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Wyświetlanie 1-14 z 14
Tytuł:
Terahertz Frequency Domain Spectroscopy Identification System Based on Decision Trees
Autorzy:
Ryniec, R.
Zagrajek, P.
Pałka, N.
Powiązania:
https://bibliotekanauki.pl/articles/1418036.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Bm
42.81.Cn
42.81.Dp
Opis:
The application of pattern recognition methodology within chemistry, biology and other science domains, especially in security systems is becoming more and more important. Many classification algorithms are available in literature but decision trees are the most commonly exploited because of their ease of implementation and understanding in comparison to other classification algorithms. Decision trees are powerful and popular tools for classification and prediction. In contrast to neural networks, decision trees represent rules, which can readily be expressed so that humans can understand them or even directly use in a database. In this paper we present an algorithm of construction of decision trees and a classification rule extraction based on a logical relationship between attributes and a generalized decision function. Moreover, correctness and efficiency of the algorithm was experimentally validated in a terahertz system, where spectra of explosives were measured in reflection configuration.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 891-895
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence Analysis of Mode Dispersion in Step-Index Polymer Optical Fibers
Autorzy:
Kovacevic, M.
Djordjevich, A.
Powiązania:
https://bibliotekanauki.pl/articles/1795632.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.-i
42.81.Ht
42.81.Dp
Opis:
Temperature dependence of the mode dispersion is investigated for commercially available polymethyl methacrylate (PMMA) based step-index polymer optical fibers. An analytical expression is proposed describing the thermal variation of the fiber refractive index. This index decreases with increasing temperature as density of the polymer material drops. The study covered the temperature range from -60°C to 100°C. Results show that the modal dispersion decreases and the bandwidth increases with rising temperature.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 649-651
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solitons in Nonlinear Directional Couplers with Optical Metamaterials by Trial Function Scheme
Autorzy:
Arnous, A.
Ekici, M.
Moshokoa, S.
Zaka Ullah, M.
Biswas, A.
Belic, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032564.pdf
Data publikacji:
2017-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Dp
42.65.Tg
Opis:
This paper obtains soliton solutions to nonlinear directional couplers in optical metamaterials by the aid of trial function method. Three types of couplers are studied. Four forms of nonlinearity are considered. Bright, dark, and singular soliton solutions are retrieved. These soliton solutions appear with certain constraint conditions that guarantee their existence.
Źródło:
Acta Physica Polonica A; 2017, 132, 4; 1399-1410
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polarization Properties of Liquid-Crystal Elliptical-Core Fibers
Autorzy:
Szymańska, A.
Woliński, T. R.
Powiązania:
https://bibliotekanauki.pl/articles/2023965.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.81.Qb
42.81.Dp
Opis:
Polarization properties of liquid-crystal core optical fibers have been investigated. The liquid-crystal fiber is characterized by elliptical anisotropic core with low birefringence liquid crystal introduced by capillary axis. The paper presents also initial experimental results of the liquid-crystal fiber in the polarimetric configuration subjected to the influence of selected perturbations.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 201-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Existence of Solitons for the Second Harmonic Equations of a Laser Beam
Autorzy:
Cao Long, V.
Goldstein, P. P.
Vu Ngoc, S.
Powiązania:
https://bibliotekanauki.pl/articles/2041595.pdf
Data publikacji:
2004-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Dp
Opis:
We look for conditions of existence of soliton solutions for equations governing propagation of a monochromatic laser beam coupled to its second harmonic in a nonlinear medium. The system proves to be non-integrable in the sense of Painlevé. However it is partially integrable for some values of its parameters. We further check the possibility of solving the equations by the Hirota bilinear method. The system is found to be solvable this way provided that amplitudes of both modes are equal while the complex phase of the second harmonic is equal to the double phase of the fundamental mode (moduloπ). The Hirota scheme is found to work merely for exact resonance, i.e. for the ratio of the dispersion coefficients equal to the ratio of frequencies. Finally, all these conditions may only be satisfied by single envelope travelling waves, in which the envelope has locally the shape of the Weierstrass function.
Źródło:
Acta Physica Polonica A; 2004, 106, 6; 843-852
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Existence of Solitons for the 3rd Harmonic of a Light Beam in Planar Waveguides
Autorzy:
Cao Long, V.
Goldstein, P. P.
Trippenbach, M.
Powiązania:
https://bibliotekanauki.pl/articles/2037293.pdf
Data publikacji:
2004-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Dp
Opis:
We consider equations governing propagation of a monochromatic laser beam coupled to its third harmonic in a nonlinear medium. The system proves to be non-integrable in the sense of Painleve. However it is partially integrable for all values of its parameters. We further check the possibility of solving the equations by the Hirota bilinear method. The system is found to be solvable this way provided that the complex phase of the third harmonics is equal to tripled phase of the fundamental mode (modulo i) and also the amplitudes of these modes are in special proportion. This result corresponds to the previously known condition of existence of the sech soliton solutions. Furthermore, the Hirota scheme is found to work only for exact resonance, i.e. for the ratio of the dispersion coefficients equal to the ratio of frequencies. Finally, all these conditions may only be satisfied for single envelope solitons of the cubic Schrödinger type.
Źródło:
Acta Physica Polonica A; 2004, 105, 5; 437-444
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multicriterial Analysis of Explosives in the THz Range
Autorzy:
Ryniec, R.
Piszczek, M.
Szustakowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1506835.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Bm
42.81.Cn
42.81.Dp
Opis:
The increasing interest in the development of identification methods of explosives in THz region over the past few years has been observed because of potential terrorist threats. To determine specific spectra properties of materials both possible spectroscopic methods - time domain spectroscopy and Fourier transform infrared spectroscopy are used to analyze different classes of compounds. This paper deals with an identification problem of more than one compound. This task was solved mathematically by means of the following methods: Monte Carlo including principal components analysis methods and analytic methods. Investigations were limited to a detector, which based on a single-frequency quantum dot matrix in 0.3 ÷ 1.3 THz range. The mathematical analysis also includes the atmosphere influence on propagation of THz waves. By means of the presented methods we indicated fourteen optimal frequency points and next we managed to identify one explosive from a set of ten explosives.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1235-1238
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hints on the Hirota Bilinear Method
Autorzy:
Goldstein, P.
Powiązania:
https://bibliotekanauki.pl/articles/1814021.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Ik
42.81.Dp
Opis:
We discuss four stages of the Hirota bilinear method, for construction of soliton solutions to partial differential equations: the proper substitution to express the equation in the bilinear variables (1), reduction of the excess degrees of freedom (2), the perturbation scheme (3), and solution of the system of equations at the successive orders of magnitude (4). For the first stage we suggest an extension of the well-known singularity analysis. In the second stage we point out the need for caution to avoid overdetermined systems. In the third one we suggest a path to proper assumptions on the orders of magnitude of the unknown functions. Finally, we summarize the question of the choice of appropriate solutions. For the expansions at the stages (1) and (3) we suggest a 'renormalization', i.e. completion of the lower order terms with higher order ones to achieve the desired form of the coefficients.
Źródło:
Acta Physica Polonica A; 2007, 112, 6; 1171-1184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
General Solution to a Bilinear Reduction of the Higher Order Nonlinear Schrödinger Equation
Autorzy:
Goldstein, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/2047168.pdf
Data publikacji:
2006-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Dp
Opis:
The general solution is found to a bilinear reduction of the higher order nonlinear Schrödinger equation. Except for the previously known special cases having multisoliton solutions, the solution has the form of a single envelope solitary wave or wave train for all other values of the parameters. We conjecture that the generic solution is limited to such a narrow class of functions because the bilinear system is overdetermined.
Źródło:
Acta Physica Polonica A; 2006, 110, 6; 769-775
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gaussian Beam Diffraction in Inhomogeneous and Nonlinear Saturable Media
Autorzy:
Berczynski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1399502.pdf
Data publikacji:
2013-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Bs
42.65.-k
42.65.Jx
42.65.Tg
42.81.Dp
42.81.-i
42.81.Ht
Opis:
The method of complex geometrical optics is presented, which describes Gaussian beam diffraction and self-focusing in smoothly inhomogeneous and nonlinear saturable media of cylindrical symmetry. Complex geometrical optics reduces the problem of Gaussian beam diffraction and self-focusing in inhomogeneous and nonlinear media to the system of the first order ordinary differential equations for the complex curvature of the wave front and for Gaussian beam amplitude, which can be readily solved both analytically and numerically. As a result, complex geometrical optics radically simplifies the description of Gaussian beam diffraction and self-focusing effects as compared to the other methods of nonlinear optics such as: variational method approach, method of moments, and beam propagation method. The power of complex geometrical optics method is presented on the example of Gaussian beam width evolution in saturable fibre with either focusing and defocusing refractive profiles. Besides, the influence of initial curvature of the wave front on Gaussian beam evolution in nonlinear saturable medium is discussed in this paper.
Źródło:
Acta Physica Polonica A; 2013, 124, 1; 56-61
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective Velocity of Soliton in the Presence of a Periodic Background
Autorzy:
Pełka, J.
Zagrodziński, J.
Powiązania:
https://bibliotekanauki.pl/articles/2029259.pdf
Data publikacji:
2001-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.50.Md
42.81.Dp
74.50.+r
85.25.Cp
Opis:
The effective soliton velocity in the presence of a periodic background differs from that when a soliton propagates alone. Using approximate relations for the Riemann-theta functions, the effective soliton velocity is derived and discussed. General relations are illustrated by examples of Korteweg de Vries and sine-Gordon equations because of the application in the Josephson junction theory.
Źródło:
Acta Physica Polonica A; 2001, 100, 6; 871-877
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coupling in Core-Ring Photonic Crystal Fibers
Autorzy:
Palka, N.
Ciurapiński, W.
Wojcik, J.
Szustakowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1811539.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Bm
42.81.Cn
42.81.Dp
Opis:
Experimental investigations of light coupling from a core into a ring caused by microbendings in photonic crystal fibres are shown. We present a setup arrangement, mode fields with and without coupling and a plot of power transfer versus localisation of the modulator along the fibre. We also show the most probable explanation of the obtained data.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-157-A-161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chirped optical solitons in birefringent fibers with parabolic law nonlinearity and four-wave mixing
Autorzy:
Triki, H.
Biswas, A.
Milović, D.
Belić, M.
Powiązania:
https://bibliotekanauki.pl/articles/1158116.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Dp
42.65.Tg
Opis:
We investigate exact soliton solutions with nonlinear chirp for the coupled nonlinear Schrödinger equations with cubic-quintic nonlinearity, self-steepening, self-frequency shift and four-wave mixing. The model governs the femtosecond pulse propagation in birefringent fibers. We introduce a new ansatz to obtain the nonlinear chirp associated with the propagating soliton pulses. New chirped soliton pair solutions with non-trivial chirping are found for the coupled nonlinear equations, illustrating the potentially rich set of solitonic pulse solutions of the model with higher-order effects. The solutions comprise two types of bright-W-shaped and bright-bright soliton pairs as well as kink and anti-kink pulses. Interestingly, the bright wave in the bright-W shaped soliton pairs possesses a platform underneath it, originating from the self-steepening and self-frequency shift effects. The corresponding chirp associated with each of these optical soliton pairs is also determined. It is shown that the nonlinear chirp is related to the pair intensity and determined by self-frequency shift and pause self-steepening. Parametric conditions for the existence and uniqueness of chirped solutions are given.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 718-726
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beam Propagation Method for Liquid Crystal-Core Optical Fiber Waveguides
Autorzy:
Szymańska, A.
Woliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/2008241.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.81.Qb
42.81.Dp
Opis:
Propagation effects in liquid crystal-core optical fiber waveguides were investigated and simulated by means of beam propagation method. Spatial propagation beam distribution for anisotropic liquid crystal fibers was defined by using BPM_CAD software package (courtesy of Optiwave Corporation). The field intensity was related to the refractive index of core at the liquid crystal fiber in two different waveguide configurations: planar and radial, whereas the number of the propagating modes was calculated. Numerical results were compared with some experimental data formerly obtained.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 761-766
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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