6,760 research outputs found
Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties
Understanding the nature of spiral structure in disk galaxies is one of the
main, and still unsolved questions in galactic astronomy. However, theoretical
works are proposing new testable predictions whose detection is becoming
feasible with recent development in instrumentation. In particular, streaming
motions along spiral arms are expected to induce azimuthal variations in the
chemical composition of a galaxy at a given galactic radius. In this letter we
analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D
chemical composition and H line-of-sight velocity distribution. We find
that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of
tangentially-slower, radially-outward (tangentially-faster, radially-inward)
streaming motions of metal-rich (poor) gas over a large range of radii. These
results show direct evidence of gas radial migration for the first time. We
compare our results with the gas behaviour in a -body disk simulation
showing spiral morphological features rotating with a similar speed as the gas
at every radius, in good agreement with the observed trend. This indicates that
the spiral arm features in NGC 6754 may be transient and rotate similarly as
the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September
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Hallazgo de una nueva columna miliaria perteneciente a la Via Augusta
By means of this article we let you know about the discovery of a new milliary column which belonged to the Roman Via Augusta. It has been found in the environs of La Torrecilla industrial area close to Córdoba. Its chronology based upon epigraphic analysis allow us to date it in the early years of Nero mandate.Mediante este artículo damos a conocer una nueva columna miliaria correspondiente a la Via Augusta y hallada en las inmediaciones del Polígono Industrial de La Torrecilla. Su cronología, basada en el análisis epigráfico, nos permite adjudicarla al emperador Nerón, en los primeros años de su mandato
Deep Learning-Based Fault Detection and Isolation in Solar Plants for Highly Dynamic Days
ICCAD'22: 2022- 6th International Conference on Control, Automation and Diagnosis, Lisbon, Portugal, July 13-15, 2022Solar plants are exposed to numerous agents that degrade and damage their components. Due to their large size and constant operation, it is not easy to access them constantly to analyze possible failures on-site. It is, therefore, necessary to use techniques that automatically detect faults. In addition, it is crucial to detect the fault and know its location to deal with it as quickly and effectively as possible. This work applies a fault detection and isolation method to parabolic trough collector plants. A characteristic of solar plants is that they are highly dependent on the sun and the existence of clouds throughout the day, so it is not easy to achieve methods that work well when disturbances are too variable and difficult to predict. This work proposes dynamic artificial neural networks (ANNs) that take into account past information and are not so sensitive to the variations of the plant at each moment. With this, three types of failures are distinguished: failures in the optical efficiency of the mirrors, flow rate, and thermal losses in the pipes. Different ANNs have been proposed and compared with a simple feedforward ANN, obtaining an accuracy of 73.35%.European Research Council 10.13039/50110000078
Causas y consecuencias de la corrosión de una tubería de acero galvanizado
Hot dip galvanising life as a corrosion protective coatings on steel depends basically on three factors: coatings quality (thickness), correct installation of the galvanised article, and weathering effects.
The aim of this research it is to study the decaying causes and effects of a plumbing installation made with hot dip galvanised steel tubes. The mentioned installation was of use during 30 years in the water supply system of the Parque Alcosa market (Sevilla, Spain). The research was divided in three parts: in the first one, shape analysis and XDR of internal decayed products was carried out: in the second one, physical properties were determined according to UNE 37- 505-89, corrosion morphology was conducted by metalographic microscopy, and it was evaluated also water quality: and finally, in the third one, diameter, section, and internal volume decrease was calculated in order to evaluate friction increase and pressure decrease in the installation.
The results obtained show the correct plumbing installation according to quality requirements (UNE 37-509-89), so corrosion causes are mainly attributed to an aggressive environment for the hot dip galvanising.La durabilidad de los galvanizados en caliente como recubrimientos protectores de la corrosión del acero dependen básicamente de tres factores: la calidad del recubrimiento (espesor), la correcta instalación del elemento galvanizado, y la agresividad del medio al que se encuentren expuestos.
En este trabajo se estudian las causas y consecuencias del deterioro sufrido por una tubería de acero galvanizado, destinada durante unos 30 años a la conducción de agua potable de la red en el mercado del Parque Al cosa (Sevilla). La investigación se ha dividido en tres etapas: en la primera, se ha realizado el análisis formal y la caracterización mediante DRX de los productos de alteración generados en el interior del tubo: en la segunda, se han determinado las características físicas del galvanizado según UNE 37-505-89, se ha estudiado la morfología del ataque corrosivo mediante microscopía metalográfica y se ha evaluado la calidad del agua circulante: y, por último, en la tercera, se han efectuado los cálculos relativos a la disminución real de diámetro, sección y volumen interno, así como consideraciones sobre la pérdida de carga generadas en la tubería.
Los resultados obtenidos indican que la tubería estaba correctamente instalada y cumplía los requisitos de calidad exigidos, por lo que las causas de su corrosión son atribuibles a la existencia de un medio agresivo para el galvanizado
A deep learning-based strategy for fault detection and isolation in parabolic-trough collectors
Solar plants are exposed to the appearance of faults in some of their components, as they are vulnerable to the action of external agents (wind, rain, dust, birds …) and internal defects. However, it is necessary to ensure a satisfactory operation when these factors affect the plant. Fault detection and diagnosis methods are essential to detecting and locating the faults, maintaining efficiency and safety in the plant. This work proposes a methodology for detecting and isolating faults in parabolic-trough plants. It is based on a three-layer methodology composed of a neural network to obtain a preliminary detection and classification between three types of fault, a second stage analyzing the flow rate dynamics, and a third stage defocusing the first collector to analyze thermal losses. The methodology has been applied by simulation to a model of the ACUREX plant, which was located at the Plataforma Solar de Almería. The confusion matrices have been obtained, with accuracies over 80% when using the three layers in a hierarchical structure. By forcing all the three layers, the accuracies exceed 90%.Unión Europea - Horizonte 2020 No 789 05
On interrelations between Sibgatullin's and Alekseev's approaches to the construction of exact solutions of the Einstein-Maxwell equations
The integral equations involved in Alekseev's "monodromy transform" technique
are shown to be simple combinations of Sibgatullin's integral equations and
normalizing conditions. An additional complex conjugation introduced by
Alekseev in the integrands makes his scheme mathematically inconsistent;
besides, in the electrovac case all Alekseev's principal value integrals
contain an intrinsic error which has never been identified before. We also
explain how operates a non-trivial double-step algorithm devised by Alekseev
for rewriting, by purely algebraic manipulations and in a different (more
complicated) parameter set, any particular specialization of the known
analytically extended N-soliton electrovac solution obtained in 1995 with the
aid of Sibgatullin's method.Comment: 7 pages, no figures, section II extende
Evaluating mountain goat dairy systems for conversion to the organic model, using a multicriteria method
Organic farming conserves natural resources, promotes biodiversity, guarantees animal welfare and obtains healthy products from raw materials through natural processes. In order to evaluate possibilities of increasing organic animal production, this study proposes a farm-scale multicriteria method for assessing the conversion of dairy goat systems to the organic model. In addition, a case study in the Northern Sierra of Seville, southern Spain, is analysed. A consensus of expert opinions and a field survey are used to validate a list of potential indicators and issues for assessing the conversion, which consider not only the European Community regulations for organic livestock farming, but also agroecological principles. As a result, the method includes 56 variables integrated in nine indicators: Nutritional management, Sustainable pasture management, Soil fertility and contamination, Weed and pest control, Disease prevention, Breeds and reproduction, Animal welfare, Food safety and Marketing and management. The nine indicators are finally integrated in a global index named OLPI (Organic Livestock Proximity Index). Application of the method to a case study with 24 goat farms reveals an OLPI value of 46.5% for dairy goat farms located in mountain areas of southern Spain. The aspects that differ most from the agroecological model include soil management, animal nutrition and product marketing. Results of the case study indicate that the proposed method is easy to implement and is useful for quantifying the approximation of conventional farms to an organic model
Estudio de senos craneales para la determinación del sexo
Se presenta un estudio sobre 106 cráneos
pertenecientes a la Colección de la Escuela de
Medicina Legal de Madrid, de población española
actual y sexo conocido a fin de estudiar si existen
diferencias en relación con el sexo en cuanto al número
de lóbulos y el área en mm de los senos frontales. Se
realiza estudio radiológico y de análisis de imagen
concluyendo que no existen diferencias en varones y en
mujeres en ninguno de los dos parámetros estudiados.We present a study about 106 crania which
belong to the collection of the Legal Medicine School
of Madrid, of current spanish population and known
sex to study if there are diferences related with sex
when it comes to talk about the number of lobes and
the area in mm between the cranial sinus. A
radiological and image analysis study is carried out
concluding that there are no differences in male and
female in both parametres studied
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