General effects of currents and sound‐speed variations on short‐range acoustic transmission in cyclonic eddies

1980 ◽  
Vol 67 (1) ◽  
pp. 121-134 ◽  
Author(s):  
R. F. Henrick ◽  
M. J. Jacobson ◽  
W. L. Siegmann
Keyword(s):  
Sound Speed ◽  
Short Range ◽  
Acoustic Transmission

Influence of mean sound speed on acoustic transmission through an internal wave

1976 ◽  
Vol 59 (3) ◽  
pp. 536-544
Author(s):  
G. A. Lieberman ◽  
M. J. Jacobson ◽  
W. L. Siegmann
Keyword(s):  
Internal Wave ◽  
Sound Speed ◽  
Acoustic Transmission

scholarly journals Sensitivity of short‐range SRBR transmissions to sound‐speed profile selection

1981 ◽  
Vol 69 (S1) ◽  
pp. S34-S34
Author(s):  
P. Bilazarian ◽  
W. L. Siegmann ◽  
M. J. Jacobson
Keyword(s):  
Sound Speed ◽  
Short Range ◽  
Speed Profile ◽  
Sound Speed Profile

Effect of a class of random currents on acoustic transmission in an ocean with linear sound speed

1980 ◽  
Vol 67 (6) ◽  
pp. 1997-2010 ◽  
Author(s):  
B. K. Newhall ◽  
M. J. Jacobson ◽  
W. L. Siegmann
Keyword(s):  
Sound Speed ◽  
Acoustic Transmission

Acoustic transmission of the chick-a-dee call of the Black-capped Chickadee (Poecile atricapillus): forest structure and note function

2010 ◽  
Vol 88 (8) ◽  
pp. 788-794 ◽  
Author(s):  
D. S. Proppe ◽  
L. L. Bloomfield ◽  
C. B. Sturdy
Keyword(s):  
Short Range ◽  
Coniferous Forest ◽  
Acoustic Transmission ◽  
Forest Types ◽  
Poecile Atricapillus ◽  
Acoustic Adaptation ◽  
Vocal Signals ◽  
Differential Transmission ◽  
Adaptation Hypothesis ◽  
Acoustic Adaptation Hypothesis

The acoustic adaptation hypothesis predicts that bird vocalizations will be structured to optimize their transmission through native vegetation. In cases where communication with distant individuals is needed, optimal transmission implies maximal propagation. In other cases, vocal signals are intended for nearby conspecifics and optimal transmission may be only a few metres. The “chick-a-dee” call of the Black-capped Chickadee ( Poecile atricapillus (L., 1766)) is a complex call used in both long- and short-range communication. Here we test whether this call transmits optimally in the locally preferred forests composed of a mix of deciduous and coniferous vegetation, or in either pure deciduous or coniferous forest stands. In addition, we examine whether notes that putatively function in short-range communication transmit shorter distances than those used in long-range communication. We found differential transmission rates for the highest and lowest frequencies in the chick-a-dee call in different forest types, and an overall improvement in call transmission in mixed forests. Note-type transmission correlated with putative note function with one notable exception. In summary, our results suggest that the chick-a-dee call conforms to the acoustic adaptation hypothesis, and that the forms of its note types are in line with their function.

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

Ordering in Ni4Mo by TEM and APFIM

1987 ◽  
Vol 45 ◽  
pp. 214-215
Author(s):  
E.A. Kenik ◽  
T.A. Zagula ◽  
M.K. Miller ◽  
J. Bentley
Keyword(s):  
Electron Irradiation ◽  
Low Temperatures ◽  
Short Range ◽  
Atom Probe ◽  
Range Order ◽  
Considerable Time ◽  
Probe Field ◽  
Disordered Phase ◽  
Transmission Electron ◽  
Diffraction Patterns

The state of long-range order (LRO) and short-range order (SRO) in Ni4Mo has been a topic of interest for a considerable time (see Brooks et al.). The SRO is often referred to as 1½0 order from the apparent position of the diffuse maxima in diffraction patterns, which differs from the positions of the LRO (D1a) structure. Various studies have shown that a fully disordered state cannot be retained by quenching, as the atomic arrangements responsible for the 1½0 maxima are present at temperatures above the critical ordering temperature for LRO. Over 20 studies have attempted to identify the atomic arrangements associated with this state of order. A variety of models have been proposed, but no consensus has been reached. It has also been shown that 1 MeV electron irradiation at low temperatures (∼100 K) can produce the disordered phase in Ni4Mo. Transmission electron microscopy (TEM), atom probe field ion microscopy (APFIM), and electron irradiation disordering have been applied in the current study to further the understanding of the ordering processes in Ni4Mo.

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