Search results for "Tractors"

Blenders near polynomial product maps of $\mathbb C^2$

2021

In this paper we show that if $p$ is a polynomial which bifurcates then the product map $(z,w)\mapsto(p(z),q(w))$ can be approximated by polynomial skew products possessing special dynamical objets called blenders. Moreover, these objets can be chosen to be of two types : repelling or saddle. As a consequence, such product map belongs to the closure of the interior of two different sets : the bifurcation locus of $H_d(\mathbb P^2)$ and the set of endomorphisms having an attracting set of non-empty interior. In an independent part, we use perturbations of H\'enon maps to obtain examples of attracting sets with repelling points and also of quasi-attractors which are not attracting sets.

Analogical reasoning performance and organization is influenced by the type of semantic distractors : an investigation with adults

2015

International audience; The way participants adapt their search to the specifics of different types of analogies is not fully understood. We compared the effects of two types of semantic distractors. The first were related to C by a semantic relation which had nothing to do with the semantic relation used in the A:B pairs, whereas the second, the so-called "double distractors", were not only related to C but also had a semantic relation similar to the one linking A to B. We used eye-tracking measurements in addition to reaction time and performance indices. We found that performance decreased, and that the solution set was less explored visually with the double distractors than with the for…

TRACLAS: a project to improve under canopy tractor safety in case of overturning

2018

Poster Abstract non previsto

Structural Stability

2020

The notion of structural stability was first introduced by the Russian math- ematicians Alexandr Andronov and Lev Pontryagin (cf. Andronov and Potryangin 1937). However, there are traces of such a concept in the work of the French math- ematician Henry Poincaré (cf. Poincaré 1880). In more recent years, interesting developments about structural stability included writings of important math- ematicians like Mauricìo Peixoto (cf. at least Peixoto 1960), Stephen Smale (cf. at least Smale 1971) and René Thom (1972, 1980) (see structural morpho- dynamics). From an intuitive point of view, structural stability refers to a particular systemic property known as robustness. Put in general terms, a s…

A methodology to select the price criterion in public procurement

2015

[EN] The construction sector is a key driver for economic growth in any nation and public procurement is one of its pillars hence the importance of the study and investigation of its mechanisms, especially tendering criteria. Price is the main deciding factor for most tenders and projects must have an appropriate base price relative to market price to avoid problems during the execution of the project. Most research on price criteria has been developed from the point of view of bidders and has discussed the development of tools and methodologies for determining the optimal bid price. In this paper we propose a methodology for public procurement procedures from the point of view of the admin…

Connaissances nécessaires à la gestion du risque "écorces sensibles au nématode du pin"

2018

Connaissances nécessaires à la gestion du risque "écorces sensibles au nématode du pin"

Phytoextractors of metal(loid)s of the Italian flora: An Outline

Intensive farming, wastewater irrigation, mining, heavy industry, smelting procedures and improper waste disposal are some of the human activities that contribute to heavy metal soil contamination (Sharma et al. 2007; Khan et al. 2008; Yu et al. 2008). As heavy metals cannot be degraded by microorganisms and tend to remain in polluted sites for long periods of time, soil contamination by heavy metals represents a particular environmental concern and a serious threat to human health. Conventional soil remediation techniques, such as soil washing, excavation, in situ vitrification, solidification and stabilization, can be effectively employed in order to achieve remediation of heavy metal con…

Distractor Efficiency in an Item Pool for a Statistics Classroom Exam: Assessing Its Relation With Item Cognitive Level Classified According to Bloom…

2018

Multiple-choice items are one of the most commonly used tools for evaluating students’ knowledge and skills. A key aspect of this type of assessment is the presence of functioning distractors, i.e., incorrect alternatives intended to be plausible for students with lower achievement. To our knowledge, no work has investigated the relationship between distractor performance and the complexity of the cognitive task required to give the correct answer. The aim of this study was to investigate this relation, employing the first three levels of Bloom’s taxonomy (Knowledge, Comprehension, and Application). Specifically, it was hypothesized that items classified into a higher level of Bloom’s class…

Hidden attractors in electromechanical systems with and without equilibria

2016

This paper studies hidden oscillations appearing in electromechanical systems with and without equilibria. Three different systems with such effects are considered: translational oscillator-rotational actuator, drilling system actuated by a DC-motor and drilling system actuated by induction motor. We demonstrate that three systems experience hidden oscillations in sense of mathematical definition. While some of these hidden oscillations can be easily seen in natural physical experiments, the localization of others requires special efforts. peerReviewed

Hidden attractors in Chua circuit: mathematical theory meets physical experiments

2022

AbstractAfter the discovery in early 1960s by E. Lorenz and Y. Ueda of the first example of a chaotic attractor in numerical simulation of a real physical process, a new scientific direction of analysis of chaotic behavior in dynamical systems arose. Despite the key role of this first discovery, later on a number of works have appeared supposing that chaotic attractors of the considered dynamical models are rather artificial, computer-induced objects, i.e., they are generated not due to the physical nature of the process, but only by errors arising from the application of approximate numerical methods and finite-precision computations. Further justification for the possibility of a real exi…