5,311 research outputs found

    Nonlinear Exchange Rate Predictability

    Get PDF
    We study whether the nonlinear behavior of the real exchange rate can help us account for the lack of predictability of the nominal exchange rate. We construct a smooth nonlinear error-correction model that allows us to test the hypotheses of nonlinear predictability of the nominal exchange rate and nonlinear behavior on the real exchange rate in the context of a fully specified cointegrated system. Using a panel of 19 countries and three numeraires, we find evidence of nonlinear predictability of the nominal exchange rate and of nonlinear mean reversion of the real exchange rate. Out-of-sample Theil's U-statistics show a higher forecast precision of the nonlinear model than the one obtained with a random walk specification. Although the robustness of the out-of-sample results over different forecast windows is somewhat limited, we are able to obtain significant predictability gains--from a parsimonious structural model with PPP fundamentals--even at short-run horizons.Exchange rates; Predictability; Nonlinearities; Purchasing power parity

    Methodology for the metric restoration of the historical cartography applied to Francisco Coello's cartografic series of the Royal Site of Aranjuez

    Get PDF
    Hojas Kilométricas (Kilometric Sheets). Specifically, the study focuses on those sheets referring to the city centre and surrounding area of the Royal Site of Aranjuez, a town in the south of the Province of Madrid. The aim of this study is to restore the actual size and measurements of scanned images of the Hojas Kilométricas. This would allow us, among other things, to reestablish both the format and scale of the original plans. To achieve this goal it is necessary to rectify and then georeference these images, i.e. assign them a geographic reference system. This procedure is essential in the overlaying and comparison of the Hojas Kilométricas of the Royal Site with other historical cartography as well as other sources related to the same area from different time periods. Subsequent research would allow us, for example, to reconstruct the time-evolution of the urban area, to spot new construction and to pinpoint the locations of any altered or missing buildings or architectural features. In addition, this would allow us to develop and integrate databases for GIS models applicable to the management of our cultural heritage

    Persistence of instanton connections in chemical reactions with time dependent rates

    Get PDF
    The evolution of a system of chemical reactions can be studied, in the eikonal approximation, by means of a Hamiltonian dynamical system. The fixed points of this dynamical system represent the different states in which the chemical system can be found, and the connections among them represent instantons or optimal paths linking these states. We study the relation between the phase portrait of the Hamiltonian system representing a set of chemical reactions with constant rates and the corresponding system when these rates vary in time. We show that the topology of the phase space is robust for small time-dependent perturbations in concrete examples and state general results when possible. This robustness allows us to apply some of the conclusions on the qualitative behavior of the autonomous system to the time-dependent situation

    Estimating Gaussian mixtures using sparse polynomial moment systems

    Full text link
    The method of moments is a statistical technique for density estimation that solves a system of moment equations to estimate the parameters of an unknown distribution. A fundamental question critical to understanding identifiability asks how many moment equations are needed to get finitely many solutions and how many solutions there are. We answer this question for classes of Gaussian mixture models using the tools of polyhedral geometry. Using these results, we present an algorithm that performs parameter recovery, and therefore density estimation, for high dimensional Gaussian mixture models that scales linearly in the dimension.Comment: 30 page

    Anaerobic co-digestion of municipal sewage sludge and fruit/vegetable waste: effect of different mixtures on digester stability and methane yield

    Get PDF
    There are different options for the management of fruit and vegetable wastes (FVWs), but the most environmental-friendly is the anaerobic digestion, because it allows an optimum recovery of materials and energy from the two by-products: biogas and digestate. Nevertheless, in many cases there are economic and technical problems that cause the selection of other alternatives. Frequently these wastes are produced in large quantities but only during few weeks of the year. In these cases, this is the most important economic problem, because large digesters that would be used only for short time periods every year would be required. In addition, a close control of the pH of the digester is required for this kind of residues, for which the hydrolysis is usually faster than the methanogenesis, so large concentrations of fatty acids should be prevented to maintain the adequate pH value for anaerobic digestion that should be neutral or slightly alkaline. Both problems can be simultaneously overcome by the co-digestion with other residues that are produced throughout the year. Among the benefits of co-digestion, one of the most important is the improvement in the feedstock characteristics, since it may allow a more equilibrate composition resulting in a better performance of the digester in treatment capacity, and a better quality of biogas and digestate. The co-digestion with other substrates with a complementary composition that are produced throughout the year and that are already managed by anaerobic digestion is probably the optimum management option. For these cases, if the existing anaerobic digester is oversized and allows the introduction of additional volumes of wastes, the mean retention time of the digestate should be maintained. Therefore, the anaerobic co-digestion of fruit and vegetable waste (FVW) and municipal sewage sludge (MSS) under mesophilic condition and a constant hydraulic retention time (20 d) is studied. The effects on digester performance of the FVW:MSS ratio and the organic loading rate (OLR) were examined. The OLR is the mass of volatile solids fed per volume of digestate and day.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Effect of the axial jet on the optimal response in Batchelor vortex

    Get PDF
    En este póster se estudia la respuesta óptima del torbellino de Batchelor para distintos números de onda. Se demuestra que incluso teniendo la velocidad axial, un torbellino es capaz de tener grandes amplificaciones de energía.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Wingtip vortex in a NACA0012 airfoil and its active control

    Get PDF
    Contribución mediante sesión pósterWe conduct experiments in a towing-tank to analyse the flow patterns of wingtip vortices in a NACA 0012 airfoil. In this experimental research, we provide PIV measurements and flow visualisations. Without active control, several parameters are given experimentally as function of the Reynolds number, so we compare these data with the theoretical models of Batchelor, and Moore and Saffman together with DNS. Secondly, we analyse the effect of a continuous injection in the spanwise direction. The continuous jet has a strong influence on the wing-tip vortex formation. We explore this effect at low chord based Reynolds number ranging from 7000 up to 20000. We change the aspect ratio of the injection, R, defined as the ratio of the velocities between the jet (Uj) and free-stream (U). For R=1, we find that the jet strongly affects the wingtip vortex formation with a sudden decrement of the axial vorticity and the azimuthal velocity. This technique is a challenge and a promising tool to reduce the intensity of the vortex core.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    La aplicación del principio de oportunidad, en las investigaciones por la comisión del delito de minería ilegal en las fiscalías especializadas de medio ambiente de La Libertad

    Get PDF
    La presente investigación, nace de la inquietud del tesista respecto a la protección del medio ambiente en el sistema penal peruano, precisamente en la actividad minera, actividad que es uno de los mayores factores de crecimiento económico del estado peruano, sin embargo también es una actividad que si no se realiza dentro del control y fiscalización del estado adecuadamente se deteriorara irreparablemente el ecosistema de manera indefinida, ya que incluso con el control del estado las agresiones al ecosistema son irreparables, por ello al analizar el dispositivo penal vigente en el código procesal penal peruano, observamos la regulación del principio de oportunidad en los delitos de minería ilegal, dentro del numeral 8 del artículo del código procesal penal. Por ello mediante el uso del método científico y los instrumentos respecto artículos científicos previos, análisis de disposiciones fiscales y legislación nacional como comparada, se buscó analizar su aplicación dentro del distrito fiscal, concluyendo que la practica fiscal incide negativamente en la correcta administración de justicia por que se viene aplicando de manera discrecional afectando reglas procedimentales, la protección del medio ambiente y el desarrollo sostenible

    Análisis de la teoría de la dignidad humana en el trabajo de parto, en el hospital Santa Gema. Yurimaguas 2021

    Get PDF
    El presente trabajo tiene como objetivo analizar la teoría de la dignidad humana en el trabajo de parto en el Hospital Santa Gema, Yurimaguas, 2021; desde un enfoque cualitativo, teniendo como eje director el diseño de teoría fundamentada, consiguiendo como resultado que la violencia obstétrica menoscaba la dignidad de las mujeres embarazadas, por la humillación, por medio de palabras destinadas a denigrar a las personas, el maltrato físico y la falta de información hacia los pacientes sobre el procedimiento a seguir. Por ende, desde la teoría de la dignidad, el ser humano esta denigrado por la mala praxis médica que repercute en la denigración de la mujer, hecho que afecta además con posterioridad su libre desarrollo de la personalidad, al incidir de forma negativa en esta etapa de la vida. Finalmente, se concluyó que la violencia obstétrica, vulnera derechos fundamentales, como la integridad, la libertad, el libre desarrollo de la personalidad, mediante la humillación, la falta de información, el mal trato, lo que a su vez configura un menoscabo a la dignidad humana, teniendo en cuenta que los derechos son una red interconectada que busca el respeto de este atribut
    corecore