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Browsing by Author "Long, CS"

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  • Andhavarapu, EV; Loveday, P; Long, CS; Heyns, PS (SACAM 2010, 2010-01)
    The semi-analytical finite element method (SAFE) is a popular method for analysing guided wave propagation in elastic waveguides of complex cross-section such as rails. The convergence of these models has previously been ...
  • Long, CS; Loveday, PW; Groenwold, AA (Elsevier, 2009-01)
    Two new solid-of-revolution axisymmetric finite elements, which account for hoop fibre rotations, are introduced. The first is based on an irreducible formulation, with only displacement and rotation fields assumed ...
  • M'Boungui, G; Loveday, PW; Long, CS (Springer verlag (germany), 2011-01)
    The use of topology optimization in the design of a novel stator for an ultrasonic motor (USM) is investigated. The design challenge is to produce a stator, with two resonant modes whose frequencies are in a ratio of 1:2. ...
  • Long, CS; Loveday, PW; Forbes, A (HVG Hanseatische Veranstaltungs-GmbH, 2008-06)
    An intra-cavity adaptive mirror is developed for compensation of time-dependent phase aberrations to a laser beam, such as those caused by thermal lensing. The unimorph-type device consists of a metallic disc, with a mirror ...
  • Long, CS; Loveday, PW; Groenwold, AA (Elsevier, 2009-09)
    The effects of selected membrane, plate and flat shell finite element formulations on optimal topologies are numerically investigated. Two different membrane components are considered. The first is a standard 4-node bilinear ...
  • Long, CS; Loveday, PW; Groenwold, AA (Springer -Verlag, 2009-01)
    The effects of selected planar finite element formulations, and their associated integration schemes, on the stiffness of a checkerboard material layout are investigated. Standard 4-node bilinear elements, 8- and 9-node ...
  • M'Boungui, G; Loveday, PW; Long, CS (SACAM 2010, 2010-01)
    The authors investigate a novel ultrasonic motor which generates a stator trajectory in the form of a figure-of-eight by superimposing two resonant modes, with one double the frequency of the other. Topology optimization ...
  • Loveday, PW; Long, CS (SACAM 2014, 2014-01)
    A transducer array comprising four transducers was developed and used to perform pulse – echo measurements on a heavy duty welded rail track. A signal processing algorithm, which uses properties of the propagating modes ...
  • Litvin, IA; Loveday, PW; Long, CS; Kazak, NS; Belyi, V; Forbes, A (Society of Photo-Optical Instrumentation Engineers (SPIE), 2008-08)
    There are many applications in which a laser beam with a flat–top intensity profile would be ideal, as compared to a laser beam with a non–uniform energy distribution. Standard stable optical resonators will unfortunately ...
  • Loveday, PW; Long, CS (Elsevier, 2014-11)
    The ability to measure the individual modes of propagation is very beneficial during the development of guided wave ultrasound based rail monitoring systems. Scanning laser vibrometers can measure the displacement at a ...
  • Loveday, PW; Long, CS; Forbes, A; Land, K (South African Conference on Computational and Applied Mechanics, 2008-03)
    An intra-cavity adaptive mirror is required to compensate for time-dependent phase aberrations to the laser beam, such as those caused by thermal lensing. A piezoelectric unimorph design can provide a small, low-cost ...
  • Long, CS; Loveday, PW (South African Institute for Non-Destructive Testing (SAINT), 2012-04)
    The analysis of travelling waves in elastic waveguides with complex cross-sections, such as train rails, can only conveniently be performed numerically. The semi-analytical finite element (SAFE) method has become a popular ...
  • Long, CS; Loveday, PW (2014-01)
    A guided wave based monitoring system for welded freight rail, has previously been developed. The existing system was designed to only detect complete breaks. Current research efforts are focused on including a pulse-echo ...
  • Long, CS; Loveday, PW; Forbes, A; Land, K (SACAM 2010, 2010-01)
    For intra-cavity laser beam control, a small, low-cost deformable mirror is required. This mirror can be used to correct for time- dependent phase aberrations to the laser beam, such as those caused by thermal expansion ...
  • Long, CS; Loveday, PW (SACAM 2012, 2012-09)
    The semi-analytical finite element (SAFE) method has become a popular tool for the analysis of elastic waveguides with complex cross-sections. We employ a recently developed hybrid SAFE-3D FE method to study the scattering ...
  • Long, CS; Loveday, PW; Forbes, A (2008-03)
    This paper describes the development of a deformable mirror to be used in conjunction with diffractive optical elements inside a laser cavity. A prototype piezoelectric unimorph adaptive mirror was developed to correct for ...
  • Long, CS; Loveday, PW; Groenwold, AA (John Wiley & Sons Ltd, 2006-03-12)
    Several new planar four node piezoelectric elements with drilling degrees of freedom are presented. The authors begin by deriving two families of variational formulations accounting for piezoelectricity and in-plane ...
  • Ramatlo, DA; Long, CS; Loveday, PW; Wilke, DN (AIP Publishing, 2016-10)
    Our existing Ultrasonic Broken Rail Detection system detects complete breaks and primarily uses a propagating mode with energy concentrated in the head of the rail. Previous experimental studies have demonstrated that a ...
  • Loveday, PW; Long, CS (South African Institute for Non-Destructive Testing (SAINT), 2012-04)
    Guided wave based inspection and monitoring systems for railway tracks operate at frequencies where as many as 40 modes of propagation may exist. During the development of such systems it is advantageous to be able to ...
  • Loveday, PW; Long, CS (International Society for Optical Engineering (SPIE), 2007-03)
    Piezoelectric transducers are commonly used to excite waves in elastic waveguides such as pipes, rock bolts and rails. While it is possible to simulate the operation of these transducers attached to the waveguide, in the ...