<p>This thesis focuses on chaotic stationary waves, both quantum mechanical and classical. In particular we study different statistical properties regarding thesewaves, such as energy transport, intensity (or density) and stress tensor components. Also, the methods used to model these waves are investigated, and somelimitations and specialities are pointed out.</p>

This thesis focuses on chaotic stationary waves, both quantum mechanical and classical. In particular we study different statistical properties regarding thesewaves, such as energy transport, intensity (or density) and stress tensor components. Also, the methods used to model these waves are investigated, and somelimitations and specialities are pointed out.

In this thesis, the two-dimensional initial and boundary value problems (IBVPs) and the one-dimensional Cauchy problems defined by the nonlinear reaction- diffusion and wave equations are numerically solved. The dual reciprocity boundary element method (DRBEM) is used to discretize the IBVPs defined by single and system of nonlinear reaction-diffusion equations and nonlinear wave equation, spatially. The advantage of DRBEM for the exterior regions is made use of for the latter problem. The differential quadrature method (DQM) is used for the spatial discretization of IBVPs and Cauchy problems defined by the nonlinear reaction-diffusion and wave equations. The DRBEM and DQM applications result in first and second order system of ordinary differential equations in time. These systems are solved with three different time integration methods, the finite difference method (FDM), the least squares method (LSM) and the finite element method (FEM) and comparisons among the methods are made. In the FDM a relaxation parameter is used to smooth the solution between the consecutive time levels. It is found that DRBEM+FEM procedure gives better accuracy for the IBVPs defined by nonlinear reaction-diffusion equation. The DRBEM+LSM procedure with exponential and rational radial basis functions is found suitable for exterior wave problem. The same result is also valid when DQM is used for space discretization instead of DRBEM for Cauchy and IBVPs defined by nonlinear reaction-diffusion and wave equations.

Cette thèse s’inscrit dans le cadre de la montée en débit des réseaux d’accès optiques passifs. Les travaux menés durant cette thèse s’appuient sur le constat que les technologies actuelles basées sur le multiplexage temporel, arriveront à leurs limites dans les années à venir et ne pourront plus répondre à l’évolution des besoins en débit. L’étude des problèmes rencontrés lors les déploiements actuels conduit à proposer une autre forme de multiplexage plus adaptée aux débits demandés par les utilisateurs : le multiplexage fréquentiel (ou FDM/FDMA). Les travaux réalisés dans cette thèse ont pour but de montrer la faisabilité d’une telle architecture en laboratoire. Les objectifs sont de déterminer les débits atteignables, que ce soit pour le lien descendant (du central vers l’abonné) ou pour le lien montant (abonnée vers central), mais également de réaliser une étude théorique afin de mettre en lumière les limites de cette solution. Des algorithmes d’allocation dynamique de ressources ont été élaborés et validés expérimentalement afin de déterminer la capacité totale de chaque lien. L’architecture utilisant deux longueurs d’ondes distinctes (une pour le lien descendant et l’autre pour le lien montant) permet d’atteindre un débit de 40 Gbps et 20 Gbps respectivement pour le lien descendant et montant en utilisant le format de multiplexage FDM/FDMA. Enfin, une architecture hybride n’employant qu’une seule longueur d’onde pour le transport à la fois les données montantes et descendantes a été explorée et permet d’atteindre un débit symétrique de 25Gbps. / This thesis is part of the growing capacity of passive optical access networks. The works done during this thesis are based on the fact that current technologies, employing time division multiplexing, will reach their limits in the coming years and will no longer respond to changes in high bitrates requirements. The study of problems encountered during the current deployments led us to propose another form of multiplexing more suitable for bitrates requested by users: the FDM/FDMA PON, frequency division multiplexing. The work done in this thesis aim to demonstrate the feasibility of a such architecture in the laboratory. The objectives are to determine the achievable capacity, whether for the downlink (from central office to user) or the uplink (subscriber to central), but also to achieve a theoretical study to highlight the limitations of this solution. Algorithms for dynamic allocation of resources have been developed and validated experimentally to determine the total capacity of each link. The architecture using two distinct wavelengths (one for the downlink and one for the uplink) achieves a capacity of 40Gbps for the downlink and 20Gbps for the uplink by using FDM/FDMA PON. Finally, a hybrid architecture using a single wavelength to transport both uplink and downlink data has been explored and achieves a symmetrical capacity of 25Gbps

The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.

The presented thesis deals with FDM 3D printing method with emphasis on printing carbon fiber reinforced plastic (CFRP). The aim of this thesis is to engineer the FDM 3D printer designed for printing CFRP and to execute the experiment targeted on comparison of CFRP material properties against commonly used 3D printing plastics such as PLA, ABS, PET etc. The device designed in this work has printing area of 200 x 200 mm with maximum height of the object of 200 mm. The printing bed is heated and the whole device is enclosed. There are two kinds of experiments carried out within the thesis. The first one is focused on tensile strength and Young's modulus of selected materials, while the second experiment compares Charpy's impact strength of specimen with different infill percentage on two selected materials, PET and PET filled with chopped carbon fiber.

This thesis deals with mechanical design of FDM 3D printer with a built-in material feeder with monitoring of remaining material. The aim of this thesis is designing the FDM 3D printer with minimum print volume of 200x200x200 mm and with usage of measured data for optimising the 3D printing process. This 3D printer is targeted to the non-experienced users, so the emphasis was on ease of use and reliability of the printer. Despite the fact that it is an innovative design solution, the suitability of the design was verified experimentally as part of this thesis. The choice of the material feeder design, which is essential for the presented thesis, was justified by the realization of prototypes of two suitable designs, from which the optimal solution was chosen. The knowledge obtained from testing the prototypes was then used for the final design of 3D printer. The usage of data for optimization of the printing process is realized by a C++ compatible source code that is a part of this thesis.

The thesis deals with the theory of 3D printing, materials for printing and bonding. It focuses on FDM printing and PLA material. It also compares gluing with other methods and deals with the distribution of adhesives, the gluing procedure and tests of glued joints. The work, based on literature studies, proposes an experiment to evaluate selected adhesives. The practical part contains a description, results and evaluation of the experiment. The evaluation of adhesives is based on tensile and shear strength.

This work describes design and realization of testing device for dynamic tests of foot prosthesis, made by methods of Rapid prototyping. Primary objective of design is to imitate the load on prosthesis during human gait. This task is accomplished by swing motion of prosthesis inside the frame of device during the loading of heel and tiptoe. Loading components can be removed and changed so the device can be used for different measurement like walking on an inclined plane. The result of this work is fully functional device including control program with many options to control the test. The result of test is to decide whether the foot prosthesis withstands the set of cyclic loads. The area of development of prosthesis by additive methods is young for the time being. It stands out especially with different materials, design, structure of prosthesis and fast process of production. Therefore this device can be used for testing of fatigue life of prosthesis made by additive methods.

The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.