GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (576)
  • 2010-2014  (576)
Document type
  • Articles  (576)
Source
Publisher
Years
Year
Journal
Topic
  • 1
    facet.materialart.
    Unknown
    A closed form solution method for rapid calculation of guided wave dispersion curves for pipes (2014)
    Elsevier
    Details
    Publication Date: 2014-12-24
    Description: Publication date: March 2015 Source: Wave Motion, Volume 53 Author(s): Ruth Sanderson Guided wave inspection is a fast growing technology for screening pipelines for corrosion. The technique is capable of inspecting tens of metres from a single test location and examining otherwise inaccessible regions of pipeline such as cased road crossings. However, enhancements to the technique are needed if inspections are to be transformed from a screening procedure to a more quantitative assessment of the condition of the pipeline. A rapid calculation procedure to determine the dispersion curves for guided wave modes is important if enhancements are to be automatically incorporated into the technique. Commercial code for dispersion curve calculation is available but it is proprietary and typically uses an iterative procedure to calculate curves which can be unreliable and slow. Other methods for calculating dispersion curves have been published including semi-analytical finite element solutions but these require extensive programming. In this paper, a closed form solution based on known trigonometric behaviour in the circumferential and axial directions and a standard polynomial solution through the thickness is presented. The method allows rapid computation of dispersion curves for typical guided wave inspection scenarios with minimal programming required. In addition, a tracing algorithm is also presented which allows the computed points to be joined to form curves and therefore fully identify the dispersive behaviour of each wave mode. The new method has been successfully verified against the well-established software, Disperse ® , for a range of pipe sizes, materials and frequencies typical to guided wave inspection.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    General plane or spherical electromagnetic waves with electric and magnetic fields parallel to each other (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 12 December 2014 Source: Wave Motion Author(s): Takahiro Nishiyama General plane-wave and spherical-wave solutions are found for Maxwell’s equations with electric and magnetic fields parallel to each other everywhere in a uniform isotropic sourceless medium. For deriving them, Beltrami’s and Chang–Carovillano–Low’s results about a Beltrami flow (or a force-free field) with a non-constant proportionality factor are applied to Uehara–Kawai–Shimoda’s equations. It is proved that other wave solutions, such as a cylindrical-wave solution, cannot be as general as the plane-wave or spherical-wave solution.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Surface waves problem in a thermoviscoelastic porous half-space (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 8 December 2014 Source: Wave Motion Author(s): Stan Chiriţă , Alexandre Danescu In this paper we analyze the surface Rayleigh waves in a half space filled by a linear thermoviscoelastic material with voids. We take into account the effect of the thermal and viscous dissipation energies upon the corresponding waves and, consequently, we study the damped in time wave solutions. The associated characteristic equation (the propagation condition) is a ten degree equation with complex coefficients and, therefore, its solutions are complex numbers. Consequently, the secular equation results to be with complex coefficients, and therefore, the surface wave is damped in time and dispersed. We obtain the explicit form of the solution to the surface wave propagation problem and we write the dispersion equation in terms of the wave speed and the thermoviscoelastic homogeneous profile. The secular equation is established in an implicit form and afterwards an explicit form is written for an isotropic and homogeneous thermoviscoelastic porous half-space. Furthermore, we use numerical methods and computations to solve the secular equation for some special classes of thermoviscoelastic materials considered in literature.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Improved multimodal methods for the acoustic propagation in waveguides with finite wall impedance (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 4 December 2014 Source: Wave Motion Author(s): Simon Félix , Agnès Maurel , Jean-François Mercier We address the problem of acoustic propagation in waveguides with wall impedance, or Robin, boundary condition. Two improved multimodal methods are developed to remedy the problem of the low convergence of the series in the standard modal approach. In the first improved method, the series is enriched with an additional mode, which is thought to be able to restore the right boundary condition. The second improved method consists in a reformulation of the expansions able to restore the right boundary conditions for any truncation, similar to polynomial subtraction technique. Surprisingly, the first improved method is found to be the most efficient. Notably, the convergence of the scattering properties is increased from N − 1 in the standard modal method to N − 3 in the reformulation and N − 5 in the formulation with a supplementary mode. The improved methods are shown to be of particular interest when surface waves are generated near the impedance wall.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Feasible fundamental solution of the multiphysics wave equation in inhomogeneous domains of complex shape (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 27 November 2014 Source: Wave Motion Author(s): Arkady M. Aizenberg , Alena A. Ayzenberg Fundamental solutions of the linear equations governing mechanical and electromagnetic oscillations are kinematically represented by delay time along ray trajectories. The fundamental solutions can contain components which are not physically justified, if their ray trajectories are partly located outside the actual medium in accordance with Fermat’s principle. To exclude all non-physical components and consider only the physically feasible fundamental solution, ray trajectories and delay time must satisfy the generalized Fermat’s principle, as introduced by Hadamard in 1910. We introduce a rigorous dynamic description of this feasible fundamental solution satisfying the generalized Fermat’s principle and being physically justifiable. The description is based on an integral condition of absolute absorption at the boundary of an effective medium. This condition selects a subset of the physically feasible fundamental solutions. We prove that, in homogeneous domains, the feasible fundamental solution is the sum of Green’s function for unbounded medium and an operator Neumann series describing cascade diffraction at the boundary. In inhomogeneous domains we represent the feasible fundamental solution by an equation with a volume integral operator. The integral kernel contains the feasible fundamental solution for a homogeneous domain. We introduce feasible surface and volume integral operators that eliminate the unfeasible wavefields in the geometrical shadow zones.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Characteristics of shear horizontal waves in magnetically affected ultra-thin films accounting for surface effect (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 12 November 2014 Source: Wave Motion Author(s): Keivan Kiani Consider a nano-scaled film which is made from highly conductive materials and is subjected to a uniform and constant magnetic field at the vicinity of its surfaces. The characteristics of the propagated shear horizontal (SH) waves within such a nanostructure are of particular interest. By decomposing the magnetically affected nanofilm into the surface layers and the bulk, surface elasticity is adopted and their equations of motion for the SH waves are constructed. The demonstrated dispersion curves reveal that the SH waves can propagate or be damped within the nanofilm in two manners: symmetric and asymmetric. Thereafter, the roles of the magnetic field strength and the thickness on the dispersion curves and phase velocities of both symmetric and asymmetric SH waves are addressed. Additionally, the limitations of the classical continuum theory in predicting the characteristics of SH waves are displayed and discussed.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Piezoelectric-sensitive mode of lamb wave in one-dimensional piezoelectric phononic crystal plate (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 10 December 2014 Source: Wave Motion Author(s): Y.F. Zhu , Y. Yuan , X.Y. Zou , J.C. Cheng We investigate the transmission modes in one-dimensional piezoelectric phononic crystal plate, which is consisted of piezoelectric ceramics placed periodically in epoxy. The influences of piezoelectricity and different electrical boundary conditions on the Lamb waves in the composite plate are studied in detail, and an important elastic wave mode named as piezoelectric-sensitive mode (PSM) is defined. Furthermore, the influences of the piezoelectric constants, the filling fraction and the ratio of thickness to lattice pitch on PSM are given, and the physical mechanism of PSM is also discussed. The numerical results show that PSM has a relatively larger frequency shift and significant change in the displacement distribution when piezoelectricity is considered; the electromechanical coupling coefficient of PSM is much larger than the other modes. It reveals that PSM is an important and useful mode in piezoelectric periodic structures. This investigation is helpful in controlling the band gaps and also gives a potential application in design of sensing system and different piezoelectric devices.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Improving spatio-temporal focusing and source reconstruction through deconvolution (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: January 2015 Source: Wave Motion, Volume 52 Author(s): Brian E. Anderson , Johannes Douma , T.J. Ulrich , Roel Snieder In this study, a technique is demonstrated to improve the ability of time reversal to both spatially and temporally focus, or compress, elastic wave energy, or to improve the quality of the reconstruction of the source signal. This method utilizes the deconvolution, or inverse filter, in single channel time reversal experiments in solids. Special attention is given to the necessary procedure for improving source signal reconstruction in real experimental conditions. It is also demonstrated theoretically and numerically that good temporal focusing implies that the radius in the spherically symmetric part of the spatial focus is small.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Numerical solution of the Benjamin equation (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: January 2015 Source: Wave Motion, Volume 52 Author(s): V.A. Dougalis , A. Duran , D. Mitsotakis In this paper we consider the Benjamin equation, a partial differential equation that models one-way propagation of long internal waves of small amplitude along the interface of two fluid layers under the effects of gravity and surface tension. We solve the periodic initial-value problem for the Benjamin equation numerically by a new fully discrete hybrid finite-element/spectral scheme, which we first validate by pinning down its accuracy and stability properties. After testing the evolution properties of the scheme in a study of propagation of single- and multi-pulse solitary waves of the Benjamin equation, we use it in an exploratory mode to illuminate phenomena such as overtaking collisions of solitary waves, and the stability of single-pulse, multi-pulse and ‘depression’ solitary waves.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Omnidirectional two-dimensional acoustic cloak by axisymmetric cylindrical lattices (2014)
    Elsevier
    Details
    Publication Date: 2014-12-18
    Description: Publication date: Available online 16 December 2014 Source: Wave Motion Author(s): Choonghee Jo , Jihoon Jeong , Byung-Jin Kwon , Kwang-Chun Park , Il-Kwon Oh We report a two-dimensional acoustic cloak designed with axisymmetric cylindrical lattices. The proposed axisymmetric lattice layers are optimized such that acoustic cloaking can be effectively realized within realistic material properties regardless of the incoming direction of plane waves. The cylindrical shape of lattice structures consists of five layers and each layer is composed of the same number of circular cylinders to form an axisymmetric lattice structure. The present results show that acoustic cloaking with axisymmetric cylindrical lattices can be realized with many advantages such as use of realistic material properties, simplified geometry, omnidirectional cloaking and controllable cloaking degrees.
    Print ISSN: 0165-2125
    Electronic ISSN: 1878-433X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...