534 research outputs found
Schaalpartituren : onderzoek: partituren in de beeldanalyse I [Herplaatsing]
No full textIn beeldanalyse spelen schaal en lokale oriëntatie een prominente
rol. Waar bevat het beeld belangrijke informatie en op welke schaling
gebeurt dit? Een gestructureerde samenvatting van deze data
noemen we een partituur van de afbeelding. Deze partituur bevat
de multischaal- en multioriëntatieinformatie op een zo uitgesproken
mogelijke manier. Remco Duits, onderzoeker op het gebied van de
beeldanalyse en -interpretatie, beschrijft in dit overzichtsartikel de
vele wiskundige mogelijkheden om zo’n structuur op een afbeelding
aan te brengen. In dit eerste deel beperkt hij zich tot schaalpartituren
van een beeld en bijbehorende evolutievergelijkingen. Deze
schaalpartituren zijn natuurlijk niet erg homogeen; ze bevatten in
het bijzonder singuliere punten waarvan topologische eigenschappen
veranderen naarmate de schaal van observatie toeneemt. Vrijwel
het gehele originele beeld kan weer worden verkregen uit deze
singulariteiten. Kennis van deze singulariteiten is belangrijk voor
beeld–manipulatie, compressie en objectherkenning
Desiring to be desired: A discursive analysis of women's responses to the 'raunch culture' debates
No full textIn recent years, an explicitly sexualised style of femininity has become more visible in Western media and societies, accompanied by the idea that women can freely choose to use this mode of sexuality to signify their empowerment. This emergence of ‘raunch culture’ has sparked significant debates within the feminist literature as to how female agency should be conceptualised in a context wherein the seemingly continued objectification of women has come to be widely (re)interpreted as reflecting female empowerment and choice. This study seeks to contribute to these debates through a discursive analysis of talk produced in a series of focus groups with seventeen women, in which they discussed the raunch culture phenomenon and some of the related feminist arguments that have been raised. Whilst the participants frequently drew on the notions of ‘confidence/self-esteem’, ‘choice’ and ‘doing it for yourself’ as a defence for women’s participation in raunch culture, an underlying ambivalence and sense of discomfort about the quest for ‘empowerment’ via raunchiness was detected in their talk, though this was only rarely expressed as an explicit social critique of the gendered aspects of their lives. These findings are discussed in relation to the ways in which the participants’ use of these discourses allows them to position themselves as autonomous and freed from gendered constraints, as well as where these discourses become insufficient
[Rezension von:] Klinge, Ekkart: Duits steengoed : German stoneware. - Amsterdam : Rijksmuseum: 1996
No full textVoor is het partikel gekropen. Een experimenteel onderzoek naar het topicaliseren van partikels in het Duits.
No full textDe mogelijkheid om het partikel van een partikelwerkwoord te kunnen topicaliseren is volgens Trotzke, Quaglia en Wittenberg (2015) en Trotzke en Wittenberg (2017) afhankelijk van de semantische autonomie van het partikelwerkwoord, of het partikelwerkwoord gecontrasteerd kan worden en de mate van expressiviteit van het werkwoord. Dit lijkt echter niet het hele verhaal te zijn, omdat partikels met een referentiële betekenis zich makkelijker laten topicaliseren dan partikels zonder referentiële betekenis. Daarnaast lijken morfologisch complexe partikels met de referentiële vorm r- als raus (r + aus) ‘eruit’ makkelijker getopicaliseerd te kunnen worden dan partikels met de niet-referentiële vorm hin- als hinaus (hin + aus) ‘eruit’. Deze observaties heb ik in deze scriptie onderzocht aan de hand van een beoordelingstaak onder moedertaalsprekers van het Duits. Hieruit bleek dat het topicaliseren van een complex partikel gefaciliteerd wordt wanneer de zin een referentiële betekenis heeft. De referentiële vorm r- lijkt echter niet voldoende om topicalisatie van een partikel te faciliteren
Left invariant evolution equations on Gabor transforms
No full textBy means of the unitary Gabor transform one can relate operators on signals to operators
on the space of Gabor transforms. In order to obtain a translation and modulation
invariant operator on the space of signals, the corresponding operator on the reproducing
kernel space of Gabor transforms must be left invariant, i.e. it should commute with the left regular action of the Heisenberg group. By using the left invariant vector fields on H3 and the corresponding left-invariant vector fields on a cross-section of the phase space H3/¿ inthe generators of our transport and diffusion equations on Gabor transforms we naturally employ the essential group structure on the domain of a Gabor transform. We shall use these evolutions for three different tasks. First, there is the task of enhancing Gabor transforms (and corresponding signals) by means of non-linear left invariant diffusion. Secondly, there is the task of non-linear adaptive left-invariant convection (reassignment) towards the most probable curves, while maintaining the original signal. Finally, there is the task of extracting the most probable curves in the Gabor domain
A generalized transient network model for associative polymer networks
No full textA transient network model is described for a polymeric system consisting of linear chains, connected with temporary cross-links. The model is a reformulation and extension of a similar model which was presented recently [Wientjes, R. H. W.; Jongschaap, R. J. J.; Duits, M. H. G.; Mellema, J. A new transient network model for associative polymer networks. J. Rheol. 1999, 43, 375−391]. Contrary to common transient network models the interconnection between segments is explicitly taken into account. The dynamics of the system is also described by the state of a whole chain, instead of separate segments. As a result a prediction of the shape of relaxation spectra is possible. The model predicts broad spectra with long relaxation times, in particular for chains with many stickers. In the present formulation also systems with multiple types of stickers can be treated. In that case, plateau regions in dynamic moduli may appear
Poverty in the paintings of Jacopo Bassano: the crisis poor and the structural poor
No full textNo abstract available
Scale spaces on Lie groups
No full textIn the standard scale space approach one obtains a scale space representation u:R of an image by means of an evolution equation on the additive group (R d ,¿+¿). However, it is common to apply a wavelet transform (constructed via a representation of a Lie-group G and admissible wavelet ¿) to an image which provides a detailed overview of the group structure in an image. The result of such a wavelet transform provides a function on a group G (rather than (R d ,¿+¿)), which we call a score. Since the wavelet transform is unitary we have stable reconstruction by its adjoint. This allows us to link operators on images to operators on scores in a robust way. To ensure -invariance of the corresponding operator on the image the operator on the wavelet transform must be left-invariant. Therefore we focus on left-invariant evolution equations (and their resolvents) on the Lie-group G generated by a quadratic form Q on left invariant vector fields. These evolution equations correspond to stochastic processes on G and their solution is given by a group convolution with the corresponding Green’s function, for which we present an explicit derivation in two particular image analysis applications. In this article we describe a general approach how the concept of scale space can be extended by replacing the additive group R d by a Lie-group with more structure. The Dutch Organization for Scientific Research is gratefully acknowledged for financial support This article provides the theory and general framework we applied in [9],[5],[8]
Optimal paths for variants of the 2D and 3D reeds-shepp car with applications in image analysis
No full textWe introduce a PDE-based approach for finding minimal paths for the Reeds-Shepp car. In our model we minimize a (data-driven) functional involving both curvature and length penalization, with several generalizations. Our approach encompasses the 2D and 3D variants of this model, state dependent costs, and the possibility of removing the reverse gear of the vehicle. The model without reverse gear resembles Dubins's car, but without imposing a constraint on the curvature. We solve our model via eikonal equations on the manifold R^d ×S^{d−1} with respect to highly anisotropic Finsler functions, which approximate the singular (pseudo)-metrics underlying the model. This is achieved using a Fast-Marching method, based on specific discretization stencils which are adapted to the preferred directions of the metric and obey a generalized acuteness property. We justify our approach by convergence results. Our curve optimization model in R^d × S^{d−1} with data-driven cost allows to extract complex tubular structures from medical images and incomplete data due to occlusions or low contrast. Our work extends the results of Sanguinetti et al. on numerical sub-Riemannian eikonal equations and the Reeds-Shepp Car: we consider a 3D extension, and a new model without reverse gear which better handles bifurcations, relying on previous work by Mirebeau for the numerics. The anisotropic fast-marching approach is optimal for efficiency with limited loss of accuracy, although the differences compared to exact solutions by Duits et al. do become noticeable. Numerical experiments show the high potential of our method in two applications: retinal vessel tree extraction in 2D fundus images for the case d=2, and brain connectivity measures from diffusion weighted MRI-data for the case d=3, extending the work of Bekkers et al
Optimal paths for the Reeds-Shepp car with monotone spatial control and vessel tracking in medical image analysis
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