A unified framework of trade in value added : physical, monetary, exchange rates, and GHG emissions

Koopman et al. (2014) developed a method to consistently decompose gross exports in value-added terms that accommodate infinite repercussions of international and inter-sector transactions. This provides a better understanding of trade in value added in global value chains than does the conventional gross exports method, which is affected by double-counting problems. However, the new framework is based on monetary input--output (IO) tables and cannot distinguish prices from quantities; thus, it is unable to consider financial adjustments through the exchange market. In this paper, we propose a framework based on a physical IO system, characterized by its linear programming equivalent that can clarify the various complexities relevant to the existing indicators and is proved to be consistent with Koopman's results when the physical decompositions are evaluated in monetary terms. While international monetary tables are typically described in current U.S. dollars, the physical framework can elucidate the impact of price adjustments through the exchange market. An iterative procedure to calculate the exchange rates is proposed, and we also show that the physical framework is also convenient for considering indicators associated with greenhouse gas (GHG) emissions.

Spatial spillover effects in determining China's regional CO2 emission growth : 2007-2010

This paper proposes an alternative input-output based spatial-structural decomposition analysis to elucidate the role of domestic-regional heterogeneity and interregional spillover effects in determining China's regional CO2 emission growth. Our empirical results based on the 2007 and 2010 Chinese interregional input-output tables show that the changes in most regions' final demand scale, final expenditure structure and export scale give positive spatial spillover effects on other regions' CO2 emission growth, the changes in most regions' consumption and export preference help the reduction of other regions' CO2 emissions, the changes in production technology, and investment preference may give positive or negative impacts on other region's CO2 emission growth through domestic supply chains. For some regions, the aggregate spillover effect from other regions may be larger than the intra-regional effect in determining regional emission growth. All these facts can significantly help better and deeper understanding on the driving forces of China's regional CO2 emission growth, thus can enrich the policy implication concerning a narrow definition of "carbon leakage" through domestic-interregional trade, and relevant political consensus about the responsibility sharing between developed and developing regions inside China.

Some geometrical methods for constructing contradiction measures on Atanassov's intuitionistic fuzzy sets

Trillas et al. (1999, Soft computing, 3 (4), 197–199) and Trillas and Cubillo (1999, On non-contradictory input/output couples in Zadeh's CRI proceeding, 28–32) introduced the study of contradiction in the framework of fuzzy logic because of the significance of avoiding contradictory outputs in inference processes. Later, the study of contradiction in the framework of Atanassov's intuitionistic fuzzy sets (A-IFSs) was initiated by Cubillo and Castiñeira (2004, Contradiction in intuitionistic fuzzy sets proceeding, 2180–2186). The axiomatic definition of contradiction measure was stated in Castiñeira and Cubillo (2009, International journal of intelligent systems, 24, 863–888). Likewise, the concept of continuity of these measures was formalized through several axioms. To be precise, they defined continuity when the sets ‘are increasing’, denominated continuity from below, and continuity when the sets ‘are decreasing’, or continuity from above. The aim of this paper is to provide some geometrical construction methods for obtaining contradiction measures in the framework of A-IFSs and to study what continuity properties these measures satisfy. Furthermore, we show the geometrical interpretations motivating the measures.

X-parameters based analytical design of non-linear microwave circuits Application to oscillator design

Resumen El diseño clásico de circuitos de microondas se basa fundamentalmente en el uso de los parámetros s, debido a su capacidad para caracterizar de forma exitosa el comportamiento de cualquier circuito lineal. La relación existente entre los parámetros s con los sistemas de medida actuales y con las herramientas de simulación lineal han facilitado su éxito y su uso extensivo tanto en el diseño como en la caracterización de circuitos y subsistemas de microondas. Sin embargo, a pesar de la gran aceptación de los parámetros s en la comunidad de microondas, el principal inconveniente de esta formulación reside en su limitación para predecir el comportamiento de sistemas no lineales reales. En la actualidad, uno de los principales retos de los diseñadores de microondas es el desarrollo de un contexto análogo que permita integrar tanto el modelado no lineal, como los sistemas de medidas de gran señal y los entornos de simulación no lineal, con el objetivo de extender las capacidades de los parámetros s a regímenes de operación en gran señal y por tanto, obtener una infraestructura que permita tanto la caracterización como el diseño de circuitos no lineales de forma fiable y eficiente. De acuerdo a esta filosofía, en los últimos años se han desarrollado diferentes propuestas como los parámetros X, de Agilent Technologies, o el modelo de Cardiff que tratan de proporcionar esta plataforma común en el ámbito de gran señal. Dentro de este contexto, uno de los objetivos de la presente Tesis es el análisis de la viabilidad del uso de los parámetros X en el diseño y simulación de osciladores para transceptores de microondas. Otro aspecto relevante en el análisis y diseño de circuitos lineales de microondas es la disposición de métodos analíticos sencillos, basados en los parámetros s del transistor, que permitan la obtención directa y rápida de las impedancias de carga y fuente necesarias para cumplir las especificaciones de diseño requeridas en cuanto a ganancia, potencia de salida, eficiencia o adaptación de entrada y salida, así como la determinación analítica de parámetros de diseño clave como el factor de estabilidad o los contornos de ganancia de potencia. Por lo tanto, el desarrollo de una formulación de diseño analítico, basada en los parámetros X y similar a la existente en pequeña señal, permitiría su uso en aplicaciones no lineales y supone un nuevo reto que se va a afrontar en este trabajo. Por tanto, el principal objetivo de la presente Tesis consistiría en la elaboración de una metodología analítica basada en el uso de los parámetros X para el diseño de circuitos no lineales que jugaría un papel similar al que juegan los parámetros s en el diseño de circuitos lineales de microondas. Dichos métodos de diseño analíticos permitirían una mejora significativa en los actuales procedimientos de diseño disponibles en gran señal, así como una reducción considerable en el tiempo de diseño, lo que permitiría la obtención de técnicas mucho más eficientes. Abstract In linear world, classical microwave circuit design relies on the s-parameters due to its capability to successfully characterize the behavior of any linear circuit. Thus the direct use of s-parameters in measurement systems and in linear simulation analysis tools, has facilitated its extensive use and success in the design and characterization of microwave circuits and subsystems. Nevertheless, despite the great success of s-parameters in the microwave community, the main drawback of this formulation is its limitation in the behavior prediction of real non-linear systems. Nowadays, the challenge of microwave designers is the development of an analogue framework that allows to integrate non-linear modeling, large-signal measurement hardware and non-linear simulation environment in order to extend s-parameters capabilities to non-linear regimen and thus, provide the infrastructure for non-linear design and test in a reliable and efficient way. Recently, different attempts with the aim to provide this common platform have been introduced, as the Cardiff approach and the Agilent X-parameters. Hence, this Thesis aims to demonstrate the X-parameter capability to provide this non-linear design and test framework in CAD-based oscillator context. Furthermore, the classical analysis and design of linear microwave transistorbased circuits is based on the development of simple analytical approaches, involving the transistor s-parameters, that are able to quickly provide an analytical solution for the input/output transistor loading conditions as well as analytically determine fundamental parameters as the stability factor, the power gain contours or the input/ output match. Hence, the development of similar analytical design tools that are able to extend s-parameters capabilities in small-signal design to non-linear ap- v plications means a new challenge that is going to be faced in the present work. Therefore, the development of an analytical design framework, based on loadindependent X-parameters, constitutes the core of this Thesis. These analytical nonlinear design approaches would enable to significantly improve current large-signal design processes as well as dramatically decrease the required design time and thus, obtain more efficient approaches.

Coupled model of initiation and propagation of corrosion in reinforced concrete

Corrosion of reinforcing steel in concrete due to chloride ingress is one of the main causes of the deterioration of reinforced concrete structures. Structures most affected by such a corrosion are marine zone buildings and structures exposed to de-icing salts like highways and bridges. Such process is accompanied by an increase in volume of the corrosión products on the rebarsconcrete interface. Depending on the level of oxidation, iron can expand as much as six times its original volume. This increase in volume exerts tensile stresses in the surrounding concrete which result in cracking and spalling of the concrete cover if the concrete tensile strength is exceeded. The mechanism by which steel embedded in concrete corrodes in presence of chloride is the local breakdown of the passive layer formed in the highly alkaline condition of the concrete. It is assumed that corrosion initiates when a critical chloride content reaches the rebar surface. The mathematical formulation idealized the corrosion sequence as a two-stage process: an initiation stage, during which chloride ions penetrate to the reinforcing steel surface and depassivate it, and a propagation stage, in which active corrosion takes place until cracking of the concrete cover has occurred. The aim of this research is to develop computer tools to evaluate the duration of the service life of reinforced concrete structures, considering both the initiation and propagation periods. Such tools must offer a friendly interface to facilitate its use by the researchers even though their background is not in numerical simulation. For the evaluation of the initiation period different tools have been developed: Program TavProbabilidade: provides means to carry out a probability analysis of a chloride ingress model. Such a tool is necessary due to the lack of data and general uncertainties associated with the phenomenon of the chloride diffusion. It differs from the deterministic approach because it computes not just a chloride profile at a certain age, but a range of chloride profiles for each probability or occurrence. Program TavProbabilidade_Fiabilidade: carries out reliability analyses of the initiation period. It takes into account the critical value of the chloride concentration on the steel that causes breakdown of the passive layer and the beginning of the propagation stage. It differs from the deterministic analysis in that it does not predict if the corrosion is going to begin or not, but to quantifies the probability of corrosion initiation. Program TavDif_1D: was created to do a one dimension deterministic analysis of the chloride diffusion process by the finite element method (FEM) which numerically solves Fick’second Law. Despite of the different FEM solver already developed in one dimension, the decision to create a new code (TavDif_1D) was taken because of the need to have a solver with friendly interface for pre- and post-process according to the need of IETCC. An innovative tool was also developed with a systematic method devised to compare the ability of the different 1D models to predict the actual evolution of chloride ingress based on experimental measurements, and also to quantify the degree of agreement of the models with each others. For the evaluation of the entire service life of the structure: a computer program has been developed using finite elements method to do the coupling of both service life periods: initiation and propagation. The program for 2D (TavDif_2D) allows the complementary use of two external programs in a unique friendly interface: • GMSH - an finite element mesh generator and post-processing viewer • OOFEM – a finite element solver. This program (TavDif_2D) is responsible to decide in each time step when and where to start applying the boundary conditions of fracture mechanics module in function of the amount of chloride concentration and corrosion parameters (Icorr, etc). This program is also responsible to verify the presence and the degree of fracture in each element to send the Information of diffusion coefficient variation with the crack width. • GMSH - an finite element mesh generator and post-processing viewer • OOFEM – a finite element solver. The advantages of the FEM with the interface provided by the tool are: • the flexibility to input the data such as material property and boundary conditions as time dependent function. • the flexibility to predict the chloride concentration profile for different geometries. • the possibility to couple chloride diffusion (initiation stage) with chemical and mechanical behavior (propagation stage). The OOFEM code had to be modified to accept temperature, humidity and the time dependent values for the material properties, which is necessary to adequately describe the environmental variations. A 3-D simulation has been performed to simulate the behavior of the beam on both, action of the external load and the internal load caused by the corrosion products, using elements of imbedded fracture in order to plot the curve of the deflection of the central region of the beam versus the external load to compare with the experimental data.

Impacto y protección radiológica asociados al transporte de residuos de alta actividad (RAA) al almacén temporal centralizado (ATC) en España

Las cuestiones relacionadas con el transporte de residuos radiactivos de alta actividad (RAA) al previsto almacén temporal centralizado (ATC) en Villar de Cañas (Cuenca) están de actualidad, debido a la movilidad que se espera en un futuro próximo, el compromiso con el medio ambiente, la protección de las personas, así, como la normativa legal reguladora. En esta tesis se ha evaluado el impacto radiológico asociado a este tipo de transportes mediante una nueva herramienta de procesamiento de datos, que puede ser de utilidad y servir como documentación complementaria a la recogida en el marco legal del transporte. Además puede facilitar el análisis desde una perspectiva más científica, para investigadores, responsables públicos y técnicos en general, que pueden utilizar dicha herramienta para simular distintos escenarios de transportes radiactivos basados únicamente en datos de los materiales de entrada y las rutas elegidas. Así, conociendo el nivel de radiación a un metro del transporte y eligiendo una ruta, obtendremos los impactos asociados, tales como las poblaciones afectadas, la dosis recibida por la persona más expuesta, el impacto radiológico global, las dosis a la población en el trayecto y el posible detrimento de su salud. En España se prevé una larga “ruta radiactiva” de más de 2.000 kilómetros, por la que el combustible nuclear gastado se transportará presumiblemente por carretera desde las centrales nucleares hasta el ATC, así como los residuos vitrificados procedentes del reprocesado del combustible de la central nuclear Vandellos I, que en la actualidad están en Francia. Como conclusión más importante, se observa que la emisión de radiaciones ionizantes procedentes del transporte de residuos radiactivos de alta actividad en España, en operación normal, no es significativa a la hora de generar efectos adversos en la salud humana y su impacto radiológico puede considerarse despreciable. En caso de accidente, aunque la posibilidad del suceso es remota, las emisiones, no serán determinantes a la hora de generar efectos adversos en la salud humana. Issues related to the transport of high level radioactive wastes (HLW) to the new centralised temporary storage facility to be built in Villar de Cañas (Cuenca) are attracting renewed attention due to the mobility expected in the near future for these materials, the commitment to the environment, the protection of persons and the legal regulatory standards. This study assesses the radiological impacts associated with this type of transport by means of a new dataprocessing tool, which may be of use and serve as documentation complementary to that included in the legal framework covering transport. Furthermore, it may facilitate analysis from a more scientific perspective for researchers, public servants and technicians in general, who may use the tool to simulate different radioactive transport scenarios based only on input materials data and the routes selected. Thus, by knowing the radiation level at a distance of one metre from the transport and selecting a route, it is possible to obtain the associated impacts, such as the affected populations, the dose received by the most exposed individual, the overall radiological impact and the doses to the public en route and the possible detriment to their health. In Spain a long “radioactive route” of more than 2,000 kilometres is expected, along which spent nuclear fuels will be transported – foreseeably by road – from the nuclear power plants to the CTS facility. The route will also be used for the vitrified wastes from fuel reprocessing of the fuel from Vandellós I nuclear power plant, which are currently in France. In conclusion, it may be observed that the emission of ionising radiations from transport of high level radioactive wastes in Spain is insignificant, in normal operations, as regards the generation of adverse effects for human health, and that the radiological impact may be considered negligible. In the event of an accident, the possibility of which is remote, the emissions will not be also a very determining factor as regards adverse effects for human health.

Exploring the feasibility of integrating water issues into the CAPRI model

Although numerous modelling efforts have integrated food and water considerations at the farm or river basin level, very few agro-economic models are able to jointly assess water and food policies at the global level. The present report explores the feasibility of integrating water considerations into the CAPRI model. First, a literature review of modelling approaches integrating food and water issues has been conducted. Three agro-economic models, IMPACT, WATERSIM and GLOBIOM, have been analysed in detail. In addition, biophysical and hydrological models estimating agricultural water use have also been studied, in particular the global hydrological model WATERGAP and the LISFLOOD model. Thanks to the programming approach of its supply module, CAPRI shows a high potentiality to integrate environmental indicators as well as to enter new resource constraints (land potentially irrigated, irrigation water) and input-output relationships. At least in theory, the activity-based approach of the regional programming model in CAPRI allows differentiating between rainfed and irrigated activities. The suggested approach to include water into the CAPRI model involves creating an irrigation module and a water use module. The development of the CAPRI water module will enable to provide scientific assessment on agricultural water use within the EU and to analyze agricultural pressures on water resources. The feasibility of the approach has been tested in a pilot case study including two NUTS 2 regions (Andalucia in Spain and Midi-Pyrenees in France). Preliminary results are presented, highlighting the interrelations between water and agricultural developments in Europe. As a next step, it is foreseen to further develop the CAPRI water module to account for competition between agricultural and non-agricultural water use. This will imply building a water use sub-module to compute water use balances.

Methodologies for Impact Assessment in the Ex Ante Evaluation of European Rural Development Programmes.

The ex ante quantification of impactsis compulsory when establishing a Rural Development Program (RDP) in the European Union. Thus, the purpose of this paper is to learn how to perform it better. In order to this all of the European 2007-2013 RDPs (a total of 88) and all of their corresponding available ex ante evaluations were analyzed.Results show that less than 50% of all RDPs quantify all the impact indicators and that the most used methodology that allows the quantification of all impact indicators is Input-Output. There are two main difficulties cited for not accomplishing the impact quantification: the heterogeneity of actors and factors involved in the program impacts and the lack of needed information.These difficulties should be addressedby usingnew methods that allow approaching the complexity of the programs and by implementing a better planning that facilitatesgathering the needed information.

Modelling of chloride transport in non-saturated concrete : from microscale to macroscale

A model for chloride transport in concrete is proposed. The model accounts for transport several transport mechanisms such as diffusion, advection, migration, etc. This work shows the chloride transport equations at the macroscopic scale in non-saturated concrete. The equations involve diffusion, migration, capillary suction, chloride combination and precipitation mechanisms. The material is assumed to be infinitely rigid, though the porosity can change under influence of chloride binding and precipitation. The involved microscopic and macroscopic properties of the materials are measured by standardized methods. The variables which must be imposed on the boundaries are temperature, relative humidity and chloride concentration. The output data of the model are the free, bound, precipitated and total chloride ion concentrations, as well as the pore solution content and the porosity. The proposed equations are solved by means of the finite element method (FEM) implemented in MATLAB (classical Galerkin formulation and the streamline upwind Petrov-Galerkin (SUPG) method to avoid spatial instabilities for advection dominated flows).

Software tool for simulation of aircraft trajectories

New concepts in air navigation have been introduced recently. Among others, are the concepts of trajectory optimization, 4D trajectories, RBT (Reference Business Trajectory), TBO (trajectory based operations), CDA (Continuous Descent Approach) and ACDA (Advanced CDA), conflict resolution, arrival time (AMAN), introduction of new aircraft (UAVs, UASs) in air space, etc. Although some of these concepts are new, the future Air Traffic Management will maintain the four ATM key performance areas such as Safety, Capacity, Efficiency, and Environmental impact. So much, the performance of the ATM system is directly related to the accuracy with which the future evolution of the traffic can be predicted. In this sense, future air traffic management will require a variety of support tools to provide suitable help to users and engineers involved in the air space management. Most of these tools are based on an appropriate trajectory prediction module as main component. Therefore, the purposes of these tools are related with testing and evaluation of any air navigation concept before they become fully operative. The aim of this paper is to provide an overview to the design of a software tool useful to estimate aircraft trajectories adapted to air navigation concepts. Other usage of the tool, like controller design, vertical navigation assessment, procedures validation and hardware and software in the loop are available in the software tool. The paper will show the process followed to design the tool, the software modules needed to perform accurately and the process followed to validate the output data.

Impact of introducing longer and heavier vehicles on regional consumer price index and Spanish road freight transport system

This paper applies an integrated modeling approach to the case of Spain; the approach is based on a random utility-based multiregional input-output model and a road transport network model for assessing the effect of introducing longer and heavier vehicles (LHVs) on the regional consumer price index (CPI) and on the transportation system. The approach strongly supports the concept that changes in transport costs derived from the LHV allowance as well as the economic structure of regions have direct and indirect effects on the economy and on the transportation system. Results show that the introduction of LHVs might reduce prices paid by consumers for a representative basket of goods and services in the regions of Spain and would also lead to a reduction in the regional CPI. In addition, the magnitude and extent of changes in the transportation system are estimated by using the commodity-based structure of the approach to identify the effect of traffic changes on traffic flows and on pollutant emissions over the whole network.

Huella de carbono de organización y producto con enfoque híbrido: mejoras en el método compusto de las cuentas contables

La lucha contra el cambio climático es uno de los retos ambientales más importantes de este siglo XXI. Para alcanzar el objetivo de reducir las emisiones de gases de efecto invernadero es necesario desarrollar herramientas aplicables a todas las actividades de la economía con las que medir el impacto generado por la actividad del hombre. La Huella de Carbono (HC) forma parte de un conjunto de indicadores desarrollados para responder a esta necesidad. Nuestra línea de trabajo parte del hecho de que la demanda de una baja HC puede ser un factor clave para estimular cambios en los hábitos de consumos y para mejorar la eficiencia en los procesos de producción. Sin embargo, una de las principales dificultades halladas al respecto es la diferencia de enfoques para el cálculo de la HC de producto y la HC de organización. De igual manera existen importantes dificultades en el establecimiento de los límites del sistema en estudio. Para asegurar el éxito de la implantación de la HC en la sociedad, es necesario el establecimiento de los mismos criterios en los distintos estudios. Por este camino, la comparabilidad esta comprometida y con ello la confianza del consumidor. Los avances en el cálculo de HC se basan en dos propuestas ampliamente conocidas: El Análisis de Ciclo de Vida y la Extensión Ambiental del Análisis Input-Output. Ambas metodologías tienen relevantes aspectos positivos y negativos. Por lo tanto, la hibridación entre ambos enfoques supone una clara oportunidad en la búsqueda de sinergias. En respuesta a esta demanda, diferentes herramientas de enfoque híbrido están siendo desarrolladas. La investigación de esta tesis doctoral parte del avance desarrollado en la concepción del Método Compuesto de las Cuentas Contables (MC3). El MC3 es un método de análisis híbrido por niveles que desarrolla un cálculo exhaustivo de la HC de organización para el posterior cálculo de la HC de producto. Esta investigación tiene como objetivo general evaluar el MC3 como herramienta de cálculo de la HC, válida tanto para organización como para producto. En este sentido, se analizan pormenorizadamente cuatro casos de estudios con características innovadoras. Tres de ellos empleando el MC3 en diferentes unidades de estudio: organización, producto y escenario internacional. La aplicación a organización se realiza sobre un centro universitario, permitiendo el análisis detallado de diferentes aspectos metodológicos. La aplicación a producto compara los resultados del MC3 con la aplicación tradicional de un Análisis de Ciclo de Vida. El escenario internacional se desarrolla en Brasil sobre la producción energética en un parque eólico de grandes dimensiones. Por último, el caso de estudio 4 se basa en la Extensión Ambiental del Análisis Multi-Region Input-Output. Este estudio elabora una nueva aproximación para el análisis del impacto generado por un hipotético cierre del comercio internacional. Estos estudios son discutidos en su conjunto a fin de poner en valor las fortalezas de las innovaciones implementadas con un sentido integrador. También se proponen estrategias futuras que permitan mejorar la propuesta metodológica del MC3 con el punto de mira puesto en la internacionalización y la armonización con los estándares internacionales de la HC. Según la experiencia desarrollada, el MC3 es un método de cálculo de la HC práctico y válido para evaluar la cantidad de emisiones directas e indirectas de gases de efecto invernadero de cualquier tipo de actividad. Una de las principales conclusiones es que el MC3 puede ser considerado una herramienta válida para el ecoetiquetado global de bienes y servicios que permita, tanto a empresas como a consumidores, funcionar como motores de cambios hacia una economía dinamizada por la búsqueda de la racionalización en el uso de los recursos.

Analysis of the railway track as a spatially periodic structure

This article presents a new and computationally efficient method of analysis of a railway track modelled as a continuous beam of 2N spans supported by elastic vertical springs. The main feature of this method is its important reduction in computational effort with respect to standard matrix methods of structural analysis. In this article, the whole structure is considered to be a repetition of a single one. The analysis presented is applied to a simple railway track model, i.e. to a repetitive beam supported on vertical springs (sleepers). The proposed method of analysis is based on the general theory of spatially periodic structures. The main feature of this theory is the possibility to apply Discrete Fourier Transform (DFT) in order to reduce a large system of q(2N + 1) linear stiffness equilibrium equations to a set of 2N + 1 uncoupled systems of q equations each. In this way, a dramatic reduction of the computational effort of solving the large system of equations is achieved. This fact is particularly important in the analysis of railway track structures, in which N is a very large number (around several thousands), and q = 2, the vertical displacement and rotation, is very small. The proposed method allows us to easily obtain the exact solution given by Samartín [1], i.e. the continuous beam railway track response. The comparison between the proposed method and other methods of analysis of railway tracks, such as Lorente de Nó and Zimmermann-Timoshenko, clearly shows the accuracy of the obtained results for the proposed method, even for low values of N. In addition, identical results between the proposed and the Lorente methods have been found, although the proposed method seems to be of simpler application and computationally more efficient than the Lorente one. Small but significative differences occur between these two methods and the one developed by Zimmermann-Timoshenko. This article also presents a detailed sensitivity analysis of the vertical displacement of the sleepers. Although standard matrix methods of structural analysis can handle this railway model, one of the objectives of this article is to show the efficiency of DFT method with respect to standard matrix structural analysis. A comparative analysis between standard matrix structural analysis and the proposed method (DFT), in terms of computational time, input, output and also software programming, will be carried out. Finally, a URL link to a MatLab computer program list, based on the proposed method, is given

Asphalt rubber mixtures with warm mix asphalt additives

En los últimos años, debido a la creciente preocupación por el calentamiento global y el cambio climático, uno de los retos más importantes a los que se enfrenta nuestra sociedad es el uso eficiente y económico de energía así como la necesidad correspondiente de reducir los gases de efecto invernadero (GEI). Las tecnologías de mezclas semicalientes se han convertido en un nuevo e importante tema de investigación en el campo de los materiales para pavimentos ya que ofrece una solución potencial para la reducción del consumo energético y las emisiones de GEI durante la producción y puesta en obra de las mezclas bituminosas. Por otro lado, los pavimentos que contienen polvo de caucho procedente de neumático fuera de uso, al hacer uso productos de desecho, ahorran energía y recursos naturales. Estos pavimentos ofrecen una resistencia mejorada a la formación de roderas, a la fatiga y a la fisuración térmica, reducen los costes de mantenimiento y el ruido del tráfico así como prolongan la vida útil del pavimento. Sin embargo, estas mezclas presentan un importante inconveniente: la temperatura de fabricación se debe aumentar en comparación con las mezclas asfálticas convencionales, ya que la incorporación de caucho aumenta la viscosidad del ligante y, por lo tanto, se producen mayores cantidades de emisiones de GEI. En la presente Tesis, la tecnología de mezclas semicalientes con aditivos orgánicos (Sasobit, Asphaltan A, Asphaltan B, Licomont) se incorporó a la de betunes de alta viscosidad modificados con caucho (15% y 20% de caucho) con la finalidad de dar una solución a los inconvenientes de mezclas con caucho gracias a la utilización de aditivos reductores de la viscosidad. Para este fin, se estudió si sería posible obtener una producción más sostenible de mezclas con betunes de alto contenido en caucho sin afectar significativamente su nivel de rendimiento mecánico. La metodología aplicada para evaluar y comparar las características de las mezclas consistió en la realización de una serie de ensayos de laboratorio para betunes y mezclas con caucho y con aditivos de mezclas semicalientes y de un análisis del ciclo de vida híbrido de la producción de mezclas semicalientes teniendo en cuenta la papel del aditivo en la cadena de suministro con el fin de cuantificar con precisión los beneficios de esta tecnología. Los resultados del estudio indicaron que la incorporación de los aditivos permite reducir la viscosidad de los ligantes y, en consecuencia, las temperaturas de producción y de compactación de las mezclas. Por otro lado, aunque la adición de caucho mejoró significativamente el comportamiento mecánico de los ligantes a baja temperatura reduciendo la susceptibilidad al fenómeno de fisuración térmica, la adición de las ceras aumentó ligeramente la rigidez. Los resultados del estudio reológico mostraron que la adición de porcentajes crecientes de caucho mejoraban la resistencia del pavimento con respecto a la resistencia a la deformación permanente a altas temperaturas y a la fisuración térmica a bajas temperaturas. Además, se observó que los aditivos mejoran la resistencia a roderas y la elasticidad del pavimento al aumentar el módulo complejo a altas temperaturas y al disminuir del ángulo de fase. Por otra parte, el estudio reológico confirmó que los aditivos estudiados aumentan ligeramente la rigidez a bajas temperaturas. Los ensayos de fluencia llevados a cabo con el reómetro demostraron una vez más la mejora en la elasticidad y en la resistencia a la deformación permanente dada por la adición de las ceras. El estudio de mezclas con caucho y aditivos de mezclas semicalientes llevado a cabo demostró que las temperaturas de producción/compactación se pueden disminuir, que las mezclas no experimentarían escurrimiento, que los aditivos no cambian significativamente la resistencia conservada y que cumplen la sensibilidad al agua exigida. Además, los aditivos aumentaron el módulo de rigidez en algunos casos y mejoraron significativamente la resistencia a la deformación permanente. Asimismo, a excepción de uno de los aditivos, las mezclas con ceras tenían la misma o mayor resistencia a la fatiga en comparación con la mezcla control. Los resultados del análisis de ciclo de vida híbrido mostraron que la tecnología de mezclas semicalientes es capaz de ahorrar significativamente energía y reducir las emisiones de GEI, hasta un 18% y 20% respectivamente, en comparación con las mezclas de control. Sin embargo, en algunos de los casos estudiados, debido a la presencia de la cera, la temperatura de fabricación debe reducirse en un promedio de 8 ºC antes de que los beneficios de la reducción de emisiones y el consumo de combustible puedan ser obtenidos. Los principales sectores contribuyentes a los impactos ambientales generados en la fabricación de mezclas semicalientes fueron el sector de los combustibles, el de la minería y el de la construcción. Due to growing concerns over global warming and climate change in recent years, one of the most important challenges facing our society is the efficient and economic use of energy, and with it, the corresponding need to reduce greenhouse gas (GHG) emissions. The Warm Mix Asphalt (WMA) technology has become an important new research topic in the field of pavement materials as it offers a potential solution for the reduction of energy consumption and GHG emissions during the production and placement of asphalt mixtures. On the other hand, pavements containing crumb-rubber modified (CRM) binders save energy and natural resources by making use of waste products. These pavements offer an improved resistance to rutting, fatigue and thermal cracking; reduce traffic noise and maintenance costs and prolong pavement life. These mixtures, however, present one major drawback: the manufacturing temperature is higher compared to conventional asphalt mixtures as the rubber lends greater viscosity to the binder and, therefore, larger amounts of GHG emissions are produced. In this dissertation the WMA technology with organic additives (Sasobit, Asphaltan A, Asphaltan B and Licomont) was applied to CRM binders (15% and 20% of rubber) in order to offer a solution to the drawbacks of asphalt rubber (AR) mixtures thanks to the use of fluidifying additives. For this purpose, this study sought to determine if a more sustainable production of AR mixtures could be obtained without significantly affecting their level of mechanical performance. The methodology applied in order to evaluate and compare the performance of the mixtures consisted of carrying out several laboratory tests for the CRM binders and AR mixtures with WMA additives (AR-WMA mixtures) and a hybrid input-output-based life cycle assessment (hLCA) of the production of WMA. The results of the study indicated that the incorporation of the organic additives were able to reduce the viscosity of the binders and, consequently, the production and compaction temperatures. On the other hand, although the addition of rubber significantly improved the mechanical behaviour of the binders at low temperatures reducing the susceptibility to thermal cracking phenomena, the addition of the waxes slightly increased the stiffness. Master curves showed that the addition of increasing percentages of rubber improved the resistance of the pavement regarding both resistance to permanent deformation at high temperatures and thermal cracking at low temperatures. In addition, the waxes improved the rutting resistance and the elasticity as they increased the complex modulus at high temperatures and decreased the phase angle. Moreover, master curves also attest that the WMA additives studied increase the stiffness at low temperatures. The creep tests carried out proved once again the improvement in the elasticity and in the resistance to permanent deformation given by the addition of the waxes. The AR-WMA mixtures studied have shown that the production/compaction temperatures can be decreased, that the mixtures would not experience binder drainage, that the additives did not significantly change the retained resistance and fulfilled the water sensitivity required. Furthermore, the additives increased the stiffness modulus in some cases and significantly improved the permanent deformation resistance. Except for one of the additives, the waxes had the same or higher fatigue resistance compared to the control mixture. The results of the hLCA demonstrated that the WMA technology is able to significantly save energy and reduce GHG emissions, up to 18% and 20%, respectively, compared to the control mixtures. However, in some of the case studies, due to the presence of wax, the manufacturing temperature at the asphalt plant must be reduced by an average of 8ºC before the benefits of reduced emissions and fuel usage can be obtained. The results regarding the overall impacts generated using a detailed production layer decomposition indicated that fuel, mining and construction sectors are the main contributors to the environmental impacts of manufacturing WMA mixtures.

Numerical analysis of shell and spatial structures

Since the advent of the computer into the engineering field, the application of the numerical methods to the solution of engineering problems has grown very rapidly. Among the different computer methods of structural analysis the Finite Element (FEM) has been predominantly used. Shells and space structures are very attractive and have been constructed to solve a large variety of functional problems (roofs, industrial building, aqueducts, reservoirs, footings etc). In this type of structures aesthetics, structural efficiency and concept play a very important role. This class of structures can be divided into three main groups, namely continuous (concrete) shells, space frames and tension (fabric, pneumatic, cable etc )structures. In the following only the current applications of the FEM to the analysis of continuous shell structures will be discussed. However, some of the comments on this class of shells can be also applied to some extend to the others, but obviously specific computational problems will be restricted to the continuous shells. Different aspects, such as, the type of elements,input-output computational techniques etc, of the analysis of shells by the FEM will be described below. Clearly, the improvements and developments occurring in general for the FEM since its first appearance in the fifties have had a significative impact on the particular class of structures under discussion.