The deployment of renewable energy (RE) technologies for electricity generation is a central element of the European energy and climate strategy and was laid down in binding targets on EU-level. The actual RE technology diffusion is, however, shaped by the framework conditions and support measures implemented in the individual EU Member States. This dissertation aims at contributing to a more integrated view of the influencing factors (determinants) for the deployment of RE technologies. To this end, a conceptual framework is drawn up to assess the boundary conditions for RE diffusion from the RE developer’s perspective. The framework is operationalised using a composite indicator (CI) approach and applied in a diffusion model to allow the anticipation of possible future technology deployment. The thesis concentrates on two mainstream RE technologies, namely onshore wind and non-residential PV, and focuses on European countries. Within the analysis, particular emphasis is placed on providing a holistic assessment of the impact of economic and non-economic determinants on the diffusion of RE technologies at national level. The assessment aims at understanding RE developers’ preferences and rationalities regarding the overall framework conditions for RE deployment in order to identify the drivers for and barriers to technological change and to facilitate efficient policy design and regulatory transformation. The most relevant diffusion determinants from the viewpoint of RE project developers are identified through literature research and moderated expert workshops. The relative relevance of the determinants in the diffusion process is then assessed based on an EU-wide questionnaire that resulted in the collection of >200 datasets. Building on this broad empirical basis, a composite indicator (CI) is developed for the diffusion of non-residential PV and wind onshore. The CI provides a transparent framework for the quantification of the diffusion determinants and allows an evaluation and benchmarking of national RE frameworks. In a further step, the CI is integrated in a diffusion model which enables projections of possible future market developments under different configurations of the national RE framework. This modelling approach applies and further develops established logistic models of technology diffusion. The overall approach is validated by applying it to three case study countries: Germany, Spain and the United Kingdom. Data collection in these case study countries involved, among others, semi-structured interviews with 31 RE experts. The different regulatory framework conditions in the three countries lead to 3 different CI results and projected technology diffusion. The results verify the robustness of the approach and the applicability of the concept to different national contexts. The findings of this thesis contribute to the methodological and empirical basis for understanding and modelling technology diffusion processes in general and RE technology diffusion in particular. The approach developed in this thesis further improves the scientific basis for the evaluation of RE support policies and can contribute to RE targets being achieved in an efficient and sustainable way.

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With the increasing use of composite materials for diverse applications ranging from civil infrastructure to offshore oil exploration, the durability of these materials is an important issue. Practical and accurate models for lifetime will enable engineers to push the boundaries of design and make the most efficient use of composite materials, while at the same time maintaining the utmost standards of safety. The work described in this dissertation is an effort to predict the strength and rupture lifetime of a unidirectional carbon fiber/polymer matrix composite using micromechanical techniques. Sources of material variability are incorporated into these models to predict probabilistic distributions for strength and lifetime. This approach is best suited to calculate material reliability for a desired lifetime under a given set of external conditions. A systematic procedure, with experimental verification at each important step, is followed to develop the predictive models in this dissertation. The work begins with an experimental and theoretical understanding of micromechanical stress redistribution due to fiber fractures in unidirectional composite materials. In-situ measurements of fiber stress redistribution are made in macromodel composites where the fibers are large enough that strain gages can be mounted directly onto the fibers. The measurements are used to justify and develop a new form of load sharing where the load of the broken fiber is redistributed only onto the nearest adjacent neighbors. The experimentally verified quasi-static load sharing is incorporated into a Monte Carlo simulation for tensile strength modeling. Very good agreement is shown between the predicted and experimental strength distribution of a unidirectional composite. For the stress-rupture models a time and temperature dependent load-sharing analysis is developed to compute stresses due an arbitrary sequence of fiber fractures. The load sharing is incorporated into a simulation for stress rupture lifetime. The model can be used to help understand and predict the role of temperature in accelerated measurement of stress-rupture lifetimes. It is suggested that damage in the gripped section of purely unidirectional specimens often leads to inaccurate measurements of rupture lifetime. Hence, rupture lifetimes are measured for [90/0_3]_s carbon fiber/polymer matrix specimens where surface 90 deg plies protect the 0 deg plies from damage. Encouraging comparisons are made between the experimental and predicted lifetimes of the [90/0_3]_s laminate. Finally, it is shown that the strength-life equal rank assumption is erroneous because of fundamental differences between quasi-static and stress-rupture failure behaviors in unidirectional polymer composites. / Ph. D.

The scope of thesis is to design a curved arch footbridge. The main structure consists of composite deck supported by steel arch. The focus is on finding optimal shape of arch and proper cross-sections of elements. Bridge is analysed according to limit states.