Mechlouch R.F.,Gabes University |
Elfalleh W.,Institute Des Regions Arides Of Medenine |
Ziadi M.,Institute National Des Science Appliquees Et Of Technology Insat |
Hannachi H.,Institute Des Regions Arides Of Medenine |
And 4 more authors.
International Journal of Food Engineering | Year: 2012
The aim of this work is to study the physico-chemical properties of dried tomatoes, variety Rio grande using direct solar dryer (DSD), open-air sun drying (OASD) and microwave drying (MW) with three output powers density (1w/g; 2w/g; 3w/g) at different temperatures (57, 67°C). Radical scavenging activity of tomatoes extracts was investigated. Results indicated that drying tomatoes by microwave (3W/g; 67°C) is faster than open-air sun drying (OASD) and direct solar dryer (DSD). The studied parameters (moisture, pH, Brix, total phenolics, total flavonoids, and carotenoids content) were significantly affected by different drying processes, with minimal effects on pH. The highest activity against the DPPH radical oxidation is investigated in methanolic extracts of tomatoes dried by direct solar dryer (DSD). Nevertheless, the highest ABTS value was observed in methanolic extracts of tomatoes dried by microwave (MW) with 3w/g at 57°C. © 2012 De Gruyter. All rights reserved.
Mustafa H.,Azzawia University
Defect and Diffusion Forum | Year: 2013
Absorption phenomenon of ammonia vapor into ammonia water solution has been investigated experimentally, by allowing superheated ammonia vapor to flow into a test cell containing a stagnant pool of ammonia water solution. Before commencing the experiment, the pressure in the test cell P1i, corresponds to the equilibrium vapor of the ammonia-water system at room temperature and initial mass fraction Ci. When the valve is opened, mechanical equilibrium is established quickly and the pressure in the test cell becomes equal to that of the ammonia vapor cylinder. The difference between the initial pressure in the vapor cylinder and the initial pressure in the test cell ΔPi is found to have a major influence on the absorption rate . The interface temperature can be estimated for a transient case, by help of an inverse solution proposed by Monde . The interface concentration Cint obtained by measured ammonia vapour pressure and the estimated interface temperature. The main objective of this study is to investigate the effect of the initial pressure difference and the initial concentration on the interface concentration. A correlation which gives the interface concentration as a function of the initial concentration, the initial pressure difference and time is derived. In addition, the absorbed mass at no pressure difference could be estimated from the absorbed mass at initial pressure difference. © (2013) Trans Tech Publications, Switzerland.
Mezughi K.,Azzawia University |
Tizaoui C.,University of Swansea |
Alkhatib M.F.,International Islamic University Malaysia
Advances in Environmental Biology | Year: 2014
Organic contaminants from industrial and/or domestic effluents may be harmful to humans directly or indirectly by degrading the quality of the environment. Consequently these contaminants must be reduced to levels that are not harmful to humans and the environment before disposal. Among the available chemical methods heterogeneous photocatalytic oxidation has been found particularly to be effective in removal of large number of persistent organics in water. Degradation of the organics was achieved by exposing synthetic effluents to UV light in a photocatalytic reactor in a dark compartment in the presence of catalyst. The degradation of RO16 was conducted at pH 5.5, 24 hr, 294 K and lamp power of 200 W. RO16 was prepared in 200 ml dye solution with concentrations of 20, 40 and 60 mg/L and the degradation took place in presence of TiO2 at concentrations of (0.5-4.0) g/L. While photolysis (in absence of TiO2) was found to have no effect on the degradation of RO16, photocatalysis (in presence of TiO2 catalyst) degraded the dye to 0.4 mg/L. © 2014 AENSI Publisher All rights reserved.
El-Hefian E.A.,Azzawia University |
Nasef M.M.,University of Technology Malaysia |
Yahaya A.H.,University of Malaya
E-Journal of Chemistry | Year: 2012
Chitosan/agar (CS/AG) films were prepared by blending different proportions of chitosan and agar (considering chitosan as the main component) in solution forms. The chemical structure and the morphology of the obtained blended films were investigated using Fourier transform infrared (FTIR) and field emission scanning electron microscope (FESEM). It was revealed that chitosan and agar form a highly compatible blend and their films displayed homogenous and smooth surface properties compared to the individual pure components.
Amer B.,Azzawia University |
Atia M.M.,Queens University |
Hefhawi M.,Azzawia University |
Noureldin A.,Queens University |
Noureldin A.,Royal Military College of Canada
Institute of Navigation International Technical Meeting 2015, ITM 2015 | Year: 2015
ZigBee wireless sensor networks has the benefit of superior optimization in power consumption and extremely long battery life. In near future, the handheld devices are expected to incorporate support for wireless sensor networks technology, and these devices can become active elements in ZigBee-based applications such as automated buildings and advanced metering systems. Use of these applications is also promising for the expansion of location services into environments that do not have access to Global Navigation Satellite Systems (GNSS). Compared with the ToA (Time of Arrival) and TDoA (Time difference of Arrival) methods, RSSI (Received Signal Strength Indicator) has several advantages. It does not require additional hardware. Owing to the simplicity of RSSI, the most recent studies on localization using wireless sensor networks use RSSI-based algorithms. Previous works RSSI-based location estimation methods discussed by the literature depend on the impractical assumption that signal propagation characteristics are known and independent of both time variations and the environment. That assumption is invalid for the complex structures of indoor areas, which make the signal propagation characteristics for the same node differ significantly based on the orientation, even if the radiation pattern of the node is omnidirectional. Additionally, obtaining knowledge about signal propagation characteristics requires using manual data collection, which is impractical and time consuming. Furthermore, location estimation techniques must consider the large variations and high degree of uncertainty in RSSI observations. In this paper, we developed an adaptive localization system with low power and low cost, IEEE 802.15.4 ZigBee WSN. The under investigated system does not require manual pre-data collection and operates without performing exhaustive radio surveys. The first contribution in this paper is involving Kalman filtering for RSSI smoothing. Secondly, estimation of multi-link signal propagation characteristics; path loss exponent and Gaussian random variable in real-time by utilizing Particle Swarm Optimization (PSO). The results from the experiments are taken show that using the proposed multi-link channel decomposition estimation technique is more effective than using only one fixed value of PLE and X0. The overall localization accuracy is within two meters in root mean square.