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Routing Attacks are a serious threat to communication in tactical MANETs. TOGBAD is a centralised approach, using topology graphs to detect such attacks. In this paper, we present TOGBAD's newly added wormhole detection capability. It is an adaptation of a wormhole detection method developed by Hu et al. This method is based on nodes' positions. We adapted it to the specific properties of tactical environments. Furthermore, we present simulation results which show TOGBAD's performance regarding the detection of wormhole attacks.
The usage of link quality based routing metrics significantly improves the quality of the chosen paths and by that the performance of the network. But, attackers may try to exploit link qualities for their purposes. Especially in tactical multi-hop networks, routing may fall prey to an attacker. Such routing attacks are a serious threat to communication. TOGBAD is a centralised approach, using topology graphs to detect routing attacks. In this paper, we enhance TOGBAD with the capability to detect fake link qualities. We use a Challenge/Response method to estimate the link qualities in the network. Based on this, we perform plausibility checks for the link qualities propagated by the nodes in the network. Furthermore, we study the impact of attackers propagating fake link qualities and present simulation results showing TOGBAD's detection rate.
The recent explosion of available audio-visual media is the new challenge for information retrieval research. Audio speech recognition systems translate spoken content to the text domain. There is a need for searching and indexing this data which possesses no logical structure. One possible way to structure it on a high level of abstraction is by finding topic boundaries. Two unsupervised topic segmentation methods were evaluated with real-world data in the course of this work. The first one, TSF, models topic shifts as fluctuations in the similarity function of the transcript. The second one, LCSeg, approaches topic changes as places with the least overlapping lexical chains. Only LCSeg performed close to a similar real-world corpus. Other reported results could not be outperformed. Topic analysis based on the repeated word usage models renders topic changes more ambiguous than expected. This issue has more impact on the segmentation quality than the state-of-the-art ASR word error rate. It could be concluded that it is advisable to develop topic segmentation algorithms with real-world data to avoid potential biases to artificial data. Unlike evaluated approaches based on word usage analysis, methods operating with local contexts can be expected to perform better through emulation of semantic dependencies.
This study presents the findings of a quantitative study on the use of Open Educational Resources (OER) and Open Educational Practices (OEP) in Higher Education and Adult Learning Institutions. The study is based on the results of an online survey targeted at four educational roles: educational policy makers; institutional policy makers/managers; educational professionals; and learners. The report encompasses five chapters and four annexes. Chapter I presents the survey and Chapter II discloses the main research questions and models. Chapter III characterises the universe of respondents. Chapter IV advances with a detailed survey analysis including an overview of key statistical data. Finally, Chapter V provides an exploratory in-depth analysis of some key issues: representations, attitudes and uses of OEP. The table of contents and the complete list of diagrams and tables can be found at the end of the report.
In an explorative study, we investigated on German schoolteachers how they use, reuse, produce and manage Open Educational Resources. The main questions in this research have been, what their motivators and barriers are in their use of Open Educational Resources, what others can learn from their Open Educational Practices, and what we can do to raise the dissemination level of OER in schools.
This paper addresses special skills, learners in Internet-based learning scenarios need. In self-directed learning scenarios, as most Internet-based learning scenarios are designed, learners bear the responsibility for their learning progress. To ease this task, institutions could prime the learners for the situation which may be quite different to their previous learning experiences. Basing on a Delphi-study, conducted with experts from the e-Learning sector in Germany, Austria, and Switzerland, the basic requirements have been determined.
Adaptability as a Special Demand on Open Educational Resources: The Cultural Context of e-Learning
(2011)
Producing and providing Open Educational Resources (OERs) is driven by the concepts of openness and sharing. Although there already are a lot of free high-quality resources available, practitioners often rather rewrite learning resources than creatively embed (and thus, reuse) existing OERs. In this paper, we analyse the reasons for this in two different educational contexts. As a result of this analysis, we found that the uncertainty on possible adaptation needs is one of the major barriers. In order to overcome this barrier and make different learning contexts comparable, we analysed the context of learners and in particular, in the research project ‘Learning Culture’, we investigated the field of culturally motivated expectations and attitudes of learners. This paper shows the results of this research project and discusses which cultural issues should be taken into consideration when OERs are to be adapted from one to another cultural context.
In Anlehnung an die von Leidner und Kayworth (2006) durchgeführte Studie zum Umgang mit Kultur in der angelsächsischen Wissenschaftsdisziplin „Information Systems“ wurde eine entsprechende Literaturstudie für die gestaltungsorientierte Wirtschaftsinformatik des deutschen Sprachraums durchgeführt. In der Studie wurde in den Hauptorganen der Disziplin untersucht, in welcher Häufigkeit kulturelle Einflüsse auf Informationstechnologie thematisiert wurden, wie diese Einflüsse aufgearbeitet wurden und welche Referenzmodel-le/Referenzliteratur verwendet wurden. Nach einer kurzen Darstellung der gewählten Vorgehensweise werden die Ergebnisse und Beschränkungen der Studie präsentiert.
The roadmap for quality and innovation through open educational practices has been conceived as a number of steps, a conceptual document, which can be used by organisations, leaners or professionals in order to improve their open educational practices. After the development of the core concept of the OPAL project, the guidelines for OEP, it became clear that these guidelines, would have to play an important part on the roadmap exercise, because they represent the very essence of how to foster and stimulate open educational practices. The roadmap therefore is meant to be an instrument, a tool which helps the different stakeholders to use the guidelines for their own context and purpose.
This paper picks up on one of the ways reported in the literature to represent hybrid models of engineering systems by bond graphs with static causalities. The representation of a switching device by means of a modulated transformer (MTF) controlled by a Boolean variable in conjunction with a resistor has been used so far to build a model for simulation. In this paper, it is shown that it can also constitute an approach to bond graph based quantitative fault detection and isolation in hybrid system models. Advantages are that Analytical Redundancy Relations (ARRs) do not need to be derived again after a switch state has changed. ARRs obtained from the bond graph are valid for all system modes. Furthermore, no adaption of the standard sequential causality assignment procedure (SCAP) with respect to fault detection and isolation (FDI) is needed.
This report presents an approach on a quadrotor dynamics stabilization based on ICP SLAM. Because the quadrotor lacks sensory information to detect its horizontal drift an additional sensor as Hokuyo-UTM has been used to perform on-line ICP-based SLAM. The obtained position estimates were used in control loops to maintain desired position and orientation of the vehicle. Such attitude parameters as height, yaw and position in space were controlled based on the laser data. As a result the quadrotor demonstrated two significant for autonomous navigation capabilities: performance of on-line SLAMon a flying vehicle and maintaining desired position in 3D space. Visual approach on optical flow based on Pyramid Lucas-Kanade algorithm has been touched and tested in different environmental conditions though hasn't been implemented in the control loop. Also the performance of the Hokuyo laser scanner and the related to it ICP SLAM algorithm have been tested in different environmental conditions indoors, outdoors and in presence of smoke. Results are presented and discussed. The requirement of performing on-line SLAM algorithm and to carry quite heavy equipment for it forced to seek a solution to increase the payload of the quadrotor with its computational power. A new hardware and distributed software architectures are therefore presented in the report.
The smart home of the future is typically researched in lab settings or apartments that have been built from scratch. However, comparing the lifecycle of buildings and information technology, it is evident that modernization strategies and technologies are needed to empower residents to modify and extend their homes to make it smarter. In this paper, we describe a case study about the deployment, adaption to and adoption of tailorable home energy management systems in 7 private households. Based on this experience, we want to discuss how hardware and software technologies should be designed so that people could build their own smart home with a high usability and user experience.
The work done in this thesis enhances the MMD algorithm in multi-core environments. The MMD algorithm, a transformation based algorithm for reversible logic synthesis, is based on the works introduced by Maslov, Miller and Dueck and their original, sequential implementation. It synthesises a formal function specification, provided by a truth table, into a reversible network and is able to perform several optimization steps after the synthesis. This work concentrates on one of these optimization steps, the template matching. This approach is used to reduce the size of the reversible circuit by replacing a number of gates that match a template which implements the same function and uses less gates. Smaller circuits have several benefits since they need less area and are not as costly. The template matching approach introduced in the original works is computationally expensive since it tries to match a library of templates against the given circuit. For each template at each position in the circuit, a number of different combinations have to be calculated during runtime resulting in high execution times, especially for large circuits. In order to make the template matching approach more efficient and usable, it has been reimplemented in order to take advantage of modern multi-core architectures such as the Cell Broadband Engine or a Graphics Processing Unit. For this work, two algorithmically different approaches that try to consider each multi-core architecture’s strengths, have been analyzed and improved. For the analysis these approaches have been cross-implemented on the two target hardware architectures and compared to the original parallel versions. Important metrics for this analysis are the execution time of the algorithm and the result of the minimization with the template matching approach. It could be shown that the algorithmically different approaches produce the same minimization results, independent of the used hardware architecture. However, both cross-implementations also show a significantly higher execution time which makes them practically irrelevant. The results of the first analysis and comparison lead to the decision to enhance only the original parallel approaches. Using the same metrics for successful enhancements as mentioned above, it could be shown that improving the algorithmic concepts and exploiting the capabilities of the hardware lead to better results for the execution time and the minimization results compared to their original implementations.
Incremental Bond Graphs
(2011)
Bond Graph Modelling of Engineering Systems: Theory, Applications and Software Support addresses readers to consider the potential and the state-of-the-art of bond graph modeling of engineering systems with respect to theory, applications and software support. Bond graph modelling is a physical modelling methodology based on first principles that is particularly suited for modelling multidisciplinary or mechatronic systems. This book covers theoretical issues and methodology topics that have been subject of ongoing research during past years, presents new promising applications such as the bond graph modeling of fuel cells and illustrates how bond graph modeling and simulation of mechatronic systems can be supported by software. This up-to-date comprehensive presentation of various topics has been made possible by the cooperation of a group of authors who are experts in various fields and share the “bond graph way of thinking.”
At present, data publication is one of the most dynamic topics in e-Research. While the fundamental problems of electronic text publication have been solved in the past decade, standards for the external and internal organisation of data repositories are advanced in some research disciplines but underdeveloped in others. We discuss the differences between an electronic text publication and a data publication and the challenges that result from these differences for the data publication process. We place the data publication process in the context of the human knowledge spiral and discuss key factors for the successful acquisition of research data from the point of view of a data repository. For the relevant activities of the publication process, we list some of the measures and best practices of successful data repositories.
In the past decade computer models have become very popular in the field of biomechanics due to exponentially increasing computer power. Biomechanical computer models can roughly be subdivided into two groups: multi-body models and numerical models. The theoretical aspects of both modelling strategies will be introduced. However, the focus of this chapter lies on demonstrating the power and versatility of computer models in the field of biomechanics by presenting sophisticated finite element models of human body parts. Special attention is paid to explain the setup of individual models using medical scan data. In order to reach the goal of individualising the model a chain of tools including medical imaging, image acquisition and processing, mesh generation, material modelling and finite element simulation –possibly on parallel computer architectures- becomes necessary. The basic concepts of these tools are described and application results are presented. The chapter ends with a short outlook into the future of computer biomechanics.