scholarly journals Centre de documentation sur les bibliothèques, Bibliothèque nationale du Canada

2018 ◽  
Vol 19 (1) ◽  
pp. 20-22
Author(s):  
Marion C. Wilson
Keyword(s):  
Reference Orientation

Description du Centre et de ses collections faites surtout de rapports, d’articles de périodiques, de bulletins de nouvelles, de textes de lois, de renseignements sur des projets de recherche, etc..; énumération des services (référence, orientation) et des publications (Nouvelles acquisitions, Réunions à venir), tout en mettant l’accent sur le rôle national et international du centre.

Maneuverability Towing Tank Experiments With Manifold Models: Part I — Static Tests

2018 ◽  
Author(s):  
Felipe Augusto de Souza Kleine ◽  
Danyllo de Lima Guedes ◽  
Felipe Santos de Castro ◽  
Daniel Carvalho ◽  
João Lucas Dozzi Dantas
Keyword(s):  
Numerical Simulation ◽  
Simulation Studies ◽  
Dynamic Tests ◽  
Static Tests ◽  
Towing Tank ◽  
Technological Research ◽  
Reference Orientation ◽  
Hydrodynamic Derivatives ◽  
Manifold Models ◽  
Almost All

This work is the Part I of a two-part work, where the maneuverability of three manifold geometries was investigated by Towing Tank tests at the Institute for Technological Research, in order to verify the influence of geometrical simplifications and modifications. In this work is presented a comparison between the forces and moments measured in static drift tests, considering a pitch orientation ranging from 0 to 360 degrees, and the static hydrodynamic derivatives in a reference orientation. In the Part II, the investigations were complemented by the results of dynamic tests. The manifold models were constructed in a 1:13 scale. The first model was a geometrically simplified version of the prototype, composed of two simple blocks; the second one was constructed with almost all the prototype geometric details; the last one used the second model with a plate installed on its top. The tests results indicate that the geometrical simplification of manifold models did not have a significant influence on the maneuvering coefficients, in contrast to the addition of the top plate, which significantly changed the maneuvering capabilities of the model. The study presented in both papers will be used to form a data base for numerical simulation studies for manifolds installation.

Effects of Orientation Angles on the Singularity-Free Workspace and Orientation Optimization of the Gough–Stewart Platform

2009 ◽  
Vol 2 (1) ◽  
Author(s):  
Qimi Jiang ◽  
Clément M. Gosselin
Keyword(s):  
Stewart Platform ◽  
Robot Design ◽  
Parallel Mechanisms ◽  
Base Plane ◽  
Optimal Orientation ◽  
Reference Orientation ◽  
Global Optimal ◽  
Orientation Optimization

The singularity-free workspace of parallel mechanisms is highly desirable in a context of robot design. This work focuses on analyzing the effects of the orientation angles on the singularity-free workspace of the Gough–Stewart platform in order to determine the optimal orientation. In any orientation with ϕ=θ=0 deg and ψ≠±90 deg, the singularity surface becomes a plane coinciding with the base plane. Hence, an analytic algorithm is presented in this work to determine the singularity-free workspace. The results show that the singularity-free workspace in some orientations can be larger than that in the reference orientation with ϕ=θ=ψ=0 deg. However, the global optimal orientation is difficult to determine. Only an approximate optimal orientation is available. The results obtained can be applied to the design or parameter setup of the Gough–Stewart platform.

scholarly journals Fourientation activities and the Tutte polynomial

2020 ◽  
Vol DMTCS Proceedings, 28th... ◽  
Author(s):  
Spencer Backman ◽  
Sam Hopkins ◽  
Lorenzo Traldi
Keyword(s):  
Linear Order ◽  
Tutte Polynomial ◽  
Reference Orientation ◽  
International Audience

International audience A fourientation of a graph G is a choice for each edge of the graph whether to orient that edge in either direction, leave it unoriented, or biorient it. We may naturally view fourientations as a mixture of subgraphs and graph orientations where unoriented and bioriented edges play the role of absent and present subgraph edges, respectively. Building on work of Backman and Hopkins (2015), we show that given a linear order and a reference orientation of the edge set, one can define activities for fourientations of G which allow for a new 12 variable expansion of the Tutte polynomial TG. Our formula specializes to both an orientation activities expansion of TG due to Las Vergnas (1984) and a generalized activities expansion of TG due to Gordon and Traldi (1990).

scholarly journals Ionization delocalization and alchemi of B2-ordered alloys

1995 ◽  
Vol 53 ◽  
pp. 124-125
Author(s):  
I. M. Anderson ◽  
J. Bentley
Keyword(s):  
Spectral Line ◽  
Crystal Orientation ◽  
Correlation Coefficients ◽  
Atom Fraction ◽  
Linear Parameter ◽  
X Ray ◽  
Reference Orientation ◽  
Ordered Alloys ◽  
Line Characteristic ◽  
Electron Intensity

Recent formulations of the ALCHEMI technique have explicitly accounted for ionization delocalization of an element i with a single linear parameter Li,- that represents the extent of localization. The x-ray emission of a spectral line characteristic of the element is assumed to be proportional to a linear combination of the thickness-averaged electron intensity at (1) the site of the atom (fraction: Li) and (2) averaged over the unit cell (fraction:1 - Li)). The parameter Li is assumed to be characteristic of the elemental shell and independent of the diffracting conditions. In consequence of these assumptions, it has been shown that ionization delocalization correction can be performed in conjunction with "statistical" ALCHEMI by correcting only the extracted correlation coefficients.The parameter γiξ / Ii(0) is defined to be the ratio of the characteristic intensity (I) of element i at a crystal orientation (ξ) to its characteristic intensity at a reference orientation (0), which is ideally free of electron channeling effects.

scholarly journals Stochastic re-calibration: contextual effects on perceived tilt

2006 ◽  
Vol 273 (1601) ◽  
pp. 2681-2686 ◽  
Author(s):  
Joshua A Solomon ◽  
Michael J Morgan
Keyword(s):  
Visual Field ◽  
Visual System ◽  
Lateral Inhibition ◽  
Human Visual System ◽  
Contextual Effects ◽  
Letter Recognition ◽  
Tilt Illusion ◽  
Reference Orientation ◽  
The Difference

The human visual system exaggerates the difference between the tilts of adjacent lines or grating patches. In addition to this tilt illusion, we found that oblique flanks reduced acuity for small changes of tilt in the centre of the visual field. However, no flanks—regardless of their tilts—decreased sensitivity to contrast. Thus, the foveal tilt illusion should not be attributed to orientation-selective lateral inhibition. Nor is it similar to conventional crowding, which typically does not impair letter recognition in the fovea. Our observers behaved as though the reference orientation (horizontal) had a small tilt in the direction of the flanks. We suggest that the extent of this re-calibration varies randomly over trials, and we demonstrate that this stochastic re-calibration can explain flank-induced acuity loss in the fovea.

Evaluating Deformation-Induced Grain Orientation Change in a Polycrystal During In Situ Tensile Deformation using EBSD

2015 ◽  
Vol 21 (4) ◽  
pp. 969-984 ◽  
Author(s):  
Thomas E. Buchheit ◽  
Jay D. Carroll ◽  
Blythe G. Clark ◽  
Brad L. Boyce
Keyword(s):  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Correlation Technique ◽  
Polycrystalline Specimen ◽  
Initial Development ◽  
Orientation Change ◽  
Reference Orientation ◽  
Orientation Deviation ◽  
Backscatter Diffraction

AbstractUsing an in situ load frame within a scanning electron microscope, a microstructural section on the surface of an annealed tantalum (Ta) polycrystalline specimen was mapped at successive tensile strain intervals, up to ~20% strain, using electron backscatter diffraction. A grain identification and correlation technique was developed for characterizing the evolving microstructure during loading. Presenting the correlated results builds on the reference orientation deviation (ROD) map concept where individual orientation measurements within a grain are compared with a reference orientation associated with that grain. In this case, individual orientation measurements in a deformed grain are measured relative to a reference orientation derived from the undeformed (initial) configuration rather than the current deformed configuration as has been done for previous ROD schemes. Using this technique helps reveal the evolution of crystallographic orientation gradients and development of deformation-induced substructure within grains. Although overall crystallographic texture evolved slowly during deformation, orientation spread within grains developed quickly. In some locations, misorientation relative to the original orientation of a grain exceeded 20° by 15% strain. The largest orientation changes often appeared near grain boundaries suggesting that these regions were preferred locations for the initial development of subgrains.

A new approach to determine the maximal singularity-free zone of 3-RPR planar parallel manipulator

Robotica ◽  
2011 ◽  
Vol 30 (6) ◽  
pp. 1005-1012 ◽  
Author(s):  
G. Abbasnejad ◽  
H. M. Daniali ◽  
S. M. Kazemi
Keyword(s):  
Parallel Manipulator ◽  
Orientation Angle ◽  
Parallel Manipulators ◽  
Swarm Optimization ◽  
New Approach ◽  
Free Zone ◽  
Reference Orientation ◽  
Planar Parallel Manipulator ◽  
Different Types ◽  
Moving Platform

SUMMARYThis paper presents a new algorithm to find the singularity-free cylindrical workspace of parallel manipulators. Because of the limited workspace of parallel manipulators cluttered with different types of singularities, a simple and robust technique to determine continuous singularity-free zones in the workspace of parallel manipulators is required. Here, the largest singularity-free cylinder within the workspace for any prescribed orientation ranging around a reference orientation angle of moving platform is determined. To this end, Particle Swarm Optimization is utilized to find the closest point on the singularity surface to the axis of the cylinder. By implementing the algorithm on 3-RPR planar parallel manipulator, the results show that this algorithm improves the efficiency and leads to significantly larger singularity-free workspace than those reported earlier.

scholarly journals Torque-induced reorientation in active fibre-reinforced materials

Soft Matter ◽  
2019 ◽  
Vol 15 (9) ◽  
pp. 2081-2091 ◽  
Author(s):  
Jacopo Ciambella ◽  
Paola Nardinocchi
Keyword(s):  
Continuum Model ◽  
Reference Orientation ◽  
External Stimuli ◽  
Active Fibre ◽  
Reinforced Materials

We introduce a continuum model for a fibre reinforced material in which the reference orientation of the fibre may evolve with time, under the influence of external stimuli.

scholarly journals Recrystallized Grain Size in Single Phase Materials

2012 ◽  
Vol 715-716 ◽  
pp. 361-366
Author(s):  
Sheng Yu Wang ◽  
Anthony D. Rollett ◽  
Elizabeth A. Holm
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
Large Strain ◽  
Subgrain Structure ◽  
Typically Develop ◽  
Reference Orientation ◽  
Orientation Deviation ◽  
Recrystallized Grain Size ◽  
Von Mises ◽  
Good Agreement

During large-strain plastic deformation, subgrain structures typically develop within the grains. At large enough equivalent strains above, say 0.5, recrystallization occurs via abnormal coarsening of the subgrain structure or abnormal (sub-) grain growth (AsGG). The fraction of subgrains that develop into new, recrystallized grains has been quantified as a function of texture spread (Grain Reference Orientation Deviation) using Monte Carlo simulation. When this fraction is combined with the known monotonic increase in mean misorientation with strain, the recrystallized grain size can be predicted as a function of von Mises strain. The prediction is in good agreement with experimental results drawn from the literature.

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