Experimental Facilities & Resources

Time Reversal Acoustics experiments are performed in our Nonlinear Elasticity Lab fully equipped for both quasi-static (measurements of stress-strain equation-of-state curves) and dynamic (wave propagation) experiments. The lab is equipped also for ultrasound imaging with different laser vibrometers and the experimental apparatus for resonant ultrasound spectroscopy.

Main Experimental Facilities

Polytec Scanning Laser Vibrometer (0-1.5 MHz)
Polytec Single Point Laser Vibrometer (0-1.5 MHz)
Polytec In-Plane Laser Vibrometer (0-1.5 MHz)
Motion Controlled X and Y Translational Stage Systems
HP 4192 LF Impedance Analyzer
Gage Data Acquisition Systems (3 - 8 Channel Generator Cards, 1 - 8 Channel Receiver Card, 8 - 2 Channel High Quality Receiver Cards)
Krohn-Hite Power Amplifiers (Single Channel)
ENI Power Amplifiers (Single Channel)
Artann RF Power Amplifiers (Ten Channel)
ADG Ultrasonic Welder
Ultraprobe 9000 Ultrasound Inspection Tool
Various Contact and Non-Contact Piezoelectric Transducers
Lock-In Amplifiers
Function Generators
Oscilloscopes
Press Instron 5569 (0-5kN and 0-30kN compression)

Computational Facilities and Resources

The group is equipped with High Performance Computing (HPC) resources for the modeling/simulation of elastic wave propagation in complex heterogeneous linear/nonlinear materials and in the earth. Numerical simulations are at the basis of the Time Reversal Computational Imaging technique used in our work: the Time Reversal backward propagation stage is simulated through a model of the propagation medium using as source signals the time reversed forward propagation signals measured during a forward propagation experiment with a lab specimen or the seismological signals measured by international seismological networks of stations around the world or in a specific region of the earth.

Our High Performance Computing Resources

Beowulf Linux cluster, 31 nodes; each node is a Symmetric Multi Processor (SMP) unit made of 2 AMD dual-core processors and 8 Gbytes of memory/node; 800 GBytes of scratch disk space and 2 TBytes of storage disk space; MPICH libraries, Pathscale and GCC compilers for C/Fortran 90 programs;
2 Dell Precision 690 workstations each of which is a 4 dual-core Intel Xeon 3.73 GHz Symmetric Multi Processor, used for data post processing and imaging analysis and processing.

Our Simulation Software

MPI-enabled parallel spectral elements (SE) method computational codes for seismic wave propagation in the Earth;
MPI-enabled parallel finite difference (FD) method computational codes for elastic wave propagation in solid specimen;
Multi-threaded finite element (FE) software platform for MultiPhysics simulations (Comsol MultiPhysics 3.4);
Matlab, GMT (General Mapping Tools), SAC (Seismic Analysis Code), Octave, Scilab computing platforms for data analysis and post processing.

TIME REVERSAL WORK at LANL