Averaging of the equation of motion of a satellite with respect to its center of mass in degenerate cases: 1. Oscillations in the absolute frame of reference

2008 ◽  
Vol 46 (2) ◽  
pp. 172-180 ◽  
Author(s):  
S. Yu. Sadov
Keyword(s):  
Center Of Mass ◽  
Equation Of Motion ◽  
Frame Of Reference ◽  
The Absolute ◽  
Absolute Frame ◽  
Degenerate Cases

scholarly journals Frames of spatial reference in Kilivila

2001 ◽  
Vol 25 (3) ◽  
pp. 521-555 ◽  
Author(s):  
Gunter Senft
Keyword(s):  
Spatial Orientation ◽  
Reference System ◽  
Spatial Configuration ◽  
Frame Of Reference ◽  
Research Results ◽  
Austronesian Language ◽  
Spatial Reference ◽  
The Absolute ◽  
Absolute Frame ◽  
Intrinsic Frame

Members of the MPI for Psycholinguistics are researching the interrelationship between language, cognition and the conceptualization of space in various languages. Research results show that there are three frames of spatial reference, the absolute, the relative, and the intrinsic frame of reference. This study first presents results of this research in general and then discusses the results for Kilivila. Speakers of this Austronesian language prefer the intrinsic frame of reference for the location of objects with respect to each other in a given spatial configuration. But they prefer an absolute frame of reference system in referring to the spatial orientation of objects in a given spatial configuration. Moreover, the hypothesis is confirmed that languages seem to influence the choice and the kind of conceptual parameters their speakers use to solve non-verbal problems within the domain of space.

Elastic Forces and Coordinate Systems in the Finite Element Formulations

1999 ◽  
Author(s):  
Marcello Berzeri ◽  
Marcello Campanelli ◽  
A. A. Shabana
Keyword(s):  
Finite Element ◽  
Absolute Nodal Coordinate Formulation ◽  
Frame Of Reference ◽  
Coordinate Systems ◽  
Absolute Nodal Coordinate ◽  
Floating Frame Of Reference ◽  
Elastic Forces ◽  
Floating Frame ◽  
The Absolute ◽  
Finite Element Formulations

Abstract The equivalence of the elastic forces of finite element formulations used in flexible multibody dynamics is the focus of this investigation. Two conceptually different finite element formulations that lead to exact modeling of the rigid body dynamics will be used. These are the floating frame of reference formulation and the absolute nodal coordinate formulation. It is demonstrated in this study that different element coordinate systems, which are used for the convenience of describing the element deformations in the absolute nodal coordinate formulation, lead to similar results as the element size is reduced. The equivalence of the elastic forces in the absolute nodal coordinate and the floating frame of reference formulations is shown. The result of this analysis clearly demonstrates that the instability observed in high speed rotor analytical models due to the neglect of the geometric centrifugal stiffening is not a problem inherent to a particular finite element formulation but only depends on the beam model that is used. Fourier analysis of the solutions obtained in this investigation also sheds new light on the fundamental problem of the choice of the deformable body coordinate system in the floating frame of reference formulation. A new method is presented and used to obtain a simple expression for the elastic forces in the absolute nodal coordinate formulation. This method, which employs a nonlinear elastic strain-displacement relationship, does not result in an unstable solution when the angular velocity is increased.

Framing the Opioid Crisis: Do Racial Frames Shape Beliefs of Whites Losing Ground?

2019 ◽  
Vol 45 (2) ◽  
pp. 241-276
Author(s):  
Sarah E. Gollust ◽  
Joanne M. Miller
Keyword(s):  
Public Health ◽  
News Article ◽  
Future Research ◽  
Control Group ◽  
Political Consequences ◽  
Treatment Groups ◽  
The Public ◽  
Opioid Crisis ◽  
The Absolute ◽  
Absolute Frame

Abstract Context: Although research has begun to examine perceptions of being on the losing side of politics, it has been confined to electoral politics. The context of health disparities, and particularly the opioid crisis, offers a case to explore whether frames that emphasize racial disadvantage activate loser perceptions and the political consequences of such beliefs. Methods: White survey participants (N = 1,549) were randomized into three groups: a control which saw no news article, or one of two treatment groups which saw a news article about the opioid crisis framed to emphasize either the absolute rates of opioid mortality among whites or the comparative rates of opioid mortality among whites compared to blacks. Findings: Among control group participants, perceiving oneself a political loser was unrelated to attitudes about addressing opioids, whereas those who perceived whites to be on the losing side of public health had a less empathetic response to the opioid crisis. The comparative frame led to greater beliefs that whites are on the losing side of public health, whereas the absolute frame led to more empathetic policy opinions. Conclusions: Perceptions that one's racial group has lost ground in the public health context could have political consequences that future research should explore.

Einstein

Lightspeed ◽  
2019 ◽  
pp. 144-158
Author(s):  
John C. H. Spence
Keyword(s):  
Frame Of Reference ◽  
Relativity Theory ◽  
Theoretical Physics ◽  
Simple Explanation ◽  
Flowing Water ◽  
Theory Of Relativity ◽  
Speed Of Light ◽  
Nuclear Explosions ◽  
Absolute Frame ◽  
The Universe

The confused state of theoretical physics in 1900 and the great unresolved issues are summarized, one of which led to the birth of quantum mechanics, and the other to relativity. How it seemed impossible to reconcile Bradley’s measurements of the speed of light with Fresnel’s Aether drag hypothesis, which was well supported by Fizeau’s measurements in Paris of the speed of light in a moving medium (flowing water). Maxwell’s equations predicted a constant speed of light, suggesting an absolute frame of reference in the universe, but did not “transform” in the same way as Newton’s equations from one moving observer to another. How Einstein made sense of all these rival theories and experimental results with his unifying theory of relativity, based on two assumptions. His life and work is discussed, and a simple explanation given of his relativity theory. How the failure of this search for an absolute frame of reference in our universe led him inexorably to perhaps the most famous equation in physics E = mc2, giving the energy release from nuclear explosions and the stars.

Gravity Compensation for Manipulator Control by Neural Networks with Partially Preorganized Structure

1990 ◽  
Vol 2 (4) ◽  
pp. 282-287
Author(s):  
Toshio Tsuji ◽  
◽  
Masataka Nishida ◽  
Toshiaki Takahashi ◽  
Koji Ito
Keyword(s):  
Neural Networks ◽  
Adaptive Learning ◽  
Center Of Mass ◽  
Back Propagation ◽  
Equation Of Motion ◽  
Point Load ◽  
Gravity Compensation ◽  
Error Back Propagation ◽  
Industrial Manipulators ◽  
Parameter Values

The gravity torque of a manipulator can be compensated if the equation of motion can be correctly introduced, but in general industrial manipulators, there are many cases when the parameter values such as the position of center of mass are not clear, and these values largely change by the exchange of hand portions and the grasping of substances. Furthermore, in addition to unclear parameters, there are factors which occur by structural gravity compensation (spring and counter-balance) and which in many cases are difficult to express with the equation of motion. In this paper, compensation of the gravity torque of the manipulator is studied by, the use of neural networks. For this purpose, a model which makes the structure known to be contained in mapping as a unit with preorganized characteristics prepared in parallel with hidden unit of error back propagation-type neural network is proposed, by which the characteristics of the link system which is the object for learning can be imbedded into the network as preorganized knowledge beforehand. Finally, the results of experiments done with the use of industrial manipulators are given, and it is made clear that the compensation of gravity torque of manipulator and adaptive learning for end-point load are possible by the use of this model.

Simulation-Based Analysis of the Micropropulsion With Rotating Corkscrew Motion of Flagella

2009 ◽  
Author(s):  
Mustafa Koz ◽  
Serhat Yesilyurt
Keyword(s):  
Cylindrical Channel ◽  
Stokes Equations ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Equation Of Motion ◽  
Navier Stokes ◽  
Mesh Deformation ◽  
Navier Stokes Equations ◽  
Simulation Based ◽  
Commercial Package

Microorganisms such as ecoli bacterium can propel themselves by means of a corkscrew motion in flow regimes where the Reynolds number is much smaller than one and inertial propulsion methods are ineffective. Micropropulsion with the rotating corkscrew motion of flagella can prove useful as a navigation mechanism for microswimming robots in medical applications. In this work, we present the motion of a microswimmer that consists of an ellipsoid of length two-microns and diameter one micron with a flagellum of length two microns and diameter of 40 nanometers. The microswimmer resembles to a typical ecoli bacterium. We present the effect of parameters such as angular velocity and amplitude of the corkscrew motion. In simulations, time-dependent three-dimensional Navier-Stokes equations are solved in deforming mesh using a commercial package COMSOL. Mesh deformation is specified based on the displacement and rotation of the microswimmer that springs from the net force and torque around the center of mass due to the rotation of the corkscrew-like flagellum. The net linear and angular accelerations of the microswimmer are calculated using ordinary-differential equations that represent the equation of motion, and coupled with the Navier-Stokes equations and the mesh deformation. For simplicity, microswimmer is placed in a cylindrical channel of diameter 20 microns and length 60 microns.

Sign in / Sign up

Export Citation Format

Share Document