1,989 research outputs found
Diseño, construcción y realización de ensayos en vuelo de un aeromodelo DLG (Discus Launch Glider)
Este trabajo tiene por objeto el diseño, la construcción y la realización de ensayos en vuelo de un aeromodelo DLG (Discus Launch Glider). A tal efecto, se han expuesto el nacimiento y la regulación de esta disciplina del aeromodelismo conocida por las siglas F3K. A partir de los requerimientos técnicos, se enumeran las soluciones constructivas posibles y se justifica la opción finalmente adoptada. A continuación se describe en detalle el proceso constructivo de nuestro prototipo. El TFG concluye con descripción y valoración de las primeras pruebas de vuel
AATR an ionospheric activity indicator specifically based on GNSS measurements
This work reviews an ionospheric activity indicator useful for identifying disturbed periods affecting the performance of Global Navigation Satellite System (GNSS). This index is based in the Along Arc TEC Rate (AATR) and can be easily computed from dual-frequency GNSS measurements. The AATR indicator has been assessed over more than one Solar Cycle (2002–2017) involving about 140 receivers distributed world-wide. Results show that it is well correlated with the ionospheric activity and, unlike other global indicators linked to the geomagnetic activity (i.e. DST or Ap), it is sensitive to the regional behaviour of the ionosphere and identifies specific effects on GNSS users. Moreover, from a devoted analysis of different Satellite Based Augmentation System (SBAS) performances in different ionospheric conditions, it follows that the AATR indicator is a very suitable mean to reveal whether SBAS service availability anomalies are linked to the ionosphere. On this account, the AATR indicator has been selected as the metric to characterise the ionosphere operational conditions in the frame of the European Space Agency activities on the European Geostationary Navigation Overlay System (EGNOS). The AATR index has been adopted as a standard tool by the International Civil Aviation Organization (ICAO) for joint ionospheric studies in SBAS. In this work we explain how the AATR is computed, paying special attention to the cycle-slip detection, which is one of the key issues in the AATR computation, not fully addressed in other indicators such as the Rate Of change of the TEC Index (ROTI). After this explanation we present some of the main conclusions about the ionospheric activity that can extracted from the AATR values during the above mentioned long-term study. These conclusions are: (a) the different spatial correlation related with the MOdified DIP (MODIP) which allows to clearly separate high, mid and low latitude regions, (b) the large spatial correlation in mid latitude regions which allows to define a planetary index, similar to the geomagnetic ones, (c) the seasonal dependency which is related with the longitude and (d) the variation of the AATR value at different time scales (hourly, daily, seasonal, among others) which confirms most of the well-known time dependences of the ionospheric events, and finally, (e) the relationship with the space weather events.Postprint (published version
Destinos turísticos: la percepción de los turistas extranjeros sobre la "Marca España"
Este trabajo se basa en las tendencias e implicaciones en la gestión de la marca en un sector emergente que crece y se renueva con el paso de los años, el sector turístico, haciendo hincapié en la imagen de España hacia el exterior. Se pretende explicar el funcionamiento de los destinos turísticos y la importancia de los mismos, en general, y en el caso particular de España. Asimismo, mediante un estudio empírico realizado a una muestra de turistas extranjeros se desea averiguar sus hábitos de consumo respecto al turismo, así como la percepción que tienen de España como destino vacacional. Los resultados obtenidos en este estudio son de interés para identificar los puntos fuertes y débiles de la marca España en el mercado internacional. En cuanto a los resultados, este trabajo muestra mediante su estudio empírico la buena imagen que los extranjeros tienen sobre nuestro país, es decir, de alguna forma verifica o respalda el trabajo que desde las instituciones como “Marca España” se está realizando para situar a España en la cúspide del turismo mundial
USO DE REMIFENTANILO – SEVOFLURANO EN EL MANEJO DEL DESPERTAR POSTOPERATORIO INMEDIATO E INTERMEDIO
Los efectos producidos por el sevoflurano son dosis dependientes, por lo que, para evitar sus efectos adversos, destacando la agitación al despertar, hay que administrar la mínima dosis posible de sevoflurano. En su lugar, se deben utilizar otros fármacos que potencien el efecto anestésico. La asociación de un opiáceo al sevoflurano en la inducción y mantenimiento anestésicos tiene un efecto sinérgico y, el remifentanilo, por sus propiedades farmacocinéticas podría considerarse el opiáceo ideal. El objetivo de este trabajo es evaluar el despertar postoperatorio inmediato e intermedio al usar de forma sinérgica remifentanilo-sevoflurano a la mínima CAM posible ajustada a BIS 40-60frente a los pacientes que presentan una CAM mayor. Este trabajo se trata de un protocolo de un ensayo clínico, con la intención de presentar sus resultados como tesis doctoral. Se llevará a cabo un estudio prospectivo de aleatorización simple en el Servicio de Anestesiología y Reanimación del Hospital Universitario Miguel Servet (HUMS). La utilización de remifentanilo-sevoflurano es utilizada en anestesia con frecuencia, por ser segura, práctica y costo-efectiva. Sin embargo, las dosis utilizadas por los anestesistas varían. Algunos especialistas utilizan el remifentanilo a dosis bajas dentro del margen de seguridad del fármaco, lo que precisa un aumento de la CAM de sevoflurano para poder alcanzar la profundidad anestésica adecuada. La administración de una CAM elevada de este fármaco (incluso dentro de su margen de seguridad) puede producir enlentecimiento en el despertar, así como estado de agitación del paciente en el postoperatorio.Palabras clave: Sevoflurano, Remifentanilo<br /
Towards the Enactment of Learning Situations Connecting Formal and Non-Formal Learning in SLEs
Producción CientíficaSmart Learning Environments hold promise of adapting learning processes to the individual context of students and connecting formal with non-formal learning. To do so, SLEs need to know the current context of the students, regardless of the physical or virtual space where learning takes place. This paper presents an architecture that assists in the deployment and enactment of learning situations across-spaces, able to sense and react to changes in the students’ context in order to adapt the learning process.ICSLE 2019: International Conference on Smart Learning EnvironmentsAgencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (projects TIN2014-53199-C3-2-R / TIN2017-85179-C3-2-R)Comisión Europea (project 588438-EPP-1-2017-1-EL-EPPKA2-KA
Path-moose: a scalable all-path bridging protocol
This paper describes Path-Moose, a scalable tree-based shortest path bridging protocol. Both ARP-Path and Path-Moose protocols belong to a new category of bridges that we name All-path, because all paths of the network are explored simultaneously with a broadcast frame distributed over all network links to find a path or set a multicast tree. Path-Moose employs the ARP-based low latency routing mechanism of the ARP-Path protocol on a bridge basis instead of a per-single-host basis. This increases scalability by reducing forwarding table entries at core bridges by a factor of fifteen times for big data center networks and achieves a faster reconfiguration by an approximate factor of ten. Reconfiguration time is significantly shorter than ARP-Path (zero in many cases) because, due to the sharing of network paths by the hosts connected to same edge bridges, when a host needs the path it has already been recovered by another user of the path. Evaluation through simulations shows protocol correctness and confirms the theoretical evaluation results.This work was supported in part by grants from Comunidad
de Madrid and Universidad de Alcal´a through the following
projects: MEDIANET-CM (S-2009/TIC-468), EMARECE
(PII1I09-0204-4319) and CMAC (UAH2011/EXP-016).Publicad
Feasibility of precise navigation in high and low latitude regions under scintillation conditions
Scintillation is one of the most challenging problems in Global Navigation Satellite Systems (GNSS) navigation. This phenomenon appears when the radio signal passes through ionospheric irregularities. These irregularities represent rapid changes on the refraction index and, depending on their size, they can produce also diffractive effects affecting the signal amplitude and, eventually producing cycle slips. In this work, we show that the scintillation effects on the GNSS signal are quite different in low and high latitudes.
For low latitude receivers, the main effects, from the point of view of precise navigation, are the increase of the carrier phase noise (measured by s¿) and the fade on the signal intensity (measured by S4) that can produce cycle slips in the GNSS signal. With several examples, we show that the detection of these cycle slips is the most challenging problem for precise navigation, in such a way that, if these cycle slips are detected, precise navigation can be achieved in these regions under scintillation conditions.
For high-latitude receivers the situation differs. In this region the size of the irregularities is typically larger than the Fresnel length, so the main effects are related with the fast change on the refractive index associated to the fast movement of the irregularities (which can reach velocities up to several km/s). Consequently, the main effect on the GNSS signals is a fast fluctuation of the carrier phase (large s¿), but with a moderate fade in the amplitude (moderate S4). Therefore, as shown through several examples, fluctuations at high-latitude usually do not produce cycle slips, being the effect quite limited on the ionosphere-free combination and, in general, precise navigation can be achieved also during strong scintillation conditions.Postprint (published version
A hybrid numerical-experimental strategy for predicting mechanical response of components manufactured via FFF
In this paper a new methodology developed for predicting the mechanical performance of the structures additively manufactured by Fused Filament Fabrication is presented. The novelty of the approach consists in accounting for the anisotropy in the material properties induced by the printing patterns. To do so we partition the manufactured structure according to the printing patterns used in a single component. For determining the material properties of each partition, a hybrid experimental/computational characterization is proposed. The external partitions with aligned (contour) and crossed (cover) filaments are characterized through uniaxial tensile tests on General Purpose Acrylonitrile Butadiene Styrene dog-bone samples with corresponding patterns. Characterization of the inner structure (infill/lattice) is done through computational homogenization technique using Representative Volume Element. The presented methodology is validated against experimental results of square cross-section demonstrators. It is shown that the material properties depend on the geometrical relationship of the different printing patterns, exclusively. Therefore, the exhaustive experimental procedure can be avoided characterizing the printed material by a pre-defined anisotropic constitutive relationship proportional to the properties of the raw material. Moreover, the acquired geometrical relationship is validated for components made of Polylactic Acid. The given methodology may be used as design-for-manufacture tool for creating functional components."Narges Dialami is a Serra Húnter Fellow.
This work has been supported by the RIS3CAT Llavor 3D Community co-financed by the Generalitat de Catalunya (ACCIÓ) through the projects TRANSPORT COMRDI16-1-0010 - 00 and PRO2 COMRDI16-1-0009-04.
Financial supports from the European Union’s horizon 2020 research and innovation programme (H2020-DT-2019-1 No. 872570) under the KYKLOS 4.0 Project (An Advanced Circular and Agile Manufacturing Ecosystem based on rapid reconfigurable manufacturing process and individualized consumer preferences) and from the Ministry of Science, Innovation and Universities (MCIU) via: the PriMuS project (Printing pattern based and MultiScale enhanced performance analysis of advanced Additive Manufacturing components, ref. num. PID2020-115575RB-I00) are gratefully acknowledged.
The financial support from the Spanish Ministry of Economy and Competitiveness, through the Severo Ochoa Programme for Centres of Excellence in R&D (CEX2018-000797-S), is gratefully acknowledged as well as from CONCYTEC R + D (Project Reference: 163-2017-FONDECYT, in association with Pontifical Catholic University of Perú and CIMNE) -” Optimización del uso de polímeros sintéticos en procesos de manufactura aditiva mediante modelos de simulación computacional y técnicas de caracterización de materiales. Caso de estudio: aplicaciones médicas - prótesis de mano.”."Peer ReviewedPostprint (published version
Electro-welded lattice reinforcement in reinforced concrete ribbed slabs
U radu se provodi eksperimentalna provjera posmične čvrstoće montažnih betonskih rebrastih ploča različitih visina s električno zavarenom armaturnom rešetkom. Prikazano je tehničko obrazloženje korištenja visokih rešetki u armaturi montažnih lakih rebrastih ploča u obliku dvostrukog slova T i montažnih armiranobetonskih ploča debljine 30 cm. Utvrđeno je da je doprinos betona posmičnoj čvrstoći uvijek veći od vrijednosti koje se mogu očekivati prema španjolskim normama. Osim toga, kako se niske rešetkaste rebraste ploče odlikuju nižim vrijednostima granične posmične čvrstoće od onih koje se očekuju prema normama, utvrđeno je da se treba osigurati odgovarajuća visina rešetaka u rebrastim pločama kako bi se osiguralo sidrenje tlačne zone te razvoj mehanizama štapova i zatega. Zato se u armiranobetonskim rebrastim pločama svakako preporučuje korištenje rešetkastih nosača na otprilike 80 % visine uzorka kada dužina pojasa rešetke iznosi 20 cm.Shear strength of precast concrete ribbed slabs reinforced with electro-welded lattice girders of variable height is experimentally verified. Technical justification is given for the use of high latticework in the reinforcement of precast lightweight double-tee ribbed slabs and precast reinforced concrete slabs 30 cm in thickness. It was established that the contribution of concrete to shear strength was always higher than the expected values according to Spanish standards. Furthermore, as low lattice ribbed slabs exhibited lower ultimate shear strength values than the ones expected based on the standards, the need arose to provide an adequate height of lattices in ribbed slabs to ensure anchorage of the compressed area in order to develop the strut-and-tie mechanisms. Consequently, lattice girders with approximately 80% of specimen height are highly recommended in reinforced concrete ribbed slabs, when the length of lattice chords is 20 cm
Un CMS orientado a la gestión de recursos didácticos
Los sistemas de gestión de contenidos CMS (Content Management System) se han convertido en parte vital de Internet, actualmente se utilizan no sólo para crear WEBs corporativas, sino también para la creación de laboratorios virtuales, control de laboratorios de forma remota, campos virtuales, etc. En nuestro caso concreto, se quieren aplicar para crear sitios WEB que ayuden en la gestión de asignaturas basadas en Laboratorios Virtuales. En el grupo de trabajo Tecnologías para el Aprendizaje Activo (NTA2), patrocinada por la Universidad Politécnica de Valencia (UPV), se pretende analizar el estado de la cuestión de: Docencia presencial, evaluación, aprendizaje colaborativo, laboratorio remoto, laboratorios virtuales y gestión de proyectos. Como factor común, todas estas áreas requieren un CMS. Es cierto que actualmente se encuentran disponibles en Internet una infinidad de CMS gratuitos y comerciales. La pregunta obvia a realizar es ¿Porqué reinventar lo hecho y tratar de hacer un CMS? La respuesta es tan simple como el contar con el control total de un CMS que nos permita estudiar la mejor forma de crear Laboratorios Virtuales que sean útiles en las asignaturas impartidas en la UPV
- …