Episciences.org
Not a member yet
6707 research outputs found
Sort by
Dynamic Behavior of a Railway Track Under a Moving Wheel Load Modelled as a Sinusoidal Pulse
No full textThe aim of this paper is to evaluate the train/track induced loads on thesubstructure by modelling the wheel, at each instant, as a moving sinusoidalpulse applied in a very short period of time. This assumption has the advantageof being more realistic as it reduces the impact of time on the loaddefinition. To that end, mass, stiffness, and dumping matrices of an elementarysection of track will be determined. As a result, the equations of motion of asection of track subjected to a sinusoidal pulse and a rectangular pulserespectively is concluded. Two numerical methods of resolution of thatequation, depending on the nature of the dumping matrix, will be presented. Thecomputation results will be compared in order to conclude about the relevanceof that load model. This approach is used in order to assess the nature and thevalue of the loads received by the substructure
The Functional Machine Calculus
No full textThis paper presents the Functional Machine Calculus (FMC) as a simple modelof higher-order computation with "reader/writer" effects: higher-order mutablestore, input/output, and probabilistic and non-deterministic computation. The FMC derives from the lambda-calculus by taking the standard operationalperspective of a call-by-name stack machine as primary, and introducing twonatural generalizations. One, "locations", introduces multiple stacks, whicheach may represent an effect and so enable effect operators to be encoded intothe abstraction and application constructs of the calculus. The second,"sequencing", is known from kappa-calculus and concatenative programminglanguages, and introduces the imperative notions of "skip" and "sequence". Thisenables the encoding of reduction strategies, including call-by-valuelambda-calculus and monadic constructs. The encoding of effects into generalized abstraction and application meansthat standard results from the lambda-calculus may carry over to effects. Themain result is confluence, which is possible because encoded effects reducealgebraically rather than operationally. Reduction generates the familiaralgebraic laws for state, and unlike in the monadic setting, reader/writereffects combine seamlessly. A system of simple types confers termination of themachine.Comment: 24 pages. To appear in Electronic Notes in Theoretical Informatics and Computer Science (ENTICS
Quasiexact posets and the moderate meet-continuity
No full textThe study of weak domains and quasicontinuous domains leads to theconsideration of two types generalizations of domains. In the current paper, wedefine the weak way-below relation between two nonempty subsets of a poset andquasiexact posets. We prove some connections among quasiexact posets,quasicontinuous domains and weak domains. Furthermore, we introduce the weakway-below finitely determined topology and study its links to Scott topologyand the weak way-below topology first considered by Mushburn. It is also provedthat a dcpo is a domain if it is quasiexact and moderately meet continuous withthe weak way-below relation weakly increasing
Continuous R-valuations
No full textWe introduce continuous -valuations on directed-complete posets (dcpos,for short), as a generalization of continuous valuations in domain theory, byextending values of continuous valuations from reals to so-called Abeliand-rags . Like the valuation monad introduced by Jones and Plotkin, weshow that the construction of continuous -valuations extends to a strongmonad on the category of dcpos and Scott-continuous maps.Additionally, and as in recent work by the two authors and C. Th\'eron, and bythe second author, B. Lindenhovius, M. Mislove and V. Zamdzhiev, we show thatwe can extract a commutative monad out of it, whose elementswe call minimal -valuations. We also show that continuous -valuations have close connections tomeasures when is taken to be , the intervaldomain of the extended nonnegative reals: (1) On every coherent topologicalspace, every non-zero, bounded -smooth measure (defined on theBorel -algebra), canonically determines a continuous-valuation; and (2) such a continuous-valuation is the most precise (in a certainsense) continuous -valuation that approximates, when the support of is a compact Hausdorff subspace of asecond-countable stably compact topological space. This in particular appliesto Lebesgue measure on the unit interval. As a result, the Lebesgue measure canbe identified as a continuous -valuation.Additionally, we show that the latter is minimal
Chambéry, une ville en plaine inondable: Un exemple de la gestion de l’eau sur le site des halles
No full textParmi les villes émergeant au cours de la période médiévale, certaines sont établies sur des terrains inhospitaliers, dans des secteurs éloignés de l'habitat antique et/ou du Premier Moyen-Âge. C'est le cas de Chambéry, en Savoie, qui se développe, à partir des XIe-XIIe siècles, sur des terrains inondables traversés par des rivières aux régimes torrentiels. Le bourg devient au XVe siècle capitale du duché de Savoie. Si son noyau central n'a pas fait l'objet d'opérations archéologiques, les fouilles menées dans les années 2000 sur ses abords immédiats apportent un éclairage sur les modalités de la prise en compte des contraintes environnementales de la plaine inondable, dans le processus d'extension de la ville, à la fin du Moyen-Âge, et sur les façons de l'investir et de l'habiter. Nourris du dialogue entre données de terrain, analyse géomorphologique et sources d'archives, leurs résultats illustrent la mise en place, le développement et la gestion d'un réseau de drainage par canaux ou la variété des techniques de construction adaptées aux sols humides
Alternating Roots of Polynomials over Cayley-Dickson Algebras
No full textWe introduce the notions of alternating roots of polynomials and alternatingpolynomials over a Cayley-Dickson algebra, and prove a connection between thealternating roots of a given polynomial and the roots of the correspondingalternating polynomial over the Cayley-Dickson doubling of the algebra. We alsoinclude a detailed Octave code for the computation of alternating roots overHamilton's quaternions
Remarks on the geometry of the variety of planes of a cubic fivefold
No full textThis note presents some properties of the variety of planes F_2(X)\subsetG(3,7) of a cubic -fold . A cotangent bundle exactsequence is first derived from the remark made by Iliev and Manivel that sits as a Lagrangian subvariety of the variety of lines of a cubic-fold, which is a hyperplane section of . Using the sequence, the Gaussmap of is then proven to be an embedding. The last section is devotedto the relation between the variety of osculating planes of a cubic -foldand the variety of planes of the associated cyclic cubic -fold
Un cadre conceptuel pour la gestion de la performance des organisations sportives (SOPEM) : une application à la Fédération Française de la Randonnée Pédestre
No full textHow can we measure performance in sport organisations? The usual framework for organisational performance in sport federations is two-stage: measuring and managing performance. A new framework is proposed by adding two intermediate stages for analysing and reporting performance. The four-stage framework is applied to the French Federation of Hiking, a leisure-oriented federation with an aging and primarily female membership. Data comes from administrative membership records over a nine-year period (2011-2019), corresponding to 2 million multivariate observations, i.e. over 20 million available data. The analysing stage combines marketing and advanced sociodemographic statistics.A discrete-time logistic binomial model of the probability of leaving the federation demonstrates the importance of considering membership duration, age (albeit in a nonlinear way) and interesting interactions with members’ sex. Value for money is demonstrated for several stakeholders (e.g. 1 euro of public subsidies corresponds to 485 euros of volunteer work). The new framework proposes a cycle of measuring, analysing, reporting and managing performance. It can be entered at any stage and used to create or cocreate a specific performance system depending on the goals and means of the sport federation considered.Comment mesurer la performance dans les organisations sportives ? Le cadre d’analyse habituel de la performance organisationnelle dans les fédérations sportives se déroule en deux étapes : mesurer puis gérer la performance. Nous proposons ici un nouveau cadre en y ajoutant deux étapes intermédiaires pour analyser et rendre compte de la performance de ces organisations sportives.Ce cadre en quatre étapes est appliqué à la Fédération Française de la Randonnée Pédestre, une fédération orientée vers les loisirs, dont les licenciés sont âgés et principalement des femmes. Les données proviennent des inscriptions administratives des licenciés sur une période de neuf ans (2011-2019), ce qui correspond à 2 millions d’observations multivariées, soit plus de 20 millions de données disponibles. L’étape d’analyse combine marketing et statistiques sociodémographiques avancées.En particulier, un modèle binomial logistique en temps discret de la probabilité de quitter la fédération démontre l’importance de prendre en compte la durée d’adhésion, l’âge (bien que de manière non linéaire) et des interactions intéressantes avec le sexe des licenciés. L’optimisation des ressources est démontrée pour plusieurs parties prenantes (par exemple, 1€ de subventions publiques correspond à 485€ de travail bénévole).Ce nouveau cadre propose un cycle de mesure, d’analyse, de compte-rendu et de management de la performance. Il peut être utilisé pour créer ou cocréer un système de performance spécifique en fonction des objectifs et des moyens de la fédération sportive considérée
THE FUTURE OF POST-KEYNESIAN ECONOMICS: Post-Keynesian Economics at 50
No full textThis article discusses the future of post-Keynesian economics by considering three angles: i) the future of post-Keynesian economics as an institution or as a school of thougth; ii) the future of post-Keynesian theory; and finally, iii) the future of post-Keynesian within the profession. My conclusion is fairly positive overall, although the place of post-Keynesian economics within the profession is certainly not enviable
The number of distinct adjacent pairs in geometrically distributed words: a probabilistic and combinatorial analysis
No full textThe analysis of strings of random variables with geometric distributionhas recently attracted renewed interest: Archibald et al. consider the numberof distinct adjacent pairs in geometrically distributed words. They obtain theasymptotic () mean of this number in the cases of differentand identical pairs. In this paper we are interested in all asymptotic momentsin the identical case, in the asymptotic variance in the different case and inthe asymptotic distribution in both cases. We use two approaches: the firstone, the probabilistic approach, leads to variances in both cases and to someconjectures on all moments in the identical case and on the distribution inboth cases. The second approach, the combinatorial one, relies on multivariatepattern matching techniques, yielding exact formulas for first and secondmoments. We use such tools as Mellin transforms, Analytic Combinatorics, MarkovChains.Comment: 47 pages, 4 figure