662 research outputs found
Sort by
No full textPoznańImpact of such terms as third order dispersion, self-steepening and stimulated Raman scattering on evolution of ultrashort pulses is considered in detail. Under influence of these effects, pulse did not maintain its initial shape. Pulse splits into constituents, its spectrum also evolving into several bands which are known as optical shock and self-frequency shift phenomena. We concluded that when the input peak power is large enough, dynamics of pulse splitting will be complicated. Our numerical simulations were in good agreement with experimental results
No full textPoznańWe presented the numerical technique to approximately solve the pulse propagation equation. Two efficient methods for this problem, the Split-Step Fourier and the fourth order Runge-Kutta methods are considered. Their high accuracy are shown by comparison with analytical solutions in some particular situations. Our numerical experiments are implemented for soliton propagation and interacting high order solitons. We also numerically investigate an important technique to create ultrashort pulses, which is known as the pulse compression. It is based on high order soliton propagation in Kerr media when the effect of stimulated Raman scattering is taken into account
No full textPoznańThe aim of this publication is to present a new probability distribution which for particular parameter values has a bimodal density function and a bathtub hazard rate function. All the main reliability properties of such distribution will be described in details in this paper. Such a distribution can constitute a very good mathematical model that would enable the description of the lifetime of technical devices. It can successfully be implemented in the planning of a burn-in procedure and a preventive maintenance of non-repairable devices
Automatyczne grupowanie wyników wyszukiwania w bibliotekach cyfrowych
Get PDFOmówienie mechanizmów automatycznego grupowania wyników wyszukiwania i prezentacja możliwości ich wykorzystania w bibliotekach cyfrowych
Rozproszone systemy uwierzytelniania użytkowników
Get PDFOmówienie zasad działania rozproszonych systemów uwierzytelniania i autoryzacji użytkowników w kontekście możliwości ich zastosowania w sieci rozproszonych bibliotek cyfrowych
No full textPoznańIn this work we investigated propagation of ultrashort laser pulses in dispersive nonlinear media. We derived a general propagation equation of pulses which includes the linear and nonlinear effects to all orders. We studied in the specific case of Kerr media and obtained an ultrashort pulse propagation equation called a Generalized Nonlinear Schrödinger Equation. The impact of the third order dispersion, the higher-order nonlinear terms self-steepening, and stimulated Raman scattering are explicitly analyzed
Zaawansowane usługi dla rozproszonych bibliotek cyfrowych
Get PDFOmówienie funkcji i zasad działania serwisu Federacja Bibliotek Cyfrowych, prezentacja dalszych możliwości rozwoju serwisu, dyskusja na temat nowych usług potrzebnych w sieci rozproszonych bibliotek cyfrowych
No full textPoznańFour definitions of skewness are discussed: classic skewness, two Pearson’s skewnesses and Bowley’s skewness. The ability of these skewnesses to express asymmetry is compared as well as the accuracy of their estimation from normal distribution is assessed
No full textPoznańLimited-data tomography, to which electromagnetic geotomography belongs, is analyzed in this paper. In this technique, a discrete forward projection model may be expressed by a rank-deficient system of linear equations whose the nullspace is non-trivial. This means that some image components may fall into the nullspace, and hence the minimal-norm least-square solution, to which many image reconstructions methods converge, may be different from the true one. The Algebraic Reconstruction Technique (ART), Simultaneous Iterative Reconstruction Technique (SIRT), or Conjugate Gradients Least Squares (CGLS) are examples of such methods. In this paper, we deal with the question of how to partially recover the missing image components. First, we analyze the advantages of using the iterative Tikhonov regularization and the Maximum A Posteriori (MAP) algorithm with Gibbs prior. Then, we conclude that the missing (nullspace) image components can be partially recovered if the MAP algorithm is implemented through a multigrid technique.The results, which are presented for synthetic noise-free and noisy data, demonstrate the validity of our assumption. The problem of estimating the regularization and scaling parameters in the MAP algorithm is also addressed