5,427 research outputs found
Demand Shocks and Trade Balance Dynamics
This paper studies the current account dynamics in the G-7 countries plus Spain. We estimate a SVAR model which allows us to identify three different shocks: supply shocks, real demand shocks and nominal shocks. We use a different identification procedure from previous work based on a microfounded stochastic open-economy model in which the real exchange rate is a determinant of the Phillips curve. Estimates from a structural VAR show that real demand shocks explain most of the variability of current account imbalances, whereas, contrary to previous findings, nominal shocks play no role. The results we obtain are consistent with the predictions of a widely set of open-economy models and illustrate that demand policies are the main responsible of trade imbalances.Current account, SVAR.
Economy and Environmental Problems in the Mexican Coastal States
A canonical correspondence analysis (CCA) for environmental and economic variables was performed for 17 Mexican coastal states. The ordination method allowed us to identify three groups, namely hydroelectric energy generation (I), pollution (II) and harbours (III), which were associated to different human activities. Furthermore, CCA is efficient to help us generate hypotheses for future research. It is therefore advised that CCA should be used for routine analyses into economics.Coastal States of Mexico, Canonical Correspondence Analysis, Diversity Index, Economic Development, Environmental Variables.
A novel particle tracking and break-up detection algorithm: application to the turbulent break-up of bubbles
A new method has been developed to measure experimentally the break-up properties of bubbles. The technique is based on the application of a particle tracking velocimetry algorithm to high-speed video images not only to measure the velocity of the bubbles, but also to detect the break-up events. Thus the algorithm is able to associate every broken bubble with the daughter bubbles formed upon their corresponding break-up. Moreover, the lifetime, as well as the number and size of fragments resulting from the break-up process, can be measured for a large number of bubbles. Statistical processing of the information collected allows us to compute the break-up frequency and daughter size distribution of the bubbles as a function of the bubble size and the mean properties of the base flow. The method has been employed to study the break-up of a cloud of bubbles injected at the central axis of a turbulent water jet. Experimental results for the break-up frequency and daughter bubble size distribution are also presented to illustrate the performance of the technique
On the optimaL response of q-vortex
Wingtip vortices represent a hazard for the stability of the following airplane in airport highways. These flows have been usually modeled as swirling jets/wakes, which are known to be highly unstable and susceptible to breakdown at high Reynolds numbers for certain flow conditions, but different to the ones present in real flying airplanes. A very recent study based on Direct Numerical Simulations (DNS) shows that a large variety of helical responses can be excited and amplified when a harmonic inlet forcing is imposed.
In this work, the optimal response of q-vortex (both axial vorticity and axial velocity can be modeled by a Gaussian profile) is studied by considering the time-harmonically forced problem with a certain frequency ω. We first reproduce Guo and Sun’s results for the Lamb-Oseen vortex (no axial flow) to validate our numerical code. In the axisymmetric case m = 0, the system response is the largest when the input frequency is null. The axial flow has a weak influence in the response for any axial velocity intensity. We also consider helical perturbations |m| = 1. These perturbations are excited through a resonance mechanism at moderate and large wavelengths as it is shown in Figure 1. In addition, Figure 2 shows that the frequency at which the optimal gain is obtained is not a continuous function of the axial wavenumber k. At smaller wavelengths, large response is excited by steady forcing. Regarding the axial flow, the unstable response is the largest when the axial velocity intensity, 1/q, is near to zero. For
perturbations with higher azimuthal wavenumbers |m| > 1, the magnitudes of the response are smaller than those for helical modes. In order to establish an alternative validation, DNS has been carried out by using a pseudospectral Fourier formulation finding a very good agreement.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
On the effect of low blowing ratio continuous jets on wingtip vortex characteristics
Vortices are an unavoidable effect of flight, which appear behind the wing with a bounded length. The strength of these vortices, which are extremely stable, is due to the lift force [1]. That is the reason why this phenomenon is especially relevant during take-off and landing operations. In these situations, when aircraft are departing from or arriving to the airport runways, the following aircraft might feel two counter-rotating vortices which remain long time under normal environmental conditions. Unfortunately, this huge rotation of airflow patterns always destabilizes the following aircraft. Consequently, trailing vortices have a mighty influence on the air traffic control of airport runways, and they have justified the research interest in this topic since the 1960's [2]. However, aeronautical engineers are still searching for different technological strategies to breakdown these wingtip vortices.Short-Term Postdoctoral Stay of Talent Attraction Plan of AndalucĂa TECH ICE. Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tec
Arcillas cerámicas de AndalucĂa. VI. Yacimientos terciarios y cuaternarios de la provincia de Huelva. comarcas de Huelva y El Condado
Se estudian veintisĂ©is muestras de arcilla de interĂ©s cerámico, procedentes de diversos yacimientos en explotaciĂłn situados en el Sur de la provincia de Huelva, en las comarcas de El Condado y zona costera. Los materiales proceden de sedimentos terciarios (la mayor parte) y cuaternarios, constituidos por margas de textura arcillo-arenosa o arcillo-limosa y se emplean en la fabricaciĂłn de ladrillos y tejas en fábricas modernas de gran producciĂłn. Los materiales más plásticos se utilizan en alfarerĂa y talleres de cerámica artĂstica en Huelva y Trigueros. Las tĂ©cnicas empleadas han sido las Siguientes: Análisis quĂmico, capacidad de cambio, análisis tĂ©rmico ponderal y diferencial, diagramas de difracciĂłn de rayos X, examen al microscopio electrĂłnico, análisis mecánico, agua de moldeo, plasticidad (Riecke) , poroSidad, secado a 50ÂşC. (Diagramas de Bourry) , contracciĂłn por calcinaciĂłn, peso especĂfico y resistencia a la compresiĂłn en probetas calcinadas. Se desprende que estas arcillas son de naturaleza fundamentalmente montmorillonĂtica, con una elevada participaciĂłn de minerales caolinĂticos y micáceos (ilita y micas potásicas). Como minerales secundarios y accesorios contienen cuarzo, geles y feldespatos. Todas las muestras contienen cantidades medias hasta altas de calcita en grano fino, que en ciertos casos es de mayor tamaño y puede llegar a ser perjudicial sin un tratamiento conveniente. Las pruebas tecnolĂłgicas indican que se trata de materiales naturales de buenas propiedades cerámicas, de utilidad para la industria de materiales de construcciĂłn, y en otros casos para alfarerĂa y cerámica artĂstica. La gran potencia de los yacimientos, su fácil explotaciĂłn y laboreo, su situaciĂłn en terreno llano y de buenas comunicaciones y la constancia en la composiciĂłn quĂmica y textura de la materia bruta, hace que los consideremos de interĂ©s industrial.Twenty Six samples of clay, interesting from the ceramic viewpoint, from several beds located in the South of the province of Huelva, in the country of El Condado and the coast have been studied. The great majority of materials belong to the Tertiary and Quaternary sediments and are formed by marls of sandy or silty clayed texture. They are used by large modern factories producing bricks and tiles. The more plastic materials are used by pottery and artistic ceramic industries in Huelva and Trigueros. The following techniques have been used: Chemical analysis, base exchange capacity, ponderal thermal analysis, D. T. A., X-ray difraction, electronic microscope, mechanical analysis, moulding water, plasticity (Riecke), porosity, drying shrinkage at 50°C. (Bourry's diagrams) firing shrinkage, specific gravity and crushing strength of fired bodies. It is concluded that these clays are fundamentally of montmorillonitic nature, with, a high proportion of kaolinitic and micaceous minerals (illite and potasic micas). They contain as secondary minerals, quartz gels and feldspars. All the samples contain medium to high quantities of fine grain ed calcite, which, in some casos, may be of larger size, being pernicious without previous treatment. The technological tests suggest that these materials are of good ceramic properties, useful in the building industry and in other cases, for pottery and artistic ceramics. The great depth of these beds, their easy explotation and working, their situation on flat and well communicated land and the constancy of chemical and textural composition of the raw materials make them of industrial interest
Arcillas cerámicas de AndalucĂa V. Yacimientos de terrenos Ăgneos y sedimentos primarios de la provincia de Huelva. Comarcas de Sierra Morena y AndĂ©valo
Twenty two samples of clays, interesting from the ceramic viewpoint, from several beds located on the northern and central regions of the province of Huelva, in the country of Sierra Morena and El AndĂ©valo, respectively, have he en studied. The materials belong to outcrops of igneous nature and slate sediments from the Silurian and Carboniferous, and are of highly sandy texture in general. They are used to make bricks and tiles. The materials of higher clay content are used in pottery and artistic ceramic industries, specially those from Aracena and Cortegana. The following techniques have been used: chemical arialysis, base exchange capacity, ponderal thermal analysis D.T.A., X-ray diffraction, electron microscopy, mechanical analysis, moulding water, plasticity (Riecke), porosity, drying shrinkage at 50ÂşC. (Bourry's diagrams), firing shrinkage, specific gravity and crushing strength in fired bodies. It is concluded that the main components of the materials belonging to the igneous outcrops (granites, porphides, etc.), are fundamentally of kaolinitic nature, with a high proportion of micaceous minerals, free quartz as an accesory mineral and a variable amount of hydrated iron and aluminum oxides. Minerals of 14 A spacings are scarce. Samples from altered slate of AndĂ©valo show distinctly a higher illite content followed by kaolinite and iron and aluminum gels. The presence of montmorillonitic minerals is more obvious. The technological tests suggest) that these raw materials have good ceramic properties, with a high iron content, appropriate for the uses mentioned above. The small extension of these beds prevent the use of these materials by the large ceramic industries.Se estudian veintidĂłs muestras de arcilla de interĂ©s cerámico procedentes de diversos yacimientos situados en las regiones norte y centro de la provincia de Huelva, en las comarcas de Sierra Morena y El AndĂ©valo, respectivamente. Los materiales proceden de afloramientos de naturaleza Ăgnea y sedimentos de pizarras del SilĂşrico y CarbonĂfero, de textura fuertemente arenosa en general, y se emplean en la fabricaciĂłn de ladrillos y tejas. Los materiales más arcillosos se utilizan en alfarerĂas y talleres de cerámica artĂstica, destacando los de Aracena y Cortegana. Las tĂ©cnicas empleadas han sido las siguientes: Análisis quĂmico, capacidad de cambio, análisis tĂ©rmico ponderal y diferencial, diagramas de difracciĂłn de rayos X, examen al microscopio electrĂłnico, análisis mecánico, agua de moldeo, plasticidad (Riecke), porosidad, secado a 50ÂşC (diagramas de Bourry), contracciĂłn por calcinaciĂłn, peso especĂfico y resistencia a la compresiĂłn en probetas calcinadas. Se deduce que los materiales procedentes de yacimientos sobre afloramientos Ăgneos (granito, pĂłrfidos, etc.) son de naturaleza fundamentalmente caolinita, con una alta proporciĂłn de minerales micáceos, cuarzo libre como mineral accesorio y un contenido variable en Ăłxidos de hierro y aluminio hidratados. Minerales con espaciados de 14 A apenas son apreciables. Las muestras procedentes de pizarras alteradas de El AndĂ©valo destacan por su mayor contenido en Hita, seguida de caolinita y geles de hierro y aluminio. Se intensifica la presencia de minerales montmorillonĂticos. Las pruebas tecnolĂłgicas indican que se trata de materiales naturales de buenas propiedades cerámicas, con alto contenido en hierro, aptos para los usos que hemos citado
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