Dynamic Analysis of Ocean Internal Waves Using Space Shuttle Data

This paper presents a NASTRAN finite element analysis for evaluation of the effectiveness of viscoelastic damping treatments as passive controls for large flexible space manipulators. The passive damping could be used alone or as an augmentation to active control. Perhaps the best existing example of a practical flexible manipulator is the space shuttle Remote Manipulator System (RMS). The authors use the RMS as an example for this investigation, subjecting it to a detailed dynamic analysis which can be used to evaluate the critical modes for control and to distinguish the modes which are good candidates for active control from those which are well suited for passive control. Modal potential energy analysis (MPE) is used to examine the modal energy distribution in each structural member of the complex flexible chained system. The results indicate that the most dominant contributors to end-point oscillations fall into two categories. These include very low frequency modes due to joint flexibility and higher frequency modes due to bending in the booms. Significant end-point motions result from each category, but the most significant motions are associated with joint flexibility. Finally, a finite element analysis is performed to evaluate the effectiveness of constrained viscoelastic layer damping treatments for passive vibration control. Passive damping augmentation is introduced through the use of a constrained viscoelastic layer damping treatment applied to the surface of the manipulator’s flexible booms. It is shown that even the joint compliance dominated modes can be damped to some degree through appropriate design of the treatment.

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Statistical and dynamical analysis of internal waves on the continental shelf of the Middle Atlantic Bight from space shuttle photographs

Journal of Geophysical Research Atmospheres ◽

10.1029/92jc02955 ◽

1993 ◽

Vol 98 (C5) ◽

pp. 8495-8504 ◽

Cited By ~ 31

Author(s):

Quanan Zheng ◽

Xiao-Hai Yan ◽

Vic Klemas

Keyword(s):

Continental Shelf ◽

Internal Waves ◽

Space Shuttle ◽

Dynamical Analysis ◽

Middle Atlantic Bight ◽

Middle Atlantic

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Dynamic interpretation of space shuttle photographs: Deepwater internal waves in the western equatorial Indian Ocean

Journal of Geophysical Research Atmospheres ◽

10.1029/94jc02921 ◽

1995 ◽

Vol 100 (C2) ◽

pp. 2579 ◽

Cited By ~ 20

Author(s):

Quanan Zheng ◽

Vic Klemas ◽

Xiao-Hai Yan

Keyword(s):

Indian Ocean ◽

Internal Waves ◽

Space Shuttle ◽

Equatorial Indian Ocean ◽

Dynamic Interpretation

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The surface signature of internal waves

Journal of Fluid Mechanics ◽

10.1017/jfm.2012.364 ◽

2012 ◽

Vol 710 ◽

pp. 277-303 ◽

Cited By ~ 13

Author(s):

W. Craig ◽

P. Guyenne ◽

C. Sulem

Keyword(s):

Internal Waves ◽

Space Shuttle ◽

Resonant Interaction ◽

Surface Modes ◽

Characteristic Features ◽

Analysis Models ◽

Internal Soliton ◽

Theoretical Results ◽

Radiative Absorption ◽

Surface Signature

AbstractOceans that are stratified by density into distinct layers support internal waves. An internal soliton gives rise to characteristic features on the surface, a signature of its presence, in the form of a ‘rip’ region, as reported in Osborne & Burch (Science, vol. 208, 1980, pp. 451–460), which results in a change in reflectance as seen in NASA photographs from the space shuttle. In the present paper, we give a new analysis of this signature of an internal soliton, and the ‘mill pond’ effect of an almost completely calm sea after its passage. Our analysis models the resonant interaction of nonlinear internal waves with the surface modes, where the surface signature is generated by a process analogous to radiative absorption. These theoretical results are illustrated with numerical simulations that take oceanic parameters into account.

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The effect of back-melting on the continuity of crystallographic orientation and composition in HgZnTe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133114 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1696-1697

Author(s):

H.J. Zuo ◽

M.W. Price ◽

R.D. Griffin ◽

R.A. Andrews ◽

G.M. Janowski

Keyword(s):

Directional Solidification ◽

Space Shuttle ◽

Solidification Process ◽

Space Experiment ◽

Infrared Detection ◽

Directionally Solidified ◽

Crystallographic Defects ◽

Semiconducting Alloys ◽

Uniform Composition ◽

Growth Experiments

The II-VI semiconducting alloys, such as mercury zinc telluride (MZT), have become the materials of choice for numerous infrared detection applications. However, compositional inhomogeneities and crystallographic imperfections adversly affect the performance of MZT infrared detectors. One source of imperfections in MZT is gravity-induced convection during directional solidification. Crystal growth experiments conducted in space should minimize gravity-induced convection and thereby the density of related crystallographic defects. The limited amount of time available during Space Shuttle experiments and the need for a sample of uniform composition requires the elimination of the initial composition transient which occurs in directionally solidified alloys. One method of eluding this initial transient involves directionally solidifying a portion of the sample and then quenching the remainder prior to the space experiment. During the space experiment, the MZT sample is back-melted to exactly the point at which directional solidification was stopped on earth. The directional solidification process then continues.

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