13,623 research outputs found
Deployment of Digital Video and Audio Over Electrical SCADA Networks
With the arrival of new hardware and software technologies,
supervisory control and data acquisition human-machine
interfaces (SCADA/HMI), usually text-based, can now benefit
from the advantages the inclusion of multimedia information
brings. However, due to the special requirements imposed by
such systems, integrating audio and video data into the SCADA
interfaces is not a trivial task. In this document we analyze those
special characteristics and propose solutions so this integration is
possible in power systems communication.Ministerio de Ciencia y Tecnología TIC2000-0367-P4-0
Supersymmetric Extension of the Snyder Algebra
We obtain a minimal supersymmetric extension of the Snyder algebra and study
its representations. The construction differs from the general approach given
in Hatsuda and Siegel ({\tt hep-th/0311002}), and does not utilize super-de
Sitter groups. The spectra of the position operators are discrete, implying a
lattice description of space, and the lattice is compatible with supersymmetry
transformations.Comment: 14 page
-structures in the integration of involutive distributions
For a system of ordinary differential equations (ODEs) or, more generally, an
involutive distribution of vector fields, the problem of its integration is
considered. Among the many approaches to this problem, solvable structures
provide a systematic procedure of integration via Pfaffian equations that are
integrable by quadratures. In this paper structures more general than solvable
structures (named cinf-structures) are considered. The symmetry condition in
the concept of solvable structure is weakened for cinf-structures by requiring
their vector fields be just cinf-symmetries. For cinf-structures there is also
an integration procedure, but the corresponding Pfaffian equations, although
completely integrable, are not necessarily integrable by quadratures. The
well-known result on the relationship between integrating factors and Lie point
symmetries for first-order ODEs is generalized for cinf-structures and
involutive distributions of arbitrary corank by introducing symmetrizing
factors. The role of these symmetrizing factors on the integrability by
quadratures of the Pfaffian equations associated with the \cinf-structure is
also established. Some examples that show how these objects and results can be
applied in practice are also presented
-symmetries of distributions and integrability
An extension of the notion of solvable structure for involutive distributions
of vector fields is introduced. The new structures are based on a
generalization of the concept of symmetry of a distribution of vector fields,
inspired in the extension of Lie point symmetries to
-symmetries for ODEs developed in the recent years.
These new objects, named -structures, play a
fundamental role in the integrability of the distribution: the knowledge of a
-structure for a corank involutive distribution
permits to find its integral manifolds by solving successive completely
integrable Pfaffian equations. These results have important consequences for
the integrability of differential equations. In particular, we derive a new
procedure to integrate an th-order ordinary differential equation by
splitting the problem into completely integrable Pfaffian equations. This
step-by-step integration procedure is applied to integrate completely several
equations that cannot be solved by standard procedures
Rigidity results for complete spacelike submanifolds in plane fronted waves
New rigidity results for complete non-compact spacelike submanifolds of arbitrary codimension in plane fronted waves are obtained. Under appropriate assumptions, we prove that a complete spacelike submanifold in these spacetimes is contained in a characteristic lightlike hypersurface. Moreover, for a complete codimension two extremal submanifold in a plane fronted wave we show sufficient conditions to guarantee that it is a (totally geodesic) wavefront.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBU
Ultrametric spaces, valued and semivalued groups arising from the theory of shape
In this paper we construct many generalizad ultrametrics in the sets of shape morphisms between topological spaes. We recognize a topology in these sets which is independen on the shape representation of the spaces. We construct valuations an semivaluations on groups of shape equivalences and on n-th shape groups. We also connect shape theory, for arbitrary topological spaces, with the algebraic theory of generalized ultrametric spaces developed by S. Priess-Crampe and P. Ribenboim among other authors
Academic Burnout, Personality, and Academic Variables in University Students
This study examines academic burnout syndrome and its relation to personal and academic variables among university students in nursing and early childhood education programs in Spain. A total of 606 university students (primary education: 49.7%; nursing: 49.7%) of both sexes (71.5% female) with an average age of 20.68 years (SD = 1.65) participated. An ex post facto retrospective single-group design was planned. The instruments used were the Maslach Burnout Inventory-Student Survey (MBI-SS) and the NEO Five-Factor Inventory (NEO-FFI). Nursing students, who reported more study hours, less sleep, and lower grades, had higher academic burnout scores. Linear regression models were proposed to analyze the relationship between academic burnout, personality, and sociodemographic variables. Nursing students scored higher in emotional exhaustion and lower in cynicism, and they scored higher in neuroticism and openness. Furthermore, 16.1% of the variance in academic burnout was explained by personality variables as well as the degree studied, course year, and study hours. These findings suggest the importance of considering both academic and personality variables in understanding academic burnout in university students
Aplicación de técnicas SIG en el estudio de evaluación de degradación de suelos. Mazarrón (Murcia)
El objetivo general de este estudio ha sido evaluar el estado actual y los cambios que se han producido en
algunas características edáficas del área de Mazarrón (Murcia) en un periodo de 20 años, en relación con los
procesos de degradación. Para ello se han utilizado los resultados de dos muestreos de suelos realizados en
un intervalo de veinte años (1988 y 2008). Se han analizado algunas de las características edáficas que más
relación tienen con la vulnerabilidad de los suelos a la erosión (Textura, Materia orgánica y Pedregosidad) y de
las cuales se disponía de datos en los dos muestreos.
Para la creación y análisis de la información espacial se han empleado dos Sistemas de Información
Geográfica de software libre. Uno de ellos ha sido GvSIG, desarrollado por la Generalitat Valenciana y el
programa GRASS. La metodología SIG empleada ha sido una herramienta fundamental para obtener la serie
de capas de variables edáficas para los años 1988 y 2008.
Los resultados muestran como el área de estudio es bastante vulnerable a los procesos erosivos, sobre
todo por erosión hidrica y antrópica, debido a las características de sus suelos. Riesgo que se incrementaría si
en futuro se abandonaran los cultivos.The main objetive of these study is to evaluate the current situation and the changes ocurred in some
edaphic characteristics of the soils in the Mazarrón area (Murcia) in a twenty years period, in relation with the
degradation processes. For these propose we have used the results of two soils samples carried out in a
twenty years intervale (1988 and 2008). The caracteristics more related with the vulnerability of the soil
erosion (texture, organic matter and stoniness) of wich we had data of the two samples were evaluated.
Two Geografical Information System of free software have been used for the creation and analisis of the
espacial information. One of these was GvSIG, developed by Generalitat Valenciana and GRASS programme.
The GIS methodology carried out was a fundamental tool to obtain edaphic variables layers for the years 1988
and 2008.
The results show how the study area is very sensible to the erosive processes, specialy by hidric and
antropic erosion, because soil caracteristics. This hazard would increase in a future if the land was
abandoned
Google es noticia. Transformación de los marcos informativos sobre Google en la prensa española
Fundada en 1998, en menos de veinte años, Google se ha convertido en una de las mayores multinacionales del mundo. Esta investigación estudia las informaciones periodísticas sobre Google, desde la perspectiva de la teoría del encuadre (framing). La pregunta propuesta es: ¿Ha cambiado la imagen que la prensa española proyecta sobre Google desde los inicios de la compañía a los últimos años? Para responder, se ha hecho un análisis de contenido de todos los textos periodísticos sobre Google publicados en 2004 y 2014 por “El País”, “El Mundo”, “ABC” y “La Vanguardia”. Mediante un protocolo de análisis, se han detectado los marcos informativos –news frames– presentes en cada texto periodístico. Los resultados de la investigación ponen de manifiesto que se ha producido una transformación de los marcos informativos sobre Google: de ser mayoritariamente positivos para la compañía estadounidense, a ser negativos. También se ha detectado que, en 2004, las informaciones sobre la empresa ponían el foco en cuestiones de tipo económico; mientras que, en 2014, los periódicos analizados prefirieron atribuir a Google la responsabilidad de una serie de problemas. El texto concluye que Google ya no es enmarcada por los principales diarios sólo como una empresa tecnológica que logra excelentes resultados económicos, sino como una compañía cuyas actividades afectan –con frecuencia, negativamente– a determinadas personas, grupos humanos y a otras compañías
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