Search results for "FAST"
showing 10 items of 821 documents
An invasive species may be better than none: invasive signal and native noble crayfish have similar community effects
2014
14 pages; International audience; Human activities have resulted in the decline of native crayfish and promoted the spread of invasive crayfish species in European fresh waters, threatening ecosystem structure and functioning. We compared effects of native noble crayfish (Astacus astacus), invasive signal crayfish (Pacifastacus leniusculus) and of the absence of crayfish on leaf litter breakdown and invertebrate prey density and biomass in stream ecosystems. In microcosm experiments, invertebrate shredder density was significantly reduced by crayfish presence but similarly affected by the two crayfish species. While crayfish did not directly influence leaf litter breakdown, their presence r…
Gas-phase ion chemistry of protonated melatonin
2009
The gas-phase ion chemistry of protonated melatonin has been investigated by mass spectrometric (MS) techniques involving chemical ionisation, fast atom bombardment and electrospray ionisation. Either naturally-occurring or collision-induced decomposition experiments have been carried out using side chain tetra-deuterium-labelled derivatives, as well as the corresponding N–D derivatives obtained by exchange with D2O. The analysis of experimental results allows definite pathways for the formation of the ion at m/z 174 to be assigned and sheds some more light on the overall fragmentation pathways. Experiments on labelled derivatives evidenced H–D scrambling processes during fragmentation.
Wavelet-like bases for thin-wire integral equations in electromagnetics
2005
AbstractIn this paper, wavelets are used in solving, by the method of moments, a modified version of the thin-wire electric field integral equation, in frequency domain. The time domain electromagnetic quantities, are obtained by using the inverse discrete fast Fourier transform. The retarded scalar electric and vector magnetic potentials are employed in order to obtain the integral formulation. The discretized model generated by applying the direct method of moments via point-matching procedure, results in a linear system with a dense matrix which have to be solved for each frequency of the Fourier spectrum of the time domain impressed source. Therefore, orthogonal wavelet-like basis trans…
Uzņēmuma "SAF Tehnika" termoskapju vadības sistēma
2015
Uzņēmums “SAF Tehnika” izstrādā dažādas iekārtas un rīkus platjoslu datu pārraidei un mobilo komunikāciju pieejamībai, garantējot to netraucētu darbību dažādās temperatūras amplitūdās. Lai pārliecinātos, ka iekārtas strādās noteiktajos apstākļos, tās no sākuma ir jānotestē, ko ir iespējams izdarīt ar izstrādāto sistēmu. Izstrādātā sistēma ir iegultā sistēma, kas nozīmē, ka tā ir kādas lielākas sistēmas sastāvdaļa (šajā gadījumā to papildina izmantotie sensori temperatūras mērījumiem un termoskapji, kuros iekārtas tiek testētas) un ir paredzēta konkrētas darbības veikšanai – temperatūras kontrolēšanai termoskapī atbilstoši lietotāja izvēlētajam režīmam. Sistēma tiek darbināta uz Raspberry Pi…
Procesu nodrošināšanas platforma
2022
Kvalifikācijas darbs apraksta Apdrošināšanas atlīdzību pieteikumu procesu nodrošināšanas sistēmu, kura sastāv no divām sistēmām: Apdrošināšanas atlīdzību pieteikumu reģistrācijas lietotnes un Apdrošināšanas atlīdzību pieteikumu formu validācijas un apstrādes sistēmas. Lietotne izmanto Apdrošināšanas atlīdzību pieteikumu formu validācijas un apstrādes sistēmas REST API, kas tiek lietots apdrošināšanas klientu jeb lietotnes lietotāju autentifikācijai, apdrošināšanas atlīdzību pieteikumu izveidei un izveidoto pieteikumu apskatei. Lietotne realizēta JavaScript valodā, izmantojot Vue.js ietvaru, formu validācijas un apstrādes sistēma papildināta ar lietotāju moduli, kas izstrādāts Python valodā,…
Unraveling the LiNbO3 X-cut surface by atomic force microscopy and density functional theory
2014
The ${\text{LiNbO}}_{3}$(2$\overline{1}\overline{1}0$) surface, commonly referred to as X-cut, is investigated by means of atomic force microscopy and first-principles calculations. Atomically resolved atomic force microscopy images show geometrical patterns not compatible with truncated bulk terminations. Fast Fourier transformation of the real-space images shows an oblique surface unit cell with lattice parameters of $a=0.75\ifmmode\pm\else\textpm\fi{}0.02$ nm, $b=0.54\ifmmode\pm\else\textpm\fi{}0.02$ nm, and $\ensuremath{\alpha}=94.{8}^{\ensuremath{\circ}}$. Comparing these experimental results with the theoretical models of stable surface terminations provides clear evidence for the for…
Measurement of high order Kerr refractive index of major air components
2009
International audience; We measure the instantaneous electronic nonlinear refractive index of N2 , O2 , and Ar at room temperature for a 90 fs and 800 nm laser pulse. Measurements are calibrated by post-pulse molecular alignment through a polarization technique. At low intensity, quadratic coefficients n2 are determined. At higher intensities, a strong negative contribution with a higher nonlinearity appears, which leads to an overall negative nonlinear Kerr refractive index in air above 26 TW/cm2 .
Incoherent solitons and condensation processes
2006
International audience; We study the nonlinear interaction of partially incoherent nonlinear optical waves. We show that, in spite of the incoherence of the waves, coherent phase effects may play a relevant role during the propagation, in contrast with the usual wave turbulence description of the interaction. These nonlinear phase effects may lead the system to unexpected processes of self-organization, such as condensation, or incoherent soliton generation in instantaneous response nonlinear media. Such self-organization processes may be characterized by a reduction of the non-equilibrium entropy, which violates the Boltzmann's H-theorem of entropy growth inherent to the wave turbulence th…
Measurement of high order Kerr refractive index of major air components: erratum
2010
A clarification is missing concerning the high order Kerr non-linearities deduced from our experimental data published in [Opt. Express 17, 13429-13434 (2009)]. Here, we rectify this omission by making explicit the distinction between cross-Kerr and Kerr effects, and by extrapolating the value of the nonlinear refractive index for the last effect. Since the occurrence of sign inversion in the Kerr effect is not affected, the overall report in [Opt. Express 17, 13429-13434] remains valid.
General approach to spatiotemporal modulational instability processes
2011
International audience; In this article, we derive the general exact solution of the modulation instability gain. The solution described here is valid for 1-D, 2-D, and 3-D cases considering any temporal response function of the medium and with possible higher order Kerr nonlinearities. In particular, we show that the gain induced by modulation instability is initial condition dependent, while the usual calculations do not lead to such a dependence. Applications for current and high-interest nonlinear propagation problems, such as 1-D optical fiber propagation with delayed Raman response and 2-D filamentation in gases, are investigated in detail. More specifically, we demonstrate that the 2-D …