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Analysis of strain rate sensitivity of ultrafine-grained AA1050 by stress relaxation test
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 45, Issue 12 , November 2014 , Pages 5442-5450 ; Akbarzadeh, A ; Kim, B. H ; Kim, S. K ; Sharif University of Technology
Abstract
Commercially pure aluminum sheets, AA 1050, are processed by accumulative roll bonding (ARB) up to eight cycles to achieve ultrafine-grained (UFG) aluminum as primary material for mechanical testing. Optical microscopy and electron backscattering diffraction analysis are used for microstructural analysis of the processed sheets. Strain rate sensitivity (m-value) of the specimens is measured over a wide range of strain rates by stress relaxation test under plane strain compression. It is shown that the flow stress activation volume is reduced by decrease of the grain size. This reduction which follows a linear relation for UFG specimens, is thought to enhance the required effective (or...
Precision measurement of a brown dwarf mass in a binary system in the microlensing event: OGLE-2019-BLG-0033/MOA-2019-BLG-035
, Article Astronomy and Astrophysics ; Volume 663 , 2022 ; 00046361 (ISSN) ; Udalski, A ; Bozza, V ; Rota, P ; Bond, I. A ; Yee, J. C ; Sajadian, S ; Mróz, P ; Poleski, R ; Skowron, J ; Szymanski, M. K ; Soszynski, I ; Pietrukowicz, P ; Kozlowski, S ; Ulaczyk, K ; Rybicki, K. A ; Iwanek, P ; Wrona, M ; Gromadzki, M ; Abe, F ; Barry, R ; Bennett, D. P ; Bhattacharya, A ; Fukui, A ; Fujii, H ; Hirao, Y ; Itow, Y ; Kirikawa, R ; Kondo, I ; Koshimoto, N ; Matsubara, Y ; Matsumoto, S ; Miyazaki, S ; Muraki, Y ; Olmschenk, G ; Ranc, C ; Okamura, A ; Rattenbury, N. J ; Satoh, Y ; Sumi, T ; Suzuki, D ; Silva, S. I ; Toda, T ; Tristram, P. J ; Vandorou, A ; Yama, H ; Beichman, C. A ; Bryden, G ; Novati, S. C ; Carey, S ; Gaudi, B. S ; Gould, A ; Henderson, C. B ; Johnson, S ; Shvartzvald, Y ; Zhu, W ; Dominik, M ; Hundertmark, M ; Jørgensen, U. G ; Longa-Peña, P ; Skottfelt, J ; Tregloan-Reed, J ; Bach-Møller, N ; Burgdorf, M ; D'Ago, G ; Haikala, L ; Hitchcock, J ; Khalouei, E ; Peixinho, N ; Rahvar, S ; Snodgrass, C ; Southworth, J ; Spyratos, P ; Zang, W ; Yang, H ; Mao, S ; Bachelet, E ; Maoz, D ; Street, R. A ; Tsapras, Y ; Christie, G. W ; Cooper, T ; De Almeida, L ; Do Nascimento, J.-D ; Green, J ; Han, C ; Hennerley, S ; Marmont, A ; McCormick, J ; Monard, L. A. G ; Natusch, T ; Pogge, R ; Sharif University of Technology
EDP Sciences
2022
Abstract
Context. Brown dwarfs are transition objects between stars and planets that are still poorly understood, for which several competing mechanisms have been proposed to describe their formation. Mass measurements are generally difficult to carry out for isolated objects as well as for brown dwarfs orbiting low-mass stars, which are often too faint for a spectroscopic follow-up. Aims. Microlensing provides an alternative tool for the discovery and investigation of such faint systems. Here, we present an analysis of the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035, which is caused by a binary system composed of a brown dwarf orbiting a red dwarf. Methods. Thanks to extensive ground...