An efficient algorithm for overlapping bubbles segmentation

Image processing is an effective method for characterizing various two-phase gas/liquid flow systems. However, bubbly flows at a high void fraction impose significant challenges such as diverse bubble shapes and sizes, large overlapping bubble clusters occurrence, as well as out-of-focus bubbles. This study describes an efficient multi-level image processing algorithm for highly overlapping bubbles recognition. The proposed approach performs mainly in three steps: overlapping bubbles classification, contour segmentation and arcs grouping for bubble reconstruction. In the first step, we classify bubbles in the image into a solitary bubble and overlapping bubbles. The purpose of the second step is overlapping bubbles segmentation. This step is performed in two subsequent steps: at first, we classify bubble clusters into touching and communicating bubbles. Then, the boundaries of communicating bubbles are split into segments based on concave point extraction. The last step in our algorithm addresses segments grouping to merge all contour segments that belong to the same bubble and circle/ellipse fitting to reconstruct the missing part of each bubble. An application of the proposed technique to computer generated and high-speed real air bubble images is used to assess our algorithm. The developed method provides an accurate and computationally effective way for overlapping bubbles segmentation. The accuracy rate of well segmented bubbles we achieved is greater than 90 % in all cases. Moreover, a computation time equal to 12 seconds for a typical image (1 Mpx, 150 overlapping bubbles) is reached

GPU acceleration of edge detection algorithm based on local variance and integral image: application to air bubbles boundaries extraction

Accurate detection of air bubbles boundaries is of crucial importance in determining the performance and in the study of various gas/liquid two-phase flow systems. The main goal of this Accurate detection of air bubbles boundaries is of crucial importance in determining the performance and in the study of various gas/liquid two-phase flow systems. The main goal of this Accurate detection of air bubbles boundaries is of crucial importance in determining the performance and in the study of various gas/liquid two-phase flow systems. The main goal of this work is edge extraction of air bubbles rising in two-phase flow in real-time. To accomplish this, a fast algorithm based on local variance is improved and accelerated on the GPU to detect bubble contour. The proposed method is robust against changes of intensity contrast of edges and capable of giving high detection responses on low contrast edges. This algorithm is performed in two steps: in the first step, the local variance of each pixel is computed based on integral image, and then the resulting contours are thinned to generate the final edge map. We have implemented our algorithm on an NVIDIA GTX 780 GPU. The parallel implementation of our algorithm gives a speedup factor equal to 17x for high resolution images (1024×1024 pixels) compared to the serial implementation. Also, quantitative and qualitative assessments of our algorithm versus the most common edge detection algorithms from the literature were performed. A remarkable performance in terms of results accuracy and computation time is achieved with our algorithm. work is edge extraction of air bubbles rising in two-phase flow in real-time. To accomplish this, a fast algorithm based on local variance is improved and accelerated on the GPU to detect bubble contour. The proposed method is robust against changes of intensity contrast of edges and capable of giving high detection responses on low contrast edges. This algorithm is performed in two steps: in the first step, the local variance of each pixel is computed based on integral image, and then the resulting contours are thinned to generate the final edge map. We have implemented our algorithm on an NVIDIA GTX 780 GPU. The parallel implementation of our algorithm gives a speedup factor equal to 17x for high resolution images (1024×1024 pixels) compared to the serial implementation. Also, quantitative and qualitative assessments of our algorithm versus the most common edge detection algorithms from the literature were performed. A remarkable performance in terms of results accuracy and computation time is achieved with our algorithm. work is edge extraction of air bubbles rising in two-phase flow in real-time. To accomplish this, a fast algorithm based on local variance is improved and accelerated on the GPU to detect bubble contour. The proposed method is robust against changes of intensity contrast of edges and capable of giving high detection responses on low contrast edges. This algorithm is performed in two steps: in the first step, the local variance of each pixel is computed based on integral image, and then the resulting contours are thinned to generate the final edge map. We have implemented our algorithm on an NVIDIA GTX 780 GPU. The parallel implementation of our algorithm gives a speedup factor equal to 17x for high resolution images (1024×1024 pixels) compared to the serial implementation. Also, quantitative and qualitative assessments of our algorithm versus the most common edge detection algorithms from the literature were performed. A remarkable performance in terms of results accuracy and computation time is achieved with our algorithm

Caractérisation des évolutions spatio temporelles des instabilités de Kelvin-Helmholtz dans un jet rond

International audienc

In-situ biogas upgrading by bio-methanation with an innovative membrane bioreactor combining sludge filtration and H2 injection

International audienceA bioreactor using membrane technologies was used to demonstrate the feasibility of in-situ bio-methanation coupled to industrial wastewater treatment for biogas upgrading. High biogas productivity (1.7 Nm 3 Biogas/m 3 Bioreactor/day) with high CH4 content (97.9%) was reached. In-situ bio-methanation did not affect the COD removal efficiency of anerobic digestion (>94%). Process resilience has been tested for both substrate overload and H2 intermittence injection. Recovery of high CH4 content after 7 days without H2 injection occurred within few hours. Influence of microbial community has been studied showing that both hydrogenotrophic and homoacetogenic-acetoclastic pathways were involved

Développement d’un nouveau procédé membranaire pour la purification in-situ du biogaz par méthanation biologique

International audienceUn bioréacteur continu de 150 L utilisant des technologies membranaires a été conçu dans le cadre du projet METHAGRID (ADEME Graine 2017) pour démontrer les performance d’un procédé innovant de méthanation biologique. La technologie permet de convertir in situ en biométhane, le biogaz produit par méthanisation d’eaux usées industrielles alimentées en continu. Elle repose sur la concentration de la flore méthanogène naturelle, issus d’un méthaniseur agricole, par filtration membranaire du digestat en continu, et l’injection de H2 et CO2 via des contacteurs membranaires.Une productivité élevée en biogaz (1,7 Nm3Biogaz/m3Bioréacteur/jour) avec une teneur élevée en CH4 (97,9 %) a été atteinte. La méthanation in situ n'a pas affecté l'efficacité d'élimination de la DCO de la digestion anaérobie (>94%). La résilience du procédé a été testée à la fois pour la surcharge en substrat organique fermentescible et l'injection intermittente de H2. Après 7 jours sans injection de H2, le procédé a été capable d’atteindre de nouveau une teneur élevée en CH4 (>97%) seulement quelques heures après la réinjection de H2. L'influence de la communauté microbienne a été étudiée, montrant que les voies hydrogénotrophes et homoacétogènes-acétoclastiques étaient toutes deux impliquées

Procédé de méthanation de l'hydrogène H2 et du dioxyde de carbone CO2, ou de l'hydrogène H2 et du monoxyde de carbone CO en vue de la production de méthane CH4

L'invention concerne un procédé de méthanation de dihydrogène Ha et d'un gaz (CO2 ou CO), en vue de la production de CH4 dans un bioréacteur (1) comprenant un milieu réactionnel (2), contenant un substrat liquide (3) avec des matières organiques et une flore microbienne catalysant une réaction de méthanation, dans lequel : a) On alimente ledit bioréacteur avec ledit substrat; b) On filtre ledit milieu au travers d'une membrane (4) pour retenir la flore microbienne active et des macromolécules de grande taille, et on évacue un digestat (5); c) On injecte au sein dudit milieu au moins un premier gaz (7), H2 ou en syngas et, optionnellement, un deuxième gaz, CO, CO2 ou biogaz, l'injection dudit au moins un gaz (7) dans le milieu étant effectuée à une pression P1 supérieure à la pression limite PI de formation des bulles dudit au moins gaz dans un liquide

A regionally based precision medicine implementation initiative in North Africa:The PerMediNA consortium

International audiencePrecision Medicine is being increasingly used in the developed world to improve health care. While several Precision Medicine (PM) initiatives have been launched worldwide, their implementations have proven to be more challenging particularly in low- and middle-income countries. To address this issue, the “Personalized Medicine in North Africa” initiative (PerMediNA) was launched in three North African countries namely Tunisia, Algeria and Morocco. PerMediNA is coordinated by Institut Pasteur de Tunis together with the French Ministry for Europe and Foreign Affairs, with the support of Institut Pasteur in France. The project is carried out along with Institut Pasteur d’Algérie and Institut Pasteur du Maroc in collaboration with national and international leading institutions in the field of PM including Institut Gustave Roussy in Paris. PerMediNA aims to assess the readiness level of PM implementation in North Africa, to strengthen PM infrastructure, to provide workforce training, to generate genomic data on North African populations, to implement cost effective, affordable and sustainable genetic testing for cancer patients and to inform policy makers on how to translate research knowledge into health products and services. Gender equity and involvement of young scientists in this implementation process are other key goals of the PerMediNA project.In this paper, we are describing PerMediNA as the first PM implementation initiative in North Africa. Such initiatives contribute significantly in shortening existing health disparities and inequities between developed and developing countries and accelerate access to innovative treatments for global health