Elkamel R.,Tunis Carthage University |
Cherif A.,Tunis el Manar University
International Journal of Communication Systems | Year: 2017
The energy consumption is considered to be the major challenge in wireless sensor networks. In this paper, we shed light on a new approach to overcome the energy consumption problems. The objective of this work is to integrate an improved algorithm which is the K-means to create a balanced energy on clusters and to use the Gaussian elimination algorithm during the election of cluster head that will guarantee the distribution of energy consumption. To address the problem of the optimal number of groups, we use Davies Bouldin index to increase the network lifetime. The simulation result shows that the proposed protocol extends the network lifetime compared to Leach, iMod-Leach, leach-C, and CELRP. © 2017 John Wiley & Sons, Ltd.
Chihaoui I.,Tunis Carthage University |
Ammari M.L.,Tunis Carthage University
2016 International Symposium on Signal, Image, Video and Communications, ISIVC 2016 | Year: 2017
The antenna selection technology has become essential for massive multiple-input multiple-output (MIMO) systems since it allows us to benefit from the massive increase in the number of antennas without a necessary use of additional RF components. However, reducing the number of active antennas may exhibit a performance loss regardless of the used antenna selection technique. In this paper, we propose a low-complexity and near maximum-likelihood (ML) performance achieving receiver for large MIMO systems with antenna selection. The proposed approach is based on the likelihood ascent search (LAS) algorithm and allows to increase the system performance in terms of bit error rate (BER). The performance of the proposed detector is analyzed by Monte-Carlo simulations. Numerical results show that our technique provides a gain of about 1 dB. © 2016 IEEE.
Guizani Z.,Tunis el Manar University |
Hamdi N.,Tunis Carthage University
International Journal of Network Management | Year: 2017
The world of telecommunication is witnessing a swift metamorphosis towards fifth generation cellular networks. Particularly, the rapid shift from a user centric to a device centric communication has created a tremendous impact on service complexity and network requirements. The future networks present requisite needs in ubiquitous throughput, low latency, and high reliability. They are also envisioned to provide energy efficiency, spectrum reuse, network scalability, and robustness as well as improved quality of user experience, which proves to be of ultimate importance. Accordingly, government, academic, and industrial institutions are working together to fulfill these challenging goals. Their research efforts have been extensively reported in various topics and directions, such as heterogeneous small cell networks, millimeter wave communication, massive multiple input multiple output, network function virtualization, software-defined network, and device-to-device communication. More interestingly, a revolutionary network architecture based on cloud computing and centralized processing is adopted as one of the best candidates for fifth generation. It is denoted Cloud Radio Access Network (CRAN) and (H-CRAN) in heterogeneous networks. An upgraded version, namely, Fog RAN (F-RAN), with caching and fog computing capabilities is also presented. Environmental friendly, it ensures flexibility and scalability with reduced expenditures. This paper presents the aforementioned key technological functionalities and surveys the benefits and challenges of CRAN, H-CRAN, and F-RAN. © 2017 John Wiley & Sons, Ltd.
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.
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.