Higher order Riesz transforms for the Dunkl Ornstein-Uhlenbeck operator

summary:The aim of this paper is to extend the study of Riesz transforms associated to Dunkl Ornstein-Uhlenbeck operator considered by A. Nowak, L. Roncal and K. Stempak to higher order

Gestion du problème de changement climatique

De la science du changement climatique aux estimations de ses impacts, le problème du changement climatique se caractérise surtout par la présence de grandes incertitudes. C'est pourquoi nous formulerons la question principale de notre article: comment tenir compte des incertitudes dans la décision de prévenir le changement climatique ? L'économie de l'environnement et des ressources naturelles nous aiderait à dessiner la portée du problème de gestion du problème du changement climatique et nous permettrais de dresser une réflexion économique, capable de rendre compte des nombreuses dimensions du problème, tout en préservant la lisibilité des résultats.

Entrepreneurial passion and entrepreneurial intention: the mediating role of perceived behavioral control

Purpose: The objective of this article is to clarify the mechanism through which entrepreneurial passion affects entrepreneurial intention. This article empirically investigate whether perceived behavior control have a mediating effects on the relationship between entrepreneurial passion and entrepreneurial intention. It is based on cognitive perspectives; the present study aimed to identify the impact of entrepreneurial passion on entrepreneurial intention. Design/methodology/approach: The research method is quantitative. The sample of this study comprised 240 respondents from the public of Tunisian project leaders. Data were gathered using a self-report administered questionnaire, and hypotheses were tested with structural equation modelling. Findings:. The results demonstrate that the relationship between passion and intention is mediated by perceived behavioral control. We found that the mediating effect of perceived behavioral control is partial. Implications/recommendations: Our study has some practical implications for the researcher and entrepreneuship education who are directly and indirectly involved in enhancing the growth of entrepreneurship. Practical implications: This article gives rise to a new reflection on the analysis of entrepreneurial behavior based on a psychological and affective approach. Paper type: Research paper &nbsp

Grasp planning for a reconfigurable parallel robot with an underactuated arm structure

In this paper, a novel approach of grasp planning is applied to find out the appropriate grasp points for a reconfigurable parallel robot called PARAGRIP (Parallel Gripping). This new handling system is able to manipulate objects in the six-dimensional Cartesian space by several robotic arms using only six actuated joints. After grasping, the contact elements at the end of the underactuated arm mechanisms are connected to the object which forms a closed loop mechanism similar to the architecture of parallel manipulators. As the mounting and grasp points of the arms can easily be changed, the manipulator can be reconfigured to match the user's preferences and needs. This paper raises the question, how and where these grasp points are to be placed on the object to perform well for a certain manipulation task. <br><br> <i>This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.</i&gt

Utilisation de la diatomite Tunisienne naturelle et modifiée pour l’élimination des polluants organiques et inorganiques d’un milieu aqueux

132 p.La pollution de l’environnement, principalement celle de l’eau, par les substances chimiques organiques et inorganiques est un majeur problème qui menace notre santé d’une façon directe ou indirecte. Cette pollution est due essentiellement aux rejets industriels des composés chimiques difficilement biodégradables (hydrocarbures aromatiques, métaux lourds, colorants…). Ainsi, des techniques de traitement existent pour minimiser ou éliminer la présence de ces polluants dans l’eau. L’adsorption est la technique la plus simple, rapide et efficace. Le choix de l’adsorbant est considéré important dans le processus de l’adsorption. Pour cela, la recherche d’adsorbants performants retient l’attention des chercheurs. Des divers matériaux ont été étudiés tels que : le charbon actif, les argiles, les algues marines, les biomasses microbiennes, la chitine, le chitosane, etc. La diatomite est considérée, un adsorbant naturel trop utilisé dans le domaine d’adsorption. L’objectif de notre travail est alors de mettre en valeur le rôle de la diatomite tunisienne pour l’élimination des polluants organiques et inorganiques d’un milieu aqueux

Effet de la convection en double diffusion thermique et massique sur une couche limite laminaire (S23)

La convection naturelle thermosolutale est due principalement à sa présence dans plusieurs, applications industrielles tels que les procédés de séparation en industries chimiques et pétrolières de stockage des déchets nucléaires, la dispersion des contaminants chimiques dans les couches d'eau souterraine, la migration de l'humidité à travers les isolations fibreuses, les processus de séchage, les opérations de dessalement de l'eau de mer. On se propose dans ce travail d'étudier par simulation numérique directe l'effet de la convection en double diffusion sur une plaque plane lisse et horizontale. La couche limite générée est considérée laminaire. La technique numérique utilisée dans cet article est la méthode des volumes finis. Les analyses de l'évolution des profils de vitesse, de concentration et de la température et la variation du nombre de Nusselt permettront d'capturer les phénomènes liés aux doubles diffusions

Improving the IEEE 802.15.4 Slotted CSMA/CA MAC for time-critical events in wireless sensor networks

In beacon-enabled mode, IEEE 802.15.4 is ruled by the slotted CSMA/CA Medium Access Control (MAC) protocol. The standard slotted CSMA/CA mechanism does not provide any means of differentiated services to improve the quality of service for timecritical events (such as alarms, time slot reservation, PAN management messages etc.). In this paper, we present and discuss practical service differentiation mechanisms to improve the performance of slotted CSMA/CA for time-critical events, with only minor add-ons to the protocol. The contribution of our proposal is more practical than theoretical since our initial requirement is to leave the original algorithm of the slotted CSMA/CA unchanged, but rather tuning its parameters adequately according to the criticality of the messages. We present a simulation study based on an accurate model of the IEEE 802.15.4 MAC protocol, to evaluate the differentiated service strategies. Four scenarios with different settings of the slotted CSMA/CA parameters are defined. Each scenario is evaluated for FIFO and Priority Queuing. The impact of the hiddennode problem is also analyzed, and a solution to mitigate it is proposed

Formation of Palygorskite Clay from Treated Diatomite and its Application for the Removal of Heavy Metals from Aqueous Solution

Environmental contamination by toxic heavy metals is a serious worldwide phenomenon. Thus, their removal is a crucial issue. In this study, we found an efficient adsorbent to remove Cu2+ and Ni2+ from aqueous solution using two materials. Chemical modification was used to obtain palygorskite clay from diatomite. The adsorbents were characterized using X-ray florescence, Fourier transform infrared spectroscopy and X-ray diffraction. The effects of contact time, initial concentration, temperature and pH on the adsorption process were investigated. Our results showed that the (%) of maximum adsorption capacity of diatomite was 78.44% for Cu2+ at pH 4 and 77.3% for Ni2+ at pH 7, while the (%) of the maximum adsorption on palygorskite reached 91% for Cu2+ and 87.05% for Ni2+, in the same condition. The results indicate that the pseudo-second-order model can describe the adsorption process. Furthermore, the adsorption isotherms could be adopted by the Langmuir and the Freundlich models with good correlation coefficient (R-2). Thus, our results showed that palygorskite prepared from Tunisian diatomite is a good adsorbent for the removal of heavy metals from water.This research was funded by Department of Education of the Basque Government grant number [IT1008-16]" and "The APC was funded by Department of Education of the Basque Government