93 research outputs found
Knowledge Propagation in Contextualized Knowledge Repositories: an Experimental Evaluation
As the interest in the representation of context dependent knowledge in the
Semantic Web has been recognized, a number of logic based solutions have been
proposed in this regard. In our recent works, in response to this need, we
presented the description logic-based Contextualized Knowledge Repository (CKR)
framework. CKR is not only a theoretical framework, but it has been effectively
implemented over state-of-the-art tools for the management of Semantic Web
data: inference inside and across contexts has been realized in the form of
forward SPARQL-based rules over different RDF named graphs. In this paper we
present the first evaluation results for such CKR implementation. In
particular, in first experiment we study its scalability with respect to
different reasoning regimes. In a second experiment we analyze the effects of
knowledge propagation on the computation of inferences.Comment: ARCOE-Logic 2014 Workshop Notes, pp. 13-2
Dynamic Provenance for SPARQL Update
While the Semantic Web currently can exhibit provenance information by using
the W3C PROV standards, there is a "missing link" in connecting PROV to storing
and querying for dynamic changes to RDF graphs using SPARQL. Solving this
problem would be required for such clear use-cases as the creation of version
control systems for RDF. While some provenance models and annotation techniques
for storing and querying provenance data originally developed with databases or
workflows in mind transfer readily to RDF and SPARQL, these techniques do not
readily adapt to describing changes in dynamic RDF datasets over time. In this
paper we explore how to adapt the dynamic copy-paste provenance model of
Buneman et al. [2] to RDF datasets that change over time in response to SPARQL
updates, how to represent the resulting provenance records themselves as RDF in
a manner compatible with W3C PROV, and how the provenance information can be
defined by reinterpreting SPARQL updates. The primary contribution of this
paper is a semantic framework that enables the semantics of SPARQL Update to be
used as the basis for a 'cut-and-paste' provenance model in a principled
manner.Comment: Pre-publication version of ISWC 2014 pape
Fruit-based fermented beverages : contamination sources and emerging technologies applied to assure their safety
The food and beverage market has become broader due to globalization and consumer
claims. Under the umbrella of consumer demands, legislation, nutritional status, and sustainability,
the importance of food and beverage safety must be decisive. A significant sector of food production
is related to ensuring fruit and vegetable conservation and utilization through fermentation. In
this respect, in this review, we critically analyzed the scientific literature regarding the presence of
chemical, microbiological and physical hazards in fruit-based fermented beverages. Furthermore, the
potential formation of toxic compounds during processing is also discussed. In managing the risks,
biological, physical, and chemical techniques can reduce or eliminate any contaminant from fruitbased fermented beverages. Some of these techniques belong to the technological flow of obtaining
the beverages (i.e., mycotoxins bound by microorganisms used in fermentation) or are explicitly
applied for a specific risk reduction (i.e., mycotoxin oxidation by ozone). Providing manufacturers
with information on potential hazards that could jeopardize the safety of fermented fruit-based drinks
and strategies to lower or eliminate these hazards is of paramount importance.info:eu-repo/semantics/publishedVersio
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Nanostructured metal oxides semiconductors for oxygen chemiresistive sensing
Nanostructured metal oxide semiconductors have been widely investigated and are commonly used in gas sensing structures. After a brief review which will be focused on chemiresistive oxygen sensing employing this type of sensing materials, for both room temperature and harsh environment applications (particularly, at high ambient temperature and high relative humidity levels), paper reports new results concerning O2detection of a structure using a sensing layer comprising nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8(STFO40), synthesized by sonochemical methods, mixed with single wall carbon nanotubes. The structure is a Microelectromechanical System (MEMS), based on a Silicon-on-Insulator (SOI), Complementary Metal-Oxide-Semiconductor (CMOS)-compatible micro-hotplate, comprising a tungsten heater which allows an excellent control of the sensing layer working temperature. Oxygen detection tests were performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 20% (v/v), at a constant heater temperature of 650 °C
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CMOS-compatible SOI micro-hotplate-based oxygen sensor
© 2016 IEEE. The paper reports upon the design and characterization of a resistive O2 sensor, which is fully CMOS-compatible and is based on an ultra-low-power Silicon on Insulator (SOI) micro-hotplate membrane. The microsensor employs SrTi0.4Fe0.6O2.8 (STFO60) as sensing layer. Thermo-Gravimetric Analysis (TGA) Energy-Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) techniques have been used to assess the quality of both the sensing layer and STFO-SOI interface. At room temperature, the SOI sensor shows good sensitivity and fast response time (≤ 6 seconds) to O2 concentration ranging from 0% to 20% in a nitrogen atmosphere. This is the first experimental result showing the potential of this structure as O2 sensor
Protect Your RDF Data!
Conference paperThe explosion of digital content and the heterogeneity of enterprise
content sources have pushed existing data integration solutions to their
boundaries. Although RDF can be used as a representation format for integrated
data, enterprises have been slow to adopt this technology. One of the primary
inhibitors to its widespread adoption in industry is the lack of fine grained
access control enforcement mechanisms available for RDF. In this paper, we
provide a summary of access control requirements based on our analysis of
existing access control models and enforcement mechanisms. We subsequently: (i)
propose a set of access control rules that can be used to provide support for
these models over RDF data; (ii) detail a framework that enforces access control
restrictions over RDF data; and (iii) evaluate our implementation of the
framework over real-world enterprise data.non-peer-reviewe
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