Search results for "layer"

Modeling Changes for SHOIN(D) Ontologies: An Exhaustive Structural Model

2013

Ontology development starts with a rigorous ontological analysis that provides a conceptualization of the domain to model agreed by the community. An ontology, specified in a formal language, approximates the intended models of this conceptualization. It needs then to be revised and refined until an ontological commitment is found. Also ulterior updates, responding to changes in the domain and/or the conceptualization, are expected to occur throughout the ontology life cycle. To handle a consistent application of changes, a couple of ontology evolution methodologies have been proposed. Maintaining the structural consistency is one of the ontology evolution criteria. It implies modeling chan…

Model Driven Specification of Ontology Translations

2008

The alignment of different ontologies requires the specification, representation and execution of translation rules. The rules need to integrate translations at the lexical, the syntactic and the semantic layer requiring semantic reasoning as well as low-level specification of ad-hoc conversions of data. Existing formalisms for representing translation rules cannot cover the representation needs of these three layers in one model. We propose a metamodel-based representation of ontology alignments that integrate semantic translations using description logics and lower level translation specifications into one model of representation for ontology alignments.

Data Mining of Specific-Domain Ontology Components

2008

This paper describes an approach for eliciting ontology components by using knowledge maps. The knowledge contained in a particular domain, any kind of text digital archive, is portrayed by assembling and displaying its ontology components.

Semi-automatic Derivation of Specific-Domain Ontologies for the Semantic Web

2006

This paper describes an approach for helping in the semi-automatic construction of specific-domain ontology components contained in a digital archive. This proposal for extracting knowledge from digital sources allows users to have a view of this knowledge and visualize specific-domain ontology components that with further processing can be shared with software agents by embedding it into digital archives themselves in the context of the Semantic Web. In particular, we deal with the issue of not constructing the ontology from scratch, our approach helps us to speed up the ontology creation process.

Well-posedness of the boundary layer equations

2004

We consider the mild solutions of the Prandtl equations on the half space. Requiring analyticity only with respect to the tangential variable, we prove the short time existence and the uniqueness of the solution in the proper function space. Theproof is achieved applying the abstract Cauchy--Kowalewski theorem to the boundary layer equations once the convection-diffusion operator is explicitly inverted. This improves the result of [M. Sammartino and R. E. Caflisch, Comm. Math. Phys., 192 (1998), pp. 433--461], as we do not require analyticity of the data with respect to the normal variable.

Análisis de la capa de fibras nerviosas usando el GDx en pacientes pseudofáquicos con opacificación capsular posterior

2008

Ultrafast Gain Recovery in Quantum Dot based Semiconductor Optical Amplifiers

2007

Summary form only given. The limiting factor in ultrahigh bit rate amplification is the ultrafast population recovery in the resonant level, which is mainly limited by carrier capture and relaxation processes in the QD. We use pump-probe measurements resonant to the QDs confined states energies (ground and excited state) to investigate the response to a four fs-pulse train of 1 THz repetition rate. A deep insight about the capture process implied is then obtained, and direct capture from the wetting layer is identified as the dominant mechanism in the high current regime.

Spectral optical layer properties of cirrus from collocated airborne measurements – a feasibility study

2015

Abstract. Spectral optical layer properties of cirrus are derived from simultaneous and vertically collocated measurements of spectral upward and downward solar irradiance above and below the cloud layer and concurrent in situ microphysical sampling. From the irradiance data spectral transmissivity, absorptivity, reflectivity, and cloud top albedo of the observed cirrus layer are obtained. At the same time microphysical properties of the cirrus were sampled. The close collocation of the radiative and microphysical measurements, above, beneath and inside the cirrus, is obtained by using a research aircraft (Learjet 35A) in tandem with a towed platform called AIRTOSS (AIRcraft TOwed Sensor Sh…

Ultra-sensitive fluorescence spectroscopy of isolated surface-adsorbed molecules using an optical nanofiber.

2009

The strong radial confinement and the pronounced evanescent field of the guided light in optical nanofibers yield favorable conditions for ultra-sensitive surface spectroscopy of molecules deposited on the fiber. Using the guided mode of the nanofiber for both excitation and fluorescence collection, we present spectroscopic measurements on 3,4,9,10-perylenetetracarboxylic dianhydride molecules (PTCDA) at ambient conditions. Surface coverages as small as 1 per thousand of a compact monolayer still give rise to fluorescence spectra with a good signal to noise ratio. Moreover, we analyze and quantify the self-absorption effects due to reabsorption of the emitted fluorescence light by circumjac…

Birth of the Localized Surface Plasmon Resonance in Monolayer-Protected Gold Nanoclusters

2013

Gold nanoclusters protected by a thiolate monolayer (MPC) are widely studied for their potential applications in site-specific bioconjugate labeling, sensing, drug delivery, and molecular electronics. Several MPCs with 1-2 nm metal cores are currently known to have a well-defined molecular structure, and they serve as an important link between molecularly dispersed gold and colloidal gold to understand the size-dependent electronic and optical properties. Here, we show by using an ab initio method together with atomistic models for experimentally observed thiolate-stabilized gold clusters how collective electronic excitations change when the gold core of the MPC grows from 1.5 to 2.0 nm. A …