Cette thèse propose une nouvelle méthode, via les outils de dosimétrie et de statistiques, pour l'évaluation de l'exposition globale d'une population aux champs électromagnétiques (EMFs) radiofréquences en prenant en compte les différentes technologies, usages et environnements... Nous avons analysé pour la première fois l'exposition moyenne d'une population induite par un réseau 3G, tout en considérant à la fois les émissions EMFs montantes et descendantes dans des différents pays, dans des différentes zones géographiques et pour les différents usages des mobiles. Les résultats montrent une forte hétérogénéité de l'exposition dans le temps et dans l'espace. Contrairement à la croyance populaire, l'exposition aux ondes EMFs 3G est dominée par les émissions montantes, résultant de l'usage voix et data. En outre, l'exposition moyenne de la population diffère d'une zone géographique à une autre, ainsi que d'un pays à un autre, en raison des différentes architectures de réseau cellulaire et de la variabilité de l'usage des mobiles. Ensuite, la variabilité et les incertitudes liées à ces facteurs ont été caractérisées. Une analyse de sensibilité basée sur la variance de l'exposition globale a été effectuée dans le but de simplifier son évaluation. Enfin, une méthodologie simplifiée basée sur des outils statistiques avancés a été proposée pour évaluer l'exposition réelle de la population en tenant compte de la variabilité liée à l'environnement de propagation, à l'usage, ainsi qu'aux émissions EMFs provenant des mobiles et des stations de base (BTS). Les résultats ont souligné l'importance de la densité de puissance reçue depuis les BTS pour l'exposition globale induite par un réseau macro LTE. / Wireless communication technologies, since their introduction, have evolved very quickly and people have been brought in 30 years into a much closer world. In parallel radiofrequency (RF) electromagnetic fields (EMF) are more and more used. As a consequence, people's attentions around health risks of exposure to RF EMFs have grown just as much as their usages of wireless communication technologies. Exposure to RF EMFs can be characterized using different exposure metrics (e.g., incident field metrics, absorption metrics...). However, the existing methodologies are well suited to the maximum exposure assessment for the individual under the worst-case condition. Moreover in most cases, when dealing with exposure issues, exposures linked to RF EMF emitted from base stations (BTS) and by wireless devices (e.g, mobile phones and tablets) are generally treated separately. This thesis has been dedicated to construct and validate a new method for assessing the real day-to-day RF EMF exposure to a wireless network as a whole, exploring the people's daily life, including both downlink and uplink exposures and taking into account different technologies, usages, environments, etc. Towards these objectives, we analyzed for the first time the average population exposure linked to third generation network (3G) induced EMFs, from both uplink and downlink radio emissions in different countries, geographical areas, and for different wireless device usages. Results, derived from device usage statistics, show a strong heterogeneity of exposure, both in time and space. We show that, contrary to popular belief, exposure to 3G EMFs is dominated by uplink radio emissions, resulting from voice and data traffic, and average population EMF exposure differs from one geographical area to another, as well as from one country to another, due to the different cellular network architectures and variability of mobile usage. Thus the variability and uncertainties linked to these influencing factors were characterized. And a variance-based sensitivity analysis of the global exposure was performed for the purpose of simplifying its evaluation. Finally, a substitution model was built to evaluate the day-to-day global LTE induced EMFs exposure of a population taking into account the variability linked to propagation environment, usage, as well as EMFs from personal wireless devices and BTS. Results have highlighted the importance of received power density from BTS to the issue of global exposure induced by a macro LTE network. This substitution model can be further used to analyze the evolution of the wireless network in terms of EMF exposure.

La mécanique computationnelle est un outil incontournable pour le monde de l’ingénierie mécanique. Motivé par un désir de réalisme et soumis à un perpétuel gigantisme, les modèles numériques doivent aujourd’hui inclure des phénomènes physiques de plus en plus complexes. Par conséquence, d’importantes capacités calculatoires sont requises afin de traiter des problèmes à la fois non-linéaires mais aussi de grande taille. Pour atteindre cet objectif, il convient de développer les stations de calculs mais aussi les méthodes algorithmiques utilisées afin de résoudre efficacement ces types de problèmes. Récemment, les méthodes de réduction de modèle se révèlent comme d’excellentes options au développement d’algorithmes de résolution performants. Le problème du contact frottant entre solides élastiques est particulièrement bien connu pour sa complexité et dont les temps de calcul peuvent devenir prohibitifs. En effet, les lois qui le régissent sont très hautement non-linéaires (non différentiables). Dans ce mémoire, nous nous proposons d’appliquer différentes méthodes de réduction de modèle (a posteriori et a priori) à ce type de problème afin de développer des méthodes de calculs accélérées dans le cadre de la méthode des éléments finis. Tout d’abord, en se plaçant dans le cadre des petites perturbations en évolution quasistatique, la réductibilité de diverses solutions impliquant du contact frottant est mise en évidence via leur décomposition en valeur singulière. De plus, leur contenu à échelle séparée est exhibé. La méthode non-incrémentale et non-linéaire à large incrément de temps (LATIN) est par la suite présentée. Dans un second temps et à partir des observations faites précédemment, une méthode LATIN accélérée est proposée en s’inspirant des méthodes multigrilles non-linéaires de type “full approximation scheme” (FAS). Cette méthode s’apparente en partie aux méthodes de réduction de modèle de type a posteriori. De plus, une stratégie de calcul de modes à partir d’un modèle de substitution est proposée. Par la suite, la décomposition propre généralisée (PGD) est utilisée afin de développer une méthode de résolution non-linéaire efficace reposant fondamentalement sur une approche de réduction de modèle de type a priori. Enfin, quelques extensions sont proposées telle que la résolution de problème faisant intervenir des études paramétriques, ou encore la prise en charge de non-linéarités supplémentaires telle que la plasticité. / Computational mechanics is an essential tool for mechanical engineering purposes. Nowadays, numerical models have to take into account complex physical phenomenons to be even more realistic and become larger and larger. As a consequence, more and more computing capacities are required in order to tackle not only non-linear problems but also large scale problems. For that purpose, both computers and numerical methods have to be developed in order to solve them efficiently. In the last decades, model reduction methods show great abilities to assign such challenges. The frictional contact problem between elastic solids is particularly well-known for its difficulty. Because its governing laws are highly non-linear (non-smooth), prohibitive computational time can occur. In this dissertation, model reduction methods (both a posteriori and a priori approaches) are deployed in order to implement efficient numerical methods to solve frictional contact problem in the finite element framework. First, small perturbations hypothesis with a quasi-static evolution are assumed. Then, reducibility of some frictional solutions is emphasized and discussed using the singular value decomposition. In addition, a scale separability phenomenon is enlightened. Then, the non-linear large time increment method (LATIN) is introduced. Secondly, an accelerated LATIN method is suggested by drawing an analogy between previous scale separability observations and the non-linear multigrid full approximation scheme (FAS). This accelerated non-linear solver relies essentially on the a posteriori model reduction approach. A precomputation strategy for modes relying on surrogate models is also suggested. Next, the proper generalized decomposition (PGD) is used to implement a non-linear solver relying fundamentally on an a priori model reduction method. Finally, some extensions are given to assign parametric studies and to take into account an additional non-linearity such as elastoplastic constitutive laws.

This thesis titled, “Nature of Local Interactions at cisPro-Aro Peptide Sequences in Proteins: Evidences for van der Waals type Interactions. Design and Synthesis of Novel Covalent Surrogates for the Peptide Hydrogen Bond”, describes two important studies. The first is to gain a thorough understanding of the nature of interactions that govern cisPro stability at Pro-Aro sequences, which described in the first four chapters. The final chapter describes the synthesis of novel 4-carbon covalent surrogates for the peptide H-bonding interaction. Chapter 1: Local Interactions Governing cisPro Stability: Refining the Model Peptides Chapter 1 Section A: Understanding the role of inter-side chain CH•••Aro interaction in cis-trans isomerization at Pro-Aro and Aro-Pro Sequences. This chapter is divided into two sections. In the first section an exhaustive overview of earlier investigations into the nature of local interactions at Xaa-cisPro-Aro and Aro-cisPro-Xaa peptide sequences, by various groups, are discussed. Most studies have found evidence for the close assemblage between side chains of residues flanking cisPro motifs, when at least one of them is an aromatic group. An electronic C-H•••π nature has been proposed for these assemblies and they are proposed to influence the cisPro stability. We highlight those features in these studies that indicate that these interactions are not always electronically tunable, are insensitive to presence of strong chaotropes in the solvent and occur at protein sequences lacking Pro or cisPro; all of which contradict the electronic C-H•••π model for these inter-side chain assemblages and their perceived influence on cisPro stability. Chapter 1 Section B: Investigation of the Nature of H Xaa•••Aro interaction at Xaa-Pro-Pro-Phe-sequences In Section B, we design and synthesize Pro-Aro containing short peptide models to investigate the nature of local C-H•••Aro interactions in them. We synthesize a series of homologous Pro-Pro-Aro containing peptides (modeled based on earlier studies) and investigate the relative populations of its four Xaa-Pro rotamers using extensive 1D and 2D NMR techniques including TOCSY, HSQC and ROESY. We find several drawbacks that make this a relatively deficient model. Firstly, their relative populations of the rotamers (the most important data for current investigation) cannot be determined with high fidelity as they are dependent on the solvent polarity, solute concentration and chemical shift degeneracy of crucial NMR signals for the rotamers. Importantly, the populations of a few rotamers are influenced by strong 13-membered ring backbone H-bonds. Notably, some of the cisPro rotamers do not even contain the inter-side chain assembly, whose nature is under investigation. Design of novel models – unconstrained by H-bonds We design the Acyl-Pro-Pro-Aro-OMe peptides that lack the possibility of forming the 13-membered ring H-bonded structures. Thorough 1D and 2D NMR analyses of these models reveal that strong Type VI β-turn type 10-membered ring H-bonds are formed in the rotamers of these models – hence precluding their applications for current study. Interestingly, the relative rotamer populations are strongly influenced by solvent polarity and are entirely different from those of the corresponding C-terminal amide models. We further discover that the Pro-Pro-Aro motif is not essential to express the inter-side chain interactions – Ala-Pro-Aro are sufficient. Formation of the 10-membered H-bonding interactions, however, are not precluded. Chapter 2: Design and Synthesis of Acyl-Pro-Phe-OMe: Novel models to investigate the role of HαXaa•••Aro interactions on Xaa-cisPro-Aro stability. Chapter 2 Section A: Design, Synthesis and Conformational Analysis of Ibu-Pro-Phe-OMe Chapter 2 is divided into two sections. In Section A, we replace the amino acid at the N-terminal of the putative Pro residue with simple isosteric isobutyryl group, the resulting minimalist dipeptide model shows the exclusive influence of desired inter-side chain interactions in the cisPro rotamer. Solvent polarity and temperature coefficient studies reveal that absence of any intramolecular H-bonding or Oπ* interactions in it. 1D and 2D NMR analyses clearly indicate the close proximity between the side chains of Ibu and Phe exclusively in the cisPro rotamer. The Kc/t value decreases upon mutation of Phe to Ala. All these features favor the Ibu-Pro-Phe-OMe as an ideal minimalistic model for investigating the nature of Ibu•••Ph assemblages in the cisPro rotamer. Chapter 2 Section B: Investigation of CH•••Aro /Alp•••Alp interactions in Ibu-cisPro-Xaa-OMe In Section B, the 1D and 2D NMR analyses of the complete set of the aliphatic and aromatic analogues Ibu-Pro-Xaa-OMe were investigated. DMSO-d6 was found to be the best solvent for mimicking both the folded and the unfolded local environments of these short peptide sequences. The HαIbu•••Aro assemblage is observed in Aro analogues, but cannot be electronically tuned. The aliphatic analogues also surprisingly contain the HαIbu•••Alp interactions! The Kc/t values (cisPro %) increase in the aliphatic analogues too, where the aliphatic side chain is long. Increase in cisPro stability is not due to ring current effects or intramolecular H-bonds or Oπ* interactions. It seems to be due to van der Waals type interactions between the involved side chains, either of which need not be aromatic in nature. Chapter 3: Nature of Inter-Side Chain Interactions at Acyl-cisPro-Aro Sequences: Evidence for van der Waals Interactions Chapter 3 Section A: Investigation of nature of inter-side chain interactions in R-CO-cisPro-Phe-OMe Chapter 3 has two sections. Section A describes the systematic design and synthesis of Acyl-Pro-Phe-OMe homologues where first the steric bulk and hence the surface area of the aliphatic side chain of the acyl group is varied. Interaction of the phenyl ring of Phe seems to occur with the Cα-Cβ σ-bond of the acyl group. Branching at either Cα or Cβ seems to destabilize the cisPro rotamer. Aliphatic•••Aromatic interactions overwhelm the cisPro rotamer population to be greater than that of transPro. In the analogues where the acidity of the acyl Cα-H bond is increased, the Kc/t does not increase correspondingly. The Δδ(trans-cis) ppm shifts of HαAcyl protons are dependent exclusively on its acidity rather than on the Kc/t values. In carbamyl-Pro, which entirely lack the HαAcyl proton, the Kc/t values are significantly high and improve as the aliphatic surface on the alkoxy group increases. Introduction of benzyloxy carbamyl group at Pro renders almost the same Kc/t values as that of ethyloxy carbamate. All these data contradict the C-H•••π interaction model and strongly support a van der Waals type interaction between the Acyl (preceding cisPro) group’s Xα-Yβ σ-bond and the Aro or Alp side chains (succeeding cisPro). Chapter 3 Section B: Evidence for the Van der Waals nature of Inter Side Chain (Acyl•••S.C.Aro/Alp) interactions- Determination of Interactions energies In Section B, a thorough investigation of both aliphatic•••aliphatic and aliphatic•••aromatic interactions on the background of homologous Acyl-Pro-Aro/Alp-OMe peptide models is undertaken. These models uniquely allow the delineation of contribution of the van der Waals interactions and the ring current effects to the cis/trans isomerization in these peptides. We see that the energy of the van der Waals component of these aliphatic•••aliphatic and aliphatic…aromatic interactions increase linearly with increase in Kc/t, in both DMSO-d6 and D2O. On other hand, energy from the ring current effects largely remains invariant. The Acyl•••Aro/Alp interactions are not hydrophobic and are facilitated by conformational effects. Chapter 4: Crystallographic evidence for van der Waals interaction-mediated stabilization of cisPro conformers Chapter 4 Section A: Systematic crystallization and crystal structure analyses of homologous Xaa-cisPro-Alp and Xaa-cisPro-Aro rotamers: Evidence for van der Waals interactions Chapter 4 has two sections, both of which present crystallographic evidence for the van der Waals nature of the Xaa•••Aro interactions at Xaa-cisPro-Aro sequences. Section A describes the unique crystal structures of five of the Acyl-Pro-Alp-OMe analogues that have been synthesized in the current study. All of them remarkably crystallize with two features: 1) the Acyl-Pro peptide bond adopts the cisPro rotamer in all; and 2) the aliphatic side chains of the acyl group and the Alp side chain are involved in van der Waals type interactions. The cisPro rotamers of even the bulkiest motifs, namely Ibu-Pro-Val-OMe, Piv-Pro-Ile-OMe and Piv-Pro-Leu-OMe crystallize, stabilized by van der Waals packing between aliphatic groups of the acyl and the Leu/Ile/Val side chains. Where the side chains are not long enough to make sub-van der Waals contacts with each other, their acyl C′-Cα σ-bond rotations are restricted due to Oσ* interactions involving the charge on the acyl carbonyl O. Where this occurs, the short space between the acyl and Alp side chains are filled in by aliphatic groups from neighbouring molecules at sub van der Waals distances. The Pro, Alp and χ1(Alp) dihedral angles are restricted to narrow range of values, irrespective of the length of Alp side chain, indicating that this backbone conformation is a conformational minimum when i+3i backbone H-bond is removed, with Pro at the i+1st position. This is further substantiated in Piv-Pro-Gly-OMe, which crystallizes in trans-Pro form, but still adopts similar backbone dihedral angles in spite of lacking any Alp side chain for interactions with the acyl group. Three of the Acyl-Pro-Aro-OMe models also crystallize in cisPro rotamer forms – both exhibit van der Waals type contacts between the Acyl group and backbone of Phe, rather than the aromatic ring of Phe. The phenyl ring of Phe may or may not form intramolecular Ph•••Pro inter-side chain contacts – which is not a pre-requisite for cisPro stabilization. No C-H••• interactions are observed anywhere in these peptides – van der Waals type contacts alone predominate in all cases. There are no abnormal distortions in bond angles or lengths even in the most sterically hindered cases, signifying that the conformations of these cisPro rotamers involving aliphatic•••aliphatic type contacts are natural minima. Chapter 4 Section B: Mining the PDB for Statistical Evidence of van der Waals interactions Section B of chapter 4 describes the data mining and statistical analyses of Xaa-cisPro-Phe, Xaa-cisPro-Val and Xaa-cisProLeu sequences in the PDB. The PEARL program was used to mine the PDB data. The overall frequency of 5.3% for appearance of cisPro among all Xaa-Pro peptide bonds, improves when Xaa is Phe or Tyr. However, several anomalies highlight the need for refining the analyses set to only those sequences where the side chains of Xaa and Aro/Alp face each other. In this refined set, clearly, inter side chain Xaa•••Alp/Aro contacts take precedence over even Aro•••Pro interactions at Aro-cisPro sequences (where Xaa is Aro). The Phe and the Leu side chains induce similar conformational effects on the preceding Xaa-Pro backbone. So does Val. Strong aliphatic•••aliphatic inter side chain contacts at van der Waals distances are observed to flank cisPro in several proteins. Substitution at the Cα of Xaa governs the proximity of the approaching side chain of Alp / Aro residue. The Cα-H of Xaa steers away from the Aro side chain at Xaa-Pro-Phe sequences, as the Aro group gets closer to it – implying the absence of ordered C-H••• contacts between them. There is consistent parallel alignment between Cα-Cβ -bond of Xaa and the C -C bond of the approaching side chain of Alp or Aro group – clearly highlighting the presence of van der Waals type interactions between them. All these evidences clearly point towards the van der Waals nature of local interactions at cisPro-Aro/Alp peptide sequences. Chapter 5: A novel 4-carbon covalent surrogate model for peptide H-Bond Chapter 5 describes the design and synthesis of novel 4-carbon covalent surrogates for the peptide H-bond (HBS). These surrogates would allow the unique constraining of two peptide strands in their extended conformations. The covalent HBS contain four orthogonal functional groups for independent extension at all of the four ends – similar to an endogenous inter-strand peptide H-bond. The synthesis of the surrogate is achieved by directly using natural chiral amino acid derivatives, beginning from amino alcohols obtained from reduction of desired amino acids. Suitably N-protected alcohols undergo oxidation to aldehyde followed by Grignard addition of allyl magnesium bromide, TBDMS protection of the homoallylic alcohol and reductive ozonolysis of the olefin to get a primary alcohol which is subject to Fukuyama-Mitsunobu reaction with desire protected peptide. The residue preferences that produce strongest inter-strand H-bonds were explored. The designed 4-carbon covalent HBS was incorporated using this methodology in a Gramicidin-S analogue, its first structural mimic containing only a single turn motif. This HBS model will have wide applications for constraining peptides in a number of secondary structures.

Diploma thesis is focused on advanced reliability analysis of structures solved by non--linear finite element analysis. Specifically, semi--probabilistic methods for determination of design value of resistance, sensitivity analysis and surrogate model created by polynomial chaos expansion are described in the diploma thesis. Described methods are applied on prestressed reinforced concrete roof girder.

Being able to accurately approximate outputs of computationally expensive simulations for arbitrary input parameters, also called missing points estimation, is central in many different areas of research and development with applications ranging from uncertainty propagation to control system design to name a few. This project investigates the potential of kernel transformations and nonlinear autoencoders as methods of improving the accuracy of the proper orthogonal decomposition method combined with regression. The techniques are applied on aerodynamic pressure CFD data around airplane wings in both two- and three-dimensional settings. The novel methods show potential in select situations, but cannot at this stage be generally considered superior. Their performances are similar although the procedure of design and training of a nonlinear autoencoder is less straight forward and more time demanding than using kernel transformations. The results demonstrate the regression bottleneck of the proper orthogonal decomposition method, which partially is improved with the new methods. Future studies should focus on adapting the autoencoder training strategy to the architecture and data as well as improving the regression stage of all methods.

Indiana University-Purdue University Indianapolis (IUPUI) / With the recent advancement of computation and imaging technology, Image-based computational fluid dynamics (ICFD) has emerged as a great non-invasive capability to study biomedical flows. These modern technologies increase the potential of computation-aided diagnostics and therapeutics in a patient-specific environment. I studied three components of this image-based computational fluid dynamics process in this work. To ensure accurate medical assessment, realistic computational analysis is needed, for which patient-specific image segmentation of the diseased vessel is of paramount importance. In this work, image segmentation of several human arteries, veins, capillaries, and organs was conducted to use them for further hemodynamic simulations. To accomplish these, several open-source and commercial software packages were implemented. This study incorporates a new computational platform, called InVascular, to quantify the 4D velocity field in image-based pulsatile flows using the Volumetric Lattice Boltzmann Method (VLBM). We also conducted several parametric studies on an idealized case of a 3-D pipe with the dimensions of a human renal artery. We investigated the relationship between stenosis severity and Resistive index (RI). We also explored how pulsatile parameters like heart rate or pulsatile pressure gradient affect RI. As the process of ICFD analysis is based on imaging and other hemodynamic data, it is often time-consuming due to the extensive data processing time. For clinicians to make fast medical decisions regarding their patients, we need rapid and accurate ICFD results. To achieve that, we also developed surrogate models to show the potential of supervised machine learning methods in constructing efficient and precise surrogate models for Hagen-Poiseuille and Womersley flows.

Neutrino astronomy is expanding into the ultra-high energy (>1017eV) frontier with the use of in-ice detection of Askaryan radio emission from neutrino-induced particle showers. There are already pilot arrays for validating the technology and the next few years will see the planning and construction of IceCube-Gen2, an upgrade to the current neutrino telescope IceCube. This thesis aims to facilitate that planning by providing faster simulations using deep learning surrogate models. Faster simulations could enable proper optimisation of the antenna stations providing better sensitivity and reconstruction of neutrino properties. The surrogates are made for two parts of the end-to-end simulations: the signal generation and the signal propagation. These two steps are the most time-consuming parts of the simulations. The signal propagation is modelled with a standard fully connected neural network whereas for the signal generation a conditional Wasserstein generative adversarial network is used. There are multiple reasons for using these types of models. For both problems the neural networks provide the speed necessary as well as being differentiable -both important factors for optimisation. Generative adversarial networks are used in the signal generation because of the inherent stochasticity in the particle shower development that leads to the Askaryan radio signal. A more standard neural network is used for the signal propagation as it is a regression task. Promising results are obtained for both tasks. The signal propagation surrogate model can predict the parameters of interest at the desired accuracy, except for the travel time which needs further optimisation to reduce the uncertainty from 0.5 ns to 0.1 ns. The signal generation surrogate model predicts the Askaryan emission well for the limited parameter space of hadronic showers and within 5° of the Cherenkov cone. The two models provide a first step and a proof of concept. It is believed that the models can reach the required accuracies with more work.

This thesis covers the process of automating the design of coolant nozzles used for cylindrical grinding. Coolant nozzles are used to supply coolant, an oil and water mixture used to cool the metal workpiece and lubricate the grinding wheel. In the automotive industry, grinding is used to reduce the surface roughness of the workpiece. However, a large amount of heat is generated, risking the heat treatment of the steel to be compromised, for this, coolant is supplied to minimize the heat caused by friction. A nozzle is used, aiming a jet to the zone that generates heat. Commonly used nozzles are adjustable, leading to variation in cooling performance if misaligned. The design of fixed nozzles is developed in this thesis to reduce variation and automatise the design for multiple applications. The automatically designed nozzles are fused deposition modeled and tested. The design automation tool is tested repeatedly and improved successively in the span of the thesis. This lead to a great extent of implementation of design automation. Which lead to a facilitation in reaching of the work zone and avoid obstacles. Also, the tool managed to create nozzle tubes for a multitude of machines. The tool is able to generate, aim, orient, and individually dimension multi-nozzle tubes. Design of Experiment methodology is implemented to find nozzle designs with improved velocity and flow rate and minimize the air mixture with the coolant. Several nozzle designs are tested and fitted into a surrogate model that is, in turn, optimized. The results of the tests led to a greater understanding of how the nozzle geometry restricts the flow rate when attempts of reaching higher velocities of the coolant jet are made. The surrogate models created, also made it possible to find the range of designs which best suits different applications, whereby a Pareto front was able to be populated with a range of different designs alternating in flow rate, velocity and coherency ratio.

[pt] A análise de fluxo de água sob condição transiente não saturada requer o conhecimento das propriedades hidráulicas do solo. Essas relações constitutivas, denominadas curva característica e função de condutividade hidráulica, são descritas através de modelos empíricos que geralmente possuem vários parâmetros que devem ser calibrados com relação a dados coletados. Muitos dos parâmetros nos modelos constitutivos não podem ser medidos diretamente em campo ou laboratório, mas somente podem ser inferidos de forma significativa a partir de dados coletados e da modelagem inversa. Para obter os parâmetros do solo com a análise inversa, um algoritmo de otimização de busca local ou global pode ser aplicado. As otimizações globais são mais capazes de encontrar parâmetros ótimos, no entanto, a solução direta, por meio da modelagem numérica é computacionalmente custosa. Portanto, soluções analíticas (modelo substituto) podem superar essa falha acelerando o processo de otimização. Nesta dissertação, apresentamos a Regressão Polinomial Evolucionária (EPR) como uma ferramenta para desenvolver modelos substitutos do fluxo não saturado. Um rico conjunto de dados de parâmetros hidráulicos do solo é usado para calibrar o nosso modelo, e dados do mundo real são utilizados para validar nossa metodologia. Nossos resultados demonstram que o modelo da EPR prevê com precisão os dados de carga de pressão. As simulações do modelo se mostram concordantes com as simulações do programa Hydrus. / [en] Water flow analyses under transient soil hydraulic conditions require knowledge of the soil hydraulic properties. These constitutive relationships, named soil-water characteristic curve (SWCC) and hydraulic conductivity function (HCF) are described through empirical models which generally have several parameters that must be calibrated against collected data. Many of the parameters in SWCC and HCF models cannot be directly measured in field or laboratory but can only be meaningfully inferred from collected data and inverse modeling. In order to obtain the soil parameters with the inverse process, a local or global optimization algorithm may be applied. Global optimizations are more capable of fiding optimum parameters, however the direct solution through numerical modeling are time consuming. Therefore, analytical solutions (surrogate models) may overcome this shortcomming by accelerating the optimization process. In this work we introduce Evolutionary Polynomial Regression (EPR) as a tool to develop surrogate models of the physically-based unsaturated flow. A rich dataset of soil hydraulic parameters is used to calibrate our surrogate model, and real-world data are then utilized to validate our methodology. Our results demonstrate that the EPR model predicts accurately the observed pressure head data. The model simulations are shown to be in good agreement with the Hydrus software package.

The procedure of joining flexible or nonrigid parts using applied loads is called compliant assembly, and it is widely used in automotive, aerospace, electronics, and appliance manufacturing. Uncontrolled assembly processes may produce geometric errors that can exceed design tolerances and induce an increment of elastic energy in the structure due to the accumulation of internal stresses. This condition might create unexpected deformations and residual stress distributions across the structure that compromise product functionality. This thesis presents a method based on nonlinear Finite Element Analysis (FEA), metamodelling, and optimization techniques to provide accurate and on-time shimming strategies to support the definition of optimum assembly strategies. An example of the method on a typical aerospace wing box structure is demonstrated in the present study. The delivered outputs intend to support the production line by anticipating the response of the structure under a specific assembly condition and presenting alternative assembly strategies that can be applied to address eventual predicted issues on product requirements. / Graduate