Validity of the perturbation model for the propagation of MSF structures in 3D

In this study, an algorithm to identify the maneuvers of a satellite is developed by comparing the Keplerian elements acquired from the two-line elements (TLEs) and Keplerian elements propagated from simplified perturbation models. TLEs contain a specific set of orbital elements, whereas the simplified perturbation models are used to propagate the state vectors at a given time. By comparing the corresponding Keplerian elements derived from both methods, a satellite’s maneuver is identified. This article provides an outline of the working methodology and efficacy of the method. The function of this approach is evaluated in two case studies, i.e., TOPEX/Poseidon and Envisat, whose maneuver histories are available. The same method is implemented to identify the station-keeping maneuvers for TDRS-3, whose maneuver history is not available. Results derived from the analysis indicate that maneuvers with a magnitude of even as low as cm/s are detected when the detection parameters are calibrated properly.

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A perturbation model to predict thermal sensitivity of transverse waves on thin quartz plates

Journal of Applied Physics ◽

10.1063/1.371740 ◽

1999 ◽

Vol 86 (12) ◽

pp. 6657-6664 ◽

Cited By ~ 1

Author(s):

J. B. Briot ◽

S. Ballandras ◽

G. Martin

Keyword(s):

Thermal Sensitivity ◽

Transverse Waves ◽

Perturbation Model

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More is Still not Better: Testing the Perturbation Model of Temporal Reference Memory across Different Modalities and Tasks

Quarterly Journal of Experimental Psychology ◽

10.1080/17470210802329201 ◽

2009 ◽

Vol 62 (5) ◽

pp. 909-924 ◽

Cited By ~ 10

Author(s):

Ruth S. Ogden ◽

Luke A. Jones

Keyword(s):

Generalization Gradient ◽

Memory Function ◽

Reference Memory ◽

Visual Cue ◽

Temporal Reference ◽

Perturbation Model ◽

Temporal Generalization

The ability of the perturbation model (Jones & Wearden, 2003) to account for reference memory function in a visual temporal generalization task and auditory and visual reproduction tasks was examined. In all tasks the number of presentations of the standard was manipulated (1, 3, or 5), and its effect on performance was compared. In visual temporal generalization the number of presentations of the standard did not affect the number of times the standard was correctly identified, nor did it affect the overall temporal generalization gradient. In auditory reproduction there was no effect of the number of times the standard was presented on mean reproductions. In visual reproduction mean reproductions were shorter when the standard was only presented once; however, this effect was reduced when a visual cue was provided before the first presentation of the standard. Whilst the results of all experiments are best accounted for by the perturbation model there appears to be some attentional benefit to multiple presentations of the standard in visual reproduction.

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Proton transitions in hydrogen bonds of DNA: A first-order perturbation model

International Journal of Quantum Chemistry ◽

10.1002/qua.560160712 ◽

2009 ◽

Vol 16 (S6) ◽

pp. 171-188

Author(s):

W. Grant Cooper

Keyword(s):

Hydrogen Bonds ◽

Order Perturbation ◽

Perturbation Model ◽

First Order ◽

First Order Perturbation

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Influence of Teeth Damage on Rotordynamic Instability of Impeller Eye Seals in Centrifugal Compressors

Volume 2: Fora ◽

10.1115/fedsm2005-77452 ◽

2005 ◽

Author(s):

Jinxiang Xi ◽

David L. Rhode

Keyword(s):

Labyrinth Seal ◽

Accurate Prediction ◽

Centrifugal Compressors ◽

Perturbation Model ◽

Rotordynamic Coefficients ◽

Leakage Path ◽

Swirl Velocity ◽

Inlet Swirl ◽

Rotordynamic Forces

This paper investigates the influence of labyrinth seal teeth damage due to rotor impacting on the performance and the rotordynamic characteristics of impeller eye seals in centrifugal compressors. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. The inclusion of at least an approximate shroud leakage path chamber is prefered for accurate prediction of seal-inlet swirl velocity and flow-induced rotordynamic forces. Impeller eye seals with teeth damage: (a) suffer significant leakage increases due to the increased seal clearance and (b) produce higher seal-inlet swirl velocity as well as larger rotordynamic forces, which tend to cause the system to become unstable. It was also found that distorted teeth tip geometries have an insignificant influence on both leakage and rotordynamic coefficients. The leakage path influence on seal-inlet swirl velocity W0 was also explored to thoroughly understand the rotordynamic characteristics of the eye seal subject to various degrees of teeth damage.

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