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Reactions of aliphatic terminal alkynes with Ti(OiPr)4/BuLi: selectivity, kinetic aspects, and a new tetramerisation process
No full textInternational audienceThe reactions of terminal aliphatic alkynes with Ti(OiPr)4/nBuLi or Ti(OiPr)4/sBuLi were investigated. Thesesubstrates were transformed more slowly than previously studied 1-aryl acetylene compounds and mixturesof products were generally obtained. This allowed the rate constants of the elementary steps involved to beevaluated. One substrate was shown to undergo cyclotrimerisation with high regioselectivity in favour of the1,2,4 adduct. Furthermore, an unprecedented tetramerisation process was uncovered
Interval Methods applied to Signal Temporal Logic - Overview and Extension on Tubes
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A simple kinematics to model the behavior of pressurized elbows under cyclic in-plane bending
No full textInternational audienceThis paper presents a simple and efficient way to calculate the ratcheting strains at the critical locations of a pressurized elbow subjected to cycles of in-plane opening/closing. To do so, a kinematics initially proposed by Boussaa and al. [Finite pure bending of curved pipes. 1996. Comput. Struct. 60, 1003-1012] is presented and a way to use it in ANSYS finite element software is described. The kinematics only describes the elbow behavior when it is subjected to pure in-plane bending. The considered loading must be an history of imposed moment or elbow angle variation. Results using this kinematics are compared with experimental and numerical results of two papers from the literature. Values of ratcheting strains at critical locations of the elbow obtained with the proposed kinematics are very comparable with the ones of the literature. Moreover, computation time is divided by around 200 when using this kinematics over a shell finite element model
Seismic soil-structure interaction study of inclusion reinforced foundations with a macro-element
No full textInternational audienceThe reinforcement technique using rigid inclusions is a practical, cost-effective, and time-saving foundation solution. This technique has already proven successful in supporting structures that are subject to high seismic demands, such as the Rio-Antirrio bridge in Greece. In a performance-based design approach, it is important to consider the dynamic soil-structure interaction phenomenon, which is specially relevant when dealing with soft soils. Direct approaches simulating the whole soil-structure system within the same numerical model are still computationally expensive and the classic modal response spectrum analyses, based on the superposition principle, are not capable of taking into account most of nonlinear mechanisms. The macro-element approach is therefore a promising method, as it allows modelling of nonlinear soil-structure interaction mechanisms at the base of the structure without increasing the numerical cost. This approach has shown particularly good performance in the dynamic analysis of shallow and piled foundations. The present paper aims to extend the application of the macro-element approach to foundations on rigid inclusions. To this end, the upper-bound kinematic exterior approach is employed to derive a yield surface corresponding to this type of foundation. Its potential application in the context of non-linear soil-structure interaction studies is also discussed
Firms' sustainable and responsible innovation in Nigeria: Does informality play a role?
No full textInternational audienceAt the turn of the millennium, developing countries face a twofold challenge. First, for reasons related to both intra‐ and inter‐generational justice, these countries need to follow sustainable development pathways. Second, they need to understand the deep principles underpinning informality, which is by now recognized as a structuring phenomenon of their economies. This paper sheds light on the relationship between these two goals by investigating how a Nigerian firm being formal versus informal affects its sustainable and responsible innovation (S&RI) activity. Using the entropy balancing methodology to analyze a novel database extracted from the Nigerian Business Innovation Surveys, we find that registered Nigerian firms engage in S&RI much more than those that are not. This suggests that, from the perspective of sustainable development, there should be no hiatus between recognizing the important role of the informal sector in the economy and promoting policies that give firms incentives to exit from it. By encouraging the registration of firms operating informally, these policies should help Nigeria in its transition to a sustainable market economy
The Moment That The Driver Takes Over: Examining trust in full-self driving in a naturalistic and sequential approach
No full textInternational audienceIn this paper, we have documented the challenges that drivers with autopilots experience on real-world roads, by focusing on the practices of humans taking over. We analyze data of full self-driving cars selected from third-party YouTube videos in a conversation analytic approach. We have shown how drivers treat the car’s moment-by-moment motion as actions that are projectable for potentially relevant risky outcomes, and how they take over the full self-driving system in situ and in vivo, with continuous situated monitoring. We have demonstrated four typical situations in which drivers take over in the unfolding course of driving action, that is, going too close to the front car, inappropriate speed in the local context, wrong recognition of lanes, and pedestrian priority. We argue that the achievement of human takeovers is inextricably connected to the situated organization and accountability of the course of action
High harmonic generation in Solids driven by high energy fiber laser source
No full textInternational audienceWe present findings on High Harmonic Generation (HHG) in solids utilizing a high-energy fiber laser system operating at 1550 nm. The driving laser source comprises an Erbium-Doped Fiber chirped pulse Amplifier (EDFA) combined with a post-compression stage employing a hollow-core photonic crystal fiber (HC-PCF) filled with noble gases. Nonlinear self-compression in the HC-PCF enables the generation of ultrashort pulses with a duration of 50 fs and energy of 0.91 μJ at a repetition rate of 660 kHz. In a first step, harmonics up to H7 were observed when focusing the laser into small bandgap materials such as Zinc Oxide (ZnO). Subsequently, the system was enhanced to measure high harmonics in the extreme ultraviolet (XUV) range, with harmonics up to H25 observed using a large bandgap material, magnesium oxide (MgO). To the best of our knowledge, this represents the first solid-state HHG source driven by a high-energy few-cycle fiber laser in the telecom regio
Une revue de littérature sur les méthodes d'analyse des curricula d'ingénieurs en matière de Développement durable
No full textInternational audienceOver the last two decades, numerous studies have highlighted the significance of integrating sustainability into higher education. Consequently, there has been a growing interest in the literature on engineering education for sustainable development, emphasizing the inclusion of this concept within engineering curricula and recognizing the pivotal role that engineers play in achieving the sustainable development goals. Therefore, sporadic engineering faculties worldwide have begun acknowledging and assessing issues related to sustainability in their curricula. As several methods have been employed to assess its inclusion, the aim of this paper is to review the various methods used to gauge how sustainability is incorporated in their respective engineering curricula. We carried out a systematic review of the literature regarding sustainability as assessed specifically in engineering curricula using the Scopus and ERIC databases. We applied PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology and, as a result, 30 papers were included. The results produced 14 methods with the articles highlighting existing limitations. Therefore, the authors recommend the combination of at least two of the methods to efficiently evaluate sustainability in engineering curricula
