Response of Mnbi-Bi Eutectic to Freezing Rate Changes

1981 ◽  
Vol 9 ◽  
Author(s):  
M. Nair ◽  
T-W. Fu ◽  
W. R. Wilcox ◽  
K. Doddi ◽  
P. S. Ravishankar ◽  
...  
Keyword(s):  
Sudden Change ◽  
Axial Direction ◽  
Freezing Rate ◽  
Theoretical Treatment ◽  
Translation Rate ◽  
Theoretical Predictions ◽  
Rate Oscillations ◽  
Silica Ampoule ◽  
Resistance To Heat ◽  
Ampoule Wall

ABSTRACTPreviously we reported on a theoretical treatment of the influence on freezing rate of sudden changes in translation rate in the Bridgman-Stockbarger technique [11]. This has now been extended to consideration of a linear ramped translation rate and an oscillatory freezing rate. Oscillations above a few hertz are found to be highly damped in smalldiameter apparatus.An experimental test was made of the theoretical predictions for a sudden change of translation rate. MnBi-Bi eutectic was solidified with current induced interface demarcation.The experimental results correspond reasonably well with theory if the silica ampoule wall is assumed either (1) to contribute only a resistance to heat exchange of sample with the furnace wall, or (2) to transmit heat effectively in the axial direction by radiation.In an attempt to explain the fact that a finer microstructure is obtained in space, MnBi-Bi microstructure is being determined when the freezing rate is rapidly increased or decreased. Preliminary results indicate that fiber branching does not occur as readily as does fiber termination.

THE K–LL AUGER SPECTRUM OF 94Pu239

1959 ◽  
Vol 37 (2) ◽  
pp. 174-182 ◽  
Author(s):  
G. T. Ewan ◽  
J. S. Geiger ◽  
R. L. Graham ◽  
D. R. MacKenzie
Keyword(s):  
High Resolution ◽  
Satisfactory Agreement ◽  
Proportional Counter ◽  
Auger Spectrum ◽  
Theoretical Treatment ◽  
J Coupling ◽  
Theoretical Predictions

The K–LL Auger spectrum of 94Pu239 has been examined using a high resolution π√2 β-ray spectrometer with a proportional counter detector. Seven lines have been observed in the Auger spectrum with the following energies and relative intensities.[Formula: see text]The presence of seven lines in this K–LL Auger spectrum is in disagreement with theoretical predictions based on pure j–j coupling and supports, rather, the recent theoretical treatment of Asaad and Burhop. The energies of the observed lines are in satisfactory agreement with their theoretical predictions but discrepancies exist in the relative intensities.

Experimental Study of Propeller-Induced Vibratory Pressures on Simple Surfaces and Correlation With Theoretical Predictions

1964 ◽  
Vol 8 (05) ◽  
pp. 15-28
Author(s):  
J. P. Breslin ◽  
T. Kowalski
Keyword(s):  
Free Space ◽  
Three Dimensional ◽  
Theoretical Treatment ◽  
Plate Boundaries ◽  
Practical Application ◽  
Finite Area ◽  
Experimental Procedure ◽  
Theoretical Predictions ◽  
Pressure Changes ◽  
Good Agreement

Vibratory pressures exerted on cylindrical and flat-plate boundaries due to a model propeller were measured at three advance coefficients. A number of "free-space" measurements also were made. All measurements were made by driving a propeller past fixed pressure gages. This method yielded curves of pressure changes which are entirely free from background noise. The magnitudes of the free-space pressures were found to be larger than one half the corresponding magnitudes measured by gages mounted flush in a large plate at equal clearances from the propeller. By postulating that the finite area of the gage diaphragm produces a partial image of the propeller (and hence a larger pressure than that in free space) an experimental procedure was devised for correcting for this finite-area effect yielding results in good agreement with theory. A theoretical treatment of this effect of finite gage size is given in Appendix 2. The decay of maximum amplitudes of vibrating pressures is shown by means of three-dimensional plots. The pressures were found to become vanishingly small within approximately one propeller diameter fore and aft of the center of the propeller. The comparison with theoretically calculated pressures and forces gives very close agreement for free-space pressures and reasonable agreement for forces on a cylindrical surface. The agreement of both pressures and forces with theory is excellent for operation near the design advance ratio. A strong plea is made for further experiments with ship models in an effort to develop design criteria for practical application.

Deviation of freezing rate from translation rate in the Bridgman-Stockbarger technique

1982 ◽  
Vol 58 (1) ◽  
pp. 219-228 ◽  
Author(s):  
Peter C. Sukanek
Keyword(s):  
Freezing Rate ◽  
Translation Rate

Experimental Techniques for Bearing Impedance Measurement

1991 ◽  
Vol 113 (3) ◽  
pp. 335-342 ◽  
Author(s):  
M. J. Goodwin
Keyword(s):  
Experimental Measurement ◽  
Computer Software ◽  
Impedance Measurement ◽  
Experimental Techniques ◽  
Design Stage ◽  
Theoretical Treatment ◽  
Yield Coefficient ◽  
Experimental Procedure ◽  
Advantages And Disadvantages ◽  
Theoretical Predictions

The dynamic characteristics of rotating machinery are almost always influenced by the impedances of the machine bearings (including the bearing supports) and it is particularly important to know of their likely values at the design stage when predicting machine critical speeds, unbalance response, and stability. In many instances the vital data may be obtained from theory which must be confirmed by experimental measurement beforehand, or alternatively the data may be obtained directly from experimental measurement when the appropriate bearing has already been manufactured. The experimental techniques available for use in the measurement of bearing impedances are varied, both in their experimental procedure and in the theoretical treatment of the data that is gathered. The aim of this paper is to provide a concise account of these techniques, and to discuss the potential advantages and disadvantages of each approach. In this document, the procedures described are classified in terms of the type of experimental measuring equipment required. These vary from the simplest of test rigs, which provide only a static load in one direction and where impedances can be evaluated by hand calculation, to sophisticated apparatus capable of providing static and dynamic loads in several directions and which require computer software to extract the bearing impedances from the measured data. The type of experimental procedure selected by the rotor dynamicist will depend upon the experimental facilities available, on the time available to carry out the testing, and on the required reliability of results. Each of these considerations is discussed for each procedure described. It is concluded that measurements made using multifrequency test signals provide more reliable data, although all measurement methods yield coefficient values which agree with theoretical predictions to within about 20 percent in general, and all methods have a significant scatter of results associated with their use.

Large Elastic Deformations of Some Cord-Reinforcedrubber Shells

1970 ◽  
Vol 43 (2) ◽  
pp. 282-303 ◽  
Author(s):  
J. M. Charrier
Keyword(s):  
Composite Material ◽  
Large Deformations ◽  
Physical Characteristics ◽  
Simple Extension ◽  
Theoretical Treatment ◽  
Two Dimensional ◽  
Elastic Deformations ◽  
Theoretical Predictions

Abstract A simple theoretical treatment of certain large elastic deformations of a symmetrical network of cords embedded in rubber is explained. The calculations are based on the main assumptions of thin, inextensible and incompressible cords and a rubber behaving like a Neo-Hookean solid. This model, although simple, respects the physical characteristics of certain cord reinforced components which would be designed for large deformations. Calculations for the simple extension of the composite material, the two-dimensional extension and its application to the inflation of tubes, are compared to experiments with reasonable success. Theoretical predictions are made for related problems of the behavior of tubes in contact with plates.

scholarly journals Influence of freezing rate oscillations and convection on eutectic microstructure

2001 ◽  
Vol 48 (2-3) ◽  
pp. 101-108 ◽  
Author(s):  
Liya L. Regel ◽  
William R. Wilcox ◽  
Dimitri Popov ◽  
Fengcui Li
Keyword(s):  
Freezing Rate ◽  
Eutectic Microstructure ◽  
Rate Oscillations

scholarly journals Looking Inside Micro- and Nano-Mechanical Pillar Resonators: A Picosecond Ultrasonics Approach

Proceedings ◽  
2020 ◽  
Vol 56 (1) ◽  
pp. 31
Author(s):  
Paul Stritt ◽  
Juliane Doster ◽  
Thomas Dekorsy ◽  
Vitalyi Gusev ◽  
Eva Weig ◽  
...  
Keyword(s):  
Gallium Arsenide ◽  
Excellent Agreement ◽  
Axial Direction ◽  
Micromechanical Resonators ◽  
Theoretical Predictions ◽  
Picosecond Ultrasonics

Pillar-shaped Gallium arsenide (GaAs) micromechanical resonators are fabricated, and the feasibility to measure the inside of the pillars in the axial direction with laser-induced GHz ultrasound based on picosecond ultrasonics is tested. Measurements on the pillars with head sizes in the µm range show excellent agreement with theoretical predictions.

Elastic-plastic strain distributions in short-link chain under load

1968 ◽  
Vol 3 (1) ◽  
pp. 11-16 ◽  
Author(s):  
I Hawkes ◽  
J H Foley
Keyword(s):  
Elastic Limit ◽  
Point Contact ◽  
Tensile Tests ◽  
Theoretical Treatment ◽  
Maximum Strain ◽  
Theoretical Predictions ◽  
Static Tensile ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Short Link

The strain distribution in short-link chain under load has been examined by a photoelastic-coating technique. It has been shown that at loads up to and just beyond the elastic limit the position of maximum strain occurs at a junction of an intrados and a straight side of the link. Beyond the elastic limit, however, changes in link geometry cause the position of maximum strain to move to the link crown. These results confirm observations of the positions of the fractures in fatigue and static tensile tests to failure but the stress concentration factors calculated from the results disagree with theoretical predictions. This anomaly is explained by assuming that the area of contact between adjacent links effects a spreading of the load, whereas the theoretical treatment assumes point contact between adjacent links.

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