7,883 research outputs found

    Social Security and the search behaviour of workers approaching retirement

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    This paper explores the links between unemployment, retirement and their associated public insurance programs. It is a contribution to a growing body of literature focused on a better understanding of the labor behavior of advanced-age workers, which has gained importance as the pension crisis looms. It also contributes to the literature of optimal unemployment insurance by exploring the interaction of unemployment benefits and retirement pensions. The analysis combines the development of a new theoretical model and a detailed exploration of the empirical regularities using the Spanish Muestra Continua de Vidas Laborales (MCVL) dataset. The model is an extension of the standard search model, designed to reproduce the non-stationary environment faced by workers of advanced ages (in the age range 50/65). Via calibrated simulations we show that the basic empirical re-employment and retirement patterns can be considered as rational responses to both the labor market conditions and the institutional incentives. Generous Unemployment Benefits (for durations of up to two years) together with very significant early retirement penalties, make optimal to stay unemployed without searching for large groups of unemployed workers. This moral hazard problem can be substantially alleviated through institutional reform. We explore several potential reforms and find that changing the details of early retirement pensions seems more promising than changing the Unemployment Benefit system.Unemployment, Retirement, Search models

    DISEÑO DE UNA COLUMNA DE ABSORCIÓN EMPACADA CONSIDERANDO CUATRO TIPOS DE EMPAQUE Y APLICANDO MATLAB

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    In the present work, a packed bed absorption column is designed to recover certain amounts of ethanol contained in a gaseous stream. Four packing types (50-mm metal Hiflow® rings, 50-mm ceramic Pall® rings, 50-mm metal Top Pak® rings and 25-mm metal VSP® rings) are considered in order to select the most appropriate one in terms of column dimensions, pressure drop and mass-transfer results. Several design parameters were determined including column diameter (D), packing height (Z), overall mass-transfer coefficient (Km) and gas pressure drop (P/Z), as well as the overall number of gas-phase transfer units (NtOG), overall height of a gas-phase transfer unit (HtOG) and the effective surface area of packing (ah). The most adequate packing to use for this absorption system constitutes the 25-mm metal VSP® rings, since it provided the greatest values of Km (0.325 kmol/m3.s), and ah (169.57 m-1), as well as the lowest values of both Z (0.6 m) and HtOG (0.145 m), meaning that it will supply the higher mass-transfer conditions with the lowest column dimensions. The influence of both gas mixture (QG) and solvent (mL) feed flowrates on D, Z, Km, P/Z, NtOG and HtOG was also evaluated for the four packing considered. The design methodology was solved using computing software MATLAB® version 7.8.0.347 (R2009a) (Math Works, 2009), and also Microsoft Excel®.DEn el presente trabajo se diseña una columna de absorción empacada para recuperar ciertas cantidades de etanol contenido en una corriente gaseosa. Se consideran 4 tipos de empaques (anillos Hiflow® metálicos de 50 mm, anillos Pall® cerámicos de 50 mm, anillos Top Pak® metálicos de 50 mm, y anillos VSP® metálicos de 25 mm) con el fin de seleccionar el más apropiado en términos de dimensiones de la columna, caída de presión y resultados de transferencia de masa. Se determinaron varios parámetros de diseño incluyendo diámetro de la columna (D), altura del empaque (Z), coeficiente global de transferencia de masa (Km) y caída de presión gaseosa (P/Z), así como también el número total de unidades de transferencia den fase gaseosa (NtOG), altura total de unidades de transferencia en fase gaseosa (HtOG) y el área superficial efectiva del empaque (ah). El empaque más adecuado de usar en este sistema de absorción constituye los anillos VSP® metálicos de 25 mm, ya que suministra los mayores valores de Km (0.325 kmol/m3.s), y ah (169.57 m-1), así como también los menores valores de tanto Z (0.6 m) y HtOG (0.145 m), significando que suministrará las condiciones más altas de transferencia de masa con las menores dimensiones dela columna. La influencia de los caudales de alimentación de tanto la mezcla gaseosa (QG) y el solvente (mL) sobre D, Z, Km, DP/Z, NtOG y HtOG fue también evaluada para los cuatro tipos de empaques considerados. La metodología de diseño fue resuelta empleando el software MATLAB® versión 7.8.0.347 (R2009a) (Math Works, 2009), y también Microsoft Excel®

    DISEÑO DE UNA COLUMNA DE ABSORCIÓN EMPACADA CONSIDERANDO CUATRO TIPOS DE EMPAQUE Y APLICANDO MATLAB

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    In the present work, a packed bed absorption column is designed to recover certain amounts of ethanol contained in a gaseous stream. Four packing types (50-mm metal Hiflow® rings, 50-mm ceramic Pall® rings, 50-mm metal Top Pak® rings and 25-mm metal VSP® rings) are considered in order to select the most appropriate one in terms of column dimensions, pressure drop and mass-transfer results. Several design parameters were determined including column diameter (D), packing height (Z), overall mass-transfer coefficient (Km) and gas pressure drop (P/Z), as well as the overall number of gas-phase transfer units (NtOG), overall height of a gas-phase transfer unit (HtOG) and the effective surface area of packing (ah). The most adequate packing to use for this absorption system constitutes the 25-mm metal VSP® rings, since it provided the greatest values of Km (0.325 kmol/m3.s), and ah (169.57 m-1), as well as the lowest values of both Z (0.6 m) and HtOG (0.145 m), meaning that it will supply the higher mass-transfer conditions with the lowest column dimensions. The influence of both gas mixture (QG) and solvent (mL) feed flowrates on D, Z, Km, P/Z, NtOG and HtOG was also evaluated for the four packing considered. The design methodology was solved using computing software MATLAB® version 7.8.0.347 (R2009a) (Math Works, 2009), and also Microsoft Excel®.DEn el presente trabajo se diseña una columna de absorción empacada para recuperar ciertas cantidades de etanol contenido en una corriente gaseosa. Se consideran 4 tipos de empaques (anillos Hiflow® metálicos de 50 mm, anillos Pall® cerámicos de 50 mm, anillos Top Pak® metálicos de 50 mm, y anillos VSP® metálicos de 25 mm) con el fin de seleccionar el más apropiado en términos de dimensiones de la columna, caída de presión y resultados de transferencia de masa. Se determinaron varios parámetros de diseño incluyendo diámetro de la columna (D), altura del empaque (Z), coeficiente global de transferencia de masa (Km) y caída de presión gaseosa (P/Z), así como también el número total de unidades de transferencia den fase gaseosa (NtOG), altura total de unidades de transferencia en fase gaseosa (HtOG) y el área superficial efectiva del empaque (ah). El empaque más adecuado de usar en este sistema de absorción constituye los anillos VSP® metálicos de 25 mm, ya que suministra los mayores valores de Km (0.325 kmol/m3.s), y ah (169.57 m-1), así como también los menores valores de tanto Z (0.6 m) y HtOG (0.145 m), significando que suministrará las condiciones más altas de transferencia de masa con las menores dimensiones dela columna. La influencia de los caudales de alimentación de tanto la mezcla gaseosa (QG) y el solvente (mL) sobre D, Z, Km, DP/Z, NtOG y HtOG fue también evaluada para los cuatro tipos de empaques considerados. La metodología de diseño fue resuelta empleando el software MATLAB® versión 7.8.0.347 (R2009a) (Math Works, 2009), y también Microsoft Excel®

    Improving a Satellite Mission System by means of a Semantic Grid Architecture

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    The use of a semantic grid architecture can make easier the deployment of complex applications, in which several organizations are involved and diverse resources are shared. This paper presents the application of the architecture defined in the Ontogrid project (S-OGSA) into a scenario for the analysis of the quality of the products of satellite missions

    Sustainable Development Goals integrated in Project-based Learning in the Mechanical Engineering Degree

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    [EN] The Sustainable Development Goals (SDGs) are an action plan to reach a better and more sustainable future for everybody. This is the main reason why universities have to make a special effort to instil in students the importance of the SDGs as well as promote actions addressed to the end poverty, the protection of the planet and the improvement of lives and prospects of everyone in any place. In light of this, one of the methodologies that currently is very used by universities is Project- Based Learning (PBL). This methodology promotes active teaching in which students are the main actors. With this methodology students solve challenging situations, raise questions, and try to answer them using their knowledge, means, resources, research, reflection in an active and collaborative way. It is not a new methodology, but it is unquestionable that in the last years it has been implemented in a generalized way in comparison with other educational trends. The objective of this paper is to define a learning approach based on PBL to achieve and enhance students' knowledge about SDGs. In addition, the paper also shows an illustrative example of a PBL model applied to some of the 17 SGDs that can be the basis for other teachers to apply the PBL methodology to develop students¿ capacity to achieve SGDs in other subjects and/or degrees.This article has been supported by Universitat Politècnica de València, particularly by the Vicerectorate for Digital Resources and Documentation (Vicerrectorado de Recursos Digitales y Documentación) and Vice-Rectorate for Studies, Quality and Accreditation (Vicerrectorado de Estudios, Calidad y Acreditación) under the Call for Learning + Teaching (Convocatoria A+D2019: Aprendizaje + Docencia. Proyectos de Innovación y Mejora Educativa) and Project Code: A157. The authors would like to acknowledge the support of the Institute of Educational Sciences (Instituto de Ciencias de la Educación), the Evaluation and Monitoring Commission for Educational Innovation and Improvement Projects (Comisión de Evaluación y Seguimiento de Proyectos de Innovación y Mejora Educativa (CESPIME) and Escuela Politécnica Superior de Alcoy.Pérez-Sánchez, M.; Sanchis, R. (2021). Sustainable Development Goals integrated in Project-based Learning in the Mechanical Engineering Degree. INTED proceedings (Online). 7480-7487. https://doi.org/10.21125/inted.2021.1502S7480748

    Deep into the Water Fountains: The case of IRAS 18043-2116

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    (Abridged) The formation of large-scale (hundreds to few thousands of AU) bipolar structures in the circumstellar envelopes (CSEs) of post-Asymptotic Giant Branch (post-AGB) stars is poorly understood. The shape of these structures, traced by emission from fast molecular outflows, suggests that the dynamics at the innermost regions of these CSEs does not depend only on the energy of the radiation field of the central star. Deep into the Water Fountains is an observational project based on the results of programs carried out with three telescope facilities: The Karl G. Jansky Very Large Array (JVLA), The Australia Telescope Compact Array (ATCA), and the Very Large Telescope (SINFONI-VLT). Here we report the results of the observations towards the WF nebula IRAS 18043-2116: Detection of radio continuum emission in the frequency range 1.5GHz - 8.0GHz; H2_{2}O maser spectral features and radio continuum emission detected at 22GHz, and H2_{2} ro-vibrational emission lines detected at the near infrared. The high-velocity H2_{2}O maser spectral features, and the shock-excited H2_{2} emission detected could be produced in molecular layers which are swept up as a consequence of the propagation of a jet-driven wind. Using the derived H2_{2} column density, we estimated a molecular mass-loss rate of the order of 10910^{-9}M_{\odot}yr1^{-1}. On the other hand, if the radio continuum flux detected is generated as a consequence of the propagation of a thermal radio jet, the mass-loss rate associated to the outflowing ionized material is of the order of 105^{-5}M_{\odot}yr1^{-1}. The presence of a rotating disk could be a plausible explanation for the mass-loss rates estimated.Comment: 10 pages, 5 figures. Accepted for publication in A&

    Retirement incentives, individual heterogeneity and labour transitions of employed and unemployed workers

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    In this paper we analyze the sensitivity of the labour market decisions of workers close to retirement with respect to the incentives created by public regulations. We improve upon the extensive prior literature on the effect of pension incentives on retirement in two ways. First, by modeling the transitions between employment, unemployment and retirement in a simultaneous manner, paying special attention to the transition from unemployment to retirement (which is particularly important in Spain). Second, by considering the influence of unobserved heterogeneity in the estimation of the effect of our (carefully constructed) incentive variables. Using administrative data, we find that, when properly defined, economic incentives have a strong impact on labour market decisions in Spain. Unemployment regulations are shown to be particularly influential for retirement behaviour, along with the more traditional determinants linked to the pension system. Pension variables also have a major bearing on both workers’ reemployment decisions and on the strategic actions of employers. The quantitative impact of the incentives, however, is greatly affected by the existence of unobserved heterogeneity among workers. Its omission leads to sizable biases in the assessment of the sensitivity to economic incentives, a finding that has clear consequences for the credibility of any model-based policy analysis. We confirm the importance of this potential problem in one especially interesting instance: the reform of early retirement provisions undertaken in Spain in 2002. We use a difference-in-difference approach to measure the behavioural reaction to this change, finding a large overestimation when unobserved heterogeneity is not taken into account.Retirement, unemployment, incentives, Pension system, Unobserved, heterogeneity, Spain.

    Flux-cutting and flux-transport effects in type-II superconductor slabs in a parallel rotating magnetic field

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    The magnetic response of irreversible type-II superconductor slabs subjected to in-plane rotating magnetic field is investigated by applying the circular, elliptic, extended-elliptic, and rectangular flux-line-cutting critical-state models. Specifically, the models have been applied to explain experiments on a PbBi rotating disk in a fixed magnetic field Ha{\bm H}_a, parallel to the flat surfaces. Here, we have exploited the equivalency of the experimental situation with that of a fixed disk under the action of a parallel magnetic field, rotating in the opposite sense. The effect of both the magnitude HaH_a of the applied magnetic field and its angle of rotation αs\alpha_s upon the magnetization of the superconductor sample is analyzed. When HaH_a is smaller than the penetration field HPH_P, the magnetization components, parallel and perpendicular to Ha{\bm H_a}, oscillate with increasing the rotation angle. On the other hand, if the magnitude of the applied field, HaH_a, is larger than HPH_P, both magnetization components become constant functions of αs\alpha_s at large rotation angles. The evolution of the magnetic induction profiles inside the superconductor is also studied.Comment: 12 pages, 29 figure

    Broadband telecom transparency of semiconductor-coated metal nanowires: more transparent than glass

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    Metallic nanowires (NW) coated with a high permittivity dielectric are proposed as means to strongly reduce the light scattering of the conducting NW, rendering them transparent at infrared wavelengths of interest in telecommunications. Based on a simple, universal law derived from electrostatics arguments, we find appropriate parameters to reduce the scattering efficiency of hybrid metal-dielectric NW by up to three orders of magnitude as compared with the scattering efficiency of the homogeneous metallic NW. We show that metal@dielectric structures are much more robust against fabrication imperfections than analogous dielectric@metal ones. The bandwidth of the transparent region entirely covers the near IR telecommunications range. Although this effect is optimum at normal incidence and for a given polarization, rigorous theoretical and numerical calculations reveal that transparency is robust against changes in polarization and angle of incidence, and also holds for relatively dense periodic or random arrangements. A wealth of applications based on metal-NWs may benefit from such invisibility
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