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Ravasi, M. (author), Ruan, J. (author), Vasconcelos, I. (author)
Local slopes carry useful information about the directionality of the predominant events in a seismic dataset and therefore can be used to steer the reconstruction process of sparsely sampled data. However, in the presence of spatial aliasing (for example, in the crossline direction of streamer data), conventional algorithms fail to provide a...
conference paper 2023
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Murano, Antonio (author), Mehrotra, A.A. (author), Ortega, Javier (author), Rodrigues, Hugo (author), Vasconcelos, Graça (author)
This work compares the ability of different numerical modelling approaches to simulate the out-of-plane behaviour of two-leaf stone masonry walls with different masonry bond configurations: an irregular drystone stone masonry wall and a masonry wall with roughly cut regular stone units. Finite element modelling, considering both a micro and...
journal article 2023
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Diekmann, Leon (author), Vasconcelos, Ivan (author), Wapenaar, C.P.A. (author), Slob, E.C. (author), Snieder, Roel (author)
Marchenko-type integrals typically relate so-called focusing functions and Green's functions via the reflection response measured on the open surface of a volume of interest. Originating from one dimensional inverse scattering theory, the extension to two and three dimensions set in motion various new developments regarding imaging in complex...
journal article 2023
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Gonçalves, Joana (author), Mateus, Ricardo (author), Dinis Silvestre, José (author), Pereira Roders, A. (author), Vasconcelos, Graça (author)
This paper presents and discusses the selection of a set of core indicators for the sustainable conservation of built heritage. This core set of indicators was selected by following a two-step methodology: 1) first, a comparative analysis of indicators of two building sustainability assessment (BSA) tools with different approaches was...
journal article 2021
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Peng, Haorui (author), Vasconcelos, Ivan (author), Sripanich, Yanadet (author), Zhang, L. (author)
Marchenko methods can retrieve both Green’s functions and focusing functions from single-sided reflection data and a smooth velocity model, as essential components of a redatuming process. Recent studies also show that a modified Marchenko scheme can reconstruct primary-only reflection responses directly from reflection data without requiring a...
journal article 2021
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Sripanich, Yanadet (author), Vasconcelos, Ivan (author), Wapenaar, C.P.A. (author)
The Marchenko method retrieves Green's functions between the acquisition surface and any arbitrary point in the medium. The process generally involves solving an inversion starting with an initial focusing function, e.g., a direct-wave Green's function from the desired subsurface position, typically obtained using an approximate velocity...
journal article 2019
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Vasconcelos, Luis A. (author), Neroni, Maria A. (author), Coimbra Cardoso, C.M. (author), Crilly, Nathan (author)
Design fixation experiments often report that participants exposed to an example solution generate fewer ideas than those who were not. This reduced ‘idea fluency’ is generally explained as participants’ creativity being constrained by the example they have seen. However, the inclusion of an example also introduces other factors that might...
journal article 2018
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Cui, Tianci (author), Vasconcelos, Ivan (author), Manen, Dirk Jan Van (author), Wapenaar, C.P.A. (author)
Marchenko redatuming can retrieve the impulse response to a subsurface virtual source from the single-sided surface reflection data with limited knowledge of the medium. We illustrate the concepts and practical aspects of Marchenko redatuming on a simple 1D acoustic lossless medium in which the coupled Marchenko equations are exact. Defined...
journal article 2018
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van der Neut, J.R. (author), Ravasi, Matteo (author), Liu, Y. (author), Vasconcelos, Ivan (author)
Seismic reflection data can be redatumed to a specified boundary in the subsurface by solving an inverse (or multidimensional deconvolution) problem. The redatumed data can be interpreted as an extended image of the subsurface at the redatuming boundary, depending on the subsurface offset and time. We retrieve targetenclosed extended images...
journal article 2017
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Vasconcelos, I. (author), Ravasi, M. (author), van der Neut, J.R. (author), Kritski, A. (author), Cui, T. (author)
The Marchenko redatuming approach reconstructs wavefields at depth that contain not only primary reflections, but also multiply-scattered waves. While such fields in principle contain additional subsurface information, conventional imaging approaches cannot tap into the information encoded in internal multiples in a trivial manner. We discuss a...
conference paper 2017
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Aldewereld, H.M. (author), Dignum, V (author), Vasconcelos, W (author)
Normative multi-agent systems offer the ability to integrate social and individual factors to provide increased levels of fidelity with respect to modelling social phenomena, such as cooperation, coordination, group decision making, and organization, in both human and artificial agent systems. An important open research issue refers to group...
journal article 2016
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Dignum, V. (author), Aldewereld, H.M. (author), Vasconcelos, W. (author)
Norms have been used to represent desirable behaviours that software agents should exhibit in sophisticated multi-agent solutions. An important open research issue refers to group norms, i.e. norms that govern groups of agents. Depending on the interpretation, group norms may be intended to affect the group as a whole, each member of a group, or...
conference paper 2015
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Van der Neut, J.R. (author), Wapenaar, C.P.A. (author), Thorbecke, J.W. (author), Slob, E.C. (author), Vasconcelos, I. (author)
In Marchenko imaging, wavefields are retrieved at specified focal points in the subsurface through an iterative scheme derived from the multidimensional Marchenko equation. The method requires seismic-reflection data at the earth’s surface (after free-surface multiple elimination) and an estimate of the direct wavefield from the surface to each...
journal article 2015
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Van der Neut, J.R. (author), Vasconcelos, I. (author), Wapenaar, C.P.A. (author)
Iterative substitution of the coupled Marchenko equations is a novel methodology to retrieve the Green's functions from a source or receiver array at an acquisition surface to an arbitrary location in an acoustic medium. The methodology requires as input the single-sided reflection response at the acquisition surface and an initial focusing...
journal article 2015
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Wapenaar, C.P.A. (author), Van der Neut, J.R. (author), Thorbecke, J.W. (author), Vasconcelos, I. (author), Van Manen, D.J. (author), Ravasi, M. (author)
Despite the close links between the fields of time-reversed acoustics, seismic interferometry and Marchenko imaging, a number of subtle differences exist. This paper reviews the various focusing conditions of these methods, the causality/acausality aspects of the corresponding focusing wavefields, and the requirements with respect to...
conference paper 2014
document
Van der Neut, J.R. (author), Wapenaar, C.P.A. (author), Thorbecke, J.W. (author), Vasconcelos, I. (author)
Recently, a novel iterative scheme was proposed to retrieve Green's functions in an unknown medium from its single-sided reflection response and an estimate of the propagation velocity. In Marchenko imaging, these Green's functions are used for seismic imaging with complete wavefields, including internal multiple reflections. In this way, common...
conference paper 2014
document
Wapenaar, C.P.A. (author), Thorbecke, J.W. (author), Van der Neut, J.R. (author), Vasconcelos, I. (author), Slob, E.C. (author)
Marchenko imaging is a new way to deal with internal multiple scattering in migration. It has been designed for layered media with smooth interfaces. Here we analyze the performance of the Marchenko scheme for a medium with many point scatterers. Although the conditions for Marchenko imaging are violated, we observe from a numerical experiment...
conference paper 2014
document
Van der Neut, J.R. (author), Vasconcelos, I. (author), Wapenaar, C.P.A. (author)
Recently, an iterative scheme was introduced to retrieve up- and downgoing Green’s functions at an arbitrary location F in the subsurface. The scheme uses the reflection data as acquired at the surface as input, together with an estimate of the direct arrival from the surface to location F, which is referred to as the initial focusing function....
conference paper 2014
document
Van der Neut, J.R. (author), Vasconcelos, I. (author), Wapenaar, C.P.A. (author)
lecture notes 2014
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Van der Neut, J.R. (author), Wapenaar, C.P.A. (author), Thorbecke, J.W. (author), Vasconcelos, I. (author)
Complex overburdens can severely distort transmitted wavefields, posing serious challenges for seismic imaging. In Marchenko redatuming, we use an iterative scheme to estimate so-called focusing functions, which can be used to redatum seismic wavefields to a specified level below the major complexities in the subsurface. Unlike in conventional...
conference paper 2014
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