102,215 research outputs found
MERLET (G.)
No full textDubois Patrick. MERLET (G.). In: Le dictionnaire de pédagogie et d'instruction primaire de Ferdinand Buisson : répertoire biographique des auteurs. Paris : Institut national de recherche pédagogique, 2002. p. 107. (Bibliothèque de l'Histoire de l'Education, 17
Liouville type results for local minimizers of the micromagnetic energy
No full textWe study local minimizers of the micromagnetic energy in small ferromagnetic 3d convex particles for which we justify the Stoner–Wohlfarth approximation: given a uniformly convex shape Ω⊂R3, there exist δc>0 and C>0 such that for 01, p≠d) is constant
Notice sur M. l'abbé G.-C. Merlet, prêtre habitué à Courtenay (4 mars 1876)
No full textAppartient à l’ensemble documentaire : Centre1Avec mode text
An investigation of the structure and bond rotational potential of some fluorinated ethanes by NMR spectroscopy of solutions in nematic liquid crystalline solvents
No full textNMR spectra of 1,2-dibromo-1,1-difluoroethane and 1-bromo-2-iodo-tetrafluoroethane dissolved in nematic liquid crystalline solvents have been analysed to yield the magnitudes and signs of the scalar couplings, J(ij), and total anisotropic couplings, T-ij, between all the H-1, F-19, and C-13 nuclei, except for those between two C-13 nuclei. The values obtained for Tij in principle contain a contribution from J(ij)(aniso), the component along the static applied magnetic field of the anisotropic part of the electron-mediated spin-spin coupling. Neglecting this contribution allows partially averaged dipolar couplings, D-ij, to be extracted from the T-ij, and these were used to determine the structure, orientational order, and the conformational distribution generated by rotation about the C-C bond. The values obtained are compared with the results of calculations by ab initio and density functional methods. The differences found are no greater than those obtained for similar compounds which do not contain fluorine, so that there is no definitive evidence for significant contributions from J(CF)(aniso) or J(FF)(aniso) in the two compounds studied
The kinematics of the redundant wire driven parallel robot
No full textWe address the kinematics of the redundant wire-driven parallel
robot, i.e. a robot with wires connected at the same point on the
platform. The redundancy allows one to increase the workspace
size. But we show, both theoretically and experimentally that if the
wires are not elastic, then the redundancy cannot be used to control
the wire tensions. Indeed we show that whatever are the number of
wires there will always be only at most 3 wires in tension, while the oth
er
wires will be slack. We then show that if the wires are elastic,
then the platform positioning will be very sensitive to stiffness
identification and wire lengths control. Hence classical redundant
control schemes are difficult to use for such robot and alternate use of
the
geometry of redundant wires have to be considered
Comparison of actuation schemes for wire-driven parallel robots
No full textThere are two main systems that can be used to coil and uncoil the
wires of a wire-driven parallel robots: a rotary motor that turns a
drum on which the wire is coiled or a linear motor with a pulley
system. The rotary category may be divided into two sub-categories:
the system with a spiral guide for the coiling, allowing only layer
for the wire and the system without guide, that allows for several
wire layers with the drawback that the amount of coiled wire for one
motor turn depends upon the number of layer. All three systems are
compared in terms of accuracy and compacit
Obtaining the structure and bond rotational potential of a substituted ethane by NMR spectroscopy of solutions in nematic liquid-crystalline solvents
No full textPartially averaged dipolar couplings (also referred to as residual dipolar couplings) Dij can be obtained from the analysis of the NMR spectra of molecules dissolved in liquid-crystalline solvents. Their values for a nonrigid molecule depend upon the bond lengths and angles, the rotational potentials, and the orientational order of the molecules. The molecule studied, 1-chloro-2-bromoethane, is one of the simplest example of a substituted alkane in which the rotational potential has three minimum-energy positions, trans and gauche±conformations, and the present investigation explores the problems inherent in deriving the form of the potential and the molecular geometry from the set of partially averaged couplings between the protons, and between protons and 13C nuclei. The geometrical parameters and the rotational potential obtained are compared with the results from a density-functional theory method
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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