process more viable for commercial scale-up, a novel unit operation called enhanced liquid flotation (ELF) was developed and tested that performs comparably to the current HHS process, but with less unit operations.

This thesis pertains to the processing of ultra-fine mineral particles and low rank coal using the hydrophobic--hydrophilic separation (HHS) method. Several explorative experimental tests have been carried out to study the effect of the various physical and chemical parameters on the HHS process. In this study, the HHS process has been employed to upgrade a chalcopyrite ore. A systematic experimental study on the effects of various physical and chemical parameters such as particle size, reagent dosage and reaction time on the separation efficiencies have been performed. For this, a copper rougher concentrate (assaying 15.9 %Cu) was wet ground and treated with a reagent to selectively hydrophobize the copper-bearing mineral (chalcopyrite), leaving the siliceous gangue minerals hydrophilic. The slurry was subjected to a high-shear agitation to selectively agglomerate the chalcopyrite and to leave the siliceous gangue dispersed in aqueous phase. The agglomerates were then separated from dispersed gangue minerals by screening and the agglomerates dispersed in a hydrophobic liquid (n-pentane) to liberate the water trapped in the agglomerates. The chalcopyrite dispersed in the hydrophobic liquid was separated from the medium to obtain a concentrate substantially free of gangue minerals and moisture. The copper recoveries were substantially higher than those obtained by flotation. The HHS process was also tested on ultrafine mono-sized silica beads. The results were superior to those obtained by flotation, particularly with ultrafine particles. The HHS process has also been tested successfully for upgrading subbituminous coals. Low-rank coals are not as hydrophobic as high-rank coals such as bituminous and anthracite coals. In the present work, a low-rank coal from Wyoming was hydrophobized with appropriate reagents and subjected to the HHS in a similar manner as described for processing copper. The results showed that the HHS process reduced the moisture substantially and increased the heating value up to 50% without heating the coal. Laboratory-scale tests conducted under different conditions, e.g., particle size, reagent type, reaction time, and pretreatments, showed promising results. Implementation for the HHS process for upgrading low-rank coals should help reduce CO2 emissions by improving combustion efficiencies. / Master of Science

New Economic Geography (NEG) models do not typically account for the presence of regions other than the ones involved in the integration process. We explore such a possibility in a Footloose Entrepreneur (FE) model aiming at studying the stability properties of long-run industrial location equilibria. We consider a world economy composed by a customs union of two regions (regions 1 and 2) and an "outside region" which can be regarded as the rest of the world (region 3). The effects of economic integration on industrial agglomeration within the customs union are studied under the assumption of a constant distance between the customs union itself and the third region. The results show that higher economic integration does not always implies the standard result of full agglomeration of FE models. This incomplete agglomeration outcome is due to the fact that the periphery region keeps a share of industrial activities in order to satisfy a share of "external demand". That is, the deindustrialization process brought about by economic integration in the periphery of the union is mitigated by the demand of consumers living in the rest of the world. In general, the market size of the third region affects the number of the long-run equilibria, as well as their stability properties. In addition to the standard outcomes of FE models, we describe the existence of two asymmetric equilibria characterised by unequal distribution of firms between regions 1 and 2, with no full agglomeration though. Interestingly, these equilibria are stable and therefore can be regarded as a likely long-run equilibrium state of the economy. (author's abstract) / Series: Department of Economics Working Paper Series