The dynamic performance of the Weissenberg rheogoniometer III. Large amplitude oscillatory shearing ? harmonic analysis

1984 ◽  
Vol 23 (1) ◽  
pp. 90-97 ◽  
Author(s):  
W. C. MacSporran ◽  
R. P. Spiers
Keyword(s):  
Harmonic Analysis ◽  
Large Amplitude ◽  
Dynamic Performance ◽  
Weissenberg Rheogoniometer ◽  
Oscillatory Shearing

Effect of Mechanical Preloads on the Dynamic Performance of Gas Foil Bearings

2008 ◽  
Author(s):  
Tae Ho Kim ◽  
Luis San Andre´s
Keyword(s):  
Large Amplitude ◽  
High Speed ◽  
Low Cost ◽  
Dynamic Performance ◽  
Cycle Performance ◽  
High Power Density ◽  
Shaft Speed ◽  
Foil Bearings ◽  
Bearing Force ◽  
Good Agreement

Gas foil bearings (GFBs) enable efficient, reliable and maintenance free operation of high-power-density microturbomachinery (< 200 kW). High speed rotors supported on bump-type GFBs, however, are prone to show large-amplitude subsynchronous motions albeit reaching limit cycle performance. Presently, commercial GFBs are simply modified to introduce a mechanical preload that induces a hydrodynamic wedge to generate more load support and direct stiffnesses. Three metal shims inserted under the bump strip layers and in contact with the bearing housing create a multiple lobe clearance profile at a very low cost. Shaft speed coastdown measurements reveal the rotordynamic performance of a rotor supported on original GBFs and (modified) shimmed GFBs. The later GFBs determine a raise in the rotor-bearing system natural frequency, as expected, and also act to delay the onset speed of large-amplitude subsynchronous motions. Predictions of imbalance response implementing linearized bearing force coefficients are in good agreement with measured amplitudes of synchronous response for both GFB configurations, original and modified.

Probing Shear-Banding Transitions of Entangled Liquids Using Large Amplitude Oscillatory Shearing (LAOS) Deformations

2008 ◽  
Author(s):  
Lin Zhou ◽  
Randy H. Ewoldt ◽  
L. Pamela Cook ◽  
Gareth H. McKinley ◽  
Albert Co ◽  
...  
Keyword(s):  
Large Amplitude ◽  
Shear Banding ◽  
Oscillatory Shearing

An Assessment of Large Amplitude Harmonic Analysis in Corrosion Studies

1986 ◽  
Vol 8 ◽  
pp. 417-428 ◽  
Author(s):  
C. Gabrielli ◽  
Michel Keddam ◽  
Hisasi Takenouti
Keyword(s):  
Harmonic Analysis ◽  
Large Amplitude ◽  
Corrosion Studies

The dynamic performance of the Weissenberg Rheogoniometer

1982 ◽  
Vol 21 (2) ◽  
pp. 184-192 ◽  
Author(s):  
W. C. MacSporran ◽  
R. P. Spiers
Keyword(s):  
Dynamic Performance ◽  
Weissenberg Rheogoniometer

The dynamic performance of the Weissenberg Rheogoniometer

1982 ◽  
Vol 21 (2) ◽  
pp. 193-200 ◽  
Author(s):  
W. C. MacSporran ◽  
R. P. Spiers
Keyword(s):  
Dynamic Performance ◽  
Weissenberg Rheogoniometer

On nearly-commensurable periods in the restricted problem of three bodies, with calculations of the long-period variations in the interior 2:1 case

1966 ◽  
Vol 25 ◽  
pp. 197-222 ◽  
Author(s):  
P. J. Message
Keyword(s):  
Periodic Solution ◽  
Periodic Solutions ◽  
Large Amplitude ◽  
Restricted Problem ◽  
Small Amplitude ◽  
Minor Planets ◽  
Long Period ◽  
Numerical Integrations ◽  
Period Variations ◽  
The Mean

An analytical discussion of that case of motion in the restricted problem, in which the mean motions of the infinitesimal, and smaller-massed, bodies about the larger one are nearly in the ratio of two small integers displays the existence of a series of periodic solutions which, for commensurabilities of the typep+ 1:p, includes solutions of Poincaré'sdeuxième sortewhen the commensurability is very close, and of thepremière sortewhen it is less close. A linear treatment of the long-period variations of the elements, valid for motions in which the elements remain close to a particular periodic solution of this type, shows the continuity of near-commensurable motion with other motion, and some of the properties of long-period librations of small amplitude.To extend the investigation to other types of motion near commensurability, numerical integrations of the equations for the long-period variations of the elements were carried out for the 2:1 interior case (of which the planet 108 “Hecuba” is an example) to survey those motions in which the eccentricity takes values less than 0·1. An investigation of the effect of the large amplitude perturbations near commensurability on a distribution of minor planets, which is originally uniform over mean motion, shows a “draining off” effect from the vicinity of exact commensurability of a magnitude large enough to account for the observed gap in the distribution at the 2:1 commensurability.

Information and estimation in image processing

1987 ◽  
Vol 45 ◽  
pp. 14-17
Author(s):  
B. Roy Frieden
Keyword(s):  
Image Processing ◽  
Optical System ◽  
Large Amplitude ◽  
Communication Theory ◽  
Image Data ◽  
Direct Approach ◽  
Ill Posed

Despite the skill and determination of electro-optical system designers, the images acquired using their best designs often suffer from blur and noise. The aim of an “image enhancer” such as myself is to improve these poor images, usually by digital means, such that they better resemble the true, “optical object,” input to the system. This problem is notoriously “ill-posed,” i.e. any direct approach at inversion of the image data suffers strongly from the presence of even a small amount of noise in the data. In fact, the fluctuations engendered in neighboring output values tend to be strongly negative-correlated, so that the output spatially oscillates up and down, with large amplitude, about the true object. What can be done about this situation? As we shall see, various concepts taken from statistical communication theory have proven to be of real use in attacking this problem. We offer below a brief summary of these concepts.

Representation Theory and Harmonic Analysis of Wreath Products of Finite Groups

2009 ◽  
Author(s):  
Tullio Ceccherini-Silberstein ◽  
Fabio Scarabotti ◽  
Filippo Tolli
Keyword(s):  
Representation Theory ◽  
Harmonic Analysis ◽  
Finite Groups ◽  
Wreath Products
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