Analyse par approche numérique mésoscopique des propriétés mécaniques résiduelles du béton après un chargement de type fluage

International audience Les modèles existants pour estimer le fluage du béton basés sur une modélisation rhéologique, supposent généralement que le béton est un matériau homogène. Par conséquent les incompatibilités de déformations entre la pâte de ciment et les granulats lorsque le béton est soumis à un chargement de type fluage ne peuvent pas être prise en compte alors qu'elles peuvent être à l'origine d'une microfissuration. Ces microfissures peuvent entrainer une diminution du module d'élasticité et de la résistance du béton, et une augmentation de la quantité de déformation par fluage sous le même niveau de chargement. Cette augmentation des déformations de fluage peut être considérée comme la source de non linéarités avec le niveau de contrainte. Pour étudier l'influence de ces microfissures, un modèle visco-élastique-endommageable a été adopté pour le calcul de fluage en utilisant une technique de maillage mésoscopique. Les résultats montrent qu'une part importante des non linéarités peut être expliquée par les microfissurations liées aux incompatibilités de déformations et que l'approche mésoscopique permet de reproduire fidèlement des essais de fluage jusqu'à la rupture. </div

Security for Cloud Environment through Information Flow Properties Formalization with a First-Order Temporal Logic

The main slowdown of Cloud activity comes from the lack of reliable security. The on-demand security concept aims at delivering and enforcing the client's security requirements. In this paper, we present an approach, Information Flow Past Linear Time Logic (IF-PLTL), to specify how a system can support a large range of security properties. We present in this paper how to control those information flows from lower system events. We give complete details over IF-PLTL syntax and semantics. Furthermore, that logic enables to formalize a large set of security policies. Our approach is exemplified with the Chinese Wall commercial-related policy. Finally, we discuss the extension of IF-PLTL with dynamic relabeling to encompass more realistic situations through the dynamic domains isolation policy.La principale cause de ralentissement de l'adoption du Cloud est le manque de sécurité fiable. Le concept de sécurité à la demande est de déployer et d'appliquer les demandes de sécurité d'un client. Dans ce papier, nous présentons une approche, Information Flow Past Linear Time Logic (IF-PLTL), qui permet de spécifier comment un système peut supporter un large ensemble de propriétés de sécurité. Nous présentons dans ce papier comment ces flux d'information peuvent être contrôler en utilisant les événements systèmes de bas niveau. Nous donnons une description compléte de la syntaxe de IF-PLTL ainsi que sa sémantique. De plus, cette logique permet de formaliser un large ensemble de politiques de sécurité. Notre approche est illustrée par la politique de sécurité de la muraille de Chine orienté vers le monde commercial. Finalement, nous montrons comment nous avons étendu notre langage pour supporter la relabélisation dynamique qui permet de supporter la dynamicité inhérante des systèmes. Nous illustrons cette extension par la formalisation d'une propriété de sécurité pour l'isolation dynamique de domaines

A Dynamic End-to-End Security for Coordinating Multiple Protections within a Linux Desktop

Index Terms-end-to-end security, multi-domains, protection mechanisms, coordination, Linux. Abstract-Currently, application protection models are mostly static and independent. It means that the applications cannot handle multiple domains to manage accordingly the permissions for a given user request. Managing multiple domains is becoming a more and more common issue as desktop applications are growing in complexity to provide better-designed user interfaces. Today, protection systems are almost everywhere. Multiple systems of protection are available from the Linux kernel such as SELinux or PIGA-Protect to get a Mandatory Protection. Those systems provide a per-syscall validation process. Network protections are also available such as the IPtables firewalling mechanism. Protections for languages or frameworks also exist such as for Java or .NET. But, solutions are missing for coordinating the various mechanisms that protect different levels of the global information system. The purpose is to reuse and coordinate efficiently those different levels of protection in order to provide a end-to-end protection that manages dynamically multiple domains. Thus, the same host can support multiple domains for the user requests while providing a transparent endto-end security that protects against complex scenarios of attack. This paper describes an attempt to deliver such a system for controlling efficiently the user requests

Massive structure monitoring: relevance of surface strain measurement

Most of large civil engineering concrete structures have been instrumented for decades with embedded sensors. To prevent the eventual loss of data, complementary instrumentation of external surface has recently been deployed. This new instrumentation can take different forms but in all cases, to avoid damaging the structure, it will be only superficially anchored. Near the outer surfaces, thermo-hydro-mechanical concrete behaviour is more sensitive to varying environmental conditions than in the centre of the structures. Therefore, the strain measured near the outer surfaces is not identical to the strain measured by embedded sensors. Consequently the methods of classical physical-statistical analysis must be reviewed. Using a thermo-hydro-mechanical finite element modeling calibrated on a representative concrete and applied on a current part of a thick structure, this work confirms a dependence of strain on the depth. First results show that the depth impact affects both kinetic and amplitude strain

Method-specific Certification of Free Sugars and Starch/Glucose in Two Artificial Food Materials - BCR-644, BCR-645.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel

Coupling by means of strong discontinuity approach between crack opening and gas permeability for concrete

Due to industrial needs, one of the key issues nowadays is to develop numerical tools that are able to predict the leakage rate through a cracked concrete structure. This paper presents a validation of a numerical modelling of leakage rate through a mortar specimen in a splitting test versus experimental results. The mechanical state of the material is described by means of an enhanced non-local damage model which takes into account the stress state and provides a realistic damage field at failure. A semi discrete method based on a Strong Discontinuity (SD) approach is then considered to study the coupling between the mechanical state of the material and its permeability. This method consists in first determining the crack opening field in the crack surface, then coupling the permeability with the crack opening by means of a modified Poiseuille's law. The assessed crack openings given by the SD method is compared to Digital Image Correlation measurements. The comparison between the two shows that the assessed crack openings given by SD are in good agreement (the maximum relative error is less than 20%). The results of the coupling compared to experimental data show a good estimation of the structural permeability for high level of cracking. Moreover, for lower levels of cracking, low differences between numerical and experimental permeabilities are observed

Enforcing Security and Assurance Properties in Cloud Environment

International audienceBefore deploying their infrastructure (resources, data, communications, ...) on a Cloud computing platform, companies want to be sure that it will be properly secured. At deployment time, the company provides a security policy describing its security requirements through a set of properties. Once its infrastructure deployed, the company want to be assured that this policy is applied and enforced. But describing and enforcing security properties and getting strong evidences of it is a complex task. To address this issue, in [1], we have proposed a language that can be used to express both security and assurance properties on distributed resources. Then, we have shown how these global properties can be cut into a set of properties to be enforced locally. In this paper, we show how these local properties can be used to automatically configure security mechanisms. Our language is context-based which allows it to be easily adapted to any resource naming systems e.g., Linux and Android (with SELinux) or PostgreSQL. Moreover, by abstracting low-level functionalities (e.g., deny write to a file) through capabilities, our language remains independent from the security mechanisms. These capabilities can then be combined into security and assurance properties in order to provide high-level functionalities, such as confidentiality or integrity. Furthermore, we propose a global architecture that receives these properties and automatically configures the security and assurance mechanisms accordingly. Finally, we express the security and assurance policies of an industrial environment for a commercialized product and show how its security is enforced

Left hepatic lobe herniation through an incisional anterior abdominal wall hernia and right adrenal myelolipoma: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Herniation of the liver through an anterior abdominal wall hernia defect is rare. To the best of our knowledge, only three cases have been described in the literature.</p> <p>Case presentation</p> <p>A 70-year-old Mexican woman presented with a one-week history of right upper quadrant abdominal pain, nausea, vomiting, and jaundice to our Department of General Surgery. Her medical history included an open cholecystectomy from 20 years earlier and excessive weight. She presented with jaundice, abdominal distension with a midline surgical scar, right upper quadrant tenderness, and a large midline abdominal wall defect with dullness upon percussion and protrusion of a large, tender, and firm mass. The results of laboratory tests were suggestive of cholestasis. Ultrasound revealed choledocholithiasis. A computed tomography scan showed a protrusion of the left hepatic lobe through the anterior abdominal wall defect and a well-defined, soft tissue density lesion in the right adrenal topography. An endoscopic common bile duct stone extraction was unsuccessful. During surgery, the right adrenal tumor was resected first. The hernia was approached through a median supraumbilical incision; the totality of the left lobe was protruding through the abdominal wall defect, and once the lobe was reduced to its normal position, a common bile duct surgical exploration with multiple stone extraction was performed. Finally, the abdominal wall was reconstructed. Histopathology revealed an adrenal myelolipoma. Six months after the operation, our patient remains in good health.</p> <p>Conclusions</p> <p>The case of liver herniation through an incisional anterior abdominal wall hernia in this report represents, to the best of our knowledge, the fourth such case reported in the literature. The rarity of this medical entity makes it almost impossible to specifically describe predisposing risk factors for liver herniation. Obesity, the right adrenal myelolipoma mass effect, and the previous abdominal surgery are likely to have contributed to incisional hernia formation.</p

Integrated Proteomic and Transcriptomic Investigation of the Acetaminophen Toxicity in Liver Microfluidic Biochip

Microfluidic bioartificial organs allow the reproduction of in vivo-like properties such as cell culture in a 3D dynamical micro environment. In this work, we established a method and a protocol for performing a toxicogenomic analysis of HepG2/C3A cultivated in a microfluidic biochip. Transcriptomic and proteomic analyses have shown the induction of the NRF2 pathway and the related drug metabolism pathways when the HepG2/C3A cells were cultivated in the biochip. The induction of those pathways in the biochip enhanced the metabolism of the N-acetyl-p-aminophenol drug (acetaminophen-APAP) when compared to Petri cultures. Thus, we observed 50% growth inhibition of cell proliferation at 1 mM in the biochip, which appeared similar to human plasmatic toxic concentrations reported at 2 mM. The metabolic signature of APAP toxicity in the biochip showed similar biomarkers as those reported in vivo, such as the calcium homeostasis, lipid metabolism and reorganization of the cytoskeleton, at the transcriptome and proteome levels (which was not the case in Petri dishes). These results demonstrate a specific molecular signature for acetaminophen at transcriptomic and proteomic levels closed to situations found in vivo. Interestingly, a common component of the signature of the APAP molecule was identified in Petri and biochip cultures via the perturbations of the DNA replication and cell cycle. These findings provide an important insight into the use of microfluidic biochips as new tools in biomarker research in pharmaceutical drug studies and predictive toxicity investigations

Modelling of Short-Term Interactions Between Concrete Support and the Excavated Damage Zone Around Galleries Drilled in Callovo–Oxfordian Claystone

peer reviewedProduction of energy from nuclear power plants generates high-level radioactive nuclear waste, harmful during dozens of thousand years. Deep geological disposal of nuclear waste represents the most reliable solutions for its safe isolation. Confinement of radioactive wastes relies on the multi-barrier concept in which isolation is provided by a series of engineered (canister, backfill) and natural (host rock) barriers. Few underground research laboratories have been built all over the world to test and validate storage solutions. The underground drilling process of disposal drifts may generate cracks, fractures/strain localisation in shear bands within the rock surrounding the gallery especially in argillaceous rocks. These degradations affect the hydro-mechanical properties of the material, such as permeability, e.g. creating a preferential flow path for radionuclide migration. Hydraulic conductivity increase within this zone must remain limited to preserve the natural barrier. In addition galleries are currently reinforced by different types of concrete supports such as shotcrete and/or prefab elements. Their purpose is twofold: avoiding partial collapse of the tunnel during drilling operations and limiting convergence of the surrounding rock. Properties of both concrete and rock mass are time dependent, due to shotcrete hydration and hydromechanical couplings within the host rock. By the use of a hydro-mechanical coupled Finite Element Code with a Second Gradient regularization, this paper aims at investigating and predicting support and rock interactions (convergence, stress field). The effect of shotcrete hydration evolution, spraying time and use of compressible wedges is studied in order to determine their relative influence