Dridi I.,Tunis el Manar University |
Arfaoui A.,Jendouba University
Environmental Earth Sciences | Year: 2017
The study of nitrogen organic matter is of great importance for both economic and environmental reasons. Thus, seven soils developed under different pedogenetic and bioclimatic conditions in Tunisia were selected to investigate the distribution of organic nitrogen (ON). Our results showed an enrichment in ON of superficial horizons to the detriment of the deep horizons. Nevertheless, this decrease in ON contents with depth occurred following different patterns according to soil type. Moreover, the investigation of ON distribution in clay- and silt-sized particles (below 50 µm) indicated a considerable contribution of the fine fraction (65–98% of the soil total ON) to the ON immobilization in soils, especially in the deep horizons, while the coarse fraction (>50 µm) seems to play a less important role. The isolation of humic substances (Humic Acids, Fulvic Acids and Humin (H)) from the fine fraction and the analysis of the ON in each of these organic fractions permitted to conclude the majority of soil ON is incorporated within the H, thus suggesting a low bioavailability of nitrogen in the studied soils. © 2017, The Author(s).
Hajji M.A.,Higher Institute of Management |
Mezni H.,Jendouba University
Soft Computing | Year: 2017
Cloud computing has emerged as a new powerful service delivery model to cope with resource challenges and to offer on-demand various types of services (e.g., software, storage, network). One of the most popular service models is Software as a Service (SaaS). To allow flexibility and reusability, SaaS can be offered in a composite form, where a set of interacting application and data components cooperate to form a higher-level functional SaaS. However, this approach introduces new challenges to resource management in the cloud, especially finding the optimal placement for SaaS components to have the best possible SaaS performance. SaaS Placement Problem (SPP) refers to this challenge of determining which servers in the cloud’s data center can host which components without violating SaaS constraints. Most existing SPP approaches only addressed homogenous SaaS components placement and only considered one type of constraints (i.e., resource constraint). In addition, none of them has considered the objective of maintaining a good machine performance by minimizing the resource usage for the hosting machines. To allow finding the optimal placement of a composite SaaS, we adopt a new variation of PSO called ’Particle Swarm Optimization with Composite Particle (PSO-CP).’ In the proposed PSO-CP-based approach, each composite particle in the swarm represents a candidate SaaS placement scheme. Composite particles adopt a collective behavior to explore and evaluate the search space (i.e., data center) and adjust their structures by collaborating with other composite or independent particles (i.e., servers). The implementation and experimental results show the feasibility and efficiency of the proposed approach. © 2017 Springer-Verlag Berlin Heidelberg
Mezni H.,Jendouba University |
Kouki J.,High Institute of Human science
Proceedings of the ACM Symposium on Applied Computing | Year: 2017
This paper explores one of the critical issues, SaaS placement in cloud data centers, for reducing execution time of composite SaaS applications. We adopt a multi-swarm variant of Particle Swarm Optimization (PSO) to propose a service placement method. Also, a cooperative learning strategy is hybridized to the placement algorithm, which makes information of best candidate servers be used more effectively to generate better placement plan. In the proposed method, for each sub-swarm of servers, the worst placement learns from the best servers, so that worst servers can have more excellent exemplars to learn and can find the optimal placement for SaaS components more easily. Experiments show that our solution is efficient in comparison with existing SaaS placement approaches. Copyright 2017 ACM.
Jbali A.,Jendouba University |
Sassi S.,Jendouba University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017
Nowadays, many organizations rely on database systems as the key data management technology for a large variety of tasks. This wide use of such systems involved that security breaches and unauthorized disclosures threat those systems especially when the data is exchanged between several parts in a distributed system. Consequently, access control must adapt to this exchange process to maintain data privacy. In this paper, the challenge is to design an approach to deal with access control policies in a context of data exchange between relational databases. In fact, the main problem that we are dealing with is that given a set of policies attached to a source schema and a set of mapping rules to a target schema, the question is how the policies will pass from the source schema to the target schema and what are the policies that will be attached to the target schema to comply with the set of source policies. For that purpose, we propose in this paper our methodology called Policies-generation. © 2017, Springer International Publishing AG.
Chaabene H.,Tunisian Research Laboratory Sport Performance Optimization |
Franchini E.,University of Sao Paulo |
Miarka B.,University of Sao Paulo |
Selmi M.A.,Jendouba University |
And 2 more authors.
International Journal of Sports Physiology and Performance | Year: 2014
Purpose: The aim of this study was to measure and compare physiological and time-motion variables during karate fighting and to assess eventual differences between winners and defeated elite karatekas in an ecologically valid environment. Methods: Fourteen elite male karatekas who regularly participated in national and international events took part in a national-level competition. Results: There were no significant differences between winners and defeated karatekas regarding all the studied variables. Karatekas used more upper-limb (76.19%) than lower-limb techniques (23.80%). The kisami-zuki represented the most frequent technique, with 29.1% of all used techniques. The duration of each fighting activity ranged from <1 s to 5 s, with 83.8% ± 12.0% of the actions lasting less than 2 s. Karatekas executed 17 ± 7 high-intensity actions per fight, which corresponded to ~6 high-intensity actions per min. Action-to-rest ratio was about 1:1.5, and high-intensityaction-to-rest ratio was ~1:10. The mean blood lactate response at 3 min postcombat (Lapost) elicited during karate fighting was 11.18 ± 2.21 mmol/L (difference between Lapre and Lapost = 10.01 ± 1.81 mmol/L). Mean heart rate (HR) was 177 ± 14 beats/min (91% ± 5% of HRpeak). Karatekas spent 65% of the time exercising at HR >90% of the individual HRpeak. Conclusion: Karatekas predominantly use upper-limb karate techniques. Karate's nature is intermittent, with fighting activities representing ~6% of total combat's duration and ~84% of actions lasting less than 2 s, with ~21-s mean time interval in between. Kumite combat sessions induced high La and near-maximal cardiovascular strain. Other key success factors should be investigated to properly discriminate winners and defeated athletes. © 2014 Human Kinetics, Inc.
Krichen S.,University of Tunis |
Krichen S.,Jendouba University |
Laabidi A.,University of Tunis |
Abdelaziz F.B.,American University of Sharjah
Computers and Industrial Engineering | Year: 2011
We consider in this paper an Economic Order Quantity (EOQ) problem involving a single supplier that offers quantity discounts and allows retailers to delay payments. The retailers are tempted to form coalitions in order to minimize their costs. We propose a solution approach that generates stable coalition structures for the retailers taking into account the delay in payments and the discount quantity offered by the supplier. The proposed approach includes a decision rule that generates preferred coalitions for each retailer. Our decision rule reduces considerably the number of explored coalition structures in order to determine solutions in the core. Through an experimental investigation of the problem, we show the effectiveness of our approach in solving large scale problems and illustrate the effect of permissible delay in payments versus discount quantity on the coalition formation problem. © 2010 Elsevier Ltd. All rights reserved.
Ben Aissa M.S.,Tunis el Manar University |
Ben Jebli M.,Tunis el Manar University |
Ben Jebli M.,Jendouba University |
Ben Youssef S.,Manouba University
Energy Policy | Year: 2014
We use panel cointegration techniques to examine the relationship between renewable energy consumption, trade and output in a sample of 11 African countries covering the period 1980-2008. The results from panel error correction model reveal that there is evidence of a bidirectional causality between output and exports and between output and imports in both the short and long-run. However, in the short-run, there is no evidence of causality between output and renewable energy consumption and between trade (exports or imports) and renewable energy consumption. Also, in the long-run, there is no causality running from output or trade to renewable energy. In the long-run, our estimations show that renewable energy consumption and trade have a statistically significant and positive impact on output. Our energy policy recommendations are that national authorities should design appropriate fiscal incentives to encourage the use of renewable energies, create more regional economic integration for renewable energy technologies, and encourage trade openness because of its positive impact on technology transfer and on output. © 2013 Elsevier Ltd.
Ben Jebli M.,Jendouba University
Environmental Science and Pollution Research | Year: 2016
This study employs the autoregressive distributed lag (ARDL) approach and Granger causality test to investigate the short- and long-run relationships between health indicator, real GDP, combustible renewables and waste consumption, rail transport, and carbon dioxide (CO2) emissions for the case of Tunisia, spanning the period of 1990–2011. The empirical findings suggest that the Fisher statistic of the Wald test confirm the existence of a long-run relationship between the variables. Moreover, the long-run estimated elasticities of the ARDL model provide that output and combustible renewables and waste consumption have a positive and statistically significant impact on health situation, while CO2 emissions and rail transport both contribute to the decrease of health indicator. Granger causality results affirm that, in the short-run, there is a unidirectional causality running from real GDP to health, a unidirectional causality from health to combustible renewables and waste consumption, and a unidirectional causality from all variables to CO2 emissions. In the long-run, all the computed error correction terms are significant and confirm the existence of long-run association among the variables. Our recommendations for the Tunisian policymakers are as follows: (i) exploiting wastes and renewable fuels can be a good strategy to eliminate pollution caused by emissions and subsequently improve health quality, (ii) the use of renewable energy as a main source for national rail transport is an effective strategy for public health, (iii) renewable energy investment projects are beneficial plans for the country as this contributes to the growth of its own economy and reduce energy dependence, and (iii) more renewable energy consumption leads not only to decrease pollution but also to stimulate health situation because of the increase of doctors and nurses numbers. © 2016 Springer-Verlag Berlin Heidelberg
Djebali R.,Jendouba University
Communications in Computational Physics | Year: 2014
This study aims to investigate turbulent plasma flow using the lattice Boltzmann (LB) method. A double population model D2Q9-D2Q4 is employed to calculate the plasma velocity and temperature fields. Along with the calculation process a conversion procedure is made between the LB and the physical unit systems, so that thermo-physical properties variation is fully accounted for and the convergence is checked in physical space. The configuration domain and the boundary condition treatment are selected based on the most cited studies in order to illustrate a realistic situation. The jet morphology analysis gives credible results by comparison with commonly published works. It was demonstrated also that accounting for the substrate as wall boundary condition modify greatly the flow and temperature structures with may affect absolutely the particles behavior during its in-flight in the hot gas. © 2014 Global-Science Press.
Mezni H.,Jendouba University
Proceedings of the IEEE International Conference on Software Engineering and Service Sciences, ICSESS | Year: 2014
Although several approaches have been proposed towards self-adaptation of Web services, most of them work in isolation and few of them deal with cross-layer and trust issues. Indeed, the complex layered nature of service-based systems frequently leads to service failure and conflicting adaptation. To tackle this problem, we propose an ontology-based categorization of service behavior across all the functional layers. The proposed ontology provides support for cross-layer self-adaptation by facilitating reasoning about events to identify the real source of service failure, and reasoning about self-adaptation actions to check integrity and compatibility of self-adaptation with constraints imposed by each layer. © 2014 IEEE.