Search results for "s.r.l.s."
showing 10 items of 213 documents
Rogue waves among noiselike-pulse laser emission: An experimental investigation
2014
We investigate experimental conditions in a fiber ring laser where noiselike-pulse emission fulfills the rogue wave criteria, highlighting the influence of the chromatic dispersion sign as well as the pivotal role of the pulse measurement design. While pulse-energy rogue waves are exclusively detected in the anomalous dispersion regime, spectral rogue waves are recorded for both positive and negative dispersions. To reveal $\mathsf{L}\text{-shaped}$ statistical series compatible with the generation of spectral rogue wave events, the dispersive Fourier-transform method is implemented to study the shot-to-shot spectral fluctuations of the laser output.
Hund's Rules and Spin Density Waves in Quantum Dots
1997
Spin density functional theory is used to calculate the ground state electronic structures of circular parabolic quantum dots. We find that such dots either have a spin configuration determined by Hund's rule or make a spin-density-wave-like state with zero total spin. The dependence of the spin-density-wave amplitudes on the density of the two-dimensional electron gas is studied.
Steady-state emission and stability of a single-mode two-level Fabry-Perot cavity laser
1997
Abstract An analytical steady-state solution for a single-mode homogeneously-broadened two-level Fabry-Perot laser, valid for any field intensity, cavity detuning and level-population decay rates, is obtained. A power-series expansion of this solution allows to perform a linear stability analysis which reveals the existence of two Hopf bifurcations instead of one as in unidirectional ring lasers. These bifurcations delimit the domain of unstable emission of the laser with respect to small perturbations. The instability threshold for hard-mode excitation is higher than in a ring laser, although introduction of a small definite detuning makes them similar. The time-dependent behaviour above t…
Deviation from Lorenz-type dynamics of an NH3 ring laser
1992
Abstract We show that the differences of the intensity spiral dynamics of an optically pumped NH 3 ring laser from that of the Lorenz model are caused by counterpropagating emission and by three-level coherence effects. In particular we find that under appropriate conditions the differences disappear and the laser emits purely according to the Lorenz model.
Utricularietum australis Th. Müller et Görs 1960 in Poland
2011
The paper presents the distribution, floristic composition and ecological requirements of the pleustonic plant community <em>Utricularietum australis</em> Th. Müller et Görs 1960 in Poland. The association was classifield to the Lemnetea minoris class. <em>Utricularietum australis</em> is considered to be a rare and endangered plant community in Europe.
Explotación de la tierra y tipos de mercado en la agricultura de la España contemporánea. Un comentario
1992
Se hace un repaso a los materiales presentados para el debate de la circulación del excedente en la España rural contemporánea. El debate se centró en las relaciones de propiedad y formas de tenencia de la tierra, la caracterización de los mercados agrarios y configuración de estrategias de participación en los mismos, y en las formas de gestión de las explotaciones. En las ponencias se destacó la intensa y diversa participación de los agentes sociales en los mercados de factores y los cambios en las formas de tenencia y explotación de la tierra como "estrategia" de adaptación de los propietarios a las diferentes coyunturas agrarias. The various points presented for the discussion over the …
Renforcement de la résistance à la corrosion localisée de l’acier inoxydable 304L grâce au traitement de surface par laser impulsionnel
2013
L’acier inoxydable 304L est utilise dans de nombreux domaines. Cependant, il peut, dans certaines conditions, etre sensible a la corrosion par piquration. Dans cette etude, nous nous sommes interesses aux potentialites du traitement de fusion superficielle par laser nanopulse pour l’amelioration de la resistance a la corrosion de cet acier. Ce traitement consiste a focaliser un faisceau laser sur la surface du materiau, provoquant sa fusion quasi instantanee sur quelques microns, immediatement suivie d’un refroidissement ultra-rapide allant jusqu’a 1011 K/s. Les parametres laser impliquent des modifications des proprietes physico-chimiques. Nous avons notamment etudie l’influence du recouvr…
Defect detection in laser powder deposition components by laser thermography and laser ultrasonic inspections
2013
Laser Powder Deposition (LDP) techniques are being adopted within aerospace and automotive manufacturing to produce innovative precision components. Non-destructive techniques (NDT) for detecting and quantifying flaws within these components enables performance and acceptance criteria to be verified, improving product safety and reducing ongoing maintenance and product repair costs. In this work, software enabled techniques are presented for in-process analysis of NDT laser ultrasonic signals and pulsed laser thermography images of sequential metallic LPD layers. LPD tracks can be as thin as 200μm while deposited at a rate of 500 mm/min, requiring ultrafast inspection and processing times. …
Modeling of interactions between xenobiotics and cytochrome P450 (CYP) enzymes
2015
The adverse effects to humans and environment of only few chemicals are well known. Absorption, distribution, metabolism, and excretion (ADME) are the steps of pharmaco/toxicokinetics that determine the internal dose of chemicals to which the organism is exposed. Of all the xenobiotic-metabolizing enzymes, the cytochrome P450 (CYP) enzymes are the most important due to their abundance and versatility. Reactions catalyzed by CYPs usually turn xenobiotics to harmless and excretable metabolites, but sometimes an innocuous xenobiotic is transformed into a toxic metabolite. Data on ADME and toxicity properties of compounds are increasingly generated using in vitro and modeling (in silico) tools.…
Influence of pump coherence on the dynamic behavior of a laser
1988
The dynamic behavior of a coherently pumped single-mode unidirectional ring laser with a homogeneously broadened three-level active medium is studied. Our formulation is based on a set often real equations of the plane-wave, mean-field Maxwell–Bloch type. The instability domain in the main control parameters space is determined. Our numerical study of these equations for a parameter range of the type explored in the recent experiments by Weiss Brock [ Phys. Rev. Lett.57, 2804 ( 1986)] reveals some similarities, but striking differences between our theoretical predictions and their experimental observations are also noted.