Kinematic structure of the inner zones of disc galaxies

2003 ◽  
Vol 10 ◽  
pp. 37-37
Author(s):  
J. C. Vega Beltrán ◽  
P. Erwin ◽  
J. Beckman
Keyword(s):  
Kinematic Structure ◽  
Disc Galaxies

Design of a Human Knee Reeducation Mechanism

2019 ◽  
Vol 11 (1) ◽  
pp. 42-53
Author(s):  
Allaoua Brahmia ◽  
Ridha Kelaiaia
Keyword(s):  
Lower Limb ◽  
Mechanical Design ◽  
Kinematic Chain ◽  
Lower Limbs ◽  
Kinematic Structure ◽  
Robotic Device ◽  
Human Knee ◽  
Kinematic Study ◽  
Rehabilitation Exercise ◽  
New Machine

Abstract To establish an exercise in open muscular chain rehabilitation (OMC), it is necessary to choose the type of kinematic chain of the mechanical / biomechanical system that constitutes the lower limbs in interaction with the robotic device. Indeed, it’s accepted in biomechanics that a rehabilitation exercise in OMC of the lower limb is performed with a fixed hip and a free foot. Based on these findings, a kinematic structure of a new machine, named Reeduc-Knee, is proposed, and a mechanical design is carried out. The contribution of this work is not limited to the mechanical design of the Reeduc-Knee system. Indeed, to define the minimum parameterizing defining the configuration of the device relative to an absolute reference, a geometric and kinematic study is presented.

scholarly journals The nature of giant clumps in high-z discs: a deep-learning comparison of simulations and observations

2020 ◽  
Vol 501 (1) ◽  
pp. 730-746
Author(s):  
Omri Ginzburg ◽  
Marc Huertas-Company ◽  
Avishai Dekel ◽  
Nir Mandelker ◽  
Gregory Snyder ◽  
...  
Keyword(s):  
Neural Network ◽  
Deep Learning ◽  
Main Sequence ◽  
High Redshift ◽  
High Mass ◽  
Galactic Centre ◽  
Preferential Formation ◽  
Maximum Resolution ◽  
Supernova Feedback ◽  
Disc Galaxies

ABSTRACT We use deep learning to explore the nature of observed giant clumps in high-redshift disc galaxies, based on their identification and classification in cosmological simulations. Simulated clumps are detected using the 3D gas and stellar densities in the VELA zoom-in cosmological simulation suite, with ${\sim}25\ \rm {pc}$ maximum resolution, targeting main-sequence galaxies at 1 < z < 3. The clumps are classified as long-lived clumps (LLCs) or short-lived clumps (SLCs) based on their longevity in the simulations. We then train neural networks to detect and classify the simulated clumps in mock, multicolour, dusty, and noisy HST-like images. The clumps are detected using an encoder–decoder convolutional neural network (CNN), and are classified according to their longevity using a vanilla CNN. Tests using the simulations show our detector and classifier to be ${\sim}80{{\ \rm per\ cent}}$ complete and ${\sim}80{{\ \rm per\ cent}}$ pure for clumps more massive than ∼107.5 M⊙. When applied to observed galaxies in the CANDELS/GOODS S+N fields, we find both types of clumps to appear in similar abundances in the simulations and the observations. LLCs are, on average, more massive than SLCs by ∼0.5 dex, and they dominate the clump population above Mc ≳ 107.6 M⊙. LLCs tend to be found closer to the galactic centre, indicating clump migration to the centre or preferential formation at smaller radii. The LLCs are found to reside in high-mass galaxies, indicating better clump survivability under supernova feedback there, due to clumps being more massive in these galaxies. We find the clump masses and radial positions in the simulations and the observations to agree within a factor of 2.

scholarly journals Probing the 2-D kinematic structure of early-type galaxies out to 3 effective radii

2009 ◽  
Vol 5 (H15) ◽  
pp. 67-67
Author(s):  
Robert N. Proctor ◽  
Duncan A. Forbes ◽  
Aaron J. Romanowsky ◽  
Jean P. Brodie ◽  
Jay Strader ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Rotation Velocity ◽  
New Technique ◽  
Kinematic Structure ◽  
Early Type ◽  
Spectroscopic Observations ◽  
Velocity Moments

We detail an innovative new technique for measuring the 2-D velocity moments (rotation velocity, velocity dispersion and Gauss-Hermite coefficients h3 and h4) using spectra from Keck DEIMOS multi-object spectroscopic observations. The data are used to reconstruct 2-D rotation velocity maps.

scholarly journals Resonant effects during the tidal encounter of disc galaxies

1983 ◽  
Vol 204 (2) ◽  
pp. 507-518 ◽  
Author(s):  
Philip L. Palmer
Keyword(s):  
Disc Galaxies

A New Technique Based on Loops to Investigate Displacement Isomorphism in Planetary Gear Trains

2002 ◽  
Vol 124 (4) ◽  
pp. 662-675 ◽  
Author(s):  
V. V. N. R. Prasad Raju Pathapati ◽  
A. C. Rao
Keyword(s):  
Graph Isomorphism ◽  
Planetary Gear ◽  
Degree Of Freedom ◽  
Gear Train ◽  
Graph Representation ◽  
Kinematic Structure ◽  
Graph Representations ◽  
Planetary Gear Trains ◽  
Gear Trains ◽  
A New Technique

The most important step in the structural synthesis of planetary gear trains (PGTs) requires the identification of isomorphism (rotational as well as displacement) between the graphs which represent the kinematic structure of planetary gear train. Previously used methods for identifying graph isomorphism yielded incorrect results. Literature review in this area shows there is inconsistency in results from six link, one degree-of-freedom onwards. The purpose of this paper is to present an efficient methodology through the use of Loop concept and Hamming number concept to detect displacement and rotational isomorphism in PGTs in an unambiguous way. New invariants for rotational graphs and displacement graphs called geared chain hamming strings and geared chain loop hamming strings are developed respectively to identify rotational and displacement isomorphism. This paper also presents a procedure to redraw conventional graph representation that not only clarifies the kinematic structure of a PGT but also averts the problem of pseudo isomorphism. Finally a thorough analysis of existing methods is carried out using the proposed technique and the results in the category of six links one degree-of-freedom are established and an Atlas comprises of graph representations in conventional form as well as in new form is presented.

A Model for Mechanism Data Storage

1992 ◽  
Author(s):  
Wan Wang
Keyword(s):  
Data Storage ◽  
Data Model ◽  
Computer Time ◽  
Kinematic Structure ◽  
Topological Graph ◽  
Complete Set ◽  
Isomorphism Identification

Abstract A data model for kinematic structure of mechanisms and its coding principle are proposed, based on the topological graph and contract graph. In the model every basic chain is mapped by a code of 5 decimal digits and a mechanism is mapped by a set of code of basic chains. The model occupies minimal memory, and contains a complete set of useful primary parameters of structure, and significantly reduce computer time for isomorphism identification.

scholarly journals Terrain-Trapped Airflows and Orographic Rainfall along the Coast of Northern California. Part II: Horizontal and Vertical Structures Observed by a Scanning Doppler Radar

2018 ◽  
Vol 146 (8) ◽  
pp. 2381-2402 ◽  
Author(s):  
Raul A. Valenzuela ◽  
David E. Kingsmill
Keyword(s):  
Wind Direction ◽  
Doppler Radar ◽  
Horizontal Gradient ◽  
Kinematic Structure ◽  
Northern California ◽  
Winter Storms ◽  
Air Masses ◽  
Additional Information ◽  
Orographic Rainfall ◽  
Close Proximity

Abstract This study documents the mean properties and variability of kinematic and precipitation structures associated with orographic precipitation along the coast of Northern California in the context of terrain-trapped airflows (TTAs). TTAs are defined as relatively narrow air masses that consistently flow in close proximity and approximately parallel to an orographic barrier. Seven land-falling winter storms are examined with observations from a scanning X-band Doppler radar deployed on the coast at Fort Ross, California. Additional information is provided by a 915-MHz wind-profiling radar, surface meteorology, a GPS receiver, and balloon soundings. The composite kinematic structure during TTA conditions exhibits a significant horizontal gradient of wind direction from the coast to approximately 50 km offshore and a low-level jet (LLJ) that surmounts a weaker airflow offshore corresponding to the TTA, with a zone of enhanced precipitation evident between ~5 and 25 km offshore and oriented nearly parallel to the coastline. Conversely, the composite kinematic structure during NO-TTA conditions exhibits a smaller offshore horizontal gradient of wind direction and precipitation structures are generally enhanced within km of the coastline. Interstorm variability analysis reveals significant variations in kinematic structures during both TTA and NO-TTA conditions, whereas significant variations in precipitation structures are only evident during TTA conditions. The interstorm analysis also illustrates more clearly how LLJ vertical structures evident during NO-TTA conditions exhibit ascent along the coast and over the coastal mountains, which is in contrast to TTA conditions where the ascent occurs offshore and over the TTA.

A Concept for Rapidly-Deployable Cable Robot Search and Rescue Systems

2005 ◽  
Author(s):  
Paul Bosscher ◽  
Robert L. Williams ◽  
Melissa Tummino
Keyword(s):  
Mobile Robots ◽  
Inverse Kinematics ◽  
Search And Rescue ◽  
Kinematic Structure ◽  
Rescue Workers ◽  
Cable Robot ◽  
System Concept ◽  
Moment Resisting ◽  
Calibration Algorithm ◽  
Forward And Inverse Kinematics

This paper introduces a new concept for robotic search and rescue systems. This system uses a rapidly deployable cable robot to augment existing search and rescue mobile robots. This system can greatly increase the range of mobile robots as well as provide overhead views of the disaster site, allowing rescue workers to reach survivors as quickly as possible while minimizing the danger posed to rescue workers. In addition to the system concept, this paper presents a novel kinematic structure for the cable robot, allowing simple translation-only motion (with moment-resisting capability) and easy forward and inverse kinematics for a 3-DOF spatial manipulator. Also, a deployment sequence is described, a rapid calibration algorithm is presented and the workspace of the manipulator is investigated.

scholarly journals Energy Transfer during the Tidal Encounter of Disc Galaxies

1983 ◽  
Vol 100 ◽  
pp. 355-356
Author(s):  
Philip L. Palmer
Keyword(s):  
Energy Transfer ◽  
Energy Loss ◽  
Numerical Simulations ◽  
Merging Galaxies ◽  
Analytic Work ◽  
Instability Modes ◽  
Impulsive Approximation ◽  
Disc Galaxies

Numerical simulations of merging galaxies do not include a disc component due to bar instability modes. Analytic work is based upon the impulsive approximation which leads to energy loss by the perturber. However, for the perturber to become bound we need consider parabolic encounters. Here we present an analytic technique suitable for all types of encounters.

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