138,279 research outputs found

    Target Tracking in Confined Environments with Uncertain Sensor Positions

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    To ensure safety in confined environments such as mines or subway tunnels, a (wireless) sensor network can be deployed to monitor various environmental conditions. One of its most important applications is to track personnel, mobile equipment and vehicles. However, the state-of-the-art algorithms assume that the positions of the sensors are perfectly known, which is not necessarily true due to imprecise placement and/or dropping of sensors. Therefore, we propose an automatic approach for simultaneous refinement of sensors' positions and target tracking. We divide the considered area in a finite number of cells, define dynamic and measurement models, and apply a discrete variant of belief propagation which can efficiently solve this high-dimensional problem, and handle all non-Gaussian uncertainties expected in this kind of environments. Finally, we use ray-tracing simulation to generate an artificial mine-like environment and generate synthetic measurement data. According to our extensive simulation study, the proposed approach performs significantly better than standard Bayesian target tracking and localization algorithms, and provides robustness against outliers.Comment: IEEE Transactions on Vehicular Technology, 201

    Power Modelling for Heterogeneous Cloud-Edge Data Centers

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    Existing power modelling research focuses not on the method used for developing models but rather on the model itself. This paper aims to develop a method for deploying power models on emerging processors that will be used, for example, in cloud-edge data centers. Our research first develops a hardware counter selection method that appropriately selects counters most correlated to power on ARM and Intel processors. Then, we propose a two stage power model that works across multiple architectures. The key results are: (i) the automated hardware performance counter selection method achieves comparable selection to the manual selection methods reported in literature, and (ii) the two stage power model can predict dynamic power more accurately on both ARM and Intel processors when compared to classic power models.Comment: 10 pages,10 figures,conferenc

    Reliable scientific service compositions

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    Abstract. Distributed service oriented architectures (SOAs) are increas-ingly used by users, who are insufficiently skilled in the art of distributed system programming. A good example are computational scientists who build large-scale distributed systems using service-oriented Grid comput-ing infrastructures. Computational scientists use these infrastructure to build scientific applications, which are composed from basic Web ser-vices into larger orchestrations using workflow languages, such as the Business Process Execution Language. For these users reliability of the infrastructure is of significant importance and that has to be provided in the presence of hardware or operational failures. The primitives avail-able to achieve such reliability currently leave much to be desired by users who do not necessarily have a strong education in distributed sys-tem construction. We characterise scientific service compositions and the environment they operate in by introducing the notion of global scien-tific BPEL workflows. We outline the threats to the reliability of such workflows and discuss the limited support that available specifications and mechanisms provide to achieve reliability. Furthermore, we propose a line of research to address the identified issues by investigating auto-nomic mechanisms that assist computational scientists in building, exe-cuting and maintaining reliable workflows.

    Analysis domain model for shared virtual environments

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    The field of shared virtual environments, which also encompasses online games and social 3D environments, has a system landscape consisting of multiple solutions that share great functional overlap. However, there is little system interoperability between the different solutions. A shared virtual environment has an associated problem domain that is highly complex raising difficult challenges to the development process, starting with the architectural design of the underlying system. This paper has two main contributions. The first contribution is a broad domain analysis of shared virtual environments, which enables developers to have a better understanding of the whole rather than the part(s). The second contribution is a reference domain model for discussing and describing solutions - the Analysis Domain Model

    Accurate high-speed urban field strength predictions using a new hybrid statistical/deterministic modelling technique

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    Measured pedestrian movement and bodyworn terminal effects for the indoor channel at 5.2 GHz

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    [Summary]: Human body effects such as antenna-body interaction and scattering caused by pedestrian movement are important indoor radio propagation phenomena at microwave frequencies. This paper reports measurements and statistical analysis of the indoor narrowband propagation channel at 5.2 GHz for two scenarios: a fixed line-of-sight (LOS) link perturbed by pedestrian movement and a mobile link incorporating a moving bodyworn terminal. Two indoor environments were considered for both types of measurements: an 18 m long corridor and a 42 m2 office. The fixed-link results show that the statistical distribution of the received envelope was dependent on the number of pedestrians present. However, fading was slower than expected, with an average fade duration of more than 100 ms for a Doppler frequency of 8.67 Hz. For the bodyworn terminal, mean received power values were dependent on whether or not the user's body obstructed the LOS. For example, in the corridor the average non-line-of-sight (NLOS) pathloss was 5.4 dB greater than with LO
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