Search results for "Computer simulation"
showing 10 items of 1054 documents
Multi-physical modelling of reverse electrodialysis
2017
Abstract Reverse electrodialysis (RED) is an electrochemical membrane process that directly converts the energy associated with the concentration difference between two salt solutions into electrical energy by means of a selective controlled mixing. The physics of RED involves the interaction of several phenomena of different nature and space-time scales. Therefore, mathematical modelling and numerical simulation tools are crucial for performance prediction. In this work, a multi-physical modelling approach for the simulation of RED units was developed. A periodic portion of a single cell pair was simulated in two dimensions. Fluid dynamics was simulated by the Navier-Stokes and continuity …
Cyclic tetraureas with variable flexibility--synthesis, crystal structures and properties.
2008
Macrocyclic molecules containing several amide or urea functions may serve as anion receptors. We describe the synthesis of 32-membered macrocycles, in which four rigid xanthene units (X) and/or diphenyl ether units (D) as flexible analogues are linked via urea groups. All six possible combinations of these units (XXXX, XXXD, XXDD, XDXD, XDDD and DDDD) were synthesized and two examples were characterised by single-crystal X-ray analyses (DDDD and two structures for XXXD). Both macrocycles showed distinct differences in their overall conformation and consequently in their hydrogen-bonding pattern. Hydrogen-bonded solvent molecules are found for both compounds and intramolecular hydrogen bond…
IV-Curves of tunnel junction arrays at lowered temperature by numerical simulation
1996
We have numerically investigated the effect of lowered T on the performance of the Coulomb blockade thermometer, which has been demostrated to yield primary thermometry in the high T limit where thermal excitations compete with the Coulomb blockade. The thermometer is formed by an array of tunnel junctions whose differentiated IV—curve is used to determine the temperature. The IV—curves were calculated by computer simulations and we have obtained corrections to the analytic high T behaviour due to the lowered temperature.
Kinetic modelling of the Zymomonas mobilis Entner-Doudoroff pathway: insights into control and functionality.
2013
Zymomonas mobilis, an ethanol-producing bacterium, possesses the Entner-Doudoroff (E-D) pathway, pyruvate decarboxylase and two alcohol dehydrogenase isoenzymes for the fermentative production of ethanol and carbon dioxide from glucose. Using available kinetic parameters, we have developed a kinetic model that incorporates the enzymic reactions of the E-D pathway, both alcohol dehydrogenases, transport reactions and reactions related to ATP metabolism. After optimizing the reaction parameters within likely physiological limits, the resulting kinetic model was capable of simulating glycolysis in vivo and in cell-free extracts with good agreement with the fluxes and steady-state intermediate …
Bend- and splitting loss of dielectric-loaded surface plasmon-polariton waveguides.
2008
International audience; The design, fabrication, characterization, and modeling of basic building blocks of plasmonic circuitry based on dielectric- loaded surface polariton waveguides, such as bends, splitters, and Mach- Zehnder interferometers are presented. The plasmonic components are realized by depositing subwavelength dielectric ridges on a smooth gold film using mass-production- compatible UV-photolithography. The near-field characterization at telecommunication wavelengths shows the strong mode confinement and low radiation and bend losses. The performance of the devices is found in good agreement with results obtained by full vectorial three-dimensional finite element simulations.…
Caustic Interpretation of the Abruptly Autofocusing Vortex beams
2021
We propose an effective scheme to interpret the abruptly autofocusing vortex beam. In our scheme, a set of analytical formulae are deduced to well predict not only the global caustic, before and after the focal plane, but also the focusing properties of the abruptly autofocusing vortex beam, including the axial position as well as the diameter of focal ring. Our analytical results are in excellent agreement with both numerical simulation and experimental results. Besides, we apply our analytical technique to the fine manipulation of the focusing properties with a scaling factor. This set of methods would be beneficial to a broad range of applications such as particle trapping and micromachi…
Vibrating temporal soliton pairs
2007
The study of temporal multisoliton complexes in dissipative systems is of potential interest for the development of new schemes of optical data transport and processing. In the present work, we thus consider pulsations of a soliton pair that consist mainly in the oscillations of the temporal separation and phase relationship between the two pulses, so that the relative motion of the two bound solitons resembles a vibrational motion.
Rogue wave description: Rational solitons and wave turbulence theory
2012
We show that rogue waves can emerge from optical turbulence and that their coherent deterministic description provided by the rational solutions is compatible with the statistical description provided by the wave turbulence theory.
On the possibility of observing bound soliton pairs in a wave-breaking-free mode-locked fiber laser
2007
On the basis of numerical simulations, we explain the formation of the stable bound soliton pairs that were experimentally reported in a high-power mode-locked ytterbium fiber laser [Opt. Express 14, 6075 (2006)], in a regime where wave-breaking-free operation is expected. A fully vectorial model allows one to rigorously reproduce the nonmonotonic nature for the nonlinear polarization effect that generally limits the power scalability of a single-pulse self-similar regime. Simulations show that a self-similar regime is not fully obtained, although positive linear chirps and parabolic spectra are always reported. As a consequence, nonvanishing pulse tails allow distant stable binding of high…
Nonlinear Sculpturing of Optical Pulses in Fibre Systems
2019
The interplay among the effects of dispersion, nonlinearity and gain/loss in optical fibre systems can be efficiently used to shape the pulses and manipulate and control the light dynamics and, hence, lead to different pulse-shaping regimes [1,2]. However, achieving a precise waveform with various prescribed characteristics is a complex issue that requires careful choice of the initial pulse conditions and system parameters. The general problem of optimisation towards a target operational regime in a complex multi-parameter space can be intelligently addressed by implementing machine-learning strategies. In this paper, we discuss a novel approach to the characterisation and optimisation of …