Dennis Heinrich

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Currently many SPARQL endpoints are freely available and accessible without any costs to users: Everyone can submit SPARQL queries to SPARQL endpoints via a standardized protocol, where the queries are processed on the datasets of the SPARQL endpoints and the query results are sent back to the user in a standardized format. As these distributed execution(More)
Ocean acidification, resulting from increasing anthropogenic CO2 emissions, is predicted to affect the physiological performance of many marine species. Recent studies have shown substantial reductions in aerobic performance in some teleost fish species, but no change or even enhanced performance in others. Notably lacking, however, are studies on the(More)
In this paper, we investigate the use of Field Programmable Gate Arrays (FPGAs) to enhance the performance of filter expressions in Semantic Web databases. The filter operator is a central part of query evaluation. Its main objective is to reduce the amount of data as early as possible in order to reduce the calculation costs for succeeding and more complex(More)
External merge sort belongs to the most efficient and widely used algorithms to sort big data: As much data as fits inside is sorted in main memory and afterwards swapped to external storage as so called initial run. After sorting all the data in this way block-wise, the initial runs are merged in a merging phase in order to retrieve the final sorted run(More)
In this paper, a data structure and a hardware acceleration for dictionary generation for Semantic Web databases are presented. Current hardware accelerators for databases are based on co-processor designs supporting software-centric applications: only single, selected operations of query processing are offloaded to the FPGA with time-consuming data(More)
Clouds are dynamic networks of common, off-the-shell computers to build computation farms. The rapid growth of databases in the context of the semantic web requires efficient ways to store and process this data. Using cloud technology for storing and processing Semantic Web data is an obvious way to overcome difficulties in storing and processing the(More)