Université de Béjaïa
  • Bejaïa, Bejaia , Algeria
Recent publications
In the present research, zeolite is used for the removal of toxic Congo red dye from water solution. The effects of different operating conditions such as hydrogen potential (pH), contact time (time), zeolite dose (D), initial dye concentration (C0), and ionic strength (I) are investigated for Congo red adsorption under batch mode. It was found that the adsorption process was greatly affected by the initial pH of the dye solution. The removal efficiency decreased from 97.68 to 5.22% when the pH varied from 3 to 5; thus, acidic conditions clearly improve Congo red adsorption on zeolite. At pH 3, an increase in C0 and I and decrease in D resulted in an increase in the adsorption capacity qe. The effects of these three parameters and their interactions were also investigated using the 2 3 full factorial design experiments approach where qe was chosen as the response. The results obtained from this method followed by the analysis of variance and the Student's t-test show that, the influence of these parameters on dye adsorption process are in the order I < C0 < D. The kinetic studies revealed that adsorption follows a pseudo-second-order kinetic model. The adsorption iso-therms experimental data were analyzed using the Langmuir, Freundlich, and Temkin isotherms models. The Freundlich isotherm was the best-fit model to the experimental data. The fitting of kinetics and isotherm models was evaluated by using non-linear modeling, R 2 , MSE, and RMSE.
The effect of hydroxyapatite (HAp) synthesized by the chemical precipitation process on the morphology and properties of composites based on poly(lactic acid) (PLA) was investigated at various filler content ratios, i.e., 5, 10 and 15 wt%. Both neat PLA and PLA-based composites were first prepared using the solvent casting method, followed by melt compounding in an internal mixer, whereas tensile specimens were obtained by thermo-compression. The study revealed that the addition of 5 wt% of HAp into the PLA led to a slight improvement in both the thermal stability and tensile properties of the composite material in comparison with neat PLA and other composite samples. Indeed, the values of the tensile strength and modulus increased from approximately 61 MPa and 2.9 GPa for the neat PLA to almost 64 MPa and 3.057 GPa for the composite sample, respectively. Moreover, the degradation temperature at a 5 wt% mass loss also increased by almost 5 °C compared to other samples, due probably to a finer dispersion of the HAp particles in the PLA, as observed under a scanning electron microscope. Furthermore, the FT-IR spectra displayed some changes in the chemical structure of the PLA/HAp (5 wt%), indicating the occurrence of filler-matrix interactions. At a higher filler content ratio, a decrease in the properties of the PLA/HAp composites was observed, being more pronounced at 15 wt%. The PLA composite containing 5 wt% HAp presents the best compromise among the investigated properties. The study highlighted the possibility of using HAp without any prior surface treatment as a reinforcement in PLA composite materials.
To mitigate the effect of earthquake on the structure, the base isolation technique is the best alternative as a seismic protection system. In this research, a two-degree-of-freedom (2DOF) equivalent model is modelled based on a real eight-level reinforced concrete structure damaged by the Boumerdes earthquake in 2003 is presented. The basic isolation systems considered are four models namely: the first system is a high damping isolator (HDBR), the second system is the friction pendulum isolator (FPS). The third model of the base isolation system is a non-linear model with two horizontal and rotational stiffness springs (SHRS), and finally the last model presents a bilinear spring (SB). The isolators are designed according to the UBC-97 code. Earthquake recordings from Dar-El-Beida of the 2003 Boumerdes earthquake were used as seismic load. A dynamic analysis of the comparative temporal responses of the structure was performed by comparing its dynamic behaviour with that of the fixed base structure. The results obtained reveal a reduction in base shear, stage drift and stage acceleration and an increase in displacement and time period for the structure isolated at the base. The results are presented in tables and graphs.
The use of Nigella seeds in the food, pharmaceutical, and cosmetic fields is common, since the iniquity and the virtues of these plants are directly related to their characteristic phytochemical composition. This investigation focused on the comparative study of the botanical aspect, phenolic profile, and in vitro and in vivo biological activities of Nigella sativa L. (NS) and Nigella damascena L. (ND) seeds. The macro- and micro-morphological properties of these seeds were studied, and the key dissimilarities between them were clearly illustrated. The phytochemical contents and phenolic profiles were determined, and the in vitro antioxidant activity was assessed using four methods. The in vivo antioxidant and biochemical parameters of the blood of supplemented mice were determined. The results of the macro- and micro-structure analysis revealed differences between the two plants. Here, ND is characterized by higher phytochemical contents and the best antioxidant activities. The HPLC analysis indicated the presence of nine compounds, namely seven phenolic acids, particularly hydroxybenzoic and caffeic acids, and two flavonoids. The administration of ND extract to mice for 21 days at a concentration of 500 mg/kg allowed a substantial amelioration of plasma antioxidant properties. In addition, the extracts ameliorate blood parameters (cholesterol, triglycerides, glycemia, and urea). Furthermore, the antimicrobial activity of extracts demonstrated their effects on Staphylococcus and Aspergillus. Nigella seeds, in particular ND, expressed considerable in vitro antioxidant properties and demonstrated significant amelioration of mice blood properties. Consequently, these species can serve as a valuable source of compounds with various applications.
One of the main causes of CO2 emissions is the production of electrical energy. Therefore, many researchers goal’s is to develop renewable power systems. This paper proposes a new intelligent control development of hybrid PV-Wind-Batteries. Neuro-Fuzzy Direct Power Control (NF-DPC) is invested in order to enhance system performance and generated currents quality. An improved MPPT algorithm based on Fuzzy Controller (FC) is invested for PV power optimization. In addition, a new Modified Fuzzy Direct Power Control (MF-DPC) is developed and applied to the grid side converter to control the active and reactive power by monitoring the involved active power flow and providing a unit power factor by imposing a zero reactive power. An Energy Management Algorithm (EMA) is developed to maintain energy balance, meet the DC load demand, mitigate fluctuations caused by weather condition variations (wind speed and solar irradiance), and minimize battery overcharge and deep discharge. To test the proposed hybrid microgrid system operation, the different parts of the system is modeled, the wind turbine associated to the DFIG, the photovoltaic system as well as the battery storage system. Furthermore, the associated power converters with their control strategies are also presented. Global system simulation, using MATLAB/Simulink, is carried out to validate the effectiveness of both EMA and control techniques. The obtained results show significant reduction of active/reactive power ripples and THD by about 64%, 72%, and 50%, respectively. The EMA ability to manage the energy flow, produced and requested by the load. The THD rate of all injected currents is less than 4%, meaning that the proposed controls will increase the used equipment's’ life span, minimize their maintenance and then reduce the hybrid power system cost.
There is a growing interest in raw earth as an eco-material of building for its local character and the low energy consumption that characterizes its overall life cycle. This work evaluates the effect of the recovery of two biomass ashes (WBAa, WBAb), resulting from domestic wood heating on the mechanical, thermal and durability properties of compressed earth bricks (BWBAa, BWBAb). These specimens were obtained in a partial substitution of a silty-clay soil by WBA, in various proportions (0, 5, 10, 15 and 20 wt%). The specimens manufactured were compacted with a compaction stress of 10 MPa, exposed to the open air and kept in the laboratory at a 20 ± 2 °C temperature, then allowed to harden for 7 and 28 days. The mechanical level strength increases with wood ash content and with curing time. BWBAb has the best flexural and compressive levels strength caused by formation of compounds with binding properties, but BWBAa shows good thermal insulation. Capillary water absorption test was performed to prevent the durability of the elaborated specimens under water action. These bricks showed different behaviors in contact with water based on the different microstructure present in the two ashes. The experimental study conducted highlighted the benefits of the high periclase (MgO) content on the mechanical properties and durability of compressed earthen bricks.
We introduce a generalisation of the Caputo fractional differential operator by replacing the Euler Gamma function in the basic operator with the generalised Gamma function. The generalised Caputo operator has a new degree of freedom (fractional parameter) that affects the dynamics of the model. The basic mathematical properties of the generalised Caputo operator are discussed. Then, we apply this generalised fractional operator to some predator–prey models, such as the fractional Hastings–Powell food chain model and the fractional generalised Lotka–Volterra model. The simulation results show that the two systems exhibit a variety of chaotic attractors when the new operator's parameter is varied.
The radiolytic method is used to synthesize ultra-small cobalt ferrite nanoparticles, CoFe2O4, exhibiting superparamagnetic properties. These systems are investigated by studying their properties at increasing dose of the irradiation process....
Adaptive reuse of heritage buildings is a viable option for giving them a second life because it is less expensive and energy efficient. However, to think of preserving a building without thinking about reviving its ambiances would be to preserve the envelope without the soul. Through the acoustic environment analysis, this research was conducted to determine the quality of historic building reconversion in Algeria. We've decided to concentrate on the acoustic environment in medieval Islamic structures. The library of the Kasbah in Bejaia was our choice. It was built in 1797 to serve as a mosque, although it has been altered numerous times since then. We carried out in-situ acoustic measurements and then distributed a closed questionnaire to three categories of people: users, staff members, and outsiders. The conversion of the mosque into a library was fraught with two significant issues. The first was technical: there was no acoustic study, resulting in a poor fit between absorbing and reflecting materials. The second was functional: there is no clear boundary between the reading room for readers and the workspace for staff members.
Several security tools have been described in recent times to assist security teams; however, the effectiveness and success remain limited to specific devices. Phishing is a type of cyberattack that uses fraudulent emails and websites to obtain personal information from unsuspecting users, such as passwords and credit card numbers. Hackers can gain access to your information through a variety of methods, and the most common of which are king, phishing, spear phishing, social engineering, and dictionary attacks. Each of these techniques is unique, but they all have the same goal: to obtain your personal information. Nevertheless, there is the potential to exploit this problem in terms of security. In this paper, we used the Bash Bunny (BB), a new tool designed to assist military, law enforcement, and penetration tester teams with their work to conduct exfiltration without privilege escalation through T1200, T1052, and T1052.001 techniques in air-gapped networks with effectiveness/success 99.706%.
Evaluating conjunctive queries (CQs) is NP-hard in general; however, acyclic CQs or nearest acyclic CQs can be evaluated in polynomial time. Many structural methods for characterising such classes are proposed in the literature. However, exploiting these methods to answer CQs is not efficient in practice when the relations have a realistic size. In this work, we propose a new method called HSJ-Solver for evaluating CQs and for solving constraint satisfaction problems (CSPs) represented by a generalised hypertree decomposition (GHD). Experiments carried out on CSP benchmarks show that using HSJ-Solver significantly improves the achieved performance.
In this paper, we study the endogenous formation of a joint lab in an oligopolistic market. We compare the situation where N firms choose their R&D efforts non-cooperatively and the situation where a subset of firms conduct their R&D through a partial joint lab. We show that the profits of the firms joining a lab increase with its size until a certain critical size. Beyond this critical size, the profits of the players decrease with the growth of the dimension of the lab. An important result yields that the socially optimum size of the lab is lower than the equilibrium size when the output spillover levels are sufficiently low such as applied research. The policy implications to this result suggest the intervention of public authorities to prohibit firms to form the grand joint lab or partial cooperations that can emerge spontaneously but are detrimental to social welfare through the strengthening of antitrust laws.
Small-scale photovoltaic (PV) power systems have been proven to be successful in generating electricity, conserving fossil fuels, and reducing greenhouse gas emissions in the residential sector, which is one of the largest consumers of energy. In Algeria, to reduce energy consumption in this sector, the authorities are considering implementing a policy that would encourage grid-connected residential PV systems. This paper presents a techno-economic assessment of grid-connected residential PV systems in four climate zones in Algeria. This work was performed using HOMER software for two different PV system configurations, grid/PV and grid/PV/battery. The technical performances of the considered systems were evaluated through the assessment of the self-consumption and self-sufficiency, while the net present value (NPV), internal rate of return (IRR), profitability index (PI), and discounted payback period (DPBP) were used to determine their feasibility. A sensitivity analysis was carried out to evaluate the effects of feed-in tariff (FiT), battery costs, and PV array capacity on the profitability of the systems. The results revealed that the grid/PV systems are technically and economically feasible in all of the four climate zones. For the grid/PV/battery systems, the grant of battery costs and the development of a regional FiT system are recommended. This article provides a tool for policymakers to assess the technical and financial performance of residential solar PV systems to develop adequate policy supports and tariff structures for Algeria.
Between 2015 and 2020, 2 092 specimens of cartilaginous fishes (Chondrichthyes: Elasmobranchii) belonging to eight species and five genera were sampled along the Tunisian coast and examined for their cymothoid parasites, Among the eight examined elasmobranch species, only three were infested, Five parasite species were identified: Anilocra physodes, Emetha audouini, Ceratothoa oestroides, C. parallela and Nerocila orbignyi, These parasites presented three maturation stages: ovigerous females of A.physodes and E. audouini, adult non-ovigerous females of N. orbignyi, and juvenile females of C. oestroides and C. parallela, Most of these parasitic isopods were found on a single host species except for the two Ceratothoa species. We report new host-parasite associations, including the presence of A. physodes and E.audouini on smooth-hound Mustelus mustelus, the occurrence of C. oestroides and N. orbignyi on cartilaginous fish species, and the presence of C. parallela on black smooth-hound Mustelus punctulatus and M. mustelus. Parasitological indices and the seasonal variation in prevalence of the collected cymothoids, as well as parasitic species richness, are presented.
The level of trace metal elements (TME) (Cd, Pd, Cu, Zn, Fe) was determined according to the seasons and the sexes in the muscle and the eggs of the deep-water pandalid shrimp Plesionika edwardsii (Brandt in Reise in den aussersten Norden und Osten Sibiriens wahrend der Jahre 1843 und 1844 mit allerhochster Genehmigung auf Veranstaltung der Kaiserlichen Akademie der Wissenschaften zu St. Petersburgausgefuhrt und in Verbindung mit vielen Gelehrten herausgegeben 2(1):77–148, 1851) of the east coast of Algeria. Using the inductively coupled atomic plasma emission spectrometry method (ICP AES), the distribution of trace metals shows a significant fluctuation according to the seasons and the sex. Throughout the annual sampling, the order of heavy metal concentrations in female and male muscle, as well as in eggs were Cd < Cu < Fe < Zn < Pb, Cd < Cu < Zn < Pb < Fe, Cd < Cu < Fe < Zn < Pb respectively. In this work the heavy metal concentrations in target tissues are below the permissible limits set by the international standard except for Pb, mainly in summer, autumn and spring, exhibiting alarming levels.
This study aims to improve the quality of operation parameters of the stand-alone hybrid microgrids (HMGs). The proposed module for the AC microgrid (ACMG) is a modulated-unified power quality conditioner (M-UPQC). Furthermore, the suggested component for the DC microgrid (DCMG) is a switched-inductor boost converter module (S-IBCM). The M-UPQC control method is based on inverter modules and the system resonant features. The aim of S-IBCM applied is to improve DC microgrid (DCMG) efficiency. In this paper, the research challenge consists of two sections: first, adjusting the control parameters of M-UPQC by the black hole optimization (BHO), Harris hawk optimization (HHO), and grasshopper optimization algorithm (GOA) techniques, respectively; second, presenting a new design of the BC module called S-IBCM to increase DCMG efficiency. The programmed multi-objective functions (MOFs) for M-UPQC contain the harmonic parameters. Finally, according to output results, the performance conditions for ACMG and DCMG divisions achieve significantly improved by the proposed modules adopted. Furthermore, the performance of the M-UPQC operating under static and dynamic disturbances is tested through an experimental setup.
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1,964 members
Fadila Benabdesselam Maiza
  • Department of Physical Biology and Chemistry
Karim Moussaceb
  • Department of Technology
Fatiha Brahmi
  • Laboratoire de biomathématique, biophysique biochimie
Mouloud Kecha
  • Department of Microbiology
Madani Samah
  • Department of Physics
Information
Address
University of Bejaia , 06000, Bejaïa, Bejaia , Algeria
Head of institution
Pr BOUDA AHMED
Website
http://www.univ-bejaia.dz
Phone
+21334214333
Fax
+21334214333