165 research outputs found
An intelligent alternative approach to the efficient network management
Due to the increasing complexity and heterogeneity of networks and services, many efforts have been made to develop intelligent techniques for management. Network intelligent management is a key technology for operating large heterogeneous data transmission networks. This paper presents a
proposal for an architecture that integrates management object specifications and the knowledge of expert systems. We present a new approach named Integrated Expert Management, for learning objects based on expert management rules and describe the design and implementation of an integrated intelligent
management platform based on OSI and Internet management models. The main contributions of our approach is the integration of both expert system and managed models, so we can make use of them to construct more flexible intelligent management network. The prototype SONAP (Software for Network Assistant and Performance) is accuracy-aware since it can control and manage a network. We have tested our system on real data to the fault diagnostic in a telecommunication system of a power utility. The
results validate the model and show a significant improvement with respect to the number of rules and the error rate in others systems
Integración de inteligencia en la MIB del Modelo OSI para la gestión de redes de telecomunicaciones
La Gestión de red se define como el conjunto de actividades dedicadas al control y vigilancia de los
recursos existentes en las redes de telecomunicaciones. En los complejos sistemas actuales, es necesario realizar
una gestión de la red asistida por un software avanzado. La Inteligencia Artificial se incorpora a la gestión de las
redes, con el fin de facilitar labores de administración y control de toda la información que proviene de los
recursos gestionados, dando origen a la Gestión Inteligente de las Redes. Este nuevo paradigma, proporciona a los
sistemas de gestión de un mayor grado de cohesión con las tecnologías de comunicaciones actuales, a la vez de
disponer de todas las posibilidades y ventajas aportadas por la Inteligencia Artificial. Nuestro estudio tiene como
objetivo perfeccionar las técnicas actuales de gestión. Para ello se establecen mecanismos que permiten una mayor
correlación entre las especificaciones de la red y las aplicaciones que efectúan el tratamiento de la información de
gestión. Presentamos una nueva concepción denominada “Gestión Inteligente Integrada” y una extensión del
modelo de gestión OSI, que contempla la inclusión del conocimiento de gestión, en las propias especificaciones
de los objetos gestionados. Este modelo consigue reunir conceptos que actualmente pertenecen a distintos ámbitos
de estudio, la Inteligencia Artificial y la Información de Gestión del sistema. De esta forma se obtiene una
solución global, que permite a los administradores de redes utilizar la potencia aportada por la Inteligencia
Artificial, en particular de los Sistemas Expertos, de una forma sencilla y transparente
Mechanical characterization and elastic stiffness degradation of unstabilized rammed earth
Rammed earth is attracting renewed interest due to its sustainability. In this work, a mechanical
characterization of unstabilized rammed earth is presented. Compressive strength, Young’s
modulus, and Poisson’s ratio were determined, with the first of these being the most representative
mechanical property of rammed earth. Stress – strain curves were obtained from uniaxial
compression tests. Creep is of great importance in the long-term assessment of historical buildings
and in the design of new ones. Samples of rammed earth were subjected to a constant load for 15
days to study their creep behavior. In order to simulate the long-term behavior of the material,
different rheological models were fitted to the experimental results. The instantaneous deformation
of rammed earth samples caused by a sudden additional load (maintaining a previous
service load level) was also studied. This is the first time that this phenomenon, called elastic
stiffness degradation, has been studied for rammed earth material
The octahedron family: a source of tensegrity structures
A tensegrity family is a group of tensegrity structures that share a common connectivity pattern. In the case that just two values of the force density or force:length ratio are adopted (one for cables and another for struts), the members of the octahedron family are: the octahedron, the expanded octahedron and the double-expanded octahedron. In this work a higher number of possible force:length ratio values have been considered in order to find new members of the family. The values of the force:length ratios which satisfy the super-stability conditions have been computed analytically. New super-stable tensegrity forms of the octahedron family have been obtained. Results show that all of them are members of the octahedron family having as folded forms all the lower members of the family. Finally, based on topological rules, it has been proved that the double-expanded octahedron can be defined from a truncated cube
Topological design of the octahedron tensegrity family
Tensegrity structures have developed greatly in recent years due to their unique mechanical and mathematical
properties. In this work, the topology of the Octahedron family is presented. New tensegrity structures that
belong to this family are defined based on their topology. As an example, the eleven-time-expanded octahedron is
shown, a super-stable tensegrity formed by 12,288 nodes, 6,144 struts, and 24,576 cables (the largest superstable
tensegrity reported in the literature in terms of number of nodes, cables, and struts so far). The values
of the force:length ratios which satisfy the super-stability conditions have also been determined based on the
topology of the Octahedron family. Consequently, the computational cost of the process of determining a suitable
prestress state and its corresponding equilibrium shape (a process called form-finding) is significantly reduced.
The members of the Octahedron family could have promising engineering and bioengineering applications
The Z-octahedron family: a new tensegrity family
The present paper work was sent to Engineering Structures on 23 April 2020 (it is currently under review).A new family of tensegrity structures is presented: the Z-octahedron family. A tensegrity family is a group of tensegrity structures that share a common connectivity pattern. The members of the Z-octahedron family have been obtained replacing the elementary rhombic cells of the members of the octahedron family with elementary Z-shaped cells. In addition, a higher number of possible force density or force:length ratio values have been considered. The values of the force:length ratio of the members of the family that lead to super-stable tensegrity forms have been computed analytically. Two members of the family have been obtained: the Z-expanded octahedron and the Z-double-expanded octahedron. Finally it has been proved that the Z-double-expanded octahedron obtained here from topological rules can also be defined from a truncated cube based on purely geometrical intuition
Mechanical Characterization and Creep Behavior of a Stone Heritage Material Used in Granada (Spain): Santa Pudia Calcarenite
Santa Pudia calcarenite was one of the most commonly used building materials in the construction of historical buildings in
the city of Granada (Spain). As a result, Santa Pudia calcarenite has been mainly studied from a petrographical point of view
in previous works. In this work, the mechanical properties of Santa Pudia calcarenite are studied. The main mechanical properties
(compressive strength, elastic modulus and Poisson’s ratio) were determined using the corresponding tests. Samples
of Santa Pudia calcarenite were heated at 550 °C to study the effect of high temperatures on its compressive strength. Two
different cooling methods were considered: air-cooling and water-cooling. Stress–strain curves of heated and non-heated
samples were obtained from uniaxial compression tests. Creep is of great importance in the long-term structural assessment
of historical buildings. To study the creep behaviour of Santa Pudia calcarenite, samples were subjected to uniaxial compressive
tests at constant stress until the stabilization of the recorded strains was reached. Different rheological models were
adjusted to the experimental results to simulate the long-term behaviour of the material studied. The instantaneous response
to additional loadings on the samples (maintaining the long-term loading and deformation) were also studied. Results show
that a Santa Pudia calcarenite specimen subjected to dead loads will suffer a higher instantaneous deformation against a
sudden load than a non-preloaded specimen. This degradation effect can be particularly important in the case of a seismic
evaluation of historical buildings
Topological design of compression structures with prestressing tendons
Compression structures with prestressing tendons are a new type of structures which combines a compression structure with a discrete number of tension members treated as ties. They are an intermediate case between tension-only structures and compression-only structures. As tension and compression members exist, the force density matrix can be singular or ill-conditioned. Consequently, the solution of the equilibrium equation is not as simple as in the case of tension-only and compression-only structures. In this catalogue, nine compression structures with prestressing tendons are presented to show the potential of this new type of structure
Octahedron family: the double-expanded octahedron tensegrity
Es un preprintThe octahedron family of tensegrity structures is presented in this research. The octahedron and the expanded octahedron (well-known tensegrities in the literature) are the first and second components of the family. A new tensegrity is presented: the double-expanded octahedron. This new tensegrity form was obtained following the connectivity pattern of the octahedron family presented in this work. The values of the force densities or force:length ratios that satisfy the minimum required rank deficiency of the force density matrix were computed analytically. Two types of solutions are obtained: full and folded forms. Results show that each lower member of the octahedron family is a folded form of a superior member of this family. Several examples are shown.Grupo de Investigación TEP-19
Use of thermal modeling to assess the tectono-metamorphic history of the Lugo and Sanabria gneiss domes, Northwest Iberia
The Lugo and Sanabria domes in Northwest Iberia have well constrained metamorphic and structural histories.
Both occur in the Iberian autochthon and resulted from late-Variscan extensional collapse following crustal thickening
related to the Variscan collision. The two domes developed beneath large thrust sheets, are cored by
sillimanite-orthoclase anatectic gneiss, preserve evidence of a steep thermal gradient (1 oC MPa-1), and exhibit a distinct
decrease in metamorphic grade to the east in the direction of nappe movement. Geochronological evidence indicates
that the lower crust melted within 30 Ma of initial crustal thickening and that dome formation occurred within
50 Ma.
The histories of the two domes are considered as the basis for one-dimensional finite-difference models of thermal
response to changes in crustal thickness. Results from thermal models suggest that thickening was limited to the
crust, provide a numeric explanation for timing and nature of granite magmatism, and indicate that high-temperature
metamorphism and crustal anatexis may result directly from thermal relaxation, eliminating the need for significant
mantle thermal contribution. Also, the models show that small differences in thickness of large, wedge-shaped thrust
sheets can explain distinct P-T paths experienced by different limbs of the domes
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