A Mobile Ad hoc Network (MANET) is typically a set of wireless mobile nodes enabled to communicate dynamically in a multi-hop manner without any pre-existing network infrastructure. MANETs have several unique characteristics in contrast to other typical networks, such as dynamic topology, intermittent connectivity, limited resources, and lack of physical security. Securing MANETs is a critical issue as these are vulnerable to many different attacks and failures and have no clear line of defence. To develop effective security services in MANETs, it is important to consider an appropriate trust infrastructure which is tailored to a given MANET and associated application. However, most of the proposed trust infrastructures do not to take the MANET application context into account. This may result in overly secure MANETs that incur an increase in performance and communication overheads due to possible unnecessary security measures. Designing and evaluating trust infrastructures for MANETs is very challenging. This stems from several pivotal overlapping aspects such as MANET constraints, application settings and performance. Also, there is a lack of practical approaches for assessing security in MANETs that take into account most of these aspects. Based on this, this thesis provides a methodological approach which consists of well-structured stages that allows the exploration of possible security alternatives and evaluates these alternatives against dimensions to selecting the best option. These dimensions include the operational level, security strength, performance, MANET contexts along with main security components in a form of a multidimensional security conceptual framework. The methodology describes interdependencies among these dimensions, focusing specifically on the service operational level in the network. To explore these different possibilities, the Server-based Security Architectures for MANETs (SSAM) simulation model has been created in the OMNeT++ simulation language. The thesis describes the conceptualisation, implementation, verification and validation of SSAM, as well as experimentation approaches that use SSAM to support the methodology of this thesis. In addition, three different real cases scenarios (academic, emergency and military domains) are incorporated in this study to substantiate the feasibility of the proposed methodology. The outcome of this approach provides MANET developers with a strategy along with guidelines of how to consider the appropriate security infrastructure that satisfies the settings and requirements of given MANET context.

This thesis concerns the changing predispositions and conditions for contemporary meaning-making in school education. From a socio-cultural perspective, multimodal theory formation is used to find suitable tools and concepts for developing teaching and learning. The overall aims are to investigate and conceptualize meaning-making in school in the frame ofmultimodal theory. Firstly, the research questions are concerned with how teachers work with written; paper-based, expository texts, and secondly, with students' meaning-making, working with meaning-offerings from different modes and media. This is followed by questions surrounding the predispositions for a multimodal view in the Swedish curriculum outline. Finally, the consequences for the role of fiction in education, using multimodal theory formation as a framework are addressed. The thesis presents two empirical studies which investigate meaning-making in upper secondary education, followed by critical discussions of the cmTiculum outline and the role of fiction. The empirical data was collected using methods inspired by ethnography in classes taking social sciences and media courses. The analyses were inspired by multimodal research, and the main analytical tools consist of a discourse framework and model inspired by Roz IvaniC, the Leaming Design Sequence developed by Staffon Selander, the wheel of multimodality and the pedagogy of multiliteracies, both developed by the New London Group and Bill Cope and :Mary Kalantzis. The first study focuses on the teachers' perspective in trying to develop students' meaning-making through written, paper-based expository texts. Analyses within the discourse framework and design layer model are used to describe the teachers' practical theory. The wheel ofmultimodality is used to differentiate the meaning-offerings used in class, and the pedagogy of multiliteracies is used to describe and analyze the discussions in groups and with the teacher. Results highlight three major possibilities for working with written, paper-based expository texts: a vvider view on meaning-making, meaning-offerings encompassing several modes and media, and the teacher's modeling ofthe reading through discussion. The second study describes and analyzes meaning-making and design in learning \vith meaning-offerings from different modes and media from the students' perspective. The analytical tools are the wheel of multimodality, the Learning Design Sequence and the further-developed pedagogy of multiliteracies. Results show a similarity in meaning-making regardless of mode and media, staiiing with the visual mode and with the students focusing their efforts on comprehending the meaning-offering. This can be explained by lack of clarity and lack of guidance which are seen as obstacles for learning. The discussions surrounding the curriculum outline and the role of fiction show that, in using a multimodal theory formation frame, the curriculum does not explicitly support a multimodal view on meaning-making and that fiction can not be seen as unique due to neither mode nor media. The results suggest that multimodal theory formation gives access to tools that are useful in developing students' meaning-making according to the predispositions and conditions oftoday, in which reading development is viewed as part of developing meaning-making as a who lei and that meaning-making in school should be based on a non-hierarchical and inclusive view on modes and media to create a readiness and a flexibility to meet demands of a rapidly-changing society. As a consequence, the curriculum outline needs to be reworded and the role of fiction in education needs to be problematized.