In the current investigation, AA2024 aluminum alloy is reinforced by alumina nanoparticles using a friction stir process (FSP) with multiple passes. The mechanical properties and microstructure observation are conducted experimentally using tensile, microhardness, and microscopy analysis methods. The impacts of the process parameters on the output responses, such as mechanical properties and microstructure grain refinement, were investigated. The effect of multiple FSP passes on the grain refinement, and various mechanical properties are evaluated, then the results are conducted to train a hybrid artificial intelligence predictive model. The model consists of a multilayer perceptrons optimized by a grey wolf optimizer to predict mechanical and microstructural properties of friction stir processed aluminum alloy reinforced by alumina nanoparticles. The inputs of the model were rotational speed, linear processing speed, and number of passes; while the outputs were grain size, aspect ratio, microhardness, and ultimate tensile strength. The prediction accuracy of the developed hybrid model was compared with that of standalone multilayer perceptrons model using different error measures. The developed hybrid model shows a higher accuracy compared with the standalone model.

Aluminum AA7075, graphene nanoplates (GNP), boron nitride (BN), and vanadium carbide (VC) are used to fabricate hybrid nanocomposite matrices. BN and VC serve as secondary reinforcement particles in the fabrication of hybrid composites, with graphene (GNP) as a key component of the hybrid process. Friction stir processing (FSP) was used to manufacture the composite matrix; it also has a major role in improving the microstructure’s grain refinement, as well as the reinforcing of the particles, which play a crucial role in limiting grain growth during the dynamic recrystallization process. Consequently, the grain sizes of the nanocomposite AA7075/GNPs, hybrid composites AA7075/GNPs+BN, and hybrid composites AA7075/GNPs+BN+VC were decreased by an average of 10.3 times compared to the base alloy. The SEM analysis demonstrated that the dispersion of the hybrid reinforcement particles was performed, and the particles were dispersed uniformly throughout the metal matrix. The mechanical characteristics of the hybrid AA7075/GNPs+BN+VC include the highest compression stress and hardness values due to the homogeneity of the hybridization process between the BN and VC particles. The GNPs reduce the electrical conductivity by 7.3% less than the base alloy. In comparison, when hybridized with BN and VC, it is reduced by 24.4% and 31.1%, respectively. In addition, the inclusion of thermally insulating materials, such as BN and VC, decreases the thermal conductivity of the hybrid composite metal matrices.

Twenty percent of the world’s energy is consumed by the construction sector, including commercial and residential buildings, where 13% is consumed by the residential sector only. Half of the total energy consumed by buildings in Saudi Arabia is specifically attributed to the hot summer season, which, unlike in many other countries in the Middle East, continues for more than 5 months annually. The use of a phase change material (PCM), as an insulator in building materials, can be a solution to provide a comfortable indoor temperature and reduce energy consumption. This study examined two different melting ranges for PCMs RT35 and RT35HC inserted into hollow clay bricks to investigate their thermal behavior and heat storage capacity and compare them with polystyrene foam. To perform this experiment, four chambers were constructed using cement plastering. The data were collected at Jeddah, Saudi Arabia, from mid-November 2020 to the end of February 2021. When the highest temperature was reached during the experiment, PCM RT35 provided a better cooling effect by 13% compared to 24% and 28.56% for PCM RT35HC and foam, respectively, compared to hollow bricks alone. However, when the lowest temperature was reached during the experiment, PCM RT35HC performed better than the other chambers in saving energy and keeping the chamber warm, which was 9.5% for the reference chamber, 7.0% for the foam chamber, and 2.8% for PCM RT35. The maximum energy saving of PCM RT35 was around 1920 kJ, which is around 0.533 kWh, for one wall only, and for PCM RT35HC, it was 2880 kJ, or 0.8 kWh, which can reduce energy consumption of the HVAC system by 97 kWh/m² and 146 kWh/m² per year, respectively.

The uniaxial compressive strength is an important parameter in selecting and design of rock and brittles structure. Protection of ancient monuments or historic structure has a great intense in material science point of view. Limestone is commonly rock material which has a great sense in historical buildings and temples. The strength of this material may be influenced by natural weathering like moisture, rains and varying temperature. Samples of ancient limestone rock are coated with Paraloid B44, Paraloid B72, ethyl silicate and Wacker OH100. The results concluded that both Wacker OH100 and Paraloid B44 coating material have more efficient and give considerable protection when the sample is immersed in salinity water for a week. The compressive strength of limestone decreases due to water action. Water absorption, porosity, and rock density are enhanced with the coating process.