A survey on computation offloading and service placement in fog computing-based IoT

The Journal of Supercomputing - In recent years, fog computing has emerged as a computing paradigm to support the computationally intensive and latency-critical applications for resource limited...     

Sterolic composition of Chétoui virgin olive oil: Influence of geographical origin

The sterol profile of Tunisian virgin olive oils produced from Chétoui cultivar, the second main variety cultivated in the north of the country, grown under different environmental conditions, was established by gas chromatography using a flame ionisation detector. More than ten compounds were identified and characterised. As expected for virgin olive oil, the main sterols found in all Chétoui olive oils were β-sitosterol, Δ5-avenasterol, campesterol and stigmasterol. Cholesterol, 24-methylenecholesterol, clerosterol, campestanol, sitostanol, Δ7-stigmastenol, Δ5,24-stigmastadienol, and Δ7-avenasterol were also found in all samples, but in lower amounts. Most of these compounds are significantly affected by the geographical origin. The majority of the Chétoui virgin olive oils analysed respected EC Regulation No. 2568, and in all cases total sterol amounts were higher than the minimum limit set by legislation, ranging from 1017 to 1522 mg/kg.     

Multitask Quantum Study of the Curcumin-Based Complex Physicochemical and Biological Properties

Density functional theory (DFT), time-dependent density functional theory (TDDFT), quantum theory of atoms in molecules (QTAIM), and extended transition state natural orbitals for chemical valence (ETS-NOCV) have all been used to investigate the physicochemical and biological properties of curcumin and three complexes, i.e., Cur-M (M = Ni, Cu, and Mg). Based on DFT calculations, the enolic form (Cur-Enol) is more stable than the anti-diketone form (Cur-Anti diketone) favored for complexation. This enolic form stability was explained by the presence of three intramolecular hydrogen bonds according to the QTAIM analysis. Furthermore, the ETS-NOCV technique revealed that the enolic form had more significant antioxidant activity compared with the anti-diketone form. The calculations from the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) showed that the dimethyl sulfoxide (DMSO) solvent could dissolve all the curcumin tautomers Cur-Enol, Cur-Anti-diketone and Cur-Cu, Cur-Mg, and Cur-Ni complexes in contrast to benzene, acetone, octanol, ethanol, methanol, and water. Furthermore, except for Cur-Mg, which had a relatively low solubility (14 g/L), all complexes were insoluble in water. Cur-Anti-diketone was considerably more soluble than Cur-Enol in the examined solvents.     

Low carbon ultrasonic production of alternate fuel: Operational and mechanistic concerns of the sonochemical process of hydrogen generation under various scenarios

Sonochemistry is considered as one of the cleaner pathways for hydrogen production. The present paper investigates the potential of this technique based upon mass, mass to energy and energy conversion metrics, using modelling and experimental approaches. Four scenarios are examined assuming four saturating gases, namely O₂, air, N₂ and Ar, four acoustic frequencies, i.e., 20, 210, 326 and 488 kHz, and considering common acoustic intensities then common net electric power. The study revealed that Ar is the best fitting saturating gas for the sonochemical production of hydrogen. With a common acoustic intensity of 0.48 W/cm², an optimum ratio of H₂ molar yield to acoustic energy intensity is retrieved at 210 kHz, while with a common net electric power of 87 W, the highest ratio of hydrogen yield to electric energy was observed at 20 kHz. Results were interpreted based upon emitter surface, energy conversion and distinction of calorimetric and cavitational energies.     

Effect of the growing area conditions on differentiation between Chemlali and Chétoui olive oils

This paper reports a discrimination study based on the antioxidant compounds, oxidative stability, aroma and sensory profiles of virgin olive oils from the main Tunisian cultivars, Chemlali and Chétoui, grown in two different locations, north and south Tunisia, with important differences in altitude, latitude and climatic conditions. There were significant differences between the oils from both cultivars when grown in the different environments. At higher altitude, the oils showed a greater amount of oleic acid, phenols and a higher stability, whilst in the open the oils had higher saturated and linoleic acid content. Aroma profiles were also influenced by the pedoclimatic conditions; hence, oils from the South had the highest level of (E)-2-hexenal and 1-hexanol, whereas varieties from the North were higher in (E)-3-hexenyl acetate and hexyl acetate. In general, and independently of the growing area conditions, oils from Chétoui olives had higher levels of antioxidants, greater oxidative stability, higher antiradical activities and more marked intensity of bitterness. These results can be used to discriminate and to characterise the Chemlali and Chétoui olive oils from each region.     

Essential oils of Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart collected from three localities of north Tunisia—Krib, Bargou and Nefza—were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin–Ciocalteu method, and antioxidant effectiveness, using the 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p‐cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), γ‐terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC₅₀, ranged from 59 to 80 mg L^?1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg^?1 dry weight, varied from 9.37 to 17.70 g kg^?1 dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p‐cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated. Copyright © 2010 Society of Chemical Industry     

Very Fast C4.5 Decision Tree Algorithm

This paper presents a novel algorithm so-called VFC4.5 for building decision trees. It proposes an adaptation of the way C4.5 finds the threshold of a continuous attribute. Instead of finding the threshold that maximizes gain ratio, the paper proposes to simply reduce the number of candidate cut points by using arithmetic mean and median to improve a reported weakness of the C4.5 algorithm when it deals with continuous attributes. This paper will focus primarily on the theoretical aspects of the VFC4.5 algorithm. An empirical trials, using 49 datasets, show that, in most times, the VFC4.5 algorithm leads to smaller decision trees with better accuracy compared to the C4.5 algorithm. VFC4.5 gives excellent accuracy results as C4.5 and it is much faster than the VFDT algorithm.     

Interpretability-based validity methods for clustering results evaluation

Validation and interpretation are the two last steps of a clustering process. Generally these steps are processed separately since the existing validity measures are not intended to express the interpretability or the non interpretability of clusters. We propose in this paper to merge the validation and interpretation steps by using a new supervised measure that we call Homogeneity degree and which is based on the criterion of interpretability to validate clusters. We also present an extended version of this measure in order to improve its use as a relative measure.     

Numerical simulation of three-dimensional double diffusive free convection flow and irreversibility studies in a solar distiller

Numerical results of double-diffusive natural convection are presented in a three-dimensional solar distiller. The flow is considered laminar and caused by the interaction of the thermal energy and the chemical species diffusions. Equations of concentration, energy and momentum are formulated using vector potential-vorticity formulations in its three-dimensional form, then solved by the finite volume method. The Rayleigh number is fixed at Ra = 10⁵ and the effects of the buoyancy ratio are studied for opposed temperature and concentration gradients, with a particular interest to the three-dimensional aspects and entropy generation.