Inquiring Systems in Approaches to Information Systems Development

The initial assertion of this paper is that information systems development (ISD) failures can best be addressed through a systems approach. Such an approach is characterised by Linstone’s Multiple Viewpoints or Checkland’s Soft System Methodology (SSM), both of which are supported by Singerian inquiring systems. The paper notes that these approaches are both forms of action research and therefore examines the support given to other forms of action research by Singerian inquiring systems. Organisations which recognise that they are not perfect when it comes to ISD and wish to do something about it can be considered as Learning Organisations. Senge’s approach to Learning Organisations is seen as being generic. In the context of ISD, it is contrasted with SSM. In particular, the support required by these approaches from the classical inquiring systems is being considered. Further, the implications of what any resolution might mean for ISD is also considered. The final focus is to consider the framework of ISD as a social construct and examine the benefits of a non-classical inquiring system, based on the philosophy of Rorty

Localisation in water wave and thin plate problems

Simulations obtained for water waves over rough seabed and waves in rough in vacuo plate. Attenuation rates of effective and individual wave fields extracted, compared and found to differ

Spectral analysis of wave propagation through rows of scatterers via random sampling and a coherent potential approximation

A method is proposed for determining the modal spectra of waves supported by arrays, which are composed of multiple rows of scatterers randomly disordered around an underlying periodic configuration. The method is applied to the canonical problem of arrays of identical small acoustically soft circular cylinders and disorder in the location of the rows. Two different approaches are adopted to calculate the modes: (i) forming an ensemble average of the modes from individual realizations (loosely: extract information, then average); and (ii) extracting the modes from the ensemble average wave field (loosely: average, then extract information). Differences in the attenuation rates predicted by the two approaches, which cannot be attributed to numerical errors, are found for problems involving multiple wave directions and large disorder. A form of the coherent potential approximation (CPA) is also devised. Comparisons of the CPA to the results given by random sampling show that it gives high accuracy. © 2013 Society for Industrial and Applied Mathematics.Luke G. Bennetts and Malte A. Pete

Graded resonator arrays for spatial frequency separation and amplification of water waves

A structure capable of substantially amplifying water waves over a broad range of frequencies at selected locations is proposed. The structure consists of a small number of C-shaped cylinders in a line array, with the cylinder properties graded along the array. Using linear potential-flow theory, it is shown that the energy carried by a plane incident wave is amplified within specified cylinders for wavelengths comparable to the array length and for a range of incident directions. Transfer-matrix analysis is used to attribute the large amplifications to excitation of local Rayleigh–Bloch waves and gradual slowing down of their group velocity along the array

Water-wave scattering and energy dissipation by a floating porous elastic plate in three dimensions

Abstract not availableMichael H. Meylan, Luke G. Bennetts, Malte A. Pete

Effective wave propagation along a rough thin-elastic beam

Abstract not availableSebastian Rupprecht, Luke G. Bennetts, Malte A. Pete

Low-frequency wave-energy amplification in graded two-dimensional resonator arrays

Energy amplification in square-lattice arrays of C-shaped low-frequency resonators, where the resonator radii are graded with distance, is investigated in the two-dimensional linear acoustics setting for both infinite (in one dimension) and finite arrays. Large amplifications of the incident energy are shown in certain array locations. The phenomenon is analysed using: (i) band diagrams for doubly-periodic arrays; (ii) numerical simulations for infinite and finite arrays; and (iii) eigenvalue analysis of transfer matrices operating over individual columns of the array. It is shown that the locations of the large amplifications are predicted by propagation cut-offs in the modes associated with the transfer-matrix eigenvalues. For the infinite array, the eigenvalues form a countable set, and for the low frequencies considered, only a single propagating mode exists for a given incident wave, which cuts off within the array, leading to predictive capabilities for the amplification location. For the finite array, it is shown that (in addition to a continuous spectrum of modes) multiple discrete propagating modes can be excited, with the grading generating new modes, as well as cutting others off, leading to complicated amplification patterns. The numerical simulations reveal that the largest amplifications are achieved for a single row array, with amplifications an order of magnitude smaller for the corresponding infinite array. This article is part of the theme issue 'Modelling of dynamic phenomena and localization in structured media (part 1)'.L. G. Bennetts, M. A. Peter and R. V. Craste

A three-dimensional model of wave attenuation in the marginal ice zone

Extent: 17p.A three-dimensional model of wave scattering by a large array of floating thin elastic plates is used to predict the rate of ocean wave attenuation in the marginal ice zone in terms of the properties of the ice cover and the incoming wavefield. This is regarded as a small step toward assimilating interactions of ocean waves with areas of sea ice into oceanic general circulation models. Numerical results confirm previous findings that attenuation is predominantly affected by wave period and by the average thickness of the ice cover. It is found that the shape and distribution of the floes and the inclusion of an Archimedean draft has little impact on the attenuation produced. The model demonstrates a linear relationship between ice cover concentration and attenuation. An additional study is conducted into the directional evolvement of the wavefield, where collimation and spreading can both occur, depending on the physical circumstances. Finally, the attenuation predicted by the new three-dimensional model is compared with an existing two-dimensional model and with two sets of experimental data, with the latter producing convincing agreement.L. G. Bennetts, M. A. Peter, V. A. Squire, and M. H. Meyla