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ETUDE DE L’INFLUENCE DES PARAMETRES GEOMETRIQUES SUR LE COMPORTEMENT STRUCTUREL DES TUBES EN ACIER FORMES A FROID SOUMIS A DES SOLLICITATIONS MECANIQUES
(2026) DAOUD AMINA; SAIAH MAMA; DJELIL M.
This work focuses on the study of the local buckling behavior of cold-formed thin profiles with
irregular octagonal tubular cross-sections (IOctHS). Thanks to their unique geometric characteristics,
these sections represent a promising alternative to conventional profiles due to their potential for
improving structural performance. However, their complex geometry significantly influences their
behavior with respect to local instability phenomena. The study involves the analysis of 124 sections
subjected to various types of loading. Particular attention is paid to evaluating the local buckling
coefficients associated with each loading case in order to: (i) better understand the influence of
geometric parameters on the local buckling behavior of the studied sections; and (ii) propose
analytical expressions for determining the critical local load, an essential parameter for evaluating the
strength of cold-formed profiles using the direct strength method. Given the geometric complexity of
IOctHS sections, conventional analytical formulations do not allow for sufficiently accurate
estimation of the local buckling coefficients. A numerical approach was therefore adopted, based on
calculating the critical loads of the cross-section using the CUFSM software. This tool relies on the
classical finite strip method as well as the constrained finite strip method, allowing for the
identification and differentiation of the various instability modes, particularly the local mode. It also
offers a detailed evaluation of the elastic stability behavior of thin profiles, explicitly taking into
account the interaction between the section geometry and the constituent walls. The results obtained
highlight the influence of different loading conditions on the local buckling behavior of IOctHS
sections and contribute to a better understanding of their structural response. They also provide a
practical basis for the design of this new generation of cold-formed profiles.
Decentralized Authentication based on Artificial Intelligence and Blockchain for Internet of Things Environments
(2026) BENADLA CHAIMAA; BACHIR NOUR EL IMANE CHAIMAÂ; MEDEDJEL MANSOUR
La croissance rapide des écosystèmes de l’IoT soulève des défis majeurs en matière d’authentification, d’évolutivité et
de détection des menaces en temps réel, car les architectures centralisées traditionnelles restent vulnérables aux points
de défaillance uniques et à la compromission des identifiants. Ce mémoire propose un framework hybride décentralisé
combinant une gestion des identités basée sur la blockchain et une détection d’anomalies pilotée par l’IA. Le système
s’articule autour d’une architecture à quatre couches comprenant des signatures ECDSA légères exécutées directement
sur les appareils IoT, une API Go à haute concurrence pour la vérification des preuves à divulgation nulle de connaissance
(ZKP), une blockchain Ethereum privée de type PoA (Proof-of-Authority) pour la gestion d’un registre immuable, et un
auto-encodeur BiLSTM pour l’analyse des menaces en temps réel. Une évaluation expérimentale menée sur des
déploiements à échelle variable de 20 à 200 appareils simulés démontre un taux de réussite d’authentification de 99 %
avec une latence de bout en bout comprise entre 4,9 et 13,3 secondes. Entraîné sur un ensemble de données complet
de 187 183 échantillons issus des ensembles IoT-23, CSE-CIC-IDS2018 et Bot-IoT, le modèle BiLSTM atteint un score F1
de 94,40 % (Precision = 95,28 %, Recall = 93,53 %, ROC-AUC= 0,9375), surpassant de 22,55 points de pourcentage un
modèle de référence « Isolation Forest ». Enfin, le framework démontre avec succès un mécanisme d’atténuation
automatisé en boucle fermée qui isole les appareils compromis en quelques secondes après la détection d’une anomalie.
L’impact de la saumure rejeté SUR L’écosystème marin
(2026) NEHARI .A; MEHADJI MOHAMED; NEHARI .A
Seawater desalination represents a strategic response to the growing freshwater scarcity in
Algeria. This thesis studies the diffusion of brine discharged from a seawater desalination
plant and proposes an optimised design for the discharge system (submarine outfall and
diffuser). The work is structured in four chapters: (I) environmental impact of brine on
Mediterranean coastal marine ecosystems — osmotic stress on Posidonia oceanica and
Cymodocea nodosa seagrass beds, residual chemical contaminant effects, long-term
biodiversity impacts; (II) brine management and valorisation strategies, from advanced
membrane technologies (HPRO, electrodialysis, membrane distillation) to the Zero Liquid
Discharge (ZLD) concept; (III) dispersion techniques — discharge pipelines, submarine
outfalls, inclined multiport diffusers, hydrodynamic modelling; (IV) in-depth case study of the
Chatt El Hilal plant at Beni Saf (200,000 m3/day, reverse osmosis) using CORMIX v.4.2GT
modelling, assessing the impact on Cymodocea nodosa meadows and validating the optimal
diffuser configuration (P1: depth 8 m, D3=1.07 m, v=3 m/s, inclination 45°, S max=1,707
mg/L < threshold 2,000 mg/L).
Influence du traitement des granulats biosourcés sur les caractéristiques générales d'un mortier écologique
(2026) Boudissa samah nihed; Attou Wafaa; ABDELHADI Houari
In the context of sustainable construction and the valorization of bio-based materials, this
study investigates the use of cork waste as lightweight aggregates in plaster mortars. The
main objective is to evaluate the influence of different pre-treatments applied to natural cork
aggregates on the physical, mechanical, thermal, and acoustic properties of plaster mortars,
with the aim of developing a more efficient and environmentally friendly building material.
Three pre-treatment methods were studied: hot-water treatment (T1), hornification treatment
(T2), and lime treatment (T3). Cork aggregates were used as a partial replacement for sand
at different substitution rates (0%, 25%, 50%, 75%, and 100%). Several tests were carried
out in both fresh and hardened states, including workability, bulk density, surface hardness,
ultrasonic pulse velocity, flexural and compressive strength, thermal conductivity, water
absorption, porosity, durability under wetting–drying cycles, and acoustic insulation.
The results showed that the incorporation of cork leads to a progressive decrease in mortar
density, producing lighter materials. It also significantly improves thermal insulation due to
the low thermal conductivity of cork. However, increasing the cork content results in higher
water absorption and porosity, accompanied by a reduction in mechanical strength. The
comparative analysis revealed that the hornification treatment (T2) provides the best
compromise between mechanical performance, durability, and fresh-state behavior, whereas
the lime treatment (T3) offers the best thermal insulation performance. Acoustic tests also
highlighted the potential of cork to improve sound insulation at specific frequencies.
This study confirms that plaster–cork mortars represent a promising eco-friendly solution
for the construction sector. The choice of cork pre-treatment makes it possible to tailor the
material properties according to the requirements of the intended application.
Contribution à l’étude de l’impact de l’agriculture intensive : Evaluation de l’effet des engrais et et pesticides sur la qualité du sol et de l’eau d’irrigation au niveau des exploitations agricoles
(2026) MAMMAR Kawtar; MILOUDI Marwa ikram; Aïssat Amal
Intensive agriculture in Algeria has experienced significant development to meet the growing
demand for agricultural products and to ensure food security. This intensification relies on
increased use of chemical fertilizers, pesticides, and modern irrigation techniques to improve
yields. However, excessive use of these chemical inputs can alter soil properties, affect its
fertility, and degrade the quality of irrigation waters, thereby compromising the sustainability
of natural resources.
In this context, the present study aims to assess the impact of intensive agricultural practices,
notably the use of fertilizers and pesticides, on the physico‐chemical quality of soil and
irrigation water in several farms within the Aïn Témouchent province.
The work is based first on a field survey of socio‐agronomic data carried out in April 2026 on
four farms located in the communes of Sidi Ben Adda and Chabat, complemented by
physico‐chemical analyses of soil and irrigation water samples.
The results show a predominance of tree crops in two farms, while the third is devoted to cereal
cultivation and market gardening, where a heavy reliance on chemical inputs is observed,
except for one farm where organic manure was used.
Pedological analyses reveal substantial variability in physical and chemical properties, with
organic matter contents ranging from 5.66% to 12.5%, slightly acidic pH values between 5.71
and 6.35, and electrical conductivity varying from 0.210 to 7.370 mS/cm, indicating contrasting
degrees of salinity. Soils S3 and S4 stand out for their higher organic and mineral richness,
favorable to greater biological activity. Concerning irrigation waters, analyses revealed variable
quality, characterized by heterogeneous salinity levels, variable amounts of suspended solids,
and an overall mildly alkaline pH.
Overall, this study highlights the influence of intensive agricultural practices on soil and
irrigation water quality, underscoring the need for more sustainable management of agricultural
inputs to preserve natural resources and the productivity of agroecosystems.