Publications Internationales
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Item Bacterial Population Kinetics and Physicochemical Profiles in Fermented Goat Milks: Roles of Streptococcus thermophiles ATCC19258 and Lactobacillus bulgaricus ATCC11842(National Nutrition and Food Technology Research Institute, 2025) Tayeb, Silarbi; Morsli, Amirouche; Saadia, Laabas; Mohamed, Chahbar; Khaled, Hamden; ben Salah-Abbes, JalilaBackground and Objective: The fermentation of Algerian goat milk, a process for the production of valuable dairy products, relies on the synergistic activity of Streptococcus (S.) thermophilus and Lactobacillus (L.) bulgaricus. However, a significant knowledge gap is seen regarding the precise dynamics of these starter cultures within the unique matrix of Algerian goat milks. Specifically, the intricate relationships between their growth patterns and the resulting physicochemical changes, which regulate the distinct biochemical characteristics of fermented products, are poorly understood. So, this study addressed this problem by studying specific contributions of S. thermophilus and L. bulgaricus to goat milk fermentation. Material and Methods: Goat milk was fermented by starter cultures of S. thermophilus and L. bulgaricus (8 h). Bacterial growth and physicochemical parameters, including pH, titratable acidity, viscosity and syneresis, were assessed. Mixed-effects models were used for statistical analysis to assess the relationship between physicochemical changes and bacterial growth. Results and Conclusion: The results showed a strong relationship between L. bulgaricus and the control of acidification, viscosity and syneresis (r = 0.979 for titratable acidity, p < 0.0001). S. thermophilus contributed significantly, particularly to the increases in viscosity (r = 0.773, p < 0.01). The two species significantly decreased the pH, with L. bulgaricus having twice the acidifying effects. By the end of the fermentation process, pH reached 4.12 ±0.20, titratable acidity increased to 84.75 ±2.19 °D and viscosity increased to 6425.00 mPa.s ±638.64. The final bacterial counts of S. thermophilus and L. bulgaricus were 519.00 ±115.29×10⁷ and 65.54±6.89×10⁷ CFU.ml-1, respect-ively. In addition to providing a robust statistical framework for process control and quality assurance in fermented milk manufacture, this study highlighted the critical role of L. bulgaricus in regulating structural and sensory qualities of fermented goat milks. Results can be used to optimize fermentation processes for goat milk by strategically manipulating the ratio of L. bulgaricus to S. thermophilus. The strong correlation between L. bulgaricus and acidification, viscosity and syneresis (r = 0.979 for titratable acidity, p<0.0001) provides a clear target for controlling key product attributesItem Predicting the viscosity of hydrogen – methane blends at high pressure for hydrogen transportation and geo-storage: Integration of robust white-box machine learning frameworks(Elsevier, 2025) Alatefi, Saad; Youcefi, Mohamed Riad; Amar, Menad Nait; Djema, HakimThe integration of hydrogen into underground storage systems is pivotal for large-scale energy management, often involving blends with methane to leverage existing infrastructure. Accurate viscosity prediction of hydrogen – methane blends under subsurface conditions is essential for optimizing flow assurance and operational safety. Accordingly, this study employs three data-driven models, namely Genetic Expression Programming (GEP), Group Method of Data Handling (GMDH), and Multi-Gene Genetic Programming (MGGP), to predict the viscosity of hydrogen – methane mixtures for transportation and underground storage applications. A comprehensive dataset of 313 experimentally measured values from the literature were utilized to develop and validate the established correlations. The MGGP paradigm emerged as the top performer, achieving a root mean square error (RMSE) of 0.4054 and an R2 value of 0.9940, outperforming both GEP and GMDH, as well as prior predictive models. The consistency of the dataset was confirmed using the Leverage approach, ensuring robust predictions. In addition, the Shapley Additive Explanations technique revealed key factors influencing the viscosity predictions, enhancing the interpretability of the best-performing correlation. Furthermore, comparative trend analysis demonstrated the MGGP correlation's superior accuracy and robustness across varying blend compositions and operational conditions. These findings offer a reliable and simple-to-use predictive correlation for engineers and researchers designing hydrogen transport and storage systems, supporting efficient energy storage and the transition to a low-carbon economyItem Maximizing enhanced oil recovery via oxidative cracking of crude oil: employing air injection and H2O2 with response surface methodology optimization(IOP publishing, 2024) Nouari, Omar; Hammadou née Mesdour, Souad; Boudjemaa, HamadaThe utilization of air injection as a method to enhance oil recovery in oil fields has gained prominence due to its cost-effectiveness and widespread availability, particularly in heavy oil production. This study focuses on optimizing the oxidative cracking process of Algerian crude oil by employing air injection supplemented with H2O2 and analyzing the interaction of key operating parameters like temperature and catalyst amount using response surface methodology. The predicted values derived from the response functions closely aligned with experimental data, demonstrating high accuracy (R2= 0.9727 for liquid oil, R2= 0.9176 for residue, and R2= 0.7399 for gas phases). Using the developed second-order model, optimal conditions were determined through contour and surface plots, as well as regression equation analysis using Design software. At these optimal parameters (14.78 wt% of H2O2, 2 l min−1 of air flow, 100 ml of crude oil at 354.05 °C for 40 min), the oxidative cracking process yielded 96.32% liquid oil, 3.018% residue, and 0.662% gas products. Notably, the experimental produced liquid oil constituted 96.07 vol. %, matching well with the optimization outcomes. Physicochemical analysis of liquid product phase obtained from oxidative cracking process of petroleum confirmed the prevalence of light aliphatic compounds(C2-C11) at 70.59%, alongside 29.41% of C12-C36. The process also resulted in reduced viscosity, density, refractive index, and sulfur content in the liquid phase. The combination of air injection and H2O2 showcases promise in recovering residual oil effectively and contributes to the ongoing advancements in EOR techniques.Item Using Machine Learning Algorithms for the Analysis and Modeling of the Rheological Properties of Algerian Crude Oils(Taylor and Francis Ltd., 2024) Souas, Farid; Oulebsir, RafikOur research described in this report investigated the rheological behavior of crude oils from the Tin Fouye Tabankort oil field in Southern Algeria, focusing on their viscosity under varying temperatures (10 °C–50 °C). The results show that the oils exhibited non-Newtonian shear-thinning behavior at low shear rates, with the viscosity decreasing as the temperature was increased. At higher shear rates, the Herschel–Bulkley model accurately described the oils’ transition to Newtonian behavior. Machine learning models, including CatBoost, LightGBM, and XGBoost, were trained on the experimental data to predict the viscosity, with CatBoost and XGBoost showing superior performance. We suggest these findings are valuable for improving the efficiency of oil transportation and processing.Item Viscosity-boosting effects of polymer additives in automotive lubricants(Springer Nature, 2024) Boussaid, Mohamed; Haddadine, Nabila; Benmounah, Abdelbaki; Dahal, Jiba; Bouslah, Naima; Benaboura, Ahmed; El-Shall, SamyThis study investigated polyethylene glycol (PEG), as a polymer improver of the paraffinic oil viscosity index (VI). The characterization of PEG/paraffinic oil blends at different concentrations (0%, 1%, 2%, 3%, 5%, and 10%), was performed using Raman spectroscopy and optical microscopy. The rheological parameters as the viscosity index and activation energy were determined using the kinematic viscosity measurements. Results showed that the VI improvement reached an optimal value for the blend containing 3% PEG, with greater value for blends containing 2% PEG than 5 and 10% PEG. The presence of polymer particles was observed by optical microscopy, which confirmed the lack of PEG distribution in the blend containing 5%, and more, whereas mixtures with 3 and 2% PEG exhibited good particle distribution, evidenced by smaller polymer particle sizes. This finding was corroborated by Raman spectroscopy, which revealed the absence of polymer–oil intermolecular interactions in the PEG/paraffinic oil blends. The rheological tests showed that increasing the blend temperature from 40 to 80 ℃, improved the PEG chains dispersion in the paraffin oil, for the blends containing up to 3% PEG. The difference of the activation energy of the pure paraffinic oil and the PEG/paraffinic oil blends, (ΔEa) was calculated, and the correlation between the ΔEa and the viscosity index values was established. Therefore, adding PEG to paraffinic oil appeared to be promising for the viscosity index improvement and promote industrial applications of paraffinic oil.Item RHEOLOGICAL AND MECHANICAL BEHAVIOR STUDY OF ECO-FRIENDLY CEMENT MORTAR MADE WITH MARBLE POWDER(University of Zielona Gora, 2024) Chahour, Kahina; Mechakra, Hamza; Safi, Brahim; Dehbi, Nacera-Melissa; Chaibet, CyliaThe work aim is to investigate the rheological and mechanical behavior of an eco-friendly mortar made with marble powder. Marble is have used as sand (total substitution of natural sand) and as an additional material (partial substitution of cement). Firstly, rheological tests were carried out on the cement pastes in order to study the effect of cement substitution by marble powder on the rheological behavior. Secondly, our study is devoted to evaluate the mechanical performances (flexural strength, compressive strength, mechanical behavior and ultrasonic pulse velocity) of a fluid mortar such as the case of the self-compacting mortars elaborated with the marble powder as an addition a material and as sand. The mechanical test results show that compressive strength and mechanical behavior of an ecological cement mortar made with marble waste as natural sand improved significantly. However, marble-based mortars with 100% of marble sand have given a mechanical strength similar to that obtained by control cement mortar (100% natural sand). It was also noted that it an ecological cement mortar made with 30% of marble powder as an addition a supplementary material can be obtained. This leads to a reduction in cement consumption and a reduction in CO2 gas emissions caused by cement production.Item Rheological behavior and microstructural properties of crude oil and emulsions (water/oil-oil/water)(Taylor & Francis, 2024) Yacine, Celia; Safri, Abdelhamid; Djemiat, Djamal Eddine; Benmounah, AbdelbakiAn experimental study on crude oil (from the Tin Fouye Tabankort oil field in southern Algeria) was carried out. This study allowed us to understand the rheological behavior of this crude oil with these different emulsions and how it reacts under the effects of temperature and the inversion of its phase from E/H to H/E. So we measured the rheological characteristics by tests flow and dynamic mode at different temperatures from 10 °C to 50 °C and at different water concentrations (20.40.50.60 and 70%) at a fixed temperature of 20 °C. The increase in temperature results in a 31.84% reduction in the initial viscosity of the crude oil. The addition of the volumic fractions of water results in an increase in viscosity at the point of inverse, which will decrease the apparent viscosity of these emulsions where the emulsions (W/O) come from (O/W). This crude oil and their emulsions exhibit a non-Newtonian behavior with shear thinning. The dynamic analysis depends on the temperature and the percentages of water added to the crude oil. At the end, a microscopic analysis was added to verify the relationship between the shape and diameter of the water droplets in each emulsion and the viscosity variation.Item An ecological water‑based drilling mud (WBM) with low cost: substitution of polymers by wood wastes(Springer, 2019) Haider, Soumia; Messaoud‑Boureghda, Mohamed‑Zine; Aknouche, Hamid; Akkouche, Ali; Hammadi, Larbi; Safi, BrahimAn ecologically friendly water-based drilling mud (WBM) was designed by using wood wastes (WP: wood powder) in order to substitute the organic polymers which are very expensive and often make the higher cost of the oil well drilling. This present work is dedicated on studying the rheological behavior and main rheological properties of WBM containing the wood powder at different contents and sizes by substitution of usually used polymers. The effect of wood powder on the drilling fluid filtrate was also analyzed. The drilling fluid that was developed has better rheological properties and fluid loss control which are required for a good functioning of oil well drilling. By a total substitution of polymers, the wood powder (300 μm at 850 kg/m3) can be used as a filtrate reducer of mud because the WBM filtrate obtained exhibits a minimum and having requested values for such formationItem Rheological behavior of oil sludge from Algerian refinery storage tanks(Elsevier, 2022) Souas, FaridRheological behavior of oil sludge from Algerian refinery storage tanks Farid Souas a, b, * a LEGHYD Laboratory, Faculty of Civil Engineering, University of Science and Technology Houari Boumediene (USTHB), Bab Ezzouar, Alger, Algeria b Research Unit Materials, Processes and Environment (UR-MPE), Faculty of Engineering Science, University M’Hamed Bougara, Boumerdes, Algeria a r t i c l e i n f o Article history: Received 15 August 2021 Received in revised form 20 December 2021 Accepted 28 January 2022 Available online xxx Keywords: Crude oil Rheology Sludge Storage tank Temperature Viscosity a b s t r a c t The consumption and demand for petroleum are increasing dramatically with the rapid development of industry and energy sector. As a result, petroleum refineries produce the greatest amount of oily sludge formed at the bottom of storage tanks during oil storage operations, which has a severely negative impact on the storage capacity and the operational safety of the storage tank. The present study focuses on the rheology of this complex fluid from Algerian crude oil storage tanks. Rheological measurements were performed at different temperatures under steady shear and dynamic oscillometry using AR-2000 Rheometer. The results obtained show that the sludge exhibits yield-pseudoplastic flow behavior at low shear rates, which is adequately described by the Herschel Bulkley model based on the standard error and correlation coefficient values. However, quasi-Newtonian flow behavior occurs at very high shear rates. The increase in temperature had positive effects on the rheological properties of the sludge, including dynamic viscosity, shear stress, yield stress, complex modulus, elastic modulus and viscous modulus. The dynamic rheology studies have shown that the sludge material behaves more like a solid than a liquid under all experimental conditions studiedItem Rheological behavior of cement-based grout with Algerian bentonite(Springer Nature, 2019) Benyounes, Khaledhe rheological parameters, yield stress, flow index, consistency, and plastic viscosity of cement grouts are important parameters for the quality control of these materials. These parameters are assessed from the rheogram using a rheo-logical model. Cement slurries without additive indicated a non-Newtonian type of rheological behaviour with yield stress. On the other hand, the mixtures containing a viscosifying agent exhibit a shear-thinning rheological behaviour which is much more important than the mixtures without a viscosifying agent. In this work, we formulated non-hydrated Algerian bentonite cement slurry in the presence of a superplasticizer. Cement was replaced cement by bentonite in five different substitution rates (2%, 4%, 6%, 8%, and 10%) and the water/binder ratio was fixed at 0.5. For this, various rheological tests were realized by using a controlled stress rheometer. In order to show the influence of bentonite on the rheological behaviour of the different grouts, several flow tests were carried out for a range of shear rates between 0.01 and 200 s−1. To properly adjust the different rheograms, various rheological models were used such as the models of Bingham, Herschel–Bulkley, modified Bingham, Casson, De Kee, Vom Berg, Yahia and Papanastasiou. For the correct choice of the rheological model, it was based on the calculation of the standard error. It was found that the rheological models of Herschel–Bulkley and Papanastasiou made it possible to better describe the flow curves compared to the other rheological models. It has been found that as the content of bentonite increases, the yield stress and the consistency evolve drastically, by cons the flow index decreases progressively