Université Ibn Khaldoun Tiaret
Recent publications
The stability evaluation of the dams subjected to seismic excitations is really very complex as the earthquake response of the concrete gravity dam depends upon its connection joints with foundation rock. This study presents the seismic response of concrete gravity dams considering welded contact and friction contact and along dam-foundation rock interface. Friction contact is provided using contact elements. Two-dimensional finite element model of Oued Fodda concrete gravity dam, located in Chlef at the northwestern part of Algeria, is used for this purpose. Nonlinear analyses of dam-foundation rock system are performed using ANSYS software. The reservoir water is modeled as added mass using the Westergaard approach. The Druker-Prager model is employed in the nonlinear analysis for dam concrete. The surface-to-surface contact elements based on the Coulomb's friction law are used to describe the friction. These contact elements use a target surface and a contact surface to form a contact pair. According to this study, when the friction contact is considered in joints, sliding displacement of dam base occurs along the dam-foundation rock interface. The dam sliding along its foundation decreases the deformation response; principal stresses in the dam body and shear force at both the heel and toe of the dam.
The post-operative period for a carrier of total hip prosthesis (THP), especially in the first months, remains the most difficult period for a patient after each operation, even if traumatologist surgeons want the relief and success of their operations. In this investigation, selected three of the daily activities for a wearer of total hip replacement (THR), such as, sitting in a chair, lifting a chair and going down stairs, and was performed a numerical simulation by finite elements in based on experimental data by Bergmann (Bergmann 2001) in terms of effort for each activity. Different stresses have been extracted, as well as a detailed comparison between two activities with different induced stresses such as normal, tensile and compressive shear stresses.
The disadvantage of using nanofluids as a heat transfer fluid in the Parabolic Trough Concentrating solar power plant is increased pressure drops. Therefore, more attention should be paid to optimizing the receiver pipe diameter. The aim of this study was to optimize a new receiver to study the industrial process performance of nanofluid-based Parabolic Trough Concentrating plants in 4 different regions in southern Algeria (Hassi rmel, In salah, Tamnrasset, and Bechar). Nanoparticles (Al2O3, CuO) were added to both base liquids (Dowtherm A, Therminol VP-1). The methodology is based on a two-step approach: first, the effects of nanoparticles and temperature on the thermophysical properties of nanofluids, such as thermal conductivity, specific heat capacity, and density, are numerically investigated using the MATLAB program; second, nanofluids properties are integrated into SAM (System Advisor Model) software to perform a 50 MW parabolic trough solar power plant with 25% of a backup system and nanofluids in heat transfer system for the different representative locations of the climate of Algeria. The results of the first part show that the addition of nanoparticles increases the thermal conductivity and density of the nanofluid by 11% and 23%, respectively, and the specific heat capacity is proportional to temperature. The most favorable site is Insalah with an optimal SM egale to 3 and a capacity factor of 51%. Finally, the use of nanofluids as a heat transfer fluid in solar power plants plays a great role in improving its efficiency, the best choice for nanofluids under Algerian climates is CuO/Dowtherm A with an optimal tube diameter of 0.07 m.
This article presents the effect of silt proportion on the hypoplastic parameters (exponent n, granular hardness hs, exponent α, and exponent β) used for numerical simulation, calculation of emax, and transitional fines content (Fct). Fifteen oedometer tests were carried out at various relative densities (RD = 30, 65, and 80%) to evaluate their effect on the compressibility parameters such as compression index Cc, secant oedometer modulus Esecant, and pre-consolidation pressure σ′p. Additionally, ten monotonic undrained triaxial tests were conducted at RD = 65% and RD = 80% to determine the value of the α parameter used in numerical simulation. The results obtained indicate that that the void ratio decreases with the increasing proportion of fine fraction up to 30% and further decreases with an additional increase of fines up to 40% for the three cases of relative densities (RD = 30, 65 and 80%). Additionally, it is shown from our results that the hypoplastic model is able to simulate soil behavior under undrained and oeodometer conditions. It was found that an increase in the α parameter leads to an increase in the dilatancy of the curves observed in the triaxial test. On the other hand, the parameters α and β seem to have no effect on the compressibility curves, and it was necessary to rely on their physical parameters. The transitional fines content (Fct)FCt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{FC}}_{\mathrm{t}}$$\end{document}FCt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{FC}}_{\mathrm{t}}$$\end{document} depends on the stress level and maximum void ratio, which are calculated from the parameters of the hypoplastic model (eio, hs, ps, n).
In the Mediterranean basin, the tick species Hyalomma lusitanicum Koch stands out among other species of the Hyalomma genus due to its wide distribution, and there is great concern about its potential role as a vector and/or reservoir and its continuous expansion to new areas because of climate warming and human and other animal movements. This review aims to consolidate all the information on H. lusitanicum, including taxonomy and evolution, morphological and molecular identification, life cycle, sampling methods, rearing under laboratory conditions, ecology, hosts, geographical distribution, seasonality, vector role and control methods. The availability of adequate data is extremely relevant to the development of appropriate control strategies in areas where this tick is currently distributed as well as in new areas where it could become established in the near future.
Recent years have seen the re-emergence of vector-borne diseases, representing more than 17% of infectious diseases globally. Most of these diseases can be prevented by vector control measures. Series of difficulties which are linked to the fight. Plant insecticides can present interesting alternatives to the chemical insecticides currently used in the fight against these pests. In the first part, we have inventoried the vector species in the region of El Kantara, Biskra, by conducting surveys of three sites. The second part focuses on the biological control of the larvae of the most abundant species in the region, that is, Culiseta longiareolata . The faunal inventory of the species of Culicidae in the three sites of El Kantara showed seven species belonging to three genera. The genus Culiseta was the best represented, particularly with the species C. longiareolata (89.91%). The toxicological activity of the ethanoic extracts of the seeds of Peganum harmala and Citrullus colocynthis was studied in synergy against the larvae of Culiseta longiareolata at different concentrations. The mortality rate increased over time to reach more than 70% after 5 days.
Introduction. In various industrial processes, squirrel cage induction motors are widely employed. These motors can be used in harsh situations, such as non-ventilated spaces, due to their high strength and longevity. These machines are subject to malfunctions such as short circuits and broken bars. Indeed, for the diagnosis several techniques are offered and used. Novelty of the proposed work provides the use of wavelet analysis technology in a continuous and discrete system to detect faults affecting the rotating part of an induction motor fed by a three-phase inverter. Purpose. This paper aims to present a novel technique for diagnosing broken rotor bars in the low-load, stationary induction machine proposed. The technique is used to address the problem of using the traditional Techniques like Fourier Transforms signal processing algorithm by analyzing the stator current envelope. The suggested method is based on the use of discrete wavelet transform and continuous wavelet transform. Methods. A waveform can be monitored at any frequency of interest using the suggested discrete wavelet transform and continuous wavelet transform. To identify the rotor broken bar fault, stator current frequency spectrum is analyzed and then examined. Based on a suitable index, the algorithm separates the healthy motor from the defective one, with 1, 2 and 3 broken bars at no-load. Results. In comparison to the healthy conditions, the recommended index significantly raises under the broken bars conditions. It can identify the problematic conditions with clarity. The possibility of detecting potential faults has been demonstrated (broken bars), using discrete wavelet transform and continuous wavelet transform. The diagnostic method is adaptable to temporary situations brought on by alterations in load and speed. Performance and efficacy of the suggested diagnostic method are demonstrated through simulation in Simulink® MATLAB environment.
Un-doped, Zn-doped, and Al–Zn co-doped CdO thin films were deposited onto glass substrates at 350 °C by spray pyrolysis. X-ray diffraction (XRD) analysis was conducted to investigate the structural properties of the films. The XRD patterns confirmed that all the films crystallize in a cubic structure and that the addition of Zn and Al did not alter the CdO crystal structure. Energy-dispersive X-ray spectroscopy analysis further confirmed the successful incorporation of Zn and Al into the CdO films. Theoretical calculations based on first-principles were performed, and crystallographic information files (CIF) were obtained for optimized theoretical supercells in space group Pm3-m. The CIF files were used as input for experimental XRD spectra Rietveld refinement, to determine the Wyckoff positions of the dopants and their occupation rates. The optical properties of the films were characterized using transmittance measurements in the wavelength range of 300–1700 nm. The optical data indicated an increase in the average transmittance from 60 to 70% within the wavelength range of 600–1700 nm upon Al–Zn co-doping. The estimated direct optical band gap of the un-doped, doped, and co-doped CdO thin films is varied between 2.41 and 2.50 eV. All the samples exhibited n-type conductivity with low electrical resistivity of about 1.32 × 10–4 Ω⋅cm. Co-doped CdO thin films with 1% Al and 3% Zn exhibited higher carrier concentration (4.39 × 10⁺²⁰ cm⁻³) than the other samples.
Introduction The inducible form of nitric oxide (iNOS) is induced by cytokines and endotoxins. The cardiac-protective effects of nitric oxide (NO) secreted by endothelial NOS are dependent on arginine. Arginine production occurs mainly within the organism, with the kidneys playing a key role in its synthesis and the elimination of asymmetric dimethylarginine (ADM). In the present study the relationship between iNOS, ADMA and left ventricular hypertrophy in chronic kidney disease (CKD) patients and the effect of treatment with angiotensin converting enzyme inhibitor (ACEI) associated with vitamin C (Vit C) were investigated. Material and methods A longitudinal observational study was conducted on 153 patients with CKD. We studied the correlation between the mean values of iNOS and ADMA in CKD patients and its relationship with left ventricular hypertrophy and the benefit of treating these patients with an associated ACEI and Vit C. Results The mean age of the patients was 58.85 ±12.75 years. The mean values of iNOS and ADMA were 63.92 ± 0.59 µmol/l and 16.77 ±0.91 µmol/l, respectively. These values increased significantly with the degradation of the renal function (p < 0.05). A significant positive correlation was found between the left ventricular mass index (LVMI) and the two markers, ADMA (0.901 and p = 0001) and iNOS (0.718 and p = 0.0001). After 2 years of treatment with Vit C and ACEI, a significant decrease in LVMI was observed. Conclusions NO secreted by the iNOS system and ADMAs initiates cardiac remodeling to lead to left ventricular hypertrophy and cardiac fibrosis. ACEIs increase the expression and activity of eNOS and decrease iNOS. Vit C prevents oxidative damage by scavenging ROS species and reagents nitrogen while. iNOS and ADMA accelerate cardiac aging. We conclude that ACEIs combined with Vit C may improve heart health and limite left ventricular hypertrophy in CKD patients.
In this research, the approach of FP-LAPW (full potential linearized augmented plane wave) is employed within WIEN2K for the investigations of structural, thermodynamic, electronic, and mechanical properties of the V2ScSnC2 and Nb2ScSnC2 MAX-phases quaternary compounds. The V2ScSnC2 and Nb2ScSnC2 compounds exist in “α” and “β” polymorph structures. The formation energies (Eform) investigated insure that the α-polymorph is more stable than the β one. As it happens, Nb2ScSnC2 is more stable than V2ScSnC2. The Nb2ScSnC2 has an enhanced mechanical property compared to the V2ScSnC2 compound. The elastic constants (ECs) of interested materials fulfill all the conditions of mechanical stability and revealed a ductile nature. The predicted Cauchy's pressure and Poisson's ratio possess positive values signifying the ionic character of the V2ScSnC2 compound. The quaternary Nb2ScSnC2 compound exists as amalgamation of covalent and ionic bonds with a predominance of the ionic bonding character. The high melting temperature and high Debye temperature of V2ScSnC2 and Nb2ScSnC2 make them suitable for use in harsh environments. Furthermore, they exhibit potential as a promising material for thermal barrier coatings (TBCs). Electronic structure analysis confirm the metallic character of the two interested compounds. At high temperatures and pressures the thermodynamic properties including the Cv (Heat capacity) and Ɵ(Debye temperature) are explored. We deem that this study of quaternary MAX-phase compounds will bring new insight for the experimentalists to employ for their future applications.
This study establishes the existence and stability of solutions for a general class of Riemann–Liouville (RL) fractional differential equations (FDEs) with a variable order and finite delay. Our findings are confirmed by the fixed-point theorems (FPTs) from the available literature. We transform the RL FDE of variable order to alternate RL fractional integral structure, then with the use of classical FPTs, the existence results are studied and the Hyers–Ulam stability is established by the help of standard notions. The approach is more broad-based and the same methodology can be used for a number of additional issues.
The fully developed turbulent flow of pseudoplastic (n=0.75) and Newtonian fluids in an isothermal axially rotating cylinder has been carried out using a large eddy simulation (LES) with an extended Smagorinsky model. The simulation Reynolds number of the present predictions has been assumed to be Res=4000 at various rotation rates (0≤N≤3). This investigation seeks to assess the influence of the centrifugal force induced by the swirl on the mean flow quantities, turbulent statistics, and instantaneous turbulence structure to describe the rheological behavior and the turbulence features. The predicted results indicate that with increasing rotation rate, the pseudoplastic fluid tends to behave like a liquid when approaching the pipe center due to the lower apparent fluid viscosity in the logarithmic region as the pipe wall rotates. Moreover, the reduction in the pseudoplastic apparent viscosity in the core region induces a pronounced increase in the axial velocity profile further away from the pipe wall toward the core region. It is interesting to note that the growth of the centrifugal force induced by the swirl driven by the rotating pipe wall results in an apparent attenuation in turbulence intensities of the axial velocity fluctuation and, consequently, in the kinetic energy of turbulent fluctuations and the turbulent Reynolds shear stress of the axial-radial velocity fluctuations, as the pipe wall rotates. Moreover, the increased rotation rate leads also to a noticeable increase in the Root mean square (RMS) of the radial and tangential fluctuations. It can be said that the transport mechanism of turbulence intensities from the axial components to the other ones exhibits a marked increase with increasing pipe wall rotation.
In this work, a layered silicate Na-magadiite was hydrothermally synthesized and used as a starting material to prepare Ag- exchanged magadiites through intercalation reaction with 0.5 M, 1 M and 1.5 M silver nitrate solutions. The obtained Ag-exchanged magadiite samples are then reduced with sodium tetrahydridoborate (NaBH4) to obtain AgNPs-magadiite composites materials with different silver contents. All samples obtained are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and thermal (TG) analysis. The results show that the exchange with silver is total and leads to a disorganization of the layered magadiite structure which is recovered again once Ag-magadiite samples are reduced with sodium tetrahydridoborate (NaBH4). Therefore, these analysis methods confirm also the formation of silver nanoparticles (AgNPs) with an average size of about 24 nm in AgNPs-magadiite materials after reduction reactions. Formed by agglomeration of reduced Ag° species which occurs outside the layered structure, these AgNPs species are dispersed in the magadiite solid matrix and are not part of its internal structure. Used as catalysts in the photodegradation of Congo red and Methylene blue dyes in aqueous solutions, the AgNPs-magadiite materials obtained lead to the complete reduction of these pollutants into nontoxic organic compounds.
Citation: Khattabi, L.; Chettoum, A.; Hemida, H.; Boussebaa, W.; Atanassova, M.; Messaoudi, M. Pirimicarb Induction of Behavioral Disorders and of Neurological and Reproductive Toxicities in Male Rats: Euphoric and Preventive Effects of Ephedra alata Monjauzeana. Abstract: Carbamate pesticides are a risk to human well-being, and pirimicarb is the most widely employed carbamate insecticide. This ongoing investigation aimed to reveal its toxicity on neurobe-havioral and reproductive function. The study was carried out on male Wistar rats by assessment of behavioral changes via experiments, such as the forced swim test and the elevated plus maze; determination of oxidative stress (checking parameters such as catalase activity, etc.); measurement of cortisol and testosterone serum titers, and IL-1β levels in the plasma and brain; and evaluation of histopathological lesions that induced pirimicarb after 28 days of gavage, specifically in the brain and testis. Traces of pirimicarb were analyzed in tissue extracts using LCMS/MS. At the same time, the beneficial and protective effect of EamCE (Ephedra alata monjauzeana Crude Extract) were tested. The outcomes showed considerable anxiety and depressive status, with an evident increase in cortisol and IL-1β titers and an important decrease in oxidative enzymes and testosterone. Significant histological lesions were also recorded. In addition, the LCMS/MS analysis affirmed the accumulation of pirimicarb in organ tissue from rats force-fed with pirimicarb. Conversely, EamCE demonstrated outstanding potential as a preventive treatment, restoring cognitive and physical performance , boosting fertility, enhancing antioxidant and anti-inflammatory activities and preserving tissue integrity. We concluded that pirimicarb has critical deleterious impacts on health, affecting the neuroimmune-endocrine axis, and EamCE has a general euphoric and preventive effect.
A mathematical study was conducted for the mixed convection inside a cavity for three aspect ratios filled with hybrid nanofluids by moving the vertical walls down, where the upper wall was thermally isolated, and the two vertical walls with a temperature that is less than the lowest wall's, which was at a sinusoidal temperature. The investigation and discussion focused on the Richardson numbers (0.1-100), hybrid nanoparticle sizes (0.0-0.08), and the impact of size on the thermal and hydrodynamic properties of hybrid nanoparticles. At lower Richardson numbers, hybrid nanoparticle volume fraction impacts the thermal behaviour model. Besides, it was observed that decreasing the effect of average Nusselt number and nanoparticle size was due to the increase in Richardson numbers.The present results also showed the vital role that sinusoidal temperature has on heat transfer.
Centaurea parviflora (C. parviflora), belonging to the family Asteraceae, is an Algerian medicinal plant used in folk medicine to treat different diseases related to hyperglycemic and inflammatory disorders, as well as in food. The present study aimed to assess the total phenolic content, in vitro antioxidant and antimicrobial activity and phytochemical profile of the extracts of C. parviflora. The extraction of phenolic compounds from aerial parts was conducted using solvents of increasing polarity starting from methanol, resulting in crude extract (CE), to chloroform extract (CHE), ethyl acetate extract (EAE) and butanol extract (BUE). The total phenolic, flavonoid and flavonol contents of the extracts were determined using the Folin–Ciocalteu and AlCl3 methods, respectively. The antioxidant activity was measured with seven methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, galvinoxyl free-radical-scavenging test, 2,2′-Azino-Bis(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS) assay, cupric reducing antioxidant capacity (CUPRAC), reducing power, Fe+2-phenanthroline reduction assay and superoxide-scavenging test. The disc-diffusion method aimed at testing the sensitivity of bacterial strains toward our extracts. A qualitative analysis with thin-layer chromatography of the methanolic extract was performed. Moreover, HPLC-DAD-MS was used to establish the phytochemical profile of the BUE. The BUE was found to contain high amounts of total phenolics (175.27 ± 2.79 µg GAE/mg E), flavonoids (59.89 ± 0.91 µg QE/mg E) and flavonols (47.30 ± 0.51 µg RE/mg E). Using TLC, different components such as flavonoids and polyphenols were noted. The highest radical-scavenging ability was recorded for the BUE against DPPH (IC50 = 59.38 ± 0.72 µg/mL), galvinoxyl (IC50 = 36.25 ± 0.42 µg/mL), ABTS (IC50 = 49.52 ± 1.54 µg/mL) and superoxide (IC50 = 13.61 ± 0.38 µg/mL). The BUE had the best reducing power according to the CUPRAC (A0.5 = 71.80 ± 1.22 μg/mL), phenanthroline test (A0.5 = 20.29 ± 1.16 μg/mL) and FRAP (A0.5 = 119.17 ± 0.29 μg/mL). The LC-MS analysis of BUE allowed us to identify eight compounds including six phenolic acids and two flavonoids: quinic acid, five chlorogenic acid derivatives, rutin and quercetin 3-o-glucoside. This preliminary investigation revealed that the extracts of C. parviflora have a good biopharmaceutical activity. The BUE possesses an interesting potential for pharmaceutical/nutraceutical applications.
The aim of this work is to examine numerically the effect of using a rotating cylinder and porous layers on the forced convection in a bifurcating grooved channel (BGC) filled with two types of nanofluids (MgO-water, SiO2-water). The semi-implicit finite volumes method was used to solve the governing equations. The effects of Reynolds number, nanoparticles volume fraction, and cylinder rotation speed on hydro-thermal performances have been investigated. According to the obtained results, the rotation direction plays a significant role in the formation of vortices at the branching channel, such that when the cylinder rotates clockwise, the vortex occurs in the vertical channel, and it decreases with increasing Reynolds number. Besides, using BGC with a porous medium enhances the heat transfer rate by 52% and 49% at the vertical and horizontal walls of the porous layer, respectively. On the other hand, the heat transfer rate is improved by 2.6% when using MgO nanoparticles compared to SiO2. Therefore, the use of bifurcating grooved channels can improve the thermal performance of various applications in thermal engineering, from fuel cells to electronic cooling.
The purpose of this research is to reveal the effects of roughness on the hydrodynamics of the fluid around a grooved cylinder by studying the drag and recirculation length. The main objectives are to reach the maximum reduction of the wind load. This work is carried out to investigate the effect of the number of grooves on the drag reduction of flow around a circular cylinder with triangular grooves. This investigation reports numerically on a laminar steady flow over a cylinder with 2, 4, 8, 12 and 16 triangular grooves regularly distributed around the cylinder circumference with wavelength and wave amplitude of 1/10, immersed in two-dimensional unconfined Newtonian fluid over the symmetry regimes. The predicted results showed an excellent agreement with the available data of literature for validation. The obtained results used for our investigations for a Reynolds number up to 40 suggest that the presence of the grooves on the smooth cylinder surface leads to a slight reduction over the drag coefficient and the recirculation length at the same Reynolds number, this trend is more pronounced as the number of grooves increase.
The goal of this work is to study a multi-term boundary value problem (BVP) for fractional differential equations in the variable exponent Lebesgue space (Lp(·)). Both the existence, uniqueness, and the stability in the sense of Ulam–Hyers are established. Our results are obtained using two fixed-point theorems, then illustrating the results with a comprehensive example.
Background Attitudes towards COVID-19 vaccines are the main determinants of herd immunity sought by public health authorities. Refusal and hesitancy are apparent expressions of negative attitudes. Statistics of Covid-19 vaccination by country (WHO 2022; Covid19taskforce 2022) showed the majority of the Algerian population are reluctant to be vaccinated against COVID-19. The main question raised by the present study is what causes are behind such hesitancy behavior towards COVID-19 vaccines. The aim of this study is to unveil factors, which influence attitudes towards the COVID-19 vaccine, in order to develop behavior change communication campaigns, and to set up a well-designed national strategy to get to a level of herd immunity. Subject and Methods To collect data, a semi-structured questionnaire was given to individuals. Results The results revealed that the majority of participants (63.55%) exhibit negative attitudes towards Covid-19 vaccine, and just a third of participants have positive attitudes towards vaccine. Factors influencing positive attitudes towards COVID-19 vaccination are mainly inherent to personal convictions on the benefits of the vaccine. While, the main factors behind negative attitudes towards COVID-19 vaccination, are inherent to the participants’ “naive explanation of COVID-19 pandemic” who rely on traditional medicine (indigenous medicine) and natural immunity and who exhibit “Mistrust towards health authorities”. Conclusion We have put forward recommendations to tackle factors causing negative attitudes towards COVID-19 vaccination, and alleviate hurdles facing national strategy to eradicate the pandemic.
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789 members
Youcef Messlem
  • Electrical Engineering
Redouane Miloua
  • Department of Biology
Abdelkader Dehbi
  • Department of Physics
Abdiche Ahmed
  • Science et Technologie
Miara Mohamed Djamel
  • Department of Nature and life sciences
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