Search

Abstract The current article aims to discuss the natural convection heat transfer of Ag/Al2O3-water hybrid filled in an enclosure subjected to a uniform magnetic field and provided with a rotating cylinder and an inner undulated porous layer. The various thermo-physical parameters are investigated such as Rayleigh number ( $$100 \le Ra \le 100000$$ 100 ≤ R a ≤ 100000 ), Hartmann number ( $$0 \le Ha \le 100$$ 0 ≤ H a ≤ 100 ), and the nanoparticles concentration ( $$0.02 \le \phi \le 0.08$$ 0.02 ≤ ϕ ≤ 0.08 ). Likewise, the rotational speed of the cylinder ( $$- 4000 \le \omega \le + 4000$$ - 4000 ≤ ω ≤ + 4000 ), as well as several characteristics related to the porous layer, are examined li its porosity ( $$0.2 \le \varepsilon \le 0.8$$ 0.2 ≤ ε ≤ 0.8 ), Darcy number ( $$- 100000 \le Da \le - 100$$ - 100000 ≤ D a ≤ - 100 ) which indicates the porous medium permeability and the number of undulations ( $$0 \le N \le 4$$ 0 ≤ N ≤ 4 ). The calculations are carried out based on the Galerkin Finite element method (GFEM) to present the streamlines, isotherms, entropy generation, and average Nusselt numbers in details. The main results proved that increment of Rayleigh number and Darcy number enhances heat transfer convection within the enclosure. Whilst, the porosity presents a minimal impact. Also, the rotational speed in a positive direction has a favorable influence on the heat transfer dispersion across the cavity.

The concentration levels of Zn, Pb, Cd and Cu were evaluated in the gonads and fillets of Horse mackerel (Trachurus trachurus) collected from Ghazaouet bay. The results showed the accumulation of Pb, Cd, Cu and Zn in the gonads and fillets. The metal concentrations in the fillets and gonads decreased in the following order: Zn >Cd >Pb >Cu and Zn >Cd >Cu >Pb, respectively. The levels of essential metals (zinc and copper) in both target organs generally complied with the recommended value for fish while the levels of non-essential metals like cadmium and lead, which are toxic and present in traces, greatly exceeded the recommended values in both target organs, which are ascribed mainly to the industrial pollution in Ghazaouet area. Therefore, it can be concluded that these heavy metals in different tissues of Horse mackerel, which is highly consumed in the Algerian coastal regions, could pose adverse health effects on consumers. [ABSTRACT FROM AUTHOR]

We carried out a study of the strain-compensated InxGa1-xN/GaN and InxGa1-xN/InyGa1-yN multiple quantum wells, In order to carry out this analysis, we choose a set of three different types of samples. The optimization of this laser structure allowed us to determine the optimal values of the functional parameters, in order to adjust their performance and interest. We also studied the electronic and structural properties of compound semiconductor alloys used in wurtzite phase and we have presented a comparative theoretical study of both structures. Our studies show the improvement of the spontaneous emission spectra and better carrier confinement from the use of InxGa1-xN/InyGa1-yN MQW with higher In-content in barrier as active regions for diode lasers and this structure is useful for the design of new high performance Laser diodes emitting in the Blue/Violet range, and it's also shows that the process of the electron-holes transition is strongly affected by the quantum well width and the Indium composition, and the InGaN lattice mismatch that increases with In-content causing the strain accumulation inside the QW structure. However, strain is undesirable as it can cause defects such as cracking at the interface. We can optimize the InGaN/GaN strained quantum well structures to achieve a reliable optoelectronic component. It suffices to incorporate small amounts of indium in the barrier enhances the annihilation of the defect and strain, thereby improving their structural properties. [ABSTRACT FROM AUTHOR]