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OGLE-2016-BLG-0693LB: Probing the Brown Dwarf Desert with Microlensing
Ryu, Y.-H.,Udalski, A.,Yee, J. C.,Albrow, M. D.,Chung, S.-J.,Gould, A.,Han, C.,Hwang, K.-H.,Jung, Y. K.,Shin, I.-G.,Zhu, W.,Cha, S.-M.,Kim, D.-J.,Kim, H.-W.,Kim, S.-L.,Lee, C.-U.,Lee, Y.,Park, B.-G.,P American Astronomical Society 2017 The Astronomical journal Vol.154 No.6
<P>We present an analysis of microlensing event OGLE-2016-BLG-0693, based on the survey-only microlensing observations by the OGLE and KMTNet groups. In order to analyze the light curve, we consider the effects of parallax, orbital motion, and baseline slope, and also refine the result using a Galactic model prior. From the microlensing analysis, we find that the event is a binary composed of a low-mass brown dwarf (49(-18)(+20) Mj) companion and a K- or G-dwarf host, which lies at a distance of 5.0 +/- 0.6 kpc toward the Galactic bulge. The projected separation between the brown dwarf and its host star is less than similar to 5 au, thus it is likely that the brown dwarf companion is located in the brown dwarf desert.</P>
OGLE-2016-BLG-1190Lb: The First<i>Spitzer</i>Bulge Planet Lies Near the Planet/Brown-dwarf Boundary
Ryu, Y.-H.,Yee, J. C.,Udalski, A.,Bond, I. A.,Shvartzvald, Y.,Zang, W.,Jaimes, R. Figuera,Jørgensen, U. G.,Zhu, W.,Huang, C. X.,Jung, Y. K.,Albrow, M. D.,Chung, S.-J.,Gould, A.,Han, C.,Hwang, K.-H.,Sh American Astronomical Society 2018 The Astronomical journal Vol.155 No.1
<P>We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/ bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M-p = 13.4 +/- 0.9 M-J, places it right at the deuteriumburning limit, i. e., the conventional boundary between 'planets' and 'brown dwarfs.' Its existence raises the question of whether such objects are really ' planets' (formed within the disks of their hosts) or 'failed stars' (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M-host = 0.89. +/- 0.07 M-circle dot, and the planet has a semimajor axis a similar to 2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over < 1% of an orbital period.</P>
An Isolated Microlens Observed from <i>K2</i> , <i>Spitzer</i> , and Earth
Zhu, Wei,Udalski, A.,Huang, C. X.,Novati, S. Calchi,Sumi, T.,Poleski, R.,Skowron, J.,Mró,z, P.,Szymań,ski, M. K.,Soszyń,ski, I.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Pawlak, M.,Be American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.849 No.2
K. W. Shao,W. H. Zhou,K. Gao,X. G. Zhu,P. Jia,Y. Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3
Catastrophic brittle failure prevents the application of bulk metallic glasses (BMGs).The brittle La69Co17Al14BMG showslarge compressive plasticity when compressed in constrained conditions. Here the compressive plasticity of this BMG wassystematically studied by decreasing aspect ratio (height/diameter) of the samples in uniaxial compression and the brittleductiletransition occurs at an aspect ratio of 0.36. With the increase of the plasticity (decrease of the aspect ratio), the hardnessdecreases firstly and then increases, however, the relaxation enthalpy indicating its structure increases monotonically. Our findings provide a powerful experimental support for the application of brittle La-based BMGs.
K. B. Nie,Z. H. Zhu,K. K. Deng,Y. C. Guo,J. G. Han 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
In this work, a Mg–Zn–Ca magnesium matrix nanocomposite containing nano-sized TiC particles was firstly processed bymultidirectional forging (MDF). With increasing the forging temperature from 230 to 310 °C for 1 MDF pass or the numberof MDF passes at 270 °C, both volume fractions and average sizes of recrystallized grains increased. The average sizes ofprecipitated MgZn2phases increased with the increase in either the initial forging temperature or MDF passes, and the volumefractions gradually decreased with increasing the initial forging temperature or decreasing the MDF passes. With decreasingthe initial MDF temperature, thermal expansion mismatch strengthening slightly decreased while fine-grain strengtheningand Orowan strengthening gradually increased, resulting in a gradual increased yield strength. The elongation of the presentnanocomposite gradually increased from 8.2% after 1 MDF pass to 22.7% after 6 MDF passes, while both yield strength andultimate tensile strength did not change significantly. This could be ascribed to that although the fine-grain strengtheninggradually reduced, there was no significant change in the Orowan strengthening caused by MgZn2phases with increasingthe number of MDF passes.
K. H. Loo,G. R. Zhu,Y. M. Lai,Chi K. Tse 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Direct methanol fuel cells (DMFC) have been widely researched for applications in portable electronics due to their use of liquid fuel for easy storage and transportation compared to gaseous hydrogen. However, DMFC’s performance is strongly affected by methanol crossover that significantly degrades the fuel conversion efficiency at low output power, and is characterized by an increasing efficiency at increasing output power. The maximum efficiency point (MEP) is inherently difficult to track due to the commonly unknown methanol crossover rate, but since it is typically located very close to the maximum power point (MPP), an alternative tracking approach based on the MPP is proposed. In this paper, a fuel-cell-oriented MPP tracking (MPPT) algorithm based on resistance matching is developed, implemented, and tested in the context of a DMFC/supercapacitor hybrid power system. To account for the generally slow fuel cell dynamics, the DMFC is constantly tracked at the MPP while any surplus or deficit power is absorbed or delivered by the supercapacitor bank. The detailed formulation of the algorithm and the power flow design and realization are also discussed.
KMT-2016-BLG-0212: First KMTNet-Only Discovery of a Substellar Companion
K.-H. Hwang,H.-W. Kim,D.-J. Kim,A. Gould,M. D. Albrow,S.-J. Chung,C. Han,Y. K. Jung,Y.-H. Ryu,I.-G. Shin,Y. Shvartzvald,J. C. Yee,W. Zang,W. Zhu,S.-M. Cha,S.-L. Kim,C.-U. Lee,D.-J. Lee,Y. Lee,B.-G. Pa 한국천문학회 2018 Journal of The Korean Astronomical Society Vol.51 No.6
We present the analysis of KMT-2016-BLG-0212, a low flux-variation $(I_{\rm flux-var}\sim 20$ mag) microlensing event, which is in a high-cadence ($\Gamma = 4 {\rm hr}^{-1}$) field of the three-telescope Korea Microlensing Telescope Network (KMTNet) survey. The event shows a short anomaly that is incompletely covered due to the brief visibility intervals that characterize the early microlensing season when the anomaly occurred. We show that the data are consistent with two classes of solutions, characterized respectively by low-mass brown-dwarf $(q=0.037)$ and sub-Neptune $(q<10^{-4})$ companions. Future high-resolution imaging should easily distinguish between these solutions.