bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the photoevaporation, dust polarization and kinematics of two nebulae in Sh2-236
Authors: Soam Archana 
Published: May 2021

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.