Publications

2023
Baiti A SH. Numerical investigation of turbulent mixed convection in a round bottom flask using a hybrid nanofluid. Advances in Mechanical Engineering. 2023;15 (9) :1-12.Abstract

In this study, we conducted a numerical investigation of the turbulent mixed convection of a hybrid nanofluid (HNF) in a flask equipped with an agitator, which is commonly used in organic chemistry synthesis. The bottom wall and the middle section of the flask were maintained at a constant high temperature Th, while the upper, left, and right walls up to the middle of the flask were kept at a low temperature Tc. The HNF consisted of Graphene (Gr) and Carbon nanotubes (CNTs) nanoparticles (NP) dispersed in pure water. The governing equations were solved numerically using the finite size approach and formulated using the Boussinesq approximation. The effects of the NP volume fraction u (ranging from 0% to 6%), the Rayleigh number Ra (ranging from 104 to 106), and the Nusselt number (Nu) were investigated in this simulation. The results indicated that the heat transfer is noticeably influenced by the Ra number and the increase in the u ratio. Additionally, the agitator rotation speed had a slight effect on the heat transfer.

Chafai Nadjib SH. Development of new models to predict the corrosion inhibition efficiency as functions of some molecular descriptors using statistical analysis. Journal of the Indian Chemical Society [Internet]. 2023;100 (9). Publisher's VersionAbstract
62 models have been proposed to predict the corrosion inhibition efficiency for a wide variety of organic and inorganic compounds using the statistical analysis. In this context, we used the experimental data of the corrosion inhibition efficiencies of 100 inhibitors (organic and inorganic) as an input data for a statistical analysis in order to determine the most adequate quantitative structure activity relationship (QSAR) models to predict the inhibition efficiency as function of some molecular descriptors. The experimental data used in this study are selected for the corrosion of steel in 0.5 M H2SO4 at 25 °C. Also, we choose the inhibition efficiencies determined by potentiodynamic polarization curves (IEp) and electrochemical impedance spectroscopy (IEEIS). Accordingly, the statistical analysis has been applied to collect the IEp and IEEIS models of corrosion inhibitors. The different models are compared to assess the performance of the best model. Global Performance Indicator (GPI) is computed to evaluate all models. The results show that the cubical model with a GPI of 1.27 is the best (M23) for IEEIS, and the linear model with a GPI of 0.64 for IEp.
7- Salhi Hicham, Hadjira A JB. Statistical analysis of the solar diffuse fraction radiation using regression analysis of longitudinal data in India. J Ther Eng . 2023;9 (3) :1-10.Abstract

In this study, the validity of the estimation of a single regression equation for the diffuse frac- tion across 22 stations in India using the two parameters: the clearness index and the sunshine ratio is tested. The homogeneity test based on Fisher’s statistics was applied to test the homo- geneity of the estimated parameters across all stations. The results showed that the p-value at the level of 5% for each model is smaller than 0.05, indicating that all stations were heteroge- neous. The Hierarchical Cluster Analysis (HCA) was used to classify the data into homoge- nous clusters. The results of HCA indicated that the longitudinal data were divided into four main clusters. For each cluster, the regression analysis was applied based on the longitudinal data then, the fixed effects model (FEM) and the random-effects model (REM) were used for the evaluation. Further, the Hausman test was applied to choose between the fixed effects model and the random-effects model. Finally, the results showed that the four best regression models were found for the selected stations in the study area.

2022
Salhi Hicham CHAFAIN. Evaluation of the thermal conductivity of nanofluids using statistical analysis methods. Nanoscience and Technology: An International Journal. 2022;13 (4) :45-61.Abstract

In this study, a statistical analysis method such as cluster analysis was used to group the effective ther- mal conductivity models of nanofluids. Ten models were selected for each nanofluid Al2O3, SiO2, TiO2, Cu, Ag, and Al, and then four models were proposed to estimate the thermal conductivity of nanoflu- ids. For the proposed models, the volume fraction is regarded as the best predictor. The nine statistical indicators and global performance indicators are calculated to evaluate different suggested models. For all used nanofluids, the recommended Global Performance Index (GPI) for the model ranges from –6.4197 to 2.5742. The highest GPI represents the best performing model.

Hicham. S. Evaluation of the Spatial Distribution of the Annual Extreme Precipitation Using Kriging and Co-Kriging Methods in Algeria Country. In: Climate Change in Asia and Africa:Examining the Biophysical and Social Consequences, and Society's Responses. IntechOpen ; 2022. Publisher's VersionAbstract

In this chapter, we have conducted a statistical study of the annual extreme precipitation (AMP) for 856 grid cells and during the period of 1979–2012 in Algeria. In the first step, we compared graphically the forecasts of the three parameters of the generalized extreme value (GEV) distribution (location, scale and shape) which are estimated by the Spherical model. We used the Cross validation method to compare the two methods kriging and Co-kriging, based on the based on some statistical indicators such as Mean Errors (ME), Root Mean Square Errors (RMSE) and Squared Deviation Ratio (MSDR). The Kriging forecast error map shows low errors expected near the stations, while co-Kriging gives the lowest errors on average at the national level, which means that the method of co-Kriging is the best. From the results of the return periods, we calculate that after 50 years the estimated of the annual extreme precipitation will exceed the maximum AMP is observed in the 33-year.

3- CHAFAI Nadjib SH. Numerical Study of Natural Convection of Nanofluids in an Inclined Flat Bottom Flask Using Finite-Volume Approach. Iran. J. Chem. Chem. Eng. 2022;41 (7).Abstract

In this work, we study numerically the natural convection of NanoFluids (NF) in an inclined flat bottom flask; it is one of the laboratory flasks used in organic chemistry synthesis. The main reason for this study is to enhance the thermal properties of the reaction medium inside the flat bottom flask and to ameliorate the rate of chemical reactions using nanofluids. The flat bottom wall is maintained at a constant high-temperature Th. While the top, left and right walls of the cavity are maintained at a low-temperature TL. The NF comprises Cu and Al2O3 NanoParticles (NP) suspended in pure water. The governing equations are solved numerically using the finite-volume approach and formulated using the Boussinesq approximation. In this simulation we examined the effects of the NP volume fraction (φ) from 0% to 5%, the Rayleigh number from 103 to 106, the various inclination angles of enclosure (γ=0°,5°,10°, 15°) and the NF type (Cu and Al2O3) on the flow streamlines, isotherm distribution, and Nusselt number. The obtained results show that the addition of Cu and Al2O3 NP increases the mean Nusselt number which enhances the heat transfer in the flat bottom flask and causes significant changes in the flow pattern. In addition, the mean Nusselt number is increased with increasing the Rayleigh number and the volume fraction, and the best results have been obtained from the Cu nanofluid. Also, as the inclination angle increases the mean Nusselt number decreases, and the highest value of the Nusselt number was obtained for a vertical enclosure (γ=0°). The obtained streamlines are mostly symmetric and their values

are generally increased by increasing the Rayleigh number and volume fractions of NPs. Besides, the obtained isotherms generally follow the geometry of the flat bottom flask.

2021
HADJIRA Abdelmounaim SH. A Comparative Study between ARIMA Model, Holt-Winters–No Seasonal and Fuzzy Time Series for New Cases of COVID-19 in Algeria. American Journal of Public Health,. 2021;9 (6) :48-256.Abstract

Coronavirus disease has become a worldwide threat affecting almost every country in the world. The spread of the virus is likely to continue unabated. The aim of this study is to compare between Autoregressive Integrated Moving Average (ARIMA) model, Fuzzy time series and Holt-Winters – No seasonal for forecasting the COVID-19 new cases in Algeria. Methods: Three different models to predict the number of Covid-19 new cases in Algeria were used. The number of new cases of COVID-19 in Algeria during the period from 24th February 2020 to 31th July 2021 was modeled according to ARIMA(4,1,2) model, Five based Fuzzy time series models including the Chen model, Heuristic Huareng model, Singh model, Abbasov-Manedova model and NFTS model, and Holt-Winters – No seasonal. Results: The predictive values were obtained from the 1st August 2021 to 31th December 2021. According to a set of criteria (ME, MAE, MSE, RMSE, U), we found that the FTNS model is the most accurate and best generating model for the values of the number of new cases of Covid-19. Conclusion: To the best of our knowledge, this is the first comparative study of three models of forecasting of Covid-19 new cases in Algeria. This study shows that ARIMA models with optimally selected covariates are useful tools for monitoring and predicting trends of COVID-19 cases in Algeria. Moreover, this forecast will help the Health authorities to be better prepared to fight the epidemic by engaging their healthcare facilities.

2020
Hicham S. Evaluation of diffuse fraction and diffusion coefficient using statistical analysis. Applied Water Science. 2020;10 (6) :1-10.Abstract

In this study, eighty models are proposed in order to estimate the diffuse fraction and diffuse coefficient. For the proposed models, sunshine ratio and clearness index are considered as predictors. Monthly average global and diffuse solar radiation together with sunshine duration data of Tamanrasset station form 1995 to 2017 were analyzed. The different proposed models are compared and statistically analyzed to assess the performance of the best fitted model. Nine statistical indicators and Global Performance Indicator are computed to evaluate different proposed models. It is concluded that the cubic model with sunshine ratio and clearness index is selected as the best accurate model to estimate diffuse solar radiation on a horizontal surface in the study area.

2012
Convection naturelle dans les enceintes: nanofluide. Revue des Energies Renouvelables . 2012;15 (1) :121-130.