Search results for "processes"
showing 10 items of 3831 documents
A Time-Non-Homogeneous Double-Ended Queue with Failures and Repairs and Its Continuous Approximation
2018
We consider a time-non-homogeneous double-ended queue subject to catastrophes and repairs. The catastrophes occur according to a non-homogeneous Poisson process and lead the system into a state of failure. Instantaneously, the system is put under repair, such that repair time is governed by a time-varying intensity function. We analyze the transient and the asymptotic behavior of the queueing system. Moreover, we derive a heavy-traffic approximation that allows approximating the state of the systems by a time-non-homogeneous Wiener process subject to jumps to a spurious state (due to catastrophes) and random returns to the zero state (due to repairs). Special attention is devoted to the cas…
Calcium mediated polyelectrolyte adsorption on like-charged surfaces.
2011
International audience; Monte Carlo simulations within the primitive model of calcium-mediated adsorption of linear and comb polyelectrolytes onto like-charged surfaces are described, focusing on the effect of calcium and polyion concentrations as well as on the ion pairing between polymers and calcium ions. We use a combination of Monte Carlo simulations and experimental data from titration and calcium binding to quantify the ion pairing. The polymer adsorption is shown to occur as a result of surface overcharging by Ca2+ and ion pairing between charged monomers and Ca2+. In agreement with experimental observations, the simulations predict that the polymer adsorption isotherm goes through …
A New Spatial Shift‐Share Decomposition: An Application to Tourism Competitiveness in Italian Regions
2020
The paper proposes a new version of spatial shift-share decomposition to improve on the various approaches to conventional shift-share analysis found in the literature. The novelty of our proposal is that it enables researchers to assess spatial competitiveness effects controlling for the influence of industrial specialization at both regional and neighborhood level. This new version is applied to inbound tourism in Italian regions and enables us to identify the best and worst performers. Our empirical results identify favorable scenarios in some areas of the country, such as Sardinia as well as regional advantage in a sizeable number of well-known destinations.
Service Climate and Display of Employees’ Positive Emotions: The Mediating Role of Burnout and Engagement in Services
2011
This article aims to test a model linking service climate to the frequency of expression of positive emotions by frontline employees. We propose that burnout and engagement at work mediate the relationship between service climate and the expression of positive emotions. Service climate impacts negatively on burnout and positively on engagement; in turn, burnout and engagement are significantly related to the frequency of expression of positive emotions. This model was tested both at the individual and work-unit levels. In addition, it was compared with a direct model that proposes an additional direct link from service climate to frontline employees’ positive emotions. Models were tested th…
Ergonomie des documents techniques informatisés : expériences et recommandations sur l'utilisation des organisateurs para-linguistiques
1998
Despite an increasing development, the design of computerized documents is still based on intuitive or esthetics concerns, rather than on experimental evidence. However a large body of literature has investigated the effects of various display factors, both on a perceptual and on a cognitive level. We propose here a review of research and its implication on the design of computerized documents.
Three-dimensional core-collapse supernovae with complex magnetic structures: I. Explosion dynamics
2021
Magnetic fields can play a major role in the dynamics of outstanding explosions associated to violent events such as GRBs and hypernovae, since they provide a natural mechanism to harness the rotational energy of the central proto-neutron star and power relativistic jets through the stellar progenitor. As the structure of such fields is quite uncertain, most numerical models of MHD-driven core-collapse supernovae consider an aligned dipole as initial magnetic field, while the field's morphology can actually be much more complex. We present three-dimensional simulations of core-collapse supernovae with more realistic magnetic structures, such as quadrupolar fields and, for the first time, an…
The impact of non-dipolar magnetic fields in core-collapse supernovae
2019
The magnetic field is believed to play an important role in at least some core-collapse supernovae if its magnitude reaches $10^{15}\,\rm{G}$, which is a typical value for a magnetar. In the presence of fast rotation, such a strong magnetic field can drive powerful jet-like explosions if it has the large-scale coherence of a dipole. The topology of the magnetic field is, however, probably much more complex with strong multipolar and small-scale components and the consequences for the explosion are so far unclear. We investigate the effects of the magnetic field topology on the dynamics of core-collapse supernovae and the properties of forming proto-neutron star (PNS) by comparing pre-collap…
Project-Based Learning: A Case for Situated Translation
2006
The author proposes replacing the folk theoretical ‘conduit’ view of learning that still predominates in Translator Education with a principled understanding of cognitive and learning processes for the design of learning events in Translator Education. A collaborative, project-based educational experience is presented by way of illustration. In conclusion, an argument is made for studying collaborative learning events to gain insight into the multi-facetted nature of the learning process as well as of the translation process itself.
Don't tell us: the demand for secretive bahaviour
2009
International audience
Aeolian Remobilisation of the 2011-Cordón Caulle Tephra-Fallout Deposit: Example of an Important Process in the Life Cycle of Volcanic Ash
2020
Although volcanic eruptions represent short periods in the whole history of a volcano, the large amount of loose pyroclastic material produced, combined with aeolian processes, can lead to continuous, long-lasting reworking of volcanic products. Driven by wind, these processes significantly influence the geomorphology and prolong the impacts of eruptions on exposed communities and ecosystems. Since such phenomena are of interest to scientists from a range of disciplines (e.g., volcanology, atmospheric and soil sciences), a well-defined, common nomenclature is necessary to optimise the multidisciplinary characterisation of both processes and deposits. We, therefore, first describe ash wind-r…