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China Communications 2020年第4期17卷 19-30页

作者： Mohamed Maalej hichem besbes Higher School of Communications of Tunis University of Carthage2083 El Ghazala ArianaTunisia

In this paper, we provide analytical results on average Symbol Error Probability(SEP) of a Free Space Optics(FSO) link employing M-ary Pulse Position Modulation(PPM), subjected to turbulent atmosphere modeled with Double Generalized Gamma(DGG) distribution. FSO link is generally impaired by turbulent atmosphere and pointing errors. As far as we know, results are presented in previous works by considering the atmosphere turbulence modeled with a Gamma-Gamma distribution. In our work, we also give asymptotic results on average SEP in order to approximate its evolution at high Signal-to-Noise-Ratio(SNR). Numerical results showed that FSO link performance is enhanced when PPM-modulation index is increased, for both strong and moderate turbulence regimes, and for both strong and weak pointing error jitter. Monte-Carlo simulations were presented to corroborate our analytical expressions.

关键词： FSO DGG atmospheric turbulence PPM modulation SEP pointing error

The Impact of the Superposition Coding Concept on Admission Control Strategy in OFDMA-Based Network

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China Communications 2018年第6期15卷 68-83页

作者： Yosra Abbes Sameh Najeh hichem besbes Research Laboratory COSIM Sup'Com University of Carthage

Admission control is a key mechanism to manage the increasing number of the simultaneous demanding services, requiring a desired Quality of Service(QoS) in a spectrum efficient manner. To address this issue,we investigate in this work, the use of the superposition coding technique to increase the system capacity through multiuser diversity exploitation. We propose a novel joint admission control and superposition coding formalism based on different utility functions:Opportunistic(OPSC), Great Fairness(GFSC)and Proportional Fairness(PFSC). Simulation results show the superiority of our proposed approaches over other by providing higher mean of served VoIP users and higher throughput while maintaining an average VoIP packet transmission delay lower than 0.6 ms.

关键词： admission control QoS superposition coding opportunistic great fairness proportional fairness VoIP users

Radio resource management scheme and outage analysis for network- assisted multi-hop D2D communications

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Digital Communications and Networks 2016年第4期2卷 225-232页

作者： Leila Melki Sameh Najeh hichem besbes University of Carthage Higher School of Communications of Tunis COSIM Research Lab Tunisia

In a cellular network it's very difficult to make spectrum resource more efficiently. Device-to-Device (D2D) technology enables new service opportunities, and provides high throughput and reliable communication while reducing the base station load. For better total performance, short-range D2D links and cellular links share the same radio resource and the management of interference becomes a crucial task. Here we argue that single-hop D2D technology can be used to further improve cellular networks performance if the key D2D radio resource management algorithms are suitably extended to support multi-hop D2D communications. Aiming to establish a new paradigm for the analysis and design of multi-hop D2D communications, We propose a radio resource allocation for multi-hop D2D routes based on interference avoidance approach in LTE-A networks. On top of that, we investigate the outage probability of D2D communication. We first introduce a new definition of outage probability by considering the maximum distance to be allowable for single-hop transmission. Then we study and analyze the outage performance of a multi-hop D2D route. We derive the general closed form expression of outage probability of the multi-hop D2D routes. The results demonstrate that the D2D radio, sharing the same resources as the cellular network, provide higher capacity compared to pure cellular communication where all the data is transmitted through the base station. They also demonstrate that the new method of calculation of D2D multi hop outage probability has better performance than classical method defined in the literature.

关键词： D2D Multi-hop Interference avoidance Outage probability LTE-A

Antimicrobial activity of Tunisian Euphorbia paralias L.

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Asian Pacific Journal of Tropical Biomedicine 2017年第7期7卷 629-632页

作者： Malek besbes Hlila Kaouther Majouli hichem Ben Jannet Mahjoub Aouni Maha Mastouri Boulbaba Selmi Laboratory of Transmissible Diseases and Biological Active Substances Department of Pharmaceutical Sciences Faculty of Pharmacy University of Monastir Avenue Avicenne 5000 Monastir Tunisia Laboratory of Biochemistry Research Unit:UR 12ES08'Cell Signaling and Pathologies' Department of Biology Faculty of Medicine University of Monastir Monastir Tunisia Laboratory of Heterocyclic Chemistry Natural Products and Reactivity Team:Medicinal Chemistry and Natural Products Department of Chemistry Faculty of Sciences of Monastir University of Monastir Monastir Tunisia Laboratory of Bioresources:Integrative Biology and Exploiting Higher Institute of Biotechnology of Monastir Department of Molecular Biology Cellular and Biotechnology University of Monastir Monastir Tunisia

Objective: To examine the potential antimicrobial activity of Euphorbia paralias L.(Euphorbiaeae) leaves and stems extracts.Methods: The antimicrobial activity was tested against six microbial strains: Escherichia coli ATCC 8739, Bacillus subtilis ATCC 6633, Salmonella enterica CIP 8039, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 9027 and Candida albicans ATCC 90028 by two different methods, the disk method and the dilution method.Results: Our results showed the important antimicrobial activity of the chloroform extract of the stems towards the majority of the strains by using both methods. Bacillus subtilis was the most sensitive strain(MIC = MBC = 15 mg/mL).Conclusion: Thus, some extracts of Euphorbia paralias can be used in the treatment of infectious diseases caused by microbes.

关键词：大戟属植物 paralias L. 抗菌剂活动 MIC MBC

In vitro antibacterial activity of the Hertia cheirifolia L.essential oils

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Journal of Coastal Life Medicine 2016年第11期4卷 865-867页

作者： Kaouther Majouli Malek besbes Hlila Guido Flamini hichem Ben Jannet Abderraouf Kenani Laboratory of Biochemistry:Research Unit 12ES08 Cell Signaling and PathologiesFaculty of MedicineUniversity of MonastirTunisia Laboratory of Transmissible Diseases and Biologically Active Substances MDT01Faculty of PharmacyUniversity of MonastirTunisia Department of Pharmacy University of PisaStreet Bonanno 656126 PisaItaly Laboratory of Heterocyclic Chemistry Natural Products and Reactivity Team:Medicinal Chemistry and Natural Products(LR11ES39)Faculty of SciencesUniversity of MonastirTunisia

Objective:To investigate the antibacterial activity of essential oils from Hertia cheirifolia L.flowers,vegetative part(leaves+stems)and roots against a panel of bacterial strains.Methods:The essential oils from Hertia cheirifolia L.flowers,vegetative part(leaves+stems)and roots were analyzed by gas chromatography and gas chromatography-mass spectrometry.The antibacterial activity of essential oils was evaluated in vitro by the broth dilution method.Results:The results showed that the essential oil of flowers exhibited a strong antibacterial activity against Staphylococcus aureus with minimal inhibitory concentration of 0.078 mg/mL.Conclusions:The essential oils of Hertia cheirifolia can be a good source of antibacterial compounds.They can be used for pharmaceutical treatments.

关键词： Essential oil Chemical composition Antibacterial activity Hertia cheirifolia L.

Total phenolic compounds,antioxidant potential and α-glucosidase inhibition by Tunisian Euphorbia paralias L.

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Journal of Coastal Life Medicine 2016年第8期4卷 628-633页

作者： Malek besbes Hlila Kaouther Majouli Fethia Harzallah Skhiri hichem Ben Jannet Mahjoub Aouni Maha Mastouri Boulbaba Selmi Laboratory of Transmissible Diseases and Biological Active Substances Faculty of PharmacyUniversity of MonastirAvenue Avicenne5000 MonastirTunisia Biochemistry Laboratory:Cell Signaling and Pathologies Research Unit:UR 12ES08Faculty of Medicine of MonastirTunisia Laboratory of Genetic Biodiversity and Valorisation of BioresourcesLR11ES41Higher Institute of Biotechnology of MonastirUniversity of MonastirMonastir 5000Tunisia Laboratory of Heterocyclic Chemistry Natural Products and ReactivityTeam:Medicinal Chemistry and Natural ProductsFaculty of Sciences of MonastirUniversity of MonastirMonastirTunisia Laboratory of Bioresources:Integrative Biology and exploiting Higher Institute of Biotechnology of MonastirMonastirTunisia

Objective:To examine the potential antioxidant and anti-α-glucosidase inhibitory activities of Tunisian Euphorbia paralias L.leaves and stems extracts and their composition of total polyphenol and flavonoids.Methods:The different samples were tested for their antiradical activities by using 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)and 1,1-diphenyl-2-picrylhydrazyl(DPPH)assays.Inα-glucosidase activity,α-glucosidase(0.3 IU/mL)and substrate,2500μmol/L p-nitrophenylα-D-glucopyranoside were used;absorbance was registered at 405 nm.Results:The leaves acetonic extract exhibited the strongestα-glucosidase inhibition[IC_(50)=(0.0035±0.001)μg/mL],which was 20-fold more active than the standard product(acarbose)[IC_(50)=(0.07±0.01)μg/mL].Acetonic extract of the leaves exhibited the highest quantity of total phenolic[(95.54±0.04)μg gallic acid equivalent/mg]and flavonoid[(55.16±0.25)μg quercetin equivalent/mg].The obtained findings presented also that this extract was detected with best antioxidant capacity[IC_(50)=(0.015±0.01)μg/mL]against DPPH and a value of IC_(50)equal to(0.02±0.01)μg/mL against ABTS.Positive relationship between polyphenolic content of the tested Euphorbia paralias L.leaves and stems extracts and its antioxidant activity(DPPH and ABTS)was detected.Elevated positive linear correlation was got between ABTS and total phenolic(R^(2)=0.751).Conclusions:The findings clearly demonstrate that the use of a polar solvent enables extraction of significant quantities of phenol compounds and flavonoids.

关键词： Euphorbia paralias L. Polyphenolic compounds Antioxidant activity Anti-α-glucosidase activity