Singly and doubly periodic system of thin elastic inclusions in a three-dimensional body

1981 ◽  
Vol 16 (4) ◽  
pp. 375-379
Author(s):  
M. M. Stadnik ◽  
V. P. Silovanyuk
Keyword(s):  
Periodic System ◽  
Three Dimensional ◽  
Elastic Inclusions

Backpropagation and Multiple Signal Classification Imaging of Small Inclusions

2015 ◽  
Author(s):  
Habib Ammari ◽  
Elie Bretin ◽  
Josselin Garnier ◽  
Hyeonbae Kang ◽  
Hyundae Lee ◽  
...  
Keyword(s):  
Search Algorithm ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Music Algorithm ◽  
Isotropic Elasticity ◽  
Static Regime ◽  
Elastic Inclusions ◽  
And Migration

This chapter deals with direct imaging of small inclusions and cracks in the static regime, focusing on MUSIC- and migration-type algorithms for detecting the small defects. MUSIC, reverse-time migration, and Kirchhoff migration algorithms take advantage of the smallness of the elastic inclusions. Even though only the two-dimensional case is considered, the same algorithms can be applied in three dimensions. These direct location search algorithms are extended to the general case of linear isotropic elasticity. After describing least-squares algorithms for locating small elastic inclusions, the chapter introduces a MUSIC-type location search algorithm in the static regime and extends it to the time-harmonic regime. It also performs three-dimensional simulations to illustrate relevant features of the MUSIC algorithm.

DYNAMIC RESPONSE OF A THREE-DIMENSIONAL FLUID CHANNEL BOUNDED BY AN ELASTIC FLOOR IN THE PRESENCE OF A SUBMERGED INCLUSION VIA BEM

2005 ◽  
Vol 13 (01) ◽  
pp. 203-227 ◽  
Author(s):  
ANTÓNIO TADEU ◽  
LUÍS GODINHO ◽  
JULIETA ANTÓNIO
Keyword(s):  
Pressure Field ◽  
Fourier Transforms ◽  
Elastic Inclusion ◽  
Three Dimensional ◽  
Pressure Variation ◽  
Rigid Boundary ◽  
Line Load ◽  
Pressure Line ◽  
Fluid Channel ◽  
Elastic Inclusions

Numerical methods for computing the three-dimensional pressure field in a flat fluid channel bounded either by a rigid boundary, an elastic semi-infinite medium or by a layer of sediment, subjected to incoherent line sources are presented. After verification Greens functions are incorporated in a Boundary Element Method (BEM) code that simulates the pressure variation inside the fluid channel in the vicinity of a rigid or elastic inclusion, avoiding the discretization of the fluid and solid channel interfaces. After the verification of the solution, the models developed are then used to simulate the pressure variation within the fluid channel in the presence of infinitely long rigid and elastic inclusions of differing sizes, when the channel is struck by a spatially-sinusoidal harmonic pressure line load. The results are then compared with those obtained when the channel floor is assumed to be rigid. Time domain results are given by means of inverse Fourier transforms, to help understand how the mechanical properties of the channel floor may affect the variation of the pressure field within the channel.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

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