Master of Science / Civil Engineering / Hani G. Melhem / Bill Zhang / Composite action is the joint behavior of two elements connected or bonded together. It is a phenomenon that is utilized in several applications throughout engineering. Previous studies have shown that cold formed steel (CFS) sheathed with structural wood panels exhibits a degree of partial composite action behavior. However currently in the design process, CFS and wood sheathing systems are considered separately in a non-composite manner due to the absence of sufficient supporting data. These systems can include the floors, roofs, and walls of a building. In order to determine the level of composite action present, the slip modulus is needed. The slip modulus describes the relationship between the shear force and the displacement exhibited by two elements in a composite system. The scope of this research is to determine the influence of fastener spacing on the slip modulus and provide a foundation of information to fully define the composite action between CFS and wood sheathing.

Master of Science / Department of Agronomy / Tesfaye Tesso / Cold temperature stress is an important abiotic constraint to grain sorghum production in temperate regions. In the United States, low temperature in late spring and early fall has limited sorghum production to a narrow growing period. Deployment of cold tolerance traits may widen this window and hence contribute to increased production. The objectives of this study were (1) to determine the effect of early and mid-season cold temperature stress on growth, phenology and yield components of sorghum, and identify key traits that are most sensitive to cold stress at seedling and flowering stages, and (2) to identify new sources of cold tolerance for use in breeding programs. Series of controlled environment (greenhouse/growth chamber) and field experiments were carried out. Three sorghum genotypes of variable response, Shan Qui Red (tolerant), SRN39 (susceptible) and Pioneer 84G62 (unknown) were subjected to cold (15/13ºC day/night) and normal (25/23ºC day/night) temperature at seedling (Experiment I) and flowering (Experiment II) stages. The genotypes were planted in a greenhouse using a 5L polytainer pots. Each pot consisted of a single plant and each plot was represented by three pots. A split-plot design with three replications was used in both experiments with temperature regimes as main plots and genotypes as sub-plots. Three days after emergence, experiment I plants were moved to the growth chamber and subjected to the designated temperature treatments. For experiment II, the treatments were assigned at heading stage immediately before anthesis had begun. The treatments lasted 10 d in both experiments. Data were collected on seedling characteristics and leaf chlorophyll content in experiment I, days to flowering, maturity, and yield components in both experiments, and anthesis duration in experiment II. For the field experiment, 150 sorghum germplasm collections of potential cold tolerance along with tolerant and susceptible checks were evaluated for emergence and seedling traits under early planting (April 13) at soil temperature of 20.1/13.4 ºC max/min. The normal temperature treatment was applied by planting at regular season (May 26) at soil temperature of 30.0/20.4ºC max/min. Twenty-four genotypes selected based on field emergence and seedling vigor were further screened under controlled environment. Early-season stress significantly reduced leaf chlorophyll content, all seedling traits (height, vigor and dry weight), and also delayed flowering and maturity. But it had no effect on final leaf number, plant height and yield components. Genotypic response to early stress was significant for all traits with the susceptible checks having the lowest score for all seedling traits. Mid-season cold stress prolonged anthesis duration, delayed maturity and highly reduced all yield components. Several genotypes among the 150 had higher seedling vigor and emergence than the tolerant check, Shan Qui Red. In conclusion, reduced seedling vigor as a result of early stress had no effect on final yield provided that stand establishment was not compromised while mid season stress is damaging to yield. The wide genetic variation for the traits indicates the potential for improvement of cold tolerance in sorghum.

Manufacturing in modern society has taken on a different role than in previous generations. Today’s manufacturing processes involve many different physical phenomenon working in concert to produce the best possible material properties. It is the role of the materials engineer to evaluate, develop, and optimize applications for the successful commercialization of any potential materials. Laser-assisted cold spray (LACS) is a solid state manufacturing process relying on the impact of supersonic particles onto a laser heated surface to create coatings and near net structures. A process such as this that involves thermodynamics, fluid dynamics, heat transfer, diffusion, localized melting, deformation, and recrystallization is the perfect target for developing a data science framework for enabling rapid application development with the purpose of commercializing such a complex technology in a much shorter timescale than was previously possible. A general framework for such an approach will be discussed, followed by the execution of the framework for LACS. Results from the development of such a materials engineering model will be discussed as they relate to the methods used, the effectiveness of the final fitted model, and the application of such a model to solving modern materials engineering challenges.

Dans les année récentes, les systèmes d'atomes froids ont été reconnus comme des outils prometteurs pour réaliser des simulateurs quantiques, ainsi que pour différentes applications en information quantique. Parmi eux notamment la jonction Josephson bosonique, un système de bosons ultrafroids dilués pouvant occuper deux modes, a été employée pour réaliser un interféromètre atomique, qui a permi d'estimer un déphasage avec une précision dépassant la limite classique. Dans cette thèse, nous étudions d'un point de vue théorique la production, la détection et la décohérence d'états intriqués qui peuvent être utilisés pour l'interférométrie de haute précision dans une jonction Josephson bosonique. Parmi ces états quantiques utiles se trouvent les états comprimés et les superpositions macroscopiques d'états cohérents. Dans la première du manuscrit, nous démontrons que les superpositions macroscopiques d'états cohérents peuvent être créées pendant la dynamique qui suit un arrêt soudain du couplage entre les deux modes de la jonction, puis nous étudions des protocoles de détection expérimentale. Il existe inévitablement dans chaque expérience des sources de bruit, les principaux étant le bruit de phase, induit par des fluctuations des énergies des deux modes, et la perte d'atomes. La présence de bruit induit de la décohérence et dégrade les corrélations quantiques des états manipulés. Dans la deuxième partie du manuscrit nous analysons en détail la façon dont les corrélations quantiques utiles des états comprimés et des superpositions macroscopiques sont dégradées par le bruit de phase. Nous montrons que, pour des intensités de bruit modérées, les superpositions d'états cohérents à plusieurs composantes sont des candidats intéressantes pour l'interférométrie de précision. Enfin, nous étudions l'effet de la perte d'atomes sur la formation des superpositions macroscopiques, en montrant comment la décohérence agit sur la matrice densité du système / In recent years, cold atomic systems have been recognized as very promising tools for quantum simulators and for applications in quantum technology. In particular, a Bose Josephson junction (BJJ) - a system of ultracold dilute bosons which can occupy two modes - has been used to realize an atomic interferometer, allowing to estimate a phase shift with a precision beyond the classical limit. In this thesis we study theoretically the production, detection and decoherence of entangled states which can be used for high-precision interferometry in a Bose Josephson junction. Among such useful quantum states are atomic squeezed states and macroscopic superpositions of coherent states. In the first part of the thesis, after demonstrating that macroscopic superpositions of coherent states can be created during the dynamics following a "quench" of the coupling between the two modes of the junction, we study protocols for their experimental detection. In the experiments there are unavoidable sources of noise, the major sources being phase noise, induced by stochastic fluctuations of the energies of the two modes of the BJJ, and particle losses. The presence of noise induces decoherence and degrades the quantum correlations of these states. In the second part of the thesis we analyze in detail how the useful quantum correlations of squeezed states and macroscopic superpositions are degraded by phase noise. We show that for moderate phase noise intensities multicomponent superpositions of coherent states are interesting candidates for high-precision atom interferometry. Finally, we address the effect of atom losses on the formation of macroscopic superpositions, showing how decoherence affects the system density matrix.

The success of Chinese foreign policy since 1949 can be demonstrated empirically in terms of core national interests defined by the realist international relations perspective: state sovereignty, territorial integrity, and socioeconomic development. Influential realist writers, however, fail to consistently identify or explain the success of Chinese foreign policy, despite the work of area specialists who suggest that Chinese foreign policy displays consistent and effective, strategic patterns of force. Strategic thought arises from culturally differing ontological, epistemological and methodological assumptions, as modified within specific historical conditions. Using the theoretical approach of comparative strategic culture, an abstract conceptual framework is developed for philosophical analysis of western and Chinese strategic culture. Classical and contemporary western realist-strategic paradigms coexist in theoretical and practical tension, resulting in a western strategic ethnocentrism which explains realist failure to recognize Chinese strategic patterns in foreign policy. Chinese philosophical assumptions, reinforced in linguistic structure, create a culturally paradigmatic approach to strategic thought, modified by the modern historical context of civil/national wars and state-building. The modern Chinese strategic paradigm of protracted war is characterized by the mutually constitutive relationship between the military and political dimensions of force, and by a cumulative, discontinuous pattern of foreign policy and state-building, in which force is created, stored, and applied over space and time. / Graduate

After reaching its light-off temperature, the catalytic aftertreatment system plays a major part in maintaining emissions at low levels for vehicles equipped with combustion engines. In this thesis, modelling of the exhaust gas temperature is investigated along with optimal control strategy for variable ignition and exhaust valve opening angles for optimal catalytic converter heating. Models for exhaust gas temperature and mass flow are presented and validated against measurement data. According to the model validation, the proposed models capture variations in ignition and exhaust valve opening angles well. Optimal control strategy for the ignition and exhaust valve opening angles to heat the catalytic converter to a predetermined temperature in the most fuel and time optimal ways are investigated by implementation of the validated models. Optimal control analysis indicates that with open wastegate, the heating time for the catalytic converter can be reduced by up to 16.4 % and the accumulated fuel to reach the desired temperature can be reduced by up to 4.6 %, compared to the case with ignition and exhaust valve opening angles fixed at nominal values. With closed wastegate the corresponding figures are 16.4 % and 4.7 %. By also including control of the variable λ-value, the heating time can be further reduced by up to 19.8 %, and the accumulated fuel consumption by up to 9.5 % with open wastegate. With closed wastegate the corresponding figures are 20.1 % decrease in heating time, and 9.8 % decrease in accumulated fuel consumption.

Thesis advisor: Michael J. Himes / Reinhold Niebuhr is among the most politically and theologically influential--and most misunderstood--American thinkers of the twentieth century. This misunderstanding is the product of a tendency among Niebuhr's admirers and critics alike to overlook the elaborate interplay of the theology and politics in Niebuhr's thought. I argue that Niebuhr understood himself as a preacher to religion's "cultured despisers," and that Niebuhr construed this role in fundamentally theological terms. As a consequence, there is a dynamic theology underlying his political engagement with the broader culture. Chief among the "cultured despisers" drawn to Niebuhr's thought were the political realists who dominated early Cold War politics. They were particularly compelled by the political insights of Niebuhr's Christian Realism, and proceeded to incorporate these insights into own realist visions. I argue that in the act of appropriating Niebuhr the political realists unwittingly absorbed much of his theology; and in neglecting to recognize the theological underpinnings to Niebuhr's political insights, they ended up misconstruing Niebuhr in important ways. I seek to demonstrate that fully appreciating Niebuhr's contributions to political discourse requires an awareness of how theology suffuses even his most overtly political writings. This project consists of two parts. Part One examines the theological formation of the concept at the heart of Niebuhr's Christian Realism: namely, the doctrine of original sin. From the outset, Niebuhr maintained that elaborating the full political implications of original sin required a theological structure. Through sustained conversations with theological contemporaries Karl Barth, Paul Tillich, Emil Brunner, and his brother H. Richard Niebuhr, Reinhold elaborated the distinctive theological anthropology, understanding of grace and redemption, and account of the dynamic interplay between faith and history underlying his exploration of original sin and its political implications. Niebuhr's Christian Realism, I suggest, is inextricably theological. Part Two analyses Niebuhr's reception among three of the most prominent midcentury political realists: Hans Morgenthau, George Kennan, and Arthur Schlesinger. Although they were among Niebuhr's most astute interpreters, all three figures wrongly presumed that they could extricate the political elements of Niebuhr's thinking on original sin from the theological structure in which this thinking was embedded, and import only these political elements into their own realist visions. Their uses of the concept of original sin indicate that they both adopt far more of Niebuhr's theology than they ever intended to, and misconstrue some of his most profound insights. I close by considering what a theologically grounded Christian Realism has to offer political discourse. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Theology.

Additive manufacturing technologies place materials at the direct point of need of the warfighter, enabling the development of optimal, situation-specific means to produce and repair parts of Army and DoD weapons systems. In the case of solid-state AM, a full understanding of the metallic powder is critical with producing ideal consolidated material properties reliably and repeatably. By way of iteratively coupling computational models with supportive experimental testing, one can rapidly archetype differences in processing methods, alloy compositions, and heat treatments for metallic powders that serve as feedstock for these AM technologies. Through the combination of thermodynamic models, advanced characterization, and dynamic nano-indentation, representative correlations are established between microstructural features and mechanical properties, enabling the development of enhanced feedstock materials that can achieve the specific needs of the warfighter efficiently without forfeiting quality. This represents both a holistic and a materials-by-design approach to AM through the deliberate use of computation to drive down the discovery process and allow feedstock powders to be engineered with specific properties dictated by Army requirements for performance. In a case study of Al 6061, unique observations were made through the combination of modeling and experimentation. It was discovered that the precipitation kinetics were greatly accelerated in powders and therefore, typical heat treatment processes used for cast-aluminum alloys were not valid. Due to this shift in precipitation sequences, high-temperature treatment was limited to discourage precipitate and grain coarsening. Additionally, when compared to typical cast Al 6061, the main precipitation hardening phase shifts from Mg2Si to Al4Cu2Mg8Si7, changing how aging mechanisms were accounted for. These conclusions were supported by both the computational models and experimental results. Through the generation of numerous data, the models were calibrated, enabling more efficient and precise development of tailored material characteristics from specific microstructural features to serve as an input in a holistic through-process model for a solid-state AM process and guide future experimentation.

Neste trabalho nós produzimos um plasma neutro ultrafrio de 85Rb através da fotoionização dos átomos aprisionados em uma armadilha magneto-óptica. Medimos o número de partículas que evaporam do plasma no momento de sua criação usando a técnica de tempo-de-vôo. A partir disto realizamos o estudo da taxa de evaporação com relação a energia cinética inicial do elétron fornecida ao sistema, onde para isto criamos o plasma com diferentes comprimentos de onda do laser de fotoinização. Nossos resultados indicam que conforme fornecemos mais energia ao sistema mais partículas evaporam e constatamos que está de acordo com a literatura. Interpretamos o resultado com um modelo analítico que considera a distribuição de energia de Maxwell-Boltzmann e encontramos a temperatura do plasma com relação a temperatura inicial dos elétrons / In this work we produced an ultracold neutral plasma of 85Rb formed by the photoionization of laser-cooled atoms. We measured the number of particles evaporated from the plasma in the moment of its formation using the time-of-flight technique. After this, we studied the evaporation rate as a function of the initial electron kinetic energy, for this we created the plasma at different wavelengths of the photoinization laser. Our results indicate that as we supplied more energy to the system more particles evaporate and we verified that it is in agreement with the literature. We interpreted the result with an analytic model that considers the Maxwell-Boltzmann energy distribution and we found the plasma temperature as a function initial electron temperature

Non-compensable cold exposure represents a potentially deadly threat to humans, as we lack highly specialized organs and mechanisms necessary to maintain our optimal core temperature of ~37°C. Repeated exposures to cold have been shown to induce protective physiological changes in cold responses through a process known as cold acclimatization (natural) or acclimation (in laboratory). The purpose of this thesis was to determine what physiological changes occur following an intense 7 day, 14°C cold water immersion acclimation protocol, during both non-compensable (Chapter 2) and compensable cold exposures (Chapter 3). This includes identifying changes in the contributions of the shivering (ST) and non-shivering (NST) thermogenic pathways to overall heat production. ST and NST changes were quantified via electromyography and indirect calorimetry, respectively. This 7 day cold water acclimation protocol resulted in a decrease in cooling rate, a significant increase in mean esophageal core temperature, a decrease in peak heart rate following immersion, and increased thermal comfort from day 1 to day 7 of the 1h 14°C cold water immersions. Further to these findings, changes in ST and NST were measured pre- and post-acclimation with a standardized compensable cold protocol using a liquid conditioned suit (LCS) which lowered Tskin to 26°C for 2.5h. The cold acclimation protocol resulted in a ~38% decrease in mean shivering over the 2.5h without any change in thermogenic rate from pre- to post-cold acclimation. In addition, no significant difference in fuel selection was observed. These results indicate that the short, intense cold acclimation protocol did result in a substantial change in the contribution of ST and NST to total heat production which could increase cold tolerance by reducing involuntary muscle contractions during ST.