Experimental study to enhance swirl burner against boundary layer flashback

In gas turbine systems, operation stability represents the major challenge to any successful device deployment. Climate change combined with fossil fuel pollution has led to the need of considering high hydrogen content fuels, thus putting more pressure to stabilise gas turbines at operation conditions. Flashback is one of the main operation stability problems that represent a real challenge for gas turbine designers when using fast reacting fuels with high hydrogen content. One mechanism that has shown to contribute to flashback considerably is the propagation of the flame through its boundary layer. Although the latter has been studied, there are still several unknowns in its evolution through the system. Thus, boundary layer flashback of a swirling turbulent flame was investigated in a 150 kW tangential swirl burner previously characterised. To produce controlled changes to the boundary layer, the internal side of the burner was covered by woven wire steel mesh to mimic biological skin techniques in flow drag improvement. Two different wire meshes were used to study the effect of the regular roughness size on the boundary flashback. Moreover, the effects of using the wire mesh in such swirling flow with and without central air injection for reduction of other flashback phenomena were studied. The results show good enhancement of the system to boundary layer flashback, and a new map of the combustion stability of the rig has been produced

THE USE OF EYE TRACKING AND ARTIFICIAL INTELLIGENCE (AI) IN ASSESSING THE HOTELS WEBSITE DESIGN AESTHETIC ELEMENT: THE CASE OF ALGERIAN HOTELS WEBSITES

Objectives: This study aims to evaluate the aesthetic quality of Algerian hotel websites and their ability to create a positive first impression, which is crucial for user engagement. The research focuses on identifying design strengths and weaknesses to propose actionable improvements for enhancing user experience.   Theoretical Framework: The study integrates Eye Tracking (ET) technology and Artificial Intelligence (AI) to analyze visual engagement and design aesthetics. Marriott Bonvoy®'s website serves as a benchmark, providing a standard for effective aesthetic design. Method: A content analysis was conducted on four Algerian hotel websites based in Constantine, utilizing ET-generated heatmaps and AI-derived visual indices, such as clarity scores, to evaluate design performance.   Results and Discussion: The analysis revealed that Marriott Bonvoy® demonstrated superior aesthetic design, followed by the local three-star El Bey Hotel, which outperformed other local websites in design quality. Despite its relative success, El Bey and the other hotels exhibited areas requiring improvement, highlighting gaps in visual hierarchy, layout coherence, and clarity.   Research Implications: The findings emphasize the need for Algerian hotel managers to prioritize design aesthetics as a key component of their digital strategy. Implementing the suggested improvements could enhance user experience and competitiveness in the hospitality sector.   Originality/Value: This study uniquely combines ET and AI to evaluate website design in the Algerian hospitality context, providing actionable insights for improving digital engagement. It contributes to the growing body of research on user-centered web design in emerging markets

The novel Parkinson's disease linked mutation G51D attenuates in vitro aggregation and membrane binding of α-synuclein, and enhances its secretion and nuclear localization in cells

A novel mutation in the α-Synuclein (α-Syn) gene "G51D” was recently identified in two familial cases exhibiting features of Parkinson's disease (PD) and multiple system atrophy (MSA). In this study, we explored the impact of this novel mutation on the aggregation, cellular and biophysical properties of α-Syn, in an attempt to unravel how this mutant contributes to PD/MSA. Our results show that the G51D mutation significantly attenuates α-Syn aggregation in vitro. Moreover, it disrupts local helix formation in the presence of SDS, decreases binding to lipid vesicles C-terminal to the site of mutation and severely inhibits helical folding in the presence of acidic vesicles. When expressed in yeast, α-SynG51D behaves similarly to α-SynA30P, as both exhibit impaired membrane association, form few inclusions and are non-toxic. In contrast, enhanced secreted and nuclear levels of the G51D mutant were observed in mammalian cells, as well as in primary neurons, where α-SynG51D was enriched in the nuclear compartment, was hyper-phosphorylated at S129 and exacerbated α-Syn-induced mitochondrial fragmentation. Finally, post-mortem human brain tissues of α-SynG51D cases were examined, and revealed only partial colocalization with nuclear membrane markers, probably due to post-mortem tissue delay and fixation. These findings suggest that the PD-linked mutations may cause neurodegeneration via different mechanisms, some of which may be independent of α-Syn aggregatio

Stochastic Q-learning for Large Discrete Action Spaces

In complex environments with large discrete action spaces, effective decision-making is critical in reinforcement learning (RL). Despite the widespread use of value-based RL approaches like Q-learning, they come with a computational burden, necessitating the maximization of a value function over all actions in each iteration. This burden becomes particularly challenging when addressing large-scale problems and using deep neural networks as function approximators. In this paper, we present stochastic value-based RL approaches which, in each iteration, as opposed to optimizing over the entire set of $n$ actions, only consider a variable stochastic set of a sublinear number of actions, possibly as small as $\mathcal{O}(\log(n))$. The presented stochastic value-based RL methods include, among others, Stochastic Q-learning, StochDQN, and StochDDQN, all of which integrate this stochastic approach for both value-function updates and action selection. The theoretical convergence of Stochastic Q-learning is established, while an analysis of stochastic maximization is provided. Moreover, through empirical validation, we illustrate that the various proposed approaches outperform the baseline methods across diverse environments, including different control problems, achieving near-optimal average returns in significantly reduced time

Engagement et spiritualité au travail : le cas de Sodexo Tunisie

Enterprises face difficult conditions related to the pace of the observed changes at the beginning of XXIst century and are struggling to raise employee commitment. The purpose of this research was to invest new managerial thoughts by questioning the contribution of spirituality at work to the affective commitment of employees. To verify the existence of this link, a case study “Sodexo Tunisia” was conducted through semi-structured interviews. These interviews have been twice analyzed, statistically using the Alceste software and qualitatively through a thematic content analysis. It was concluded, on one side, that basic forms of the affective commitment of employees, namely their emotional attachment, their desire to stay and make special efforts, are favored by the spiritual dimension “spirit of survival” related to the presence and the “shared values” of the enterprise. On the other side, correlated forms of affective commitment interpreted as “psychological identification to the job” and "psychological identification to the group” are associated with the spiritual dimensions “self-government” and “inner life” for the former, and “esprit de corps” for the latter. In a managerial perspective, these spiritual dimensions favor the recognition of individuals (stimulus to potential and intellectual capital), the development of “esprit de corps” (glue of lasting commitment) and help maintain the “spirit of survival” of the enterprise (basis of the emotional attachment of employees). This “mind-state” provides an enterprise model with a resilience capacity, due to the consistency between the parts and the whole.Les entreprises affrontent des conditions difficiles liées au rythme des changements observés en ce début de XXIème siècle et ont du mal à susciter l’engagement des salariés. L’objet de cette recherche a été d’investir de nouvelles réflexions managériales en s’interrogeant sur la contribution de la spiritualité au travail à l’engagement affectif des salariés. Pour vérifier l’existence de ce lien, une étude du cas « Sodexo Tunisie » a été réalisée à travers des entretiens semi-directifs. Ces entretiens ont fait l’objet d’un double traitement, statistique, à l’aide du logiciel Alceste, puis qualitatif par le biais d’une analyse de contenu thématique. Il a été conclu, d’un côté, que les formes de base de l’engagement affectif des salariés, à savoir leur attachement émotionnel, leur désir de rester et de réaliser des efforts particuliers, sont favorisées par la dimension spirituelle « esprit de survie » reliée à la présence et le « partage de valeurs communes » de l’entreprise. De l’autre côté, les formes corrélées d’engagement affectif interprétées par «l’identification psychologique au travail » et «l’identification psychologique au groupe » sont associées aux dimensions spirituelles « gouvernement de soi » et « vie intérieure » pour la première, et « esprit de corps » pour la deuxième. Exploitées dans une optique managériale, ces dimensions spirituelles favorisent la reconnaissance des individualités (révélateur de potentiel et de capital intellectuel), le développement de l’esprit de corps (ciment de l’engagement durable) et permettent d’entretenir l’esprit de survie de l’entreprise (fondement de l’attachement émotionnel des salariés). Cet « état d’esprit » constitue un modèle d’entreprise ayant la capacité de résilience et ce, grâce à la cohérence entre les parties et le tout

Contribution du systeme educatif a la croissance economique en Algerie

Les recherches sur le lien entre l’éducation et la croissance économique se heurtent à de multiples difficultés méthodologiques et les résultats obtenus sont souvent difficilement interprétables. Cependant, la plupart des études empiriques semblent s'accorder sur un effet positif de l’éducation sur la croissance économique.Cet article traite de la contribution du système éducatif algérien à la croissance économique à travers l’utilisation d’une approche multivariée. Il en ressort de cette étude que l’enseignement primaire et universitaire en Algérie sont non seulement une source d’accumulation du capital humain mais également un facteur de la croissance économique. Il est donc important que ces niveaux d’enseignement soient prioritaires dans la politique d’enseignement.Mots clés: Système éducatif, Capital humain, Croissance économique, VA