Hassiba Benbouali University of Chlef

Al‐Qaisi S., Mebed A.M., Mushtaq M., Rai D.P., Alrebdi T.A., Sheikh R.A., Rached H., Ahmed R., Faizan M., Bouzgarrou S., Javed M.A.

Caid M., Rached D., Al-Qaisi S., Rached Y., Rached H.

Lead-free halide double perovskite materials have recently attracted considerable interest from the scientific community due to their vast potential in optoelectronic applications without toxicity issues. Herein, we report a new lead-free halide double perovskite, namely Cs2CdZnCl6, based on DFT calculations. We found that Cs2CdZnCl6 is mechanically stable in the cubic nonmagnetic phase. The Electronic band structure calculations revealed that this compound exhibits a direct semiconductor band gap of 1.43 eV. The dielectric function ε, reflectivity R, refractive index n, absorption coefficient α, and optical conductivity σ are analyzed up to 13.0 eV. Furthermore, it is found that the studied compound has a significant photoresponse in the ultraviolet light region. Finally, the findings suggest that Cs2CdZnCl6 is a promising material for optoelectronic applications.

Al-Qaisi S., Mushtaq M., Alomairy S., Vu T.V., Rached H., Haq B.U., Mahmood Q., Al-Buriahi M.S.

Investigations of stable lead-free perovskites have ignited an increasing interest in overcoming lead-based perovskites' instability and toxicity problems. This study thoroughly investigated the transport, nature of electronic, stability, and optical properties of inorganic halide double perovskites', namely Na 2 CuMCl 6 (M = Bi, Sb), to better understand their possible applications. The theory of density function was applied to determine the physical characteristics of these materials. This cubic material's stability was validated by optimizing the mechanical stability test, tolerance factor, and structure. Small bandgap semiconductors with outstanding optoelectronic performance caused by low reflectivity, high conductivity, and optical absorption, as well as a high potential for optoelectronic application, were used. Due to the small bandgap, we also identified multiple transport parameters with chemical potential (μ). Based on this study, our findings revealed that the figure of merit (ZT) was near to unity due to the semiconducting nature of the materials, implying that it will be effective in thermoelectric technology.

Bouledroua O., Hafsi Z., Djukic M.B., Elaoud S.

We are reporting in this study the hydrogen permeation in the lattice structure of a steel pipeline designed for natural gas transportation by investigating the influence of blending gaseous hydrogen into natural gas flow and resulted internal pressure values on the structural integrity of cracked pipes. The presence of cracks may provoke pipeline failure and hydrogen leakage. The auto-ignition of hydrogen leaks, although been small, leads to a flame difficult to be seen. The latter makes such a phenomenon extremely dangerous as explosions became very likely to happen. In this paper, a reliable method is presented that can be used to predict the acceptable defect in order to reduce risks caused by pipe failure due to hydrogen embrittlement. The presented model takes into account the synergistic effects of transient gas flow conditions in pipelines and hydrogen embrittlement of steel material due to pressurized hydrogen gas permeation. It is found that blending hydrogen gas into natural gas pipelines increases the internal load on the pipeline walls due to overpressure values that may be reached in a transient gas flow regime. Also, the interaction between transient hydrogen gas flow and embrittlement of API 5L X52 steel pipeline was investigated using Failure Assessment Diagram (FAD) and the results have shown that transient flow enhances pipeline failure due to hydrogen permeation. It was shown that hydrogen embrittlement of steel pipelines in contact with the hydrogen environment, together with the transient gas flow and significantly increased transient pressure values, also increases the probability of failure of a cracked pipeline. Such a situation threatens the integrity of high stress pipelines, especially under the real working conditions of hydrogen gas transportation. • Numerical investigation of transient hydrogen-natural gas flow in a steel pipeline. • Influence of gaseous hydrogen flow on the structural integrity of precracked pipes. • Interaction between transient hydrogen-natural gas flow and hydrogen embrittlement. • Failure Assessment Diagram (FAD) of a precracked API 5L X52 steel pipeline. • The stress intensity and safety factors analysis during transient hydrogen pressure.

Hai T., Sharafati A., Mohammed A., Salih S.Q., Deo R.C., Al-Ansari N., Yaseen Z.M.

Sustainable utilization of the freely available solar radiation as renewable energy source requires accurate predictive models to quantitatively evaluate future energy potentials. In this research, an evaluation of the preciseness of extreme learning machine (ELM) model as a fast and efficient framework for estimating global incident solar radiation (G) is undertaken. Daily meteorological datasets suitable for G estimation belongs to the northern parts of the Cheliff Basin in Northwest Algeria, is used to construct the estimation model. Cross-correlation functions are applied between the inputs and the target variable (i.e., G) where several climatological information's are used as the predictors for surface level G estimation. The most significant model inputs are determined in accordance with highest cross-correlations considering the covariance of the predictors with the G dataset. Subsequently, seven ELM models with unique neuronal architectures in terms of their input-hidden-output neurons are developed with appropriate input combinations. The prescribed ELM model's estimation performance over the testing phase is evaluated against multiple linear regressions (MLR), autoregressive integrated moving average (ARIMA) models and several well-established literature studies. This is done in accordance with several statistical score metrics. In quantitative terms, the root mean square error (RMSE) and mean absolute error (MAE) are dramatically lower for the optimal ELM model with RMSE and MAE = 3.28 and 2.32 Wm -2 compared to 4.24 and 3.24 Wm -2 (MLR) and 8.33 and 5.37 Wm -2 (ARIMA).

Rached Y., Caid M., Rached H., Merabet M., Benalia S., Al-Qaisi S., Djoudi L., Rached D.

Within density functional theory (DFT), we have investigated the structural, elastic, electronic, magnetic, and thermoelectric properties of XCrSb (X = Fe and Ni) half-Heusler (HH) alloys and FeCrSb/NiCrSb superlattice (SL). Firstly, we have checked the chemical phase of HH and SL compounds, respectively, in addition to the mechanical stability of two HH compounds. The description of the band structure and integer magnetic moment values lead to a half-metallic behavior of compounds. Moreover, within Boltzmann’s transport theory, the thermoelectric properties are carried out; for example, the Seebeck coefficient (S), thermal electronic conductivity (κe/τ), power factor (PF), and figure of merit (ZT) were determined. Consequently, the obtained results of the suggested materials made them potential candidates for thermospintronic devices.

Djilali S., Ghanbari B.

In this research, we discuss the influence of an infectious disease in the evolution of ecological species. A computational predator-prey model of fractional order is considered. Also, we assume that there is a non-fatal infectious disease developed in the prey population. Indeed, it is considered that the predators have a cooperative hunting. This situation occurs when a pair or group of animals coordinate their activities as part of their hunting behavior in order to improve their chances of making a kill and feeding. In this model, we then shift the role of standard derivatives to fractional-order derivatives to take advantage of the valuable benefits of this class of derivatives. Moreover, the stability of equilibrium points is studied. The influence of this infection measured by the transmission rate on the evolution of predator-prey interaction is determined. Many scenarios are obtained, which implies the richness of the suggested model and the importance of this study. The graphical representation of the mathematical results is provided through a precise numerical scheme. This technique enables us to approximate other related models including fractional-derivative operators with high accuracy and efficiency.

Achour K., Meddi M., Zeroual A., Bouabdelli S., Maccioni P., Moramarco T.

Drought is the most frequent natural disaster in Algeria during the last century, with a severity ranging over the territory and causing enormous damages to agriculture and economy, especially in the north-west region of Algeria. The above issue motivated this study, which is aimed to analyse and predict droughts using the Standardized Precipitation Index (SPI). The analysis is based on monthly rainfall data collected during the period from 1960 to 2010 in seven plains located in the north-western Algeria. While a drought forecast with 2 months lead-time is addressed using an artificial neural network (ANN) model. Based on SPI values at different time scales (3-, 6-, 9-, and 12-months), the seven plains of north-western Algeria are severely affected by drought, conversely of the eastern part of the country, wherein drought phenomena are decreased in both duration and severity. The analysis also shows that the drought frequency changes according to the time scale. Moreover, the temporal analysis, without considering the autocorrelation effect on change point and monotonic trends of SPI series, depicts a negative trend with asynchronous in change-point timing. However, this becomes less significant at 3 and 6 months’ time scales if time series are modelled using the corrected and unbiased trend-free-pre-whitening (TFPWcu) approach. As regards the ANN-based drought forecast in the seven plains with 2 months of lead time, the multi-layer perceptron networks architecture with Levenberg–Marquardt calibration algorithm provides satisfactory results with the adjusted coefficient of determination ( $$ R_{\text{adj}}^{2} $$ ) higher than 0.81 and the root-mean-square-error (RMSE) and the mean absolute error (MAE) less than 0.41 and 0.23, respectively. Therefore, the proposed ANN-based drought forecast model can be conveniently adopted to establish with 2 months ahead adequate irrigation schedules in case of water stress and for optimizing agricultural production.

Azzouz-Rached A., Hadi M.A., Rached H., Hadji T., Rached D., Bouhemadou A.

• Mn 2 SiC is ductile, whereas Mn 2 AlC is brittle. • Mn 2 AlC is a promising thermal barrier coating (TBC) material. • Mn 2 AlC and Mn 2 SiC are suitable for use in harsh environments. • Both of studied compounds remain mechanically stable under the pressure up to 30 GPa. The inherent properties of MAX phases have made them candidate materials for various technological applications. From this perspective, the present article reports the results of a detailed theoretical investigation of the effects of pressure on the structural, elastic, magnetic, and thermodynamic properties of Mn 2 AlC and Mn 2 SiC MAX phases using density functional theory (DFT). The lattice parameter c decreases with increasing pressure slightly faster than the lattice constant a . Both of studied compounds remain mechanically stable under the pressure up to 30 GPa. All independent elastic constants increase non-linearly with increasing pressure. Mn 2 SiC is ductile, whereas Mn 2 AlC is brittle at ambient pressure. The ductility of Mn 2 SiC increases with increasing pressure, while Mn 2 AlC undergoes a transition from brittle to ductile at 10 GPa. It is found that Mn 2 AlC is stable in a ferromagnetic ordering of magnetic moments, while Mn 2 SiC is stable in an anti-ferromagnetic ordering. The magnetic moment of Mn in Mn 2 AlC at zero pressure is approximately 1.67 μ B , which is consistent with the value of 1.86 μ B reported in the literature. The high melting temperature and high Debye temperature of Mn 2 AlC and Mn 2 SiC make them suitable for use in harsh environments. Mn 2 AlC is a promising thermal barrier coating (TBC) material. The rate of increase of the isobaric heat capacity C p of Mn 2 AlC with increasing temperature is higher than that of Mn 2 SiC. The thermal expansion coefficient of Mn 2 AlC is larger than that of Mn 2 SiC over all pressure and temperature ranges considered here. We hope this study will inspire MAX phase researchers around the world to further explore the properties of the title materials through experiments and theories.

Djilali S., Ghanbari B., Bentout S., Mezouaghi A.

• A diffusive mussel-algae model with time fractional-order derivative is proposed. • The existence of Turing instability, Hopf bifurcation, Turing-Hopf bifurcation are achieved in the presence of time-fractional derivative. • The influence of the time fractional derivative on the spatiotemporal dynamics is investigated. • The obtained mathematical results are tested numerically. In this paper, we consider a time fractional-order derivative for a diffusive mussel–algae model. The existence of pattern formation was the subject of interest of many previous research works in the case of the diffusive mussel–algae model. Examples include the Turing instability, Hopf bifurcation, Turing-Hopf bifurcation, and others. The presence of the time–fractional–order derivative never been investigated in this model. Next to it ecological relevant, it can generate some important patterns. One of these patterns is produced by the presence of the Turing-Hopf bifurcation. Therefore, our main interest is to analyze the effect of the time fractional–order derivative on the spatiotemporal behavior of the solution, which never been achieved for the mussel-algae model. Besides, Turing–Hopf was studied exclusively on the classical reaction-diffusion systems, where it was also considered for the diffusive mussel-algae model. Thus, our paper puts the fist steps on proving the existence of this type of codimension bifurcation on the diffusive systems with time fractional–order–derivative systems. Further, a suitable numerical simulations are used for confirming the theoretical obtained results.