Search results for "FrACT"
showing 10 items of 6229 documents
La fractalité des structures urbaines
1994
Urban patterns show often an irregular morphology. The fact that this phenomenon appears often despite of the intensions of planers and that it is not related to a particular historical situation, incites to suppose the existence of self-organisation process, promoting such an evolution. To get more insight in these aspects of urban growth, it has been investigated, whether there exists appropriated quantitative measures to characterize the irregular structures. The analysis of the build-up area of a certain number of agglomerations of the scale of metropolitan areas has shown, that the urban patterns follow an interior order principle, and that they may be characterized by fractal dimensio…
Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts
2019
A versatile synthetic strategy for the preparation of multimetallic oxynitrides has been designed and here exemplarily discussed considering the preparation of nanoscaled zinc-gallium oxynitrides and zinc-gallium-indium oxynitrides, two important photocatalysts of new generation, which proved to be active in key energy related processes from pollutant decomposition to overall water splitting. The synthesis presented here allows the preparation of small nanoparticles (less than 20 nm in average diameter), well-defined in size and shape, yet highly crystalline and with the highest surface area reported so far (up to 80 m2 g-1 ). X-ray diffraction studies show that the final material is not a…
Assessing Transfer Entropy in cardiovascular and respiratory time series: A VARFI approach
2021
In the study of complex biomedical systems represented by multivariate stochastic processes, such as the cardiovascular and respiratory systems, an issue of great relevance is the description of the system dynamics spanning multiple temporal scales. Recently, the quantification of multiscale complexity based on linear parametric models, incorporating autoregressive coefficients and fractional integration, encompassing short term dynamics and long-range correlations, was extended to multivariate time series. Within this Vector AutoRegressive Fractionally Integrated (VARFI) framework formalized for Gaussian processes, in this work we propose to estimate the Transfer Entropy, or equivalently G…
Performance analysis of Latvian zenith camera
2018
Since finalizing of design in 2016, the digital zenith camera of the University of Latvia was involved in a number of test observations as well as field observations at about 70 different sites. The paper presents analysis of observation results, estimation of instrument’s performance and accuracy. Random and systematic error sources are outlined. Impact of anomalous refraction on vertical deflection determination is discussed. Results of adaptation of GAIA reference star catalog for astrometric data reduction are reported.
Fractalité tridiastatique: propositions conceptuelles pour l'aménagement urbain
2015
National audience; Le contexte de cette communication est motivé par l’objectif de la ville durable (se¬lon la définition de l’ICLEI), et tente de contribuer aux solutions conceptuelles qui permettent d’y parvenir. Nous partons du principe que l’étalement urbain est certes identifié comme un processus néfaste a‘ la continuation de l’urbanisation (§ 1.1) , mais posons l’hypothèse qu’il nécessite un chan¬gement de paradigme (penser l’espace ur¬bain en 3D et non plus en 2D) pour être dépassé (§ 1.2).
Exploration trans-échelles d'une ville nouvelle à l'aide de l'analyse multiradiale
2017
National audience; L’analyse spatiale du bâti repose généralement sur des indicateurs de caractéristiques morphologiques absolues des bâtiments (taille, élongation, compacité, orientation) ou relatives (espacements, positions par rapport au voisinage, position par rapport au réseau), dont on calcule ensuite la distribution statistique, ou quelques résumés de cette distribution, comme la moyenne et l’écart-type. Ces mesures sont efficaces pour décrire l’aspect du tissu bâti (Regnault 2002, Sabo et al. 2005), mais souffrent d’une limitation importante : elles sont purement locales, et ne disent rien, ou presque, de l’organisation spatiale du bâti à d’autres échelles qui sont celles des quarti…
On the Dynamics of Fractional Visco-Elastic Beams
2012
With increasing advanced manufacturing process, visco-elastic materials are very attractive for mitigation of vibrations, provided that you may have advanced studies for capturing the realistic behavior of such materials. Experimental verification of the visco-elastic behavior is limited to some well-known low order models as the Maxwell or Kelvin models. However, both models are not sufficient to model the visco-elastic behavior of real materials, since only the Maxwell type can capture the relaxation tests and the Kelvin the creep tests, respectively. Very recently, it has been stressed that the most suitable model for capturing the visco-elastic behavior is the spring-pot, characterized …
Fractional Hardy inequalities and visibility of the boundary
2013
We prove fractional order Hardy inequalities on open sets under a combined fatness and visibility condition on the boundary. We demonstrate by counterexamples that fatness conditions alone are not sufficient for such Hardy inequalities to hold. In addition, we give a short exposition of various fatness conditions related to our main result, and apply fractional Hardy inequalities in connection to the boundedness of extension operators for fractional Sobolev spaces.
Estrabismo y visión binocular tras cirugía refractiva
2018
ANTECEDENTES: La cirugía refractiva ha demostrado ser segura y efectiva para la corrección de errores de refracción y estrabismos puramente acomodativos. Sin embargo, alteraciones sensoriomotoras como descompensación de estrabismos, aparición de diplopía y supresión son complicaciones también descritas tras la cirugía refractiva. OBJETIVOS: El objetivo principal fue evaluar los efectos en la alineación ocular y en la visión binocular, en términos de fusión y estereopsis, en pacientes sometidos a cirugía refractiva mediante técnicas tanto ablativas corneales como intraoculares. Los objetivos secundarios fueron determinar la prevalencia de alteraciones en la visión binocular y el alineamiento…
Virskorekcijas pielietojamība tuvredzības progresijas novērtēšanā ortokeratoloģijas pacientiem
2022
Darbs ir uzrakstīts angļu valodā uz 93 lapaspusēm. Tas satur 49 attēlus, 24 tabulas un 95 atsauces uz literatūras avotiem. Šī darba mērķis ir pārbaudīt, vai virskorekcija ir derīga metode tuvredzības progresēšanas novērtēšanai ortokeratoloģijā. Hipotēze ir atrast lielākas izmaiņas gados jaunākiem pacientiem nekā pieaugušajiem, kā tas ir norādīts literatūrā. Pētījumā iekļauti 192 Eiropeīdās rases subjekti vecumā no 6 līdz 56 gadiem (vidēji 19,61±10,30). Izmantojot retrospektīvu analīzi, no objektīva BOZR kontaktlēcas parametra tiek iegūta virskorekcija (ORX). Jaunākiem cilvēkiem ir lielākas ORX vērtības, bet pieaugušajiem nav atšķirības (p<0,05). Vidēji tuvredzība progresēja par –0,18±0,44 D…