Effects of Sliding Velocity and Thermal Conduction of the Tool on X20Cr4 Steel Friction Coefficient and Structure in Nanostructuring Burnishing

The developmental study has succeeded in finding how the sliding velocity of an indenter affects the friction coefficient and changes the structure and phase state in the surface layer of a X20Cr13 stainless steel when nanostructuring burnishing is done with a tool with no heat removal and, alternatively, when the tool is equipped with a cooling system. It has been shown that structural dispersion of the treated material results in obtaining 20⋯80 nm nanocrystallites if the friction coefficient of the spherical synthetic diamond indenter is within 0.15⋯0.18 nm. Application of a compact cooling system, based on Peltier's thermoelectric module, made it possible to stabilize the friction coefficient at 0.17 and to increase the sliding velocity from 13 m/min, this being the case of no heat removal, to 45 m/min in the case when the cooling system having a cooling performance of 120 W was used. TEM and SEM analyses of the surface layer structure confirmed that there is a correlation between the friction coefficient and the size of nanocrystallites and the thickness of the dispersed layer. EBSD analysis of the structure showed that a maximum permissible sliding velocity can be established as referenced to the nucleation and growth of γ-phase grains in the nanostructured layer caused by heating of the material under deformation and reaching the temperature beyond the point α→γ phase transition as well as by behavior of dynamic recrystallization. It was established that the heat removal ensures suppression of dynamic recrystallization when the sliding velocity is increased up to 50 m/min. © 2018 Published under licence by IOP Publishing Ltd

Noncommutative geometry and stochastic processes

The recent analysis on noncommutative geometry, showing quantization of the volume for the Riemannian manifold entering the geometry, can support a view of quantum mechanics as arising by a stochastic process on it. A class of stochastic processes can be devised, arising as fractional powers of an ordinary Wiener process, that reproduce in a proper way a stochastic process on a noncommutative geometry. These processes are characterized by producing complex values and so, the corresponding Fokker-Planck equation resembles the Schroedinger equation. Indeed, by a direct numerical check, one can recover the kernel of the Schroedinger equation starting by an ordinary Brownian motion. This class of stochastic processes needs a Clifford algebra to exist. In four dimensions, the full set of Dirac matrices is needed and the corresponding stochastic process in a noncommutative geometry is easily recovered as is the Dirac equation in the Klein-Gordon form being it the Fokker--Planck equation of the process.Comment: 16 pages, 2 figures. Updated a reference. A version of this paper will appear in the proceedings of GSI2017, Geometric Science of Information, November 7th to 9th, Paris (France

Random Forest identification of the thin disk, thick disk and halo Gaia-DR2 white dwarf population

Gaia-DR2 has provided an unprecedented number of white dwarf candidates of our Galaxy. In particular, it is estimated that Gaia-DR2 has observed nearly 400,000 of these objects and close to 18,000 up to 100 pc from the Sun. This large quantity of data requires a thorough analysis in order to uncover their main Galactic population properties, in particular the thin and thick disk and halo components. Taking advantage of recent developments in artificial intelligence techniques, we make use of a detailed Random Forest algorithm to analyse an 8-dimensional space (equatorial coordinates, parallax, proper motion components and photometric magnitudes) of accurate data provided by Gaia-DR2 within 100 pc from the Sun. With the aid of a thorough and robust population synthesis code we simulated the different components of the Galactic white dwarf population to optimize the information extracted from the algorithm for disentangling the different population components. The algorithm is first tested in a known simulated sample achieving an accuracy of 85.3%. Our methodology is thoroughly compared to standard methods based on kinematic criteria demonstrating that our algorithm substantially improves previous approaches. Once trained, the algorithm is then applied to the Gaia-DR2 100 pc white dwarf sample, identifying 12,227 thin disk, 1,410 thick disk and 95 halo white dwarf candidates, which represent a proportion of 74:25:1, respectively. Hence, the numerical spatial densities are $(3.6\pm0.4)\times10^{-3}\,{\rm pc^{-3}}$, $(1.2\pm0.4)\times10^{-3}\,{\rm pc^{-3}}$ and $(4.8\pm0.4)\times10^{-5}\,{\rm pc^{-3}}$ for the thin disk, thick disk and halo components, respectively. The populations thus obtained represent the most complete and volume-limited samples to date of the different components of the Galactic white dwarf population.Comment: 18 pages, 11 figures and 3 tables. Accepted for publication in MNRA

On Albanese torsors and the elementary obstruction

We show that the elementary obstruction to the existence of 0-cycles of degree 1 on an arbitrary variety X (over an arbitrary field) can be expressed in terms of the Albanese 1-motives associated with dense open subsets of X. Arithmetic applications are given

Crystal Undulator As A Novel Compact Source Of Radiation

A crystalline undulator (CU) with periodically deformed crystallographic planes is capable of deflecting charged particles with the same strength as an equivalent magnetic field of 1000 T and could provide quite a short period L in the sub-millimeter range. We present an idea for creation of a CU and report its first realization. One face of a silicon crystal was given periodic micro-scratches (grooves), with a period of 1 mm, by means of a diamond blade. The X-ray tests of the crystal deformation have shown that a sinusoidal-like shape of crystalline planes goes through the bulk of the crystal. This opens up the possibility for experiments with high-energy particles channeled in CU, a novel compact source of radiation. The first experiment on photon emission in CU has been started at LNF with 800 MeV positrons aiming to produce 50 keV undulator photons.Comment: Presented at PAC 2003 (Portland, May 12-16

NANOSTRUCTURING OF SURFACE LAYER OF 1.3505 STEEL BY WEDGE CYLINDRICAL TOOL

This paper discusses the issues of normal load during burnishing by a wedge cylindrical tool that influences the hardening of the 1.3505 steel surface according to the criteria of microhardness and thickness of nanostructuring layer. It has been established that burnishing with a normal force of 200 and 250 N provides formation of a nanostructured layer with a 4,3–5,5 µm thickness and a maximum micro-hardness of 1120–1170 HV0,05.В работе рассмотрены вопросы влияния нормальной нагрузки при выглаживании клиновым цилиндрическим инструментом на упрочнение поверхности стали ШХ15 по критериям микротвердости и толщины наноструктурированного слоя. Установлено, что выглаживание с нормальной силой 200 и 250 Н обеспечивает формирование наноструктурированного слоя толщиной 4,3–5,5 мкм с максимальной микротвердостью 1120–1170 HV0,05

Effects of interatomic interaction on cooperative relaxation of two-level atoms

We study effects of direct interatomic interaction on cooperative processes in atom-photon dynamics. Using a model of two-level atoms with Ising-type interaction as an example, it is demonstrated that interparticle interaction combined with atom-field coupling can introduce additional interatomic correlations acting as a phase synchronizing factor. For the case of weakly interacting atoms with $J<\hbar\omega_0$, where $J$ is the interparticle coupling constant and $\omega_0$ is the atomic frequency, dynamical regimes of cooperative relaxation of atoms are analyzed in Born-Markov approximation both numerically and using the mean field approximation. We show that interparticle correlations induced by the direct interaction result in inhibition of incoherent spontaneous decay leading to the regime of collective pulse relaxation which differs from superradiance in nature. For superradiant transition, the synchronizing effect of interatomic interaction is found to manifest itself in enhancement of superradiance. When the interaction is strong and $J>\hbar\omega_0$, one-partice one-photon transitions are excluded and transition to the regime of multiphoton relaxation occurs. Using a simple model of two atoms in a high-Q single mode cavity we show that such transition is accompanied by Rabi oscillations involving many-atom multiphoton states. Dephasing effect of dipole-dipole interaction and solitonic mechanism of relaxation are discussed.Comment: 34 pages, 8 figure

ИСПОЛЬЗОВАНИЕ ФЛУОРИМЕТРИИ В БЛИЖНЕЙ ИК-ОБЛАСТИ С ФОТОГРАФИЧЕСКОЙ РЕГИСТРАЦИЕЙ СИГНАЛА В МЕТОДЕ «ОТПЕЧАТКОВ ПАЛЬЦЕВ» С ДОБАВКОЙ ФЛУОРОФОРА К ОБЪЕКТУ: ДИСКРИМИНАЦИЯ ЯБЛОЧНЫХ СОКОВ

The application of dyes, that fluoresce in the near infrared (NIR, 700-800 nm) region, for the recognition of samples using a fingerprinting method with the addition of fluorophores to the samples (“fluorescent eye”) is proposed. The technique has been successfully applied to the classification of samples of various nature. In the current work, this strategy has been tested on the example of discrimination of 17 samples of apple juice from different manufacturers, purchased at different times. An indolenine series heptamethine carbocyanine dye in the presence of surfactants was used as the added fluorophore, red LEDs were used as an excitation source, and the signal was recorded using a digital camera with an additional IR filter installed; a spectrofluorimeter with a 96-well plate accessory was used to record the spectra. Photographic images were processed using Unscrambler X and Excel software. The results were presented using the following coordinates: intensity of NIR fluorescence - intensity of visible light reflection (using the photographic images). It was found that such presentation allowed the samples to be divided into groups associated with the manufacturer. We have also obtained intrinsic fluorescence spectra, including those with the addition of NIR dye, and these results were processed by the principal component analysis. It was possible to distinguish 5–6 groups of samples by their intrinsic emission, not counting the blank, while the spectra with the addition of the dye allowed to isolate the largest number of groups of samples (9). At the same time, the classification using spectra did not allow juices to be grouped by the producer. Also, obtaining photographs using a visualizer was easier and faster than recording the fluorescence spectra. The joint processing of emission spectra and photographs did not improve the quality of discrimination.Keywords: fingerprinting method, NIR fluorimetry, apple juice, principal component analysisDOI: http://dx.doi.org/10.15826/analitika.2022.26.1.005E.V. Skorobogatov, I.A. Stepanova, V.S. Orekhov, M.K. Beklemishev Department of Chemistry, Lomonosov Moscow State University, Russin Federation, 119991, GSP-1, Moscow, Leninskie gory, 1, building 3Предложено использовать красители, флуоресцирующие в ближней ИК (БИК) области спектра (700–800 нм), для распознавания объектов методом «отпечатков пальцев», основанным на добавке флуорофоров к объекту («флуоресцентный глаз»). Метод успешно применяется в классификации объектов различной природы. В данной работе метод опробован на примере дискриминации 17 образцов яблочного сока разных производителей, выпущенных в разное время. В качестве добавляемого флуорофора использовали гептаметиновый карбоцианиновый краситель индоленинового ряда в присутствии ПАВ, в качестве источника излучения – красные светодиоды, а сигнал регистрировали с помощью цифрового фотоаппарата с дополнительным ИК-светофильтром; для записи спектров применяли спектрофлуориметр с приставкой для 96-луночного флуориметрического планшета. Фотографические изображения обрабатывали с помощью стандартного программного обеспечения Unscrambler X и Excel. Результаты представили в координатах: интенсивность БИК-флуоресценции – интенсивность отражения видимого света (с использованием соответствующих фотографий). Обнаружили, что такое представление позволяет разделить образцы на группы, связанные с производителем. Получали также спектры собственной флуоресценции, в том числе с добавкой БИК-красителя, обрабатывая эти результаты методом главных компонент. По собственной эмиссии можно выделить 5–6 групп образцов, не считая контрольного, тогда как по спектрам с добавкой красителя удается добиться выделения наибольшего числа групп образцов (девять). При этом классификация с использованием спектров не позволяет группировать соки по производителям. Кроме того, получение фотографий с помощью визуализатора проще и экспресснее, чем регистрация спектров флуоресценции. Совместная обработка эмиссионных спектров и фотографий не позволяет повысить качество дискриминации образцов.Ключевые слова: метод «отпечатков пальцев», флуориметрия в ближней ИК-области, яблочный сок, метод главных компонентDOI: http://dx.doi.org/10.15826/analitika.2022.26.1.00