370 research outputs found
BATSE observations of BL Lac Objects
The Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory has been shown to be sensitive to non-transient hard X-ray sources in our galaxy, down to flux levels of 100 mCrab for daily measurements, 3 mCrab for integrations over several years. We use the continuous BATSE database and the Earth Occultation technique to extract average flux values between 20 and 200 keV from complete radio- and X-ray- selected BL Lac samples over a 2 year period
Verification and Validation of Semantic Annotations
In this paper, we propose a framework to perform verification and validation
of semantically annotated data. The annotations, extracted from websites, are
verified against the schema.org vocabulary and Domain Specifications to ensure
the syntactic correctness and completeness of the annotations. The Domain
Specifications allow checking the compliance of annotations against
corresponding domain-specific constraints. The validation mechanism will detect
errors and inconsistencies between the content of the analyzed schema.org
annotations and the content of the web pages where the annotations were found.Comment: Accepted for the A.P. Ershov Informatics Conference 2019(the PSI
Conference Series, 12th edition) proceedin
Weaving the Web(VTT) of Data
International audienceVideo has become a first class citizen on the Web with broad support in all common Web browsers. Where with struc- tured mark-up on webpages we have made the vision of the Web of Data a reality, in this paper, we propose a new vi- sion that we name the Web(VTT) of Data, alongside with concrete steps to realize this vision. It is based on the evolving standards WebVTT for adding timed text tracks to videos and JSON-LD, a JSON-based format to serial- ize Linked Data. Just like the Web of Data that is based on the relationships among structured data, the Web(VTT) of Data is based on relationships among videos based on WebVTT files, which we use as Web-native spatiotemporal Linked Data containers with JSON-LD payloads. In a first step, we provide necessary background information on the technologies we use. In a second step, we perform a large- scale analysis of the 148 terabyte size Common Crawl corpus in order to get a better understanding of the status quo of Web video deployment and address the challenge of integrat- ing the detected videos in the Common Crawl corpus into the Web(VTT) of Data. In a third step, we open-source an online video annotation creation and consumption tool, targeted at videos not contained in the Common Crawl cor- pus and for integrating future video creations, allowing for weaving the Web(VTT) of Data tighter, video by video
Deployment of RDFa, Microdata, and Microformats on the Web – A Quantitative Analysis
More and more websites embed structured data describing for instance
products, reviews, blog posts, people, organizations, events, and cooking recipes
into their HTML pages using markup standards such as Microformats, Microdata
and RDFa. This development has accelerated in the last two years as major Web
companies, such as Google, Facebook, Yahoo!, and Microsoft, have started to
use the embedded data within their applications. In this paper, we analyze the
adoption of RDFa, Microdata, and Microformats across the Web. Our study is
based on a large public Web crawl dating from early 2012 and consisting of 3
billion HTML pages which originate from over 40 million websites. The analysis
reveals the deployment of the different markup standards, the main topical areas
of the published data as well as the different vocabularies that are used within each
topical area to represent data. What distinguishes our work from earlier studies,
published by the large Web companies, is that the analyzed crawl as well as the
extracted data are publicly available. This allows our findings to be verified and to
be used as starting points for further domain-specific investigations as well as for
focused information extraction endeavors
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