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Witzgall, Zachary F. "Parametric sensitivity analysis of microscrews." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4892.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xi, 73 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-53).
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Sulieman, Hana. "Parametric sensitivity analysis in nonlinear regression." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0004/NQ27858.pdf.
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Gholami, Farnood. "Sensitivity and parametric analyses of multibody mechanical systems." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103734.
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Sensitivity and parametric analyses are powerful tools in assisting engineers to improve design, control and operation of mechanical systems. Sensitivity derivatives help designers to understand the behaviour of the system at hand and modify the design to achieve more satisfactory results. Moreover, these derivatives are beneficial in optimum design, optimal control algorithms, and parameter identification methods. In addition to all these applications, sensitivity derivatives can be used to develop methods for parametric analysis of multibody systems; the formulation of such a method is also described in this thesis. The thesis includes several sections: first, the sensitivity analysis of multibody systems is categorized into two groups: the inverse- and the forward-dynamics based problems. Next, an overview of the literature on different mathematical methods for calculation of the sensitivity derivatives is presented. Then, the dynamics parametric analysis problem is formulated. A parametric analysis method is presented, which relies on the interpretation of a linear space based on sensitivity derivatives. Further to the analysis mentioned above, a parametric analysis toolbox is created in the Simulink environment which complements the Multibody Toolbox (MuT) developed by the Canadian Space Agency. To illustrate the material,two problems are considered to apply the proposed sensitivity and parametric analyses approach on them. First, parametric analysis of contact/impact dynamics for a five-bar linkage is performed. The performance indicator is the pre-impact constrained motion space kinetic energy for contact/impact problems. The performance indicators of these contact/impact systems are related to characterizing the intensity of the contact transition during a change in topology. Second, a combined physical-virtual system is considered and effect of the variation of the inertial parameters of the virtual model on the joint torque variations of such a system is investigated. Simulation and experiments are performed using a setup that contains a physical device and a virtual dynamic system. Experimental results are compared to the simulation results.Les analyses paramétriques et de sensibilités sont des outils puissants qui aide les ingénieurs à améliorer la conception, le contrôle et le fonctionnement des systèmes mécaniques. Les produits dérivés de sensibilité aide les concepteurs à comprendre le comportement du système à portée de main et à modifier la conception à fin obtenir des résultats plus satisfaisants. En outre, ces dérivés sont bénéfiques pour la conception optimale, pour les algorithmes de contrôle optimal ainsi que pour les méthodes d'identification paramétriques. De plus, les produits dérivés de sensibilité peuvent être utilisés à fin de développer des méthodes d'analyse paramétrique des systèmes multicorps; la formulation d'une telle méthode est décrite dans cette thèse. La thèse comprend plusieurs sections: dans la première section, l'analyse de sensibilité des systèmes multicorps sont classés en deux groupes: les problèmes fondés sur la dynamique inverse et ceux fondés sur la dynamique avant. Dans une autre sections, un aperçu de la littérature sur les différentes méthodes mathématiques pour le calcul de sensibilité des dérivés est présentée. Ensuite, l'analyse paramétrique dynamique est formulée. Cette méthode d'analyse s'appuie sur l'interprétation d'un espace linéaire basée sur le produit dérivé de sensibilités. De plus, basée sur cette méthode, une boîte à outils d'analyse paramétrique est créé dans l'environnement Simulink qui complémente la palette d'outils multicorps (Mut) développés par l'Agence spatiale canadienne. Pour démontrer l'applicabilité de l'approche proposées, deux problèmes sont considérés. Tout d'abord, l'analyse paramétrique de contact et d'impact dynamique d'un lien de cinq-barre est effectuée. Pour cet exemple, les indicateurs de performance sont liés a la caractérisation de l'intensité du contact de transition durant un changement de topologie. Dans le second exemple, un système combiné physique-virtuel est considérée et l'effet de la variation des paramètres d'inertie du mode virtuels sur les variations de couples sont investigués. Des simulations et expériences sont effectuée en utilisant une configuration qui contient un dispositif physique et un système dynamique virtuel. Enfin, les résultats expérimentaux sont comparés aux résultats de la simulation.
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Gray, W. Steven. "A geometric approach to the parametric sensitivity of dynamical systems." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/15632.
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Duke, John R. "A Markov model for parametric sensitivity analysis of Crusader effectiveness." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA316985.
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Thesis (M.S. in Operations Research) Naval Postgraduate School, June 1996.Thesis advisor(s): Donald P. Gaver, Patricia A. Jacobs. "June 1996." Includes bibliographical references. Also available online.
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Chua, Hung Soon. "Shape sensitivity of parametric CAD models and strategies for their improvement." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546029.
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Chai, Wenqi. "Global sensitivity analysis on vibro-acoustic composite materials with parametric dependency." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC037/document.
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Avec le développement rapide des modèles mathématiques et des outils de simulation, le besoin des processus de quantification des incertitudes a été bien augmenté. L'incertitude paramétrique et la groupe des nombreux décisions sont aujourd’hui les deux barrières principales dans la résolution des grandes problèmes systématiques.Capable de proportionner l'incertitude de la sortie sur celle des entrées, l’Analyse de Sensibilité Globale (GSA) est une solution fiable pour la quantification de l’incertitude. Parmi plusieurs algorithmes de GSA, Fourier Amplitude Sensitivity Analysis (FAST) est l’un des choix les plus populaires des chercheurs. Basé sur ANOVA-HDMR (ANalysis Of VAriance - High Dimensional Model Representation), il est solide en mathématique est efficace en calcul.Malheureusement, la décomposition unique d’ANOVA-HDMR se dépend sur l’indépendance des entrées. À cause de cela, il y a pas mal de cas industriels qui ne peut pas se traiter par FAST, particulièrement pour ceux qui donnent uniquement les échantillons mais sans lois de distribution. Sous cette demande, deux méthode extensifs de FAST avec design de corrélation sont proposées et étudiées dans la recherche. Parmi les deux méthodes, FAST-c s’est basé sur les distributions et FAST-orig s’est basé sur les échantillons.Comme applications et validations, multiples problèmes vibroacoustiques se sont traités dans la recherche. Les matériaux acoustiques avec soustructures, sont des candidats parfaits pour tester FAST-c et FAST-orig. Deux application sont présentées dans la première partie de la thèse, après l’état de l’arts. Les modèles choisis sont matérial poroélastique et structures composite sandwich, dont les propriétés mécaniques sont tous fortement influencées par les paramètres géométriques microscopique ou mesoscopique. D’avoir la méthode de FAST originale comparée avec les deux nouvelles, on trouve bien plus d’information sur la performance vibroacoustique de ces matériaux.Déjà répondu à la demande de GSA sur les modèles avecs les variables dépendantes, la deuxième partie de la thèse contient plus de recherches reliées avec FAST. D’abord FAST est pris en comparaison avec Random Forest, une algorithme bien connu de data-mining. Leurs erreurs potentiels et la possibilité de fonctioner ensemble sont discutés. Et dans les chapitres suivies, plus d’application de FAST sont présentées. Les méthodes sont appliquées sous plusieurs différente conditions. Une modèle de structure périodique qui contient des corrélation parmi les unités nous a en plus forcé à développer une nouvelle FAST-pe méthode. Dans ces applications, les designs des processus préliminaires et les stratégies d’échantillonages sont des essences à présenterWith rapid development of mathematical models and simulation tools, the need of uncertainty quantification process has grown higher than ever before. Parametric uncertainties and overall decision stacks are nowadays the two main barriers in solving large scale systematic problem.Global Sensitivity Analysis (GSA) is one reliable solution for uncertainty quantification which is capable to assess the uncertainty of model output on its inputs’. Among several GSA algorithms, Fourier Amplitude Sensitivity Test (FAST) is one of the most popular choices of researchers. Based on ANOVA-HDMR (ANalysis Of VAriance - High Dimensional Model Representation), it is both mathematically solid and computationally efficient.One unfortunate fact is that the uniqueness of ANOVA-HDMR relies on the independency of input variables. It makes FAST unable to treat many industrial cases especially for those with only datasets but not distribution functions to be found. To answer the needs, two extended FAST methods with correlation design are proposed and further studied in this research. Among them FAST-c is distribution-based and FAST-orig is data-based.As a frame of validation and application, a number of vibroacoustic problems are dealt with in this research. Vibroacoustic materials with substructures, are perfect test candidates for FAST-c and FAST-orig. Two application cases are presented in the first part of this thesis, following the literature review. The models chosen here are poroelastic material and sandwich composite structures, both having their mechanical properties hugely influenced by their microscopic and mesoscopic geometric parameters. Getting the original FAST method compared to the two with correlation design, many different features on materials’ vibroacoustic performance are latter discovered.Having got an answer for GSA on models with dependent variables, the second part of this thesis contains more extended researches related to FAST. It is taken into comparison with Random Forest, a well-known data-mining algorithm. The potential error of both algorithms are analyzed and the possibility of joint application is discussed. In the following chapters, more applications of FAST-series methods are reported. They are applied under various conditions where another improved version named FAST-pe is developed to treat a model of periodic structures with correlation among each units. Upon these FAST application cases, the design of preliminary process and the sampling strategies is the core part to be introduced
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Zubairi, Mohammad Shaheer. "Using parametric sensitivity analysis to detect design intent in CAD assemblies." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675418.
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The intellectual arrangement of parts in an assembly is a difficult task. Modern CAD environments contain tools which allow CAD part models to be brought together and problems such as clashes to be discovered. Clashes occur when components in an assembly unintentionally violate others. If clashes are not identified and designed out before manufacture, the physical parts will not assemble together without rework. This work introduces a novel approach for eliminating clashes by identifying which parameters defining the part features in a CAD assembly need to change, and by how much, to eliminate the clashes. Consideration is given to the fact that it is sometimes preferable to modify some components in an assembly rather than others, and that some components in an assembly cannot be modified as the designer does not have control over their shape. One of the interesting insights offered by this work is that certain aspects of design intent related to component interfaces in an assembly can be enforced by identifying the faces between the different components, and understanding the effect of parameters which define the model has on them. The work presented in this thesis determines which parameters should be related to one another and, more importantly, how parametric sensitivities are used to: (a) identify parametric relationships between different parameters in the CAD assembly, and (b) constrain the assembly using the identified relationships to define the design intent of the assembly. The developed processes advances the state-of-the-art CAD systems by explicitly determining the relationships between the parameters and eliminating clashes in CAD models. A well-captured design intent for assembly models will enable the designer to design out manufacturing and assembly difficulties at an early product development stage. The approaches have been tested on a number of example models in this thesis.
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Louh, Hsing-Duan. "Parametric Sensitivity in a Model of a Motor Pattern Generator in Aplysia." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case159558630128468.
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Giovannini, Alessandro. "Parametric Sensitivity Analysis of the Most Recent Computational Models of Rabbit Cardiac Pacemaking." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4800/.
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The cellular basis of cardiac pacemaking activity, and specifically the quantitative contributions of particular mechanisms, is still debated. Reliable computational models of sinoatrial nodal (SAN) cells may provide mechanistic insights, but competing models are built from different data sets and with different underlying assumptions. To understand quantitative differences between alternative models, we performed thorough parameter sensitivity analyses of the SAN models of Maltsev & Lakatta (2009) and Severi et al (2012). Model parameters were randomized to generate a population of cell models with different properties, simulations performed with each set of random parameters generated 14 quantitative outputs that characterized cellular activity, and regression methods were used to analyze the population behavior.
Clear differences between the two models were observed at every step of the analysis. Specifically: (1) SR Ca2+ pump activity had a greater effect on SAN cell cycle length (CL) in the Maltsev model; (2) conversely, parameters describing the funny current (If) had a greater effect on CL in the Severi model; (3) changes in rapid delayed rectifier conductance (GKr) had opposite effects on action potential amplitude in the two models; (4) within the population, a greater percentage of model cells failed to exhibit action potentials in the Maltsev model (27%) compared with the Severi model (7%), implying greater robustness in the latter; (5) confirming this initial impression, bifurcation analyses indicated that smaller relative changes in GKr or Na+-K+ pump activity led to failed action potentials in the Maltsev model. Overall, the results suggest experimental tests that can distinguish between models and alternative hypotheses, and the analysis offers strategies for developing anti-arrhythmic pharmaceuticals by predicting their effect on the pacemaking activity.
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Miao, Shicong. "A Parametric Study For Panel Buckling Sensitivity Of Composite Sandwich Wind Turbine Blades." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1323963140.
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Menin, Michel. "Parametric sensitivity study for wind power trading through stochastic reserve and energy market optimization." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257502.
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Trading optimal wind power in energy and regulation market offers possibil-ities for increasing revenues as well as impacting security of the system in apositive way[33]. The bidding in both energy and regulation markets can bedone through stochastic optimization process of both markets.Stochastic optimization can be possible once the probabilistic forecst is avail-able through ensemble forecast methodology. For stochastic optimization, thepost-processing of the ensembles to generate quantiles that will be used in op-timization can be accomplished by employing different methodology. In thisstudy, we will concentrate on the impact of post-processing of ensembles onthe stochastic optimization.Generation of quantiles needed for stochastic optimization used herein formarket optimization will be the main focus of the investigation. The impactof price ratios between energy and reserve market will be also investigated toanalyse the impact of said ratios on the revenues. Furthermore this analysiswill be performed for both US and Swedish markets.
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Zhou, Haochuan. "New Non-Parametric Confidence Interval for the Youden." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/math_theses/56.
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Youden index, a main summary index for the Receiver Operating Characteristic (ROC) curve, is a comprehensive measurement for the effectiveness of a diagnostic test. For a continuous-scale diagnostic test, the optimal cut-point for the positive of disease is the cut-point leading to the maximization of the sum of sensitivity and specificity. Finding the Youden index of the test is equivalent to maximize the sum of sensitivity and specificity for all the possible values of the cut-point. In this thesis, we propose a new non-parametric confidence interval for the Youden index. Extensive simulation studies are conducted to compare the relative performance of the new interval with the existing intervals for the index. Our simulation results indicate that the newly developed non-parametric method performs as well as the existing parametric method but it has better finite sample performance than the existing non-parametric methods. The new method is flexible and easy to implement in practice. A real example is also used to illustrate the application of the proposed interval.
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Kozderka, Michal. "Parametric LCA approaches for efficient design." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAD050/document.
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Ces travaux de recherche portent sur la problématique de la mise en pratique de l'analyse de cycle de vie (ACV). La question principale est : comment faire une ACV plus rapide et plus facilement accessible pour la conception des produits ? Nous nous concentrons sur deux problématiques qui prolongent l'inventaire de Cycle de Vie (ICV) : • recherche des données manquantes : Comment ranger les données manquantes selon leur importance? Comment traiter l'intersection des aspects qualitatifs et les aspects quantitatifs des données manquantes? • Modélisation du cycle de vie : Comment réutiliser le cycle de vie existant pour un nouveau produit? Comment développer un modèle de référence? Pour la recherche des solutions nous avons utilisé l'approche "Case study" selon Robert Yin. Nos contributions font résultat de trois études de cas, dont la plus importante est l'ACV du High Impact Polypropylene (HIPP) recyclé. Nous avons publié les résultats de celle-ci dans la revue scientifique Journal of Cleaner Production. Suite aux études de cas nous proposons deux approches d'amélioration d'efficacité en ICV : nous proposons l'analyse de sensibilité préalable pour classifier les données manquantes selon leur impact sur les résultats d'ACV. L'approche combine les aspects quantitatifs avec les aspects quantitatifs en protégeant le respect des objectives d'étude. Nous appelons cette protection "LCA Poka-Yoké". La modélisation du cycle de vie peut être assistée grace à la méthode basée sur l'algorithme de King. Pour la continuation de la recherche nous proposons huit perspectives, dont six font l'objet d'intégration des nouvelles approches d'amélioration dans les concepts d'ACV basés sur la norme ISO 14025 ou dans le projet de la Commission Européenne PEFThis work addresses the different issues that put a brake to using Lifecycle assessment (LCA) in product design by answering the main question of the research: How to make Lifecycle assessment faster and easier accessible for manufactured product design? In the LCA methodology we have identified two issues to deal with and their consecutive scientific locks : • Research of missing data : How to organize missing data? How to respect quantitative and qualitative dimensions? • Modeling of the lifecycle scenario : How to translate methodological choices into the lifecycle scenario model? How to transform the reference scenario into a new one? We have dealt with these issues using the scientific approach Case study according toRobert Yin. Our contributions are based on three case studies, between which the most important is study of High Impact Polypropylene recycling in the automotive industry. We have published it in the Journal of Cleaner Production. As result of our research we present two methods to improve efficiency of the LifecycleInventory Analysis (LCI) : To organize the missing data: Preliminary sensitivity analysis with LCA Poka-Yoke ; To help with scenario modeling: Method of workflows factorization, based on Reverse engineering. For further research we propose eight perspectives, mostly based on integration of our methods into Product Category Rules (PCR)-based platforms like EPD International or the European PEF
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Zhang, Tianyao. "A study on the heat transfer and energy performance implications of cool roofs." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52977.
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In this study, we examined the effect of cool roofs on commercial and residential buildings in each climate zone, by looking at monitored case studies and DOE-2 simulations from various sources of literature; and using an online tool - the Cool Roof Calculator and a simple COP ratio model to validate the results of the case studies. It was found that the Cool Roof Calculator does not take building form into account, hence a sensitivity analysis was first conducted to rank the importance of various building parameters against one another. The analysis was conducted on the EPC normative building energy model. Results indicated that roof absorptance coefficient, aspect ratio and number of floors were the three parameters that either ranked highest or were important parameters, and were chosen for further parametric analysis to evaluate the impact of these building parameters on total building loads.
A simple COP ratio model was also developed to validate the results from the literature review and Cool Roof Calculator, and it was found that in terms of cost, for a prototype medium-sized commercial building, it is always beneficial to use a white roof, but cities in northern climates may have little advantage, and insulation may be a better
choice.
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Park, Sungho. "Development and Applications of Finite Elements in Time Domain." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/30693.
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A bilinear formulation is used for developing the time finite element method (TFM) to obtain transient responses of both linear, nonlinear, damped and undamped systems. Also the formulation, used in the h-, p- and hp-versions, is extended and found to be readily amenable to multi-degree-of-freedom systems. The resulting linear and nonlinear algebraic equations for the transient response are differentiated to obtain the sensitivity of the response with respect to various design parameters. The present developments were tested on a series of linear and nonlinear examples and were found to yield, when compared with other methods, excellent results for both the transient response and its sensitivity to system parameters. Mostly, the results were obtained using the Legendre polynomials as basis functions, though, in some cases other orthogonal polynomials namely, Hermite, Chebyshev, and integrated Legendre polynomials were also employed (but to no great advantage). A key advantage of TFM, and the one often overlooked in its past applications, is the ease in which the sensitivity of the transient response with respect to various design parameters can be obtained. Since a considerable effort is spent in determining the sensitivity of the response with respect to system parameters in many algorithms for parametric identification, an identification procedure based on the TFM is developed and tested for a number of nonlinear single-and two-degree-of-freedom system problems. An advantage of the TFM is the easy calculation of the sensitivity of the transient response with respect to various design parameters, a key requirement for gradient-based parameter identification schemes. The method is simple, since one obtains the sensitivity of the response to system parameters by differentiating the algebraic equations, not original differential equations. These sensitivities are used in Levenberg-Marquardt iterative direct method to identify parameters for nonlinear single- and two-degree-of-freedom systems. The measured response was simulated by integrating the example nonlinear systems using the given values of the system parameters. To study the influence of the measurement noise on parameter identification, random noise is added to the simulated response. The accuracy and the efficiency of the present method is compared to a previously available approach that employs a multistep method to integrate nonlinear differential equations. It is seen, for the same accuracy, the present approach requires fewer data points. Finally, the TFM for optimal control problems based on Hamiltonian weak formulation is proposed by adopting the p- and hp-versions as a finite element discretization process. The p-version can be used to improve the accuracy of the solution by adding more unknowns to each element without refining the mesh. The usage of hierarchical type of shape functions can lead to a significant saving in computational effort for a given accuracy. A set of Legendre polynomials are chosen as higher order shape functions and applied to two simple minimization problems for optimal control. The proposed formulation provides very accurate results for these problems.Ph. D.
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Moschetti, Lorenzo. "Parametric Sensitivity Study of Shear-Flexure Interaction Modeling for Reinforced Concrete Structural Walls under Cyclic Loading." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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In order to predict the inelastic hysteretic behavior of reinforced concrete (RC) structural walls under lateral cyclic loading, robust and reliable numerical tools are required. The Shear-Flexure-Interaction Multiple-Vertical-Line-Element-Model (SFI-MVLEM) proposed by Kolozvari et al. (2015) incorporates important material characteristics and behavioral response features, therefore it promises excellent capabilities. In reference to the SFI-MVLEM approach, this study investigates the global response (i.e. lateral load versus lateral top displacement) sensitivity to some input parameters, in order to evaluate which input parameters are influential and which ones are not. Seven RC structural wall specimens with a moderate aspect ratio are considered for the parametric sensitivity study. The predicted load-displacement responses are compared with the experimental ones, in order to assess variations in analytical responses. The input parameters here analyzed are the number of SFI-MVLEM elements used for the wall discretization, the concrete tensile strength, the dowel stiffness coefficient for steel reinforcing bars, and the cracks closure mechanism.
The study shows that the number of SFI-MVLEM elements does not affect the predicted global response, while the concrete tensile strength and the dowel stiffness coefficient for steel reinforcing bars affect the simulated global response in terms of both lateral load capacity and energy capacity dissipation. In addition, the study indicates that the assumption of sudden crack closure provides more accurate results in terms of energy capacity dissipation than the assumption of gradual cracks closure.
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Edwards, Tyler A. "A Parametric Study of Stack Performance for a 4.8kW PEM Fuel Cell." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1275667559.
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SANDOVAL, PEDRO EMILIO GALLARDO. "PARAMETRIC SENSITIVITY ANALYSIS CONSIDERING THE LIFE CYCLE OF BASE OILS FOR THE PRODUCTION OF MINERAL AND VEGETABLE LUBRICANTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=31415@1.
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A constante procura por desenvolvimento sustentável tem originado a criação de novas técnicas de avaliação dos custos ambientais nos sistemas de produção. Atualmente a produção de óleos lubrificantes está sendo ambientalmente avaliada devido aos grandes impactos ambientais gerados pela produção, utilização e disposição final dos óleos de base mineral. Como alternativa para os óleos de bases minerais vem-se estudando a substituição por óleos oriundos de bases animais e vegetais, os quais apresentam melhores características ambientais. Este trabalho teve por objetivo realizar uma análise de ciclo de vida simplificada (berço-porta) das fases de produção de 1 kg de óleo de base mineral e 1 kg de óleo de base de óleo de jatropha com a utilização de uma análise de sensibilidade. A comparação para a obtenção dos dados foi realizada nos mesmos cenários de produção tanto para os óleos lubrificantes de base de
jatropha quanto para os óleos lubrificantes de base mineral. Os resultados nestes cenários indicaram que na produção do óleo de jatropha, o potencial de aquecimento global foi 1,01 kg maior do que o cenário base da produção do óleo mineral; o potencial de eutrofização de água foi 2,06E-04 kg maior do que o cenário base da produção do óleo mineral; o potencial de toxicidade humana foi 0,08 kg maior do que o cenário base da produção do óleo mineral e o potencial de depleção de água foi 1,33E-01 kg maior do que o cenário base da produção do óleo mineral. No cenário base da produção do óleo mineral, o potencial de
depleção de combustíveis fósseis foi 0,70 kg maior do que o cenário base da produção do óleo de jatropha. Entretanto, no contexto desta modelagem deve-se ainda levar em consideração outros parâmetros, como os relacionados às limitações geográficas, pois algumas discrepâncias nas análises do ciclo de vida dos óleos podem ocorrer.The continuously effort to reach the sustainable development has led to the creation of new techniques for assess environmental costs of the production systems. Nowadays the production of mineral oil base lubricants is assessed due to the large environmental impacts generated in their production, use and final disposal. As alternatives to the substitution of mineral oil base lubricants, vegetable oil base lubricants have been studied and used because their environmental characteristics. Hence, this study focused on execute a simplified LCA (cradle-to-gate analysis) for the production phase of 1 kg of mineral base oil and 1 kg of jatropha base oil trough a sensitivity analysis. The comparison for both oil bases was performed under the same production scenarios. Results shown that the jatropha base oil production scenario presented 1,01 kg more than the base mineral oil production scenario; the fresh water eutrophication potential had 2,06E-04 kg more than the base mineral oil scenario; the human toxicity potential presented 0,08 kg more than the base mineral oil scenario; the water depletion potential showed 1,33E-01 kg more than the base mineral oil scenario. On the mineral base oil production scenario, the fossil depletion potential shown 0,70 kg more than the base jatropha oil production scenario. However, it had to still take in consideration parameters such as geographic limitations, due to some discrepancies in the life cycle assessment of oils can occur.
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Chesson, Kristin Elaine. "A one-group parametric sensitivity analysis for the graphite isotope ratio method and other related techniques using ORIGEN 2.2." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1944.
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Rashidi, Mehrabadi Niloofar. "Power Electronics Design Methodologies with Parametric and Model-Form Uncertainty Quantification." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82934.
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Modeling and simulation have become fully ingrained into the set of design and development tools that are broadly used in the field of power electronics. To state simply, they represent the fastest and safest way to study a circuit or system, thus aiding in the research, design, diagnosis, and debugging phases of power converter development. Advances in computing technologies have also enabled the ability to conduct reliability and production yield analyses to ensure that the system performance can meet given requirements despite the presence of inevitable manufacturing variability and variations in the operating conditions. However, the trustworthiness of all the model-based design techniques depends entirely on the accuracy of the simulation models used, which, thus far, has not yet been fully considered. Prior to this research, heuristic safety factors were used to compensate for deviation of real system performance from the predictions made using modeling and simulation. This approach resulted invariably in a more conservative design process.
In this research, a modeling and design approach with parametric and model-form uncertainty quantification is formulated to bridge the modeling and simulation accuracy and reliance gaps that have hindered the full exploitation of model-based design techniques. Prior to this research, a few design approaches were developed to account for variability in the design process; these approaches have not shown the capability to be applicable to complex systems. This research, however, demonstrates that the implementation of the proposed modeling approach is able to handle complex power converters and systems. A systematic study for developing a simplified test bed for uncertainty quantification analysis is introduced accordingly. For illustrative purposes, the proposed modeling approach is applied to the switching model of a modular multilevel converter to improve the existing modeling practice and validate the model used in the design of this large-scale power converter.
The proposed modeling and design methodology is also extended to design optimization, where a robust multi-objective design and optimization approach with parametric and model form uncertainty quantification is proposed. A sensitivity index is defined accordingly as a quantitative measure of system design robustness, with regards to manufacturing variability and modeling inaccuracies in the design of systems with multiple performance functions. The optimum design solution is realized by exploring the Pareto Front of the enhanced performance space, where the model-form error associated with each design is used to modify the estimated performance measures. The parametric sensitivity of each design point is also considered to discern between cases and help identify the most parametrically-robust of the Pareto-optimal design solutions.
To demonstrate the benefits of incorporating uncertainty quantification analysis into the design optimization from a more practical standpoint, a Vienna-type rectifier is used as a case study to compare the theoretical analysis with a comprehensive experimental validation. This research shows that the model-form error and sensitivity of each design point can potentially change the performance space and the resultant Pareto Front. As a result, ignoring these main sources of uncertainty in the design will result in incorrect decision-making and the choice of a design that is not an optimum design solution in practice.Ph. D.
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Auer, Zbyněk. "Citlivostní analýza v energetickém hodnocení budov." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265418.
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The master´s thesis was focused on parametric computer simulations of the energy performance of buildings. The aim is to determine the sensitivity of the individual operating and climatic influences on the final energy demand of the building, which will be reflected in final form Et-curve. Parametric simulation for building energy efficiency is planned to use the BSim and ready climatic database for a specific location in place of the assessed building. The outcome of the evaluation of the real use of property in Et-curve using a custom application.
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Labrik, Rachid. "Integration of energy management and production planning : Application to steelmaking industry." Thesis, KTH, Optimeringslära och systemteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141432.
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Steelmaking industry, one of the most electricity-intensive industrial processes, is seeking for new approaches to improve its competitiveness in terms of energy savings by taking advantage of the volatile electricity prices. This fluctuation in the price is mainly caused by the increasing share of renewable energy sources, the liberalization of energy markets and the growing demand of the energy. Therefore, making the production scheduling of steelmaking processes with knowledge about the cost of the energy may lead to significant cost savings in the electricity bills. With this aim in mind, different models are developed in this project in order to improve the existing monolithic models (continuous-time based scheduling) to find an efficient formulation of accounting for electricity consumption and also to expand them with more detailed scheduling of Electric Arc Furnace stage in the production process. The optimization of the energy cost with multiple electricity sources and contracts and the production planning are usually done as stand-alone optimizers due to their complexity, therefore as a new approach in addition to the monolithic model an iterative framework is developed in this work. The idea to integrate the two models in an iterative manner has potential to be useful in the industry due to low effort for reformulation of existing models. The implemented framework uses multiparametric programming together with bilevel programming in order to direct the schedule to find a compromise between the production constraints and goals, and the energy cost. To ensure applicability heuristic approaches are also examined whenever full sized models are not meeting computational performance requirements. The results show that the monolithic model implemented has a considerable advantage in terms of computational time compared to the models in the literature and in some cases, the solution can be obtained in a few minutes instead of hours. In the contrary, the iterative framework shows a bad performance in terms of computational time when dealing with real world instances. For that matter a heuristic approach, which is easy to implement, is investigated based on coordination theory and the results show that it has a potential since it provides solutions close to the optimal solutions in a reasonable amount of time. Multiparametric programming is the main core of the iterative framework developed in this internship and it is not able to give the solutions for real world instances due to computational time limitations. This computational problem is related to the nature of the algorithm behind mixed integer multiparametric programming and its ability to handle the binary variables. Therefore, further work to this project is to develop new approaches to approximate multiparametric technique or develop some heuristics to approximate the mp-MILP solutions.
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BORGES, ANTONIO A. "Combinacao entre os metodos diferencial e da teoria de pertubacao para calculo dos coeficientes de sensibilidade." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9267.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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BORGES, ANTONIO A. "Uma combinação entre os métodos diferencial e da teoria de perturbação para o cálculo dos coeficientes de sensibilidade." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9267.
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Desenvolve-se aqui um novo método para calcular coeficientes de sensibilidade. Este novo método é uma combinação entre as duas metodologias usadas para calcular estes coeficientes, que são o método diferencial e o método da teoria da perturbação generalizada. O método consiste em fazer como parâmetro integral o fluxo médio em uma região arbitrária do sistema. Dessa forma, o coeficiente de sensibilidade passa a conter somente o termo correspondente ao fluxo de nêutrons. Para obtenção do novo coeficiente de sensibilidade é feito o cálculo do coeficiente de sensibilidade desse parâmetro integral com relação a σ através do método de perturbação e são obtidas as derivadas funcionais do parâmetro integral genérico com relação a σ e Φ utilizando o método diferencial.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Schirén, Whokko, and Trixie Swahn. "Vibrations in residential timber floors : A comparison between the current and the revised Eurocode 5." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-89293.
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The European standard Eurocode 5, a design method for timber structures,is currently under revision. In this study the draft for a reviseddesign method for vibrations in timber floors was compared to the currentmethod. The hypothesis of the thesis was that the revised designmethod might force some changes to the present construction practiceand that these changes may carry with them increased costs for the industry.Six common floor structures used in Sweden today were identifiedand for these floors design calculations were made according to the currentand the revised design method. It was checked whether the floorspassed the criteria in the two design methods and a comparison was madefor the only criterion which could be compared between the methods, thepoint load deflection. Floor structures could pass or fail the current designmethod based on two criteria, the point load deflection and the unitimpulse velocity response. All floors passed the current design methodexcept one which had a fundamental frequency below 8 Hz, because ofthe low frequency the current design method was not applicable to thefloor structure. In the revised design method the final result is a responsefactor and based on the response factor floors are given floor performancelevels. The seven step scale for the floor performance level go from I toVII where I is excellent and VII is unacceptable. All floor structures excepttwo achieved an acceptable floor performance level according to therevised design method. The two floors which failed were floors commonlyused in single family houses, they failed for a span length commonly usedtoday. A limited parametric study was performed where it was found thatthe modal mass used had a larger impact on the floor performance levelthan the mass per square meter included. For floors with a fundamentalfrequency above 8 Hz, including a higher mass per square meter resultedin a lower, i.e. better, response factor in all cases except one. For floorswith a fundamental frequency between 4.5 and 8 Hz, a higher mass resultedin a higher, i.e. worse, response factor. The study found that notall floor structures used in Sweden today are acceptable according to therevised design method therefore changes may have to be implemented andthese changes could result in an increased cost.
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Guo, Yichao. "Analytical Study On Compound Planetary Gear Dynamics." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1312289370.
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Jakel, Roland. "Using a Catenary Equation in Parametric Representation for Minimizing Stress Concentrations at Notches." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-172192.
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Der Vortrag beschreibt, wie sich mittels Kettenlinien als Kerbgeometrie der Spannungskonzentrationsfaktor an Querschnittsübergängen auf nahezu 1 reduzieren lässt. Mittels globaler Sensitivitätsstudien in der p-FEM-Software Creo Simulate wird mithilfe eines in Creo Parametric parametrisierten CAD-Modells der Kettenlinie in Parameterdarstellung ein normiertes Kerbzahldiagramm erstellt. Dieses erlaubt die Dimensionierung einer Kerbe, d.h. die Festlegung ihrer exakten Geometrie und der damit verbundenen Kerbzahl αk ohne die weitere Verwendung eines FEM-ProgrammesThe presentation describes how to reduce the stress concentration factor at cross section transitions to nearly 1 by using a catenary curve as notch geometry (catenary fillet). With help of global sensitivity studies performed in the p-FEM-code Creo Simulate, a normalized stress concentration factor diagram is drawn. Therefore, a CAD-model of the catenary curve in parametric representation was developed. The diagram created allows to dimension the notch, that means to determine its exact geometry and stress concentration factor Kt, without further usage of a FEM code
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Seelbinder, David [Verfasser], Christof [Akademischer Betreuer] [Gutachter] Büskens, and Stephan [Gutachter] Theil. "On-board Trajectory Computation for Mars Atmospheric Entry Based on Parametric Sensitivity Analysis of Optimal Control Problems / David Seelbinder ; Gutachter: Christof Büskens, Stephan Theil ; Betreuer: Christof Büskens." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/1141277700/34.
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Akansel, Vesile Hatun. "Fragility Of A Shear Wall Building With Torsional Irregularity." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613542/index.pdf.
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Buildings with torsional irregularity represent the main focus of many
current investigations. However, despite this volume of research, there is no
established framework that describes adequately the seismic vulnerability of
reinforced concrete shear wall systems. In this study, the three-dimensional
behavior of a particular shear-wall structure under earthquake effects was
examined with regard to the nonlinear behavior of the reinforced concrete
assembly and the parameters that characterize the structure exposed to seismic
motion for damage assessment.
A three story reinforced concrete shear-wall building was analyzed using
the finite element method based ANSYS software. The scaled model building was
subjected to shaking table tests at Saclay, France. The project was led by the
Atomic Energy Agency (CEA Saclay, France) under the &ldquoSMART 2008 Project.&rdquo
The investigation was conducted in two phases. In the first phase, the results of the finite element method and experiments were examined, and were reported in this study. For time history analysis, micro-modeling was preferred due to allowing inclusion the nonlinear effects of concrete and steel for analysis. The guiding parameters (acceleration, displacement, strain) of analytical results are compared with the corresponding values that were measured in the experiments to be able to quantify the validity of models and simulation. For the comparison of v the numerical model results with the experimental results FDE (Frequency Domain Error) method was used. After comparison of the numerical model results with the experimental results, the second phase of the SMART 2008 Project was undertaken. The second phase consisted of two parts summarized as &ldquo
Sensitivity Study&rdquo
and &ldquo
Vulnerability Analyses&rdquo
. However, in this report only the sensitivity study and fragility analyses will be reported. Sensitivity study was done to understand which parameters affect the response of the structure. Twelve parametric cases were investigated under two different ground motions. Different behavior parameters were investigated. The effective damping coefficient was found to affect the structural response at 0.2 g design level as well as at 0.6 g over-design level. At the design level, it was observed that elasticity modulus of concrete and additional masses on the specimen determined as effective on the calculated results. To derive the failure probabilities of this structure under various earthquake forces for the given limit states, fragility curves were obtained. Different seismic indicators such as PGA (Peak ground acceleration), PGV (Peak ground velocity), PGD (Peak ground displacement) and CAV (Cumulative absolute velocity) were used as seismic indicators and MISD (Maximum interstory drift) were used as damage indicator for fragility curves. In all 30 time history analyses were done. Regression analyses using least squares method were performed to determine the median capacity and its deviation. Correlation coefficients of the time history data versus fitted curves obtained from the regression analyses changes between 0.65 and 0.99. The lower cases were for PGD- MISD graphs. The scatter of the fragility curves calculated for each damage limit was slightly wider. HAZUS MH MR1 (2003) damage states were also used for the calculation of the fragility curves and compared with the SMART 2008 damage states.
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Di, Chicco Augusto. "Optimization of a calculation scheme through the parametric study of effective nuclear cross sections and application to the estimate of neutronic parameters of the ASTRID fast nuclear reactor." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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This thesis presents the project for the optimization of the APOLLO3® neutronic calculation scheme applied to the 4th generation fast neutron reactor ASTRID. APOLLO3® is the new multipurpose neutronic platform developed by the CEA. It incorporates many of the previous generation codes used in the French reactor core design supply chain. Like all deterministic codes, APOLLO3® solves the neutron transport equation with a discretization of the variables of interest: multi-group method for the energy, discrete ordinates and spherical harmonics for the angular variable, collision probabilities and characteristics methods for the spatial variable. The resolution of the transport equation handles useful quantities such as the neutron flux and multiplication factor, fission rates and cross sections to understand the physical behaviour of the reactor core. Currently it is not possible to use deterministic codes to simulate an entire reactor with a heterogeneous 3D geometry and a fine energy description, so to simplify the study of complete neutron field at core level, the calculation scheme is divided into two phases: lattice and core calculation. The main purpose of this work is to find an optimal degree of approximations of the calculation scheme for the evaluation of a desired physical effect and of the user constraints. In order to reach this optimum, several studies have been carried out with different levels of approximations. The results have been benchmarked with the ones obtained using the stochastic code TRIPOLI4®, used as a reference and to ensure a good accuracy. Furthermore, several sensitivity studies have been carried out to understand how the different approximations affect the macroscopic cross sections evaluation, because these dependences are not yet fully understood.
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Mattos, Wellington da Silva. "Ajuste do modelo matemático de uma aeronave com sistema de aumento de estabilidade com base em ensaios em túnel de vento." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-20092007-171040/.
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O presente trabalho descreve a aplicação de um método de ajuste de modelo, com base em resultados experimentais obtidos em túnel de vento, a uma aeronave com sistema de aumento de estabilidade longitudinal (LSAS). O estudo inclui uma revisão de métodos para ajuste de modelos, o desenvolvimento do modelo matemático da aeronave e uma descrição dos ensaios em túnel de vento da aeronave com o LSAS. O sistema automático de controle é composto de (1) um sistema de aquisição de dados, que processa o sinal do sensor e envia um sinal de comando para o atuador; (2) um potenciômetro, usado como sensor de ângulo de arfagem; e (3) um servo motor, usado como atuador do canard. O modelo de aeronave é baseado no Grumman X-29, que tem asa de enflechamento negativo e canard. Sua margem de estabilidade estática pode ser ajustada mudando a posição do centro de rotação que, por sua vez, coincide com a posição do centro de gravidade da aeronave através de balanceamento do peso. O ajuste do modelo matemático do avião é conduzido, no ambiente Matlab/Simulink, com a modificação dos parâmetros das derivadas de estabilidade da aeronave, do filtro digital e da dinâmica do sensor e do atuador. O objetivo é obter uma correlação ótima entre resultados teóricos e experimentais. O método da análise da sensibilidade paramétrica é escolhido para o ajuste do modelo. Numa primeira fase do estudo, a comparação entre resultados experimentais e numéricos é feita com base nas freqüências e razões de amortecimento da variação do ângulo de arfagem em resposta a uma entrada do tipo impulso de deflexão do canard. Numa segunda fase a comparação é baseada diretamente na resposta no tempo do ângulo de arfagem numérico e experimental para a mesma entrada impulso do canard. Três posições do centro de gravidade são analisadas, uma em que a aeronave é estaticamente estável e duas em que ela é instável. Os resultados mostram grande variação dos parâmetros ajustados indicando a necessidade de aperfeiçoamento na implementação da metodologia utilizada.The present work describes the application of a model updating method, based on experimental wind tunnel data to an aircraft longitudinal stability augmentation system (LSAS). The study includes a revision of model updating methods, the development of the aircraft mathematical model and the description of a previously conducted, aircraft LSAS wind tunnel testing. The LSAS is comprised by (1) a data acquisition system, which processes the sensor signal and sends the control command to the actuator; (2) a potentiometer, used as a pitch angle sensor; and (3) a servo motor, used to actuate canard deflection. The aircraft model is based on the Grumman X-29, which has canard and forward swept wing. Its static stability margin can be adjusted by changing the center of rotation position which, in turn, coincides with the aircraft center of gravity position through weight balance. The airplane mathematical model updating is carried out, in the Matlab/Simulink environment, by adjusting model parameters for aircraft stability derivatives, digital filter, sensor and servo dynamics. The objective is to obtain an optimal correlation between numerical and experimental results. The parametric sensitivity analysis method is chosen for model updating. In a first phase of the study the comparison between theoretical and experimental results is based on frequencies and damping ratios for aircraft pitch angle response to an impulse canard deflection input. In a second phase the comparison is based directly on experimental and numerical pitch angle time response to the same impulse canard deflection input. Three center of gravity positions are analyzed, one for which the aircraft is statically stable and two for which it is unstable. Results show large variations among adjusted parameters indicating the need for improvements in the implementation of the adopted methodology.
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Barrera, Gallegos Noé. "Sensibilité Paramétrique pour l’Analyse Dynamique des Réseaux à Courant Continu." Thesis, Ecole centrale de Lille, 2016. http://www.theses.fr/2016ECLI0021/document.
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Ce travail de thèse a pour finalité de présenter différentes méthodologies pour l’analyse de réseaux à courant continue haut tension (HVDC). La théorie fondamentale de l‘analyse de sensitivité s’applique sur l’analyse des systèmes électriques de puissance dans les différentes étapes de la production et la transmission de l’énergie. Des outils de bases concernant cette théorie sont devenus populaires et très utilisés.En pratique, les facteurs de participation représentent un exemple de ces outils, utilisés depuis longtemps. Ils ont été proposés par (Perez-Arriaga et al., 1982). Le but des facteurs de participation est la réduction des modèles des systèmes ayant une dynamique particulière comme celle des systèmes électromécaniques. Aussi, les facteurs de participation sont utilisés pour comprendre les relations entre les variables d’état et les valeurs propres des systèmes. Nous présentons la théorie fondamentale de la sensitivité analytique dans laquelle les facteurs de participation sont basses. Pour une bonne compréhension de ces éléments de base de cette théorie, quelques exemples sont présentés. Nous présentons une formulation différente pour l’analyse par sensitivité paramétrique (Barrera Gallegos et al., 2016).Enfin, les deux méthodologies sur des exemples des réseaux HVDC. Notre comparaison permet d’exposer les limites de l’utilisation des facteurs de participation sur des réseaux HVDC.En conclusion, la nouvelle méthodologie est plus générale comparée aux facteurs de participation. Egalement, la nouvelle méthodologie, par sensitivité paramétrique, nous donne plus d’informations sur les caractéristiques dynamiques des réseaux HVDCThe work presented in this thesis presents different methodology for parametric sensitivity of high voltage dc networks(HVDC).The fundamental theory of modal analysis has been applied for analysis of the power electrical systems in its different stages of production and transmission of energy. Tools derived from these fundamentals have become popular with its use. Among the tools used in dynamic analysis, participation factors have been used for a long time. Proposed by (Perez-Arriaga et al., 1982), they give a metric for relating states and eigenvalues of a system. The objective of the participation factors is to analyze systems with particular dynamics such as electromechanical systems. The participation factors is a tool that helps in the reduction of systems. Firstly, we present the fundaments of the sensitivity analysis upon which the participation factors are based on. The principle is illustrated with several examples.We propose a new formulation for sensitivity analysis using parametric sensitivity (Barrera Gallegos et al., 2016).In the latter, the application of participation factors and parametric sensitivity analysis is performed using HVDC networks. This comparison exposes the limitation of the participation factors for the general analysis of HVDC grids.In conclusion, the new methodology is a better and general alternative compared to traditional participation factors employed for analysis of HVDC grids. In addition, the new technique of parametric sensitivity produces several novel information related to the dynamic characteristics of the HVDC grid
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Silva, João Eduardo Maeda Moreira da. "Estimação de parâmetros de modelos compartimentais para tomografia por emissão de pósitrons." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-17082010-131206/.
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O presente trabalho possui como metas o estudo, simulação, identificação de parâmetros e comparação estatística de modelos compartimentais utilizados em tomografia por emissão de pósitrons (PET). Para tanto, propõe-se utilizar a metodologia de equações de sensibilidade e o método de Levenberg-Marquardt para a tarefa de estimação de parâmetros característicos das equações diferenciais descritoras dos referidos sistemas. Para comparação entre modelos, foi empregado o critério de informação de Akaike. São consideradas três estruturas compartimentais compostas, respectivamente, por dois compartimentos e duas constantes características, três compartimentos e quatro constantes características e quatro compartimentos e seis constantes características. Os dados considerados neste texto foram sintetizados preocupando-se em reunir as principais características de um exame de tomografia real, tais como tipo e nível de ruído e morfologia de função de excitação do sistema. Para tanto, foram utilizados exames de pacientes do setor de Medicina Nuclear do Instituto do Coração da Faculdade de Medicina da Universidade de São Paulo. Aplicando-se a metodologia proposta em três níveis de ruído (baixo, médio e alto), obteve-se concordância do melhor modelo em graus forte e considerável (com índices de Kappa iguais a 0.95, 0.93 e 0.63, respectivamente). Observou-se que, com elevado nível de ruído e modelos mais complexos (quatro compartimentos), a classificação se deteriora devido ao pequeno número de dados para a decisão. Foram desenvolvidos programas e uma interface gráfica que podem ser utilizadas na investigação, elaboração, simulação e identificação de parâmetros de modelos compartimentais para apoio e análise de diagnósticos clínicos e práticas científicas.This work has as goals the study, simulation, parameter identification and statistical comparison of compartmental models used in positron emission tomography (PET). We propose to use the methodology of sensitivity equations and the method of Levenberg-Marquardt for the task of estimating the characteristic parameters of the differential equations describing such systems. For model comparison, Akaikes information criterion is applied. We have considered three compartmental structures represented, respectively, by two compartments and two characteristic constants, three compartments and four characteristic constants and four compartments and six characteristics constants. The data considered in this work were synthesized taking into account key features of a real tomography exam, such as type and level of noise and morphology of the input function of the system. To this end, we used tests of patients in the sector of Nuclear Medicine of the Heart Institute of the Faculty of Medicine, University of São Paulo. Applying the proposed methodology with three noise levels (low, medium and high), we obtained agreement of the best model with strong and considerable degrees (with Kappa indexes equal to 0.95, 0.93 and 0.63, respectively). It was observed that, with high noise level and more complex models (four compartments), the classification is deteriorated due to lack of data for the decision. Programs have been developed and a graphical interface that can be used in research, development, simulation and parameter identification of compartmental models, supporting analysis of clinical diagnostics and scientific practices.
35
Solís, Maikol. "Conditional covariance estimation for dimension reduction and sensivity analysis." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2354/.
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Cette thèse se concentre autour du problème de l'estimation de matrices de covariance conditionnelles et ses applications, en particulier sur la réduction de dimension et l'analyse de sensibilités. Dans le Chapitre 2 nous plaçons dans un modèle d'observation de type régression en grande dimension pour lequel nous souhaitons utiliser une méthodologie de type régression inverse par tranches. L'utilisation d'un opérateur fonctionnel, nous permettra d'appliquer une décomposition de Taylor autour d'un estimateur préliminaire de la densité jointe. Nous prouverons deux choses : notre estimateur est asymptoticalement normale avec une variance que dépend de la partie linéaire, et cette variance est efficace selon le point de vue de Cramér-Rao. Dans le Chapitre 3, nous étudions l'estimation de matrices de covariance conditionnelle dans un premier temps coordonnée par coordonnée, lesquelles dépendent de la densité jointe inconnue que nous remplacerons par un estimateur à noyaux. Nous trouverons que l'erreur quadratique moyenne de l'estimateur converge à une vitesse paramétrique si la distribution jointe appartient à une classe de fonctions lisses. Sinon, nous aurons une vitesse plus lent en fonction de la régularité de la densité de la densité jointe. Pour l'estimateur de la matrice complète, nous allons appliquer une transformation de régularisation de type "banding". Finalement, dans le Chapitre 4, nous allons utiliser nos résultats pour estimer des indices de Sobol utilisés en analyses de sensibilité. Ces indices mesurent l'influence des entrées par rapport a la sortie dans modèles complexes. L'avantage de notre implémentation est d'estimer les indices de Sobol sans l'utilisation de coûteuses méthodes de type Monte-Carlo. Certaines illustrations sont présentées dans le chapitre pour montrer les capacités de notre estimateurThis thesis will be focused in the estimation of conditional covariance matrices and their applications, in particular, in dimension reduction and sensitivity analyses. In Chapter 2, we are in a context of high-dimensional nonlinear regression. The main objective is to use the sliced inverse regression methodology. Using a functional operator depending on the joint density, we apply a Taylor decomposition around a preliminary estimator. We will prove two things: our estimator is asymptotical normal with variance depending only the linear part, and this variance is efficient from the Cramér-Rao point of view. In the Chapter 3, we study the estimation of conditional covariance matrices, first coordinate-wise where those parameters depend on the unknown joint density which we will replace it by a kernel estimator. We prove that the mean squared error of the nonparametric estimator has a parametric rate of convergence if the joint distribution belongs to some class of smooth functions. Otherwise, we get a slower rate depending on the regularity of the model. For the estimator of the whole matrix estimator, we will apply a regularization of type "banding". Finally, in Chapter 4, we apply our results to estimate the Sobol or sensitivity indices. These indices measure the influence of the inputs with respect to the output in complex models. The advantage of our implementation is that we can estimate the Sobol indices without use computing expensive Monte-Carlo methods. Some illustrations are presented in the chapter showing the capabilities of our estimator
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Oudshoorn, Adrien. "Contribution à l'optimisation des structures mécaniques sous contraintes : l'optimisation de la conception d'avant-projet : application aux structures de véhicules de transport guidés." Valenciennes, 1994. https://ged.uphf.fr/nuxeo/site/esupversions/bf8407f4-a1d8-4b9b-bfa0-bdbd0dd4fafe.
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Le problème de conception d'avant-projet des structures mécaniques complexes soumis au double impératif de qualité et de rapidité est de plus en plus difficile à appréhender. Il offre un terrain très favorable à la synthèse automatique par le biais de l'optimisation mathématique. Fort de ce constat, nous étudions le potentiel d'utilisation de l'optimisation mathématique dans la phase de conception d'avant-projet. Notre étude se décompose en deux étapes: l'élaboration d'un outil informatique adapté et son exploitation dans le contexte de la conception d'avant-projet des structures de véhicules de transport guidés. L’outil informatique proposé s'appuie sur des techniques d'optimisation éprouvées et respecte les exigences de l'optimisation des structures d'avant-projets. Il met en œuvre la méthode des différences finies pour le calcul des sensibilités paramétriques et la méthode à linéarisation convexe de C. Fleury pour l'optimisation proprement dite. Des améliorations sont apportées à cette dernière et une recherche linéaire appropriée est développée. Trois tests simples démontrent le bien fondé des modifications effectuées. L’exploitation de l'outil proposé est conduite à partir de l'optimisation sous contraintes statiques et dynamiques de quatre structures à caractère industriel. Des simulations du processus de conception et de rédaction d'offres incluant des éléments issus de l'optimisation illustrent les résultats obtenus. L’utilisation judicieuse de l'optimisation et l'exploitation fine de ses résultats fournit rapidement au concepteur des réponses fiables à ses interrogations et devrait lui permettre de conduire efficacement les premiers pas de son projet ou encore de produire en temps limite des offres très compétitives
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Meesala, Vamsi Chandra. "Modeling and Analysis of a Cantilever Beam Tip Mass System." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83378.
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We model the nonlinear dynamics of a cantilever beam with tip mass system subjected to different excitation and exploit the nonlinear behavior to perform sensitivity analysis and propose a parameter identification scheme for nonlinear piezoelectric coefficients.
First, the distributed parameter governing equations taking into consideration the nonlinear boundary conditions of a cantilever beam with a tip mass subjected to principal parametric excitation are developed using generalized Hamilton's principle. Using a Galerkin's discretization scheme, the discretized equation for the first mode is developed for simpler representation assuming linear and nonlinear boundary conditions. We solve the distributed parameter and discretized equations separately using the method of multiple scales. We determine that the cantilever beam tip mass system subjected to parametric excitation is highly sensitive to the detuning. Finally, we show that assuming linearized boundary conditions yields the wrong type of bifurcation.
Noting the highly sensitive nature of a cantilever beam with tip mass system subjected to parametric excitation to detuning, we perform sensitivity of the response to small variations in elasticity (stiffness), and the tip mass. The governing equation of the first mode is derived, and the method of multiple scales is used to determine the approximate solution based on the order of the expected variations. We demonstrate that the system can be designed so that small variations in either stiffness or tip mass can alter the type of bifurcation. Notably, we show that the response of a system designed for a supercritical bifurcation can change to yield a subcritical bifurcation with small variations in the parameters. Although such a trend is usually undesired, we argue that it can be used to detect small variations induced by fatigue or small mass depositions in sensing applications.
Finally, we consider a cantilever beam with tip mass and piezoelectric layer and propose a parameter identification scheme that exploits the vibration response to estimate the nonlinear piezoelectric coefficients. We develop the governing equations of a cantilever beam with tip mass and piezoelectric layer by considering an enthalpy that accounts for quadratic and cubic material nonlinearities. We then use the method of multiple scales to determine the approximate solution of the response to direct excitation. We show that approximate solution and amplitude and phase modulation equations obtained from the method of multiple scales analysis can be matched with numerical simulation of the response to estimate the nonlinear piezoelectric coefficients.Master of Science
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Krajčovič, Ján. "Zpětná analýza sypané přehradní hráze a predikce jejího chování při mimořádných zatěžovacích stavech." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391964.
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Diplomová práce představuje vytvoření softwarového 2D MKP modelu přehrady Slezská Harta v České Republice za pomoci softwaru PLAXIS 2D. V úvodu práce je analýza vodní nádrže, vytvořené jako zásobárna vody a protipovodňové dílo. Analýza sleduje geomorfologii, geologii, konstrukci tělesa hráze, použité materiály a metody, a stávající monitorovací zařízení. Pro pochopení tvorby 2D MKP modelu jsou předloženy a definované metody použitých analýz - metoda konečných prvků, analýza prosakování, materiálové modely, citlivostná analýza. Následně byla definována tvorba struktury modelu - určení posloupnosti použitých analýz, definování vstupních dat a mezních podmínek a tvorba kalibračního segmentu. V závěrečné části práce je analýza dosažených výstupů rozsáhlého testování modelu, jejich korelace s reálnými naměřenými hodnotami a celkové shrnutí přínosu vytvořeného modelu pro jeho využití při předpovídání chování přehrady v extrémních případech.
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Akkari, Nissrine. "Etude mathématique de la sensibilité POD (Proper orthogonal decomposition)." Phd thesis, Université de La Rochelle, 2012. http://tel.archives-ouvertes.fr/tel-01066073.
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Dans cette thèse, nous nous sommes intéressés à l'étude mathématique de la sensibilité paramétrique de la méthode de réduction de modèles par projection connue sous le nom de POD pour Proper Orthogonal Decomposition. Dans beaucoup d'applications de la mécanique des fluides,la base de projection (base POD) calculée à un paramètre caractéristique fixe du problème de Navier-Stokes, est utilisée à la suite pour construire des modèles d'ordre réduit ROM-POD pour d'autres valeurs du paramètre caractéristique. Alors, la prédiction du comportement de ce ROM-POD vis-à-vis du problème initial est devenue cruciale. Pour cela, nous avons discuté cette problématique d'un point de vue mathématique. Nous avons établi des résultats mathématiques de sensibilité paramétrique des erreurs induites par application de la méthode ROM-POD. Plus précisément, notre approche est basée sur l'établissement d'estimations a priori de ces erreurs paramétriques, en utilisant les méthodes énergétiques classiques. Nos résultats sont démontrés pour les deux problèmes de type Burgers et Navier-Stokes. Des validations numériques de ces résultats mathématiques ont été faites uniquement pour le problème de type Burgers.
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Susetyo, Budi. "Modélisation de l'impédance harmonique de charges agrégées." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0027.
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Les applications de l’électronique de puissance contribuent à la pollution harmonique des réseaux électriques. Pour estimer le niveau de distorsion de tension, les différents composants du réseau doivent être modélisés en régime harmonique, en particulier les charges consommatrices, industrielles, commerciales et domestiques. L’étude concerne la modélisation de l’impédance harmonique des charges qui peuvent être séparées en deux grandes catégories: les charges passives et les charges dites actives qui réalisent une conversion d’énergie électromécanique. Les modèles disponibles pour les charges élémentaires sont récapitules en termes de complexité et de précision. Puis une méthode d’agrégation est développée, permettant d'obtenir un circuit équivalent d'ordre minimal et de structure compatible avec celle du réseau. La méthode d'identification des paramètres de ce circuit est basée sur une représentation fréquentielle de l’impédance harmonique, afin d'obtenir une réponse qui coïncide avec celle du réseau réel. Ce modèle agrège est utilise pour étudier la sensibilité de l’impédance harmonique aux variations aléatoires des paramètres caractéristiques du réseau et des charges.
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Rousseau, Marie. "Propagation d'incertitudes et analyse de sensibilité pour la modélisation de l'infiltration et de l'érosion." Phd thesis, Université Paris-Est, 2012. http://pastel.archives-ouvertes.fr/pastel-00788360.
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Nous étudions la propagation et la quantification d'incertitudes paramétriques au travers de modèles hydrologiques pour la simulation des processus d'infiltration et d'érosion en présence de pluie et/ou de ruissellement. Les paramètres incertains sont décrits dans un cadre probabiliste comme des variables aléatoires indépendantes dont la fonction de densité de probabilité est connue. Cette modélisation probabiliste s'appuie sur une revue bibliographique permettant de cerner les plages de variations des paramètres. L'analyse statistique se fait par échantillonage Monte Carlo et par développements en polynômes de chaos. Nos travaux ont pour but de quantifier les incertitudes sur les principales sorties du modèle et de hiérarchiser l'influence des paramètres d'entrée sur la variabilité de ces sorties par une analyse de sensibilité globale. La première application concerne les effets de la variabilité et de la spatialisation de la conductivité hydraulique à saturation du sol dans le modèle d'infiltration de Green--Ampt pour diverses échelles spatiales et temporelles. Notre principale conclusion concerne l'importance de l'état de saturation du sol. La deuxième application porte sur le modèle d'érosion de Hairsine--Rose. Une des conclusions est que les interactions paramétriques sont peu significatives dans le modèle de détachement par la pluie mais s'avèrent importantes dans le modèle de détachement par le ruissellement
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Hejtmánek, Petr. "Vliv aerodynamických parametrů na jízdní vlastnosti vozidel." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-234180.
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The main aim of this dissertation was to develop a computational tool capable of evaluating the influence of aerodynamics on the handling of a vehicle. The methodology it uses is based on the simulation of driving manoeuvres with a single-track model of a vehicle, which was composed with an emphasis on minimizing the amount of necessary input parameters. This simple model, which allows the assessment of the influence of aerodynamics on vehicle dynamic and static driveability, therefore doesn’t require large amount of input data, which makes the acquirement of relevant values easier. The computational model was validated by extensive measurements of two driving manoeuvres defined by ISO norms (step steer input and steady state cornering). As a consequence of unsatisfactory initial validation results, the differences between measurements and simulations were analysed, which led to gradual enhancements of the model with additional inputs to achieve better accuracy of simulations. The final part of the thesis deals with the comparison of influences of individual aerodynamic parameters on vehicle handling and the assessment of overall significance of aerodynamics compared to other factors which were taken into account (tires, mass properties, steering etc.). This thesis was realized in close cooperation with Škoda-Auto.
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Castellanos, Silva Abraham. "Compensation adaptative par feedback pour le contrôle actif de vibrations en présence d’incertitudes sur les paramètres du procédé." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT050/document.
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Dans cette thèse, nous proposons des solutions pour la conception de systèmes de contrôle actif de vibration robustes (AVC). Le manuscrit de thèse comporte deux grandes parties.Dans la première, les problèmes d'incertitude paramétrique dans les systèmes de contrôle actif de vibration sont étudiés. En plus des incertitudes sur la fréquence des perturbations, nous avons trouvé que la présence de zéros complexes peu amortis soulevait des problèmes de conception difficiles, même pour des systèmes et des modèles parfaitement connus. Dans ce contexte, nous avons proposé des solutions pour le problème linéaire. Une procédure améliorée d'identification en boucle fermée a été développée pour réduire les incertitudes dans l'identification de ces zéros. Pour traiter les incertitudes sur la perturbation, l'adaptation de la fréquence est de toute façon incontournable.La seconde partie est consacrée au développement et/ou à l'amélioration de deux algorithmes, désormais classiques, de compensation par feedback adaptatif direct, fondés sur la paramétrisation de Youla-Kučera. Le premier résulte de l'amélioration d'un précédent travail (Landau et al., 2005) ; les contributions concernent la synthèse du contrôleur central robuste et l'utilisation optionnelle de la surparamétrisation du filtre Q-FIR (réponse à temps fini) avec pour effet de minimiser l'effet « waterbed » sur la fonction de sensibilité de sortie. Le second algorithme présente une structure hybride directe/indirecte qui utilise un filtre Q-IIR (à temps de réponse infini). Les améliorations sont dues principalement au dénominateur du filtre, obtenu à partir d'une estimation de la perturbation. Cette solution permet également de simplifier la conception du contrôleur central.Les algorithmes ont été testés, comparés et validés sur un procédé réel du laboratoire Gipsa-lab, dans le cadre d'un benchmark internationalIn this thesis, solutions for the design of robust Active Vibration Control (AVC) systems are presented. The thesis report is composed of two main parts.In the first part of the thesis uncertainties issues in Active Vibration Control systems are examined. In addition of the uncertainties on the frequency of the disturbances it has been found that the presence of low damped complex zeros raise difficult design problems even if plant and models are perfectly known. Solutions for the linear control in this context have been proposed. In order to reduce the uncertainties in the identification of low complex zeros and improved closed loop identification procedure has been developed. To handle the uncertainties on the disturbance frequency adaptation has any way to be used.The second part is concerned with the further development and/or the improvement of the now classical direct adaptive feedback compensation algorithms using Youla Kucera controller parametrization. Two new solutions have been proposed in this context. The first one results from the improvement of a previous work (Landau et al., 2005). The contributions are a new robust central controller design to the optional use of over parameterization of the Q-FIR filter which aims to ensure a small waterbed effect for the output sensitivity function and therefore reducing the unwanted amplification. The second algorithm presents a mixed direct/indirect structure which uses a Q-IIR filter. The improvements are mainly the effect of the Q filter denominator, which is obtained from a disturbance identification. This solution in addition drastically simplifies the design of the central controller.The algorithms have been tested, compared and validated on an international benchmark setup available at the Control System Department of GIPSA-Lab, Grenoble, France
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Monnanni, Andrea. "Ponti a cassone monocellulare in c.a.p.: sviluppi analitici, modelli numerici, analisi di sensitività e studio parametrico." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Il calcolo delle sollecitazioni negli impalcati a cassone monocellulare è abbastanza semplice qualora si utilizzi un programma di calcolo, ma è assai più complesso capire i meccanismi fisici con cui si sviluppano. Infatti, questi impalcati sono dotati di diaframmi di irrigidimento solamente in corrispondenza delle spalle e delle pile. L’assenza dei diaframmi in campata non consente di ritenere queste sezioni trasversalmente rigide, come richiesto dalla teoria classica di DSV. Quindi si rende necessario considerare deformabile la sezione nel proprio piano e considerare tutti gli effetti prodotti dalla perdita di forma. Infatti, per condizioni di carico antisimmetriche i nodi della sezione trasversale possono subire spostamenti relativi, quindi la sezione si distorce, facendo nascere sollecitazioni trasversali e longitudinali aggiuntive.
Il lavoro si pone l’obiettivo di studiare in modo approfondito il fenomeno fisico cui sono soggetti questi tipi di impalcati. In un primo momento studiando, in maniera molto dettagliata, la teoria analitica che ci permette di comprendere l’interazione che nasce tra la direzione trasversale e longitudinale dimostrando e ricostruendo alcuni passaggi analitici fondamentali.
Inoltre attraverso quest’approccio prettamente teorico si vuole quantificare ogni singolo contributo prodotto dal comportamento fisico dell’impalcato, realizzando anche dei modelli numerici con software FEM di confronto.
Al fine di capire l’influenza della distorsione della sezione, associata al caricamento antisimmetrico, che caratterizza questi tipi d’impalcati, si conduce un’analisi di sensitività variando la capacità di distorcersi della sezione.
Inoltre si conduce uno studio parametrico finalizzato alla ricerca di un metodo di progettazione semplificato utilizzabile in una fase di predimensionamento secondo il D.M. 14/01/2008 per l’impalcati a cassone monocellulare di sezione costante a una sola campata.
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Saleh, Marwan. "Étude mathématique et numérique des méthodes de réduction dimensionnelle de type POD et PGD." Thesis, La Rochelle, 2015. http://www.theses.fr/2015LAROS004/document.
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Ce mémoire de thèse est formé de quatre chapitres. Un premier chapitre présente les différentes notions et outils mathématiques utilisés dans le corps de la thèse ainsi qu’une description des résultats principaux que nous avons obtenus. Le second chapitre présente une généralisation d’un résultat obtenu par Rousselet-Chénais en 1990 qui décrit la sensibilité des sous-espaces propres d’opérateurs compacts auto-adjoints. Rousselet-Chénais se sont limités aux sous-espaces propres de dimension 1 et nous avons étendu leur résultat aux dimensions supérieures. Nous avons appliqué nos résultats à la Décomposition par Projection Orthogonale (POD) dans le cas de variation paramétrique, temporelle ou spatiale (Gappy-POD). Le troisième chapitre traite de l’estimation du flot optique avec des énergies quadratiques ou linéaires à l’infini. On montre des résultats mathématiques de convergence de la méthode de Décomposition Progressive Généralisée (PGD) dans le cas des énergies quadratiques. Notre démonstration est basée sur la décomposition de Brézis-Lieb via la convergence presque-partout de la suite gradient PGD. Une étude numérique détaillée est faite sur différents type d’images : sur les équations de transport de scalaire passif, dont le champ de déplacement est solution des équations de Navier-Stokes. Ces équations présentent un défi pour l’estimation du flot optique à cause du faible gradient dans plusieurs régions de l’image. Nous avons appliqué notre méthode aux séquences d’images IRM pour l’estimation du mouvement des organes abdominaux. La PGD a présenté une supériorité à la fois au niveau du temps de calcul (même en 2D) et au niveau de la représentation correcte des mouvements estimés. La diffusion locale des méthodes classiques (Horn & Schunck, par exemple) ralentit leur convergence contrairement à la PGD qui est une méthode plus globale par nature. Le dernier chapitre traite de l’application de la méthode PGD dans le cas d’équations elliptiques variationnelles dont l’énergie présente tous les défis aux méthodes variationnelles classiques : manque de convexité, manque de coercivité et manque du caractère borné de l’énergie. Nous démontrons des résultats de convergence, pour la topologie faible, des suites PGD (lorsqu’elles sont bien définies) vers deux solutions extrémales sur la variété de Nehari. Plusieurs questions mathématiques concernant la PGD restent ouvertes dans ce chapitre. Ces questions font partie de nos perspectives de rechercheThis thesis is formed of four chapters. The first one presents the mathematical notions and tools used in this thesis and gives a description of the main results obtained within. The second chapter presents our generalization of a result obtained by Rousselet-Chenais in 1990 which describes the sensitivity of eigensubspaces for self-adjoint compact operators. Rousselet-Chenais were limited to sensitivity for specific subspaces of dimension 1, we have extended their result to higher dimensions. We applied our results to the Proper Orthogonal Decomposition (POD) in the case of parametric, temporal and spatial variations (Gappy- POD). The third chapter discusses the optical flow estimate with quadratic or linear energies at infinity. Mathematical results of convergence are shown for the method Progressive Generalized Decomposition (PGD) in the case of quadratic energies. Our proof is based on the decomposition of Brézis-lieb via the convergence almost everywhere of the PGD sequence gradients. A detailed numerical study is made on different types of images : on the passive scalar transport equations, whose displacement fields are solutions of the Navier-Stokes equations. These equations present a challenge for optical flow estimates because of the presence of low gradient regions in the image. We applied our method to the MRI image sequences to estimate the movement of the abdominal organs. PGD presented a superiority in both computing time level (even in 2D) and accuracy representation of the estimated motion. The local diffusion of standard methods (Horn Schunck, for example) limits the convergence rate, in contrast to the PGD which is a more global approach by construction. The last chapter deals with the application of PGD method in the case of variational elliptic equations whose energy present all challenges to classical variational methods : lack of convexity, lack of coercivity and lack of boundedness. We prove convergence results for the weak topology, the PGD sequences converge (when they are well defined) to two extremal solutions on the Nehari manifold. Several mathematical questions about PGD remain open in this chapter. These questions are part of our research perspectives
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Salvà, Gagliolo Giuseppe. "Simulazione energetica di un edificio passivo: valutazione del performance gap determinato dal comportamento dell'utente e dalla qualità costruttiva." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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Simulazione parametrica su di un edificio passivo a S. Mauro Pascoli (FC), con valutazione di quanto l'incidenza dell'utente e della correttezza costruttiva possano incidere sulla reale prestazione dell'edificio, quindi il concetto di performance gap.
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Romano, Marisa. "Analisi della sensitività delle politiche manutentive al variare del grado di conoscenza dei parametri operativi dei componenti." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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In ambito aziendale, la manutenzione degli impianti gioca un ruolo strategico, risulta quindi necessario dedicare tempo e risorse alla corretta pianificazione degli interventi manutentivi. L'obiettivo principale è infatti quello di minimizzare gli intervalli di fermo, in quanto il verificarsi di un guasto tendenzialmente causa costi operativi più elevati e produce beni meno competitivi.
Visto il ruolo fondamentale assunto dalla manutenzione, il presente elaborato ha l'obiettivo di studiare la sensitività delle politiche preventive, al variare del grado di conoscenza di una serie di parametri definiti nel corso della trattazione. Nella prima parte dell'elaborato verrà fornito un quadro generale sui principi alla base della teoria affidabilistica, seguito da una descrizione dettagliata delle principali politiche di manutenzione. Successivamente, partendo dall'utilizzo di dati dal campo forniti da due aziende operanti nel bolognese, verrà condotto uno studio sperimentale focalizzato sull'analisi di sensitività delle politiche di manutenzione preventiva “Type I” e “Type II”. In particolare, si cercherà di analizzare l’impatto causato dall'evoluzione dei dati negli anni, sulle suddette politiche. Difatti, l'accumulo di nuovi dati fa in modo che i parametri che ne descrivono l'andamento si evolvano nel tempo; si è cercherà pertanto di capire se tale variazione ha un forte impatto sulle politiche oppure se l'impatto è marginale. Si concluderà quindi l'elaborato con un'analisi che valuti la sensibilità del costo e del tempo ottimale in cui effettuare gli interventi.
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Corne, Adrien. "Current Sensorless Control Strategies for an Automotive Electric Powertrain." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0292.
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L’application de quotas d’émissions de gaz à effet de serre a amené les constructeurs automobiles à augmenter le niveau d’électrification de leurs véhicules. En parallèle des véhicules tout électrique, se sont développées les solutions hybrides, tel le mild-hybrid autorisant l’association d’une chaîne de traction électrique avec le moteur à combustion dans le but d’absorber les pics de consommation de carburant. Afin de rester compétitif, les coûts de production d’un véhicule doivent être optimisés autant que possible, ainsi l’étude réalisée de commande de machine synchrone à griffes sans capteur de courant permet la suppression des capteurs du stator de la machine et donc de s’affranchir de leur coût. Une commande vectorielle de la machine est nécessaire afin d’optimiser les courants statoriques pour un couple donné. L’utilisation d’observateurs d’état permettant l’estimation des courants manquants a donc été privilégiée. Ainsi différentes topologies d’observateurs ont été développées : le filtre de Kalman étendu ainsi qu’un observateur d’état et deux déclinaisons dont la conception est basée sur une analyse de convergence à l'aide de fonctions de Lyapunov. Afin d’améliorer la précision de l’observation des courants statoriques, une étude approfondie du modèle électrique de la machine a été réalisée. Elle permet de minimiser les erreurs dues aux variations paramétriques, liées notamment à la saturation magnétique de la machine et des incertitudes liées aux phénomènes non modélisés de la chaîne de conversion électromécanique. Une méthode de cartographie de la machine a ainsi été proposée à l’aide d’un estimateur paramétrique. Les résultats expérimentaux, obtenus sur un banc de test réalisé en laboratoire, sont concluants en régime établi : les courants non mesurés sont estimés avec une précision satisfaisante pour une application automobile et permettent le contrôle sans capteur de courant de la machineThe application of greenhouse gases quotas has led the automotive manufacturers to increase the electrification level of their vehicles. In parallel with Battery Electric Vehicles (BEV), hybridization solutions have been developed. Among them, mild-hybrid technology allows the connection of an electric powertrain with an Internal Combustion Engine (ICE) with the aim of absorbing peaks of fuel consumption. In order to remain competitive, the manufacturing costs of a vehicle need to be optimized. In that regard, removing the stator currents sensors allows avoiding their inherent costs. However, within the vector control framework, a feedback on these currents is required to optimize their value for a given torque. For this reason, it has been decided to use state observers to estimate the missing currents. Different state observer solutions have thus been developed: the Extended Kalman Filter (EKF) and a state observer with two extensions whose design is based on a convergence analysis using Lyapunov functions. With the aim of improving the precision of the stator currents estimation, an in-depth study of the machine's electrical model was carried out. It allows minimizing errors due to parametric variations, related in particular to the magnetic saturation of the machine and uncertainties due to unmodeled phenomena in the whole drive. A method for mapping the machine was proposed using a parametric estimator. The experimental results, obtained on a test bench built in the laboratory, are conclusive in steady-state: the real currents are estimated with a satisfying precision for an automotive application and allow performing a current sensorless control of the machine
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Stenvall, Brita. "Känslighets- och osäkerhetsanalys av parametrar och indata i dagvatten- och recipientmodellen StormTac." Thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88864.
Full textAbstract:
Three methods of sensitivity and unceartainty analysis have been applied to the operative stormwater- and recipient model StormTac. The study area is the watershed of lake Flaten in the municipality Salem. StormTac’s submodels for stormwater, pollutant transport and the recipient are cosidired. In the sensitivity assessment, the model parametres and inputs were varied one at a time by a constant percentage according to the “one at a time” (OAAT) method and the response of the outputs were calculated. It was found that the stormwater- and baseflow were most sensitive to perturbations in the perciptation. Unceartainty analysis using Monte Carlo simulation was performed in two different ways. (1) All model parametres and inputs were included with defined unceartainties and the resulting unceartainty for the target variable was quantified. Thereafter, whith the purpose to estimate the contribution of all the parametres and inputs, the cumulative uncertainty for the target variable, each parameters/inputs unceartainty was omitted one at the time. The most crucial uncertainty for the storm water flow was the runoff coefficient for forestland and the perciptation (i.e the differens between the 90- and 10-percentile for the storm water flow was reduced whith 44 % and 33 % respectively). (2) To identify optimal parameter intervals, the probability for an acceptable value of the target variable was plotted against each parameters value range. The result suggests that for some of the parametres i StormTac, the ranges should be changed.
Den operativa dagvatten- och recipientmodellen StormTac har applicerats på sjön Flatens avrinningsområde i Salems kommun. StormTac:s delmodeller för dagvatten, föroreningstransport och recipienten studerades. Tre olika metoder för att undersöka osäkerheten och känsligheten hos parametrar och indata i delmodellerna tillämpades. I känslighetsanalysen (OAAT-metoden) behäftades parametervärdena och indata med systematiska fel och responsen hos utdata beräknades. Dag- och basvattenflödet var känsligast mot fel i nederbördsdata, medan kväve-, fosfor- och kopparbelastningen till recipienten var känsligast mot respektive förorenings dagvattenkoncentration från områden med bebyggelse. Varje parameter och indatas bidrag till den kumulativa osäkerheten hos utdata uppskattades med hjälp av Montecarlosimulering. Genom att för varje effektvariabel studera differensen mellan 90- och 10-percentilen när osäkerheten hos en parameter/indata i taget utelämnades, kunde varje parameters/indatas bidrag till modellresultatets osäkerhet kvantifieras. För dagvattenflödet bidrog avrinningskoefficienten för skogmark med 44 % av osäkerheten och nederbörden med 33 %. Montecarloanlys praktiserades även för att identifiera optimala intervall för parametrarna i modellen. Sannolikheten för ett accepterat värde på den simulerade effektvariabeln plottades mot varje parameters värdemängd. För vissa parametrar indikerade resultatet att intervallen kan förändras mot hur de i nuläget ser ut i StormTac. Uniforma sannolikhetsfördelningar, begränsade av StormTac:s min- och maxvärden för parametrarna och ± 50% av orginalvärdet för indata, användes i båda osäkerhetsanalyserna.
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Šeliga, Ladislav. "Vysokonapěťové součástky v moderních bipolárních technologiích." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-221014.
Full textAbstract:
Tato práce se zabývá popisem základních vlastností LDMOS tranzistorů. V první části práce jsou rozebrány vlastnosti LDMOS tranzistorů, jejich základní parametry a techniky pro vylepšení parametrů těchto tranzistorů. V další části je rozebrána spolehlivost LDMOS tranzistorů, tato část popisuje bezpečnou pracovní oblast (SOA), injekci horkých nosičů (HCI) a negativní teplotní stabilitu (NBTI). Poslední teoretická část popisuje používané modely pro simulaci ESD událostí. Praktická část práce je zaměřena na simulaci základních parametrů PLDMOS a NLDMOS tranzistorů, porovnání simulovaných a změřených koncentračních profilů. Dále se práce zabývá simulacemi změny geometrických parametrů PLDMOS tranzistoru a vliv těchto změn na elektrické parametry. Poslední část práce tvoří TLP simulace, které zkoumají elektrické vlastnosti PLDMOS tranzistoru při použití jako ESD ochrana.