Search results for " dynamic"
showing 10 items of 4727 documents
Analysing spatial dynamics using cellular automata-based artificial neural networks
2015
La modélisation de l'information spatio-temporelle
2012
Understanding Urban Fabric with the OH_FET model based on Social Use, Space and Time
2008
The proposed principle for understanding the urban fabric is based on considering the town as a set of complex objects, taking a systemic approach. The town system used to study the urban fabric over large time spans is composed of three sub-systems relating to historical objects from the level of the excavation to that of the former urban space: function (social use), space (location, surface area and morphology) and time (dating, duration and chronology). The historical object is the analytical unit of the space studied. It is the Cartesian product of the three sets, Social use, Space and Time, from which it stems. On the basis of this process, the Historical Object (OH) is broken down in…
Octopus, a computational framework for exploring light-driven phenomena and quantum dynamics in extended and finite systems
2020
Over the last few years, extraordinary advances in experimental and theoretical tools have allowed us to monitor and control matter at short time and atomic scales with a high degree of precision. An appealing and challenging route toward engineering materials with tailored properties is to find ways to design or selectively manipulate materials, especially at the quantum level. To this end, having a state-of-the-art ab initio computer simulation tool that enables a reliable and accurate simulation of light-induced changes in the physical and chemical properties of complex systems is of utmost importance. The first principles real-space-based Octopus project was born with that idea in mind,…
Realization of time-resolved two-vacuum-ultraviolet-photon ionization
2009
International audience; Ultrafast dynamics of excited molecules is studied through time-resolved two-vacuum-ultraviolet (vuv)- photon ionization using a nonlinear volume autocorrelator unit. The two-vuv-photon process is induced by the intense fifth harmonic radiation of a femtosecond Ti:sapphire laser. In a proof-of-principle experiment, ultrafast dynamics of excited ethylene and oxygen molecules are investigated. Molecular decay times are deduced by comparing the experimental data with the results of a numerical model that accounts for the spatial and temporal characteristics of the harmonic field. The present experiments pave a convenient way for time domain investigations in the vuv-xuv s…
Spectroscopic studies of semiconducting single-walled carbon nanotubes
2010
The unique nature of optical properties of single-walled carbon nanotubes (SWCNT), together with their promising potential applications, have created enormous interest towards the photophysics of SWCNT. Many aspects of carbon nanotubes originate from the electronic structure of carbon honeycomb lattice and one-dimensionality. SWCNTs exist in various chiral structures and diameters, which the optical and electrical properties are dependent on. It has been discovered that SWCNT excited states are excitonic with strong Coulomb interaction between the electron and the hole. However, many features of excitons are not yet well defined, such as absorption cross-sections, fluorescence quantum yield…
Il dynamic business model: una prospettiva dinamica per la progettazione dei modelli di business
2017
Building on the extant literature on business modelling and focussing on start-up firms, this article aims at exploring the combination between conventional business model schemes and System Dynamics methodology with the intent to overcome those limitations related to a static design approach. By mapping the multiple key elements underlying value creation processes – linked according to a cause-and-effect perspective – and with the support of a simulation-based methodology, entrepreneurs may experiment and understand how the firm reacts to strategic and organizational changes in terms of performance, innovation and value creation.
Inferring directionality of coupled dynamical systems using Gaussian process priors: Application on neurovascular systems
2022
Dynamical system theory has recently shown promise for uncovering causality and directionality in complex systems, particularly using the method of convergent cross mapping (CCM). In spite of its success in the literature, the presence of process noise raises concern about CCM's ability to uncover coupling direction. Furthermore, CCM's capacity to detect indirect causal links may be challenged in simulated unidrectionally coupled Rossler-Lorenz systems. To overcome these limitations, we propose a method that places a Gaussian process prior on a cross mapping function (named GP-CCM) to impose constraints on local state space neighborhood comparisons. Bayesian posterior likelihood and…