... Hacia un modelo espacial de la cultura de los Talayots de Mallorca. Autores: Francisco JavierAramburu-Zabala Higuera; Localización: Saguntum: Papeles del Laboratorio de Arqueología de Valencia, ISSN 0210-3729, Nº 27, 1994 , págs.... more
... Hacia un modelo espacial de la cultura de los Talayots de Mallorca. Autores: Francisco JavierAramburu-Zabala Higuera; Localización: Saguntum: Papeles del Laboratorio de Arqueología de Valencia, ISSN 0210-3729, Nº 27, 1994 , págs. 125-136. Fundación Dialnet. ...
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A medição do templo em Apocalipse 11:1-2 tem sido entendida de várias maneiras segundo as diferentes perspectivas interpretativas. Uma das principais chaves no entendimento tanto deste texto quanto do Apocalipse como um todo, é a alusão... more
A medição do templo em Apocalipse 11:1-2 tem sido entendida de várias maneiras segundo as diferentes perspectivas interpretativas. Uma das principais chaves no entendimento tanto deste texto quanto do Apocalipse como um todo, é a alusão ao Antigo Testamento por trás da passagem. Frequentemente têm sido atribuídos dois panos de fundo do Antigo Testamento para tal imagem, no entanto esse estudo visa esclarecerá que tal conexão não é legitima na sua totalidade, mas que existe um pano de fundo danielico na medição do templo de Apocalipse 11:1-2.
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A new lattice gas is introduced based on the Chapman–Enskog expansion for small Knudsen numbers of a model Boltzmann equation. This kind of discrete dynamical system is intended to narrow the gap between ordinary lattice gases and the... more
A new lattice gas is introduced based on the Chapman–Enskog expansion for small Knudsen numbers of a model Boltzmann equation. This kind of discrete dynamical system is intended to narrow the gap between ordinary lattice gases and the macroscopic incompressible Navier–Stokes equations, and to increase the efficiency and flexibility of lattice gas methods. The large scale evolution of the gas is shown to obey the Navier–Stokes equations. The linear stability of the system, considered as a finite‐difference scheme, is studied.
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Información del artículo Arquitectura en Cantabria en la época del Renacimiento.I. Los arquitectos.
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Resumen El objeto de este trabajo es dar a conocer las posibilidades de las Oficinas &Empleo del 1k/EM en el desarrollo de lasprácticas integradas de la Diplomatura de Relaciones Laborales. En particular hemos ha comprobado que, con... more
Resumen El objeto de este trabajo es dar a conocer las posibilidades de las Oficinas &Empleo del 1k/EM en el desarrollo de lasprácticas integradas de la Diplomatura de Relaciones Laborales. En particular hemos ha comprobado que, con una dirección ...
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... Adiciones al inventario de yacimientos arqueológicos del término de Palma. Autores: FranciscoJavier Aramburu-Zabala Higuera; Localización: Bolletí de la Societat Arqueològica Lul·liana: Revista d'estudis històrics, ISSN... more
... Adiciones al inventario de yacimientos arqueológicos del término de Palma. Autores: FranciscoJavier Aramburu-Zabala Higuera; Localización: Bolletí de la Societat Arqueològica Lul·liana: Revista d'estudis històrics, ISSN 0212-7458, Nº. 54, 1998 , págs. 399-406. ...
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The stability and transient response of solid propellant combustion has received considerable attention in the literature, using, after Zeldovich (1942 and 1964) and Denison and Baum (1961), the quasisteady approximation for the gas... more
The stability and transient response of solid propellant combustion has received considerable attention in the literature, using, after Zeldovich (1942 and 1964) and Denison and Baum (1961), the quasisteady approximation for the gas phase. This approximation results from the small value of the ratio of gas-to-solid densities. The analysis of the stability of a simple model of solid propellant combustion is given here. The model includes a surface pyrolisis reaction and a gas phase reaction, assuming the gas phase combustion process to be quasisteady and quasiplanar. The quasiplanar assumption results from the moderately small value of the ratio of thickness of the gas-to-solid transport zones, or from large values of the effective nondimensional activation energy of the gas phase reaction.
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Spontaneous capillary rise of viscous liquid between two sinusoidally corrugated plates, which are vertically placed in a gravitational field, is studied. The effect of geometrical variations perpendicular to the direction of penetration... more
Spontaneous capillary rise of viscous liquid between two sinusoidally corrugated plates, which are vertically placed in a gravitational field, is studied. The effect of geometrical variations perpendicular to the direction of penetration on the rate of capillary penetration is analyzed by using the lubrication theory. Numerical solutions of the Reynolds equations for the local free surface and pressure distribution in the fluid and the spatially-averaged penetration length are given. It was found that the amplitude of corrugation determines the time necessary to reach the equilibrium length when constant average capillary gap width is applied. These results also illustrate some features experimentally observed in spontaneous penetration of liquids into porous materials where the permeability changes spatially. Many geological and technological applications involve this type of anomalies.
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This work is intended for getting a better knowledge about the role that fractures play in the transport of passive substances in the geophysical context (diagenesis and dispersion of contaminants are phenomena tight related). The thermal... more
This work is intended for getting a better knowledge about the role that fractures play in the transport of passive substances in the geophysical context (diagenesis and dispersion of contaminants are phenomena tight related). The thermal convection and the transport of an ideal tracer in a single, tilted, small aspect ratio tube embedded in an impermeable rock were studied. The fluid-filled tube and the tube filled with a saturated porous medium were analyzed. The impervious rock is affected by a constant vertical temperature gradient and its thermal conductivity is large respect to that of the flow zone. Closed-form analytical solutions, restricted to small Rayleigh numbers, were obtained for the temperature in the solid and for velocity and temperature within the flow zones. Experiments for the fluid-filled tube showed good agreement. The temperature distribution in the solid was measured by an infrared camera and by the PIV technique the convective velocity field was estimated. ...
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In this work we are interested in describing the shape of a single drop which emerges on top of a vertical tube just when it reaches the edge of the tube. We assume that the liquid is injected at a very low, constant, volume flow rate Q.... more
In this work we are interested in describing the shape of a single drop which emerges on top of a vertical tube just when it reaches the edge of the tube. We assume that the liquid is injected at a very low, constant, volume flow rate Q. We consider, as a first approximation, that the drop shape can be calculated by using a balance of force equation that relates the hydrostatic and capillary presures. The results are valid for cases of good and poor wetting, respectively, and for high and low Bond numbers. We present experiments that validate the numerical results obtained for the drop shapes.
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We review recent developments of the Lattice Boltzmann Equation method (LBE) for incompressible hydrodynamics. Modifications of the discrete Boltzmann equation for a lattice gas to improve its efficiency as a numerical method are... more
We review recent developments of the Lattice Boltzmann Equation method (LBE) for incompressible hydrodynamics. Modifications of the discrete Boltzmann equation for a lattice gas to improve its efficiency as a numerical method are discussed. Estimations of the minimum lattice size necessary for high Reynolds number simulations are given, showing that this minimum arises from physical properties of the flows (range of scales to resolve) and not from any intrinsic limitation of the lattice gas method. Applications of the LBE to several problems are presented.
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Without Abstract
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The solidification of a liquid flowing along a flat plate whose temperature presents a step reduction from a value above to a value below the melting temperature of the liquid is shown to promote a viscous–inviscid interaction region. The... more
The solidification of a liquid flowing along a flat plate whose temperature presents a step reduction from a value above to a value below the melting temperature of the liquid is shown to promote a viscous–inviscid interaction region. The structure of the flow in this region and the growth of the solid phase crust above the plate are described in the limit of high Reynolds numbers using triple‐deck theory. Boundary‐layer separation, which is a regular process in the framework of triple‐deck theory, is shown to occur under appropriate conditions, namely for severe plate temperature reductions leading to thick solid crusts. A simplified approximate method is introduced to deal with these separated flows.
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The presence of space charge in a dielectric liquid subject to an electric field leads to a Coulomb force that may set the liquid into motion. Such motion is of interest in a number of applications including electrostatic precipitators,... more
The presence of space charge in a dielectric liquid subject to an electric field leads to a Coulomb force that may set the liquid into motion. Such motion is of interest in a number of applications including electrostatic precipitators, electrohydrodynamic (EHD) ion-drag pumps, and several instances of EHD laminar and turbulent mixing, which depend on the transport of charge, momentum or heat across the liquid [1],[2].
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We present a comprehensive theoretical study of the shallow donor and acceptor states and their binding energies in large bandgap bulk nitride semiconductors. An envelope function scheme within the effective mass theory in a multi-band... more
We present a comprehensive theoretical study of the shallow donor and acceptor states and their binding energies in large bandgap bulk nitride semiconductors. An envelope function scheme within the effective mass theory in a multi-band formalism was used to obtain the impurity levels in a variational fashion. Suitable atomic pseudopotentials were employed to resemble the impurity potential of the different
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The adequacy of the ``assumed pdf" approximation as a subgrid model for the reaction terms in a fast, cold, diffusion-controlled turbulent reacting flow, is tested at different resolutions using DNS data from three-dimensional,... more
The adequacy of the ``assumed pdf" approximation as a subgrid model for the reaction terms in a fast, cold, diffusion-controlled turbulent reacting flow, is tested at different resolutions using DNS data from three-dimensional, temporally-growing turbulent mixing layers, at Reynolds numbers beyond the mixing transition. The subgrid scalar fluctuation variance is estimated using a similarity assumption on the scalar field filtered
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In this work we have considered the problem of the growth and detachment of bubbles in a viscous liquid in finite reservoirs where axisymmetrical walls were located near the gas injection orifice. We studied numerically and experimentally... more
In this work we have considered the problem of the growth and detachment of bubbles in a viscous liquid in finite reservoirs where axisymmetrical walls were located near the gas injection orifice. We studied numerically and experimentally how the coaxial pipe and inverted-cone walls affect the shape, final volume and coalescence of bubbles under conditions of constant gas flow rate,
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In this note, the onset of the Gunn effect in the classical 1D unipolar drift-diffusion model is investigated through a Hopf bifurcation analysis of the spontaneous current oscillation. It is found that in the case that the dimensionless... more
In this note, the onset of the Gunn effect in the classical 1D unipolar drift-diffusion model is investigated through a Hopf bifurcation analysis of the spontaneous current oscillation. It is found that in the case that the dimensionless semiconductor length is of order unity the bifurcation is supercritical, and becomes subcritical for dimensionless lengths above a certain critical value.
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A linear stability analysis of the rapid evaporation of a superheated liquid is presented. Due to the small value of the vapor-to-liquid density ratio, the evolution time for the perturbations that can grow is found to be much shorter... more
A linear stability analysis of the rapid evaporation of a superheated liquid is presented. Due to the small value of the vapor-to-liquid density ratio, the evolution time for the perturbations that can grow is found to be much shorter than that of the basic planar configuration and the normal mode analysis for steady basic solutions is applicable as an approximation. Depending on the values of the surface tension, the effective gravity acceleration, and the instantaneous vaporizing mass flux, an initial perturbation of a given wavelength can grow directly or give rise to an oscillatory state. In the second case, the slow evolution of the oscillations depends on the liquid viscosity and on temperature sensitivities of the evaporating mass flux and the surface tension.
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Numerical computations and order-of-magnitude estimates are used to analyze a jet of a very viscous liquid of finite electrical conductivity that is injected at a constant flow rate in an immiscible dielectric liquid under the action of... more
Numerical computations and order-of-magnitude estimates are used to analyze a jet of a very viscous liquid of finite electrical conductivity that is injected at a constant flow rate in an immiscible dielectric liquid under the action of an electric field. The conditions under which the injected liquid can form an elongated meniscus with a thin jet issuing from its apex (a cone-jet) are investigated by computing the flow, the electric field, and the transport of electric charge in the meniscus and a leading region of the jet. The boundaries of the domain of operation of the cone-jet mode are discussed. The current transfer region determining the electric current carried by the jet is analyzed taking into account the viscous drag of the dielectric liquid surrounding the jet. Conditions under which the electric current/flow rate characteristic follows a square root law or departs from it are discussed.
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In this work we present a theoretical study of the spontaneous capillary flow, of a viscous liquid, developed into the gap between a couple of parallel corrugated plates (corrugated Hele- Shaw cell). The periodical corrugation of the... more
In this work we present a theoretical study of the spontaneous capillary flow, of a viscous liquid, developed into the gap between a couple of parallel corrugated plates (corrugated Hele- Shaw cell). The periodical corrugation of the interior walls of the plates is assumed as a sine-like pattern, transverse to the flow direction. Such a configuration may generate periodical gaps with a structure where zones of maximum and minimum closing occur. This is a simple idealization of typical micro and nano fabricated gaps used to mould polymers by capillarity. By using the lubrication theory we found that a very peculiar temporal flow is developed which could be of interest to improve the knowledge of this type of moulding.
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The spread of a flame along a thermally thick horizontal solid fuel cylinder in a quiescent atmosphere is analyzed modeling the gas-phase kinetics by means of a single-step irreversible Arrhenius reaction and assuming that vaporization of... more
The spread of a flame along a thermally thick horizontal solid fuel cylinder in a quiescent atmosphere is analyzed modeling the gas-phase kinetics by means of a single-step irreversible Arrhenius reaction and assuming that vaporization of the solid occurs at a constant temperature. The natural convection flow of the warm gas surrounding the flame is mostly normal to the axis of the cylinder, but a weak flow is also induced along the axis by the axial gradient of the pressure variation that gravity generates in the warm gas. This latter flow aids flame propagation in the lower part of the cylinder. The effects of finite rate kinetics and of radiative losses from the surface of the solid are studied, computing the spread rate as a function of the Damkohler number, the oxygen concentration in the atmosphere and the strength of the radiative losses for a set of material properties chosen to mimic flame spread on PMMA. The effect of a small inclination of the cylinder is also discussed, showing that a continuous transition from upward to down ward flame spread occurs when the tilt angle is small of the order of the inverse of the power 1/8 of the Grashof number based on the radius of the cylinder.
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An order-of-magnitude analysis of the flow around the tip of the meniscus and in the jet of an electrospray of a very polar liquid in the cone-jet mode is reported. Assuming that a long stationary jet exists, the relationship between the... more
An order-of-magnitude analysis of the flow around the tip of the meniscus and in the jet of an electrospray of a very polar liquid in the cone-jet mode is reported. Assuming that a long stationary jet exists, the relationship between the electric current and the flow rate is predicted to change from the well-known square root law for high flow
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An asymptotic order-of-magnitude description is given of the structure of a circular laminar hydraulic jump for large values of the Reynolds and Froude numbers of the flow entering the jump. The results are compared with numerical... more
An asymptotic order-of-magnitude description is given of the structure of a circular laminar hydraulic jump for large values of the Reynolds and Froude numbers of the flow entering the jump. The results are compared with numerical solutions of the boundary layer equations for the flow in a liquid layer on a horizontal disk and with experimental results existing in the literature.
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An analysis is presented of the two-dimensional natural convection flow induced under an adiabatic unbounded horizontal surface by an embedded constant strength line heat source that is switched on at a certain initial time. After a... more
An analysis is presented of the two-dimensional natural convection flow induced under an adiabatic unbounded horizontal surface by an embedded constant strength line heat source that is switched on at a certain initial time. After a sufficiently long time, the flow takes on an asymptotic boundary layer form in most of the warm fluid, with all the variables scaling as powers of time. This boundary layer includes a region of reverse flow and a sublayer of high temperature near the source. In addition, the limiting solution displays two small nonslender regions around the source and the front of the spreading layer. The analogous flow in a starting vertical plume is also discussed.
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A simple model is proposed for the flow around the apex of a meniscus of a liquid undergoing ion evaporation in a vacuum under the action of a high electric field. The model includes a simplified description of the effect of the space... more
A simple model is proposed for the flow around the apex of a meniscus of a liquid undergoing ion evaporation in a vacuum under the action of a high electric field. The model includes a simplified description of the effect of the space charge surrounding the evaporating surface, and the idealizations that ion evaporation occurs at a constant surface field and that the electric field and viscous forces are negligible in the liquid. In agreement with known experimental and theoretical results for liquid metal ion sources, numerical solutions of the model problem show that the meniscus develops a protrusion and the current-voltage characteristic is linear in a range of voltages above an extinction voltage at which evaporation switches off. An oscillatory regime and transient evolutions ending in surface pinch-off and the emission of a drop are described, and the stabilizing effect of the pressure variations due to the evaporation flux is discussed. Asymptotic estimates for large evaporation flow rates are worked out.
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ABSTRACT
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ABSTRACT
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Worldwide prevalence of amoebiasis is estimated at 4 x 10(8) cases/year, yet only one of about 300 individuals harbouring Entamoeba histolytica suffers tissue invasion and these cases are mostly concentrated in certain areas of Asia,... more
Worldwide prevalence of amoebiasis is estimated at 4 x 10(8) cases/year, yet only one of about 300 individuals harbouring Entamoeba histolytica suffers tissue invasion and these cases are mostly concentrated in certain areas of Asia, Africa and Latin America. Patients with amoebic abscess of the liver (AAL) represent only a small fraction of that. These contrasting figures have been tentatively explained on the one hand through variations in sex, immunocompetence, nutritional and other socioeconomic features of the host, and on the other hand through differences in parasite virulence. In order to explore a possible association between the major histocompatibility complex (MHC) and AAL susceptibility, we studied the HLA profile in 31 Mexican mestizos with AAL and compared it to race and socioeconomically matched controls. Mexican mestizo patients with AAL revealed a significant increase in HLA-Bw16 and HLA-DR3 which could suggest an HLA-related susceptibility to liver invasion by E. histolytica.
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ecnica de Madrid, 28040 Madrid, Spain An analysis is presented of the time-periodic conjugate free convective heat transfer from a long vertical, thermally thin fin heated from above to the surrounding fluid. The temperature at the top of... more
ecnica de Madrid, 28040 Madrid, Spain An analysis is presented of the time-periodic conjugate free convective heat transfer from a long vertical, thermally thin fin heated from above to the surrounding fluid. The temperature at the top of the fin oscillates with a given frequency about a mean value that is higher than the temperature of the ambient fluid. The solution for very long fins depends on four nondimensional parameters: the Prandtl number of the fluid; the relative amplitude of the thermal oscillation; the Fourier number, which is the ratio of the period of the thermal oscillation to the conduction time in the fin over a length determined by the steady solution; and the ratio of this latter time to the residence time of the fluid in the boundary layer. Numerical and asymptotic results are given covering a wide region of the parametric space. A linearized version of the governing equations is worked out and shown to give oscillatory Nusselt numbers in excellent accordance with the results from the full nonlinear equations.
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The flow field of a diffusion flame attached to a thick-rim injector between two coflowing streams of fuel and oxidiser is analysed in the Burke–Schumann limit of infinitely fast reaction rate. The length of the recirculation region... more
The flow field of a diffusion flame attached to a thick-rim injector between two coflowing streams of fuel and oxidiser is analysed in the Burke–Schumann limit of infinitely fast reaction rate. The length of the recirculation region immediately behind the injector and the velocity of the recirculating fluid are proportional to the shear stresses of the reactant streams on the wall of the injector for a range of rim thicknesses, and the structure of the flow in the wake depends then on three main non-dimensional parameters, measuring the gas thermal expansion due to the chemical heat release, the air-to-fuel stoichiometric ratio of the reaction, and the air-to-fuel ratio of wall shear stresses. The recirculation region shortens with increasing heat release, and the position of the flame in this region depends on the other two parameters. An asymptotic analysis is carried out for very exothermic reactions, showing that the region of high temperature around the flame is confined by nea...