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Πλοήγηση ανά Θέμα "Query languages"

Αποτελέσματα 1-20 από 25

    • Big spatial and spatio-temporal data analytics systems 

      Velentzas P., Corral A., Vassilakopoulos M. (2021)
      We are living in the era of Big Data, and Spatial and Spatio-temporal Data are not an exception. Mobile apps, cars, GPS devices, ships, airplanes, medical devices, IoT devices, etc. are generating explosive amounts of data ...

    • Building in-silico pathway SBML models from heterogeneous sources 

      Kanaris, I.; Moutselos, K.; Chatziioannou, A.; Maglogiannis, I.; Kolisis, F. N. (2008)
      The recent revolutionary developments concerning the high throughput (-omics) measuring techniques in life sciences is expediting the way for the development of in silico models envisioning the Systems biology perspective ...

    • Bulk-loading xBR+-trees 

      Roumelis G., Vassilakopoulos M., Corral A., Manolopoulos Y. (2016)
      Spatial indexes are important in spatial databases for efficient execution of queries involving spatial constraints. The xBR+-tree is a balanced disk-resident quadtree-based index structure for point data, which is very ...

    • A comparison of distributed spatial data management systems for processing distance join queries 

      García-García F., Corral A., Iribarne L., Mavrommatis G., Vassilakopoulos M. (2017)
      Due to the ubiquitous use of spatial data applications and the large amounts of spatial data that these applications generate, the processing of large-scale distance joins in distributed systems is becoming increasingly ...

    • Conceptual universal database language: Moving up the database design levels 

      Karanikolas, N. N.; Vassilakopoulos, M. Gr (2009)
      Today, the simplicity of the relational model types affects Information Systems design. We favor another approach where the Information System designers would be able to portray directly the real world in a database model ...

    • Double chain-star: An RDF indexing scheme for fast processing of SPARQL joins 

      Meimaris M., Papastefanatos G. (2016)
      State of the art RDF stores often rely on exhaustive indexing and sequential (self-)joins for SPARQL query processing. However, query execution is dependent on, and often limited by the underlying storage and indexing ...

    • An efficient algorithm for bulk-loading xBR+-trees 

      Roumelis G., Vassilakopoulos M., Corral A., Manolopoulos Y. (2018)
      A major part of the interface to a database is made up of the queries that can be addressed to this database and answered (processed) in an efficient way, contributing to the quality of the developed software. Efficiently ...

    • An efficient flash-aware spatial index for points 

      Carniel A.C., Roumelis G., Ciferri R.R., Vassilakopoulos M., Corral A., Ciferri C.D.deA. (2018)
      Spatial database systems often employ spatial indices to speed up the processing of spatial queries. In addition, modern spatial database applications are interested in exploiting the positive characteristics of flash-based ...

    • Efficient large-scale distance-based join queries in spatialhadoop 

      García-García F., Corral A., Iribarne L., Vassilakopoulos M., Manolopoulos Y. (2018)
      Efficient processing of Distance-Based Join Queries (DBJQs) in spatial databases is of paramount importance in many application domains. The most representative and known DBJQs are the K Closest Pairs Query (KCPQ) and the ...

    • Efficient query processing on large spatial databases: A performance study 

      Roumelis G., Vassilakopoulos M., Corral A., Manolopoulos Y. (2017)
      Processing of spatial queries has been studied extensively in the literature. In most cases, it is accomplished by indexing spatial data using spatial access methods. Spatial indexes, such as those based on the Quadtree, ...

    • Extended characteristic sets: Graph indexing for SPARQL Query Optimization 

      Meimaris M., Papastefanatos G., Mamoulis N., Anagnostopoulos I. (2017)
      SPARQL query execution in state of the art RDF engines depends on, and is often limited by the underlying storage and indexing schemes. Typically, these systems exhaustively store permutations of the standard three-column ...

    • Extended OQL for object oriented parallel query processing 

      Fountoukis, S. G.; Bekakos, M. P. (2007)
      Herein, an extension to the object query language (OQL) for incorporating binary relational expressions is investigated. The extended query language is suitable for query submissions to an object oriented database, whose ...

    • GRISSOM web based grid portal: Exploiting the power of grid infrastructure for the interpretation and storage of DNA microarray experiments 

      Chatziioannou, A.; Kanaris, I.; Maglogiannis, I.; Doukas, C.; Moulos, P.; Pilalis, E.; Kolisis, F. (2009)
      DNA Microarrays have dramatically reshaped modern biological research by deriving profiles of genome-wide expression of living organisms, and producing an unprecedented wealth of quantitative data. Given this characteristic, ...

    • The K group nearest-neighbor query on non-indexed RAM-resident data 

      Roumelis G., Vassilakopoulos M., Corral A., Manolopoulos Y. (2016)
      Data sets that are used for answering a single query only once (or just a few times) before they are replaced by new data sets appear frequently in practical applications. The cost of buiding indexes to accelerate query ...

    • Merging R-trees 

      Vasaitis, V.; Nanopoulos, A.; Bozanis, P. (2004)
      R-trees, since their introduction in 1984, have been proven to be one of the most well-behaved practical data structures for accommodating dynamic massive sets of geometric objects and conducting a diverse set of queries ...

    • New plane-sweep algorithms for distance-based join queries in spatial databases 

      Roumelis G., Corral A., Vassilakopoulos M., Manolopoulos Y. (2016)
      Efficient and effective processing of the distance-based join query (DJQ) is of great importance in spatial databases due to the wide area of applications that may address such queries (mapping, urban planning, transportation ...

    • Plane-sweep algorithms for the K Group Nearest-Neighbor Query 

      Roumelis, G.; Vassilakopoulos, M.; Corral, A.; Manolopoulos, Y. (2015)
      One of the most representative and studied queries in Spatial Databases is the (K) Nearest-Neighbor (NNQ), that discovers the (K) nearest neighbor(s) to a query point. An extension that is important for practical applications ...

    • A query language for multi-version data web archives 

      Meimaris M., Papastefanatos G., Viglas S., Stavrakas Y., Pateritsas C., Anagnostopoulos I. (2016)
      The Data Web refers to the vast and rapidly increasing quantity of scientific, corporate, government and crowd-sourced data published in the form of Linked Open Data, which encourages the uniform representation of heterogeneous ...

    • RkNN query processing in distributed spatial infrastructures: A performance study 

      García-García F., Corral A., Iribarne L., Vassilakopoulos M. (2017)
      The Reverse k-Nearest Neighbor (RkNN) problem, i.e. finding all objects in a dataset that have a given query point among their corresponding k-nearest neighbors, has received increasing attention in the past years. RkNN ...

    • Robust multi-modal speech recognition in two languages utilizing video and distance information from the kinect 

      Galatas, G.; Potamianos, G.; Makedon, F. (2013)
      We investigate the performance of our audio-visual speech recognition system in both English and Greek under the influence of audio noise. We present the architecture of our recently built system that utilizes information ...