Search results for "asma"

Fission studies at IGISOL/JYFLTRAP: Simulations of the ion guide for neutron-induced fission and comparison with experimental data

2020

For the production of exotic nuclei at the IGISOL facility, an ion guide for neutron-induced fission has been developed and tested in experiments. Fission fragments are produced inside the ion guide and collected using a helium buffer gas. Meanwhile, a GEANT4 model has been developed to simulate the transportation and stopping of the charged fission products. In a recent measurement of neutron-induced fission yields, implantation foils were located at different positions in the ion guide. The gamma spectra from these foils and the fission targets are compared to the results from the GEANT4 simulation. In order to allow fission yield measurements in the low yield regions, towards the tails a…

Short and Medium Range Order in Se1-xTexGlasses

1997

Complementary XAFS measurements (LURE and NSLS) of Se 1 - x Te x glasses have been carried out on both the Se and Te K-edges at low and room temperatures. Using a multi-shell best fit analysis procedure, we have reconstructed the Se and Te local environment: (i) first shell intrachain nearest neighbors (Se-Se 1 , Se-Te 1 , Te-Se 1 ,and Te-Te 1 ); (ii) second shell intrachain (Se-Se 2 and Se-Te 2 ) and interchain next nearest neighbors (Se⇔Se 3 single scattering in the chains Se-Se 1 -Se 3 and Se-Te 1 -Se 3 ). For the first and second coordination shells we suggest that the intrachain chemical order increases with Te content. On the other hand, we propose a model of random distribution of Se…

Dynamical Stark Effect in the nu(2)/nu(4) Vibrational Polyad of SiH(4): Theory and Observation.

2000

We report a theoretical and experimental investigation of the dynamical Stark effect in a tetrahedral molecule, silane (SiH(4)). We use a tetrahedral formalism and Floquet theory to calculate the absorption spectra for the molecule dressed by an intense nonresonant pulsed laser. Experimentally, the dynamical Stark effect is observed for transitions of the nu(2)/nu(4) vibrational polyad of SiH(4) by means of nanosecond diode laser absorption spectroscopy and a Nd:YAG laser excitation. Copyright 2000 Academic Press.

Floquet theory for temporal correlations and spectra in time-periodic open quantum systems: Application to squeezed parametric oscillation beyond the…

2021

Open quantum systems can display periodic dynamics at the classical level either due to external periodic modulations or to self-pulsing phenomena typically following a Hopf bifurcation. In both cases, the quantum fluctuations around classical solutions do not reach a quantum-statistical stationary state, which prevents adopting the simple and reliable methods used for stationary quantum systems. Here we put forward a general and efficient method to compute two-time correlations and corresponding spectral densities of time-periodic open quantum systems within the usual linearized (Gaussian) approximation for their dynamics. Using Floquet theory we show how the quantum Langevin equations for…

Plagiochasma appendiculatumLehm. & Lindenb. (Marchantiales, Aytoniaceae), a species new to the European bryophyte flora

2005

Abstract The liverwort Plagiochasma appendiculatum Lehm. & Lindenb. is reported for the first time in Europe from Mallorca (Balearic Islands, Spain). The species is described and illustrated and its distribution and ecology are discussed. Plagiochasma appendiculatum differsfromP. rupestre (J. R. Forst. & G. Forst.) Steph., the only species of the genus known at present in Europe, by characters such as the bright green or green-yellowish thallus and the orbicular and obtusescale appendages which are markedly constricted and folded at the base.

A New Systematic Series of Foil Sections with Parallel Sides

2020

Parallel-sided foil sections are used for centerboards and rudders in sailing dinghy classes and also for struts placed in a fluid flow. The objective of this work is to create a systematic series of parallel-sided sections to be used under different conditions, with an emphasis on the sailing dinghies 470, 420 and Optimist. The loss, and surprisingly the gain, in performance relative to 4-digit NACA sections are also investigated. A 2D Reynolds-averaged Navier&ndash

Axial dispersion of Brownian colloids in microfluidic channels

2016

Experimental research of surfaced nanoparticle thermal transport in a porous medium

2018

Abstract Experimental research on thermally induced nanocolloid transport in a porous environment is presented. Addition of excess surfactant to a colloid with dispersed phase made of surfaced nanoparticles results in a decrease of effective Soret coefficient in a porous environment. It is shown that with sufficient amounts of surfactant added, this effect extends to a reversal of nanoparticle thermophoretic transport direction, and that the effect shows a tendency of saturation. A mechanism of thermal transport that involves slip velocity of surfactant molecules appearing near pore walls is evaluated as a possible cause of the decrease of Soret coefficient. Effects of temperature on partic…

Optofluidic microconvection with magnetic nanoparticles: Novel interaction of thermal diffusion and magnetic field

2021

Abstract Light-matter interactions are exploited in many applications, whereas superparamagnetic nanoparticles allow to introduce magnetic field control in diverse fluid environments. We study the structure of laser-induced thermal lens in thin layers of ferromagnetic colloid and predict significant magnetoconvective motion around the beam spot. It was found that localized heating depletes/accumulates magnetic nanoparticles in the beam-spot by thermal diffusion and collective magnetic interactions of nanoparticles produce strong microconvective currents. This mode of mass transport can be controlled by magnetic field. We expect the novel magnetosolutal microconvective coupling, which we des…

Turbulences of the supersonic gas flow during cold spraying and their negative effects: A DNS CFD analysis coupled with experimental observation and …

2020

Abstract This paper investigates the phenomenological flow during cold spraying through DNS CFD analysis and experimental observations. The transient DNS computation shows that the gas flow begins to be instable inside the nozzle and generates self-sustained intermittent swirls across the nozzle exit due the shearing behavior of the flow. There is alternate swirling within the separated sheared layers on top and then on bottom of the jet, at sporadic time intervals. The swirls are not strictly periodic in nature, but they recur with an irregular frequency. The temperature field exhibits analogous variation and the thermal turbulence produces a heating confinement within the end zone of the …