Beyond The Cloud, How Should Next Generation Utility Computing Infrastructures Be Designed?

To accommodate the ever-increasing demand for Utility Computing (UC) resources, while taking into account both energy and economical issues, the current trend consists in building larger and larger data centers in a few strategic locations. Although such an approach enables to cope with the actual demand while continuing to operate UC resources through centralized software system, it is far from delivering sustainable and efficient UC infrastructures. We claim that a disruptive change in UC infrastructures is required: UC resources should be managed differently, considering locality as a primary concern. We propose to leverage any facilities available through the Internet in order to deliver widely distributed UC platforms that can better match the geographical dispersal of users as well as the unending demand. Critical to the emergence of such locality-based UC (LUC) platforms is the availability of appropriate operating mechanisms. In this paper, we advocate the implementation of a unified system driving the use of resources at an unprecedented scale by turning a complex and diverse infrastructure into a collection of abstracted computing facilities that is both easy to operate and reliable. By deploying and using such a LUC Operating System on backbones, our ultimate vision is to make possible to host/operate a large part of the Internet by its internal structure itself: A scalable and nearly infinite set of resources delivered by any computing facilities forming the Internet, starting from the larger hubs operated by ISPs, government and academic institutions to any idle resources that may be provided by end-users. Unlike previous researches on distributed operating systems, we propose to consider virtual machines (VMs) instead of processes as the basic element. System virtualization offers several capabilities that increase the flexibility of resources management, allowing to investigate novel decentralized schemes.Afin de supporter la demande croissante de calcul utilitaire (UC) tout en prenant en compte les aspects énergétique et financier, la tendance actuelle consiste à construire des centres de données (ou centrales numériques) de plus en plus grands dans un nombre limité de lieux stratégiques. Cette approche permet sans aucun doute de satisfaire la demande tout en conservant une approche centralisée de la gestion de ces ressources mais elle reste loin de pouvoir fournir des infrastructures de calcul utilitaire efficaces et durables. Après avoir indiqué pourquoi cette tendance n'est pas appropriée, nous proposons au travers de ce rapport, une proposition radicalement différente. De notre point de vue, les ressources de calcul utilitaire doivent être gérées de manière à pouvoir prendre en compte la localité des demandes dès le départ. Pour ce faire, nous proposons de tirer parti de tous les équipements disponibles sur l'Internet afin de fournir des infrastructures de calcul utilitaire qui permettront de part leur distribution de prendre en compte plus efficacement la dispersion géographique des utilisateurs et leur demande toujours croissante. Un des aspects critique pour l'émergence de telles plates-formes de calcul utilitaire ''local'' (LUC) est la disponibilité de mécanismes de gestion appropriés. Dans la deuxième partie de ce document, nous défendons la mise en oeuvre d'un système unifié gérant l'utilisation des ressources à une échelle sans précédent en transformant une infrastructure complexe et hétérogène en une collection d'équipements virtualisés qui seront à la fois plus simples à gérer et plus sûrs. En déployant un système de type LUC sur les coeurs de réseau, notre vision ultime est de rendre possible l'hébergement et la gestion de l'Internet sur sa propre infrastructure interne: un ensemble de ressources extensible et quasiment infini fourni par n'importe quel équipement constituant l'Internet, partant des gros noeud réseaux gérés par les ISPs, les gouvernements et les institutions acadèmiques jusqu'à n'importe quelle ressource inactive fournie par les utilisateurs finaux. Contrairement aux approches précédentes appliquées aux systèmes distribués, nous proposons de considérer les machines virtuelles comme la granularité élémentaire du système (à la place des processus). La virtualisation système offre plusieurs fonctionnalités qui améliorent la flexibilité de la gestion de ressources, permettant l'étude de nouveaux schémas de décentralisation

Mixing downstream a 90° open channel junction

International audienc

Mapping territorial vulnerability to wildfires: A participative multi-criteria analysis

International audienceThe Mediterranean region is routinely affected by forest fires, with adverse consequences on ecological, infrastructural, and socioeconomic assets. In a context of climate change, it is crucial for fire prevention and suppression to be able to identify locations where assets are most at risk, due to environmental, physical or socioeconomic reasons. Besides, this knowledge needs to be developed together with operational services and field experts to ensure their application. So far, fire risk research has largely focused on fire behavior, effects, and model simulation. In this article, we show how the concept of vulnerability can provide a flexible and relevant framework for assessing fire risk and be evaluated using a spatial multicriteria decision analysis method (MCDA)-the Analytical Hierarchy Process (AHP)-based on both quantitative data and expert judgment gathered through a participative approach. We focus on SouthEastern France, a region characterized by high economic and environmental stakes and heavily affected by wildfires. We develop a series of spatialized indicators using ecological, land-use and sociodemographic data which we aggregate to produce vulnerability maps for three categories of assets: population, ecosystems and infrastructures. An ex-post workshop was organized with field experts to put both the approach and results into discussion. Results reveal significant differences in indicators' perceived contributions to risk and vulnerability and enable appraising the contribution of sociodemographic factors, often overlooked in the literature. We also reveal differences in spatial patterns across both vulnerability subcomponents and exposed assets, helping identify primary and secondary vulnerability hotspots and underlying drivers. Consideration of multiple subcomponents of risk and vulnerability may help local decision makers prioritize how and where measures should be implemented, while the use of MCDA favors experience and knowledge sharing and among stakeholders while providing a basis of discussion

Comparison of residual stresses obtained by the crack compliance method for parts produced by different metal additive manufacturing techniques and after friction stir processing

Metal additive manufacturing (AM) techniques are promising to build complex components in automotive, aerospace and biomedical industries. However, as built AM parts generally present residual stresses which may degrade the fatigue resistance of the material. Although the AM techniques have been substantially studied, few data about the residual stress level and distribution are available in literature. This paper presents residual stress measurements and analysis on the metal powder bed AM parts using the crack compliance method. Both electron beam melting (EBM) and selective laser melting (SLM) processes are investigated for two manufactured alloys, i.e., Ti6Al4V and AlSi10Mg. It is found that: (i) the EBM process results in negligible residual stresses; (ii) the SLM leads to compressive stresses in the middle, accompanied by tensile stresses at the bottom and the top of the built part; (iii) preheating the build platform in the SLM process significantly reduces the residual stresses and effectively mitigates the porosity. Moreover, we show that post-treatment by friction stir processing inverts the residual stress distribution compared to the SLM process while significantly reducing the porosity

Une nouvelle structure d'écoulement en bifurcation à surface libre

National audienceDividing flows have been widely studied. These special structures found in sewers are responsible for complex flows. The understanding of these complex flows is the basis to better manage pollutants transport and mixing in sewer systems. This paper describes two flow structures observed experimentally and numerically in the downstream lateral branch of a 90° open channel dividing flow. These structures are recirculation flows: a classical one (2D) and a helix-shaped one (3D). First, the numerical model has been validated, being confronted with experimental measurements of velocities and water depths for two reference cases. Then, a numerical campaign has been led in order to describe in detail these structures. For the two types of recirculation, the flow visualization, notably of the streamlines in 3D, shows quite different characteristics of exchange with the main flow. It should be the same for their influence on the operation in sewers.Les bifurcations sont des ouvrages spéciaux présents en réseau d'assainissement et qui sont le siège d'écoulements complexes qu'il est important de comprendre et de maîtriser afin de mieux appréhender le transport de polluants particulaires ou dissous. L'étude présentée dans cet article porte sur la description de deux structures différentes observées expérimentalement et numériquement dans la branche aval latérale d'une bifurcation à 90° à surface libre. Ces deux structures sont des recirculations, l'une classique (2D), l'autre en hélicoïde (3D). Après avoir validé le modèle numérique grâce aux données expérimentales de vitesse et hauteur, une campagne de simulations a été menée dans le but de bien décrire ces structures. La visualisation des lignes de courant en 3D montre que leurs caractéristiques d'échange avec l'écoulement principal dans chaque branche sont très différentes, comme devrait l'être ainsi leurs influences sur le fonctionnement du réseau

Influence of model geometric distortion in laboratory scale modelling of urban flooding

peer reviewedUrban flooding at the block- or district-level is characterized by comparatively larger horizontal length scales than vertical ones. Therefore, a number of laboratory experi-ments of urban flooding were based on geometrically distorted scale models. Here, we investigate the influence of model geometric distortion on the flow processes in two simple settings representative of urban flooding: a single prismatic street and a street junction. We specifically compare the upstream flow depths predicted from laboratory observations using different geometric distortions. The predicted upstream flow depths consistently decrease as the model geometric distortion is increased. The bias induced by model geometric distortion, estimated as the relative difference between predictions from distorted and undistorted models is of order of 15% and 7% for the prismatic street and the street junction, respectively. This difference may be attributed to a difference in the relative importance of frictional losses and local head losses in the two settings. The outcomes of the study provide valuable guidance for the design of laboratory models of urban flooding

A combined experimental and numerical strategy to assess the influence of model geometric distortion in laboratory scale modelling of urban flooding

Accurate modelling of urban flood hazard remains hampered by a lack of suitable validation data. In contrast with water marks and inundation extent, discharge partition in-between streets and flow fields are generally unknown, while they have a strong influence on flood risk (human destabilization, scour, contaminant transport). Laboratory experiments may provide a valuable complement to field data to achieve robust validation of flood hazard models. However, urban flooding is a multiscale phenomenon, with horizontal length scales (~ 103 m) are considerably larger than the vertical ones (~ 1 m). Therefore, recent experimental studies of urban flooding used geometrically distorted scale models, with a vertical scale factor smaller than the horizontal one. Though, little is known so far on the bias induced by model geometric distortion in the case of urban flooding. To address this issue, we have combined computational modelling with laboratory experiments. Based on 100+ numerical simulations, the bias induced by model geometric distortion on flow depth and discharge partition was found of the order of 10 %, which is not negligible compared to other uncertainties involved in urban flood hazard modelling. Moreover, when the geometric distortion is varied, the induced bias shows an intriguing non-monotonous evolution, which we could relate to a competition between frictional and secondary head losses. New tailored laboratory experiments are on-going on a “series” of laboratory scale models, i.e. several laboratory models representing the same urban layout at various scales. The outcomes of these experiments will make more robust the conclusions drawn from computational modelling

A Multicenter, Investigator-Blinded, Randomized Controlled Trial to Assess the Efficacy of Calf Neuromuscular Electrical Stimulation Program on Walking Performance in Peripheral Artery Disease: The ELECTRO-PAD Study Protocol

This paper describes a currently on-going multicenter, randomized controlled trial designed to assess the efficacy of calf neuromuscular electrical stimulation (NMES) on changes in maximal walking distance in people with lower extremity peripheral artery disease (PAD), compared with a non-intervention control-group. This study (NCT03795103) encompasses five participating centers in France. PAD participants with a predominant claudication at the calf level and a maximal treadmill walking distance ≤300 m are randomized into one of the two groups: NMES group or Control group. The NMES program consists of a 12-week program of electrical stimulations at the calf-muscle level. The primary outcome of the study is the change in maximal treadmill walking distance at 12 weeks. Main secondary outcomes include changes in the pain-free treadmill walking distance; 6 min total walking distance; global positioning system (GPS)-measured outdoor walking capacity; daily physical activity level by accelerometry; self-reported walking impairment; self-reported quality of life; ankle-brachial index; and skin microvascular function, both at the forearm and calf levels. Recruitment started in September 2019 and data collection is expected to end in November 2022. </p

Influence on surface characteristics of electron beam melting process (EBM) by varying the process parameters

The use of additive manufacturing processes keeps growing in aerospace and biomedical industry. Among the numerous existing technologies, the Electron Beam Melting process has advantages (good dimensional accuracy, fully dense parts) and disadvantages (powder handling, support structure, high surface roughness). Analyzes of the surface characteristics are interesting to get a better understanding of the EBM operations. But that kind of analyzes is not often found in the literature. The main goal of this study is to determine if it is possible to improve the surface roughness by modifying some parameters of the process (scan speed function, number of contours, order of contours, etc.) on samples with different thicknesses. The experimental work on the surface roughness leads to a statistical analysis of 586 measures of EBM simple geometry parts.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

High Fructose Diet inducing diabetes rapidly impacts olfactory epithelium and behavior in mice

indexation en coursInternational audienceType 2 Diabetes (T2D), a major public health issue reaching worldwide epidemic, has been correlated with lower olfactory abilities in humans. As olfaction represents a major component of feeding behavior, its alteration may have drastic consequences on feeding behaviors that may in turn aggravates T2D. In order to decipher the impact of T2D on the olfactory epithelium, we fed mice with a high fructose diet (HFruD) inducing early diabetic state in 4 to 8 weeks. After only 4 weeks of this diet, mice exhibited a dramatic decrease in olfactory behavioral capacities. Consistently, this decline in olfactory behavior was correlated to decreased electrophysiological responses of olfactory neurons recorded as a population and individually. Our results demonstrate that, in rodents, olfaction is modified by HFruD-induced diabetes. Functional, anatomical and behavioral changes occurred in the olfactory system at a very early stage of the disease