161 research outputs found

    Video adaptation using the Variation Factory

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    Abstract-Video adaptation is an active research area aiming at delivering heterogeneous content to yet heterogeneous devices under different network conditions. This paper presents an architecture for generating variations (different versions) from an MPEG-4 source video to be used during adaptation. Different products are defined and the Variation Factory is introduced. It generates different versions of the source and an MPEG-7 metadata document. The information contained in the metadata document helps the system to identify the most appropriate version that meets the required Quality of Service (QoS). In addition to the implementation of the commonly used reduction methods, two novel methods, viz. object-based and segmentbased variations are introduced. Our proposals are implemented and experimentally validated

    MPI Phantom Study with A High-Performing Multicore Tracer Made by Coprecipitation

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    Magnetic particle imaging (MPI) is a new imaging technique that detects the spatial distribution of magnetic nanoparticles (MNP) with the option of high temporal resolution. MPI relies on particular MNP as tracers with tailored characteristics for improvement of sensitivity and image resolution. For this reason, we developed optimized multicore particles (MCP 3) made by coprecipitation via synthesis of green rust and subsequent oxidation to iron oxide cores consisting of a magnetite/maghemite mixed phase. MCP 3 shows high saturation magnetization close to that of bulk maghemite and provides excellent magnetic particle spectroscopy properties which are superior to Resovist® and any other up to now published MPI tracers made by coprecipitation. To evaluate the MPI characteristics of MCP 3 two kinds of tube phantoms were prepared and investigated to assess sensitivity, spatial resolution, artifact severity, and selectivity. Resovist® was used as standard of comparison. For image reconstruction, the regularization factor was optimized, and the resulting images were investigated in terms of quantifying of volumes and iron content. Our results demonstrate the superiority of MCP 3 over Resovist® for all investigated MPI characteristics and suggest that MCP 3 is promising for future experimental in vivo studies

    Bi-criteria Pipeline Mappings for Parallel Image Processing

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    Mapping workflow applications onto parallel platforms is a challenging problem, even for simple application patterns such as pipeline graphs. Several antagonistic criteria should be optimized, such as throughput and latency (or a combination). Typical applications include digital image processing, where images are processed in steady-state mode. In this paper, we study the mapping of a particular image processing application, the JPEG encoding. Mapping pipelined JPEG encoding onto parallel platforms is useful for instance for encoding Motion JPEG images. As the bi-criteria mapping problem is NP-complete, we concentrate on the evaluation and performance of polynomial heuristics

    Design and implementation of the fast send protocol

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    Over the last decades Internet traffic has grown dramatically. Besides the number of transfers, data sizes have risen as well. Traditional transfer protocols do not adapt to this evolution. Large-scale computational applications running on expensive parallel computers produce large amounts of data which often have to be transferred to weaker machines at the clients' premises. As parallel computers are frequently charged by the minute, it is indispensable to minimize the transfer time after computation succeeded to keep down costs. Consequently, the economic focus lies on minimizing the time to move away all data from the parallel computer whereas the actual time to arrival remains less (but still) important. This paper describes the design and implementation of a new transfer protocol, the Fast Send Protocol (FSP), which employs striping to intermediate nodes in order to minimize sending time and to utilize the sender's resources to a high extent

    Idiomatic Persistence and Querying for the W3C Web Annotation Data Model

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    Abstract. W3C Web annotations are a powerful way to support metadata information about digital resources. The Web Annotation Data Model proposes standardised RDF structures that express this by implementing a hierarchical annotation structure. Those annotations are designed to be shared, linked, tracked back as well as searched and discovered across different peers. However, non-Semantic Web experts may struggle to produce the corresponding RDF data or SPARQL queries. Therefore, we propose Anno4j, a Java-based library that gives developers the possibility to create and consume Web Annotations by using plain old Java objects. Anno4j follows natural Object-oriented idioms including inheritance, polymorphism, and composition to facilitate the development with Web Annotations. An extensible and modular architecture supports enhancements and use-case specific model alterations, while the plugin functionality of Anno4j allows to enrich querying by adding custom function evaluators

    Multimedia on the web - editorial

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