Numerical modeling of the effect of carbon dioxide sequestration on the rate of pressure solution creep in limestone: preliminary results.

When carbon dioxide (CO2) is injected into an aquifer or a depleted geological reservoir, its dissolution into solution results in acidification of the pore waters. As a consequence, the pore waters become more reactive, which leads to enhanced dissolution-precipitation processes and a modification of the mechanical and hydrological properties of the rock. This effect is especially important for limestones given that the solubility and reactivity of carbonates is strongly dependent on pH and the partial pressure of CO2. The main mechanism that couples dissolution, precipitation and rock matrix deformation is commonly referred to as intergranular pressure solution creep (IPS) or pervasive pressure solution creep (PSC). This process involves dissolution at intergranular grain contacts subject to elevated stress, diffusion of dissolved material in an intergranular fluid, and precipitation in pore spaces subject to lower stress. This leads to an overall and pervasive reduction in porosity due to both grain indentation and precipitation in pore spaces. The percolation of CO2-rich fluids may influence on-going compaction due to pressure solution and can therefore potentially affect the reservoir and its long-term CO2 storage capacity. We aim at quantifying this effect by using a 2D numerical model to study the coupling between dissolution-precipitation processes, local mass transfer, and deformation of the rock over long time scales. We show that high partial pressures of dissolved CO2 (up to 30 MPa) significantly increase the rates of compaction by a factor of 50 to 75, and also result in a concomitant decrease in the viscosity of the rock matrix

Low velocity impact modelling in laminate composite panels with discrete interface elements

A model enabling the detection of damages developing during a low velocity/low energy impact test on laminate composite panels has been elaborated. The ply model is composed of interface type elements to describe matrix cracks and volumic finite elements. This mesh device allows to respect the material orthotropy of the ply and accounts for the discontinuity experimentally observed. Afterwards delaminations are described with interfaces similar to the ones observed with matrix cracks and the coupling between these two damages are established. In the first step, simple stress criteria are used to drive these interface type elements in order to assess the relevance of model principle. Nevertheless, the well known problem of mesh sensitivity of these criteria prevents the use of this model for now as a predictive tool but rather as a qualitative tool. An experimental validation is carried out thanks to impact experimental tests performed by Aboissiere (2003) and a very good match has been found. However, this model could predictivelly be used and would allow to foresee an original method to detect delaminations during an experimental test. This modelling has been successfully tested experimentally and compared to a C-Scan ultrasonic investigation

Predictability of Volcano Eruption: lessons from a basaltic effusive volcano

Volcano eruption forecast remains a challenging and controversial problem despite the fact that data from volcano monitoring significantly increased in quantity and quality during the last decades.This study uses pattern recognition techniques to quantify the predictability of the 15 Piton de la Fournaise (PdlF) eruptions in the 1988-2001 period using increase of the daily seismicity rate as a precursor. Lead time of this prediction is a few days to weeks. Using the daily seismicity rate, we formulate a simple prediction rule, use it for retrospective prediction of the 15 eruptions,and test the prediction quality with error diagrams. The best prediction performance corresponds to averaging the daily seismicity rate over 5 days and issuing a prediction alarm for 5 days. 65% of the eruptions are predicted for an alarm duration less than 20% of the time considered. Even though this result is concomitant of a large number of false alarms, it is obtained with a crude counting of daily events that are available from most volcano observatoriesComment: 4 pages, 4 figure

A New NDT Method for the study of composite bonded repair

This paper deals with the non destructive analysis of bonded repaired CFRP laminates by means of an active Infrared Thermography (IT) approach. The challenging issue comes from the weak property contrast between parts of repaired assemblies (carbon-epoxy composites bonded by an epoxy glue) and thickness of the joint. A specific experimental device has been set up to strongly control tests conditions (heat load, boundary conditions) and be able to develop a physically consistent numerical model of the thermal problem. Comparison between measured and simulated surface temperature fields shows very good agreement regarding temporal and spatial evolutions and provides new solutions for the non destructive testing (NDT) of bonded repaired composites. Specially is investigated here the opportunity to incorporate relevant additives with specific infrared signatures into the adhesive to improve thermal contrast between different parts and thus to improve the defects detection

NDT-based design of joint material for the detection of bonding defects by infrared thermography

Non Destructive Testing (NDT) by active InfraRed Thermography (IRT) of bonded Carbon Fibers Reinforced Plastic (CFRP) laminates is a very challenging issue. Difficulties come from the weak contrast between the thermal properties of constitutive parts, the small thickness of the epoxy joint and also the depth of the bonded interface. The strategy considered in this work is to design a new joint material specially adapted to the NDT detection of bonding defects. Using a numerical model, it is suggested to reinforce the epoxy joint material with conductive boron nitride particles. Experimental investigation of defective assemblies confirms the interest of such approach through a clear improvement of the IRT defect detection capacity

Infrared signatures of bonded interfaces for the repair of primary structures in composite materials

This paper deals with the use of infrared thermography for the reliability evaluation of bonded repaired composite structures. To address such issue, the present work intends to characterize a heat flow load by inverse identification. In this way, a specific experimental bench is developed to carry out thermal tests under controlled conditions. Moreover, the FEMU technique is adopted to identify the heat flow amplitude by means of correlation between experimental and numerical surface temperature fields. Such procedure is used on metallics coupons to identify the heat flow and is validated on carbon fiber laminates with different lay up

Investigating acceptability of a training programme in precision medicine for frontline healthcare professionals: a mixed methods study.

BACKGROUND Precision Medicine offers tailored prevention, diagnosis, treatment and management to patients that considers genomics, lifestyle and environmental factors. If implementation of Precision Medicine is to advance, effective, focused upskilling of frontline healthcare professionals through quality continuing professional development is needed. This study reports on an evidence-based approach to needs assessment to investigate the current level of knowledge of Precision Medicine, acceptable content for training, the perceived potential of a more precision approach to patient care and motivation to participate in a training programme among pharmacists, advanced practice nurses and general practitioners. Investigating perceived needs can avoid a top-down approach and support a design that is fit for purpose to targeted professions. METHODS This study reports on 2 focus groups (n = 12) delivered in French and German with equal professional participation of the targeted professions. The research objectives were investigated in two phases. During the first phase, a literature review and expert consultations were conducted to develop a definition of PM, patient cases and content for training. In a second phase, these investigations were further explored using focus groups to investigate acceptable learning objectives, the potential of PM to relevant professions and motivation of participants. Quantitative investigations using rating scales and visual analogues were incorporated. The focus groups were audio recorded, transcribed by intelligent verbatim and translated to English. NVivo was used for data analysis and interpretation following a hybrid approach using the Framework Method and thematic analysis. The analytical framework, Implementation Science, was applied to organise and present research data. RESULTS Precision Medicine is considered a new topic area, largely unfamiliar to frontline healthcare professionals.. There was acceptance of a more precision approach to care among all participants with perceived positive implications for patients. Valuable insight was gathered on acceptable content and form for training. All participants expressed concerns on readiness within their professions which included an insufficient system infrastructure, a lack of time to attend needed training, a lack of clarity for use in practice and the time needed to build a support network. CONCLUSIONS A precision approach to patient care is on the horizon for health care professionals not only in hospital settings but also at the community level. Our results conclude that an adaptable and flexible training programme in PM is timely, contextually relevant and conducive to the needs of targeted health professions for successful implementation. A training programme in PM will require support across sectors and stakeholders, supporting insurance models, educated patients and integrated care supported by innovative technology. Implementation Science outcomes are a useful strategy towards design of an effective training programme that can have measurable impact in practice

Logical modelling of cellular decision processes with GINsim

International audienc