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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.
301

New capacity design methods for seismic design of ductile RC shear walls / Nouvelles méthodes de dimensionnement à la capacité pour la conception parasismique de murs ductiles en béton armé

Boivin, Yannick January 2012 (has links)
In order to produce economical seismic designs, the modern building codes allow reducing seismic design forces if the seismic force resisting system (SFRS) of a building is designed to develop an identified mechanism of inelastic lateral response. The capacity design aims to ensure that the inelastic mechanism develops as intended and no undesirable failure modes occur. Since the 1984 edition, this design approach is implemented in the Canadian Standards Association (CSA) standard A23.3 for seismic design of ductile reinforced concrete (RC) shear walls with the objectives of providing sufficient flexural and shear strength to confine the mechanism to the identified plastic hinges and ensure a flexure-governed inelastic lateral response of the walls. For a single regular wall, the implemented capacity design requirements assume a lateral deformation of the wall in its fundamental lateral mode of vibration, and hence aim to constrain the inelastic mechanism at the expected base plastic hinge. This design is referred to as single plastic-hinge (SPH) design. Despite these requirements, CSA standard A23.3 did not prescribe, prior to the 2004 edition, any methods for determining capacity design envelopes for flexural and shear strength design of ductile RC shear walls over their height. Only its Commentary recommended such methods. However, various studies suggested, mainly for cantilever walls, that the application of these methods could result in multistorey wall designs experiencing the formation of unintended plastic hinges at the upper storeys and a high potential of undesirable shear failure, principally at the wall base, jeopardizing the intended ductile flexural response of the wall. These design issues result from an underestimation of dynamic amplification due to lateral modes of vibration higher than the fundamental lateral mode. The 2004 CSA standard A23.3 now prescribes capacity design methods intending in part to address these design issues. Although these methods have not been assessed yet, their formulation appears deficient in accounting for the higher mode amplification effects. In this regard, this research project proposes for CSA standard A23.3 new capacity design methods, considering these effects, for a SPH design of regular ductile RC cantilever walls used as SFRS for multistorey buildings. In order to achieve this objective, first a seismic performance assessment of a realistic ductile shear wall system designed according to the 2004 CSA standard A23.3 is carried out to assess the prescribed capacity design methods. Secondly, an extensive parametric study based on sophisticated inelastic dynamic simulations is conducted to investigate the influence of various parameters on the higher mode amplification effects, and hence on the seismic force demand, in regular ductile RC cantilever walls designed with the 2004 CSA standard A23.3. Thirdly, a review of various capacity design methods proposed in the current literature and recommended by design codes for a SPH design is performed. From the outcomes of this review and the parametric study, new capacity design methods are proposed and a discussion on the limitations of these methods and on their applicability to various wall systems is presented.
302

Survival analysis of gas turbine components

Olivi, Alessandro January 2016 (has links)
Survival analysis is applied on mechanical components installed in gas turbines. We use field experience data collected from repair inspection reports. These data are highly censored since the exact time-to-event is unknown. We only know that it lies before or after the repair inspection time. As event we consider irreparability level of the mechanical components. The aim is to estimate survival functions that depend on the different environmental attributes of the sites where the gas turbines operate. Then, the goal is to use this information to obtain optimal time points for preventive maintenance. Optimal times are calculated with respect to the minimization of a cost function which considers expected costs of preventive and corrective maintenance. Another aim is the investigation of the effect of five different failure modes on the component lifetime. The methods used are based on the Weibull distribution, in particular we apply the Bayesian Weibull AFT model and the Bayesian Generalized Weibull model. The latter is preferable for its greater flexibility and better performance. Results reveal that components from gas turbines located in a heavy industrial environment at a higher distance from sea tend to have shorter lifetime. Then, failure mode A seems to be the most harmful for the component lifetime. The model used is capable of predicting customer-specific optimal replacement times based on the effect of environmental attributes. Predictions can be also extended for new components installed at new customer sites.
303

"Det kändes mer verkligt, som att man nästan var där själv!" : En experimentell studie om lågstadieelevers läsupplevelse vid tillämpande av auditiva intryck / “It felt more real, as if you were almost there yourself!” : An experimental study of primary school pupils’ reading experience in the application of auditory impressions

Rosengren, Jennifer January 2016 (has links)
Syftet med denna studie var att undersöka vilken effekt tillämpandet av auditiva intryck hade för elevers läsupplevelse. Detta undersöktes genom en experimentell studie som genomfördes tillsammans med elever i årskurs 3. Eleverna fick då, under observation, läsa en text med och utan ljud. Resultatet från observationerna användes sedan för att urskilja eventuella likheter och skillnader i elevernas läsning utifrån de olika tillvägagångssätten. I samband med dessa observationer genomfördes även intervjuer med några av de elever som deltog i undersökningen, för att därigenom skapa en tydligare bild av elevernas individuella upplevelser av läsningen samt för att kunna stärka, bekräfta eller förkasta de tendenser som framgick under observationerna. Resultatet visade tydliga tendenser av ett möjligt samband mellan elevernas läsupplevelse och tillämpandet av auditiva intryck under läsning, där majoriteten av eleverna fick bättre inlevelse och kunde koncentrera sig mer under läsning. / The purpose of this study was to investigate which effect the application of auditory impressions had for students’ reading experience. This was investigated by an experimental study conducted together with pupils from the third grade. Students were then, under observation, reading texts with and without sound. The results of the observations were then used to identify similarities and differences in the students’ reading abilities in the two different scenarios. In conjunction with these observations, interviews were conducted with some of the students who participated in the study in order to create a clearer picture of their individual experiences of reading, and to strengthen, confirm or reject the trends that emerged during the observations. The results clearly showed tendencies of a possible connection between the students' reading experience and the application of auditory impression in reading, where the majority of students had a better involvement and could concentrate more during reading.
304

Extreme temperature regimes during the cool season: Their trends, variability, triggers and physical connections to low frequency modes

Westby, Rebecca Marie 27 May 2016 (has links)
During the boreal cool season (December – February) extreme temperature regimes (ETRs), including cold air outbreaks (CAOs) and warm waves (WWs), affect regional economies and human safety via their significant impacts on energy consumption, local agriculture and human health. This work aims to improve our understanding of the trends and variability in ETRs, their physical connections to low frequency modes, and the dynamical mechanisms leading to ETR onset. Earlier studies on ETR trends and variability do not consider the last decade. Further, little is known about the physical and dynamical nature of ETR onset. These unknowns motivate this dissertation and are particularly important for WWs, which have rarely been studied. This study begins with an updated analysis of the long-term trends and interannual variability in ETRs. Even with the inclusion of the last decade, no significant trends in either WW or CAO occurrence are identified over the continental United States between 1949-2011. The accompanying correlation analysis reveals that on interannual time scales, ETRs in specific regions of the U.S. tend to be modulated by certain low frequency modes. This analysis highlights an important regional asymmetry in the low frequency mode modulation of ETRs, and also indicates that the influence of ENSO upon ATRs is mainly limited to a modest modulation of WWs over the southeast US. Further, a multiple linear regression analysis reveals that the regional collective influence of low-frequency modes accounts for as much as 50% of interannual ETR variability. A synoptic-dynamic characterization of ETR onset over the southeast US is then performed using composite time-evolution analyses of events occurring between 1949-2011 to provide a qualitative indication of the role of low frequency modes. During CAO (WW) onset, negative (positive) geopotential height anomalies are observed in the upper troposphere over the Southeast with oppositely-signed anomalies in the lower troposphere over the central US. In most cases, there is a surface east-west height anomaly dipole, with anomalous northerly (CAO) or southerly (WW) flow into the Southeast leading to cold or warm surface air temperature anomalies, respectively. Companion potential vorticity anomaly analyses reveal prominent features in the mid- to upper-troposphere consistent with the geopotential height anomaly patterns. The composite analyses reveal significant roles for both synoptic and large-scale disturbances in ETR development. Synoptic-scale disturbances serve as dynamic triggers for ETR events, while low-frequency modes can provide a favorable environment for ETR onset. A suite of diagnostic analyses is conducted next and aims to identify the primary thermodynamic processes and dynamical mechanisms responsible for ETR development over the Southeast US. Heat budget analyses implicate linear temperature advection as the primary contributor to ETR development, while nonlinear advection plays a smaller role. Both the linear and the nonlinear terms contribute positively to the temperature tendencies of interest, while the adiabatic and diabatic terms offset some of the advection contributions. Piecewise PV inversion analyses are then conducted to assess which dynamical features directly contribute to the local temperature changes that occur in association with ETRs. A novel result is the discovery of the potential pathway through which the low frequency mode modulation of ETRs takes place. An upper-tropospheric PV feature first induces near-surface temperature advection, which then creates a near-surface temperature anomaly and a corresponding circulation that further enhances the initial temperature advection and ultimately leads to the ETR event.
305

Localisation d'énergie dans les protéines

Juanico, Brice 20 December 2007 (has links) (PDF)
Afin de mettre en évidence le phénomène de localisation d'énergie dans les protéines, un modèle utilisant les concepts de la Physique non-linéaire a été développé. Il permet, via l'utilisation d'un potentiel de type FPU et d'une dissipation placée sur la surface, de faire apparaître des breathers chaotiques dans certaines enzymes. Ces breathers ont une durée de vie importante par rapport aux échelles de temps caractéristiques du système. Ils sont localisés sur un seul résidu, toujours situé dans une région rigide de la protéine. Cela nous a conduit à l'hypothèse d'un lien possible entre la fonction catalytique, les propriétés locales de structure des enzymes et les localisations d'énergie. Plus précisément, l'activation d'un breather chaotique lors d'une réaction enzymatique au niveau des sites catalytiques pourrait permettre à la protéine de stocker de l'énergie pendant de longues durées.
306

Internationalization of „Coffee houses“ business / „Kavos namų“ verslo internacionalizavimas

Buiko, Violeta 22 June 2010 (has links)
In the master thesis there are analysed the methods and strategies of coffee houses‘ business internationalization, theories of business worldwide expansion, theorie of international business networks, opportunities and barriers of business evolution and development across countries. There are presented, examined and compared entry modes of business internationalization process of coffee houses. There is made micro- and macro-environment‘s factors affecting habits, traditions and preferences of coffee consumption. Moreover, there are distinguished trends in coffee house business according changing situation in world market. There are made market researches of the international business expansion of coffee houses and performed market survey about coffee drinking tranditions in coffee house. After investigation of theoretical and practical issues of coffee houses‘ business internationalization there was created model for coffee house business expansion across the world. There are introduced conclusions and suggestions for business crossnational development. Master thesis consists of four main parts: problematic, theoretic, practical and project part. Moreover, there are displayed introduction, conclusions, reccomendations and references. Volume of master thesis – 87 pg. without appendixes, figures, charts and tables, bibliography. Appendixes are attached separately. / Baigiamajame magistro darbe nagrinėjamos kavos namų verslo internacionalizavimo strategijos, metodai, problemos, verslo internacionalizavimo teorijos, tarptautinių verslo tinklų teorijos, globalaus verslo plėtimosi galimybės ir sunkumai. Pateikti yra kavos namų verslo internacionalizavimo modeliai, jų analizė ir palyginimas. Yra išanalizuoti mikro ir makro aplinkos faktoriai įtakojantys kavos gėrimo tradicijas ir poreikius o taip pat pokyčius kavos namų versle. Darbo eigoje yra atlikti tarptautinių kavos namų verslo internacionalizavimo proceso tyrimai bei atlikta kavos namų rinkos apklausa. Išnagrinėjus teorinius ir praktinius kavos namų verslo internacionalizavimo aspektus yra sukurtas kavos namų tarptautinio plėtimosi modelis ir suformuluotos išvados ir pasiūlymai verslui. Darbą sudaro keturios pagrindinės dalys: probleminė, teorinė, praktinė ir projektinė, o taip pat įvadas, išvados ir pasiūlymai, literatūros sąrašas. Darbo apimtis –87 p. teksto be priedų, iliustracijos, lentelės, grafikai, bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.
307

Critères de test et génération de séquences de tests pour des systèmes réactifs synchrones modélisés par des équations flots de données et contrôlés par des automates étendus,

Junke, Christophe 09 January 2012 (has links) (PDF)
Nous nous intéressons aux approches formelles pour le développement de systèmes réactifs critiques. Le langage synchrone Lustre pour la spécification de tels systèmes a subit des évolutions majeurs au cours des dernières années en intégrant dans sa sémantique à base flots de données synchrones des constructions de plus haut-niveau appelées automates de modes (dans le langage Scade 6). Ceux-ci mettent en œuvre l'activation de modes de calculs en fonction des états et des transitions de l'automate, et reposent pour cela sur la sémantique des horloges du langage Lustre. En particulier, nous étudiions la prise en compte des horloges et des automates de modes dans l'outil de génération de tests GATeL dédié à l'origine au langage Lustre mono-horloge (flots de données purs). GATeL génère automatiquement des séquences de tests pour un modèle à partir d'un objectif de test décrit en Lustre à travers une exploration en arrière des dépendances entre flots et selon des teniques de résolution de contraintes. Nous présentons ces différents domaines et la mise en oeuvre des modifications apportées à l'outil pour prendre en compte les automates de modes. Enfin, nous définissons des critères de couverture structurelle pour les automates de modes et montrons alors comment, en les traduisant de manière automatique sous forme d'objectifs de tests, GATeL permet de générer des séquences couvrant ces critères.
308

Theoretical problems in global seismology and geodynamics

Al-Attar, David January 2011 (has links)
In Chapter 2, we consider the hydrostatic equilibrium figure of a rotating earth model with arbitrary radial density profile. We derive an exact non-linear partial differential equation describing the equilibrium figure. Perturbation theory is used to obtain approximate forms of this equation, and we show that the first-order theory is equivalent to Clairaut's equation. In Chapter 3, a method for parametrizing the possible equilibrium stress fields of a laterally heterogeneous earth model is described. In this method a solution of the equilibrium equations is first found that satisfies some desirable physical property. All other solutions can be written as the sum of this equilibrium stress field and a divergence-free stress tensor field whose boundary tractions vanish. In Chapter 4, we consider the minor vector method for the stable numerical solution of systems of linear ordinary differential equations. Results are presented for the application of the method to the calculation of seismic displacement fields in spherically symmetric, self-gravitating earth models. In Chapter 5, we present a new implementation of the direct solution method for calculating normal mode spectra in laterally heterogeneous earth models. Numerical tests are presented to demonstrate the validity and effectiveness of this method for performing large mode coupling calculations. In Chapter 6, we consider the theoretical basis for the viscoelastic normal mode method which is used in studies of seismic wave propagation, post-glacial rebound, and post-seismic deformation. We show how the time-domain solution to the viscoelastodynamic equation can be written as a normal mode sum in a rigorous manner.
309

IKT som verktyg för främjandet av literacy i förskolan : Förskolepedagogers design för lärande och barns användning av IKT och deras skapande av literacy / ICT as a tool for the support of literacy in preschool

Thuresson, Daniel, Sörman, Niclas January 2016 (has links)
No description available.
310

Développement, validation et nouvelles applications d’un modèle d’analyse des modes normaux basé sur la séquence et la structure de protéines

Frappier, Vincent January 2016 (has links)
Les protéines existent sous différents états fonctionnels régulés de façon précise par leur environnement afin de maintenir l‘homéostasie de la cellule et de l‘organisme vivant. La prévalence de ces états protéiques est dictée par leur énergie libre de Gibbs alors que la vitesse de transition entre ces états biologiquement pertinents est déterminée par le paysage d‘énergie libre. Ces paramètres sont particulièrement intéressants dans un contexte thérapeutique et biotechnologique, où leur perturbation par la modulation de la séquence protéique par des mutations affecte leur fonction. Bien que des nouvelles approches expérimentales permettent d‘étudier l‘effet de mutations en haut débit pour une protéine, ces méthodes sont laborieuses et ne couvrent qu‘une fraction de l‘ensemble des structures primaires d‘intérêt. L‘utilisation de modèles bio-informatiques permet de tester et générer in silico différentes hypothèses afin d‘orienter les approches expérimentales. Cependant, ces méthodes basées sur la structure se concentrent principalement sur la prédiction de l‘enthalpie d‘un état, alors que plusieurs évidences expérimentales ont démontré l‘importance de la contribution de l‘entropie. De plus, ces approches ignorent l‘importance de l‘espace conformationnel protéique dicté par le paysage énergétique cruciale à son fonctionnement. Une analyse des modes normaux peut être effectuée afin d‘explorer cet espace par l‘approximation que la protéine est dans une conformation d‘équilibre où chaque acide aminé est représenté par une masse régie par un potentiel harmonique. Les approches actuelles ignorent l‘identité des résidus et ne peuvent prédire l‘effet de mutations sur les propriétés dynamiques. Nous avons développé un nouveau modèle appelé ENCoM qui pallie à cette lacune en intégrant de l‘information physique et spécifique sur les contacts entre les atomes des chaînes latérales. Cet ajout permet une meilleure description de changements conformationnels d‘enzymes, la prédiction de l‘effet d‘une mutation allostérique dans la protéine DHFR et également la prédiction de l‘effet de mutations sur la stabilité protéique par une valeur entropique. Comparativement à des approches spécifiquement développées pour cette application, ENCoM est plus constant et prédit mieux l‘effet de mutations stabilisantes. Notre approche a également été en mesure de capturer la pression évolutive qui confère aux protéines d‘organismes thermophiles une thermorésistance accrue.

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