1,975 research outputs found
Modifying catalytically the soot morphology and nanostructure in diesel exhaust: Influence of silver De-NOx catalyst (Ag/Al2O3)
The influence of an Ag/Al2O3 HC-SCR catalyst on the morphological and nanostructural aspects of the exhaust particulate matter (PM) generated during the combustion of diesel fuel and a glycol ether–diesel fuel blend was addressed in this research work. In addition, the impact of in-cylinder fuel post injections (FPI) on the particulate formation pathway and on the catalytic de-NOx efficiency was also studied.
The tests were carried at low exhaust temperatures in the absence and presence of small amounts of hydrogen (H2). It is concluded that in the absence of H2, the catalyst does not modify the primary particle size (dp0) of the soot aggregates, while the aggregation of the soot particles throughout the catalyst channels is the main governing mechanism. The catalyst influence on the particulate structure was evident when H2 was introduced, with smaller dp0 seen downstream of the catalyst, indicating that despite the short residence time of the PM within the catalyst bed, the soot particles were partially oxidised. The use of late FPI reduces the exhaust PM level and delivers sufficient HC:NOx ratios that improves the catalyst activity up to a maximum of 80% NOx conversion, with no sign of catalyst deactivation when H2 (500 ppm) was injected. Furthermore, it is suggested that along with oxidising part of the particles produced during the main fuel injection phase, late FPI can also produce, to a lesser extent, some additional soot with a less matured structure, resulting on average in less ordered particles being emitted into the exhaust stream.
This work shows that in modern diesel engines, a silver catalyst can alter the soot structure in the exhaust in a way that can ease the diesel particulate filter (DPF) regeneration cycles, improve its filtration efficiency and help in effectively reducing the tailpipe NOx emissions. For the catalyst to perform these functions, multiple in-cylinder fuel injection strategies (late FPI) combined with small amounts of hydrogen addition to the exhaust are required
Fabricación y caracterización de composites de ácido poliláctico reforzados con madera de olivo
En esta investigación se ha reforzado el biopolímero ácido poliláctico con madera de olivo obteniéndose un composite que mejora las propiedades y a la vez cumple con los requisitos medioambientales. El proceso ha consistido en un mezclado automático del PLA, fibra de madera y 10% de aditivo, seguido de un proceso de inyección. El porcentaje de fibra de madera de olivo adicionada han sido del 20% y se ha empleado madera sin tratar y tratada con álcali. Se han determinado las propiedades mecánicas y térmicas de los composites y se ha evaluado la influencia de la exposición ultravioleta en el comportamiento mecánico
Detection of a Corrugated Velocity Pattern in the Spiral Galaxy NGC 5427
Here we report the detection, in Halpha emission, of a radial corrugation in
the velocity field of the spiral galaxy NGC 5427. The central velocity of the
Halpha line displays coherent, wavy-like variations in the vicinity of the
spiral arms. The spectra along three different arm segments show that the
maximum amplitude of the sinusoidal line variations are displaced some 500 pc
from the central part of the spiral arms. The peak blueshifted velocities
appear some 500 pc upstream the arm, whereas the peak redshifted velocities are
located some 500 pc downstream the arm. This kinematical behavior is similar to
the one expected in a galactic bore generated by the interaction of a spiral
density wave with a thick gaseous disk, as recently modeled by Martos & Cox
(1998).Comment: Accepted for publication in Ap
The certification of anti-myeloperoxidase immunoglobulin G in human serum ERM® - DA476/IFCC
This report describes the production and certification of ERM-DA476/IFCC, a new serum protein reference material intended for the standardisation of measurements of anti-myeloperoxidase immunoglobulin G (anti-MPO IgG) antibodies. The material was produced according to ISO Guide 34:2009. The raw material used to prepare ERM-DA476/IFCC was a plasmapheresis material containing a high concentration of anti-MPO IgG. After a thorough commutability study lyophilised serum was selected as the format for the candidate reference material. Serum processing was performed based on the procedure used for the reference material ERM-DA470k/IFCC. The plasma was converted into serum which was then delipidated. After the addition of preservatives the processed serum was diluted with plasmapheresis solution containing albumin, prior to the transfer of 1 mL aliquots to glass vials. The serum was then lyophilised and the vials closed with rubber stoppers and screw caps under nitrogen atmosphere prior to storage at -70 °C. The between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The material was characterised by an inter-laboratory comparison exercise performed by laboratories of demonstrated competence and with adherence to ISO/IEC 17025 , using a purified anti-MPO IgG preparation as calibrant. This was achieved using a value transfer protocol previously used in the characterisation of ERM-DA470k/IFCC. Technically invalid results were removed. However no other outliers were eliminated on statistical grounds only. Uncertainties of the certified values were calculated in accordance to the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties relating to possible lack of homogeneity, instability and characterisation. The material is intended for the calibration of methods and quality control. As any reference material, it can also be used for control charts or validation studies. The CRM is available in glass vials containing the lyophilised residue of 1 g serum. The minimum amount of reconstituted sample to be used is 10 μL. The CRM was accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium
Efectos del entrenamiento interválico de alta intensidad durante el periodo transitorio en jugadores de fútbol sub-19
Actualmente existe un creciente interés por la aplicación del entrenamiento interválico de alta intensidad (HIIT) en fútbol (Buchheit et al. 2013). La eficacia mostrada por esta metodología de entrenamiento para mejorar las variables del rendimiento ha provocado una mayor aplicación en deportes colectivos (Iaia et al. 2009). Sin embargo, es escasa la literatura científica acerca de su impacto en fútbol. Por ello, el objetivo del trabajo es comparar los efectos sobre el rendimiento del HIIT versus entrenamiento tradicional durante el periodo transitorio invernal en jugadores de fútbol sub-19
Vertical variation in the amplitude of the seasonal isotopic content of rainfall as a tool to jointly estimate the groundwater recharge zone and transit times in the Ordesa and Monte Perdido National Park aquifer system, north-eastern Spain
The time series of stable water isotope composition relative to meteorological stations and springs located in the high mountainous zone of the Ordesa and Monte Perdido National Park are analyzed in order to study how the seasonal isotopic content of precipitation propagates through the hydrogeological system in terms of the aquifer recharge zone elevation and transit time. The amplitude of the seasonal isotopic composition of precipitation and the mean isotopic content in rainfall vary along a vertical transect, with altitudinal slopes for d18O of 0.9‰/km for seasonal amplitude and - 2.2‰/km for isotopic content. The main recharge zone elevation for the sampled springs is between 1950 and 2600 m·a.s.l. The water transit time for the sampled springs ranges from 1.1 to 4.5 yr, with an average value of 1.85 yr and a standard deviation of 0.8 yr. The hydrological system tends to behave as a mixing reservoir.Peer ReviewedPostprint (author's final draft
Statistical Mechanics of Soft Margin Classifiers
We study the typical learning properties of the recently introduced Soft
Margin Classifiers (SMCs), learning realizable and unrealizable tasks, with the
tools of Statistical Mechanics. We derive analytically the behaviour of the
learning curves in the regime of very large training sets. We obtain
exponential and power laws for the decay of the generalization error towards
the asymptotic value, depending on the task and on general characteristics of
the distribution of stabilities of the patterns to be learned. The optimal
learning curves of the SMCs, which give the minimal generalization error, are
obtained by tuning the coefficient controlling the trade-off between the error
and the regularization terms in the cost function. If the task is realizable by
the SMC, the optimal performance is better than that of a hard margin Support
Vector Machine and is very close to that of a Bayesian classifier.Comment: 26 pages, 12 figures, submitted to Physical Review
A Semantic Portal for the International Affairs Sector
The Royal Institute Elcano(dagger) (Real Instituto Elcano) in Spain is a prestigious independent political institute whose mission is to comment on the political situation in the world focusing on its relation to Spain. As part of its dissemination strategy it operates a public website. The online content can be accessed by navigating through categories or by a keyword-based, full text search engine. The work described in this paper aims at improving access to the content. We describe an approach, tools and techniques that allow building a semantic portal, where access is based on the meaning of concepts and relations of the International Affairs domain. The approach comprises an automatic ontology-based annotator, a semantic search engine with a natural language inter-face, a web publication tool allowing semantic navigation, and a 3D visualization component. The semantic portal is currently being tested by the Institute
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