795 research outputs found

    Impacto socio ambiental y comprensión de percepciones sobre la presencia de las empresas industriales petroleras en la vereda Calderón, puerto Boyacá - Boyacá

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    Maestría en Desarrollo Sostenible y Medio Ambiente, Facultad de Ciencias Contables, Económicas y Administrativas.Con el presente trabajo de investigación se pretende describir el impacto socio ambiental en la vereda Calderón del Municipio de Puerto Boyacá (Boyacá), y comprender las categorías que surgen de las percepciones de la comunidad, como consecuencia del funcionamiento de las empresas industriales del sector petrolero en dicha vereda. Se analizan algunas variables sociales como son la calidad de vida, aspectos ambientales (cambios del área), y cómo la industria petrolera ha impactado positiva o negativamente en esta región. La investigación desarrollada es mixta, de carácter descriptivo, porque busca caracterizar el impacto socio ambiental producido por la industria petrolera en la vereda Calderón del Municipio de Puerto Boyacá, y hermenéutica, en la intencionalidad de comprender las percepciones que ésta comunidad tiene sobre la presencia de estas empresas petroleras. La vereda Calderón pertenece al municipio de Puerto Boyacá, en el departamento Boyacá, y se ubica en un área de 150 km2, la muestra es representativa y se selecciona al azar (según formula estadística), la cual es de 235 habitantes. Para la recolección de información se usó una encuesta que buscó de manera natural y espontánea las percepciones, que además se convierte en la unidad de análisis, que tiene la comunidad acerca del funcionamiento de empresas industriales petroleras en esta vereda. También se aplicó una entrevista a veinte (20) informantes que han vivido más de 15 años en la vereda, y con conocimiento de lo que ha venido sucediendo en la vereda con las empresas industriales que laboran allí

    Exact solution of the one-dimensional ballistic aggregation

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    An exact expression for the mass distribution ρ(M,t)\rho(M,t) of the ballistic aggregation model in one dimension is derived in the long time regime. It is shown that it obeys scaling ρ(M,t)=t4/3F(M/t2/3)\rho(M,t)=t^{-4/3}F(M/t^{2/3}) with a scaling function F(z)z1/2F(z)\sim z^{-1/2} for z1z\ll 1 and F(z)exp(z3/12)F(z)\sim \exp(-z^3/12) for z1z\gg 1. Relevance of these results to Burgers turbulence is discussed.Comment: 11 pages, 2 Postscript figure

    On the strong anomalous diffusion

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    The superdiffusion behavior, i.e. t2ν \sim t^{2 \nu}, with ν>1/2\nu > 1/2, in general is not completely characherized by a unique exponent. We study some systems exhibiting strong anomalous diffusion, i.e. tqν(q) \sim t^{q \nu(q)} where ν(2)>1/2\nu(2)>1/2 and qν(q)q \nu(q) is not a linear function of qq. This feature is different from the weak superdiffusion regime, i.e. ν(q)=const>1/2\nu(q)=const > 1/2, as in random shear flows. The strong anomalous diffusion can be generated by nontrivial chaotic dynamics, e.g. Lagrangian motion in 2d2d time-dependent incompressible velocity fields, 2d2d symplectic maps and 1d1d intermittent maps. Typically the function qν(q)q \nu(q) is piecewise linear. This corresponds to two mechanisms: a weak anomalous diffusion for the typical events and a ballistic transport for the rare excursions. In order to have strong anomalous diffusion one needs a violation of the hypothesis of the central limit theorem, this happens only in a very narrow region of the control parameters space.Comment: 27 pages, 14 figure

    Two methods of obtaining sol gel Nb2O5 thin films for electrochromic devices

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    Nb2O5 coatings prepared by the sol-gel route using the dip coating technique with sols prepared from alkoxide or chloroalkoxide (two different methods: sonocatalytic and conventional) precursors are a promising alternative for WO3 electrochromic coatings. The crystalline films (TT phase) sintered at 560 and 600 degrees C are transparent and present a deep blue colour under Li+ ion insertion. Electrochemical stability is excellent as these systems are fully reversible and stable and no change in colour, amount of charge exchanged and corrosion effect could be observed after 2000 voltammetry cycles between 2 and - 1.8 V versus Ag. The electrochemical and optical properties of these coatings have been determined as a function of sintering temperature. The superficial structure was visualized by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and the Li+ diffusion coefficient was determined for both kinds of coatings

    Effects of Turbulent Mixing on the Critical Behavior

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    Effects of strongly anisotropic turbulent mixing on the critical behavior are studied by means of the renormalization group. Two models are considered: the equilibrium model A, which describes purely relaxational dynamics of a nonconserved scalar order parameter, and the Gribov model, which describes the nonequilibrium phase transition between the absorbing and fluctuating states in a reaction-diffusion system. The velocity is modelled by the d-dimensional generalization of the random shear flow introduced by Avellaneda and Majda within the context of passive scalar advection. Existence of new nonequilibrium types of critical regimes (universality classes) is established.Comment: Talk given in the International Bogolyubov Conference "Problems of Theoretical and Mathematical Physics" (Moscow-Dubna, 21-27 August 2009

    Enhacement in the dymanic response of a viscoelastic fluid flowing through a longitudinally vibrating tube

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    We analyzed effects of elasticity on the dynamics of fluids in porous media by studying a flow of a Maxwell fluid in a tube, which oscillates longitudinally and is subject to oscillatory pressure gradient. The present study investigates novelties brought about into the classic Biot's theory of propagation of elastic waves in a fluid-saturated porous solid by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. Using the time Fourier transform and transforming the problem into the frequency domain, we calculated: (A) the dynamic permeability and (B) the function F(κ)F(\kappa) that measures the deviation from Poiseuille flow friction as a function of frequency parameter κ\kappa. This provides a more complete theory of flow of Maxwell fluid through the longitudinally oscillating cylindrical tube with the oscillating pressure gradient, which has important practical applications. This study has clearly shown transition from dissipative to elastic regime in which sharp enhancements (resonances) of the flow are found

    Spectrum of the Fokker-Planck operator representing diffusion in a random velocity field

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    We study spectral properties of the Fokker-Planck operator that represents particles moving via a combination of diffusion and advection in a time-independent random velocity field, presenting in detail work outlined elsewhere [J. T. Chalker and Z. J. Wang, Phys. Rev. Lett. {\bf 79}, 1797 (1997)]. We calculate analytically the ensemble-averaged one-particle Green function and the eigenvalue density for this Fokker-Planck operator, using a diagrammatic expansion developed for resolvents of non-Hermitian random operators, together with a mean-field approximation (the self-consistent Born approximation) which is well-controlled in the weak-disorder regime for dimension d>2. The eigenvalue density in the complex plane is non-zero within a wedge that encloses the negative real axis. Particle motion is diffusive at long times, but for short times we find a novel time-dependence of the mean-square displacement, t2/d \sim t^{2/d} in dimension d>2, associated with the imaginary parts of eigenvalues.Comment: 8 pages, submitted to Phys Rev

    Resonant enhanced diffusion in time dependent flow

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    Explicit examples of scalar enhanced diffusion due to resonances between different transport mechanisms are presented. Their signature is provided by the sharp and narrow peaks observed in the effective diffusivity coefficients and, in the absence of molecular diffusion, by anomalous transport. For the time-dependent flow considered here, resonances arise between their oscillations in time and either molecular diffusion or a mean flow. The effective diffusivities are calculated using multiscale techniques.Comment: 18 latex pages, 11 figure

    La sostenibilidad en la arquitectura industrializada: cerrando el ciclo de los materiales

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    The condition of sustainability, from a physical point of view, can be defined as the closure of the material cycle. This is reached in determined systems, in the absence of residual flows, and in which resources are constantly recycled. Such systems can encounter serious obstacles in the productive model that characterises the majority of contemporary industry. The productive model, born during the Industrial Revolution, can be summarised by the following lineal sequence: extraction > manufacture > use > residue. In contrast, this research focuses on a productive model from the ecological industry, based on the example of the biosphere as a recycling machine. Requiring the elimination of the concept of residues, the system can be summarised by the following continuous cycle: recycling-manufacturing-use-recycling. The hypothesis posed is as follows: using technology presently available, represented by the lightweight modular construction that is commercialised by renting (making it possible to return the modules to the factory once their useful life is over, therefore recuperating resources), a management system capable to close the material cycle at least to 90% can be developed. (conventional building construction currently manages a recycling value of 10% of used resources).La condición de sostenibilidad, desde el punto de vista físico, puede ser definida como el cierre de los ciclos materiales, alcanzándose éste en un sistema determinado cuando no existen flujos de residuos sino que los recursos se reciclan constantemente. Tal condición encuentra un fuerte obstáculo en el modelo productivo que caracteriza a la mayor parte de la industria contemporánea, nacido en la revolución industrial, que puede sintetizarse en la secuencia lineal extracción > fabricación > uso > residuo. En oposición a ello, el modelo productivo en el que se centra la investigación que aquí se presenta es la ecología industrial y se basa en el ejemplo de la biosfera como máquina de reciclar. Supone la eliminación del concepto de residuo y puede resumirse en el ciclo continuo de reciclaje-fabricación-uso-reciclaje. La hipótesis planteada consiste en que, a partir de los sistemas de construcción modular ligera que se comercializan bajo el sistema de alquiler (que hace posible que los módulos regresen a la fábrica una vez cumplida su vida útil, recuperándose sus componentes) se puede desarrollar un sistema de gestión de los recursos empleados en el ciclo de vida de los edificios capaz de cerrar los ciclos materiales hasta en un 90% (en la construcción convencional se alcanza un 10%)

    Malvinas-slope water intrusions on the northern Patagonia continental shelf

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    The Patagonia continental shelf located off southeastern South America is bounded offshore by the Malvinas Current, which extends northward from northern Drake Passage (~55° S) to nearly 38° S. The transition between relatively warm-fresh shelf waters and Subantarctic Waters from the western boundary current is characterized by a thermohaline front extending nearly 2500 km. We use satellite derived sea surface temperature, and chlorophyll-<I>a</I> data combined with hydrographic and surface drifter data to document the intrusions of slope waters onto the continental shelf near 41° S. These intrusions create vertically coherent localized negative temperature and positive salinity anomalies extending onshore about 150 km from the shelf break. The region is associated with a center of action of the first mode of non-seasonal sea surface temperature variability and also relatively high chlorophyll-<I>a</I> variability, suggesting that the intrusions are important in promoting the local development of phytoplankton. The generation of slope water penetrations at this location may be triggered by the inshore excursion of the 100 m isobath, which appears to steer the Malvinas Current waters over the outer shelf
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