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1
Freitag, Melina. "Inner-outer iterative methods for eigenvalue problems : convergence and preconditioning". Thesis, University of Bath, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512248.
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Many methods for computing eigenvalues of a large sparse matrix involve shift-invert transformations which require the solution of a shifted linear system at each step. This thesis deals with shift-invert iterative techniques for solving eigenvalue problems where the arising linear systems are solved inexactly using a second iterative technique. This approach leads to an inner-outer type algorithm. We provide convergence results for the outer iterative eigenvalue computation as well as techniques for efficient inner solves. In particular eigenvalue computations using inexact inverse iteration, the Jacobi-Davidson method without subspace expansion and the shift-invert Arnoldi method as a subspace method are investigated in detail. A general convergence result for inexact inverse iteration for the non-Hermitian generalised eigenvalue problem is given, using only minimal assumptions. This convergence result is obtained in two different ways; on the one hand, we use an equivalence result between inexact inverse iteration applied to the generalised eigenproblem and modified Newton's method; on the other hand, a splitting method is used which generalises the idea of orthogonal decomposition. Both approaches also include an analysis for the convergence theory of a version of inexact Jacobi-Davidson method, where equivalences between Newton's method, inverse iteration and the Jacobi-Davidson method are exploited. To improve the efficiency of the inner iterative solves we introduce a new tuning strategy which can be applied to any standard preconditioner. We give a detailed analysis on this new preconditioning idea and show how the number of iterations for the inner iterative method and hence the total number of iterations can be reduced significantly by the application of this tuning strategy. The analysis of the tuned preconditioner is carried out for both Hermitian and non-Hermitian eigenproblems. We show how the preconditioner can be implemented efficiently and illustrate its performance using various numerical examples. An equivalence result between the preconditioned simplified Jacobi-Davidson method and inexact inverse iteration with the tuned preconditioner is given. Finally, we discuss the shift-invert Arnoldi method both in the standard and restarted fashion. First, existing relaxation strategies for the outer iterative solves are extended to implicitly restarted Arnoldi's method. Second, we apply the idea of tuning the preconditioner to the inner iterative solve. As for inexact inverse iteration the tuned preconditioner for inexact Arnoldi's method is shown to provide significant savings in the number of inner solves. The theory in this thesis is supported by many numerical examples.
2
Pranjal, Pranjal. "Optimal iterative solvers for linear systems with stochastic PDE origins : balanced black-box stopping tests". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/optimal-iterative-solvers-for-linear-systems-with-stochastic-pde-origins-balanced-blackbox-stopping-tests(4fd0d668-3271-4615-9def-07fc9fe2ea9e).html.
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The central theme of this thesis is the design of optimal balanced black-box stopping criteria in iterative solvers of symmetric positive-definite, symmetric indefinite, and nonsymmetric linear systems arising from finite element approximation of stochastic (parametric) partial differential equations. For a given stochastic and spatial approximation, it is known that iteratively solving the corresponding linear(ized) system(s) of equations to too tight algebraic error tolerance results in a wastage of computational resources without decreasing the usually unknown approximation error. In order to stop optimally-by avoiding unnecessary computations and premature stopping-algebraic error and a posteriori approximation error estimate must be balanced at the optimal stopping iteration. Efficient and reliable a posteriori error estimators do exist for close estimation of the approximation error in a finite element setting. But the algebraic error is generally unknown since the exact algebraic solution is not usually available. Obtaining tractable upper and lower bounds on the algebraic error in terms of a readily computable and monotonically decreasing quantity (if any) of the chosen iterative solver is the distinctive feature of the designed optimal balanced stopping strategy. Moreover, this work states the exact constants, that is, there are no user-defined parameters in the optimal balanced stopping tests. Hence, an iterative solver incorporating the optimal balanced stopping methodology that is presented here will be a black-box iterative solver. Typically, employing such a stopping methodology would lead to huge computational savings and in any case would definitely rule out premature stopping. The constants in the devised optimal balanced black-box stopping tests in MINRES solver for solving symmetric positive-definite and symmetric indefinite linear systems can be estimated cheaply on-the- fly. The contribution of this thesis goes one step further for the nonsymmetric case in the sense that it not only provides an optimal balanced black-box stopping test in a memory-expensive Krylov solver like GMRES but it also presents an optimal balanced black-box stopping test in memory-inexpensive Krylov solvers such as BICGSTAB(L), TFQMR etc. Currently, little convergence theory exists for the memory-inexpensive Krylov solvers and hence devising stopping criteria for them is an active field of research. Also, an optimal balanced black-box stopping criterion is proposed for nonlinear (Picard or Newton) iterative method that is used for solving the finite dimensional Navier-Stokes equations. The optimal balanced black-box stopping methodology presented in this thesis can be generalized for any iterative solver of a linear(ized) system arising from numerical approximation of a partial differential equation. The only prerequisites for this purpose are the existence of a cheap and tight a posteriori error estimator for the approximation error along with cheap and tractable bounds on the algebraic error.
3
MASSON, MICHELE. "Etude par spectrometrie raman de films tres minces et d'interfaces". Paris 6, 1988. http://www.theses.fr/1988PA066405.
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Un montage par excitation des plasmons de surface est mis au point pour etudier les interfaces et les couches minces. Cette technique est appliquee a l'etude des films solides deposes par la methode langmuir blodgett et a l'etude de l'interface liquide/solide
4
Bourouga, Brahim. "Etude d'une methode de mesure instationnaire de resistance thermique de contact entre parois cylindriques concentriques minces". Nantes, 1986. http://www.theses.fr/1986NANT2063.
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Developpement d'dune methode de mesure de resistance thermique de contact dans des doubles tubes metalliques minces destines a la fabrication de condenseurs pour des installations nucleaire. La methode, qui fonctionne en regime instationnaire, est basee sur l'analyse de la reponse de l'echantillon a une sollicitation thermique du type echelon temperature
5
Griso, Georges. "Etudes asymptotiques de structures réticulées minces". Paris 6, 1995. http://www.theses.fr/1995PA066338.
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La premiere partie de cette these est consacree a l'etude asymptotique de problemes elliptiques du second ordre, dans une structure reticulee periodique dependant de deux parametres, avec differentes conditions sur la frontiere des trous de la structure. La deuxieme partie de cette these a pour objet l'obtention d'un modele de jonction des poutres et l'application de ce modele a l'etude d'une grue
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Westberg, Daniel. "A sensor fusion method for detection of surface laid land mines". Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10479.
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Landminor är ett stort problem både under och efter krigstid. De metoder som används för att detektera minor har inte ändrats mycket sedan 1940-talet. Forskning med mål att utvärdera olika elektro-optiska sensorer och metoder som skulle kunna användas för att skapa mer effektiv min-detektion genomförs på FOI. Försök som har gjorts med data från bland annat laser-radar och IR-sensorer har gett intressanta resultat.
I det här examensarbetet utvärderades olika fenomen och egenskaper i laser-radar- och IR-data. De testade egenskaperna var intensitet, IR, ytlikhet och höjd.
En metod som segmenterar intressanta objekt och bakgrundsdata utformades och implementerades. Metoden använde sig av expectation-maximization-skattning och ett minimum message length-kriterium. Ett scatter separability-kriterium användes för att bestämma kvalitén på de olika egenskaperna och på den resulterande segmenteringen.
Data insamlad under en mätkampanj av FOI användes för att testa metoden. Resultatet visade bland annat att ytlikhetsmåttet gav en bra segmentering för stora objekt med släta ytor, men var sämre för små objekt med skrovliga ytor. Vid jämförelse med en manuellt skapad mål-mask visade det sig att metoden klarade av att välja ut egenskaper som i många fall gav en godkänd segmentering.
Land mines are a huge problem in conflict time and after. Methods used to detect mines have not changed much since the 1940's. Research aiming to evaluate output from different electro-optical sensors and develop methods for more efficient mine detection is performed at FOI. Early experiments with laser radar sensors show promising results, as do analysis of data from infrared sensors.
In this thesis, an evaluation is made of features found in laser radar- and in infrared -sensor data. The tested features are intensity, infrared, a surfaceness feature extracted from the laser radar data and height above an estimated ground plane.
A method for segmenting interesting objects from background data using theexpectation-maximization algorithm and a minimum message length criterion is designed and implemented. A scatter separability criterion is utilized to determine the quality of the features and the resulting segmentation.
The method is tested on real data from a field trial performed by FOI. The results show that the surfaceness feature supports the segmentation of larger object with smooth surfaces but gives no contribution to small object with irregular surfaces. The method produces a decent result of selecting contributing features for different neighbourhoods of a scene. A comparison with a manually created target mask of the neighbourhood and the segmented components show that in most cases a high percentage separation of mine data and background data is possible.
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Attipou, Kodjo. "Étude des instabilités dans les membranes minces sous chargements thermomécaniques". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0207/document.
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Le plissement est généralement observé dans les structures minces ayant un comportement de type membrane. Ces structures minces ne supportent pas d'effort de flexion et sont donc sollicitées en traction. Dans cette thèse, nous avons développé une technique de réduction de modèle pour la modélisation du plissement des membranes minces. Cette technique, basée sur les séries de Fourier à double échelle, permet de déduire d'un modèle complet de membrane, un modèle réduit capable de prendre en compte les instabilités globales et locales. Les valeurs critiques de charge et longueur d'onde sont déterminées analytiquement puis numériquement. Des exemples numériques nous ont permis de valider le modèle numérique par rapport au modèle analytique. Les modèles numériques étudiés prennent en compte le modèle complet et le modèle réduit de la membrane. Le modèle complet est simulé dans Abaqus et résolu numériquement à l'aide de la méthode de la longueur d'arc et le modèle réduit est implémenté dans Matlab et résolu numériquement à l'aide de la méthode asymptotique numérique. Nous avons étudié le comportement de la membrane sous sollicitation mécanique, thermique et thermo-mécanique. Les résultats obtenus montrent que le modèle réduit est capable de se substituer au modèle complet dans la détermination des contraintes critiques et longueurs d'onde correspondantes. Le gain en temps de calcul obtenu est important, ceci grâce à la très faible densité de maillage requis par le modèle réduit. Le modèle réduit est très sensible aux conditions aux bords de la membrane et requiert d'avoir une longueur d'onde des plis quasiment constante dans la largeur de la membraneWrinkling is an instability phenomenon generally observed in thin structures with membrane's behavior. Those thin structures have no rigidity to flexion and are therefore used in traction. In this thesis, we developed a reduction model's technique for the modeling of wrinkling phenomenon in thin membranes. This technique, based on the double scale Fourier series, allow us to deduce from a full membrane model, a reduced membrane model that is able to take into account the global and local instability of the structure. The critical load and critical wavelength are determined analytically on one side, then numerically on the other side. Numerical exemples are conducted to validate the numerical model towards the analytical one. Numerical models studied take into account both full and reduce membrane models. The full model is simulated in Abaqus and solved numerically using the arc length method and the reduced model is implemented in Matlab and solved numerically using the asymptotic numerical method. We studied the membrane behavior under mechanical, thermal and thermo-mechanical loading. The results obtained show that the full membrane model can be replaced by the reduced one in determining critical loads and corresponding wavelengths. The gain in computation time obtained is important, due to the coarse mesh required by the reduced model. The reduced model is very sensitive to membrane's boundaries conditions and requires to have a quasi constant wavelength along the membrane width
8
ROBERTS, MARK CULMER. "THEORY AND PRACTICE OF THE INTENSITY OF USE METHOD OF MINERAL CONSUMPTION FORECASTING (MINERAL, ECONOMICS)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187962.
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The intensity of use of a mineral is traditionally defined as the consumption (production plus net imports) of the mineral divided by gross national product. It has been proposed that this ratio of raw material input to gross economic output is a predictable function of per capita income and that the relationship is based on economic theory. Though the theory has never been clearly defined, the intensity of use method has been used to make long term forecasts. This dissertation formulates a theoretical model of the consumption of minerals and the resulting intensity of use which is used to test the validity of the traditional intensity of use measure and its forecasting ability. Previous justifications of the intensity of use hypothesis state that changes in technical efficiency, substitution rates among inputs, and demands are explained by per capita income, which, as it grows, produces a regular intensity of use pattern. The model developed in this research shows that the life of the goods in use, foreign trade of raw and final goods, prices, consumer preferences, technical innovations, as well as the above factors fully explain economic use, which is not simply a function of per capita income. The complete model is used to restate the traditional theory of intensity of use and to examine the sensitivity of traditional measures to changes in the explanatory variables which are commonly omitted. The full model demonstrates the parameters that must be examined when making a long term forecast. Regular intensity of use patterns are observed for many minerals in many nations. Setting aside the theoretical questions, the intensity of use method is often used to make long term projections based on these trends in intensity of use as well as the trends in population and gross national product. This dissertation examines the forecasting ability of the traditional intensity of use method and finds that it is not necessarily an improvement over naive consumption time trend forecasts. Furthermore, it is unstable for very long term projections.
9
Bretall, Damien Carl. "Inverse hybrid method for determining explosive loading on plates due to buried mines". College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7814.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
10
Nguyen, Thanh Trung. "Méthode PEEC inductive par élément de facette pour la modélisation des régions conductrices volumiques et minces". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT049/document.
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La méthode PEEC est connue comme une bonne méthode pour la modélisation des interconnexions électriques dans les domaines de l’électronique de puissance et l’électrotechnique. Elle s'applique à une large gamme de dispositifs : circuits imprimés, bus-barres, conducteurs massifs. Elle est particulièrement bien adaptée pour la modélisation de régions conductrices du type filaire. Cependant, elle est requise d’un maillage structuré(discrétisation des géométries en quadrangles) et l’approche est limitée en fréquence (grande épaisseur de peau). Enfin, il semble actuellement difficile d’envisager la modélisation de conducteurs volumiques dans une formulation PEEC standard.Cette thèse développe des formulations intégrales en utilisant des éléments de facette afin d’lever des verrous de la méthode PEEC standard évoqués ci-dessus. Elle constitue de fait une généralisation de la méthode PEEC standard par la prise en compte de maillages non structurés (volumique et surfacique) et la prise en compte de notion de régions minces à faible épaisseur de peau.Les applications visées sont la modélisation de systèmes de conducteurs complexes (des régions non simplement connexes) en prenant en compte des connexions entre des régions (volumique/filaire, surfacique/filaire,volumique/surfacique et surfacique/surfacique)The PEEC method is known as a good method for modeling electrical connections in the domains of powerelectronics and electrical engineering. It applies to a wide range of devices: printed circuits, bus-bars, solidconductors. It is particularly well adapted for modeling the wire type conductive regions. However, it is requireda structured mesh (discretization geometries quadrangles) and this approach is limited in frequency (high skindepth). Finally, it now seems difficult to envisage modeling of the volume conductors in standard PEECformulation.This thesis develops integrals formulations using facet elements to improve the above mentioned limitations ofthe standard PEEC method. It is in fact a generalization of the standard PEEC method by taking into accountunstructured meshes (volume and surface) and taking into account the notion of thin region with a small skindepth.The applications are the modeling of complex systems of conductors (non-simply connected regions) taking intoaccount the connections between regions (volume / wireframe, surface / wired volume / surface and surface /surface)
11
Fenneman, Douglas. "An acoustic method for the detection of surface waves in sand". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/21802.
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Body, Christophe. "Modélisation des couches minces magnétostrictives [Texte imprimé] : application aux microsystèmes". Grenoble INPG, 1996. http://www.theses.fr/1996INPG0049.
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Le développement actuel des micro actionneurs est tributaire de la disponibilité et du perfectionnement des matériaux dits intelligents tels que, par exemple, les matériaux magnétostriction. Ceux-ci assurent une conversion directe de l'énergie électromagnétique en énergie mécanique. Dans cette optique, la mise au point récente de matériaux magnétostriction en couches minces ouvre de nouveaux champs d'applications et de fonctionnalités pour les microsystèmes. Ces matériaux sont caractérisés par un fort couplage, non linéaire, entre les phénomènes magnétiques et mécaniques. La compréhension du phénomène de magnétostriction en couche mince est une étape primordiale. Le présent travail consiste en l'étude de ce phénomène du point de vue de la modélisation par éléments finis. En effet, le développement des microsystèmes passe impérativement par la mise au point d'outils de modélisation et de conception tenant compte de la réduction d'échelle, de la spécificité des matériaux et des couplages physiques mis en jeu qui rendent la tâche difficile. A partir de la méthode des éléments finis, des techniques originales de couplage fort (couplage simultané) magnétodynamique, non linéaires, sont développées pour modéliser de tels matériaux. Ces techniques sont ensuite appliquées à la modélisation de deux prototypes basés sur le bilame magnétostrictif : une micro membrane active pour micro pompe et une micro poutre encastrée, en tenant compte du circuit de création du champ et des non linéarités magnétiques et mécaniques. Les résultats obtenus soulignent les atouts de la magnétostriction dans le domaine des micro actionneurs, ainsi que la pertinence des méthodes de modélisation développées pour leur conception
13
Zhang, Yigong. "ACTIVE CURRENT INJECTION METHOD FOR LIMITING GROUND FAULT CURRENT HARMONICS IN UNDERGROUND COAL MINES". UKnowledge, 2014. http://uknowledge.uky.edu/mng_etds/15.
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Current practice in U.S. underground coal mine high-voltage distribution systems is to attempt to limit ground fault current to 25 Amperes and de-energize the circuit at 10 Amperes. However, the significant amount of system capacitance due to the use of shielded cables can cause ground fault current to be two or three times the intended ground fault limit. Consequently, this practice can cause several issues such as ground fault currents significantly exceeding the neutral grounding resistor current limit, loss of relay selectivity in the distribution system, and transient overvoltages in certain ground fault situations. These issues are solved to some extent by using a resonance grounded system, currently used in some other countries. However, a shortcoming of traditional resonance grounded systems is the inability to deal with the harmonic components existing in ground fault current. With the increasing use of nonlinear sources such as variable frequency drives, the proportion of harmonic components in ground fault current can be significant. Consequently, although the fundamental component can be almost fully compensated in a traditional resonance grounded system, the harmonic components can still be large enough to maintain arcing and cause personal injury and equipment damage. In this dissertation, a novel method is developed to perform real-time prediction of the harmonics in ground fault currents. Methods for neutralizing the ground fault current harmonics and identifying ground fault location are also developed. Results indicate that the combination of traditional high-resistance grounding and active current injection to neutralize harmonics in the ground fault has the potential to significantly reduce the total ground fault current and reduce arc and flash hazards during ground faults in high voltage distribution systems.
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Fredriksson, Anna. "Mätvärdesbaserad metod för minskade emissioner i mindre förbränningsanläggningar". Thesis, Linnéuniversitetet, Institutionen för byggd miljö och energiteknik (BET), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-45943.
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En mätvärdesbaserad metod har använts för att i den enskilda förbränningsanläggningen kunna visa vilka driftsätt som ger onormalt höga utsläpp. Tre olika typer av anläggningsdata har använts. Metoden fokuserar på gasfasreaktioner för att hållas oberoende av eldningsteknik. För att hålla nere beräkningstider och datorkapacitet fokuserar arbetet på summareaktioner och enkla samband vad gäller kemiska processer och förhållanden i eldstaden.
15
Schröder, Christoph T. "On the interaction of elastic waves with buried land mines : an investigation using the finite-difference time-domain method". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/13928.
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Souag, Nadjia. "Influence de certains types de defauts sur la tenue dielectrique aux temps courts des couches minces de polymeres". Toulouse 3, 1987. http://www.theses.fr/1987TOU30138.
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Caracterisation de la tenue dielectrique des couches minces, sur des echantillons mim autocicatrisants. Methode statistique permettant le calcul des parametres de claquage. Resultats obtenus avec un film de silicone et un film polytetrafluorethylene
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ROGER, JEAN-PAUL. "Contributions a l'etude des surfaces, interfaces et films minces par la methode mirage". Paris 6, 1988. http://www.theses.fr/1988PA066509.
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Detection in situ d'un depot metallique sur une electrode rugueuse avec une sensibilite d'une fraction de couche monoatomique; analyse et modelisation des effets de rugosite pour des surfaces metalliques, caracterisation optique et thermique de couches minces semiconductrices et mise en evidence d'une absorption de surface
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Julisson, Sarah. "Optimisation de formes de coques minces pour des géométries complexes". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV106/document.
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Au cours des processus de conception,l’optimisation de formes apporte aux industriels dessolutions pour l’amélioration des performances desproduits. En particulier, les structures minces quiconstituent environ 70% d’un véhicule, sont une préoccupationdans l’industrie automobile. La plupartdes méthodes d’optimisation pour ces structures surfaciquesprésentent certaines limites et nécessitent desexpertises à chaque niveau de la procédure d’optimisation.L’objectif de cette thèse est de proposer une nouvellestratégie d’optimisation de formes pour les coquesminces. L’approche présentée consiste à exploiter leséquations de coques du modèle de Koiter en se basantsur une analyse isogéométrique. Cette méthode permetde réaliser des simulations sur la géométrie exacteen définissant la forme à l’aide de patchs CAO. Lesvariables d’optimisation choisies sont alors les pointsde contrôle permettant de piloter leur forme. La définitiondes patchs permet également de dégager ungradient de forme pour l’optimisation à l’aide d’uneméthode adjointe.Cette méthode a été appliquée pour des critères mécaniquesissus des bureaux d’études Renault. Des résultatsd’optimisation pour un critère de compliance sontprésentés. La définition et l’implémentation de critèresvibro-acoustiques sont discutés à la fin de cette thèse.Les résultats obtenus témoignent de l’intérêt de la méthode.Toutefois, de nombreux développements serontnécessaires avant d’être en mesure de l’appliquer dansl’industrieDuring the design process, optimizationof shapes offers manufacturers solutions for improvingproducts performances. In particular, thin shellstructures that represent about 70 % of a vehicle, area concern in the automotive industry. Most optimizationmethods for surface structures have limitationsand require expertise at every level of the optimizationprocedure.The aim of this thesis is to propose a new strategyfor the shape optimization of thin shell structures.The approach presented rely on using the Koiter’sshell model based on an isogeometric analysis. Thismethod allows for simulations on the exact geometryby defining the shape using CAD patches. Selectedoptimization variables are the control points used tocontrol the shape of the CAD patches. Variations ofthese points allows to scan a wide design space withfew parameters. The definition of patchs also enablesto find a gradient with respect to the shape for theoptimization by using the adjoint state method.This method was applied to mechanical criteria fromthe Renault design offices. Optimization results for acompliance criterion are presented. The definition andimplementation of vibro-acoustic criteria are discussedat the end of this thesis. The results demonstratethe interest of the method. However, many developmentswill be needed before being able to apply it inthe industry
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Sun, Zhouming. "Reliability-based method for stability of mine entry design and evaluation". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1575.
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Thesis (Ph. D.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 162 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 156-161).
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Kostecki, Todd. "DESIGN METHODS FOR ROCK BOLTS USING IN-SITU MEASUREMENT FROM UNDERGROUND COAL MINES". OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1695.
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The research in this dissertation was undertaken because of a need for a more accurate, reliable and relatively simple method for determining the combined loading (i.e., axial, flexure and shear) along rock bolts. This combined load determination and understanding also resulted in a relatively simple and reliable new rock bolt design methodology. The new design method was based on a clearer understanding of the actual loading along a grouted rock bolt. To accomplish these research goals, double shear tests were conducted in the lab with reinforced concrete specimens, and field trials were conducted in room and pillar coal mines, with the aim to measure in-situ rock shear. Strain measurements were obtained using rock bolts instrumented with optical fibers that possessed high spatial resolution (≈ 1.25 – 2.5 mm). Corroboration with a past database of rock bolt measurements in shale aided in the deduction of the final support design method. The scientific contributions from this research include the conceptualization of a ground reaction curve that considers time effects such as rock relaxation, long term weakening effects, and lateral rock movement. A new explanation as to why rock bolts creep in practice (i.e., dislocation creep) is described based upon field measurements, which also indicated that the process of in-situ rock shear involves slow episodic movements. Specifically, there are localized compression (i.e., rock pinch) and tensile zones (i.e., dilatation) prior to the occurrence of plastic relief (i.e., rock slip). Finally, the design method is developed using simple factors (i.e., strain and shape factors) and loading conditions (e.g., installed load, rock slip) that occurred throughout the rock bolt’s design life. This approach results in a methodology that considers effects on reinforcement with time and combined loadings. The method is then extended by producing survival and hazard functions for rock bolts to ultimately reduce risk associated with design.
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Moulin, Stéphane. "Contribution à l'étude des mécanismes de nucléation et de croissance des couches minces de diamant par mesures in-situ". Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10018.
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Des mesures optiques in-situ de reflectivite, diffusion elastique, et spectroscopie de reflectivite differentielle, ont permis d'etudier les mecanismes de nucleation et de croissance des couches minces de diamant. L'elaboration des echantillons a ete effectuee par depot chimique en phase vapeur assiste par filament chaud, a partir d'un melange de methane et d'hydrogene. La diffusion elastique de la lumiere a ete reliee a la rugosite de surface de l'echantillon. Elle donne alors acces a la taille des cristaux de diamant. Leurs cinetiques de croissance peuvent ainsi etre etudiees. On observe en particulier, que la croissance ne debute qu'apres que les noyaux aient atteint un rayon critique (30-40 nm) en dessous duquel ils sont instables. Au dela, le rayon des cristaux evolue comme la racine carree du temps de depot, jusqu'a environ 60 nm. Ensuite, il evolue lineairement avec le temps. Les mesures optiques spectroscopiques de reflectivite differentielle sont tres sensibles a des modifications d'absorption et de rugosite de surface. Elles ont permis de reveler la formation de graphite polycristallin pendant la periode de nucleation du diamant. Une competition entre le depot de graphite et sa gravure par l'hydrogene atomique a pu etre observee. L'influence de la temperature du substrat a ete etudiee de 700 a 950c. On peut deduire de cette etude que la formation de graphite favorise la nucleation du diamant tant que le depot de graphite est limite par sa gravure (de 700 a 800c). Quand la gravure n'est plus suffisante (au dessus de 900c), la croissance du graphite inhibe la nucleation du diamant. On observe ainsi que la densite de nucleation est maximale vers 800c
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Bouillaud, Pascal. "Irradiation aux ions lourds de films minces nanocristallins d'alliages FeCo et FeAl". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37612171v.
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Luxbacher, Kramer Davis. "Time-lapse Passive Seismic Velocity Tomography of Longwall Coal Mines: A Comparison of Methods". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29018.
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Time-lapse passive seismic velocity tomography was conducted utilizing data from three underground longwall coal mines to produce a better understanding of the processes that lead to ground failure in mines, especially large, violent failures, such as bumps. Two of the datasets, US Western I and US Western II, were collected at bump-prone underground longwall coal mines in the Western United States using surface mounted receiver arrays, while the third data set was collected at an underground longwall coal mine in Australia utilizing an underground array. The Australian mine was experiencing problems with periodic caving and subsequent wind blasts, rather than bumps.
Seismic velocity tomography allows for non-invasive imaging of a rock mass and inference of stress redistribution from the velocity images. These tomograms are unique as they are generated using source data that was collected remotely and the sources are mining-induced. Tomograms were generated using three inversion methods: simultaneous iterative reconstructive technique (SIRT), double difference least squares event relocation, and least squares event relocation. The three methods were compared and contrasted to determine if one is superior and if event relocation improves the image. Also, the tomograms were analyzed to determine if passive seismic velocity tomography is an appropriate technology for the study of stress in mines and assistance in forecasting of bumps. The tomograms were compared with known roof events, face advance, and fall locations at the mines to establish if expected stress features can be imaged with velocity. Finally, synthetic tomograms were generated using a starting velocity model that approximates the predicted â trueâ model for each mine to determine if the velocity images produced correlate with the theoretical stress state at the mine.
Results indicate that high velocity zones correlating with high stress abutment regions can be imaged for the US Western I data set with all three inversion methods, but the SIRT method provided the best agreement when the synthetic tomogram was generated. Additionally, a low velocity zone that correlates with the gob is consistently imaged. These features also redistribute with face advance.
The US Western II data set was not as densely sampled as the US Western I data set. A low velocity region was consistently present in the gob area and redistributed with face advance, but abutment stress features were not evident. Additionally an unexplained high velocity feature was evident on several of the tomograms. Synthetic tomography indicated that the double difference least squares event relocation method is most appropriate for this data set.
Finally, the Moonee Colliery results, which were also not as densely sampled as US Western I were uncertain. While velocity anomalies were often present in the vicinity of a fall, the anomalies were not reliably high or low. Again, synthetic tomography indicated that the double difference damped least squares event relocation method was most appropriate for this data set.
The tomograms presented indicate that source-receiver configuration and density and variable gridding are extremely important in the application of passive seismic velocity tomography to mines. The source-receiver configuration and density determine how well various areas of a model are constrained, and the variable gridding allows areas that are not well sampled to still be adequately constrained.
As a result of this work several things can be drawn about requirements that must be met in order to utilize seismic velocity tomography for inference of stress in underground mines. First, typical longwall stress abutment patterns can be inferred from velocity images of underground coal mines. Second, synthetic tomography and analysis of this tomography, in addition to some knowledge of the general location and frequency of microseismic events, is necessary prior to designing receiver arrays for passive seismic velocity tomography. Suboptimal source-receiver configurations may be used for passive seismic velocity tomography, but there is a minimum threshold for the number of raypaths that must be met that is unique to each site. Finally, a good understanding of the mechanics of stress and failure at the site is necessary to interpret the tomograms.Ph. D.
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Phillips, Kent Thomas. "Applications of Thermal and Laser-Based Methods for Monitoring Airborne Particulates in Coal Mines". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79386.
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The purpose of this thesis is to examine applications of thermal and laser-based methods to monitor airborne particulates in underground coal mines. Specifically, coal and mixed mineral mine dust, as well as, diesel particulate matter (DPM). These particulates have historically, and continue to have, significant health impacts on underground miners. Chapters 1 and 2 of this thesis concentrate on using a novel method of thermogravimetric analysis (TGA) to characterize respirable coal and mixed mineral mine dust and presents the results of this method being applied to samples collected in Appalachia coal mines. Appalachia has been a geographic "hotspot" for the rise in occupational lung disease amongst underground coal miners, which began in 1990's after decades of steady decline. This has led researchers to propose there could be something unique about the respirable dust composition in Appalachia coal mines, which resulted in the surge of lung disease cases; however, the knowledge base regarding the actual composition of respirable coal mine dust is limited. The results of this thesis show that most of the mass fraction of respirable Appalachia coal mine dust is not coal, but rather carbonates and non-carbonate minerals (i.e. silica and silicates). These findings are significant as many researchers now suspect silica and silicates to be the true culprit in the occupational lung disease of coal miners.
DPM presents an additional occupational health hazard to underground coal miners where diesel equipment is used and is difficult to monitor due to its complex nature. In underground metal/non-metal mines, airborne DPM is regulated and monitored using carbon surrogates. However, due to the potential interference from coal-sourced carbon, DPM in coal mines is monitored only by taking samples at the tailpipe of each piece of equipment. This thesis aims to investigate the potential for a laser-based instrument, the FLIR Airtec, to be used in underground coal mines. In particular, what effect the coal dust will have on the instrument, as it measures DPM by way of elemental carbon (EC). The results of this study show that while the Airtec will not over-estimate coal-sourced EC, there could be some sampling artifacts associated with its operation in coal mines, which may inhibit its effectiveness.Master of Science
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Peplow, Dan. "The influence of mine waste contamination on invertebrates and fish in the Methow River Valley, Okanogan County, Washington (U.S.A.) /". Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/5519.
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Altamirano-Soto, Pablo, Jorge Supa-Urrutia, Humbero Pehovaz-Alvarez, Carlos Raymundo, Nestor Mamani-Macedo i Francisco Dominguez. "Filling Method Implementing Hydraulic Lime for Reusing Mine Tailings and Improve Sustainability in Conventional Peruvian Underground Mines". Springer, 2020. http://hdl.handle.net/10757/656169.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.Mining in Peru has existed for several decades, and for several years, there has been no proper environmental management of the impact of this activity on the environment and society in general, whether it be gas emissions, the presence of acidic water, or the generation of mining tailings. One of the most prominent examples involve mine tailings; these are by-products of mining processing plants and are stored in a dam known as a tailings dam. Like any extraction activity, mining generates large amounts of waste material that could become potential risks to the environment and society. Using hydraulic fills, the mine tailings contained in tailings dams could be reused. These fills seek to decrease the volume of stored tailings to prevent any future dam collapses, as observed in Brazil with the Vale mining company, where its tailings dam collapsed and caused more than 200 deaths.
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Delpire, Norbert. "Contribution à l'automatisation de la procédure de préparation et d'étude en ultra-vide de couches minces d'alliages". Rouen, 1986. http://www.theses.fr/1986ROUES037.
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Description de l'automatisation de la phase de la mise en vide d'un groupe a des pressions de l'ordre de 10**(-9) torr à partir d'un microordinateur et de nombreux circuits d'interface. Extension du projet global d'automatisation pour gérer toutes les phases du processus. Description de l'appareillage de mesures analogique ainsi que son interface avec le microordinateur
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Monsalve, Juan J. "Integrating Laser Scanning with Discrete Element Modeling for Improving Safety in Underground Stone Mines". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90659.
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According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is a predominant failure mechanism in underground limestone mines. This type of instability occurs when the different discontinuity sets intercept with each other forming rock blocks that displace inwards the tunnel as the excavation takes place, posing a great hazard for miners and overall mine planning. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed numerical modeling codes to represent more realistically the behavior of a fractured rock masses. This work presents and implements a methodology that integrates laser scanning technology along with Discrete Element Modeling as tools for characterizing, preventing, and managing structurally controlled instability that may affect large-opening underground mines. The stability of an underground limestone mine that extracts a dipping ore body with a room and pillar (and eventual stoping) mining method is analyzed with this approach. While this methodology is proposed based on a specific case study that does not meet the requirements to be designed with current NIOSH published guidelines, this process proposes a general methodology that can be applied in any mine experiencing similar failure mechanisms, considering site-specific conditions. The aim of this study is to ensure the safety of mine workers and to reduce accidents that arise from ground control issues. The results obtained from this methodology allowed us to generate Probability Density Functions to estimate the probability of rock fall in the excavations. These models were also validated by comparing the numerical model results with those obtained from the laser scans.M.S.
According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is one of the main causes of rock falls in underground limestone mines. This type of instability occurs when the fractures present in the rock mass intercept each other forming rock blocks that displace into the tunnel as the excavation takes place and poses a great hazard for miners. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed simulation softwares such as the Discrete Element Model (DEM) to represent more realistically the behavior of a fractured rock mass under excavation. The aim of this work was to develop and evaluate a methodology that could complement already exisiting design guidelines that may not apply to all kind of underground mines. The presented methodology evaluates rock failure due to presence of discontinuites, through the integration of TLS with DEM and considers site specific conditions. An area of a case study mine was assessed with this methodology, where several laser scans were performed. Information extracted from this laser scans was used to simulate the response of the rock mass under excavation by running Discrete Element Numerical Models. Results from these models allowed us to estimate the probability of rock failure in the analized areas. These, rock block failure probability estimations provide engineers a tool for characterizing, preventing, and managing structurally controlled instability, and ultimately improving workers safety.
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MORICHERE, DOMINIQUE. "Etude des proprietes electrooptiques de couches minces organiques par la methode de la reflexion totale attenuee". Paris 11, 1991. http://www.theses.fr/1991PA112118.
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En vue de realiser des modulateurs electrooptiques a faible tension de commande, a grande bande passante et faible cout, nous avons caracterise differents materiaux organiques deposes en couche mince. La methode de la reflexion totale attenuee (art) est particulierement adaptee pour la determination des constantes optiques (indices, epaisseur) et des coefficients electrooptiques lineaires (effet pockels) et quadratiques (effet kerr). Elle permet, par excitation des modes guidees, de sonder l'echantillon dans son volume. Les valeurs des indices et de l'epaisseur du polymere sont determinees a partir de l'enregistrement de la reflectivite en fonction de l'angle d'incidence du faisceau incident excitant les modes guides. La variation de la reflectivite, sous l'effet d'un champ electrique permet de mesurer les variations induites d'indices et d'epaisseur. Il est alors possible de separer l'effet electrooptique direct de l'effet electromecanique (piezoelectricite, electrostriction). Nous avons caracterise tout d'abord un materiau isotrope centrosymetrique, le poly(phenylmethyl) silane, puis un polymere ferroelectrique, le p(vdcn-vac), deux copolymere et enfin un colorant azoique disperse red 1 (dr1) dopant une matrice de polymethylmethacrylate. L'etude de la molecule de dr1 a montre que l'atr n'est pas seulement un outil de mesure des coefficients electrooptiques mais aussi, un moyen d'analyse des effets produits par l'interaction molecule-lumiere (changement de la configuration cis-trans)
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Molavi, M. A. "A study of potash mining methods related to ground control criteria /". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66262.
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Zelaya-Reyes, Yadira, Luis Arauzo-Gallardo, Guillemo Diaz-Huaina, Carlos Raymundo, Nestor Mamani-Macedo i Javier M. Moguerza. "Mathematical Model of a Drilling Mesh to Reduce Dilution in the Sublevel Stoping Method in Peru’s Underground Mines". Springer, 2020. http://hdl.handle.net/10757/656172.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.This research study focuses on creating a drill pattern for the Condestable mine, which will allow us to assess the percentage of dilution. For these purposes, we used the Pearse formula proposed in 1955, which allowed us to find the burden and later, the spacing that each drill hole should have in the pattern. Once we had collected all the numerical data, we used the JK SimBlast program to design the proposed drill pattern and analyze the damage zones, the tonnage acquired and the existing dilution. According the results obtained, the smaller the hole diameter, the less dilution will be generated when diversifying the wall and ceiling explosives.
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Osborne, Caudill. "A Comparison of the HGM Approach to the RBP Method of Evaluating Reconstructed Streams on Surface Coal Mines". Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/176.
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ABSTRACT
A review of annual monitoring reports for stream restoration projects on surface coal mines in the central Appalachian Mountains found that the criteria used for judging the success of the projects was generally based on visual assessments of habitat structure which were evaluated using the Rapid Bioassessment Protocol (RBP) (Palmer and Hondula, 2014). In recent years the Hydrogeomorphic Approach (HGM), which was originally developed to evaluate wetlands, has been adapted for stream evaluations as well (Summers, et al., 2017). Both of these methods are primarily a means to determine if suitable habitat structure and riparian growth are present to support aquatic life. It is assumed that if habitat structure is suitable then macroinvertebrate and other life will be present. However, each of these two methods place emphasis on different aspects of habitat and riparian structure. The primary purpose of this project is to compare and contrast how effective these two methods are at evaluating reconstructed streams on surface coal mines. A secondary objective is to determine if macroinvertebrate assemblages in reconstructed streams is significantly different from that of reference streams not impacted by mining. Research on benthic community structure downstream of coal mining activities suggests that even after many decades taxa richness and abundance still have not recovered from indirect impacts (Petty, et al., 2010). Information on reconstructed streams directly impacted is lacking. This project evaluates streams that were reconstructed five years prior using the RBP and HGM methods, and compares them to local reference streams that have minimal to no mining impacts. Multiple benthic metrics are also used to evaluate community structure.
REFERENCES
Petty, J. Todd, Jennifer B. Fulton, Michael P. Strager, George T. Merovich Jr., James M. Stiles, and Paul F. Ziemkiewicz. 2010. Lanscape indicators and thresholds of stream ecological impairment in an intensely mined Appalachian watershed. Journal of the North American Benthological Society, 29(4): 1292-1309.
Palmer, Margaret A., and Kelly L. Hondula. 2014. Restoration as mitigation: analysis of stream mitigation for coal mining impacts in southern Appalachia. Environmental Science and Technology 48: 10552-10560.
Summers, Elizabeth A., Chris V. Noble, Jacob F. berkowitz, and Frank J. Spilker. 2017. Operational Draft Regional Guidebook for the Functional Assessment of High-Gradient Headwater Streams and Low-Gradient Perennial Streams in Appalachia. ERDC/EL TR-17-1.
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Jurin, Florian. "Croissance et propriétés de films minces conducteurs par auto-assemblage de polyélectrolytes". Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2072/document.
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L'auto-assemblage de polymères a été étudié afin d'élaborer des films multicouches possédant des propriétés conductrices. Dans un premier temps, l'influence de différents paramètres physico-chimiques (pH , force ionique, nature et charge des ions, concentrations en polymères...) sur la croissance de couche polymères isolants (PSS ou PDDA) / polymères conducteurs ( PEDOT : PSS ou P3HT-R) a été étudiée par des mesures in-situ de réflectométrie laser à angle fixe. La compréhension de ses paramètres a permis de contrôler l'assemblage des matériaux afin d'obtenir des films multicouches aux propriétés souhaitées ( épaisseur, morphologie, conductivité électrique...)les épaisseurs des films obtenus ont été déterminées par ellipsométrie ou profilométrie, la morphologie de la morphologie de la surface de ces films a été observé par MEB et leur conductivité a été mesurée par la méthode de van Pauw. Dans un second temps, des films multicouches polymères / particules composites ont été construits après avoir optimisé les conditions d'élaboration des particules composites Al2-PEDOT : PSSph ou SiO2-P3HT-R).Les films multicouches obtenus présentent des conductivités équivalentes à celles des films à base de polymères mais sont construits avec moins d'étapes d'adsorption. Enfin des couches multicouches à bases de deux polymères conducteurs (P3HT-R et PEDOT:PSS) ont été construits sur substrats souples. Ils présentent la plus haute conductivité mesurée (1,5 S.m-1) et conservent leurs propriétés électriques lorsqu'ils sont soumis à des contraintes mécaniques de flexion , ce qui est prometteur quant à leur utilisation dans le domaine de l'électronique déformableSelf-assembly of polymers has been studied in order to produce multilayer films having conductive properties. First, the influence of various physicochemical parameters (pH, ionic strength, nature and charge of ions, polymer concentrations, etc.) on the growth of insulating polymer (PSS or PDDA) / conductive polymers (PEDOT : PSS or P3HT-R) was studied by in-situ measurements of fixed-angle laser reflectometry. The understanding of its parameters allowed to control the assembly of the materials in order to obtain multilayer films with the desired properties (thickness, morphology, electrical conductivity...) The thicknesses of the films obtained were determined by ellipsometry or profilometry, morphology Of the surface morphology of these films was observed by SEM and their conductivity was measured by the method of van Pauw. Second, polymer multilayer films / composite particles were built after optimizing the conditions for the production of the composite particles Al2-PEDOT: PSSph or SiO2-P3HT-R). The multilayer films obtained have conductivities equivalent to those of Films are based on polymers but are constructed with fewer adsorption steps. Finally, multilayer layers based on two conductive polymers (P3HT-R and PEDOT: PSS) were built on flexible substrates. They have the highest conductivity measured (1.5 Sm-1) and retain their electrical properties when subjected to mechanical bending stresses, which is promising for their use in the field of deformable electronics
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Ftouni, Hossein. "Transport thermique dans des membranes très minces de SiN amorphe". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00995424.
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Afin de comprendre les mécanismes de transport de la chaleur dans des films très minces des matériaux amorphes, nous avons proposé et démontré expérimentalement une nouvelle technique de mesure des propriétés thermiques de membranes très minces. Cette technique consiste à coupler la méthode 3 oméga avec la géométrie Völklein (membrane suspendue allongée). L'échantillon d'intérêt est alors monté dans un pont de Wheatstone spécifique afin d'éliminer le signal électrique 1 oméga. Cette technique permet de mesurer avec une très haute sensibilité le signal thermique 3 oméga et donc les propriétés thermiques des membranes. Le nitrure de silicium étudié dans ce travail constitue un matériau amorphe typique. Nous avons été intéressés par l'étude du transport thermique dans un tel système de dimensions réduites en fonction de la température et du stress intrinsèque qui présente dans les films. Afin d'atteindre cet objectif, les membranes de nitrure de silicium de stress élevé et de faible niveau de stress ont été mesurées respectivement pour une épaisseur de 50 nm et 100 nm. Le comportement global de la conductivité thermique mesurée est une croissance quand la température augmente, une tendance généralement constaté pour un matériau amorphe. Le data de membrane de 50 nm présente une conductivité thermique inférieure à celle du 100 nm, ce qui est en accord avec l'effet des dimensions réduites. La chaleur spécifique mesurée s'écarte sensiblement de la loi en T3 de Debye. Cela est particulièrement important en dessous de 100 K où la chaleur spécifique est plus élevé que celle prévue par la modèle Debye. Ces résultats expérimentaux sont en excellent accord avec les prévisions d'un model théorique qui tient en compte de l'effet TLS (Two Level System) qui présente dans le matériaux amorphe. Il a été montré expérimentalement que le stress n'a pas d'effet sur la chaleur spécifique de nitrure de silicium. De plus, nous avons démontré que le stress n'affecte pas la dissipation dans nitrure de silicium, et la dissipation par dilution semble être la cause de la réduction de la dissipation. Par conséquent, le stress ne devrait pas affecter la conductivité thermique du nitrure de silicium, ce qui est cohérent avec les résultats expérimentaux. En terme d'application de la méthode 3 oméga-Völklein, nous avons démontré que la membrane de SiN peut être utilisée comme capteur thermique spécifique pour caractériser un autre matériau déposée sur la face arrière de la membrane. Nous avons testé ce modèle pour mesurer les propriétés thermiques d'un film de 200 nm de Bi2Te3. Les résultats obtenus sont en excellent accord avec la littérature. Comme le SiN est un matériau isolant, ce modèle est capable de mesurer des films très minces quelle que soit sa nature, isolant, semi conducteur ou métallique.
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Barrezueta-Delgado, Erika, Naysha Blas-Trujillo, Yaneth Vasquez-Olivera, Carlos Raymundo, Nestor Mamani-Macedo i Javier M. Moguerza. "A Cyanide Tailings Management Method Using Pseudomonas Fluorescens to Improve Conventional Treatments for Progressive Closure at Small Gold Mines". Springer, 2020. http://hdl.handle.net/10757/656170.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.Based on the review of different research studies, we could assess that, due to their unique biological features, microbes, specifically bacteria, could be used to repair damaged soils with heavy metal and toxic compound contents. Furthermore, these microorganisms are metabolically capable to oxidize cyanide and its by-products to generate less-toxic compounds at the end of the process. This research proposal seeks to improve conventional mine closure designs, thus counteracting their negative short-term, medium-term, and long-term after-effects to the environment. The proposed technique as a solution, therefore, is microbial remediation, using pseudomonas fluorescens bacteria to oxidize this compound to non-toxic components. It will ensure operational continuity for the deposits and, in turn, the sustainability of the entire mining industry.
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Puspitosari, Nastiti. "Density of states measurements on semiconductor and thin film materials using photocurrent methods". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS018/document.
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Les recherches sur les matériaux en couches minces dédiées à l'industrie solaire restent un sujet d'intérêt avec le nombre croissant de types de matériaux incorporés en tant qu'absorbeur dans un dispositif solaire. Le besoin de techniques de caractérisation est donc aigu pour l'optimisation des matériaux et leur incorporation dans des cellules photovoltaïques. Dans cette thèse, une méthode de photo-courant basée sur la spectroscopie de photo-courant à transformée de Fourier (FTPS) est utilisée pour effectuer des mesures sur des matériaux en couches minces et des cellules solaires. Notre FTPS a été développée pour réaliser 3 types de mesures: 1.) mesure de réflexion et de transmission (R/T), 2.) spectroscopie du coefficient d'absorption, et 3.) mesure de réponse spectrale, efficacité quantique externe et densité de photo-courant court-circuit. Cette dernière est spécifiquement utilisée pour les cellules solaires. Nous avons utilisé les résultats de R/T pour effectuer une simulation numérique donnant l'épaisseur, l'indice de réfraction, la rugosité du film et le coefficient d'absorption optique. Une modélisation de la densité d'états (DOS) en utilisant le logiciel DeOSt automatisé avec l'algorithme TLBO (Teacher Learner Based Optimization) a été développée pour trouver les valeurs des paramètres de DOS les mieux adaptées afin de reproduire le ∝ expérimental. Une analyse de sensibilité a été faite pour trouver les paramètres DOS les plus importants parmi 15-17 paramètres. Nous avons mesuré plusieurs échantillons de a-Si: H déposés sous différentes conditions de dépôt, et utilisé nos résultats pour étudier leur DOS. Une comparaison des mesures de α sur a-Si: H déposé sur un substrat de verre et incorporé dans une cellule solaire a également été réalisée. Cette étude a conclu qu'une correction du spectre de coefficient d'absorption doit être effectuée pour les mesures sur les cellules solairesInvestigations on thin film materials dedicated to the solar industry are still a matter of interest with the growing numbers of material types incorporated as absorbers in a solar cell device. The need of characterization techniques is therefore acute for the optimization of materials and their incorporation in solar devices. In this thesis, a photocurrent method based on Fourier Transform Photocurrent Spectroscopy (FTPS) is used to perform the measurements of thin film materials and solar cells. Our FTPS was further developed to perform 3 types of measurements: 1.) reflection and transmission (R/T) measurement, 2.) absorption coefficient spectroscopy and 3.) spectral response, external quantum efficiency, and short circuit photocurrent density measurements. This latter is specifically used for solar cells. We used the R/T results to perform numerical simulations giving the thickness, refractive index, film roughness, and optical absorption coefficient. A modeling of the density of states (DOS) using the software DeOSt automated with the Teacher Learner Based Optimization (TLBO) algorithm was achieved to find the best suited DOS parameter values to reproduce the experimental spectrum of alpha. A sensitivity analysis was performed to find the most important DOS parameters among 15-17 parameters. For the experimental studies, we have measured several a-Si:H thin film samples prepared under different deposition conditions, and used their absorption coefficient; spectra to study their DOS. A comparison of absorption coefficient; measurements on a-Si:H thin films deposited on a glass substrate and incorporated in a solar cell device stack was also conducted. This study concluded that a correction of the absorption coefficient spectrum measured on solar cells had to be done
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Wootton, Robert James Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Investigation into the feasibility and application of composite materials in conveyor support structures for use in underground coal mines". Awarded by:University of New South Wales. Mechanical & Manufacturing Engineering, 2009. http://handle.unsw.edu.au/1959.4/43697.
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Composite materials are well-renown for their strength to weight ratios and are widely used in many industries where high strength and low weight is required. Although steel is the traditional material of choice in the mining industry, and particularly for conveyor support structures, the strength and weight advantages offered by composite materials has prompted this investigation into the feasibility of using composite materials in underground mining conveyor support structures. The first phase of the project centred on establishing and applying selection criteria for the materials and processes which could be used in such a structure. Key concerns include fire performance, electrical conductivity, cost, availability and manufacturability. Based on these considerations, the project identified a phenolic-glass laminate manufactured using the RTM method (for moulded components) or the pultrusion process (for tube sections) as a possible basis for a composite conveyor support structure. The second phase of the project developed a set of design criteria for the use of composite materials in conveyor support structures and a series of preliminary designs based on current conveyor configurations. After analysing each preliminary design against key design criteria, in particular cost, weight, assembly time, susceptibility to damage and torsional loading, the Linestand Suspended - Beam configuration was selected as the preferred option. The third phase of the project used the findings of the preliminary design analysis and the key design criteria to develop a prototype final design. The prototype design is based on a hybrid style of frame. The majority of the structure is constructed from a custom pultruded beam connected with a composite connection piece, while the interface between the rollers and the frame utilises a steel bracket to reduce the risk of damage to the composite frame. The final design is 12kg lighter than the current smaller steel design of similar function. The project has demonstrated the feasibility of using composite materials in conveyor support structures and the weight savings that may be achieved.
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Tang, Xiaochao. "Numerical modeling of deformations caused by carbon dioxide sequestration in coal seams". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4809.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains viii, 83 p. : ill. (some col.), maps (part col.). Vita. Includes abstract. Includes bibliographical references (p. 74-78).
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Le, Duc Tung. "Développement de méthodes intégrales de volume en électromagnétisme basse fréquence. Prise en compte des matériaux magnétiques et des régions minces conductrices dans la méthode PEEC". Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENT052/document.
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Cette thèse concerne l'étude des dispositifs d'électronique de puissance du point de vue de la modélisation. Ces derniers sont souvent constitués de conducteurs ayant des dimensions géométriques très hétérogènes (plaque à épaisseur faible devant la largeur et/ou la longueur par exemple) dont la modélisation est difficile. Les méthodes d'interactions proches, comme celle des éléments finis, sont mal adaptés car elle nécessite la discrétisation de la région air (maillage). Pour cette raison, les travaux ont été orientés vers l'utilisation et le développement des méthodes intégrales : méthode PEEC, méthode des moments magnétiques, méthode intégrale de volume, ces dernières étant particulièrement bien adaptées au calcul des interactions à distance... Les applications visées sont la modélisation de systèmes de conducteurs complexes associés à des masses ferromagnétiques (noyaux inductances par exemple) et à des blindages (carcasses d'armoires électriques par exemple). Ce type de structure se retrouve largement dans le domaine de l'électronique de puissance. Plusieurs formulations intégrales ont été proposées permettant la prise en compte des régions volumiques magnétiques et des régions minces conductrices et/ou magnétiques au sein de la méthode PEECThis thesis concerns the study of power electronic device modelling. These devices are often composed of conductors with heterogeneous geometric dimensions (plate where the thickness is much smaller than its width and / or length, for example) whose modelling is difficult. Because of the inadequacy of finis methods (finite element method, finite volume method) with these structures, the work has been directed to the integral method (PEEC method, magnetic moment method). This work consists in the introduction of magnetic and conductive regions in the PEEC method. Target applications are the modeling of complex conductors systems associated with ferromagnetic masses (e.g., core inductors) and shielding (casings of electrical cabinets, for example). This type of structure is widely found in the field of power electronics. In order to provide a complet modeling tools, many types of regions were processed: volume regions, thin regions and conductive and/or magnetic regions, with any skin thickness. Although not all types of regions have been treated and coupled with PEEC method, a lot of formulations have been implemented
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Love, David. "Mine water geochemistry and management : two case studies and a new treatment method". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51829.
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Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Mine water, that is all forms of water associated with and affected by mining operations is probably the largest area of concern in the environmental geology of mining. This study looks at the inter-relationship between mine water geochemistry and mine water management. The objectives of this study are: 1. To examine major geochemical processes influencing mine water; 2. To apply new national water and environmental legislation to the mining industry and discover how mine water management will be regulated; 3. To examine the approach of Integrated Catchment Management, and discover how this approach can be applied to the mining industry; 4. To conduct two case studies, where environmental geochemistry, general geochemistry and multivariate analyses are used as tools to investigate groundwater contamination problems in mining areas, and therefore suggest mine water management interventions; and 5. To, considering mine water problems discovered in the case studies, develop a newly-patented chemical treatment method for possible application in the mining industry. The changing legal framework - principally the implementation of the National Water Act (Act No 36 of 1998) and the National Environmental Management Act (Act No 107 of 1998) - is leading to the responsibilities of a mine becoming substantially clearer, and responsibilities which in the past could have been ignored until public outcry will now be difficult to escape. Two case studies are investigated. In both cases, general geochemistry and hydrogeochemistry, coupled with factor analysis are used to determine the major signatures in groundwater chemistry and the major sources of contamination. On the basis of this, management interventions are suggested. In the first case study, Sishen Iron Ore Mine of the Northern Cape, three signatures are identified in the groundwater: a clean dolomitic water signature, and a contamination signature from the mine and one from agriculture. The extent of nitrate and diesel contamination is shown to be related to agriculture, the use of explosives and to mine workshops and depots. Surface water controls may help reduce these problems. In the second case study, West Driefontein Gold Mine of the Far West Rand, two signatures are identified in the groundwater: a clean dolomitic water signature and a signature relating to contamination from the mine. Cluster analysis is used to suggest three groundwater zones, the chemistry of one being fairly clean dolomitic aquifer, the chemistry of the second affected by the mine and the chemistry of the third affected by granites. Contamination is shown to be related to mining operations, especially the slimes dams, and agriculture. Rehabilitation of dams and dumps, as well as surface water controls may help reduce these problems. Considering mine water problems discovered in the case studies, a newly-patented chemical treatment method is examined and tested for possible application in the mining industry. It is shown to be extremely effective for the removal of calcium from water, but less effective for the removal of iron and manganese. More broadly, this study shows the inter-dependence between mine water geochemistry and mine water management, and the need to be multi-disciplinary in approach.
AFRIKAANSE OPSOMMING: Mynwater, dit is aile soorte water wat geaffekteer en geassosieer word met mynbou bedrywighede, is moontlik die grootste rede tot kommer in omgewingsgeologie van mynbou. Hierdie studie stel ondersoek in na die verhouding tussen mynwater geochemie en mynwater bestuur. Die doelwitte van die studie is soos volg: 1. Om die hoof geochemiese prosesse te ondersoek wat mynwater beinvloed: 2. Om die nuwe nasionale water- en omgewingswette toe te pas op die mynboubedryf en te ondersoek hoe die bestuur van mynwater gereguleer sal word; 3. Om die benadering van Gerntegreerde Opvangs Bestuur ("Integrated Catchment Managemement") te ondersoek, en te ondersoek hoe hierdie benadering op die mynbou industrie toegepas kan word' 4. Om twee gevallestudies te doen, waar omgewingsgeochemie, algemene geochemie en multivariant analise gebruik word as middels om grondwater besoedeling in mynbougebiede te ondersoek, en daarvolgens om mynwater bestuurswysigings voor te stel; en 5. Om, nemende in ag die mynwater probleme wat ontdek is in die gevallestudies, 'n nuutgepatenteerde chemiese behandelingsmetode, vir moontlike toepassing in die mynbou industrie, te ontwikkel. Die veranderende regtelike raamwerk - hoofsaaklik die implementering van die Nasionale Waterwet (Wet No. 36 van 1998) en die Nasionale Omgewingsbestuur Wet (Wet No.1 07 van 1998) - lei daartoe dat 'n myn verantwoordelik moet wees om opmerklik skoner te word, verantwoordelikhede wat in die verlede maklik gergnoreer kon word maar wat nou te moeilik is om te ignoreer as gevolg van publieke uitroepe. Twee gevalle is ondersoek. In be ide studies word algemene geochemie en hidrogechemie, saam met faktoranalise, gebruik om die hoof kenmerke te bepaal in grondwaterchemie en die hoof bronne van besoedeling. Deur dit as basis te gebruik word bestuurswysigings voorgestel. In die eerste gevallestudie, Sishen Ystererts Myn in die Noordkaap, is drie kenmerkende samestellings qeidentitiseer in die grondwater: 'n skoon dolomitiese samestelling, en een elk van 'n myn en landbou gekontamineerde samestelling. Die omvang van nitraat en diesel kontaminasie word aangedui as geassosieerd met landbou, die gebruik van plofstowwe, mynwerkswinkels en depots. Oppervlak waterbeheer mag help om hierdie probleme te beheer. In die tweede gevallestudie, Wes Driefontein Goudmyn in die Ver Wesrand, is twee kenmerkende samestellings in die grondwater gerdentifiseer: 'n skoon dolomitiese samestelling en 'n samestelling geassosieer met kontaminasie van die myn. "Cluster" analise is gebruik om drie grondwatersones te identifiseer, die eerste een se chemie stem redelik ooreen met 'n skoon akwifer, die tweede een se chemie is bernvloed deur die myn en die derde se chernie is deur granite bemvloed. Kontaminasie word aangedui as geassosieer met mynboubedrywighede, veral die slikdamme, en landbou. Rehabilitasie van damme en afvalhope, asook oppervlak waterbeheer mag help om die probleem te verminder. Deur die mynwater probleme wat in die gevallestudies ontdek is in ag te neem, word 'n nuutgepatenteerde chemiese behandeling ondersoek en getoets vir moontlike toepassing in die mynboubedryf. Dit word aangewys as uiters effektief vir die verwydering van kalsium, maar minder effektief in die verwydering van yster en mangaan. In die algemeen, wys hierdie studie inter-afhanklikheid tussen mynwater geochemie en mynwater bestuur, en 'n behoefte aan 'n rnultidissiplinere benadering.
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Leroy, Annie. "Une methode generale de calcul des systemes portants et/ou propulsifs minces (fluide parfait incompressible en ecoulement instationnaire)". Orléans, 1997. http://www.theses.fr/1997ORLE2018.
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Ce travail de recherche s'inscrit dans le cadre de l'etude d'ecoulements tridimensionnels instationnaires de fluide parfait incompressible autour de systemes aerodynamiques deformables, en mouvement arbitraire, de type aile, pale d'helicoptere, helice. . . La prise en compte de l'emission et de l'evolution de la nappe tourbillonnaire representant le sillage libre est importante dans la mise au point d'une methode destinee a l'etude de tels ecoulements. Pour aborder ce probleme, certaines methodes traitent le sillage a l'aide d'une distribution surfacique d'anneaux tourbillonnaires, d'autres a l'aide d'un modele de particules tourbillonnaires. Ces methodes reposent davantage sur un raisonnement a priori numerique que sur des fondements theoriques precis. En rejoignant le concept de particules tourbillonnaires pour le sillage, nous etablissons une formulation theorique complete de ce probleme en utilisant la theorie des sillages instationnaires de mudry. La nappe tourbillonnaire est consideree comme une couche mediane, caracterisee par une parametrisation mobile, decrivant sa geometrie et sa cinematique, et une densite tourbillonnaire associee decrivant son intensite. Ces deux fonctions fondent le concept de particules tourbillonnaires. Les equations gouvernant le probleme sont issues de l'application de la condition de glissement sur la surface portante, d'une formulation explicite de la condition de joukowsky en son bord de fuite et de la condition de liberte des particules tourbillonnaires du sillage. La numerisation des equations permet de realiser un code de calcul. Le fait qu'il soit le resultat d'une analyse theorique rigoureuse permet d'obtenir des performances interessantes du point de vue numerique et couts de calcul. Il predit les efforts aerodynamiques s'exercant sur le systeme et permet de suivre l'evolution geometrique du sillage. Nous presentons en particulier un cas de calcul complexe d'ailes battantes deformables.
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Basson, Gysbert. "An explicit finite difference method for analyzing hazardous rock mass". Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17957.
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Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: FLAC3D is a three-dimensional explicit nite difference program for solving a variety of solid mechanics problems, both linear and non-linear. The development of the algorithm and its initial implementation were performed by Itasca Consulting Group Inc. The main idea of the algorithm is to discritise the domain of interest into a Lagrangian grid where each cell represents an element of the material. Each cell can then deform according to a prescribed stress/strain law together with the equations of motion. An in-depth study of the algorithm was performed and implemented in Java. During the implementation, it was observed that the type of boundary conditions typically used has a major in uence on the accuracy of the results, especially when boundaries are close to regions with large stress variations, such as in mining excavations. To improve the accuracy of the algorithm, a new type of boundary condition was developed where the FLAC3D domain is embedded in a linear elastic material, named the Boundary Node Shell (BNS). Using the BNS shows a signi cant improvement in results close to excavations. The FLAC algorithm is also quite amendable to paralellization and a multi-threaded version that makes use of multiple Central Processing Unit (CPU) cores was developed to optimize the speed of the algorithm. The nal outcome is new non-commercial Java source code (JFLAC) which includes the Boundary Node Shell (BNS) and shared memory parallelism over and above the basic FLAC3D algorithm.
AFRIKAANSE OPSOMMING: FLAC3D is 'n eksplisiete eindige verskil program wat 'n verskeidenheid liniêre en nieliniêre soliede meganika probleme kan oplos. Die oorspronklike algoritme en die implimentasies daarvan was deur Itasca Consulting Group Inc. toegepas. Die hoo dee van die algoritme is om 'n gebied te diskritiseer deur gebruik te maak van 'n Lagrangese rooster, waar elke sel van die rooster 'n element van die rooster materiaal beskryf. Elke sel kan dan vervorm volgens 'n sekere spannings/vervormings wet. 'n Indiepte ondersoek van die algoritme was uitgevoer en in Java geïmplimenteer. Tydens die implementering was dit waargeneem dat die grense van die rooster 'n groot invloed het op die akkuraatheid van die resultate. Dit het veral voorgekom in areas waar stress konsentrasies hoog is, gewoonlik naby areas waar myn uitgrawings gemaak is. Dit het die ontwikkelling van 'n nuwe tipe rand kondisie tot gevolg gehad, sodat die akkuraatheid van die resultate kon verbeter. Die nuwe rand kondisie, genaamd die Grens Node Omhulsel (GNO), aanvaar dat die gebied omring is deur 'n elastiese materiaal, wat veroorsaak dat die grense van die gebied 'n elastiese reaksie het op die stress binne die gebied. Die GNO het 'n aansienlike verbetering in die resultate getoon, veral in areas naby myn uitgrawings. Daar was ook waargeneem dat die FLAC algoritme parralleliseerbaar is en het gelei tot die implentering van 'n multi-SVE weergawe van die sagteware om die spoed van die algoritme te optimeer. Die nale uitkomste is 'n nuwe nie-kommersiële Java weergawe van die algoritme (JFLAC), wat die implimentering van die nuwe GNO randwaardekondisie insluit, asook toelaat vir die gebruik van multi- Sentrale Verwerkings Eenheid (SVE) as 'n verbetering op die basiese FLAC3D algoritme.
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Sjöström, Jenny, i Marie Wilhelmsson. "Säkrare utveckling och användning av kalkylark inom mindre och medelstora företag : en metod". Thesis, Högskolan i Borås, Institutionen Handels- och IT-högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-18612.
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Kalkylapplikationer används frekvent av företag för bearbetning avfinansiell information. Denna uppsats inriktar sig på Excel, som är denvanligast förekommande kalkylapplikationen. Vår undersökning visade attExcel betraktas som ett mycket bra och flexibelt verktyg och attapplikationens kalkylark är av stor betydelse för företagens verksamhet.Kalkylerna används främst inom finansiella processer för bland annatsammanställning av årsredovisningar, budgetering och kalkylering, vilketgör att många av de här kalkylerna är signifikanta för verksamheten. För attuppfylla företagsspecifika behov tenderar kalkylerna också att varaegenutvecklade inom företagen. Då kalkylerna är egenutvecklade samtidigtsom de är signifikanta ställs höga krav på både utvecklare och slutanvändare.Studier har visat att nästintill alla kalkyler innehåller fel och att behovet avintern kontroll inte tas på fullt allvar. Orsaker till det här är attmedvetenheten om de fel och risker som finns kring Excel-kalkyler ärbegränsad samtidigt som det i stor utsträckning är accepterat att felförekommer i dem till skillnad från andra applikationer. Trots att flertaletExcel-kalkyler är signifikanta för verksamheten brister den internakontrollen och få beaktar de risker och fel som är förknippade med dem. Iuppsatsen identifieras de fel som kan förekomma vid utveckling ochanvändning av Excel-kalkyler. Möjligheten att stävja de här riskerna ochfelen är små utan en fungerade kontrollstruktur och väl fungerande rutiner.Syftet med vår uppsats var att utveckla en metod för hur mindre ochmedelstora företag själva kan implementera en intern kontrollstruktur för ensäkrare utveckling och användning av Excel-kalkyler. Uppsatsen utgår frånett hermeneutiskt synsätt och har en kvalitativ ansats. Undersökningenbaseras på fyra intervjuer som tillsammans med den teoretiska referensramenutgjort grund för den föreslagna metoden. Utifrån det här har vi identifieratfem kritiska områden: dokumentation, kalkyldesign, testning, säkerhet ochkompetens, vilka den föreslagna metoden baseras på. De här kritiskaområdena omfattar i sin tur förebyggande och upptäckande kontroller, vilkadelats in i olika nivåer och utgör enkla till mer avancerade åtgärder försäkerställande av Excel-kalkyler. Metoden inriktar sig främst på signifikantakalkyler och utgör en vägledning för hur mindre och medelstora företag kanuppnå en säkrare utveckling och användning av Excel-kalkyler.Uppsatsnivå: D
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Loomis, Ian Morton. "Application of water mist to fuel-rich fires in model coal mine entries". Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01102009-063037/.
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Pan, Guocheng. "Concepts and methods of multivariate information synthesis for mineral resources estimation". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184946.
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This study introduces a new methodology referred to as geoinformation synthesis for multivariate evaluation of mineral resources and integration of diverse geoscience data. The most critical component is the development of the notion of intrinsic samples and the methods for their delineation. Intrinsic samples replace grid cells which are conventionally employed as the basic information reference. Grid cell sampling has imposed several serious limitations on the geoscience and genetic information that can be objectively related to mineral endowment. Methods based upon intrinsic samples moderate to a certain extent these problems and bring the critical genetic information into the geoscience information system which forms the basis for the quantitative evaluation of mineral resources. The second major component in this new methodology is the integration of factors describing exploration effects with other geodata and mineral endowment estimation; this combination effectively reduces the possibilities of biases in the estimates of mineral endowment and recoverable resources due to the incomplete knowledge on the control area and imperfect analogy with the study areas. The third component is the use in the qualitative models of synthesized geoinformation, which is considerably enhanced, instead of using directly the original measurements (geodata). Several multivariate techniques are proposed and employed for synthesis of diverse information and estimation of mineral endowment, including a priori weighted multivariate criterion, optimum discretization, coherency analysis, multidimensional scaling method (p(ijk), filtering analysis, and geochemical transportation models. These methods were developed, tested, and demonstrated on an actual case study of the epithermal gold-silver deposits in the Walker Lake quadrangle of Nevada and California using various data sets available for this region: geochemical, structural, gravity and magnetic, lithology, and alteration. Finally, the estimation of endowment in terms of epithermal gold-silver mineral occurrences is given for some selected intrinsic samples or information zones identified in the Walker Lake region.
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Jan, Yannick. "Modélisation de la propagation de fissure sur des structures minces, soumises à des sollicitations intenses et rapides, par la méthode X-FEM". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI066/document.
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Actuellement, les méthodes classiques (éléments finis, endommagement, critère de rupture) pour analyser la tenue des structures sous des chargements extrêmes sont très dépendantes de la taille de maille du modèle et nécessitent à la fois un savoir-faire spé- cifique dans le domaine et des études de sensibilité au maillage. De nouvelles approches basées sur la méthode des éléments finis étendus permettent de traiter des propagations de fissure sur des structures de petites tailles et volumiques. Cependant, la propagation sur de grandes longueurs avec des modèles volumiques demande une puissance de calcul importante, souvent inaccessible dans le cadre industriel. Cette thèse a pour but de cou- pler des éléments finis de coque avec la méthode des éléments finis étendue (X-FEM). On peut ainsi diminuer la taille des modèles et gagner en temps de calcul. La fissure peut éga- lement évoluer librement dans le maillage. Après avoir fait le choix d’un élément fini de coque simple et de bonne qualité, l’objectif est de modifier cet élément afin de permettre la description d’une fissure au sein même de celui-ci. Ensuite, l’enjeu est d’adapter les critères de propagation qui existent déjà pour des modèles plans ou volumiques pour les matériaux dits "ductiles" afin de les utiliser dans le cadre d’une modélisation coque. Ces critères sont basés sur l’analyse des champs de contrainte et déformation sur un demi- disque aval à la pointe de fissure. Le calcul de la contrainte équivalente extraite de ces champs servant de seuil pour déclencher ou non la propagation est un point clef de ce travail. Cette étude se place dans le cadre de la plasticité généralisée et fait l’hypothèse d’une fissure initialement traversante dans l’épaisseur de la coque. La phase d’amorçage de la fissure n’est pas prise en compte et le défaut initial est supposé préexistant au sein de la structure. En vue de valider le couplage coque/X-FEM et le critère de propagation, des essais de fissuration sur des structures minces sont réalisés et présentés dans ce documentIn shipbuilding industry, classical methods to analyze the behavior of structures under extreme loadings are very dependent on the size of the mesh. Moreover, propagation over long lengths with volumetric models requires huge processing power, often inaccessible within this framework. In order to manage these issues and due to the geometry to be considered, a coupling between shell finite element and the extended finite element method (X-FEM) using an adapted propagation criterion is proposed. The developments are made in the fast explicit dynamic finite element code EUROPLEXUS, CEA Saclay. For shell structures involving significant thickness such as submarines, Mindlin-Reissner theory is needed to enable shear strain. Therefore, locking-free element are used to avoid the numerical issue of shear-locking that appears when the shell becomes too thin. The fracture of Mindlin-Reissner plates based on the X-FEM discrete approximation framework is studied by Dolbow and Belytschko with the MITC4. A four node shell element using the same formulation is here only enriched with a step function along the crack line to take into consideration the discontinuity of the displacement field across the crack. The calculation remains accurate without the asymptotic enrichment functions near the crack-tip, as long as the mesh is refined near the crack tip. The numerical integration issue for elements cut by the crack is solved by a partitioning strategy developed by Elguedj. Since the crack is contained in the shell for which the mid plane's position is entirely known, only one information left is needed to locate it. Therefore, a crack is represented by several line segments on the three-dimensional mesh. Only through thickness cracks are considered so far. As regards to the crack propagation, a local criteria proposed by Haboussa is used based on the calculation of mechanical equivalent quantities in the vicinity of the crack tip. The maximum of the equivalent stress tensor near the crack tip is used to decide if the crack propagates as well as its propagation direction, and the Kaninen equation gives the crack velocity
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Aguir, Khalifa. "Nouvelle methode de pulverisation reactive : synthese et caracterisation de films minces de ga::(x)as::(1-x) amorphe hydrogene". Toulouse 3, 1987. http://www.theses.fr/1987TOU30174.
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Ce procede de synthese utilise pour la premiere fois fait intervenir simultanement des processus competitifs de depot tels que la pulverisation cathodique de ga et la decomposition de l'arsenic dans une decharge luminescente. La caracterisation optique et electrique du plasma a permis de maitriser la zone transitoire et la composition des depots. La nature amorphe des materiaux synthetises et leur structure ont ete mises en evidence par microdiffraction electronique et diffusion raman. Mise en evidence de l'homogeneite par spectrometrie sims. Pour des depots realises a temperature ambiante, la conductivite et la bande interdite optique varient avec la composition des films. Les films obtenus a des temperatures de support plus elevees ont des comportements optiques et electriques differents
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GOETZBERGER, OLIVIER. "Depot et caracterisation de films minces de silicium sur substrat polymere par la methode cvd assistee par photons lumineux". Université Louis Pasteur (Strasbourg) (1971-2008), 1996. http://www.theses.fr/1996STR13159.
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Le but principal de ce travail a ete d'examiner la possibilite de deposer des films de silicium ainsi que de silice sio2 par la methode appelee photon induced cvd. Notre objectif etait de deposer le silicium et la silice sur un substrat polymere. Nous avons choisi le polyphenilquinoxalin d'une part a cause de sa bonne stabilite thermique jusqu'a des temperatures de l'ordre de 300c et d'autre part pour son caractere non hygroscopique
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EL, GHAZOULI KAMAL HEIZMANN JEAN JULIEN. "NOUVELLES METHODES D'ANALYSE, PAR DIFFRACTION DES RAYONS X, DES VARIATIONS DE TEXTURE DANS LES COUCHES MINCES /". [S.l.] : [s.n.], 1998. ftp://ftp.scd.univ-metz.fr/pub/Theses/1998/El_Ghazouli.Kamal.SMZ9826.pdf.
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Jara, Olivares Angelica Yuliana. "Biocompatible nanostructured multilayer systems". Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT222/document.
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Le domaine des couches minces fait l’objet d’un grand nombre d’études en raison du vaste champ d’applications. La modification de surfaces par des revêtements sous forme de couches minces a ainsi été étudiée dans le domaine biomédical afin d’améliorer les propriétés de bioactivité et biocompatibilité des matériaux. Des couches minces monocouches, Ta et TaN, ainsi que bi-couches, TaN/Ta, ont été déposées sur des substrats de verre, d’acier, SS316LVM, et de titane par pulvérisation cathodique. La caractérisation des couches par diffraction des rayons X (XRD and GIXRD) a montré que la nature du substrat a une forte influence sur la nature de la phase, Ta, formée. La formation de la phase ordonnée, Ta-a, est obtenue sur le substrat acier alors que la phase désordonnée métastable, Ta-b, se forme sur le substrat titane. Quant à la phase TaN, elle cristallise sous la forme cubique de type NaCl (Fm3m) sur les différents substrats mais présente une orientation préférentielle selon le plan (200) dans le cas du substrat verre. L’étude de la composition chimique par XPS a montré que les couches sont également constituées de phases oxydes, telles que TaxOy et TaOxNy, en raison de la forte affinité du tantale avec l’oxygène. Les observations en microscopie électronique à balayage ont mis en évidence une croissance colonnaire des couches avec une microstructure de surface dite de type « chou-fleur ». Cette microstructure est caractéristique du procédé de pulvérisation cathodique et correspond à la microstructure dite de zone I prédite par le modèle de Thornton, dérivé du modèle de Movchan and Demchishin. Des méthodes biomimétiques ont été utilisées afin d’évaluer la bioactivité des couches minces étudiées. Dans ce but, les échantillons ont été immergés dans un fluide biologique (SBF, Simulated Body Fluid) afin de promouvoir le dépôt de phosphate de calcium. Après étude de fluides de compositions différentes, le fluide SBF 1.5, enrichi en ions Ca2 + and PO43-, a été choisi. Les analyses par XRD, FTIR et XPS ont mis en évidence la formation en surface d’une couche cristalline d’hydroxyapatite quelle que soit la nature des sous-couches, Ta, TaN ou TaN/Ta, après immersion de trois semaines. Le mécanisme de dépôt d’hydroxyapatite implique la formation de liaisons Ta-OH par hydratation de la couche passive d’oxyde de tantale présente en surface.Pour étudier les propriétés de biocompatibilité, les échantillons ont été placés en milieux de culture contenant des ostéoblastes. Tous les matériaux observés présentent une adhésion des cellules en surface avec la formation de filipodia. L’un des principaux problèmes des implants osseux est la formation en surface d’un biofilm du à la colonisation de bactéries. Des essais en milieu bactériologique ont donc été réalisés avec des bactéries de type Pseudomonas Aeruginosa, agents pathogènes très fréquemment observés lors d’opérations chirurgicales. Ces essais expérimentaux ont permis de déterminer la réaction des différents matériaux étudiés au contact de ces bactéries. Il s’est avéré que l’adjonction de couches de tantale permet de réduire fortement la formation de bio-films en comparaison avec des couches de titane, qui présentent une croissance importante de bio-films à base de P. aeruginosa.Des films minces de silice ont également été étudiés en tant qu’agents bactéricides. Ces études ont montré l’absence de colonies microbiennes et l’absence de la formation de bio-films en surfaceThin films have been the subject of intense study in materials because they offer multiple applications of great interest. Various surfaces have been modified with thin films or coatings to study how to improve their bioactivity and biocompatibility properties to form a biomaterial. Thin films of Ta, TaN and Ta/TaN were deposited on glass substrates, metallic substrates, SS316LVM and Ti, by RF Sputtering technique. By High angle XRD and GIXRD it was found that the nature of the substrate has a strong influence on the Ta phase formed. Formation of ordered α-Ta phase was obtained on SS316LVM, but the disordered metastable β-Ta phase was formed on Ti and on TaN substrates. While TaN crystallizes in the cubic phase (Fm3m) NaCl type on metallic substrates but shows a preferential orientation in the (200) plane on the glass substrate. The chemical analysis of the surfaces by XPS reveals that in the surfaces of the deposited layers are several oxidized chemical species such as Ta2O5, TaOxNy TaxOy due to Ta is a very reactive metal and is readily oxidized even at low partial pressures as for our synthesis conditions. Characterization by Scanning Electron Microscopy reveals that the microstructure of the films was homogeneous with small clusters size and a cauliflower type, also the films exhibit the typical columnar growth for films deposited by PVD techniques, following the growth of zone I described by the model developed by Movchan and Demchisin and Thornton. Biomimetic method was used to evaluate the bioactivity in all surfaces which involves immersing the thin films in simulated body fluid (SBF) to promote the deposition of calcium phosphates, two concentrations were used to assess qualitatively which could deposit the stoichiometric calcium phosphate hydroxyapatite and make it more efficiently. The SBF 1.5 enriched in Ca2 + and PO43- ions was chosen. A new layer was deposited upon the surfaces and it was determined by XRD, FTIR and XPS that crystalline Hydroxyapatite phase was formed, so that all our surfaces have the ability to form apatite spontaneously after an immersion period of three weeks. The mechanism of deposition of HAp involves the formation of small amounts of Ta-OH groups by a hydration of the tantalum oxide passive layer on its surface. To study biocompatibility properties, films were placed in cell culture containing osteoblasts, all surfaces exhibit cell adhesion and formation of filipodia. Whereas one of the main problems of bone implants is biofilm formation caused by bacterial colonization, tests were made with the bacterium Pseudomonas Aeruginosa, which is a major human opportunistic pathogens in surgical procedures, causing infections in soft tissue, bones, among others. This assay allowed us to know how the different surfaces react when exposed to this bacteria, Titanium had greater growth of P. aeruginosa and biofilm formation in all periods of study, while Ta surfaces showed the lowest activity of biofilm formation. Mesoporous silica thin films where used as bactericidal agents, and it was found by MEB that no microbial colonization or biofilm formation occur on these surfaces