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Regular version of the site
Of all publications in the section: 259
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Article
Ryzhikov A., Ustyuzhanin A. Journal of Physics: Conference Series. 2018. Vol. 1085. P. 1-6.

In the research, a new approach for finding rare events in high-energy physics was tested. As an example of physics channel the decay of \tau -> 3 \mu is taken that has been published on Kaggle within LHCb-supported challenge. The training sample consists of simulated signal and real background, so the challenge is to train classifier in such way that it picks up signal/background differences and doesn’t overfits to simulation-specific features. The approach suggested is based on cross-domain adaptation using neural networks with gradient reversal. The network architecture is a dense multi-branch structure. One branch is responsible for signal/background discrimination, the second branch helps to avoid overfitting on Monte-Carlo training dataset. The tests showed that this architecture is a robust a mechanism for choosing tradeoff between discrimination power and overfitting, moreover, it also improves the quality of the baseline prediction. Thus, this approach allowed us to train deep learning models without reducing the quality, which allow us to distinguish physical parameters, but do not allow us to distinguish simulated events from real ones. The third network branch helps to eliminate the correlation between classifier predictions and reconstructed mass of the decay, thereby making such approach highly viable for great variety of physics searches.

Added: Dec 11, 2017
Article
Norman G., Timofeev A. Journal of Physics: Conference Series. 2016. Vol. 774. No. 012170. P. 1-8.

The self-consistency and basic openness of dusty plasma, charge fluctuations, high dissipation and other features of dusty plasma system lead to the appearance of a number of unusual and unique properties of dusty plasma. “Anomalous” heating of dusty particles, anisotropy of temperatures and other features, parametric resonance, charge fluctuations and interaction potential are among these unique properties. Study is based on analytical approach and numerical simulation. Mechanisms of “anomalous” heating and energy transfer are proposed. Influence of charge fluctuations on the system properties is discussed. The self-consistent, many-particle, fluctuation and anisotropic interparticle interaction potential is studied for a significant range of gas temperature. These properties are interconnected and necessary for a full description of dusty plasmas physics.

Added: Feb 17, 2017
Article
Popel S I, Golub’ A. P., Zakharov A. V. et al. Journal of Physics: Conference Series. 2019. Vol. 1147. P. 1-11.

Dusty plasmas are shown to be formed in a surface layer over the illuminated part of Martian satellites Phobos and Deimos owing to photoelectric and electrostatic processes. The distribution functions of photoelectrons near surfaces of the satellites, altitude dependences of the density of dust particles, and their charges and sizes, as well as electric fields, have been determined within a physical-mathematical model for the self-consistent description of densities of photoelectrons and dust particles over the surface of the illuminated parts of Phobos and Deimos. In view of a weak gravitational field, dust particles rising over the surfaces of Phobos and Deimos are larger than those over the surface of the Moon. In this case, the role of adhesion, which is a significant process preventing the separation of dust particles from the lunar surface, is much smaller on Phobos and Deimos.

Added: Jan 21, 2019
Article
Popel S.I., Golub' A. P., Zelenyi L.M. et al. Journal of Physics: Conference Series. 2018. Vol. 946. P. 012142-1-012142-9.

A possibility of the formation in the lunar exosphere of dust cloud due to meteoroid impacts onto the lunar surface is studied. The main attention is paid to the high altitudes over the lunar surface including the range of the altitudes between 30 and 110 km where the measurements of dust were performed within the NASA LADEE mission. From the viewpoint of the formation of dust cloud at high altitudes over the Moon, the most important zone formed by the meteoroid impact is the zone of melting of substance. Only the droplets originated from this zone have the speeds between the first and second astronautical velocities (for the Moon). Correspondingly, only such droplets can perform finite movement around the Moon. The liquid droplets harden when rising over the lunar surface. Furthermore, they aquire electric charges due to the action, in particular, of the solar wind electrons and ions, as well as of the solar radiation. Thus dusty plasmas exist in the lunar exosphere with the characteristic number density $\lesssim 10^{-2}$~m$^{-3}$ of dust particles with the sizes from 300~nm to 1~${\rm\mu}$m which is in accordance with the results of measurements performed by LADEE.

Added: May 20, 2018
Article
Medvedev T. V., Medvedev V., Zhuzhoma E. V. Journal of Physics: Conference Series. 2018. Vol. 990. P. 1-9.

We suggest a new model of the fast nondissipative kinematic dynamo which describes the phenomenon of exponential growth of the magnetic eld caused by the motion of the conducting medium. This phenomenon is known to occur in the evolution of magnetic elds of astrophysical bodies. In the 1970s A.D. Sakharov and Ya.B. Zeldovich proposed a \rope" scheme of this process which in terms of the modern theory of dynamical systems can be described as Smale solenoid. The main disadvantage of this scheme is that it is non-conservative. Our model is a modi cation of the Sakharov-Zeldovich's model. We apply methods of the theory of dynamical systems to prove that it is free of this fault in the neighborhood of the nonwandering set.

Added: Apr 5, 2018
Article
Komrakova S., Kovalyuk V., An P. et al. Journal of Physics: Conference Series. 2020. Vol. 1695.

In this paper, we demonstrate the results of a study of the optical absorption properties of graphene integrated with silicon nitride O-ring resonator. We fabricated an array of O-ring resonators with different graphene coverage area atop. By measuring the transmission spectra of nanophotonic devices with and without graphene, we calculated the effective absorption coefficient of the graphene on a rib silicon nitride waveguide.

Added: Apr 28, 2021
Article
Бобров М., Blokhin S., Малеев Н. et al. Journal of Physics: Conference Series. 2019. Vol. 1400. No. 7. P. 077014.

Miniature laser source based on intracavity-contacted vertical-cavity surface-emitting laser with rhomboidal oxide current aperture was investigated for coherent population trapping (CPT) resonance excitation in microfabricated 133Cs gas cell filled with Ne buffer gas under the pressure of 300 torr. The cell operation temperature was 90°C. The laser output power was 550 μW at bias current of 3.2 mA and 65°C. The short-term stability of ~2.5•10-11 at the measurement time of 1 sec was estimated from CPT resonance signal measurements.

Added: Dec 9, 2020
Article
Vlasenko V., Pervakov K., Pudalov V. et al. Journal of Physics: Conference Series. 2014. Vol. 507. No. 1. P. 022044-1-022044-4.

We report on successful fabrication of superconducting FeSe wire using hot gas extrusion (HGE) ex-situ PIT (powder in tube) method. Length of the obtained wire was about 60cm with cross-sectional superconducting core area nearly 2.5x 10^-3 cm^2. For the wire sample we observed superconducting transition temperature, T_onset =  11 K, about 1.2K lower compared to the preliminary prepared FeSe powder. Heat treatment in argon atmosphere at 350C resulted in transition width decrease from \Delta T(10% - 90%) = 1.75K in sample without heat treatment down to \Delta T = 0.9 K in annealed samples. Estimated derivative of the upper critical eld as a function of temperature of the sample annealed during 72h in argon atmosphere at 350C is dHc2/dT =2.9 T/K. Applying WHH theory to our data allows to defi ne Hc2(0K) = 0.69Tc x(dHc2/dT )=  19.8T. The untreated wire shows critical current density, Jc = 75 A/cm2 at T=4.0 K in zero fi eld. Increasing annealing time up to 72 hours at 350C in argon atmosphere gives rise to Jc increase of about 60% approaching 120 A/cm2 at T=4.0K and H=0T . Also Jc measurements were made in magnetic fields up to 9T. Our results show applicability of the HGE PIT method for fabrication of superconducting wires based on FeSe compound. Long-range heat treatment is necessary to improve superconducting properties of the samples.

Added: Mar 19, 2016
Article
Lankin A., Orekhov M. Journal of Physics: Conference Series. 2016. Vol. 774. P. 1-8.
Added: Apr 5, 2017
Article
Kuzin A., Kovalyuk V., Golikov A. et al. Journal of Physics: Conference Series. 2019. Vol. 1410. P. 1-5.

Here we experimentally studied dependence of a focusing grating coupler efficiency versus taper length and angle on silicon nitride platform. As a result, we obtained a dependence for the efficiency of a focusing grating coupler on the parameters of the taper length and angle.

Added: Dec 20, 2019
Article
Izvekova Y. N., Popel S. I. Journal of Physics: Conference Series. 2020. Vol. 1556. P. 012071.

We study dust vortices called dust devils and dynamics of dust in this structures. Dust devils are well formed relatively short-lived vortices that can appear over well heated surfaces like deserts and are clearly visible due to large amount of dust raised. Dust particles rotating in a flow bump and scrape each other and as a result particles obtain electric charges. Space separation of particles with opposite charges leads to generation of macroscopic electric field. We simulate dust dynamics with taking into account the electric field of the vortex.

Added: Jul 6, 2020
Article
Belavin V., Ustyuzhanin A. Journal of Physics: Conference Series. 2020. P. 1-7.

In this work, we propose an approach for electromagnetic shower generation on a track level. Currently, Monte Carlo simulation occupies 50-70\% of total computing resources that are used by physicists experiments worldwide. Thus, speedup of the simulation step allows to reduce simulation cost and accelerate synthetic experiments. In this paper, we suggest dividing the problem of shower generation into two separate issues: graph generation and tracks features generation. Both these problems can be efficiently solved with a cascade of deep autoregressive generative network and graph convolution network. The novelty of the proposed approach lies in the Neural networks application to the generation of the complex recursive physical process.

Added: Oct 31, 2019
Article
Smirnov K., Золотов Ф. И., Romanov N. et al. Journal of Physics: Conference Series. 2018. No. 1124. P. 1-6.

The research of ultrathin vanadium nitride (VN) films as a promising candidate for superconducting single-photon detectors (SSPD) is presented. The electron diffusivity measurements are performed for such devices. Devices that were fabricated out from 9.9 nm films had diffusivity coefficient of 0.41 cm2 /s and from 5.4 nm – 0.54 cm2 /s. Obtained values are similar to other typical SSPD materials. The diffusivity that increases along with decreasing of the film thickness is expected to allow fabrication of the devices with improved characteristics. Fabricated VN SSPDs showed prominent single-photon response in the range 0.9-1.55 µm

Added: Dec 27, 2018
Article
Krukov V. A., Suslov N., Markova V. et al. Journal of Physics: Conference Series. 2019. Vol. 1261. P. 1-6.

The energy sector of Russia is one of the most potent in the world - it is the second in extraction of oil and gas, the third for total output of fuel and energy resources. While exporting nearly 45% of its total production of energy resources, Russia produces more energy per capita than most other countries - 5 times higher the global average and 3 times higher than the average level for OECD countries. The energy sector of Siberia represents the crucial part of the country's energy sector. Over decades, the energy resources of the region massively contributed to the Russian federal budget and brought in a major part of hard currency from export trade. In the current conditions of existing geopolitical challenges and expected global demand for energy resources, it is much more of a priority for Russia not to raise the output of fuel and energy resources but to improve the overall quality and reliability of the whole energy supply system, increase the depth of mineral fuel, including solid fuel and waste recycling.

Added: Sep 12, 2019
Article
Timofeev A., Semyonov V. Journal of Physics: Conference Series. 2016. Vol. 774. No. 012171. P. 1-5.

Dust particles under certain conditions can acquire kinetic energy of the order of 10 eV and higher, far above the temperature of gas and temperatures of ions and electrons in the discharge. Such heating can be explained by the energy transfer between degrees of freedom of a dusty plasma system. One of the mechanisms of such energy transfer is based on parametric resonance. A model of dust particles system in gas discharge plasma including fluctuations of dust particles charge and features of near-electrode layer is presented. Molecular dynamics simulation of the dust particles system is performed. Conditions of the resonance occurrence are obtained for a wide range of parameters.

Added: Feb 17, 2017
Article
Zotov L., Bizouard C. Journal of Physics: Conference Series. 2018. Vol. 955. No. 1. P. 1-6.

We study the Chandler wobble (CW) of the pole from 1846 to 2017 extracted by the Panteleev ltering. The CW has period of 433 days, average amplitude of 0.13 milliarcseconds (mas) which is changing, and phase jump by pi in 1930-th. The CW amplitude strongly (almost to zero) decreases in 1930-th and 2010-th with the phase jump in 1930th. The envelope model contains 83- and 42-years quasi-periodicities. We think the rst one can be represented by the 166-years changes of the envelope, crossing zero in 1930th. We reconstruct Chandler input excitation based on the Euler-Liouville equation. Its amplitude has 20-years variations. We explain this based on simple model and prove, that they appear in consequence of 42-years modulation of CW. The excitation ampli es the amplitude of CW for 20 years then damps it for another 20 years. The analysis of the modulated CW signal in a sliding window demonstrates the specific effect, we called the "escargot effect", when instantaneous "virtual" retrograde component appears in the purely prograde (at long-time interval) signal. Chandler excitation envelope shape is similar to this instantaneous retrograde component, which re ects the changes of ellipticity of the approximation ellipse.

Added: Feb 8, 2018
Article
Aleshin S., Glyzin D., Glyzin S. et al. Journal of Physics: Conference Series. 2019. Vol. 1163. P. 012045.

Lyapunov exponents play an important role among the invariant characteristics of dynamical systems. Analysis of the spectrum of Lyapunov exponents is widely used to study the complex dynamics in systems of ordinary differential equations and models that can be reduced to maps. In this paper we consider the question of numerical evaluation of Lyapunov exponents for delay differential equations. We used a new algorithm with FFT, tested it on Hutchinson equation with known Lyapunov exponents spectrum and compared with results of the old algorithm. The so-called quasi-stable behavior is typical for a number of gene networks models and neuronal associations that have been studied recently. The phenomenon of cycle (k-dimensional torus) quasistability in dynamical system is characterized by the fact that some of its multipliers are asymptotically close to the unit circle, and the remaining multipliers are modulo less than one (with the exception of a simple root 1 (k such roots)). In some cases, it is possible to prove the existence and give an asymptotic estimate of the multipliers of considered system by using the large parameter methods. However, if these methods are not applicable, it is necessary to obtain a tool for the numerical estimation of multipliers. Such a tool is provided by algorithms for Lyapunov exponents estimation. Given that the equations with delay are often applied in the models of neural and gene networks, the algorithm for Lyapunov exponents estimation for such systems will be in demand.

Added: Nov 13, 2020
Article
Ustyuzhanin A., Artemov A., Kazeev N. et al. Journal of Physics: Conference Series. 2015. Vol. 664.

LHC experiments generate up to 10^11LHC experiments generate up to 1012 events per year. This paper describes Event Index – an event search system. Event Index’s primary function is quickly selecting subsets of events from a combination of conditions, such as the estimated decay channel or stripping lines output. Event Index is essentially Apache Lucene [1] optimized for read-only indexes distributed over independent shards on independent nodes. events per year. This paper describes Event Index – an event search system. Event Index’s primary function is quickly selecting subsets of events from a combination of conditions, such as the estimated decay channel or stripping lines output. Event Index is essentially Apache Lucene [1] optimized for read-only indexes distributed over independent shards on independent nodes.

Added: Dec 21, 2015
Article
Kazeev N., Ustyuzhanin A., Artemov A. et al. Journal of Physics: Conference Series. 2015. Vol. 664. No. 3. P. 032019-032019.

During LHC Run 1, the LHCb experiment recorded around 1011 collision events. This paper describes Event Index — an event search system. Its primary function is to quickly select subsets of events from a combination of conditions, such as the estimated decay channel or number of hits in a subdetector. Event Index is essentially Apache Lucene [1] optimized for read-only indexes distributed over independent shards on independent nodes.

Added: Oct 24, 2016
Article
Ustyuzhanin A., Babuschkin I. Journal of Physics: Conference Series. 2017. Vol. 898. No. 7. P. 1-8.

© Published under licence by IOP Publishing Ltd. Modern science clearly demands for a higher level of reproducibility and collaboration. To make research fully reproducible one has to take care of several aspects: research protocol description, data access, environment preservation, workflow pipeline, and analysis script preservation. Version control systems like git help with the workflow and analysis scripts part. Virtualization techniques like Docker or Vagrant can help deal with environments. Jupyter notebooks are a powerful platform for conducting research in a collaborative manner. We present project Everware that seamlessly integrates git repository management systems such as Github or Gitlab, Docker and Jupyter helping with a) sharing results of real research and b) boosts education activities. With the help of Everware one can not only share the final artifacts of research but all the depth of the research process. This been shown to be extremely helpful during organization of several data analysis hackathons and machine learning schools. Using Everware participants could start from an existing solution instead of starting from scratch. They could start contributing immediately. Everware allows its users to make use of their own computational resources to run the workflows they are interested in, which leads to higher scalability of the toolkit.

Added: Feb 25, 2018
Article
Bakunina I. A., Abramov-Maximov V., Osharin A. Journal of Physics: Conference Series. 2017. Vol. 798. No. 1. P. 1 -4.

Under this study we considered active region 09415 of the 23-rd cycle of solar activity which was observed with the 2D spatial resolution at three frequencies: 17 and 34 GHz with the Nobeyama Radioheliograph (NoRH) and 17 GHz with the Solar Siberian Radiotelescope (SSRT). We detected rapid development of a compact microwave source above the neutral line of the magnetic field of leading sunspot (NLS-source) few hours before the X-class flare. The position of this source is associated with the place of the maximum of magnetic field gradient at the photosphere. 

Added: May 26, 2017