Moment-Frequency distribution as a constraint for hydro-mechanical modelling in fracture networks

International audienceShear re-activation of deep fractured rocks for EGS purposes is accompanied by microseismicity. From our numerical hydro-mechanical coupling in discrete fracture network models which incorporates stress drops with known amplitudes and neglects the influence of static stress changes, it happens that the moments of induced seismic events are scaling with the power 3 of the fracture size. It follows that the value of the slope of the moment-frequency diagram better known as the b'value obtained from numerical experiments correlates with the exponent of the power law distribution used for the fracture size generation. Our suggestion is therefore to use these diagrams for constraining the fracture network generation proces

A Smart Contract Architecture Framework for Successful Industrial Symbiosis Applications Using Blockchain Technology

Funding Information: Author acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via the project UIDB/00667/2020 (UNIDEMI). Publisher Copyright: © 2023 by the authors.Industrial Symbiosis (IS) involves a network of organizations that exchange energy, materials, and by-products to lower production costs, reduce environmental impact, and conserve natural resources. Despite over two decades of extensive research into IS, its benefits are well known, but implementation remains challenging. This paper proposes utilizing blockchain technology (BCT) to digitize IS, making it more secure and transparent. First, drivers and barriers of BCT implementation in IS are identified. A smart contract architecture framework using Hyperledger Fabric is then proposed using the constructed theoretical background and abductive method. Finally, the paper discusses how this framework supports the implementation of BCT in IS by addressing its drivers and attempting to overcome its barriers. It is a resource for those seeking a comprehensive grasp of the foundational elements necessary for constructing a successful IS blockchain design, which is adaptable to all types of IS network configurations.publishersversionpublishe

Towards an Integrated Conceptual Design Evaluation of Mechatronic Systems: The SysDICE Approach

National audienceMechatronic systems play a significant role in different types of industry, especially in trans- portation, aerospace, automotive and manufacturing. Although their multidisciplinary nature provides enormous functionalities, it is still one of the substantial challenges which frequently impede their design process. Notably, the conceptual design phase aggregates various engi- neering disciplines, project and business management fields, where different methods, modeling languages and software tools are applied. Therefore, an integrated environment is required to intimately engage the different domains together. This paper outlines a model-based research approach for an integrated conceptual design evaluation of mechatronic systems using SysML. Particularly, the state of the art is highlighted, most important challenges, remaining problems in this field and a novel solution is proposed, named SysDICE, combining model based system engineering and artificial intelligence techniques to support for achieving efficient design

Juegos catequísticos

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Role of temperature change in micro seismic activity during fluid injections in faulted and fractured zones. Part 1 : Updating the thermal modelling in a DFN model using a double media approach

3International audienceL'exploitation de l'énergie géothermique des zones de socles ou de failles pour la production d'électricité fait l'objet de nombreux programmes de recherches en Europe en particulier (site de Soultz sous Forêts en France, Bâle en Suisse) avec la création de quelques sites pilotes opérationnels (Landau, Allemagne). Ces projets ont des caractéristiques communes, en particulier la nécessité d'améliorer les performances hydrauliques du réservoir, pour pouvoir atteindre une productivité économique, et aussi la nécessité de ré-injecter à basse température le fluide produit après passage dans les échangeurs de surfaces. Le succès de la première étape, optimisation du réservoir, dépend de la compréhension des interactions hydrauliques-mécaniques qui se développent pendant les phases de stimulation et (re-)fracturation du système naturel, et qui sont en partie contrôlées par le contexte tectonique local. Cette étape est cruciale. Des micro-seismes de trop fortes magnitudes ont été induits à Bâle et le projet est définitivement arrété. L'évolution à long terme du dispositif dépendra davantage du comportement thermique de la boucle géothermale. Nous savons que la présence de fluides dans les réseaux poreux des roches et la circulation des fluides à plus grande échelle (failles) contrôle le champ de température dans les premiers kilomètres de la croûte. Notre but est d'anticiper sur l'impact que pourrait avoir le refroidissement du à une circulation fluide imposée le long de fractures (convection forcée) dans le cadre d'une mise en exploitation géothermique d'une portion de faille avec re-injection froide. Le sujet consistera donc en une modélisation des échanges thermiques entre la roche et le fluide injecté afin de coupler l'évolution thermique du système au comportement hydro-mécanique du modèle, dans un contexte de faille normale (graben du Rhin), l'impact du refroidissement des roches allant dans le sens d'un accroissement des ouvertures des fractures. Ce point nous semble particulièrement à propos pour le cas du Rift d'Asal, (Djibouti), car le mécanisme naturel de propagation des failles sur ces sites pourrait bien être lié à l'écoulement naturel des fluides (C. Doubre et G. Peltzer, 2007) . Les fractures seraient donc en permanence dans un état de stabilité mécanique critique, et des ruptures potentiellement importantes pourraient être déclanchées. Ce mécanisme est à l'étude pour les micro séismes récents enregistrés sur le site des Geysers (Californie), et qui se localisent au centre du réservoir, exploité avec réinjection depuis plusieurs dizaines d'années. Dans l'approche proposée, on considérera le milieu remplissant les fractures comme étant poreux, ces fractures pouvant s'assembler à plus grande échelle en réseau, pour constituer un modèle de portion de faille. La matrice rocheuse sera imperméable dans un premier temps. Les outils numériques existant au laboratoire seront adaptés et améliorés pour cette application. - Dans les équations de Darcy (qui décrivent l'écoulement) on tiendra compte de la variation de densité et de viscosité du fluide provoquée par les différences de température, et le transport de chaleur sera convectif dans les fractures, conductif dans la matrice rocheuse. La convection pourra donc être mixte (naturelle et forcée). - Le comportement mécanique suppose que le milieu formant la matrice est élastique, et que les déformations sont des glissements le long des plans des fractures, lorsque un critère de rupture est atteint. Une première partie de ce travail consistera, à évaluer ce critère pour représenter l'état naturel avant toutes mise en circulation de fluides dans le réservoir. La perturbation thermique due à la circulation forcée d'un fluide sera alors superposée, et la question de la stabilité ré-évaluée pour différents temps. - Les données proviendront des bases partagées dans le cadre du projet européen GEISER support de la recherche sur la période 2010-2013, et pourront à titre prospectif être utilisées pour discuter d'un nouveau projet en cours d'implantation le long du rift d'Asal (Djibouti)

Combining Scenario Workshops and Participatory System Dynamics Modelling to Study Food Security. A case study with farmers in Zambia

Food security, which affects mainly developing countries, is a worldwide problem that has called the attention of the economic, political and scientific community. Achieving food security is a very complex process that involves not only the ability of farming but also a constant adaptation to natural phenomena, as for example, rainfall patterns. Limited knowledge and access to information and technologies, restrict the capacity of local farming communities to achieve food security. Furthermore, there is a lack of suitable methods and tools for involving stakeholders, such as farmers, in the development and assessment of food policies and their long-term system-wide effects. The main goal of this research is to investigate how the use of mixed-methods – scenarios and participatory System Dynamics (SD) modelling – are capable of improving understanding and an integrative view of food systems, serving as a lever for supporting food security decision-making processes. Additionally, this research aims to answer the following two questions: i) How can scenarios and participatory SD be used together to study plausible futures of food security involving smallholder farmers in developing countries?; ii) What are the possible policy pathways to avoid undesirable situations and to stimulate desirable ones, in a context of subsidence farming in Sub-Saharan African countries?. For this specific purpose, a group of smallholder farmers in Zambia was analyzed as a case study. First, a workshop was implemented in which a scenario of poor rainfall and no government help was developed. In order to achieve food security, participants had to find policy proposals and pathways to avoid or to overcome this undesired scenario. Subsequently, from the scenario workshop data, causal loop diagrams (CLD) were built using a systematic coding process. The next steps were to analyse policy proposals through a cross-impact analysis and develop an outline of pathways to study the complementarity and compatibility of such proposals. The 11 policy proposals were Charcoal Business; Livestock Business; Groundnuts Business; Gardening; Loan; Piecework; Land (productive land); Rental Business; Partnership; Legislation for Deforestation/Afforestation; and, Retention Basins/Drilling Boreholes. Finally, it was possible to design an innovative Action Plan that shows the pathways and the pace at which each proposal may achieve food security. It was concluded that scenario workshop and participatory SD may tightly coupled since these methods complement each other, stimulating system thinking and co-creation of knowledge. Scenario workshops are a disruptive and exploratory method, as it allows to elicit creative and plausible images from participants. Participatory SD supports decision-making processes by analysing policy proposals and its pathways, leading to the elaboration of joint action plans. In the Zambian case, from the 11 plausible policy proposals, it was found that Piecework enables a swifter path to achieve food security, while Rental Business would be the slowest. Additionally, it was found that some of the policy proposals could be reinforced if implemented together, while others, such as Charcoal Business and Legislation for Deforestation/Afforestation, did not show such potential. A follow-up survey with workshop participants showed that they were following the Action Plan, confirming the preference for the short-term policy proposal pathways

Influence of geological parameters on CO2 storage prediction in deep saline aquifer at industrial scale

International audienceConsequences of uncertainties on geological parameters are examined using 2D models at large extension. Reduction of the uncertainties on predictions is also investigated, either because parameter's influence is negligible for the project design, or by showing for which parameters additional data will significantly increase the quality of prediction. TOUGH2/ECO2N is used to simulate the injection of millions tonnes of CO2 for the specific case of the Dogger aquifer (carbonates aquifer in the Paris Basin) with high lateral and vertical heterogeneities and for which few data are available. Studied parameters are spatial variability and correlation length of permeability, value of absolute permeability, pore compressibility, caprock permeability and relative permeability curves. Several numerical models of permeability are constructed: two uniform cases (two values of permeability) and 200 geostatistical initial realizations, which are modified according to the studied parameters. Results are compared in terms of propagation of pressure perturbations, injectivity (pressure in the vicinity of the well) and in terms of gas migration and dissolution. The results indicate, for the specific scale and values, that: (1) Pore compressibility, absolute value and spatial variability of permeability have the main influence on pressure propagation and injectivity. Relative permeability curves and correlation lengths have a weaker influence for the peak of pressure but tend to increase the variations for maximum/minimum cases. (2) Relative permeability curves and heterogeneities have a significant impact on prediction of gas dissolution and migration. At last, we also investigate the possibility to reduce the number of runs

How to Analyze Modeling Approach Comparison Criteria

National audienceOne possible final goal of defining a set of criteria to define modeling approaches [1] is to help people, especially from industry, picking up the good approaches or artifacts according to their own purpose. The authors of the comparison criteria have managed to get several different assessments made by defenders of particular modeling approaches. From our point of view the experiment is mature enough to support a factorial analysis of the criteria themselves. The goal of this paper is to present how such an analysis could be conducted and illustrate its usefulness. We have identified several key modeling concepts but we only focus in this document on the assessment of modeling approaches

Modeling and verification of Functional and Non-Functional Requirements of ambient Self-Adaptive Systems

International audienceSelf-Adaptive Systems modify their behavior at run-time in response to changing environmental conditions. For these systems, Non-Functional Requirements play an important role, and one has to identify as early as possible the requirements that are adaptable. We propose an integrated approach for modeling and verify- ing the requirements of Self-Adaptive Systems using Model Driven Engineering techniques. For this, we use Relax, which is a Requirements Engineering language which introduces flexibility in Non-Functional Require- ments. We then use the concepts of Goal-Oriented Requirements Engineering for eliciting and modeling the requirements of Self-Adaptive Systems. For properties verification, we use OMEGA2/IFx profile and toolset. We illustrate our proposed approach by applying it on an academic case study