Search results for "fractal geometry"
showing 10 items of 13 documents
Relationship between particle size and dissolution rate of bulk powders and sieving characterized fractions of two qualities of orthoboric acid
1996
Drug Dev. Ind. Pharm. ISI Document Delivery No.: VN279 Times Cited: 1 Cited Reference Count: 22 Tromelin, A Habillon, S Andres, C Pourcelot, Y Chaillot, B; International audience; We have carried out a study of the particle size distribution and aqueous dissolution rate of two commercially available qualities of orthoboric acid, labeled ''crystal'' (ABC) and ''powder'' (ABP). In a previous work, we have shown that the two commercial qualities of orthoboric acid chosen as model compound (''powder'' and ''crystal'') are related to the same crystal network in spite of their different names. However, these two qualities have very different size particle distributions, as previously determined b…
P-T path development derived from shearband boudin microstructure
2016
This work focuses on the development of a regional P-T-path from the Malpica-Lamego Ductile Shear Zone, NW Portugal, based on the microstructures of shearband boudins evolved during progressive simple shear. The combination of microstructural analysis, fluid inclusion studies, crystallographic pre- ffered orientation and fractal geometry analyses, allows to link several stages in the internal evolution of the boudin to regional P-T conditions. The boudinage process is initiated under differential stress after the original layer achieved sufficient viscosity contrast relative to the surrounding matrix. Two main transformations occur simultaneously: i) change in the external shape with contin…
Multifractal models and their formal properties in urban geography
2019
International audience; Fractal analysis for exploring the spatial organization of settlement patterns is used since a coupleof years. On the one hand, scaling behavior turned out to be a suitable approach for characterizingsuch patterns, but town sections, issued from different periods of urban history or corresponding toparticular planning concepts show different types of scaling behavior what aided classifying urbanpatterns. However, on the scale of agglomerations these different scaling behaviors are mixed. Thatincites asking whether multifractal approaches could be of interest when considering urban patternsor settlement systems, as local properties like different degrees of concentrat…
A physically based connection between fractional calculus and fractal geometry
2014
We show a relation between fractional calculus and fractals, based only on physical and geometrical considerations. The link has been found in the physical origins of the power-laws, ruling the evolution of many natural phenomena, whose long memory and hereditary properties are mathematically modelled by differential operators of non integer order. Dealing with the relevant example of a viscous fluid seeping through a fractal shaped porous medium, we show that, once a physical phenomenon or process takes place on an underlying fractal geometry, then a power-law naturally comes up in ruling its evolution, whose order is related to the anomalous dimension of such geometry, as well as to the m…
Fractal geometry and urban patterns – from exploring morphology to applications in planning
2014
International audience; Fractal geometry turned out to be a powerful approach in many domains for describing complex structures which have multiscale properties. In particular, fractal analysis allows making evident scaling properties and hence underlying structural order principles which cannot be discovered by other measuring approaches like densities which refer to one unique scale. We present here how this approach helps to analyze the distribution of build-up surface in urban patterns and how it can be used to link these morphologiocal properties to specific contexts of urbanization. Indeed, contemporary urban patterns have usually an irregular shape reminding rather deposits on surfac…
Fractal geometry for modeling and measuring urban patterns
2012
International audience
Building scenarios for a LUTI model : articulation of spaced based models and an agent based model
2013
International audience
L'analyse fractale, un nouvel outil pour l'analyse spatiale des agglomérations urbaines
1997
The fractal approach. A new tool for the spatial analysis of urban agglomerations. Fractal geometry is a new approach for the study of spatial distributions. The basic model is a law of hierarchical distribution corresponding to Pareto's law which is familiar to urban geographers and demographers. The methods of fractal analysis can be used to study the spatial organization of human activities across scales. The regularities and the discontinuities in the distributions can then be identified. These discontinuities can be spatially situated. Applying this concept to urbanized areas has shown that districts can be defined and classified according to their scaling relations, thereby allowing d…
LA GEOMETRIE FRACTALE - UN NOUVEL OUTIL POUR EVALUER LE ROLE DE LA MORPHOLOGIE DES RESEAUX DE TRANSPORT PUBLIC DANS L'ORGANISATION SPATIALE DES AGGLO…
1998
National audience
Iterative geometric modelling and new world of shapes
2010
Mes recherches ont pour cadre la modélisation géométrique pour la Conception Assistée par Ordinateur et la Synthèse d'images. Plus précisément, j'étudie les possibilités qu'offrent les procédés de construction itératifs basés sur le principe de la géométrie fractale. Partant du modèle IFS (Iterated Function System), nous avons montré qu'il est possible de modéliser des formes non conventionnelles et ainsi de donner accès à un nouvel univers de formes aux concepteurs, artistes et designers. Cette approche est notamment utilisée pour modéliser des surfaces plissées (comme pour la réalisation de coques en architecture) ou des surfaces rugueuses. Nous avons orienté nos travaux sur la notion de …