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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

Contribution à l'homogénéisation des milieux viscoélastiques et introduction du couplage avec la température par extensions d'une approche incrémentale directe / Contribution to homogeneization of viscoelastic media and introduction of the coupling with temperature by extensions of an incremental approach

Tressou, Benjamin 01 April 2016 (has links)
Cette thèse traite de la modélisation micromécanique de composites viscoélastiques via une approche incrémentale(Al) proposée par Lahellec et Suquet (2007). En plus d'être fondée sur un cadre thermodynamique rigoureux, 1' Al permet une résolution du problème local dans l'espace-temps réel (i.e. sans passage dans l'espace de Laplace). Le premier objectif est d'élargir le spectre d'application de I' Al en termes de lois viscoélastiques locales et de microstructures. Le second objectif est de tenter d'introduire au sein de l'AI la prise en compte des effets de couplage entre la viscoélasticité et la température (couplage thermoélastique mais aussi l'échauffement induit par la dissipation viscoélastique). Tout d'abord, I' Al est codée en Python• puis le programme validé pour des lois viscoélastiques linéaires simples, des microstructures et des chargements déjà étudiés dans les travaux de Lahellec et Suquet. Une seconde partie opère une généralisation théorique de l'AI à de multiples variables internes, non nécessairement déviatoriques et des phases non nécessairement isotropes. Les différentes extensions sont validées progressivement par confrontations aux solutions exactes de référence (champs complets) et en particulier l'efficacité de I' Al étendue à traiter des matrices de type Maxwell généralisé (sans et avec déformations volumiques anélastiques). Cette partie se termine par une démonstration concrète de la possible associat on de l'AI à trois schémas d'homogénéisation (Mori-Tanaka, Double Inclusion, schéma de Malekmohammadi et al. (2014)) en vue de traiter diverses morphologies (composites à fibres, à particules, et à copeaux anisotropes de bois lamellés). La dernière partie traite du couplage entre la viscoélasticité et la température au sein de l'AI. Les versions initiale et discrétisée dans le temps du problème hétérogène thermoviscoélastique fortement couplé sont formulées. Puis, plusieurs degrés de couplage sont envisagés selon une approche progressive des difficultés. Le cas du seul couplage thermoélastique est tout d'abord étudié (couplage de la thermique vers la mécanique, sans résolution de l'équation de la cha leur). les estimations obtenues pour plusieurs chargements thermomécaniques imposés à un milieu périodique contenant des fibres élastiques, thermoélastiques puis thermoviscoélastiques,dans une matrice thermoviscoélastique sont confrontées avec succès aux solutions de référence. Enfin, la résolution simultanée de l'équation de la chaleur est abordée en intégrant comme terme source la dissipation viscoélastique au sein de la matrice en plus du terme de couplage thermoélastique, les fibres étant considérées élastiques. Les évolutions de la température et de la réponse globales révèlent des tendances cohérentes. / This study is devoted to the micromechanical modeling of viscoelastic composites using an incremental approach (IA) due to Lahellec and Suquet (2007). ln addition to be based on a rigorous thermodynamic framework, the IA allows solving the heterogeneous viscoelastic problem in the real time domain (i.e. without the Laplace transform). The first aim is to extend the IA application range in terms of local linear viscoelastic laws and microstructures. The second one is to attempt to introduce the coupling effects between the viscoelasticity and the temperature within the IA framework. First, the IA is coded in Python• and the program validated for simple viscoelastic laws, and for microstructures and loading paths already studied in Lahellec and Suquet (2007). The second part focuses on a theoretical generalization of the IA for many internal variables which are not necessarily deviatoric and for anisotropie phases. The resulting estlmates are progressively validated by confrontation to reference so lutions (full -field simulations) and especially the IA ability to deal with matrices described by generalized Maxwell laws (without and with volumetric anelastic strains). This part ends with a demonstration of the possible association of the IA with three linear homogenization schemes (Mori-Tanaka, Lielen's interpolation, scheme of Malekmohammadi et al. (2014)) in order to deal with various morphologies (fiber or part icle reinforced composites, wood strand-based composites). The last part focuses on the coupling between the viscoelasticity and the temperature within the IA framework. The initial and time discretized versions of the strongly coupled local problem are formulated. Then, increasing coupling levels are envisioned for a progressive approach of the solving procedure. The thermoelastic coupling, alone, is first studied (effect of the thermies on mechanics, without solving the heat equation). The resulting estimates for a periodic microstructure with elastic, thermoelastic then thermoviscoelastic fibers, in a thermoviscoelastic matrix are successfully compared to reference solutions. At last, the heat equation is simultaneously solved by taklng into account the viscoelastic dissipation within the matrix as a source term, in addition to the thermoelastic coupling term. The evolutions of the global temperature and response reveal relevant tendencies.
22

A journey to learn about journeys : a practical examination of the nature of the relationship between the change manager and his change project

Barker, Hazel January 2000 (has links)
This research is concerned with finding out about the nature of the relationship between the change manager and the change project. An action learning approach to the investigation and analysis was adopted throughout in order to achieve a 'practitioner's perspective' in a range of inter-related learning environments. The research tracks the progress of six change managers. To attempt to minimise the variables, six smaller organisations (i.e. those employing fewer than 250 employees) from the manufacturing and production sector were recruited; all were based within a 20 mile radius; and all were attempting to change to meet the key indicators of a national performance standard from a similar starting point. Please see Table 1 below for further details. From the work with the change managers and the action learning set, all of whom acted as co-researchers during the analysis phase, some conclusions were drawn. The most significant being that the relationship between the change manager and the change project could be described as being essentially symbiotic in its nature, insofar as the change project impacted directly and indirectly upon the change manager, and the change manager's direct and indirect actions influenced the degree of success of the change project. From the conclusions drawn, and as might be considered to befit an action learning approach to research, a practical solution was proposed for achieving more successful organisational change outcomes - a framework to enable the change manager to develop, within the context of the demands of the change project. The framework was not intended to be a constant, but rather a guide for action. Some conclusions were also drawn about the form of the development which might be required by those advising on change, as a consequence of the findings.
23

Outcomes for the Hybrid Approach to First State Treatment of Hypoplastic Left Heart Syndrome

Crawford, Daniel 02 April 2018 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / BACKGROUND & SIGNIFICANCE Hypoplastic left heart syndrome (HLHS) is a congenital condition that involves hypoplasia or atresia of left heart structures. Treatment requires three separate interventions, and the “hybrid” procedure is a less invasive alternative to the initial open-heart operation. This approach has become favorable for certain patients in recent years, but there is a need to better understand the outcomes and the factors that influence the outcomes for hybrid Stage 1 palliation of HLHS.
24

Negotiating identity in multilingual parliamentary discourses in the Western Cape: a discourse analysis

McLean, Stacy Avril January 2014 (has links)
Magister Artium - MA / South Africa transitioned from an apartheid system of government, with one ruling party to a new democracy; a transition that is still currently in progress. With this transition came many new freedoms, such as the ability to choose and freely express one’s linguistic and cultural preferences, amongst many others. This study analyses the negotiation of identity in constitutionally multilingual parliamentary discourses in the Western Cape in order to create a better understanding of the influence the new South Africa has on the identities constructed in parliamentary discourses whereby polylingualism is used as a linguistic resource. The parliamentary discourse is deemed constitutionally multilingual due to the fact that before 1994, African languages were not considered official, but presently Afrikaans, English and isiXhosa are credited provincial official languages in the Western Cape and are amongst the eleven national official languages. In order to investigate how performative identities are constructed discursively in the relatively new spaces of linguistic democracy, this study conducted a multisemiotic analysis on political manifestos in conjunction with a discourse analysis of a randomly selected Hansard Report of the Western Cape Provincial Parliament, which is the only parliament of the national nine to have an alternate political party in government. In collaboration with consulting the Standing Rules of the House, the National Language Policy Framework, the Western Cape Language Policy and observing the actual sitting, scholarly literature pertaining to language use, multisemiotic features and identity negotiation were evaluated to better understand the discursive spaces in which identity is negotiated as well as to achieve the objectives of this study.
25

Approach-avoidance motivation across cultures

Hamamura, Takeshi 11 1900 (has links)
People everywhere strive for an ideal view of the self, but the conception of “ideal” differs importantly across cultures. In Western societies, the ideal self entails the possession of high self-esteem, whereas in East Asian cultures the ideal self entails maintenance of “face,” or successful performance of social roles and obligations. Within each cultural context, aspirations for an ideal self are facilitated by a network of psychological processes. One such psychological process is approach and avoidance motivations: approach motivation is useful for Westerners’ pursuit of high self-esteem whereas avoidance motivation is useful for East Asians’ concerns for face maintenance. Review of prior research renders support to this theorizing. Because approach and avoidance motivations are fundamental psychological processes, cross-cultural research on this topic is a great venue for investigating the ways in which culture shapes psychological processes. This dissertation examines the implication of cultural differences in approach and avoidance motivations in two domains. Studies 1 and 2 investigated the motivational consequences of a fit between culturally encouraged motivation and focus of self-regulation that a task at hand calls for. In comparisons of Canadians and Japanese, these studies found that individuals’ motivation for a task is enhanced when culturally encouraged motivation matched with focus of self-regulation required for the task. The second set of studies (Study 3 and 4) examined cognitive consequences of approach-avoidance motivation cultural difference. These studies found that a type of information that people are attuned to differs as a function of cultural differences in approach-avoidance motivations. Implications of the findings and future directions are discussed. / Arts, Faculty of / Psychology, Department of / Graduate
26

Návrh zeolitických materiálů s řízenou strukturou a texturními vlastnostmi / Design of zeolite materials with tailored interlayer structure and tunable textural properties

Kasneryk, Valeryia January 2018 (has links)
Germanosilicate zeolites attracted a lot of attention during the last decade. The reason for such interest is related to the unique structural properties of germanosilicates, which include zeolites of UTL, UOV, ITH, IWR, IWW, and CIT-13 types. The frameworks of these materials can be described as Si-rich layers connected by double four ring (D4R) units preferentially occupied by Ge atoms. Hydrolytic instability of Ge-O bonds in mentioned frameworks compared with Si-O bonds in conventional zeolites gives the opportunity for controllable chemically selective transformation of the germanosilicate frameworks towards novel types of zeolites including their 2D analogues. This PhD thesis focuses on modification of the structure and textural properties of germanosilicates using different ways of post-synthesis treatment: the ADOR (Assembly - Disassembly - Organization - Reassembly) transformation and post-synthesis degermanation and alumination. Presented work was carried out in the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry in Prague under the supervision of Dr. Maksym Opanasenko and advising of Prof. Jiři Čejka. First way of post-synthesis treatment applied in this work was the recently developed method of zeolite synthesis - the ADOR transformation....
27

The Reuse-Oriented Approach and its Case Study

Lou, Zhiyi 11 1900 (has links)
1 volume
28

An entrepreneurial approach to significant change

Humphreys, Debora Sholl January 1990 (has links)
No description available.
29

A capacitance approach to electromagnetic tomography

Liu, Kefeng January 1987 (has links)
No description available.
30

A General Approach to Design Automation

Chen, Shuejun 09 1900 (has links)
This thesis developed a domain independent “shell system for routine mechanical design”. This shell is used to produce domain specific design systems by simply placing domain- related knowledge into it. A general “design model”, which is an informal description of the mechanisms behind the design process, has been implemented. The design model is established based on the “characteristics and mechanisms common in routine mechanical design activities”. By examining particular design examples, it is concluded that the routine design activities have: 1) a “common design procedure” from specification recognition to detailed design; 2) “common mechanisms” to determine parameters and the like; and 3) “common knowledge formats” to express design knowledge. Only “detailed design knowledge” is specific to each domain, but can be represented in common knowledge formats. The “model” and its implementation, the shell system, describe the design process in four stages: specification development, synthesis, analysis and non-functional considerations. The synthesis achieves rough structural configurations by following the “configuration decomposition approach” which is derived from the well-developed configuration decomposition patterns in the routine design, and which uses function-to-configuration, configuration decomposition and function-checking relations. In the analysis stage, configuration parameters are determined by design relations which are represented by “design slices” written in the form of “basic description elements”. The analysis knowledge is organized in a multilevel structure from lower levels of basic description elements, design slices, to upper levels of “design procedures” and “knowledgeable configuration units”. Design slices are classified as “solving slices” and “checking slices” responsible respectively for determining parameters and ensuring that checking criteria among parameters are met. A design procedure is a pile of design slices and determines a set of parameters since design relations are used in groups. The uppermost level consists of knowledgeable configuration units. They organize design procedures, parameter sets and configuration decomposition patterns under a configuration. The reasoning process in analysis is decentralized through a number of “interpreters” which handle various tasks such as choosing a design procedure. The non-functional design aspects are considered in the design relations and are incorporated into the analysis. The shell system provides general design knowledge representation formats and general reasoning mechanisms. It is implemented on a SUN workstation using KEE which provides object-oriented programming and rule reasoning facilities. Connection between design components is dealt with using partial configurations and constraints which define the relationships between configurations and partial configurations involved in a connection. The iteration process caused by dependency among parameters is handled using the failure design procedures, that is, if a checking relation is not satisfied, a failure design procedure is called to modify some parameters at the early design stage. The geometry aspect is implemented parametrically based on an existing feature-based modelling system (IPDM). Two specific design systems: a cam system and a bolted flange system, have been developed based on the shell. Both accept given specifications, and output configurations with parameters and graphic display. The development process of these two systems is simple and efficient; and design results are satisfactory. These examples illustrated the versatility and effectiveness of the developed approach to routine mechanical engineering design activities. The major feature of this work is the explicit descriptive style in representing the design knowledge. The domain independent shell approach enhanced by this feature greatly simplifies the development of domain specific knowledge bases. / Thesis / Master of Engineering (ME)

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