Depositional style and tectonostratigraphic evolution of the El Bierzo Tertiary Subbasin (Pyrenean orogen, NW Spain)

El Bierzo Tertiary sub-basin (Oligocene–Miocene, NW Spain) is a small remnant of the western Duero Basin, a nonmarine broken foreland basin developed in front of the Cantabrian Mountains (Pyrenean orogen). The alluvial infill of El Bierzo Tertiary sub-basin consists of a coarsening-upward succession from fluvial (Toral Formation) to alluvial-fan deposits (Las Médulas Formation) and reflects the uplift of the Cantabrian Mountains, in the north, and then of the related Galaico-Leoneses Mountains, in the south. These alluvial deposits show signs of having been laid down mainly by catastrophic flows (flood-dominated systems) and consist of three main depositional elements, namely, flood-plain fines, and lobe and channel conglomerates and sandstones. The vertical stacking patterns of these deposits and their relationships to the Alpine structures permit to unravel the tectonosedimentary evolution of the basin. The alluvial-plain element is the main constituent of a wide unconfined alluvial plain (Toral Formation) during the early stages of basin evolution, whereas the channel and lobe elements form a set of relatively small, laterally confined alluvial fans (Las Médulas Formation) fed first from the north and then from the south. Las Médulas deposits form two superposed units, the lower unit, cut by the Alpine thrusts, shows a progradational character, and the upper unit, which postdates most of the thrusts but not the youngest ones, displays a composite retrogradational trend. This organisation reflects the interplay between thrust emplacement and alluvial-fan sedimentation and suggests that maximum progradation took place during the climax of Alpine deformation

The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization

The characterization of building materials is a key tool to assess deterioration processes and improve potential restoration works of archaeological sites. The aim of this paper is to identify and characterize the most important building stones used in the construction of the Roman city of Lixus (Larache, Morocco) by means of petrographic and petrophysical techniques. Based on the visual analysis of the monuments, three major building stones (i.e. lithotypes) have been identified: i) Oligocene sandstones, ii) Quaternary sandstones and iii) Quaternary conglomerates. Based on the analysis of the regional geology and exploitation marks, these three lithotypes have been recognised to crop out in the surroundings of Lixus and the quarries, presumably Roman in origin, recognized. The Oligocene sandstone is the primary building stone in Lixus as it forms and crops out extensively in the Tchemmis hill, at the top of which the city is settled. The Quaternary sandstones and conglomerates, which represent nearshore deposits and eolianites, crop out along the Atlantic coast where they form part of the cliffs next to Larache. Petrographic results indicate that lithotypes differ notably in grain size, ratio of detrital to allochemical components, and the configuration of their porous system. Mechanical analysis shows that the Oligocene sandstones are more resistant to compression than the Quaternary sandstones and conglomerates, the latter exhibiting relatively low compressive strength. The Oligocene sandstones, which display scarce porosity and permeability, show a hydric behaviour characterized by a very low degree of absorption and desorption water, likely resulting from a poor connectivity of the pore network. Contrary to the latter lithotype, the Quaternary sandstones, which exhibit very high porosity and permeability, display a hydric behaviour characterized by high degree of both absorption and desorption of water. This is attributed to the low degree of cementation compared to porosity of this lithotype and the excellent connectivity of the porous network. Finally, Oligocene and Quaternary sandstones do not show a significant weight loss after the accelerated artificial aging test, indicating that both are slightly affected by salt crystallization and presumably ice formation. Results indicate that the relatively fine state of conservation of the building rocks of Lixus is linked to intrinsic factors such as mineralogy and petrophysical characteristics together with the favourable effect of the climatic condition of the study area

Development of a Variable Valve Actuation Control to Improve Diesel Oxidation Catalyst Efficiency and Emissions in a Light Duty Diesel Engine

[EN] Growing interest has arisen to adopt Variable Valve Timing (VVT) technology for automotive engines due to the need to fulfill the pollutant emission regulations. Several VVT strategies, such as the exhaust re-opening and the late exhaust closing, can be used to achieve an increment in the after-treatment upstream temperature by increasing the residual gas amount. In this study, a one-dimensional gas dynamics engine model has been used to simulate several VVT strategies and develop a control system to actuate over the valves timing in order to increase diesel oxidation catalyst efficiency and reduce the exhaust pollutant emissions. A transient operating conditions comparison, taking the Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC) as a reference, has been done by analyzing fuel economy, HC and CO pollutant emissions levels. The results conclude that the combination of an early exhaust and a late intake valve events leads to a 20% reduction in CO emissions with a fuel penalty of 6% over the low speed stage of the WLTC, during the warm-up of the oxidation catalyst. The same set-up is able to reduce HC emissions down to 16% and NO(x)emission by 13%.This research has been partially funded by the Spanish government under the grant agreement TRA2017-89894-R ("Mecoem"). Angel Aunon was supported through the "Apoyo para la investigacion y Desarrollo (PAID)" grant for doctoral studies (FPI S2 2018 1048) by Universitat Politecnica de Valencia.Serrano, J.; Arnau Martínez, FJ.; Martín, J.; Auñón-García, Á. (2020). Development of a Variable Valve Actuation Control to Improve Diesel Oxidation Catalyst Efficiency and Emissions in a Light Duty Diesel Engine. Energies. 13(17):1-26. https://doi.org/10.3390/en13174561S1261317Arnau, F. J., Martín, J., Pla, B., & Auñón, Á. (2020). Diesel engine optimization and exhaust thermal management by means of variable valve train strategies. International Journal of Engine Research, 22(4), 1196-1213. doi:10.1177/1468087419894804Luján, J. M., Serrano, J. R., Piqueras, P., & García-Afonso, Ó. (2015). Experimental assessment of a pre-turbo aftertreatment configuration in a single stage turbocharged diesel engine. Part 2: Transient operation. Energy, 80, 614-627. doi:10.1016/j.energy.2014.12.017Lancefield, T., Methley, I., Räse, U., & Kuhn, T. (2000). The Application of Variable Event Valve Timing to a Modern Diesel Engine. SAE Technical Paper Series. doi:10.4271/2000-01-1229Gonzalez D, M. A., & Di Nunno, D. (2016). Internal Exhaust Gas Recirculation for Efficiency and Emissions in a 4-Cylinder Diesel Engine. SAE Technical Paper Series. doi:10.4271/2016-01-2184Serrano, J. R., Piqueras, P., Navarro, R., Gómez, J., Michel, M., & Thomas, B. (2016). Modelling Analysis of Aftertreatment Inlet Temperature Dependence on Exhaust Valve and Ports Design Parameters. SAE Technical Paper Series. doi:10.4271/2016-01-0670Siewert, R. M. (1971). How Individual Valve Timing Events Affect Exhaust Emissions. SAE Technical Paper Series. doi:10.4271/710609Tomoda, T., Ogawa, T., Ohki, H., Kogo, T., Nakatani, K., & Hashimoto, E. (2010). Improvement of Diesel Engine Performance by Variable Valve Train System. International Journal of Engine Research, 11(5), 331-344. doi:10.1243/14680874jer586Benajes, J., Reyes, E., & Luján, J. M. (1996). Modelling Study of the Scavenging Process in a Turbocharged Diesel Engine with Modified Valve Operation. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 210(4), 383-393. doi:10.1243/pime_proc_1996_210_210_02Deppenkemper, K., Özyalcin, C., Ehrly, M., Schoenen, M., Bergmann, D., & Pischinger, S. (2018). 1D Engine Simulation Approach for Optimizing Engine and Exhaust Aftertreatment Thermal Management for Passenger Car Diesel Engines by Means of Variable Valve Train (VVT) Applications. SAE Technical Paper Series. doi:10.4271/2018-01-0163Zammit, J. P., McGhee, M. J., Shayler, P. J., Law, T., & Pegg, I. (2015). The effects of early inlet valve closing and cylinder disablement on fuel economy and emissions of a direct injection diesel engine. Energy, 79, 100-110. doi:10.1016/j.energy.2014.10.065Pan, X., Zhao, Y., Lou, D., & Fang, L. (2020). Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load. Energies, 13(6), 1500. doi:10.3390/en13061500Guan, W., Pedrozo, V. B., Zhao, H., Ban, Z., & Lin, T. (2019). Variable valve actuation–based combustion control strategies for efficiency improvement and emissions control in a heavy-duty diesel engine. International Journal of Engine Research, 21(4), 578-591. doi:10.1177/1468087419846031Guan, W., Zhao, H., Ban, Z., & Lin, T. (2018). Exploring alternative combustion control strategies for low-load exhaust gas temperature management of a heavy-duty diesel engine. International Journal of Engine Research, 20(4), 381-392. doi:10.1177/1468087418755586Maniatis, P., Wagner, U., & Koch, T. (2018). A model-based and experimental approach for the determination of suitable variable valve timings for cold start in partial load operation of a passenger car single-cylinder diesel engine. International Journal of Engine Research, 20(1), 141-154. doi:10.1177/1468087418817119Kim, J., & Bae, C. (2015). An investigation on the effects of late intake valve closing and exhaust gas recirculation in a single-cylinder research diesel engine in the low-load condition. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 230(6), 771-787. doi:10.1177/0954407015595149Zhou, X., Liu, E., Sun, D., & Su, W. (2018). Study on transient emission spikes reduction of a heavy-duty diesel engine equipped with a variable intake valve closing timing mechanism and a two-stage turbocharger. International Journal of Engine Research, 20(3), 277-291. doi:10.1177/1468087417748837Gosala, D. B., Ramesh, A. K., Allen, C. M., Joshi, M. C., Taylor, A. H., Van Voorhis, M., … Stretch, D. (2017). Diesel engine aftertreatment warm-up through early exhaust valve opening and internal exhaust gas recirculation during idle operation. International Journal of Engine Research, 19(7), 758-773. doi:10.1177/1468087417730240Parvate-Patil, G. B., Hong, H., & Gordon, B. (2004). Analysis of Variable Valve Timing Events and Their Effects on Single Cylinder Diesel Engine. SAE Technical Paper Series. doi:10.4271/2004-01-2965Piano, A., Millo, F., Di Nunno, D., & Gallone, A. (2017). Numerical Analysis on the Potential of Different Variable Valve Actuation Strategies on a Light Duty Diesel Engine for Improving Exhaust System Warm Up. SAE Technical Paper Series. doi:10.4271/2017-24-0024Payri, F., Arnau, F. J., Piqueras, P., & Ruiz, M. J. (2018). Lumped Approach for Flow-Through and Wall-Flow Monolithic Reactors Modelling for Real-Time Automotive Applications. SAE Technical Paper Series. doi:10.4271/2018-01-0954Martin, J., Arnau, F., Piqueras, P., & Auñon, A. (2018). Development of an Integrated Virtual Engine Model to Simulate New Standard Testing Cycles. SAE Technical Paper Series. doi:10.4271/2018-01-1413Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., Dombrovsky, A., & Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management, 128, 281-293. doi:10.1016/j.enconman.2016.09.032Galindo, J., Tiseira, A., Navarro, R., Tarí, D., Tartoussi, H., & Guilain, S. (2016). Compressor Efficiency Extrapolation for 0D-1D Engine Simulations. SAE Technical Paper Series. doi:10.4271/2016-01-0554Serrano, J. R., Olmeda, P., Arnau, F. J., & Samala, V. (2019). A holistic methodology to correct heat transfer and bearing friction losses from hot turbocharger maps in order to obtain adiabatic efficiency of the turbomachinery. International Journal of Engine Research, 21(8), 1314-1335. doi:10.1177/1468087419834194Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). Analysis and Methodology to Characterize Heat Transfer Phenomena in Automotive Turbochargers. Journal of Engineering for Gas Turbines and Power, 137(2). doi:10.1115/1.4028261Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2015). Turbocharger heat transfer and mechanical losses influence in predicting engines performance by using one-dimensional simulation codes. Energy, 86, 204-218. doi:10.1016/j.energy.2015.03.130Arrègle, J., López, J. J., Martín, J., & Mocholí, E. M. (2006). Development of a Mixing and Combustion Zero-Dimensional Model for Diesel Engines. SAE Technical Paper Series. doi:10.4271/2006-01-1382Payri, F., Arrègle, J., López, J. J., & Mocholí, E. (2008). Diesel NOx Modeling with a Reduction Mechanism for the Initial NOx Coming from EGR or Re-entrained Burned Gases. SAE Technical Paper Series. doi:10.4271/2008-01-1188Broatch, A., Olmeda, P., Martin, J., & Salvador-Iborra, J. (2018). Development and Validation of a Submodel for Thermal Exchanges in the Hydraulic Circuits of a Global Engine Model. SAE Technical Paper Series. doi:10.4271/2018-01-0160Guardiola, C., Pla, B., Bares, P., & Mora, J. (2018). An on-board method to estimate the light-off temperature of diesel oxidation catalysts. International Journal of Engine Research, 21(8), 1480-1492. doi:10.1177/1468087418817965Russell, A., & Epling, W. S. (2011). Diesel Oxidation Catalysts. Catalysis Reviews, 53(4), 337-423. doi:10.1080/01614940.2011.596429Guardiola, C., Pla, B., Piqueras, P., Mora, J., & Lefebvre, D. (2017). Model-based passive and active diagnostics strategies for diesel oxidation catalysts. Applied Thermal Engineering, 110, 962-971. doi:10.1016/j.applthermaleng.2016.08.207Abdelghaffar, W. A., Osman, M. M., Saeed, M. N., & Abdelfatteh, A. I. (2002). Effects of Coolant Temperature on the Performance and Emissions of a Diesel Engine. Design, Operation, and Application of Modern Internal Combustion Engines and Associated Systems. doi:10.1115/ices2002-464Torregrosa, A. J., Olmeda, P., Martín, J., & Degraeuwe, B. (2006). Experiments on the influence of inlet charge and coolant temperature on performance and emissions of a DI Diesel engine. Experimental Thermal and Fluid Science, 30(7), 633-641. doi:10.1016/j.expthermflusci.2006.01.00

Anàlisi espacio-temporal de la línia de costa i del foredune del sistema dunar de Sa Canova d’Artà (Mallorca)

[cat] Els sistemes platja-duna, són una de les morfologies sedimentàries més abundants a les Illes Balears. Aquests es troben composats per diferents subsistemes, els quals presenten diferents nivells de dinamisme. Des d’aquest punt de vista, la foredune és el sector més dinàmic de la part emergida del sistema i en la qual la vegetació té un paper clau per al desenvolupament de la resta del sistema. Tots i cada un dels sistemes existents a la comunitat autònoma i a la resta del món disposa d’una condicions/característiques que el fan peculiar i diferent a la resta; a part de les pròpies condicions físiques intrínseques al propi medi, a dia d’avui els sistemes han de fer front a tota una sèrie de pressions d’origen antròpic, destacant especialment l’activitat turística en el cas Balear. El cas d’estudi, és Sa Canova, situada al terme municipal d’Artà (NE de l’illa de Mallorca); aquest sistema tampoc n’és una excepció, al llarg del període d’estudi (1956-2012), ha sofert variacions, tant d’origen natural, com antròpic, les quals han tingut com a conseqüència el sistema dunar actualment existent.[eng] The beach-dune systems, are one of the most abundant sedimentary morphologies in the Balearic Islands. These are composed of different subsystems, which present different levels of dynamism. From this point of view, Foredune is the most dynamic sector of the emerging part of the system and in which vegetation plays a key role for the development of the rest of the system. Each and every one of the existing systems in the autonomous community and the rest of the world has conditions / characteristics that make it peculiar and different from the rest; Apart from the intrinsic physical conditions inherent in their own environment, today, systems have to deal with a whole series of pressures of anthropogenic origin, with special emphasis on tourism in the Balearic Islands. The case study is Sa Canova, located in the municipality of Artà (NE of the island of Mallorca); This system is not an exception either, during the period of study (1956-2012), it has undergone variations, both of natural origin and anthropic, which have resulted in the current dune system

The building stone of the Roman city of Lixus (NW Morocco) : provenance, petrography and petrophysical characterization

Characterization of building material is a key tool to assess deterioration processes and improve potential restoration works of archaeological sites. The aim of this paper is to identify and characterize the building stone used in the construction of the Phoenician-Roman city of Lixus (Larache, Morocco) by means of petrographic and petrophysical technics. Based on the visual analysis of the monuments, three major building stones (i.e., lithotypes) have been identified: (1) Oligocene sandstones, (2) Quaternary sandstones, and (3) Quaternary conglomerates. Based on the analysis of the regional geology and exploitation marks, these three lithotypes have been identified to crop out in the surroundings of Lixus and the quarries, presumably Roman in origin, recognized. The Oligocene sandstone is the primary building stone in Lixus as form and crop out extensively in the Tchemmis hill, at top of which the city is settled. The Quaternary sandstones and conglomerates, which represent nearshore deposits and eolianites, are less abundant as building rocks in Lixus and crop out along the Atlantic coast where form part pf the cliffs close to Larache. Petrographic results indicate that lithotypes differ notably in grain size, ratio of detrital to allochemical components, and the configuration of their porous system. Mechanical analysis show that the Oligocene sandstones are more resistant to compression than the Quaternary sandstones and conglomerates, the latter exhibiting low compressive strength. The Oligocene sandstones, which display scarce porosity and permeability, show a hydric behaviour characterized by a very low degree of absorbing and desorbing water, likely resulting from a poor connectivity of the pore network. Contrary to later lithotype, the Quaternary sandstones and conglomerates, which exhibit very high porosity and permeability, display a hydric behaviour characterized by high degree of both absorbing and desorbing water. This behaviour is attributed to both the low degree of cementation and excellent connectivity of the porous network of the lithotype typical of coastal deposists. Finally, the accelerated artificial aging test they do not show a significant weight loss after twelve cycles of salt crystallization, indicating that the three lithotypes are not vulnerable to sodium sulphate attacks. Results of this study indicate that the good state of conservation of the building rocks of Lixus is linked to intrinsic factors as mineralogy and petrophysical characteristics together with the favourable effect of the climatic condition of the study area

Effect of natural and forced charge air humidity on the performance and emissions of a compression-ignition engine operating at high warm altitude

[EN] The effect of ambient humidity on the performance and pollutant emissions of internal combustion engines is not considered in the literature despite type-approval criteria are moving closer to real driving conditions. This work analyses experimentally the effects of charge air humidity at high warm altitudes, where the use of exhaust gas recirculation (EGR) is typically lowered and even avoided to recover engine performance at the expense of NOx emissions increase, on the response of a compression-ignition engine under a wide range of steady-state con-ditions in terms of engine-out emissions and specific fuel consumption. The impact of specific humidity varia-tions within the atmospheric range was analysed by coupling the engine to an altitude simulator with pressure, temperature, and humidity control capabilities. High altitudes and warm & high ambient temperatures were explored (2000 m at 30 degrees C and 2500 m at 45 degrees C) to cover ambient specific humidity up to 30 gwater/kgdry_air. In addition, the effects of increasing the specific humidity above the atmospheric levels were considered at 2500 m and 45 degrees C to emulate forced injection of water in the engine intake line corresponding to 60 gwater/kgdry_air. With this approach, understanding of the role of humidity is provided to highlight its importance as additional ambient property in emission control. In parallel, the assessment of the forced water content increase to control NOx emissions when EGR must be lowered was performed due to the altitude impact on the engine performance and turbocharger limits. The results showed a consistent and significant reduction in engine-out NOx emissions as the ambient humidity increased, reaching up to 300% with respect to the dry case, caused by the decrease in O2 availability due to the water content increase. The benefits of high humidity in NOx emission control at high altitudes when EGR is not feasible were complemented by an improved trade-off with particulate matter emission compared to the standard from EGR use. The results evidenced a reduction in opacity close to 250% for a given engine-out NOx emission when EGR was replaced by water content. By contrast, the slowdown of the combustion process as the fresh air humidity increased deteriorated the specific fuel consumption significantly as the engine load and speed increased. Nevertheless, these penalties ranged from 2 to 2.7% in the worst conditions and showed the same sensitivity for EGR and humidity increases.This research has been supported by Grant PID2020-114289RB-I00 funded by the Spanish Ministerio de Ciencia e Innovacion - Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033). The PhD candidate Roberto Tabet has been funded by Universitat Politecnica de Valencia through grant PAID -01-18.Serrano, J.; Martín, J.; Piqueras, P.; Tabet-Aleixandre, R.; Gómez-Gil, J. (2023). Effect of natural and forced charge air humidity on the performance and emissions of a compression-ignition engine operating at high warm altitude. Energy. 266:1-11. https://doi.org/10.1016/j.energy.2022.12640911126

Pre-main-sequence Lithium Depletion

In this review I briefly discuss the theory of pre-main-sequence (PMS) Li depletion in low-mass (0.075<M<1.2 Msun) stars and highlight those uncertain parameters which lead to substantial differences in model predictions. I then summarise observations of PMS stars in very young open clusters, clusters that have just reached the ZAMS and briefly highlight recent developments in the observation of Li in very low-mass PMS stars.Comment: 8 pages, invited review at "Chemical abundances and mixing in stars in the Milky Way and its satellites", eds. L. Pasquini, S. Randich. ESO Astrophysics Symposium (Springer-Verlag

Bases fisiopatológicas del tratamiento de la enfermedad de Scheüermann

Los estudios realizados sobre la etiopatogenia de la enfermedad de Scheüermann, no han mostrado hasta el momento suficientes datos para determinar con exactitud cual es la verdadera causa del acuñamiento vertebral, pero es evidente que la deformidad vertebral es consecuencia de una debilidad osteocondral en una etapa de crecimiento sobre la que actúan factores mecánicos. Sobre esta base se plantean los fundamentos del tratamiento conservador analizando los resultados obtenidos con el corsé de Milwaukee y con el corsé de New York de bajo perfil. Los resultados demuestran una clara ventaja del corsé de Milwaukee para las curvas altas, mientras que las curvas con ápex por debajo de T7 se corrigen bien en su valor angular con el corsé de bajo perfil, pero con menor corrección del ángulo de acuñamiento.As to the ethiopathogeny of Scheüermann's disease there is no consensus about the true cause of vertebral body wedging. It seems clear that the deformity of vertebral bodies is a consecuence of osteochondral weakness in a growth period in which mechanic factors are involved. This provides fundamentals of conservative treatment analvzing the results obtained with the Milwaukee and New York braces. The results demostrate a clear adventage of Milwaukee brace for upper kiphosis. On the other hand, low profile braces work well on curves with apex below T7, although less wedge angle correction is obtained

Temperature dependence and mechanisms for vortex pinning by periodic arrays of Ni dots in Nb films

Pinning interactions between superconducting vortices in Nb and magnetic Ni dots were studied as a function of current and temperature to clarify the nature of pinning mechanisms. A strong current dependence is found for a square array of dots, with a temperature dependent optimum current for the observation of periodic pinning, that decreases with temperature as (1-T/Tc)3/2. This same temperature dependence is found for the critical current at the first matching field with a rectangular array of dots. The analysis of these results allows to narrow the possible pinning mechanisms to a combination of two: the interaction between the vortex and the magnetic moment of the dot and the proximity effect. Moreover, for the rectangular dot array, the temperature dependence of the crossover between the low field regime with a rectangular vortex lattice to the high field regime with a square configuration has been studied. It is found that the crossover field increases with decreasing temperature. This dependence indicates a change in the balance between elastic and pinning energies, associated with dynamical effects of the vortex lattice in the high field range.Comment: 12 text pages (revtex), 6 figures (1st jpeg, 2nd-6th postscript) accepted in Physical Review