... 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...
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An analysis is presented of some steady natural convection flows at large distances downstream of point heat sources on solid walls. These asymptotic self-similar flows depend only on the Prandtl number of the fluid. The flow induced by a... more
An analysis is presented of some steady natural convection flows at large distances downstream of point heat sources on solid walls. These asymptotic self-similar flows depend only on the Prandtl number of the fluid. The flow induced by a localized source on an adiabatic wall that is vertical or facing downwards is described numerically, whereas the flow due to a localized source on a wall facing upwards separates and leads to a self-similar plume. When the wall is held at the same temperature as the ambient fluid far from the source, the flow is described by a self-similar solution of the second kind, with the algebraic decay of the temperature excess above the ambient temperature determined by a nonlinear eigenvalue problem. Numerical solutions of this problem are presented for two-dimensional and localized heat sources on a vertical wall, whereas the problem for a localized heat source under an inclined isothermal downwards-facing wall turns out to capture the Rayleigh–Taylor ins...
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The coupling of the temperature and velocity fields by buoyancy in a laminar two-dimensional wall jet over a finite-length horizontal plate is studied numerically and analytically in the asymptotic limit of infinite Reynolds number. Two... more
The coupling of the temperature and velocity fields by buoyancy in a laminar two-dimensional wall jet over a finite-length horizontal plate is studied numerically and analytically in the asymptotic limit of infinite Reynolds number. Two configurations are considered leading to a cold layer of fluid over the plate, namely an ambient-temperature jet over a cooled plate and a cold jet over an insulated plate. In both cases buoyancy generates an adverse pressure gradient that may separate the flow if the Froude number is sufficiently small and always makes the solution everywhere over the plate dependent on the conditions at the downstream boundary. In the limit of very small Froude number separation occurs in a viscous–inviscid interaction region near the origin of the jet, leading to a separation bubble that covers a fraction of the plate dependent on the Prandtl number. The scalings of the solution in this asymptotic limit are obtained by order of magnitude estimations in the differe...
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An analysis of the quasi-steady streaming of the liquid in a vertically vibrated horizontal soap film is reported. The air around the soap film is seen to play a variety of roles: it transmits normal and tangential oscillatory stresses to... more
An analysis of the quasi-steady streaming of the liquid in a vertically vibrated horizontal soap film is reported. The air around the soap film is seen to play a variety of roles: it transmits normal and tangential oscillatory stresses to the film, damps out Marangoni waves, and forces non-oscillatory deflection of the film and tangential motion of the liquid. Non-oscillatory volume forcing originating inside the liquid is also analysed. This forcing dominates the quasi-steady streaming when the excitation frequency is close to the eigenfrequency of a Marangoni mode of the soap film, while both volume forcing in the liquid and surface forcing of the gas on the liquid are important when no Marangoni mode resonates. Different manners by which the combined forcings can induce quasi-steady streaming motion are discussed and some numerical simulations of the quasi-steady liquid flow are presented.
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Contour dynamics methods are used to determine the shapes and speeds of planar, steadily propagating, solitary waves on a two-dimensional layer of uniform vorticity adjacent to a free-slip plane wall in an, otherwise irrotational,... more
Contour dynamics methods are used to determine the shapes and speeds of planar, steadily propagating, solitary waves on a two-dimensional layer of uniform vorticity adjacent to a free-slip plane wall in an, otherwise irrotational, unbounded incompressible fluid, as well as of axisymmetric solitary waves propagating on a tube of azimuthal vorticity proportional to the distance to the symmetry axis. A continuous family of solutions of the Euler equations is found in each case. In the planar case they range from small-amplitude solitons of the Benjamin–Ono equation to large-amplitude waves that tend to one member of the touching pair of counter-rotating vortices of Pierrehumbert (1980), but this convergence is slow in two small regions near the tips of the waves, for which an asymptotic analysis is presented. In the axisymmetric case, the small-amplitude waves obey a Korteweg–de Vries equation with small logarithmic corrections, and the large-amplitude waves tend to Hill's spherica...
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An analysis is presented of the flow in a layer of liquid whose surface tension varies under the action of a moving surface heat flux distribution chosen to model the spread of a flame over the liquid. Subject to this heat flux, the... more
An analysis is presented of the flow in a layer of liquid whose surface tension varies under the action of a moving surface heat flux distribution chosen to model the spread of a flame over the liquid. Subject to this heat flux, the surface temperature increases from the ambient temperature of the liquid, far upstream, to its vaporization temperature at a moving vaporization front, and stays constant at this value downstream of the vaporization front. The speed of the front is determined by a condition of regularity of the temperature. Three different regimes are found which correspond to the uniform, pulsating and pseudo-uniform regimes of flame spread observed experimentally when the ambient temperature of the liquid, or the strength of the surface heat flux, is decreased. The first and third of these are stationary regimes of high and low front speed, and the second is an oscillatory regime featuring long phases of low speed and short pulses of high speed. An asymptotic descripti...
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The β-assumed-p.d.f. approximation of Cook & Riley (1994) is tested as a subgrid model for the LES computation of non-premixed turbulent reacting flows, in the limit of infinitely fast chemistry, for two plane constant-density turbulent... more
The β-assumed-p.d.f. approximation of Cook & Riley (1994) is tested as a subgrid model for the LES computation of non-premixed turbulent reacting flows, in the limit of infinitely fast chemistry, for two plane constant-density turbulent mixing layers with different degrees of intermittency. Excellent results are obtained in the computation of plane-averaged properties, such as product mass fractions and relatively high powers of the temperature, and even of the p.d.f. of the conserved scalar itself. In all these cases the errors are small enough to be useful in practical applications. The analysis is extended to slightly out-of-equilibrium problems, such as the generation of radicals, and formulated in terms of the p.d.f. of the gradient of the mixture fraction. It is shown that the form of the conditional gradient distribution is universal in a wide range of cases, whose limits are established. Within those limits, engineering approximations to the radical concentration are also po...
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The hydraulic jump appearing in the viscous laminar flow of a thin liquid layer over a finite horizontal plate is studied using the boundary-layer approximation for the flow in and around the jump. The position and structure of the jump... more
The hydraulic jump appearing in the viscous laminar flow of a thin liquid layer over a finite horizontal plate is studied using the boundary-layer approximation for the flow in and around the jump. The position and structure of the jump are determined by numerically solving the resulting problem with a boundary condition at the edge of the plate that expresses the matching of the layer with the shorter region where the liquid turns around and falls under the action of gravity. When the Froude number of the flow ahead of the jump is very large, the jump is much shorter than the horizontal extent of the layer, though still much longer than its depth. An asymptotic description of the inner structure of such a jump is given, building upon the analysis of Bowles & Smith for the short interaction region at the leading end of the jump. This structure consists of a fast moving separated flow in the upper part of the layer that progressively slows down by ingesting new fluid across its lower...
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Abstract An analysis is presented of the laminar natural convection flow due to a localized heat source on the centerline of a long vertical channel or pipe whose walls are kept at a constant temperature. Stationary solutions are obtained... more
Abstract An analysis is presented of the laminar natural convection flow due to a localized heat source on the centerline of a long vertical channel or pipe whose walls are kept at a constant temperature. Stationary solutions are obtained for infinitely long and finite length channels, the asymptotic limit of infinite Rayleigh numbers is discussed, and an optimal height of the channel is found leading to maximum mass flux and minimum temperature for a given heat release rate.
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Background.No information is available about the financial impact of central venous catheter (CVC)-associated bloodstream infection (BSI) in Mexico.Objective.To calculate the costs associated with BSI in intensive care units (ICUs) in... more
Background.No information is available about the financial impact of central venous catheter (CVC)-associated bloodstream infection (BSI) in Mexico.Objective.To calculate the costs associated with BSI in intensive care units (ICUs) in Mexico City.Design.An 18-month (June 2002 through November 2003), prospective, nested case-control study of patients with and patients without BSI.Setting.Adult ICUs in 3 hospitals in Mexico City.Patients and Methods.A total of 55 patients with BSI (case patients) and 55 patients without BSI (control patients) were compared with respect to hospital, type of ICU, year of hospital admission, length of ICU stay, sex, age, and mean severity of illness score. Information about the length of ICU stay was obtained prospectively during daily rounds. The daily cost of ICU stay was provided by the finance department of each hospital. The cost of antibiotics prescribed for BSI was provided by the hospitals' pharmacy departments.Results.For case patients, the ...
Research Interests: Public Health, Mexico, Humans, Infection Control, Mexico City, and 14 moreHospital costs, Female, Male, Sepsis, Length of Stay, Intensive Care Unit, Middle Aged, Adult, MEXICO, Intensive Care Units, Central Venous Catheter, Case Control Studies, Severity of Illness Index, and Medical and Health Sciences
... fluids, and the resulting parabolic equations are solved numerically using either series expansionmethods or finite ... Details of the numerical procedure are not presented here as they can be found in [11 ... 1 − x) small, calling... more
... fluids, and the resulting parabolic equations are solved numerically using either series expansionmethods or finite ... Details of the numerical procedure are not presented here as they can be found in [11 ... 1 − x) small, calling for the rescaling (30) In terms of these new variables the ...
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... Dr. DAN ROTHMAN is kindly acknowledged for many helpful discussions. We are grateful to an anonimous referee whose criticism greatly improved the quality of this paper. Page 7. 438 EUROPHYSICS LETTERS REFERENCES ...
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... further loss of resolution, it is also possible to average over the flow residence time in a ... 3090 vector computer) the computational cost of substituting the Boolean operations of the direct simulation by ... 4, the break-even Re,... more
... further loss of resolution, it is also possible to average over the flow residence time in a ... 3090 vector computer) the computational cost of substituting the Boolean operations of the direct simulation by ... 4, the break-even Re, for the Boltzmann method in the 2D calculation is about ...
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... 345-349 (1989) 15 June 1989 Lattice Gas Dynamics with Enhanced Collisions. F. J. HIGUERA(*), S. SUCCI(**) and R. BENZI(***) Department of Fluid Mechanics, School of Aeronautics Pxa. ... PACS. 61.205 - Computer simulation of static and... more
... 345-349 (1989) 15 June 1989 Lattice Gas Dynamics with Enhanced Collisions. F. J. HIGUERA(*), S. SUCCI(**) and R. BENZI(***) Department of Fluid Mechanics, School of Aeronautics Pxa. ... PACS. 61.205 - Computer simulation of static and dynamic behaviour. ...
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It is shown that the lattice Boltzmann equation deriving from the Frisch-Hasslacher-Pomeau cellular automation, being free from microscopic fluctuations, provides a new appealing tool to simulate realistic incompressible hydrodynamics.... more
It is shown that the lattice Boltzmann equation deriving from the Frisch-Hasslacher-Pomeau cellular automation, being free from microscopic fluctuations, provides a new appealing tool to simulate realistic incompressible hydrodynamics. Numerical results pertaining to a two-dimensional flow past a cylinder are reported and compared with numerical and experimental data available in the literature.
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... Contribución al estudio espacial del Paleolítico Superior cantábrico: el caso asturiano. Autores: Francisco Javier Aramburu-Zabala Higuera; Localización: Arqueología espacial, ISSN 1136-8195, Nº 2, 1984 (Ejemplar dedicado a: Estudios... more
... Contribución al estudio espacial del Paleolítico Superior cantábrico: el caso asturiano. Autores: Francisco Javier Aramburu-Zabala Higuera; Localización: Arqueología espacial, ISSN 1136-8195, Nº 2, 1984 (Ejemplar dedicado a: Estudios diacrónicos y Paleolítico) , págs. ...
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... Los yacimientos arqueológicos del valle del Galatzó (Mallorca). Autores: Francisco JavierAramburu-Zabala Higuera; Localización: Bolletí de la Societat Arqueològica Lul·liana: Revista d'estudis històrics, ISSN 0212-7458, Nº. 55,... more
... Los yacimientos arqueológicos del valle del Galatzó (Mallorca). Autores: Francisco JavierAramburu-Zabala Higuera; Localización: Bolletí de la Societat Arqueològica Lul·liana: Revista d'estudis històrics, ISSN 0212-7458, Nº. 55, 1999 , págs. 327-334. Fundación Dialnet. ...
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... Francisco Higuera Corresponding Author Contact Information , Hilda Hidalgo, Carlos J. Sanchez and Armando Valle. Hospital General de Mexico, Mexico City, Mexico. Received 12 March 1993. ... (Abstract)HA Hammill, HS Glazier and RJ... more
... Francisco Higuera Corresponding Author Contact Information , Hilda Hidalgo, Carlos J. Sanchez and Armando Valle. Hospital General de Mexico, Mexico City, Mexico. Received 12 March 1993. ... (Abstract)HA Hammill, HS Glazier and RJ Townsend et al., Development of topical ...
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To ascertain the effect of an infection control program including process control on intensive care unit (ICU) rates of intravascular device (IVD)-associated bloodstream infection (BSI). Two level III adult ICUs in one public university... more
To ascertain the effect of an infection control program including process control on intensive care unit (ICU) rates of intravascular device (IVD)-associated bloodstream infection (BSI). Two level III adult ICUs in one public university hospital in Mexico: one medical surgical ICU and one neurosurgical ICU. POPULATION STUDY: All adult patients admitted to study units who had a central venous catheter (CVC) in place for at least 24 hrs. A prospective before/after trial in which rates of IVD-associated BSI are determined during a period of active surveillance without process control (phase 1) were compared with rates of IVD-associated BSI after implementing an infection control program applying process control (phase 2). Six hundred five IVD-days were accumulated in phase 1, and 2824 IVD-days were accumulated during phase 2. Compliance with CVC site care and hand hygiene improved significantly from baseline during the study period: placing a gauze dressing over the catheter insertion site (99.24% vs. 86.69%, respectively; relative risk [RR] = 1.14; 95% confidence interval [CI] = 1.07-1.22; p = .0000), proper use of gauze for vascular catheter insertion site (97.87% vs. 84.21%, respectively; RR = 1.16; 95% CI = 1.09-1.24; p = .0000), documentation of the duration of the administration set of the vascular catheter (93.85% vs. 40.69%, respectively; RR = 2.34; 95% CI = 2.14-2.56; p = .0000), and hand hygiene before contact with the patient (84.9% vs. 62%, respectively; RR = 1.37; 95% CI = 1.21-1.51; p = .0000). Overall rates of IVD-associated BSI were lowered significantly from baseline rates after implementation of process control (19.5 vs. 46.3 BSIs per 1000 IVD-days, respectively; RR = 0.42; 95% CI = 0.27-0.66; p = .0001). Overall rates of crude unadjusted mortality were lowered significantly from baseline rates (48.5% vs. 32.8% per 100 discharges, respectively; RR = 0.68; 95% CI = 0.50-0.31; p = .01). Implementation of an infection control program utilizing education, process control, and performance feedback was associated with significant reductions in rates of IVD-associated BSI and mortality.
Research Interests: Nursing, Hospital Infection, Medicine, Critical Care, Critical Care Medicine, and 15 moreMexico, Humans, Infection Control, Developing Country, Clinical Sciences, Intensive Care Unit, Adult, Bacteremia, MEXICO, Population Study, Intensive Care Units, Central Venous Catheter, Confidence Interval, Nosocomial infection, and Cross Infection
The flow induced in a layer of liquid fuel at sub-flash temperature by the thermocapillary forces associated with the spreading of a flame that heats and vaporizes the liquid is analysed numerically and asymptotically, for large values of... more
The flow induced in a layer of liquid fuel at sub-flash temperature by the thermocapillary forces associated with the spreading of a flame that heats and vaporizes the liquid is analysed numerically and asymptotically, for large values of the Marangoni number and of the Reynolds number based on the propagation speed. Upstream heat convection in a recirculating region moving with
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An analysis is carried out of the spread of a flame along a horizontal solid fuel rod, for which a weak aiding natural convection flow is established in the underside of the rod by the action of the axial gradient of the pressure... more
An analysis is carried out of the spread of a flame along a horizontal solid fuel rod, for which a weak aiding natural convection flow is established in the underside of the rod by the action of the axial gradient of the pressure variation that gravity generates in the warm gas surrounding the flame. The spread rate is determined in the limit of infinitely fast kinetics, taking into account the effect of radiative losses from the solid surface. The effect of a small inclination of the rod is discussed, pointing out a continuous transition between upward and downward flame spread. Flame spread along flat-bottomed solid cylinders, for which the gradient of the hydrostatically generated pressure drives the flow both along and across the direction of flame propagation, is also analysed.
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An analysis is presented of the steady two-dimensional spread of a flame down a vertical surface of a thermally thick solid fuel, under the assumptions that the gas-phase reaction is infinitely fast and that vaporization of the solid... more
An analysis is presented of the steady two-dimensional spread of a flame down a vertical surface of a thermally thick solid fuel, under the assumptions that the gas-phase reaction is infinitely fast and that vaporization of the solid occurs at a constant temperature. A condition of regularity of the solid phase temperature, the gas phase mixture fraction and enthalpy, and the mass vaporization flux at the vaporization front is proposed to determine the flame spread rate. Numerical solutions computed using this condition show that the spread rate decreases with decreasing heat of reaction and becomes zero for a certain heat of reaction. An order-of-magnitude analysis is given for the case when heat conduction in the solid dominates heat conduction in the gas.
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Research Interests: Mechanical Engineering, Chemical Engineering, Chemistry, Kinetics, Heat Transfer, and 12 moreAutomotive Engineering, Fossil Fuels, Activation Energy, Radiative Heat Transfer, Heat Conduction, Particle Size, Kinetic Energy, Chemical Reaction, Energy Transfer, Differential equation, Reaction Kinetics, and Energy Source
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Abstract Plantejament processualista neo-evolucionista...+ Factors naturals+ Factors naturals transf p home+ Factors humans (sist socio-econ)(273) Variaci paisatge entesa en termes d'adaptaci al medi. Factors determinants: demografia... more
Abstract Plantejament processualista neo-evolucionista...+ Factors naturals+ Factors naturals transf p home+ Factors humans (sist socio-econ)(273) Variaci paisatge entesa en termes d'adaptaci al medi. Factors determinants: demografia i ramaderia (274) Constants ...