A Numerical Study of Plate Anchors Embedded in Sand

The work described in this thesis begins with an elastic analysis of ground anchors in which several assumptions were made. Some of these assumptions limited the applicability of the analysis but some useful insights into the stress distribution around ground anchors were obtained. However, a more realistic non-linear analysis was required before any definitive conclusion could be drawn. Finite element analysis appeared to be the most appropriate method. However, since the behaviour of sand is rather complex (dilatancy, softening) an appropriate stress-strain model was then necessary. After a review of several constitutive models for sands, Vermeer's model which has the merit of being relatively simple yet comprehensive, has been studied in detail. However, this model does not describe softening behaviour since this is not a material property of a continuum. For this reason among others, it was decided that little advantage would be gained by implementing the model into the finite element program. Instead, a simple linear elastic-perfectly plastic model based on the Mohr-Coulomb yield criterion was employed in the finite element analyses. The effects of soil properties, embedment depth and initial stress conditions were studied as well as the effects of sand inhomogeneity and test scale. Contours representing the stress distribution around the anchor and yield propagation during the loading history were plotted. This gave an insight into the progressive mechanism of failure occuring in the soil mass. The results from the finite element anlyses were based on the so-called 4 failure load concept which appeared to give satisfactory results for loose sands

Political attitudes and participation among young Arab workers:a comparison of formal and informal workers in five Arab countries

Informal employment has long been a feature of Arab economies and as such, better understanding of the political participation of informal workers is important, especially given their involvement in social uprisings, such as during the Arab Spring in 2011. This paper tests for the first time the impact of informality of labour on political participation in five Arab countries: Algeria, Egypt, Lebanon, Morocco, and Tunisia. By using the European Union’s 2015–2016 SAHWA survey and logistic regression models, we are able to show evidence of an association between political participation and informality through the negative impact of the latter on four indicators of political participation: affiliation to political parties/movements; frequency of participation in political activities; frequency of speaking about politics; and voting in elections. Furthermore, the paper confirms that age, gender and education are significant predictors of political participation in the countries analysed. We argue that these findings have relevant policy implications

Biofiltration du méthane issu de sites d'enfouissement sanitaire en présence de composés organiques volatils

Abstract : Global warming is a growing concern due to the increase in greenhouse gases (GHG) in the atmosphere. Methane (CH4) contributes to 11% of global GHG emissions and landfills generate 17% of global anthropogenic CH4 emissions. Biotechnologies such as biofiltration offer sustainable solutions for the biotreatment of CH4 (at concentrations lower than 5% v/v), although the presence of other pollutants such as volatile organic compounds (VOCs) in landfill gas (LFG) and low CH4 mass transfer issues need to be considered. Biofiltration of CH4 in complex mixtures with VOCs is yet to be fully understood, with further studies required to strengthen knowledge in this field. This study focuses on the simultaneous biofiltration of CH4 with two aromatic compounds, xylene (X) and ethylbenzene (EB), by studying the effect of operational parameter changes such as empty bed residence time (EBRT) and concentration of CH4, X and EB on biofiltration performances. First, a literature review discussing LFG emissions, conventional LFG abatement methods, the suitability of biotechnologies for LFG removal in old and small landfills, and the challenges and advantages of biofiltration for LFG were provided. Secondly, the simultaneous biofiltration of CH4 in the presence of either X or EB was carried out in inorganic packed bed biofilters (BFs) at an EBRT of 4.5 min at CH4 concentrations in the range of 1000-10000 ppmv and individual VOC concentrations between 200-500 ppmv. The study found that low concentrations of CH4 (2000-6000 ppmv) had a minor effect on the removal efficiency (RE) of the VOCs, with average RE remaining above 85% for VOCs at 200 ppmv. However, at higher CH4 concentrations i.e. 10000 ppmv, inhibition became apparent for both VOCs and CH4, reducing both their REs by 80%. Thirdly, a ternary mixture consisting of CH4, X and EB was treated in an inorganic based-bed BF for CH4 concentrations in the range of 1000-10000 ppmv and VOC concentrations varying from 200 to 600 ppmv. The study found that CH4-RE was 41% when its concentration was 2000 ppmv and the concentrations of X and EB were 200 ppmv, at an EBRT of 9 min. Similarly, X and EB-REs were 58% and 57% respectively, at the same concentrations but with a shorter EBRT of 4.5 min. The biodegradation of pollutants in the BF was found to be located at different sections. The highest CH4-RE was in the top section while X and EB-REs were highest in the middle section and were not affected by CH4 concentrations. In the third part of the study, an artificial neural network (ANNs) was used to predict the BF performance. The ANN models accurately predicted dynamic and pseudo-steady-state CH4 and VOCs-REs. The findings suggest the need for a large database to enhance ANN performance in simulating complex CH4 biofiltration kinetics. Overall, this study provides promising results and insights into the simultaneous biofiltration of CH4 with VOCs, highlighting the significance of pollutant concentrations and EBRT. The use of ANNs for performance prediction shows potential for industrial applications, saving time and costs associated with experimentations.Le réchauffement climatique est une préoccupation croissante en raison de l'augmentation des gaz à effet de serre (GES) dans l'atmosphère. Le méthane (CH4) contribue à 11% des émissions mondiales de GES et les sites d’enfouissement sanitaires (SES) génèrent 17% des émissions anthropiques mondiales de CH4. Les biotechnologies telles que la biofiltration offrent des solutions durables pour le traitement biologique du CH4 (à des concentrations inférieures à 5% v/v), bien que la présence d'autres polluants tels que les composés organiques volatils (COVs) dans le gaz des sites d’enfouissement (GSE) doit être prise en compte. La biofiltration du CH4 dans des mélanges complexes en présence de COVs nécessite des études supplémentaires pour renforcer les connaissances dans ce domaine. Cette étude se concentre sur la biofiltration simultanée du CH4 en présence de deux composés aromatiques, le xylène (X) et l'éthylbenzène (EB) ; l'effet des changements de paramètres opérationnels tels que le temps de séjour en fût vide (EBRT) et la concentration de CH4, de X et de l’EB sur les performances de la biofiltration a été étudiée. Tout d'abord, une revue de littérature a porté sur les émissions de GSE, les méthodes conventionnelles de réduction des GSE, l'adéquation des biotechnologies pour l'élimination des GES dans les anciens SES ou les SES de faible taille, ainsi que sur les défis et avantages de la biofiltration des GES. Ensuite, la biofiltration simultanée du CH4 en présence de X ou de l’EB a été effectuée dans des biofiltres à lit inorganique sous un EBRT de 4.5 minutes pour des concentrations de CH4 comprises entre 1000 et 10000 ppmv et des concentrations individuelles de COVs comprises entre 200 et 500 ppmv. L'étude a révélé que les faibles concentrations de CH4 (2000-6000 ppmv) avaient un effet mineur sur la conversion (RE) des COVs, avec une RE moyenne supérieure à 85% pour les COVs (concentration de 200 ppmv). Cependant, pour des concentrations de CH4 plus élevées, c'est-à-dire 10000 ppmv, une inhibition est apparue à la fois pour les COV et le CH4, réduisant leurs REs respectives de 80%. Ensuite, un mélange ternaire composé de CH4, de X et de l’EB a été traité dans un biofiltre à lit inorganique pour des concentrations de CH4 comprises entre 1000 et 10000 ppmv et des concentrations de COVs variant de 200 à 600 ppmv. L'étude a montré que la RE du CH4 était de 41% lorsque sa concentration était de 2000 ppmv et que les concentrations de X et EB étaient de 200 ppmv, sous un EBRT de 9 minutes. De même, les REs de X et EB étaient de 58% et 57% respectivement, pour des concentrations identiques mais avec un EBRT plus court de 4,5 minutes. La biodégradation des polluants était située dans différentes sections du biofiltre. La RE du CH4 était la plus élevée dans la section supérieure, tandis que les REs de X et de l’EB étaient les plus élevées dans la section intermédiaire et n'étaient pas affectées par les concentrations de CH4. Dans la troisième partie de l'étude, un réseau de neurones artificiels (RNA) a été utilisé pour prédire les performances du biofiltre. Les modèles de RNA ont prédit avec précision les REs dynamiques et pseudo-stationnaires du CH4 et des COVs. Les résultats suggèrent la nécessité d'une grande base de données pour améliorer les performances des RNAs dans la simulation de la cinétique de la biofiltration complexe du CH4. Dans l'ensemble, cette étude fournit des résultats prometteurs et des connaissances sur la biofiltration simultanée du CH4 en présence de COVs et met en évidence l'importance des concentrations de polluants et de l'EBRT. L'utilisation des RNAs pour la prédiction des performances montre un potentiel pour des applications industrielles, ce qui permettrait d'économiser du temps et des coûts liés aux expérimentations

Acute toxicity of Aristolochia longa L. of aqueous extract in mice

Aristolochia longa L. (Aristolochiaceae) is widely used to treat breast cancer in Algerian traditional medicine. The present study was conducted to investigate the effects of ingestion of aqueous extracts of different parts of the plant on liver and kidney functions in wistar albinos mice. Acute oral toxicity was performed to determine DL50, this toxicity was carried out by the oral administration in single doses of 0–12 g/kg for tubers aqueous extracts and 2 g/kg and 5 g/kg for aerial and fruit aqueous extract respectively.  General behavior, adverse effects and mortality were determined for up to 14 days. The animals were sacrificed and biochemical study was done. The acute oral toxicity result revealed that LD50 of the tubers and fruit aqueous extracts was respectively more than 12 g/kg and 5 g/kg, but DL50 of the aerial aqueous extract was at 5 g/kg. The result revealed also that liver and kidney function of different groups receiving high doses was affected as ASAT, ALAT, Urea, creatinine was significantly increased as compared to control group. Histological examination showed alterations of the renal parenchyma and the liver which is greater in animals treated with high dose. Thus, caution should be exercised with its usage. Keywords: Acute toxicity, Biochemical parameters, Histological examination Aristolochia longa L

Facial expression recognition via a jointly-learned dual-branch network

Human emotion recognition depends on facial expressions, and essentially on the extraction of relevant features. Accurate feature extraction is generally difficult due to the influence of external interference factors and the mislabelling of some datasets, such as the Fer2013 dataset. Deep learning approaches permit an automatic and intelligent feature extraction based on the input database. But, in the case of poor database distribution or insufficient diversity of database samples, extracted features will be negatively affected. Furthermore, one of the main challenges for efficient facial feature extraction and accurate facial expression recognition is the facial expression datasets, which are usually considerably small compared to other image datasets. To solve these problems, this paper proposes a new approach based on a dual-branch convolutional neural network for facial expression recognition, which is formed by three modules: The two first ones ensure features engineering stage by two branches, and features fusion and classification are performed by the third one. In the first branch, an improved convolutional part of the VGG network is used to benefit from its known robustness, the transfer learning technique with the EfficientNet network is applied in the second branch, to improve the quality of limited training samples in datasets. Finally, and in order to improve the recognition performance, a classification decision will be made based on the fusion of both branches’ feature maps. Based on the experimental results obtained on the Fer2013 and CK+ datasets, the proposed approach shows its superiority compared to several state-of-the-art results as well as using one model at a time. Those results are very competitive, especially for the CK+ dataset, for which the proposed dual branch model reaches an accuracy of 99.32, while for the FER-2013 dataset, the VGG-inspired CNN obtains an accuracy of 67.70, which is considered an acceptable accuracy, given the difficulty of the images of this dataset

A frictional contact problem with wear involving elastic-viscoplastic materials with damage and thermal effects

We consider a mathematical problem for quasistatic contact between a thermo-elastic-viscoplastic body with damage and an obstacle. The contact is frictional and bilateral with a moving rigid foundation which results in the wear of the contacting surface. We employ the thermo-elasticviscoplastic with damage constitutive law for the material. The damage of the material caused by elastic deformations. The evolution of the damage is described by an inclusion of parabolic type. The problem is formulated as a coupled system of an elliptic variational inequality for the displacement, a parabolic variational inequality for the damage and the heat equation for the temperature. We establish a variational formulation for the model and we prove the existence of a unique weak solution to the problem. The proof is based on a classical existence and uniqueness result on parabolic inequalities, differential equations and fixed point arguments

Ethnobotanical Study, Anatomical Study and Phytochemical Screening of Aristolochia longa L.

Aristolochia longa L. (Aristolochiaceae) is used in Algerian traditional medicine. The ethnobotanical study conducted in the region of Setif (East Algeria) has as an objective of evaluating the potential of the region of Aristolochia longa L. used in the treatment of different diseases. A questionnaire was used which consisted of the diseases treated by this plant, the part of the plant used in the treatment and how to use this plant. The survey targeted 100 people from the local population. We also evaluated the phytochemical composition of the aerial parts (stems and leaves), fruits and tubers. Our results showed that A. longa is widely used to treat several ailments such as cancer (43%), diabetes (17%), and treatment of wounds in cattle (12%), and intestinal and stomach diseases (9 and 7%), the most used part is tubers by 70%.Crushed tubers are commonly mixed with honey(44%), milk(24%), water (8%). Results of the phytochemical screening revealed that A. longa contained various bioactive compounds, including polyphenols, flavonoids, saponins, terpenoids, and Alkaloids. In addition, there is very little information concerning the anatomical and morphological structure of this species of Setif region (Algeria), a preliminary study on anatomy of this plant is therefore reported in this paper. These preliminary results could be used to justify the traditional use of this plant and their bioactive substances could be exploited for therapeutic purposes such as antioxidant, antimicrobial and anti-inflammatory, and may be considered as a promising source of new drugs for treating cancer. Keywords: Aristolochia longa L., ethnobotany Setif(Algeria), anatomical study of plant, phytochemical screening

Le systeme algerien de protection sociale : entre bismarckien et beveridgien

Les systèmes de protection sociale tels qu’ils sont connus aujourd’hui sont issus de l’évolution des systèmes bismarckien et beveridgien. Le premier basé sur le principe d’assurance a vu le jour en Allemagne en 1883, le second basé sur le principe d’assistance a été créé par Beveridge en Grande Bretagne en 1941. Ce dernier était financé principalement par l’impôt et avait comme objectif de couvrir la plus grande partie de la population contre les risques sociaux. Nous proposons dans notre travail de caractériser le système algérien de protection sociale à partir de ces deux types de systèmes. En Algérie, le système de sécurité sociale a été fondé en 1949 sur le principe de l’assurance. L'accès au système était destiné aux travailleurs en contre partie de prélèvements sur leurs salaires. Le système était corporatiste-conservateur (Esping Anderson, 1990) de doctrine bismarckienne. Il a vu plusieurs réformes de l’indépendance à nos jours. Des lois visant à étendre la couverture sociale à une plus large partie de la population ont été introduites dans le système. Pour atteindre cet objectif, les pouvoirs publics ont créé d’autres composantes dans le système de protection sociale à côté du système d’assurance en place depuis 1949. Cela donna un changement de nature du système algérien de protection sociale. Dans ce travail nous allons étudier le système algérien de protection sociale dans sa globalité et essayer de lui accorder selon son architecture institutio- nnelle actuelle un cadre doctrinal cohérent (les prestations résiduelles et la primauté accordée au marché et à la lutte contre la pauvreté ; les assurances sociales et la protection des catégories professionnelles ; les prestations universelles et la recherche de l’égalité). Cette grille de lecture permet d’identifier les traits d’un système national dans son ensemble et dégager les tendances lourdes de son évolution. Celles-ci ne peuvent être dégagées par des analyses sectorielles (maladie, vieillesse …etc.). Par ailleurs, sur le plan économique, le passage de l’économie planifiée à l’économie de marché et la difficulté pour l’Etat d’atteindre le plein emploi ont permis l’apparition de certaines formes d’activités informelles sur le marché du travail. 41,8% de la population occupée ne sont pas affiliés à la sécurité sociale (ONS1, 2014). Cette population ne s’acquitte pas de ses cotisations sociales, mais elle profite de la gratuité des soins d’où la partie universaliste du système algérien de protection sociale. Nous exploiterons les données de la comptabilité nationale pour évaluer les recettes du système de protection sociale en provenance du marché du travail (cotisations des travailleurs) et les recettes en provenance du budget de l’Etat. L’évolution de ces agrégats pourrait constituer un indicateur de la typologie du système algérien de protection sociale.Mots clés : Algérie, Protection sociale, Système Bismarckien, Système Beveridgien, Recettes de la sécurité sociale, Budget social de l’Etat