A revisited thermal, hydrodynamic, chemical and mechanical model of compacted bentonite for the entire duration of the FEBEX in situ test

Versión aceptada de https://doi.org/10.1016/j.clay.2018.02.019[Abstract:] The safety assessment of geological repositories for radioactive waste requires quantifying the geochemical evolution of the engineered clay barriers where thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) phenomena play a major role during the early stages of the repository. Compacted bentonite is one of the components of the engineered barrier system. The FEBEX (Full-scale Engineered Barrier EXperiment) in situ heating and hydration test was performed at the Grimsel underground laboratory (Switzerland) in two operation periods. The 1st period lasted from 1997 to 2002 when heater 1 was switched off and the area around it was dismantled. Heater 2 was turned off and the full test was dismantled in 2015. Here we present a revisited THCM model of the two operation periods of the FEBEX in situ test, which improves the THCM model reported by Zheng et al. (2011) for the 1st operation period by revising the boundary condition at the heater/bentonite interface, refining the spatial discretization of the finite element mesh near the heater, updating the dispersivities of the bentonite and the granite and revisiting the back-diffusion of solutes from the bentonite barrier into the granite. The concentrations of dissolved Cl− computed with the revisited model at the end of the 1st operation period almost coincide with those of the previous model, except near the heater where the concentrations computed with the revisited model are much larger than those of the previous model. Both models provide a similar fit to the pore water concentration data inferred from aqueous extracts because the model differences occur in a band 0.045 m thick near the heater where there are no measured pore water chemical data. Solute back-diffusion from the bentonite pore water to the granite groundwater is not uniform along the FEBEX gallery due to the heterogeneity of the surrounding granitic formation. The revisited model reproduces the trends of the experimental observations of solute back-diffusion by adopting diffusion coefficients of the bentonite and granite larger than those of the simulation run without the solute back-diffusion. The results of the revisited THCM model match the gravimetric water content and dry density data measured at the end of both operation periods in 2002 and 2015 and fit the general trends of the on line data of temperature and volumetric water content in the bentonite and pore water pressure in the granitic rock collected from 2002 to 2015. The predicted concentrations of the dissolved species in 2002 are sensitive to changes in the vapour tortuosity factor and the retention curve of the bentonite, but are less sensitive to smectite dissolution. The predicted concentrations of the dissolved species at the end of the 2nd operation period in 2015 computed with the revisited THCM model are large near the heater and decrease towards the bentonite/granite interface. The concentrations are generally smaller than those computed at the end of the 1st operation period, except for the concentration of dissolved HCO3– which increases due to a calcite dissolution front. The predicted pH at the end of the 2nd operation period is similar to that of the 1st operation period. The concentrations of dissolved Cl− predicted at the end of the 2nd period with the revisited model reproduce the sharp increase of the measured Cl− data near the heater and match the data measured in 5 out of 6 radial distances.The FEBEX-DP Consortium funded the dismantling operation in 2015. The support of the responsible person of the Consortium, Dr. Florian Kober, is greatly acknowledged. Additional funding by the Spanish Ministry of Economy and Competitiveness (Project CGL2016-78281-R), the FEDER funds (Project CGL2016-78281-R) and the Galician Regional Government (Ref. ED431C 2017/67 from “Consolidación e Estruturación de Unidades de Investigación Competitivas”, Grupos de Referencia Competitiva) are acknowledged. Alba Mon enjoyed a research contract from University of A Coruña. We thank the comments, corrections and suggestions of the two reviewers which contributed to the significant improvement of the paper.Xunta de Galicia; ED431C 2017/6

Analysis of the parameter identifiability of the in situ diffusion and retention (DR) experiments

Versión aceptada de https://doi.org/10.1016/j.pce.2010.04.012[Abstract:] In situ diffusion experiments are performed at underground research laboratories to overcome the limitations of laboratory diffusion experiments. The diffusion and retention (DR) experiments are long-term, natural-scale, in situ experiments performed in the anisotropic Opalinus Clay Formation at Mont Terri, Switzerland. Dilution data are monitored at the injection interval and overcoring data will be measured at samples around the injection interval at the end of the experiment during overcoring. Interpretation of DR experiments is complicated by the non-ideal effects caused by the sintered filter, the gap between the filter and the borehole wall and the excavation disturbed zone (EdZ). Their impact on parameter estimates has been evaluated with numerical sensitivity analyses and synthetic experiments having the same geometry and parameters as the real DR experiments. Dimensionless sensitivities of tracer concentrations in the injection interval and along the overcoring profiles have been computed numerically. They have been used to identify the tracer parameters that can be estimated with the least uncertainty from tracer dilution and overcoring data. Sensitivities of tracer dilution data change with time and those of overcoring concentrations along the bedding are different from those along profiles normal to the bedding. Concentrations along overcoring profiles are sensitive to the effective diffusion normal to the bedding. Synthetic experiments generated with prescribed known parameters have been interpreted automatically with INVERSE-CORE2D and used to evaluate the relevance of non-ideal effects and determine parameter identifiability in the presence of random errors for HTO and 22Na+. Model results show that it is difficult to estimate the parameters of the undisturbed clay when the tracer dilution data contain noise. The convergence of the estimation algorithm improves when the starting values are smaller than the true parameters. Although the parameters of the undisturbed clay and the EdZ cannot be estimated using tracer dilution data, their joint estimation from overcoring noisy data is possible for standard deviations of the noise up to 0.05. Large estimation errors in the parameters of the undisturbed clay and poor fits are obtained when the assumption about the existence of EdZ is incorrect. The effective diffusion of the filter is a key parameter for the interpretation of the experiments. Small errors in the volume of the circulation system do not affect the estimates of the component of the effective diffusion of undisturbed clay parallel to bedding. The results of the identifiability analysis clearly shows that: (1) The proper interpretation of in situ DR experiments requires accounting for the filter and the EdZ and (2) Overcoring data allow a more accurate estimation of the parameters of the undisturbed clay than the tracer dilution data.This work was supported by the Mont Terri Consortium and the Spanish Ministry of Science and Technology through Project CGL2006-09080 and a research scholarship awarded to the third author. We thank Josep Soler, Thomas Gimmi and Olivier Leupin for fruitful discussions on the DR experiments and their interpretation. We are also grateful to the two anonymous reviewers for their comments which improved the paper

In situ diffusion experiments: Effect of water sampling on tracer concentrations and parameters

Versión aceptada de https://doi.org/10.1016/j.pce.2010.04.009[Abstract:] In situ diffusion experiments are performed at underground research laboratories (URL) in clay formations to overcome the limitations of laboratory diffusion experiments and investigate scale effects. Tracers are monitored in the circulation system by aliquoting the solution at selected times. The extracted samples may be replaced with the same volume of synthetic unspiked water as it is done in the Bure URL (France). Sampling with replacement induces the tracer dilution. In the sampling method used in the Mont Terri URL (Switzerland), on the other hand, sampling volumes are not replaced. In this case, there is no tracer dilution, but the volume in circulation decreases progressively. Water sampling is commonly disregarded in the numerical interpretation of such experiments. However, water sampling may induce changes in the tracer concentrations and errors in the estimated diffusion and sorption parameters. Such errors have been analyzed here with a numerical model which accounts for sample extraction, sample replacement and the changes in the volume of the circulation system. These errors have been analyzed for HTO, 36Cl−, 22Na+ and 134Cs+ in the DIR2003 and EST 208 experiments at the Bure URL and for HTO, HDO, Br−, 22Na+, 85Sr2+, 133Ba2+ and 137Cs+ in the DR experiments at the Mont Terri URL. The effect of water sampling on the relative tracer concentrations depends on the sampling method and frequency, the volume of the sample and the volume of the circulation system. Water sampling causes minor differences in relative tracer concentrations in the DR experiments and its effect can be disregarded. In the DIR2003 experiment, however, the differences induced by aliquoting cannot not be neglected. 36Cl− is the tracer most affected by sampling and 134Cs+ is the least influenced. The identifiability analysis of the EST208 experiment reveals that failing to account for the effect of water sampling may lead to a significant overestimation of diffusion and sorption parameters, especially for 36Cl−. The results of our analysis indicate that the effects of the water sampling should not be neglected without a careful in-depth analysis.This work was supported by ANDRA and the Spanish Ministry of Science and Technology through the Research Project CGL2006-09080 and a FPI Research Scholarship awarded by the Spanish Ministry to the first author. We are grateful to the two anonymous reviewers for their comments and recommendations which improved the paper

Réplica adaptada dunha metodoloxía activa desenvolvida na UDC noutras titulacións e Universidades mediante a colaboración entre docentes

[Resumo] No curso 2016-17, desenvolveuse unha iniciativa de innovación docente na materia de Hidroloxía Aplicada ás Obras Públicas do grao en Enxeñaría de Obras Públicas da UDC. O obxectivo desta materia é asimilar os conceptos básicos de hidroloxía e as súas aplicacións ás obras de enxeñaría civil. Os alumnos e as alumnas resolveron co software VISUALCORE problemas reais simplificados do efecto de drenes e pantallas no fluxo subterráneo. Dito software é unha versión adaptada á docencia do código CORE (Samper et al., 2011) desenvolvido polo grupo de investigación Aquaterra. A actividade foi avaliada moi positivamente polos estudantes e permitiu: (1) Fixar e profundar nos conceptos estudados e (2) Motivar ao alumnado achegando a teoría a realidade e amosándolles as habilidades adquiridas na materia e a utilidade do aprendido nas aplicacións reais. Unha docente da Universidade do Miño púxose en contacto co profesorado da UDC coa intención de replicar a metodoloxía no seu centro en tres materias de diferentes titulacións: (1) Hidroxeoloxía do Grado en Bioloxía-Xeoloxía; (2) Hidroxeoloxía do Grado en Xeoloxía e (3) Xestión das Augas Subterráneas do Mestrado en Xeociencias. Traballouse conxuntamente para adaptar a metodoloxía aos contidos e ás competencias das materias. Unha profesora da UDC realizou dúas estadías cortas na Universidade do Minho, no marco do programa Erasmus+ (EU, 2018), para impartir as clases co software e mostrar ao alumnado aplicacións reais da actividade profesional dun hidroxeólogo. A avaliación dos estudantes e da profesora da Universidade do Minho foi excelente. No futuro, preténdese fortalecer esta colaboración docente interuniversitaria e posiblemente estendela nalgún Traballo Fin de Mestrad

Estrategias de edición genómica en la cianobacteria Synechococcus elongatus

Las cianobacterias, los únicos procariotas que realizan fotosíntesis oxigénica, tienen un gran potencial biotecnológico. Synechococcus elongatus es uno de los sistemas modelo de referencia en la investigación de procesos como el control del ritmo circadiano, la división celular o la regulación por nitrógeno. En el contexto del análisis genético de Synechococcus, la manipulación genética implica estrategias ya establecidas que implican un tiempo considerable para la obtención de estirpes mutantes. Muy recientemente se ha empezado a implementar la herramienta (sistema) CRISPR/Cas9 para la modificación de cepas de Synechococus, el cual puede acelerar el proceso de obtención de estirpes e incrementar la precisión de la modificación. En este trabajo se describirán los sistemas de edición genómica en Synechococcus con especial interés del sistema CRISPR del cual se propondrá una estrategia virtual para la modificación genética de Synechococcus elongatus

An efficient hybrid recommender system framework using semantic technology for social networks

The first group of companies that have a business on online social networks try to design an efficient plan for making more money on this platform. Advertising can be a solution for introducing and promoting the services or products for the clients and it can be led to more sells. There are a second group of companies intended to use advertisements on social networks, many of these annoy the users since they are not fascinating or matched for the clients. The primary target of the current study is to design and present a model of advertising recommender systems on social networks using innovative techniques. Although there are numerous applications and research works about recommender frameworks, in the proposed model, it is valuable to plan a recommender system which focus more precisely on the user's interests. The framework uses a semantic logic to increase the accuracy of the recommendations along with using a combination of four recommender methods, the particular estimations for each method and the integration of recommendations generated by each method using a rank-based approach which totally can differentiate the proposed recommender framework from the previous similar methods. The accuracy of suggested framework is 0,7498 that was revealed by implementing a web application. The comparison of some similar models with the current work based on various features and aspects shows a significant excellence of this study. --- El primer grupo de empresas que tienen un negocio en línea en redes sociales intenta diseñar un plan eficiente para incrementar sus ganancias en esta plataforma. La publicidad puede ser una solución para introducir y promocionar servicios o productos para los clientes, lo cual puede conducir a más ventas. Existe un segundo grupo de empresas destinadas a utilizar anuncios en las redes sociales, muchos de los cuales molestan a los usuarios ya que no son fascinantes o coinciden con los clientes. El objetivo principal del actual estudio es diseñar y presentar un modelo de sistemas de recomendación publicitaria en las redes sociales utilizando técnicas innovadoras. Aunque existen numerosas aplicaciones y trabajos de investigación sobre frameworks de recomendación, en el modelo propuesto, es valioso planificar un sistema de recomendación que se centre en los intereses del usuario. El framework utiliza una lógica semántica para aumentar la precisión de las recomendaciones junto con el uso de una combinación de cuatro métodos, las estimaciones particulares para cada método y la integración de las recomendaciones generadas mediante un enfoque basado en posiciones que puede diferenciar totalmente el framework de recomendación propuesto con respecto a métodos similares anteriores. La precisión del framework sugerido tiene un valor de 0,7498 que se obtuvo mediante la implementación de una aplicación web. La comparación de algunos modelos similares con el trabajo actual basado en diversas características y aspectos, muestra una excelencia significativa en este estudio

Dynamic update of flow and transport parameters in reactive transport simulations of radioactive waste repositories

Versión aceptada de https://doi.org/10.1016/j.apgeochem.2020.104585[Abstract:] The changes in porosity caused by mineral dissolution/precipitation and the associated changes in flow, transport and chemical parameters of porous and fractured media are relevant for the geochemical time-evolution of natural and engineered underground systems. The realistic representation of natural systems requires modeling tools accounting for the changes in porosity. Here, we investigate the significance of the dynamic upgrade of the flow, transport and chemical parameters in reactive transport models with mineral dissolution/precipitation. The water flow, heat transfer and multicomponent reactive solute transport code, CORE2DV5, was extended to take into account the changes in porosity provoked by mineral dissolution/precipitation and their effect on flow, solute transport and chemical parameters. The improvements implemented in the code were verified against analytical solutions and the numerical solutions computed with other reactive transport codes with similar capabilities for isothermal mineral dissolution/precipitation test cases. Model results computed with CORE2DV5 agree with the analytical and numerical solutions for several isothermal test cases with porosity feedback. Model results show that failing to account for the porosity feedback leads to large errors. The porosity feedback effect (PFE) is especially relevant in long-term problems with mineral dissolution/precipitation leading to strong changes in porosity. The PFE is analysed with a non-isothermal geochemically-reactive transport model of the long-term (4·104 years) interactions of compacted bentonite with corrosion products and concrete in a high-level radioactive waste repository in clay. The model predicts pore clogging in the concrete and at the concrete-clay interface. The thickness of the zone affected by pore clogging computed with the PFE is smaller than that computed without the PFE.This work was funded by the CEBAMA Project of the European Atomic Energy Community's (Euratom) Horizon 2020 Programme (NFRP-2014/2015) under grant agreement # 662147, the Spanish Ministry of Economy and Competitiveness (Project CGL2016-78281), the FEDER funds, ENRESA (Spain), and the Xunta de Galicia (Galician Regional Government, project ED431C 2017/67). The first author enjoyed a Contract from the FPI Program of the Spanish Ministry of Economy and Competitiveness. We thank the comments and corrections of the three anonymous reviewers who contributed to the improvement of the paper.Xunta de Galicia; ED431C 2017/6

Ontologías para servicios web semánticos de información de tráfico: descripción y herramientas de explotación.

RESUMEN Esta tesis forma parte de los denominados Sistemas Inteligentes de Tráfico (ITS) los cuales se basan en la aplicación de tecnologías de Telecomunicaciones e Informática (Telemática) a los sistemas de ayuda al tráfico vial, perteneciendo al dominio Servicios de Información al Viajero (TIS). Como se pone de manifiesto, existen algunos problemas derivados del uso de este tipo de sistemas, desde el punto de vista del usuario, que dan lugar a que éste sea incapaz de obtener la información clara y precisa correspondiente a sus requerimientos. Los principales problemas identificados han sido la falta de un vocabulario común de términos que haga uso de una semántica bien definida que permita obtener el significado (incluso aquél no explícito) de cada concepto de tráfico vial, así como la recuperación de información desde distintas fuentes heterogéneas, de una forma intuitiva y sencilla. Varios aspectos describen la problemática actual relativos al acceso y distribución de la información: 1. Un gran volumen de información de tráfico se distribuye entre varios sitios Web. El principal problema para un usuario que necesita información de este tipo es encontrar estos sitios Web y además tratar con los diferentes accesos a ésta, así como sus diferentes formas de presentación. 2. Por otra parte, un usuario puede necesitar información de diferente naturaleza o tipo, y por lo tanto el almacenaje de toda esta información en un solo sitio Web no es viable a nivel de costes de almacenamiento ni incluso a nivel de mantenimiento. 3. El tratamiento de la información no permite realizar inferencias sobre ella de manera que pueda ser obtenido como resultado, información que a priori no estuviera explícitamente detallada. Tras el descubrimiento de la problemática existente y la identificación de elementos que pudieran solventar esta situación, el presente trabajo se centra en el estudio de los sistemas ITS orientados a facilitar información de tráfico al usuario, y que a su vez permitan la gestión de la información, su tratamiento e intercambio, de manera eficaz entre los diferentes elementos que componen la arquitectura de servicios de información de tráfico, como los usuarios, aplicaciones, y proveedores de la información. Para la consecución de los objetivos marcados han sido desarrollados diversos elementos como parte integrante de una arquitectura, que supusieron determinados aportes y/o resultados: 1. Construcción de una infraestructura ontológica cuyo dominio queda enmarcado en la información sobre tráfico vial. 2. Se ha expuesto un marco de trabajo para la conversión de portales Web convencionales de información en Servicios Web Semánticos (SWS). 3. Extensión a las metodologías de construcción de ontologías, previamente existentes, para plantear el proceso a seguir en la obtención de un modelo semántico formal a partir de un modelo de Entidad-Relación (ER). 4. Se ha diseñado, implementado y evaluado, un algoritmo de emparejamiento de SWS, que aprovecha al máximo las capacidades proporcionadas por las ontologías de descripción de servicios y que constituye una mejora de los ya existentes. Inclusión del grado fraternal o de hermanos y otra serie de modificaciones. 5. Se han mostrado una serie de propuestas que permiten crear y manejar Servicios Web Semánticos de información de tráfico vial: nuevo parámetro no funcional (valor añadido), ontología de categorización de servicios de tráfico y elección de factores de medida en la QoS. Finalmente las propuestas han sido validadas a partir del desarrollo de un prototipo software basado en la arquitectura de integración de SWS de información sobre tráfico vial, que ha permitido el ensamblaje de todos los elementos (ontologías de tráfico, algoritmo de emparejamiento, servicios de información de tráfico), obtenidos como resultado en cada una de las etapas de esta investigación. __________________________________________________________________________________________________This thesis forms part of the common Intelligent Transportation Systems which in turn are based on the application of telecommunication and Informatics (Telematics) to traffic management which belongs to the domain of Traveller Information.. The principle identified problems are the lack of a common vocabulary of elements which use a well defined semantic description which permits obtaining the meaning (including the non-explicit) of each concept of rural traffic as well as obtaining information from different heterogeneous sources in an intuitive and simple way. Different aspects describe the actual problem related to the access and distribution of information: 1. High volume of traffic information is distributed over different web sites. The main problem for a user who needs such information is to find such webs and handle the different ways of access and presentation 2. On the other hand, the users need information of a different nature or type, and the storage of such information on a simple site would be too costly as well for maintenance. 3. It is no possible to obtain any information if this information is not explicit before, After defining the existing problems and identifying the elements which could solve this situation, the present work focuses on those ITS-systems which provide traffic information to the user, its handling and exchange, in an efficient way between the elements which compose the architecture of traffic information systems, such as users applications and information providers. Different elements have been developed as an integral part of an architecture: 1. Construction of an ontological infrastructure which domain is covered by road traffic information, 2. A framework was defined for the conversion of conventional web portals to semantic web services (SWS), 3. Extension of the existing methodology for the construction of ontologies based on ER model, 4. A SWS matching algorithm was designed, implemented and evaluated which make maximal use of the capabilities of the ontologies of the service description, which constitute an improvement of the existing ones. 5. A number of proposals were demonstrated which permits creation and handling of Semantic web services of road traffic information

O hidroxeodía en Galicia

[Resumo] O Hidroxeodía é unha xornada de divulgación da hidroxeoloxía e da profesión do hidroxeólogo organizada simultaneamente en hasta 20 provincias españolas por entidades locais coa colaboración do Grupo Español da Asociación Internacional de Hidrogeólogos (AIH-GE) e do Instituto Geológico y Minero de España (IGME). A actividade consiste nunha excursión ou itinerario hidroxeolóxico no que pode participar todo tipo de público, visitando algunha zona que mostre o papel das augas subterráneas e a necesidade de aplicar técnicas hidroxeolóxicas para diagnosticar e corrixir problemas. O grupo de investigación AQUATERRA da Universidade da Coruña organizou a xornada en Galicia durante os tres últimos anos coa colaboración doutras entidades. En 2017 e 2018 a xornada consistiu nun recorrido polo Concello de Abegondo (A Coruña) no que se presentou a hidroxeoloxía da zona e as accións demostrativas de deseño e mantemento das traídas veciñais e construción axeitada de pozos. En 2019, impartiuse unha formación básica en hidroxeoloxía dirixida ás xuntas de augas das traídas veciñais da provincia de Pontevedra e realizouse unha visita aos mananciais das traídas do Concello de Tomiño (Pontevedra). A actividade tivo un éxito crecente nos últimos anos e está a resultar moi satisfactoria para os participantes e a organización.[Abstract] The Hidrogeodía (hydrogeoday) is an activity for the dissemination of hydrogeology and the hydrogeologist profession organized simultaneously in up to 20 Spanish provinces by local entities in collaboration with the Spanish Group of the International Association of Hydrogeologists (AIH-GE) and the Spanish Geological and Mining Institute (IGME). The activity consists of a hydrogeological journey for any kind of public, visiting some area which illustrates the relevance of groundwater on the ecosystems and the hydrogeological techniques to identify and deal with groundwater scarcity or pollution issues. The AQUATERRA research team of the University of A Coruña have organized the activity in Galicia for the last three years in collaboration with other entities. In 2017 and 2018, it consisted of a visit to Abegondo (A Coruña) introducing the hydrogeology of the area and presenting the demonstrative actions of rural water supplies design and maintenance and appropriate well construction. In 2019, an introductory talk to hydrogeology was given to the boards of directors of the rural water supplies of Pontevedra and the springs of the rural supply of Tomiño (Pontevedra) were visited. This dissemination activity has been a growing success in the last years and it is being very satisfying for the attendees and the organization