Numerical and Experimental Study of the Impact of Key Parameters on a PVT Air Collector: Mass Flow Rate and Duct Depth

The PVT-air solar system simultaneously generates electrical and thermal energy. Therefore, increasing the cost-effectiveness of the system requires an appropriate choice of key parameters such as mass flow rate and air channel depth. In this paper, a PVT-air kit of a single module with a 30° slope was used to measure photovoltaic electricity and air heating power in the city of Sfax, Tunisia. Besides, a computer method was implemented using the ANSYS Fluent 17.0 software and the MATLAB program to analyse the properties of the airflow and to characterise PVT-air yields under different mass flow rates and depths. From the comparison of numerical and experimental data, the numerical method was validated with a good agreement. Indeed, we have found that increasing of the airflow rate improves the thermal efficiency with a slight change on electrical output. However, the reduction in depth shows an improvement on thermal efficiency and a negligible effect on electrical efficiency. Also, we have presented the thermal and electrical performance of PVT-air as a function of the key parameters with the Hottel-Whillier-Bliss formulation.     

Pleurotusostreatus and Agaricus subrufescens: investigation of chemical composition and antioxidant properties of these mushrooms cultivated with different handmade and commercial supplements

In this study, the chemical composition, total phenolic content and antioxidant activity (DPPH, ORAC and FRAP assays) of A. subrufescens and P. ostreatus, cultivated with handmade and commercials supplements, were compared. Additionally, the compounds ergosterol, saccharopine, and hexitol were identified in A. subrufescens by HPLC-MS/MS. The antioxidant compound p-coumaric acid and dihexoses was found in both mushroom species. A. subrufescens presented higher total phenolic content (73.8 ± 0.6 mg GAE 100 g⁻¹) and antioxidant activity than P. ostreatus (16.6 ± 0.5 mg GAE 100 g⁻¹). The handmade supplement based on the waste of noble grains presented statistically similar phenolic content to the mushrooms cultivated with commercial ones Spawn Mate II SE (86.1 ± 1.4 and 92.9 ± 0.3 mg GAE 100 g⁻¹, respectively). Therefore, the results support the use of handmade supplements based on agro-wastes as a viable alternative to the use of high-cost commercial ones.     

An optimal control of a wastewater treatment reactor by catalytic ozonation

This paper deals with the control of a wastewater treatment pilot by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The objective of this study focuses on the optimization of the catalytic ozonation reactor. A continuous-time transfer function model is identified to represent the pilot behavior, and an optimal control is proposed to obtain a significant abatement of the pollutant. In this application, the pollutant abatement is represented by the absorbance.     

An Evaluation of Routing Protocols for Vehicular Ad-Hoc Network Considering the Video Stream

Wireless Personal Communications - In promising application field such as Vehicular Ad hoc Networks, the ability of the driver to exchange video streams smoothly over the network regardless of his...     

Hypergraph imaging: an overview

Hypergraph theory as originally developed by Berge (Hypergraphe, Dunod, Paris, 1987) is a theory of finite combinatorial sets, modeling lot of problems of operational research and combinatorial optimization. This framework turns out to be very interesting for many other applications, in particular for computer vision. In this paper, we are going to survey the relationship between combinatorial sets and image processing. More precisely, we propose an overview of different applications from image hypergraph models to image analysis. It mainly focuses on the combinatorial representation of an image and shows the effectiveness of this approach to low level image processing; in particular to segmentation, edge detection and noise cancellation.     

Analyse de la stabilité spectrale d’un laser DFB à trois sauts de phase (3PS-DFB)

The aim of this article is to analyze the spectral stability of the three phase shift distributed feedback (3ps-dfb) laser by using Time domain model (tdm). We have developed a software that simulates static and dynamic properties of distributed feedback (dfb) multi-sections laser at large signal. The best single-mode stability operation up to 18mW of the 3ps-dfb is achieved for three phase shifts at (π, π, π) whatever the phase position. These results showed that the 3ps-dfb laser was a much more suitable structure to realize stable single-mode high-power operation for a coherent optical communication system.     

Atomistic study of structural, elastic, electronic and thermal properties of perovskites Ba(Ti,Zr,Nb)O3

The full-potential linearized augmented plane waves (FP-LAPW) method based the on density functional theory (DFT) using the generalized gradient approximation (GGA) is applied to study the structural, mechanical, and electronic properties of BaTiO₃, BaZrO₃, and BaNbO₃ cubic perovskites. The quasi-harmonic Debye model, by means of total energy versus volume calculations obtained with the FP-LAPW method, is applied to study the thermal and vibrational effects. Predicted temperature and pressure effects on the structural parameters, thermal expansions, heat capacities, and Debye temperatures are determined from the non-equilibrium Gibbs functions.