Ammari F.,Tunis Carthage University |
Ammari F.,French National Institute for Agricultural Research |
Jouan-Rimbaud-Bouveresse D.,French National Institute for Agricultural Research |
Boughanmi N.,Tunis Carthage University |
Rutledge D.N.,French National Institute for Agricultural Research
Talanta | Year: 2012
The aim of this study was to find objective analytical methods to study the degradation of edible oils during heating and thus to suggest solutions to improve their stability. The efficiency of Nigella seed extract as natural antioxidant was compared with butylated hydroxytoluene (BHT) during accelerated oxidation of edible vegetable oils at 120 and 140 °C. The modifications during heating were monitored by 3D-front-face fluorescence spectroscopy along with Independent Components Analysis (ICA), 1H NMR spectroscopy and classical physico-chemical methods such as anisidine value and viscosity. The results of the study clearly indicate that the natural seed extract at a level of 800 ppm exhibited antioxidant effects similar to those of the synthetic antioxidant BHT at a level of 200 ppm and thus contributes to an increase in the oxidative stability of the oil. © 2012 Elsevier B.V.
Abidi H.,Tunis el Manar University |
Ben Abdelghani A.B.,Tunis Carthage University |
Montesinos-Miracle D.,Polytechnic University of Catalonia
Proceedings of the Mediterranean Electrotechnical Conference - MELECON | Year: 2012
This paper presents a new maximum power point tracking (MPPT) strategy for DC/DC converters used in Photovoltaic field. The main advantages of this strategy are the minimization of the needed electrical sensors and its simple implementation. The considered method uses only the PV current sensor. The performances of this proposed MPPT algorithm are verified using a photovoltaic emulator. This emulator is designed based on power converters and is capable to reproduce, in the laboratory, the electrical characteristics of a real PV module without depending on external weather conditions. The usefulness of proposed system is demonstrated through simulation carried out under PSIM environment. © 2012 IEEE.
Ellouzi H.,Tunis Carthage University |
Ben Hamed K.,Tunis Carthage University |
Cela J.,University of Barcelona |
Munne-Bosch S.,University of Barcelona |
Abdelly C.,Tunis Carthage University
Physiologia Plantarum | Year: 2011
Early changes in physiological and oxidative status induced by salt stress were monitored in two Brassicaceae plants differing in their tolerance to salinity, Cakile maritima (halophyte) and Arabidopsis thaliana (glycophyte). Growth response and antioxidant defense of C. maritima under 400 mM NaCl were compared with those of A. thaliana exposed to 100 mM NaCl. Salinity induced early growth reduction that is less pronounced in C. maritima than in A. thaliana. Maximum hydrogen peroxide (H2O2) level occurred in the leaves of both species 4 h after the onset of salt treatment. A rapid decline in H2O2 concentration was observed thereafter in C. maritima, whereas it remained high in A. thaliana. Correlatively, superoxide dismutase, catalase and peroxidase activities increased at 4 h of treatment in C. maritima and decreased thereafter. However, the activity of these enzymes remained higher in treated plants than that in controls, regardless of the duration of treatment, in A. thaliana. The concentrations of malondialdehyde (MDA) reached maximum values at 24 h of salt stress in both species. Again, MDA levels decreased later in C. maritima, but remained high in A. thaliana. The contents of α-tocopherol remained constant during salt stress in C. maritima and decreased during the first 24 h of salt stress and then remained low in A. thaliana. The results clearly showed that C. maritima, in contrast to A. thaliana, can rapidly evolve physiological and antioxidant mechanisms to adapt to salt and manage the oxidative stress. This may explain, at least partially, the difference in salt tolerance between halophytes and glycophytes. © Physiologia Plantarum 2011.
Riahi A.,Tunis Carthage University |
Hdider C.,Tunis Carthage University
Scientia Horticulturae | Year: 2013
In this study, the antioxidant properties of two tomato cultivars Firenze and Rio Grande grown organically in an open-field under different combinations of organic fertilizer sources were investigated, lycopene, total phenols and flavonoids contents, as well as lipophilic, hydrophilic and total antioxidant activities were determined. Significant differences were found between tomato cvs in lycopene and antioxidant activity. Firenze cv showed higher lycopene, lipophilic, hydrophilic and total antioxidant activities when compared to cv Rio Grande. On the other hand, even though antioxidant activity was affected by the different organic fertilizer treatments, tomato bioactive compounds were not affected whatever the cv. LAA ranged from 123.8 μM Trolox/100. g fresh weight (fw) in cv Rio Grande to 153.4 μM Trolox/100. g fw in cv Firenze and was significantly correlated to lycopene (r= 0.45; p< 0.05) content. HAA ranged from 81.5 μM Trolox/100. g fw in cv Rio Grande to 101.3 μM Trolox/100. g fw in cv Firenze and was not significantly correlated to total phenols and flavonoids contents. Although these data require confirmation over a longer period of time, this investigation emphasizes the satisfactory organic tomato antioxidant attributes. © 2012 Elsevier B.V.
Jebara S.B.,Tunis Carthage University
BIOSIGNALS 2013 - Proceedings of the International Conference on Bio-Inspired Systems and Signal Processing | Year: 2013
This paper focuses on the classification of speech sequences into two classes: healthy speech and esophageal speech. Two kinds of features are selected: those based on speaker speech production mechanism and those using listener auditory system properties. Two classification strategies are used: the Discriminant Analysis and the GMM based bayesian classifier. Experiments, conducted with a large database, show classification accuracy using both features. Moreover, auditory based features are the best since error rates tend to be null.
Naoui F.B.,Manouba University |
Zaiem I.,Tunis Carthage University
International Journal of Pharmaceutical and Healthcare Marketing | Year: 2010
Purpose: The purpose of this paper is to study the theoretical foundation of the relationship quality concept and loyalty, and to study the relationship between relationship quality, its antecedents and loyalty. Design/methodology/approach: An empirical study was conducted in the parapharmaceutical sector. Data collection was carried out through the direct administration of a questionnaire to a sample of 300 pharmacists dealing with sales representatives of the parapharmaceutical products. Findings: The results show that there is a significant relation between the antecedents of relationship quality, namely, interpersonal communication, relational contact, conflict resolution and client-oriented behavior, and relationship quality itself. Relationship quality has also an impact on loyalty which is accounted for positively by satisfaction, and negatively by affective conflict. Research limitations/implications: The authors limited the scope of the study to purifying measurement scales and testing the links between the various concepts. Practical implications: The paper sheds light on the action leverages that suppliers have to work on so as to improve the quality of their relation with their clients. Originality/value: Compared to most previous research works which did not go beyond the probing of antecedents of relationship quality separately, the most important contribution of the study lies in taking into account some important antecedents in the study of the influence of antecedents of relationship quality on each dimension of relationship quality. © Emerald Group Publishing Limited.
Kardous Z.,Tunis Carthage University |
Braiek N.B.,Tunis Carthage University
Journal of the Franklin Institute | Year: 2015
The sliding mode control of uncertain homogeneous bilinear systems is the main interest of this paper. Modelling is based on TS-bilinear approach. A sliding mode multimodel control is suggested and a stability study is conducted leading to sufficient conditions of global stabilization. Simulations on numerical examples are presented to prove the effectiveness of the proposed approach. © 2014 The Franklin Institute.
Maaloul S.,Tunis Carthage University |
Afif M.,Tunis Carthage University |
Tabbane S.,Tunis Carthage University
Proceedings - 27th International Conference on Advanced Information Networking and Applications Workshops, WAINA 2013 | Year: 2013
The integration of heterogeneous wireless networks allows the users to benefit simultaneously from these radio access technology (RAT) and they can also use an important number of applications. New applications constraints are more complex and may be change dynamically and rapidly under time. The handover mechanism is responsible to guarantee the required quality of service when users roam across different RAT in order to provide an ubiquitous environment. With the diversification of the context metrics allowed by these networks, the level of computationally and complexity has a direct impact on the perceived quality of service especially of the network selection process on application performance. The present work addresses the network selection process, which is probably the most important key of the vertical handover decision mechanism. It proposes a modification of the Simple Additive Weighting called Enhanced-Simple Additive Weighting (E-SAW) for ranking networks that avoid computational cheaper by eliminating network access which does not satisfy a minimum required context. After ranking, in order to avoid bad network selection which does not respond to user requirement, we define handover decision scheme that improves network performances perceived by end users and avoid the processing delay caused by unnecessary handover. © 2013 IEEE.
Ben Jebara S.,Tunis Carthage University
European Signal Processing Conference | Year: 2014
The purpose of this work is to discriminate between smoker and non-smoker speakers by analyzing their voice. In fact, the vocal folds, the main organ responsible of producing voice, is damaged by smoke so that its structure and its vibration are altered. Some bio-mechanical features, describing vocals folds behavior and status are used. They are based on the two-mass model which characterizes vocal folds by the mass, the stiffness and the losses of their cover and body parts. Bio-mechanical features of smokers and non-smokers are analyzed and compared to select relevant features permitting to discriminate between the two categories of speakers. The Quadratic Discriminant Analysis is used as a tool of classification and shows a relatively good rate of detection of smokers. © 2014 EURASIP.
Ben Jebara S.,Tunis Carthage University
European Signal Processing Conference | Year: 2014
This paper deals with noise removal in ElectroMyoGram (EMG) signals acquired in the hostile noisy environment of functional Magnetic Resonance Imaging (fMRI). The noise due to magnetic fields and radio frequencies corrupts significantly the EMG signal which render its extraction very difficult. The proposed approach operes in the frequency domain to estimate the noise spectrum to subtract it from noisy observation spectrum. The noise estimation is based on spectral minima tracking in each frequency bin without any distinction between muscle activity and muscle rest. But it looks for connected time-frequency regions of muscle activity presence to estimate a bias compensation factor. The method is tested with a simulated noisy observation in order to evaluate its performance using objective criteria. It is also validated for real noisy observations where no clean is available. © 2014 EURASIP.