A Thorough Analysis of the Engineering Solutions Deployed to Stop the Oil Spill Following the Deepwater Horizon Disaster

International audienceThe Deepwater Horizon drilling accident that occurred on 20 April 2010 was a two-fold catastrophe. The initial total loss of the drilling rig was followed by one of the worst environmental disasters in recent history. The four million barrels of oil that were released into the Gulf of Mexico continue to impact human activities in the area. The Macondo well incident (Mississippi Canyon 252-1, leased by BP as the primary operator) was the first deep subsea blowout in the history of the oil and gas industry, and both the United States’ government and the private sector were unprepared to deal with it. All of the safety system’s lines of defense failed and the response required multiple courses of actions to be taken to address an unprecedented situation. It was imperative to deliver the best engineering solutions under intense and ongoing pressure in a very harsh and highly stressful operational environment. In this paper we review the engineering solutions considered by the response teams. The first part of the paper gives a brief presentation of our approach to the case study. The second reviews post-blowout events, the initial organizational response and the discovery of leaks. The final part presents how the statement of the problem was developed by the organization and how the response was structured. We then analyse the engineering solutions and finally, show how the organization implemented these solutions to control the source of the spill, recover the effluent and seal the well. In conclusion, we provide an overview of the engineering work that was carried out and preview our forthcoming work. We assume that the response to the Deepwater Horizon oil spill was efficient from an operational point of view. Therefore, our findings will be used to develop a new approach to the analysis of major accidents and ultimately shape the design of a new set of disaster management guidelines

Protein kinase C and human uterine contractility

Abnormalities in uterine contractility are thought to contribute to several clinical problems, including preterm labor. A better understanding of the mechanisms controlling uterine activity would make it possible to propose more appropriate and effective management practices than those currently in use. Recent advances point to a role of the protein kinase C (PRKC) family in the regulation of uterine smooth muscle contraction at the end of pregnancy. In this review, we highlight recent work that explores the involvement of individual PRKC isoforms in cellular process, with an emphasis on the properties of PRKCZ isoform

Une métrique psychovisuelle d'évaluation de la qualité des images couleur intégrant les effets de masquage inter-canal

- Tout traitement appliqué sur des images numériques doit, au final, être validé par un processus de qualité. Dans le cadre de la compression des images, ce processus repose sur la mesure de la qualité de l'image reconstruite. Or, le recours à des études subjectives est très coûteux car fastidieux à mettre en oeuvre. Dès lors, de nombreuses métriques de qualité sont apparues avec pour principal objectif la corrélation avec le jugement humain. Dans ce papier, une métrique psychovisuelle de la qualité basée sur une décomposition en ondelettes et sur une mesure des effets de masquage intra et inter-bande est développée. Une étude des performances est réalisée en terme de corrélation et de robustesse au type d'images

Contribution des réseaux bayésiens à la gestion du risque de piraterie contre les champs pétroliers

International audienceCes dernières années, les attaques de pirates contre des navires ou des champs pétroliers n'ont cessé de se multiplier et de s'aggraver. Pour exemple, l'attaque contre la plate-forme pétrolière Exxon Mobil en 2010 au large du Nigeria s'est soldée par l'enlèvement de dix neuf membres d'équipage et la réduction de 45.000 barils de sa production pétrolière quotidienne ce qui a engendré une montée des prix à l'échelle internationale. Cet exemple est une parfaite illustration de la faiblesse actuelle des dispositifs d'anti-piraterie existants. Pour faire face à ce problème, le projet SARGOS propose un système innovant prenant en compte toute la chaine de traitement depuis la détection d'une menace potentielle jusqu'à la mise en oeuvre de la réaction. Pour réagir contre une attaque, il faut considérer de nombreux paramètres relatifs à la menace, la cible potentielle, les dispositifs de protection mis en place, les contraintes liées à l'environnement, etc. Pour gérer ces paramètres, les potentialités des réseaux bayésiens sont exploitées afin de définir les contre-mesures possibles ainsi que leur mode de gestion / In recent years, pirates attacks against ships or oil platforms have continued to multiply and get worse. For example, the attack against Exxon Mobil oil rig in 2010 off the coast of Nigeria has caused the removal of nineteen of the crew and the reduction of 45.000 barrels of daily oil production which resulted the rise in prices internationally. This example is a perfect illustration of current weaknesses of the existing anti-piracy systems. To address this problem, the SARGOS project proposes an innovative system taking account the whole processing chain from detection of a potential threat to the implementation of the reaction. To react against an attack, we should consider many parameters of the threat, the potential target, the existing protection tools, the environment constraints , etc. To manage these parameters, the potentials of Bayesian Networks are used to identify feasible counterattacks and their management

The Contribution of Bayesian Networks to Manage Risks of Maritime Piracy against Oil Offshore Fields

International audienceIn recent years pirate attacks against shipping and oil fields have continued to increase in quantity and severity. For example, the attack against the Exxon Mobil oil rig in 2010 off the coast of Nigeria ended in the kidnap of 19 crew members and a reduction in daily oil production of 45,000 barrels, which resulted in an international rise in the price of oil. This example is a perfect illustration of current weaknesses in existing anti-piracy systems. The SARGOS project proposes an innovative system to address this problem. It takes into account the entire threat treatment process; from the detection of a potential threat to implementation of the response. The response to an attack must take into account all of the many parameters related to the threat, the potential target, the available protection resources, environmental constraints, etc. To manage these parameters, the power of Bayesian networks is harnessed to identify potential countermeasures and the means to manage them

Fruit and pulp production of the African grape Lannea microcarpa Engl. & K. Krause from dry and humid Sudanian zone in Northern Bénin, West Africa

Lannea microcarpa, an Anacardiaceae species associated to croplands in West Africa is a multipurpose tree used in traditional medicine, human and animal feeding in Sudanian zone of Bénin. This study aimed at evaluating its fruits and pulp yield. Fruit and pulp production and dendrometric variables were collected on 21 and 27 trees respectively in dry and humid Sudanian zone. Data were analysed using two independents samples t-test and Pearson correlation to find out variation in production and relation between variables. Trees in dry Sudanian zone showed the largest crown. The number of fruit, fruit mass and pulp mass were highest in dry Sudanian zone. Also, trees with high diameter at 1.30 m above the ground had produced low number of grapes and fruit per grape. Pruning and debarking did not affect the fruit and pulp mass. In humid Sudanian zone, tree crown could be used as indicator of number of fruit per grape in the one hand and in other hand the number of tertiary branches could be used for fruit and pulp yield. This study highlighted that in northern Bénin, dry Sudanian zone could be preferable for L. microcarpa fruit and pulp production. The variations observed between zones deserve to be investigated.Keywords: Lannea microcarpa production, Humid and dry Sudanian zone, Bénin, West Africa

Simulation of continuous detonation in H2-O2 mixture using adaptive mesh refinement

The necessity to have a fine resolution within a large computational domain represents an important difficulty especially for 3D simulations. To cope with this problem, the method of Adaptive Mesh Refinement (AMR) can be used. This paper presents some simulations performed with an Euler solver integrated in an AMR code. Results obtained for a model problem of detonation propagation in a layer of stoichiometric H2-O2 mixture are used to evaluate the AMR code efficiency. Examples of 2D and 3D simulations of continuous detonation wave are presented

Silicon nanowires as negative electrode for lithium-ion microbatteries

International audienceThe increasingly demand on secondary batteries with higher specific energy densities requires the replace- ment of the actual electrode materials. With a very high theoretical capacity (4200 mAh g−1 ) at low voltage, silicon is presented as a very interesting potential candidate as negative electrode for lithium-ion micro- batteries. For the first time, the electrochemical lithium alloying/de-alloying process is proven to occur, respectively, at 0.15 V/0.45 V vs. Li+ /Li with Si nanowires (SiNWs, 200-300 nm in diameter) synthesized by chemical vapour deposition. This new three-dimensional architecture material is well suited to accom- modate the expected large volume expansion due to the reversible formation of Li-Si alloys. At present, stable capacity over ten to twenty cycles is demonstrated. The storage capacity is shown to increase with the growth temperature by a factor 3 as the temperature varies from 525 to 575 ◦ C. These results, showing an attractive working potential and large storage capacities, open up a new promising field of research

Controlled fabrication of patterned lateral porous alumina membranes

International audienceConfined lateral alumina templates are fabricated with different pore sizes by changing the acid electrolyte and the anodization voltage. The control of the number of pore rows down to one dimension is also achieved, by controlling the thickness of the starting aluminum film as well as the anodization voltage. We observe that the mechanism of pore formation in the lateral regime is very similar to that in the classical vertical situation

Factors associated with balance impairments amongst stroke survivors in northern Benin: A cross-sectional study

BACKGROUND: Balance impairment is the predominant risk factor for falls in stroke survivors. A fear of falling after stroke can contribute to sedentary lifestyles, increased disability and risk of recurrence, leading to poor quality of life. OBJECTIVE: To determine the frequency and factors associated with balance impairments amongst stroke survivors at the University Hospital of Parakou. METHOD: This cross-sectional study included adult stroke survivors. Stroke survivors after discharge were enrolled at the University Hospital of Parakou between 01 January 2020 and 30 September 2020. Balance impairments were measured by using the Berg Balance Scale (BBS), the Timed Up and Go (TUG) and the Get Up and Go (GUG) tests. RESULTS: A total of 54 stroke survivors were included, with a mean age of 58.37 ± 12.42 years and a male predominance of 68.52%. The mean BBS score was 36.87 ± 14.34 with a minimum and a maximum of 10 and 56, respectively. Thirteen (24.07%) had balance impairments (BBS score ≤ 20), 34 (62.96%) had a TUG score ≥ 14 s (abnormal), 9 (16.67%) presented a moderate risk of falling and 6 (11.11%) presented high risk of fall with the GUG test. Post-stroke duration (odds ratio [OR] = 0.04; 95% CI: 0.04-0.30; p < 0.01), severity of disability (OR = 8.33; 95% CI: 1.03-67.14; p = 0.03) and the number of physiotherapy sessions (OR = 0.18; 95% CI: 0.03-0.93; p = 0.02) were significantly associated with balance impairments. CONCLUSION: Our results showed that almost one quarter of stroke survivors after discharge at the University Hospital of Parakou had balance impairments. Post-stroke duration, severity of disability and the number of physiotherapy sessions were significantly associated with balance impairments. CLINICAL IMPLICATIONS: [AQ1] Balance should be regularly assessed in people post-stroke. Further studies should document the content of rehabilitation and any rehabilitative efforts to improve balance in people post-stroke in Benin