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Even with the advent of efficient, faster computers, researchers are often forced to scale down some of their problems, or pay a high price on huge computer resources for solving them. This has led to an intense effort directed towards developing efficient and rapid analysis procedures. This scenario is also true for many research-oriented finite element codes which have a limited element library or have a problem-size limit because of the use of a memory-resident equation solver. This study focuses on the development of a simple and accurate global/local method for calculating the static response of simply-supported, laminated composite panels, with cutouts and cracks. The approach primarily involves two steps. In the first step a global approach, the Rayleigh-Ritz method, is used to calculate the response of the structure. Displacement based Ritz functions for the plate without the cutout are augmented with a perturbation function. which is accurate for uniform thickness isotropic plates only, to account for the cutout. The Ritz solution does not accurately satisfy the natural boundary conditions at the cutout boundary. Therefore, a second step, local in nature is taken in which a small area in the vicinity of the hole and encompassing other points of singularities is discretized using a fine finite element mesh. The displacement boundary conditions for the local region are obtained from the global Ritz analysis. The chosen perturbation function is reliable only for circular cutout in uniform plates, therefore elliptical cutouts were suitably transformed to circular shapes using conformal mapping. Cracks are modeled as elliptical cutouts with high aspect ratios. The methodology is also extended to the analysis of composite plates. Composite structures have very high structural efficiency due to the high values of stiffness and fiber strength. But the design and analysis of composite structures is much more complicated than that of metallic structures because of the presence of highly directional properties which induces anisotropy in the mechanical characteristics and lead to a myriad of failure modes. Behavior of these structures in the presence of various discontinuities, particularly cutouts and cracks. could be even more complicated. Global/local analysis of composites with cracks and cutouts proved to be very useful and more efficient. The proposed approach resulted in considerable savings in both computational times and data storage without sacrificing the accuracy in the prediction of stresses. Results are compared with adaptive meshing technique, and it is seen that global/local analysis performed equally well. The method is very useful in design and optimization where a large number of analyses have to be performed. / Ph. D.

A global/local framework for multidisciplinary optimization of generalized aircraft wing structure has been developed. The concept of curvilinear stiffening members (spars, ribs and stiffeners) has been applied in the optimization of a wing structure. A global wing optimization framework EBF3WingOpt, which integrates the static aeroelastic, flutter and buckling analysis, has been implemented for exploiting the optimal design at the wing level. The wing internal structure is optimized using curvilinear spars and ribs (SpaRibs). A two-step optimization approach, which consists of topology optimization with shape design variables and size optimization with thickness design variables, is implemented in EBF3WingOpt. A local panel optimization EBF3PanelOpt, which includes stress and buckling evaluation criteria, is performed to optimize the local panels bordered by spars and ribs for further structural weight saving. The local panel model is extracted from the global finite element model. The boundary conditions are defined on the edges of local panels using the displacement fields obtained from the global model analysis. The local panels are optimized to satisfy stress and buckling constraints. Stiffened panel with curvilinear stiffeners is implemented in EBF3PanelOpt to improve the buckling resistance of the local panels. The optimization of stiffened panels has been studied and integrated in the local panel optimization. EBF3WingOpt has been applied for the optimization of the wing structure of the Boeing N+2 supersonic transport wing and NASA common research model (CRM). The optimization results have shown the advantage of curvilinear spars and ribs concept. The local panel optimization EBF3PanelOpt is performed for the NASA CRM wing. The global-local optimization framework EBF3GLWingOpt, which incorporates global wing optimization module EBF3WingOpt and local panel optimization module EBF3PanelOpt, is developed using MATLAB and Python programming to integrate several commercial software: MSC.PATRAN for pre and post processing, MSC.NASTRAN for finite element analysis. An approximate optimization method is developed for the stiffened panel optimization so as to reduce the computational cost. The integrated global-local optimization approach has been applied to subsonic NASA common research model (CRM) wing which proves the methodology's application scaling with medium fidelity FEM analysis. Both the global wing design variables and local panel design variables are optimized to minimize the wing weight at an acceptable computational cost. / Ph. D.

The aim of this thesis is to demonstrate how music has become a significant means of communication in the process of globalization, and how it integrates the &lsquo / global&rsquo / and the &lsquo / local&rsquo / while enabling the aggrieved populations to speak through and to express their antagonistic stances. In addition to the discussions of globalization, this study analyzes the medium of music along the areas of media and identity politics. In this respect, it deliberates on the global and local features of hip-hop. Although born in the ghettos of Bronx, New York, this global youth culture has been adopted by other minority youths in order to voice their anger and frustration towards the exclusionist practices of the state, as well as racism and discrimination they face in their host countries. Accordingly, the second and third generation Turkish youths in Germany and South Asian youths in Britain have revealed their rage through the subversive lyrics they employed. Therefore, these lyrics can also be regarded as narratives that indicate these immigrant youths as representatives of resistance and defiance. Despite the fact that the musical works of these minority youths may be considered a product of the &lsquo / culture industry&rsquo / , this does not eliminate their resistive and subversive characteristics.

This research work has contributed in various ways to help develop a better understanding of textile composites and materials with complex microstructures in general. An instrumental part of this work was the development of an object-oriented framework that made it convenient to perform multiscale/multiphysics analyses of advanced materials with complex microstructures such as textile composites. In addition to the studies conducted in this work, this framework lays the groundwork for continued research of these materials. This framework enabled a detailed multiscale stress analysis of a woven DCB specimen that revealed the effect of the complex microstructure on the stress and strain energy release rate distribution along the crack front. In addition to implementing an oxidation model, the framework was also used to implement strategies that expedited the simulation of oxidation in textile composites so that it would take only a few hours. The simulation showed that the tow architecture played a significant role in the oxidation behavior in textile composites. Finally, a coupled diffusion/oxidation and damage progression analysis was implemented that was used to study the mechanical behavior of textile composites under mechanical loading as well as oxidation. A parametric study was performed to determine the effect of material properties and the number of plies in the laminate on its mechanical behavior. The analyses indicated a significant effect of the tow architecture and other parameters on the damage progression in the laminates.

We assess the relationship between model size and complexity in the time-varying parameter VAR framework via thorough predictive exercises for the Euro Area, the United Kingdom and the United States. It turns out that sophisticated dynamics through drifting coefficients are important in small data sets while simpler models tend to perform better in sizeable data sets. To combine best of both worlds, novel shrinkage priors help to mitigate the curse of dimensionality, resulting in competitive forecasts for all scenarios considered. Furthermore, we discuss dynamic model selection to improve upon the best performing individual model for each point in time. / Series: Department of Economics Working Paper Series

A well-known result in spectral graph theory states that if a graph has an equitable partition then the eigenvalues of the associated divisor graph are a subset of the graph's eigenvalues. A natural question question is whether it is possible to recover the remaining eigenvalues of the graph. Here we show that if a graph has a Hermitian adjacency matrix then the spectrum of the graph can be decomposed into a collection of smaller graphs whose eigenvalues are collectively the remaining eigenvalues of the graph. This we refer to as a complete equitable decomposition of the graph.

An ensemble representation refers to a statistical summary representation of a group of similar objects. Recent work has shown that we can form multiple ensemble representations – ensemble representations for a single feature dimension across multiple stimulus groups, ensemble representations for multiple feature dimensions in the same stimulus group, and ensemble representations across multiple sensory domains. In our study, we use hierarchical stimuli based on the Navon figures (Navon 1977) to study properties of ensemble representations across multiple spatial scales. In Experiments 1 and 3, we study properties of ensemble representations for the orientation and size feature dimension, respectively. In Experiment 2, we study properties of individual representations for the orientation feature dimension. Results indicate that it is possible to form ensemble representations across multiple spatial scales. Experiment 1 shows that the global ensemble representations may be extracted automatically (without intent) whereas the local ensemble representation is only extracted in response to task demands (with intent). Finally, in both Experiment 1 and Experiment 3, participants were more accurate at reporting the global ensemble representation than the local ensemble representation whereas in Experiment 2, performance did not differ across the levels. These results point towards global precedence in the formation of ensemble representations.

<p>The aim of this thesis is to describe and understand the introduction of entrepreneurship and enterprise projects in primary and secondary schools in the North of Sweden and to identify and analyse the driving forces and actors behind this process. In particular the influence and significance of education policy at supranational, national and subnational level for the introduction of entrepreneurship and enterprise in education are analysed. The main questions of the study have been:</p><p>• How and why have entrepreneurship and enterprise education come to the schools in the northern region of Sweden, in particular within the framework of the PRIO1 project?</p><p>• How were important stakeholders involved at the subnational level and how did they reason and act in relation to the introduction of entrepreneurship and enterprise in the schools?</p><p>• How are the concepts of entrepreneurship and enterprise education presented in policy documents at different policy levels?</p><p>The study wants to report on changes in education policy during recent years. Especially the emergence of international policy convergence and new forms of governance are among the factors that are considered. Drawing on a conceptual framework of structure and agency, the analyses in the empirical studies are informed by a combination of theoretical fields. Important contributions are rendered from the education policy literature. The first method consists of a policy study of documents produced by organisations at different levels (supranational, national and subnational). The purpose of this analysis is to capture the ideas and arguments that have been used but also to understand the context and driving forces for the introduction of entrepreneurship and enterprise in education. Starting from the supranational level, the analysis focuses mainly on two organisations, OECD and EU. These organisations were chosen because they are widely regarded as leading organisations in setting the supranational policy agenda for education. The document study consists of a selection of OECD documents that have been released during the period 1970 - 2006, as well as a selection of EU documents. The EU documents cover the last 15 years. Attention is paid to several documents at the national and subnational level as well. The second method is an interview study. The interview study aims to focus on some of the key stakeholders (agents/actors) that have been participating in the formation (initiation, financing and realisation) of a county wide project “PRIO1”, Priority Enterprise in Västerbotten, in the North of Sweden. In order to understand why and how these actors at the subnational level have become involved in the process, there exists a need to hear their arguments. The document study shows that there is interplay between the different levels, but intertextual aspects have also become visible. The policy drive and policy scope show the concatenation but also the complexity of the policy development. Education is increasingly related to economic policies, in particular through labour market policies. Although the concepts of Entrepreneurship and Enterprise have developed within the economic sector, they are penetrating the education and training systems of many countries. From the results presented in this study, it seems that lifelong learning has become the guiding principle for the amalgamation of education and the world of work, while learning is no longer equated with just schooling. The opening of the school towards the surrounding world is a characteristic development in all this, but it is also a process that certainly is stipulated by agencies and actors at different levels, as is shown in this study. The interviews with some stakeholders at the subnational level show that the promotion of entrepreneurship and enterprise in education is related to arguments for economic and societal development. The interviews also reveal some of the “bottom-up” aspects of the policy process. One of the important results of this study is that the education policy studies have to include the level beyond the national borders. The interplay between the different policy-levels (supranational, national and subnational) needs more attention in order to understand the transformation of the education system.</p>