Search results for "RDF"
showing 10 items of 95 documents
ViziQuer: A Visual Notation for RDF Data Analysis Queries
2019
Visual SPARQL query notations aim at easing the RDF data querying task. At the current state of the art there is still no generally accepted visual graph-based notation suitable to describe RDF data analysis queries that involve aggregation and subqueries. In this paper we present a visual diagram-centered notation for SPARQL select query formulation, capable to handle aggregate/statistics queries and hierarchic queries with subquery structure. The notation is supported by a web-based prototype tool. We present the notation examples, describe its syntax and semantics and describe studies with possible end users, involving both IT and medicine students.
Praktiski vizuāli datu vaicājumi
2019
Maģistra darbā ir aprakstīts par saistītajiem datiem, RDF, SPARQL vaicājumiem, ViziQuer rīku, kas paradzēts praktiski vizuāli datu vaicājumu veidošanai, tā darbības būtību, pamatidejām, kā arī piekļuves punktiem, kuros iespējams iegūt datus izmantojot SPARQL vaicājumus. Rīku, ar kura palīdzību iespējams veikt vizuālus datu vaicājumus, šobrīd īsti nav, tāpēc, ņemot vērā to, ka vizuāli sastādīt vaicājumus ir ērtāk kā pārzināt dažādas sintakses, ir svarīgi veikt izpēti un paātrināt attīstību šajā virzienā. Izpētot pieejamos resursus par augstāk minētajām tēmām, veicot praktiskus izmēģinājumus un aplūkojot iegūtos rezultātus, tika izdarīti vairāki secinājumi par ViziQuer rīka darbību un iespēja…
RDF datu validācija, izmantojot datu formas
2017
Šis bakalaura darbs apraksta semantiskajā tīmeklī pieejamo RDF datu validācijas iespējas, izmantojot divas no populārākajām datu formu ierobežojumu valodām - SHACL un ShEx. Datu formu ierobežojumu valodas ļauj pārliecināties, vai semantiskā tīmekļa dati atbilst sagaidītajam formātam no datu lietotāja viedokļa, kā arī, dod iespēju uzlabot šo datu kvalitāti no datu īpašnieka viedokļa. Darba ievadā ir sniegts vispārīgs ieskats semantiskā tīmekļa tehnoloģijās, parādot to sasaisti ar darba pamattēmu. Iztirzājuma daļā ir aprakstītas RDF datu formu ierobežojumu valodas SHACL un ShEx, kā arī dots abu valodu sniegto iespēju salīdzinājums. Atsevišķi tiek apskatīta arī RDF datu praktiskā validācija. B…
Vizuālo vaicājumu rezultātu attēlošana gala lietotājam
2019
Vizuālo/diagrammatisko vaicājumu rīks ViziQuer spēj veidot vizuālus vaicājumus pār semantiskajām datubāzēm (datubāzes RDF formātā), piedāvājot iespējas, kas pārsniedz tradicionālajos vaicājumu rīkos piedāvātās (ietverot agregāciju, apakšvaicājumus). Tomēr iegūto datu attēlošana gala lietotājam šobrīd notiek tikai tabulu veidā. Darba mērķis ir izveidot sistēmu, kas lietotājam iesaka iespējami piemērotāko vizualizāciju, kā arī ļauj lietotājam ērti izvēlēties starp dažādiem rezultātu prezentācijas variantiem.
Building Ontologies from XML Data Sources
2009
In this paper, we present a tool called X2OWL that aims at building an OWL ontology from an XML datasource. This method is based on XML schema to automatically generate the ontology structure, as well as, a set of mapping bridges. The presented method also includes a refinement step that allows to clean the mapping bridges and possibly to restructure the generated ontology.
Querying Dynamic and Context-Sensitive Metadata in Semantic Web
2005
RDF (core Semantic Web standard) is not originally appropriate for context representation, because of its initial focus on the ordinary Web resources, such as web pages, files, databases, services, etc., which structure and content are more or less stable. However, on the other hand, emerging industrial applications consider e.g. machines, processes, personnel, services for condition monitoring, remote diagnostics and maintenance, etc. to be specific classes of Web resources and thus a subject for semantic annotation. Such resources are naturally dynamic, not only from the point of view of changing values for some attributes (state of resource), but also from the point of view of changing “…
COMPOSITION OF REFUSE DERIVED FUELS IN LATVIA AND ESTONIA IN COMPARISION WITH WORLDWIDE AVERAGE VALUES
2019
Information about composition of RDF worldwide was collected using literature analysis. RDF samples produced in Latvia and Estonia were collected, those fractional and elemental composition analyzed using standard methods. Comparing obtained results with worldwide data we have found that the quality of local RDFs in general is higher than typical values, while elevated content of chlorine must be mentioned as a problem. Results also show that majority of chlorine in studied samples exists in organic form. Recommendations to overcome this problem have been developed.
SmartResource Platform and Semantic Agent Programming Language (S-APL)
2007
Although the flexibility of agent interactions has many advantages when it comes to engineering a complex system, the downside is that it leads to certain unpredictability of the run-time system. Literature sketches two major directions for search for a solution: social-level characterization of agent systems and ontological approaches to inter-agent coordination. Especially the latter direction is not yet studied much by the scientific community. This paper describes our vision and the present state of the SmartResource Platform. The main distinctive features of the platform are externalization of behavior prescriptions, i.e. agents access them from organizational repositories, and utiliza…
Probabilistic risk assessment of the exposure to polybrominated diphenyl ethers via fish and seafood consumption in the Region of Valencia (Spain)
2013
The study was carried out to estimate the dietary intake of polybrominated diphenyl ethers (PBDEs) in the Region of Valencia (Spain) in order to evaluate the resultant risk. The PBDE levels in fish and seafood (a total of 206 samples) were determined. Dietary intake was estimated using results of PBDE analyses in fish and seafood marketed in the Region of Valencia over the period 2007-2012 and data of the first Valencian Food Consumption Survey, conducted in 2010. Two scenarios were assumed for left-censored results: the lower-bound (LB) scenario, in which unquantified results (below the limit of quantification (LOQ)) were set to zero and the upper-bound (UB) scenario, in which unquantified…
Assessment of metal levels in foodstuffs from the Region of Valencia (Spain).
2017
Graphical abstract