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Tytuł:
Influence of atmospheric turbulence on bomb release
Wpływ turbulencji atmosferycznych na zrzut bomby
Autorzy:
Kowaleczko, G.
Żyluk, A.
Powiązania:
https://bibliotekanauki.pl/articles/280204.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
atmospheric turbulence
bombing
Opis:
A model of the bomb release dynamics is presented in the paper, and how it is influenced by a wind field. The applied way of describing this field is discussed with account taken of its stochastic nature. Exemplary results of a numerical simulation of bombing are submitted and concluded.
W pracy przedstawiono model dynamiki zrzutu bomby. Pokazano wpływ pola wiatru na szybowanie bomby. Strukturę wiatru opisano, uwzględniając jego stochastyczny charakter. Pokazano wyniki symulacji numerycznej zrzutu oraz poddano je analizie.
Źródło:
Journal of Theoretical and Applied Mechanics; 2009, 47, 1; 69-90
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sensitivity of a bomb to wind turbulence
Wrażliwość bomby na turbulencje wiatru
Autorzy:
Żyluk, A.
Powiązania:
https://bibliotekanauki.pl/articles/279357.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
bomb release
atmospheric turbulence
Opis:
This paper presents results of numerical investigations into the bomb release in a turbulent wind field. Short descriptions of mathematical models of both the bomb dynamics and the stochastic wind are shown. The effect of parameters of the turbulent wind field on a random distribution of points of the impact is investigated.
W pracy przedstawiono wyniki numerycznej symulacji wpływu turbulencji wiatru na zrzut bomby. Praca zawiera opis matematyczny dynamiki lotu bomby oraz stochastycznego pola wiatru. Badano zależność pomiędzy parametrami turbulencji i punktem upadku bomby.
Źródło:
Journal of Theoretical and Applied Mechanics; 2009, 47, 4; 815-828
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An efficient algorithm for determining positions of astronomical objects in the Deep Sky Object pictures
Autorzy:
Suszynski, R.
Wawryn, K.
Dziębowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/201895.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
effect of atmospheric turbulence
filtering of Deep Sky Object images
Gaussian noise
efekt turbulencji atmosferycznej
obiekt głębokiego nieba
obiekt astronomiczny
Opis:
The article presents an algorithm for digital image processing of astronomical objects in order to effectively determine the position of these objects. The proposed method has been optimized due to its effectiveness of removing noise and distortion caused by atmospheric turbulence and imperfections in long exposure photography of astronomical objects. This solution is ready for implementation in a system for automatic identification of stars in the recorded images. Such a system is designed for GoTo circuits at telescope’s drives, which can automatically point a telescope to astronomical objects. The method was verified by simulation in MATLAB program on real images of astronomical objects.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 3; 679-684
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic evolution and classification of coherent vortices in atmospheric turbulence
Autorzy:
Zeng, J.
Li, J
Powiązania:
https://bibliotekanauki.pl/articles/174463.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
vortex beam
coherent vortices
atmospheric turbulence
Opis:
Based on the extended Huygens–Fresnel principle, the analytical expressions for the cross-spectral density function of partially coherent sine-Gaussian vortex beams and partially coherent sine-Gaussian non-vortex beams propagating through free space and atmospheric turbulence are derived, and used to study the dynamic evolution behavior of coherent vortices in free space and atmospheric turbulence. According to the creation, the coherent vortices are grouped into three classes: the first is their inherent coherent vortices of the vortex beam, the second is created by the vortex beam itself during transmission process in free space, and the third is created by the atmospheric turbulence inducing the vortex beam.
Źródło:
Optica Applicata; 2015, 45, 3; 299-308
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal threshold detection for Málaga turbulent optical links
Autorzy:
Jurado-Navas, A.
Garrido-Balsells, J. M.
Castillo-Vázquez, M.
Puerta-Notario, A.
Monroy, I. T.
Olmos, J. J. V.
Powiązania:
https://bibliotekanauki.pl/articles/173418.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
atmospheric propagation
atmospheric turbulence
Malaga distribution
scintillation
Opis:
A new and generalized statistical model, called Málaga distribution (M distribution), has been derived recently to characterize the irradiance fluctuations of an unbounded optical wave front propagating through a turbulent medium under all irradiance fluctuation conditions. As great advantages associated to that model, we can indicate that it is written in a simple tractable closed-form expression and that it is able to unify most of the proposed statistical models for free-space optical communications derived until now in the scientific literature. Based on that Málaga model, we have analyzed in this paper the role of the detection threshold in a free-space optical system employing an on-off keying modulation technique and involved in different scenarios, and taking into account the extinction ratio associated to the employed laser. First we have derived some analytical expressions for the lower-bound performance of the free-space optical system with the light intensity fading induced by turbulence obtained when the additive white Gaussian noise is not present in the system. Then, we have analyzed the optimal threshold in the system and how it changes when atmospheric conditions vary. Finally, a closed form expression for the bit error rate of that system is derived.
Źródło:
Optica Applicata; 2016, 46, 4; 577-595
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Analysis of WDM-FSO Link under Turbulence Channel
Autorzy:
Mazin, Ali A. Ali
Powiązania:
https://bibliotekanauki.pl/articles/1192036.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
free space optics
BER
Atmospheric Turbulence
NRZ format
RZ technique
Opis:
In this paper, the performance analysis of FSO communication link in various atmospheric turbulence has been analysis for different bit rate using NRZ and RZ technique. The effect of turbulence on the link performance has been investigated by varying bit rate, turbulence strength and modulation format. FSO performance carried out for BER, Q. factor, received power under maximum link. Simulation results show that RZ format is best for strong turbulence. Where NRZ technique is used for low and medium turbulence.
Źródło:
World Scientific News; 2016, 50; 160-173
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in the states of polarization of random electromagnetic beams in atmospheric turbulence
Autorzy:
Li, J.
Zhao, K.
Lai, Y.
Powiązania:
https://bibliotekanauki.pl/articles/174110.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
non-Kolmogorov atmospheric turbulence
random electromagnetic beams
degree of polarization
orientation angle
degree of ellipticity
Opis:
Taking the random electromagnetic cosh-Gaussian beam as a typical example of random electromagnetic beams, the analytical expressions for the cross-spectral density matrix element of random electromagnetic cosh-Gaussian beams propagating through non-Kolmogorov atmospheric turbulence are derived, and used to study the changes in the states of polarization (degree of polarization, orientation angle and degree of ellipticity) of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence. It is shown that the states of polarization of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence are different from those in free space. The degree of polarization decreases, and the orientation angle and degree of ellipticity increase with increasing structure constant. The on-axis degree of polarization and the degree of ellipticity appear to have an oscillatory behavior and the orientation angle has a rapid transition for the larger cosh-part parameter of random electromagnetic cosh-Gaussian beams in atmospheric turbulence.
Źródło:
Optica Applicata; 2017, 47, 1; 51-62
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of sub-channel based Málaga atmospheric optical links with real β parameter
Autorzy:
López-González, F. J.
Jurado-Navas, A.
Garrido-Balsells, J. M.
Castillo-Vázquez, M.
Puerta-Notario, A.
Powiązania:
https://bibliotekanauki.pl/articles/174807.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Malaga distribution
generalized-K distribution
atmospheric optical communications
atmospheric propagation
atmospheric turbulence
scintillation
Opis:
A generalization of the Málaga atmospheric optical communications links treated as a finite number of generalized-K distributed sub-channels is analyzed in terms of outage probability and outage rate when its β parameter belongs to the set of real numbers. To the best of the author’s knowledge, this is the first time that β ∈ ℜ is considered. The new analytical expressions derived in this paper lead to a new physical and more realistic interpretation of atmospheric optical links, especially in terms of performance.
Źródło:
Optica Applicata; 2017, 47, 4; 545-556
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic evolution of mixed circular edge-screw dislocations
Autorzy:
Gao, P.
Li, J.
Cheng, K.
Duan, M.
Powiązania:
https://bibliotekanauki.pl/articles/173359.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mixed circular edge-screw dislocations
optical vortex
circular edge dislocations
atmospheric turbulence
Opis:
Based on the extended Huygens–Fresnel principle, the analytical expressions for the cross-spectral density function of mixed circular edge-screw dislocations beams propagating through atmospheric turbulence have been derived, and used to study the dynamic evolution of mixed circular edge-screw dislocations in free space and atmospheric turbulence. It is shown that the radius of circular edge dislocations increases with increasing propagation distance, and both the positions of the optical vortex and the center of circular edge dislocations are located at the point (0, 0) when mixed circular edge-screw dislocations propagate in free space. When mixed circular edge-screw dislocations propagate in the atmospheric turbulence, the position of optical vortices varies with increasing propagation distance, the circular edge dislocation evolves into a pair of optical vortices with the opposite topological charge ±1, and the pair of optical vortices will annihilate as soon as the propagation distance becomes large enough.
Źródło:
Optica Applicata; 2017, 47, 3; 471-481
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of zero and non-zero boresight pointing errors on bit-error rate free-space optic transmission over Málaga atmospheric channel
Autorzy:
Smilić, M.
Perić, Z.
Milić, D.
Marković, A.
Savić, M.
Powiązania:
https://bibliotekanauki.pl/articles/173446.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
free-space optic system
FSO
Málaga atmospheric turbulence channel
zero boresight pointing error
non-zero boresight pointing error
average bit-error-rate
ABER
Opis:
In this paper, the influence of a zero and a non-zero boresight pointing errors on the performances of free-space optic transmission over the Málaga atmospheric turbulence channel is considered. Closed form expressions for a zero boresight channel model probability density function, non-zero boresight channel model probability density function, as well as a bit-error rate over a binary phase shift keying modulation transmission are provided. Numerical results for zero and non-zero boresight pointing errors are graphically presented.
Źródło:
Optica Applicata; 2018, 48, 2; 179-189
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on self-repairing and non-diffraction of Airy beams in slant atmospheric turbulence
Autorzy:
Li, Y.-Q.
Wang, L.-G.
Powiązania:
https://bibliotekanauki.pl/articles/174867.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
atmospheric turbulence
Airy beam
self-repairing
non-diffraction
numerical simulation
Opis:
The Airy beams propagation in atmospheric turbulence along a slant path was simulated numerically, based on the split-step Fourier method. Also, the self-repairing and non-diffraction characteristics of Airy beams were investigated and compared with beams propagation on a horizontal path. The effects of parameters including zenith angle, propagation distance, radii of Gaussian aperture and turbulence intensity on the two characteristics of beams were revealed. Additionally, the two characteristics of the Airy beam were compared with those of a Bessel–Gauss beam. The results showed that the two beams obscured by Gaussian apertures can be repaired after propagating some distance along a slant path. However, the non-diffraction characteristic of an Airy beam was stronger than that of a Bessel–Gauss beam and the amplitude attenuation rate of the Bessel–Gauss beam was greater than that of the Airy beam in the process of self-repairing. Results obtained can provide a theoretical basis for an outdoor experiment as well as theoretical guidance for various practical applications including laser communications, laser warning systems, and remote sensing.
Źródło:
Optica Applicata; 2018, 48, 3; 435-447
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Atmospheric Turbulence on the Striking Accuracy of Guided Bombs
Wpływ parametrów atmosfery na dokładność trafienia bomby w cel
Autorzy:
Grajewski, Krzysztof
Kowaleczko, Grzegorz
Pietraszek, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/403464.pdf
Data publikacji:
2020
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
guided bomb
numerical simulation
atmospheric turbulence
bomba korygowana
symulacja numeryczna
turbulencja atmosfery
Opis:
This paper presents the test results of a simulation of an air-to-surface guided bomb drop in a turbulent atmosphere. The guided bomb was developed from a practice bomb built and upgraded by the Air Force Institute of Technology. The paper presents the test results of a numerical simulation of an air-to-surface guided bomb drop ran in a proprietary software environment. The numerical simulation inputs included aerodynamic characteristics calculated with PRODAS software and verified by wind tunnel tests. The stochastic components of atmospheric turbulence were simulated with a stochastic process model proposed by Shinozuki. Examples of the guided bomb drop simulation results are given in the paper. The effect of atmospheric turbulence parameters, i.e. standard deviation, σ and turbulence scale, Lw on the striking accuracy and ground impact scatter, are also shown.
W artykule przedstawiono wyniki przeprowadzonych symulacji zrzutu bomby w turbulentnej atmosferze. Bomba ta powstała na bazie bomby ćwiczebnej zbudowanej i zmodernizowanej w Instytucie Technicznym Wojsk Lotniczych. W artykule przedstawiono wyniki numerycznej symulacji z wykorzystaniem autorskiego oprogramowania. W obliczeniach użyto charakterystyki aerodynamiczne wyliczone programem PRODAS, które weryfikowano badaniami w tunelu aerodynamicznym. Do opisu składowej turbulencji wykorzystano model procesów stochastycznych zaproponowany przez Shinozukiego. Przedstawiono przykładowe wyniki symulacji zrzutu bomby. Pokazano wpływ parametrów turbulencji atmosfery - odchylenia standardowego i skali turbulencji σ, Lw, na celność i rozrzut.
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2020, 11, 1 (39); 31-48
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spreading properties of a multi-Gaussian Schell-model vortex beam in slanted atmospheric turbulence
Autorzy:
Chang, Shuai
Song, Yansong
Dong, Yan
Dong, Keyan
Powiązania:
https://bibliotekanauki.pl/articles/174088.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
average intensity
vortex beam
multi-Gaussian Schell-model source
atmospheric turbulence
slanted path
Opis:
The cross-spectral density function of a multi-Gaussian Schell-model vortex (MGSMV) beam propagating through slanted atmospheric turbulence was derived, and the influences of the MGSMV beam parameter and slanted atmospheric turbulence on the spreading properties of a MGSMV beam are studied. One can find that a MGSMV beam propagating in slanted atmospheric turbulence can evolve into the flat-topped beam, and a MGSMV beam with larger index N and topological charge M propagating in slanted atmospheric turbulence will lose the dark hollow center and evolve into the Gaussian beam more slowly than the MGSMV beam with smaller index N and topological charge M. It is also found that a MGSMV beam propagating in slanted atmospheric turbulence with larger strucutre parameter C will evolve into Gaussian beam faster, but the influences of zenith angle α on the spreading properties of MGSMV beam in the far field can be ignored.
Źródło:
Optica Applicata; 2020, 50, 1; 83-94
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
FSO system performance analysis based on novel Gamma–Chi-square irradiance PDF model
Autorzy:
Todorović, Jelena
Spalević, Petar
Panić, Stefan
Milosavljević, Bojana
Gligorijević, Milan
Powiązania:
https://bibliotekanauki.pl/articles/2033970.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
free space optics
FSO
Gamma-Chi-square distribution
atmospheric turbulence
pointing error
on-off keying
OOK
Opis:
In order to provide a novel analytically traceable free space optics (FSO) channel model for describing turbulence based irradiance fluctuations, following basic scintillation theory principles, we have derived closed-form expression for probability density function (PDF) of a new statistical Gamma–Chi-square model. Further, capitalizing on provided model, error performances of FSO system over on-off keying (OOK) transmission scheme both in the presence of atmospheric turbulence and misalignment fading (pointing error) is investigated. For both cases, the average bit error rate (ABER) at the receiving side of the system is determined in an analytically closed form. The results are graphically presented in order to analyze the impact of different levels of turbulence, as well as other relevant parameters, on the quality of the received signal in the OOK modulated FSO system.
Źródło:
Optica Applicata; 2021, 51, 3; 335-348
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the propagation of laser beams array with coherent and incoherent combination in dynamic atmosphere turbulence
Autorzy:
Deng, Wantao
Wang, Chengcheng
Gan, Chunquan
Xue, Liangping
Xia, Huijun
Wang, Peng
Yang, Huan
Powiązania:
https://bibliotekanauki.pl/articles/2086761.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
laser propagation
dynamic atmospheric turbulence
coherent combination
incoherent combination
beam quality
Opis:
High-power laser systems mostly use coherent or incoherent combined beams to achieve higher laser output power to satisfy the application. However, the far-field beam quality of laser will be reduced when propagating over atmosphere. Based on the propagation model of laser beams array, we use atmospheric coherence length, laser duration and average wind velocity to construct dynamic atmospheric turbulence which is characterized as a phase screen sequence. Meanwhile, considered as the indexes to evaluate beam quality, peak intensity and intensity in bucket are comparatively analysed in coherent and incoherent combined beams in far-field. The results indicate that in weaker turbulence circumstances, coherent combined beam has an advantage compared with the incoherent combined beams when laser duration is short, and coherent combination is more suitable for pulsed laser. With laser duration is increasing, the beam quality of incoherent and coherent combined beams both decrease and tend to be close. In stronger turbulence circumstances, the corresponding laser duration will be shorter when the beam quality of coherent combined beams is extraordinary close to that of incoherent combined beams. The researches can provide important data for high-power laser system to select the optimal beam combination mode to improve its performance.
Źródło:
Optica Applicata; 2022, 52, 2; 243--257
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
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