Rotating coordinates as tools for calculating circular geodesics and gyroscopic precession

1990 ◽  
Vol 22 (9) ◽  
pp. 1067-1081 ◽  
Author(s):  
W. Rindler ◽  
V. Perlick
Keyword(s):  
Gyroscopic Precession ◽  
Rotating Coordinates

Stability of Milling Operations With Asymmetric Cutter Dynamics in Rotating Coordinates

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Alptunc Comak ◽  
Orkun Ozsahin ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Machine Tools ◽  
High Speed ◽  
End Mill ◽  
Spindle Shaft ◽  
Milling Operations ◽  
Stability Model ◽  
Principal Directions ◽  
The Stability ◽  
Rotating Coordinates

High-speed machine tools have parts with both stationary and rotating dynamics. While spindle housing, column, and table have stationary dynamics, rotating parts may have both symmetric (i.e., spindle shaft and tool holder) and asymmetric dynamics (i.e., two-fluted end mill) due to uneven geometry in two principal directions. This paper presents a stability model of dynamic milling operations with combined stationary and rotating dynamics. The stationary modes are superposed to two orthogonal directions in rotating frame by considering the time- and speed-dependent, periodic dynamic milling system. The stability of the system is solved in both frequency and semidiscrete time domain. It is shown that the stability pockets differ significantly when the rotating dynamics of the asymmetric tools are considered. The proposed stability model has been experimentally validated in high-speed milling of an aluminum alloy with a two-fluted, asymmetric helical end mill.

scholarly journals Penalty Function Finite Element Analysis of Steady Viscous Incompressible Flow in Rotating Coordinates

1984 ◽  
Author(s):  
M. C. Rosen ◽  
P. E. Allaire ◽  
J. G. Rice
Keyword(s):  
Finite Element ◽  
Turbulent Flows ◽  
Penalty Function ◽  
Experimental Measurements ◽  
Element Analysis ◽  
Viscous Incompressible Flow ◽  
Incompressible Viscous Flow ◽  
Rotating Coordinates ◽  
Rotating Channel ◽  
Laminar And Turbulent Flows

Finite element methods for incompressible viscous flow in turbomachines have not been presented in the literature previously. This paper develops a penalty function primitive variable method including Coriolis and centrifugal force terms for steady flow in a rotating coordinate system. Simplex elements are used with the result of solution times comparable to equivalent finite different solutions. Example cases considered are Couette flow, Poiseuille flow, flow over a step and flow in a rotating channel. Both laminar and turbulent flows are discussed. The accuracy of computed solutions compares well with theoretical solutions and experimental measurements.

scholarly journals ON TURNING OVER GYROSCOPIC PRECESSION

2001 ◽  
Author(s):  
J. L. HERNÁNDEZ-PASTORA ◽  
J. MARTÍN ◽  
E. RUIZ
Keyword(s):  
Gyroscopic Precession

Simulation for Dynamics of Leaf Based on a 1/ƒ Noise Method

2014 ◽  
Vol 488-489 ◽  
pp. 858-861
Author(s):  
Bei Bei Li ◽  
Zhi Hong Zhao
Keyword(s):  
Experimental Results ◽  
Sample Points ◽  
Rotating Coordinates ◽  
Leaf Dynamics

This study addresses a method for simulating a leaf dynamics on the basis of a 1/fnoise method. Firstly, a 1/fnoise with linear varying amplitude is used to simulate a selected leaf boundary detected and recognized. Secondly, a sample points operation is employed within its boundary after a corresponding reprocess is adopted, and then the corresponding body within its boundary is capable of being simulated. Finally, simulation for the leaf dynamics may be completed by using a dynamically rotating coordinates method. The experimental results show that this method has a better capability and can be used to realize simulation for the leaves with regular shapes to some extent.

Grid synchronization and symmetrical components extraction with PLL algorithm for grid connected power electronic converters - a review

2011 ◽  
Vol 59 (4) ◽  
pp. 485-497 ◽  
Author(s):  
M. Bobrowska-Rafal ◽  
K. Rafal ◽  
M. Jasinski ◽  
M. Kazmierkowski
Keyword(s):  
Extraction Methods ◽  
Power Electronic ◽  
Practical Application ◽  
Power Electronic Converters ◽  
Symmetrical Components ◽  
Grid Synchronization ◽  
Synchronous Reference Frame ◽  
Symmetrical Component ◽  
Rotating Coordinates ◽  
Virtual Flux

Grid synchronization and symmetrical components extraction with PLL algorithm for grid connected power electronic converters - a reviewIn this paper, a review of Phase Locked Loop (PLL) algorithms and symmetrical component extraction methods intended for grid-connected power electronic converters are presented. Proposed classification is based on voltage representation in three coordinates: natural (abc), stationary (αβ) and rotating coordinates (dq). The three selected algorithms are described in details: Dual Second Order Generalized Integrator (DSOGI-PLL), Dual Virtual Flux - both in stationary coordinates. The third one, in rotating dq coordinates, is Dual Synchronous Reference Frame PLL (DSRF-PLL). A comparison of PLL algorithms is presented. Also, selected experimental results are given to verify practical application of discussed algorithms.

1007 Posture control for two-legged robot with passive wheels using gyroscopic precession

2013 ◽  
Vol 2013.51 (0) ◽  
pp. _1007-1_-_1007-2_
Author(s):  
Takahiro MANPUKU ◽  
Yoshio INOUE ◽  
Kyoko SHIBATA
Keyword(s):  
Posture Control ◽  
Legged Robot ◽  
Gyroscopic Precession
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