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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

First Principles Study of Metastable Beta Titanium Alloys

Gupta, Niraj 08 1900 (has links)
The high temperature BCC phase (b) of titanium undergoes a martensitic transformation to HCP phase (a) upon cooling, but can be stabilized at room temperature by alloying with BCC transition metals such as Mo. There exists a metastable composition range within which the alloyed b phase separates into a + b upon equilibrium cooling but not when rapidly quenched. Compositional partitioning of the stabilizing element in as-quenched b microstructure creates nanoscale precipitates of a new simple hexagonal w phase, which considerably reduces ductility. These phase transformation reactions have been extensively studied experimentally, yet several significant questions remain: (i) The mechanism by which the alloying element stabilizes the b phase, thwarts its transformation to w, and how these processes vary as a function of the concentration of the stabilizing element is unclear. (ii) What is the atomistic mechanism responsible for the non-Arrhenius, anomalous diffusion widely observed in experiments, and how does it extend to low temperatures? How does the concentration of the stabilizing elements alter this behavior? There are many other w forming alloys that such exhibit anomalous diffusion behavior. (iii) A lack of clarity remains on whether w can transform to a -phase in the crystal bulk or if it occurs only at high-energy regions such as grain boundaries. Furthermore, what is the nature of the a phase embryo? (iv) Although previous computational results discovered a new wa transformation mechanism in pure Ti with activation energy lower than the classical Silcock pathway, it is at odds with the a / b / w orientation relationship seen in experiments. First principles calculations based on density functional theory provide an accurate approach to study such nanoscale behavior with full atomistic resolution, allowing investigation of the complex structural and chemical effects inherent in the alloyed state. In the present work, a model Ti-Mo system is investigated to resolve these fundamental questions. Particular attention is paid to how Mo- (i) influences the bonding in Ti, (ii) distorts the local structure in the Ti lattice, (iii) impacts the point and interfacial defect formation and migration energies, and (iv) affects the mechanism and energetics of b w and wa transformations. Our results are correlated with appropriate experimental results of our collaborators and those in open literature. The modification of Ti bonding by Mo solutes and the attendant distortion of the lattice hold the key to answering the diverse questions listed above. The solutes enhance electron charge density in the <111> directions and, consequently, stiffen the lattice against the displacements necessary for b w transformation. However, Ti atoms uncoordinated by Mo remain relatively mobile, and locally displace towards w lattice positions. This effect was further studied in a metastable Ti-8.3 at.% Mo system with an alternate cell geometry which allows for either b w or $\betaa transformation, and it was found that after minimization Ti atoms possessed either a or w coordination environments. The creation of this microstructure is attributed to both the disruption of uniform b w transformation by the Mo atoms and the overlap of Ti-Mo bond contractions facilitating atomic displacements to the relatively stable a or w structures in Mo-free regions. The vacancy migration behavior in such a microstructure was then explored. Additionally, several minimized configurations were created with planar interfaces between Mo-stabilized b region and its adjacent a- or w- phases, and it was found that the positioning of Mo at the interface strongly dictates the structure of the adjacent Mo depleted region.
22

Gender equality in the subject of English in Swedish schools

Hörnebrant Bengtsson, Marie January 2013 (has links)
The National Agency for Education (Skolverket) and The Swedish National Curriculum have stated that equality between female and male students is important. The present study investigates students in the subject English in Swedish upper secondary school and municipal school for adult education from the perspective of gender dominance in English conversation with a teacher present, with the focus on turn-taking. Two separate observations were made in three classes in adult education and two classes in upper secondary school. The research questions of this investigation are; which gender dominates the on-going conversation in English with a teacher present, how the turns were allocated, given or taken, and if the gender patterns differ between a municipal school for adults and an upper secondary school. The potential impact of the teacher’s sex on the patterns of domination is also taken into consideration. Female dominance as well as male dominance is revealed in the result of the investigated classes’ gender patterns. The results also reveal that the teacher’s sex could have an impact on the patterns of domination.
23

Gender equality in the subject of English in Swedish schools

Bengtsson, Marie January 2013 (has links)
The National Agency for Education (Skolverket) and The Swedish National Curriculum have stated that equality between female and male students is important. The present study investigates students in the subject English in Swedish upper secondary school and municipal school for adult education from the perspective of gender dominance in English conversation with a teacher present, with the focus on turn-taking. Two separate observations were made in three classes in adult education and two classes in upper secondary school. The research questions of this investigation are; which gender dominates the on-going conversation in English with a teacher present, how the turns were allocated, given or taken, and if the gender patterns differ between a municipal school for adults and an upper secondary school. The potential impact of the teacher’s sex on the patterns of domination is also taken into consideration. Female dominance as well as male dominance is revealed in the result of the investigated classes’ gender patterns. The results also reveal that the teacher’s sex could have an impact on the patterns of domination.
24

An Analysis of the Protected-Permitted Left Turn at Intersections with a Varying Number of Opposing Through Lanes

Navarro, Alexander 01 January 2014 (has links)
The Flashing Yellow Arrow Left Turn signal is quickly becoming prominent in Central Florida as a new method of handling left turns at traffic signals. While the concept of a protected-permitted left turn is not groundbreaking, the departure from the typical display of a five-section signal head is, for this type of operation. The signal head introduced is a four-section head with a flashing yellow arrow between the yellow and green arrows. With this signal head quickly becoming the standard, there is a need to re-evaluate the operational characteristics of the left turning vehicle and advance the knowledge of the significant parameters that may affect the ability for a driver to make a left turn at a signalized intersection. With previous research into the behavioral and operational characteristics of the flashing yellow arrow conducted, there is more information becoming available about the differences between this signal and the previously accepted method of allowing left turns at an intersection. The protected-permitted signal is typically displayed at an intersection with up to two through lanes and generally a protected signal is installed when the number of through lanes increases above two unless specific criteria is met. With the advent of larger arterials and more traffic on the highway networks, the push to operate these intersections at their maximum efficiency has resulted in more of these protected-permitted signals being present at these larger intersections, including the flashing yellow arrow. The core of the research that follows is a comparative analysis of the operation and parameters that affect the left turn movement of the intersection with larger geometry to that of the smaller geometry. The significant parameters of the left turn movement were examined through means of collecting, organizing and analyzing just over 68 hours of field data. This research details the determining of the significant parameters based on the generation of a simulation model of the protected left turn using Synchro, a traffic simulation package, and regression models using field driven data to determine the significant parameters for predicting the number of left turns that can be made in the permitted phase under specific operating conditions. Intuitively, there is an expectation that a larger intersection will not allow for as many permitted lefts as a smaller intersection with all conditions remaining the same. The conclusions drawn from this analysis provide the framework to understanding the similarities and the differences that are encountered when the intersection geometry differs and help to more efficiently manage traffic at signalized intersections. The work of this field promises to enhance the operations of the left turning movement for traffic control devices. With an understanding of the statistical models generated, a broader base of knowledge is gained as to the significant parameters that affect a driver's ability to make the left turn. A discussion of the statistical differences and between the models generated from the small and large geometry intersections is critical to drive further research into standards being developed for the highway transportation network and the treatment of these large signalized intersections. The exploration of specific parameters to predict the number of permitted left turns will yield results as to if there is more to be considered with larger intersections moving forward as they become a standard sight on the roadway network.
25

Effects of Orientation Change on Spatial Learning of Novel Environments on Younger and Older Adults

Fox, Michael J. January 2014 (has links)
No description available.
26

A conversaÃÃo de pessoas com transtornos mentais: um estudo dos turnos conversacionais, dos marcadores e do fenÃmeno da relevÃncia / A conversation of people with mental disorders: A study of conversational shift, and the phenomenon of labels of relevance

LetÃcia Adriana Pires Ferreira dos Santos 21 November 2000 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A presente pesquisa apresenta uma anÃlise da conversaÃÃo de pessoas com transtornos mentais enfocando trÃs aspectos principais: um que investiga os marcadores conversacionais, outro que procura verificar como os participantes da conversaÃÃo interagem uns com os outros e finalmente um que analisa o fenÃmeno de relevÃncia. Para compreender a conversaÃÃo de pessoas com transtornos mentais, analisamos as conversas de trinta e cinco sujeitos, pacientes do Centro de AtenÃÃo de Quixadà (CAPS) nos anos de 1998, 1999 e 2000. Pela interpretaÃÃo dos resultados, chegou-se à conclusÃo de que tanto em situaÃÃes de surto como de nÃo surto, as pessoas com transtornos mentais dÃo seqÃÃncia aos turnos que exigem a formaÃÃo obrigatÃria e nÃo cancelÃvel de um par adjacente, usam mais sinais conversacionais pÃs-posicionados e utilizam mais os marcadores conversacionais convergentes e indagativos do que os divergentes. Confirmou-se tambÃm a hipÃtese de que em situaÃÃes de surto, essas pessoas apresentam um comprometimento maior no fenÃmeno da relevÃncia do que quando nÃo estÃo em surto. O estudo ressalta, ainda, que as conversas de pessoas com transtornos mentais contÃm elementos coerentes e relevantes, possibilitando reflexÃes sobre as concepÃÃes que defendem o isolamento dessas pessoas por as conceberem totalmente incapazes de um convÃvio social / This research presents an analysis of the conversation of mentally disturbed people focusing on three main aspects: it investigates the conversational markers used in their interactions, it verifies how conversation participants interact with one another and, finally, it analyses the relevance phenomenon. In order to reach our aim, we have analysed the conversation of thirty-five patients of the Centro de AtenÃÃo (CAPS) of QuixadÃ, in Brazilâs northeastern state of Cearà who had their conversations recorded during 1988, 1999 and 2000. The results of the analysis have indicated that both in periods of onset or not, mentally disturbed people give continuation to conversational turns that require the mandatory formation of na adjacency pair, use more post-positioned conversational signals than pre-positioned ones, and utilize more converging and enquiring conversational markers than diverging ones. The hypothesis that, when in crises, the conversation of mentally disturbed people present a greater weakening of the relevance phenomenon has also been confirmed. The study highlights that the conversation of such people is, to some extent, coherent and relevant. This fact calls for a revision as regards the conceptions that defend the isolation of these people by preconceiving them unable of social interaction
27

The Effect of Predictability of Head Turns on Gait in Community-Dwelling Older Adults

Casper, A., Davenport, M. J., Hall, Courtney D. 17 February 2016 (has links)
No description available.
28

La construcción de la imagen social en dos pares adyacentes: Opinión-acuerdo/desacuerdo y ofrecimiento-aceptación/rechazo : Un estudio de la conversación familiar sueca y española / The construction of face in two adjacency pairs: Opinion-agreement/disagreement and offer-acceptance/rejection : A study of Swedish and Spanish family conversations

Henning, Susanne January 2015 (has links)
The main purpose of this study is to conduct a contrastive analysis on a corpus of Swedish and Spanish family conversations with respect to two adjacency pairs: opinion-agreement/disagreement (OADs) and offer-acceptance/rejection (OARs). On one hand, from a structural perspective, based on the methodology of Conversation Analysis, one of the objectives is to observe how (dis)preferred turns of the OADs and OARs are managed by the interlocutors. On the other hand, from a functional perspective, based on the methodology of Sociocultural Pragmatics, the intention is to study how face is constructed and how politeness is managed by the family members when expressing OADs and OARs. The structural analysis of OADs and OARs shows that the majority of agreements and acceptances follow the rules for preferred turns proposed by orthodox conversation analysts, i.e. they appear directly after the first part of the adjacency pair (opinion or offer), and they are brief and unambiguous. However, the structural analysis also reveals that 70% (Swedish corpus) and 72% (Spanish corpus) of the disagreements as well as 64% (Swedish corpus) and 70% (Spanish corpus) of the rejections have a tendency to not follow the proposed rules for dispreferred turns, i.e. they are not delayed or accompanied by hesitations, justifications, etc. and nor are they evaluated as dispreferred by the participants. This indicates that social perspective, especially face, has to be considered when deciding what is considered (dis)preferred. The functional analysis of the OADs indicates that the majority of the disagreements in both Swedish (68%) and Spanish (79%) corpus are not mitigated, but rather are expressed in a fairly direct manner. Swedes tend to avoid disagreements, and therefore we expected to find a major difference between the two groups. One explanation could be that family members enjoy close relationships, and therefore the Swedes feel free to express their disagreements. As for the impact on the family members face, in both groups, it is both autonomy face and affiliation face that are influenced when OADs are expressed. As for agreement, for example, it is usually autonomy face that is affected. We interpret this as a way for the participants to show that both speakers and listeners have valuable opinions that deserve to be both voiced and commented on. This reveals the more discursive (rather than ritual) nature of OADs. In addition, the functional study of OARs shows that acceptances and rejections in both corpora are expressed using both ritual and attenuating politeness according to the norms required by the situation. Concerning the impact on face, autonomy face has different requirements in the two cultures: in the Swedish conversations, it is important to offer food without insisting several times, and in the Spanish corpus, it is important to offer food more than one or two times, and there is also a tendency to refuse the offer several times before accepting it. Therefore, according to one’s situational role, one has to know how to both give and receive offers, which points to the more ritual nature of OARs. Finally, we want to emphasize that by adding a social perspective to the structural one, we can interpret the meaning of the conversations in a way that provides a broader understanding of what is being said as participants express OADs and OARs.
29

Synthèses et analyses structurales d’oligomères d’ATCs : une nouvelle famille de γ-aminoacides hétérocycliques pour la conception de foldamères / Syntheses and structural analyses of ATCs oligomers : a new family of heterocyclic γ-aminoacids for foldamers conception

Mathieu, Loic 15 January 2015 (has links)
Le travail décrit dans ce manuscrit est consacré à la synthèse et à la caractérisation structurale d'une nouvelle famille de γ-amino acides hétérocycliques contraints, les ATCs (acides 4-Amino-(méthyl)-1,3-Thiazole-5-Carboxyliques). Ces monomères sont construits autour d'un noyau thiazole inséré entre les carbones Cα-Cβ permettant de limiter la valeur de l'angle dièdre ζ à 0°. La présence de deux points de substitution, sur le carbone γ asymétrique et en position 2 du noyau aromatique, autorise une large diversification structurale des ATCs. Des séries d'oligomères, i.e. dimères, tétramères et hexamères solubles dans les solvants organiques halogénés, dans les alcools et dans l'eau ont été synthétisées par couplages peptidiques. La conformation adoptée par ces séquences a été déterminée en solution par RMN 1D et 2D associées à des techniques de modélisation sous contraintes RMN. Nous avons montré que les oligomères d'ATCs s'arrangeaient en hélices 39 droites, présentant un pas de 11,8 Å. La conformation hélicoïdale est stabilisée par un réseau de liaisons hydrogène de type CO(i)…NH(i+2) s'établissant tout au long de la séquence, faisant entrer les oligomères d'ATCs dans le monde des foldamères. Des mesures de dichroïsme circulaire ont permis d'apprécier la stabilité conformationnelle des édifices et l'analyse à l'état solide par diffraction des rayons X a confirmé l'arrangement observé par RMN. Dans une seconde partie nous avons étudié le rôle structurant d'un motif ATC placé au sein d'une petite séquence peptidique. Nous montrons au travers d'expériences RMN et de calculs théoriques que la configuration du monomère d'ATC conditionne la conformation de peptides hybrides αγαα en solution. En termes d'application nous décrivons l'utilisation du motif ATC comme mime de coude pour concevoir un analogue fonctionnel de la gramicidine S, un cyclodécapeptide symétrique antibactérien. La dernière partie de ce travail concerne nos efforts pour développer, à partir des connaissances acquises quant à la structure tridimensionnelle des oligomères d'ATCs, des inhibiteurs de l'interaction protéine-protéine STAT6-NCoA-1. / The work described herein is devoted to the synthesis and the structural characterization of a new family of heterocyclic constrained γ-amino acids, named ATCs (4-Amino-(methyl)-1,3-Thiazole-5-Carboxylic acids). These building-blocks are built around a thiazole ring inserted between the Cα-Cβ carbons allowing the limitation of the ζ dihedral angle value to 0°. The presence of two diversification points both on the γ asymmetric carbon and on the position 2 of the aromatic ring, allows a large structural diversification of the ATCs. Series of oligomers consisting in dimers, tetramers and hexamers soluble in halogenated solvents, alcools and water have been synthesized according to peptide chemistry. The conformations of the sequences have been studied by various NMR experiments associated to modelling studies led under NMR constraints. The ATC oligomers adopt a right 39 helical shape, owning a pitch of 11.8 Å which has been confirmed by crystallography. The helix is stabilized by a conserved hydrogen bond pattern between CO(i)…NH(i+2) occurring all along the sequence axis. Circular dichroism measures have been done to check the conformational stability of the architectures. In the second part of the manuscript, we demonstrate by NMR and theoretical computing that when included in a short peptide sequence, ATCs could act as turns. The derived application consists in optimizing the biological behaviour of the ATC moiety as a turn mimetic thanks to the design and the antibacterial evaluation of a gramicidin S analogue. Based on our knowledge about the three-dimensional structure of ATC oligomers, the last part of this work deals with our efforts to develop inhibitors of protein-protein interaction STAT6-NCoA-1.
30

The Sustainability of Lean Manufacturing as a Competitive Advantage

Jones, Louis G. 10 July 2013 (has links) (PDF)
Since the early 1990s lean manufacturing has been employed by companies looking to reduce costs, increase efficiencies and improve quality. Academic studies of the financial benefits of lean manufacturing are mixed in their results, where some show benefit and others do not. The objective of the current work was to confirm a financial benefit of lean manufacturing, while also establishing whether such a financial advantage was sustainable. Financial data was collected for a large number of companies in the manufacturing sector, over the period from 1990 to 2010. The data were used to show correlation between inventory turns and return on assets (ROA), where turns were a measure of the leanness of a firm or an industry. A positive correlation between turns and ROA showed evidence of financial benefit from lean implementation, confirming previous results from a smaller-scale study. It was then shown that about 45% of firms studied had a competitive advantage that could be attributed to their level of leanness. Firms with a competitive advantage were compared to peer companies and it was found that about 60% are able to sustain their competitive advantage for more than 10 years.

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