• Title/Summary/Keyword: Cluster observation

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Cluster Model of Multilingual Training of University Students: Theory and Practice of Engineering Education

  • Suvorova, Svetlana;Khilchenko, Tatyana;Gnatyshina, Elena;Uvarina, Natalia;Savchenkov, Alexey
    • International Journal of Computer Science & Network Security
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    • v.22 no.10
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    • pp.107-112
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    • 2022
  • Nowadays clusters are recognized as an important instrument for promoting industrial development, innovation, competitiveness and growth. An educational cluster is a set of interrelated vocational educational institutions of various levels that are united by industry with each other and are connected by partnership with industry enterprises. This article attempts to develop and describe cluster model of university students' multilingual training. The purpose of this study is to describe multilingual training of university students and their polycultural competencies formation and to define the process of multilingual training in form of a cluster. The authors consider clusters as an integral part of the educational campus within the concept framework of Shadrinsk State Pedagogical University. To determine the essence of the concept of a cluster model of university students' multilingual training, theoretical, empirical, observational, and diagnostic methods were implemented, such as a review of scientific literature, a compilation of best practices, observation, statistical methods, etc. The authors analyzed the programs of partner universities and organized international webinars and internships for bachelors and masters abroad and developed online courses "Foreign language for undergraduate students and masters". Experimental data obtained during the implementation of cluster training show the effectiveness of the formation of students' polycultural competencies.

Circumnuclear gas around the central AGN in a cool-core cluster, A1644-South

  • Baek, Junhyun;Chung, Aeree;Kim, Jae-Woo;Jung, Taehyun
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.30.2-31
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    • 2020
  • We present the properties of circumnuclear gas associated with the AGN located in the center of Abell 1644-South. A1644-S is the main cluster in a merging system, which is also known for gas sloshing in its core as seen in X-ray. The X-ray emission of A1644-S shows a rapidly declining profile, indicating the presence of cooling gas flow. This flow of cool gas may fuel the supermassive black hole embedded in the brightest cluster galaxy, leading to the activation of the central AGN. Indeed, we find a parsec-scale bipolar jet feature in the center of A1644-S in our recent KaVA observation, which implies that its central AGN is likely to have been (re)powered quite recently. In order to verify the hypothesis that cooling gas flow in the cluster core can (re)activate the central AGN, we probe the cold gas properties of the central 1 kpc region of A1644-S using the archival VLA and ALMA data. Based on the spatially resolved morphology and kinematics of HI and CO gas, we challenge to identify inflow/outflow gas streams and clumps. We study the role of circumnuclear cool gas in fueling the centrally located cluster AGN in the cool-core environment. We also discuss how the feedback due to the (re)powered AGN affects the surrounding medium.

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A Numerical Weather Prediction System for Military Operation Based on PC cluster (작전기상 지원을 위한 PC 클러스터 기반의 기상수치예보시스템)

  • 이용희;장동언;안광득;조천호
    • Journal of the Korea Institute of Military Science and Technology
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    • v.6 no.4
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    • pp.45-55
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    • 2003
  • Weather conditions have played a vital role in a war. Many historical records reported that the miss use of weather information is the main reason of the lost a war. In this study we demonstrated the possibility of applying the numerical weather prediction system(NWPS) for military operations. The NWPS consists of PC-cluster as a super computer, data assimilation system ingesting many remote sensing observation, and graphic systems. High resolution prediction in NWPS can provide useful weather information such as wind, temperature, sea fog and so on for military operations.

NEW VARIABLE STARS IN THE REGION OF THE OPEN CLUSTER M48 (NGC 2548) (산개성단 M48(NGC 2548) 영역의 새로운 변광성)

  • Jeon, Young-Beom;Lee, Hye-Ran
    • Publications of The Korean Astronomical Society
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    • v.26 no.4
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    • pp.141-146
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    • 2011
  • In the region of the open cluster M48 (NGC 2548), time-series BV CCD images were taken for 22 nights from February 28 in 2008 to March 17 in 2011. From this observation, we found 10 new variable stars. They include five eclipsing binaries, an RR Lyrae, two ${\delta}$ Scuti, and two semi-periodic and/or slow irregular type variable stars. We fail to find the member stars of the open cluster among the 10 variable stars.

Black Hole Binaries Dynamically Formed in Globular Clusters

  • Park, Dawoo;Kim, Chunglee;Lee, Hyung Mok;Bae, Yeong-Bok;Belczynski, Krzysztof
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.1
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    • pp.43.1-43.1
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    • 2017
  • We investigate properties of black hole (BH) binaries formed in globular clusters, by using direct N-body simulations. Comparing with previous studies which usually considered single BH masses, our models consist of two-component BH masses, or continuous BH mass function with single mass ordinary cluster stars. During the early stage of dynamical evolution, initially distributed BHs are move to the cluster center by dynamical friction, then BH-BH binaries start to be formed, and eventually be ejected from the cluster due to three body interaction. Finally we find the formation efficiency of high mass BHs are alwats larger than that of lower mass BHs, implying that a BH mass spectrum expected from GW observation should be biased to high mass. In addition, mass ratios of BHs in binaries prefer similar masses (ratio~1), while the most extreme case is less than 3. Expected merger rate from our models is about 7 BH-BH mergers per $Mpc^3$ per yr.

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Estimating dark matter mass for the most massive high-z galaxy cluster, SPT-CL J2106-5844 using weak-lensing analysis with HST observations

  • Kim, Jinhyub;Jee, Myungkook James;Ko, Jongwan
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.67.2-67.2
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    • 2016
  • SPT-CL J2106-5844 is known to be one of the most massive galaxy clusters ($M_{200}{\sim}1.27{\times}10^{15}M_{sun}$) ever found at z > 1. Given its redshift (z ~ 1.132), the mass of this cluster estimated by Sunyaev-Zel'dovich effect and X-ray observation is too large compared with the current ${\Lambda}CDM$ cosmology prediction. Mass estimation from these methods can be biased because they require assumptions on hydrostatic equilibrium, which are not guaranteed to hold at such high redshift (about 40% of the current age of the Universe). Thus, we need to verify the mass of this interesting cluster using gravitational lensing, which does not require such assumptions. In this work, we present our preliminary result of dark matter mass and its spatial mass distribution of SPT-CL J2106-5844 using weak-lensing analysis based on HST optical/NIR deep imaging data. We compare mass estimates from different sources and discuss cosmological implications.

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Tales of AGN tails: How AGN tails become radio relics in merging galaxy clusters?

  • Lee, Wonki;Jee, M. James
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.1
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    • pp.32.2-32.2
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    • 2021
  • Radio relics, Mpc-size elongated diffuse radio emissions found at galaxy cluster outskirts, are known as the result of shock acceleration during the cluster merger. Theories have claimed that low Mach number shocks are too inefficient to create the observed properties of radio relics. Alternative scenarios such as fossil cosmic ray electrons (CRes) from AGNs are required to explain the observations. However, how exactly the fossil CRes from AGNs can supply the Mpc-size radio relic is still an open question. In this study, we present our recent uGMRT radio observation results of the merging galaxy cluster Abell 514. We found three remarkable AGN jet tails that may have undergone multiple reorientations and extend nearly 800 kpc. Using multi-frequency data, we have performed spectral analysis along the AGN tails and track how the tails lose or gain energy as they propagate in the intracluster medium. We will discuss whether these AGN jets can provide sufficient seed CRes to radio relics.

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Observation of Transition Boundary between Cold, Dense and Hot, Tenuous Plasmas in the Near-Earth Magnetotail

  • Kim, Hee-Eun;Lee, Ensang
    • Journal of Astronomy and Space Sciences
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    • v.37 no.2
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    • pp.95-104
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    • 2020
  • Properties of plasmas that constitute the plasma sheet in the near-Earth magnetotail vary according to the solar wind conditions and location in the tail. In this case study, we present multi-spacecraft observations by Cluster that show a transition of plasma sheet from cold, dense to hot, tenuous state. The transition was associated with the passage of a spatial boundary that separates the plasma sheet into two regions with cold, dense and hot, tenuous plasmas. Ion phase space distributions show that the cold, dense ions have a Kappa distribution while the hot, tenuous ions have a Maxwellian distribution, implying that they have different origins or are produced by different thermalization processes. The transition boundary separated the plasma sheet in the dawn-dusk direction, and slowly moved toward the dawn flank. The hot, tenuous plasmas filled the central region while the cold, dense plasmas filled the outer region. The hot, tenuous plasmas were moving toward the Earth, pushing the cold, dense plasmas toward the flank. Different types of dynamical processes can be generated in each region, which can affect the development of geomagnetic activities.