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Nebbali R.,Mouloud Mammeri University | Roy J.C.,University of Franche Comte | Boulard T.,French National Institute for Agricultural Research
Renewable Energy | Year: 2012

This article presents numerical simulations of the distribution of climate parameters within a ventilated tunnel tomato greenhouse during variable outside conditions. The simulations were performed using a computational fluid dynamics (CFD) code that solved the transport equations in a 3D domain, including the greenhouse and its crop stands, the surrounding ambient air and the soil located directly under the greenhouse. Radiative heat transfers were modeled using a bi-band discrete ordinates (DO) model, and the crop was considered to be a porous medium. Sensible and latent heat transfer between leaves and the surrounding air were determined based on the energy balance that included longwave and shortwave radiation fluxes in each crop control volume. The climatic boundary conditions were determined using experimental measurements, and the sun position was calculated for each time interval that was considered. The temperature distribution in the soil was determined based on a preliminary CFD determination of the conductive heat transfer in a 1D soil column. Simulations in the entire 3D domain were then performed, and 1h time step and boundary conditions were updated prior to each calculation procedure. Results are presented for the spring equinox and summer solstice. These results highlight the combined influence of sun position, wind direction and intensity on the greenhouse microclimate and especially on the evapotranspiration rate of the crop at the leaf level. We discuss the possibility of using CFD code integration as a conceptual tool for designers or in association with a control climate model for farmers. © 2011 Elsevier Ltd.

Aiche F.,Mouloud Mammeri University | Dubois D.,French National Center for Scientific Research
Communications in Computer and Information Science | Year: 2012

This paper deals with methods for ranking fuzzy intervals in connection with probabilistic and interval orderings. According to the interpretation of a fuzzy interval, various such extensions can be laid bare. In this paper, we especially consider extensions of probabilistic orderings using possibilistic interpretations of fuzzy intervals, crisp substitutes thereof, and gradual numbers. This framework can encompass the comparison of fuzzy random variables: coupling one form of probabilistic comparison with one form of interval comparison induces a method for ranking random fuzzy intervals. © 2012 Springer-Verlag Berlin Heidelberg.

Guenin E.,University of Paris 13 | Meziane D.,Mouloud Mammeri University
Current Organic Chemistry | Year: 2011

While microwave dielectric heating had been widely exploited in several organic chemistry areas to accelerate and improve reactions yields, it has not been often applied to phosphorus chemistry since the beginning of the 21st century. Recently, there has been an important increase in the number of reported uses of microwave in several fields of phosphorus chemistry. This review focuses on a literature survey of the uses of microwave "flash heating" in this chemistry area. Where possible, the relative advantages of this methodology will be compared to classical heating. © 2011 Bentham Science Publishers.

Khled khoudja N.,Mouloud Mammeri University | Boulekbache-Makhlouf L.,University of Abderrahmane Mira de Béjaïa | Madani K.,University of Abderrahmane Mira de Béjaïa
Industrial Crops and Products | Year: 2014

The present study was carried out to evaluate the antioxidant capacity of the aerial parts of ethanol crude extracts and their four solvent fractions (hexane (HF), ethyl acetate (EAF), butanol (BuOHF), and aqueous (WF)) of three selected Algerian Lamiaceae: Calamintha clinopodium, Teucrium flavum and Thymus algeriensis. The extracts of the three Lamiaceae were evaluated for their total phenols, flavonoids, flavonols content and antioxidant activity (reducing power, total antioxidant capacity, DPPH radical and hydrogen peroxide scavenging effect). WF of T. algeriensis was the most effective fraction with 75.13mgascorbic acid equivalent (AscA E)/g of powder for reducing power, and 218.37mg(AscA E)/g of powder for total antioxidant activity. It also showed the highest DPPH and hydrogen peroxide scavenging capacities with IC50 values of 0.01 and 0.08mg/mL, respectively. Moreover, WF of T. algeriensis exhibited higher total phenolic content (99.21mggallic acid equivalent (GAE)/g of powder). Aqueous fraction of T. algeriensis has a strong ability to act as antioxidant, and may be considered as a natural source of active compounds. © 2013 Elsevier B.V.

Djennoune S.,Mouloud Mammeri University | Bettayeb M.,University of Sharjah | Bettayeb M.,King Abdulaziz University
Automatica | Year: 2013

Nowadays, the control of fractional-order system is one of the most popular topics in control theory. Recent studies have demonstrated the interest of fractional calculus both for systems modeling in many areas of science and engineering and for robust controller design. Thus, several research contributions have been devoted to the extension of control theory to fractional-order systems. Synergetic control was introduced in power electronics and other industrial processes. The benefit of this control scheme has been recognized for both integer-order linear and nonlinear systems. In this paper, a fractional-order synergetic control for fractional-order systems is proposed. Both linear and nonlinear cases are considered. The macro-variable is defined by the fractional-order integral of state variables. Optimality and stability properties are analyzed. A numerical example is investigated to confirm the effectiveness of the proposed method. © 2013 Published by Elsevier Ltd.

Djouadi Y.,Mouloud Mammeri University | Prade H.,University Paul Sabatier
Fuzzy Optimization and Decision Making | Year: 2011

Formal concept analysis (FCA) associates a binary relation between a set of objects and a set of properties to a lattice of formal concepts defined through a Galois connection. This relation is called a formal context, and a formal concept is then defined by a pair made of a subset of objects and a subset of properties that are put in mutual correspondence by the connection. Several fuzzy logic approaches have been proposed for inducing fuzzy formal concepts from L-contexts based on antitone L-Galois connections. Besides, a possibility-theoretic reading of FCA which has been recently proposed allows us to consider four derivation powerset operators, namely sufficiency, possibility, necessity and dual sufficiency (rather than one in standard FCA). Classically, fuzzy FCA uses a residuated algebra for maintaining the closure property of the composition of sufficiency operators. In this paper, we enlarge this framework and provide sound minimal requirements of a fuzzy algebra w.r.t. the closure and opening properties of antitone L-Galois connections as well as the closure and opening properties of isotone L-Galois connections. We apply these results to particular compositions of the four derivation operators. We also give some noticeable properties which may be useful for building the corresponding associated lattices. © 2011 Springer Science+Business Media, LLC.

Amarni F.,Mouloud Mammeri University | Kadi H.,Mouloud Mammeri University
Innovative Food Science and Emerging Technologies | Year: 2010

Microwave-assisted solvent extraction (MASE) of oil from olive cake can be used as an alternative for conventional solvent extraction (CSE).The present research showed that, compared to the CSE, the MASE gave better yields within very short times. The results obtained with this new procedure indicated that the radiation power and exposition time enhanced extraction ability. The Patricelli model has been applied to describe the MASE kinetic. The coefficients of determination were found to be very high in all the cases (R2 ≥ 0.992) indicating a good fit of the experimental data at tested conditions. The results obtained were compared with those given by the same model in the case of the conventional extraction. Industrial relevance: Olive cake pollutes the environment around the Mediterranean basin where it is generated in great amounts within a short period (from November to March). To avoid this pollution, it must be treated. Its valorization by recovery of its residual oil using conventional solvent extraction is time-consuming and needs large volumes of solvent. Compared to this conventional technique, the microwave-assisted solvent extraction can be a nice alternative because it gives better yields within short times and consumes less solvent. © 2010 Elsevier Ltd. All rights reserved.

Meziane S.,Mouloud Mammeri University
Food Science and Technology International | Year: 2013

A statistical methodology, combining Plackett-Burman design with Box-Behnken design, was applied to optimize the oil extraction process from olive pomace using hexane as solvent. Plackett-Burman design was used in the first step to evaluate the effects of five independent variables on the oil extraction yield. Temperature of extraction, time of contact, solvent-to-solids ratio and moisture content of the olive pomace were identified as significant independent variables and were further optimized by using response surface methodology based on Box-Behnken design. The optimized conditions to maximize the yield were as follows: extraction temperature at 33 °C, contact time at 10 min, solvent-to-solids ratio at 3.5 mL/g and moisture content at 13%. The experimental value of the yield (5.98%) at these optimum conditions was found in perfect agreement with the value predicted by model (5.80%). © The Author(s) 2012.

Dahmani L.,Mouloud Mammeri University
Strength of Materials | Year: 2011

The reinforced concrete tanks for liquefied natural gas storage, which have many advantages over steel tanks (high resistance to cryogenic temperatures and thermal shock, fatigue and buckling, fire resistance, etc.), are analyzed. Since the main drawback of concrete tanks is their poor resistance to tensile stresses, in order to investigate the thermally induced tensile stresses, a numerical model of a transient thermal analysis is presented for the evaluation of thermomechanical response of concrete tank to the cryogenic temperature, taking into account the temperature dependence of the thermophysical properties of the concrete tank thermal conductivity and specific heat. © 2011 Springer Science+Business Media, Inc.

Meziane S.,Mouloud Mammeri University
Energy Conversion and Management | Year: 2011

Drying kinetics of olive pomace was investigated in a fluidized bed dryer. The drying experiments were performed at different temperatures of the drying air (50, 60, 70 and 80 °C) and bed heights of the sample (41, 52, and 63 mm), using a constant air velocity of 1.0 m/s. A constant rate period was not observed in the drying of olive pomace; all the drying process occurred in falling rate period. Ten thin layer drying models were evaluated and fitting to the experimental moisture data. The fit quality of the models was evaluated using the determination coefficient, chi-square, and root mean square error. Among the selected models, the Midilli et al. model was found to be the best model for describing the drying behaviour of olive pomace. For all drying experiments, the effective diffusivity values were found to be varying between 0.68 and 2.15 × 10-7 m2/s depending on air temperature and bed height of the sample. The activation energies were 34.05, 36.84 and 38.10 kJ/mol for 41, 52 and 63 mm bed height of the sample, respectively. © 2010 Elsevier Ltd. All rights reserved.

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