bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine-grained distributed averaging for large-scale radio interferometric measurement sets
Authors: Wei Shou-Lin , Luo Kai-Da , Wang Feng , Deng Hui , Mei Ying 
Published: May 2021

Abstract
The Square Kilometre Array (SKA) would be the world’s largest radio telescope with eventually over a square kilometre of collecting area. However, there are enormous challenges in its data processing. The use of modern distributed computing techniques to solve the problem of massive data processing in the SKA is one of the most important challenges. In this study, basing on the Dask distribution computational framework, and taking the visibility function integral processing as an example, we adopt a multi-level parallelism method to implement distributed averaging over time and channel. Dask Array was used to implement super large matrix or arrays with supported parallelism. To maximize the usage of memory, we further exploit the data parallelism provided by Dask that intelligently distributes the computational load across a network of computer agents and has a built-in fault tolerance mechanism. The validity of the proposed pattern was also verified by using the Common Astronomy Software Application (CASA), wherein we analyze the smearing effects on images reconstructed from different resolution visibilities.
Portable adaptive optics for exoplanet imaging
Authors: Zhu Yong-Tian , Dou Jiang-Pei , Zhang Xi , Zhao Gang , Guo Jing , Infante Leopoldo 
Published: May 2021

Abstract
The portable adaptive optics (PAO) device is a low-cost and compact system, designed for 4- meter class telescopes that have no adaptive optics (AO) system, because of the physical space limitation at the Nasmyth or Cassegrain focus and the historically high cost of conventional AO. The initial scientific observations of the PAO are focused on the direct imaging of exoplanets and sub-stellar companions. This paper discusses the concept of PAO and the associated high-contrast imaging performance in our recent observational runs. PAO deliver a Strehl ratio better than 60% in H band under median seeing conditions of 1″. Combined with our dedicated image rotation and subtraction (IRS) technique and the optimized IRS (O-IRS) algorithm, the averaged contrast ratio for a 5 ≤ V
mag ≤ 9 primary star is 1.3 × 10−5 and 3.3 × 10−6 at angular distance of 0.36″ with exposure time of 7 minutes and 2 hours, respectively. PAO has successfully revealed the known exoplanet of κ And b in our recent observation with the 3.5-meter ARC telescope at Apache Point Observatory. We have performed the associated astrometry and photometry analysis of the recovered κ And b planet, which gives a projected separation of 0.984″ ± 0.05″, a position angle of 51.1° ± 0.5° and a mass of

10.15

−
1.255

+
2.19

M

Jup

. These results demonstrate that PAO can be used for direct imaging of exoplanets with medium-sized telescopes.
A study of the global magnetic activity of the star Kepler-17 using light curve inversion with bipartite regularization
Authors: Luo Tao , Liang Yan-Yan , Ip Wing-Huen , Huang Hao-Zhi , Lin Xu-Xin 
Published: May 2021

Abstract
A new method of light curve inversion with bipartite regularization (LIBR), which is complementary to the previous treatments by Bonomo and Lanza and Estrela and Valio, is used to reconstruct the physical properties of star spots on the solar-type star Kepler-17 by using the full Q1- Q17 data set. The Markov Chain Monte Carlo (MCMC) method was applied to find the best profile of the reconstructed surface. The known value of the rotation inclination of Kepler-17 allows the generation of a star spot model in a sequence of stellar rotation with a period of 12.26 d. Because of the nature of the light curve inversion, the spot model is limited to the equatorial region. We also investigated the starspot lifetimes of Kepler-17 utilizing the MCMC method. Combined with the LIBR inversion results, it was found that the star spots typically last from one to several stellar rotations. From the time evolution of the spot size, a magnetic cycle period of 437 d can be derived. This value is comparatively shorter than the solar cycle which might be a consequence of the younger age (∼ 1.78 Gyr) of Kepler-17. The light curve of Kepler-17 is characterized by the presence of large-amplitude variation caused by star spots but no superflare activity. An interesting possibility is that the magnetic energy stored in the star spot regions could have been constantly dissipated by electrodynamic interaction between the central star and the hot Jupiter, Kepler-17b, via a lower-level energy release process.
Explaining recently studied intermediate luminosity optical transients (ILOTs) with jet powering
Authors: Soker Noam , Kaplan Noa 
Published: May 2021

Abstract
We apply the jet-powered ILOT scenario to two recently studied intermediate luminosity optical transients (ILOTs), and find the relevant shell mass and jets’ energy that might account for the outbursts of these ILOTs. In the jet-powered ILOT scenario, an accretion disk around one of the stars of a binary system launches jets. The interaction of the jets with a previously ejected slow shell converts kinetic energy to thermal energy, part of which is radiated away. We apply two models of the jet-powered ILOT scenario. In the spherical shell model, the jets accelerate a spherical shell, while in the cocoon toy model the jets penetrate into the shell and inflate hot bubbles, the cocoons. We find consistent results. For the ILOT (ILRT: intermediate luminosity red transient) SNhunt120 we find the shell mass and jets’ energy to be M
s ≃ 0.5 − 1 M
⊙ and E
2j ≃ 5 × 1047 erg, respectively. The jets’ half opening angle is αj
≃ 30° − 60°. For the second peak of the ILOT (luminous red nova) AT 2014ej we find these quantities to be M
s ≃ 1 − 2 M
⊙ and E
2j ≃ 1.5 × 1048 erg, with αj
≃ 20° − 30°. The models cannot tell whether these ILOTs were powered by a stellar merger that leaves one star, or by mass transfer where both stars survived. In both cases the masses of the shells and energies of the jets suggest that the binary progenitor system was massive, with a combined mass of M
1 + M
2 ≳ 10 M
⊙.
Resolving the inner jet of PKS 1749+096 with super-resolution VLBA images at 7 mm
Authors: Cui Lang , Lu Ru-Sen , Yu Wei , Liu Jun , Patiño-Álvarez Víctor M. , Yuan Qi 
Published: May 2021

Abstract
High resolution imaging of inner jets in Active Galactic Nuclei (AGNs) with Very Long Baseline Interferometry (VLBI) at millimeter wavelengths provides deep insight into the launching and collimation mechanisms of relativistic jets. The BL Lac object, PKS 1749+096, shows a core-dominated jet pointing toward the northeast on parsec-scales revealed by various VLBI observations. In order to investigate the jet kinematics, in particular, the orientation of the inner jet on the smallest accessible scales and the basic physical conditions of the core, in this work we adopted a super-resolution technique, the Bi-Spectrum Maximum Entropy Method (BSMEM), to reanalyze VLBI images based on the Very Long Baseline Array (VLBA) observations of PKS 1749+096within the VLBA-BU-BLAZAR 7mm monitoring program. These observations include a total of 105 epochs covering the period from 2009 to 2019. We found that the stacked image of the inner jet is limb-brightened with an apparent opening angle of 50 ° 0 ± 8 ° 0 and 42 ° 0 ± 6° 0 at the distances of 0.2 and 0.3 mas (0.9 and 1.4 pc) from the core, corresponding to an intrinsic jet opening angle of 5° 2 ± 1 ° 0 and 4° 3 ± 0° 7, respectively. In addition, our images show a clear jet position angle swing in \sr within the last ten years. We discuss the possible implications of jet limb brightening and the connection of the position angle with jet peak flux density and gamma-ray brightness.
A catalogue of 74 new open clusters found in Gaia Data-Release 2
Authors: He Zhi-Hong , Xu Ye , Hao Chao-Jie , Wu Zhen-Yu , Li Jing-Jing 
Published: May 2021

Abstract
Based on astrometric data from Gaia Data-Release 2 (DR2), we employ an unsupervised machine learning method to blindly search for open star clusters in the Milky Way within the Galactic latitude range of |b| < 20°. In addition to 2080 known clusters, 74 new open cluster candidates are found. In this work, we present the positions, apparent radii, parallaxes, proper motions and member stars of these candidates. Meanwhile, to obtain the physical parameters of each candidate cluster, stellar isochrones are fit to the photometric data. The results show that the apparent radii and the observed proper motion dispersions of these new candidates are consistent with those of open clusters previously identified in Gaia DR2.
BoxCox multi-output linear regression for 10.7 cm solar radio flux prediction
Authors: Cui Rui-Fei , Zhu Ya-Guang , Zhang Huan , Zhang Ri-Wei , Zhao Hong-Yu , Li Zheng-Lian 
Published: May 2021

Abstract
We consider the problem of predicting the mid-term daily 10.7cm solar radio flux (F10.7), a widely-used solar activity index. A novel approach is proposed for this task, in which BoxCox transformation with a proper parameter is first applied to make the data satisfy the property of homoscedasticity that is a basic assumption of regression models, and then a multi-output linear regression model is used to predict future F10.7 values. The experiment shows that the BoxCox transformation significantly improves the predictive performance and our new approach works substantially better than the prediction from the US Airforce and other alternative methods like Auto-regressiveModel, Multi-layer Perceptron, and Support Vector Regression.
Hierarchical event-based control of multi-robot systems in unstructured environments
Authors: Bychkov I , Ulyanov S , Nagul N , Davydov A , Kenzin M , Maksimkin N 
Published: May 2021

Abstract
An essential requirement for achieving a high level of performance, autonomy, and reliability of a multi-robot system performing joint long-term operations in an unstructured environment is an advanced control system. In general, the robot’s control system is designed to be hierarchical and consists of several subsystems. To unify the interaction of individual components and reduce the load on computing and communication devices, we use the event-based methodology at different levels of the control system. In the paper, we demonstrate how this methodology can be applied to solve four challenging problems in robotics: cooperative formation control, path planning, missions scheduling, and action planning.
Artificial Intelligence at Present and Tomorrow
Authors: Gorodetsky V , Yusupov R. 
Published: May 2021

Abstract
Artificial Intelligence, part of Information Technology, is currently the hottest spot in Information technology the main research subject of which is knowledge and the main research directions are methodologies, methods, and algorithms for knowledge acquisition, knowledge representations, and knowledge usage. The paper describes the core scientific content of these directions, outlines their state-of-the-arts, and analyzes briefly new trends and prospects for research and development in Artificial Intelligence for the forthcoming years.
In-flight inertial navigation system alignment under non-controlled delays in aiding data
Authors: Golovan A.A. , Zheleznov V.M. , Smolianov D.I. , Mishin A.Yu. , Fomin D.M. , Belov R.V. 
Published: May 2021

Abstract
In the presented paper we consider a well-known in-flight alignment problem for strapdown inertial navigation system (INS) via position and velocity data provided by the reference inertial navigation system. Main challenges of the mentioned problem are displacement of the reference navigation system relative to the navigation system being aligned, mutual misalignment of the relevant body frames, the presence of uncontrolled time delays in the positional and velocity aiding data. We propose in-flight alignment algorithm that was tested based on simulation. Typical vehicle’s trajectories were derived from relevant telemetry data. The results of numerical experiments are also presented.
Neural network approach to recognition of visible constellations by sky photo image
Authors: Galkin V.A. , Makarenko A.V. 
Published: May 2021

Abstract
The current paper demonstrates the effective capabilities of deep neural networks in solving the problem of identification of constellations from a photo of the sky in conditions of a priori uncertainty, incomplete observability and stochastic disturbances. The quality of solution 0,927 by metric F1 is obtained. In order to achieve the result, the original ResNet-like architecture of the convolution neural network was synthesized; statistical analysis of the dataset was carried out, the function of losses and strategy of neural network training were developed, and an accurate criterion of constellation observability in the image was formed. The observation of noise influence on the quality and stability of solutions was carried out.
On the application of neural network technologies for control problems in cognitive transportation systems
Authors: Lukomskaya O.Yu. , Seliverstov Y.A. 
Published: May 2021

Abstract
In the work, the functions of cognition are brought in line with the aspects of the functioning of cognitive transport systems and technologies. We consider the mathematical apparatus of cognitive technologies – neural network control systems, based on trained multi-layer neural networks of direct action in the class of adaptive control systems for dynamic objects. The possibility and variants of their inclusion in the control system of the transport system are clarified. On the basis of the considered approach, a country road recognition system based on a convolutional neural network has been developed, which will automatically segment rural roads using satellite images and build a road network diagram to analyze the spatial development of transport networks and to control unmanned vehicles. The development of a neural network based on U-net was carried out in Python 3x. The training set consists of 880 images prepared by hand mark up. The accuracy of the developed model when testing on prepared samples was 64%. According to the results of the study, conclusions were drawn and prospects for further functional development of the developed tools were determined.
Application of singular transformations method with regard to nonlinearities in the equations of dynamics and measurements
Authors: Tupysev V. A. , Loparev A. V. , Litvinenko Yu. A. 
Published: May 2021

Abstract
The possibility of state estimation for a dynamic system with nonlinearities in the equations of dynamics and measurements using the Singular Transformations Method is discussed. The features of the proposed approach application are considered. For a methodological example, the equations for the required estimates are specified and the estimation accuracy analysis is carried out.
On Control of Brushless Torque Motors with High Phase Inductance in Direct Drives of Gyro Devices
Authors: Grechushkin Yu. V. , Epifanov O. K. 
Published: May 2021

Abstract
The paper studies how the phase inductance of brushless DC torque motors affects their performance within high precision electric direct drives. Modified control laws for torque motors with high phase inductance are described, which optimize their performance by various criteria. The modified laws are based on continuous regulation of mutual attitude of current and voltage vectors in the motor windings. Parameters of torque motors are compared with the described control laws applied, and advantages of their use are covered.
Development of a combined navigation and measurement system for manned airborne geophysical measurements
Authors: Trigubovich G.M. , Shevchuk S.O. , Kosarev N.S. , Sverkunov A.S. , Nikitin V.N. 
Published: May 2021

AbstractThe article is devoted to the idea of combining navigation and measurement software to provide a higher level of efficiency and quality of aerial electromagnetic survey. Complex geophysical measurement systems of “Impulse-Aero” series are overviewed. Current survey technology with the above-mentioned systems includes human-based control of the measurements with a geophysicist on-board. The technology also includes the navigational support by the geophysicist or an additional navigation specialist. The concept of automatic combined complex for navigational and measurement monitoring is proposed in the article. The main goal of the system under analysis is to automatically estimate the quality of received data and to give necessary recommendations on the screen of the navigation unit. As the result of the survey, some tasks during the flight can be solved by pilots without any additional staff. This approach is supposed to increase flight safety, reduce costs and raise the efficiency of the survey in general.
Properties of solutions of dynamic control reconstruction problems
Authors: Krupennikov E. A. 
Published: May 2021

Abstract
This paper is devoted to inverse problems of the control theory, namely, the dynamic control reconstruction problem. It is the problem of online reconstruction of unknown controls (the input) using known inaccurate measurements of the realized trajectory (the output). Deterministic affine controlled systems are considered. A method for solving this problem is suggested. It relies on auxiliary variational problems on extremum of a regularized integral residual functional. The key feature of this method is using a functional which is convex in control variables and concave in state variables. Properties of the solutions obtained by this method are studied. It is shown that the obtained solutions have oscillating character and are bounded. Results of numerical simulations are provided.
Ensuring the accuracy of modal control in systems with multicomponent actions
Authors: Tavolzhanskij A.V. 
Published: May 2021

Abstract
The problem of ensuring the accuracy for constant and harmonic input actions in systems with modal control is considered. An analytical method of combined formation of both the control accuracy and the type of transient process is proposed. The modal control possibilities for harmonic signals are shown, for which the synthesis method is usually applied to the desired frequency response. It also introduces a requirement of quality in terms of speed. This problem is being solved by drawing up an inequality system. These inequalities are illustrated graphically. Using a numerical example, the effectiveness of the proposed method for solving the problem is shown.
Stability study of digital multi-connected automatic control system
Authors: Ilyasov B. G. , Saitova G.A. , Elizarova A.V. 
Published: May 2021

Abstract
A study of the stability of a multiply connected automatic control system containing digital links by the frequency method is proposed. The stability criterion is based on the system description of the dynamic properties of the system at the level of characteristics of subsystems and characteristics of communication.
Emergency broadcasting strategies for distributed robotic groups under limited communication
Authors: Kenzin Maksim , Bychkov Igor , Maksimkin Nikolai 
Published: May 2021

Abstract
Execution of large-scale search and survey operations by groups of autonomous mobile robots requires the ability to respond to unforeseen events of different nature in a quick and efficient manner. In order to achieve this requirement, the available information about recent changes should be spread among all active group members as soon as possible. Informing a non-stationary group of mobile robots distributed across different regions of the operational area is a nontrivial task for large groups with limited communication capabilities. The paper addresses the problem of agent-based information distribution throughout a network in a new original formulation. In essence, the problem is to define an effective order of transferring data between single robots in order to achieve the fastest way of sharing it among the whole group. A number of heuristic strategies are proposed for building initial solutions alongside with the local search scheme for their further optimization. The comparison between the suggested approaches is made regarding both the solution quality and the speed of algorithm operation. Some issues related to the test instances generation are also considered.
Vulnerabilities, Points of Failure and Adaptive Protection Methods in the Context of Group Control of Unmanned Vehicles
Authors: Iskhakov A.Yu. , Mamchenko M.V. 
Published: May 2021

Abstract
Continuous improvements in the hardware, software and algorithms of unmanned vehicles (UVs) are nearing their mass deployment in all physical environments, including within unmanned groups, and with traditional means of transport controlled by the operators (drivers). Notwithstanding the measures taken to improve security and resilience, UVs as complicated cyberphysical systems have a number of vulnerabilities and failure points. This paper comprises the review of known vulnerabilities and failure points (including those in group control scenarios), and the development of the proposals to improve the resilience and security of UVs, and addresses the identified issues.
Algorithms for coordination of autonomous underwater drones searching for a hidden object when no long-range communication is allowed
Authors: Fedyanin D. N. 
Published: May 2021

Abstract
The paper is devoted to comparison of the efficiency of information exchange by autonomous mobile agents when searching in a limited coverage area. The special feature of the problem is to consider the case of operation within the prohibition of usage of radio, light, and acoustic communication channels at a great distance, as well as without surfacing. The paper compares the following algorithms for the work of groups of autonomous robots, based on a preliminary division of area into sectors and survey of robots in their sectors using the “breadth-first search” method.
On how to model and investigate the interaction of mobile network nodes with a limited number of mobile access points
Authors: Blinova O.V. 
Published: May 2021

Abstract
This paper investigates a new way to position unmanned aerial vehicles, that act as routers, to allow subscribers to access a communication network. In my model, the subscribers move along known trajectories in sparsely populated areas. To solve this problem, I developed a software to simulate how the subscribers move. I also developed an optimization algorithm that maximizes my custom objective function, where the function sums the probabilities for the subscribers to access the network.
Shapley value of n-person prisoner’s dilemma
Authors: Grinikh A.L. , Petrosyan L.A. 
Published: May 2021

Abstract
n-Person prisoner’s dilemma is a Markovian sequence of static games that are realized randomly depending on players’ previous choices. The dynamic Shapley value is constructed in this case. The work is a continuation of the paper published earlier by Grinikh A. L. [1]. In this paper, we consider the new approach of dynamics of game which depends on the strategies of all players.
The study of periodic oscillations and global stability in the Tal’ model via the Tsypkin method and the LPRS method
Authors: Kuznetsov N.V. , Akimova E.D. , Mokaev R.N. , Morozova M.N. 
Published: May 2021

Abstract
Analysis of the phase space of discontinuous systems via classical methods of the theory of oscillations can be quite a difficult task. Moreover, in some cases this analysis is impossible to perform. Due to the emergence of frequency methods for analysis of discontinuous systems and the development of various analytical-numerical methods, it has become possible to give a more accurate description of the phase space of systems with discontinuous right-hand sides. The present report tries to adopt to the Watt’s governor model that takes account of the self-regulation of the object and the derivative action. We compare the results with those obtained by rigorous analytical method.