64 research outputs found

    Investigating Properties of Bow-Shock Pulsar Wind Nebulae

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    Рассчитаны модели туманностей быстролетящих пульсаров для скоростей нейтронной звезды 150, 450 и 1500 км/с, а также показателя адиабаты газа в классическом и ультра релятивистском пределах (5/3 и 4/3). Модели учитывают морфологию релятивистских течений газа и его ионизационное состояние. Впервые выполнены не-ЛТР расчет и анализ карт излучения в линии Hα, а также в линиях атомов CI, NI и ионов NII, OII, OIII и NeIV от УФ- до ИК-диапазона. Получены потоки на порядок меньшие, чем в Hα, а при подходящих условиях сравнимые с ней в случае OIII и превосходящие их почти на порядок в случае OII. Рассмотрена морфология туманностей и даны предсказания наблюдательных особенностей.We performed a calculation of bow-shock pulsar wind nebulae models for pulsar velocities of 150, 450 and 1500 km/s and adiabatic index in classical and ultrarelativistic limits. For the first time we calculated and analysed the non-LTE emissivity maps in Hα, spectral lines of CI, NI atoms and NII, OII, OIII, NeIV ions from UV to IR wavelengths. Fluxes of order of magnitude lower than Hα were obtained in most cases, but in favorable conditions were approximately equal to it or even of magnitude higher in some cases. Morphology of nebulae was investigated and predictions of observable features were given.Работа выполнена при поддержке гранта РНФ 23-22-00385. Основные вычисления были выполнены на кластере CfCA Национальной астрономической обсерватории Японии. Авторы выражают благодарность команде PLUTO за возможность использования программного пакета PLUTO

    Photometric calibration of 28-cm telecsope of NCAS KFU by jointly modeling equations of transformations and the extinction

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    Данная работа посвящена нахождению уравнений перехода от фотометрической системы Binstr, Ginstr, Rinstr телескопа ШК-280, установленного на СКАС КФУ, в стандартную BJ , VJ , RC систему Джонсона—Казинса с применением современных численных методов. Были проведены наблюдения стандартов Ландольта поля SA110. Выполнена абсолютная фотометрия избранных звезд, оценена погрешность измерений. Построена модель перехода от заатмосферных звездных величин в стандартной системе к наблюдаемым инструментальным. С помощью метода Монте-Карло с марковскими цепями совместно определены средние за период наблюдений коэффициенты атмосферной экстинкции (0.276, 0.205, 0.159 для Binstr, Ginstr, Rinstr соответственно) и коэффициенты уравнений перехода между системами (цветовые коэффициенты 0.165, −0.120, −0.378 для B0 J , V 0 J , R0C в зависимости от (B −G)0 instr, (G−R)0 instr, (G−R)0 instr соответственно).This work is devoted to study of transformations equations between Binstr, Ginstr, Rinstr photometric system of 28-cm Schmidt-Cassegrain telescope mounted in NCAS KFU to standard Johnson—Cousins BJ , VJ , RC using modern numerical methods. Observations of Landold Standards at the SA110 region were performed. Absolute photometry of selected stars was obtained with estimatiuon of observational errors. To transform the observational data into the standart system numerical model was built with the use of Markov Chain Monte Carlo sampling. So, we found average parameters of transformations between systems (color reduction coefficients are 0.165, −0.120, −0.378 for B0 J , V 0 J , R0C in dependence of (B − G)0 instr, (G − R)0 instr, (G − R)0 instr respectievely) and medium extinction at the observational period (0.276, 0.205, 0.159 for Binstr, Ginstr, Rinstr respectievely)

    Deep learning-based video stream reconstruction in mass-production diffractive optical systems

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    Возможность существенно снизить массу и стоимость систем технического зрения привела к появлению большого числа работ, посвященных разработке новых оптических схем на основе дифракционной оптики и новых подходов к реконструкции получаемых изображений. Получаемые системы демонстрируют достаточное для прикладных систем технического зрения качество изображений. Однако при создании таких прикладных систем возможны источники дополнительных потерь качества получаемого видеопотока. В настоящей работе исследовано влияние на итоговое качество реконструируемого видеопотока таких факторов, как ограничения технологии массового производства дифракционной оптики, артефактов сжатия видеопотока с потерями, а также особенностей нейросетевого подхода к реконструкции. Предложена сквозная нейросетевая технология реконструкции изображений, позволяющая компенсировать дополнительные факторы потери качества и получить итоговый видеопоток с качеством, достаточным для решения прикладных задач технического зрения. Many recent studies have focused on developing image reconstruction algorithms in optical systems based on flat optics. These studies demonstrate the feasibility of applying a combination of flat optics and the reconstruction algorithms in real vision systems. However, additional causes of quality loss have been encountered in the development of such systems. This study investigates the influence on the reconstructed image quality of such factors as limitations of mass production technology for diffractive optics, lossy video stream compression artifacts, and specificities of a neural network approach to image reconstruction. The paper offers an end-to-end deep learning-based image reconstruction framework to compensate for the additional factors of quality losing. It provides the image reconstruction quality sufficient for applied vision systems.Теоретическая часть работы и разработка нейросетевых моделей выполнена при поддержке гранта РНФ 20-69-47110, экспериментальная часть выполнена при поддержке грантов РФФИ № 18-07-01390-А, а также в рамках государственного задания ИСОИ РАН – филиала Федерального научно-исследовательского центра «Кристаллография и фотоника» РАН (соглашение № 007-ГЗ/Ч3363/26)

    PHOTO DESTRUCTION OF SILVER NANOPARTICLES IN PHOTO-THERMO-REFRACTIVE GLASS

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    Silver nanoparticles destruction process in photo-thermo-refractive glass under nanosecond pulsed laser irradiation (532nm) depending on exposure dose is investigated. It is shown that photo fragmentation of silver nanoparticles and formation of silver clusters as well as the photoionization of silver neutral atoms with their transition into ion state takes place under laser radiation

    FORMATION OF LUMINESCENT OPTICAL WAVEGUIDES IN SILICATE GLASS MATRIX BY THE ION-EXCHANGE TECHNIQUE

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    We present spectra of the alkali-silicate glasses with copper ions in near-surface area, introduced by ion exchange of different temperature and duration. It is shown that the reduction of Cu2+ in the near-surface area causes existence of Cu+ and neutral atoms in glass after the ion-exchange in divalent salt. The ion-exchange itself involves only Cu+ and Na+ ions. The formation of subnanometer clusters Cun is due to neutral copper atoms staying in near-surface zone. We have shown that the waveguide layer in near-surface area, made by ion-exchange, has а visible luminescence with the excitation by UVradiation. At the same time, the contribution to luminescence is made by Cu+ ions, molecular clusters Cun and by dimers Cu+ - Cu+ . During the high-temperature ion-exchange at 600 °С the formation and destruction equilibrium shift of molecular clusters Cun can be seen. An hour ion-exchange leads to molecular clusters Cun destruction, while at time periods less than 30 min and around 18 hours it leads to the formation of Cun. The sample turns green after 18,5 hours ion-exchange showing formation of a considerable amount of divalent copper ions Cu2+ therein

    FEATURES OF MULTIPLEXED HOLOGRAMS RECORDING IN PHOTO-THERMO-REFRACTIVE GLASS

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    We have carried out calculations of recording conditions for multiplexed holograms in photo-thermo-refractive (PTR) glass. The proposed calculation sets the link between such parameters as: the angle between recording beams and the angle of sample rotation, operating wavelength, the angle of incidence on the element, output angle. To study recording features of multiplexed holograms on PTR glass several elements was made. Six holograms in each element were recorded with various exposures. All samples were heat-treated at one temperature around glass transition temperature. It has been demonstrated that at the recording of several gratings with a total exposure exceeding an optimal value for a given material, the total value of the refractive index modulation amplitude (n1) reaches the maximum attainable magnitude that is equivalent to a value of a single hologram with optimal exposure. It has been found that refractive index dynamic range of the material distributes between the gratings in accordance with the ratio between exposure times if holograms exposures have significant differences. In the present paper six-channel multiplexer was recorded for a wavelength equal to 632.8 nm (He-Ne laser). The diffraction angles correspond to calculations mentioned above. The n1 value in each grating is equal to the value of the highest attainable value of the value of n1 divided by the total number of multiplexed holograms

    IDENTIFICATION OF LUMINESCENT CENTRES IN GLASS WITH COPPER AND CHLORINE IONS

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    Research results of luminescent and excitation spectra of potassium-alumina-borate glass with copper and chlorine ions luminescence are submitted. It is shown, that before the heat treatment glass luminescence is connected with molecular clusters Cun (n < 10). The broadband luminescence in the visible spectral region, appearing after the heat treatment, is due to the appearance of (CuCl)n and (Cu2O)n molecular clusters in glass matrix
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