Search results for "magnitude"
showing 10 items of 501 documents
Summary of Trap Properties
2009
Three-dimensional confinement of charged particles requires a potential energy minimum at some region in space, in order that the corresponding force is directed toward that region in all three dimensions. In general, the dependence of the magnitude of this force on the coordinates can have an arbitrary form; however, it is convenient to have a binding force that is harmonic, since this simplifies the analytical description of the particle motion.
Turbulent mixing and dispersion mechanisms over flexible and dense vegetation
2019
The present study investigates flow turbulence and dispersion processes in the presence of flexible and dense vegetation on the bed. The turbulent dispersion coefficients and the terms of the turbulent kinetic energy equation are determined by using data collected in a straight laboratory channel with living vegetation on the bed. Results show that the turbulent integral lengths assume an order of magnitude comparable to the stems’ characteristic dimension independently by the direction and the turbulence assumes an isotropic behavior. The coefficients of dispersion have a trend similar to that of the turbulent lengths and assume low values in the longitudinal, transversal and vertical dire…
Long-time dynamics of modulated waves in a nonlinear discrete LC transmission line.
2003
International audience; The long-time dynamics of modulated waves in a nonlinear LC transmission line is investigated. Considering the higher-order nonlinear Schrodinger equation, we define analytically the conditions leading to the instability of modulated waves. We show that two kinds of instabilities may develop in the network depending on the frequency range of the chosen carrier wave and on the magnitude of its initial amplitude, which is confirmed by our numerical simulations. The nonreproducibility of numerical experiments on modulated waves is also considered.
Elastic Metasurfaces for Deep and Robust Subwavelength Focusing and Imaging
2021
International audience; Metasurfaces are planar metamaterials with a flat surface and a subwavelength thickness that are able to shape arbitrary wave fronts such as focusing or imaging. There is a broad interest in the literature about subwavelength focusing and imaging based on bulk metamaterials while the utilization of metasurfaces for elastic waves has rarely been reported. Here, we present a type of elastic metasurface consisting of a line of gradient resonant pillars for robust deep subwavelength focusing and imaging of elastic waves in a plate. Numerical approaches supported by analytic Huygens-Fresnel demonstrations show that the subwavelength full width at half maximum (FWHM) behav…
Analytical formula for calculating the focal shift in apodized systems
1998
We report a quite simple analytical formula for the evaluation of the focal shift in apodized systems, with or without rotational invariance. Specifically it is shown that the magnitude of the focal shift is determined by the product of the Fresnel number of the focusing geometry and the standard deviation of a mapped version of the azimuthal average of the pupil transmittance. To illustrate our approach, several examples are examined.
Dyakonov surface waves in lossy metamaterials
2015
We analyze the existence of localized waves in the vicinities of the interface between two dielectrics, provided one of them is uniaxial and lossy. We found two families of surface waves, one of them approaching the well-known Dyakonov surface waves (DSWs). In addition, a new family of wave fields exists which are tightly bound to the interface. Although its appearance is clearly associated with the dissipative character of the anisotropic material, the characteristic propagation length of such surface waves might surpass the working wavelength by nearly two orders of magnitude. This research was funded by the Spanish Ministry of Economy and Competitiveness under the Project TEC2013-50416-E…
Cubic optical nonlinearity of
1999
We perform angular non-critical phase-matching third-harmonic generation (THG) experiments in (KTP). From these experiments, we determine the magnitude and sign of the two phase-matched nonlinear coefficients of by a complete analysis of phase-matching properties of the cascaded quadratic and pure cubic processes, the resolution of the coupled propagation equations and by the calculation of the quadratic and cubic dielectric susceptibility tensor by an extended bond charge model; we find: and . We also demonstrate that the two studied THG are mainly governed by the cubic interaction.
An improved value for the hyperfine splitting of hydrogen-like209Bi82+
2015
We report an improved measurement of the hyperfine splitting in hydrogen-like bismuth (209Bi82+) at the experimental storage ring ESR at GSI by laser spectroscopy on a coasting beam. Accuracy was improved by about an order of magnitude compared to the first observation in 1994. The most important improvement is an in situ high voltage measurement at the electron cooler (EC) platform with an accuracy at the 10 ppm level. Furthermore, the space charge effect of the EC current on the ion velocity was determined with two independent techniques that provided consistent results. The result of nm provides an important reference value for experiments testing bound-state quantum electrodynamics in t…
High redshift galaxies in the ALHAMBRA survey
2015
Context. Most observational results on the high redshift restframe UV-bright galaxies are based on samples pinpointed using the so called dropout technique or Ly-alpha selection. However, the availability of multifilter data allows now replacing the dropout selections by direct methods based on photometric redshifts. In this paper we present the methodology to select and study the population of high redshift galaxies in the ALHAMBRA survey data. Aims. Our aim is to develop a less biased methodology than the traditional dropout technique to study the high redshift galaxies in ALHAMBRA and other multifilter data. Thanks to the wide area ALHAMBRA covers, we especially aim at contributing in th…
The stellar content of the XMM-Newton Bright Serendipitous Survey
2006
Context: The comparison of observed counts in a given sky direction with predictions by Galactic models yields constraints to the spatial distribution and the stellar birthrate of young stellar populations. In this work we present the results of the analysis of the stellar content of the XMM-Newton Bright Serendipitous Survey (XBSS). This unbiased survey includes a total of 58 stellar sources selected in the 0.5 -- 4.5 keV energy band, having a limiting sensitivity of $10^{-2}$ cnt s$^{-1}$ and covering an area of 28.10 sq. deg. Aims: Our main goal is to understand the recent star formation history of the Galaxy in the vicinity of the Sun. Methods: We compare the observations with the predi…