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The paper presents preliminary results of data analysis and discusses the application of soft computing methods in the field of non-destructive tests. The main objective of developed diagnostic system are the automatic detection and evaluation of damage. Thus the system is composed of two signal processing techniques known as novelty detection and pattern recognition. For this purpose autoassociative as well as feed-forward neural networks are used. All the signals used for training the system are obtained from laboratory tests of strip specimens, where phenomenon of elastic wave propagation in solids was utilized. Computed parameters of time signals defines various types of input vectors used for training neural networks. The results finally obtained prove that the proposed diagnostic system made automation of structure testing possible and can be applied to Structural Health Monitoring. [ABSTRACT FROM AUTHOR]

In this paper, a new elastic-wave-based NDT system was proposed and then applied to reveal the defects inside the concrete specimens by imaging method. In this NDT system, it integrates the point-source/point-receiver scheme with the synthetic aperture focusing technique (SAFT) to achieve the effect like scanning with a phase array system; hence it is equipped with large functioning depth because of the high-energy feature that transient elastic wave method possessed over traditional ultrasonic method. This system is mainly composed of an impact source generator, a vertical displacement transducer, a signal capturing unit and operation software. To evaluate the feasibility of this system on NDT of concrete structures, some concrete slabs with artificial voids inside were built for experiment. 2D plane stress FEM numerical simulations were performed for further comparison. Experimental result shows good agreement with the numerical result not only on the B-scan diagram but also on the processed scanning image. The elastic-wave-based scanning system proposed in this paper exhibits high potential in inspecting the defects of in-situ concrete structures by imaging for civil engineering applications. [ABSTRACT FROM AUTHOR]

One of the primary goals in seismology is to predict realistic ground motion during an earthquake. The problem of seismic wave propagation based on partial differential equations is the part of continuum physics that deals with the medium at large scales, and the desired precision of the solutions allows approximating the matter as a continuum. Discrete methods for the solution of a wave equation have a practical interest to earthquake engineering community dealing with seismic risk problems. This paper presents solutions based on a spectral method involving Chebyshev grids. [ABSTRACT FROM AUTHOR]

Chapter 5, Section 8 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses on the significance of sonic well logging in an application of elastic waves in the petroleum industry. The logging aims to measure sonic velocity of the formation surrounding the well.

Chapter 5, Section 7 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses on the significance of the boundaries or interfaces between different parts of a medium for most aspects of rock acoustics. Reflections at interfaces are considered as the basis of surface seismics.

Chapter 5, Section 6 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses on the links between rock mechanics and rock acoustics. It discusses the association of the parameters describing elastic waves and the parameters describing rock mechanical properties.

Chapter 5, Section 5 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses on the anisotropic characteristics of rocks, mostly sedimentary rocks. This dependence may affect the acoustic properties of the rock which needs a generalized version of the wave equation and its solutions.

Chapter 5, Section 3 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses on the elastic waves in porous materials. It notes that the elastic response of a porous material may be affected through a pore fluid. Study shows that pore fluid's impact on the velocities is related to rock porosity.

Chapter 5, Section 2 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses the elastic wave propagation in an isotropic solid. It explains the polarization parallel to the direction of propagation (P-wave) and polarization normal to the direction of propagation (S-waves).

In this short paper we show how one may extract elastic properties of materials by probing it with elastic waves and processing the signal that returns (i.e. the scattered waves) in an appropriate way. In particular, we present a linearized inversion scheme to estimate the high-frequency, anisotropic components of the elastic tensor and density (the elastic moduli) in human tissue. For a given configuration source and receiver transducers, we show what combinations of moduli can be determined. Conversely, to estimate moduli in a specified region of the tissue, we derive an algorithm that searches for an optimal configuration of transducer pairs which best resolves the moduli. The ultimate goal of this work is application to biomedical imaging for early detection of tumours. [ABSTRACT FROM AUTHOR]

Surface wave method can be used to determine the properties of the component materials of a pavement structure. The measurements are made of the differences in the phase of a wave of the Rayleigh type, received at two points at known radial spacings from the source of the wave. Pavements for highways or airport runways are usually constructed of cement concrete. Such pavements are treated as a single layer of a constant thickness overlying a semi-infinite medium. The system is dispersive and inverse methods can be employed to determine the properties of the materials of the component layers of the structure. Algebraic inverse method has been developed and employed to conduct the inversion process of the experimental dispersion curve in order to back calculate the unknown parameters of the system. [ABSTRACT FROM AUTHOR]

The article presents information on acoustic microwaves devices. Surface acoustic wave (SAW) devices, have led to major advances in pulse compression radar and have become a critical enabling technology for the wireless communications industry. The principal benefit of employing SAW delay lines is the large group delays that are possible. Care must be exercised when designing a SAW filter having two apodized transducers. Since in this case the acoustic beam generated by the first apodized transducer will not be uniform across its width, the signal detected by each finger in the second transducer will not in general be proportional to its length.

Chapter 5, Section 9 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It focuses on the significance of seismic survey for mapping and characterization of large sub-surface structures. This survey aims to determine and localize the subsurface structures. Seismic shot is considered to be its basic element.

Chapter 5, Section 1 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes is presented. It presents the fundamentals of elastic wave propagation in porous media in rocks. It discusses the significance of wave equation which describes wave propagation mathematically. It notes that each part of the material is forced into oscillating motion when an elastic wave passes through it.

Several elastic wave propagation in rock formulas for calculations in the book ""Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes are presented.

References for the topics discussed in Chapter 5, Section 1 of the book "Petroleum Related Rock Mechanics," 2nd Edition, by Erling Fjaer, Rune M. Holt, Per Horsrud, Arne Marius M. Raaen and Rasmus Risnes are presented.

The article lists references used in Chapter 5, Section 1-9 of the book including "Quantitative Seismology," "Handbook of Physical Properties of Rocks" and "Evaluation of Anisotropy by Shear Wave Splitting."