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1
Noruziaan, Bahman Carleton University Dissertation Engineering Civil and Environmental. "Nonlinear seismic analysis of concrete arch dams." Ottawa, 1995.
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O'Connor, J. P. F. "The static and dynamic analysis of arch dams." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371484.
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Moghadas, Jafari Ryhane. "Dynamic analysis of arch dams : effect of thermal loading." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56585.
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Conducting a case study, this thesis investigates the dynamic behavior of Karun IV arch dam (Iran) under the effect of maximum feasible thermal input. A three-dimensional finite element model is created using ANSYS software. The thesis determines the impact of thermal loadings under two scenarios of normal and minimum water levels. The dam-foundation, dam-water and water-foundation interactions are considered in the modeling to accurately capture its dynamic response. Furthermore, in addition to the water compressibility, appropriate wave absorbing boundaries are used for the reservoir far end and bottom and for the foundation. Stability, static, modal, and thermal analyses are conducted as initial conditions. Using three orthogonal earthquake components, linear dynamic time history analyses with and without thermal loading are performed. The comparison of the results verified that the application of thermal effects on the dynamic analysis increases the maximum tension, changes the maximum pressure, and decreases the displacements in the dam body. This study concludes that thermal loading must be considered in the dynamic analysis of an arch dam as it can worsen the tensile cracks.<br>Applied Science, Faculty of<br>Engineering, School of (Okanagan)<br>Graduate
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Nzuza, Mbongeni Hopewell Sabelo. "Thermo-mechamical modelling of arch dams for performance assessment." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/5017.
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Includes abstract.<br>Includes bibliographical references.<br>This document underscores various temperature related components and procedures for undertaking a successful performance analysis of concrete arch dams. Arch dams experience high temperature variations, which are generally assessed using finite element models. Deterioration of arch dams is caused principally by thermal effects, with 19% cases attributed to freezing and thawing, and 9% to temperature variations (Daoudu et al., 1997). The temperature loading conditions cause a high expanse of stresses at the various interface locations due to change in environmental conditions. Past research has shown that stresses caused by temperature change can be larger than those from reservoir loading (Bureau of Reclamation, 1977). The proposed finite element model for this study focuses on the performance assessment of arch dams in operation due to thermal loading.
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Vezi, Mfundo. "Dynamic modelling of arch dams in the ambient state." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9083.
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Includes bibliographical references.<br>To date, dam failures have resulted in significant losses in the commercial economy and in human life. Raising awareness in the field of structural health monitoring is neccesary to develop contemporary structural analysis and monitoring methods to ensure the integrity of these structures. Hence, the research aims at developing an analytical formulation that can be used in the dynamic modelling of arch dams, for structural health monitoring purposes. A hypothetical arch dam model was created to investigate the influence of a reservoir’s orientation and geometry on the dam’s dynamic properties, and the discrepancies between the Westergaard and Fluid Structure Interaction (FSI) analysis methods. The two analysis methods were then utilized to develop an updatable finite element model, in a case study pertaining to the 72m high Roode Elsberg concrete-arch dam. Thereafter, ambient vibration tests were conducted on the Roode Elsberg dam to measure its dynamic properties and validate the finite element models. The excitation on the dam was provided by the wind and the reservoir flowing over the spillway. Vibrations of the dam were measured and recorded by accelerometers placed on the cantilevered arch blocks. Finally, the Frequency Domain Decomposition (FDD) algorithm was used to analyse the acquired data and identify the natural frequencies of the dam.
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Meri, Tony Carlos. "Temperature and thermal stress distribution in concrete arch dams in operation." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11420.
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The temperature field of concrete dams in operational stages is dominantly influenced by variations in environmental seasonal temperature and climatic conditions. Cyclic seasonal temperature and associated thermally induced stresses have been found to contribute significantly to long term degradation of strength and stiffness of concrete dams raising concerns about their durability (Leger et al. 1993). In this study, a critical review of the current state-of-the-art of temperature models for determining temperature distribution including the main environmental parameters influencing the temperature distribution for concrete dams in operation has been undertaken. It is found that, the heat flow in the concrete dams currently is approximated as conduction only and the classical Fourier heat conduction models are adopted as the governing equations to define heat flow mechanisms in the dam. The solution to Fourier heat models is accurately achieved through the finite element analysis using finite element models of the dam to the determine the temperature field.
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Tzenkov, Anton D. "Seismic analysis of concrete arch dams with contraction joint and nonlinear material models." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ61026.pdf.
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Tan, Fengjie [Verfasser], and Tom [Akademischer Betreuer] Lahmer. "Shape Optimization Design of Arch Type Dams under Uncertainties / Fengjie Tan ; Betreuer: Tom Lahmer." Weimar : Bauhaus-Universität Weimar, 2019. http://d-nb.info/1193423937/34.
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Mokhuthu, Batho. "Parametric study on the buckling behaviour of singly and doubly curved concrete arch dams." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11421.
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This study explores the buckling behaviour of thin walled and curved concrete arch dams investigated as a function of various parameters of interest, the focus being on the influence of dam thickness on the elastic buckling behaviour.
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Bukenya, Patrick. "Structural performance evaluation of concrete arch dams using ambient vibration monitoring and GNNS systems." Doctoral thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/32568.
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Societies around the world are heavily dependent on civil engineering infrastructures such as concrete dams that provide necessities such as water supply for irrigation, hydroelectric power generation and prevention of floods. As a result, it is important to ensure that concrete dams are protected such that their failure is avoided. To ensure the structural safety of these structures, concrete dams are continuously monitored by sensors installed on the dam to detect any unusual behaviour. Data collected by the sensors include environmental variables (temperature and water levels) and dam responses (deformations, stresses, strains, natural frequencies) which indicate the structural behaviour of dams. This implies that research in the analysis of the collected data is very important. Methods used in the analysis of dam monitoring data include data-driven models, physical-based models and hybrid models. Data-driven models utilise environmental variables as independent factors and dam responses as dependent factors. The trends in the dam responses can be learnt for purposes of monitoring and prediction by understanding the interactions between environmental variables and dam responses. Dam specialists have mainly focused on predicting the static deformations of dam walls using environmental variables through statistical modelling. Dynamic properties such as natural frequencies also provide valuable information on the structural behaviour of dams as they are influenced by the changes in environmental variables. To the best of my knowledge, there is no scientific literature that has studied the influence of environmental variables on natural frequencies through statistical modelling. The increase in the amount of data collected from monitoring devices installed on dams has led to the use of advanced statistical models to extract important information about the behaviour of dams. Machine learning algorithms have been developed to solve problems of large data sets and nonlinearity between variables. In particular, there are no studies that exist in the prediction of natural frequencies using measured environmental variables (water level and temperature). Therefore, the purpose of this study was to understand the effect of water level and temperature on natural frequencies and deformations. The case study used in this thesis is Roode Elsberg dam, a concrete arch dam located in South Africa. Natural frequency data used was collected between December 2014 and June 2017 while deformation data used was between January 2012 and June iii 2016. Observations indicated that water level was the dominant factor driving the variation of natural frequencies with temperature affecting the natural frequency variations in periods of constant water levels. On the other hand, temperature was the driving factor in deformation variations with water level also affecting deformation variation. Due to the nonlinear relationship between environmental variables and dam responses, a machine learning-based algorithm known as Gaussian process regression models were developed to predict natural frequencies. In Gaussian process regression, the choice of a covariance function is very important in producing good results. The ability of the different covariance functions in Gaussian process regression models, to predict natural frequencies and dam deformations, was studied. The performance of Gaussian process regression models was compared with other machine learning algorithms (BRT, SVR and ANN), multivariate adaptive regression splines and the commonly used MLR models in the prediction of natural frequencies and deformations. Results suggested that the GPR model is the most suitable and more accurate in the prediction of dam responses. Finally, robust statistics are introduced in the identification of anomalies in the collected data. Furthermore, univariate methods are used to identify any abnormalities in dam behaviour. Results indicated, there were no abnormalities in the dam behaviour.
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Gunn, Russell Michael. "Non-linear analysis of arch dams including an anisotropic damage mechanics based constitutive model for concrete." Thesis, University of Brighton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299219.
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Andersson, Oskar, and Max Seppälä. "Verification of the response of a concrete arch dam subjected to seasonal temperature variations." Thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169917.
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Many dams existing today were constructed around fifty years ago. Condition monitoring is essential for maintaining high safety and determining the current level of safety and stability for these dams. There is a need for new monitoring techniques and finite element coupled monitoring could be one of these techniques. A concrete arch dam located in Sweden is modelled and calibrated with respect to concrete temperature measurements. The temperature distribution is then defined as a prescribed strain in a structural mechanical model in which a parametric study is performed. The results from the parametric study are compared to measurements of the crest deformation and a combination of parameters is found giving the lowest difference between measurements and model results for the mid-section. The results show that the finite element model can be used to predict the behavior of the dam with acceptable deviation. The parametric study indicates that the reference temperature of the concrete has little effect on the amplitude of the deformation and that the governing factor is the coefficient of thermal expansion.<br>Många av de dammar som finns idag byggdes för omkring femtio år sedan. Tillståndsövervakning är avgörande för att kunna bestämma nivån av säkerhet och stabilitet för dessa dammar. Det finns ett behov av ny övervakningsteknik och finita element-kopplad övervakning kan vara en av dessa tekniker. En betongvalvdamm modelleras och kalibreras med avseende på uppmätt betongtemperatur. Den beräknade temperaturfördelningen definieras sedan som en föreskriven töjning en strukturmekanisk modell i vilken en parametrisk studie utförs. Resultaten från parameterstudien jämförs med mätningar av kröndeformation och en kombination av parametrar identifieras som ger lägsta skillnad mellan mätningar och modellresultat för mittsektionen. Resultaten visar att modellen kan användas för att förutsäga dammens beteende med acceptabel avvikelse. Parameterstudien indikerar att referenstemperaturen för betongen har liten inverkan på amplituden för deformationen och att den styrande faktorn är längdutvidgningskoefficienten.
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Stehle, Hermann Theodor. "A comparative study on the structural behavior of concrete arch dams subjected to swelling due to aggregate sllica reactions." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29282.
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South Africa is considered a water-scarce country and this fact alone stresses the absolute need to preserve its water resources. As time goes by, the ageing of dams in South Africa is becoming an increasingly important factor to consider from a dam safety perspective. When considering concrete dams, Alkali Aggregate Reactions (AAR) which is the collective term referring to the potential chemical reactions between the cement and the coarse aggregate in the concrete, are a major cause of ageing. AAR causes internal swelling of concrete leading to stresses that eventually manifest on a macroscopic level as inter alia cracks, deformation and opening of horizontal construction joints. Although the effect of AAR expansion on arch dams is complex, certain behavioural phenomena have been identified as typical indicators of swelling concrete. These are well covered by literature. This thesis aims to compare the structural behaviour of concrete arch dams in South Africa that are subjected to swelling due to AAR. Three arch dams, namely Hartebeeskuil Dam, Poortjieskloof Dam and Thabina Dam (all located in different climatic regions), were identified and their behavioural patterns were investigated by using visual techniques along with the interpretation of instrumentation results. The typical instrumentation results that were used for interpretation purposes included geodetic surveying results, crack width gauge results, in situ stress measurement results and trivec measurement results. Poortjieskloof Dam, the oldest of the three dams, showed permanent upstream displacement trends of both flanks, but the centre of the arch showed a downstream displacement trend. Both flanks show swelling towards the abutments and rising crest levels are evident throughout the length of the dam wall. The dam wall was cracked quite severely on the downstream face and the horizontal joints showed clear separation. The most recent displacement trends suggest that the rate of AAR is decreasing. Hartebeeskuil Dam, the second oldest of the three dams, showed permanent upstream displacement trends throughout the length of the dam wall. Both flanks show swelling towards the abutments and crest levels at both flanks show some settlement. The central section of the arch show rising crest levels. The results of in situ stress measurements carried out in 1999 showed that the downstream section of the arch is experiencing tensile stresses while the upstream section of the arch is mostly experiencing compressive stresses. The cracking patterns on both the upstream and downstream faces seem to agree with these findings. The results generally seem to suggest that the AAR mainly occurs on the upstream side of the arch and that the effective arch has become thinner due to the tension zone on the downstream side. The most recent displacement trends suggest that the rate of AAR is not showing any signs of decreasing. Thabina Dam, the youngest of the three dams, showed permanent upstream trends of the right flank while the central region and left flank of the arch showed downstream trends. The flanks have moved permanently towards each other and the crest levels have increased throughout the length of the arch section. The most recent trends show increasing rates of strain especially in the vertical (z) and tangential (y) directions. More recently the entire arch has started showing upstream displacement trends. These may indicate the onset of a swelling mechanism in the concrete, most likely AAR, but extensive testing is required to prove this.
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Zuwak, Imal, and Wasseem Kordoghly. "Numerical study of the effect of thermal ice loads on concrete dams." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278545.
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It is essential to understand the mechanics of ice load and how it affects concrete dams located in a cold climate, such as Sweden, where the temperature becomes sufficiently cold to freeze the surface of the reservoir. The purpose of this thesis is to study ice load distribution along concrete dams, and its response during the application of an ice load. Two types of concrete dams were analysed, an arch dam and a buttress dam. For these dams, the influence from different parameters on the ice load distribution along the dams is studied. In addition to this, a study on how the ice load affects dam stability had also been performed. Stability analyses based on the finite element method were performed using both linear and nonlinear formulation of the interaction behaviour between the base of the dam and the underlying rock. A parametric study of ice sheet expansion on different dam types and geometries were performed. The expansion of the ice sheet was assumed to either be caused by a constant temperature 15 ˚C uniformly distributed over the ice thickness, or by a temperature gradient from 15 ˚C at the top surface of the ice sheet and 0 ˚C at the bottom. The parametric study also includes an investigation about influence of the shape of the reservoir beaches, where it either had a perpendicular shape towards the surface of the dam, or it had an angle of 30˚ with the dam surface. In the linear stability analysis, the structure continued to deform with increasing of the resultant pressure until it reached nonlinearity. The dam deflection had a linear relation with the applied ice load force until it reached the point when structure behaviour was nonlinear. The structure failed due to sliding, overturning or combination of both sliding and overturning. A material failure can also occur if the nonlinear material behaviour is considered, however this was not considered in this study. The parametric study showed that the ice load distribution was less near the beaches, and the distribution of the load on the concrete dam was higher near the top surface of the ice sheet. It was also shown in the study that the distribution of the ice load along the dam was as a cosine function where it had the maximum value at the buttress and the minimum at monolith connections. The result also showed that the load distribution over the thickness of the ice sheet was the same along the dam, regardless of the shape of the beaches or the length of the ice sheet.<br>Det är viktigt att förstå hur islasten beter sig och hur den påverkar betongdammar som är belägna i kallt klimat, som t.ex. Sverige, där temperaturen blir tillräckligt låg för att frysa ytvattnet i en flod. Syftet med detta examensarbete är att studera isbelastningsfördelningen längs en betongdamm och dess respons under en belastningen. Två olika typer av betongdammar har analyserats, vilka är valvdamm samt lamelldamm. För dessa, studerades det hur olika parametrar påverkar lastfördelningen från istrycket längsmed dessa dammar. Slutligen har det studerats hur islasten påverkar dammsäkerheten och risken för dammbrott. Inverkan från interaktionen mellan dammen och det underliggande berget som linjär eller olinjärt har studerats i stabilitetsanalyser baserade på finita elementmetoden. En parameterstudie har också genomförts för olika dammtyper och geometrier där islasten orsakades av en expansion av isytan. Denna expansion antogs vara orsakad av antingen av en jämn fördelad temperatur över istjockleken på 15 ˚C, eller en temperaturgradient över istjockleken med +15 ˚C på den övre ytan och 0 °C vid isens bottenyta. Den parametriska studien beaktar även inverkan från utformningen av stränderna, där den har definierats som antingen vinkelrät mot dammen eller med en lutande vinkel på 30 grader. I fallet med linjära stabilitetsanalyser kommer konstruktionen att fortsätta att deformeras som ett resultat av ökande resulterande tryckkraft. Dammens deformation har ett linjärt förhållande med den applicerade islasten till dess att den når en punkt då strukturens beteende övergå till olinjärt. Strukturens brottmod kan uppstå på grund av glidning, stjälpning eller i en kombination av både glidning och stjälpning. materialbrott kan uppstå om icke-lineariteterna beaktas. Dammen gick till brott på grund av glidning, vältning eller i kombinationen av dessa då. Materialbrott kan uppstå om icke-linjära materialmodeller inkluderas, men detta beaktades dock ej i denna studie. Den parametriska studien visar att isbelastningen är mindre nära stränderna och att belastningen på betongdammen är högre vid isens ovanyta. Studien visar att islastfördelningen längsmed dammen liknar en cosinusfunktion som når sitt maximum vid stödskivan och sitt minimum vid monolitanslutningen. Resultatet visar även att islastfördelningen genom islastens tjocklek har samma form längsmed dammen oavsett utformningen av stränder eller istäckets längd.
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Koufoudi, Eleni. "variabilité spatiale des mouvements sismiques : barrages voûtes." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI036/document.
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Le terme variabilité spatiale des mouvements sismiques (SVGM en anglais pour Spatial Variability of Ground Motion) désigne les différences entre deux mesures du mouvement du sol effectuées à différents endroits, généralement en surface. La modélisation de SVGM ainsi que son effet sur la réponse dynamique des barrages est nécessaire pour l'intégration du phénomène dans les codes parasismiques. L'étude actuelle présente une mesure et une enquête approfondie sur SVGM à l'interface barrage voûte - fondation rocher. Des mesures in situ sont utilisées pour sa quantification et des simulations numériques pour la compréhension plus approfondie des phénomènes physiques qui contribuent à SVGM notamment à l'interface, c-à-d la topographie de la voûte et l'interaction sol-structure. Les données in situ provient d'une campagne sismologique qui a eu lieu sur et autour le barrage voûte du Saint Guérin pendant six mois. Le sous-ensemble d'événements consiste des événements de faible à moyenne magnitude, locaux et régionaux. Ainsi, des analyses linéaires sont permises. Tout d'abord, l'analyse dynamique du barrage voûte est réalisée; les fréquences de vibration, le coefficient d'amortissement et l'amplification de crête sont estimées profitant des mesures continues de bruit ambiant et des enregistrements sismiques. Ensuite, le SVGM est quantifiée au moyen de la phase et de la variabilité d'amplitude en utilisant des estimations de cohérence et de l'écart type de la différence des amplitudes des spectres de Fourier respectivement. Forte variabilité est observée à la fois en phase et en amplitude à l'interface de barrage-fondation rocher. Une fois que les estimateurs de la variabilité sont obtenus à partir des données, les modèles paramétriques existants sont comparés avec eux. Accentuation est mis sur deux observations: 1) les mouvements sismiques au champ libre semblent être légèrement moins variable par rapport aux mouvements à l'interface barrage-fondation rocher et 2) à l'interface barrage-fondation rocher, il y a une variabilité plus forte autour des fréquences de vibration du barrage. Ces observations suggèrent que la présence de la structure ainsi que la topographie du canyon augmentent SVGM. Cette hausse semble cependant être faible étant donné que les observations sont montés par des modèles paramétriques satisfaisants basés sur des données provenant de réseaux sismiques plates (sans topographie et structure). Des simulations numériques dans le code SPECFEM3D, basé sur les éléments spectraux, sont utilisées pour étudier plus profondément les observations in situ par le découplage des différentes causes de SVGM et évaluer l'impact de chacune. Une étude paramétrique en utilisant une topographie du canyon simplifié tente d'identifier l'effet de la topographie du canyon local sur SVGM tandis qu'un modèle géométrique précis du barrage voûte à Saint Guérin et sa topographie du canyon nous donne une idée plus précise sur l'impact de l'interaction barrage-fondation rocher sur SVGM. Les résultats de cette recherche devraient contribuer à l'amélioration de notre compréhension de SVGM à l'interface barrage-fondation rocher et de proposer des modèles de variabilité utilisés dans la conception de barrages voûtes<br>Spatial variability of seismic ground motions (SVGM) denotes the differences between two time histories of the ground motion recorded at different locations, generally at the ground surface. The modeling of SVGM and the understanding of its influence on the dam's response are necessary so as design codes start to incorporate its effects in their provisions. This study presents a measure and a profound investigation of SVGM at the dam-foundation rock interface of an arch dam. In-situ measurements are used to quantify SVGM and numerical simulations to deeper understand the particular physical phenomena that contribute to SVGM at the interface, i.e. local canyon topography and rock-structure interaction. The in-situ data comes from a seismological experimental campaign that has taken place on and around Saint Guérin arch dam over the period of six months. The campaign was held in the framework of the present thesis. The subset of events consists of low to moderate magnitude local and regional earthquakes. Thus, analysis is allowed in the linear range. Firstly, dynamic analysis of the arch dam is conducted; the frequencies of vibration, the damping coefficient and the crest amplification are estimated based on ambient noise and seismic records. Then, SVGM is quantified by means of phase and amplitude variability using coherency estimates and standard deviation of difference of Fourier amplitudes respectively. High variability is observed both in phase and amplitude at the dam-foundation rock interface. Once the estimators of variability are obtained from the data, parametric models are fitted to them. Focus is given on two observations : 1) the ground motions in the free field appear to be slightly less variable with respect to the motions at the dam-foundation rock interface and 2) at the dam-foundation rock interface, there is higher variability around the frequencies of vibration of the dam. These observations suggest that the presence of the structure along with the canyon topography increase SVGM. This increase though seems to be small given that the observations are satisfactory fitted by parametric models based on data coming from flat seismic arrays. Numerical simulations in the SPECFEM3D code, based on the spectral element method are used to deeper investigate the in-situ observations by decoupling the various causes of SVGM and evaluating the impact of each one. A parametric study using a simplified canyon topography attempts to identify the effect of local canyon topography on SVGM while a geometrically accurate model of the Saint Guérin arch dam and its canyon topography gives us a better insight on the dam-foundation rock interaction impact on SVGM. Although both features are found to increase SVGM, their impact remains secondary. The findings of the present research are expected to contribute in enhancing our understanding of SVGM at the dam-foundation rock interface and proposing variability models used in arch dams' design
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Divoux, Patrick. "Modélisation du comportement hydro-mécanique des discontinuités dans les structures et les fondations rocheuses : application aux barrages en béton." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10192.
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Les incidents et les accidents survenus a des barrages en beton, ainsi que les resultats d'auscultation, ont montre que leur stabilite depend tres largement du comportement mecanique des zones les plus faibles de l'ensemble vallee-barrage. Localises au niveau des discontinuites dans la structure et dans le rocher, ces points faibles sont principalement les failles des zones d'appui, les reprises de betonnage dans le barrage, le contact beton-rocher au niveau de la fondation et les joints de plots du barrage. Nous avons travaille a la modelisation du comportement de ces zones avec les elements finis particuliers que sont les elements d'interface. Un grande partie de ce rapport est consacree a la connaissance du comportement de ces elements, aux hypotheses emises lors de leur formulation et aux difficultes numeriques associees a la prise en compte de comportements fortement non-lineaires. Le mode de construction, les techniques de clavage et de drainage des barrages en beton en font des ouvrages particuliers dont la modelisation est rendue difficile avec les codes aux elements finis classiques. Le code de calcul gefdyn a ete le support du developpement d'outils et de methodes d'analyse du comportement des barrages en beton et des fondations rocheuses. Appliquees aux barrages de puyvalador et de puylaurent, ces methodes permettent de prendre en compte les principales non-linearites du comportement des ouvrages et de mieux comprendre leur fonctionnement. Ces calculs fournissent des renseignements exploitables sur le plan pratique et sur le plan theorique.
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Ould, Ahmedou Voffal Mohamed Said. "Estimation récursive dans les modèles Arch." Montpellier 2, 1994. http://www.theses.fr/1994MON20115.
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Le but de cette these est l'etude des proprietes asymptotiques des estimateurs de robbins-monro et des moindres carres d'un modele arch. Elle comprend cinq chapitres. Le premier chapitre rappelle les proprietes de ces modeles et fait une revue bibliographique. Dans le deuxieme chapitre nous determinerons la vitesse de convergence de l'estimateur des moindres carres. Dans les troisieme et quatrieme chapitres nous definissons un estimateur de robbins-monro et montrons sa forte consistance. Dans le chapitre 5 enfin, nous effectuons des simulations de ces estimateurs
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Kairalla, Silvana Allegrini. "DETERMINAÇÃO DAS FORMAS E DIMENSÕES DOS ARCOS DENTAIS PARA USO DE ARCO CONTÍNUO NA TÉCNICA LINGUAL." Universidade Metodista de São Paulo, 2011. http://tede.metodista.br/jspui/handle/tede/1203.
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Previous issue date: 2011-11-30<br>This study aims to determine the shapes and dimensions of dental arches to define the shape of a straight wire dental arch that could be used in lingual technique. The sample consisted of 70 white Brazilian individuals with normal occlusion and who had at least four of the six keys to normal occlusion as defined by Andrews. This sample was composed of 40% male and 60% female subjects (28 men and 42 women), with an average age of 16,4. The maxilla and mandible dental arch models were (3D) scanned and the images were analyzed in the Delcam Power SHAPE® 2010 software (Birmingham, U.K.). Points on the lingual surfaces of the teeth were selected and 14 measurements were outlined to determine the sizes and shapes of the dental arches. The Shapiro-Wilk Test enabled the definition of the small arch shape, using the 25th percentile (P25%); the average percentile for the medium arch, and a large one defined through the 75th percentile (P75%). Student t-test verified whether there were differences between male and female sexes and 12 dental arch sizes were found (6 for female sex and 6 for male sex). For all the statistical tests, the significance level used was of 5% (p<0,05). From the results found, it was possible to determine the straight-wire arch shape to be used in the LSW technique (Lingual Straight Wire) - a parabola-shaped arch -, slightly flattened on its anterior portion. And, due to the similarities found among the different dental arch sizes, shown by sexual dimorphism, we were able to create a more simplified diagram chart for dental arches.<br>Este estudo objetiva encontrar a forma e dimensão de arcos dentais para definir a forma de um arco contínuo que possa ser utilizado na técnica lingual. A amostra foi composta de 70 indivíduos brasileiros, leucodermas, com oclusão normal natural, que apresentaram no mínimo quatro das seis chaves de oclusão de Andrews. Esta amostra possui 40% de indivíduos do sexo masculino (28 homens) e 60% do sexo feminino (42 mulheres) com idade média de 16,4a. Os modelos dos arcos dentais da maxila e mandíbula foram digitalizados (3D) e as imagens exportadas para o software Delcam Power SHAPE® 2010 (Birmingham, U.K.). Foram selecionados pontos nas superfícies linguais dos dentes e traçadas 14 medidas para determinar a forma e a dimensão do arco dental. O teste de Shapiro-Wilk possibilitou definir uma forma de arco pequeno utilizando o percentil 25% (P25%), um arco médio (média) e uma forma de arco grande pelo percentil 75% (P75%). O teste t-student comparou se houve uma diferença entre os sexos, e foram encontrados 12 tamanhos de arcos dentais (6 para o sexo feminino e 6 para o sexo masculino). Em todos os testes estatísticos foi adotado nível de significância de 5% (p<0,05). A partir dos resultados obtidos, foi possível definir uma forma de arco contínuo para ser utilizado na técnica Lingual Straight Wire (LSW) - parábola levemente achatada na região anterior - e, devido à similaridade entre alguns tamanhos de arcos dentais, encontrados pelo dimorfismo sexual, pôde ser elaborado um diagrama de arcos de maneira mais simplificada.
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Nunes, Marcos Felipe. "ESTUDO DAS DIMENSÕES TRANSVERSAIS DOS ARCOS DENTAIS MANDIBULARES EM INDIVÍDUOS COM DIFERENTES PADRÕES FACIAIS." Universidade Metodista de São Paulo, 2012. http://tede.metodista.br/jspui/handle/tede/1207.
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Previous issue date: 2012-04-23<br>This study evaluated the transverse dimensions of the mandibular dental arches in individuals with different facial patterns. The sample was made up by right lateral cephalograms and dental casts of 33 Caucasian individuals of both sexes, aged between 13 and 25 years in the stage of permanent dentition. The Facial Pattern was obtained through a subjective facial analysis on frontal and profile photographs of 1.500 orthodontic documentations, using the cephalometric analysis by means of ANB angle to define the Skeletal Pattern, which should agree with the Angle malocclusion classification. The sample was divided into three groups: Group 1 - Pattern I, Class I of Angleand ANB 2.0o (±0.5o); Group 2 - Pattern II, Class II division 1 of Angle and ANB≥ 4.0o, and Group III Pattern III, Class III of Angle and ANB≥ - 4.5o. Transversal arch dimensions were measured after 3D digitizing (Scanning Dental Wings) of the cast models, from which were set the transverse distances intercanine, inter-first premolars, inter-second premolars, and inter-first molar mesial and distal cusps, inter-second molar mesial and distal cusps, by using the software Geomagic Studio® 12. The mean values and standard deviation of the transverse dimensions were obtained and to compare the three groups, an analysis of variance and Tukey s post-hoc test were applied.For all statistical tests, the significance level was set at 5% (p<0.05). A statistical difference was detected for 2 of the 14 transverse dimensions evaluated in the maxillary arch in the mesial region of the second molar (p=0.024), and in the mandibular arch, in the distal region of the first molar (p=0.047). The mandibular dental arches were similar for the three studied groups.<br>O presente estudo avaliou as dimensões transversais dos arcos dentais mandibulares em indivíduos com diferentes padrões faciais. A amostra foi constituída por telerradiografias em norma lateral direita e modelos em gesso de 33 indivíduos, leucodermas, em ambos os sexos, com idade entre 13 e 25 anos, na fase de dentição permanente. O Padrão Facial foi obtido pela análise facial subjetiva em fotografias frontal e de perfil de 1500 documentações ortodonticas, foi utilizada análise cefalométrica por meio do ângulo ANB para confirmar o padrão esquelético, o qual deveria coincidir com a classificação de maloclusão de Angle. A amostra foi dividida em três grupos: Grupo I Padrão I, Classe I de Angle e ANB 2,0 o ±0,5o; Grupo II Padrão II, Classe II divisão 1 de Angle e ANB ≥ 4,0, e Grupo III Padrão III, Classe III de Angle e ANB ≥ - 4,5o. As dimensões transversais do arco foram mensuradas após a digitalização dos modelos em gesso pelo Scanner Dental Wings (3D), a partir dos quais foram estabelecidas as distâncias transversais intercanino, inter 1º PM, inter 2º PM, inter 1º M (cúspide mesial e distal), inter 2º M (cúspide mesial e distal), com o auxílio do software Geomagic Studio® 12. As médias e desvio padrão das dimensões transversais foram obtidas, e, para comparação entre os três grupos foi utilizado a Análise de Variância e teste de Tukey. Em todos os testes estatísticos foi adotado nível de significância de 5% (p<0,05). Houve diferença estatística em duas dimensões transversais das 14 avaliadas no arco maxilar na região mesial do segundo molar (p=0,024) e no mandibular na região distal do primeiro molar (p=0,047). Os arcos dentais mandibulares foram semelhantes nos três grupos estudados.
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Lounis, Tewfik. "Inférences dans les modèles ARCH : tests localement asymptotiquement optimaux." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0222/document.
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L'objectif de cette thèse est la construction des tests localement et asymptotiquement optimaux. Le problème traité concerne un modèle qui contient une large classe de modèles de séries chronologiques. La propriété de la normalité asymptotique locale (LAN) est l'outil fondamental utilisé dans nos travaux de recherches. Une application de nos travaux en finance est proposée<br>The purpose of this phD thesis is the construction of alocally asymptotically optimal tests. In this testing problem, the considered model contains a large class of time series models. LAN property was the fundamental tools in our research works. Our results are applied in financial area
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Lounis, Tewfik. "Inférences dans les modèles ARCH : tests localement asymptotiquement optimaux." Electronic Thesis or Diss., Université de Lorraine, 2015. http://www.theses.fr/2015LORR0222.
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L'objectif de cette thèse est la construction des tests localement et asymptotiquement optimaux. Le problème traité concerne un modèle qui contient une large classe de modèles de séries chronologiques. La propriété de la normalité asymptotique locale (LAN) est l'outil fondamental utilisé dans nos travaux de recherches. Une application de nos travaux en finance est proposée<br>The purpose of this phD thesis is the construction of alocally asymptotically optimal tests. In this testing problem, the considered model contains a large class of time series models. LAN property was the fundamental tools in our research works. Our results are applied in financial area
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Maftoul, Joseph. "Étude de l'extinction spontanée des arcs à faible courant dans l'air." Paris 11, 1987. http://www.theses.fr/1987PA112465.
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Les arcs électriques à faible courant sont l'objet d'instabilités. Parmi ces instabilités, l'extinction de l’arc occupe une place importante tant du point de vue expérimental que théorique. L'extinction d'arc joue un rôle considérable dans l'industrie. En même temps, son étude est liée au problème de l'émission électronique de la cathode, au comportement de l'ensemble des sites émissifs et aux caractéristiques individuelles des sites. Dans le présent travail,un modèle statistique (modèle "multisite") de fonctionnement et des extinctions spontanées des arcs est proposé. Ce modèle recoupe les données expérimentales sur la durée des arcs à faible courant entre des électrodes en métal non réfractaire. Grâce à ce modèle, l'arrachement de courant trouve une explication. Ce modèle permet également une approche théorique du problème de l'érosion des électrodes. Une simulation numérique des extinctions des arcs basée sur la méthode de MONTE-CARLO permet de mieux comprendre les lois de probabilité qui régissent le comportement des sites émissifs sur la surface cathodique. L'étude spectroscopique de la lumière de l'arc a permis d'établir une classification des raies et des bandes moléculaires émises. La présence de cyanogène CN est détectée dans ce type d'arc brûlant dans l'air. Une estimation de la température, du degré d'ionisation et da la densité électronique dans les régions cathodique et anodique et dans la colonne est donnée. Un dispositif de spectroscopie résolue dans le temps a été réalisé. Ce dispositif permet d'établir l'évolution de la lumière avant et après l'extinction pour différentes longueurs d'onde. Une présentation de spectres-rapport est proposée. Grâce à cette méthode, l'émission d'ions d'azote et d'oxygène avant l’extinction est montrée. Le modèle "unisite" basé sur l'analyse des spectres-rapport des différentes. Espèces émettrices est ensuite utilisé pour expliquer l'extinction de l'arc.
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Prins, Zac James. "Investigating the operational behaviour of a double curvature arch dam." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25385.
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The safety of dams is crucial in ensuring the continual availability of water, safety of the surrounding communities and infrastructure. Surveillance systems are implemented to monitor the structural integrity of certain dams which have a safety risk. The components and extent of the surveillance systems adopted depends on many factors, which include the type of dam wall structure used to impound the reservoir, geotechnical and environmental conditions. The case study used for this thesis is Kouga Dam located in the Eastern Cape Province of South Africa. It is a double curvature, concrete arch dam which supplies water for domestic, irrigation and industrial use to the Gamtoos River Valley and Nelson Mandela Metropolitan. During construction the stability of the right flank was questioned and subsequently, remedial measures were taken in order to increase the shear resistance of this flank. Previous dam safety evaluations also noted the possibility of Alkali Silica Reaction (ASR) occurring within the structure which resulted in concrete swelling and loss of strength. Due to these factors and the large hazard potential rating associated with this dam an intensive surveillance system has been used to monitor the dam's behaviour during operation. In this thesis the results of the surveillance system is analysed. A strong linear relationship exists between the temperature loading and displacement response of the dam wall. Changes in temperature initiate the response of the structure almost instantaneously. A more complex relationship exists between hydrostatic loading and the displacement response of the structure. A phase lag of approximately one to three months is evident between these two variables. Since construction the displacement and strain rates in the upstream (y) and upward (z) directions are 0.3mm/annum and 8.6με/annum respectively. However, since 1989 there has been a reduction in the average displacement and strain rates in all directions by approximately 70%. This may suggest that the ASR has stabilized. The vertical construction joints, especially the central and upper joints, are relatively open during low water levels. The structure is found to transfer the imposed loading mainly to the central foundation via dominant cantilever action. As a result the reaction forces on the upper foundation have been found to be relatively low, lowering the risk of potential shear failure of the right foundation. Small foundation movements of less than 0.3mm have been observed within the foundation downstream of the dam wall on the right flank. These movements are between 10 and 40m within the foundations.
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Assili, Omar. "Tests paramétriques et non paramétriques dans les modèles à erreur ARCH." Doctoral thesis, Universite Libre de Bruxelles, 1997. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212210.
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Santos, Marisa Coelho. "Modelação da volatilidade das criptomoedas “dominantes” no mercado." Master's thesis, Instituto Superior de Economia e Gestão, 2019. http://hdl.handle.net/10400.5/19862.
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Mestrado em Econometria Aplicada e Previsão<br>Nos últimos anos, o mercado das criptomoedas cresceu exponencialmente, ocorrendo uma diminuição considerável do grau de concentração deste mercado.
As criptomoedas apresentam como maior desvantagem os elevados níveis de volatilidades e, consequentemente, as criptomoedas aparentarem ter mais características de ativo com risco do que de moeda fiduciária. Não obstante, maior parte dos estudos académicos sobre este tema analisam apenas o comportamento dos preços e/ou retornos da Bitcoin, existindo uma fraca evidência estatística sobre as características da volatilidade de outras criptomoedas.
Deste modo, o principal objetivo deste trabalho é analisar, de forma mais detalhada, as principais propriedades de um conjunto de nove criptomoedas: Ethereum, Ripple, Litecoin, Monero, Stellar, Dashcoin, Dogecoin e Nemcoin, no período de 27 de outubro de 2015 a 10 de setembro de 2019. Também vou propor modelos da classe GARCH para caracterizar o comportamento das séries temporais destas criptomoedas.
Numa primeira fase, constatou-se que as séries dos retornos diários das criptomoedas verificam os factos estilizados das séries financeiras. Posteriormente, foram estimados diferentes modelos GARCH, tendo sido escolhido o modelo que apresentou menor valor nos critérios de informação para cada criptomoeda.
Com base nos resultados, os modelos que apresentaram o melhor ajustamento ao comportamento dos retornos diários foram o AR(5)-GARCH para a Bitcoin, Ethereum e Dogecoin, e o AR(5)-IGARCH para os retornos da Ripple, Litecoin, Monero, Stellar, Dashcoin e Nemcoin.<br>In the last few years, the cryptocurrency market has grown exponentially, with a smaller decrease in the degree of concentration of this market.
The cryptocurency has as disadvantage the high levels of volatility. Therefore, based on the academic literature, have more financial asset characteristics than fiduciary currency. However, most cryptocurrency studies only analyze Bitcoin price and / or return behavior, and there are few studies on the characteristics and behavior of others cryptocurrencies, consequently, there is no statistical evidence to conclude whether cryptocurrencies, regardless of their representativeness, assume a standard behavior in volatility or diverge.
Therefore, the main objective of this study is to model a set of nine cryptocurrencies: Ethereum, Ripple, Litecoin, Monero, Stellar, Dashcoin, Dogecoin and Nemcoin, from October 27, 2015 to September 10, 2019, using a class of GARCH models.
In the first phase, it was verified whether the daily returns series of the cryptocurrencies verify the stylized facts of the financial series and, later, the different GARCH models were estimated, choosing the model that showed the lowest value in the information criteria for each cryptocurrency.
Based on the results, the AR (5) -GARCH model provides better adjustment to the volatility behavior of Bitcoin, Ethereum and Dogecoin daily returns, and the AR (5) -IGARCH model to model the volatility returns of Ripple, Litecoin, Monero, Stellar, Dashcoin and Nemcoin.<br>info:eu-repo/semantics/publishedVersion
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Laforest, Zoé. "Etude expérimentale et numérique d'un arc électrique dans un liquide." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30161/document.
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L'étude des arcs électriques dans les liquides débute au XXème siècle suite à la création des premiers disjoncteurs à bain d'huile et à l'utilisation de différents procédés de soudure/découpe en pleine eau de coques de navire. Ces études ont été délaissées pendant environ 60 ans jusqu'à ce que de nouvelles applications voient le jour comme la fabrication de nanostructures (pour le génie électrique, la médecine, etc), la fracturation électrique ou encore diverses applications environnementales (dépollution, stérilisation, gazéification, ondes de chocs). Ces diverses applications se font avec des temps et des énergies mises en jeu pour la décharge très variables. Malgré ces différences, il y a toujours l'apparition d'une phase gazeuse globalement sphérique due au passage du courant. Cependant, cette phase est très peu étudiée dans la littérature notamment pour des décharges de l'ordre du kilojoule pour des durées de 10ms environ. L'objectif de la thèse est donc d'améliorer la compréhension de la formation et de la dynamique de la bulle de gaz alimentée par cet arc en jouant sur certains paramètres du système. Les travaux effectués s'articulent suivant deux axes : une étude expérimentale pour analyser le comportement de cette bulle par rapport à l'arc en modifiant notamment l'énergie injectée, la distance inter-électrode utilisée ou encore la nature du fluide employé ; et une étude numérique où un modèle diphasique 2D a été mis en œuvre sous Ansys Fluent pour simuler la création et le développement de cette phase gazeuse au sein d'une phase liquide. La complémentarité de ces deux études permet de témoigner de la présence de certains mécanismes comme ceux de la formation de bulles ou de cycles d'expansion et d'effondrement, gouvernés par des phénomènes de chauffage, d'évaporation ou électrothermiques. L'expérience mise en place se compose d'un réacteur hermétique en aluminium où l'arc électrique est amorcé par un fil fusible entre deux électrodes dans un liquide : eau ou huile. Des hublots permettent la visualisation par caméra rapide de l'espace inter électrode, et donc de l'arc et de la bulle de gaz qu'il engendre. Les caractéristiques courant et tension de l'arc électrique sont suivies dans le temps. Un capteur de pression dans le volume d'air situé au-dessus du liquide contrôle l'onde de pression générée par la décharge. Les résultats expérimentaux sont traités sous Matlab et permettent de conforter le modèle numérique mis en place. Le code utilise les équations de Navier-Stokes pour décrire les deux phases du fluide via la méthode Volume-Of-Fluids (VOF). A ces développements a aussi été intégré un modèle pour prendre en compte le transfert d'une phase de fluide vers une autre. Pour nos conditions de températures élevées, ce modèle a dû être adapté via le coefficient d'intensité de transfert de masse, qui est décrit en fonction de la température et de la proportion de phase dans une cellule. Les résultats de simulation issus de ce modèle permettent d'appuyer les observations expérimentales, et de poser les bases d'une étude sur la formation et le comportement de la phase gazeuse produite par le passage d'un arc électrique dans un liquide<br>The study of electrical arcs in liquids begins in XXth century with the first oil circuit breaker and the use of welding/cutting processes on ship hulls in full water. These studies have been neglected for about 60 years, until the emergence of new applications such as the manufacture of nanostructures (for electrical engineering, medicine, etc.), electrical arc fracturing or different environmental applications (depollution, sterilization, gasification). In these applications different times and energies scales are involved for the discharge characteristics. Despite these differences, in all configurations a spherical gaseous medium dues to the current carrying path in the liquid exists. However, this gaseous phase is not much studied in the literature, particularly for an energy discharges of the order of kilojoule applied during 10ms. The goal of the thesis was to improve the understanding and to interpret the formation and the dynamic of the gas bubble created by this arc by varying the conditions. The work follows two ways: an experimental study to analyze the behavior of the bubble depending on the arc characteristics as the energy injected, the distance between the electrodes or the nature of the fluid; And a numerical study, where a 2D diphasic model has been implemented under Ansys Fluent to simulate the creation and the expansion of this gaseous phase in a liquid. The complementarity of these two approaches allows complementarities and interpretations. The experiment set up is composed by a closed aluminum reactor, where the electric arc is established in a liquid (water or oil) by a fusible wire between two electrodes. Windows allows to visualize by a speed camera the inter-electrode space, and so the arc and the gas bubble created. The current and voltage characteristics of the electric arc are recorded over time. A pressure sensor located in the volume of air above the liquid controls the pressure variations. The experimental results are treated through Matlab software and allow corroborating the numerical model developments. The code uses the Navier-Stokes equations to describe the two phases of the fluid via the Volume-Of-Fluids (VOF) method. Specifics developments have also been integrated to take into account the phase transfer at the gas/liquid interface adapting the mass transfer intensity coefficient. This coefficient is described as a function of the temperature and of the proportion of phase in a cell. The simulation results from the model support the experimental observations and build the foundations for a study on the behavior of the gaseous phase produced by the passage of an electric arc in a liquid
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Correia, Anabela Miranda Batista. "O efeito sorriso da valatilidade: uma análise do PSI 20 e de onze das empresas que o constituem." Master's thesis, Universidade de Évora, 2009. http://hdl.handle.net/10174/21012.
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A volatilidade das cotações dos activos financeiros está directamente relacionada com o respectivo retomo e a sua análise constitui uma das ferramentas estatísticas mais importantes para os agentes económicos que actuam nos mercados accionistas. É útil a observação dos comportamentos assimétricos da volatilidade, exibidos principalmente em períodos de intensa volatilidade associados a fases de quebra de preços, mas também à persistência de choques positivos e negativos, geradores de efeitos diferenciados sobre a volatilidade. Os efeitos da assimetria podem ser satisfatoriamente captados por modelos de tipo ARCH (Autoregressive Conditional Heteroscedasticity) e, em especial, pelo EGARCH (Exponential Autoregressive Conditional Heteroscedasticity). Este último é utilizado no presente estudo, onde se analisam os efeitos da volatilidade no PSI 20, e em onze títulos que o compõe, entre Janeiro de 1996 e Junho de 2009. Os modelos assimétricos evidenciam o efeito alavancagem na amostra estudada, sugerindo que os retornos negativos estão mais associados aos aglomerados de volatilidade, ou seja, que as "más notícias" têm maior impacte na volatilidade do que as "boas notícias". - ABSTRACT: The volatility of assets prices is directly related to their return and its analysis is a fundamental tool for all agents operating in equity markets. It is especially useful the observation of volatility's asymmetric behavior, mainly displayed in periods of high volatility during bear markets, and of the persistence of positive and negative shocks generating distinct effects on volatility. The effects of asymmetry can be captured by ARCH type models (Autoregressive conditional heteroscedasticity) and by the EGARCH (Exponential Autoregressive conditional heteroscedasticity). The latter is used in this study where the volatility of the PSI 20 and of eleven of its titles is analyzed between January 1996 and June 2009. The estimated models uncovered the asymmetric leverage in the assessed sample of data, suggesting that negative returns are more associated with clusters of volatility, i.e. that "bad news" have a greater impact on volatility than "good news".
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Kahhali, Nicolas. "Modélisation et simulations numériques du transfert radiatif dans les plasmas d'arc électrique." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2009. http://www.theses.fr/2009ECAP0023/document.
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De nombreuses études, aussi bien expérimentales que théoriques, ont été menées pour l'industrie électrique afin de comprendre et d'être capable de prédire les mécanismes intervenant lors d'une coupure électrique par arc. Ces études ont montré la grande diversité et complexité des phénomènes physiques et chimiques mis en œuvre. L'arc électrique créé juste après la séparation des contacts est poussé par les forces électromagnétiques vers une zone d'extinction. Durant son développement et sa propagation, l'énergie lui est fournie par effet Joule et est dissipée par différents modes de transfert thermique. Son expansion rapide induit des effets de compressibilité avec la propagation d'ondes de pression. Le rayonnement intense du plasma créé, ainsi que les phénomènes aux pieds des électrodes, induisent une ablation des parois qui change la composition chimique du milieu et rend plus complexe la modélisation de l'ensemble des phénomènes couplés par hydrodynamique, électromagnétisme, transferts thermiques et diffusion d'espèces chimiques en régime fortement instationnaire. Le rôle du transfert radiatif est primordial dans la mesure où, d'une part, il conditionne le champ de température et donc les propriétés de transport, notamment électriques, et, d'autre part, participe pour une grande part à la thermo-dégradation des parois.La modélisation de l'ensemble des phénomènes physico-chimiques a beaucoup progressé durant les vingt dernières années mais le calcul du transfert radiatif demeure un point bloquant dans l'avancement des méthodes de modélisation.En effet, le champ de rayonnement est caractérisé par une luminance qui dépend de la longueur d'onde, de la position spatiale, de la direction de propagation, ainsi que du temps au travers ici des variations des champs de température et de la composition chimique.La prise en compte rigoureuse de toutes ces dépendances demeure inaccessible à l'heure actuelle pour des simulations complètes d'extinction d'arc, en particulier à cause de la complexité des spectres d'émission et d'absorption des milieux plasmas. Le recours à des modèles approchés pour le traitement spectral et/ou pour les dépendances géométriques et directionnelles est nécessaire.Ce travail a été mené en collaboration entre le Laboratoire EM2C et la société Schneider Electric. Il fait suite à des travaux de collaboration antérieurs dont l'objectif était la détermination des propriétés radiatives fondamentales des plasmas d'arc (Thèse S. Chauveau).Le but principal du présent travail est de développer des modèles approchés mais précis, ainsi que des outils de simulation numérique avec différents degrés de finesse, pour le calcul du champ de puissance radiative et des flux pariétaux dans des chambres de coupure électrique basse tension. Les modèles et outils développés doivent être implémentés dans des codes de simulation hydrodynamique dédiés soit à des géométries bidimensionnelles simplifiées, soit à des géométries industrielles complexes et tridimensionnelles. Ces outils doivent Les études expérimentales menées sur des maquettes représentatives des dispositifs industriels montrent la présence de vapeurs plastiques et métalliques dues à l'ablation et à l'érosion des parois. La composition chimique change par ailleurs fortement avec le temps entre la naissance et l'extinction de l'arc électrique. Bien que les modèles développés ici puissent être adaptés à cette composition chimique complexe, nous supposerons tout le long de ce travail que le milieu gazeux est un plasma d'air à l'équilibre thermique et chimique local<br>Non fourni
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Guimarães, Gil Eduardo. "Avaliação microestrutural e das propriedades mecânicas de aço ARBL de resistência ambiental soldado a arco submerso com adição de pó metálico." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-15092016-122338/.
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Estudos anteriores mostraram que a soldagem de aço USI-SAC-50 com adição de pó metálico pode promover o aparecimento de microfases que interferem nas propriedades mecânicas. Este trabalho, teve o objetivo de estudar os efeitos de variações nos consumíveis, aporte de calor e do tratamento térmico pós-soldagem na diminuição ou eliminação das microfases. Chapas de aço USI-SAC-50 foram soldadas por arco submerso com adição de pó metálico utilizando-se fluxos de soldagem BX-200 e OK-1071,arames de soldagem EM-12K e EB-2 e aportes de calor de 4,8 kJ/mm e 3,6 kJ/mm. Tensão e corrente foram mantidas em 34 V e 600 A, respectivamente. Após a soldagem, metade das chapas foi submetida a um tratamento térmico de alívio de tensões a 580ºC por 1 h. Foram realizados ensaios mecânicos de dureza, tração a -10ºC e CTOD a -10ºC, assim como foram realizadas metalografias preto e branco e coloridas para identificação e quantificação de fases. As composições químicas obtidas nos cordões de solda foram adequadas para que a quantidade de ferrita acicular presente assegurasse as boas propriedades mecânicas. As mudanças na composição química, em relação à trabalhos anteriores, ocasionadas pela variação dos fluxo e as variações nos aportes de calor promoveram uma sensível diminuição na quantidade de microfase para faixa de 2,5 a 10%. Entre os cordões ensaiados para avaliação de CTOD aquele com maior teor de austenita retida apresentou um CTOD menor, mostrando a influência dessa fase sobre a tenacidade. Também o tratamento térmico de alívio de tensões contribuiu para a diminuição da quantidade de microfase para a faixa de 0 a 1,5%, sendo que a microfase restante apresentou uma forma esferoidal.<br>Previous studies showed that the welding of steel USI-SAC-50 with addition of metal powder can promote the appearing of one phase that interfere in the mechanical properties. This work had the objective of studying the effects of variations in the consumable ones, contribution of heat input and of the thermal treatment in the decrease or elimination of this phase. Plates of steel USI-SAC-50 were welded by submerged are weld with addition of metal powder being used welding fluxes BX-200 and OK-1071, welding wires EM-12K and EB-2 and heat inputs of 4,8 kJ/mm and 3,6 kJ/mm. Tension and current were maintained in 34 V and 600 A, respectively. After the welding, half of the plates was submitted to a thermal treatment of relief of tensions to 580ºC for 1 h. Mechanical tests of hardness, traction to -10ºC and CTOD to -10ºC were carried out, as well as black and white and colored metalographies were carried out for identification and quantification of phases. The chemical compositions obtained in the weld beads they were appropriate so that the amount of acicular ferrite present assured the good mechanical properties. The changes in the chemical composition, in relation to previous works, caused by the variation of the fluxes and the variations in the heat inputs they promoted a sensitive decrease in the amount of microphase for strip from 2,5 to 10%. The thermal treatment of relief of tensions also contributed to the decrease of the amount of microphase for the strip from 0 to 1,5%, and the remaining microphase presented a spherical shape.
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Nunes, Patrícia Cristina Cunha. "Teoria do arco de alvenaria : uma perspectiva histórica." reponame:Repositório Institucional da UnB, 2009. http://repositorio.unb.br/handle/10482/4465.
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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2009.<br>Submitted by Larissa Ferreira dos Angelos (ferreirangelos@gmail.com) on 2010-04-07T14:28:34Z
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Previous issue date: 2009-04<br>O arco de alvenaria é um dos grandes testemunhos da evolução da ciência estrutural. Conjuntamente com a cúpula e a abóbada, que constituem seu prolongamento natural no espaço, o arco de alvenaria, enquanto elemento arquitetônico e estrutural, está na base da arquitetura ocidental, e, portanto, de parte significativa do patrimônio histórico, muito particularmente de muitos dos edifícios mais emblemáticos legados pela história à contemporaneidade. Durante séculos, sua utilização se fundamentou em regras estruturais baseadas na tradição e no conhecimento empírico, mas com o advento da ciência moderna, se desenvolveram ferramentas analíticas que possibilitavam a compreensão científica de seu comportamento estrutural e a elaboração de regras científicas para o seu cálculo. Surgem, então, as teorias científicas do arco de alvenaria, que recorrem em especial à Mecânica e à Matemática para explicarem o comportamento do arco e desenvolverem métodos de base científica para o dimensionamento dessas estruturas. Este trabalho faz um exame crítico analítico do desenvolvimento dessas teorias, no período histórico que se estende do século XV, com os escritos de Leonardo da Vinci, até meados do século XX, às vésperas do desenvolvimento das ferramentas numéricas. São identificadas algumas mudanças de paradigma durante esse período, que convergem para o debate atual entre a teoria elástica e a teoria plástica. Este trabalho de pesquisa envolveu uma consulta ampla a fontes primárias (em meio eletrônico) e secundárias. São descritas algumas das teorias e métodos mais influentes no período, buscando-se inseri-los no quadro geral das grandes linhas teóricas. Entre os temas examinados encontram-se o modelo do arco de alvenaria como sistema de cunhas polidas, a investigação de seus mecanismos de colapso, experimentos comprobatórios da existência da linha de empuxo bem como seu funcionamento, a teoria elástica aplicada aos arcos de alvenaria e, de forma resumida, a teoria da carga limite. ______________________________________________________________________________________ ABSTRACT<br>The masonry arch is a great witness of the evolution of Structural Science. Together with vault and the dome, which naturally result from its evolving in space, the masonry arch as both architectural and structural element is in the basis of western architecture, so that it also makes up an important part of our heritage, particularly including some of our most emblematic, icons buildings. For centuries the building of masonry arch relied on structural rules based upon tradition and empirical knowledge, but with the rise of modern science, analytical tools have been brought to light which made it possible to build up a scientific understanding of its structural behavior and to draw up science based rules for the dimensioning of new vaulted structures. That is the born of masonry arch scientific theories, which call upon Mechanics and Mathematics to explain the way arches behave and to develop new methods for finding safe dimensions of new structures and assessing the safety of existing ones. This work makes an analytical exam of such theories, in respect to the period that runs from the 15th century, with the writings by Leonardo up to the mid 20th century, at the dawn of computer technology and numerical tools. Paradigm shifts are identified within this time frame which converges to present days disputes between plastic and elastic theory over the field of masonry vaults. This research work relied substantially on primary resources from electronic media, as well as on secondary resources. It describes some of the most influential methods, while considering them in the broad framework of the great theoretical lines. It explores the masonry arch modeled as a system of frictionless wedges, the study of its collapse modes, some historic experiments showing the thrust line existence and behavior, the elastic theory and the limit analysis applied to the masonry arch, among other issues.
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Giol, Julien. "Arcs d'idempotents dans les algèbres de Banach." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12823.
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Cette thèse étudie les arcs d'idempotents dans les algèbres de Banach réelles. D'après Esterle (1983), si deux idempotents p,q sont homotopes, on peut toujours les relier par un arc polynômial d'idempotents. Notre principale motivation est d'estimer le degré minimal d'un tel polynôme. Le second paramètre étudié est le nombre minimal de segments requis pour relier p et q, bien défini également s'ils sont homotopes. Nous obtenons des estimations uniformes et optimales pour ces nombres dans les algèbres de dimension finie, les AF-algèbres, les algèbres de von Neumann de Type I
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Enzell, Jonas, and Markus Tollsten. "Thermal cracking of a concrete arch dam due to seasonal temperature variations." Thesis, KTH, Betongbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209839.
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Concrete dams located in northern regions are exposed to large seasonal temperature variations. These seasonal temperature variations have resulted in cracking in thin concrete dams. Continuous monitoring and evaluation of existing dams are important to increase the knowledge about massive concrete structures and to ensure dam safety. The aim of this degree project is to increase the knowledge about how cracking occurs in concrete dams and how it affects the dam safety. This was achieved by simulating the development of cracks in a concrete arch dam exposed to seasonal temperature variations using finite element analysis (FEA). The accuracy of the model was evaluated by comparing the results with measurements from a Swedish concrete arch dam. Finally, effect of cracks and temperature on the dam safety was investigated. FEA was used to predict the crack pattern and displacements in the arch dam. The analyses were performed both with linear elastic and nonlinear material behavior. Two models were analyzed, in one model the dam was considered to be a homogeneous arch, the other model included contraction joints. The cracking was simulated using temperature envelopes from the location of the Swedish arch dam. To evaluate the displacements in the arch, further analyses were carried out, where the cracked arch dam was exposed to the actual temperature variations at the location. The results were compared to the crack pattern and measurements of displacements of the Swedish arch dam. To investigate the effects from the cracking on the safety of the dam, a progressive failure analyses performed. The results show that the downstream face of the arch cracked under hydrostatic pressure. The cracks propagated further during winter when the temperature load was applied. The resulting crack pattern corresponded well with the survey of the cracks from the Swedish arch dam. The FE-models with nonlinear material developed a horizontal plastic hinge due to excessive cracking in a region halfway down from the crest. The plastic hinge affected the shape of the deflected arch. The magnitude of the displacements and the shape of the deflected arch was captured with the nonlinear models. A safety factor of 3 for internal structural failure in the arch was found in the failure analyses. The safety factor of the arch only decreased slightly due to the cracking. During a cold winter, the safety factor decreased to 2.5.<br>Betongdammar belägna i nordliga klimat blir utsatta för stora säsongsburna temperaturvariationer. Dessa temperaturvariationer har orsakat sprickbildning i tunna betongdammar. Kontinuerlig övervakning och utvärdering av befintliga dammar är viktigt för att öka kunskapen om massiva betongkonstruktioner och för att säkerställa dammsäkerheten. Syftet med det här examensarbetet är att öka kunskapen om hur sprickor uppstår i valvdammar samt hur de påverkar anläggningens säkerhet. Målet är att med finit elementanalys (FEA) analysera uppsprickningen av betongen i en valvdamm som påverkas av säsongsburna temperaturvariationer. Tillförlitligheten i modellen utvärderas genom att jämföra med mätningar från en svensk valvdamm av liknande dimensioner. Slutligen utvärderas hur dammens säkerhet påverkas av sprickbildningen. FE-analys användes för att förutsäga sprickmönstret och förskjutningarna i valvdammen. Analyserna utfördes både med linjärelastiskt och icke-linjärt materialbeteende. Två modeller användes i analysen, i ena modellen betraktades dammen som homogen och i den andra inkluderades gjutfogar. Sprickmönstret simulerades med temperaturcykler baserade på extremtemperaturer tagna intill den svenska valvdammen. För att utvärdera förskjutningarna i dammen gjordes vidare analyser där den spruckna dammen utsattes för temperaturvariationer uppmätta från samma plasts. Resultaten från analysen jämfördes med mätningar av förskjutningar och kartering av sprickor från den svenska valvdammen. För att undersöka hur säkerheten påverkades av sprickbildningen utfördes progressiv brottanalys. Resultaten visar att dammen spricker på nedströmssidan när den utsätts för vattentryck. Sprickorna fortplantas under vintern när temperaturlasten appliceras. Sprickmönstret stämmer överens med kartering av den verkliga dammen. FE-modellerna med icke-linjärt materialbeteende utvecklade en plastisk led längs horisontella sprickor halvvägs ner från krönet. Den plastiska leden påverkade dammens utböjda form. Förskjutningarna och dammens utböjda form i de ickelinjära modellerna stämmer väl överens med de uppmätta förskjutningarna. Vid brottanalysen var säkerhetsfaktorn mot materialbrott i dammen 3. Säkerhetsfaktorn minskade något till följd av sprickorna. Under en kall vinter sjönk säkerhetsfaktorn till 2,5.
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Seibert, Chloé. "Transferts Sédimentaires et Grands Séismes dans l'Arc des Petites Antilles : apport de la Paleosismologie en mer." Thesis, Sorbonne Paris Cité, 2019. https://theses.md.univ-paris-diderot.fr/SEIBERT_chloe_2_complete_20190701.pdf.
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L’Arc volcanique des Petites Antilles, résultant de la subduction des plaques américaines sous la plaque caraïbe, est menacé par des méga-séismes pouvant être générés à l’interface de ces plaques, tel que le séisme de 2004 à Sumatra de Mw 9,3. Le catalogue des séismes historiques ne débutant qu’au 17ème siècle dans l’arc des Petites Antilles, l’aléa sismique n’est connu que sur une courte période et seul deux séismes destructeurs, en 1839 et 1843, ont été interprétés comme le résultat de la rupture de l’interface de subduction, avec des magnitudes estimées supérieures à 8. Il est donc primordial d’obtenir de nouvelles informations sur le potentiel sismogénique de cette zone. Plusieurs méthodologies ont été développées pour retrouver des traces de séismes anciens, dont la paléosismologie en mer est la plus appropriée dans le contexte de l’Arc des Petites Antilles. Cette méthode est basée sur l’analyse d’événements turbiditiques générés par des séismes. Une analyse morpho-sédimentaires, basées sur un important jeu de données d’imagerie (données bathymétriques et d’imageries acoustiques et profils sismiques), a permis de caractériser les transferts sédimentaires actuels ainsi que les forçages qui les contrôlent. Ces données nous ont permis d’identifier deux zones distinctes séparées par le grand escarpement de La Désirade : au Nord, le plancher océanique est caractérisé par des escarpements raides incisés par de nombreux petits canyons et des bassins profonds ; au Sud, la pente insulaire est douce et incisée par des canyons majeurs qui se dirigent vers le seul bassin avant-arc de cette zone. Cette étude nous a permis de mettre en évidence un contrôle tectonique important du système de drainage mais surtout plusieurs bassins isolés des apport sédimentaires de l’arc, qui ont été prioritairement prélevés lors de la campagne en mer CASEIS.Treize carottes sédimentaires longues, prélevées dans les deux secteurs qui ont probablement rompu lors de séismes de 1839 (au large de la Martinique) et de 1843 (au large de la Guadeloupe), ont fait l’objet d’une analyse sédimentologique détaillée (mesures géophysiques, géochimiques, tailles des grains, composition sédimentaire, datations 14C). Les résultats suggèrent que la majorité des turbidites enregistrées sont des événements co sismiques. Dans le secteur de la Guadeloupe, l’étendue des déstabilisations ainsi que des mesures de PGA impliquent que ces séismes soient générés à l’interface de subduction. Parmi ces événements, quatre sont associés des facies sédimentaires particuliers suggérant des paléo tsunamis. Dans le secteur de la Martinique, la temporalité des événements, identiques à ceux enregistrés au large de la Guadeloupe, implique également des séismes générés à l’interface entre les plaques. L’absence de dépôt associé aux séismes historiques suggère que les turbidites documentées sont générées par des séismes moins profonds ou plus importants. La non-synchronicité des événements majeurs malgré des intervalles de récurrence similaires suggère que la subduction des Petites Antilles est segmentée mais qu’une interaction peut exister entre les ruptures des segments<br>The Lesser Antilles Volcanic Arc, resulting from the subduction of the American plates beneath the Caribbean plate, is threatened by large magnitude earthquakes that can be generated at the interface of these plates, such as the Mw 9.3 2004 Sumatra earthquake. The historical seismic catalogue began in the 17th century in the Lesser Antilles, thus the seismic hazard is only known for a short period of time. Only two destructive earthquakes, in 1839 and 1843, were interpreted as megathrust earthquakes, with estimated magnitudes greater than 8. It is therefore essential to obtain new information on the seismogenic potential of this area. Several methods have been developed to find traces of old earthquakes. In the context of the Lesser Antilles Arc, offshore paleoseismology is the most appropriate. This method is based on the analysis of turbiditic events generated by earthquakes. A morpho-sedimentary analysis, based on a large set of imaging data (bathymetric and backscatter data and seismic profiles), characterized the current sediment transfers and their forcing. We identify two distinct areas separated by the Desirade escarpment: northwards, the seafloor is characterized by steep escarpments incised by many small canyons and deep basins; whereas southwards, the insular slope is gentle and incised by major canyons that flow towards the only forearc basin in this area. This study allowed us to highlight an important tectonic control of the drainage system and several basins isolated from the sedimentary inputs of the arc, which were collected during the CASEIS cruise.Thirteen long sedimentary cores, which were collected along the two areas which probably ruptured during the 1839 (offshore Martinique) and 1843 (offshore Guadeloupe) earthquakes, were subjected to detailed sedimentological analysis (geophysical and geochemical measurements, grain sizes analyses, sediment composition, radiocarbon ages). The results suggest that the majority of turbidites recorded are co-seismic events. In the Guadeloupe sector, the extent of destabilization as well as PGA measurements imply that these earthquakes are generated at the subduction interface. Among these events, four are associated with specific sedimentary facies suggesting paleo-tsunamis. In the Martinique sector, the temporality of the events, identical to those recorded offshore Guadeloupe, also involves earthquakes generated at the interface between the plates. The absence of deposition associated with historical earthquakes suggests that documented turbidites are generated by shallower or larger earthquakes. The non-synchronicity of major events despite similar recurrence intervals suggests that subduction in the Lesser Antilles is segmented but that an interaction may exist between segment ruptures
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Randrianandraina, Hery Zo. "Améliorations des méthodes de calcul du transfert radiatif dans des plasmas thermiques : application au SF6." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1331/.
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"A cause de sa forte dépendance géométrique et spectrale, la prise en compte du rayonnement et du transfert radiatif dans les modèles se fait à travers des méthodes approchées. Pour valider leur utilisation et apporter d'éventuelles améliorations, nous confrontons ces méthodes à un calcul " exact ". Dans ce travail, nous décrivons finement le spectre d'un plasma de SF6 avec près de 300000 points en fréquence (ou longueur d'onde). A partir de ce découpage, nous avons calculé la divergence du flux radiatif soit à partir de la méthode approchée du coefficient d'émission nette (CEN) basée sur une simplification géométrique du plasma, soit à partir de coefficients moyens d'absorption (CMA) obtenus après découpage du spectre en 7 intervalles spectraux pour lesquels le rayonnement est supposé invariant avec la fréquence dans chacun d'entre eux, soit à partir d'un calcul " exact " correspondant à la résolution directe de l'équation du transfert radiatif. Nous avons également calculé le flux radiatif à partir des deux dernières méthodes, le coefficient d'émission nette ne permettant pas le calcul de cette grandeur. Les différentes étapes de calcul y sont présentées mettant en évidence l'influence de certains paramètres comme le nombre de points utilisés pour discrétiser le spectre, l'erreur commise lors de l'utilisation du facteur de fuite revenant à négliger le chevauchement des raies, les largeurs des raies à considérer pour le calcul des profils correspondant, le nombre de directions à prendre en compte dans le calcul de la divergence du flux radiatif. . . Pour la détermination des coefficients moyens d'absorption, plusieurs moyennes ont été testées: moyenne de Planck, moyenne de Rosseland et moyenne classique. Les calculs ont été réalisés pour des configurations simples (1D, 2D et 3D) simulant un plasma cylindrique dont la température ne varie qu'en fonction du rayon. Une grande partie de ce travail porte sur la comparaison des résultats obtenus par le calcul " exact " avec ceux déduits des différentes approchées dans le but de valider leur utilisation ainsi que leur précision. L'analyse des résultats obtenus nous amène à définir de nouveaux intervalles spectraux et de nouvelles moyennes comme par exemple la combinaison de la moyenne de Planck et de la moyenne classique. Cette étude a été effectuée pour unplasma de SF6 utilisé dans les disjoncteurs à haute tension, mais pourrait être généralisée pour tout plasma thermique à condition que l'équilibre thermodynamique local soit réalisé. "<br>Because of a strong spectral and geometric dependence, the consideration of the radiation and the radiative transfer in the numerical models is done through approximate methods. To validate their use and to bring any improvement, we have compared these methods with the "exact" calculation. In this work, we have carried out a detailed description of the spectrum of SF6 plasmas with about 300000 points on frequency. From this description, we have calculated the divergence of the radiative flux either from the net emission coefficient (NEC) based on a geometric simplification of the plasma, or from the mean absorption coefficients (MAC) calculated after a division of the spectrum into 7 intervals in which we have assumed a constant radiation for each of them, or from an exact calculation corresponding to a direct solution of the radiative transfer equation. We have also calculated the radiative flux from the two last methods since the net emission coefficient is not adapted to estimate this property. The different steps of the work are presented and highlight the influence of several parameters such as the number of points used to discretize the spectrum, the discrepancies observed when we use the escape factor to estimate the emission or the absorption of the lines, the influence of the lines overlapping, the integration of the lines' profiles, the number of directions to consider in order to estimate correctly the divergence of the radiative flux. . . For the mean absorption coefficients, three definitions have been tested : the Planck mean, the Rosseland mean and the classical mean. All calculations have been done for simplified configurations (1D, 2D and 3D) assuming a cylindrical plasma for which the temperature profile varies only with the radius. A great part of this work deals with the comparison between the results obtained from the exact resolution with the results deduced from the other approaches in order to validate the use and the accuracy of the different methods. The results' analysis leads us to redefine new spectral intervals and new mean functions as the combination of the Planck mean and the classical mean. This study have been performed for SF6 plasmas used in high voltage circuit breakers but it could equally be generalized for any thermal plasma in local thermodynamic equilibrium
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Bonnet, Éric. "De l'arc comme variation du champ pictural." Paris 1, 1994. http://www.theses.fr/1994PA010677.
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Interroger les rapports et les interactions de l'arc et du champ pictural: génération, désignation, variation, sont les objectifs de cette thèse. Dans la mise en place de dualités, opposant la tension d'une ligne cursive et séparatrice, à l'intensivité d'un fond monochrome et sorud, ce dernier est identifié à l'écran d'oubli, et suscite l'anamnèse. L'écriture d’Edmond Jabes vient, en écho de cette deuxième dualité, ouvrir un dialogue entre texte et peinture. La mise en évidence du champ pictural conduit l'auteur à interroger cette notion dans son extension et sa profondeur, comme porteuse de tensions potentielles et de contradictions susceptibles de générer un nouveau type d'espace : la profondeur plate, caractéristique de l'espace Pollock ou de certaines œuvres de Mondrian. Monet, Bonnard, Malevitch, Strzeminski, Tal Coat et Ryman sont étudiés dans cette perspective. Les notions d'espace lisse et d'espace strie, chez Deleuze et Guattari, apportent un éclairage sur les conflits internes du champ, comme opposition entre la désignation concrète des termes du tableau, et la perte des repères, le trouble de la surface. La courbure de l'arc est la figure et l'opérateur de ces perturbations, ouvrant a de nouveaux champs<br>Interrogate the connexions and the interactions between arc and painting field : generation, designation, variation, are the objectives of this thesis. The setting up of dualities, opposing the cursive and separative line tension, to the non-tensivity of a monochromatic and hollow ground, the latter is identified to the forgetfulness screen, and arouses remembrance. Edmond Jabes's writing comes, as an echo of this second duality, to open a dialogue between text and painting. The focusing on painting field leads the author to interrogate this knowledge in its extent and its depth, as a carrier of potential tensions and contradictions generating a new model of space : the flat depth, characteristic of Pollock's space, or of several Mondrian's works. Monet, Monnard, Malevitch, Strzeminski, Tal Coat and Ryman are studied in this prospect. The knowledges of soft space and striated space, with Deleuze and Guattari, carry a lighting over internal conflicts of the field, as opposition between concrete designation of the painting's terms, and the loos o f marks, the surface desorder. The arc curve is the figure and the operator of these disturbances, opening to new fields
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Augeard, Amaury. "Etude des risques d'arc électrique dans les batteries lithium-ion." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22616.
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La sûreté de fonctionnement des batteries est un point clé pour la croissance de ce marché et le déploiement de solutions hybrides afin de réduire la consommation d’énergie. L’électrification croissante de ces systèmes ne fait qu’aggraver l’augmentation de l’occurrence de ce problème qui bien que connu depuis longtemps dans le domaine des applications DC ne fait l’objet de recherches intensives que depuis peu comme en témoigne le développement récent des premiers détecteurs d’arc pour l’aviation. L’arc dans les batteries représente aujourd’hui un risque potentiel pour l’intégrité du matériel et des personnes du fait de l’utilisation des batteries au sein d’applications industrielles de fortes puissances. Afin de caractériser ce risque et d’en évaluer la dangerosité, plusieurs bancs d’essais sont réalisés au niveau élément et système afin de reproduire le phénomène d’arc électrique. Les essais réalisés permettent d’extraire les caractéristiques intrinsèques de l’arc. En complément de cette caractérisation, un modèle d’arc permettant d’évaluer les paramètres et d’améliorer la compréhension de ce phénomène est réalisé. Des solutions de limitation, voire de suppression de l’arc issues de cette étude sont proposées. Parmi ces nombreuses solutions, l’utilisation de capteurs optiques, les méthodes numériques pour le traitement des signaux issus de l’arc, la modification de l’architecture batterie ainsi que l’augmentation du niveau de tension lors de l’amorçage de l’arc ouvrent la voie à la conception de systèmes de batteries innovants et plus sûrs en termes de fiabilité, sécurité et de robustesse. Les nombreuses perspectives de recherches proposées permettront également d’améliorer la couverture de ce risque<br>The operational security of batteries is a key element in the growth of this market and the deployment of hybrid solutions to reduce energy consumption.The increasing electrification of these systems can only exacerbate the occurrence ratio increase of this problem. Although known for a number of years in the field of DC applications, electric arcs are the subject of intensive research for a short time as shown by the recent development of the first arc sensors for aviation. Electric arcs in batteries currently represent a potential risk to the integrity of the equipment and people because of the use of these batteries in industrial high power applications. To characterize this risk and assess its dangerousness, several test benches were designed at the cell and system level to reproduce the electric arc phenomenon. The tests carried out allow extracting the intrinsic characteristics of the arc. In addition to this characterization, an arc model to evaluate the parameters and improve the understanding of this phenomenon is realized. Limiting mitigation solutions or suppression of the arc resulting from this study are proposed. Among the many solutions, the use of optical sensors, the numerical methods for digital signal processing from the arc, the modification of the architecture as well as the increase of the arc ignition voltage pave the way for the design of innovative and safer batteries systems in terms of reliability, security and robustness. The numerous proposed research perspectives will also improve the coverage of this risk
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Dias, Neto David. "Modélisation de la dépendance dans l'analyse multivariée des séries financières." Paris 1, 2004. http://www.theses.fr/2004PA010013.
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Les séries financières sont connues pour présenter de nombreuses "anomalies" qui portent à mal l'inférence statistique traditionnelle basée sur la normalité des processus. Les faits stylisés observés dans l'analyse statistique univariée sont essentiellement l'hétéroscedasticité variable dans le temps et le caractère leptokurtique et asymétrique des distributions empiriques. En analyse multivariée vient s'ajouter à ces difficultés celle de la spécificité de la dépendance qui a pendant longtemps été absente de la littérature économétrique. Ce n'est que très récemment, avec la redécouverte des fonctions copules, que cet aspect a pris une place non négligeable dans les études économétriques. Cette thèse a pour objet de montrer que les structures de dépendance des séries financières, lorsqu'elles font l'objet d'une analyse jointe, correspondent rarement au cas Gaussien.
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Makha, Ramonate. "Calibration of an arch dam model by the finite element method using ambient vibration testing." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/14555.
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Includes bibliographic references.<br>The finite element model of an arch dam was calibrated for dynamic behaviour using the measured natural frequencies and mode shapes as benchmarks. The properties were extracted from the structure using ambient vibration testing techniques. Besides the geometry and general material properties of the dam wall concrete and foundation rock, the measured frequencies and mode shapes depend on the conditions at the dam site namely water level, temperature and the interactions between the several components of the dam. This study, however investigated the effects of the water level and to some extent, the effect of dissimilar foundation abutment material properties on the natural frequencies of the dam. A dam is continuously in harmonic motion due to some environmental factors such as wind. Either due to this movement of the dam itself or the internal movement of the reservoir water, a dynamic interaction occurs between the water and the dam wall where the movement of the one medium affects the other. A study conducted in the early twentieth century deduced that it is only part of the reservoir water that can be assumed to interact with the dam. It is from the same study that the Westergaard added mass concept was born which says that the interacting water mass can simply be added to the dam wall mass, a procedure from which the extraction of the dynamic properties can ensue as normal. This added mass formulation was derived on a basis of some assumptions which include a rigid and vertical dam wall and the incompressible water body. The added mass concept was extended to account for flexibility and curvature of the upstream dam wall in more recent studies. The extended version of the Westergaard method is normally referred to as the generalized Westergaard method. The original Westergaard added mass formulation was used to account for the dam wall- water interaction in the double curved Roode Elsberg dam model. This proved to be problematic as this dam is highly asymmetrical and has diverging reservoir walls, the characteristics of which are not catered for in the original Westergaard added mass method. The combined effect of using the original Westergaard method and these deficiencies in the formulation resulted in the model's natural frequencies being lower than the field ones, for the same ambient conditions. On the basis of literature, a factor of 0.8 on the added masses was applied on all the original Westergaard added masses to account for the effect of the diverging reservoir walls. The remaining masses were then reduced until a good correlation of the field frequencies and model frequencies was achieved. This was done to account for the effects of the flexibility of the dam and the curved upstream dam wall. All in all, a factor of 0.25 on the masses calculated using the original Westergaard added masses was applied to account for all the above-mentioned effects. This factor compares favourably with literature even though in literature it is rarely mentioned what effects are being accounted for when this factor is introduced. This work hence raises awareness about the shortcomings of the Westergaard method when used for model calibration and how those shortcomings can be accounted for. In summary, these shortcomings are brought about by assuming a prismatic and infinite reservoir, while in reality this is not always the case. It appears that these shortcomings affect the results of the added mass approach when used as a tool to represent the dam-water dynamic interaction in arch dams.
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Ielpo, Florian. "L'intégration de l'information dans le prix des actifs financiers." Phd thesis, Université Panthéon-Sorbonne - Paris I, 2008. http://tel.archives-ouvertes.fr/tel-00354454.
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Le sujet principal de cette thèse est l'intégration de l'information macroéconomique et financière par les marchés financiers. Les contributions présentées ici sont au nombre de cinq. Les trois premières utilisent de récentes avancées de l'économétrie de la valorisation d'actifs. L'objectif est de mesurer les anticipations, l'aversion au risque ou simplement de prévoir le prix des produits dérivés. (1) Tout d'abord, on introduit une nouvelle méthode économétrique permettant d'estimer l'évolution de la distribution subjective à partir des futures sur taux d'int´erˆet.(2) Ensuite, à partir des cotations d'options et des futures sur le marché européen du Carbone, on met en évidence l'impact de la publication des quotas d'émission attribués par la Commission Européenne sur l'aversion au risque dans ce nouveau marché. (3) Puis, on présente un nouveau modèle d'évaluation de produits dérivés basé sur des rendements suivant une loi hyperbolique généralisée sous la mesure historique. En supposant que le noyau de prix est une fonction exponentielle affine de la valeur future du sous-jacent, on montre que la distribution risque neutre est unique et à nouveau conditionnellement hyperbolique généralisée. Le modèle conduit à de faibles erreurs de prix, lorsqu'on les compare à la littérature existante. Enfin, deux thèmes li´es à l'impact des nouvelles macro-économiques sur la courbe des taux sont présentés ici: (4) on montre tout d'abord que la perception de l'impact d'une surprise sur le marché des taux européens est grandement modifiée lorsque l'on tient compte de l'influence américaine. (5) Ensuite, on quantifie l'intuition largement répandue selon laquelle la forme de la structure par terme de l'impact des nouvelles sur la courbe des taux d´epend des conditions économiques et monétaires, et ceci dans le cas américain.
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Laleh, Haeedeh. "La Structure fondamentale des arcs dans l'architecture saldjukide de l'Iran." Paris 4, 1989. http://www.theses.fr/1989PA040056.
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Nous avons étudié les arcs dans cinq salles à coupole-maksurasaldjykide dans deux régions d'Isfahan et de Kazwin : la maksura et la salle nord du djami d'Isfahan ; les maksuras de la mosquée de Barsian ; du djami et de la mosquée de Haydariyya à Kazwin. Dans ces édifices l'arc est l'élément essentiel de l'architecture et du décor. Son analyse a permis de distinguer deux écoles architecturales au centre et au Nord ouest de l'Iran. La construction de ces édifices a donné l'occasion aux architectes de faire preuve d'originalité dans la parfaite adaptation des éléments et des procédés de construction antérieurement amorcés. .<br>We have studied the arches in five significant Saljuk domed chambers located in two important regions : Isfahan and Kazwin. .
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Karoui, Khaled. "La restitution des arcs de Dougga dans leur contexte urbain." Bordeaux 3, 2011. http://www.theses.fr/2011BOR30065.
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Costa, Fabricio Ricardo Ginez. "Prevalência e correlação das dimensões oclusais transversais em pacientes com diferente diagnóstico de obstrução respiratória." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-01042015-141840/.
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Introdução: Dentre as alterações da má-oclusão dentária na primeira dentição, destaca-se a mordida cruzada posterior, a qual consiste numa relação de sobressaliência vestibular inversa dos dentes superiores com seus antagonistas inferiores. O crescimento das estruturas faciais é composto de múltiplas atividades funcionais inter-relacionadas por diferentes componentes da cabeça e pescoço. A respiração nasal é um dos elementos de atividade funcional. Se houver obstrução nas vias aéreas superiores, haverá adaptações funcionais na direção de crescimento das estruturas do esqueleto da face. A hiperplasia das tonsilas faríngeas e/ou palatinas associadas são uma das causas mais comuns de obstrução respiratória. Objetivos: investigar a prevalência da mordida cruzada posterior em crianças de 3 a 6 anos de idade e associá-la ao padrão respiratório; verificar se houve associação desta má-oclusão com o tipo da hiperplasia das tonsilas palatinas associadas ou não com tonsilas faríngeas; realizar uma análise comparativa em crianças respiradoras orais e respiradoras nasais na idade categorizada 3-4 anos e 5-6 anos nos seguintes aspectos: distâncias da largura dos arcos por meio das distâncias intercaninos e intermolares da maxila e mandíbula. Casuística e Métodos: Participaram deste estudo 53 crianças, meninos e meninas com hiperplasia das tonsilas faríngea e/ou palatinas provenientes do ambulatório da Divisão da Clínica Otorrinolaringológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo - HCFMUSP, com indicação de adenoamigdalectomia ou adenoidectomia. Os pacientes foram submetidos a exame físico otorrinolaringológico, além de fibronasofaringoscopia ou Raios- X de Cavum. O grupo controle foi de 41 crianças sem queixas de obstrução respiratória levantada por questionários dirigidos aos pais, oriundas de escolas do município de Itapetininga-SP. Todas as crianças foram avaliadas por um cirurgião dentista que mensurou a largura dos arcos dentários diretamente na boca por meio de um paquímetro digital. Resultados: A mordida cruzada posterior esteve presente em 9,57% do total da amostra. A prevalência do cruzamento posterior no grupo de estudo foi de 15,09% e, no grupo controle, 2,13%. Foram encontradas nos diferentes tipos de hiperplasia linfoide as seguintes frequências de cruzamento posterior: palatina isolada (16,67%); faríngea isolada (25%); e palatina e faríngea associada (7,41%). A largura dos arcos dentais no grupo de estudo, apesar de não apresentar relevância estatística quando comparado com o grupo controle na idade de 3-4 anos, mostrou-se com as maiores médias. Já na idade de 5-6 anos, mostrou-se com as menores médias. Conclusões: A prevalência de mordida cruzada em respiradores orais é 15,09%. Observou-se uma tendência associativa da mordida cruzada posterior nas crianças do grupo de estudo. Na associação do tipo de obstrução respiratória com a presença do cruzamento posterior, não houve diferença estatística. Quanto à análise da largura dos arcos dentais em relação à idade categorizada, verificou-se, no grupo controle, uma diferença estatisticamente significante da idade de 5-6 anos em relação à idade 3-4 anos. Esta diferença, porém, não foi encontrada no grupo de estudo<br>Introduction: Among the alterations of dental malocclusion in the first dentition, the posterior crossbite stands out, which consists of a relation of vestibular reverse overjet of superior teeth with their inferior antagonists. The growth of facial structures consists of multiple functional activities interrelated by different components of the head and the neck. Breathing through the nose is one of the elements of functional activity. If there is obstruction in the superior airway, there will be functional adaptations in the growth direction of face skeleton structures. The hyperplasia of the adenoids and/or associate palatine tonsils is one of the most common causes of airway obstruction. Objectives: Probe the prevalence of posterior crossbite in children from 3 to 6 years old and associate it to the respiratory pattern; verify if there is association of such malocclusion with the etiology of hyperplasia of palatine tonsils associate or not with hyperplasia of the adenoids; carry out a comparative analysis in children who breathe through their mouth and nose at the categorized age of 3-4 years old and 5-6 years old in the following aspects: arch width distances by means of maxillary and mandibular intercanine and intermolar distances. Casuistry and Methods: A total of 53 children took part in the study herein, boys and girls with hyperplasia of the adenoids and/or associate palatine tonsils coming from the ambulatory of the Division of Otorhinolaryngology, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo - HCFMUSP, with indication of tonsillectomy or adenoidectomy. The patients have been submitted to an otorhinolaryngological physical examination, in addition to nasal fiber pharyngoscopy or Cavum x-ray. The control group consisted of 41 children with no complaints of airway obstruction surveyed by questionnaires forwarded to their parents, children coming from schools of the municipality of Itapetininga, State of São Paulo. All children have been evaluated by a dental surgeon who has measured their dental arch width directly in the mouth by means of a digital calliper. Results: The posterior crossbite was present in 9.57% out of the total of the sample. The prevalence of posterior cross in the study group was 15.09% and, in the control group, 2.13%. The following frequencies of posterior cross have been found in different etiologies of lymphoid hyperplasia: isolated palatine (16.67%); isolated pharynx (25%); and associated palatine and pharynx (7.41%). The dental arch width in the study group, in spite of not presenting statistical relevance when compared to the control group at the age of 3-4 years old, was shown with the highest averages. On the other hand, at the age of 5-6 years old, lowest averages were shown. Conclusions: The prevalence of crossbite in children who breathe through their mouth is of 15.09%. An associated trend of posterior crossbite in children of the study group has been observed. In the association of the type of airway obstruction with the presence of posterior cross, there was no statistical difference. As per the dental arch width analysis in regards to the categorized age, in the control group, a statistically significant difference was verified at the age of 5-6 years old regarding the age of 3-4 years old. Such difference, however, was not found in the study group
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Chemartin, Laurent. "Modélisation des arcs électriques dans le contexte du foudroiement des aéronefs." Rouen, 2008. http://www.theses.fr/2008ROUES055.
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Ce travail porte sur l'étude des arcs électriques dans le contexte du foudroiement des aéronefs. Une modélisation tridimensionnelle et instationnaire de l'arc de foudre est réalisée à l'aide d'un modèle magnétohydrodynamique résistif, qui s'appuie sur les hypothèses d'un plasma à l'équilibre thermodynamique local, d'un écoulement incompressible et dilatable et d'un champ électromagnétique statique. Cette modélisation permet de simuler deux aspects caractéristiques de l'arc qui interviennent dans un foudroiement d'aéronef. Le premier porte sur sa tortuosité et ses mouvements chaotiques, que l'on compare à des mesures expérimentales obtenues au niveau de la mer. Les simulations faites à des altitudes de vol de l'aéronefs (changement de la densité de l'air) ne modifient pas les caractéristiques de l'arc, validant la représentativité des essais de certification au sol. Le second aspect étudié porte sur l'interaction de l'arc avec la surface foudroyée. Il s'agit de simuler un dispositif d'essais de certification de matériau qui reproduit en laboratoire les conséquences d'un foudroiement. Les simulations de ce dispositif mettent en évidence le rôle fondamental des forces magnétiques et convectives dans le déplacement tridimensionnel de l'arc en accord avec les observations. L'analyse des simulations a permis d'élaborer une modélisation axisymétrique de l'interaction du pied d'arc avec le matériau à tester au moins 50 fois plus économique en coût de calcul. Les résultats de simulation montrent, en accord avec les observations, que les dommages occasionnés sur la plaque d'aluminium étudiée sont plus importants lorsque cette plaque est une cathode et qu'ils augmentent avec le courant pour une même quantité de charge injectée<br>This work concerns the study of electric arcs in the context of lightning strike to aircraft. A three-dimensional modelling of unsteady lightning arc, based on the resistive magneto hydrodynamic equations, is performed assuming Local Thermal Equilibrium, incompressible and expandable flow and static electromagnetic field. This modelling allows to compute two main characteristics of the arc that occur during a lightning strike to aircraft. The first one deals with the tortuosity and the chaotic motions, which are compared to measurements obtained at mean sea level. Simulations at usual aircraft flight altitudes (by changing the air density) do not modify the lightning channel main properties, which validate the mean sea level lightning test device. The second aspect concerns the study of the interaction of the arc with a blasted surface. The goal is to simulate a lightning test device which recreates in a laboratory the lightning damages. The simulations bring to light the fundamental role of the magnetic and the convective forces on the three-dimensional arc displacement, already observed during lightning test. The analysis of the simulations allows to develop an axisymectric modelling of the arc root interaction with the material, which reduces fifty times the calculation cost. Results show that, in agreements with observations, the damages bring on an aluminium panel are more important when this panel is a cathode, and increase with the current for the same charge transfer
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Maftoul, Joseph. "Etude de l'extinction spontanée des arcs à faible courant dans l'air." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37607592x.
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Bezerra, Valeria Matos. "Alterações das dimensões dos arcos dentários e das inclinações dos incisivos produzidas pelo Sistema Damon." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/25/25144/tde-05042013-102219/.
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PROPOSIÇÃO: O objetivo deste trabalho foi descrever as alterações das dimensões dos arcos dentários e das inclinações dos incisivos produzidas pelo Sistema Damon, durante a fase de alinhamento e nivelamento. Outro objetivo foi verificar a correlação destas alterações com o padrão de crescimento dos indivíduos. MATERIAL E MÉTODOS: modelos de estudo, telerradiografias convencionais e telerradiografias reconstruídas a partir de tomografias computadorizadas cone-beam de 22 casos tratados com o bráquetes Damon 3MXTM foram avaliados durante a fase de alinhamento e nivelamento. Os modelos de estudo foram obtidos ao início do tratamento (T0), após a primeira troca de fio (T1) e na inserção do fio de aço 0,019 x 0,025 (T2). Foram verificados os comprimentos de arco e as dimensões transversais nas regiões de caninos, primeiros e segundos pré-molares e primeiros molares mensuradas a partir das pontas de cúspides e margens gengivais linguais dos dentes, a cada etapa. Nas telerradiografias foram verificadas as alterações das inclinações dos incisivos inferiores e superiores, bem como o padrão de crescimento dos indivíduos. RESULTADOS: os comprimentos dos arcos e todas as distâncias transversais apresentaram aumentos significantes, com exceção da distância intercervical dos caninos superiores; houve aumento significante das inclinações vestibulares dos incisivos superiores e inferiores; o padrão de crescimento dos pacientes apresentou correlação significante com os aumentos transversais na região de pré-molares inferiores. CONCLUSÕES: o alinhamento e nivelamento de casos tratados sem extrações com o uso do Sistema Damon resultou no aumento significante das dimensões dos arcos dentários e das inclinações dos incisivos para vestibular.<br>OBJECTIVE: This study aimed to evaluate the dental arch widths and incisor torque changes produced by the Damon System during leveling and alignment. Other objective was to verify the correlation between these changes and the growth pattern. MATHERIAL AND METHODS: study casts and lateral radiographs derived from cone-beam computed tomographies of 22 subjects treated with Damon 3MXTM brackets were evaluated. The study casts were obtained at the start of treatment (T0), the first archwire change (T1), and the placement of the final 0,019 x 0,025-in archwire (T2). Arch depth and widths (intercanine, interpremolar and intermolar) were assessed at each stage. The incisor torques changes and the growth pattern were measured on the cephalometric records at T0 and T2. RESULTS: There was significant increase of the arch depths and lateral expansion of the arches for all measures, except for the intercervical of maxillary canines. The maxillary and mandibular incisors were significantly tipped labially; the growth pattern showed significant correlation with the lateral increases in lower premolars region. CONCLUSIONS: nonextraction cases treated with Damon System show significant increases in arch dimensions and incisors proclination.
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Hellgren, Rikard. "Influence of Fluid Structure Interaction on a Concrete Dam during Seismic Excitation : -Parametric analyses of an Arch Dam-Reservoir-Foundation system." Thesis, KTH, Betongbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145655.
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The aim of this study is to investigate how Fluid-Structure interaction is included in numerical earthquake analyses of dams. The base for this project is theme A from the 12th international benchmark workshop on numerical analysis of dams, which was held in October 2013. The focus of theme A was how to account for the fluid structure interaction in numerical earthquake analyses of dams. To highlight how engineers and researchers include this interaction in their analysis, a literature review of the modeling choices and conclusions from all participants are included. Since the workshop contains participants from seven countries, this review aims to describe of how this analysis is carried out in practice. Further, parametric numerical analyses are performed in this study, where the purpose is to isolate some important parameters and investigate how these influence the results in seismic analyses of dams. These analyses were performed through the use of the finite element method. The geometric model from the benchmark workshop was used and analysed with the commercial software Abaqus. The studied parameters are the choice of fluid element, Rayleigh damping parameters, reservoir boundaries and wave absorption in the foundation-reservoir interface. The water has a major effect on a dam's seismic behaviour and should be included in the analysis. The added mass approach gives similar results compared with a more sophisticated method. This simplified approach could be used in engineering purpose where the time is limited and the accuracy is of lesser importance, since the calculated stresses are conservative. Using acoustic finite elements provides a reasonable computation time, while also allowing for more advanced features, such as bottom absorption and non-reflecting boundaries The definition of Rayleigh damping has proven to be a very challenging task, especially as it has a large impact on the results. The choice of boundary conditions for the back end of the reservoir was the parameter that least influenced the results. The conservative approach is to use a fixed boundary where all pressure waves are reflected. The reflection coefficient for the foundation-reservoir interface has a large influence on the results, both for the participants that used this coefficient in the benchmark workshop and for the analyses presented in this study. The coefficient should therefore be used carefully.<br>Syftet med denna studie är att undersöka hur fluid-struktur interaktion inkluderas i numeriska jordbävningsanalyser av dammar. Detta ämne var ett av de teman som behandlades vid den 12:e internationella benchmark-workshopen för numerisk analys av dammar som hölls i oktober 2014 i Graz, österike. För att visa hur ingenjörer och forskare tar hänsyn till denna interaktion har en litteraturstudie på bidragen till workshopen genomförts. Då workshopen lockade deltagare från universitet och konstruktionsfirmor från sju länder, är målet att kunna beskriva hur jordbävningsanalyser av dammar utförs i praktiken. Dessutom har numeriska parameterstudier genomförts, med syfte att isolera enskilda parametrars inverkan vid seismiska anslyser av dammar. Analyserna har utförts med finita elementmetoden och analyserna är utförda med den geometriska modellen som användes i workshopen. Alla analyser har utförts i programmet Abaqus. De analyserade parametrarna är, val av fluid-element, Rayleigh dämpningsparametrar, randvillkor för reservoaren samt tryckvågsabsorption i gränsytan mellan reservoar och berg. Vattnet har en stor inverkan på dammen och de hydrodynamiska effekterna bör inkluderas vid en jordbävningsanalys. Metoden med impulsiv massa ger liknande resultat jämfört med mer sofistikerade metoder. Denna enklare metod kan användas i samanhang där beräknings och modelleringstid är begränsad och noggrannhet är av mindre intresse så länge resultaten är konservativa. För tillämpningar där noggrannheten är viktigare kan akustiska element användas för att beskriva vattnet. De akustiska element ger möjligheter för mer sofistikerade analyser där t.ex. vågabsorption och icke reflekterande gränser kan beaktas. Att välja Rayleigh dämpning visade sig var en väldigt utmanande uppgift, där valet hade stor påverkan på resultaten. Valet av randvillkor för reservoarens bortre ände var den parameter som hade minst påverkan på resultaten. Det konservativa valet är att välja en ''fixed'' gräns med full reflektion av tryckvågor. Reflektionskoefficienten för interaktionen mellan vatten och berg visade sig ha en stor inverkan på resultaten, både för de deltagare i workshopen som valde att använda denna koefficient och för de analyser som presenteras i denna studie. Denna koefficient bör därför användas med försiktighet.
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Chapelle, Pierre. "Étude expérimentale et modélisation de l'arc électrique dans le procédé de refusion var." Vandoeuvre-les-Nancy, INPL, 2001. http://www.theses.fr/2001INPL004N.
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Le comportement de l'arc électrique dans le procédé de refusion var conditionne les distributions d'énergie et de courant électrique au sommet du lingot, ainsi que le transport des espèces volatiles dans la phase gazeuse. Une étude expérimentale de l'arc électrique est menée sur un four var industriel instrumenté, lors de la refusion d'un alliage de zirconium. Des observations par vidéo rapide synchronisées avec l'enregistrement à haute fréquence de la tension d'arc permettent de décrire le comportement de l'arc électrique et ses interactions avec les mécanismes de transfert des gouttes de métal liquide de l'électrode au lingot. Un diagnostic, résolu spatialement, du plasma d'arc par spectroscopie d'émission optique permet de déterminer la proportion relative et la température d'excitation des différentes espèces de particules composant le plasma. A partir des résultats expérimentaux obtenus et de l'analyse de la bibliographie relative aux arcs sous vide crées entre deux électrodes solides, nous proposons une démarche de modélisation de l'arc électrique, basée sur une représentation de l'arc comme un ensemble de clusters identiques et indépendants. Dans ce travail, nous nous focalisons sur la description d'un cluster unique, qui combine deux modèles : un modèle cinétique de la formation du plasma dans la région adjacente a la cathode et un modèle hydrodynamique bidimensionnel a deux fluides du jet de plasma en expansion sous vide dans l'espace interélectrode. Le modèle ainsi construit donne accès à la composition du plasma (degré d'ionisation, distribution du nombre de charge des ions) et permet de calculer les grandeurs macroscopiques (densité, vitesse et température) des différentes espèces du jet de plasma, ainsi que la densité de courant électrique et la densité de flux d'énergie cédées par le jet à l'anode. En particulier, le pourcentage de la puissance électrique du cluster transmis par le jet de plasma au bain liquide anodique, prédit par notre calcul (environ 24%), est en bon accord avec la valeur donnée dans la littérature.
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Bolender, Yves. "Influence des variations de température rencontrées dans la cavité buccale sur les propriétés physiques des arcs orthodontiques à base de nickel-titane." Thesis, Nancy 1, 2008. http://www.theses.fr/2008NAN10144/document.
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Cette étude a tenté de caractériser dix types de fil orthodontique à base de nickel-titane de section 0,017x0,025 pouces et de vérifier l’influence de la température sur leur structure et leurs propriétés mécaniques. Les fils se révèlent sous dimensionnés dans leur section. Les états de surface apparaissent hétérogènes. La composition permet de distinguer les alliages de type nickel-titane des alliages cuivre-nickel-titane. Une diversité certaine des types et températures de transition est observée en calorimétrie différentielle à balayage (DSC). La diffraction des rayons X des fils Neosentalloy 100gR et Copper NiTi 35°CR, confirme les transitions détectées par DSC. Le comportement en torsion des fils varie selon la température. La quasi-totalité des fils testés ne possède pas en torsion de propriétés superélastiques à la température buccale moyenne de 35°C<br>This study aims to characterize ten of the most commonly used .017x.025 in. NiTi archwires and to test the influence of temperature on their structure and mechanical properties. Archwires height and width are below nominal values. Surface characteristics are diverse. Two different compositions are identified : the nearly equiatomic NiTi alloys, and the Copper NiTi alloys. The diverse transition types and temperatures defined by differential scanning calorimetry (DSC) confirm the heterogeneity of our sample. X-ray diffraction of the Neosentalloy 100gR and Copper NiTi 35°CR wires confirms the two and one-step transitions displayed by these wires in DSC. Torsional properties are temperature-dependent. Most archwires do not display superelasticity at the mean buccal temperature of 35°C
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Triviño, Tarcila. "DETERMINAÇÃO DAS FORMAS DO ARCO DENTÁRIO INFERIOR NA OCLUSÃO NORMAL NATURAL." Universidade Metodista de São Paulo, 2005. http://tede.metodista.br/jspui/handle/tede/1231.
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Previous issue date: 2005-03-02<br>In order to determine the lower dental arch form of major incidence in the natural normal occlusion, a mathematic method associated with a polynomial function was
applied on 63 study models of the lower arcade, which were selected among 6118 adolescents. All these patients were in permanent dentition, including second
molars, with natural normal occlusion. A small pearl (bead) was glued to each dental element, which would simulate the orthodontic accessory and help to
measure the distances between the center of the bead to axes x and y . The plaster models were, then, digitalized and the images were plotted on a computer
program to obtain the polynomial function of sixth degree, as well as the graph of this function for the entire one hundred and twenty six curve segments, which were originated from the right and left sections of the images based on sixty three models. These segments were organized, according to the characteristics of the anterior curvature, in eight groups according with the eight different types of arch
forms, which received the following denominations Form A, Form B, Form C, Form D, Form E, Form F, Form G, Form H. Each group was, then, divided into three
sub-groups, which represented the sizes small, medium and large. The results indicated 23 most representative forms of the lower dental arch and a medium form for the natural normal occlusion.<br>Com a finalidade de determinar as formas do arco dentário inferior de maior incidência na oclusão normal natural, utilizou-se um método matemático associado ao emprego de uma função polinomial, o qual foi aplicado a 63
modelos de arcadas inferiores selecionados a partir de 6118 adolescentes. Todos os indivíduos eram portadores de dentição permanente, incluindo os segundos
molares, e oclusão normal natural. Em cada dente foi fixada uma esfera de vidro, que teve a função de simular o acessório do aparelho ortodôntico, sendo utilizada
na medição das distâncias entre o centro da imagem dessas esferas aos eixos x e y. Após a digitalização dos modelos de gesso, as imagens foram plotadas em um
programa de computador, a fim de se obterem a função polinomial de sexto grau e o gráfico dessa função para os 126 segmentos de curva, originados das secções das imagens em lado direito e esquerdo. A seguir organizaram-se esses segmentos, de acordo com as características da curvatura anterior dos arcos dentários, em oito grupos diferentes de formas, que receberam as denominações de Forma A, Forma B, Forma C, Forma D, Forma E, Forma F, Forma G, Forma H.
Cada grupo foi, então, dividido em três subgrupos, conforme os tamanhos pequeno, médio e grande. Os resultados indicaram 23 formas representativas do
arco dentário inferior e uma forma média para a oclusão normal natural.
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Costa, Carina Martins. "Uma arca das tradições: educar e comemorar no Museu Mariano Procópio." reponame:Repositório Institucional do FGV, 2011. http://hdl.handle.net/10438/8991.
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Previous issue date: 2011<br>This thesis is a reflection on the making o Brazilian History writings in museums since the 1920s, a central moment for the establishment of a republican 'pedagogy of nationality' based on museal support. Some of the political-pedagogic efforts of those institutions were observed in order to understand the chief characteristics of an educational paradigm for historical knowledge in museums. Thus, the analysis of civic celebrations, guides and expositions allowed an approximation of the memorial activations of museum actors, with special attention to the continuities, negotiations and transformations o the projects, particularly in their pedagogic dimension. Mariano Procópio Museum was chosen as a case study both due to its specificities, which leads us to understand the 'concert' of national museums from the countryside, and to the relevance of its collection and the intensity of educational actions developed under the Geralda Armond management (1944-1980). The Armond management in the center of this thesis, marked by the defense of institutional continuity and of the framing of the Lage family memory; by the struggle of the material maintenance of the museum, with a close approximation to the civilian and military regime; and by the search for the professionalization of personnel and for dynamism in actions. The results highlight the multiplicity and fragility of the museum’s identity formation, associated to the fact that it is a 'municipal' museum. A situation which explains, at least in part, its oblivion in the national scene, despite its expressive collection and its articulation with the school system, through the strengthening of the civic sense of its pedagogic actions.<br>Esta tese é uma reflexão sobre a construção de escritas da História do Brasil em museus, a partir da década de 1920, momento fulcral para o estabelecimento de uma 'pedagogia da nacionalidade' republicana, que tem por suporte o discurso museal. Alguns dos esforços político-pedagógicos dessas instituições foram observados, com o objetivo de compreender as principais características de um paradigma educativo para o saber histórico nos museus. Assim, a análise das comemorações cívicas, dos guias de divulgação e das exposições permitiu uma aproximação das ativações memoriais ensejadas pelos atores dos museus, com atenção para as continuidades, as negociações e as transformações dos projetos, especialmente em sua dimensão pedagógica. O Museu Mariano Procópio foi selecionado para a realização de um estudo de caso, tanto por suas especificidades, que nos induzem a pensar o 'concerto' dos museus nacionais a partir do interior do país como pela relevância de seu acervo e pela intensidade de ações educativas desenvolvidas na gestão de Geralda Armond (1944-1980). A gestão Armond é o foco da tese, sendo marcada pela defesa da continuidade institucional e do enquadramento da memória da família Lage; pela luta pela sustentação material do Museu, inclusive com uma forte aproximação com o regime civil e militar; e pela busca da profissionalização de quadros e do dinamismo das ações. Os resultados atentam para a multiplicidade e fragilidade na construção identitária do Museu, associada ao fato de ser um museu 'municipal'. Uma situação que explica, ao menos em parte, seu esquecimento no cenário nacional a despeito de seu acervo expressivo e das articulações encetadas com o sistema escolar, por meio do fortalecimento do sentido cívico de suas ações pedagógicas.