Search results for "Fractal"

L'analyse fractale, nouvelle approche pour mesurer l'intensité des communications dans un réseau urbain

1997

International audience

Fractal behaviour of urban patterns on different scales

2002

Growing a Project-Based Translation Pedagogy: A Fractal Perspective

2012

Le présent article propose un cheminement fractal à travers la psychologie et la philosophie éducative, avec l’intention de faire la lumière sur une représentation arborescente de sources d’inspiration interdisciplinaires et complémentaires pour une pédagogie de la traduction par projets. Commençant par la méthode d’apprentissage socioconstructiviste proposée au tournant du millénaire, notre propos tente de brosser un vaste portrait des influences synergiques sous-jacentes à l’approche émergente « holistique-expérientielle » de la formation en traduction. Le post-modernisme, l’énaction dans les sciences cognitives, la théorie de la complexité, la théorie éducative transformationnelle et l’é…

Comparing methods for estimating the fractal nature of built-up surfaces in Brussels and Lyon

2014

International audience

Geometry control of the junction between two fractal curves

2012

International audience; The general objective of our work is to create a geometric modeller based on iterative processes. With this objective in mind, we have to provide tools that work with fractal objects in the same manner as with objects of classical topology. In this article we focus on the constructing of an intermediate curve between two other curves defined by different iterative construction processes. A similar problem often arises with subdivision surfaces, when the goal is to connect two surfaces with different subdivision masks. We start by dealing with curves, willing to later generalise our approach to surfaces. We formalise the problem with the Boundary Controlled Iterated F…

Cluster formation and rheology of photoreactive nanoparticle dispersions.

2008

We show how photocrosslinking of small nanoparticles within a very dilute colloidal dispersion leads to the formation of large fractal particle clusters, which have a strong influence on the viscosity of the dispersion although the overall solid content is well below 5 wt %. Furthermore, the solvent plays an important role because of its function as an optical filter, for example, in toluene only photocrosslinking but no photocleavage takes place. Therefore, a diffusion-controlled cluster growth mechanism, leading to clusters with low fractal dimension, is expected; on the other hand, in tetrahydrofuran the photoreaction is partially reversible. Therefore, the cluster growth in this case is…

Merging the transform step and the quantization step for Karhunen-Loeve transform based image compression

2000

Transform coding is one of the most important methods for lossy image compression. The optimum linear transform - known as Karhunen-Loeve transform (KLT) - was difficult to implement in the classic way. Now, due to continuous improvements in neural network's performance, the KLT method becomes more topical then ever. We propose a new scheme where the quantization step is merged together with the transform step during the learning phase. The new method is tested for different levels of quantization and for different types of quantizers. Experimental results presented in the paper prove that the new proposed scheme always gives better results than the state-of-the-art solution.

PD recognition by means of statistical and fractal parameters and a neural network

2000

A novel partial discharge (PD) defect identification method is described. Starting with PD data on different families of specimens, a suitable set of parameters are determined and then used as input variables to a neural network for the purpose of identifying the defects within the insulation. In this procedure the statistical Weibull analysis is performed on PD pulse amplitude histograms to obtain the scale parameter /spl alpha/ and the shape parameter /spl beta/. Thereafter, the two statistical operators (skewness and kurtosis) and two fractal parameters (fractal dimension and lacunarity) are evaluated from the PD phase on the discharge epoch histogram and from the 3 dimensional (pulse am…

Morphological similarities between DBM and an economic geography model of city growth

2009

International audience; An urban microeconomic model of households evolving in a 2Dcellular automata allows to simulate the growth of a metropolitan area whereland is devoted to housing, road network and agricultural/green areas. Thissystem is self-organised: based on individualistic decisions of economic agentswho compete on the land market, the model generates a metropolitan area withhouses, roads, and agriculture. Several simulation are performed. The resultsshow strong similarities with physical Dieletric breackdown models (DBM). Inparticular, phase transitions in the urban morphology occur when a controlparameter reaches critical values. Population density in our model and theelectric …

Mucoadhesive Polymer Hyaluronan as Biodegradable Cationic/Zwitterionic-Drug Delivery Vehicle

2014

Mucoadhesive polymers in pharmaceutical formulations release drugs in mucosal areas. They interact and fix to mucus via molecular interpenetration, etc ., which increase drug bioavailability. Polymers physicochemical properties affect formulation mucoadhesion, rheological behaviour and drug absorption. Hyaluronan (HA) is selected as a mucoadhesive and biodegradable polymer. Geometric, topological and fractal analyses are carried out with program TOPO. Reference calculations are performed with algorithm GEPOL. Procedure TOPO underestimates molecular volume by 0.7%. Error results 5% in surface area and derived topological indices. Solvent-accessible surface is undercalculated by 3%: from hexa…