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Oum el Bouaghi, Algeria

Bennamoun L.,University of Oum El Bouaghi
Renewable and Sustainable Energy Reviews

Drying constitutes an important process for wastewater sludge management, as it can reduce the mass and the volume of the product and consequently the cost of storage, handling and transport. During constant operating conditions, the drying kinetic of the sludge has shown mainly: a constant drying rate, one or two falling rate periods and a final short period with variations along the process of the physical properties of the product with the appearance of shrinkage and cracks phenomena. Solar drying was benefit as using free solar energy can reduce the cost of the operation. On the other hand, it plays an important role for the pathogen reduction until Environmental protection Agency (EPA) recommendations. In some studied cases, the value of 1000 CFU g -1 DS, which represents the EPA Class A pathogen requirement, for fecal coliform was attained. The general design of used solar dryers was constituted of: a greenhouse made with transparent material and a floor, where the product is speared in thick layers. Furthermore, fans and ventilations can be used in order to have homogeneous distribution of the air inside the greenhouse with replacement of humidified air with fresh one. Automatic or handle mix of the product was used once or for several times a day. In order to increase the performances of the drying system, other ways such as heating the floor using solar water heater, infrared lamps, using heat pumps or adding thermal energy storage systems were also tested. Covered solar drying has given better results than open solar drying. However, the origin of the wastewater sludge affects the obtained results. Alternatively, modeling drying systems was effectuated using heat and mass balances, applied for the air and the dried product. Solar drying of wastewater sludge has given satisfactory results. © 2011 Elsevier Ltd. All rights reserved. Source

Mahdad B.,University Mohamed Khider of Biskra | Srairi K.,University Mohamed Khider of Biskra | Bouktir T.,University of Oum El Bouaghi
International Journal of Electrical Power and Energy Systems

The main disadvantage of GAs is the high CPU time execution and the qualities of the solution deteriorate with practical large-scale optimal power flow (OPF) problems. This paper presents an efficient parallel GA (EPGA) for the solution of large-scale OPF with consideration of practical generators constraints. The length of the original chromosome is reduced successively based on the decomposition level and adapted with the topology of the new partition. Partial decomposed active power demand added as a new variable and searched within the active power generation variables of the new decomposed chromosome. The strategy of the OPF problem is decomposed in two sub-problems, the first sub-problem related to active power planning to minimize the fuel cost function, and the second sub-problem designed to make corrections to the voltage deviation and reactive power violation based in an efficient reactive power planning of multi Static VAR Compensator (SVC). Numerical results on three test systems IEEE 30-Bus, IEEE 118-Bus and 15 generation units with prohibited zones are presented and compared with results of others competitive global approach. The results show that the proposed approach can converge to the optimum solution, and obtains the solution with high accuracy. © 2009 Elsevier Ltd. All rights reserved. Source

Bennamoun L.,University of Oum El Bouaghi
Renewable and Sustainable Energy Reviews

Solar drying is one of the processes that have found application in Algeria, because of the important quantities of solar irradiations that can be exploited in this country. Nevertheless, the experience of Algeria in solar drying is recent and limited to drying of fruits, vegetables, medicinal and aromatic herbs. The effectuated review has given an idea about the existing functional dryers in this country with presentation of their different design aspects and in some cases the mathematical modeling for well describing and predicting their behaviours. The solar dryers were classified into two classes according to their operation mode and without taking into account if the dryers are using auxiliary sources of energy. The two classes are: passive dryers and active dryers. On the other hand, each class was divided into subclasses representing the type. We have found the direct and indirect types for the passive dryers, but only indirect types for the active dryers. Mixed types were not developed. The solar dryers were developed and tested in two different climatic regions which are the north of the country and the Sahara. In the most studied cases, one or multiple auxiliary sources of energy were used in order to increase the performances of the dryer or to decrease drying time. Consequently, we register the utilization of pebbles as a heat storage system, resistances as electrical heater, gas-ring and photovoltaic cells in order to give independency against the use of the traditional electrical energy. In the case of the active dryers, adding fans and temperature and flow controllers has permitted the control of the drying conditions. Depending on the dryers, the dried quantities vary from 200 g to 36 kg. Comparison between many studied cases for different modes and types and with open sun drying method was furthermore done. With a few exceptions to some solar dryers which present problems of complexity and was not practical and easy for manipulation to the agricultural producer, the majority of the developed solar dryers have presented satisfactory results. © 2011 Elsevier Ltd All rights reserved. Source

Nini B.,University of Oum El Bouaghi
Informatica (Slovenia)

This paper presents a novel algorithm for a color image encryption which involves simultaneously two operations in one: permutation and substitution of pixels. It uses the rows and columns of images' bits as transformation units. Each bit is regarded as an observed entity having a light ray which intersects a new rotated image. The intersection position is used to paste the corresponding bit. Such projection makes the pixels' bits migrate between each other which generate a cipher image. Despite its simplicity, the algorithm shows a great resistance against many kinds of attacks through its sensitivity to the initial values used in encryption. Source

Barra K.,University of Oum El Bouaghi | Rahem D.,University of Oum El Bouaghi
Energy Conversion and Management

The paper presents an improved predictive power control for a photovoltaic conversion chain connected to a grid based on finite states space model of the converter. The proposed control algorithm selects the switching state of the inverter that minimizes the error between active and reactive power predictions to their computed values for all different voltage vectors. The optimal voltage vector that minimizes a cost function is then applied to the output of the power converter. Once the proposed predictive strategy is validated, a multilevel converter is then used to improve and highlight the obtained results. The proposed predictive control strategy uses only one sample time prediction and it is very intuitive since it is very simple and provides best performances compared to other modulation techniques. © 2013 Elsevier Ltd. All rights reserved. Source

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