The effects of immigration on the productive structure of Spanish regions

Immigrants have increased their participation in Spanish labour supply from less than 3 percent in 1996 to more than 13 percent in 2005. Using the factor proportion model of production, this paper analyses whether this labour supply shock has affected the industrial structure of Spanish regions. Our best specification suggests the need to include time varying region-specific effects to capture differences in technology and prices across regions. Our results confirm that, first, labour endowment differences across regions help to explain the pattern of industry specialisation across region. Second, immigrants and natives act as complementary factors in most industries. Third, the importance of factor endowment changes is relatively small compared to production technique changes and idiosyncratic industry changes in explaining the overall changes in industrial structure over 1996-2005, being only important in the case of Building, a sector where foreign workers represent an important share of its total labour force.

Attitude control techniques for a 1U CubeSat

This thesis is focused on the study, design and simulation of an Attitude Control System for a 1U CubeSat. The simulations and their proper validation are carried out with MATLAB/Simulink. It is undertaken within the PLATHON project, which is led by Dr. Javier Gago of the Electronic Department in UPC ESEIAAT. The final design is aimed to correctly perform two manoeuvres: first, detumbling the spacecraft in order to stabilise it when deployed and rotating at high angular speeds, and secondly pointing in the Nadir direction to carry out communications with ground stations. The orientation and Reaction Wheels controllers, which make the Nadir pointing possible, are developed using the classical PID control algorithm, whereas the B-dot algorithm will be implemented for the Magnetorquers controllers, responsible of the Detumbling manoeuvre. Three PMSM motors in an orthogonal configuration are used as drivers of the Reaction Wheels, which provide with accurate torques to rotate the spacecraft. Magnetorquers act as the auxiliary actuators, preventing the Reaction Wheels from saturating. The Simulink model used to carry out this project is based on the template the Aerospace Blockset library arranges, which integrates the main three functionalities blocks: Environment, CubeSat Vehicle and 3D Animation. The simulations executed to test the correct operation of the system are based on Equatorial and ISS orbits, and validate the performance of the control system in terms of stabilisation, alignment errors, settling times and power consumption of the actuators. The results are satisfactory, with decent stabilisation times in front of elevated angular rates, precise pointing orientation with negligible stationary errors and an overall moderate energy consumption throughout the manoeuvre

Effect of key design parameters on bacteria community and effluent pollutant concentrations in constructed wetlands using mathematical models

Constructed wetlands are currently recognized as an effective environmental biotechnology for wastewater treatment, but the influence of their design parameters on internal functioning and contaminant removal efficiency is still under discussion. In this work, the effect of aspect ratio and water depth on bacteria communities as well as treatment efficiency of horizontal subsurface flow constructed wetlands (HSSF) under the Mediterranean climate was evaluated, using a mathematical model. For this purpose, experimental results from four pilot-scale wetlands of equal surface area but different aspect ratios and water depth were used. The HSSF system was fed with municipal wastewater. The experimental data were simulated using the BIO_PORE model, developed in the COMSOL Multiphysics™ platform. Simulations with the BIO_PORE model fitted well to the experimental results, showing a higher removal efficiency for the shallower HSSF for COD (93.7% removal efficiency) and ammonia nitrogen (73.8%). The aspect ratio had a weak relationship with the bacteria distribution and the removal efficiency. In contrast, the water depth was a factor. The results of the present study confirm a previous hypothesis in which depth has an important impact on the biochemical reactions causing contaminants transformation and degradation.Peer ReviewedPostprint (author's final draft

Microalgae and bacteria dynamics in high rate algal ponds based on modelling results: long-term application of BIO_ALGAE model

The mechanistic model (BIO_ALGAE) for microalgae-bacteria based wastewater treatment systems simulation was validated in the long-term (months) using experimental results from a pilot high rate algal pond (HRAP) treating municipal wastewater. Simulated results were compared with data gathered during two different seasons (summer and winter), and with the HRAP operating at different hydraulic retention times (HRT, 4 and 8 days, respectively). The model was able to simulate with a good degree of accuracy the dynamics of different components in the pond, including the total biomass (bacteria and microalgae). By means of practical study cases, the influences of different HRT operating strategies and seasonal variations of temperature and irradiance were investigated for the relative proportion of microalgae and bacteria, and biomass production over a year cycle. Model predictions show that the proportion of microalgae in the microalgal/bacterial biomass is quite similar in warmer months if the pond is operated with 8-day HRT (76–78%) or 4-day HRT (60–75%). Significant differences were observed in colder months (4-day HRT (27–33%) and 8-day HRT (65–68%)). The model identified a scenario in which overall microalgae production and ammonium removal efficiency were optimized. By operating the HRAP with lower HRT (4 days) in warmer months and higher HRT (8 days) in colder months, the average annual microalgae production increased up to 14.1 gTSS m-2d-1, in contrast with 10.2 gTSS m-2d-1 and 9.2 gTSS m-2d-1 operating with constant HRAP (4 and 8 days, respectively) over a year cycle.Peer ReviewedPostprint (author's final draft

Conflicting national policies: The creation of the euro and the rebalancing of telecommunications prices

Government departments have diverse interests, and on certain occasions, the need to achieve a priority objective in one department may lead to the adoption of inefficient policies in other areas, with long-lasting consequences. In this paper, we analyze the rebalancing of the telecommunications tariffs that took place in the European Union before and after the liberalization of the market in 1998. We show that the objective of satisfying the Maastricht inflation condition to allow participation in the European Monetary Union from 1999 led some national governments to block the rebalancing of telecommunications tariffs. Specifically, we demonstrate that in the years immediately before the liberalization of the telecommunications market, those countries that faced greater difficulty achieving the inflation objectives of the Maastricht Treaty reduced, rather than increased, the prices of local telephone calls and line rental. Furthermore, these countries did not intensify efforts to rebalance their tariffs after the creation of the euro. Our paper also shows that in this period the countries that diverged most from the inflation condition invested less in their telecommunications infrastructure

Numerical dynamic analysis of reciprocating compressor mechanism. Parametric studies for optimization purposes

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A complete numerical dynamic analysis of reciprocating compressor mechanism is presented, coupling the instantaneous pressure in the compression chamber, the electric motor torque and the hydrodynamic reactions, which arise from the piston and crankshaft secondary movements. Additionally, non-constant crankshaft angular velocity and the piston and crankshaft misalignment torques have also been considered. Two sensitivity analyses have been carried out to prove that neither the inertial forces in the directions of the secondary movements, nor the oscillations of the angular velocity produce significant differences in the compressor behaviour. Finally, a set of parametric studies has been developed to evaluate the influence of geometrical parameters in the stability of the secondary movements, the friction power losses and the compressor consumptionPeer ReviewedPostprint (author's final draft

Modelització dels processos físics, químics i biològics en aiguamolls construïts per al tractament d'aigües

Els aiguamolls construïts s'utilitzen per al tractament d'aigües residuals de poblacions de fins a 2000 p.e des de la dècada dels 70. Aquests sistemes compten amb una sèrie d'avantatges respecte a les plantes de tractament convencionals, com són la baixa inversió inicial, el reduït consum energètic i la baixa producció de fangs, entre d'altres. La millora de la qualitat de l'aigua als aiguamolls es du a terme per mitjà de diversos processos tan físics com químics i biològics, que es desenvolupen simultàniament. Els models numèrics comencen a ser considerats una eina ESSENCIAL per tal de millorar el coneixement existent sobre aquest tipus de sistemes i optimitzar-ne el disseny. En aquest article es presenta un model d'aiguamoll desenvolupat sobre la plataforma Comsol Multiphisics i que incorpora les equacions del model biocinètic CWM1 per descriure els processos implicats en la millora de la qualitat de l'aigua.Peer Reviewe

Writing Environmental Sciences at University

User guide to written communication in academic disciplines (in this case environmental sciences) for teachers and students

Dissolution experiments of commercial PWR (52 MWd/kgU) and BWR (53 MWd/kgU) spent nuclear fuel cladded segments in bicarbonate water under oxidizing conditions. Experimental determination of matrix and instant release fraction

The denominated instant release fraction (IRF) is considered in performance assessment (PA) exercises to govern the dose that could arise from the repository. A conservative definition of IRF comprises the total inventory of radionuclides located in the gap, fractures, and the grain boundaries and, if present, in the high burn-up structure (HBS). The values calculated from this theoretical approach correspond to an upper limit that likely does not correspond to what it will be expected to be instantaneously released in the real system. Trying to ascertain this IRF from an experimental point of view, static leaching experiments have been carried out with two commercial UO2 spent nuclear fuels (SNF): one from a pressurized water reactor (PWR), labelled PWR, with an average burn-up (BU) of 52 MWd/kgU and fission gas release (FGR) of 23.1%, and one from a boiling water reactor (BWR), labelled BWR, with an average BU of and 53 MWd/kgU and FGR of 3.9%.; One sample of each SNF, consisting of fuel and cladding, has been leached in bicarbonate water during one year under oxidizing conditions at room temperature (25 +/- 5) degrees C. The behaviour of the concentration measured in solution can be divided in two according to the release rate. All radionuclides presented an initial release rate that after some days levels down to a slower second one, which remains constant until the end of the experiment. Cumulative fraction of inventory in aqueous phase (FIAPc) values has been calculated. Results show faster release in the case of the PWR SNF. In both cases Np, Pu, Am, Cm, Y, Tc, La and Nd dissolve congruently with U, while dissolution of Zr, Ru and Rh is slower. Rb, Sr, Cs and Mo, dissolve faster than U. The IRF of Cs at 10 and 200 days has been calculated, being (3.10 +/- 0.62) and (3.66 +/- 0.73) for PWR fuel, and (035 +/- 0.07) and (0.51 +/- 0.10) for BWR fuel. (C) 2015 Elsevier B.V. All rights reserved.Peer ReviewedPostprint (author's final draft

Los Polímeros en la Educación Secundaria Obligatoria y Bachillerato en España: Análisis de Libros de Texto y Opinión del Profesorado

Even though the study of polymers is included in the school secondary curriculum in Spain, all the signs are that this topic is not being adequately addressed in the classroom. For this reason, this paper focuses on two key factors for polymers teaching and learning at secondary level: teachers and textbooks. A qualitative methodology, based on semi-structured interviews and a content analysis of textbooks, has been used. Six High School teachers have participated in this research. Attempts have been made to find out teachers' opinion about introducing contents of polymers in the classroom by means of semi-structured interviews. The content analysis of textbooks used in many schools of Spain has been carried out through the application of a assessment questionnaire. The results obtained as regards the polymers suggest that: a) Teachers provide only a limited amount of time for this topic in the curriculum; b) Textbooks do not include a large part of basic contents; and c) The low level of knowledge of students is justified by a) and b)