Study of vibrations in visco-poroelastic cylinder over a initially stressed heterogeneous layer

Floated Lamella Films of Styrenic Block Copolymers: Local Shearing Deformations and Heterogeneous Layer at the Substrate

Macromolecules ◽

10.1021/ma4020802 ◽

2013 ◽

Vol 47 (1) ◽

pp. 316-323 ◽

Cited By ~ 2

Author(s):

Eva Max ◽

Markus Hund ◽

Igor I. Potemkin ◽

Larisa Tsarkova

Keyword(s):

Block Copolymers ◽

Local Shearing ◽

Heterogeneous Layer

Download Full-text

The E Perpendicular Polarization Response of a Two-Dimensional Heterogeneous Layer Modeled by Two Thin Sheets in a Horizontally Stratified Half-Space

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.1987.289854 ◽

1987 ◽

Vol GE-25 (4) ◽

pp. 432-440 ◽

Cited By ~ 3

Author(s):

R. Robertson

Keyword(s):

Half Space ◽

Thin Sheets ◽

Two Dimensional ◽

Polarization Response ◽

Heterogeneous Layer ◽

Perpendicular Polarization

Download Full-text

Disturbances in semi-infinite heterogeneous media generated by torsional sources. I

Bulletin of the Seismological Society of America ◽

10.1785/bssa0620020541 ◽

1972 ◽

Vol 62 (2) ◽

pp. 541-550

Author(s):

R. S. Sidhu

Keyword(s):

Heterogeneous Media ◽

Formal Solution ◽

Homogeneous Medium ◽

Finite Depth ◽

Free Boundaries ◽

Axially Symmetric ◽

Sh Waves ◽

Reflected Waves ◽

Buried Point ◽

Heterogeneous Layer

abstract This paper studies the generation of axially symmetric transient SH waves in semi-infinite heterogeneous media in which μ and ρ vary with depth. The sources generating these waves are taken in the form of time-dependent torsional-body forces of finite dimensions. The solution is obtained using Hankel and Laplace transforms and Green's function. The disturbance from a buried point source of impulsive type is discussed in two cases, (a) μ = μo(1 + ɛz)2, ρ = ρo (1 + ɛz)2, (b) μ = μoe2az, ρ = ρoe2az. It is shown that, in contrast to the results for a homogeneous medium, in case (i), the wave reflected by the free surface generates secondary disturbances which trail behind the wave front and die out as t increases; the incident wave in this medium generates no such disturbance. In case (ii), however, both the incident as well as the reflected waves generate secondary disturbances. Formal solution for the disturbance in a heterogeneous layer of finite depth with stress-free boundaries is discussed in Appendix II.

Download Full-text

The oxidation of iron around 200 °C

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1953.0028 ◽

1953 ◽

Vol 216 (1126) ◽

pp. 375-397 ◽

Cited By ~ 28

Keyword(s):

Oxygen Uptake ◽

Metal Ion ◽

Absolute Temperature ◽

Ion Diffusion ◽

Surface And Interface ◽

Air Interface ◽

Original Metal ◽

Logarithmic Relationship ◽

Boundary Reaction ◽

Heterogeneous Layer

Phenomena associated with a critical temperature at ca . 200° C in the oxidation of mild steel sheet in air (for example, a change of slope in the curve relating reciprocal of absolute temperature with logarithm of oxygen uptake in constant time) have been investigated by gravimetric, microchemical and electron-diffraction methods. The evidence is interpreted on the basis of predominant metal-ion diffusion above and predominant oxygen-ion diffusion below 200° C, in the oxide film. In the film an outer layer of rhombohedral α -Fe 2 O 3 , overlies a layer of cubic oxide which, initially nearer γ -Fe 2 O 3 , tends towards Fe 3 O 4 —rapidly and completely above 200° C, slowly and incompletely below 200° C. Above 200° C the rate of oxidation is controlled by the diffusion of ions across the film (Wagner mechanism), the parabolic law is followed, and oxygen uptake derived from the weight increase of the specimen is coincident with the oxygen content of the film on removal from the substrate. The film, being produced outside the original metal/air interface, is relatively insensitive to the mode of preparation of the surface, and interface colours readily develop. Below 200° C, oxidation again involves ion diffusion across the film, but the rate is controlled by a boundary reaction with a consequent logarithmic relationship with time. Since oxidation now proceeds at an oxide-metal interface the optical homogeneity of the oxidized layer is very sensitive to the initial condition of the surface. Abraded surfaces carry initially a heterogeneous layer (abrasion-produced oxide in a matrix of iron) in which oxidation can proceed without contributing to the overlying (strippable) film on which the development of interference colours depends. Thickening of the film and progression of colours may be long delayed during the period of oxygen uptake within the substrate. This period may be eliminated or. reduced either by removal of the heterogeneous layer by acid etching or by its modification by vacuum annealing. Although the disturbed substrate on abraded specimens serves in this way to provide evidence for the inward diffusion of oxygen, it exerts no appreciable control over the total oxygen uptake either above or below 200° C.

Download Full-text