Dynamic modelling of the behaviour of the quarkiss earthen dam under seismic loads

The dynamic modelling of the behaviour of the Ouarkiss earthen dam under seismic loads was performed using the finite elements method (FEM), with an approach in effective stresses. The soil behaviour is described by the Mohr-Coulomb criterion. A numerical method and a procedure of analysis are presented in this work. The seismic response of an earthen dam was evaluated. Particular emphasis is placed on the calculation of stresses, displacements, deformations and interstitial overpressures recorded during the seismic solicitation. It has been shown that numerical simulation is able to highlight the fundamental aspects of the displacements and deformations processes experienced by the structure ofdam and to produce preliminary results for the evaluation of the seismic behaviour of the structure taking into account the physical non-linearity of the materials constituting the body of the dam and the effect of the rigidity of the different zones of the dam and the foundation

Effecs of damage by wheat bug, Aelia germari [Hemiptera : Pentatomidae], on grain quality and on reproductive performance of the rice weevil, Sitophilus oryzae [Coleoptera : curculionidae]

La punaise des céréales, Aelia germari, cause des dégâts au champ, avant la maturité du grain, qui ont pour conséquence majeure une réduction de la valeur boulangère du blé destiné à la panification. Pour tenter de mettre en évidence les modifications induites par les attaques de punaises sur la valeur nutritive du grain, un essai biologique a été réalisé sur le charançon du riz Sitophilus oryzae, qui se développe dans l'endosperme du grain. Le charançon du riz a été élevé sur des échantillons de blé du cultivar 'Manondemias', dans lesquels ont été incorporés des taux différents (0, 4, 8, et 13%) de grain attaqué par la punaise phytophage A. germari. Sur les échantillons de blé punaisé à 4, 8 ou 13%, la durée moyenne de développement de S. oryzae était plus courte que sur le grain non punaisé. Cependant, le calcul des corrélations sur les variables prises deux à deux a montré que ni l'indice de sensibilité Dobie aux attaques d'insectes, ni la descendance par femelle de charançon, ni la perte de poids du grain consécutive au développement complet de S. oryzae, n'étaient corrélés avec le pourcentage de grains punaisés dans l'échantillon. À partir d'une analyse multivariable globale, associant les propriétés physicochimiques ou rhéologiques des grains avec les paramètres décrivant la réponse biologique du charançon S. oryzae, il a été montré que le blé sans attaque apparente de punaise pouvait être associé à une longue durée de développement pour S. oryzae, un nombre plus faible de descendants, une force boulangère, une teneur en azote et un temps de chute élevés, ainsi qu'à une faible teneur en cendres et en azote assimilable du grain.The wheat bug, Aelia germari, feeds on developing wheat kernels, causing a loss in baking quality of the harvested wheat (Triticum aestivum). The possible nutritional changes in the bug-damaged kernels after the harvest were tested in a bioassay using the rice weevil Sitophilus oryzae, which feeds on the kernel endosperm. The weevils were reared on baking wheat cultivar 'Manon demias', grown in Algeria, with different levels (0, 4, 8 and 13%) of wheat bug (A. germari) damaged kernels. Rice weevil reared on 4, 8 or 13% damaged wheat had a shorter development time than on wheat with no damage. However, pair-wise correlations showed that Dobie's index for susceptibility of grain for stored-products insect attack, number of progeny per female and kernel weight loss were not correlated with the percentage of damaged kernels. Using multivariate analysis, the general characteristics of high quality grain were associated with long development times for S. oryzae, low number of progeny, high baking strength, high falling number, high nitrogen, low ash content, and low assimilable nitrogen

NUMERICAL MODELING OF UNSTABLE FLOWS IN CONDUCTS WITH VARIABLE GEOMETRY

Changes in the system flow of a fluid in a conduct often cause sudden changes in pressure and give rise to so-called unstable flows. So, the study of the phenomenon of unstable flows aims to determine ifthe pressure in a system is within the prescribed limits, following a perturbation of the flow. In the objective of studying the rangeof a water hammer, an examination of variations in velocity or flow and pressure resulting from inappropriate operation of the hydraulic system is made. This study presents a numerical modeling of the phenomenon of instable flows in load conducts with variable geometries. The characteristic method is used to solve the governing equations. Thanks to the AFT Impulse industrial program, very interesting and very practical numerical resultsare obtainedto describe the phenomenon of instable flows inconducts with variable geometry. And to more illustrate the graphical presentation two cases are graphically overlay for each of the two types of models (slow closing and rapid closingof the valve)

Shale problems and water-based drilling fluid optimisation in the Hassi Messaoud Algerian oil field

Drilling fluid formulation and properties play a fundamental role in drilling operations. Clay minerals behave initially as a beneficial rheological adjuvant in drilling muds. Nevertheless, the contamination of oil reservoirs by clay minerals present in the drilled geological formation (shales) may generate major problems during drilling as plug formation. In this context, our study deals with the optimisation of drilling conditions in the Hassi Messaoud Algerian field. The mineralogical heterogeneity of this field is first discussed. The rheological and filtration characteristics of water-based muds with different polymer and electrolyte concentrations are investigated. The physical and chemical changes of both drilled formation and drilling fluid during the drilling process are studied. Therefore, depending on the clay present in the geological formation, an optimised drilling fluid system using a new filtration procedure is proposed. A good correlation is found between filtration/rheological properties and inhibition

A systemic approach of qualitative changes in the stored wheat ecosystem: prediction of deterioration risks in unsafe storage conditions in relation to relative humidity, infestation by Sitophilus oryzae (L.), and variety influence

A multidimensional laboratory trial was carried out to identify how key overall quality traits of different common wheat varieties change during storage, to understand their interactions in the process of deterioration, and finally to reveal underlying trends of critical storage conditions that may endanger grain quality. A large set of qualitative criteria were followed on grain batches of three wheat varieties with various qualities for food processing, which were stored for 160 d at 22-23°C, under two different relative humidities (r.h.), and with or without infestation by the rice weevil Sitophilus oryzae. All variables involved in quality components assessment were recorded at 42-d periods. From the Pearson’s product moment correlation matrix, it was observed that the quality traits that correlated significantly to biotic variables (insect and fungal species dynamics) were: moisture content, hL mass, seed viability, and fat acidity of extracted flour. The interactions between biotic deteriorative factors and qualitative trait changes revealed through principal component analysis (PCA) were significant between four factors explaining the major part of qualitative criteria variance: storage duration; moisture content; hidden infestation density; fungal contamination level. The rate of increase of insect population was significantly different among varieties. PCA revealed that the significant difference in qualitative deterioration pattern among the three varieties was not related to their hardness, but to a different r.h. affinity. The germination rate was the qualitative criteria the more early declining during storage. The technological properties of extracted flour from each variety were significantly affected only when insect density exceeded 1000 insects per kg, a situation only observed in hot-spots. This work highlighted the trends of variation in quality traits of wheat varieties when stored under critical conditions. It can be used in IPM approaches to predict the susceptibility of a wheat variety to insect and fungi damage during storage. Keywords: Common wheat, Variety, Qualitative change, Insect pest, Fungal spoilage, Multivariate analysi

NUMERICAL MODELING OF UNSTABLE FLOWS IN CONDUCTS WITH VARIABLE GEOMETRY

International audienceChanges in the system flow of a fluid in a conduct often cause sudden changes in pressure and give rise to so-called unstable flows. So, the study of the phenomenon of unstable flows aims to determine ifthe pressure in a system is within the prescribed limits, following a perturbation of the flow. In the objective of studying the rangeof a water hammer, an examination of variations in velocity or flow and pressure resulting from inappropriate operation of the hydraulic system is made. This study presents a numerical modeling of the phenomenon of instable flows in load conducts with variable geometries. The characteristic method is used to solve the governing equations. Thanks to the AFT Impulse industrial program, very interesting and very practical numerical resultsare obtainedto describe the phenomenon of instable flows inconducts with variable geometry. And to more illustrate the graphical presentation two cases are graphically overlay for each of the two types of models (slow closing and rapid closingof the valve)

Multivariate analysis of the temporal changes of fungal communities in unsafe storage conditions of some common wheat varieties in relation to relative humidity level and rice weevil infestation

Fungal colonization of stored grain bulks is a major threat for mycotoxin contamination and reduction in viability of grain when stored under unsafe conditions, e.g. under high r.h. and insect presence. An investigation was carried out to identify the trends of the changes in the fungal species communities during storage of wheat grain under these unsafe storage conditions. The distribution change of fungi genera was monitored on small grain samples of three wheat varieties with different kernel size and hardness (soft, medium-hard and hard), during 160 d storage at constant temperature of 22-23°C, at two r.h. levels, and with or without an infestation by the rice weevil . According to their behavioral differences related to grain water activity affinity, fungi genera were classified in three groups: i/ The hydrophilic group of field fungi (Fusarium, Geniculifera, Sepedonium, and Chrysogenum); ii/ The intermediate semi-xerophilic fungi (Alternaria, Mucor, Ulocladium, Epicoccum, and Arthrobotrys); iii/ The storage xerophilic fungi (Penicillium and Aspergillus). Temporal abundance of these three groups with grain storage time and condition was observed in weak relation with wheat variety and insect presence. The multivariate comparison of the different experimental situations revealed a difference in the susceptibility of varieties to fungal species colonization in close relationship with the final equilibrium level between ambient r.h. and grain moisture content which was observed variety-dependent. This difference was not related to grain hardness but rather to a different r.h. affinity. For one variety (Apache), the germination rate was declining more rapidly than for the two others with storage time. Any significant relation between sound and infested grain condition and the contamination rate by storage fungi could be found. The susceptibility of the three wheat varieties to critical storage conditions and fungal colonization may lead in one variety to a hot-spot formation.Keywords: Common wheat, Variety, Fungal microflora, Insect pest, Fungi abundance chang

Mechanical Behavior of the Extraction Mud Dam for Use in the Manufacture of CEB

The aim of this work is to study the mechanical behavior of the sediments extracted from the Koudiet Meddaouar, Timgad dam (Algeria), for a possible valorization in the field for building works in order to minimize this phenomenon which is currently a concern for the operators and the persons in charge of the mobilization of the water resources. This siltation therefore severely limits its storage capacity and consequently it’s operating life. The extraction of the sediments accumulated in the dam's reservoir is therefore imperative, on the pain of seeing it perish in the medium term. These sediments are, however, of great geotechnical and mechanical value. The results of the tests conducted in the laboratory have enabled us to identify the different sediments from a physical and geotechnical point of view In front of the difficulties noted in the control of the silting up of the dams in Algeria, a very important quantity of silt being deposited annually in the dams. In order to achieve our objective, different mixtures of silt with or without lime treatment, cement glass fibers and powdered fibers were studied for the possible manufacture of Compressed Earth Bricks (CEB). The results obtained show that some of the mixtures present very interesting results in the different tests (compression and bending), verifying the conditions of the standards in force and thus allowing their use in the field of the manufacture of building materials. Doi: 10.28991/cej-2021-03091759 Full Text: PD

NUMERICAL MODELING OF UNSTABLE FLOWS IN CONDUCTS WITH VARIABLE GEOMETRY

Changes in the system flow of a fluid in a conduct often cause sudden changes in pressure and give rise to so-called unstable flows. So, the study of the phenomenon of unstable flows aims to determine ifthe pressure in a system is within the prescribed limits, following a perturbation of the flow. In the objective of studying the rangeof a water hammer, an examination of variations in velocity or flow and pressure resulting from inappropriate operation of the hydraulic system is made. This study presents a numerical modeling of the phenomenon of instable flows in load conducts with variable geometries. The characteristic method is used to solve the governing equations. Thanks to the AFT Impulse industrial program, very interesting and very practical numerical resultsare obtainedto describe the phenomenon of instable flows inconducts with variable geometry. And to more illustrate the graphical presentation two cases are graphically overlay for each of the two types of models (slow closing and rapid closingof the valve)