Search results for "SIMULATION"
showing 10 items of 5095 documents
Aerodynamics of an isolated ski jumping ski
2019
A single isolated ski was suspended from a six-component wind tunnel balance and three angles, the angle of attack, the yaw angle and the edge angle were adjustable during the test. Increasing yaw angle from 0 to 15° increased the lift coefficient CL from 0.42 to 0.90 at edge angle 0° and from 0.70 to 0.87 at edge angle 10°, respectively. Increasing yaw angle also increased the sensitivity of the ski to changes in edge angle, i.e., increasing the edge angle (20°–45°) decreased the CL and the ratio $$C_{L}^{2}/{C_D}$$ with large yaw angles. However, to maximize the lift-to-drag ratio with a typical angle of attack of 30° in ski jumping, it may be reasonable to have an edge angle of 5°–10° on…
Indoor artificial lighting: Prediction of the circadian effects of different spectral power distributions.
2014
The study presented in this paper aims to evaluate if and how the environment affects the circadian impact of a light source by predicting circadian stimulus (CS) resulting from the exposure to different light scenes, using equations reported in studies by Rea et al. The main findings are: (1) Above 600 lx at eye level the increase of CS is little; (2) Between 50 lx and 200 lx at the eye level an increase of only 50 lx determines a significant increase of CS; (3) Light sources with correlated colour temperatures between 2900 K and 4200 K have similar impacts on the circadian system according to the calculation method used; (4) Even an almost neutral environment affects the circadian impact…
The minimal model of Hahn for the Calvin cycle.
2018
There are many models of the Calvin cycle of photosynthesis in the literature. When investigating the dynamics of these models one strategy is to look at the simplest possible models in order to get the most detailed insights. We investigate a minimal model of the Calvin cycle introduced by Hahn while he was pursuing this strategy. In a variant of the model not including photorespiration it is shown that there exists exactly one positive steady state and that this steady state is unstable. For generic initial data either all concentrations tend to infinity at lates times or all concentrations tend to zero at late times. In a variant including photorespiration it is shown that for suitable v…
Hydrogen abstraction by photoexcited benzophenone: consequences for DNA photosensitization
2016
International audience; We report a computational investigation of the hydrogen abstraction (H-abstraction) induced by triplet benzophenone (3BP) on thymine nucleobase and backbone sugar. The chemical process is studied using both high level multiconfigurational perturbation and density functional theory. Both methods show good agreement in predicting small kinetic barriers. Furthermore the behavior of benzophenone in DNA is simulated using molecular dynamics and hybrid quantum mechanics/molecular mechanics methods. The accessibility of benzophenone to the labile hydrogens within B-DNA is demonstrated, as well as the driving force for this reaction. We evidence a strong dependence of the H-…
Excitation-Wavelength-Dependent Photocycle Initiation Dynamics Resolve Heterogeneity in the Photoactive Yellow Protein from Halorhodospira halophila
2018
Photoactive yellow proteins (PYPs) make up a diverse class of blue-light-absorbing bacterial photoreceptors. Electronic excitation of the p-coumaric acid chromophore covalently bound within PYP results in triphasic quenching kinetics; however, the molecular basis of this behavior remains unresolved. Here we explore this question by examining the excitation-wavelength dependence of the photodynamics of the PYP from Halorhodospira halophila via a combined experimental and computational approach. The fluorescence quantum yield, steady-state fluorescence emission maximum, and cryotrapping spectra are demonstrated to depend on excitation wavelength. We also compare the femtosecond photodynamics …
Modeling of an annular photocatalytic reactor for water purification: oxidation of pesticides.
2004
Photocatalytic oxidation (PCO) over titanium dioxide (TiO2) is a “green” sustainable process for the treatment and purification of water and wastewater. However, the application of PCO for wastewater treatment on an industrial scale is currently hindered by a lack of simple mathematical models that can be readily applied to reactor design. Current models are either too simplistic or too rigorous to be useful in photocatalytic reactor design, scale-up, and optimization. In this paper a simple mathematical model is presented for slurry, annular, photocatalytic reactors that still retains the essential elements of a rigorous approach while providing simple solutions. The model extends the appl…
Multi-scale dynamics simulations of molecular polaritons: The effect of multiple cavity modes on polariton relaxation
2021
It is included two versions of this item: the Accepted Version which is already Open Access and the Published Version which is under an embargo period till 2022-03-09.
Analysis of the human a-wave ERG component
2006
The a-wave is one of the main issues of research in the field of ocular electrophysiology, since it is strictly connected with early photoreceptoral activities. The present study proposes mathematical methods that analyse this component in human subjects, and supports experimental evidence relating to possible correlations among the responses of photoreceptoral units under a light stimulus. The investigation is organized in two parts: the first part concerns the onset and the initial slope, up to the first minimum (about 10-15 ms), the second part deals with the main portion of the wave, up to about 30 ms. In both cases, the a-waves, recorded at various levels of luminance, have been fitted…
Photoactivation of Drosophila melanogaster cryptochrome through sequential conformational transitions
2019
Time-resolved x-ray scattering reveals light-induced signal transduction in insect cryptochromes.
Experimental signature of optical wave thermalization through supercontinuum generation in photonic crystal fiber
2009
International audience; We report an experimental, numerical and theoretical study of the incoherent regime of supercontinuum generation in a two zero dispersion wavelengths fiber. By using a simple experimental setup, we show that the phenomenon of spectral broadening inherent to supercontinuum generation can be described as a thermalization process, which is characterized by an irreversible evolution of the optical field towards a thermal equilibrium state. In particular, the thermodynamic equilibrium spectrum predicted by the kinetic wave theory is characterized by a double peak structure, which has been found in quantitative agreement with the numerical simulations without adjustable pa…