1,029 research outputs found
Ontological Reengineering for Reuse
This paper presents the concept of Ontological Reengineering as the process of retrieving
and transforming a conceptual model of an existing and implemented ontology into a new, more correct and more complete conceptual model which is reimplemented. Three activities have been identified in this process: reverse engineering, restructuring and forward engineering. The aim of Reverse Engineering is to output a possible conceptual model on the basis of the code in which the ontology is implemented. The goal of Restructuring is to reorganize this initial conceptual model into a new conceptual model, which is built bearing in mind the use of the restructured ontology by the ontology/application that reuses it. Finally, the objective of Forward Engineering is output a new implementation of the ontology. The paper also discusses how the ontological reengineering process has been applied to the Standard-Units ontology [18], which is included in a Chemical-Elements [12] ontology. These two ontologies will be included in a Monatomic-Ions and Environmental-Pollutants ontologies
Wetting of Nematic Liquid Crystals on Crenellated Substrates: A Frank–Oseen Approach
We revisit the wetting of nematic liquid crystals in contact with crenellated substrates, studied previously using the Landau–de Gennes formalism. However, due to computational limitations, the characteristic length scales of the substrate relief considered in that study limited to less than 100 nematic correlation lengths. The current work uses an extended Frank–Oseen formalism, which includes not only the free-energy contribution due to the elastic deformations but also the surface tension contributions and, if disclinations or other orientational field singularities are present, their core contributions. Within this framework, which was successfully applied to the anchoring transitions of a nematic liquid crystal in contact with structured substrates, we extended the study to much larger length scales including the macroscopic scale. In particular, we analyzed the interfacial states and the transitions between them at the nematic–isotropic coexistence
An extension of the slash-elliptical distribution
This paper introduces an extension of the slash-elliptical distribution. This new distribution is generated as the quotient between two independent random variables, one from the elliptical family (numerator) and the other (denominator) a beta distribution. The resulting slash-elliptical distribution potentially has a larger kurtosis coefficient than the ordinary slash-elliptical distribution. We investigate properties of this distribution such as moments and closed expressions for the density function. Moreover, an extension is proposed for the location scale situation. Likelihood equations are derived for this more general version. Results of a real data application reveal that the proposed model performs well, so that it is a viable alternative to replace models with lesser kurtosis flexibility. We also propose a multivariate extension
Ontology's crossed life cycles
This paper presents the idea that the life cycle of an ontology is highly impacted as a result of the process of reusing it for building another ontology. One of the more important results of the experiment presented is how the different activities to be carried out during the development of a specific ontology may involve performing other types of activities on other ontologies already built or under construction. We identify in that paper new intradependencies between activities carried out inside the same otology and interdependencies between activities carried out in different ontologies. The interrelation between life cycles of several ontologies provokes that integration has to be approached globally rather than as a mere integration of out implementation
Nonsmooth multiobjective fractional programming with generalized convexity
En el artículo estudiamos una clase de problemas fraccionales multiobjetivos no convexos y no diferenciables. Usamos la transformación propuesta por Dinkelbach [2] y Jagannathan [4] y obtenemos condiciones de optimalidad para soluciones débilmente eficientes de dichos problemas. Además, definimos un problema dual y establecemos algunos resultados sobre dualidad. Para lograrlo, utilizamos una noción de convexidad generalizada llamada KT-invexidad. El artículo generaliza los resultados obtenidos por Osuna-Gómez et al. en [6], en donde los autores consideran problemasIn this paper we study a class of nonconvex and nondifferentiable multiobjective fractional problems. We use the transformation proposed by Dinkelbach [2] and Jagannathan [4] and we obtain optimality conditions for weakly efficient solutions for these problems. Furthermore, we define a dual problem and we establish some results on duality. To obtain our results, we use a notion of generalized convexity, called KT-invexity. Our paper generalizes the results given by Osuna-Gómez et al. in [6], where the authors considered smooth problems.
 
Generalized Berreman's model of the elastic surface free energy of a nematic liquid crystal on a sawtoothed substrate
In this paper we present a generalization of Berreman's model for the elastic
contribution to the surface free-energy density of a nematic liquid crystal in
presence of a sawtooth substrate which favours homeotropic anchoring, as a
function of the wavenumber of the surface structure , the tilt angle
and the surface anchoring strength . In addition to the previously
reported non-analytic contribution proportional to , due to the
nucleation of disclination lines at the wedge bottoms and apexes of the
substrate, the next-to-leading contribution is proportional to for a given
substrate roughness, in agreement with Berreman's predictions. We characterise
this term, finding that it has two contributions: the deviations of the nematic
director field with respect to the corresponding to the isolated disclination
lines, and their associated core free energies. Comparison with the results
obtained from the Landau-de Gennes model shows that our model is quite accurate
in the limit , when strong anchoring conditions are effectively achieved.Comment: 13 pages, 9 figures; revised version submitted to Phys. Rev.
Manejo exitoso con stent en un prematuro con síndrome de vena cava superior. Reporte de caso
El síndrome de vena cava superior en la infancia es una complicación inusual al uso de catéter venoso central en la unidad de cuidados intensivos neonatales. Otras causas en niños son la cirugía para enfermedades congénitas del corazón la cual ocupa la mayoría de los casos, y los linfomas, que constituyen la segunda causa más frecuente de obstrucción. Se describe el caso de un recién nacido prematuro de 25 semanas, con síndrome de vena cava superior secundario al uso de catéter venoso central para manejo de sepsis. Se destaca la importancia de un diagnóstico y tratamiento precoz. Así mismo, se reporta el manejo exitoso con stent para el síndrome de vena cava superior.Superior vena cava syndrome in infancy is an unusual complication of the use of central venous catheters in neonatal intensive care unit. Other causes of this syndrome in children are surgery for congenital heart disease which accounts for most of the cases, and lymphomas, that constitute the second most common cause of obstruction. We describe the case of a premature infant born at 25 weeks with superior vena cava syndrome secondary to a central venous catheter for management of sepsis. The importance of early diagnosis and treatment is highlighted. We also report the successful management with stenting for superior vena cava syndrome
Biodiesel production from palm oil in a fixed-bed-reactor with calcium methoxide catalyst
En el presente trabajo se analizó el comportamiento del metóxido de calcio como catalizador para la producción de
biodiesel a partir de aceite de palma. Inicialmente se establecieron condiciones de operación en un reactor por lotes,
como temperatura de activación CaO (25°C), temperatura de reacción (60°C) y relación molar metanol/aceite (10).
Se describió el montaje y puesta en marcha de un reactor de lecho fijo y flujo continuo a escala laboratorio; a las
condiciones establecidas se obtuvieron rendimientos a métilesteres del 20% con un tiempo de residencia de 60 min.
También se analizó el uso de cosolventes como el terbutanol y el acetato de etilo para eliminar las limitaciones de
transferencia de masa entre las fases e incrementar los rendimientos a metil ésteres. Se encontró que el uso de etil
acetato como cosolvente incrementó el rendimiento a metil esteres hasta el 31 %. Abstract
In this research, the behavior of calcium methoxide as catalyst for the production of biodiesel from palm oil
in a continuous system was studied. Initially, operating conditions such as CaO activation temperature (25°C),
reaction temperature (60°C) and molar ratio methanol-oil (10)were established for a batch reactor. Then, the
schematic diagram of the experimental setup and its implementation were described for a packed-bed laboratory
scale reactor with continuous flow; for this system, yields of methyl esters of 20% with a residence time of 60 min
were obtained. The use of co-solvent such as tert-Bbutanol and ethyl acetate in the continuous reaction system
was also investigated, aiming to eliminate mass transfer artifacts between the phases and eventually increasing
yields to methyl esters. The use of ethyl acetate as co-solvent increased methyl esters yields up to 31 %
Gastronomía típica margariteña como atractivo turístico del municipio Antolín del Campo. Estado Nueva Esparta
Se caracteriza la situación actual de la Gastronomía Típica Margariteña como atractivo turístico
del Municipio Antolín del Campo. Se determinan los elementos que la componen, se inventariaron
los productos de la Gastronomía Típica Margariteña ofertados por los restaurantes del municipio y se
identificó el tipo de promoción, se obtuvo la opinión de turistas y propietarios de los restaurantes, respecto
a esta gastronomía como Atractivo Turístico. El estudio es descriptivo. Como conclusión se obtuvo
que: la gastronomía Típica Margariteña no es resaltada como elemento del folklore margariteño, es
ofrecida como una opción más en el menú no como plato principal, los restaurantes que ofrecen gastronomía
Típica Margariteña no utilizan ningún tipo de promoción para la misma.This work deals with the actual situation of the typical gastronomy from Margarita Island as a
tourist attraction of Antolín del Campo municipality. All the elements are determined, the gastronomical
products are sorted according to what is sold in the restaurants of the municipality and the type of promotion
was identified. The restaurants owners` and tourist opinion about the typical gastronomy from
Margarita island as a tourist attraction was got. This is a descriptive research. In conclusion the typical
gastronomy from Margarita island is not taken into consideration as an element of the Margarita island
folklore. It is offered as an option of the menu but no as a main course. The restaurants that sell the typical
dishes do not offer any kind promotion of them
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