Jurnal Edukasi
Not a member yet
4879 research outputs found
Sort by
Equivalence between Exact and Approximate Controllability for Finite-Dimensional Quantum Systems
No full textInternational audienc
Stable time step estimates for NURBS-based explicit dynamics
No full textInternational audienceAutomobile crashworthiness is a complex application for numerical methods in dynamics of structures which includes many high non-linearities. Explicit techniques are widely used for structural dynamics dealing with difficult and large problems that prevent the use of implicit methods. We propose, in this paper, a deep study of the stable time step, which guarantees the stability of the method, and its estimates, for one-dimensional and two-dimensional problems. Element and nodal time steps are presented and adapted to highly regular B-spline and NURBS functions, in the context of isogeometric analysis. The size of the proposed stable time estimates benefits from the properties of regularity and extended support of the basis. Their performance is assessed and compared in several examples, with an arbitrary mesh, uniform or non-uniform, and considering polynomial orders from one to five. The smoothness and order of the polynomials have a significant effect on the stable time step and its estimates. Several lumping schemes of the mass matrix are presented and their accuracy is assessed
Receptivity and sensitivity of the leading-edge boundary layer of a swept wing
No full textInternational audienceA global stability analysis of the boundary layer in the leading edge of a swept wingis performed in the incompressible flow regime. It is demonstrated that the globaleigenfunctions display the features characterizing the local instability of the attachmentline, as in swept Hiemenz flow, and those of local cross-flow instabilities furtherdownstream along the wing. A continuous connection along the chordwise directionis established between the two local eigenfunctions. An adjoint-based receptivityanalysis reveals that the global eigenfunction is most responsive to forcing appliedin the immediate vicinity of the attachment line. Furthermore, a sensitivity analysisidentifies the wavemaker at a location that is also very close to the attachmentline where the corresponding local instability analysis holds: the local cross-flowinstability further along the wing is merely fed by its attachment-line counterpart. Asa consequence, global mode calculations for the entire leading-edge region only needto include attachment-line structures. The result additionally implies that effectiveopen-loop control strategies should focus on base-flow modifications in the region where the local attachment-line instability prevails
Boundary Integral Equations for the Transmission Eigenvalue Problem for Maxwell’s Equations
No full textInternational audienceIn this paper we consider the transmission eigenvalue problem for Maxwell’s equations corresponding to non-magnetic inhomogeneities with contrast in electric permittivity that changes sign inside its support. We formulate the transmission eigenvalue problem as an equivalent homogeneous system of boundary integral equa- tion, and assuming that the contrast is constant near the boundary of the support of the inhomogeneity, we prove that the operator associated with this system is Fredholm of index zero and depends analytically on the wave number. Then we show the existence of wave numbers that are not transmission eigenvalues which by an application of the analytic Fredholm theory implies that the set of transmission eigenvalues is discrete with positive infinity as the only accumulation point
Managing Societal Performance of Impact Investing: An Action Research Inquiry
No full textImpact investments are emerging as a new asset class of social finance, sometimes driven by multinational enterprises as part of their strategic corporate social responsibility strategy. These investments intend to create positive societal impact beyond a financial return through the development of social enterprises. Scholars have highlighted the conflicting institutional logics that these later hybrid organizations must face when combining social welfare and profitability. Yet we lack in-depth insight into how impact investing funds are building their own accountability and legitimacy, and more specifically how they are responding to their investor’s pressure to manage societal impact. This paper builds on a three year actionresearch program conducted with Schneider Electric, a multinational enterprise specialized in energy management. The company initiated and sponsored an impact investing fund targeting energy access ventures in Sub-Saharan Africa, alongside four Development Finance Institutions. Grounded in neo-institutional and resource dependence theories, the article analyzes the perceptions of the fund’s managers and suggests a pattern of strategic responses. The fund initially conformed to the emerging values and practices of the industry motivated by a search for salient legitimacy. Then they turned to find a compromise when facing operational complexity, and negotiated the increasing number of requirements from their investors. The paper further provides recommendation for social innovation actors in adopting a performance-oriented approach for managing societal value creation
A Note on the Complexity of Classical and Intuitionistic Proofs
No full textInternational audience—We show an effective cut-free variant of Glivenko's theorem extended to formulas with weak quantifiers (those without eigenvariable conditions): " There is an elementary function f such that if ϕ is a cut-free LK proof of A with symbol complexity ≤ c, then there exists a cut-free LJ proof of ¬¬A with symbol complexity ≤ f (c) ". This follows from the more general result: " There is an elementary function f such that if ϕ is a cut-free LK proof of A with symbol complexity ≤ c, then there exists a cut-free LJ proof of A with symbol complexity ≤ f (c) ". The result is proved using a suitable variant of cut-elimination by resolution (CERES) and subsumption
Vers une Génération Efficace d’Analyses de Sûreté de Fonctionnement dans le Cadre du Déploiement de l’ISO 26262
No full textCars embed a steadily increasing number of Electric and Electronic Systems. The ISO 26262 standard dis-cusses at length the requirements that these systems must follow in order to guaranty their functional safety.One of the means at hand to ensure the automotive systems safety is to perform safety analyses. During these analyses, practitioners perform FTA and FMEDA in order to evaluate the “trust” that we have in a system. As big quantities of data are handled in those analyses, it would be of great help for them to have the possibility to efficiently generate a part of them and check their consistency.This manuscript is the result of a thesis led on this subject. It focuses on the formalization of the data handled during the safety analyses in order to propose an efficient methodology for their generation. It presents the different works done, from the proposition of formal models for the safety related element behavior representation to the design and implementation of a process for consistent FMEDA generation based on Fault tree patterns.La complexité et la criticité des systèmes électroniques embarqués automobiles est en augmentation constante. Un nouveau standard concernant la sûreté de fonctionnement automobile (ISO 26262) permet d'établir un cadre et de définir des exigences sur les systèmes concernés afin de garantir leur sécurité.Un des moyens permettant de vérifier la sûreté de ces systèmes consiste à effectuer des analyses dites de sureté de fonctionnement. Au cours de ces analyses, les praticiens effectuent des analyses de type FTA et FMEDA afin d’évaluer robustesse et la sûreté de ces systèmes. Lors de ces analyses, les praticiens manipulent une masse de données de plus en plus conséquente ; Ce qui a créé le besoin d’avoir un moyen de générer une partie de ces données efficacement et de vérifier leur cohérence.Dans ce manuscrit, nous détaillons les travaux que nous avons effectués sur ce sujet, en nous concentrant principalement sur la formalisation des données manipulées durant les analyses de sûreté de fonctionnement afin de proposer une méthode efficace pour leur génération. Nous y présentons les différents travaux réalisés, de la proposition de modèles formels pour la représentation du comportement dysfonctionnel « d’élément lié à la sûreté » à la conception et mise en œuvre d'un processus pour la génération de FMEDA cohérentes à partir d’arbres de défaillances
