Optimisation multi-objectif par l'algorithme des colonies de fourmis

International audienceL'objectif de ce travail est de montrer qu'il est possible de mener l'optimisation multiobjectifs en utilisant un algorithme heuristique aussi performant qu'un Algorithme Génétique (AG), qui est actuellement le plus utilisé dans les solveurs d'optimisation. Il s'agit de l'algorithme d'optimisation basé sur l'approche Pareto (Pareto Ant Colony Optimization : P-ACO). Dans ce papier on montrera à travers l'étude d'une plaque raidie en composite multicouches que l'algorithme P-ACO est aussi performant qu'un AG mais a l'avantage d'être plus aisé à mettre en oeuvre numériquement. La modélisation de la structure composite est réalisée par le code de calcul commercial ANSYS®

A squeezed review on coherent states and nonclassicality for non-Hermitian systems with minimal length

It was at the dawn of the historical developments of quantum mechanics when Schrödinger, Kennard and Darwin proposed an interesting type of Gaussian wave packets, which do not spread out while evolving in time. Originally, these wave packets are the prototypes of the renowned discovery, which are familiar as “coherent states” today. Coherent states are inevitable in the study of almost all areas of modern science, and the rate of progress of the subject is astonishing nowadays. Nonclassical states constitute one of the distinguished branches of coherent states having applications in various subjects including quantum information processing, quantum optics, quantum superselection principles and mathematical physics. On the other hand, the compelling advancements of non-Hermitian systems and related areas have been appealing, which became popular with the seminal paper by Bender and Boettcher in 1998. The subject of non-Hermitian Hamiltonian systems possessing real eigenvalues are exploding day by day and combining with almost all other subjects rapidly, in particular, in the areas of quantum optics, lasers and condensed matter systems, where one finds ample successful experiments for the proposed theory. For this reason, the study of coherent states for non-Hermitian systems have been very important. In this article, we review the recent developments of coherent and nonclassical states for such systems and discuss their applications and usefulness in different contexts of physics. In addition, since the systems considered here originated from the broader context of the study of minimal uncertainty relations, our review is also of interest to the mathematical physics communit

Definition of a temporal distribution index for high temporal resolution precipitation data over Peninsular Spain and the Balearic Islands: the fractal dimension; and its synoptic implications

Precipitation on the Spanish mainland and in the Balearic archipelago exhibits a high degree of spatial and temporal variability, regardless of the temporal resolution of the data considered. The fractal dimension indicates the property of self-similarity, and in the case of this study, wherein it is applied to the temporal behaviour of rainfall at a fine (10-min) resolution from a total of 48 observatories, it provides insights into its more or less convective nature. The methodology of Jenkinson & Collison which automatically classifies synoptic situations at the surface, as well as an adaptation of this methodology at 500 hPa, was applied in order to gain insights into the synoptic implications of extreme values of the fractal dimension. The highest fractal dimension values in the study area were observed in places with precipitation that has a more random behaviour over time with generally high totals. Four different regions in which the atmospheric mechanisms giving rise to precipitation at the surface differ from the corresponding above-ground mechanisms have been identified in the study area based on the fractal dimension. In the north of the Iberian Peninsula, high fractal dimension values are linked to a lower frequency of anticyclonic situations, whereas the opposite occurs in the central region. In the Mediterranean, higher fractal dimension values are associated with a higher frequency of the anticyclonic type and a lower frequency of the advective type from the east. In the south, lower fractal dimension values indicate higher frequency with respect to the anticyclonic type from the east and lower frequency with respect to the cyclonic type

La coupe de l'oued Ahmadi (Dahar, sud tunisien) : son intérêt pour la compréhension de l'évolution climatique au Pléistocène moyen

Four sedimentary sequences are seen in the Middle Pleistocene terrace of Wadi Ahmadi. They may indicate four climatic oscillations while climate remains arid for the most part. An occasional changing of direction in the general Quaternary trend to aridification is indicated by the genesis of a calcrust after a gypscrust.La coupe de la terrasse du Pléistocène moyen de l'oued Ahmadi est organisée en quatre séquences sédimentaires qui pourraient traduire l'existence de quatre oscillations climatiques dans un climat restant aride dans l'ensemble. La genèse d'une croûte calcaire postérieurement à celle d'une croûte gypseuse indique un renversement épisodique de la tendance générale à l'aridification du climat pendant le Quaternaire.Ballais Jean-Louis, Ben Ouezdou H., Ghanmi M., Regaya K. La coupe de l'oued Ahmadi (Dahar, sud tunisien) : son intérêt pour la compréhension de l'évolution climatique au Pléistocène moyen. In: Méditerranée, troisième série, tome 64, 2-1988. Évolution des paysages tunisiens au cours du Quaternaire, sous la direction de J.-L Ballais et J. Vaudour. pp. 52-60

Activité antimicrobienne et composition chimique de l'huile essentielle de Plectranthus aromaticus Roxb. de l'Ile de la Grande Comore

Antimicrobial activity and chemical composition of Plectranthus aromaticus Roxb. essential oil from Grande Comore Island. This work aims to study the antibacterial and antifungal activity and chemical composition of Plectranthus aromaticus essential oil from Grande Comore Island. This species has provided an essential oil with a yield of 1.31%. The chromatographic analysis (GC and GC/MS) of the essence of P. aromaticus has identified about 32 constituents which are the most dominant: the trans-verbenol (23.11%), carvacrol (22.96%) and 1,4-cineol (14.50%). The antimicrobial activity of this oil has been studied with respect to seven microorganisms. The essential oil of P. aromaticus has proven antibacterial and antifungal activity at low concentrations

Juniperus Phoenicea essential oil as green corrosion inhibitor for mild steel in molar hydrochloric acid

Juniperus Phoenicea Essential Oil (JPEO) was obtained by hydro-distillation and characterized using Gas Chromatography Electronic (GC). It is found that major component was α-pinene (89.31%). In addition, this compound was investigated as green corrosion inhibitor of mild steel in 1.0 M HCl using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The polarization measurements showed that JPEO acts as mixed-type inhibitor and its inhibition efficiency increased with concentration to reach 88.3% at 250 ppm. This result was confirmed the EIS. The influences of temperature and immersion time were also studied in the range from 298 to 328 K and up to 12 h, respectively. The kinetic and thermodynamic data of activation dissolution process were determined and discussed