106 research outputs found

    All-Fiber Thulium-Doped Mode-Locked Lasers Based on the Nonlinear Amplifying Loop Mirror

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    We  report  on  thulium-doped  all-fiber  lasers  based on the nonlinear amplifying loop mirror and mode-locked by both a semiconductor saturable absorber (SESAM) and  single-walled  carbon  nanotubes (SWCNT).  An  intracavity  and  external dispersion management was realized with the aid of a passive germanium-silicate fiber.  SESAM  mode-locked laser  generates  as  short  as  230-fs  pulses with maximum  average  output  power  of  106 mW, corresponding to a 3.7 kW peak power and almost 2 nJ  pulse  energy.  In  contrast  to  SESAM-based laser,  the SWCNT  mode-locked  laser  generates 450-fs  pulses  of  mW-level  average  output power respectively

    Robusna procedura za umetanje vodenog žiga u sliku zasnovana na Hermitovoj projekcijskoj metodi

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    A procedure for combined image watermarking and compression, based on the Hermite projection method is proposed. The Hermite coefficients obtained by using the Hermite expansion are used for watermark embedding. The image can be efficiently reconstructed by using a set of Hermite coefficients that is quite smaller than the number of original ones. Hence, the watermark embedding is actually done in the compressed domain, while maintaining still high image quality (measured by high PSNR). The efficiency of the proposed procedure is proven experimentally, showing high robustness even for very strong standard attacks. Moreover, the method is robust not only to the standard attacks, but to the geometrical attacks, as well. The proposed approach can be suitable for different copyright and ownership protection purposes, especially in real-applications that require image compression, such as multimedia and Internet applications, remote sensing and satellite imaging.U radu je predložena procedura za umetanje vodenog žiga u sliku i kompresiju slike zasnovana na Hermitovoj projekcijskoj metodi. Odgovarajući koeficijenti, dobiveni kao rezultat primjene razvoja slike u red Hermitovih funkcija, korišteni su za umetanje vodenog žiga watermark). S obzirom na to da se slika može efikasno rekonstruirati korištenjem znatno manjeg broja Hermitovih koeficijenata u odnosu na broj originalnih koeficijenata slike, umetanje vodenog žiga zapravo je provedeno u domeni kompresije, uz očuvanje visoke kvalitete slike (velika vrijednost PSNR). Učinkovitost predložene procedure ispitana je eksperimentalno i pokazuje značajnu otpornost na uobičajene napade. Osim uobičajenih, procedura pokazuje robusnost i na geometrijske napade. Predloženi pristup može biti korišten u različitim aplikacijama za zaštitu autorskih prava, naročito u aplikacijama koje ujedno zahtijevaju i kompresiju slike, kao što su multimedijske i internetske aplikacije, daljinsko očitavanje podataka i satelitska snimanja

    Conservative interacting particles system with anomalous rate of ergodicity

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    We analyze certain conservative interacting particle system and establish ergodicity of the system for a family of invariant measures. Furthermore, we show that convergence rate to equilibrium is exponential. This result is of interest because it presents counterexample to the standard assumption of physicists that conservative system implies polynomial rate of convergence.Comment: 16 pages; In the previous version there was a mistake in the proof of uniqueness of weak Leray solution. Uniqueness had been claimed in a space of solutions which was too large (see remark 2.6 for more details). Now the mistake is corrected by introducing a new class of moderate solutions (see definition 2.10) where we have both existence and uniquenes

    Comissioning of the linear accelerator-injector at the TNK facility

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    The industrial storage facility has been developed and manufactured at the Budker INP SB RAS. It contains an 80 MeV electron linear accelerator-injector and two electron storage rings: the lesser 450 MeV booster ring and the main 2.5 GeV storage ring. In 2002, the work on the accelerator assembling was begun. On December, 25 this year the accelerator was started up, and the current at the linear accelerator output was obtained. The linear accelerator schematic together with a description of the 6 meter long accelerating DAW structure which operates at 2.8 GHz, are presented in the paper. The first results of the accelerator start-up are as follows: the accelerated electron current of ~50 mA with the energy of ~55...60 MeV.Технологічний накопичувальний комплекс був спроектований і виготовлений у ІЯФ ім. Г.І. Будкера СВ РАН. Він містить у собі інжектор–лінійний прискорювач електронів з енергією до 80 МеВ і два накопичувачі електронів: малий накопичувач–бустер на енергію 450 МеВ і основний накопичувач на енергію 2.5 ГеВ. Приводяться функціональна схема лінійного прискорювача й опис конструкції прискорюючої структури із шайбами і діафрагмами довжиною 6 м, що працює на частоті 2.8 ГГц.Представлено перші результати запуску прискорювача: отриманий прискорений струм електронів ~50 мА з енергією ~(55...60) МеВ.Технологический накопительный комплекс был спроектирован и изготовлен в ИЯФ им. Г.И. Будкера СО РАН. Он включает в себя инжектор–линейный ускоритель электронов с энергией до 80 МэВ и два накопителя электронов: малый накопитель–бустер на энергию 450 МэВ и основной накопитель на энергию 2.5 ГэВ. Приводятся функциональная схема линейного ускорителя и описание конструкции ускоряющей структуры с шайбами и диафрагмами длиной 6 метров, работающей на частоте 2.8 ГГц. Представлены первые результаты запуска ускорителя: получен ускоренный ток электронов ~50 мA с энергией ~(55...60) МэВ

    Nucleosomes in gene regulation: theoretical approaches

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    This work reviews current theoretical approaches of biophysics and bioinformatics for the description of nucleosome arrangements in chromatin and transcription factor binding to nucleosomal organized DNA. The role of nucleosomes in gene regulation is discussed from molecular-mechanistic and biological point of view. In addition to classical problems of this field, actual questions of epigenetic regulation are discussed. The authors selected for discussion what seem to be the most interesting concepts and hypotheses. Mathematical approaches are described in a simplified language to attract attention to the most important directions of this field

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

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    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

    Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

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    A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

    Method and style of religious and philosophical criticism of vasily rozanov

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    © 2020, Universidad del Zulia. All rights reserved. The appearance of a significant and new figure in criticism cannot be accidental. Criticism as a specific form of activity presupposes an equally special mindset for which somewhat different tasks are important than, for example, for a philosopher, an artist or a scientist. The purpose of the present article is to show how the specific method of working with text and the unique literary style of Rozanov determined his way from philosophy to criticism. Methodological principles and stylistic features are discovered in V. Rozanov’s literary and critical heritage, which later become attribute features of Russian religious and philosophical thought
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