731 research outputs found
WRF simulation of the atmospheric conditions in some aircraft accidents
Aviation, probably more than any other mode of transportation, is greatly affected by weather. Commercial aviation must deal with storms, fogs, windshears, ash from the volcanoes, intense rain, turbulences and other weather phenomena regularly. In this document are exposed in detail the effects of these phenomena on the aircraft's performance and on the airport facilities. Additionally, it is performed too, a study of the impact that these weather phenomena have had in aviation in the period from 1967 to 2010 at global level. The study shall, in particular, analyze the impact of these phenomena on the number of accidents per year and the number of fatalities per year, according to the phase of flight, the climatic zone and the meteorological seasons. As result of the analysis, it is necessary to note, that the number of accidents due to unfavorable weather conditions represent 40,7 % of the events, which occurred during this period and has a clear descending evolution since the 1990s. Most accidents and fatalities take place during the take-off, climb, approach and landing stages. During these phases aircrafts are close to the ground and in a more vulnerable configuration than during other flight phases, also a external perturbation induced by low visibility, fog, or rain can crash the aircraft. During the enroute phase of flight, turbulences, CATs and storms are especially hazardous to modern jet aircrafts structures. The probability to suffer an accident increases in temperate zones during the approach phase in winter. The eruption of Mount Pinatubo in 1991, which raised the number of accidents for meteorological reasons in 1993 to 47, altered the Earth's climate (Arctic Oscillation) specifically in the high latitudes of the temperate zones, leading to the appearance and disappearance of meteorological phenomena on atypical regions. The study of the University of Reading, which used the same turbulence models that air traffic controllers use every day, found that the frequency of turbulence on the many flights will double by 2050 and its intensity increase by 10-40%. That's a reason to investigate more; we have to know better our atmosphere. Additionally it is studied the case of the accident of AF447 of June 1, 2009 with the help of the WRF model, remarking through this relatively current example, the affect of the weather phenomena on the modern aircraft. Therefore, the primary aim of this study is to prove, that aircraft remain dependent on weather conditions.Las aeronaves comerciales que transportan pasajeros
se enfrentan
diariamente
a tormentas, nieblas, vientos de cizalla, cenizas de volcán, lluvias
intensas
, turbulencias
y otros
fenómenos
meteorológicos
que dejan a los
pasajeros con el corazón en un puño
en el mejor de los casos.
E
n e
l presente documento
,
se exponen detalladamente, cuáles son los efectos
de estos fenómenos sobre las performances de la aeronave y de las
instalaciones aeroportuarias.
Complementariamente se
realiza un estudio sobre
el impacto
que han tenido
estos
fenómenos meteorológicos en la seguridad aérea
, a nivel mundial, en el
período de 1967 a 2010. En concreto se analiza su repercusión sobre el
número de accidentes aéreos
y
el número de fallecidos, en función de la fase
de vuelo, de la zona climática del p
laneta y de la estaci
ón del año.
Como
resultado del análisis
,
se observa que la siniestralidad aérea por causas
atmosféricas
,
representa el 40,7% de los sucesos
,
ocurridos durante este
período y tiene además una clara evolución descendente desde la década
de
los 90. Las causas más importantes
durante las fases de vuelo cercanas a
tierra son la baja visibilidad, la niebla, y la lluvia, mientras que para mayor
altitud lo son las turbulencias, las CATs y las tormentas
.
Respecto a la
distribución
,
se obtiene qu
e la probabilidad de sufrir un accidente, aumenta
durante el invierno en las zonas templadas, corriendo especialmente riesgo
durante la fase de aproximación.
Para corroborar la influencia de la meteorología en la aviación
,
también se
ha
analizado la erup
ción
del Monte Pinatubo de 1991, que elevó el número de
accidentes aéreos por causas meteorológicas en 1993 a 47, alterando el clima
del planeta (oscilación ártica), especialmente en las latitudes altas de las
zonas templadas, provocando la aparición y des
aparición de fenómenos
meteorológicos en regiones atípicas.
Exponiéndose también
,
que a partir de
2050 como consecuencia del calentamiento global y la
mayor concentración
de
CO2
en la atmosfera
,
las aeronaves encontrará
n con mayor frecuencia e
intensidad t
urbulencias durante la fase de crucero.
Adicionalmente se estudia el caso del accidente de
l AF447 del 1 de Junio de
2009
mediante el modelo WRF
,
remarcándose mediante este ejemplo relativamente actual, la vulnerabilidad todavía existente de las aeronaves
modernas
ante
fenómenos meteorológicos
como el engelamiento unido a las
malas decisiones de los pilotos y a unos criterios de certificación de las sondas
de Pitot que no se ajustan a los parámetros que se encuentran realmente en la
alta troposfera.
Por
lo tanto, e
l objetivo principal de este trabajo es demostrar que a
pesar de
los avances tecnológicos, la formación sistemática de los pilotos, y la mejora
en el conocimiento de la atmosfera,
las aerona
ves actuales siguen
dependiendo
aunque en menor medida
,
de las condicione
s del medio en el
que se mueven
, siendo necesario seguir investigando para conocer mejor la
atmosfera
Búsqueda y evaluación de emplazamientos óptimos para albergar instalaciones de energías renovables en la costa de la Región de Murcia: combinación de Sistemas de Información Geográfica (SIG) y Soft Computing
[SPA] Las instalaciones de energías renovables (EERR), impulsadas inicialmente por un marco legislativo favorable, por la necesidad de disminuir la dependencia energética de combustibles fósiles y, posteriormente por una evolución progresiva extraordinaria, han experimentado una creciente expansión y desarrollo en el sector energético español en las últimas décadas. La búsqueda y selección de emplazamientos óptimos para implantar instalaciones de EERR, no sólo requiere disponer de un grupo de asesoramiento capaz de evaluar y analizar las diferentes alternativas, sino que resulta conveniente aplicar un conjunto de herramientas y métodos que faciliten el proceso de tomas de decisiones. El problema de localización de instalaciones de energías renovables es un problema complejo, dado que se necesitan manejar gran variedad de criterios de distinta índole y procedencia, así como evaluar en la mayoría de los casos un gran número de alternativas. Para ello, los métodos de decisión multicriterio constituyen la metodología principal para abordar este problema combinándolos por un lado con los Sistemas de Información Geográfica que, nos servirán de soporte de base de datos a nuestra problema y por otro con las herramientas de Soft Computing aplicadas en las propias metodologías de decisión que, les confieren a éstas el modelado de la incertidumbre y la vaguedad de los datos que se manejan en este tipo de problemas. En particular y como ejemplo de aplicación, en la presente investigación se propone la combinación de distintas metodologías de decisión multicriterio con Sistemas de Información Geográfica como soporte de base de datos, y el Soft Computing y en concreto la lógica difusa con el objetivo de evaluar y clasificar los emplazamientos óptimos de instalaciones de EERR en la costa de la Región de Murcia.[ENG] Renewable energy facilities, initially driven by a favourable legislative framework due to the need to reduce energy dependence on fossil fuels and later by a progressive extraordinary evolution, have experienced an increasing expansion and development in the Spanish energy sector in recent decades. The search and selection of optimal locations to implant renewable energy facilities, requires not only to have an advisory group able to assess and analyze alternatives, but it is appropriate to apply a set of tools and methods to facilitate the decision making process. The locating problem of renewable energy facilities is a complex problem because it needs to handle a great variety of criteria with different nature and origin, as well as to evaluate, in most cases, a large number of alternatives. For this, multicriteria decision methods are the main methods to tackle this problem by combining them, on the one hand with Geographic Information Systems that will be used as support database to our problem, and on the other hand, with Soft Computing tools applied in the own decision methodologies which give them the uncertainty modeling and vagueness of the data used in this type of problems. In particular and as an example of application, in this investigation the combination of multicriteria decision methods with Geographic Information Systems is proposed as support database, and Soft Computing (specifically the Fuzzy Logic) for the search and evaluation of optimal locations to implant renewable energy facilities on the coast of the Region of Murcia.Universidad Politécnica de Cartagen
Caracterización del comportamiento hidrológico del rio Aragón en su parte alta. Estudio de sus crecidas y su afección en distintos núcleos de población
Se realiza un estudio del comportamiento hidrológico del rio Aragón en su parte alta (Huesca, España), es decir, desde su nacimiento al inicio de su curso medio. A partir de los datos de las estaciones de aforo de Canfranc-Estación, Canfranc y Jaca, se hace un análisis de las crecidas del río a lo largo del tiempo para evaluar el riesgo que han producido, y pueden producir, en las localidades de Canfranc-Estación, Canfranc, Castiello de Jaca y Jaca. Se incluyen una serie de mapas que señalan las áreas inundables del rio a su paso por estas localidades. Finalmente, se ofrecen una serie de propuestas y sugerencias para reducir el riesgo al que están expuestos estos pueblos y evitar posibles consecuencias dramáticas
An alternative Drum test method to UNECE Regulation 117 for measuring tyre/road noise under laboratory controlled conditions
Tyre/road sound emissions have been proved to be the main source of noise caused by road traffic when
traveling at medium and high speeds (Sandberg and Ejsmont, 2002). Tyre/road noise has been widely
studied among the last decades. However, an important part of this research has been focused, mainly,
on track tests. Different track or road methods have been developed for measurement of tyre/road sound
emissions. The most important ones are the Coast-By, the Close-Proximity, the Statistical Pass-By or the
Controlled Pass-By methods. Among all of them, the Coast-By method has been raised in Europe as standard
method concerning the approval of tyres with regard to tyre/road sound emissions as preconized in
UNECE Regulation 117 (2007)[2]. However, all the above mentioned methods have several disadvantages
such as the influence of environmental factors, the different results that can be obtained depending on
the test track or the vehicle upon which the tests are carried out, the lack of repeatability or, the most
important aspect, which is the limitation of the measured magnitude, the sound pressure level.
A new methodology (Clar-Garcia et al., 2016) based on drum tests and the ISO 3744 (1994), which was
developed in order to avoid these limitations, has been proved to be comparable to the Coast-By (CB)
method. This paper describes how different tyres have been tested according to both the CB and the
new Alternative Drum test method (A-DR) while their results have been compared. In order to be able
to carry out this comparison, as the measured magnitudes and test conditions differ widely from one test
to another, the standardised ISO 9613 sound propagation method (ISO 9613-2, 1996) has been applied to
obtain the sound pressure value at 7.5 m from the sound power level of a tyre measured under
laboratory-controlled conditions when rolling against a drum. Results have shown that both methods
are not only comparable but also have remarkably similar sound spectra and, for that reason, the new
methodology based on drum tests can be used in order to obtain tyre/road noise emission approved
values
Consideraciones clínicas sobre la resorción radicular externa por impactación dentaria
[email protected] resorción externa por presión (RREP) consiste en una pérdida de tejido dentinario y cementario de las raíces
dentarias que se origina a nivel del ligamento periodontal, ocasionada por presiones prolongadas y mantenidas
sobre la raíz. Presentamos tres casos con diferente repercusión y tratamiento. Según el distinto grado de afectación
se describe y clasifica el tratamiento de RREP a causa de dientes impactados. En cuanto a la restauración
de RREP se perfila la cavidad clase V de diseño 5 y el empleo de cermet o amalgamas de plata para su relleno.Pressure external root resorption (PERR) is a loss of dental root tissues (dentine and cementum) that begin in the
periodontal area caused by a impacted teeth. We show three cases with differents clinical situations and therapeutical
aspects. Pulpal injurie and difficulty in the post-endodontic cavity acces are characteristiques of these processes.
Depending on the level of tissue destruction we discusse the therapeutical orientation in each case. Some
treatments like class V type 5 cavities or fillings with cermet glass-ionomer in the more atipical situations (generally
after an endodontic treatment) are a good choice in these [email protected]
[email protected]
Spatio-temporal dynamic clustering modeling for solar irradiance resource assessment
Nowadays, with the development of international policies and agreements to promote the integration of renewable energy sources, mainly solar and wind, modeling the solar resource by including the spatio-temporal variability is crucial to determine future PV power plant locations and estimate potential power generation performances. However, contributions involving long-term periods and different time windows to explore such potential solar resource variability are generally scarce. Under this framework, the present paper proposes a methodology focused on characterizing and clustering the spatio-temporal solar resource variability through the global horizontal irradiance analysis. Hierarchical clustering technique is firstly used to classify the spatial data. Different time windows — from short-term to long-term data — can be subsequently evaluated by using various sources of information. The Spanish territory is selected as case study, considering 22-year period data (1999–2020) and 1,936,917 observations from online satellite database. Spatial variability and geographical clustering differences are discussed and compared depending on the selected time windows, identifying relevant spatial variations for some specific months. Additionally, some years present more variability as well, in line with the sunspot peak of the solar cycles. The proposed approach gives an alternative comprehensive spatio-temporal clustering and characterization of GHI evolution, providing a suitable methodology to help the current European sustainable energy transition.These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program, United States. The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
This work was partially funded by the research project PID2020–112754GB–I00, financially supported by the Ministerio de Ciencia e Innovación (Spain)
TBT e imposex en Galicia: los efectos de un disruptor endocrino en poblaciones de gasterópodos marinos
En este artículo se resume la experiencia de nuestro grupo de investigación en el campo de los efectos de un disruptor endocrino
androgenizante (el tributilo de estaño, más conocido como TBT por su abreviatura del inglés tributyltin) en gasterópodos marinos del
litoral gallego. Nuestras investigaciones sobre este tema comenzaron en 1996 y continúan en la actualidad. Después de una breve
introducción sobre qué es el TBT y su problemática, se resumen los principales hallazgos conseguidos con nuestro trabajo, que se
basan principalmente en el estudio de los efectos en el gasterópodo carnívoro Nucella lapillus con alguna información adicional para
otras especies como el carroñero Nassarius reticulatus. Nuestro trabajo abarca tanto la bioacumulación de contaminante, la
manifestación de un biomarcador específico de los efectos del TBT (masculinización de hembras, conocido como imposex) en
poblaciones naturales y en experiencias de trasplante, el estudio de la presencia de individuos genéticamente más resistentes a los
efectos del TBT y algunos datos de ecología molecular sobre la estructuración poblacional y capacidad de dispersión de Nucella lapillus
Identification and selection of potential sites for onshore wind farms development in Region of Murcia, Spain
It is often advisable to combine spatial representation tools such as Geographic Information Systems (GIS) with Multi criteria Decision Making Methods (MCDM) when solving location complex problems. The current case refers to the search for and selection of sites for onshore wind farms on the coast of the Region of Murcia, in the southeast of Spain. When resolving the proposed problem, the legal restrictions and the criteria (wind speed, area, slope, etc.) that influence the location will be considered. These will be defined in the form of thematic layers that will be entered into the GIS. Restrictions will be imposed taking into account the legislative framework of the study area so that, through their analysis and editing, it will be possible to reduce the initial area and obtain suitable sites where this type of facilities can be installed. Moreover, as the objective of the study is to select the locations and obtain a ranking two different models will be applied, initially a categorical assessment through a lexicographic order will be performed using the tools available in the GIS and, later it will be applied the ELECTRE-TRI methodology will be applied in order to make a comparison between the methods.This work is partially supported by FEDER funds, the DGICYT and Junta de Andalucía under projects TIN2011-27696-C02-01 and P11-TIC-8001, respectively
Low-Cost Surface Classification System Supported by Deep Neural Models
Determining the surface on which a vehicle is moving is vital information for im-proving active safety systems. Performing the surface classification or estimating adherence through tire slippage can lead to late action in possible risk situations. Currently, approaches based on image, sound, or vibration analysis are emerging as a viable alternative, though sometimes complex. This work proposes a methodology based on the use of low-cost accelerometers combined with Deep Learning tech-niques. The performance of the proposed system is evaluated with real tests, where high percentages of accuracy are obtained in the classification task.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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