The thesis focuses on transport infrastructure in the Czech republic. Its aiming at road, railway and combined infrastucture.It analyzes its current situation and short historical development. There is analysis focused on the density of infrastructure in european conditions and national regions in Czech Rep. Further, it analyzes the transport overload on chosen roads. Sugested solution is to move the road freigth to railway through combined transportation. Cost savings coming from lower reconstruction costs are calculated as well. In the end, there is proposal about implementation of combined transport in the region as a regional logistic center.

Nesta dissertação apresenta-se a análise de métodos totalmente discretos, estabilizados espacialmente, para a resolução de problemas de transporte unidimensionais convectivos-difusivos-reativos, lineares e transientes que modelam o transporte de contaminantes radioativos com decaimento a uma taxa constante em um meio poroso saturado. O método de elementos finitos clássico de Galerkin é usado no espaço quando o problema de transporte é pura e/ou predominantemente difusivo, ao passo que quando a convecção domina, o método SUPG (Streamline Upwind Petrov-Galerkin) é utilizado. O método de elementos finitos é combinado a um esquema discreto de integração no tempo, os algoritmos trapezoidais generalizados. Observa-se que a solução aproximada pode apresentar oscilações espúrias quando o método de Crank-Nicolson é utilizado. São consideradas diversas metodologias propostas na literatura para amortecer tais oscilações. Como consequência da análise de estabilidade desenvolvida, uma nova condição de estabilidade é proposta. / This work deals with the stability analysis of the fully discrete transport problem obtained using a stable finite element method in space and the generalized trapeizoidal family of methods in time. Depeding on the range of parameters the Galerkin and the Streamline Upwind Petrov-Galerkin Methods are introduced. We evaluate the accuracy and stability properties of the methods. The sawtooth pattern in time is observed,caused by spurious higher modes when Crank-Nicolson method is used. We derive a stability analysis of the fully discrete method and investigate the techniques proposed in literature to damp oscillations. We propose a new stability condition to overcome the spurious modes. The proposed methodology is apllied to a one-dimensional contaminant transport problems in a saturated porous media that considers a radioactive contaminant decay at a constant rate.

The origin of the Mixed Glass Former Effect (MGFE) is studied, which manifests itself in a non-monotonic behavior of the activation energy for long-range ion transport as a function of the mixing ratio of two glass formers. Two theoretical models are developed, the mixed barrier model and the network unit trap model, which consider different possible mechanisms for the occurrence of the MGFE. The mixed barrier model is based on the assumption that energy barriers are reduced for ionic jumps in regions of mixed composition. By employing percolation theory it is shown that this mechanism can successfully account for the behavior of the activation energy in various ion conducting mixed glass former glasses. The network unit trap model is based on the fact that a variety of network forming units, the so-called Q(n) species, can be associated with one glass former. Using a thermodynamic approach, the change of the concentration of these units in dependence of ionic concentration and the glass former mixing ratio is successfully predicted for alkali borate, phosphate and borophosphate glasses. In a second step, the charge distribution of the various units is considered and related to it, the binding energies to alkali ions. This gives rise to a modeling of the ionic transport in an energy landscape that changes in a defined manner with the glass former mixing ratio. Kinetic Monte Carlo simulations for alkali borophosphate glasses, which serve as a representative system for the MGFE in the literature, demonstrate that this approach succeeds to predict the behavior of the activation energy. In a further part of the thesis, Reverse Monte Carlo (RMC) simulations for the atomic structure of sodium borophosphate glasses are carried out with X-ray and neutron diffraction data as further input from experiments. Three-dimensional structures could be successfully generated that are in agreement with all experimental and theoretical constraints. Volume fractions of the ionic conduction pathways determined from these structures, however, do not show a substantial relationship to the activation energy, as earlier proposed in the iterature for alkali borate and alkali phosphate glasses.