VictorJuiz/thesis huggingface dataset:
Spray Combustion Characteristics and Emissions of a Wood derived Fast Pyrolysis Liquid-ethanol Blend in a Pilot Stabilized Swirl Burner

Biomass fast pyrolysis liquid (bio-oil) is a cellulose based alternative fuel with the potential to displace fossil fuels in stationary heat and power applications. To better understand the combustion behavior and emissions of bio-oil, a 10 kW spray burner was designed and constructed. The effect of swirl, atomization quality, ignition source (pilot) energy, air/fuel preheat and equivalence ratio on the stability and emissions of bio-oil spray flames was investigated. A blend of 80% pyrolysis liquid and 20% ethanol by volume was used during the tests and the results were compared to burner operation with diesel. It is important to have good atomization, thorough mixing and high swirl in order to stabilize ignition, promote the burnout of bio-oil and decrease CO, hydrocarbon and particulate matter emissions. The total amount of primary air and atomizing air that can be used to improve turbulence, mixing, droplet burnout and overall combustion quality is limited by the distillable fraction and narrow lean blow-out limit associated with pyrolysis liquid. Air and fuel preheat are important for reducing hydrocarbon and CO emissions, although subsequent fuel boiling should be avoided in order to maintain flame stability. The NOx produced in bio-oil flames is dominated by the conversion of fuel bound nitrogen. The particulate matter collected during bio-oil combustion is composed of both carbonaceous cenosphere residues and ash. Under good burning conditions, the majority consists of ash. Pilot flame energy and air/fuel preheat have a weak effect on the total particulate matter in the exhaust. Generally, these results suggest that available burner parameters can be adjusted in order to achieve low hydrocarbon, CO and carbonaceous particulate matter emissions when using pyrolysis liquid. Total particulates can be further mitigated by reducing the inherent ash content in bio-oil. Comparative burner tests with diesel reveal much lower emissions for this fuel at most of the operating points considered. This is due to the fully distillable nature, better atomization and improved spray ignition characteristics associated with diesel. Because of its superior volatility, diesel can also operate over a much wider range of primary air and atomizing air flow rates compared to bio-oil.

Keywords: spray combustion
fast pyrolysis liquid
pyrolysis oil
bio-oil
swirl burner
CO emissions
NOx emissions
particulate emissions
Advisor: Thomson, Murray J.
Structural Change and Income Differences

Economic growth and development is intimately related to the decline of agriculture’s share of output and employment. This process of structural change has important implications for income and productivity differences between regions within a country or between countries themselves. Agriculture typically has low productivity relative to other sectors and this is particularly true in poor areas. So, as labour switches to nonagricultural activities or as agricultural productivity increases, poor agriculturallyintensive areas will benefit the most. In this thesis, I contribute to a recent and growing line of research and incorporate a separate role for agriculture, both into modeling frameworks and data analysis, to examine income and productivity differences. I first demonstrate that restrictions on trade in agricultural goods, which support inefficient domestic producers, inhibit structural change and lower productivity in poor countries. To do this, I incorporate multiple sectors, non-homothetic preferences, and labour mobility costs into an Eaton-Kortum trade model. With the model, I estimate productivity from trade data (avoiding problematic data for poor countries that typical estimates require) and perform a variety of counterfactual exercises. I find import barriers and labour mobility costs account for one-third of the aggregate labour productivity gap between rich and poor countries and for nearly half the gap in agriculture. Second, moving away from international income differences, I use a general equilibrium model of structural transformation to show a large labour migration cost between regions of the US magnifies the impact improved labour markets have on regional convergence. Finally, I estimate the influence of structural change on convergence between Canadian regions. I construct a unique dataset of census-division level wage and employment levels in both agriculture and nonagriculture between 1901 and 1981. I find convergence is primarily due to region-specific factors with structural change playing little role.

Keywords: Structural Change
International Trade
Food Problem
Convergence
Advisor: Zhu, Xiaodong
Understanding the Mechanisms of Motor Learning in the Vestibulo-ocular Reflex

The vestibulo-ocular reflex (VOR) is a simple reflex that stabilizes gaze by moving the eyes in the opposite direction to the head. The gain of the VOR (ratio of head to eye velocity) can be increased or decreased during motor learning. It is thought that the memory for learned changes in the VOR gain is initially encoded within the cerebellar flocculus. Furthermore, these learned gain changes can be disrupted or consolidated into a long-term memory. In this thesis we describe novel results that show that consolidation of the VOR can take place rapidly, within 1 hour after learning has stopped. Furthermore, we demonstrated that unlike learning, which has been shown to have frequency selectivity, disruption and rapid consolidation generalize across the range of frequencies. We suggest that disruption and rapid consolidation in the VOR are local mechanisms within the cerebellar cortex, and do not require new learning. This thesis also provides additional evidence for the idea that learned gain increases and decreases are the result of separate mechanisms, most likely long-term depression and potentiation respectively, at the parallel fibre-Purkinje cell synapses. We demonstrate that learned gain increases, but not decreases, require the activation of type 1 metabotropic glutamate receptors (mGluR1) and B type γ-aminobutyric acid (GABAB) receptors. Blocking one or both of these receptors with an antagonist inverts gain-up learning, while the agonist augments gain-up learning. Furthermore, we provide novel evidence that these receptors are co-activated during gain-up learning.

Keywords: VOR
cerebellum
motor learning
vestibulo-ocular reflex
Advisor: Broussard, Dianne
The Cuntz Semigrop of C(X,A)

The Cuntz semigroup is an isomorphism invariant for C*-algebras consisting of a semigroup with a compatible (though not algebraic) ordering. Its construction is similar to that of the Murray-von Neumann semigroup (from which the ordered K_0-group arises by the Grothendieck construction), but using positive elements in place of projections. Both rich in structure and sensitive to subtleties of the C*-algebra, the Cuntz semigroup promises to be a useful tool in the classification program for nuclear C*-algebras. It has already delivered on this promise, particularly in the study of regularity properties and the classification of nonsimple C*-algebras. The first part of this thesis introduces the Cuntz semigroup, highlights structural properties, and outlines some applications. The main result of this thesis, however, contributes to the understanding of what the Cuntz semigroup looks like for particular examples of (nonsimple) C*-algebras. We consider separable C*-algebras given as the tensor product of a commutative C*-algebra C_0(X) with a simple, approximately subhomogeneous algebra A, under the regularity hypothesis that A is Z-stable. (The Z-stability hypothesis is needed even to describe of the Cuntz semigroup of A.) For these algebras, the Cuntz semigroup is described in terms of the Cuntz semigroup of A and the Murray-von Neumann semigroups of C(K,A) for compact subsets K of X. This result is a marginal improvement over one proven by the author in [Tikuisis, A. "The Cuntz semigroup of continuous functions into certain simple C*-algebras." Internat. J. Math., to appear] (there, A is assumed to be unital), although improvements have been made to the techniques used. The second part of this thesis provides the basic theory of approximately subhomogeneous algebras, including the important computational concept of recursive subhomogeneous algebras. Theory to handle nonunital approximately subhomogeneous algebras is novel here. In the third part of this thesis lies the main result. The Cuntz semigroup computation is achieved by defining a Cuntz-equivalence invariant I(.) on the positive elements of the C*-algebra, picking out certain data from a positive element which obviously contribute to determining its Cuntz class. The proof of the main result has two parts: showing that the invariant I(.) is (order-)complete, and describing its range.

Keywords: C*-algebras
the Cuntz semigroup
Advisor: Elliott, George Arthur
Slice Sampling with Multivariate Steps

Markov chain Monte Carlo (MCMC) allows statisticians to sample from a wide variety of multidimensional probability distributions. Unfortunately, MCMC is often difficult to use when components of the target distribution are highly correlated or have disparate variances. This thesis presents three results that attempt to address this problem. First, it demonstrates a means for graphical comparison of MCMC methods, which allows researchers to compare the behavior of a variety of samplers on a variety of distributions. Second, it presents a collection of new slice-sampling MCMC methods. These methods either adapt globally or use the adaptive crumb framework for sampling with multivariate steps. They perform well with minimal tuning on distributions when popular methods do not. Methods in the first group learn an approximation to the covariance of the target distribution and use its eigendecomposition to take non-axis-aligned steps. Methods in the second group use the gradients at rejected proposed moves to approximate the local shape of the target distribution so that subsequent proposals move more efficiently through the state space. Finally, this thesis explores the scaling of slice sampling with multivariate steps with respect to dimension, resulting in a formula for optimally choosing scale tuning parameters. It shows that the scaling of untransformed methods can sometimes be improved by alternating steps from those methods with radial steps based on those of the polar slice sampler.

Keywords: adaptive Markov chain Monte Carlo
adaptive MCMC
slice sampling
crumb framework
Advisor: Neal, Radford
MSE-based Linear Transceiver Designs for Multiuser MIMO Wireless Communications

This dissertation designs linear transceivers for the multiuser downlink in multiple-input multiple-output (MIMO) systems. The designs rely on an uplink/downlink duality for the mean squared error (MSE) of each individual data stream. We first consider the design of transceivers assuming channel state information (CSI) at the transmitter. We consider minimization of the sum-MSE over all users subject to a sum power constraint on each transmission. Using MSE duality, we solve a computationally simpler convex problem in a virtual uplink. The transformation back to the downlink is simplified by our demonstrating the equality of the optimal power allocations in the uplink and downlink. Our second set of designs maximize the sum throughput for all users. We establish a series of relationships linking MSE to the signal-to-interference-plus-noise ratios of individual data streams and the information theoretic channel capacity under linear minimum MSE decoding. We show that minimizing the product of MSE matrix determinants is equivalent to sum-rate maximization, but we demonstrate that this problem does not admit a computationally efficient solution. We simplify the problem by minimizing the product of mean squared errors (PMSE) and propose an iterative algorithm based on alternating optimization with near-optimal performance. The remainder of the thesis considers the more practical case of imperfections in CSI. First, we consider the impact of delay and limited-rate feedback. We propose a system which employs Kalman prediction to mitigate delay; feedback rate is limited by employing adaptive delta modulation. Next, we consider the robust design of the sum-MSE and PMSE minimizing precoders with delay-free but imperfect estimates of the CSI. We extend the MSE duality to the case of imperfect CSI, and consider a new optimization problem which jointly optimizes the energy allocations for training and data stages along with the sum-MSE/PMSE minimizing transceivers. We prove the separability of these two problems when all users have equal estimation error variances, and propose several techniques to address the more challenging case of unequal estimation errors.

Keywords: Multiuser downlink
Broadcast channel
Multiple antenna
MIMO systems
Optimization
Convex optimization
Numerical Optimization
Nonlinear programming
Information rates
Diversity methods
Minimum mean squared error
Least mean squares
Linear precoder design
Uplink / downlink duality
Channel estimation and training
Channel feedback
Advisor: Adve, Raviraj
Search for Wt-channel Single Top Quark Production in 7 TeV Proton-proton Collisions using the ATLAS Detector

The production of single top quarks through the weak interaction is of great interest in particle physics, as it provides the only means to directly measure the CKM matrix element |Vtb|, one of the few remaining Standard Model parameters which has yet to be precisely constrained by direct experimental measurements. This thesis describes a search for Wt-channel single top quark production using proton-proton collision data collected at a center-of-mass energy of 7 TeV by the ATLAS detector at the Large Hadron Collider, corresponding to a total integrated luminosity of 35 pb-1. Collision events having exactly two oppositely-charged electrons or muons, a single high-transverse-momentum jet, and large missing or total transverse energy are selected, resulting in a sample with enhanced single top purity. 38 data events are found to survive the selection, in good agreement with the expected sum from all signal and background predictions of 38.6 ± 6.0. The Wt content of the selected sample is predicted to amount to 4.3 ± 0.3 events. The resulting cross-section measurement is 10 +20-10 (stat) +20-10 (syst) pb. As this level of precision is insufficient to claim evidence or discovery of this process, an upper limit is also derived for the parameter of interest, resulting in σ(pp→Wt) < 70 pb at 95% confidence level.

Advisor: Trischuk, William
A Multifaceted Examination of the Central Processes Underlying Vestibular Compensation

The vestibular system provides us with sensory information that is essential for maintaining balance and stability. When sensory input is lost due to unilateral vestibular damage (UVD), our ability to maintain stable gaze and posture becomes compromised. Over time, vestibular function is partially restored through a process known as vestibular compensation, which is associated with the rebalancing of activity in the vestibular nuclear complex (VNC) of the brainstem. However, the physiological mechanisms associated with vestibular compensation remain elusive. We addressed several different experimental objectives pertaining to plasticity and sensory adaptation associated with vestibular compensation. First, we demonstrated that systemic manipulation of γ-amino-butyric acid type B (GABAB) receptors altered the course of vestibular behavioural recovery within the first several hours after UVD. Second, we showed that immunohistochemical labeling of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluR4 was elevated in the VNC on the intact compared to lesioned side acutely following UVD. Third, we produced preliminary data suggesting that excitatory responses to vestibular nerve stimulation may be acutely potentiated by UVD on the intact side. Finally, we established that rapid sensory adaptation may increase the dynamic ranges of vestibular neurons and perhaps improve limited vestibular reflex function in the long term. Acutely following UVD, potentiation of vestibular nerve synapses appear to be associated with an increase in GluR4 subunit expression in the contralesional VNC. Also, such potentiation could be enhanced by acute modifications in pre-synaptic GABAB receptor activation. In the long term, and independent of these plastic changes, sensory adaptation may enable the vestibular system to overcome the persistent limitations imposed by UVD.

Keywords: vestibular
neuron
Advisor: Broussard, Dianne
Surviving the Sasachacuy Tiempu [Difficult Times]: The Resilience of Quechua Women in the Aftermath of the Peruvian Armed Conflict

Resilience and post trauma responses often coexist, however, for the past decades, the trauma paradigm has served as the dominant explanatory framework for human suffering in post-conflict environments, while the resilience of individuals and communities affected by mass violence has not been given equal prominence. Consequently, mental health interventions in post-conflict zones often fail to respond to local realities and are ill equipped to foster local strengths. Drawing primarily from trauma, feminist and structural violence theories, this study strengthens understanding of adult resilience to traumatic exposure by examining the resilience of Quechua women in the aftermath of the political violence in Peru (1980-2000), and their endurance of racially and gender-targeted violence. The study uses a cross sectional survey to examine the resilience and posttraumatic responses of 151 Quechua women. Participants were recruited from an urban setting and three rural villages in Ayacucho, Peru. The study examines the associations between resilience, past exposure to violence, current life stress and post-trauma related symptoms as well as the individual and community factors associated with the resilience of Quechua women. In doing so, this study makes a unique contribution by simultaneously examining posttraumatic responses and resilience in a post-conflict society, an area with a dearth of research. Results indicate that resilience was not associated with overall posttraumatic stress related symptoms, but instead higher resilience was associated with lower level of avoidance symptoms and therefore with lesser likelihood of chronic symptoms. Findings also demonstrate that enhanced resilience was associated with women’s participation in civic associations, as well as being a returnee of mass displacement. Lower resilience was instead associated with lower levels of education, absence of income generated from a formal employment and the experience of sexual violence during the conflict. These results were triangulated with qualitative findings, which show that work, family, religion, and social participation are enhancing factors of resilience. The study highlights the courage and resilience of Quechua women despite persistent experiences of everyday violence. The importance to situate trauma and resilience within historical processes of oppression and social transformation as well as other implications for social work practice and research are discussed.

Keywords: resilience
posttrauma responses
political violence
indigenous women
gender based violence
Advisor: Williams, Charmaine
Experiencing Everyday Prejudice of a Concealabe Stigma: Jews in a non-Jewish World

Dion (2001) observed that being the target of stigma and prejudice has a “demonstrable, negative effect upon the individual.” While blatant prejudice has lessened there has been little change in the rate of subtle forms of stigma and prejudice (Wilson, 1996). Recent trends in the literature acknowledge the importance of everyday reminders of difference or prejudice for women, racial minorities and ethnic groups (Swim, 2003). Jews with a long history as targets of stigma, prejudice and discrimination are an excellent example of a modern concealable stigma. Previous research into the Jewish experience has been influenced by concerns about group survival and has not included specific investigation of the experience of the target of stigma in interaction with perpetrators. Using a qualitative life history methodology this research sheds light on the experience of minority group members with a concealable stigma. Jewish adults with diverse backgrounds were interviewed using a semi-structured life history approach. The first layer of analysis identified six overarching themes – unshakeable loyalty to Jewish identity; importance of belonging; living Jewishness in a way that is meaningful; concerns about visibility of Jewishness; concerns about personal and group vulnerability including references to the Holocaust; and everyday encounters with prejudice. These themes share commonalities with Fiske’s (2004) social needs expressed in a Jewish context. The second layer of analysis developed a model of an encounter with everyday prejudice. This model identifies the overriding importance of contextual influences on perceptions of an encounter in turn influencing the reaction and response. Following the example of Miller and Kaiser (Miller, 2006; 2001b), these encounters are seen as stressful events which can be understood using the framework of the stress and coping model (Lazarus & Folkman, 1984). The results show the subtle but important impact of everyday prejudice. As well as providing a means of understanding the experience of these individuals the results have implications for both therapeutic and psychoeducational interventions.

Keywords: social psychology
stigma
prejudice
everyday prejudice
concealable stigma
Jews
Judaism
anti-semitism
qualitative methodology
life history method
Advisor: Cole, Ardra