bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors influencing the development of violent pyroconvection. Part I: fire size and stability
Authors: Badlan Rachel L. , Sharples Jason J. , Evans Jason P. , McRae Rick H. D.
Published: May 2021

Violent fire-driven convection can manifest as towering pyrocumulus (pyroCu) or pyrocumulonimbus (pyroCb) clouds, which can have devastating impacts on the environment and society. Their associated fire spread is erratic, unpredictable and not generally suppressible. Research into large pyroconvective events has mainly focused on the atmospheric processes involved in normal atmospheric convection, or on surface fire weather and associated fuel conditions. There has been comparatively less attention paid to the role of the fire itself in these coupled fire–atmosphere events. This paper draws on recent insights into dynamic fire propagation and extreme wildfire development to investigate how the fire influences the occurrence of violent pyroconvective events. A static heat source of variable dimension and intensity is used. This is accompanied by a companion paper that extends the analysis by including the effect of fire geometry on the pyroconvective plume. The analyses indicate that the spatial expanse and intensity of large fires are critical factors driving the development of pyroconvective plumes and can override the influence of the stability of the atmosphere. These findings provide motivation for further investigation into the effect of the fire’s attributes on the immediate atmosphere and have the potential to improve forecasting of blow-up fire events.
Evolutionary design of magnetic soft continuum robots
Authors: Wang Liu , Zheng Dongchang , Harker Pablo , Patel Aman B. , Guo Chuan Fei , Zhao Xuanhe
Published: May 2021

Significance

Magnetic soft continuum robots (MSCRs) capable of magnetic field–controllable steering offer great promise for the endovascular treatment of cardiovascular diseases. However, existing MSCRs are often limited to small workspaces because of the lack of efficient design and optimization tools. In this work, we introduce an evolutionary design strategy by integrating theoretical modeling and the genetic algorithm. Enabled by this strategy, the proposed MSCR achieves an optimal workspace much larger than those of the state-of-the-art MSCRs. The proposed design strategy also offers a potent tool for efficient design and optimization of future magnetic soft robots and actuators.
Pharmacological inhibition of MDA-9/Syntenin blocks breast cancer metastasis through suppression of IL-1β
Authors: Pradhan Anjan K. , Maji Santanu , Bhoopathi Praveen , Talukdar Sarmistha , Mannangatti Padmanabhan , Guo Chunqing , Wang Xiang-Yang , Cartagena Lorraine Colon , Idowu Michael , Landry Joseph W. , Sarkar Devanand , Emdad Luni , Cavenee Webster K. , Das Swadesh K. , Fisher Paul B.
Published: May 2021

Significance

Metastasis is a leading cause of breast cancer-associated death. MDA-9/Syntenin expression is elevated and contributes at multiple nodal points in the metastatic process. Inhibition of MDA-9/Syntenin using a pharmacological inhibitor (PDZ1i), which blocks protein–protein interactions, suppresses metastasis in syngeneic mouse and human xenograft models. PDZ1i therapy robustly constrains breast cancer metastasis in syngeneic animals by inhibiting tumor cell-derived interleukin-1β secretion through deactivation of STAT3 and reducing infiltration of immune suppressor cells in the metastatic niche. Enhanced antitumor immunity correlates with expansion of interferon-γ–expressing T cells and conversion of the immunosuppressive microenvironment into an immunostimulatory tumor environment. Collectively, our findings highlight the essential function of MDA-9/Syntenin in immune tolerance, documenting a promising therapeutic strategy selectively targeting breast cancer metastasis.
Testing hilltop supernatural inflation with gravitational waves
Authors: Lin Chia-Min
Published: May 2021

The scale of small-field inflation cannot be constrained via primordial gravitational waves through measurement of tensor-to-scalar ratio r.
In this study, I show that if cosmic strings are produced after symmetry breaking at the end of hilltop supernatural inflation, this small-field inflation model can be tested through the production of gravitational waves from cosmic strings. Future experiments of gravitational wave detectors will determine or further constrain the parameter space in the model.
Comparative study of spark pin-array and printed circuit board surface plasma pre-ionization systems for transversely excited atmospheric CO2 laser performance
Authors: Torabi Reza , Silakhori Kaveh , Nejhad Hamid Salmani
Published: May 2021

The performance of a homemade transversely excited atmospheric CO2 laser, capable to be alternatively run using UV spark pin-array (SPA) and printed circuit board (PCB) surface plasma pre-ionization systems, is comparatively studied. The pin-array configuration is comprised of two rows of 5 mm spark gaps symmetrically located on either side of the discharge volume. The surface plasma pre-ionization system consists of a PCB of which, one side is patterned with isolated millimeter size circular pieces. The performance of both types of pre-ionization in different working conditions was experimentally investigated and the output energies were compared with each other as well as the simulation results based on the six-temperature vibrational-rotational model. It has been found that the SPA system provides better discharge stability and uniformity with higher output energies, while using the PCB surface plasma configuration allowed the laser to operate with higher gas lifetime and lowered the need for helium in its gas mixture.
Simultaneous cooling of double oscillators in an optomechanical system with an optical parametric amplifier
Authors: Yang Hao-Tian , Yuan Zhong-Hui , Zhu Ai-Dong
Published: May 2021

Quantum manipulation of mechanical oscillators has important applications in fundamental physics and quantum information processing. Ground-state cooling of the mechanical oscillators is the prerequisite for these applications. In this paper, we propose a scheme for cooling double mechanical oscillators simultaneously, in which the parametric processes induced by a degenerate optical parameter amplifier (OPA) change the statistical properties of the cavity field, resulting in the lower average phonon numbers. However, it is worth noting that two mechanical modes with the same frequency cannot be cooled due to destructive interference between the two cooling processes. While two mechanical oscillators with different frequencies can be simultaneously cooled to near their ground-state, and the cooling efficiency can be improved by increasing the parametric gain of OPA.
Ohmic and Schottky contacts of hydrogenated and oxygenated boron-doped single-crystal diamond with hill-like polycrystalline grains*
Authors: Wang Jing-Cheng , Chen Hao , Wan Lin-Feng , Mu Cao-Yuan , Liu Yao-Feng , Cheng Shao-Heng , Wang Qi-Liang , Li Liu-An , Li Hong-Dong
Published: May 2021

Hill-like polycrystalline diamond grains (HPDGs) randomly emerged on a heavy boron-doped p+ single-crystal diamond (SCD) film by prolonging the growth duration of the chemical vapor deposition process. The Raman spectral results confirm that a relatively higher boron concentration (∼ 1.1 × 1021 cm−3) is detected on the HPDG with respect to the SCD region (∼ 5.4 × 1020 cm−3). It demonstrates that the Au/SCD interface can be modulated from ohmic to Schottky contact by varying the surface from hydrogen to oxygen termination. The current–voltage curve between two HPDGs is nearly linear with either oxygen or hydrogen termination, which means that the HPDGs provide a leakage path to form an ohmic contact. There are obvious rectification characteristics between oxygen-terminated HPDGs and SCD based on the difference in boron doping levels in those regions. The results reveal that the highly boron-doped HPDGs grown in SCD can be adopted as ohmic electrodes for Hall measurement and electronic devices.
Removal of GaN film over AlGaN with inductively coupled BCl3/Ar atomic layer etch
Authors: Tang Jia-Le , Liu Chao
Published: May 2021

Atomic layer etching (ALE) of thin film GaN (0001) is reported in detail using sequential surface modification by BCl3 adsorption and removal of the modified surface layer by low energy Ar plasma exposure in a reactive ion etching system. The estimated etching rate of GaN is ∼ 0.74 nm/cycle. The GaN is removed from the surface of AlGaN after 135 cycles. To study the mechanism of the etching, the detailed characterization and analyses are carried out, including scanning electron microscope (SEM), x-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM). It is found that in the presence of GaCl
x
after surface modification by BCl3, the GaCl
x
disappears after having exposed to low energy Ar plasma, which effectively exhibits the mechanism of atomic layer etch. This technique enables a uniform and reproducible fabrication process for enhancement-mode high electron mobility transistors with a p-GaN gate.
A Bayesian-based approach for extracting the pion charge radius from electron-electron scattering data
Authors: Hidayat Alam A , Pardamean Bens
Published: May 2021

In this study, we utilize a potentially versatile Bayesian parameter approach to compute the value of the pion charge radius and quantify its uncertainty from several experimental

datasets for the pion vector form factor. We employ dispersion relations to model the pion vector form factor to extract the radius. Nested model selection is used to determine the order of polynomial appearing in the form factor formulation that can be supported by the data, adapting the computation of Bayes evidence and Bayesian effective complexity based on Occam's razor. Our findings indicate that five out of six used datasets favor the nine-parameter model for radius extraction, and accordingly, we average the radii from the datasets. Despite some inconsistencies with the most updated radius values, our approach may serve as a more intuitive method of addressing parameter estimations in dispersion theory.
HI detection of J030417.78+002827.4 by the Five-hundred-meter Aperture Spherical Radio Telescope
Authors: Yu Nai-Ping , Qian Lei , Zhang Chuan-Peng , Jiang Peng , Xu Jin-Long , Wang Jun-Jie
Published: May 2021

We present the first HI 21 cm spectroscopy detection of J030417.78+002827.4, which is an active galactic nucleus (AGN) with an intermediate-mass black hole (IMBH) in the center. The observations were carried out with the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) last year. We relied on the ON-OFF observing approach with the 19-beam receiver covering 1.05 – 1.45 GHz. Within a total integration time of about 20 min, the root mean square (RMS) of our data reaches 1.2 mJy beam−1, at a velocity resolution of 1.6 kms. Radio frequency interference (RFI) is checked and excluded during the data analysis. The detected HI spectroscopy shows a dual-horned profile with a line width of 223.5 kms, indicating gas rotation around this AGN. The redshift of this galaxy derived from our HI observation is 0.0447. We calculate the atomic gas mass by the integrated flux of the HI emission line. The total gas mass in this galaxy is estimated to be 1.8 × 1010
M
⊙. We find the fraction of gas-to-stellar mass ratio in J030417.78+002827.4 is more than 50%. This ratio is much higher than the typical value found in other AGNs with supermassive black holes (SMBHs), and is comparable to some star-forming galaxies recently observed by FAST.
Optical monitoring and IDV analysis of the blazars S5 0716+714 and 3C 273
Authors: Liu Xiao-Lan , Yuan Yu-Hai , Huang Hong-Ren
Published: May 2021

S5 0716+714 and 3C 273 are frequently studied blazars, which show obvious optical variabilities with different timescales. Using the 1.0 m telescope at the Yunnan Observatory, we monitored the two sources. For S5 0716+714, we report 990 observations during the monitoring duration from JD 2458536 to JD 2458540. For 3C 273, there are 884 observations during the monitoring duration from JD 2458539 to JD 2458542. Based on those observations, we obtain the following results. (1) For S5 0716+714, there lie intra-day optical variabilities (IDVs), with timescales from 0.31 hours to 2.64 hours. For 3C 273, it is possible that there lie IDVs, with timescales from 0.36 hours to 0.49 hours. (2) The time delay of S5 0716+714 is τRI
= 3.46 min between R and I bands, and the time delay of 3C273 is τIV
= 6.42 min between I and V bands. (3) We find that, for S5 0716+714, there lies a suspected intra-day period, P ≈ 185.78 min; for 3C 273, there lie intra-day periods, which are about ∼60 min and ∼80 min.
An explanation about the flat radio spectrum for Mrk 421
Authors: Xue Rui , Wang Ze-Rui
Published: May 2021

It is well known that a flat radio spectrum is a common property in the spectral energy distribution of blazars. Although one-zone leptonic models are generally successful in explaining the multi-wave band emission, they are problematic in reproducing the radio spectrum. In the study of Mrk 421, one-zone models suggest that in order to avoid overproducing the radio flux, the minimum electron Lorentz factor should be larger than a few hundred at least, even considering the synchrotron self-absorption effect. This result suggests that the model predicted spectral index in the radio band of Mrk 421 should be -1/3. On the basis of this result, by assuming there is a neglected region that will also contribute the radio emission and its electron energy index naturally originates from the simplest first-order Fermi acceleration mechanism, we can get a superimposed flat radio spectrum. In this paper, a two-zone model is proposed to reproduce the quiescent state spectral energy distribution of Mrk 421. In addition to taking into account the emission from a conventional radiation zone, we further consider emission from the acceleration zone in which particles are accelerated at a shock front. With the present model, our fitting result suggests that the low frequency flat radio spectrum of Mrk 421 might be explained as a superposition of the synchrotron emission from acceleration zone and radiation zone.
Solar radio filtering algorithm based on improved long short-term memory
Authors: Du Qing-Fu , Zhang Qiao-Man , Li Xin , Gao Chang-Lin
Published: May 2021

The effective observation of burst events in solar radio research has been impeded by various interference signals, especially interference signals with a wide frequency range and high intensity, as they can partially or completely obscure the observation of burst events. Image processing methods that directly remove the interference signal channels and subtract the average of the interference signal channel are not suitable for processing all types of interference signals. This paper proposes the use of a specific kind of recurrent neural networks, called long short-term memory networks, to predict the value of the radio frequency interference signals with high intensity of the burst event in the solar radio spectrum. The predicted interference can then be removed in accordance with the principle that signals can be linearly added. Therefore, predicted value is subtracted from the data containing the burst event signals and the RFI signals (The radio frequency interference signals to be processed in this article refer to the signal of the broadcast signal that can be received in the frequency range, the signal transmitted by the mobile phone, and the signal transmitted by the sea vessel, and the like) to remove the interference. Then, in order to reduce the error caused by the stepwise prediction in the network and further improve the prediction accuracy, this paper analyzes the characteristics of the value of the radio interference and applies the digital mapping method to convert the prediction problem into the classification problem in the time series. The experimental results show that the proposed method can effectively remove the radio interference in the solar spectrum and clearly show the burst events.
The estimate of sensitivity for large infrared telescopes based on measured sky brightness and atmospheric extinction
Authors: Zhao Zhi-Jun , Zhou Hai-Jing , Zhang Yu-Chen , Ling Yun , Xu Fang-Yu
Published: May 2021

In order to evaluate the ground-based infrared telescope sensitivity affected by the noise from the atmosphere, instruments and detectors, we construct a sensitivity model that can calculate limiting magnitudes and signal-to-noise ratio (S/N). The model is tested with tentative measurements of M′-band sky brightness and atmospheric extinction obtained at the Ali and Daocheng sites. We find that the noise caused by an excellent scientific detector and instruments at −135° C can be ignored compared to the M′-band sky background noise. Thus, when S/N = 3 and total exposure time is 1 second for 10 m telescopes, the magnitude limited by the atmosphere is 13.01m at Ali and 12.96m at Daocheng. Even under less-than-ideal circumstances, i.e., the readout noise of a deep cryogenic detector is less than 200e− and the instruments are cooled to below −87.2° C, the above magnitudes decrease by 0.056m at most. Therefore, according to observational requirements with a large telescope in a given infrared band, astronomers can use this sensitivity model as a tool for guiding site surveys, detector selection and instrumental thermal-control.
Effect of anisotropic collisions on solar scattering polarization
Authors: Qutub Saleh , Derouich Moncef , Ahmad Badruddin Zaheer
Published: May 2021

Scattering of anisotropic radiation by atoms, ions or molecules is sufficient to generate linear polarization observable in stars’ and planets’ atmospheres, circumstellar environments, and in particular in the Sun’s atmosphere. This kind of polarization is called scattering polarization (SP) or second solar spectrum (SSS) if it is formed near the limb of the solar photosphere. Generation of linear SP can typically be reached more easily than circular SP. Interestingly, the latter is often absent in observations and theories. Intrigued by this, we propose to demonstrate how circular SP can be created by anisotropic collisions if a magnetic field is present. We also demonstrate how anisotropic collisions can result in the creation of circular SP if the radiation field is anisotropic. We show that under certain conditions, linear SP creation is accompanied by the emergence of circular SP which can be useful for diagnostics of solar and astrophysical plasmas. We treat an example and calculate the density matrix elements of tensorial order k = 1 which are directly associated with the presence of circular SP. This work should encourage theoretical and observational research to be increasingly oriented towards circular SP profiles in addition to linear SP in order to improve our analysis tools of astrophysical and solar observations.
On the photoevaporation, dust polarization and kinematics of two nebulae in Sh2-236
Authors: Soam Archana
Published: May 2021

In the work presented here, the impact of magnetic field on the dynamical evolution of cometary globules Sim 129 and Sim 130 in the Sh2-236 HII region and the ionized gas streaming out of their surfaces is investigated. The magnetic field morphology in the region associated with these globules is inferred using optical polarization measurements with the Sampurnanand Telescope at ARIES. The nebular emission is probed through radio continuum mapping at 1.4 GHz with the archival National Radio Astronomy Observatory (NRAO) Very Large Array (VLA) Sky Survey (NVSS) data. The correlation of these measurements suggests that photoevaporated gas from the surfaces of Sim 129 and Sim 130 accumulates in clouds and starts streaming along the magnetic field lines. The 12CO (J=1–0) molecular line observations are performed towards NGC 1893 from the 14-m single dish radio telescope in Taeduk Radio Astronomy Observatory (TRAO). The velocity dispersion in the 12CO (J=1–0) molecular line and the dispersion in polarization angles are considered in the Davis-Chandrasekhar-Fermi formulation to estimate the magnetic field strength towards two Sim nebulae. The average value of field strength is found to be ∼60 μG with uncertainty of 0.5 times the estimated value.
Variations of helioseismic parameters due to magnetic field generated by a flux transport model
Authors: Bi Shao-Lan , Li Tan-Da , Liu Kang , Jiang Jie , Li Ya-Guang , Zhang Jing-Hua , Zhang Xian-Fei , Wu Ya-Qian
Published: May 2021

The change of sound speed has been found at the base of the convection during the solar cycles, which can be used to constrain the solar internal magnetic field. We aim to check whether the magnetic field generated by the solar dynamo can lead to the cyclic variation of the sound speed detected through helioseismology. The basic configuration of magnetic field in the solar interior was obtained by using a Babcock-Leighton (BL) type flux transport dynamo. We reconstructed one-dimensional solar models by assimilating magnetic field generated by an established dynamo and examined their influences on the structural variables. The results show that magnetic field generated by the dynamo is able to cause noticeable change of the sound speed profile at the base of the convective zone during a solar cycle. Detailed features of this theoretical prediction are also similar to those of the helioseismic results in solar cycle 23 by adjusting the free parameters of the dynamo model.
LAMOST Medium-Resolution Spectral Survey of Galactic Nebulae (LAMOST MRS-N): An overview of scientific goals and survey plan
Authors: Wu Chao-Jian , Wu Hong , Zhang Wei , Ren Juan-Juan , Chen Jian-Jun , Hsia Chih-Hao , Wu Yu-Zhong , Zhu Hui , Li Bin , Hou Yong-Hui , Wang Jun-Lin , Yu Shuo-Ran
Published: May 2021

Since Sep. 2018, LAMOST has started the medium-resolution (R ∼ 7500) spectral survey (MRS). We proposed the spectral survey of Galactic nebulae, including H ii regions, HH objects, supernova remnants, planetary nebulae and the special stars with MRS (LAMOST MRS-N). LAMOST MRS-N covers about 1700 square degrees of the northern Galactic plane within 40° < l < 215° and –5° < b < 5°. In this 5-year survey, we plan to observe about 500 thousand nebulae spectra. According to the commissioning observations, the nebulae spectra can provide precise radial velocity with uncertainty less than 1 km s−1. These high-precision spectral data are of great significance to our understanding of star formation and evolution.
Non-sinusoidal transit timing variations for the exoplanet HAT-P-12b
Authors: Sariya Devesh P. , Jiang Ing-Guey , Su Li-Hsin , Yeh Li-Chin , Chang Tze-En , Moskvin V. V. , Shlyapnikov A. A. , Ignatov V. , Mkrtichian David , Griv Evgeny , Mannaday Vineet Kumar , Thakur Parijat , Sahu D. K. , Chand Swadesh , Bisht D. , Sun Zhao , Ji Jianghui
Published: May 2021

Considering the importance of investigating the transit timing variations (TTVs) of transiting exoplanets, we present a follow-up study of HAT-P-12b. We include six new light curves observed between 2011 and 2015 from three different observatories, in association with 25 light curves taken from the published literature. The sample of the data used thus covers a time span of ∼ 10.2 years with a large coverage of epochs (1160) for the transiting events of the exoplanet HAT-P-12b. The light curves are utilized to determine the orbital parameters and conduct an investigation of possible TTVs. The new linear ephemeris shows a large value of reduced χ
2, i.e.

χ

red

2

(
23
)

= 7.93, and the sinusoidal fitting using the prominent frequency coming from a periodogram shows a reduced χ
2 around 4. Based on these values and the corresponding O – C diagrams, we suspect the presence of a possible non-sinusoidal TTV in this planetary system. Finally, we find that a scenario with an additional non-transiting exoplanet could explain this TTV with an even smaller reduced χ
2 value of around 2.
Searching for the brightest stars in galaxies outside the Local Group
Authors: Tikhonov Nikolay , Galazutdinova Olga , Sholukhova Olga , Valcheva Antoniya , Nedialkov Petko , Merkulova Olga
Published: May 2021

This paper introduces a technique for searching for bright massive stars in galaxies beyond the Local Group. To search for massive stars, we processed the results of stellar photometry from the Hubble Space Telescope (HST) images using the DAOPHOT and DOLPHOT packages. The results of such searches are demonstrated with examples of the galaxies DDO 68, M94 and NGC 1672. In the galaxy DDO 68, the LBV star changes its brightness, and massive stars in M94 can be identified by excess in the Hα band. For the galaxy NGC 1672, we measure the distance for the first time by the TRGB method, which enabled determining the luminosities of the brightest stars, likely hypergiants, in the young star formation region. So far, we have performed stellar photometry on HST images of 320 northern sky galaxies located at a distance less than 12 Mpc. This allowed us to identify 53 galaxies with probable hypergiants. Further photometric and spectral observations of these galaxies are planned to search for massive stars.
The feasibility and flexibility of selecting quasars by variability using ensemble machine learning algorithms
Authors: Yang Da-Ming , Xie Zhang-Liang , Wang Jun-Xian
Published: May 2021

In this work, we train three decision-tree based ensemble machine learning algorithms (Random Forest Classifier, Adaptive Boosting and Gradient Boosting Decision Tree respectively) to study quasar selection in the variable source catalog in SDSS Stripe 82. We build training and test samples (both containing 1:1 of quasars and stars) using the spectroscopic confirmed sources in SDSS DR14 (including 8330 quasars and 3966 stars). We find that when trained with variation parameters alone, all three models can select quasars with similarly and remarkably high precision and completeness (∼ 98.5% and 97.5%), even better than trained with SDSS colors alone (∼ 97.2% and 96.5%), consistent with previous studies. By applying the trained models on the variable sources without spectroscopic identifications, we estimate the spectroscopically confirmed quasar sample in Stripe 82 variable source catalog is ∼ 93% complete (95% for mi
< 19.0). Using the Random Forest Classifier we derive the relative importance of the observational features utilized for classifications. We further show that even using one- or two-year time domain observations, variability-based quasar selection could still be highly efficient.
Main problems of trajectory processing and approaches to their solution within the framework of multitarget tracking
Authors: Solonar A.S. , Khmarski P.A.
Published: May 2021

The main problems of trajectory processing of radar data are considered. Within the framework of the task of multitarget traсking, approaches are proposed that effectively solve the following problems: assignment problems; detection (reset) of trajectories; trajectory measurement of coordinates and motion parameters of the observed objects; highlighting trajectory features.
Aircraft flight control system fault tolerance under structural and parametric uncertainties
Authors: Kosyanchuk V. , Zheltov S. , Zybin E.
Published: May 2021

The concept of an intelligent hybrid aircraft fault-tolerant flight control system operating under complete parametric and structural uncertainty is considered. Fault tolerance in the proposed system is ensured through the efficient integration of model-based and model-free health monitoring and reconfiguring methods.
Strapdown electrostatic gyro with and without self-compensation
Authors: Landau B.E. , Belash A.A. , Levin S.L. , Medvedkov A.A. , Romanenko S.G.
Published: May 2021

Various applications of strapdown electrostatic gyroscopes (ESG), depending on the type and purpose of the vehicle on which the gyro is installed, as well as operation conditions, impose substantially different requirements on this gyro, including accuracy of information it provides. One of traditional methods used to ensure the gyro accuracy is self-compensating rotation of the housing. The paper considers some applications of a strapdown ESG with a solid rotor and the self-compensation methods used in these applications. This gyroscope was developed 20 years ago at the CSRI Elektropribor, but the work on its improvement goes on continuously. Theoretical aspects of the ESG operation are discussed, taking into account the developed drift model, as well as their experimental validation based on the analysis of ESG operation in polar orientations.
The investigation of FOG output signal dependency on environment temperature at high rates of temperature change
Authors: Nikiforovskii Danila , Smirnov Daniil , Deyneka Ivan , Nikitenko Alexander , Rupasov Andrey
Published: May 2021

The development of fiber-optic and electronic components has led to a significant widening of their application scope, in particular in the construction of ground vehicles navigation systems. Often, such systems have the special performance requirements under difficult temperature conditions: the environment temperature changing rate in some cases may reach several °C/min. One of the key elements of a navigation system is a fiber-optic gyroscope (FOG). The harsh environmental conditions increase the demands on production technology of the FOG, on the choice of construction materials, on the arrangement and shape of the parts, etc., however, in order to decrease temperature effects influence on the output signal of the device, the use of special algorithmic compensation methods is also required. Algorithmic compensation requires careful preparation of input data, which is associated with extensive experimental work. This article analyses the FOG temperature dependence characteristics in the wake of the designated experimental preparation for algorithmic compensation.
On Synthesis of Electromechatronic Module of the Gearless Servo System for High-Precision Motion Control of the Loaded Axis
Authors: Grechushkin Yu. V. , Epifanov O.K.
Published: May 2021

The paper analyses the torque characteristics, angular errors, natural frequencies, and finite elasticities of electromechatronic module within gearless servo system with coaxially arranged multi-pole brushless DC torque motor and high-precision induction resolver. We provide analytical expressions and describe conditions for optimization with regard to the following criteria: sufficient torque, minimized angular errors, downsized construction, and absence of resonant frequencies as applied to principal and design solutions of the module. The results from calculation studies for module implementations with different types of torque motors are discussed.
High-level testing of distributed systems based on a link model without loss of information
Authors: Gruzlikov A.V. , Kolesov N.V. , Tolmacheva M.V.
Published: May 2021

A new dynamic model of a distributed real-time computing system is investigated. The model is embedded in the system software and is intended for test diagnostics of violations in addressing exchanges between the system software modules. The questions of observability and controllability of the proposed model are discussed for the case when models of links are used without loss of information.
Using solvable classes of systems for scheduling of real-time computations with minimized jitter
Authors: Gruzlikov A.V. , Kolesov N.V. , Tolmacheva M.V.
Published: May 2021

An approach to scheduling a computational process in distributed real-time systems with jitter minimization is considered. The approach is based on the concept of a solvable class of systems for which there exist optimal scheduling algorithms of polynomial complexity.
Observers of Disturbances and Measurement Noises for Sector-bound Nonlinear System
Authors: Furtat I. B. , Gushchin P.A.
Published: May 2021

Observers of disturbances and measurement noises are developed for dynamical systems with sector-bound nonlinearity and parametric uncertainty. Conditions for the existence of these observers are proposed in the form of solvability of linear matrix inequalities (LMIs). Using the observers, a control law is designed to ensure system stabilization. The proposed algorithm is experimentally studied on a stand for multi-machine power systems control.
Adaptive observer of magnetic flux, angular position and velocity for synchronous motor with permanent magnets
Authors: Vedyakov A. , Pyrkin A. A. , Bespalov V. V. , Antipov V. A. , Cherginets D. A.
Published: May 2021

An adaptive magnetic flux and position observer has been designed for a permanent magnet synchronous motor. The measurable signals are stator winding currents and voltages only. The observer provides observation error convergence to zero in finite time for measurements without noise. The design method is iteratively applied to obtain the rotor velocity and load torque estimates.
Solving the problem of analytical design of the controller for a stationary discrete system with a small step
Authors: Ashirbaev B.Y.
Published: May 2021

In this paper, we study the problem of designing a linear controller for a stationary discrete system with a small step. By the method of integral manifolds, the discrete optimal control problem with a small step is subdivided into two subproblems, the solutions of which are found independently of each other. Algorithms for analytical solutions of subproblems are based on the second Lyapunov method. As a result, a linear controller was designed for a controlled stationary discrete system with a small step, consisting of two subcontrollers, which separately regulate the movements of a system of lower dimension. The results obtained can be used to design an optimal linear digital controller.
Tracking Problem with Consideration of Physical Constraints on Phase Variables and Control. Method of State Space Extension
Authors: Gulyukina S.I. , Utkin V.A.
Published: May 2021

The paper proposes a method for the synthesis of nonlinear systems invariant to the output variable, under the conditions of parametric and external perturbations, taking into account the constraints on phase variables and control. To solve the problem, the ideology of the block method using sat-functions as local feedback, and the disturbances observer on the sliding modes are applied.
Optimal damping concept: features and applications
Authors: Veremey E. I.
Published: May 2021

This work presents new ideas related to the synthesis of nonlinear stabilizing control laws in the framework of optimization approach. The focus is done on the optimal damping concept, proposed by V.I. Zubov in the early 60s of the last century. This theory is used to reduce significant computational costs in solving optimal stabilization problems. The essential features of the aforementioned concept are taken into account, allowing the construction of new methods for practical synthesis of control systems with desired dynamic properties. Various modern aspects of the optimal damping theory’s practical implementation are discussed. Special attention is paid to the specific choice of the functional to be damped to provide the desirable stability and performance features of the closed-loop connection.
Synthesis of modal control in servo system with a differentiating observer
Authors: Serdechnaya E. A.
Published: May 2021

A method of synthesis of modal control in servo systems with a differentiating observer of the reference action is proposed. It is shown that with the joint design of the modal controller and the observer, the uncertainty of the synthesis problem arises, which leads to the oscillation of the regulated value under step setting actions. To eliminate this uncertainty, the transition to the optimization problem of control synthesis was carried out. A numerical example of the formulation and solution of this problem is presented, which confirms the effectiveness of the proposed method.
Solving the Brokett problem based on robust stabilization
Authors: Serdechnaya E.A.
Published: May 2021

The paper proposes a method for solving the Brockett problem based on the synthesis of robust modal control for systems with non-stationary parameters, which does not require complex adaptation algorithms that involve the introduction of a variable regulator matrix. A transition to the task of synthesizing the regulator is shown, using a certain optimality criterion with limitations, which provides similar values to those of the regulator coefficients. A practical numerical example of setting and solving this problem is presented, which confirms the effectiveness of the proposed method. To illustrate the results obtained, a root travel time curve was constructed for two systems: robust and non-robust.
Analytical design of optimal regulators for non-classic quality functionals in a degenerate formulation
Authors: Bukov V.N. , Daneev A.V. , Sizykh V.N.
Published: May 2021

The paper considers the problem of analytical design of optimal controllers in the most general formulation for nonlinear plants with affinely (linearly and additively) input states and/or controls. On the basis of a new approach to approximately optimal control synthesis, a generalized theory of analytical design of optimal controllers is being developed. The main theorems are formulated; new concrete forms of non-classical quality functionals are obtained.
A method and tools for prototyping components of intelligent systems based on transformations
Authors: Bychkov I. V. , Yurin A. Yu.
Published: May 2021

The paper describes a method and tools for prototyping components of intelligent systems. These means are the parts of the PESoT technology based on generative and visual programming as well as the model transformations. The proposed method redefines the main stages and models of the standardized model-driven approach, in particular, Model Driven Architecture in the context of developing knowledge bases and expert systems that use the logical rules formalism. The description of the method is presented. Proposed tools include languages and software. Specifically, the Rule Visual Modeling Language and Personal Knowledge Base Designer are used for knowledge bases engineering including modeling and codification; the Transformation Model Representation Language and Knowledge Base Development System support model transformations and the rapid creation of computation-independent models. Described tools were applied to solve problems in the field of reliability and safety of technical systems.
Application of the PCF calculus for solving the problem of nonblocking supervisory control of discrete event systems
Authors: Davydov Artem , Larionov Aleksandr , Nagul Nadezhda
Published: May 2021

The paper provides a general view on the original logical inference based approach to dealing with discrete event systems as subject to supervisory control theory. The approach suggests a representation of discrete event system as a positively constructed formula to imply automated logical inference in the calculus of positively constructed formulas. During the inference, languages of the discrete event system are generated and analyzed. The minimally restricting supervisor for uncontrollable specification may be also designed. A nonblocking supervisor design is illustrated with a simplified model of autonomous underwater vehicle operational modes switching.
On the Concept of an Informational Community in a Social Network
Authors: Chkhartishvili A G , Gubanov D A
Published: May 2021

This paper introduces a constructive definition of an informational community, which agrees with formal models of opinion dynamics for bounded rational agents in social networks. As is shown below, uncertainty can be taken into account when detecting informational communities. An example of a stable informational community is given. A control problem for informational communities is stated, and its solution is presented within the DeGroot model.
The control model of arid plant communities
Authors: Shiroky A.A. , Isakov A.S. , Novochadov V.V.
Published: May 2021

The paper is devoted to simulation modelling of the arid plant communities (APC) behaviour. Such systems belong to the class of agroecological systems and include a large number of interacting natural factors that contribute to the system’s degradation. We propose a model of APC behaviour based on a weighted oriented graph. The values of weights and other coefficients reflecting the exposure of factors and their mutual relationship are acquired by expert assessments. The proposed model allows predicting the behaviour of APC in response to various biogenic control actions.
Mathematical theory of analysis and synthesis of control systems based on the general principle of isomorphism
Authors: Kulabukhov V.S.
Published: May 2021

A new paradigm in the theory of control systems is presented, in which all the basic concepts and properties of systems are formalized on the basis of a single principle - the general principle of isomorphism. The principle made it possible to formulate and prove the realization theorem, on the basis of which the basic concepts (model, abstract system, simple, complex, large system) have been mathematically strictly defined and the fundamental properties of systems and criteria for their provision have been formalized: in a new way, up to isomorphic models of a rather general form, the concepts and criteria of observability, controllability, checkability, identifiability of systems have been defined, and new formalized methods of analysis and synthesis of regulators, observers and integrated information-control systems have been developed, the examples of applications of the theory have been given.
Instances generation for a single machine scheduling problem
Authors: Lazarev A. , Pravdivets N. , Grishin E. , Galakhov S.
Published: May 2021

The branch and bound method is used to obtain exact solutions of the single machine scheduling problem with the objective function of maximum lateness minimization. Lower bounds are estimated by solving dual problems. A machine-independent value, namely the number of branching points in the search tree, is used as the complexity index of instances. The instances are presented as points in 3n-dimensional space. Known and newly developed ways of instances generation (with a large number of branching points) are presented, and the advantages and disadvantages of each of them are described.
The Notional Model of Knowledge Representation
Authors: Vykhovanets V. S.
Published: May 2021

The article describes a model of knowledge, called the notional model. A notion is a thought about a certain unique representation from the subject domain. The notional model uses notion-signs, notion-associations and notion-generalizations that are formed by primary mental abstractions: identification, generalization and association, respectively. The notional model consists of the notional structure and the contents of the notions. The notional structure describes each notion as a set of other notions united by one of the primary mental abstractions. The content of the notion is described using enumerating and resolving procedures. The notional model is semantically invariant, improves the transparency of the subject domain, and allows you to create the knowledge base with a linear estimate of a query execution time.
Decomposition Principle in Control of Socio-Technical Systems
Authors: Novikov D. A.
Published: May 2021

A general approach to decompose the interaction of agents in social, organizational and technical systems is proposed. Within this approach, the problems of reachability, sustainability and searching for an optimal trajectory can be solved independently for each agent.
Differential game of alternating pursuit of three targets by two pursuers with a Time-type criterion
Authors: Rubinovich Evgeny
Published: May 2021

On the plane, we consider the differential game of two identical pursuers against three consistently evading players (targets) forming a coalition. Players’ movements are simple. The speed of the pursuers is limited to one, the speed of the targets is limited by a given constant of less than one. At the beginning of the game, the pursuers and targets are localized at two different points on the plane: the pursuers are at a certain point P
0, and the targets are at a point E
0. A game is conducted with complete information. The task of the pursuers is to pinpoint all the targets in the shortest possible time. The task of evading players is the opposite.
Automatic Control Of Inverters In Electrical Networks: Capture Range And Cycle Slipping
Authors: Kuznetsov N.V. , Lobachev M.Y. , Yuldashev M.V. , Yuldashev R.V. , Volskiy S.I. , Sorokin D.A.
Published: May 2021

The paper discusses one of the issues of interaction of inverter electrical systems with control systems based on special models of the phase-locked loop, called Enhanced Phase-Locked Loop.
G.A. Leonov: eminent scholar, admired teacher and unconventional administrator
Authors: Abramovich S. , Kuznetsov N. , Razov A.
Published: May 2021

Gennady Alekseevich Leonov (1947 – 2018) – Corresponding member of the Russian Academy of Sciences, Foreign Member of the Finnish Academy of Science and Letters, a Council Member of International Federation of Automatic Control, the Highly Cited Mathematician of the Russian Federation, a bearer of many notable awards – passed away on April 23, 2018 after a short battle with a grievous illness. This paper is written in his memory. The authors remember Prof. Leonov as eminent scholar, admired teacher, and unconventional administrator.
Effect of adaptation rate value on convergence of gradient descent-based identification methods
Authors: Glushchenko A.I. , Petrov V.A. , Lastochkin K.A.
Published: May 2021

In this study, one of the main problems of practical implementation of adaptive control and identification systems is considered. This is the problem of choice of an adaptation rate value to provide the required convergence rate of linear regression parameters. The most widely applied method to identify such regression parameter values is the gradient descent (GD) one. But the adaptation rate is usually chosen manually for it and kept constant in the course of the plant functioning. The recursive least-squares (RLS) method can be used instead of GD as it provides the developer with the equation to adjust the adaptation rate automatically, taking into account the current value of the regressor. Therefore, the aim of this research is to compare the known properties of GD and RLS methods and demonstrate the capability of the RLS to provide a constant convergence rate under the condition of the time-varying regressor.
Optimal Dynamic Measurement Method Using Digital Moving Average Filter
Authors: Shestakov A.L. , Keller A.V.
Published: May 2021

The theory of optimal dynamic measurements is based on the use of methods of optimal control theory to find a dynamically distorted input signal from the observed output signal. The model of the measuring system contains a Leontief type system, the initial Showalter–Sidorov condition. Inertia of the measuring system and interference lead to distortion of the input signal. We present a numerical method to use a digital moving average filter for the observed signal with subsequent application of the method of optimal dynamic measurement, as well as the results of computational experiments.
Projection-operator optimization of controls of dynamic objects
Authors: Kozlov V.N. , Efremov A.A.
Published: May 2021

The principles of application of projection-operator methods of mathematical programming for calculating optimal controls based on “immersion of control problems” in problems of finite-dimensional mathematical programming are formulated. The results obtained illustrate the technique of qualitative study of the stability of systems with optimizing feedback based on the contraction mapping principle of functional analysis. The considered technique allows one to synthesize locally optimal systems with nonlinear control objects. In this case, nonlinear models of objects are taken into account in the right-hand sides of linear manifolds, and the projection operator forms nonlinear optimal controls with feedback taking into account the operators of nonlinearities of the object.