Algerian Sahara Sand Dunes Characterization

For a possible use of Saharan sands, representative samples were collected and analysed by several physicochemical methods. The results show that quartz (98 %) is the most represented mineral, while the oxides of aluminium, potassium, iron, chromium and manganese probably are included in a clay phase. The granular analysis enabled the determination of uniformity coefficient (CU) and equivalent diameter. On the other hand, a comparison of the Infrared spectrum of the sand (washed and unwashed) was carried out as well as Scanning Electron Microscopy observations and X-Ray analysis.     

Preparation of new microporous titanium pillared kenyaite materials active for the photodegradation of methyl orange

In recent years, layered silicates have extensively been used to design new nanomaterials through functionalization. In this work, the lamellar sodium silicates magadiite and kenyaite have been hydrothermally synthesized in presence of ethanol as organic co-solvent. Materials of high purity and high crystallinity were obtained after only 24 h of crystallization at a temperature of 180 °C for kenyaite and a temperature of 150 °C for magadiite. It appears that the presence of ethanol in the synthesis medium tends not only to increase the crystallization rate, but also to stabilize the formation of magadiite.The as-synthesized Na-kenyaite was used as precursor for the preparation of titanium pillared clay materials. The resulting microporous titanium oxide pillared kenyaite materials exhibit large specific surface areas up to 180 m² g^?1 with a Ti contents up to 24 wt% and are active for the photocatalytic degradation under UV light irradiation of the organic dye methyl orange in water.     

Periodic homogenization for heat,air, and moisture transfer of porous building materials

ABSTRACT

In this work, a macroscopic model of hygrothermal transfers in porous building materials was developed, using periodic homogenization, where the air infiltration was added to the classical mass and energy balance equations written at the microscopic scale. The corresponding infiltration, hygric, and thermal input parameters were carefully identified. Numerical calculations of thermal and diffusion tensors were performed on a representative concrete elementary cell. Further, the diffusion tensor was compared to the equivalent experimental results available in the literature, and its sensitivity to the water content variations and porosity has been evaluated on the concerned elementary cell.     

A fuzzy C‐regression model algorithm using a new PSO algorithm

In this paper, a new methodology is introduced for the identification of the parameters of the multiple‐input–multiple‐output local linear Takagi‐Sugeno fuzzy models using the weighted recursive least squares (WRLS). The WRLS is sensitive to initialization, which leads to no convergence. In order to overcome this problem, adaptive chaos particle swarm optimization is proposed to optimize the initial states of WRLS. This new algorithm is improved versions of the original particle swarm optimization algorithm. Finally, comparative experiments are designed to verify the validity of the proposed clustering algorithm and the Takagi‐Sugeno fuzzy model identification method, and the results show that the new method is effective in describing a complicated nonlinear system with significantly high accuracies compared with approaches in the literature.     

The adoption of artificial intelligence and robotics in the hotel industry: prospects and challenges

Electronic Markets - The growth of technology has resulted in the use of state-of-the-art systems such as artificial intelligence (AI) and robot-based applications and services in the hotel...     

Design optimization of a solar tower power plant heliostat field by considering different heliostat shapes

The present study focuses on the optimization of solar tower power plant heliostat field by considering different heliostat shapes including rectangular, square, pentagon, hexagon, heptagon, octagon, and circular heliostat shapes. The optimization is carried out using an in-house developed code-based MATLAB program. The developed in-house code is validated first on a well-known PS10 Solar Thermal Power plant having rectangular heliostats shape and the resulting yearly unweighted heliostat field efficiency of about 64.43% could be obtained. The optimized PS10 heliostat field using different heliostat shapes showed that the circular and octagon heliostat shapes provide better efficiency with minimum land area. The yearly efficiency is increased from 69.65% for the rectangular heliostat shape to 70.96% and 71% for the octagon and circular shapes, respectively. In addition, the calculated field area (land area) is reduced for the case of circular and octagon heliostat shapes with a gain of about 11.10% and 10.93% (about 42.0436 × 10³ and 41.4036 × 10³ m²), respectively, in comparison with the PS10 field area.