Search results for "BESS"
showing 10 items of 144 documents
Impact of a temporal sinusoidal phase modulation on the optical spectrum
2018
International audience; We discuss the effects of imparting a temporal sinusoidal phase modulation to a continuous wave on the frequency spectrum. While a practical analytical solution to this problem already exists, we present here a physical interpretation based on interference processes. This simple model will help the students better understand the origin of the oscillatory structure that can be observed in the resulting spectrum and that is characteristic of Bessel functions of the first kind. We illustrate our approach with an example from the field of optics.
Control of nonlinear instabilities in Bessel beams using shaped longitudinal intensity profiles
2017
International audience; We show that tailored longitudinal intensity shaping of a non-diffracting Bessel beam can strongly reduce four wave mixing induced oscillations and stabilize nonlinear propagation at ablation-level intensities
Free-space delay lines and resonances with ultraslow pulsed Bessel beams
2008
We investigate the ultraslow motion of polychromatic Bessel beams in unbounded, nondispersive media. Control over the group velocity is exercised by means of the angular dispersion of pulsed Bessel beams of invariant transverse spatial frequency, which spontaneously emerge from near-field generators. Temporal dynamics in transients and resonances over homogeneous delay lines (dielectric slabs) are also examined.
Analytical formulation of the axial behavior of apodized general Bessel beams
1999
We present an analytical formula for the evaluation of the axial-irradiance distribution of general Bessel beams apodized by a radially-nonsymmetric window. Our approach is based on the similarity between the axial behavior of such beams and the propagation properties of a properly modified version of the window transmittance. To illustrate our formalism, we analyze the axial behavior of some complex beams.
X-wave bullets with negative group velocity in vacuum.
2006
Propagation-invariant, X waves with negative group velocity are reported. Beam aperturing allows for a comprehensive analysis concerning the causality of the optical signal and forerunner formation.
Forces Between Thin Coils With Parallel Axes Using Bessel Functions
2013
A method based on Bessel functions is presented for calculating the forces between combinations of thin coils with parallel axes. The coaxial case is solved in closed form in terms of elliptic integrals, whereas for the noncoaxial case the force components are expressed both as integrals of Bessel functions and as integrals of complete elliptic integrals. The results for the coaxial case have been compared with calculations in the literature with excellent agreement. The numerical results presented for the noncoaxial have been cross-checked by comparing the two methods. These methods can also be applied to current loops, disk coils, thick noncoaxial cylindrical coils, and various combinatio…
Zvaigžņotā Debess: 2009, Pavasaris (203)
2009
Contents: E.R.Mustel, President of the Astronomical Council of the USSR Academy of Sciences. Congratulations to Editorial Board of “Zvaigžņotā debess” ; Z.Alksne. Gould’s Belt ; I.Daube. At the Radioastrophysical Observatory of the Latvian Academy of Sciences ; Z.Alksne, A.Alksnis. Lopsided Galaxies ; A.Alksnis. HII Region Gum 29 – a Stellar Nursery ; D.Docenko. On Collision of Asteroid 2008 TC3 with the Earth ; V.Lapoška. On „Leap Second” ; I.Vilks, M.Gills. Beginning of the International Year of Astronomy in Paris: Impressions by Latvian Delegates ; J.Jaunbergs. Equatorial Ridge on Iapetus ; M.Sudārs. Space Shuttle Is Not Likely to Retire Next Year ; I.Vilks. Planet Satellite Names in Lat…
Indefinite integrals of quotients of Gauss hypergeometric functions
2018
A method recently applied to obtain indefinite integrals involving quotients of some common special functions is applied to obtain indefinite integrals of some quotients of Gauss hypergeometric fun...
Indefinite integrals of quotients of special functions
2018
ABSTRACTA new method is presented for deriving indefinite integrals involving quotients of special functions. The method combines an integration formula given previously with the recursion relations obeyed by the function. Some additional results are presented using an elementary method, here called reciprocation, which can also be used in combination with the new method to obtain additional quotient integrals. Sample results are given here for Bessel functions, Airy functions, associated Legendre functions and the three complete elliptic integrals. All results given have been numerically checked with Mathematica.
On some dual frames multipliers with at most countable spectra
2021
A dual frames multiplier is an operator consisting of analysis, multiplication and synthesis processes, where the analysis and the synthesis are made by two dual frames in a Hilbert space, respectively. In this paper we investigate the spectra of some dual frames multipliers giving, in particular, conditions to be at most countable. The contribution extends the results available in literature about the spectra of Bessel multipliers with symbol decaying to zero and of multipliers of dual Riesz bases.