Transfer between community colleges and four-year institutions has become more common as student mobility increases. Accordingly, the higher education system has coped with the fluidity by establishing articulation agreements that facilitate pathways from one institution to another. The forward-facing policies and guides to inform students on those pathways are known to be complicated, leading to the development of web-based tools like Transferology to help students navigate the system. Still, credit loss is common, whether through misunderstandings, lack of awareness, or changing degree plans. A proliferation of literature examines the experiences of transfer students and other agents in the process like community college advisors, but few pieces interrogate the underlying website structures that facilitate those experiences as the unit of analysis. Information related to facilitating transfer from one institution to another is often fragmented across multiple webpages or policies and uses language not optimal for communicating with students – creating what are called "information asymmetries" between the students and institutions. The premise of an exchange having information asymmetries is that one or more parties in the exchange have more or better information than the others, leading to an imbalance in power. In the case of higher education, transfer students – and their advisors by extension – can be subjected to manipulation by the invisible hands of the four-year institutions through language gaps and scattered sources of information. Accordingly, this dissertation explored four-year university websites, a major point of contact students have with information on transfer, to address the following main research question: "How are information asymmetries in curricular policies/procedures apparent for engineering students on institutional webpages in terms of language and fragmentation?" The subsequent research question synthesized the results of the first question: "Looking across information asymmetry measures, what are the different narratives of information asymmetry that integrate themes of language and fragmentation across institutions?" A fully integrated mixed methods design using all existing data was employed to address the two research questions. A stratified random sample was taken with respect to institution size based on their Carnegie classifications (n = 38). The collection of relevant public webpages based on a set of keywords from the sampled institutions was transformed into three network measures - hierarchy, centrality, and nonlinear – that were used in cluster analyses to group the institutions based on their information structures. Sequential mixed methods sampling was used to choose institutions purposefully from each cluster based on notable features recorded during the first stage of data collection. Two-cycle coding followed the cluster analysis by elaborating on the networks formed during data collection. I used joint displays to organize the networks and In-Vivo codes in the same picture and develop themes related to fragmentation and language simultaneously. K-means and K-medoids cluster methods both produced the same four cluster solution illustrating one aspect of information asymmetries through fragmentation. The clustering solution highlighted four major network patterns, plus one cluster mixing two of the patterns: 1) linear browsing, 2) centralized expansive browsing, 3) branched browsing, and 4) mixed browsing. Further qualitative analysis of the sampled institutions revealed several types of missteps where information is obscured through language or dispersed in the network. I explored a subset of 16 institutions and identified four themes related to fragmentation (unlinked divergence, progressive disclosure, lack of uniformity, and neighborhood linking) and six themes related to language (hedging transferability and applicability, legalese handwaving, building rapport, exclusivity, deviance from common practice, and defining terms). The missteps were contextualized further using six narratives with institutional examples. This work characterized the information design for transfer students as a messy web of loosely connected structures with language that complicates understanding. Integrated narratives illustrate a landscape of loosely coupled information structures that become more expansive as state initiatives interact with already existing local agreements. Moreover, institutional websites describing transfer processes use communication strategies similar to private companies writing online privacy policies. In light of the themes of information asymmetries, opportunities for supporting transfer were highlighted. For example, institutions are encouraged to create visual representations of the transfer credit process, ensure terms are defined upfront while minimizing jargon, and avoid linking to information that is easily summarizable on the current page. This research would be of interest to institutions looking to improve the presentation of their transfer information by critically examining their designs for the missteps described here. In addition, engineering education practitioners and researchers studying transfer student pathways and experiences will find the results of interest – especially in considering how to support the students despite the large information gaps. Finally, those looking to implement a fully integrated mixed methods design or use existing/archival data in their own context will find the use of mixing strategies of interest. / Doctor of Philosophy / Transfer between community colleges and four-year institutions has become more common as student mobility increases, especially for engineering. Institutions have coped with this inter-institutional movement by establishing agreements with each other that facilitate pathways between programs. The forward-facing policies and guides to inform students on such pathways are known to be complicated, leading to the development of web-based tools like Transferology to help students navigate the system. Despite these advances, transfer students continue to struggle in their information search. The purpose of this dissertation was to describe the extent to which information for engineering transfer students is scattered across multiple web-based sources and written in a manner not conducive to understanding. I used a fully integrated mixed methods design to create narratives capturing the interactions between the more quantitative idea of scatter using network analysis and the more qualitative aspect of language-use using visually based two-cycle coding across 38 U.S. four-year institutions. All data was readily available online, which were transformed and combined using several mixing strategies to form integrated stories of information asymmetries. The resulting narratives characterized the information design for transfer students as a messy web of loosely connected structures with language that complicates understanding. Moreover, institutional websites describing transfer processes use communication strategies similar to private companies writing online privacy policies. In light of the themes of information asymmetries, opportunities for supporting transfer were highlighted. This work will be of interest to those interested in engineering transfer student experiences and pathways. Also, those looking to implement fully integrated mixed methods approaches or make extensive use of existing data, especially mixing during analysis, will see strategies applicable in their own work.

Afin de générer des plasmas performants sur de longues durées, un tokamak nécessite des dispositifs de chauffage et de génération de courant additionnels. Des antennes haute-fréquences, délivrant des puissances de plusieurs mégawatts au plasma, sont actuellement utilisées dans de nombreux tokamaks. Pour optimiser les performances de chauffage et de génération de courant obtenues avec le système LH (fréquence de quelques gigahertz), une bonne maitrise du couplage de l'onde émise par l'antenne au plasma de bord est nécessaire. Or, des effets non-linéaires dépendant du niveau de puissance HF injectée dans le plasma perturbent fortement le couplage de l'onde LH pour certains paramètres de bord (densité et température en particulier). Les travaux présentés dans ce manuscrit portent sur l'étude du couplage linéaire et non-linéaire de l'onde LH au plasma de bord. Dans le cadre de l'installation d'une antenne dite « Passive Active Multijunction » en 2009 sur le tokamak Tore Supra visant à tester le système LH proposé pour ITER, la caractérisation du couplage obtenu avec cette antenne a été réalisée à partir d'expériences menées à basse puissance sur Tore Supra. Les résultats, analysés conjointement avec l'utilisation d'un code de couplage (ALOHA), ont ainsi validé les prédictions théoriques prévoyant de bonnes propriétés de couplage à des densités de plasma de bord faibles. Par ailleurs, l'effet pondéromoteur a été clairement identifié comme responsable de la forte détérioration du couplage de l'onde mesurée sous certaines conditions de plasma de bord. / In order to achieve long pulse operation with a tokamak, additional heating and current drive systems are necessary. High frequency antennas, which deliver several megawatts of power to the plasma, are currently used in several tokamaks. Moreover, a good control of the coupling of the wave launched by the antenna to the edge plasma is required to optimize the efficiency of heating and current drive LH systems. However, non-linear effects which depend on the level of injected power in the plasma strongly damage the coupling of the LH wave at particular edge parameters (density and temperature profiles). Results presented in the manuscript deal with the study of the linear and non-linear coupling of the LH wave to the plasma. In the framework of the commissioning of the Passive Active Multijunction antenna in 2009 on the Tore Supra tokamak aiming at validating the LH system suggested for ITER, the characterisation of its coupling properties was realized from low power experiments. The experimental results, which are compared with the linear coupling code ALOHA, have valided the theoretical predictions of good coupling at edge plasma density around the cut-off density. Besides, the ponderomotive effect is clearly identified as responsible for the deterioration in the coupling of the wave, which is measured under particular edge plasma conditions. A theoretical model combining the coupling of the LH wave with the ponderomotive force is suggested to explain the experimental observations.

γ-TiAl based alloys have attracted considerable research interest in the past few decades and have gained niche high temperature applications in aero-engines and automobiles. As high temperature structural materials, these alloys require stable microstructures. This thesis aims at addressing knowledge gaps in the understanding of microstructural stability in two technologically important γ-TiAl based alloys in different microstructures, viz. fully lamellar (FL) and duplex. Creep and exposure tests were complemented with a variety of microstructural characterization tools (SEM, EBSD, TEM, XRD). Density functional theory based calculations were also performed to further the understanding of stability of phases. In the first part of the thesis, microstructural stability of a FL microstructure was studied under creep and high temperature exposure conditions. An aim of these studies was to probe the effect of stress orientation with respect to lamellar plates on microstructural changes during primary creep. It was observed that retention of excess α2 resulted in an unstable microstructure and so under stress and temperature, excess α2 was lost. However, depending on stress orientation, the sequence of precipitates formed was different. In particular, for certain stress orientations, the formation of the non-equilibrium C14 phase was observed. The stress dependence of microstructural evolution was found to be stem from internal stresses due to lattice misfit and elastic moduli mismatch between α2 and γ. In the second part of this thesis, microstructural stability of a duplex alloy was probed, with an emphasis on understanding mechanisms that lead to tertiary creep. The as-extruded microstructure consisted of bands of equiaxed grains and lamellar grains. During creep, loss of lamellar grains was observed and this was attended by kinking of laths and formation of dynamically recrystallized equiaxed grains. Significant dislocation activity was seen in both lamellar and equiaxed grains at all stages of creep. Initially, dislocation activity leads to strengthening and primary creep behavior, but at later stages, it triggers dynamic recrystallization. Dynamic recrystallization was found to be the rate controlling creep mechanism. Accelerating creep behavior was due to strain localization during the constant load tensile test resulting from microstructural instabilities such as kinking.

Numerical modeling of several turbulent nonreacting and reacting spray jets is carried out using a fully stochastic separated flow (FSSF) approach. As is widely used, the carrier-phase is considered in an Eulerian framework, while the dispersed phase is tracked in a Lagrangian framework following the stochastic separated flow (SSF) model. Various interactions between the two phases are taken into account by means of two-way coupling. Spray evaporation is described using a thermal model with an infinite conductivity in the liquid phase. The gas-phase turbulence terms are closed using the k-� model. In the classical SSF (CSSF) approach the effects of turbulent velocity fluctuations of the gas-phase are modeled stochastically to obtain instantaneous gas-phase velocity, which subsequently is used to estimate droplet dispersion and interphase transport rates. However, in the CSSF model, no such effort is made to model the effects of the fluctuations in the gas-phase reactive scalars, namely temperature and species mass fractions. Instead, the mean value of these scalars is used while solving for the droplet governing equations and estimating various interphase source terms. Also, in flamelet model and conditional moment closure (CMC) applications of turbulent sprays, the mixture fraction is defined using conventional definition, which is no longer a conserved quantity due to associated phase change. Therefore, in this thesis a novel mixture fraction based FSSF approach is used to stochastically model the fluctuating temperature and composition of the gas phase. These gas-phase reactive scalars are then used to refine the estimates of the heat and mass transfer rates between the droplets and the surrounding gas-phase. It is assumed that the fluctuations in the gas-phase reactive scalars are inherently associated with the fluctuation of a single conserved scalar, namely instantaneous mixture fraction. Instantaneous value of the gas-phase reactive scalars seen by individual droplets is then estimated from the instantaneous gas-phase mixture fraction, which is obtained as the Weiner process by randomly sampling a known beta-function probability density function (PDF) of the local mixture fraction field. Finally, Favre mean value of the gas-phase scalars are recovered as appropriate moments of the PDF. The present definition of the mixture fraction based on its instantaneous value facilitate exact calculation of the source terms in the transport equation for variance of the mixture fraction, whereas conventional definition leads to terms which require further modeling and simplifications. The present FSSF model also accounts for the possibility of existence of an envelope flame between the droplet and the bulk gas-phase, which greatly increases the heat and mass transfer rates to the droplet. The present model allows us to treat the occurrence of envelope flame separately which is otherwise neglected in the conventional spray combustion models. The FSSF model is implemented into a numerical code, and different well-defined nonreacting and reacting turbulent spray jets are investigated. For the reacting spray jets, single-step irreversible reaction with infinitely fast chemistry is assumed in the body of the flow. In such cases special care must be taken with modeling the upstream boundary condition. This is because the flow from the spray jet nozzle is unreacted and yet it becomes well reacted shortly downstream. Numerical results are compared against experimental measurements as well as with predictions using the CSSF approach. Numerical results from the FSSF and CSSF model are almost identical for the nonreacting spray jets, where the fluctuations in the gas-phase scalars are relatively low. For the reacting sprays, significant differences are found between the results of the FSSF and CSSF models for the reacting spray jets, where the fluctuations in the reactive scalars are high. The FSSF model reasonably predicts many features of the jet spray flames, such as flame length, gas-phase temperature, and spray droplet velocity/diameter distribution; results appear to be close to the experimental measurements. Finally, the combustion characteristics of the reacting spray jets are studied following classical group combustion theory. It shows that these spray jets have external group combustion mode near the nozzle-exit. Transition to internal group combustion takes place at different downstream locations based on the droplet loading and equivalence ratio at the nozzle-exit, whereas single droplet combustion regime is observed near the tip of the visible flame. Another alternate approach to study the combustion behavior of a cloud is proposed based on fraction of droplets having i) no envelope flame, ii) envelope flame, iii) extinguished envelope flame due to high slip velocity, iv) extinguished envelope flame due to droplet diameter being too small, v) both iii) and iv) above. Based on these, different group combustion behavior of the reacting spray jets are interpreted.

For decades, duplex filters have been put to use virtually unmodified. Technologies, handling and use of materials show enormous potential for improvement. Filter element emoval/replacement is performed according to a complex process sequence. With the newly developed Duplex Filter, the market demands concerning simple filter element removal/replacement, as well as weight and pressure loss reduction are fully met.

Space-charge effects play a dominant role in many areas of physics. In high-power microwave devices using high-current, relativistic electron beams, it places a limit on the amount of radiation a device can produce. Because the beam's space-charge can actually reflect a portion of the beam, the ability to accurately predict the amount of current a device can carry is needed. This current value is known as the space-charge limited current. Because of the mathematical difficulties, this limit is typically estimated from a one-dimensional theory. This work presents a two-dimensional theory for calculating an upper-bound for the space-charge limited current of relativistic electron beams propagating in grounded coaxial drift tubes. Applicable to annular beams of arbitrary radius and thickness, the theory includes the effect introduced by a finite-length drift tube of circular cross-section. Using Green's second identity, the need to solve Poisson's equation is transferred to solving a Sturm-Liouville eigenvalue problem, which is easily solved by elementary methods. In general, the resulting eigenvalue, which is required to estimate the limiting current, must be numerically determined. However, analytic expressions can be found for frequently encountered limiting cases. Space-charge effects also produce the fundamental collective behavior found in plasmas, especially in plasma sheaths. A plasma sheath is the transition region between a bulk plasma and an adjacent plasma-facing surface. The sheath controls the loss of particles from the plasma in order to maintain neutrality. Using a fully kinetic theory, the problem of a planar sheath with a single-minimum electric potential profile is investigated. Appropriate for single charge-state ions of arbitrary temperature, the theory includes the emission of warm electrons from the surface as well as a net current through the sheath and is compared to particle-in-cell simulations. Approximate expressions are developed for estimating the sheath potential as well as the transition to space-charge saturation. The case of a space-charge limited sheath is discussed and compared to the familiar Child-Langmuir law.

Expatriates’ adjustment to the host-country culture is a dynamic and gradual process. This process can be facilitated by cross-cultural training. The relationship between cross-cultural training and crosscultural adjustment has been explored to a great extent in the literature, however scholars have mainly put focus on how this relationship unfolds in the context of MNCs offering CCT in-house. Consequently, this leaves an interesting uninvestigated gap in terms of how fully integrated relocation service companies work with cross-cultural services and how their work can facilitate cross-cultural adjustment. This qualitative case-study therefore aims to examine the relationship between crosscultural training provided by a relocation service company and the expatriate adjustment process. An extensive review on existing theories concerning cross-cultural adjustment, cross-cultural training and cross-cultural learning are presented. After this, the case study examines how Nordic Relocation Group (NRG), a relocation service company in Sweden, operates in terms of providing cross-cultural services. The findings indicate that the relocation service company’s services are divided into different phases, whereby the timing and content of services offered varies as the expatriates’ international assignment develops over time. This form of tailoring the cross-cultural training and the content of their services supports the notion of sequential training, which within IHRM literature, is proposed as optimal in order to facilitate the expatriate’s adjustment process. Moreover, the results further indicate that the way in which NRG works with cross-cultural services, in terms of strategy, sequential order, and specific CCT activities offered, promotes effective cross-cultural learning. Consequently, the CCT strategies offered by the relocation service company can be viewed as being aligned with best practice.

Les schémas de Chiffrement Complètement Homomorphe (FHE) permettent de manipuler des données chiffrées avec grande flexibilité : ils rendent possible l'évaluation de fonctions à travers les couches de chiffrement. Depuis la découverte du premier schéma FHE en 2009 par Craig Gentry, maintes recherches ont été effectuées pour améliorer l'efficacité, atteindre des nouveaux niveaux de sécurité, et trouver des applications et liens avec d'autres domaines de la cryptographie. Dans cette thèse, nous avons étudié en détail ce type de schémas. Nos contributions font état d'une nouvelle attaque de récuperation des clés au premier schéma FHE, et d'une nouvelle notion de sécurité en structures hierarchiques, évitant une forme de trahison entre les usagers tout en gardant la flexibilité FHE. Enfin, on décrit aussi des implémentations informatiques. Cette recherche a été effectuée au sein du Laboratoire de Mathématiques de Versailles avec le Prof. Louis Goubin. / Fully Homomorphic Encryption schemes allow public processing of encrypted data. Since the groundbreaking discovery of the first FHE scheme in 2009 by Craig Gentry, an impressive amount of research has been conducted to improve efficiency, achieve new levels of security, and describe real applications and connections to other areas of cryptography. In this Dissertation, we first give a detailed account on research these past years. Our contributions include a key-recovery attack on the ideal lattices FHE scheme and a new conception of hierarchic encryption, avoiding at some extent betrayal between users while maintaining the flexibility of FHE. We also describe some implementations. This research was done in the Laboratoire de Mathématiques de Versailles, under supervision of Prof. Louis Goubin.

Scalar (heat or mass) transfer plays an important role in many industrial and engineering applications. Difficulties in experimental measurements means that there is limited detailed information available, especially in the near-wall region. Prediction in simple flows is well documented and the basis for development of many Computational Fluid Dynamics (CFD) models. This is, however, not the case for scalar transfer, especially when the Prandtl (Pr) or Schmidt number (Sc) is much greater than unity. In complex flows that involve separation and reattachment, the scalar transfer coefficient is significantly different to that of fully developed turbulent flow. The purpose of this Thesis is to investigate high Prandtl number (Pr ≥ 10) scalar transfer in fully developed (pipe) and disturbed (sudden pipe expansion) turbulent flow using CFD. Direct Numerical Simulation (DNS) is the most straight-forward approach to the solution of turbulent flows with scalar transfer. However, this technique is computationally intensive because all turbulent scales need to be resolved by the simulation. Large eddy simulation (LES) is a compromise compared to DNS. Instead of resolving all spatial scales, LES resolves only the large-scales with the small-scales being accounted for by a subgrid-scale model. Chapter 2 details the mathematical, numerical and computational details of LES with scalar transfer. From this, an optimized and highly scalable parallel LES solver was developed based on state-of-the-art LES subgrid-scale models and numerical techniques. Chapter 3 provides a verification of the LES solver for fully developed turbulent pipe flow. Reynolds numbers between Re = 180 and 1050 were simulated with a single Prandtl number of Pr = 0.71. Detailed turbulent statistics are provided for Re = 180, 395 and 590 with varying grid resolution for each Reynolds number. The results from these simulations were compared to established experimental and numerical databases of fully developed turbulent pipe and channel flows. The LES solver was shown to be in good agreement with the prior work with most discrepancies being accounted for by only reporting the resolved (large-scale) component directly reported from the LES results. For a Prandtl number close to unity, the mechanisms of turbulent transport and scalar transfer are similar. The near-wall region was shown to be dominated by large-scale sweeping structures that bring high momentum and scalar concentrations to the near-wall region. These are convected parallel to the wall as diffusion mechanisms act to transfer this to the wall where dissipation takes effect. An ejection structure then acts to transport the resultant low momentum, scalar depleted fluid back to the bulk to be replenished and continue the cycle. As the Prandtl number increases, molecular diffusivity decreases relative to viscosity, and the mechanisms of scalar transfer differ to those at Pr = 0.71. This is investigated in Chapter 4 using simulations at Re = 180, 395 and 590, with detailed statistics at Re = 395 for Pr = 0.71, 5, 10, 100 and 200. Where possible the results are compared to other numerical work and the LES solver was shown to accurately resolve the higher Prandtl number flows. There are marked variations in the scalar transfer with increasing Prandtl number as the turbulent scalar transfer becomes concentrated closer to the wall and dominated by large-scale turbulent structures. Sweeping structures are still responsible for bringing the high scalar concentrations towards the wall, however, high Prandtl number scalars are unable to completely diffuse to the wall in the time that the structure is convected parallel to the wall adjacent to the diffusive sublayer. Therefore, most of the high Prandtl number scalar is returned to the bulk via the ejection structure rather than being dissipated at the wall. Chapter 5 uses the sudden pipe expansion (SPE) to investigate disturbed turbulent flow for an inlet Reynolds numbers of Reb = 15600 and a diameter ratio of E = 1.6. These simulation parameters were chosen to match the experimental LDA measurements of Stieglmeier et al. (1989). The LES results for a range of grid resolutions were shown to be in very good agreement with the experimental work. From the LES results it was determined that the fluctuations in the wall shear stress are important in the near-wall turbulent transport. These are the result of eddies originating from the free shear layer down-washing and impinging upon the wall. This is a more effective sweeping mechanism than that observed for the fully developed turbulent pipe flow. Despite the down-wash structures impinging upon the wall, a viscous sublayer still exists in the reattachment region, albeit much thinner than the fully developed turbulent pipe flow further downstream. Using the same Reynolds number and diameter ratio, scalar transfer simulations were also undertaken in the SPE with Prandtl numbers of Pr = 0.71, 5, 10, 100 and 200. An applied scalar flux was used to heat the expanded pipe wall. The LES results are in agreement with experimental Nusselt numbers from Baughn et al. (1984) for Pr = 0.71. The disturbed turbulent flow enhances the scalar transfer and this is the result of down wash events transporting low (cold) scalar from the inlet pipe to the near-wall of the expanded pipe. This cools the heated wall and enhances localized scalar transfer downstream of the expansion. A diffusive sublayer still exists in the reattachment region within the viscous sublayer for Prandtl numbers greater than unity. As the Prandtl number increases the diffusivity decreases relative to viscosity and near-wall scalar transfer enhancement decreases as the diffusion time-scales increase.

<p>The present thesis concerns applications of first principles electronic structure calculations in conjunction with methods of statistical mechanics for simulations of transition metal alloys both in the bulk and at surfaces.</p><p>A fully relativistic generalization of the exact muffin-tin orbitals (EMTO) method has been developed. The method accurately takes into account spin-orbit coupling and allows one to calculate orbital polarization and magneto-crystalline anisotropy in magnetic systems as well as increasing the range of applicability of the EMTO method to heavy elements. A new direct-exchange Monte Carlo (DEMC) method has been proposed, which is capable to tackling effectively statistical simulations of surface segregations in disordered and ordered alloys.</p><p>The applications of relativistic methods include calculations of spin and orbital magnetization in iron-cobalt disordered and partially ordered alloys, as well as computation of the core-level shifts (CLS) in transition metal alloys. It has been found, that relativistic corrections are important for CLS calculations in 5-d metal alloys. Properties of a Ni monolayer deposited on a Cu surface have been studied. The monolayer is found to be unstable in the top layer, and its magnetization depends greatly on the surface orientation. Two distinct energy levels have been found to exist Co/Cu/Ni trilayers deposited on the (100) Cu surface, which correspond to a completely paramagnetic trilayer and the case when only Ni is paramagnetic.</p><p>Vacancy ordering in substoichometric titanium carbides TiC_x have been simulated. Existence of three ordered phases in the range of carbon concentration x=0.5 ÷1.0 has been revealed and a theoretical phase diagram has been proposed. Surface segregations have been calculated in disordered Ni₅₀Pt₅₀ and Ni₅₀Pd₅₀ as well as in ordered NiPt alloys. Segregation reversal has been observed in the Ni₅₀Pt₅₀ alloy with Pt segregation at the (111) surface and Ni segregation at the (110). In the ordered NiPt alloys segregation behaviour is found to be affected greatly by small deviations from the exact stoichiometric composition in bulk. Surface magnetization in PdV and MoV bcc alloys have been studied. It has been found, that in PdV alloys surface segregations suppress magnetic order at the surface, while in MoV alloys magnetization is substantially enhanced due to the segregation.</p>