Capacité portante des fondations sous charge inclinée par approche numérique

La capacité portante des fondations superficielles est l'un des domaines les plus importants des études dans l’ingénierie géotechnique. La plupart des études ont été effectuées sur le cas où la fondation est soumise à une charge verticale centrée. Alors que les fondations superficielles sont souvent soumises à des charges excentrées et/ou inclinées (moments de flexion et des efforts tranchants transmis par la superstructure). Toutefois, lorsque la fondation est soumise à une charge inclinée et/ou excentrée, sa stabilité devient un problème majeur en géotechnique. Cependant, les projets d’'installation de plates-formes pétrolières et gazières en mer a donné un intérêt important pour la compréhension du comportement ainsi que les mécanismes de rupture des fondations superficielles sous chargement incliné et/ou excentré, ce qui va conduire à l’amélioration des méthodes d’estimation de la capacité portante de ce type de fondations. Par ailleurs, le code de différences finies Flac a été utilisé dans cette thèse pour évaluer numériquement la capacité portante des fondations superficielles en utilisant une loi de comportement de Mohr Coulomb associée et non associée. Toutes fois l’analyse numérique a été effectuée en faisant varier plusieurs paramètres géométriques et mécaniques. Les résultats obtenus montrent que pour le cas d’une semelle reposant sur la surface libre du sable et soumise à un chargement vertical excentré, les valeurs des capacités portantes calculées en utilisant l’approche de la largeur effective de Meyerhof ont tendance à sous-estimer les capacités portantes notamment, quand les excentricités sont importantes. On note que sur la base des résultats obtenus par l'analyse numérique, une nouvelle conception est proposée pour la largeur effective. Pour le cas d’une semelle encastrée dans un sable et sous un chargement vertical excentré, la variation de facteur de réduction (RF) avec l'augmentation du rapport d'excentricité est parabolique, et tend à être linéaire avec l’augmentation de l’encastrement de la semelle. Pour le cas d’une semelle reposant sur la surface libre du sable et soumise à un chargement incliné centré, le facteur d'inclinaison dépend uniquement de l'angle d'inclinaison α. Les résultats de cette étude, ont fait l’objet d’une confrontation avec ceux de la littérature

Effect of the eccentric load on the bearing capacity of a strip footing founded on sand

The finite differences FLAC 2D software which allows to model all soil-structure interactions regardless of the difficulty of the problems is used to determine the bearing capacity and stress distribution under a rigid strip footing submitted to vertical centered and eccentric loads. The footing is set on a free surface of sand with no surcharge applied. The soil is assumed to be elastic – perfectly plastic following the Mohr–Coulomb failure criterion. The results of the present study show that the conception proposed by Meyerhof tends to underestimate the bearing capacity, especially for large eccentricities. The study proposes an expression of the effective width that gives reasonable bearing capacity values, even for large eccentricities

Peripheral vision by a real time 3D system for analysing dynamic scenes

Many applications in robotics need enhanced vision systems able to give a reliable 3D information of the focused objects in a dynamic scene context . In this paper we propose a complete system (including the conception of sensors, their disposition and th e information processing) for observing a scene in a peripheral way, this means that it will cover 360° of angle, and for evaluatin g the observed objects' distances .De nombreuses applications en robotique exigent des systèmes de vision de plus en plus performants permettant de restituer l'espace 3D observé le plus fidèlement possible et dans un contexte de scène dynamique. Dans cette contribution on propose un système complet temps réel (comprenant la conception des capteurs, leur disposition, et le traitement informatique de l'information) visant à observer une scène de façon périphérique, c'est à dire couvrant 360° d'angle, et à évaluer les distances des objets observés

OLSEN: An Object-Oriented Formalism for Information and Decision System Design

data Types (ASAT) [Guttag#78] [Jacquenet#86] [Liskov#87] so as to have efficient and simple proof techniques at our disposal. An ASAT enables us to express an entity behaviour in a high level formalism. For a given entity, an ASAT is a triple <W,S,A>, where W is a set of domains containing the domain of the entity values, S is a set of operations on the entity, and A is a set of equations (axioms and preconditions) on these operations, which determines the entities behaviour and the relationships between them. ASAT are automatically constructed from the entities automata, which are the result of the analysis stage. This automatic construction is realised by the algorithms [Nkongo#90] developed in our laboratory. 3.2.2.#Organization Specification It starts from the analysis of the "existing system", which results (inter alia) in the identification of actors and their functions and objectives. Specifying organisation consists in formally expressing identified objectives (in the "triple" ..

Cucumis sativus L. hydroethanolic extracts: chemical characterization, bioactive properties and application as functional ingredients

Dupla diplomação com a Universite Libre de Tunis (ULT)There is a huge diversity of natural resources with potential to be used as bioactive agents/ingredients, for example in the food industry, since one of the current hot topics is the development of functional foods. Cucumber (Cucumis sativus L.) belongs to the Cucurbitaceae family that also includes melon, watermelon and pumpkin. It is widely consumed in European countries; however, underutilized in African regions. This fruit is 95% constituted of water and a rich source of vitamins K, B1 and C, biotin, carotenoids, potassium, copper, magnesium, manganese, phosphorus, silica, triterpenoids, flavonoids and molybdenum, having also high amounts of pantothenic acid and fibers. Moreover, the different parts of cucumber (fruits, peels and seeds) have also been described as having several bioactivities, such as anti-inflammatory, antioxidant and antibacterial properties. Therefore, in this dissertation, it was intended to study C. sativus fruits (entire fruits, pulp, peel and seeds) in terms of nutritional and chemical composition, and to perform a screening of the bioactive properties of its hydroethanolic extracts. Moreover, the most promising extract was incorporated in dark chocolate to obtain a differentiated product with strong biological properties. The obtained results demonstrated that the seeds presented the highest content in organic acids and tocopherols, as well as a valuable nutritional profile, due to the presence of proteins and carbohydrates as the most abundant macronutrients. This part of the fruit also revealed the strongest antioxidant activity, antitumor, anti- inflammatory and antimicrobial activities, being the selected one for incorporation in the dark chocolate. The developed chocolate formulation presented an increase in the sugars content, namely duo to the presence of fructose and glucose, provided by the extract, since these sugars were not detected in the control chocolate. Moreover, by screening the presence of antioxidants, it was observed that the incorporated chocolate presented a significant increase in these molecules, and it was evident that these molecules are stable and present in a high concentration in the final product. Overall, it was possible to obtain a differentiated product with a significant increase in its biological effects, conjugating an ingredient that is rarely appreciated with a high-consumed foodstuff.Existe uma enorme diversidade de recursos naturais com potencial para serem utilizados como agentes/ingredientes bioativos, por exemplo, na indústria alimentar, uma vez que um dos tópicos atuais mais relevantes é o desenvolvimento de alimentos funcionais. O pepino (Cucumis sativus L.) pertence à família Cucurbitaceae, que inclui também o melão, a melancia e a abóbora. É amplamente consumido nos países europeus; no entanto, subutilizado nas regiões africanas. Cerca de 95% deste fruto é água, sendo também uma fonte rica em vitaminas (K, B1 e C), biotina, carotenoides, potássio, cobre, magnésio, manganês, fósforo, sílica, triterpenoides, flavonoides e molibdénio, assim como apresenta um elevado teor de ácido pantoténico e fibras. Além disso, as diferentes partes do pepino (polpa, cascas e sementes) também foram descritas como tendo várias bioatividades, como propriedades anti- inflamatórias, antioxidantes e antibacterianas. Nesta perspetiva, esta dissertação, focou-se no estudo do pepino e das suas diferentes partes (frutos inteiros, polpa, casca e sementes), quanto à sua composição nutricional e química. Foram ainda preparados extratos hidroetanólicos e avaliados quanto à capacidade bioativa. Dentre as amostras analisadas, o extrato mais promissor foi incorporado em chocolate negro, de forma a obter um produto diferenciado e com um aumento significativo nas suas propriedades. Os resultados obtidos demonstraram que as sementes apresentaram maiores conteúdos em ácidos orgânicos e tocoferóis, além de um perfil nutricional valioso, devido à presença de proteínas e hidratos de carbono como macronutrientes mais abundantes. Esta amostra foi também a que exerceu a maior capacidade bioativa, nos ensaios de atividade antioxidante, citotóxica, anti-inflamatória e antimicrobiana, tendo sido a amostra selecionada para incorporação no chocolate. O chocolate incorporado apresentou um aumento no teor de açúcares, devido à presença de frutose e glucose, proporcionadas pelo extrato, não tendo sido estes açúcares detetados no chocolate controlo. Pela análise dos antioxidantes presentes, observou-se que o chocolate incorporado apresentou um aumento significativo nessas moléculas, corroborando a integridade e a estabilidade no produto final. Em suma, foi possível obter um produto diferenciado com um aumento significativo dos seus efeitos biológicos, conjugando um ingrediente que raramente é apreciado com um alimento altamente consumido

Rare earth - Transition metal based intermetallics : structural, magnetic and magnetocaloric properties

Les composés intermétalliques à base de terres rares et de métaux de transition présentent des propriétés magnétiques intéressantes pour les applications technologiques (aimants permanents, enregistrement magnétique à haute densité, réfrigération magnétique…).Ce travail est dédié à l'étude des propriétés structurales, magnétiques et magnétocaloriques des composés Pr2Fe17 dérivant de la structure Th2Zn17. Les propriétés magnétiques intrinsèques recherchées pour des propriétés performantes de ces composés sont améliorées sous l'effet de la substitution (fer par aluminium et praséodyme par dysprosium) et/ou l'insertion d'un élément léger (carbone). Les nanomatériaux intermétalliques sont élaborés par broyage à haute énergie suivi de recuit, ce qui pourrait conduire à des phases hors équilibre thermodynamique. L'homogénéité des alliages a été systématiquement analysée par diffraction des rayons X suivi de l'affinement Rietveld et par microscopie électronique en transmission. Les résultats ont montré qu'on peut former la phase désirée monophasée en faisant un broyage suivi d'un recuit de 30 min au lieu d'un recuit de 7 jours pour les composés massifs. Ceci représente un gain de temps non négligeable. D'après les mesures magnétiques effectuées, tous les composés possèdent une transition de phase de second ordre. Leur température de Curie augmente avec le taux d'Al et de Dy alors que la variation d'entropie diminue légèrement. Par ailleurs, l'insertion d'atomes interstitiels tels que le carbone a été réalisée. On remarque une nette amélioration de la température de transition. Il ressort de cette étude que ces composés présentent un grand intérêt dans la recherche de futurs matériaux magnétocaloriques pour la réfrigération magnétique à température ambianteThe intermetallic compounds based on rare earth and transition metals present interesting magnetic properties for technological applications (permanent magnets, high density magnetic recording, magnetic refrigeration ...).This work is dedicated to the study of structural, magnetic and magnetocaloric of Pr2Fe17 compounds Th2Zn17-type structure. The intrinsic magnetic properties of these compounds are improved due to the substitution (iron and aluminum by praseodymium by dysprosium) and / or the insertion of a light element (carbon). Intermetallic nanomaterials are prepared by high energy milling and subsequent annealing, which could lead to non-equilibrium phases. The homogeneity of these alloys was checked by X-ray diffraction and by transmission electron microscopy. The results have showed that single-phase can be obtained by milling and annealed during 30 min instead of 7 days annealing for bulk compounds. This represents a considerable saving of time. From the magnetic measurements, all compounds exhibit a second order phase transition. Their Curie temperature increases with the rate of Al and Dy as the entropy change slightly decreases. Moreover, the insertion of interstitial atoms such as carbon was achieved. We notice a significant improvement of the transition temperature. It appears from this study that these compounds are of great interest in the search for future magnetocaloric materials for magnetic refrigeration at room temperatur

Data quality evaluation in an e-business environment : a survey

International audienceIndustrial databases and information systems are plagued by a plethora of quality issues especially in cooperative information systems under the use of external data files because of the lack of collaboration in internal integration processes of marketing and sales data which is still a biggest challenge facing businesses, and, above all, the lack of benchmarks and tools standardizing for the external files exchanges and handling. In fact, the quality of exchanged data is essential for developing service-based applications and correctly performing cooperative activities such in Business-to-Business (B-to-B) marketing operations where issues are no longer limited to individual erroneous records but also to the insufficiency of customer knowledge and files features when integrating external data files. In this paper, we describe data assessment methods needed to assess and maintain the quality of an e-business activity. The aim is to define the basis of a data quality assessment framework that is suitable for evaluating and enhancing an e-business information system

CoMod: An Abstractive Approach to Discourse Context Identification

Generative text summarization can condense large volumes of information into a concise summary. It helps users quickly grasp the main points of a text without having to read the entire document. Machine learning (ML) plays a pivotal role in this domain, offering significant advantages in information processing and comprehension. In this paper we present CoMod, an abstractive method for generating the context of a document, from its content and that of the referenced documents, if any. CoMod analyzes the intricate patterns and relationships within a document’s content, thereby extracting and inferring the underlying context. The context generation process involves using a word linearization process as well as a Markov model, specifically a Bigram model, to predict the likelihood of word sequences. The Markov model is trained on a corpus of text and used to generate coherent sentences based on the probabilities of transitioning from one word to another. Markov tables allows to adapt the generated context to a specific domain and can be built on the fly in CoMod. The approach was compared to other methods and demonstrated very encouraging capabilities by outperforming other approaches tested on the same datasets. It thus confirms the potential of generative methods in the field of automatic text summarization and their ability of leveraging the power of machine learning for context generation to revolutionize information management, boosting productivity, scalability and knowledge discovery in various domains