Numerical investigation into the failure of a micropile retaining wall

The paper presents a numerical investigation on the failure of a micropile wall that collapsed while excavating the adjacent ground. The main objectives are: to estimate the strength parameters of the ground; to perform a sensitivity analysis on the back slope height and to obtain the shape and position of the failure surface. Because of uncertainty of the original strength parameters, a simplified backanalysis using a range of cohesion/friction pairs has been used to estimate the most realistic strength parameters. The analysis shows that failure occurred because overestimation of strength and underestimation of loads.Peer ReviewedPostprint (author's final draft

Pfaffian Systems from Twistor Fibrations

Canonical twistor fibrations lead to Pfaffian systems by means of their superhorizontal distribution. The aim of this note is to identify explicitly the Pfaffian systems of five or less variables that arise in this way in terms of the classification given by A.Awane and M.Goze.Comment: 18 page

Synthesis and cytotoxic activity of geranylmethoxyhydroquinone derivatives

Indexación: Web of Science; ScieloEl geranilo-2 ,4-sintético nuevo methoxyhydroquinone 1 y el conocido geranilo-4 ,5 methoxyhydroquinone- 2 se prepararon por sustitución electrófila aromática (EAS) reacciones entre geraniol y 1,3,5-trimethoxyphenol utilizando BF 3 · Et 2 O como un catalizador. Además, los nuevos derivados geranylmethoxyhydroquinones (3-6) se obtuvieron mediante transformaciones químicas de 1 y 2. Los compuestos se han evaluado por sus actividades citotóxicas contra PC-3 línea celular humana de cáncer de próstata, MCF 7-y humano MDA-MB-231 las células de cáncer de mama líneas y dengue hemorrágico cutánea fibroblastos humanos. IC 50 valores para los compuestos 1 y 5 varió en el nivel mu M 80.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072012000300005&lng=es&nrm=is

Heat transport with advection in fractured rock

In the transport of heat in porous media, diffusion generally dominates over advection due to slow fluid velocities imposed by low permeability. This is the reason why standard Galerkin formulation leading to extra non-symmetric matrix terms may be still used successfully. However, in the presence of fractures the situation may be different. Fractures constitute preferential flow paths where fluid velocities may be significant and advection may become dominant over diffusion (“large advection” with Péclet number >1). This paper focuses on the formulation, numerical implementation and verification of a model to solve the steady-state heat transport problem with large advection along geomechanical discontinuities represented by zero-thickness interface elements. The fluid velocity field is considered as known input data (no hydraulic coupling). The existing SUPG method is modified for its application to zero-thickness interface elements, and the resulting formulation is implemented in an existing FE geomechanical code. An example of application is presented with large advection along a discontinuity crossing a low permeability domain. The results show that the proposed approach leads to stable results, in contrast to standard Galerkin

COMMISSION STAFF WORKING PAPER IMPACT ASSESSMENT Common Agricultural Policy towards 2020 ANNEX 8 {COM(2011) 625 final} {COM(2011) 626 final} {COM(2011) 627 final} {COM(2011) 628 final} {COM(2011) 629 final} {COM(2011) 630 final} {COM(2011) 631 final} {SEC(2011) 1154 final}. SEC (2011) 1153 final, 12.10.2011

En los últimos tempos la educación infantil ha adquirido especial relevancia en el marco de las políticas educacionales de los países latinoamericanos y en especial de Chile (CONTRERAS, HERRERA; LEYTON, 2007; DIEZ, 2011; DUSSAILLANT, 2009; TOKMAN, 2010). La investigación centra su atención en la calidad educativa y, en particular, en los procesos autoevaluativos que demuestran los niños de edades tempranas. Desde una perspectiva paradigmática cuantitativa, apoyada de reportes cualitativos, el estudio presenta la capacidad explicativa de las variables metacognición, autorregulación, autoeficacia, lenguaje y autoconcepto, respecto del desarrollo de la autoevaluación y su vinculación con mejores niveles de logros en párvulos de cinco a seis años. Los hallazgos muestran que la autoevaluación es una dimensión que muestra diversos niveles de expresión en el grupo investigado, fuertemente influenciada por las profesionales del área, tal como se aprecia en los discursos infantiles. Además, las variables analizadas presentan diferentes grados de contribución a la explicación de la autoevaluación en el grupo estudiado

Numerical analysis of desiccation, shrinkage and cracking in low plasticity clayey soils

This paper presents a numerical study of the desiccation processes of low-plasticity clayey soils that usually result in shrinkage and often in cracking. For the theoretical development of the numerical model, concepts of Unsaturated Soils Mechanics and of classical Strength of Materials are used as a framework for formulating phenomena such as water flow in deformable porous media and cracking. The mathematical formulation of the problem and its implementation in a hydro-mechanical coupled model is presented, in order to simulate fluid flow and cracking in soils, for which the FEM and the node release technique is combined. The code developed has been used to perform several numerical analyses on radial sections of cylindrical soil specimens subjected to a drying process for which experimental laboratory data was available. The objective of these simulations is to determine the mechanisms by which the soil shrinks and cracks during desiccation. The results show the capabilities of the approach to reproduce the main features of the problem, with desiccation, shrinkage, and cracking being reproduced consistently during a desiccation cycle. The model also highlights the key role of the displacement and suction boundary conditions in the development of cracks as a consequence of tensile stress fields. Finally, the model has revealed the necessity of further research in the study of the soil-container and soil-atmosphere interaction in order to reproduce with more accuracy the changes in the main variable

Applications of spatial altimetry to studies of ocean dynamics in the Gulf of Cadiz

Sea-level records, and their global and local spatio-temporal variations, are related to many oceanographic and geophysical features. The sea surface can also be visualised as the physical representation of the geoid, averaging the sea-surface records over long periods to eliminate the short periods of dynamic perturbation. Over the last ten years, orbit determination improvements have opened up the possibility of using, for ocean dynamic and sea-level variation studies, several altimetric satellites, accurate to the sub-decimetre level (ERS-1, ERS-2, Topex-Poseidon). Of these satellites, Topex-Poseidon makes it possible to measure the sea-level variation over global or regional zones with an accuracy better than 5 cm. This paper presents the results of the sea-surface height measurements from Topex-Poseidon, corrected for wet and dry troposphere range delays, ionosphere delay, sea-state bias, the inverse barometer, loading effects and the oceanic, solid-earth and pole tides. The authors analyse the spatio-temporal stability of the geoid OSU91-a and the mean sea-surface OSUMSS95, comparing the behaviour of the dynamic signal using the two different surfaces along Topex profile 122, which overflies the Atlantic apertures of the Gulf of Cadiz. Long-term analysis has been done over several points located on the Iberian Atlantic continental margin using Topex Poseidon altimeter data collected from October 1992 (cycle 2) to October 1997 (cycle 186). The main findings of the data analysis present a semi-annual variation with peaks in autumn and winter, separated on the order of 20 cm, which could be explained by the seawater temperature seasonal variation and the doubtful use of the inverse barometer model to correct the response of the ocean to changes in atmospheric pressure. Records also show a secular variation in the regional sea level of roughly 3 mm/year, according to historical tide-gauge trends, which could also probably be explained by polar ice melting and a slight warming tendency of the ocean.Los registros de la variación espaciotemporal del nivel del mar están relacionados con un gran número de procesos oceanográficos y geofísicos que afectan a la superficie del océano y que pueden representar físicamente la figura del geoide, al eliminarse las variaciones dinámicas de corto periodo una vez promediados los registros sobre largos periodos de tiempo. En el último decenio los desarrollos técnicos y las mejoras en los formalismos de corrección y cálculo de las órbitas han permitido misiones altimétricas de precisión subdecimétrica, especialmente diseñadas para el estudio de la variación del nivel del mar y la dinámica oceánica global y regional (ERS-1, ERS-2, Topex-Poseidon). Una vez corregidos los observables del altímetro conforme propone la Agencia AVISO, se han comparado las precisiones del geoide OSU91-a con la superficie media OSUMSS95, analizando los valores obtenidos en la señal dinámica en el perfil del Topex n1 122, al sobrevolar la zona del Atlántico ibérico. Los autores presentan los resultados del estudio que han realizado de los datos obtenidos por el satélite Topex-Poseidon entre los ciclos 2 y 186 de sus órbitas (octubre de 1992 y octubre de 1997) en varios puntos del margen continental ibérico. Los principales resultados presentan una variación, del orden de 20 cm, en el nivel del mar en los bajos de Gorringe de tipo semianual, justificable con la variación de la temperatura de las masas de agua superficiales entre otoño e invierno y un comportamiento inadecuado del modelo de barímetro invertido en las zonas de estudio. Una variación del mismo orden se detecta en el golfo de Cádiz, igualmente justificable por la variación estacional de la temperatura del océano en su superficie. Además de la variación semianual se detecta una variación secular del orden de 2 a 3 mm/año, probablemente de naturaleza global, compatible con los resultados obtenidos con mareógrafos clásicos, justificable por la fusión de hielos en los casquetes polares y un ligero aumento secular de la temperatura de las masas de agua del océano en la zona del margen continental ibérico.Instituto Español de Oceanografí

Mapping the secondary star in QQ Vulpeculae

We present high- and medium-resolution phase-resolved far-red spectra of the magnetic cataclysmic variable QQ Vul. The spectra show the Na i doublet absorption features near λ 8190 Å from the cool secondary star, and the lines of He ii, O i, Mg ii, C i, N i, Ca ii and Paschen in emission. Using a Doppler imaging technique, we find that the H i, He ii, C i and O i lines have a narrow component originating near the L1 point and a strong component from the stream, while the Mg ii and Ca ii emission arises solely from the illuminated hemisphere of the red dwarf. We carry out an exhaustive analysis of the emission- and absorption-line velocities and fluxes seen in the QQ Vul spectrum. By simultaneously fitting the radial velocity and flux information we are able to produce surface maps of each line on the secondary star using a technique analogous to the one employed by Davey. The Na i and Mg ii maps show an asymmetric distribution akin to that seen in AM Her. Although the observed velocity semi-amplitudes (K2) of the lines can potentially be corrected for the effects of irradiation, we find that time-dependent changes in the degree of heating on the secondary can lead to large discrepancies in the results, significant enough to give inconsistent values from data taken at different epochs. We discuss the limitations of the surface mapping method as a means of correcting the observed K2. Our results also suggest that the emission features from the red dwarf are likely to be formed at quite high levels of the stellar chromosphere, in some cases probably even beyond the L1 point and inside the Roche lobe of the white dwarf, with the different lines possibly forming at different depths. Using the Na i absorption doublet, we find a velocity semi-amplitude for the secondary star of K2=219±6 km s−1 and a projected rotational velocity of vrot sin i=110±15 km s−1. Thus we estimate the mass ratio to be q=0.54±0.14. Based on the results of the best-fitting surface maps on all the lines, and the nature of the phase-dependent variations of the continuum and lines, we infer a binary inclination of i=65°±7°, and obtain a complete set of binary parameters for QQ Vul. We classify the secondary star as M4V from the TiO band ratios

La creación de la ventaja comparativa en la industria automovilística española, 1898-1996

A finales del siglo XX, la fabricación de automóviles en España alcanzaba el billón de pesetas de supéravit comercial (cuatro veces más que el calzado o la cerimica, las siguientes industrias más exitosas en el exterior). Este trabajo analiza las causas teóricas y las evidencias empíricas que explican la formación de la actual ventaja comparativa en la automoción. Parte del estudio de los procesos de relocalización internacional de la industria del motor e inscribe el caso espa- Bol en las grandes etapas de desarrollo de dicha actividad