Search results for "RDF"
showing 10 items of 95 documents
Database to Ontology Mapping Patterns in RDB2OWL Lite
2016
We describe the RDB2OWL Lite language for relational database to RDF/OWL mapping specification and discuss the architectural and content specification patterns arising in mapping definition. RDB2OWL Lite is a simplification of original RDB2OWL with aggregation possibilities and order-based filters removed, while providing in-mapping SQL view definition possibilities. The mapping constructs and their usage patterns are illustrated on mapping examples from medical domain: medicine registries and hospital information system. The RDB2OWL Lite mapping implementation is offered both via translation into D2RQ and into standard R2RML mapping notations.
Angular Dependency of Hyperspectral Measurements over Wheat Characterized by a Novel UAV Based Goniometer
2015
In this study we present a hyperspectral flying goniometer system, based on a rotary-wing unmanned aerial vehicle (UAV) equipped with a spectrometer mounted on an active gimbal. We show that this approach may be used to collect multiangular hyperspectral data over vegetated environments. The pointing and positioning accuracy are assessed using structure from motion and vary from σ = 1° to 8° in pointing and σ = 0.7 to 0.8 m in positioning. We use a wheat dataset to investigate the influence of angular effects on the NDVI, TCARI and REIP vegetation indices. Angular effects caused significant variations on the indices: NDVI = 0.83–0.95; TCARI = 0.04–0.116; REIP = 729–735 nm. Our analysis high…
Enrichissement sémantique d'un IFC pour une extraction partielle dynamique
2014
http://www.lcdpu.fr/livre/?GCOI=27000100860820&fa=sommaire; International audience; La dématérialisation de l'ensemble des données et des processus dans le domaine du bâtiment est un enjeu mondial depuis ces 10 dernières années. Au-delà de la simple représentation géométrique d'un bâtiment, le BIM s'impose petit à petit comme un système d'information coopératif complexe, intégrant avec difficulté les données et pratiques hétérogènes des différents acteurs du domaine. La restitution intégrée de ces données aux usagers du bâtiment est une opération délicate. Pour répondre à ce verrou, nous utilisons une approche sémantique de représentation du bâtiment et particulièrement de la norme IFC. Cet…
Modélisation d'images agronomiques - application a la reconnaissance d'adventices par imagerie pour une pulvérisation localisée
2009
Plant (crop and weed) identification is a very active field of research in agriculture since the reinforcement of European laws about pesticide applications for a site-specific management of spraying practices. A new crop/weed simulation model was developed to allow the evaluation of crop/weed spatial identification methods from imaging. Considering multiples agronomic parameters – crop location, weed infestation rate, weed spatial distribution – the first step of this model allows the simulation of an infested crop field. Then, in a second step, a world to camera transformation is applied to allow every kind of picture (with or without perspective effect). The validation of this model was …
The visual query language CQL for transitive and relational computation
2000
Abstract Classification query language (CQL) is a high-level visual query language with a great expressive power. In CQL the processing of ordinary relations and classifications based on transitive relationships is integrated seamlessly. Relations and classifications are represented in the visual interface in a uniform way through relation and classification skeletons. All query formulation in CQL is QBE-like – based on the intuitive way of filling constants and sample values into the skeletons. In order to guarantee great expressive power, relational and classification expressions can be nested freely with each other at unlimited nesting levels. Recursive definition of transitive processin…
Schema-Based Visual Queries over Linked Data Endpoints
2019
We present the option to use the schema-based visual query tool ViziQuer over realistic Linked Data endpoints. We describe the tool meta-schema structure and the means for the endpoint schema retrieval both from an OWL ontology and from a SPARQL endpoint. We report on a store of the endpoint-specific schemas and the options to support the schema presentation to the end-user both as a class tree within the environment and as external visual diagram.
Export of Relational Databases to RDF Databases: A Case Study
2010
The vast amount of business information nowadays is stored in relational databases. For the Semantic Web vision to become a reality, we need ways how to exploit this data in form of RDF triples. The universal and commonly accepted solution for this problem still does not exist. In most cases, mapping languages are used for specification of correspondences between OWL ontology and DB schema. At the same time, these languages generally are not well suited for specification of mappings in cases when there is a substantial difference between OWL ontology and DB schema. In this paper, we describe a new model transformation-based method for specification of correspondences between the elements of…
Faceted Search Over RDF-Based Knowledge Graphs
2016
Knowledge graphs such as Yago and Freebase have become a powerful asset for enhancing search, and are being intensively used in both academia and industry. Many existing knowledge graphs are either available as Linked Open Data, or they can be exported as RDF datasets enhanced with background knowledge in the form of an OWL 2 ontology. Faceted search is the de facto approach for exploratory search in many online applications, and has been recently proposed as a suitable paradigm for querying RDF repositories. In this paper, we provide rigorous theoretical underpinnings for faceted search in the context of RDFbased knowledge graphs enhanced with OWL 2 ontologies. We identify well-defined fra…
A framework for context-sensitive metadata description
2006
Expectations regarding the new generation of Web depend on the success of Semantic Web technology. Resource Description Framework (RDF) is a basis for explicit and machine-readable representation of semantics. However RDF is not suitable for describing dynamic and context-sensitive resources (eg. processes). We present the Context Description Framework (CDF) as an extension of the RDF by adding a 'TrueInContext' component to the basic RDF triple ('subject-predicate-object'), and consider contextual value as a container of RDF statements. We also add a probabilistic component, which allows multilevel contextual dependence descriptions as well as presumes possibility for Bayesian reasoning wi…
Advanced RDB-to-RDF/OWL Mapping Facilities in RDB2OWL
2011
We present advanced features of RDB2OWL mapping specification language that allows expressing RDB-to-RDF/OWL mappings in a concise and human comprehensible way. The RDB2OWL mappings can be regarded as documentation of the database-to-ontology relation. The RDB2OWL language uses the OWL ontology structure as a backbone for mapping specification by placing the database link information into the annotations for ontology classes and properties. Its features include reuse of database table key information, user defined scalar and aggregate functions, table-based functions and multiclass conceptualization that is essential to keep mappings compact in case when large tables are mapped onto several…